WorldWideScience

Sample records for plant stirred-tank bioleaching

  1. Comparison of bioleaching of heavy metals from municipal sludge using indigenous sulfur and iron-oxidizing microorganisms: continuous stirred tank reactor studies.

    Science.gov (United States)

    Pathak, Ashish; Kothari, Richa; Dastidar, M G; Sreekrishnan, T R; Kim, Dong J

    2014-01-01

    A comparative study was undertaken using indigenous sulfur-oxidizing microorganisms and iron-oxidizing microorganisms in separate 12 litre continuous stirred tank reactors (CSTRs) for solubilization of heavy metals from anaerobically digested sewage sludge. The CSTRs were operated at hydraulic retention times (HRTs) ranging from 4 to 10 days using sewage sludge feed having near neutral pH. The pH, oxidation-reduction potential (ORP) and solubilization efficiency of metals were found to be highly dependent on HRT and an increase in HRT led to higher solubilization of metals in both the CSTRs. In both the CSTRs, the CSTR operated with sulfur-oxidizing microorganisms at an HRT of 8 days was found to be optimum in solubilizing 58% Cu, 52% Ni, 72% Zn and 43% Cu from the sludge. The nutrient value, nitrogen and phosphorus of bioleached sludge was also conserved (<20% loss) at 8 days HRT. The metals fractionation study conducted using BCR sequential extraction procedure suggested that most of the metals remaining in the bioleached sludge were in the more stable fractions (F3 and F4) and, therefore, can be safely apply as a fertilizer on land.

  2. Modelling of baffled stirred tanks

    Energy Technology Data Exchange (ETDEWEB)

    Ahlstedt, H.; Lahtinen, M. [Tampere Univ. of Technology (Finland). Energy and Process Engineering

    1996-12-31

    The three-dimensional flow field of a baffled stirred tank has been calculated using four different turbulence models. The tank is driven by a Rushton-type impeller. The boundary condition for the impeller region has been given as a source term or by calculating the impeller using the sliding mesh technique. Calculated values have been compared with measured data. (author)

  3. Optimization of lignin peroxidase production and stability by Phanerochaete chrysosporium using sewage-treatment-plant sludge as substrate in a stirred-tank bioreactor.

    Science.gov (United States)

    Alam, Md Zahangir; Mansor, Mariatul F; Jalal, K C A

    2009-05-01

    A laboratory-scale study was carried out to produce lignin peroxidase (ligninase) by white rot fungus (Phanerochaete chrysosporium) using sewage-treatment-plant (STP) sludge as the major substrate. The optimization was done using full-factorial design (FFD) with agitation and aeration as the two parameters. Nine experiments indicated by the FFD were fermented in a stirred-tank bioreactor for 3 days. A second-order quadratic model was developed using the regression analysis of the experimental results with the linear, quadratic, and interaction effects of the parameters. Analysis of variance (ANOVA) showed a high coefficient of determination (R (2)) value of 0.972, thus indicating a satisfactory fit of the quadratic model with the experimental data. Using statistical analysis, the optimum aeration and agitation rates were determined to be 2.0 vvm and 200 rpm, respectively, with a maximum activity of 225 U l(-1) in the first 3 days of fermentation. The validation experiment showed the maximum activity of lignin peroxidase was 744 U l(-1) after 5 days of fermentation. The results for the tests of the stability of lignin peroxidase showed that the activity was more than 80% of the maximum for the first 12 h of incubation at an optimum pH of 5 and temperature of 55 degrees C.

  4. Monoterpenoid oxindole alkaloid production by Uncaria tomentosa (Willd) D.C. cell suspension cultures in a stirred tank bioreactor.

    Science.gov (United States)

    Trejo-Tapia, Gabriela; Cerda-García-Rojas, Carlos M; Rodríguez-Monroy, Mario; Ramos-Valdivia, Ana C

    2005-01-01

    Cell growth, monoterpenoid oxindole alkaloid (MOA) production, and morphological properties of Uncaria tomentosa cell suspension cultures in a 2-L stirred tank bioreactor were investigated. U. tomentosa (cell line green Uth-3) was able to grow in a stirred tank at an impeller tip speed of 95 cm/s (agitation speed of 400 rpm), showing a maximum biomass yield of 11.9 +/- 0.6 g DW/L and a specific growth rate of 0.102 d(-1). U. tomentosa cells growing in a stirred tank achieved maximum volumetric and specific MOA concentration (467.7 +/- 40.0 microg/L, 44.6 +/- 5.2 microg/g DW) at 16 days of culture. MOA chemical profile of cell suspension cultures growing in a stirred tank resembled that of the plant. Depending on culture time, from the total MOA produced, 37-100% was found in the medium in the bioreactor culture. MOA concentration achieved in a stirred tank was up to 10-fold higher than that obtained in Erlenmeyer flasks (agitated at 110 rpm). In a stirred tank, average area of the single cells of U. tomentosa increased up to 4-fold, and elliptical form factor increased from 1.40 to 2.55, indicating enlargement of U. tomentosa single cells. This work presents the first report of U. tomentosa green cell suspension cultures that grow and produce MOA in a stirred tank bioreactor.

  5. Modified Mathematical Model For Neutralization System In Stirred Tank Reactor

    Directory of Open Access Journals (Sweden)

    Ahmmed Saadi Ibrehem

    2011-05-01

    Full Text Available A modified model for the neutralization process of Stirred Tank Reactors (CSTR reactor is presented in this study. The model accounts for the effect of strong acid [HCL] flowrate and strong base [NaOH] flowrate with the ionic concentrations of [Cl-] and [Na+] on the Ph of the system. In this work, the effect of important reactor parameters such as ionic concentrations and acid and base flowrates on the dynamic behavior of the CSTR is investigated and the behavior of mathematical model is compared with the reported models for the McAvoy model and Jutila model. Moreover, the results of the model are compared with the experimental data in terms of pH dynamic study. A good agreement is observed between our model prediction and the actual plant data. © 2011 BCREC UNDIP. All rights reserved(Received: 1st March 2011, Revised: 28th March 2011; Accepted: 7th April 2011[How to Cite: A.S. Ibrehem. (2011. Modified Mathematical Model For Neutralization System In Stirred Tank Reactor. Bulletin of Chemical Reaction Engineering & Catalysis, 6(1: 47-52. doi:10.9767/bcrec.6.1.825.47-52][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.1.825.47-52 || or local:  http://ejournal.undip.ac.id/index.php/bcrec/article/view/825 ] | View in 

  6. Phosphorus removal in aerated stirred tank reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ghigliazza, R.; Lodi, A.; Rovatti, M. [Inst. of Chemical and Process Engineering ``G.B. Bonino``, Univ. of Genoa (Italy)

    1999-03-01

    The possibility to obtain biological phosphorus removal in strictly aerobic conditions has been investigated. Experiments, carried out in a continuous stirred tank reactor (CSTR), show the feasibility to obtain phosphorus removal without the anaerobic phase. Reactor performance in terms of phosphorus abatement kept always higher then 65% depending on adopted sludge retention time (SRT). In fact increasing SRT from 5 days to 8 days phosphorus removal and reactor performance increase but overcoming this SRT value a decreasing in reactor efficiency was recorded. (orig.) With 6 figs., 3 tabs., 18 refs.

  7. Bio-processing of copper from combined smelter dust and flotation concentrate: A comparative study on the stirred tank and airlift reactors

    Energy Technology Data Exchange (ETDEWEB)

    Vakylabad, Ali Behrad, E-mail: alibehzad86@yahoo.co.uk [Department of Mining Engineering, Shahid Bahonar University, Kerman (Iran, Islamic Republic of); Engineers of Nano and Bio Advanced Sciences Company (ENBASCo.), ATIC, Mohaghegh University (Iran, Islamic Republic of); Schaffie, Mahin [Department of Chemical Engineering, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Mineral Industries Research Centre (MIRC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Ranjbar, Mohammad [Department of Mining Engineering, Shahid Bahonar University, Kerman (Iran, Islamic Republic of); Mineral Industries Research Centre (MIRC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Manafi, Zahra [Sarcheshmeh Copper Complex, National Iranian Copper Industry Company (Iran, Islamic Republic of); Darezereshki, Esmaeel [Mineral Industries Research Centre (MIRC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Energy and Environmental Engineering Research Center (EERC), Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of)

    2012-11-30

    Highlights: Black-Right-Pointing-Pointer Flotation concentrate and smelter dust were sampled and combined. Black-Right-Pointing-Pointer Copper bioleaching from the combined was investigated. Black-Right-Pointing-Pointer Two bio-reactors were investigated and optimized: stirred and airlift. Black-Right-Pointing-Pointer STRs had better technical conditions and situations for bacterial leaching. - Abstract: To scrutinize the influence of the design and type of the bioreactors on the bioleaching efficiency, the bioleaching were evaluated in a batch airlift and a batch stirred tank bioreactors with mixed mesophilic and mixed moderately thermophilic bacteria. According to the results, maximum copper recoveries were achieved using the cultures in the stirred tank bioreactors. It is worth noting that the main phase of the flotation concentrate was chalcopyrite (as a primary sulphide), but the smelter dust mainly contained secondary copper sulphides such as Cu{sub 2}S, CuS, and Cu{sub 5}FeS{sub 4}.Under optimum conditions, copper dissolution from the combined flotation concentrate and smelter dust (as an environmental hazard) reached 94.50% in the STR, and 88.02% in the airlift reactor with moderately thermophilic, after 23 days. Also, copper extractions calculated for the bioleaching using mesophilic bacteria were 48.73% and 37.19% in the STR (stirred tank reactor) and the airlift bioreactor, respectively. In addition, the SEM/EDS, XRD, chemical, and mineralogical analyses and studies confirmed the above results.

  8. Bio-processing of copper from combined smelter dust and flotation concentrate: a comparative study on the stirred tank and airlift reactors.

    Science.gov (United States)

    Vakylabad, Ali Behrad; Schaffie, Mahin; Ranjbar, Mohammad; Manafi, Zahra; Darezereshki, Esmaeel

    2012-11-30

    To scrutinize the influence of the design and type of the bioreactors on the bioleaching efficiency, the bioleaching were evaluated in a batch airlift and a batch stirred tank bioreactors with mixed mesophilic and mixed moderately thermophilic bacteria. According to the results, maximum copper recoveries were achieved using the cultures in the stirred tank bioreactors. It is worth noting that the main phase of the flotation concentrate was chalcopyrite (as a primary sulphide), but the smelter dust mainly contained secondary copper sulphides such as Cu(2)S, CuS, and Cu(5)FeS(4).Under optimum conditions, copper dissolution from the combined flotation concentrate and smelter dust (as an environmental hazard) reached 94.50% in the STR, and 88.02% in the airlift reactor with moderately thermophilic, after 23 days. Also, copper extractions calculated for the bioleaching using mesophilic bacteria were 48.73% and 37.19% in the STR (stirred tank reactor) and the airlift bioreactor, respectively. In addition, the SEM/EDS, XRD, chemical, and mineralogical analyses and studies confirmed the above results. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Impeller Submergence Depth for Stirred Tanks

    Directory of Open Access Journals (Sweden)

    Thiyam T. Devi

    2011-11-01

    Full Text Available Impeller submergence governs the performance of mixing tanks employed in oxygen transfer operation. Present work experimentally investigates the effect of impeller submergence depths on oxygen transfer and corresponding power consumption. It has been found that at higher range of impeller submergence, mixing tanks consume less power and gives higher values of oxygen transfer coefficient. Optimal range of submergence depth is 0.7 to 0.9 times the impeller diameter. Copyright ©2011 BCREC UNDIP. All rights reserved.(Received: 4th March 2011; Revised: 12nd July 2011; Accepted: 14th July 2011[How to Cite: T.T. Devi, A.P. Sinha, M. Thakre, and B. Kumar. (2011. Impeller Submergence Depth for Stirred Tanks. Bulletin of Chemical Reaction Engineering & Catalysis, 6 (2: 123-128. doi:10.9767/bcrec.6.2.826.123-128][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.2.826.123-128 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/826] | View in 

  10. CFD simulation of particle suspension in a stirred tank

    Institute of Scientific and Technical Information of China (English)

    Nana Qi; Hu Zhang; Kai Zhang; Gang Xu; Yongping Yang

    2013-01-01

    Particle suspension characteristics are predicted computationally in a stirred tank driven by a Smith turbine.In order to verify the hydrodynamic model and numerical method,the predicted power number and flow pattern are compared with designed values and simulated results from the literature,respectively.The effects of particle density,particle diameter,liquid viscosity and initial solid loading on particle suspension behavior are investigated by using the Eulerian-Eulerian two-fluid model and the standard k-ε turbulence model.The results indicate that solid concentration distribution depends on the flow field in the stirred tank.Higher particle density or larger particle size results in less homogenous distribution of solid particles in the tank.Increasing initial solid loading has an adverse impact on the homogeneous suspension of solid particles in a low-viscosity liquid,whilst more uniform particle distribution is found in a high-viscositv liauid.

  11. Numerical Simulation of Laminar Flow Field in a Stirred Tank

    Institute of Scientific and Technical Information of China (English)

    范茏; 王卫京; 杨超; 毛在砂

    2004-01-01

    Stirred tanks are used extensively in process industry and one of the most commonly used impellers in stirred tanks is the R.ushton disk turbine. Surprisingly few data are available regarding flow and mixing in stirred-tank reactors with Rushton turbine in the laminar regime, in particular the laminar flow in baffled tanks.In this paper, the laminar flow field in a baffled tank stirred by a standard R.ushton turbine is simulated with the improved inner-outer iterative method. The non-inertial coordinate system is used for the impeller region, which is in turn used as the boundary conditions for iteration. It is found that the simulation results are in good agreement with previous experiments. In addition, the flow number and impeller power number calculated from the simulated flow field are in satisfactory agreement with experimental data. This numerical method allows prediction of flow structure requiring no experimental data as the boundary conditions and has the potential of being used to scale-up and design of related process equipment.

  12. Biohydrogen production from waste bread in a continuous stirred tank reactor: A techno-economic analysis.

    Science.gov (United States)

    Han, Wei; Hu, Yun Yi; Li, Shi Yi; Li, Fei Fei; Tang, Jun Hong

    2016-12-01

    Biohydrogen production from waste bread in a continuous stirred tank reactor (CSTR) was techno-economically assessed. The treating capacity of the H2-producing plant was assumed to be 2 ton waste bread per day with lifetime of 10years. Aspen Plus was used to simulate the mass and energy balance of the plant. The total capital investment (TCI), total annual production cost (TAPC) and annual revenue of the plant were USD931020, USD299746/year and USD639920/year, respectively. The unit hydrogen production cost was USD1.34/m(3) H2 (or USD14.89/kg H2). The payback period and net present value (NPV) of the plant were 4.8years and USD1266654, respectively. Hydrogen price and operators cost were the most important variables on the NPV. It was concluded that biohydrogen production from waste bread in the CSTR was feasible for practical application. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Adaptive Controller Design for Continuous Stirred Tank Reactor

    Directory of Open Access Journals (Sweden)

    K. Prabhu

    2014-09-01

    Full Text Available Continues Stirred Tank Reactor (CSTR is an important issue in chemical process and a wide range of research in the area of chemical engineering. Temperature Control of CSTR has been an issue in the chemical control engineering since it has highly non-linear complex equations. This study presents problem of temperature control of CSTR with the adaptive Controller. The Simulation is done in MATLAB and result shows that adaptive controller is an efficient controller for temperature control of CSTR than PID controller.

  14. Design of Controllers for Continuous Stirred Tank Reactor

    Directory of Open Access Journals (Sweden)

    Somasundaram Deepa

    2015-02-01

    Full Text Available The objective of the project is to design various controllers for temperature control in Continuous Stirred Tank Reactor (CSTR systems. Initially Zeigler-Nichols, modified Zeigler-Nichols, Tyreus-Luyben, Shen-Yu and IMC based method of tuned Proportional Integral (PI controller is designed and comparisons are made with Fuzzy Logic Controller. Simulations are carried out and responses are obtained for the above controllers. Maximum peak overshoot, Settling time, Rise time,  ISE, IAE  are chosen as performance index. From the analysis it is found that the Fuzzy Logic Controller  is a promising controller than the conventional controllers.

  15. Fluid dynamic analysis of a continuous stirred tank reactor for technical optimization of wastewater digestion.

    Science.gov (United States)

    Hurtado, F J; Kaiser, A S; Zamora, B

    2015-03-15

    Continuous stirred tank reactors (CSTR) are widely used in wastewater treatment plants to reduce the organic matter and microorganism present in sludge by anaerobic digestion. The present study carries out a numerical analysis of the fluid dynamic behaviour of a CSTR in order to optimize the process energetically. The characterization of the sludge flow inside the digester tank, the residence time distribution and the active volume of the reactor under different criteria are determined. The effects of design and power of the mixing system on the active volume of the CSTR are analyzed. The numerical model is solved under non-steady conditions by examining the evolution of the flow during the stop and restart of the mixing system. An intermittent regime of the mixing system, which kept the active volume between 94% and 99%, is achieved. The results obtained can lead to the eventual energy optimization of the mixing system of the CSTR.

  16. Nonlinear versus Ordinary Adaptive Control of Continuous Stirred-Tank Reactor

    Science.gov (United States)

    Vojtesek, Jiri; Dostal, Petr

    2015-01-01

    Unfortunately, the major group of the systems in industry has nonlinear behavior and control of such processes with conventional control approaches with fixed parameters causes problems and suboptimal or unstable control results. An adaptive control is one way to how we can cope with nonlinearity of the system. This contribution compares classic adaptive control and its modification with Wiener system. This configuration divides nonlinear controller into the dynamic linear part and the static nonlinear part. The dynamic linear part is constructed with the use of polynomial synthesis together with the pole-placement method and the spectral factorization. The static nonlinear part uses static analysis of the controlled plant for introducing the mathematical nonlinear description of the relation between the controlled output and the change of the control input. Proposed controller is tested by the simulations on the mathematical model of the continuous stirred-tank reactor with cooling in the jacket as a typical nonlinear system. PMID:26346878

  17. Artificial Neural Networks Based Modeling and Control of Continuous Stirred Tank Reactor

    Directory of Open Access Journals (Sweden)

    R. S.M.N. Malar

    2009-01-01

    Full Text Available Continuous Stirred Tank Reactor (CSTR is one of the common reactors in chemical plant. Problem statement: Developing a model incorporating the nonlinear dynamics of the system warrants lot of computation. An efficient control of the product concentration can be achieved only through accurate model. Approach: In this study, attempts were made to alleviate the above mentioned problem using “Artificial Intelligence” (AI techniques. One of the AI techniques namely Artificial Neural Networks (ANN was used to model the CSTR incorporating its non-linear characteristics. Two nonlinear models based control strategies namely internal model control and direct inverse control were designed using the neural networks and applied to the control of isothermal CSTR. Results: The simulation results for the above control schemes with set point tracking were presented. Conclusion: Results indicated that neural networks can learn accurate models and give good non-linear control when model equations are not known.

  18. A cubic autocatalytic reaction in a continuous stirred tank reactor

    Energy Technology Data Exchange (ETDEWEB)

    Yakubu, Aisha Aliyu; Yatim, Yazariah Mohd [School of Mathematical Sciences, Universiti Sains Malaysia, 11800 USM, Penang Malaysia (Malaysia)

    2015-10-22

    In the present study, the dynamics of the cubic autocatalytic reaction model in a continuous stirred tank reactor with linear autocatalyst decay is studied. This model describes the behavior of two chemicals (reactant and autocatalyst) flowing into the tank reactor. The behavior of the model is studied analytically and numerically. The steady state solutions are obtained for two cases, i.e. with the presence of an autocatalyst and its absence in the inflow. In the case with an autocatalyst, the model has a stable steady state. While in the case without an autocatalyst, the model exhibits three steady states, where one of the steady state is stable, the second is a saddle point while the last is spiral node. The last steady state losses stability through Hopf bifurcation and the location is determined. The physical interpretations of the results are also presented.

  19. Improving heat transfer in stirred tanks cooled by helical coils

    Directory of Open Access Journals (Sweden)

    S.M.C.P. Pedrosa

    2003-06-01

    Full Text Available Stirred Tank Reactors are extensively used in chemical industries. When they are used for highly exothermic reactions, jackets or coils are employed for heat removal. Internal coils can be either helical or axial and they considerably affect the flow inside the reactor because they impose an additional resistance to flow circulation. The aim of this work is to show that the design of vessels cooled by helical coils can be further improved. The design of these reactors follows very much the geometry proposed by Oldshue and Gretton (1954, and some minor modifications in the coil arrangements are likely to improve internal circulation inside these vessels mainly in the region between coils and wall of the vessel. Results show a gain in performance when small alterations are made specially in the shape of the coil arrangement.

  20. Implementation of Neural Control for Continuous Stirred Tank Reactor (CSTR

    Directory of Open Access Journals (Sweden)

    Karima M. Putrus

    2011-01-01

    Full Text Available In this paper a dynamic behavior and control of a jacketed continuous stirred tank reactor (CSTR is developed using different control strategies, conventional feedback control (PI and PID, and neural network (NARMA-L2, and NN Predictive control. The dynamic model for CSTR process is described by a first order lag system with dead time.The optimum tuning of control parameters are found by two different methods; Frequency Analysis Curve method (Bode diagram and Process Reaction Curve using the mean of Square Error (MSE method. It is found that the Process Reaction Curve method is better than the Frequency Analysis Curve method and PID feedback controller is better than PI feedback controller. The results show that the artificial neural network is the best method to control the CSTR process and it is better than the conventional method because it has smaller value of mean square error (MSE. MATLAB program is used as a tool of solution for all cases used in the present work.

  1. Energy-efficient stirred-tank photobioreactors for simultaneous carbon capture and municipal wastewater treatment.

    Science.gov (United States)

    Mohammed, K; Ahammad, S Z; Sallis, P J; Mota, C R

    2014-01-01

    Algal based wastewater treatment (WWT) technologies are attracting renewed attention because they couple energy-efficient sustainable treatment with carbon capture, and reduce the carbon footprint of the process. A low-cost energy-efficient mixed microalgal culture-based pilot WWT system, coupled with carbon dioxide (CO2) sequestration, was investigated. The 21 L stirred-tank photobioreactors (STPBR) used light-emitting diodes as the light source, resulting in substantially reduced operational costs. The STPBR were operated at average optimal light intensity of 582.7 μmol.s(-1).m(-2), treating synthetic municipal wastewater containing approximately 250, 90 and 10 mg.L(-1) of soluble chemical oxygen demand (SCOD), ammonium (NH4-N), and phosphate, respectively. The STPBR were maintained for 64 days without oxygen supplementation, but had a supply of CO2 (25 mL.min(-1), 25% v/v in N2). Relatively high SCOD removal efficiency (>70%) was achieved in all STPBR. Low operational cost was achieved by eliminating the need for mechanical aeration, with microalgal photosynthesis providing all oxygenation. The STPBR achieved an energy saving of up to 95%, compared to the conventional AS system. This study demonstrates that microalgal photobioreactors can provide effective WWT and carbon capture, simultaneously, in a system with potential for scaling-up to municipal WWT plants.

  2. Mass transfer and power characteristics of stirred tank with Rushton and curved blade impeller

    Directory of Open Access Journals (Sweden)

    Thiyam Tamphasana Devi

    2017-04-01

    Full Text Available Present work compares the mass transfer coefficient (kLa and power draw capability of stirred tank employed with Rushton and curved blade impeller using computational fluid dynamics (CFD techniques in single and double impeller cases. Comparative analysis for different boundary conditions and mass transfer model has been done to assess their suitability. The predicted local kLa has been found higher in curved blade impeller than the Rushton impeller, whereas stirred tank with double impeller does not show variation due to low superficial gas velocity. The global kLa predicted has been found higher in curved blade impeller than the Rushton impeller in double and single cases. Curved blade impeller also exhibits higher power draw capability than the Rushton impeller. Overall, stirred tank with curved blade impeller gives higher efficiency in both single and double cases than the Rushton turbine

  3. CFD simulation of flow patterns in unbaffled stirred tank with CD-6 impeller

    Directory of Open Access Journals (Sweden)

    Devi Tamphasana Thiyam

    2012-01-01

    Full Text Available Understanding the flow in stirred vessels can be useful for a wide number of industrial applications. There is a wealth of numerical simulations of stirring vessels with standard impeller such as Rushton turbine and pitch blade turbine. Here, a CFD study has been performed to observe the spatial variations (angular, axial and radial of hydrodynamics (velocity and turbulence field in unbaffled stirred tank with Concave-bladed Disc turbine (CD-6 impeller. Three speeds (N=296, 638 & 844.6 rpm have been considered for this study. The angular variations of hydrodynamics of stirred tank were found very less as compared to axial and radial variations.

  4. Numerical Simulation of Gas—Liquid Flow in a Stirred Tank with a Rushton Impeller

    Institute of Scientific and Technical Information of China (English)

    WANGWeijing; MAOZaisha

    2002-01-01

    The gas-liquid flow field in a stirred tank with a Rushton disk turbine,including the impeller region,was numerically simulated using the improved inner-outer iterative procedure.The characteristic features of the strirred tank,such as gas cavity and accumulation of gas at the two sides of wall baffles,can be captured by the simulation.The simulated results agree well with available experimental data.Since the improved inner-outer iterative algorithm demands no empirical formula and experimental data for the impeller region,and the approach seems generally applicable for simulating gas-liquid stirred tanks.

  5. Bioleaching of zinc and iron from steel plant waste using Acidithiobacillus ferrooxidans.

    Science.gov (United States)

    Bayat, Oktay; Sever, Efsun; Bayat, Belgin; Arslan, Volkan; Poole, Colin

    2009-01-01

    The bacterial leaching of zinc and iron from solid wastes at the Isdemir iron and steel plant has been investigated using Acidithiobacillus ferrooxidans as the bacterial agent. The effects of a range of operational parameters, including particle size, solids concentration and pH, on the efficiency of the bioleaching process were investigated. In each test, several variables were determined to assess the efficiency of leaching, including slurry pH and redox potential, temperature, bacteria population and concentrations of zinc and iron in solution. Experimental results demonstrated that pulp solids concentration, slurry pH and solids particle size were all important parameters in the bacterial leaching process. Maximum extraction was achieved at pH values around 1.3 and a solids concentration of 1% w/v, with 35% of the Zn content and 37% of the Fe being dissolved.

  6. Chaotic behavior in the dynamical system of a continuous stirred tank reactor

    Science.gov (United States)

    Retzloff, D. G.; Chan, P. C.-H.; Chicone, C.; Offin, D.; Mohamed, R.

    1987-03-01

    The dynamical system describing a continuous stirred tank reactor (CSTR) for the reactions A→B→C and A→C, B→D is considered. A circulating attractor with accompanying circulating orbits is shown to exist when the critical point of the system is unique and unstable. The orbit structure has been numerically found to consist of periodic orbits and chaotic behavior.

  7. A Colorful Mixing Experiment in a Stirred Tank Using Non-Newtonian Blue Maize Flour Suspensions

    Science.gov (United States)

    Trujilo-de Santiago, Grissel; Rojas-de Gante, Cecillia; García-Lara, Silverio; Ballesca´-Estrada, Adriana; Alvarez, Marion Moise´s

    2014-01-01

    A simple experiment designed to study mixing of a material of complex rheology in a stirred tank is described. Non-Newtonian suspensions of blue maize flour that naturally contain anthocyanins have been chosen as a model fluid. These anthocyanins act as a native, wide spectrum pH indicator exhibiting greenish colors in alkaline environments, blue…

  8. Gas Hold-Up in Stirred Tank Reactors in the Presence of Inorganic Electrolytes

    NARCIS (Netherlands)

    Yawalkar, Archis A.; Heesink, Albertus B.M.; Versteeg, Geert F.; Pangarkar, Vishwas G.

    2002-01-01

    Gas hold-up (εG) in air–aqueous electrolyte solutions in stirred tank reactors (STR) is correlated using a relative gas dispersion parameter, N/Ncd and a surface tension factor (STF), (c/z)(dσ/dc)^2. For electrolyte concentration below transition concentration (ct) a single correlation in the form o

  9. Mechanism of Off—Bottom Suspension of Solid Particles in a Mechanical Stirred Tank

    Institute of Scientific and Technical Information of China (English)

    BAOYuyun; HUANGXiongbin; 等

    2002-01-01

    The minimum fluid velocity to maintain particles just suspended was deduced,and the theoretical analysis shows that the minimum velocity is influenced by the properties of the solid and liquid,not by the operational conditions. For justification,the local minimum velocity at the bottom of the tank was measured by a bi-electrode conductivity probe,in a square-sectioned stirred tank (0.75m×0.75m×1.0m) with the glass beads-water system. The experiments showed that the fluid velocities for the same suspension state were identical despite that the power dissipated per unit mass was not the same under different configuration and operation.Both theoretical analysis and experimental results indicate that the off-bottom suspension is controlled by the local fluid flow over the bottom of the stirred tank.

  10. Perancangan Sistem Pemantauan Pengendali Suhu pada Stirred Tank Heater menggunakan Supervisory Control and Data Acquisition (SCADA

    Directory of Open Access Journals (Sweden)

    Ike Bayusari

    2013-04-01

    Full Text Available This paper discusses design of a suhue control monitoring system in stirred tank heater system that has an important function in industrial processes. Monitoring of suhue control system in stirred tank heater is designed using Supervisory Control and Data Acquisition (SCADA that control function of industrial processes. While the actuator to be controlled is the position of burner openings, so that the heat can be adjusted to meet a predetermined set-point. The suhue controller that is also used as a Remote Terminal Unit (RTU is Programmable Logic Controller (PLC. The testing result showed on SCADA system was quite good, where the average percentage of deviation for testing of set-point data was 0.76687%, and the percentage of deviation for testing of suhue data was 0.082%.

  11. Experimental Study on Scale-Up of Solid-Liquid Stirred Tank with an Intermig Impeller

    Science.gov (United States)

    Zhao, Hongliang; Zhao, Xing; Zhang, Lifeng; Yin, Pan

    2017-02-01

    The scale-up of a solid-liquid stirred tank with an Intermig impeller was characterized via experiments. Solid concentration, impeller just-off-bottom speed and power consumption were measured in stirred tanks of different scales. The scale-up criteria for achieving the same effect of solid suspension in small-scale and large-scale vessels were evaluated. The solids distribution improves if the operating conditions are held constant as the tank is scaled-up. The results of impeller just-off-bottom speed gave X = 0.868 in the scale-up relationship ND X = constant. Based on this criterion, the stirring power per unit volume obviously decreased at N = N js, and the power number ( N P) was approximately equal to 0.3 when the solids are uniformly distributed in the vessels.

  12. Selective precipitation of Cu from Zn in a pS controlled continuously stirred tank reactor

    NARCIS (Netherlands)

    Sampaio, R.M.; Timmers, R.A.; Xu, Y.; Keesman, K.J.; Lens, P.N.L.

    2009-01-01

    Copper was continuously and selectively precipitated with Na2S to concentrations below 0.3 ppb from water containing around 600 ppm of both Cu and Zn in a Continuously Stirred Tank Reactor. The pH was controlled at 3 and the pS at 25 (pS = ¿log(S2¿)) by means of an Ag2S sulfide selective electrode.

  13. Bistability in an uncatalyzed bromate oscillator in a continuously fed stirred tank reactor

    Science.gov (United States)

    Dutt, Arun K.; Müller, S. C.

    1996-01-01

    Uncatalyzed gallic acid oscillating system has been investigated in a continuously fed stirred tank reactor (CSTR). In the [Bromate]0-[Bromide]0 concentration space, a region has been located where a bistability is observed between an oscillatory branch and a flow branch. To our knowledge this is the first evidence of bistability in an uncatalyzed bromate oscillator. Some observations have been explained in terms of the skeleton mechanism proposed in the past.

  14. Continuous production of diatom Entomoneis sp. in mechanically stirred tank and flat-panel airlift photobioreactors.

    Science.gov (United States)

    Viriyayingsiri, Thunyaporn; Sittplangkoon, Pantaporn; Powtongsook, Sorawit; Nootong, Kasidit

    2016-10-02

    Continuous production of diatom Entomonies sp. was performed in mechanically stirred tank and flat-panel airlift photobioreactors (FPAP). The maximum specific growth rate of diatom from the batch experiment was 0.98 d(-1). A series of dilution rate and macronutrient concentration adjustments were performed in a stirred tank photobioreactor and found that the dilution rate ranged from 0.7 to 0.8 d(-1) and modified F/2 growth media containing nitrate at 3.09 mg N/L, phosphate at 2.24 mg P/L, and silicate at 11.91 mg Si/L yielded the maximum cell number density. Finally, the continuous cultivation of Entomonies sp. was conducted in FPAP using the optimal conditions determined earlier, resulting in the maximum cell number density of 19.69 × 10(4) cells/mL, which was approximately 47 and 73% increase from the result using the stirred tank photobioreactor fed with modified and standard F/2 growth media, respectively.

  15. High cell density cultivation of recombinant yeasts and bacteria under non-pressurized and pressurized conditions in stirred tank bioreactors.

    Science.gov (United States)

    Knoll, Arnd; Bartsch, Stefan; Husemann, Bernward; Engel, Philip; Schroer, Kirsten; Ribeiro, Betina; Stöckmann, Christoph; Seletzky, Juri; Büchs, Jochen

    2007-10-31

    This study demonstrates the applicability of pressurized stirred tank bioreactors for oxygen transfer enhancement in aerobic cultivation processes. The specific power input and the reactor pressure was employed as process variable. As model organism Escherichia coli, Arxula adeninivorans, Saccharomyces cerevisiae and Corynebacterium glutamicum were cultivated to high cell densities. By applying specific power inputs of approx. 48kWm(-3) the oxygen transfer rate of a E. coli culture in the non-pressurized stirred tank bioreactor was lifted up to values of 0.51moll(-1)h(-1). When a reactor pressure up to 10bar was applied, the oxygen transfer rate of a pressurized stirred tank bioreactor was lifted up to values of 0.89moll(-1)h(-1). The non-pressurized stirred tank bioreactor was able to support non-oxygen limited growth of cell densities of more than 40gl(-1) cell dry weight (CDW) of E. coli, whereas the pressurized stirred tank bioreactor was able to support non-oxygen limited growth of cell densities up to 225gl(-1) CDW of A. adeninivorans, 89gl(-1) CDW of S. cerevisiae, 226gl(-1) CDW of C. glutamicum and 110gl(-1) CDW of E. coli. Compared to literature data, some of these cell densities are the highest values ever achieved in high cell density cultivation of microorganisms in stirred tank bioreactors. By comparing the specific power inputs as well as the k(L)a values of both systems, it is demonstrated that only the pressure is a scaleable tool for oxygen transfer enhancement in industrial stirred tank bioreactors. Furthermore, it was shown that increased carbon dioxide partial pressures did not remarkably inhibit the growth of the investigated model organisms.

  16. A new microfluidic concept for parallel operated milliliter-scale stirred tank bioreactors.

    Science.gov (United States)

    Gebhardt, Gabi; Hortsch, Ralf; Kaufmann, Klaus; Arnold, Matthias; Weuster-Botz, Dirk

    2011-01-01

    Parallel miniaturized stirred tank bioreactors are an efficient tool for "high-throughput bioprocess design." As most industrial bioprocesses are pH-controlled and/or are operated in a fed-batch mode, an exact scale-down of these reactions with continuous dosing of fluids into the miniaturized bioreactors is highly desirable. Here, we present the development, characterization, and application of a novel concept for a highly integrated microfluidic device for a bioreaction block with 48 parallel milliliter-scale stirred tank reactors (V = 12 mL). The device consists of an autoclavable fluidic section to dispense up to three liquids individually per reactor. The fluidic section contains 144 membrane pumps, which are magnetically driven by a clamped-on actuator section. The micropumps are designed to dose 1.6 μL per pump lift. Each micropump enables a continuous addition of liquid with a flow rate of up to 3 mL h(-1) . Viscous liquids up to a viscosity of 8.2 mPa s (corresponds to a 60% v/v glycerine solution) can be pumped without changes in the flow rates. Thus, nearly all feeding solutions can be delivered, which are commonly used in bioprocesses. The functionality of the first prototype of this microfluidic device was demonstrated by double-sided pH-controlled cultivations of Saccharomyces cerevisiae based on signals of fluorimetric sensors embedded at the bottom of the bioreactors. Furthermore, fed-batch cultivations with constant and exponential feeding profiles were successfully performed. Thus, the presented novel microfluidic device will be a useful tool for parallel and, thus, efficient optimization of controlled fed-batch bioprocesses in small-scale stirred tank bioreactors. This can help to reduce bioprocess development times drastically.

  17. MODELLING AND CONTROL OF CONTINUOUS STIRRED TANK REACTOR WITH PID CONTROLLER

    Directory of Open Access Journals (Sweden)

    Artur Wodołażski

    2016-09-01

    Full Text Available This paper presents a model of dynamics control for continuous stirred tank reactor (CSTR in methanol synthesis in a three-phase system. The reactor simulation was carried out for steady and transient state. Efficiency ratio to achieve maximum performance of the product per reactor unit volume was calculated. Reactor dynamics simulation in closed loop allowed to received data for tuning PID controller (proportional-integral-derivative. The results of the regulation process allow to receive data for optimum reactor production capacity, along with local hot spots eliminations or temperature runaway.

  18. LARGE EDDY SIMULATIONS OF THE TURBULENT FLOW IN A STIRRED TANK

    DEFF Research Database (Denmark)

    Fan, Jianhua; Wang, Yundong; Fei, Weiyang

    2005-01-01

    Computational fluid dynamics (CFD) simulations of the fluid flow in a baffled, stirred tank with a single Rushton turbine are performed. The simulations are carried out on the “Shengcao-21C” supercomputer via commercial CFD software CFX5, using k-ε and large eddy simulation (LES) turbulence model...... respectively. Results show that CFD simulations using k-ε and LES model agree well with DPIV measurements. From the LES simulation, the velocity fluctuation is shown to occur with the development of vortices and eddies. This shows that LES simulation is better than k-ε simulation, although it demands a lot...

  19. LARGE EDDY SIMULATIONS OF THE TURBULENT FLOW IN A STIRRED TANK

    DEFF Research Database (Denmark)

    Fan, Jianhua; Wang, Yundong; Fei, Weiyang

    Computational fluid dynamics (CFD) simulations of the fluid flow in a baffled, stirred tank with a single Rushton turbine are performed. The simulations are carried out on the “Shengcao-21C” supercomputer via commercial CFD software CFX5, using k-ε and large eddy simulation (LES) turbulence model...... respectively. Results show that CFD simulations using k-ε and LES model agree well with DPIV measurements. From the LES simulation, the velocity fluctuation is shown to occur with the development of vortices and eddies. This shows that LES simulation is better than k-ε simulation, although it demands a lot...

  20. Absorption of NO2 into Na2S solution in a stirred tank reactor

    Institute of Scientific and Technical Information of China (English)

    Xiang GAO; Rui-tang GUO; Hong-lei DING; Zhong-yang LUO; Ke-fa CEN

    2009-01-01

    To understand the absorption mechanism of nitrogen dioxide into a sodium sulfide solution, a stirred tank reactor with a plane gas-liquid interface was used to measure the chemical absorption rate of diluted nitrogen dioxide into sodium sulfide solution. The absorption rates under various experimental conditions were measured and the effects of experimental conditions on nitrogen dioxide absorption rate were discussed. The results show that, in the range of this study, nitrogen dioxide absorption rate increases with increasing sodium sulfide concentration, nitrogen dioxide inlet concentration, and flue gas flow rate, but decreases with increasing reaction temperature and oxygen content in flue gas.

  1. Development of Linearizing Feedback Control with a Variable Structure Observer for Continuous Stirred Tank Reactors

    Institute of Scientific and Technical Information of China (English)

    Bachir Daaou; Abdellah Mansouri; Mohamed Bouhamida; Mohammed Chenafa

    2012-01-01

    This paper deals with the design of an observer-based nonlinear control for continuous stirred tank reactors (CSTR). A variable structure observer is constructed to estimate the whole process state variables. This observer is basically the conventional Luenberger observer with an additional switching term used to guarantee the robustness against modeling errors. The observer is coupled with a nonlinear controller, designed based on input-output linearization for controlling the reactor temperature. The asymptotical stability of the closed-loop system is shown by the Lyapunov stability theorem. Finally, computer simulations are developed for showing the performance of the proposed approach.

  2. Fungal leaching of valuable metals from a power plant residual ash using Penicillium simplicissimum: Evaluation of thermal pretreatment and different bioleaching methods.

    Science.gov (United States)

    Rasoulnia, P; Mousavi, S M; Rastegar, S O; Azargoshasb, H

    2016-06-01

    Each year a tremendous volume of V-Ni rich ashes is produced by fuel oil consuming power plants throughout the world. Recovery of precious metals existing in these ashes is very important from both economic and environmental aspects. The present research was aimed at investigating bioleaching potential of Penicillium simplicissimum for the recovery of metals from power plant residual ash (PPR ash) using different bioleaching methods such as one-step, two-step, and spent-medium bioleaching at 1% (w/v) pulp density. Furthermore, the effects of thermal pretreatment on leaching of V, Ni, and Fe, as major elements present in PPR ash, were studied. Thermal pretreatment at various temperatures removed the carbonaceous and volatile fraction of the ash and affected the fungal growth and metal leachability. The highest extraction yields of V and Ni were achieved for the original PPR ash, using spent-medium bioleaching in which nearly 100% of V and 40% of Ni were extracted. The maximum extraction yield of Fe (48.3%) was obtained for the pretreated PPR ash at 400°C by spent-medium bioleaching. In addition, the fungal growth in pure culture was investigated through measurement of produced organic acids via high performance liquid chromatography (HPLC). Chemical leaching experiments were performed, using commercial organic acids at the same concentrations as those produced under optimum condition of fungal growth (5237ppm citric, 3666ppm gluconic, 1287ppm oxalic and 188ppm malic acid). It was found that in comparison to chemical leaching, bioleaching improved V and Ni recovery up to 19% and 12%, respectively. Moreover, changes in physical and chemical properties as well as morphology of the samples utilizing appropriate analytical methods such as XRF, XRD, FTIR, and FE-SEM were comprehensively investigated.

  3. Biohydrogen and Bioethanol Production from Biodiesel-Based Glycerol by Enterobacter aerogenes in a Continuous Stir Tank Reactor.

    Science.gov (United States)

    Jitrwung, Rujira; Yargeau, Viviane

    2015-05-11

    Crude glycerol from the biodiesel manufacturing process is being produced in increasing quantities due to the expanding number of biodiesel plants. It has been previously shown that, in batch mode, semi-anaerobic fermentation of crude glycerol by Enterobacter aerogenes can produce biohydrogen and bioethanol simultaneously. The present study demonstrated the possible scaling-up of this process from small batches performed in small bottles to a 3.6-L continuous stir tank reactor (CSTR). Fresh feed rate, liquid recycling, pH, mixing speed, glycerol concentration, and waste recycling were optimized for biohydrogen and bioethanol production. Results confirmed that E. aerogenes uses small amounts of oxygen under semi-anaerobic conditions for growth before using oxygen from decomposable salts, mainly NH4NO3, under anaerobic condition to produce hydrogen and ethanol. The optimal conditions were determined to be 500 rpm, pH 6.4, 18.5 g/L crude glycerol (15 g/L glycerol) and 33% liquid recycling for a fresh feed rate of 0.44 mL/min. Using these optimized conditions, the process ran at a lower media cost than previous studies, was stable after 7 days without further inoculation and resulted in yields of 0.86 mol H2/mol glycerol and 0.75 mol ethanol/mole glycerol.

  4. Biohydrogen and Bioethanol Production from Biodiesel-Based Glycerol by Enterobacter aerogenes in a Continuous Stir Tank Reactor

    Directory of Open Access Journals (Sweden)

    Rujira Jitrwung

    2015-05-01

    Full Text Available Crude glycerol from the biodiesel manufacturing process is being produced in increasing quantities due to the expanding number of biodiesel plants. It has been previously shown that, in batch mode, semi-anaerobic fermentation of crude glycerol by Enterobacter aerogenes can produce biohydrogen and bioethanol simultaneously. The present study demonstrated the possible scaling-up of this process from small batches performed in small bottles to a 3.6-L continuous stir tank reactor (CSTR. Fresh feed rate, liquid recycling, pH, mixing speed, glycerol concentration, and waste recycling were optimized for biohydrogen and bioethanol production. Results confirmed that E. aerogenes uses small amounts of oxygen under semi-anaerobic conditions for growth before using oxygen from decomposable salts, mainly NH4NO3, under anaerobic condition to produce hydrogen and ethanol. The optimal conditions were determined to be 500 rpm, pH 6.4, 18.5 g/L crude glycerol (15 g/L glycerol and 33% liquid recycling for a fresh feed rate of 0.44 mL/min. Using these optimized conditions, the process ran at a lower media cost than previous studies, was stable after 7 days without further inoculation and resulted in yields of 0.86 mol H2/mol glycerol and 0.75 mol ethanol/mole glycerol.

  5. CFD SIMULATION OF THE HYDRODYNAMICS AND MIXING TIME IN A STIRRED TANK

    Directory of Open Access Journals (Sweden)

    AOYI OCHIENG

    2010-12-01

    Full Text Available Hydrodynamics and mixing efficiency in stirred tanks influence power draw and are therefore important for the design of many industrial processes. In the present study, both experimental and simulation methods were employed to determine the flow fields in different mixing tank configurations in a single phase system. Laser Doppler velocimetry (LDV and computational fluid dynamics (CFD techniques were used to determine the flow fields in systems with and without a draft tube. There was reasonable agreement between the simulation and experimental results. It was shown that the use of a draft tube with a Rushton turbine and hydrofoil impeller resulted in a reduction in the homogenization energy by 19.2 and 17.7%, respectively. This indicates that a reduction in the operating cost can be achieved with the use of a draft tube in a stirred tank and there would be a greater cost reduction in a system stirred by the Rushton turbine compared to that stirred by a propeller.

  6. A simple eccentric stirred tank mini-bioreactor: mixing characterization and mammalian cell culture experiments.

    Science.gov (United States)

    Bulnes-Abundis, David; Carrillo-Cocom, Leydi M; Aráiz-Hernández, Diana; García-Ulloa, Alfonso; Granados-Pastor, Marisa; Sánchez-Arreola, Pamela B; Murugappan, Gayathree; Alvarez, Mario M

    2013-04-01

    In industrial practice, stirred tank bioreactors are the most common mammalian cell culture platform. However, research and screening protocols at the laboratory scale (i.e., 5-100 mL) rely primarily on Petri dishes, culture bottles, or Erlenmeyer flasks. There is a clear need for simple-easy to assemble, easy to use, easy to clean-cell culture mini-bioreactors for lab-scale and/or screening applications. Here, we study the mixing performance and culture adequacy of a 30 mL eccentric stirred tank mini-bioreactor. A detailed mixing characterization of the proposed bioreactor is presented. Laser induced fluorescence (LIF) experiments and computational fluid dynamics (CFD) computations are used to identify the operational conditions required for adequate mixing. Mammalian cell culture experiments were conducted with two different cell models. The specific growth rate and the maximum cell density of Chinese hamster ovary (CHO) cell cultures grown in the mini-bioreactor were comparable to those observed for 6-well culture plates, Erlenmeyer flasks, and 1 L fully instrumented bioreactors. Human hematopoietic stem cells were successfully expanded tenfold in suspension conditions using the eccentric mini-bioreactor system. Our results demonstrate good mixing performance and suggest the practicality and adequacy of the proposed mini-bioreactor.

  7. Mass Transfer Coefficientin Stirred Tank for p-Cresol Extraction Process from Coal Tar

    Science.gov (United States)

    Fardhyanti, D. S.; Tyaningsih, D. S.; Afifah, S. N.

    2017-04-01

    Indonesia is a country that has a lot of coal resources. The Indonesian coal has a low caloric value. Pyrolysis is one of the process to increase the caloric value. One of the by-product of the pyrolysis process is coal tar. It contains a lot of aliphatic or aromatic compounds such asp-cresol (11% v/v). It is widely used as a disinfectant. Extractionof p-Cresol increases the economic value of waste of coal. The aim of this research isto study about mass tranfer coefficient in the baffled stirred tank for p-Cresolextraction from coal tar. Mass transfer coefficient is useful for design and scale up of industrial equipment. Extraction is conducted inthe baffled stirred tank equipped with a four-bladed axial impeller placed vertically in the vessel. Sample for each time processing (5, 10, 15, 20, 25 and 30minutes) was poured into a separating funnel, settled for an hour and separated into two phases. Then the two phases were weighed. The extract phases and raffinate phases were analyzed by Spectronic UV-Vis. The result showed that mixing speed of p-Cresol extraction increasesthe yield of p-Cresol and the mass transfer coefficient. The highest yield of p-Cresol is 49.32% and the highest mass transfer coefficient is 4.757 x 10-6kg/m2s.

  8. Submerged culture of phellinus linteus in a stirred tank fermenter and an airlift fermenter

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Keun Ho; Lee, Chang Woo [Dept. of Chemical Engineering, Hanbat National University, Taejeon (Korea)

    2000-04-01

    In this study, to choose a suitable bioreactor type for the mass culture of Phellinus linteus mycelium, we cultured phellinus linteus mycelium using a stirred tank fermenter and an airlift fermenter and compared the performances of the two fermenters. The effects of aeration rate and agitation speed on the culture of Phellinus linteus mycelium were also investigated in the ranges of 1-4L/min, 200-300 rpm, respectively. For the Batch submerged culture, the dry weight of mycelium, pH, and dissolved oxygen concentration changed in four steps, respectively. But the periods of same steps were not consistent with each other. With an increase in aeration rate, the final dry weight of mycelium, dissolved oxygen concentration and pH value until the third step of pH change were increased. As the time increased, the concentration of glucose decreased. However, the effects of aeration rate and agitation speed on the variation of glucose concentration were negligible. The maximum final dry weight of mycelium was obtained when agitation speed was 300 rpm. The dissolved oxygen concentration was increased with agitation speed. The dry weight of mycelium and dissolved oxygen concentration in the continuous stirred tank fermenter were larger than them those in the airlift fermenter. 27 refs., 9 figs.

  9. Large Eddy Simulations of a Stirred Tank Using the Lattice Boltzmann Method on a Nonuniform Grid

    Science.gov (United States)

    Lu, Zhenyu; Liao, Ying; Qian, Dongying; McLaughlin, J. B.; Derksen, J. J.; Kontomaris, K.

    2002-09-01

    A nonuniform grid lattice Boltzmann technique previously described by He et al. [1] has been extended to simulate three-dimensional flows in complex geometries. The technique is applied to the computation of the turbulent flow in a stirred tank driven by a standard Rushton turbine. With the nonuniform grid approach, the total CPU time required for a simulation of the flow in a stirred tank can be reduced by roughly 75% and still provide the same spatial accuracy as would be obtained with a uniform high-resolution grid. Statistical results for the computed flow fields will be compared with experimental results (H. Wu and G. K. Patterson, Chem. Eng. Sci.44, 2207 (1989)) and with simulations by J. G. M. Eggels ( Int. J. Heat Fluid Flow17, 307 (1996)) and J. J. Derksen and H. E. A. Van den Akker ( AIChE J.45, 209 (1999)). The results of the nonuniform mesh simulation are in reasonable agreement with the available experimental data and the results of previous simulations.

  10. Experimental measurement and computational fluid dynamics simulation of mixing in a stirred tank: a review

    Directory of Open Access Journals (Sweden)

    K. Kiriamiti

    2010-02-01

    Full Text Available Stirred tanks are typically used in many reactions. The quality of mixing generated by the impellers can be determined using either experimental and simulation methods, or both methods. The experimental techniques have evolved from traditional approaches, such as the application of hot-wire anemometry, to more modern ones like laser Doppler velocimetry (LDV. Similarly, computational fluid dynamics (CFD simulation techniques have attracted a lot of attention in recent years in the study of the hydrodynamics in stirred tanks, compared to the empirical modelling approach. Studies have shown that the LDV technique can provide very detailed information on the spatio-temporal variations in a tank, but the method is costly. For this reason, CFD simulation techniques may be employed to provide such data at a lower cost. In recent years, both integrated experimental and CFD approaches have been used to determine flow field and to design various systems. Both CFD and LDV data reveal the existence of flow maldistribution caused by system design features, and these in turn show that the configurations that have, over the years, been regarded as standard may not provide the optimal operating conditions with regards to the system homogeneity and power consumption. The current trends in CFD studies point towards an increasing application of more refined grids, such as in large eddy simulation, to capture turbulent structures at microscales. This trend will further improve the quality of the simulation results for processes such as precipitation, in which micromixing and reaction kinetics are important.

  11. Using spatio-temporal asymmetry to enhance mixing in chaotic flows: From maps to stirred tanks

    Science.gov (United States)

    Alvarez, Mario Moises

    Under laminar flow conditions, chaos is the only route to achieve effective mixing. Indeed, industrially relevant devices such as static mixers, stirred tanks, and roller bottles work because they create chaotic flows. However, they are generally operated and designed in a symmetric fashion (e.g. symmetric construction, periodic operation). Under such circumstances, chaotic and nonchaotic regions always co-exist, often hindering mixing performance. The introduction of asymmetries (in space or time) has been proposed as a means to improve mixing performance by generating globally chaotic systems in which the entire flow domain is subject to the action of exponential stretching and repeated folding, key features of chaotic flows capable of good mixing. Here we compare mixing performance of symmetric and asymmetric mixing flows from the point of view of the properties of the structure that they generate. In particular, we analyze two classes of systems: We use computer simulations to follow the process of elongation and deformation of interfaces as they are advected by time-periodic and aperiodic protocols in an idealized 2-D flow (the sine flow). The distribution of length scales characteristic of the partially mixed structures in this flow is calculated and their statistical properties are investigated. As the main conclusion, we find that the distribution of length scales is universal (independently on the periodic or aperiodic nature of the flow), and predictable (based on stretching calculations) for any globally chaotic flow. Subsequently, mixing structures and flow patterns in stirred tank systems of geometries encountered in engineering practice and operated in the laminar regime are investigated experimentally using UV visualization techniques, Particle Image Velocimetry (PIV) and Planar Laser Induced Fluorescence (p-LIF). It is experimentally demonstrated that concentric stirred tank configurations achieve partial chaos only by virtue of the small

  12. A new halogen-free chemical oscillator: the reaction between permanganate ion and ninhydrin in a continuously stirred tank reactor

    Science.gov (United States)

    Treindl, Ľudovít; Nagy, Arpád

    1987-07-01

    The reaction between permanganate ion and ninhydrin in the presence of phosphoric acid in aqueous solution shows sustained oscillations in a continuously stirred tank reactor (CSTR). It exhibits a kinetic bistability between an oscillatory and a stationary state. Our new oscillating system seems to be a second permanganate chemical oscillator, thus broadening the small group of non-halogen-based chemical oscillators.

  13. Nonequilibrium chemical instabilities in continuous flow stirred tank reactors: The effect of stirring

    Science.gov (United States)

    Horsthemke, W.; Hannon, L.

    1984-11-01

    We present a stochastic model for stirred chemical reactors. In the limiting case of practical interest, i.e., fast stirring, we solve for the characteristic function in steady state and derive expressions for the stationary moments through a perturbation expansion. Moments are explicitly calculated for a generic model of bistable behavior. We find that stirring decreases the area of the bistable region essentially by changing the point of transition from the high reaction rate state to the low reaction rate state. This is in remarkable agreement with the experimental findings of Roux, et al. Our results indicate that stirring should not be considered simply as an ``enhanced diffusion'' process and that nucleation plays only a minor role in transitions between multiple steady states in a continuous flow stirred tank reactor (CSTR).

  14. Biological treatment of phenolic wastewater in an anaerobic continuous stirred tank reactor

    Directory of Open Access Journals (Sweden)

    Firozjaee Taghizade Tahere

    2013-01-01

    Full Text Available In the present study, an anaerobic continuous stirred tank reactor (ACSTR with consortium of mixed culture was operated continuously for a period of 110 days. The experiments were performed with three different hydraulic retention times and by varying initial phenol concentrations between 100 to 1000 mg/L. A maximum phenol removal was observed at a hydraulic retention time (HRT of 4 days, with an organic loading rate (OLR of 170.86 mg/L.d. At this condition, phenol removal rate of 89% was achieved. In addition, the chemical oxygen demand (COD removal corresponds to phenol removal. Additional operating parameters such as pH, MLSS and biogas production rate of the effluents were also measured. The present study provides valuable information to design an anaerobic ACSTR reactor for the biodegradation of phenolic wastewater.

  15. Continuous-flow stirred-tank reactor 20-L demonstration test: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Lee, D.D.; Collins, J.L.

    2000-02-01

    One of the proposed methods of removing the cesium, strontium, and transuranics from the radioactive waste storage tanks at Savannah River is the small-tank tetraphenylborate (TPB) precipitation process. A two-reactor-in-series (15-L working volume each) continuous-flow stirred-tank reactor (CSTR) system was designed, constructed, and installed in a hot cell to test the Savannah River process. The system also includes two cross-flow filtration systems to concentrate and wash the slurry produced in the process, which contains the bulk of radioactivity from the supernatant processed through the system. Installation, operational readiness reviews, and system preparation and testing were completed. The first test using the filtration systems, two CSTRs, and the slurry concentration system was conducted over a 61-h period with design removal of Cs, Sr, and U achieved. With the successful completion of Test 1a, the following tests, 1b and 1c, were not required.

  16. Thermodynamics of open nonlinear systems far from equilibrium: The continuously stirred tank reactor

    Science.gov (United States)

    Yoshida, Nobuo

    1993-11-01

    A thermodynamic analysis is made of a continuously stirred tank reactor (CSTR) which is fed with ideal gases and in which arbitrary types of chemical reactions take place. For stationary states and oscillatory ones in which limit cycles are established, expressions are derived which describe the change of entropy of the reactor contents relative to the feed in terms of explicit quantities, including the rate of entropy production due to the chemical reactions. This entropy change is shown to be always greater than what would be observed in closed systems under comparable circumstances. It is pointed out that this statement is beyond what the second law of thermodynamics can predict. In previous articles, entropy and entropy production have been found to follow certain systematic trends in some specific models based on the CSTR. That work is compared with the present theory.

  17. Anaerobic digestion performance of vinegar residue in continuously stirred tank reactor.

    Science.gov (United States)

    Li, Lin; Feng, Lu; Zhang, Ruihong; He, Yanfeng; Wang, Wen; Chen, Chang; Liu, Guangqing

    2015-06-01

    Anaerobic digestion (AD) of vinegar residue was investigated in continuously stirred tank reactor (CSTR). The influence of organic loading rate (OLR) and effluent recirculation on AD performance of vinegar residue was tested. Five OLRs, 1.0, 1.5, 2.0, 2.5, and 3.0 g(vs) L(-1) d(-1), were used. The highest volumetric methane productivity of 581.88 mL L(-1) was achieved at OLR of 2.5 g(vs) L(-1) d(-1). Effluent reflux ratio was set as 50%, the results showed that effluent recirculation could effectively neutralize the acidity of vinegar residue, raise the pH of the feedstock, and enhance the buffering capacity of the AD system. Anaerobic digestion of vinegar residue could be a promising way not only for converting this waste into gas energy but also alleviating environmental pollution which might be useful for future industrial application.

  18. Power demand and mixing performance of coaxial mixers in a stirred tank with CMC solution

    Institute of Scientific and Technical Information of China (English)

    Yuyun Bao; Yu Lu; Qianqin Liang; Li Li; Zhengming Gao; Xiongbin Huang; Song Qin

    2015-01-01

    Experimental investigation was carried out in an el iptical based stirred tank with a diameter of 0.48 m to explore the power demand and mixing performance of coaxial mixers. Syrup and CMC solution (sodium carboxy methyl cellulose) were used as the Newtonian and non-Newtonian fluids, respectively. Four different coaxial mixers were combined with either CBY or Pfaudler impeller as the inner one, and anchor or helical ribbon (HR) as the outer one. Results show that Pfaudler-HR is the optimized combination among four coaxial mixers in this work, which provides the shortest mixing time given the same power consumption. Compared with the syrup solution, the increase of power input can make the mixing time decreasing more obviously in the CMC solution. The quantitative correlations for both syrup and CMC solutions were established to calculate the power draw and the mixing time of four coaxial mixers.

  19. Large eddy simulations of flow instabilities in a stirred tank generate by a Rushton turbine

    DEFF Research Database (Denmark)

    Fan, Jianhua; Wang, Yundong; Fei, Weiyang

    2007-01-01

    The aim of this paper is to investigate the flow instabilities in a baffled, stirred tank generated by a single Rushton turbine by means of large eddy simulation (LES) and simulation using the k-ε turbulent model. A sliding mesh method was used for the coupling between the rotating...... that CFD simulations using k-ε model and LES approach agreed well with the DPIV measurement. Fluctuations of the radial and axial velocity were well predicted at different frequencies by the LES simulation. Velocity fluctuations of high frequencies were observed in the impeller region, while low...... computational time and computer memories. The results of the present work give better understanding to the mixing mechanisms in the mechanically agitated tank....

  20. Performance of continuous stirred tank reactor (CSTR) on fermentative biohydrogen production from melon waste

    Science.gov (United States)

    Cahyari, K.; Sarto; Syamsiah, S.; Prasetya, A.

    2016-11-01

    This research was meant to investigate performance of continuous stirred tank reactor (CSTR) as bioreactor for producing biohydrogen from melon waste through dark fermentation method. Melon waste are commonly generated from agricultural processing stages i.e. cultivation, post-harvesting, industrial processing, and transportation. It accounted for more than 50% of total harvested fruit. Feedstock of melon waste was fed regularly to CSTR according to organic loading rate at value 1.2 - 3.6 g VS/ (l.d). Optimum condition was achieved at OLR 2.4 g VS/ (l.d) with the highest total gas volume 196 ml STP. Implication of higher OLR value is reduction of total gas volume due to accumulation of acids (pH 4.0), and lower substrate volatile solid removal. In summary, application of this method might valorize melon waste and generates renewable energy sources.

  1. Modeling of organic pollutant destruction in a stirred-tank reactor by ozonation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Destruction of organic contaminants in water by ozonation is a gas-liquid process which involves ozone mass transfer and fast irreversible chemical reactions. Ozonation reactor design and process optimizing require the modeling of the gas-liquid interactions within the reactor. In this paper a theoretical model combining the fluid dynamic and reaction kineticparameters is proposed for predicting the destruction rates of organic pollutants in a semi-batch stirred-tank reactor by ozonation. A simple expression for the enhancement factor as ourprevious work (Cheng, 2000) has been applied to evaluate the chemical mass transfer coefficient in ozone absorption.2,4-dichlorophenol (2,4-DCP) and 2,6-DCP or their mixture are chosen as the model compounds for simulating, and the predicted DCP oundation item: The National Natural Science Foundation of China (No. 20006006) ncentrations are compared with some measured data.

  2. Genetic Algorithm Based PID Controller Tuning Approach for Continuous Stirred Tank Reactor

    Directory of Open Access Journals (Sweden)

    A. Jayachitra

    2014-01-01

    Full Text Available Genetic algorithm (GA based PID (proportional integral derivative controller has been proposed for tuning optimized PID parameters in a continuous stirred tank reactor (CSTR process using a weighted combination of objective functions, namely, integral square error (ISE, integral absolute error (IAE, and integrated time absolute error (ITAE. Optimization of PID controller parameters is the key goal in chemical and biochemical industries. PID controllers have narrowed down the operating range of processes with dynamic nonlinearity. In our proposed work, globally optimized PID parameters tend to operate the CSTR process in its entire operating range to overcome the limitations of the linear PID controller. The simulation study reveals that the GA based PID controller tuned with fixed PID parameters provides satisfactory performance in terms of set point tracking and disturbance rejection.

  3. Bio-hydrogen production from molasses by anaerobic fermentation in continuous stirred tank reactor

    Science.gov (United States)

    Han, Wei; Li, Yong-feng; Chen, Hong; Deng, Jie-xuan; Yang, Chuan-ping

    2010-11-01

    A study of bio-hydrogen production was performed in a continuous flow anaerobic fermentation reactor (with an available volume of 5.4 L). The continuous stirred tank reactor (CSTR) for bio-hydrogen production was operated under the organic loading rates (OLR) of 8-32 kg COD/m3 reactor/d (COD: chemical oxygen demand) with molasses as the substrate. The maximum hydrogen production yield of 8.19 L/d was obtained in the reactor with the OLR increased from 8 kg COD/m3 reactor/d to 24 kg COD/m3 d. However, the hydrogen production and volatile fatty acids (VFAs) drastically decreased at an OLR of 32 kg COD/m3 reactor/d. Ethanoi, acetic, butyric and propionic were the main liquid fermentation products with the percentages of 31%, 24%, 20% and 18%, which formed the mixed-type fermentation.

  4. Modelling, Optimization and Optimal Control of Small Scale Stirred Tank Bioreactors

    Directory of Open Access Journals (Sweden)

    Mitko Petrov

    2004-10-01

    Full Text Available Models of the mass-transfer in a stirred tank bioreactor depending on general indexes of the processes of aeration and mixing in concrete simplifications of the hydrodynamic structure of the flows are developed. The offered combined model after parameters identification is used for optimization of the parameters of the apparatus construction. The optimization problem is solved by using of the fuzzy sets theory and in this way the unspecified as a result of the model simplification are read. In conclusion an optimal control of a fed-batch fermentation process of E. coli is completed by using Neuro-Dynamic programming. The received results after optimization show a considerable improvement of the mass-transfer indexes and the quantity indexes at the end of the process.

  5. Ozone degradation of alkylbenzene sulfonate in aqueous solutions using a stirred tank reactor with recirculation.

    Science.gov (United States)

    Jurado-Alameda, Encarnación; Vicaria, José M; Altmajer-Vaz, Deisi; Luzón, Germán; Jiménez-Pérez, José L; Moya-Ramírez, Ignacio

    2012-01-01

    The degradation of linear alkylbenzene sulfonates (LAS) in aqueous solutions by ozone has been investigated. The ozonation process was performed in a stirred tank reactor with recirculation which simulates the clean-in-place process used in many industrial facilities. The gas-liquid mass transfer of ozone in a buffer solution at different temperatures (25-55°C) was also studied in the same device, revealing that ozone decomposition can be considered negligible under the experimental conditions assayed. The effect of the initial LAS concentration, temperature, and ozone concentration on the concentration of homologues and total LAS were analysed as a function of time. Both concentrations diminished with time, this effect being more significant when higher temperatures were assayed. The relative proportion of homologues shows that the homologues of higher chain length are degraded in a greater proportion than are the homologues with shorter chain lengths.

  6. Stability criteria and critical runway conditions of propylene glycol manufacture in a continuous stirred tank reactor

    Directory of Open Access Journals (Sweden)

    Miguel Ángel Gómez

    2015-08-01

    Full Text Available Here, a new method for the analysis of the steady state and the safety operational conditions of the hydrolysis of propylene oxide with excess of water, in a Continuous Stirred Tank Reactor (CSTR, was developed. For industrial operational typical values, at first, the generated and removed heat balances were examined. Next, the effect of coolant fluid temperature in the critical ignition and extinction temperatures (TCI and TCE, respectively was analyzed. The influence of the heat exchange parameter (hS on coolant and critical temperatures was also studied. Finally, the steady state operation areas were defined. The existence of multiple stable states was recognized when the heat exchange parameter was in the range 6.636 < hS kJ/(min.K < 11.125. Unstable operation area was located between the TCI and TCE values, restricting the reactor operation area to the low stable temperatures.

  7. Immersion and invariance adaptive control of a class of continuous stirred tank reactors

    Institute of Scientific and Technical Information of China (English)

    Gaiyan HONG; Xiangbin LIU; Hongye SU

    2015-01-01

    An immersion and invariance (I&I) manifold based adaptive control algorithm is presented for a class of continuous stirred tank reactors (CSTR) to realize performance-oriented control in this paper. The nonlinear contraction method is combined into the control law design to render the closed-loop CSTR system globally asymptotically stable, firstly. Then, the I&I method is used to form the adaptation law such that the off-the-manifold coordinate (the parameter estimation error) converges to zero using P-monotone property enforced by selecting tuning function in manifold. As a result, the state of the closed-loop CSTR converges to its desired value asymptotically. The simulation is given to illustrate the effectiveness of the presented algorithm.

  8. CFD optimization of continuous stirred-tank (CSTR) reactor for biohydrogen production.

    Science.gov (United States)

    Ding, Jie; Wang, Xu; Zhou, Xue-Fei; Ren, Nan-Qi; Guo, Wan-Qian

    2010-09-01

    There has been little work on the optimal configuration of biohydrogen production reactors. This paper describes three-dimensional computational fluid dynamics (CFD) simulations of gas-liquid flow in a laboratory-scale continuous stirred-tank reactor used for biohydrogen production. To evaluate the role of hydrodynamics in reactor design and optimize the reactor configuration, an optimized impeller design has been constructed and validated with CFD simulations of the normal and optimized impeller over a range of speeds and the numerical results were also validated by examination of residence time distribution. By integrating the CFD simulation with an ethanol-type fermentation process experiment, it was shown that impellers with different type and speed generated different flow patterns, and hence offered different efficiencies for biohydrogen production. The hydrodynamic behavior of the optimized impeller at speeds between 50 and 70 rev/min is most suited for economical biohydrogen production.

  9. Evaluating the efficiency of two phase partitioning stirred tank bio-reactor for treating xylene vapors from the airstreamthrough a bed of Pseudomonas Putida

    Directory of Open Access Journals (Sweden)

    F. Golbabaei

    2015-04-01

    Conclusion: Overall, the results of the present research revealed that the application of two phase stirred tank bioreactors (TPPBs containing pure strains of Pseudomonas putida was successful for treatment of air streams with xylene.

  10. A novel milliliter-scale chemostat system for parallel cultivation of microorganisms in stirred-tank bioreactors.

    Science.gov (United States)

    Schmideder, Andreas; Severin, Timm Steffen; Cremer, Johannes Heinrich; Weuster-Botz, Dirk

    2015-09-20

    A pH-controlled parallel stirred-tank bioreactor system was modified for parallel continuous cultivation on a 10 mL-scale by connecting multichannel peristaltic pumps for feeding and medium removal with micro-pipes (250 μm inner diameter). Parallel chemostat processes with Escherichia coli as an example showed high reproducibility with regard to culture volume and flow rates as well as dry cell weight, dissolved oxygen concentration and pH control at steady states (n=8, coefficient of variation bioreactor on a liter-scale. Thus, parallel and continuously operated stirred-tank bioreactors on a milliliter-scale facilitate timesaving and cost reducing steady state studies with microorganisms. The applied continuous bioreactor system overcomes the drawbacks of existing miniaturized bioreactors, like poor mass transfer and insufficient process control.

  11. Effect of tryptone and ammonia on the biogas process in continuously stirred tank reactors treating cattle manure

    DEFF Research Database (Denmark)

    Nielsen, Hanne Bjerg; Ahring, Birgitte Kiær

    2007-01-01

    . Three days after the pulses a second peak in acetate concentration and a decrease in methane production indicated an ammonia-inhibition of the acetoclastic methanogens. During the pulses of tryptone the performance of R1 was slightly more affected than R2. Pulses of ammonia (0.79 g l(-1) as N) resulted...... in a decrease in methane production of both reactors but no immediate increases in VFA concentrations was observed illustrating that the ammonia inhibition during this experiment was an overall inhibition of the biogas process and not only an inhibition of the methanogens.......Two themophilic continuously stirred tank reactors, R1 and Two thermophilic continuously stirred tank reactors, R1 and R2, were subject to pulses of tryptone and ammonia. R1 was operated at an ammonia-N concentration of 3.0 g l(-1) and R2 was operated at an ammonia-N concentration of 1.7 g l(-1...

  12. Cultivation of diploid and tetraploid hairy roots of Datura stramonium L. in stirred tank bioreactor for tropane alkaloids production

    Directory of Open Access Journals (Sweden)

    ATANAS PAVLOV

    2012-01-01

    Full Text Available Biomass accumulation and tropane alkaloids production by diploid and tetraploid hairy root cultures of Datura stramonium L. cultivated in stirred tank bioreactor at different aeration rates were investigated. The maximal growth for both hairy root cultures (ADB = 8.3 g/L and 6.8 g/L for diploid and tetraploid line, respectively was achieved at aeration rate of 15.0 L/(L.h. The corresponding growth indexes were remarkably high (GIDW = 9.0 and 7.8 for diploid and tetraploid line, respectively compared to the values, usually reported for other hairy root cultures. The optimal aeration rate for biomass accumulation was also optimal for alkaloids biosynthesis. According to our survey, the achieved maximal amounts of accumulated hyoscyamine (35.0 mg/L and 27.0 mg/L for diploid and tetraploid line were the highest reported in the scientific literature for D. stramonium L. hairy roots. During the cultivation in stirred tank bioreactor, the hairy roots biosynthesized pharmaceutically important alkaloid scopolamine in minor concentrations. This is an important observation since scopolamine was not detected during submerged cultivation of these hairy root lines in other bioreactor types. However, the ploidy level was found to be the most important factor concerning scopolamine production by D. stramonium L. hairy roots cultures. The present work demonstrated the effect of ploidity levels on biomass accumulation and tropane alkaloids production by D. stramonium L. hairy roots cultivated in stirred tank bioreactor. This investigation show that the stirred tank bioreactor could be successfully applied for both maximal biomass accumulations, as well as for manipulation of tropane alkaloids production by diploid and tetraploid D. stramonium L. hairy root cultures.

  13. Control of the sulfide (S2-) concentration for optimal zinc removal by sulfide precipitation in a continuously stirred tank reactor

    NARCIS (Netherlands)

    Veeken, A.H.M.; Akoto, L.; Pol, L.W.H.; Weijma, J.

    2003-01-01

    Precipitation of Zn2+ with S2− was studied at room temperature in a continuously stirred tank reactor of 0.5 l to which solutions of ZnSO4 (800–5800 mg Zn2+/l) and Na2S were supplied. The pH was controlled at 6.5 and S2− concentration in the reactor was controlled at set point values ranging from 3.

  14. The Reduced Rank of Ensemble Kalman Filter to Estimate the Temperature of Non Isothermal Continue Stirred Tank Reactor

    OpenAIRE

    Erna Apriliani; Dieky Adzkiya; Arief Baihaqi

    2011-01-01

    Kalman filter is an algorithm to estimate the state variable of dynamical stochastic system. The square root ensemble Kalman filter is an modification of Kalman filter. The square root ensemble Kalman filter is proposed to keep the computational stability and reduce the computational time. In this paper we study the efficiency of the reduced rank ensemble Kalman filter. We apply this algorithm to the non isothermal continue stirred tank reactor problem. We decompose the covariance of the ense...

  15. Dynamical Analysis of a Continuous Stirred-Tank Reactor with the Formation of Biofilms for Wastewater Treatment

    Directory of Open Access Journals (Sweden)

    Karen López Buriticá

    2015-01-01

    Full Text Available This paper analyzes the dynamics of a system that models the formation of biofilms in a continuous stirred-tank reactor (CSTR when it is utilized for wastewater treatment. The growth rate of the microorganisms is modeled using two different kinetics, Monod and Haldane kinetics, with the goal of studying the influence of each in the system. The equilibrium points are identified through a stability analysis, and the bifurcations found are characterized.

  16. Imaging Velocimetry Measurements for Entropy Production in a Rotational Magnetic Stirring Tank and Parallel Channel Flow

    Directory of Open Access Journals (Sweden)

    Greg F. Naterer

    2009-07-01

    Full Text Available An experimental design is presented for an optical method of measuring spatial variations of flow irreversibilities in laminar viscous fluid motion. Pulsed laser measurements of fluid velocity with PIV (Particle Image Velocimetry are post-processed to determine the local flow irreversibilities. The experimental technique yields whole-field measurements of instantaneous entropy production with a non-intrusive, optical method. Unlike point-wise methods that give measured velocities at single points in space, the PIV method is used to measure spatial velocity gradients over the entire problem domain. When combined with local temperatures and thermal irreversibilities, these velocity gradients can be used to find local losses of energy availability and exergy destruction. This article focuses on the frictional portion of entropy production, which leads to irreversible dissipation of mechanical energy to internal energy through friction. Such effects are significant in various technological applications, ranging from power turbines to internal duct flows and turbomachinery. Specific problems of a rotational stirring tank and channel flow are examined in this paper. By tracking the local flow irreversibilities, designers can focus on problem areas of highest entropy production to make local component modifications, thereby improving the overall energy efficiency of the system.

  17. Experimental Characterisation and Modelling of Homogeneous Solid Suspension in an Industrial Stirred Tank

    Directory of Open Access Journals (Sweden)

    Sébastien Calvo

    2013-01-01

    Full Text Available In this work, we study the conditions needed to reach homogeneous distribution of aluminium salts particles in water inside a torispherical bottom shaped stirred tank of 70 L equipped with a Pfaudler RCI type impeller and three equispaced vertical baffles. The aim of the present study is to develop a CFD model describing the quality of particle distribution in industrial scale tanks. This model, validated with experimental data, is used afterwards to develop scale-up and scale-down correlations to predict the minimum impeller speed needed to reach homogeneous solid distribution Nhs. The commercial CFD software Fluent 14 is used to model the fluid flow and the solid particle distribution in the tank. Sliding Mesh approach is used to take the impeller motion into account. Assuming that the discrete solid phase has no influence on the continuous liquid phase behaviour, the fluid flow dynamics is simulated independently using the well-known k-∊ turbulence model. The liquid-solid mixture behaviour is then described by implementing the Eulerian Mixture model. Computed liquid velocity fields are validated by comparison with PIV measurements. Computed Nhs were found to be in good agreement with experimental measurements. Results from different scales allowed correlating Nhs values to the volumetric power consumption.

  18. Micromixing characteristics in a gas-liquid-solid stirred tank with settling particles☆

    Institute of Scientific and Technical Information of China (English)

    Wanbo Li; Xingye Geng; Yuyun Bao; Zhengming Gao

    2015-01-01

    The parallel-competing iodide–iodate reaction scheme was used to study the micromixing performance in a multi-phase stirred tank of 0.3 m diameter. The impeller combination consisted of a half el iptical blade disk tur-bine below two down-pimping wide-blade hydrofoils, identified as HEDT+2WHD. Nitrogen and glass beads of 100μm diameter and density 2500 kg·m−3 were used as the dispersed phases. The micromixing could be improved by sparging gas because of its additional potential energy. Also, micromixing could be improved by the solid particles with high kinetic energy near the impeller tip. In a gas–solid–liquid system, the gas–liquid film vibration with damping, due to the frequent collisions between the bubbles and particles, led to the decrease of the turbulence level in the liquid and caused eventual y the deterioration of the micromixing. A Damping Film Dissipation model is formulated to shed light on the above micromixing performances. At last, the micromixing time tm according to the incorporation model varied from 1.9 ms to 6.7 ms in our experiments.

  19. Culture of human mesenchymal stem cells on microcarriers in a 5 l stirred-tank bioreactor.

    Science.gov (United States)

    Rafiq, Qasim A; Brosnan, Kathryn M; Coopman, Karen; Nienow, Alvin W; Hewitt, Christopher J

    2013-08-01

    For the first time, fully functional human mesenchymal stem cells (hMSCs) have been cultured at the litre-scale on microcarriers in a stirred-tank 5 l bioreactor, (2.5 l working volume) and were harvested via a potentially scalable detachment protocol that allowed for the successful detachment of hMSCs from the cell-microcarrier suspension. Over 12 days, the dissolved O2 concentration was >45 % of saturation and the pH between 7.2 and 6.7 giving a maximum cell density in the 5 l bioreactor of 1.7 × 10(5) cells/ml; this represents >sixfold expansion of the hMSCs, equivalent to that achievable from 65 fully-confluent T-175 flasks. During this time, the average specific O2 uptake of the cells in the 5 l bioreactor was 8.1 fmol/cell h and, in all cases, the 5 l bioreactors outperformed the equivalent 100 ml spinner-flasks run in parallel with respect to cell yields and growth rates. In addition, yield coefficients, specific growth rates and doubling times were calculated for all systems. Neither the upstream nor downstream bioprocessing unit operations had a discernible effect on cell quality with the harvested cells retaining their immunophenotypic markers, key morphological features and differentiation capacity.

  20. Selective precipitation of Cu from Zn in a pS controlled continuously stirred tank reactor

    Energy Technology Data Exchange (ETDEWEB)

    Sampaio, R.M.M., E-mail: ricardo.sampaio@wur.nl [Sub-department of Environmental Technology, Wageningen University, ' Biotechnion' , Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen (Netherlands); Timmers, R.A., E-mail: ruud.timmers@wur.nl [Sub-department of Environmental Technology, Wageningen University, ' Biotechnion' , Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen (Netherlands); Xu, Y., E-mail: lucyxyzxyz@hotmail.com [Sub-department of Environmental Technology, Wageningen University, ' Biotechnion' , Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen (Netherlands); Keesman, K.J., E-mail: karel.keesman@wur.nl [Systems and Control Group, Wageningen University, Bornsesteeg 59, 6708 PD Wageningen (Netherlands); Lens, P.N.L., E-mail: piet.lens@wur.nl [Sub-department of Environmental Technology, Wageningen University, ' Biotechnion' , Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen (Netherlands)

    2009-06-15

    Copper was continuously and selectively precipitated with Na{sub 2}S to concentrations below 0.3 ppb from water containing around 600 ppm of both Cu and Zn in a Continuously Stirred Tank Reactor. The pH was controlled at 3 and the pS at 25 (pS = -log(S{sup 2-})) by means of an Ag{sub 2}S sulfide selective electrode. Copper's recovery and purity were about 100%, whereas the total soluble sulfide concentration was below 0.02 ppm. X-ray diffraction (XRD) analysis showed that copper precipitated as hexagonal CuS (covellite). The mode of the particle size distribution (PSD) of the CuS precipitates was around 36 {mu}m. The PSD increased by high pS values and by the presence of Zn. Depending on the turbulence, the CuS precipitates can grow up to 200 {mu}m or fragment in particles smaller than 3 {mu}m in a few seconds. Zn precipitation with Na{sub 2}S at pH 3 and 4, in batch, always lead to Zn concentrations above 1 ppm. Zn precipitated as cubic ZnS (spharelite).

  1. Biodegradation of high concentrations of benzene vapors in a two phase partition stirred tank bioreactor

    Directory of Open Access Journals (Sweden)

    Karimi Ali

    2013-01-01

    Full Text Available Abstract The present study examined the biodegradation rate of benzene vapors in a two phase stirred tank bioreactor by a bacterial consortium obtained from wastewater of an oil industry refinery house. Initially, the ability of the microbial consortium for degrading benzene was evaluated before running the bioreactor. The gaseous samples from inlet and outlet of bioreactor were directly injected into a gas chromatograph to determine benzene concentrations. Carbone oxide concentration at the inlet and outlet of bioreactor were also measured with a CO2 meter to determine the mineralization rate of benzene. Influence of the second non-aqueous phase (silicon oil has been emphasized, so at the first stage the removal efficiency (RE and elimination capacity (EC of benzene vapors were evaluated without any organic phase and in the second stage, 10% of silicon oil was added to bioreactor media as an organic phase. Addition of silicon oil increased the biodegradation performance up to an inlet loading of 5580 mg/m3, a condition at which, the elimination capacity and removal efficiency were 181 g/m3/h and 95% respectively. The elimination rate of benzene increased by 38% in the presence of 10% of silicone oil. The finding of this study demonstrated that two phase partition bioreactors (TPPBs are potentially effective tools for the treatment of gas streams contaminated with high concentrations of poorly water soluble organic contaminant, such as benzene.

  2. Biodegradation of High Concentrations of Benzene Vapors in a Two Phase Partition Stirred Tank Bioreactor

    Directory of Open Access Journals (Sweden)

    Ali Karimi

    2013-01-01

    Full Text Available The present study examined the biodegradation rate of benzene vapors in a two phase stirred tank bioreactor by a bacterial consortium obtained from wastewater of an oil industry refinery house. Initially, the ability of the microbial consortium for degrading benzene was evaluated before running the bioreactor. The gaseous samples from inlet and outlet of bioreactor were directly injected into a gas chromatograph to determine benzene concentrations. Carbone oxide concentration at the inlet and outlet of bioreactor were also measured with a CO2 meter to determine the mineralization rate of benzene. Influence of the second non-aqueous phase (silicon oil has been emphasized, so at the first stage the removal efficiency (RE and elimination capacity (EC of benzene vapors were evaluated without any organic phase and in the second stage, 10% of silicon oil was added to bioreactor media as an organic phase. Addition of silicon oil increased the biodegradation performance up to an inlet loading of 5580?mg/m3, a condition at which, the elimination capacity and removal efficiency were 181?g/m3/h and 95% respectively. The elimination rate of benzene increased by 38% in the presence of 10% of silicone oil. The finding of this study demonstrated that two phase partition bioreactors (TPPBs are potentially effective tools for the treatment of gas streams contaminated with high concentrations of poorly water soluble organic contaminant, such as benzene.

  3. Cassava Stillage Treatment by Thermophilic Anaerobic Continuously Stirred Tank Reactor (CSTR)

    Science.gov (United States)

    Luo, Gang; Xie, Li; Zou, Zhonghai; Zhou, Qi

    2010-11-01

    This paper assesses the performance of a thermophilic anaerobic Continuously Stirred Tank Reactor (CSTR) in the treatment of cassava stillage under various organic loading rates (OLRs) without suspended solids (SS) separation. The reactor was seeded with mesophilic anaerobic granular sludge, and the OLR increased by increments to 13.80 kg COD/m3/d (HRT 5d) over 80 days. Total COD removal efficiency remained stable at 90%, with biogas production at 18 L/d (60% methane). Increase in the OLR to 19.30 kg COD/m3/d (HRT 3d), however, led to a decrease in TCOD removal efficiency to 79% due to accumulation of suspended solids and incomplete degradation after shortened retention time. Reactor performance subsequently increased after OLR reduction. Alkalinity, VFA and pH levels were not significantly affected by OLR variation, indicating that no additional alkaline or pH adjustment is required. More than half of the SS in the cassava stillage could be digested in the process when HRT was 5 days, which demonstrated the suitability of anaerobic treatment of cassava stillage without SS separation.

  4. [Research on change process of nitrosation granular sludge in continuous stirred-tank reactor].

    Science.gov (United States)

    Yin, Fang-Fang; Liu, Wen-Ru; Wang, Jian-Fang; Wu, Peng; Shen, Yao-Liang

    2014-11-01

    In order to investigate the effect of different types of reactors on the nitrosation granular sludge, a continuous stirred-tank reactor (CSTR) was studied, using mature nitrosation granular sludge cultivated in sequencing batch reactor (SBR) as seed sludge. Results indicated that the change of reactor type and influent mode could induce part of granules to lose stability with gradual decrease in sludge settling ability during the initial period of operation. However, the flocs in CSTR achieved fast granulation in the following reactor operation. In spite of the changes of particle size distribution, e. g. the decreasing number of granules with diameter larger than 2.5 mm and the increasing number of granules with diameter smaller than 0.3 mm, granular sludge held the absolute predominance of sludge morphology in CSTR during the entire experimental period. Moreover, results showed that the change of reactor type and influent mode didn't affect the nitrite accumulation rate which was still kept at about 85% in effluent. Additionally, the average activity of the sludge in CSTR was stronger than that of the seed sludge, because the newly generated small particles in CSTR had higher specific reactive activity than the larger granules.

  5. Growth kinetics of biopigment production by Thai isolated Monascus purpureus in a stirred tank bioreactor.

    Science.gov (United States)

    Kongruang, Sasithorn

    2011-01-01

    Monascus purpureus is a biopigment-producing fungi whose pigments can be used in many biotechnological and food industries. The growth kinetics of biopigment production were investigated in a liquid fermentation medium in a 5-l stirred tank bioreactor at 30°C, pH 7, for 8 days with 100 rpm agitation and 1.38 × 10(5) N/m(2) aeration. Thai Monascus purpureus strains TISTR 3002, 3180, 3090 and 3385 were studied for color production, growth kinetics and productivity. Citrinin as a toxic metabolite was measured from the Monascus fermentation broth. The biopigment productions were detected from fermentation broth by scanning spectra of each strain produced. Results showed a mixture of yellow, orange and red pigments with absorption peaks of pigments occurring at different wavelengths for the four strains. It was found that for each pigment color, the color production from the strains increased in the order TISTR 3002, 3180, 3090, 3385 with 3385 production being approximately 10 times that of 3002. Similar results were found for growth kinetics and productivity. HPLC results showed that citrinin was not produced under the culture conditions of this study. The L*, a* and b* values of the CIELAB color system were also obtained for the yellow, orange and red pigments produced from the TISTR 3002, 3180, 3090 and 3385 strains. The colors of the pigments ranged from burnt umber to deep red.

  6. Bioconversion of Waste Gases into Biofuel via Fermentation in a Continuous Stirred Tank Bioreactor

    Directory of Open Access Journals (Sweden)

    Najafpour, G.

    2005-01-01

    Full Text Available Biological hydrogen production was carried out in a continuous stirred tank bioreactor. A photosynthetic bacterium, Rhodospirillum rubrum, was used as biocatalyst to oxidize carbon monoxides in the waste gas generated from biomass in a gasification process. The fresh liquid media was supplied for microbial growth which contained sodium acetate as carbon source at initial concentration of 4 gL-1. The optimum media space velocity or the suitable ratio of liquid flow rate to the reactor volume (F/VL was 0.02 h-1. At the steady state condition, the concentration of acetate was independent of the dilution rate and it was approximately 1.5 gL-1. The average cell dry weight in the fermentation broth was at satisfactory concentration, approximately 3.4 gL-1 with dilution rate at 0.55 mL min-1. The maximum value of KLa and CO conversion were about 58 h-1 and 80%, respectively, with agitation speed at 500 rpm and gas flow rate at 14 mL min-1. At this condition, the maximum yield of hydrogen production was 0.82 mmol H2•mmol-1 CO.

  7. Bioleaching of chalcopyrite by mixed culture of moderately thermophilic microorganisms

    Institute of Scientific and Technical Information of China (English)

    WU Chang-bin; ZENG Wei-min; ZHOU Hong-bo; FU Bo; HUANG Ju-fang; QIU Guan-zhou; WANG Dian-zuo

    2007-01-01

    A mixed culture of moderately thermophilic microorganisms was enriched from acid mine drainages(AMDs) samples collected from several sulphide mines in China, and the bioleaching of chalcopyrite was conducted both in shake flask and bioreactor.The results show that in the shake flask, the mixture can tolerate 50 g/L chalcopyrite after being acclimated to gradually increased concentrations of chalcopyrite. The copper extraction increases obviously in bioleaching of chalcopyrite with moderately thermophilic microorganisms supplemented with 0.4 g/L yeast extract at 180 r/min, 74% copper can be extracted in the pulp of 50 g/L chalcopyrite after 20 d. Compared with copper extractions of mesophilic culture, unacclimated culture and acclimated culture without addition of yeast extract, that of accliniated culture with addition of yeast extract is increased by 53%, 44% and 16%,respectively. In a completely stirred tank reactor, the mass fraction of copper and total iron extraction reach up to 81% and 56%,respectively. The results also indicate that it is necessary to add a large amount of acid to the pulp to extract copper from chalcopyrite effectively.

  8. The nonequilibrium electromotive force. II. Theory for a continuously stirred tank reactor

    Science.gov (United States)

    Keizer, Joel

    1987-10-01

    In previous work [J. Keizer, J. Chem. Phys. 82, 2751 (1985)] we used statistical nonequilibrium thermodynamics to predict a non-Nernstian component to the electromotive force (EMF) for half-reactions involving reactants at nonequilibrium steady states. In this paper we present a simple theory for calculating the nonequilibrium component of the EMF based on the elementary transport processes occurring in a continuously stirred tank reactor (CSTR). The calculations utilize the density-density correlation function, which is obtained from the statistical theory of nonequilibrium thermodynamics. This gives rise to an expression for the second partial derivatives of the generalized entropy, or sigma function, which is used to calculate generalized chemical potentials. The generalized chemical potentials are related to the EMF through a generalization of the Nernst equation. The calculations presented here depend on the residence time in the CSTR, reaction rate constants, feed line concentrations in the CSTR, and the diffusion constants of reactants and products. A characteristic diffusion length is used to represent the length scale below which turbulent mixing effects are not important. Calculations with the theory are carried out for several different reaction mechanisms, including A+B⇄C; A+B⇄C, D+E⇄B; A+B⇄2B; and A+B→C+D, A+D→C+E. Values of the nonequilibrium EMF depend on the mechanism as well as all of the transport parameters cited above. For a plausible choice of the diffusion length, corrections to the Nernst formula can be as large as 10-15 mV. Specific calculations for the reaction of Fe2+ with S2O2-8 are shown in the preceding paper to agree with experimental measurements on this system in a CSTR.

  9. Production of halophilic proteins using Haloferax volcanii H1895 in a stirred-tank bioreactor.

    Science.gov (United States)

    Strillinger, Eva; Grötzinger, Stefan Wolfgang; Allers, Thorsten; Eppinger, Jörg; Weuster-Botz, Dirk

    2016-02-01

    The success of biotechnological processes is based on the availability of efficient and highly specific biocatalysts, which can satisfy industrial demands. Extreme and remote environments like the deep brine pools of the Red Sea represent highly interesting habitats for the discovery of novel halophilic and thermophilic enzymes. Haloferax volcanii constitutes a suitable expression system for halophilic enzymes obtained from such brine pools. We developed a batch process for the cultivation of H. volcanii H1895 in controlled stirred-tank bioreactors utilising knockouts of components of the flagella assembly system. The standard medium Hv-YPC was supplemented to reach a higher cell density. Without protein expression, cell dry weight reaches 10 g L(-1). Two halophilic alcohol dehydrogenases were expressed under the control of the tryptophanase promoter p.tna with 16.8 and 3.2 mg gCDW (-1), respectively, at a maximum cell dry weight of 6.5 g L(-1). Protein expression was induced by the addition of L-tryptophan. Investigation of various expression strategies leads to an optimised two-step induction protocol introducing 6 mM L-tryptophan at an OD650 of 0.4 followed by incubation for 16 h and a second induction step with 3 mM L-tryptophan followed by a final incubation time of 4 h. Compared with the uncontrolled shaker-flask cultivations used until date, dry cell mass concentrations were improved by a factor of more than 5 and cell-specific enzyme activities showed an up to 28-fold increased yield of the heterologous proteins.

  10. Shear conditions in clavulanic acid production by Streptomyces clavuligerus in stirred tank and airlift bioreactors.

    Science.gov (United States)

    Cerri, M O; Badino, A C

    2012-08-01

    In biochemical processes involving filamentous microorganisms, the high shear rate may damage suspended cells leading to viability loss and cell disruption. In this work, the influence of the shear conditions in clavulanic acid (CA) production by Streptomyces clavuligerus was evaluated in a 4-dm(3) conventional stirred tank (STB) and in 6-dm(3) concentric-tube airlift (ALB) bioreactors. Batch cultivations were performed in a STB at 600 and 800 rpm and 0.5 vvm (cultivations B1 and B2) and in ALB at 3.0 and 4.1 vvm (cultivations A1 and A2) to define two initial oxygen transfer conditions in both bioreactors. The average shear rate ([Formula: see text]) of the cultivations was estimated using correlations of recent literature based on experimental data of rheological properties of the broth (consistency index, K, and flow index, n) and operating conditions, impeller speed (N) for STB and superficial gas velocity in the riser (UGR) for ALB. In the same oxygen transfer condition, the [Formula: see text] values for ALB were higher than those obtained in STB. The maximum [Formula: see text] presented a strong correlation with a maximum consistency index (K (max)) of the broth. Close values of maximum CA production were obtained in cultivations A1 and A2 (454 and 442 mg L(-1)) with similar maximum [Formula: see text] values of 4,247 and 4,225 s(-1). In cultivations B1 and B2, the maximum CA production of 269 and 402 mg L(-1) were reached with a maximum [Formula: see text] of 904 and 1,786 s(-1). The results show that high values of average shear rate increase the CA production regardless of the oxygen transfer condition and bioreactor model.

  11. Biodegradation of Fresh vs. Oven-Dried Inedible Crop Residue in a Continuously Stirred Tank Reactor

    Science.gov (United States)

    Crawford, Kamau; Strayer, Richard

    1998-01-01

    The degradation of soluble organics and mineral recovery from fresh and oven-dried biomass were compared in an Intermediate-Scale Aerobic Bioreactor (8 L working volume) to determine if drying crop residue improves performance in a continuously stirred tank reactor (CSTR). The study was conducted in an Intermediate-Scale Aerobic Bioreactor (ISAB) CSTR with dimensions of 390 mm height x 204 mm diameter. The pH in the bioreactor was controlled at 6.0, temperature at 30 C, and aeration at 7.0 L/min. Gases monitored were CO2 evolution and dissolved oxygen. Homogeneously mixed wheat cultures, used either fresh or oven-dried biomass and were leached, then placed in the ISAB for a 4-day degradation period. Studies found that mineral recovery was greater for leached oven-dried crop residue. However, after activity by the mixed microbial communities in the ISAB CSTR, there were little notable differences in the measured mineral recovery and degradation of soluble organic compounds. Degradation of soluble organic compounds was also shown to improve for leached oven-dried crop residue, but after mixing in the CSTR the degradation of the fresh biomass seemed to be slightly greater. Time for the biomass to turn in the CSTR appeared to be one factor for the experimental differences between the fresh and oven-dried biomass. Other factors, although not as defined, were the differing physical structures in the cell walls and varying microbial components of the fresh and oven-dried treatments due to changes in chemical composition after drying of the biomass.

  12. Fully automated single-use stirred-tank bioreactors for parallel microbial cultivations.

    Science.gov (United States)

    Kusterer, Andreas; Krause, Christian; Kaufmann, Klaus; Arnold, Matthias; Weuster-Botz, Dirk

    2008-04-01

    Single-use stirred tank bioreactors on a 10-mL scale operated in a magnetic-inductive bioreaction block for 48 bioreactors were equipped with individual stirrer-speed tracing, as well as individual DO- and pH-monitoring and control. A Hall-effect sensor system was integrated into the bioreaction block to measure individually the changes in magnetic field density caused by the rotating permanent magnets. A restart of the magnetic inductive drive was initiated automatically each time a Hall-effect sensor indicates one non-rotating gas-inducing stirrer. Individual DO and pH were monitored online by measuring the fluorescence decay time of two chemical sensors immobilized at the bottom of each single-use bioreactor. Parallel DO measurements were shown to be very reliable and independently from the fermentation media applied in this study for the cultivation of Escherichia coli and Saccharomyces cerevisiae. The standard deviation of parallel pH measurements was pH 0.1 at pH 7.0 at the minimum and increased to a standard deviation of pH 0.2 at pH 6.0 or at pH 8.5 with the complex medium applied for fermentations with S. cerevisiae. Parallel pH-control was thus shown to be meaningful with a tolerance band around the pH set-point of +/- pH 0.2 if the set-point is pH 6.0 or lower.

  13. Production of halophilic proteins using Haloferax volcanii H1895 in a stirred-tank bioreactor

    KAUST Repository

    Strillinger, Eva

    2015-10-01

    The success of biotechnological processes is based on the availability of efficient and highly specific biocatalysts, which can satisfy industrial demands. Extreme and remote environments like the deep brine pools of the Red Sea represent highly interesting habitats for the discovery of novel halophilic and thermophilic enzymes. Haloferax volcanii constitutes a suitable expression system for halophilic enzymes obtained from such brine pools. We developed a batch process for the cultivation of H. volcanii H1895 in controlled stirred-tank bioreactors utilising knockouts of components of the flagella assembly system. The standard medium Hv-YPC was supplemented to reach a higher cell density. Without protein expression, cell dry weight reaches 10 g L−1. Two halophilic alcohol dehydrogenases were expressed under the control of the tryptophanase promoter p.tna with 16.8 and 3.2 mg gCDW −1, respectively, at a maximum cell dry weight of 6.5 g L−1. Protein expression was induced by the addition of l-tryptophan. Investigation of various expression strategies leads to an optimised two-step induction protocol introducing 6 mM l-tryptophan at an OD650 of 0.4 followed by incubation for 16 h and a second induction step with 3 mM l-tryptophan followed by a final incubation time of 4 h. Compared with the uncontrolled shaker-flask cultivations used until date, dry cell mass concentrations were improved by a factor of more than 5 and cell-specific enzyme activities showed an up to 28-fold increased yield of the heterologous proteins.

  14. Extended continuous-flow stirred-tank reactor (ECSTR) as a simple model of life under thermodynamically open conditions

    Science.gov (United States)

    Takinoue, Masahiro; Ma, Yue; Mori, Yoshihito; Yoshikawa, Kenichi

    2009-07-01

    A continuous-flow stirred-tank reactor (CSTR) is a vital tool for investigating the nonlinear dynamics of chemical systems. This report proposes an extended CSTR (ECSTR) inspired by active and passive transports through a closed membrane in living systems. In addition to the externally-controlled flow in a conventional CSTR, we introduce passive diffusion through a membrane into the ECSTR. This extension allows us to control the chemical dynamics with a larger parameter-dimension. Numerical analyses show that the ECSTR can expand an oscillatory region in the parameter space and can convert a non-oscillatory chemical system to an oscillatory system.

  15. CONTINUOSLY STIRRED TANK REACTOR PARAMETERS THAT AFFECT SLUDGE BATCH 6 SIMULANT PROPERTIES

    Energy Technology Data Exchange (ETDEWEB)

    Newell, J.; Lambert, D.; Stone, M.; Fernandez, A.

    2010-05-28

    The High Level Radioactive Waste (HLW) Sludge in Savannah River Site (SRS) waste tanks was produced over a period of over 60 years by neutralizing the acidic waste produced in the F and H Separations Canyons with sodium hydroxide. The HLW slurries have been stored at free hydroxide concentrations above 1 M to minimize the corrosion of the carbon steel waste tanks. Sodium nitrite is periodically added as a corrosion inhibitor. The resulting waste has been subjected to supernate evaporation to minimize the volume of the stored waste. In addition, some of the waste tanks experienced high temperatures so some of the waste has been at elevated temperatures. Because the waste is radioactive, the waste is transforming through the decay of shorter lived radioactive species and the radiation damage that the decay releases. The goal of the Savannah River National Laboratory (SRNL) simulant development program is to develop a method to produce a sludge simulant that matches both the chemical and physical characteristics of the HLW without the time, temperature profile, chemical or radiation exposure of that of the real waste. Several different approaches have been taken historically toward preparing simulated waste slurries. All of the approaches used in the past dozen years involve some precipitation of the species using similar chemistry to that which formed the radioactive waste solids in the tank farm. All of the approaches add certain chemical species as commercially available insoluble solid compounds. The number of species introduced in this manner, however, has varied widely. All of the simulant preparation approaches make the simulated aqueous phase by adding the appropriate ratios of various sodium salts. The simulant preparation sequence generally starts with an acidic pH and ends up with a caustic pH (typically in the 10-12 range). The current method for making sludge simulant involves the use of a temperature controlled continuously stirred tank reactor (CSTR

  16. Production of hydrogen in a granular sludge-based anaerobic continuous stirred tank reactor

    Energy Technology Data Exchange (ETDEWEB)

    Show, Kuan-Yeow [Faculty of Engineering and Science, University of Tunku Abdul Rahman, 53300 Setapak, Kuala Lumpur (Malaysia); Zhang, Zhen-Peng; Tay, Joo-Hwa [School of Civil and Environmental Engineering, Nanyang Technological University, 639798 (Singapore); Institute of Environmental Science and Engineering, Nanyang Technological University, 637723 (Singapore); Tee Liang, David [Institute of Environmental Science and Engineering, Nanyang Technological University, 637723 (Singapore); Lee, Duu-Jong [Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan, RO (China); Jiang, Wen-Ju [Department of Environmental Science and Engineering, Sichuan University, Chengdu 610065 (China)

    2007-12-15

    An investigation on biohydrogen production was conducted in a granular sludge-based continuous stirred tank reactor (CSTR). The reactor performance was assessed at five different glucose concentrations of 2.5, 5, 10, 20 and 40 g/L and four hydraulic retention times (HRTs) of 0.25, 0.5, 1 and 2 h, resulting in the organic loading rates (OLRs) ranged between 2.5 and 20 g-glucose/L h. Carbon flow was traced by analyzing the composition of gaseous and soluble metabolites as well as the cell yield. Butyrate, acetate and ethanol were found to be the major soluble metabolite products in the biochemical synthesis of hydrogen. Carbon balance analysis showed that more than half of the glucose carbon was converted into unidentified soluble products at an OLR of 2.5 g-glucose/L h. It was found that high hydrogen yields corresponded to a sludge loading rate in between 0.6 and 0.8 g-glucose/g-VSS h. Substantial suppression in hydrogen yield was noted as the sludge loading rate fell beyond the optimum range. It is deduced that decreasing the sludge loading rate induced the metabolic shift of biochemical reactions at an OLR of 2.5 g-glucose/L h, which resulted in a substantial reduction in hydrogen yield to 0.36-0.41 mol-H{sub 2}/mol-glucose. Optimal operation conditions for peak hydrogen yield (1.84 mol-H{sub 2}/mol-glucose) and hydrogen production rate (3.26 L/L h) were achieved at an OLR of 20 g-glucose/L h, which corresponded to an HRT of 0.5 h and an influent glucose concentration of 10 g/L. Influence of HRT and substrate concentration on the reactor performance was interrelated and the adverse impact on hydrogen production was noted as substrate concentration was higher than 20 g/L or HRT was shorter than 0.5 h. The experimental study indicated that a higher OLR derived from appropriate HRTs and substrate concentrations was desirable for hydrogen production in such a granule-based CSTR. (author)

  17. Production of Newcastle Disease Virus by Vero Cells Grown on Cytodex 1 Microcarriers in a 2-Litre Stirred Tank Bioreactor

    Directory of Open Access Journals (Sweden)

    Mohd Azmir Arifin

    2010-01-01

    Full Text Available The aim of this study is to prepare a model for the production of Newcastle disease virus (NDV lentogenic F strain using cell culture in bioreactor for live attenuated vaccine preparation. In this study, firstly we investigated the growth of Vero cells in several culture media. The maximum cell number was yielded by culture of Vero cells in Dulbecco's Modified Eagle Medium (DMEM which was 1.93×106 cells/ml. Secondly Vero cells were grown in two-litre stirred tank bioreactor by using several commercial microcarriers. We achieved the maximum cell concentration about 7.95×105 cells/ml when using Cytodex 1. Later we produced Newcastle Disease virus in stirred tank bioreactor based on the design developed using Taguchi L4 method. Results reveal that higher multiplicity of infection (MOI and size of cell inoculums can yield higher virus titer. Finally, virus samples were purified using high-speed centrifugation based on 3∗∗(3-1 Fractional Factorial Design. Statistical analysis showed that the maximum virus titer can be achieved at virus sample concentration of 58.45% (v/v, centrifugation speed of 13729 rpm, and centrifugation time of 4 hours. As a conclusion, high yield of virus titer could be achieved through optimization of cell culture in bioreactor and separation by high-speed centrifugation.

  18. Effective bioleaching of chromium in tannery sludge with an enriched sulfur-oxidizing bacterial community.

    Science.gov (United States)

    Zeng, Jing; Gou, Min; Tang, Yue-Qin; Li, Guo-Ying; Sun, Zhao-Yong; Kida, Kenji

    2016-10-01

    In this study, a sulfur-oxidizing community was enriched from activated sludge generated in tannery wastewater treatment plants. Bioleaching of tannery sludge containing 0.9-1.2% chromium was investigated to evaluate the effectiveness of the enriched community, the effect of chromium binding forms on bioleaching efficiency, and the dominant microbes contributing to chromium bioleaching. Sludge samples inoculated with the enriched community presented 79.9-96.8% of chromium leaching efficiencies, much higher than those without the enriched community. High bioleaching efficiencies of over 95% were achieved for chromium in reducible fraction, while 60.9-97.9% were observed for chromium in oxidizable and residual fractions. Acidithiobacillus thiooxidans, the predominant bacteria in the enriched community, played an important role in bioleaching, whereas some indigenous heterotrophic species in sludge might have had a supporting role. The results indicated that A. thiooxidans-dominant enriched microbial community had high chromium bioleaching efficiency, and chromium binding forms affected the bioleaching performance.

  19. Molecular weight​/branching distribution modeling of low-​density-​polyethylene accounting for topological scission and combination termination in continuous stirred tank reactor

    NARCIS (Netherlands)

    Yaghini, N.; Iedema, P.D.

    2014-01-01

    We present a comprehensive model to predict the molecular weight distribution (MWD),(1) and branching distribution of low-density polyethylene (IdPE),(2) for free radical polymerization system in a continuous stirred tank reactor (CSTR).(3) The model accounts for branching, by branching moment or ps

  20. Linear and Non-linear Multi-Input Multi-Output Model Predictive Control of Continuous Stirred Tank Reactor

    Directory of Open Access Journals (Sweden)

    Muayad Al-Qaisy

    2013-04-01

    Full Text Available In this article, multi-input multi-output (MIMO linear model predictive controller (LMPC based on state space model and nonlinear model predictive controller based on neural network (NNMPC are applied on a continuous stirred tank reactor (CSTR. The idea is to have a good control system that will be able to give optimal performance, reject high load disturbance, and track set point change. In order to study the performance of the two model predictive controllers, MIMO Proportional-Integral-Derivative controller (PID strategy is used as benchmark. The LMPC, NNMPC, and PID strategies are used for controlling the residual concentration (CA and reactor temperature (T. NNMPC control shows a superior performance over the LMPC and PID controllers by presenting a smaller overshoot and shorter settling time.

  1. Stochastic resonance in the presence or absence of external signal in the continuous stirred tank reactor system

    Science.gov (United States)

    Hou, Zhonghuai; Xin, Houwen

    1999-07-01

    A two variable model, which has been proposed to describe a first-order, exothermic, irreversible reaction A→B carried out in a continuous stirred tank reactor (CSTR), is investigated when the control parameter is modulated by random and/or periodic forces. Within the bistable region where a limit cycle and a stable node coexist, stochastic resonance (SR) is observed when both random and periodic modulations are present. In the absence of periodic external signal noise induced coherent oscillations (NICO) appear when the control parameter is randomly modulated near the supercritical Hopf bifurcation point. In addition, the NICO-strength goes through a maximum with the increment of the noise intensity, characteristic for the occurrence of internal signal stochastic resonance (ISSR).

  2. Numerical Simulation of the Whole Three—Dimensional Flow in a Stirred Tank with Anisotropic Algebraic Stress Model

    Institute of Scientific and Technical Information of China (English)

    SUNHaiyan; WANGWeijing; 等

    2002-01-01

    In accordance to the anisotropic feature of turbulent flow, an anisotropic algebraic stress model is adopted to predict the turbulent flow field and turbulent characteristics generated by a Rushton disc turbine with the improved inner-outer iterative procedure. The predicted turbulent flow is compared with experimental data and the simulation by the standard κ-ε turbulence model. The anisotropic algebraic stress model is found to give better prediction than the standard κ-ε turbulence model. The predicted turbulent flow field is in accordance to experimental data and the trend of the turbulence intensity can be effectively reflected in the simulation. The distribution of turbulent shear rate in the stirred tanks was simulated with the established numerical procedure.

  3. Evaluation of mass-transfer and kinetic parameters for Rhodospirillum rubrum in a continuous stirred tank reactor

    Energy Technology Data Exchange (ETDEWEB)

    Klasson, K.T. (Oak Ridge National Lab., TN (United States)); Gupta, A.; Clausen, E.C.; Gaddy, J.L. (Univ. of Arkansas, Fayetteville, AR (United States))

    The photosynthetic bacterium Rhodospirillum rubrum has been evaluated for its ability to produce hydrogen from carbon monoxide and water in a continuous stirred tank reactor according to the water-gas shift reaction. An assessment of mass-transfer parameters and reaction kinetics was made for this sparingly soluble substrate system. Experiments were conducted in a nonsteady-state fashion with continuous liquid and gas flow, which allowed for separation of the mass-transfer and kinetic-limited regions. Based on the data obtained, mass-transfer coefficients for the system were determined, and a mathematical expression for the reaction kinetics was formulated. The results showed that the hydrogen production was inhibited by elevated levels of dissolved carbon monoxide in the liquid. 8 refs., 4 figs., 1 tab.

  4. Optimal conditions and operational parameters for conversion of Robusta coffee residues in a continuous stirred tank reactor

    Energy Technology Data Exchange (ETDEWEB)

    Msambichaka, B.L.; Kivaisi, A.K.; Rubindamayugi, M.S.T. [Univ. of Dar es Salaam, Applied Microbiology Unit (Tanzania, United Republic of)

    1997-12-31

    This experiment studied the possibility of optimizing anaerobic degradation, developing microbial adaptation and establishing long term process stability in a Continuous Stirred Tank Reactor (CSTR) running on Robusta coffee hulls as feed substrate. Decrease in lag phase and increase in methane production rate in batch culture experiment conducted before and after process stabilization of each operational phase in the CSTR clearly suggested that microbial adaptation to increasing coffee percentage composition was attained. Through gradual increase of coffee percentage composition, from 10% coffee, 2% VS, 20 days HRT and a 1 g VS/1/day loading rate to 80% coffee, 4.5% VS, 12 days HRT and a loading rate of 3 g VS/1/day the CSTR system was optimized at a maximum methane yield of 535 ml/g VS. Again it was possible to attain long term process stability at the above mentioned optimal operational parameters for a further 3 month period. (au)

  5. Rushton桨搅拌槽中气液两相流动的全流场数值模拟%Numerical Simulation of Gas-Liquid Flow in a Stirred Tank with a Rushton Impeller

    Institute of Scientific and Technical Information of China (English)

    王卫京; 毛在砂

    2002-01-01

    The gas-liquid flow field in a stirred tank with a Rushton disk turbine, including the impeller region,was numerically simulated using the improved inner-outer iterative procedure. The characteristic features of the stirred tank, such as gas cavity and accumulation of gas at the two sides of wall baffles, can be captured by the simulation. The simulated results agree well with available experimental data. Since the improved inner-outer iterative algorithm demands no empirical formula and experimental data for the impeller region, and the approach seems generally applicable for simulating gas-liquid stirred tanks.

  6. Bacterial bioleaching of low grade nickel limonite and saprolite ores by mixotrophic bacteria

    Directory of Open Access Journals (Sweden)

    Chaerun Siti Khodijah

    2016-01-01

    Full Text Available Utilization of indigenous bacteria should be considered to establish a successful biohydrometallurgical process. In this study, mixrotrophic iron-oxidizing bacterial consortia consisting of Comamonas testosteroni, Alicyclobacillus ferrooxydans and Pantoea septic which were isolated from Indonesian mineral ores were examined to determine their abilities to recover nickel from limonite and saprolite ores in the bioleaching experiments using stirred tank reactors. The nickel bioleaching experiments inoculated with the bacterial consortia were carried out using coarse limonite ores and weathered saprolite ores with pulp density of 10% w/v. Abiotic controls were also carried out replacing the inocula by the sterile medium. The bioleaching processes were monitored by measuring Ni and Fe contents and pH of the leaching solution as well as the total bacterial enzymatic activity measured as FDA hydrolytic activity. The effect of leaching on the mineralogy of laterite ores was investigated by the scanning electron microscope equipped with energy-dispersive spectroscopy (SEM-EDS and X-ray powder diffraction (XRD. After 28 days of incubation, the FDA hydrolytic activity was observed in both bioleaching experiments containing limonite (17.2 μg fluorescein/mL and saprolite ores (16.9 μg fluorescein/mL. The leached Ni and Fe in the bioleaching experiments containing limonite ores (30% Ni and 5.6% Fe was greater than that in abiotic controls (1% Ni and 0.1% Fe with the pH range of 2.5 to 3.5. However, the bacterial consortia were less capable of bioleaching of Ni (2.5% with the similar leached Fe (6% from the saprolite ores. In abiotic controls, the medium pH remained relatively constant (pH 6. It was concluded that these bacterial isolated as the consortium were capable of nickel bioleaching (precious metal more effectively than iron (gangue metal, thus being applicable to the commercial processing of the difficult-to-process low-grade nickel laterite ores

  7. Quantitative monitoring of microbial species during bioleaching of a copper concentrate

    Directory of Open Access Journals (Sweden)

    Sabrina Hedrich

    2016-12-01

    Full Text Available Monitoring of the microbial community in bioleaching processes is essential in order to control process parameters and enhance the leaching efficiency. Suitable methods are, however, limited as they are usually not adapted to bioleaching samples and often no taxon-specific assays are available in the literature for these types of consortia. Therefore, our study focused on the development of novel quantitative real-time PCR (qPCR assays for the quantification of Acidithiobacillus caldus, Leptospirillum ferriphilum, Sulfobacillus thermosulfidooxidans and Sulfobacillus benefaciens and comparison of the results with data from other common molecular monitoring methods in order to evaluate their accuracy and specificity. Stirred tank bioreactors for the leaching of copper concentrate, housing a consortium of acidophilic, moderately-thermophilic bacteria, relevant in several bioleaching operations, served as a model system. The microbial community analysis via qPCR allowed a precise monitoring of the evolution of total biomass as well as abundance of specific species. Data achieved by the standard fingerprinting methods, terminal restriction fragment length polymorphism (T-RFLP and capillary electrophoresis single strand conformation polymorphism (CE-SSCP on the same samples followed the same trend as qPCR data. The main added value of qPCR was, however, to provide quantitative data for each species whereas only relative abundance could be deduced from T-RFLP and CE-SSCP profiles. Additional value was obtained by applying two further quantitative methods which do not require nucleic acid extraction, total cell counting after SYBR Green staining and metal sulfide oxidation activity measurements via microcalorimetry. Overall, these complementary methods allow for an efficient quantitative microbial community monitoring in various bioleaching operations.

  8. Quantitative Monitoring of Microbial Species during Bioleaching of a Copper Concentrate

    Science.gov (United States)

    Hedrich, Sabrina; Guézennec, Anne-Gwenaëlle; Charron, Mickaël; Schippers, Axel; Joulian, Catherine

    2016-01-01

    Monitoring of the microbial community in bioleaching processes is essential in order to control process parameters and enhance the leaching efficiency. Suitable methods are, however, limited as they are usually not adapted to bioleaching samples and often no taxon-specific assays are available in the literature for these types of consortia. Therefore, our study focused on the development of novel quantitative real-time PCR (qPCR) assays for the quantification of Acidithiobacillus caldus, Leptospirillum ferriphilum, Sulfobacillus thermosulfidooxidans, and Sulfobacillus benefaciens and comparison of the results with data from other common molecular monitoring methods in order to evaluate their accuracy and specificity. Stirred tank bioreactors for the leaching of copper concentrate, housing a consortium of acidophilic, moderately thermophilic bacteria, relevant in several bioleaching operations, served as a model system. The microbial community analysis via qPCR allowed a precise monitoring of the evolution of total biomass as well as abundance of specific species. Data achieved by the standard fingerprinting methods, terminal restriction fragment length polymorphism (T-RFLP) and capillary electrophoresis single strand conformation polymorphism (CE-SSCP) on the same samples followed the same trend as qPCR data. The main added value of qPCR was, however, to provide quantitative data for each species whereas only relative abundance could be deduced from T-RFLP and CE-SSCP profiles. Additional value was obtained by applying two further quantitative methods which do not require nucleic acid extraction, total cell counting after SYBR Green staining and metal sulfide oxidation activity measurements via microcalorimetry. Overall, these complementary methods allow for an efficient quantitative microbial community monitoring in various bioleaching operations. PMID:28066365

  9. 大涡模拟搅拌槽内混合时间%Large Eddy Simulations of Mixing Time in a Stirred Tank

    Institute of Scientific and Technical Information of China (English)

    闵健; 高正明

    2006-01-01

    Large eddy simulations (LES) of mixing process in a stirred tank of 0.476m diameter with a 3-narrow blade hydrofoil CBY impeller were reported. The turbulent flow field and mixing time were calculated using LES with Smagorinsky-Lilly subgrid scale model. The impeller rotation was modeled using the sliding mesh technique. Better agreement of power demand and mixing time was obtained between the experimental and the LES prediction than that by the traditional Reynolds-averaged Navier-Stokes (RANS) approach. The curve of tracer response predicted by LES was in good agreement with the experimental. The results show that LES is a reliable tool to investigate the unsteady and quasi-periodic behavior of the turbulent flow in stirred tanks.

  10. Defluoridation of drinking water by electrocoagulation/electroflotation in a stirred tank reactor with a comparative performance to an external-loop airlift reactor

    OpenAIRE

    Essadki, Abdel Hafid; Gourich, Bouchaib; Vial, Christophe; Delmas, Henri; Bennajah, Mounir

    2009-01-01

    Defluoridation using batch electrocoagulation/electroflotation (EC/EF) was carried out in two reactors for comparison purpose: a stirred tank reactor (STR) close to a conventional EC cell and an external-loop airlift reactor (ELAR) that was recently described as an innovative reactor for EC. The respective influences of current density, initial concentration and initial pH on the efficiency of defluoridation were investigated. The same trends were observed in both reactors, but the efficiency...

  11. 搅拌釜中层流流场的模拟%Numerical simulation of laminar flow field in a stirred tank

    Institute of Scientific and Technical Information of China (English)

    范茏; 王卫京; 杨超; 毛在砂

    2004-01-01

    Stirred tanks are used extensively in process industry and one of the most commonly used impellers in stirred tanks is the Rushton disk turbine.Surprisingly few data are available regarding flow and mixing in stirred-tank reactors with Rushton turbine in the laminar regime,in particular the laminar flow in baffled tanks.In this paper,the laminar flow field in a baffled tank stirred by a standard Rushton turbine is simulated with the improved inner-outer iterative method.The non-inertial coordinate system is used for the impeller region,which is in turn used as the boundary conditions for iteration.It is found that the simulation results are in good agreement with previous experiments.In addition,the flow number and impeller power number calculated from the simulated flow field are in satisfactory agreement with experimental data.This numerical method allows prediction of flow structure requiring no experimental data as the boundary conditions and has the potential of being used to scale-up and design of related process equipment.

  12. Reuse of drinking water treatment residuals in a continuous stirred tank reactor for phosphate removal from urban wastewater.

    Science.gov (United States)

    Bai, Leilei; Wang, Changhui; Pei, Yuansheng; Zhao, Jinbo

    2014-01-01

    This work proposed a new approach of reusing drinking water treatment residuals (WTR) in a continuous stirred tank reactor (CSTR) to remove phosphate (P) from urban wastewater. The results revealed that the P removal efficiency of the WTR was more than 94% for urban wastewater, in the condition of initial P concentration (P0) of 10 mg L⁻¹, hydraulic retention time (HRT) of 2 h and WTR dosage (M0) of 10 g L⁻¹. The P mass transfer from the bulk to the solid-liquid interface in the CSTR system increased at lower P0, higher M0 and longer HRT. The P adsorption capacity of WTR from urban wastewater was comparable to that of the 201 × 4 resin and unaffected by ions competition. Moreover, WTR had a limited effect on the metals' (Fe, Al, Zn, Cu, Mn and Ni) concentrations of the urban wastewater. Based on the principle of waste recycling, the reuse of WTR in CSTR is a promising alternative technology for P removal from urban wastewater.

  13. Entropy production in a chemical system involving an autocatalytic reaction in an isothermal, continuous stirred tank reactor

    Science.gov (United States)

    Yoshida, Nobuo

    1990-02-01

    The rate of entropy production due to chemical reaction is calculated for various combinations of parameter values in the cubic autocatalator model in an isothermal, continuous stirred tank reactor (CSTR) proposed by Gray and Scott and by Escher and Ross. Values of the entropy production averaged over periods of limit cycle oscillations are compared with those in coexistent unstable stationary states. It is found that in ranges of the residence time over which there are limit cycles, the entropy production in coexisting stationary states increases as the residence time is shortened, i.e., as the system is removed farther from thermodynamic equilibrium. The average entropy production over a limit cycle is less than that in the corresponding stationary state over wide ranges of parameter values, but not necessarily for the whole oscillatory region. More specifically, the former inequality always prevails in ranges where the entropy production of stationary states is larger, i.e., the residence time is shorter, but in some cases the inequality is reversed in ranges of lower magnitudes of the entropy production.

  14. Quantifying the Reactive Uptake of OH by Organic Aerosols in aContinuous Flow Stirred Tank Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Che, Dung L.; Smith, Jared D.; Leone, Stephen R.; Ahmed, Musahid; Wilson, Kevin R.

    2009-03-01

    Here we report a new method for measuring the heterogeneous chemistry of submicron organic aerosol particles using a continuous flow stirred tank reactor. This approach is designed to quantify the real time heterogeneous kinetics, using a relative rate method, under conditions of low oxidant concentration and long reaction times that more closely mimic the real atmosphere. A general analytical expression, which couples the aerosol chemistry with the flow dynamics in the chamber is developed and applied to the heterogeneous oxidation of squalane particles by hydroxyl radicals (OH) in the presence of O2. The particle phase reaction is monitored via photoionization aerosol mass spectrometry and yields a reactive uptake coefficient of 0.51+-0.10, using OH concentrations of 1-7x108 molec cdot cm-3 and reaction times of 1.5+-3 hours. This uptake coefficient is larger than that found for the reaction carried out under high OH concentrations (~;;1x1010 molec cdot cm-3) and short reaction times in a flow tube reactor. This difference suggests that oxidant concentration and reaction time are not interchangeable quantities in reactions of organic aerosols with radicals. In general, this approach provides a new way to examine how the chemical aging of organic particles measured at short reaction times and high oxidant concentrations in flow tubes might differ from the long reaction times and low oxidant levels found in the real atmosphere.

  15. Investigations of the Gas-Liquid Multiphase System Involving Macro-Instability in a Baffled Stirred Tank Reactor

    Directory of Open Access Journals (Sweden)

    Shuo Zhang

    2016-01-01

    Full Text Available Bubble Sauter Mean Diameter (SMD in gas-liquid multiphase system is of particular interest and the quantification of gas characteristics is still a challenge today. In this contribution, multiphase Computational Fluid Dynamic (CFD simulations are combined with Population Balance Model (PBM to investigate the bubble SMD in baffled stirred tank reactor (STR. Hereby, special attention is given to the phenomenon known as the fluid macro-instability (MI, which is a large-scale low-frequency fluid velocity variation in baffled STRs, since the fluid MIs have a dominating influence on the bubble breakage and coalescence processes. The simulations, regarding the fluid velocity, are validated with Laser Doppler Anemometry (LDA experiments, in which the instant radial velocity is analyzed through Fast Fourier Transform (FFT spectrum. The frequency peaks of the fluid MIs are found both in the simulation and in the experiment with a high degree of accuracy. After the validation, quantitative predictions of overall bubble SMD with and without MIs are carried out. Due to the accurate prediction of the fluid field, the influence of the fluid MI to bubble SMD is presented. This result provides more adequate information for engineers working in the field of estimating bubble SMDs in baffled STRs.

  16. Fermentation characteristics in stirred-tank reactor of exopolysaccharides with hypolipidemic activity produced by Pleurotus geesteranus 5#

    Directory of Open Access Journals (Sweden)

    MAO DUOBIN

    2013-01-01

    Full Text Available In this study, the hypolipidemic effect of exopolysaccharides (EPS from Pleurotus geesteranus 5# fermenting liquor by the optimal culture conditions in a 5-L stirred-tank reactor was investigated. The hypolipidemic effect of the polysaccharide, investigated in streptozotocin induced diabetic mice, decreased plasma glucose, total cholesterol and triacylglycerol concentrations by 17.1 %, 18.8 % and 12.0 %, respectively. The results of the present investigation strongly demonstrate the potential of this polysaccharide to prevent hyperglycemia in the experimental animals. Under optimal culture conditions, the maximum concentrations of mycelial and EPS were 22.63 g/L after 7 d cultivation and 11.09 g/L after 10 d, respectively. Furthermore, the morphological parameters (i.e. mean diameter, circularity, roughness and compactness of the pellets and the broth viscosity were characterized. It was proved that compactness of the pellet morphology (R2=0.963, p<0.01 was significantly and positively determined with mycelial biomass. Moreover, mean diameter (R2=93.3, p<0.01 and broth viscosity (R2=0.950, p<0.01 were significantly and positively determined with EPS content.

  17. Investigation of hydroxyl radical reactions with o-xylene and m-xylene in a continuous stirred tank reactor

    Energy Technology Data Exchange (ETDEWEB)

    Gery, M.W.; Fox, D.L.; Kamens, R.M.; Stockburger, L.

    1987-04-01

    The gas-phase reactions of hydroxyl radicals with o-xylene and m-xylene were studied in a continuous stirred tank reactor. Gas and aerosol products accounted for 65-85% of the reacted carbon. Approximately 19 and 13% of the original o-xylene and m-xylene oxidation were estimated to have occurred through methyl hydrogen abstraction by OH, primarily leading to methylbenzyl nitrates and tolualdehydes. The remaining mass reacted through the OH addition pathway forming dimethylphenols, nitrodimethylphenols, nitroxylenes, and stable products resulting from reaction of metastable O/sub 2/-OH adducts. For o-xylene, the ratio of the rate constants for formation of nitroxylenes vs. dimethylphenols was estimated to be 5.9 x 10/sup 4/, while the same value for m-xylene was only about 1.0 x 10/sup 4/. The ratios of the dimethylphenol formation rates to the oxygen addition rates were found to be greater than or equal to 0.15 for o-xylene and 0.27 for m-xylene. 44 references, 3 figures, 4 tables.

  18. A comparison of mass transfer coefficients between trickle-bed, hollow fiber membrane and stirred tank reactors.

    Science.gov (United States)

    Orgill, James J; Atiyeh, Hasan K; Devarapalli, Mamatha; Phillips, John R; Lewis, Randy S; Huhnke, Raymond L

    2013-04-01

    Trickle-bed reactor (TBR), hollow fiber membrane reactor (HFR) and stirred tank reactor (STR) can be used in fermentation of sparingly soluble gasses such as CO and H2 to produce biofuels and bio-based chemicals. Gas fermenting reactors must provide high mass transfer capabilities that match the kinetic requirements of the microorganisms used. The present study compared the volumetric mass transfer coefficient (K(tot)A/V(L)) of three reactor types; the TBR with 3 mm and 6 mm beads, five different modules of HFRs, and the STR. The analysis was performed using O2 as the gaseous mass transfer agent. The non-porous polydimethylsiloxane (PDMS) HFR provided the highest K(tot)A/V(L) (1062 h(-1)), followed by the TBR with 6mm beads (421 h(-1)), and then the STR (114 h(-1)). The mass transfer characteristics in each reactor were affected by agitation speed, and gas and liquid flow rates. Furthermore, issues regarding the comparison of mass transfer coefficients are discussed.

  19. Increased production of recombinant prourokinase with porous microcarrier cell culture by periodic pressure oscillation in a stirred tank reactor

    Institute of Scientific and Technical Information of China (English)

    Hu Xianwen; Gao Lihua; Li Zuohu; Xiao Chengzu; Xu Zhaoping

    2006-01-01

    An rCHO cell line expressing recombinant human prourokinase (pro-UK at the level of 5μg/106cells/d was cultivated on Cytopore cellulose porous microcarriers in a 7.5L Biostat CT stirred tank reactor. A periodic pressure oscillation of 0.04 MPa and 0.04 Hz was adopted to introduce a physical stimulus on the rCHO cells and to improve mass transfer characteristic between cells and medium in the process of porous microcarrier CHO cell culture. Compared to constant pressure culture, the oscillation culture didn't influence specific cell growth rate significantly, but could enhance the pro-UK specific production by 10%~40%, and reduce production of lactate by 10%~30%. In the perfusion culture of recombinant CHO cell with serum-free medium for 67 days, cell density could reach 2.64×107/ml, the maximal prourokinase concentration in harvested supernatant was about 118mg/L, a total of 21.1 grams of prourokinase was produced in 313 liters of supernatant. In conclusion, the perfusion cell culture with periodic pressure oscillation can enhance the production of recombinant protein and increase the reactor specific productivity.

  20. Modelling of the Bubble Size Distribution in an Aerated Stirred Tank: Theoretical and Numerical Comparison of Different Breakup Models

    Directory of Open Access Journals (Sweden)

    Kálal Zbyněk

    2014-09-01

    Full Text Available The main topic of this study is the mathematical modelling of bubble size distributions in an aerated stirred tank using the population balance method. The air-water system consisted of a fully baffled vessel with a diameter of 0.29 m, which was equipped with a six-bladed Rushton turbine. The secondary phase was introduced through a ring sparger situated under the impeller. Calculations were performed with the CFD software CFX 14.5. The turbulent quantities were predicted using the standard k-ε turbulence model. Coalescence and breakup of bubbles were modelled using the MUSIG method with 24 bubble size groups. For the bubble size distribution modelling, the breakup model by Luo and Svendsen (1996 typically has been used in the past. However, this breakup model was thoroughly reviewed and its practical applicability was questioned. Therefore, three different breakup models by Martínez-Bazán et al. (1999a, b, Lehr et al. (2002 and Alopaeus et al. (2002 were implemented in the CFD solver and applied to the system. The resulting Sauter mean diameters and local bubble size distributions were compared with experimental data.

  1. Fermentative hydrogen production from beet sugar factory wastewater treatment in a continuous stirred tank reactor using anaerobic mixed consortia

    Institute of Scientific and Technical Information of China (English)

    Gefu ZHU; Chaoxiang LIU; Jianzheng LI; Nanqi REN; Lin LIU; Xu HUANG

    2013-01-01

    A low pH, ethanol-type fermentation process was evaluated for wastewater treatment and bio-hydrogen production from acidic beet sugar factory wastewater in a continuous stirred tank reactor (CSTR) with an effective volume of 9.6 L by anaerobic mixed cultures in this present study. After inoculating with aerobic activated sludge and operating at organic loading rate (OLR) of 12 kgCOD·m-3·d-1, HRT of 8h, and temperature of 35℃ for 28 days, the CSTR achieved stable ethanol-type fermentation. When OLR was further increased to 18 kgCOD·m-3·d-1, on the 53rd day, ethanol-type fermentation dominant microflora was enhanced. The liquid fermentation products, including volatile fatty acids (VFAs) and ethanol, stabilized at 1493mg·L-1 in the bioreactor. Effluent pH, oxidation-reduction potential (ORP), and alkalinity ranged at 4.1-4.5, -250-(-290) mV, and 230-260mgCaCO3·L-1. The specific hydrogen production rate of anaerobic activated sludge was 0.1 L'gMLVSS-1· d-1 and the COD removal efficiency was 45%. The experimental results showed that the CSTR system had good operation stability and microbial activity, which led to high substrate conversion rate and hydrogen production ability.

  2. Production of bioethanol by direct bioconversion of oil-palm industrial effluent in a stirred-tank bioreactor.

    Science.gov (United States)

    Alam, Md Zahangir; Kabbashi, Nassereldeen A; Hussin, S Nahdatul I S

    2009-06-01

    The purpose of this study was to evaluate the feasibility of producing bioethanol from palm-oil mill effluent generated by the oil-palm industries through direct bioconversion process. The bioethanol production was carried out through the treatment of compatible mixed cultures such as Thrichoderma harzianum, Phanerochaete chrysosporium, Mucor hiemalis, and yeast, Saccharomyces cerevisiae. Simultaneous inoculation of T. harzianum and S. cerevisiae was found to be the mixed culture that yielded the highest ethanol production (4% v/v or 31.6 g/l). Statistical optimization was carried out to determine the operating conditions of the stirred-tank bioreactor for maximum bioethanol production by a two-level fractional factorial design with a single central point. The factors involved were oxygen saturation level (pO(2)%), temperature, and pH. A polynomial regression model was developed using the experimental data including the linear, quadratic, and interaction effects. Statistical analysis showed that the maximum ethanol production of 4.6% (v/v) or 36.3 g/l was achieved at a temperature of 32 degrees C, pH of 6, and pO(2) of 30%. The results of the model validation test under the developed optimum process conditions indicated that the maximum production was increased from 4.6% (v/v) to 6.5% (v/v) or 51.3 g/l with 89.1% chemical-oxygen-demand removal.

  3. Application of a continuously stirred tank bioreactor (CSTR) for bioremediation of hydrocarbon-rich industrial wastewater effluents

    Energy Technology Data Exchange (ETDEWEB)

    Gargouri, Boutheina; Karray, Fatma; Mhiri, Najla; Aloui, Fathi [Laboratoire des Bioprocedes Environnementaux, Pole d' Excellence Regional AUF-LBPE, Centre de Biotechnologie de Sfax, Universite de Sfax, BP 1117, 3018 Sfax (Tunisia); Sayadi, Sami, E-mail: sami.sayadi@cbs.rnrt.tn [Laboratoire des Bioprocedes Environnementaux, Pole d' Excellence Regional AUF-LBPE, Centre de Biotechnologie de Sfax, Universite de Sfax, BP 1117, 3018 Sfax (Tunisia)

    2011-05-15

    A continuously stirred tank bioreactor (CSTR) was used to optimize feasible and reliable bioprocess system in order to treat hydrocarbon-rich industrial wastewaters. A successful bioremediation was developed by an efficient acclimatized microbial consortium. After an experimental period of 225 days, the process was shown to be highly efficient in decontaminating the wastewater. The performance of the bioaugmented reactor was demonstrated by the reduction of COD rates up to 95%. The residual total petroleum hydrocarbon (TPH) decreased from 320 mg TPH l{sup -1} to 8 mg TPH l{sup -1}. Analysis using gas chromatography-mass spectrometry (GC-MS) identified 26 hydrocarbons. The use of the mixed cultures demonstrated high degradation performance for hydrocarbons range n-alkanes (C10-C35). Six microbial isolates from the CSTR were characterized and species identification was confirmed by sequencing the 16S rRNA genes. The partial 16S rRNA gene sequences demonstrated that 5 strains were closely related to Aeromonas punctata (Aeromonas caviae), Bacillus cereus, Ochrobactrum intermedium, Stenotrophomonas maltophilia and Rhodococcus sp. The 6th isolate was affiliated to genera Achromobacter. Besides, the treated wastewater could be considered as non toxic according to the phytotoxicity test since the germination index of Lepidium sativum ranged between 57 and 95%. The treatment provided satisfactory results and presents a feasible technology for the treatment of hydrocarbon-rich wastewater from petrochemical industries and petroleum refineries.

  4. Lipozyme IM-catalyzed interesterification for the production of margarine fats in a 1 kg scale stirred tank reactor

    DEFF Research Database (Denmark)

    Zhang, Hong; Xu, Xuebing; Mu, Huiling

    2000-01-01

    Lipozyme IM-catalyzed interesterification of the oil blend between palm stearin and coconut oil (75/25 w/w) was studied for the production of margarine fats in a 1 kg scale batch stirred tank reactor. Parameters such as lipase load, water content, temperature, and reaction time were investigated......, 42, 44, and 46 increased by 1.1, 1.6, 6.8, 16.7, and 6.5%, respectively, in comparison with the increase of those species after chemical interesterification, 0.2, 1.5, 6.5, 17.0, and 9.2%, respectively. Lipase load and reaction time had great influence on the degree of interesterification. A Lipozyme...... by equivalent carbon number (ECN), namely ECN34, 36, 48, and 50, decreased by 6.0, 5.9, 5,8, and 13.7%, respectively, after enzymatic interesterification, similar to the reduction of those species after chemical interesterification, 6.6, 6.0, 7.1, and 12.9%, respectively. On the other hand, those of ECN38, 40...

  5. Lipozyme IM-catalyzed interesterification for the production of margarine fats in a 1 kg scale stirred tank reactor

    DEFF Research Database (Denmark)

    Zhang, Hong; Xu, Xuebing; Mu, Huiling

    2000-01-01

    Lipozyme IM-catalyzed interesterification of the oil blend between palm stearin and coconut oil (75/25 w/w) was studied for the production of margarine fats in a 1 kg scale batch stirred tank reactor. Parameters such as lipase load, water content, temperature, and reaction time were investigated......, 42, 44, and 46 increased by 1.1, 1.6, 6.8, 16.7, and 6.5%, respectively, in comparison with the increase of those species after chemical interesterification, 0.2, 1.5, 6.5, 17.0, and 9.2%, respectively. Lipase load and reaction time had great influence on the degree of interesterification. A Lipozyme...... by equivalent carbon number (ECN), namely ECN34, 36, 48, and 50, decreased by 6.0, 5.9, 5.8, and 13.7%, respectively, after enzymatic interesterification, similar to the reduction of those species after chemical interesterification, 6.6, 6.0, 7.1, and 12.9%, respectively. On the other hand, those of ECN38, 40...

  6. The Reduced Rank of Ensemble Kalman Filter to Estimate the Temperature of Non Isothermal Continue Stirred Tank Reactor

    Directory of Open Access Journals (Sweden)

    Erna Apriliani

    2011-01-01

    Full Text Available Kalman filter is an algorithm to estimate the state variable of dynamical stochastic system. The square root ensemble Kalman filter is an modification of Kalman filter. The square root ensemble Kalman filter is proposed to keep the computational stability and reduce the computational time. In this paper we study the efficiency of the reduced rank ensemble Kalman filter. We apply this algorithm to the non isothermal continue stirred tank reactor problem. We decompose the covariance of the ensemble estimation by using the singular value decomposition (the SVD, and then we reduced the rank of the diagonal matrix of those singular values. We make a simulation by using Matlab program. We took some the number of ensemble such as 100, 200 and 500. We compared the computational time and the accuracy between the square root ensemble Kalman filter and the ensemble Kalman filter. The reduced rank ensemble Kalman filter can’t be applied in this problem because the dimension of state variable is too less.

  7. Decolourization of anaerobically digested and polyaluminium chloride treated distillery spentwash in a fungal stirred tank aerobic reactor.

    Science.gov (United States)

    Singh, S S; Dikshit, A K

    2011-11-01

    Decolourization of anaerobically digested and polyaluminium chloride treated distillery spentwash was studied in a fungal stirred tank aerobic reactor without dilution of wastewater. Aspergillus niger isolate IITB-V8 was used as the fungal inoculum. The main objectives of the study were to optimize the stirrer speed for achieving maximum decolourization and to determine the kinetic parameters. A mathematical model was developed to describe the batch culture kinetics. Volumetric oxygen transfer coefficient (k (L) a) was obtained using dynamic method. The maximum specific growth rate and growth yield of fungus were determined using Logistic equation and using Luedeking-Piret equation. 150 rpm was found to be optimum stirrer speed for overall decolourization of 87%. At the optimum stirrer speed, volumetric oxygen transfer coefficient (k (L) a) was 0.4957 min(-1) and the maximum specific growth rate of fungus was 0.224 h(-1). The values of yield coefficient (Y ( x/s)) and maintenance coefficient (m (s)) were found to be 0.48 g cells (g substrate)(-1) and 0.015 g substrate (g cells)(-1) h(-1).

  8. Effect of Hydraulic Retention Time on Anaerobic Digestion of Wheat Straw in the Semicontinuous Continuous Stirred-Tank Reactors

    Science.gov (United States)

    Shi, Xiao-Shuang; Yu, Jun-Hong; Yin, Hua; Hu, Shu-Min; Huang, Shu-Xia

    2017-01-01

    Three semicontinuous continuous stirred-tank reactors (CSTR) operating at mesophilic conditions (35°C) were used to investigate the effect of hydraulic retention time (HRT) on anaerobic digestion of wheat straw. The results showed that the average biogas production with HRT of 20, 40, and 60 days was 46.8, 79.9, and 89.1 mL/g total solid as well as 55.2, 94.3, and 105.2 mL/g volatile solids, respectively. The methane content with HRT of 20 days, from 14.2% to 28.5%, was the lowest among the three reactors. The pH values with HRT of 40 and 60 days were in the acceptable range compared to that with HRT of 20 days. The propionate was dominant in the reactor with HRT of 20 days, inhibiting the activities of methanogens and causing the lower methane content in biogas. The degradation of cellulose, hemicellulose, and crystalline cellulose based on XRD was also strongly influenced by HRTs. PMID:28589134

  9. Serial completely stirred tank reactors for improving biogas production and substance degradation during anaerobic digestion of corn stover.

    Science.gov (United States)

    Li, YuQian; Liu, ChunMei; Wachemo, Akiber Chufo; Yuan, HaiRong; Zou, DeXun; Liu, YanPing; Li, XiuJin

    2017-07-01

    Several completely stirred tank reactors (CSTR) connected in series for anaerobic digestion of corn stover were investigated in laboratory scale. Serial anaerobic digestion systems operated at a total HRT of 40days, and distribution of HRT are 10+30days (HRT10+30d), 20+20days (HRT20+20d), and 30+10days (HRT30+10d) were compared to a conventional one-step CSTR at the same HRT of 40d. The results showed that in HRT10+30d serial system, the process became very unstable at organic load of 50gTS·L(-1). The HRT20+20d and HRT30+10d serial systems improved methane production by 8.3-14.6% compared to the one-step system in all loads of 50, 70, 90gTS·L(-1). The conversion rates of total solid, cellulose, and hemicellulose were increased in serial anaerobic digestion systems compared to single system. The serial systems showed more stable process performance in high organic load. HRT30+10d system showed the best biogas production and conversions among all systems. Copyright © 2017. Published by Elsevier Ltd.

  10. Production of biohythane from food waste via an integrated system of continuously stirred tank and anaerobic fixed bed reactors.

    Science.gov (United States)

    Yeshanew, Martha M; Frunzo, Luigi; Pirozzi, Francesco; Lens, Piet N L; Esposito, Giovanni

    2016-11-01

    The continuous production of biohythane (mixture of biohydrogen and methane) from food waste using an integrated system of a continuously stirred tank reactor (CSTR) and anaerobic fixed bed reactor (AFBR) was carried out in this study. The system performance was evaluated for an operation period of 200days, by stepwise shortening the hydraulic retention time (HRT). An increasing trend of biohydrogen in the CSTR and methane production rate in the AFBR was observed regardless of the HRT shortening. The highest biohydrogen yield in the CSTR and methane yield in the AFBR were 115.2 (±5.3)L H2/kgVSadded and 334.7 (±18.6)L CH4/kgCODadded, respectively. The AFBR presented a stable operation and excellent performance, indicated by the increased methane production rate at each shortened HRT. Besides, recirculation of the AFBR effluent to the CSTR was effective in providing alkalinity, maintaining the pH in optimal ranges (5.0-5.3) for the hydrogen producing bacteria.

  11. Application of a continuously stirred tank bioreactor (CSTR) for bioremediation of hydrocarbon-rich industrial wastewater effluents.

    Science.gov (United States)

    Gargouri, Boutheina; Karray, Fatma; Mhiri, Najla; Aloui, Fathi; Sayadi, Sami

    2011-05-15

    A continuously stirred tank bioreactor (CSTR) was used to optimize feasible and reliable bioprocess system in order to treat hydrocarbon-rich industrial wastewaters. A successful bioremediation was developed by an efficient acclimatized microbial consortium. After an experimental period of 225 days, the process was shown to be highly efficient in decontaminating the wastewater. The performance of the bioaugmented reactor was demonstrated by the reduction of COD rates up to 95%. The residual total petroleum hydrocarbon (TPH) decreased from 320 mg TPH l(-1) to 8 mg TPH l(-1). Analysis using gas chromatography-mass spectrometry (GC-MS) identified 26 hydrocarbons. The use of the mixed cultures demonstrated high degradation performance for hydrocarbons range n-alkanes (C10-C35). Six microbial isolates from the CSTR were characterized and species identification was confirmed by sequencing the 16S rRNA genes. The partial 16S rRNA gene sequences demonstrated that 5 strains were closely related to Aeromonas punctata (Aeromonas caviae), Bacillus cereus, Ochrobactrum intermedium, Stenotrophomonas maltophilia and Rhodococcus sp. The 6th isolate was affiliated to genera Achromobacter. Besides, the treated wastewater could be considered as non toxic according to the phytotoxicity test since the germination index of Lepidium sativum ranged between 57 and 95%. The treatment provided satisfactory results and presents a feasible technology for the treatment of hydrocarbon-rich wastewater from petrochemical industries and petroleum refineries.

  12. Efficient azo dye decolorization in a continuous stirred tank reactor (CSTR) with built-in bioelectrochemical system.

    Science.gov (United States)

    Cui, Min-Hua; Cui, Dan; Gao, Lei; Cheng, Hao-Yi; Wang, Ai-Jie

    2016-10-01

    A continuous stirred tank reactor with built-in bioelectrochemical system (CSTR-BES) was developed for azo dye Alizarin Yellow R (AYR) containing wastewater treatment. The decolorization efficiency (DE) of the CSTR-BES was 97.04±0.06% for 7h with sludge concentration of 3000mg/L and initial AYR concentration of 100mg/L, which was superior to that of the sole CSTR mode (open circuit: 54.87±4.34%) and the sole BES mode (without sludge addition: 91.37±0.44%). The effects of sludge concentration and sodium acetate (NaAc) concentration on azo dye decolorization were investigated. The highest DE of CSTR-BES for 4h was 87.66±2.93% with sludge concentration of 12,000mg/L, NaAc concentration of 2000mg/L and initial AYR concentration of 100mg/L. The results in this study indicated that CSTR-BES could be a practical strategy for upgrading conventional anaerobic facilities against refractory wastewater treatment.

  13. Biohydrogen production in a continuous stirred tank bioreactor from synthesis gas by anaerobic photosynthetic bacterium: Rhodopirillum rubrum.

    Science.gov (United States)

    Younesi, Habibollah; Najafpour, Ghasem; Ku Ismail, Ku Syahidah; Mohamed, Abdul Rahman; Kamaruddin, Azlina Harun

    2008-05-01

    Hydrogen may be considered a potential fuel for the future since it is carbon-free and oxidized to water as a combustion product. Bioconversion of synthesis gas (syngas) to hydrogen was demonstrated in continuous stirred tank bioreactor (CSTBR) utilizing acetate as a carbon source. An anaerobic photosynthetic bacterium, Rhodospirillum rubrum catalyzed water-gas shift reaction which was applied for the bioconversion of syngas to hydrogen. The continuous fermentation of syngas in the bioreactor was continuously operated at various gas flow rates and agitation speeds, for the period of two months. The gas flow rates were varied from 5 to 14 ml/min. The agitation speeds were increasingly altered in the range of 150-500 rpm. The pH and temperature of the bioreactor was set at 6.5 and 30 degrees C. The liquid flow rate was kept constant at 0.65 ml/min for the duration of 60 days. The inlet acetate concentration was fed at 4 g/l into the bioreactor. The hydrogen production rate and yield were 16+/-1.1 mmol g(-1)cell h(-1) and 87+/-2.4% at fixed agitation speed of 500 rpm and syngas flow rate of 14 ml/min, respectively. The mass transfer coefficient (KLa) at this condition was approximately 72.8h(-1). This new approach, using a biocatalyst was considered as an alternative method of conventional Fischer-Tropsch synthetic reactions, which were able to convert syngas into hydrogen.

  14. Perancangan dan Simulasi MRAC untui Proses Pengendalian Temperatur pada Continuous Stirred Tank Reactor (CSTR

    Directory of Open Access Journals (Sweden)

    Amelia Sylvia

    2014-03-01

    Full Text Available Temperatur merupakan salah satu variabel proses dasar yang dikendalikan untuk menjaga suhu cairan di dalam reaktor. Model Reference Adaptive Controller (MRAC dengan MIT rule dipilih untuk mencapai spesifikasi respon yang diinginkan pada CSTR. Beban yang bervariasi berupa debit aliran likuid yang masuk ke dalam reaktor dapat menyebabkan perubahan parameter yang mempengaruhi perubahan temperatur output produk pada CSTR. Sebuah simulasi dilakukan dengan menggunakan MATLAB dan hasilnya dianalisa. Respon plant dapat melakukan adaptasi parameter – parameter kontrolernya cukup baik pada nilai gain adaptasi dengan rentang 0.00000010000 sampai 0.00000000001. Waktu yang dibutuhkan untuk mengatasi beban yang bervariasi berupa debit aliran yang masuk ke dalam reaktor dengan nilai yang maksimal (1.5 m^3/min menghasilkan respon plant lebih cepat 42 detik dari pada debit aliran masuk dengan nilai yang nominal (1 m^3/min 63 detik dan minimal (0.5 m^3/min 75 detik.

  15. Analysis of metal Bioleaching from thermal power plant fly ash by Aspergillus niger 34770 culture supernatant and reduction of phytotoxicity during the process.

    Science.gov (United States)

    Jadhav, Umesh U; Hocheng, Hong

    2015-01-01

    Aspergillus niger culture supernatant is used for bioleaching process. Before starting bioleaching process, fly ash was washed with distilled water. This removed 100 % sodium, 47 % (±0.45) boron, 38.07 % (±0.12) calcium, 29.89 % (±0.78) magnesium, and 11.8 % (±0.05) potassium. The pH was reduced from 10.5 to 8.5 after water washing. During bioleaching process, around 100 % metal removal was achieved in 4 h for all metals except chromium 93 % (±1.18), nickel 83 % (±0.32), arsenic 78 % (±0.52), and lead 70 % (±0.20). The process parameters including temperature, shaking speed, and solid/liquid ratio were optimized for bioleaching process. Experiments were conducted to evaluate effect of fly ash on growth of mung bean (Vigna radiata). At 20 g/100 ml fly ash concentration no germination of V. radiata seeds was observed. With an increasing concentration of untreated fly ash, a gradual decrease in root/shoot length was observed. After bioleaching process 78 % (±0.19) germination of V. radiata was observed with 20 g/100 ml fly ash. This study will help to develop an efficient process to remove the toxic metals from fly ash.

  16. ENVIRONMENTAL AND PROCESS PARAMETERS OF METHANE FERMENTATION IN CONTINUOSLY STIRRED TANK REACTOR (CSTR

    Directory of Open Access Journals (Sweden)

    Kamil Kozłowski

    2016-12-01

    Full Text Available A key indicator of methane fermentation process which influences the cost-effectiveness of the biogas plant is efficient production of methane per 1 m3 of reactor. It depends on the proper selection of environmental and process parameters. This article present collected and analyzed the effect of the most important parameters of continuous methane fermentation (CSTR, which include temperature, pH, nutrient content and the C/N ratio in the feed medium, the presence of inhibitors, and the volume load of reactor, retention time and mixing of digestion reactor. Still, the impact of many factors remain unknown, hence there is a need for more comprehensive studies.

  17. Bioleaching of Minerals

    Energy Technology Data Exchange (ETDEWEB)

    F. Roberto

    2002-02-01

    Bioleaching is the term used to describe the microbial dissolution of metals from minerals. The commercial bioleaching of metals, particularly those hosted in sulfide minerals, is supported by the technical disciplines of biohydrometallurgy, hydrometallurgy, pyrometallurgy, chemistry, electrochemistry, and chemical engineering. The study of the natural weathering of these same minerals, above and below ground, is also linked to the fields of geomicrobiology and biogeochemistry. Studies of abandoned and disused mines indicate that the alterations of the natural environment due to man's activities leave as remnants microbiological activity that continues the biologically mediated release of metals from the host rock (acid rock drainage; ARD). A significant fraction of the world's copper, gold and uranium is now recovered by exploiting native or introduced microbial communities. While some members of these unique communities have been extensively studied for the past 50 years, our knowledge of the composition of these communities, and the function of the individual species present remains relatively limited. Nevertheless, bioleaching represents a major strategy in mineral resource recovery whose importance will increase as ore reserves decline in quality, become more difficult to process (due to increased depth, increased need for comminution, for example), and as environmental considerations eliminate traditional physical processes such as smelting, which have served the mining industry for hundreds of years.

  18. 双层桨搅拌槽内流场的数值模拟%Numerical simulation of fluid flow in stirred tank with double impellers

    Institute of Scientific and Technical Information of China (English)

    张少坤; 尹侠

    2011-01-01

    利用Fluent软件对双层六直叶涡轮桨搅拌槽内的流场进行整体数值模拟,选用标准湍流模型及滑移网格法,考察搅拌桨高度对流场结构的影响,模拟得到搅拌槽内的流场分布和功率消耗,并同文献试验结果进行对比.结果表明:桨叶的空间位置的变化对搅拌槽流场性能的影响是非常明显的,改变双层桨叶位置分别产生了平行流、合并流和分散流,模拟成功预测了搅拌槽内速度分布和漩涡位置,3种流型的功率消耗存在较大的差异,平行流时的功耗最大.%The fluid flow in stirred tank with dual six-blade Rushton turbine was numerically simulated using fluent software. The turbulent model and sliding meshes were used in the simulation. The effects of the span of the impellers on the fluid flow were analyzed.The flow structure of stirred tank and power consumption was obtained,and compared with literature test results. The research indicates that the position of impeller is main influencing factor for flow structure in the stirred tank, parallel flow, merging flow and diverging flow were obtained by changing the position of impellers, vortex position and velocity distribution were also predicated successfully. Power consumption of three kinds of flow pattern is very difference,power consumption of parallel flow is the largest.

  19. Solid-Liquid Dispersion in a Stirred Tank%固-液搅拌槽的分散性能

    Institute of Scientific and Technical Information of China (English)

    张优; 尹喜祥; 黄雄斌

    2011-01-01

    在直径为0.478 m的立式搅拌槽中,采用高岭土和水为物料,比较了四斜叶、六直叶涡轮等8种桨的固-液分散性能及搅拌功率(P)、桨组合形式对分散性能的影响规律.结果表明,8种桨中分散效果最好的是六直叶涡轮桨和四斜叶桨,分散速率最快的是两叶CBY桨;分散速率与P1.08成正比;分散前期,搅拌功率增加,相对分散效果Y随之提高,当Y达到0.999以上,提高搅拌功率对搅拌效果几乎不起作用;采用分散速率较快(两叶CBY桨)与分散效果较好(四斜叶桨)的双桨组合,更适于连续操作过程.%The solid-liquid dispersion property by eight types of impeller such as four-pitched-blade turbine (PBT), Rushton turbine (RT), etc, and the influences of stirring power and impeller combinations on dispersion property were studied in a vertical stirred tank with diameter of 0.478 m. Kaolin particles were chosen as the particulate material to be dispersed in the water. The experimental results show that PBT and RT have the optimum dispersion performance, while the 2-blade CBY propeller has the shortest dispersion time. The dispersion rate is in the direct ratio of 1.08 to the stirring power. In the beginning period, the relative dispersion performance Y increases with the stirring power, but the stirring power has little influence on the dispersion performance when the relative dispersion performance Y is more than 0.999. The results also reveal that the combination of a bottom 2-blade CBY and an upper PBT has a clear advantage in continuous operation.

  20. High-density mammalian cell cultures in stirred-tank bioreactor without external pH control.

    Science.gov (United States)

    Xu, Sen; Chen, Hao

    2016-08-10

    Maintaining desired pH is a necessity for optimal cell growth and protein production. It is typically achieved through a two-sided pH control loop on the bioreactor controller. Here we investigated cell culture processes with minimum or no pH control and demonstrated that high-density mammalian cell cultures could be maintained for long-term protein production without pH control. The intrinsic interactions between pCO2, lactate, and pH were leveraged to maintain culture pH. Fed-batch cultures at the same lower pH limit of 6.75 but different upper pH limits (7.05, 7.30, 7.45, 7.65) were evaluated in the 3L bioreactors and comparable results were obtained. Neither CO2 sparging nor base addition was required to control pH in the pH range of 6.75-7.65. The impact of sparger configurations (drilled hole sparger vs. frit sparger) and scales (3L vs. 200L) on CO2 accumulation and culture pH was also demonstrated. The same principle was applied in two perfusion cultures with steady state cell densities at 42.5±3.3 or 68.3±6.0×10(6)cells/mL with low cell specific perfusion rates (15±2 to 23±3pL/cell/day), achieving up to 1.9±0.1g/L/day bioreactor productivity. Culture pH level in the 3L perfusion bioreactors was steadily maintained by controlling the residual lactate and pCO2 levels without the requirement of external pH control for up to 40days with consistent productivity and product quality. Furthermore, culture pH could be potentially modulated via adjusting residual glucose levels and CO2 stripping capability in perfusion cultures. To the best of our knowledge, this is the first time a systematic study was performed to evaluate the long-term cell cultivation and protein production in stirred-tank bioreactors without external pH control.

  1. Experimental data and numerical predictions of a single-phase flow in a batch square stirred tank reactor with a rotating cylinder agitator

    Science.gov (United States)

    Escamilla-Ruíz, I. A.; Sierra-Espinosa, F. Z.; García, J. C.; Valera-Medina, A.; Carrillo, F.

    2017-09-01

    Single-phase flows in stirred tank reactors have useful characteristics for a wide number of industrial applications. Usually, reactors are cylindrical vessels and complex impeller designs, which are often highly energy consuming and produce complicated flow patterns. Therefore, a novel configuration consisting of a square stirred tank reactor is proposed in this study with potential advantages over conventional reactors. In the present work hydrodynamics and turbulence have been studied for a single-phase flow in steady state operating in batch condition. The flow was induced by drag from a rotating cylinder with two diameters. The effects of drag from the stirrer as well as geometrical parameters of the system on the hydrodynamic behavior were investigated using Computational Fluids Dynamics (CFD) and non-intrusive Laser Doppler Anemometry, (LDA). Data obtained from LDA measurements were used for the validation of the CFD simulations, and to detecting the macro-instabilities inside the tank, based on the time series analysis for three rotational speeds N = 180, 1000 and 2000 rpm. The numerical results revealed the formation of flow patterns and macro-vortex structures in the upper part of the tank as consequence of the Reynolds number and the stream discharge emanated from the cylindrical stirrer. Moreover, increasing the cylinder diameter has an impact on the number of recirculation loops as well as the energy consumption of the entire system showing better performance in the presence of turbulent flows.

  2. Experimental data and numerical predictions of a single-phase flow in a batch square stirred tank reactor with a rotating cylinder agitator

    Science.gov (United States)

    Escamilla-Ruíz, I. A.; Sierra-Espinosa, F. Z.; García, J. C.; Valera-Medina, A.; Carrillo, F.

    2017-04-01

    Single-phase flows in stirred tank reactors have useful characteristics for a wide number of industrial applications. Usually, reactors are cylindrical vessels and complex impeller designs, which are often highly energy consuming and produce complicated flow patterns. Therefore, a novel configuration consisting of a square stirred tank reactor is proposed in this study with potential advantages over conventional reactors. In the present work hydrodynamics and turbulence have been studied for a single-phase flow in steady state operating in batch condition. The flow was induced by drag from a rotating cylinder with two diameters. The effects of drag from the stirrer as well as geometrical parameters of the system on the hydrodynamic behavior were investigated using Computational Fluids Dynamics (CFD) and non-intrusive Laser Doppler Anemometry, (LDA). Data obtained from LDA measurements were used for the validation of the CFD simulations, and to detecting the macro-instabilities inside the tank, based on the time series analysis for three rotational speeds N = 180, 1000 and 2000 rpm. The numerical results revealed the formation of flow patterns and macro-vortex structures in the upper part of the tank as consequence of the Reynolds number and the stream discharge emanated from the cylindrical stirrer. Moreover, increasing the cylinder diameter has an impact on the number of recirculation loops as well as the energy consumption of the entire system showing better performance in the presence of turbulent flows.

  3. CFD Simulation of Mixing in a Stirred Tank with Multiple Hydrofoil Impellers%多层翼形桨搅拌槽内混合过程的CFD模拟

    Institute of Scientific and Technical Information of China (English)

    闵健; 高正明; 施力田

    2005-01-01

    The mixing process in a stirred tank of 0.476 m diameter with single, dual and triple 3-narrow blade hydrofoil CBY impellers was numerically simulated by using computational fluid dynamics (CFD) package FLU-ENT6.1. The multi-reference frame (MRF) and standard k-ε turbulent model were used in the simulation. The shaft power and the mixing time predicted by CFD were in good agreement with the experiment. The effects of tracer feeding and detecting positions on mixing time were investigated. The results are of importance to the optimum design of industrial stirred tank/reactors.

  4. Effect of noise correlation on noise-induced oscillation frequency in the photosensitive Belousov-Zhabotinsky reaction in a continuous stirred tank reactor.

    Science.gov (United States)

    Simakov, David S A; Pérez-Mercader, Juan

    2013-12-27

    We report on the experimental study of noise-induced oscillations in the photosensitive Ru(bpy)3(2+)-catalyzed Belousov-Zhabotinsky reaction in a continuous stirred tank reactor (CSTR). In the absence of deterministic oscillations and any external periodic forcing, oscillations appear when the system is perturbed by stochastic fluctuations in light irradiation with sufficiently high amplitude in the vicinity of the bifurcation point. The frequency distribution of the noise-induced oscillations is strongly affected by noise correlation. There is a shift of the noise-induced oscillation frequency toward higher frequencies for an intermediate range of the noise correlation exponent, indicating the occurrence of coherence resonance. Our findings indicate that, in principle, noise correlation can be used to direct chemical reactions toward certain behavior.

  5. 基于MLD模型的CSTR建模和控制%Modeling and Control of a Continuous Stirred Tank Reactor Based on a Mixed Logical Dynamical Model

    Institute of Scientific and Technical Information of China (English)

    杜静静; 宋春跃; 李平

    2007-01-01

    A novel control strategy for a continuous stirred tank reactor (CSTR) system, which has the typical characteristic of strongly pronounced nonlinearity, multiple operating points, and a wide operating range, is initiated from the point of hybrid systems. The proposed scheme makes full use of the modeling power of mixed logical dynamical (MLD) systems to describe the highly nonlinear dynamics and multiple operating points in a unified framework as a hybrid system, and takes advantage of the good control quality of model predictive control (MPC)to design a controller. Thus, this approach avoids oscillation during switching between sub-systems, helps to relieve shaking in transition, and augments the stability robustness of the whole system, and finally achieves optimal (i.e.fast and smooth) transition between operating points. The simulation results demonstrate that the presented approach has a satisfactory performance.

  6. Flow Field Around Rushton Turbine in Stirred Tank by Particle Image Velocimetry Measurement%搅拌槽内的Rushton桨叶周围流场的PIV测量

    Institute of Scientific and Technical Information of China (English)

    GAO Dianrong(高殿荣); ACHARYA Sumanta; WANG Yiqun(王益群); UHM Jongho

    2004-01-01

    In this paper, particle image velocimetry (PIV) was used to measure the mean and root meansquare(RMS) velocity in the stirred tank with six-flat blade Rushton turbine and with no baffles. Two typesof motion patterns were studied. One was that the impeller runs at constant speed, the other was that the impellerruns at time-dependent speed and in a periodic way. The emphasis of the paper was on the comparison of meanand RMS velocity vector maps and profiles between these two types of motion patterns, and especial attention waspaid to the comparison of the mean velocity, time-averaged RMS velocity, phase averaged RMS velocity betweenthe constant 3 RPS (revolution per second) and time-dependent operation. The Reynolds number was between 763and 1527. The study explained the mechanism that time-dependent RPS is more efficient for mixing than that ofconstant RPS.

  7. Study on the efficiency of the two phase partitioning stirred tank bioreactor on the toluene filtration from the airstream by Pseudomonas putida via

    Directory of Open Access Journals (Sweden)

    2013-02-01

    Full Text Available Introduction: There are different methods for controlling gaseous pollutants formed from air pollution sources that one of the most economical and efficient of them, is bio-filtration. The purpose of this study is Toluene removal from airstream by using the pure Pseudomonas putida bacteria as a fluidized bed in a two phase partitioning stirred tank bioreactor.Toluene ( Metyle benzene is one of the aromatic compounds which uses as a chemical solvent.low to moderate concentration of Toluene causes fatigue, dizziness, weakness,unbalance behaviour, memory loss, insomnia, loss of appetite, loss of vision and hearing. .Material and Method: In this experimental study at first, pure Pseudomonas putida in an aqueous phase containing nutrients and trace elements solution was duplicated and accustomed with Toluene. then solution contained microorganisms with 10% silicon oil was entered to bioreactor. The amount of CO2 and pollutant concentrations in the entrance and exhaust of bioreactor containing Pseudomonas putida was studied during 17 days for each variable. .Result: Experimental findings showed that in the 0.06 m3/h and 0.12 m3/h flow rate, the efficiency of bioreactor containing Pseudomonas putida in the concentration ranges of 283 Mg/m3 to 4710 Mg/m3 was at least 97% and 25% respectively. Statistical analysis (ANOVA showed that in two flow rates of 0.06 m3/h and 0.12 m3/h removal efficiency and mineralization percentage had significant differences .(Pvalue =0.01. .Conclusion: Achieving high efficiencies in pollutants removal was because of the prepared optimum conditions for Pseudomonas putida in the two phase partitioning stirred tank bioreactor with 10% organic phase.

  8. Use of stirred tanks for studying matrix effects caused by inorganic acids, easily ionized elements and organic solvents in inductively coupled plasma atomic emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Paredes, Eduardo [Departamento de Quimica Analitica, Nutricion y Bromatologia, University of Alicante, 03080 Alicante (Spain); Maestre, Salvador E. [Departamento de Quimica Analitica, Nutricion y Bromatologia, University of Alicante, 03080 Alicante (Spain); Todoli, Jose L. [Departamento de Quimica Analitica, Nutricion y Bromatologia, University of Alicante, 03080 Alicante (Spain)]. E-mail: jose.todoli@ua.es

    2006-03-15

    A stirred tank was used for the first time to elucidate the mechanism responsible for inductively coupled plasma atomic emission spectroscopy (ICP-AES) matrix effects caused by inorganic, acids and easily ionized elements (EIEs), as well as organic, ethanol and acetic acid, compounds. In order to gradually increase the matrix concentration, a matrix solution was introduced inside a stirred container (tank) initially filled with an aqueous multielement standard. PolyTetraFluoroEthylene (PTFE) tubing was used to deliver the resulting solution to the liquid sample introduction system. Matrix concentration ranged from 0 to 2 mol l{sup -1} in the case of inorganic acids (i.e., nitric, sulfuric, hydrochloric and a mixture of them), from 0 to about 2500 mg l{sup -1} for EIEs (i.e., sodium, calcium and mixtures of both) and from 0% to 15%, w/w for organic compounds. Up to 40-50 different solutions were prepared and measured in a period of time shorter than 6-7 min. This investigation was carried out in terms of emission intensity and tertiary aerosols characteristics. The experimental setup used in the present work allowed to thoroughly study the effect of matrix concentration on analytical signal. Generally speaking, the experiments concerning tertiary aerosol characterization revealed that, in the case of inorganic acids and EIEs, the mechanism responsible for changes in aerosol characteristics was the droplet fission. In contrast, for organic matrices it was found that the interference was caused by a change in both aerosol transport and plasma thermal characteristics. The extent of the interferences caused by organic as well as inorganic compounds was compared for a set of 14 emission lines through a wide range of matrix concentrations. With a stirred tank, it is possible to choose an efficient internal standard for any given matrix composition. The time required to complete this procedure was shorter than 7 min.

  9. 搅拌槽中固体颗粒离底悬浮机理的研究%Mechanism of Off-Bottom Suspension of Solid Particles in a Mechanical Stirred Tank

    Institute of Scientific and Technical Information of China (English)

    包雨云; 黄雄斌; 施力田; 王英琛

    2002-01-01

    The minimum fluid velocity to maintain particles just suspended was deduced, and the theoretical analysis shows that the minimum velocity is influenced by the properties of the solid and liquid, not by the operational conditions. For justification, the local minimum velocity at the bottom of the tank was measured by a bi- electrode conductivity probe, in a square-sectioned stirred tank (0.75m×0.75m×1.0m) with the glass beads-water system.The experiments showed that the fluid velocities for the same suspension state were identical despite that the power dissipated per unit mass was not the same under different configuration and operation. Both theoretical analysis and experimental results indicate that the off-bottom suspension is controlled by the local fluid flow over the bottom of the stirred tank.

  10. Hydrodynamic Study Of Column Bioleaching Processes

    Directory of Open Access Journals (Sweden)

    Sadowski Zygmunt

    2015-06-01

    Full Text Available The modelling of flow leaching solution through the porous media has been considered. The heap bioleaching process can be tested using the column experimental equipment. This equipment was employed to the hydrodynamic studies of copper ore bioleaching. The copper ore (black shale ore with the support, inertial materials (glass small balls and polyethylene beads was used to the bioleaching tests. The packed beds were various composition, the ore/support ratio was changed. The correlation between the bed porosity and bioleaching kinetics, and copper recovery was investigated.

  11. 搅拌釜内流场三维数值模拟及功率预测%3-D Numerical Simulation and Power Prediction of Flow Field in Stirred Tank

    Institute of Scientific and Technical Information of China (English)

    丁健华; 马腾; 陈涛; 杨象岳; 刘延雷

    2015-01-01

    大型搅拌釜,尤其是涉及传热或两相介质搅拌的容器,其搅拌效果和功率往往难以预测。针对大型搅拌釜的搅拌器设计、流场结构模拟和功率预测等问题,采用CFD数值模拟技术,对搅拌釜内部的三维流场进行了数值计算。分析了搅拌釜内的流动结构,计算了不同曝气量时的搅拌功率,获得了详细的流场信息和各项特性参数。%The stirring effects and powers of large stirred tanks, especially that involving heat transfer or stirring of two-phase medium, are difficult to predict. Employs CFD numerical simulation method to perform the numerical calculation of 3-D flow field in a stirred tank, referring to the design of stirrer, structure simulation of flow field and power prediction of the large stirred tank. Analyzes the flow structure in the tank, calculates the stirring power at different aeration intensities and obtains detailed information about flow field and various characteristic parameters. The analysis method mentioned in the paper can provide a reference for the design of stirrers.

  12. Bistability in isothermal photochemical systems: The A ⇆ h nu B --> h nu C reaction in a continuous flow stirred tank reactor

    Science.gov (United States)

    Laplante, J. P.; Lavabre, D.; Micheau, J. C.

    1988-08-01

    In this paper we present a kinetic analysis of the consecutive photoreaction scheme A⇄hνB→hνC assuming the reaction is carried out in a continuous flow stirred tank reactor (CSTR). The reactor is kept at constant temperature and fed with reactant A at a constant flow rate. A numerical analysis of the model's stationary states reveals a range of constraints for which the system possesses multiple steady states. The observed bistability depends strongly on the rate constant of the B→A reaction k2 . It is typically observed when k2 is much larger than the other rate constants. Our numerical calculations also reveal a marked dependency on parameters such as the molar absorptivities and the irradiation intensity I0 . Interestingly, multiple steady states are only observed for intermediate values of I0 . Analytical approximations are obtained for the stationary states in the limit where the end-product C does not absorb light. These approximations are used to clarify the mechanism responsible for the light-induced instability.

  13. Determination of Noncovalent Binding Using a Continuous Stirred Tank Reactor as a Flow Injection Device Coupled to Electrospray Ionization Mass Spectrometry

    Science.gov (United States)

    Santos, Inês C.; Waybright, Veronica B.; Fan, Hui; Ramirez, Sabra; Mesquita, Raquel B. R.; Rangel, António O. S. S.; Fryčák, Petr; Schug, Kevin A.

    2015-07-01

    Described is a new method based on the concept of controlled band dispersion, achieved by hyphenating flow injection analysis with ESI-MS for noncovalent binding determinations. A continuous stirred tank reactor (CSTR) was used as a FIA device for exponential dilution of an equimolar host-guest solution over time. The data obtained was treated for the noncovalent binding determination using an equimolar binding model. Dissociation constants between vancomycin and Ac-Lys(Ac)-Ala-Ala-OH peptide stereoisomers were determined using both the positive and negative ionization modes. The results obtained for Ac- L-Lys(Ac)- D-Ala- D-Ala (a model for a Gram-positive bacterial cell wall) binding were in reasonable agreement with literature values made by other mass spectrometry binding determination techniques. Also, the developed method allowed the determination of dissociation constants for vancomycin with Ac- L-Lys(Ac)- D-Ala- L-Ala, Ac- L-Lys(Ac)- L-Ala- D-Ala, and Ac- L-Lys(Ac)- L-Ala- L-Ala. Although some differences in measured binding affinities were noted using different ionization modes, the results of each determination were generally consistent. Differences are likely attributable to the influence of a pseudo-physiological ammonium acetate buffer solution on the formation of positively- and negatively-charged ionic complexes.

  14. Coproduction of hydrogen and methane via anaerobic fermentation of cornstalk waste in continuous stirred tank reactor integrated with up-flow anaerobic sludge bed.

    Science.gov (United States)

    Cheng, Xi-Yu; Li, Qian; Liu, Chun-Zhao

    2012-06-01

    A 10 L continuous stirred tank reactor (CSTR) system was developed for a two-stage hydrogen fermentation process with an integrated alkaline treatment. The maximum hydrogen production rate reached 218.5 mL/L h at a cornstalk concentration of 30 g/L, and the total hydrogen yield and volumetric hydrogen production rate reached 58.0 mL/g-cornstalk and 0.55-0.57 L/L d, respectively. A 10 L up-flow anaerobic sludge bed (UASB) was used for continuous methane fermentation of the effluents obtained from the two-stage hydrogen fermentation. At the optimal organic loading rate of 15.0 g-COD/Ld, the COD removal efficiency and volumetric biogas production rate reached 83.3% and 4.6L/Ld, respectively. Total methane yield reached 200.9 mL/g-cornstalk in anaerobic fermentation with the effluents and alkaline hydrolysate. As a result, the total energy recovery by coproduction of hydrogen and methane with anaerobic fermentation of cornstalk reached 67.1%.

  15. Effects of organic loading rate on hydrogen and volatile fatty acid production and microbial community during acidogenic hydrogenesis in a continuous stirred tank reactor using molasses wastewater.

    Science.gov (United States)

    Yun, J; Cho, K-S

    2016-12-01

    Microbial community associated with hydrogen production and volatile fatty acids (VFAs) accumulation was characterized in acidogenic hydrogenesis using molasses wastewater as a feedstock. Hydrogen and VFAs production were measured under an organic loading rate (OLR) from 19 to 35 g-COD l(-1)  day(-1) . The active microbial community was analysed using RNA-based massively parallel sequencing technique, and their correlation patterns were analysed using networking analysis. The continuous stirred tank reactor achieved stable hydrogen production at different OLR conditions, and the maximum hydrogen production rate (HPR) was 1·02 L-H2  l(-1)  day(-1) at 31·0 g-COD l(-1)  day(-1) . Butyrate (50%) and acetate (38%) positively increased with increase in OLR. Total VFA production stayed around 7135 mg l(-1) during the operation period. Although Clostridiales and Lactobacillales were relatively abundant, the HPR was positively associated with Pseudomonadaceae and Micrococcineae. Total VFA and acetate, butyrate and propionate concentrations were positively correlated with lactic acid bacteria (LAB) such as Bacillales, Sporolactobacillus and Lactobacillus. The close relationship between Pseudomonadaceae and Micrococcineae, and LAB play important roles for stable hydrogen and VFA production from molasses wastewater. Microbial information on hydrogen and VFA production can be useful to design and operate for acidogenic hydrogenesis using high strength molasses wastewater. © 2016 The Society for Applied Microbiology.

  16. Hydrolysis-acidogenesis of food waste in solid-liquid-separating continuous stirred tank reactor (SLS-CSTR) for volatile organic acid production.

    Science.gov (United States)

    Karthikeyan, Obulisamy Parthiba; Selvam, Ammaiyappan; Wong, Jonathan W C

    2016-01-01

    The use of conventional continuous stirred tank reactor (CSTR) can affect the methane (CH4) recovery in a two-stage anaerobic digestion of food waste (FW) due to carbon short circuiting in the hydrolysis-acidogenesis (Hy-Aci) stage. In this research, we have designed and tested a solid-liquid-separating CSTR (SLS-CSTR) for effective Hy-Aci of FW. The working conditions were pH 6 and 9 (SLS-CSTR-1 and -2, respectively); temperature-37°C; agitation-300rpm; and organic loading rate (OLR)-2gVSL(-1)day(-1). The volatile fatty acids (VFA), enzyme activities and bacterial population (by qPCR) were determined as test parameters. Results showed that the Hy-Aci of FW at pH 9 produced ∼35% excess VFA as compared to that at pH 6, with acetic and butyric acids as major precursors, which correlated with the high enzyme activities and low lactic acid bacteria. The design provided efficient solid-liquid separation there by improved the organic acid yields from FW.

  17. Remediation of a mixture of analgesics in a stirred-tank photobioreactor using microalgal-bacterial consortium coupled with attempt to valorise the harvested biomass.

    Science.gov (United States)

    Ismail, Maha M; Essam, Tamer M; Ragab, Yasser M; El-Sayed, Abo El-Khair B; Mourad, Fathia E

    2017-02-20

    An artificial microalgal-bacterial consortium was used to remediate a mixture of analgesics (ketoprofen, paracetamol and aspirin) in a stirred-tank photobioreactor. A hydraulic retention time (HRT) of 3days supported poor treatment because of the formation of p-aminophenol (paracetamol toxic metabolite). Increasing the HRT to 4days enhanced the bioremediation efficiency. After applying an acclimatization regime, 95% removal of the analgesics mixture, p-aminophenol and COD reduction were achieved. However, shortening the HRT again to 3days neither improved the COD reduction nor ketoprofen removal. Applying continuous illumination achieved the best analgesics removal results. The harvested biomass contained 50% protein, which included almost all essential amino acids. The detected fatty acid profile suggested the harvested biomass to be a good biodiesel-producing candidate. The water-extractable fraction possessed the highest phenolic content and antioxidant capacity. These findings suggest the whole process to be an integrated eco-friendly and cost-efficient strategy for remediating pharmaceutical wastewater.

  18. Defluoridation of drinking water by electrocoagulation/electroflotation in a stirred tank reactor with a comparative performance to an external-loop airlift reactor

    Energy Technology Data Exchange (ETDEWEB)

    Essadki, A.H., E-mail: essadki@hotmail.com [Ecole Superieure de Technologie de Casablanca, BP 8012, Oasis, Casablanca (Morocco); Gourich, B. [Ecole Superieure de Technologie de Casablanca, BP 8012, Oasis, Casablanca (Morocco); Vial, Ch. [Laboratoire de Genie Chimique et Biochimique, LGCB-UBP/ENSCCF, 24 avenue des Landais, BP 206, 63174 Aubiere Cedex (France); Delmas, H. [Laboratoire de Genie Chimique, ENSIACET-INPT, 5 rue Paulin Talabot, 31106 Toulouse (France); Bennajah, M. [Ecole Superieure de Technologie de Casablanca, BP 8012, Oasis, Casablanca (Morocco); Laboratoire de Genie Chimique, ENSIACET-INPT, 5 rue Paulin Talabot, 31106 Toulouse (France)

    2009-09-15

    Defluoridation using batch electrocoagulation/electroflotation (EC/EF) was carried out in two reactors for comparison purpose: a stirred tank reactor (STR) close to a conventional EC cell and an external-loop airlift reactor (ELAR) that was recently described as an innovative reactor for EC. The respective influences of current density, initial concentration and initial pH on the efficiency of defluoridation were investigated. The same trends were observed in both reactors, but the efficiency was higher in the STR at the beginning of the electrolysis, whereas similar values were usually achieved after 15 min operation. The influence of the initial pH was explained using the analyses of sludge composition and residual soluble aluminum species in the effluents, and it was related to the prevailing mechanisms of defluoridation. Fluoride removal and sludge reduction were both favored by an initial pH around 4, but this value required an additional pre-treatment for pH adjustment. Finally, electric energy consumption was similar in both reactors when current density was lower than 12 mA/cm{sup 2}, but mixing and complete flotation of the pollutants were achieved without additional mechanical power in the ELAR, using only the overall liquid recirculation induced by H{sub 2} microbubbles generated by water electrolysis, which makes subsequent treatments easier to carry out.

  19. Submerged fermentation of the edible mushroom Pleurotus ostreatus in a batch stirred tank bioreactor as a promising alternative for the effective production of bioactive metabolites.

    Science.gov (United States)

    Papaspyridi, Lefki-Maria; Aligiannis, Nektarios; Topakas, Evangelos; Christakopoulos, Paul; Skaltsounis, Alexandros-Leandros; Fokialakis, Nikolas

    2012-03-06

    The aim of this study was to investigate the potential of the submerged fermentation procedure in the production of bioactive metabolites of the common edible mushroom Pleurotus ostreatus. The biomass of the mushroom strain was produced by submerged fermentation in a batch stirred tank bioreactor and extracted by solvents of increasing polarity. The dichloromethane and methanol extract were fractioned by different techniques including Adsorption Chromatography and Fast Centrifugal Partition Chromatography (FCPC). The structures of pure compounds were elucidated with 1D/2D NMR-spectroscopic analyses, and chemical correlations combined with GC/MS and LC/MS experiments. Nineteen metabolites (e.g., fatty acids, phenolic metabolites, nucleotides and alkaloids) were isolated. Beyond the production of known metabolites, we report herein the production also of trans-3,4-dihydro-3,4,8-trihydroxynapthalen-1(2H)-one, indolo-3-carboxylic acid, 3-formylpyrrole and 4-hydroxybenzoic acid, that have pharmaceutical interest and are isolated for the first time from Pleurotus strains. This work indicates the great potential of the established bioprocess for the production of P. ostreatus mycelia with enhanced metabolic profile.

  20. On the effect of added impurity on crystal purity of urea in an oscillatory baffled crystallizer and a stirred tank crystallizer

    Science.gov (United States)

    McLachlan, Hannah; Ni, Xiong-Wei

    2016-05-01

    Previous work has indicated that crystals produced in oscillatory baffled crystallisers (OBC) from a relatively 'pure' starting environment gave statistically higher purities than that in stirred tank crystallisers (STC) under comparable conditions. In this work, a known amount of biuret (the impurity) was added to the 'pure' urea system and the results show that the OBC still produced higher purity crystals than the STC, although these purity values were statistically lower than from the 'pure' environment in both vessels. By evaluating crystallisation rates of both urea and biuret, we noticed that these rates are higher in the STC than in the OBC, which would have led to small crystals in the former vessel. The CSD data however gave the opposite result where the CSD is wider with more, large crystals in the STC than in the OBC, in particular in the presence of added impurity. These larger crystals are likely formed due to agglomeration coupled with incorporation of impurity, which leads to a lower purity.

  1. Performance comparison of a continuous-flow stirred-tank reactor and an anaerobic sequencing batch reactor for fermentative hydrogen production depending on substrate concentration.

    Science.gov (United States)

    Kim, S-H; Han, S-K; Shin, H-S

    2005-01-01

    This study was conducted to compare the performance of a continuous-flow stirred-tank reactor (CSTR) and an anaerobic sequencing batch reactor (ASBR) for fermentative hydrogen production at various substrate concentrations. Heat-treated anaerobic sludge was utilized as an inoculum, and hydraulic retention time (HRT) for each reactor was maintained at 12 h. At the influent sucrose concentration of 5 g COD/L, start-up was not successful in both reactors. The CSTR, which was started-up at 10 g COD/L, showed stable hydrogen production at the influent sucrose concentrations of 10-60 g COD/L during 203 days. Hydrogen production was dependent on substrate concentration, resulting in the highest performance at 30 g COD/L. At the lower substrate concentration, the hydrogen yield (based on hexose consumed) decreased with biomass reduction and changes in fermentation products. At the higher substrate concentration, substrate inhibition on biomass growth caused the decrease of carbohydrate degradation and hydrogen yield (based on hexose added). The ASBR showed higher biomass concentration and carbohydrate degradation efficiency than the CSTR, but hydrogen production in the ASBR was less effective than that in the CSTR at all the substrate concentrations.

  2. IMPROVED CELLULASE PRODUCTION BY Aspergillus terreus USING OIL PALM EMPTY FRUIT BUNCH FIBRE AS SUBSTRATE IN A STIRRED TANK BIOREACTOR THROUGH OPTIMIZATION OF THE FERMENTATION CONDITIONS

    Directory of Open Access Journals (Sweden)

    Mahdi Shahriarinour

    2011-05-01

    Full Text Available Response surface methodology (RSM was performed to evaluate the effects of dissolved oxygen tension (DOT and initial pH on the production of carboxymethyl cellulase (CMCase, filter-paper hydrolase (FPase, and β-glucosidase by Aspergillus terreus in a 2 L stirred tank bioreactor. Delignified oil palm empty fruit bunch (OPEFB fibre was used as the main substrate under submerged fermentation. Growth of A. terreus and the production of three main components of cellulase were optimized by central composite design (CCD design. Statistical analysis of results showed that the individual terms of these two variables (DOT and pH had significant effects on growth and the production of all components of cellulase. Maximum growth (13.07 g/L and cellulase activity (CMCase = 50.33 U/mL, FPase = 2.29 U/mL and β-glucosidase = 15.98 U/ml were obtained when the DOT and initial culture pH were set at 55% and 5.5, respectively. A high proportion of β-glucosidase to FPase (8:1 in cellulase of A. terreus could be beneficial for efficient hydrolysis of cellulosic materials. The use of OPEFB as a main substrate would reduce the cost of fermentation for the production of cellulase.

  3. Growth and biomass production with enhanced {beta}-glucan and dietary fibre contents of Ganoderma australe ATHUM 4345 in a batch-stirred tank bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Papaspyridi, Lefki-Maria; Christakopoulos, Paul [BIOtechMASS Unit, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens (Greece); Katapodis, Petros [BIOtechMASS Unit, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens (Greece); Biotechnology Laboratory, Department of Biological Applications and Technologies, University of Ioannina, Ioannina (Greece); Gonou-Zagou, Zacharoula; Kapsanaki-Gotsi, Evangelia [Department of Ecology and Systematics, Faculty of Biology, National and Kapodistrian University of Athens, Athens (Greece)

    2011-02-15

    In this study we maximized biomass production by the basidiomycete Ganoderma australe ATHUM 4345, a species of pharmaceutical interest as it is a valuable source of nutraceuticals, including dietary fibers and glucans. We used the Biolog FF MicroPlate to screen 95 different carbon sources for growth monitoring. The pattern of substrate catabolism forms a substrate assimilation fingerprint, which is useful in selecting components for media optimization of maximum biomass production. Response surface methodology, based on the central composite design was applied to explore the optimum concentrations of carbon and nitrogen sources of culture medium in shake flask cultures. When the improved culture medium was tested in a 20-L stirred tank bioreactor, using 13.7 g/L glucose and 30.0 g/L yeast extract, high biomass yields (10.1{+-}0.4 g/L) and productivity of 0.09 g L{sup -1} h{sup -1} were obtained. The yield coefficients for total glucan and dietary fibers on biomass formed were 94.82{+-}6 and 341.15{+-}12.3 mg/g mycelium dry weight, respectively. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Removal of oxytetracycline (OTC) in a synthetic pharmaceutical wastewater by a sequential anaerobic multichamber bed reactor (AMCBR)/completely stirred tank reactor (CSTR) system: biodegradation and inhibition kinetics.

    Science.gov (United States)

    Sponza, Delia Teresa; Çelebi, Hakan

    2012-01-01

    An anaerobic multichamber bed reactor (AMCBR) was effective in removing both molasses-chemical oxygen demand (COD), and the antibiotic oxytetracycline (OTC). The maximum COD and OTC removals were 99% in sequential AMCBR/completely stirred tank reactor (CSTR) at an OTC concentration of 300 mg L(-1). 51%, 29% and 9% of the total volatile fatty acid (TVFA) was composed of acetic, propionic acid and butyric acids, respectively. The OTC loading rates at between 22.22 and 133.33 g OTC m(-3) d(-1) improved the hydrolysis of molasses-COD (k), the maximum specific utilization of molasses-COD (k(mh)) and the maximum specific utilization rate of TVFA (k(TVFA)). The direct effect of high OTC loadings (155.56 and -177.78 g OTC m(-3) d(-1)) on acidogens and methanogens were evaluated with Haldane inhibition kinetic. A significant decrease of the Haldane inhibition constant was indicative of increases in toxicity at increasing loading rates.

  5. Effect of organic loading rate on dark fermentative hydrogen production in the continuous stirred tank reactor and continuous mixed immobilized sludge reactor from waste pastry hydrolysate.

    Science.gov (United States)

    Han, Wei; Hu, Yunyi; Li, Shiyi; Nie, Qiulin; Zhao, Hongting; Tang, Junhong

    2016-12-01

    Waste pastry (6%, w/v) was hydrolyzed by the produced glucoamylase and protease to obtain the glucose (19.8g/L) and free amino nitrogen (179mg/L) solution. Then, the effect of organic loading rate (OLR) (8-40kgCOD/(m(3)d)) on dark fermentative hydrogen production in the continuous stirred tank reactor (CSTR) and continuous mixed immobilized sludge reactor (CMISR) from waste pastry hydrolysate was investigated and compared. The maximum hydrogen production rate of CSTR (277.76mL/(hL)) and CMISR (320.2mL/(hL)) were achieved at OLR of 24kgCOD/(m(3)d) and 32kgCOD/(m(3)d), respectively. Carbon recovery ranged from 75.2-84.1% in the CSTR and CMISR with the balance assumed to be converted to biomass. One gram waste pastry could produce 0.33g (1.83mmol) glucose which could be further converted to 79.24mL (3.54mmol) hydrogen in the CMISR or 91.66mL (4.09mmol) hydrogen in the CSTR. This is the first study which reports dark fermentative hydrogen production from waste pastry.

  6. Anaerobic treatment of cassava stillage for hydrogen and methane production in continuously stirred tank reactor (CSTR) under high organic loading rate (OLR)

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Gang; Xie, Li; Zou, Zhonghai; Wang, Wen; Zhou, Qi [Key Laboratory of Yangtze River Water Environment, Ministry of Education (Tongji University), UNEP-Tongji, Tongji University, Siping Road No. 1239, Shanghai 200092 (China); Shim, Hojae [Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau SAR 999078 (China)

    2010-11-15

    Anaerobic hydrogen and methane production from cassava stillage in continuously stirred tank reactor (CSTR) were investigated in this study. Results showed that the heat-pretreatment of inoculum did not enhance hydrogen yield compared to raw inoculum under mesophilic condition after continuous operation. However, the hydrogen yield increased from about 14 ml H{sub 2}/gVS under mesophilic condition to 69.6 ml H{sub 2}/gVS under thermophilic condition due to the decrease of propionate concentration and inhibition of homoacetogens. Therefore, temperature was demonstrated to be more important than pretreatment of inoculum to enhance the hydrogen production. Under high organic loading rate (OLR) (>10 gVS/(L.d)), the two-phase thermophilic CSTR for hydrogen and methane production was stable with hydrogen and methane yields of 56.6 mlH{sub 2}/gVS and 249 mlCH{sub 4}/gVS. The one-phase thermophilic CSTR for methane production failed due to the accumulation of both acetate and propionate, leading to the pH lower than 6. Instead of propionate alone, the accumulations of both acetate and propionate were found to be related to the breakdown of methane reactor. (author)

  7. Defluoridation of drinking water by electrocoagulation/electroflotation in a stirred tank reactor with a comparative performance to an external-loop airlift reactor.

    Science.gov (United States)

    Essadki, A H; Gourich, B; Vial, Ch; Delmas, H; Bennajah, M

    2009-09-15

    Defluoridation using batch electrocoagulation/electroflotation (EC/EF) was carried out in two reactors for comparison purpose: a stirred tank reactor (STR) close to a conventional EC cell and an external-loop airlift reactor (ELAR) that was recently described as an innovative reactor for EC. The respective influences of current density, initial concentration and initial pH on the efficiency of defluoridation were investigated. The same trends were observed in both reactors, but the efficiency was higher in the STR at the beginning of the electrolysis, whereas similar values were usually achieved after 15min operation. The influence of the initial pH was explained using the analyses of sludge composition and residual soluble aluminum species in the effluents, and it was related to the prevailing mechanisms of defluoridation. Fluoride removal and sludge reduction were both favored by an initial pH around 4, but this value required an additional pre-treatment for pH adjustment. Finally, electric energy consumption was similar in both reactors when current density was lower than 12mA/cm(2), but mixing and complete flotation of the pollutants were achieved without additional mechanical power in the ELAR, using only the overall liquid recirculation induced by H(2) microbubbles generated by water electrolysis, which makes subsequent treatments easier to carry out.

  8. Spatially-resolved current and impedance analysis of a stirred tank reactor and serpentine fuel cell flow-field at low relative humidity

    Science.gov (United States)

    Hogarth, Warren H. J.; Steiner, Johannes; Benziger, Jay B.; Hakenjos, Alex

    A 20 cm 2 segmented anode fuel cell is used to investigate the performance of a hydrogen-air fuel cell at 1 atm. with two different flow-fields using spatially-resolved current and impedance measurements. A self-draining stirred tank reactor (STR) fuel cell and a single-channel serpentine fuel cell are compared with humidified and dry feed conditions. The current density distribution, impedance distribution, heat distribution and water evolution are compared for the two different flow-fields. With inlet feed dew points of 30 °C, the STR fuel cell and serpentine system performed comparably with moderate current gradients. With drier feeds, however, the STR fuel cell exhibited superior overall performance in terms of a higher total current and lower current, impedance and temperature distribution gradients. The STR fuel cell design is superior to a single-channel serpentine design under dry conditions because its open channel design allows the feed gases to mix with the product water and auto-humidify the cell.

  9. Influence of Light Intensity and Temperature on Cultivation of Microalgae Desmodesmus Communis in Flasks and Laboratory-Scale Stirred Tank Photobioreactor

    Science.gov (United States)

    Vanags, J.; Kunga, L.; Dubencovs, K.; Galvanauskas, V.; Grīgs, O.

    2015-04-01

    Optimization of the microalgae cultivation process and of the bioprocess in general traditionally starts with cultivation experiments in flasks. Then the scale-up follows, when the process from flasks is transferred into a laboratory-scale bioreactor, in which further experiments are performed before developing the process in a pilot-scale reactor. This research was done in order to scale-up the process from a 0.4 1 shake flask to a 4.0 1 laboratory-scale stirred-tank photobioreactor for the cultivation of Desmodesmus (D.) communis microalgae. First, the effect of variation in temperature (21-29 ºC) and in light intensity (200-600 μmol m-2s-1) was studied in the shake-flask experiments. It was shown that the best results (the maximum biomass concentration of 2.72 g 1-1 with a specific growth rate of 0.65 g g-1d-1) can be achieved at the cultivation temperature and light intensity being 25 °C and 300 μmol m2s-1, respectively. At the same time, D. communis cultivation under the same conditions in stirred-tank photobioreactor resulted in average volumetric productivities of biomass due to the light limitation even when the light intensity was increased during the experiment (the maximum biomass productivity 0.25 g 1-1d-1; the maximum biomass concentration 1.78 g 1-1). Mikroaļģu kultivēšanas procesa optimizēšana parasti sākas ar kultivēšanas eksperimentiem kolbās. Tālāk seko procesa pārnese uz laboratorijas mēroga fotobioreaktoru, kurā tiek veikti tālāki eksperimenti, pirms tiek izveidots pilota mēroga reaktors. Šis pētījums tika veikts ar mērķi, pārnest Desmodesmus communis kultivēšanas procesu no 0.4 1 kolbas uz 4.0 1 laboratorijas fotobioreaktoru. Vispirms tika pētīta dažādu temperatūru (21-29 ºC) un gaismas intensitātes (200-600 μmol m-2s-1) ietekme uz aļģu biomasu veicot eksperimentus kolbās. Labākie rezultāti (maksimālā biomasas koncentrācija 2.72 g 1-1; īpatnējais augšanas ātrums 0.65 g g-1d-1) sasniegti, kad

  10. Stirred tank bioreactor culture combined with serum-/xenogeneic-free culture medium enables an efficient expansion of umbilical cord-derived mesenchymal stem/stromal cells.

    Science.gov (United States)

    Mizukami, Amanda; Fernandes-Platzgummer, Ana; Carmelo, Joana G; Swiech, Kamilla; Covas, Dimas T; Cabral, Joaquim M S; da Silva, Cláudia L

    2016-08-01

    Mesenchymal stem/stromal cells (MSC) are being widely explored as promising candidates for cell-based therapies. Among the different human MSC origins exploited, umbilical cord represents an attractive and readily available source of MSC that involves a non-invasive collection procedure. In order to achieve relevant cell numbers of human MSC for clinical applications, it is crucial to develop scalable culture systems that allow bioprocess control and monitoring, combined with the use of serum/xenogeneic (xeno)-free culture media. In the present study, we firstly established a spinner flask culture system combining gelatin-based Cultispher(®) S microcarriers and xeno-free culture medium for the expansion of umbilical cord matrix (UCM)-derived MSC. This system enabled the production of 2.4 (±1.1) x10(5) cells/mL (n = 4) after 5 days of culture, corresponding to a 5.3 (±1.6)-fold increase in cell number. The established protocol was then implemented in a stirred-tank bioreactor (800 mL working volume) (n = 3) yielding 115 million cells after 4 days. Upon expansion under stirred conditions, cells retained their differentiation ability and immunomodulatory potential. The development of a scalable microcarrier-based stirred culture system, using xeno-free culture medium that suits the intrinsic features of UCM-derived MSC represents an important step towards a GMP compliant large-scale production platform for these promising cell therapy candidates. Copyright © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. PIV Application in Flow Measurement within Chemical Stirred Tank%PIV在化工搅拌釜内流动测量中的应用

    Institute of Scientific and Technical Information of China (English)

    杨斌; 高凯; 淡勇

    2013-01-01

    着重探讨了新一代全场光学测速技术——粒子图像速度场仪(PIV)在搅拌混合实验中的应用,指出PIV及其衍生的测速技术在搅拌混合实验研究中具有广泛应用前景.PIV流场测量结果兼具很高的空间分辨率和时间解析度,可以得到搅拌釜中混合流体的瞬时2D或3D速度场以及浓度场等信息,进行非定常湍流特性研究,有助于建立搅拌釜内多相流动模型,揭示搅拌混合作用机理,优化搅拌桨型设计,促进搅拌混合技术的进一步发展.%Particle image velocimetry (PIV) was introduced, which has great application in the experimental study on mixing flow in a stirred tank. PIV has higher space-resolution and time-resolution. Based on PIV, 2D or 3D instant velocity fields and the mixing flow' s density field can be obtained to benefit the research of unsteady turbulent characteristics, the building of multi-phase flow model, the revealing of stirred autoclave' s mixing mechanism and the optimization of mixing paddle design as well as the promotion of further development of the mixing technology.

  12. Interpreting hydrodynamic behaviour by the model of stirred tanks in series with exchanged zones: preliminary study in lab-scale trickling filters.

    Science.gov (United States)

    Zeng, Ming; Soric, Audrey; Ferrasse, Jean-Henry; Roche, Nicolas

    2013-01-01

    In trickling filters for wastewater treatment, hydrodynamic behaviour is affected by the growth of biofilm on the porous medium. Therefore, modelling hydrodynamic behaviour is necessary and efficient to predict the biodegradation of pollutants. In this study, laboratory-scale trickling filters were filled with two different porous media (glass beads and plastic rings) and were fed by a synthetic substrate in batch mode. Total organic carbon (TOC) of the effluent was measured and retention time distribution (RTD) was determined by injecting NaCl. Results showed that medium had no significant effect on TOC removal rate (around 80% and 60% respectively for batch time of seven and two days). However, regarding the hydrodynamic behaviour, the effective volume ratio and hydraulic efficiency in the glass beads bed increased remarkably from 28% and 18% to 80% and 70%, respectively, with the reduction of dispersion coefficient (from 4.55 to 1.53). Moreover, the short batch time accelerated this change. Conversely, no variation of hydrodynamic behaviour in plastic rings bed was evident. Along with the feeding of synthetic substrate, biofilm concentration ranged from 1.5 to 10.1 g/L in the glass beads reactor and it achieved around 2.8 g/L in the plastic rings reactor. Hydrodynamic modelling indicated that the model of stirred tanks in series with exchanged zones fitted the experimental results well. These gave values of mobile and immobile volumes of 51 mL and 17 mL, respectively, in the glass beads filter and 25 mL and 15 mL, respectively, in the plastic rings filter.

  13. Reactor models for a series of continuous stirred tank reactors with a gas-liquid-solid leaching system: Part I. Surface reaction control

    Science.gov (United States)

    Papangelakis, V. G.; Demopoulos, G. P.

    1992-12-01

    In this three-part series of articles, comprehensive three-phase steady-state hydrometallurgical reactor models of the continuous stirred tank reactor (CSTR) type are developed and applied to a commercial (pressure oxidation) process. The key features of the developed models are the coupling of both mass and heat balance equations, the description of the nonisothermal performance (autothermal) of a multistage continuous reactor, and the treatment of multimineral feed materials. The model considers only the oxidation reactions, because they mainly affect the thermal balance of the reactor. The stoichiometries and intrinsic kinetics of the heterogeneous leaching reactions, which are established via independent experiments, are the foundation of the developed model. A three-phase (g-l-s) reaction process might be controlled by either surface reaction control, i.e., the rate(s) of the heterogeneous leaching reaction(s), or by gas transfer control, i.e., the rate of transfer of the gaseous reactant into the liquid phase. In the present article (Part I), the case of surface reaction control is treated. The article addresses, in particular, the following topics: (1) it outlines the basic mass and heat balance equations which describe the performance of a multistage leaching reactor; (2) it presents a continuous function to describe the particle size distribution of the feed; and (3) it develops, on the basis of probability theory, number- and mass-particle size density functions which give the size distribution of particle populations reacting according to the surface reaction control-shrinking core model.

  14. Coupling of acrylic dyeing wastewater treatment by heterogeneous Fenton oxidation in a continuous stirred tank reactor with biological degradation in a sequential batch reactor.

    Science.gov (United States)

    Esteves, Bruno M; Rodrigues, Carmen S D; Boaventura, Rui A R; Maldonado-Hódar, F J; Madeira, Luís M

    2016-01-15

    This work deals with the treatment of a recalcitrant effluent, from the dyeing stage of acrylic fibres, by combination of the heterogeneous Fenton's process in a continuous stirred tank reactor (CSTR) with biological degradation in a sequential batch reactor (SBR). Three different catalysts (a commercial Fe/ZSM-5 zeolite and two distinct Fe-containing activated carbons - ACs - prepared by wet impregnation of iron acetate and iron nitrate) were employed on the Fenton's process, and afterwards a parametric study was carried out to determine the effect of the main operating conditions, namely the hydrogen peroxide feed concentration, temperature and contact time. Under the best operating conditions found, using the activated carbon impregnated with iron nitrate, 62.7% of discolouration and 39.9% of total organic carbon (TOC) reduction were achieved, at steady-state. Furthermore, a considerable increase in the effluent's biodegradability was attained (BOD5:COD ratio increased from <0.001 to 0.27 and SOUR - specific oxygen uptake rate - from <0.2 to 11.1 mg O2/(gVSS·h)), alongside a major decrease in its toxicity (from 92.1 to 94.0% of Vibrio fischeri inhibition down to 6.9-9.9%). This allowed the application of the subsequent biological degradation stage. The combination of the two processes provided a treated effluent that clearly complies with the legislated discharge limits. It was also found that the iron leaching from the three catalysts tested was very small in all runs, a crucial factor for the stability and long-term use of such materials.

  15. Performance and microbial communities of a continuous stirred tank anaerobic reactor treating two-phases olive mill solid wastes at low organic loading rates.

    Science.gov (United States)

    Rincón, B; Raposo, F; Borja, R; Gonzalez, J M; Portillo, M C; Saiz-Jimenez, C

    2006-02-24

    A study of the performance and microbial communities of a continuous stirred tank reactor (CSTR) treating two-phases olive mill solid wastes (OMSW) was carried out at laboratory-scale. The reactor operated at a mesophilic temperature (35 degrees C) and an influent substrate concentration of 162 g total chemical oxygen demand (COD)L(-1) and 126 g volatile solids (VS)L(-1). The data analyzed in this work corresponded to a range of organic loading rates (OLR) of between 0.75 and 3.00 g CODL(-1)d(-1), getting removal efficiencies in the range of 97.0-95.6%. Methane production rate increased from 0.164 to 0.659 L CH(4)L(reactor)(-1)d(-1) when the OLR increased within the tested range. Methane yield coefficients were 0.225 L CH(4)g(-1) COD removed and 0.290 L CH(4)g(-1) VS removed and were virtually independent of the OLR applied. A molecular characterization of the microbial communities involved in the process was also accomplished. Molecular identification of microbial species was performed by PCR amplification of 16S ribosomal RNA genes, denaturing gradient gel electrophoresis (DGGE), cloning and sequencing. Among the predominant microorganisms in the bioreactor, the Firmicutes (mainly represented by Clostridiales) were the most abundant group, followed by the Chloroflexi and the Gamma-Proteobacteria (Pseudomonas species as the major representative). Other bacterial groups detected in the bioreactor were the Actinobacteria, Bacteroidetes and Deferribacteres. Among the Archaea, the methanogen Methanosaeta concilii was the most representative species.

  16. Photocatalytic inactivation of Flavobacterium and E. coli in water by a continuous stirred tank reactor (CSTR) fed with suspended/immobilised TiO2 medium.

    Science.gov (United States)

    Cohen-Yaniv, Vered; Narkis, Nava; Armon, Robert

    2008-01-01

    A photocatalytic continuous stirred tank reactor (CSTR) was built at laboratory scale to inactivate two environmental bacteria strains (Flavobacterium and E. coli) in tap water. Several parameters were found to impact reactor efficiency. Bacterial initial concentration is an important factor in inactivation rate. After 30 minutes of irradiation at 10(8)-10(9) CFU mL(-1) starting concentration, a >5 log reduction was achieved while at 10(4)-10(6) CFU mL(-1) only a 2 log reduction was observed. Water hardness and pH have an important influence on the photocatalytic inactivation process. Soft water, with low Ca(+2) and Mg(+2) at low pH approximately 5.3 resulted in increased inactivation of Flavobacterium reaching >6 orders of magnitude reduction. E. coli and Flavobacterium at pH 5 were inactivated by 3 logs more as compared to pH 7 under similar conditions. pH below TiO2 isoelectric point (approximately 5.6) supports better contact between bacteria and anatase particles resulting in superior inactivation. TiO2 powder suspension was compared with immobilised powder in sol-gel coated glass beads in order to exclude the need for particles separation from the treated water. TiO2 suspension was more effective by 3 orders of magnitude when compared to coated glass beads. An interesting observation was found between the two bacterial strains based on their hydrophobicity/hydrophilicity balance. The more hydrophobic Flavobacterium compared to E. coli was inactivated photocatalytically by >3 logs more then E. coli in the first 30 minutes of irradiation interval. The results indicate the importance of the parameters involved in the contact between TiO2 particles and microorganisms that govern the successful inactivation rate in CSTR.

  17. Effects of nitrobenzene concentration and hydraulic retention time on the treatment of nitrobenzene in sequential anaerobic baffled reactor (ABR)/continuously stirred tank reactor (CSTR) system.

    Science.gov (United States)

    Kuscu, Ozlem Selcuk; Sponza, Delia Teresa

    2009-04-01

    The effects of increasing nitrobenzene (NB) concentrations and hydraulic retention times (HRT) on the treatment of NB were investigated in a sequential anaerobic baffled reactor (ABR)/aerobic completely stirred tank reactor (CSTR) system. In the first step of the study, the maximum COD removal efficiencies were found as 88% and 92% at NB concentrations varying between 30 mg L(-1) and 210 mg L(-1) in ABR. The minimum COD removal efficiency was 79% at a NB concentration of 700 mg L(-1). The removal efficiency of NB was nearly 100% for all NB concentrations in the ABR reactor. The methane gas production and the methane gas percentage remained stable (1500 mL day(-1) and 48-50%, respectively) as the NB concentration was increased from 30 to 210 mg L(-1). In the second step of the study it was found that as the HRT decreased from 10.38 days to 2.5 days the COD removal efficiencies decreased slightly from 94% to 92% in the ABR. For maximum COD and NB removal efficiencies the optimum HRT was found as 2.5 days in the ABR. The total COD removal efficiency was 95% in sequential anaerobic (ABR)/aerobic (CSTR) reactor system at a minimum HRT of 1 day. When the HRT was decreased from 10.38 days to 1 day, the methane percentage decreased from 42% to 29% in an ABR reactor treating 100 mg L(-1) NB. Nitrobenzene was reduced to aniline under anaerobic conditions while aniline was mineralized to catechol with meta cleavage under aerobic conditions.

  18. Effect of aeration and agitation regimes on lipase production by newly isolated Rhodotorula mucilaginosa-MTCC 8737 in stirred tank reactor using molasses as sole production medium.

    Science.gov (United States)

    Potumarthi, Ravichandra; Subhakar, Chennupati; Vanajakshi, J; Jetty, Annapurna

    2008-12-01

    The influence of media and process parameters (aeration and agitation) on fermentation broth rheology and biomass formation has been studied in 1.5-l stirred tank reactor for lipase production using Rhodotorula mucilaginosa MTCC 8737. Molasses, as sole production medium, is used for lipase production by varying aeration (1, 2, and 3 vvm) and agitation speeds (100, 200, and 300 rpm). Maximum lipase activity of 72 U/ml was obtained during 96 h of fermentation at 2 vvm, 200 rpm, pH 7, and 25 +/- 2 degrees C temperature. Lipase production kinetics with respect to dry cell weight of biomass showed Y (P/S) of 25.71 U/mg, specific product formation of 10.9 U/mg DC, and Y (X/S) 2.35 mg/mg. Maximum lipase activity (MC 2) of 56 U/ml was observed at 1% molasses, and a further increase in the molasses concentration of (%) 1.5 and 2 inhibited the product formation of lipase with 15 and 8.5 U/ml, respectively. The production kinetics of molasses media showed Y (P/X) was 14 U/mg DC, Y (P/S) 16 U/mg, and Y (X/S) 1.14 mg/mg during 96 h of bioreactor operation. The k(L)a values for all batches (MC 1-MC 4) at 96 h of fermentation were 32, 28, 21, and 19/h, and the |oxygen transfer rate were 54.4, 56, 35.7, and 17.29 mg/l h, respectively. Increase in molasses concentration resulted in decreased lipase activity by increase in viscosity of the fermentation broth.

  19. Bioleaching of heavy metals from sewage sludge by Acidithiobacillus thiooxidans. A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Ye-Ming; Wang, Qing-Ping; Chen, Zu-Liang [Fujian Normal Univ., Fuzhou (China). School of Environmental Science and Engineering; Tang, Caixian [La Trobe Univ., Melbourne, VIC (Australia). Dept. of Agricultural Sciences

    2012-06-15

    To understand the bioleaching of metals from sludge by Acidithiobacillus thiooxidans, the aims of this study were to evaluate the experimental conditions affecting the efficiency of removal of the metals, including solids concentration, initial pH, sulfur concentration and inoculum level were examined, and following the bioleaching mechanism was proposed. Materials and methods: A. thiooxidans were isolated from collected sludge samples containing bacteria from Fuzhou Jingshan sewage treatment plant, and identification of bacteria by sequencing the 16 s rDNA gene sequences. Conditions affecting the bioleaching and application were conducted by batch experiments. The analysis of Cr, Cu, Pb, and Zn was carried out using an atomic absorption spectrophotometer, and the pH and oxidation-reduction potential (ORP) were measured using a pH meter and an ORP meter. The results show that a high metal leaching efficiency was achieved at low solid concentrations due to decreases in buffering capacity. In addition, the best conditions of the bioleaching included 2 % (w/{nu}) solid concentration, 5.0 gL{sup -1} sulfur concentration, and 10 % ({nu}/{nu}) inoculum concentration, where the removal efficiencies of Cr, Cu, Pb, and Zn in sewage sludge was 43.6 %, 96.2 %, 41.6 %, and 96.5 %, respectively. We found that the bioleaching of Zn was governed by direct and indirect mechanisms, while the bioleaching of Cu, Pb, and Cr was mainly dominated by the bioleaching indirect mechanism. After processing with the proposed techniques, the heavy metals in the sewage sludge did meet the requirement of the national standards. (orig.)

  20. Maximization of organic acids production by Aspergillus niger in a bubble column bioreactor for V and Ni recovery enhancement from power plant residual ash in spent-medium bioleaching experiments.

    Science.gov (United States)

    Rasoulnia, P; Mousavi, S M

    2016-09-01

    Spent-medium bioleaching of V and Ni from a power plant residual ash (PPR ash) was conducted using organic acids produced by Aspergillus niger. The production of organic acids in a bubble column bioreactor was optimized through selecting three most influencing factors. Under optimum condition of aeration rate of 762.5(ml/min), sucrose concentration of 101.9(g/l) and inoculum size of 40(ml/l), respectively 17,185, 4539, 1042 and 502(ppm) of oxalic, gluconic, citric and malic acids were produced. Leaching experiments were carried out using biogenic produced organic acids under leaching environment temperature of 60°C and rotary shaking speed of 135rpm, with various pulp densities of 1, 2, 3, 5, 7 and 9(%w/v). The results showed that biogenic produced organic acids leached V much more efficiently than Ni so that even at high pulp density of 9(%w/v), 83% of V was recovered while Ni recovery yield was 30%.

  1. Mixing performance comparison between top entry impeller and side entry impeller in stirred tanks%顶入式与侧入式搅拌槽内混合特性的比较

    Institute of Scientific and Technical Information of China (English)

    方键; 凌祥; 桑芝富

    2012-01-01

    应用计算流体动力学方法(CFD)对顶入式与侧入式搅拌槽内的流型特征、混合过程进行了数值模拟.计算采用标准k-ε湍流模型、多重参考系法和滑移网格法研究了2种形式搅拌槽的混合效率,分析了不同槽高径比H/T及桨型对侧入式搅拌槽混合性能的影响,并使用文献数据与碘-硫代硫酸钠褪色法对模拟进行了验证.结果表明:四斜叶开启涡轮桨( PBTD45)运行下顶入式与侧入式搅拌槽内主体循环均是轴向循环流;在H/T=1的搅拌槽中相同功耗情况下,顶入式搅拌的混合效率比侧入式搅拌的高,混合时间减少了约28.2%;侧入式搅拌在较低H/T比的搅拌槽内的混合效率较高,当H/T=0.6左右时侧入式搅拌的混合效率与顶入式(H/T =1)接近.PBTD6030桨与FE-4桨较适合侧入式搅拌槽中的混合操作.%Computational fluid dynamics ( CFD) method was used to study the flow field and mixing process in stirred tanks equipped with top entry impeller and side entry impellers. The standard k-e turbulent model, multi-reference frame and sliding grid methods were used in the simulation. The mixing performances of top entry impeller and side entry impellers were analyzed. Simulation results were validated by the fade method for iodine-sodium thiosulfate and reference data. The effect of tank height-diameter ratio, H/T, and impeller type on mixing time in side entry stirred tank were investigated. It was found that the main circulation loops in both the top entry and side entry stirred tanks equipped with pitched blade agitators ( PBTD45 ) were axial loops. In the stirred tanks (H/T = 1) , the mixing performance of top entry mixer was better than that of the side entry on the same power consumption and the mixing time reduced about 28. 2%. For the side entry mixer, the mixing performance was better when H/T was lower. The mixing efficiency was the same as that of top entry mixer (H/T = 1) when H/T ratio of side entry

  2. Analyzing the biomass filter behavior in an anaerobic wastewater treatment plants

    Energy Technology Data Exchange (ETDEWEB)

    Carlos-Hernandez, S.

    2009-07-01

    Nowadays, waste emissions in air, water and soil must be reduced in order to reach the more and more strict environmental rules. In the case of wastewater, there exists a big interest to improve treatment plants performances. The paper deals with the analysis, via the phase portraits method, of a biomass filter behavior in a completely stirred tank reactor deals with the analysis. (Author)

  3. Arsenic bioleaching in medical realgar ore and arsenic- bearing ...

    African Journals Online (AJOL)

    medical realgar ore that allowed much higher leaching rates ... bioleaching behavior between mixed unadapted ... Acid drainage from copper mine, Zhongtiao Mountain, Shanxi,. China ..... during high temperature bioleaching of gold-bearing.

  4. Simulation on 3D flow field of stirring tank with double folded-blade and analysis on factors affecting power%双层折叶浆搅拌槽三维流场模拟及其功率影响因素分析

    Institute of Scientific and Technical Information of China (English)

    李志刚; 贾慧芳; 王健

    2013-01-01

    为了研究搅拌槽的功率及其影响因素,分别采用Bachjbhob算图、永田进治公式、流场数值模拟的方法计算搅拌槽功率.首先采用Mixsim软件建立搅拌槽模型,然后将其导入至FLUENT软件中进行三维流场模拟分析,最后通过Mixsim软件计算搅拌槽的功率,并且对影响其功率的因素进行分析.分析结果表明:3种功率计算方法的结果基本一致;在一定的范围内,随着搅拌槽的浆叶宽度、数量的增加,浆叶角度的增大,搅拌槽的功率也随之增大,液层高度对其功率影响较小.%In order to research the power of the stirring tank and its influencing factors,Bachjbhob chart,Nagata Shinji formula and numerical simulation method of the flow field were respectively used to calculate the power of the stirring tank.Firstly Mixsim software was applied to build the model of the stirring tank,and then the model was imported into FLUENT to simulate and analyze 3D flow field of the stirring tank.Finally,Mixsim software was applied to calculate the power of the stirring tank,and the factors affecting the power of the stirring tank was analyzed.The analysis results showed that:results obtained from three methods of power calculation were basically identical; during a certain range,with the increase in width of the blade,number of the blade and angle of the blade,the power of the stirring tank increased,while the liquid level had a little influence on the power of the stirring tank.

  5. Numerical Simulation of the Laminar Flow Field and Mixing Time in Stirred Tank with Double Layer Impeller%双层桨搅拌槽内层流流场与混合时间的数值模拟

    Institute of Scientific and Technical Information of China (English)

    梁瑛娜; 高殿荣; 拜亮

    2015-01-01

    The laminar model, the multiple reference frame(MRF) and the tracer concentration method are employed to simulate the laminar flow field and the mixing time of highly viscous non-Newtonian fluid in stirred tank with double layer straight impeller. The flow field characteristics, the spreading process of tracer, the responding curves of tracer concentration and the mixing time are analyzed. The tracer particles and the acid-base indicator method are used to measure the flow field and the mixing process in a transparent plexiglass stirred tank in experiment. The results show that the tracer is flowing and diffusing with main medium first in the feeding half of stirred tank because of the intermediate surface between double paddle, then diffusing to the other half when the concentration difference has increased. The shorter mixing time is obtained when feeding tracer at the blade-closed-area which stirred vigorously or at the intermediate surface. Different time are used to complete mixing at different points, so choosing reasonable monitor points with mixing require could avoid resource wasting or insufficient stirring. The mixing process of the medium in stirred tank is faster and the mixing time is shorter when increasing stirring speed. The accuracy of the numerical simulation results is verified by the experimental results. The research provides the theory basis for the design and engineering application of the laminar flow stirred tank with non-Newtonian fluid.%采用Laminar模型、多重参考系法(Multiple reference frame,MRF)和示踪剂浓度法对双层六直叶桨搅拌槽内高黏非牛顿流体层流流场和混合时间进行数值模拟,分析其流动特性、示踪剂扩散过程、示踪剂浓度响应曲线和混合时间;采用示踪粒子法和酸碱指示剂变色法对透明有机玻璃搅拌槽内流动场和混合过程进行试验测定。结果表明,双层桨中间面将示踪剂先控制在加料的半层内随主体介质流

  6. Bioleaching of copper oxide ore by Pseudomonas aeruginosa

    Science.gov (United States)

    Shabani, M. A.; Irannajad, M.; Azadmehr, A. R.; Meshkini, M.

    2013-12-01

    Bioleaching is an environmentally friendly method for extraction of metal from ores. In this study, bioleaching of copper oxide ore by Pseudomonas aeruginosa was investigated. Pseudomonas aeruginosa is a heterotrophic bacterium that can produce various organic acids in an appropriate culture medium, and these acids can operate as leaching agents. The parameters, such as particle size, glucose percentage in the culture medium, bioleaching time, and solid/liquid ratio were optimized. Optimum bioleaching conditions were found as follows: particle size of 150-177 μm, glucose percentage of 6%, bioleaching time of 8 d, and solid/liquid ratio of 1:80. Under these conditions, 53% of copper was extracted.

  7. Bioleaching of copper oxide ore by P seudomonas aeruginosa

    Institute of Scientific and Technical Information of China (English)

    MA Shabani; M Irannajad; AR Azadmehr; M Meshkini

    2013-01-01

    Bioleaching is an environmentally friendly method for extraction of metal from ores. In this study, bioleaching of copper oxide ore by Pseudomonas aeruginosa was investigated. Pseudomonas aeruginosa is a heterotrophic bacterium that can produce various organic acids in an appropriate culture medium, and these acids can operate as leaching agents. The parameters, such as particle size, glucose percentage in the culture medium, bioleaching time, and solid/liquid ratio were optimized. Optimum bioleaching conditions were found as follows: particle size of 150-177 μm, glucose percentage of 6%, bioleaching time of 8 d, and solid/liquid ratio of 1:80. Under these conditions, 53%of copper was extracted.

  8. Complete genome sequence of Peptoniphilus sp. strain ING2-D1G isolated from a mesophilic lab-scale completely stirred tank reactor utilizing maize silage in co-digestion with pig and cattle manure for biomethanation.

    Science.gov (United States)

    Tomazetto, Geizecler; Hahnke, Sarah; Maus, Irena; Wibberg, Daniel; Pühler, Alfred; Schlüter, Andreas; Klocke, Michael

    2014-12-20

    The bacterium Peptoniphilus sp. strain ING2-D1G (DSM 28672), a mesophilic and obligate anaerobic bacterium belonging to the order Clostridiales was isolated from a biogas-producing lab-scale completely stirred tank reactor (CSTR) optimized for anaerobic digestion of maize silage in co-fermentation with pig and cattle manure. In this study, the whole genome sequence of Peptoniphilus sp. strain ING2-D1G, a new isolate potentially involved in protein breakdown and acidogenesis during biomass degradation, is reported. The chromosome of this strain is 1.6Mb in size and encodes genes predicted to be involved in the production of acetate, lactate and butyrate specifying the acidogenic metabolism of the isolate.

  9. 大型侧进式搅拌釜内湍流流场的数值模拟%Numerical simulation of turbulent flow field in industrial-scale side-entering stirred tank

    Institute of Scientific and Technical Information of China (English)

    陈佳; 肖文德

    2013-01-01

    采用计算流体力学(CFD)技术对直径和高度均为13m的大型侧进式搅拌釜内均相宏观流场进行数值计算.结果表明,将计算域划分为大约90万网格时,计算得到的搅拌功率曲线与实验数据吻合较好;考察不同操作转速、搅拌桨安装角度及个数对釜内低速死区分布的影响,发现增大搅拌转速很难有效地消除水平面上的死区;搅拌桨垂直向下5.71°或水平偏转11°安装能明显改善流体运动.三桨和四桨搅拌体系对釜上部流场的优化要好于两桨体系;但在相同转速下,双桨、三桨和四桨搅拌釜的搅拌功耗分别是单桨搅拌釜的1.2倍、2.3倍和3.4倍.综合考虑,三桨体系搅拌效率较高.最后采用组分模型计算得到不同转速下三桨釜的混合时间.%Computational Fluid dynamics (CFD) technique was employed to simulate the single-phase turbulent flow field in an industrial-scale stirred tank equipped with a side-entering impeller.The calculated power curve and velocity profiles were in good agreement with the available experimental results for the finer-mesh cases with 900,000 grids in the calculation domain.The effect of impeller rotation speed and impeller layout on the mixing effect was studied.The results indicate that the increasing of impeller speed can not effectively eliminate the low velocity dead zones,and the flow pattern can be obviously improved when the impeller is inserted into the tank with a vertical angle of 5.71°or a horizontal angle of 11°.Compared with two-impeller stirred system,the three-and four-impeller systems can more obviously decrease the area of low-velocity dead zones,especially in the top part of the tank.But the total power consumption of two-,three-and four-impeller stirred tank is 1.2,2.3 and 3.4 timesthat of the single-impeller stirred tank.The mixing time of a three-impeller stirred tank under the different impeller speeds was calculated by using species model.

  10. Improving the production yield and productivity of 1,3-dihydroxyacetone from glycerol fermentation using Gluconobacter oxydans NL71 in a compressed oxygen supply-sealed and stirred tank reactor (COS-SSTR).

    Science.gov (United States)

    Zhou, Xin; Zhou, Xuelian; Xu, Yong; Yu, Shiyuan

    2016-08-01

    In this study, a compressed oxygen gas supply was connected to a sealed aerated stirred tank reactor (COS-SSTR) bio-system, leading to a high-oxygen pressure bioreactor used to improve the bio-transformative performance in the production of 1,3-dihydroxyacetone (DHA) from glycerol using Gluconobacter oxydans NL71. A concentration of 301.2 ± 8.2 g L(-1) DHA was obtained from glycerol after 32 h of fed-batch fermentation in the COS-SSTR system. The volumetric productivity for this process was 9.41 ± 0.23 g L(-1) h(-1), which is presently the highest obtained level of glycerol bioconversion into DHA. These results show that the application of this bioreactor would enable microbial production of DHA from glycerol at the industrial scale.

  11. Building and analyzing models from data by stirred tank experiments for investigation of matrix effects caused by inorganic matrices and selection of internal standards in Inductively Coupled Plasma-Atomic Emission Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Grotti, Marco [Dipartimento di Chimica e Chimica Industriale, Via Dodecaneso 31, 16146 Genova (Italy)], E-mail: grotti@chimica.unige.it; Paredes, Eduardo; Maestre, Salvador; Todoli, Jose Luis [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, 03080, Alicante (Spain)

    2008-05-15

    Interfering effects caused by inorganic matrices (inorganic acids as well as easily ionized elements) in inductively coupled plasma-atomic emission spectroscopy have been modeled by regression analysis of experimental data obtained using the 'stirred tank method'. The main components of the experimental set-up were a magnetically-stirred container and two peristaltic pumps. In this way the matrix composition was gradually and automatically varied, while the analyte concentration remained unchanged throughout the experiment. An inductively coupled plasma spectrometer with multichannel detection based on coupled charge device was used to simultaneously measure the emission signal at several wavelengths when the matrix concentration was modified. Up to 50 different concentrations were evaluated in a period of time of 10 min. Both single interfering species (nitric, hydrochloric and sulphuric acids, sodium and calcium) and different mixtures (aqua regia, sulfonitric mixture, sodium-calcium mixture and sodium-nitric acid mixture) were investigated. The dependence of the emission signal on acid concentration was well-fitted by logarithmic models. Conversely, for the easily ionized elements, 3-order polynomial models were more suitable to describe the trends. Then, the coefficients of these models were used as 'signatures' of the matrix-related signal variations and analyzed by principal component analysis. Similarities and differences among the emission lines were highlighted and discussed, providing a new insight into the interference phenomena, mainly with regards to the combined effect of concomitants. The combination of the huge amount of data obtained by the stirred tank method in a short period of time and the speed of analysis of principal component analysis provided a judicious means for the selection of the optimal internal standard in inductively coupled plasma-atomic emission spectroscopy.

  12. Upscaling of an electronic nose for completely stirred tank reactor stability monitoring from pilot-scale to real-scale agricultural co-digestion biogas plant.

    Science.gov (United States)

    Adam, Gilles; Lemaigre, Sébastien; Goux, Xavier; Delfosse, Philippe; Romain, Anne-Claude

    2015-02-01

    This study investigated the use of an electronic nose for on-line anaerobic reactor state monitoring at the pilot-scale level and then upscaling to the full-scale level. E-nose indicator was compared to classical state indicators such as pH, alkalinity, volatile fatty acids concentration and to other gas phase compounds. Multivariate statistical process control method, based on principal component analysis and the Hotelling's T(2) statistics was used to derive an indicator representative of the reactor state. At the pilot-scale level, the e-nose indicator was relevant and could distinguish 3 process states: steady-state, transient and collapsing process. At the full-scale level, the e-nose indicator could provide the warning of the major disturbance whereas two slight disturbances were not detected and it gave one major false alarm. This work showed that gas phase relation with anaerobic process should be deeper investigated, as an e-nose could indicate the reactor state, focusing on the gas phase.

  13. Enhanced bioleaching on attachment of indigenous acidophilic bacteria to pyrite surface

    Science.gov (United States)

    Wi, D. W.; Cho, K. H.; Kim, B. J.; Choi, N. C.; Park, C. Y.

    2012-04-01

    In recent years, bioleaching has been widely applied on an industrial scale due to the advantages of low cost and environment friendliness. The direct contact mechanism of bioleaching assumes the action of a metal sulfide-attached cell oxidizing the mineral by an enzyme system with oxygen to sulfate and metal cations. Fundamental surface properties of sulfide particles and leaching-bacteria in bioleaching play the key role in the efficiency of this process. The aim of this work is to investigate of direct contact bioleaching mechanism on pyrite through attachment properties between indigenous acidophilic bacteria and pyrite surfaces. The bacteria were obtained from sulfur hot springs, Hatchobaru thermal electricity plant in Japan. And pyrite was collected from mine waste from Gwang-yang abandoned gold mines, Korea. In XRD analyses of the pyrite, x-ray diffracted d-value belong to pyrite was observed. The indigenous acidophilic bacteria grew well in a solution and over the course of incubation pH decreased and Eh increased. In relation to a bacterial growth-curve, the lag phase was hardly shown while the exponential phase was very fast. Bioleaching experiment result was showed that twenty days after the indigenous acidophilic bacteria were inoculated to a pyrite-leaching medium, the bacterial sample had a greater concentration of Fe and Zn than within the control sample. In SEM-EDS analyses, rod-shaped bacteria and round-shaped microbes were well attached to the surface of pyrite. The size of the rod-shaped bacteria ranged from 1.05~1.10 ? to 4.01~5.38 ?. Round-shaped microbes were more than 3.0 ? in diameter. Paired cells of rod-shaped bacteria were attached to the surface of pyrite linearly.

  14. Bioleaching of heavy metals from sewage sludge using Acidithiobacillus thiooxidans

    Science.gov (United States)

    Wen, Ye-Ming; Lin, Hong-Yan; Wang, Qing-Ping; Chen, Zu-Liang

    2010-11-01

    Acidithiobacillus thiooxidans was isolated from sewage sludge using the incubation in the Waksman liquor medium and the inoculation in Waksman solid plate. It was found that the optimum conditions of the bioleaching included solid concentration 2%, sulfur concentration 5 gṡL-1 and cell concentration 10%. The removal efficiency of Cr, Cu, Pb and Zh in sewage sludge, which was obtained from waste treatment plant, Jinshan, Fuzhou, was 43.65%, 96.24%, 41.61% and 96.50% in the period of 4˜10 days under the optimum conditions, respectively. After processing using the proposed techniques, the heavy metals in sewage sludge did meet the requirement the standards of nation.

  15. Robust L2-L∞ Control for Continuous Stirred Tank Reactor Based on T-S Model%基于T-S模型的连续搅拌反应釜鲁棒L2-L∞控制

    Institute of Scientific and Technical Information of China (English)

    李艳辉; 冯岩

    2014-01-01

    To realize precise control for CSTR( Continuous Stirring Tank Reactor) systems in actual reactions, a robust L2-L∞ state feedback control problem is studied by using a T-S fuzzy model to approximate the nonlinear object according to reaction characteristics of the CSTR. All reactor temperatures which are easier to be measured can be treated as premise variables in the model, where fewer number of fuzzy rules are employed. The design method of partial controllers is given by applying the PDC ( Parallel Distributed Compensation ) algorithm. A global controller is designed by adopting the LMI ( Linear Matrix Inequality ) technique, and the design of controllers is cast into a convex optimization problem. Simulations are provided to demonstrate the effectiveness of the proposed design scheme, which can be applied to other chemical industrial reactions.%为实现对连续搅拌反应釜( CSTR:Continuous Stirring Tank Reactor)系统在实际反应中的精确控制,根据CSTR反应特点,采用T-S模糊模型逼近非线性对象,研究鲁棒L2-L∞状态反馈控制问题。模型中将更易测量的反应器温度作为前件变量,模糊规则少。应用平行分配补偿算法( PDC:Parallel Distributed Compensation),给出局部控制器的设计方法,并利用线性矩阵不等式( LMI:Linear Matrix Inequality)技术设计全局控制器,在此基础上把控制器的设计转化为一个凸优化的求解问题。最后仿真验证了该方法的有效性,从而可扩展到其他化学工业反应中。

  16. Comparison of a production process in a membrane-aerated stirred tank and up to 1000-L airlift bioreactors using BHK-21 cells and chemically defined protein-free medium.

    Science.gov (United States)

    Hesse, Friedemann; Ebel, Maria; Konisch, Nadine; Sterlinski, Reinhard; Kessler, Wolfgang; Wagner, Roland

    2003-01-01

    The applicability of a protein-free medium for the production of recombinant human interleukin-2 with baby hamster kidney cells in airlift bioreactors was investigated. For this purpose, a BHK-21 cell line, adapted to grow and produce in protein-free SMIF7 medium without forming spheroids in membrane-aerated bubble-free bioreactors, was used as the producer cell line. First, cultivation of the cells was established at a 20-L scale using an internal loop airlift bioreactor system. During the culturing process the medium formulation was optimized according to the specific requirements associated with cultivation of mammalian cells under protein-free conditions in a bubble-aerated system. The effects of the addition of an antifoam agent on growth, viability, productivity, metabolic rates, and release of lactate dehydrogenase were investigated. Although it was possible to establish cultivation and production at a 20-L scale without the use of antifoaming substances, the addition of 0.002% silicon-oil-based antifoaming reagent improved the cultivation system by completely preventing foam formation. This reduced the release of lactate dehydrogenase activity to the level found in bubble-free aerated stirred tank membrane bioreactors and led to a reduction in generation doubling times by about 5 h (17%). Using the optimized medium formulation, cells were cultivated at a 1000-L scale, resulting in a culture performance comparable to the 20-L airlift bioreactor. For comparison, cultivations with protein-containing SMIF7 medium were carried out at 20- and 1000-L scales. The application of protein supplements did not lead to a significant improvement in the cultivation conditions. The results were also compared with experiments performed in a bubble-free aerated stirred tank membrane bioreactor to evaluate the influence of bubbles on the investigated culture parameters. The data implied a higher metabolic activity of the cells in airlift bioreactors with a 150% higher glucose

  17. Computational fluid dynamics (CFD) tools for investigating flow and mixing in industrial systems: The Koch-Glitsch SMX(RTM) static mixer and a three Rushton turbine stirred tank

    Science.gov (United States)

    Zalc, Jeffrey Michael

    2000-11-01

    A suite of numerical tools, encompassing both commercial software and algorithms developed over the course of this dissertation research, is implemented for a detailed analysis of laminar flow and mixing in two industrial systems. A four element SMX static mixer geometry and a batch stirred tank equipped with three Rushton turbines are considered. Computational fluid dynamics (CFD) is used to compute the fully three-dimensional flow fields over tine unstructured tetrahedral meshes; at least ten flow conditions are considered for each system. Particle tracking routines are then employed to characterize the velocity components, pressure fields, and local mixing rates. Lagrangian mixing analysis is based on the dispersion of tracer particles. The stretching of fluid elements is used to quantify mixing performance. In the SMX static mixer, CFD results are validated through comparison of computed pressure drops with experimental results reported in the literature. Flow behavior is characterized by contour plots and probability density functions of velocity components and the magnitude of the deformation tensor. It is found that the flow in the static mixer is essentially independent of flow rate up through a Reynolds number of 1, beyond which inertial effects become significant and substantial differences in the nature of the flow are observed. Computed mixing patterns exhibit self-similarity and asymptotic directionality, which are fingerprints of chaotic behavior. Statistical characterization of the partially mixed structures reveals an exponential decay of the coefficient of variance with increasing axial distance. In the three Rushton turbine stirred tank, planar velocity vectors extracted from the CFD results are compared with experimental results obtained from particle imaging velocimetry (PIV). Planar laser-induced fluorescence (PLIF) and Poincare sections are both used to expose persistent poor-mixing regions, whose sizes and shapes depend strongly on the

  18. Numerical simulation of mixing process in a silicone oil emulsion stirred tank with gate impeller%硅油乳状液体系搅拌槽内混合过程的数值模拟

    Institute of Scientific and Technical Information of China (English)

    倪邦庆; 王秋实; 范明明

    2012-01-01

    Stirred reactors are widely used in many industrial processes. The mixing process in a stirred tank of 0.0465 m radius with gate impeller was numerically simulated by using computational fluid dynamics (CFD) package FLUENT 6.3.26. The multi-reference frame (MRF), standard k -εturbulent model and SIMPLE Pressure-velocity coupling were used in the simulation. The mixing predicted in Silicone oil emulsion by CFD is in 1200 r-min-1 agreement with the experiment. Velocity field, concentration field were respectively studied. The effects of tracer feeding and detecting positions on mixing time were investigated. The mixing process is dominated by the flow field in the stirred tank. For certain detecting positions, comparing with the tracer feeding at the liquid surface, the mixing time detected is different. For certain feeding positions, the shortest mixing time is detected by the detectors located at the bottom region, the next shortest and the considerably longer mixing time are detected by the detectors located at the impeller region and the liquid surface, respectively.%在FLUENT6.3.26软件平台上,采用多重参考系和标准k-ε湍流模型、SIMPLE压力-速度耦合算法对硅油乳状液体系搅拌槽内流场进行模拟.模拟以中粘乳状液为物系,采用0.0465 m半径的搅拌槽及框式搅拌浆,在和实验相同的1200 r.min-1转速的流场进行模拟.计算了上述条件下的速度场和浓度场.同时采用数值模拟方法研究了在不同示踪剂监控点的混合规律,并对模拟结果进行可视化定量研究分析.模拟结果表明,混合过程由搅拌槽内流体流动控制,混合时间与示踪剂监控点位置密切相关.

  19. Liquid mixing and Curcumin nanoparticle preparation in stirred tanks%搅拌釜内液-液混合溶析沉淀法制备纳米姜黄素颗粒

    Institute of Scientific and Technical Information of China (English)

    赵述芳; 王文坦; 胡银玉; 邵婷; 金涌; 程易

    2013-01-01

    The preparation of Curcumin nanoparticles was realized in a small stirred tank by the anti-solvent precipitation process. The influences of such factors as tank size, stirring style, initial concentration and rotation speed on nanoparticle preparation were investigated. Meanwhile, planar laser induced fluorescence (PLIF) technique was used to quantitatively measure the liquid-liquid mixing performance in the tank, and the mixing environment was found to be important for the preparation of nanoparticles. A low stirring speed in a small stirred tank with a turbine impeller could not achieve the desired mixing efficiency because of agglomeration of nanoparticles. An overly high stirring speed brought in strong shearing interaction between particles and fluid so that many particles were broken up. Overly high over-saturation in local areas would cause growth and agglomeration of particles. The optimal mixing environment with moderate process intensification was crucial to successfully prepare high quality Curcumin nanoparticles with spherical shape and narrow size distribution.%研究了在搅拌釜内利用溶析沉淀法制备姜黄素纳米颗粒的过程,分别探讨了搅拌釜尺寸、搅拌形式、初始浓度以及搅拌转速对制备结果的影响.通过平面激光诱导荧光技术定量测量釜内液液混合行为,揭示了流体混合环境的控制是决定溶析沉淀产品过程的关键因素.实验表明,搅拌速度过低无法保证流体混合效率,将导致颗粒黏结;搅拌速度过高带来颗粒与流场的强剪切作用,引起颗粒破碎;局部过饱和度过大,引起颗粒的生长和聚团.搅拌釜内纳米颗粒制备需提供适度强化的流体混合环境.

  20. pH值对纯菌种Ethanologenbacterium sp.nov R3产氢的影响%Effects of pH value on fermentative biohydrogen production with Ethanologenbacterium sp. nov R3 in continous stirred tank reactor

    Institute of Scientific and Technical Information of China (English)

    史沫男; 林永波; 邓洁璇; 陈红; 李永峰

    2011-01-01

    In this paper, Ethanologenbacterium sp. nov R3 was used as research microbe which was inoculated from continuous stirred tank reactor (CSTR). The temperature and HRT of CSTR were controlled at ( 35 ± 1 ) ℃ and 8 h respectively. The effects of influent pH value on fermentative biohydrogen production with R3 were showed in this paper. When influent pH value was 5.5, the capacity of R3 to produce hydrogen was best. In this influent pH value, biogas yield and hydrogen content respectively achieved 6.85 ~ 8.86 L/d and 59.44% ~65. 13%. COD removal and effluent pH value were mainly stable at 26% and 4.38.The average concentration of ethanol and acetic acid in VFAs were respectively 706 mg/L and 446 mg/L. R3 maintained ethanol - type fermentation characteristics all along.%以Ethanologenbacterium sp.nov R3(以下称为R3)为研究对象,将其接种入连续搅拌槽式反应器(continuous stirred tank reactor,CSTR)中进行发酵产氢实验,以葡萄饮料废水为底物,温度控制在(35±1)℃,水力停留时间为8 h,探讨了不同的进水pH值对纯菌种R3连续流厌氧发酵生物制氢的影响.实验证明,当进水pH值为5.5时R3的厌氧发酵产氢能力最强.此时,产气量和氢气体积分数分别达到了6.85~8.86L/d和59.44%~65.13%,COD去除率稳定在26%左右,出水pH值稳定在4.38左右.在总挥发酸中,乙醇和乙酸的平均质量浓度分别是706mg/L和446 mg/L.整个过程中,R3始终保持乙醇型发酵特性.

  1. Bioleaching of low-grade copper sulphides

    Institute of Scientific and Technical Information of China (English)

    YIN Sheng-hua; WU Ai-xiang; QIU Guan-zhou

    2008-01-01

    The bioleaching behavior of low-grade copper sulphides under the condition of preferential solution flow was investigated through experiments.The experiment of bioleaching was conducted within the multifunction autocontrol bioleaching apparatus.The results show that the concentrations of Cu2+ and total Fe increase slowly at the beginning.The recovery rate decreases with the increase of depth of dump.The preferential solution happens within the fine region when the application rate is low,and the recovery rate of the fine region is higher than that of the coarse region.The content of fine ore particles within both fine and coarse regions increases during the leaching period,and the preferential solution flow shifts from fine region to coarse region.The surface of the ores at the top of dump is attacked seriously,and the ores in the middle is attacked slightly.There are plenty of crackles on the surface of bottom ores because of the precipitation layer on the surface.

  2. Chemoorganotrophic Bioleaching of Olivine for Nickel Recovery

    Directory of Open Access Journals (Sweden)

    Yi Wai Chiang

    2014-06-01

    Full Text Available Bioleaching of olivine, a natural nickel-containing magnesium-iron-silicate, was conducted by applying chemoorganotrophic bacteria and fungi. The tested fungus, Aspergillus niger, leached substantially more nickel from olivine than the tested bacterium, Paenibacillus mucilaginosus. Aspergillus niger also outperformed two other fungal species: Humicola grisae and Penicillium chrysogenum. Contrary to traditional acid leaching, the microorganisms leached nickel preferentially over magnesium and iron. An average selectivity factor of 2.2 was achieved for nickel compared to iron. The impact of ultrasonic conditioning on bioleaching was also tested, and it was found to substantially increase nickel extraction by A. niger. This is credited to an enhancement in the fungal growth rate, to the promotion of particle degradation, and to the detachment of the stagnant biofilm around the particles. Furthermore, ultrasonic conditioning enhanced the selectivity of A. niger for nickel over iron to a value of 3.5. Pre-carbonating the olivine mineral, to enhance mineral liberation and change metal speciation, was also attempted, but did not result in improvement as a consequence of the mild pH of chemoorganotrophic bioleaching.

  3. Ce-Zr-La/Al2O3 prepared in a continuous stirred-tank reactor: a highly thermostable support for an efficient Rh-based three-way catalyst.

    Science.gov (United States)

    Wang, Su-Ning; Lan, Li; Hua, Wei-Bo; Shi, Zhong-Hua; Chen, Yao-Qiang; Gong, Mao-Chu; Zhong, Lin

    2015-12-21

    Two Ce-Zr-La/Al2O3 composite oxides, CZLA-C and CZLA-B, were synthesized using a co-precipitation method in a continuous stirred-tank reactor (CSTR) and a batch reactor (BR), respectively. Two Rh-based three-way catalysts (TWCs), Rh/CZLA-C and Rh/CZLA-B were obtained by a wet-impregnation method using the two composites as the supports. The physicochemical properties of the samples before and after thermal treatment at 1000 °C were characterized by N2 adsorption-desorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), H2-temperature programmed reduction (H2-TPR) and CO chemisorption. The results indicated that CZLA-C shows higher thermal stability than CZLA-B due to a sparsely-agglomerated morphology. Compared with Rh/CZLA-B, Rh/CZLA-C displayed better reducibility and higher thermal stability and exhibited significantly higher activity in the catalytic removal of the simulated gasoline vehicle exhaust emission (NO, CO and C3H8). Our work can provide a facile and economical synthesis route to advanced support materials and catalysts for exhaust emission control.

  4. Hinfinity control for continuous stirred tank reactor based on Takagi-Sugeno fuzzy bilinear models%基于Takagi-Sugeno模糊双线性模型的连续搅拌反应釜H∞控制

    Institute of Scientific and Technical Information of China (English)

    陈珺; 刘飞

    2012-01-01

    This paper is concerned with the H-infinity control for a class of continuous stirred tank reactor (CSTR) systems, in which the nonlinear dynamics are described by TakagiSugeno fuzzy bilinear models. By introducing two free matrix variables, we derive a new sufficient condition, in terms of linear matrix inequalities, of the global stability with a prescribed Hinfinity performance level for the closedloop fuzzy bilinear systems. The controller design method is also given. Simulation results of a CSTR system illustrate the effectiveness of the design method.%本文研究了一类连续搅拌反应釜(CSTR)系统的H∞控制问题.系统中的非线性动态特性可采)用Takagi-Sugeno(T-S)模糊双线性模型进行描述.通过引入两个自由矩阵,给出一个新的保证闭环模糊双线性系统在H∞性能指标下全局渐近稳定的充分条件和控制器设计方法,并且该条件最终可归结为求解一组线性矩阵不等式的可行性问题.CSTR系统的仿真结果表明设计方法的有效性.

  5. 偏心搅拌槽内颗粒悬浮特性的试验研究%Experimental Study on Critical Suspension Speed of Shaft in Eccentrically Stirred Tank

    Institute of Scientific and Technical Information of China (English)

    杨敏官; 冯浪; 康灿; 车占富

    2012-01-01

    利用固体激光发生器和扭矩仪对固体颗粒体积浓度为5%的偏心搅拌槽内颗粒的悬浮特性进行试验研究,分析了偏心率、转速和桨叶离底高度对临界悬浮转速、功率消耗和混合时间的影响.研究发现,偏心搅拌能改善颗粒分布效果,降低混合时间,并提高颗粒的临界悬浮转速和功率消耗.%Solid-liquid suspension performance in eccentrically stirred tank is investigated with experimental method by using solid-state laser generator and torque sensor. The volume concentration of the solid particles is 5%. This paper mainly analyzes the influence of eccentricity, rotational speed and the height of agitator from bottom of the vessel on critical suspension speed, power consumption and mixed time. It has been shown that eccentric stirring can improve the effectiveness of particle distribution and reduce mixed time obviously, which can raise the critical suspension speed and power consumption.

  6. Anaerobic co-digestion of cheese whey and the screened liquid fraction of dairy manure in a single continuously stirred tank reactor process: Limits in co-substrate ratios and organic loading rate.

    Science.gov (United States)

    Rico, Carlos; Muñoz, Noelia; Rico, José Luis

    2015-01-01

    Mesophilic anaerobic co-digestion of cheese whey and the screened liquid fraction of dairy manure was investigated with the aim of determining the treatment limits in terms of the cheese whey fraction in feed and the organic loading rate. The results of a continuous stirred tank reactor that was operated with a hydraulic retention time of 15.6 days showed that the co-digestion process was possible with a cheese whey fraction as high as 85% in the feed. The efficiency of the process was similar within the range of the 15-85% cheese whey fraction. To study the effect of the increasing loading rate, the HRT was progressively shortened with the 65% cheese whey fraction in the feed. The reactor efficiency dropped as the HRT decreased but enabled a stable operation over 8.7 days of HRT. At these operating conditions, a volumetric methane production rate of 1.37 m(3) CH4 m(-3) d(-1) was achieved.

  7. Importance of reduced sulfur for the equilibrium chemistry and kinetics of Fe(II), Co(II) and Ni(II) supplemented to semi-continuous stirred tank biogas reactors fed with stillage.

    Science.gov (United States)

    Shakeri Yekta, Sepehr; Lindmark, Amanda; Skyllberg, Ulf; Danielsson, Asa; Svensson, Bo H

    2014-03-30

    The objective of the present study was to assess major chemical reactions and chemical forms contributing to solubility and speciation of Fe(II), Co(II), and Ni(II) during anaerobic digestion of sulfur (S)-rich stillage in semi-continuous stirred tank biogas reactors (SCSTR). These metals are essential supplements for efficient and stable performance of stillage-fed SCSTR. In particular, the influence of reduced inorganic and organic S species on kinetics and thermodynamics of the metals and their partitioning between aqueous and solid phases were investigated. Solid phase S speciation was determined by use of S K-edge X-ray absorption near-edge spectroscopy. Results demonstrated that the solubility and speciation of supplemented Fe were controlled by precipitation of FeS(s) and formation of the aqueous complexes of Fe-sulfide and Fe-thiol. The relatively high solubility of Co (∼ 20% of total Co content) was attributed to the formation of compounds other than Co-sulfide and Co-thiol, presumably of microbial origin. Nickel had lower solubility than Co and its speciation was regulated by interactions with FeS(s) (e.g. co-precipitation, adsorption, and ion substitution) in addition to precipitation/dissolution of discrete NiS(s) phase and formation of aqueous Ni-sulfide complexes. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Improvement of the conversion of polystyrene to polyhydroxyalkanoate through the manipulation of the microbial aspect of the process: a nitrogen feeding strategy for bacterial cells in a stirred tank reactor.

    Science.gov (United States)

    Goff, Miriam; Ward, Patrick G; O'Connor, Kevin E

    2007-11-01

    Pseudomonas putida CA-3 has been shown to accumulate the biodegradable plastic polyhydroxyalkanoate (PHA) when fed styrene or polystyrene pyrolysis oil as the sole carbon and energy source under nitrogen limiting growth conditions (67 mg nitrogen per litre at time 0). Batch fermentation of P. putida CA-3 grown on styrene or polystyrene pyrolysis oil in a stirred tank reactor yields PHA at 30% of the cell dry weight (CDW). The feeding of nitrogen at a rate of 1mg N/l/h resulted in a 1.1-fold increase in the percentage of CDW accumulated as PHA. An increase in the rate of nitrogen feeding up to 1.5mg N/l/h resulted in further increases in the percentage of the cell dry weight composed of PHA. However, feeding rates of 1.75 and 2mg N/l/h resulted in dramatic decreases in the percentage of cell dry weight composed of PHA. Interestingly nitrogen was not detectable in the growth medium after 16 h, in any of the growth conditions tested. A higher cell density was observed in cells supplied with nitrogen and thus further increases in the overall production of PHA were observed through nitrogen feeding. The highest yield of PHA was 0.28 g PHA per g styrene supplied with a nitrogen feeding rate of 1.5mg/l/h.

  9. The influence of metal speciation in combustion waste on the efficiency of Cu, Pb, Zn, Cd, Ni and Cr bioleaching in a mixed culture of sulfur-oxidizing and biosurfactant-producing bacteria.

    Science.gov (United States)

    Karwowska, Ewa; Wojtkowska, Małgorzata; Andrzejewska, Dorota

    2015-12-15

    Metal leachability from ash and combustion slag is related to the physico-chemical properties, including their speciation in the waste. Metals speciation is an important factor that influences the efficiency of metal bioleaching from combustion wastes in a mixed culture of acidophilic and biosurfactant-producing bacteria. It was observed that individual metals tended to occur in different fractions, which reflects their susceptibility to bioleaching. Cr and Ni were readily removed from wastes when present with a high fraction bound to carbonates. Cd and Pb where not effectively bioleached when present in high amounts in a fraction bound to organic matter. The best bioleaching results were obtained for power plant slag, which had a high metal content in the exchangeable, bound to carbonates and bound to Fe and Mg oxides fractions- the metal recovery percentage for Zn, Cu and Ni from this waste exceeded 90%.

  10. Bioleaching of marmatite in high concentration of iron

    Institute of Scientific and Technical Information of China (English)

    邱冠周; 吴伯增; 覃文庆; 蓝卓越

    2002-01-01

    Bioleaching of marmatite with a culture of Thiobacillus ferrooxidans and Thiobacillus thiooxidans in high concentration of iron was studied, the results show that the zinc leaching rate of the mixed culture is faster than that of the sole Thiobacillus ferrooxidans, the increasing iron concentration in leaching solution enhances the zinc leaching rate. The SEM analysis indicates that the chemical leaching residues is covered with porous solid layer of elemental sulfur, while elemental sulfur is not found in the bacterial leaching residues. The primary role of bacteria in bioleaching of sphalerite is to oxidize the chemical leaching products of ferrous ion and elemental sulfur, thus the indirect mechanism prevails in the bioleaching of marmatite.

  11. Importance of reduced sulfur for the equilibrium chemistry and kinetics of Fe(II), Co(II) and Ni(II) supplemented to semi-continuous stirred tank biogas reactors fed with stillage

    Energy Technology Data Exchange (ETDEWEB)

    Shakeri Yekta, Sepehr, E-mail: sepehr.shakeri.yekta@liu.se [Department of Thematic Studies – Water and Environmental Studies, Linköping University, SE-581 83 Linköping (Sweden); Lindmark, Amanda [Department of Thematic Studies – Water and Environmental Studies, Linköping University, SE-581 83 Linköping (Sweden); Skyllberg, Ulf [Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå (Sweden); Danielsson, Åsa; Svensson, Bo H. [Department of Thematic Studies – Water and Environmental Studies, Linköping University, SE-581 83 Linköping (Sweden)

    2014-03-01

    Highlights: • Thermodynamics and kinetics of Fe, Co and Ni added to biogas reactors were studied. • Formation of Fe-sulfide and Fe-thiol aqueous complexes controlled the Fe solubility. • Cobalt solubility was controlled by processes independent of Co-sulfide interaction. • Iron added to the biogas reactors effected the Ni speciation and solubility. - Abstract: The objective of the present study was to assess major chemical reactions and chemical forms contributing to solubility and speciation of Fe(II), Co(II), and Ni(II) during anaerobic digestion of sulfur (S)-rich stillage in semi-continuous stirred tank biogas reactors (SCSTR). These metals are essential supplements for efficient and stable performance of stillage-fed SCSTR. In particular, the influence of reduced inorganic and organic S species on kinetics and thermodynamics of the metals and their partitioning between aqueous and solid phases were investigated. Solid phase S speciation was determined by use of S K-edge X-ray absorption near-edge spectroscopy. Results demonstrated that the solubility and speciation of supplemented Fe were controlled by precipitation of FeS(s) and formation of the aqueous complexes of Fe-sulfide and Fe-thiol. The relatively high solubility of Co (∼20% of total Co content) was attributed to the formation of compounds other than Co-sulfide and Co-thiol, presumably of microbial origin. Nickel had lower solubility than Co and its speciation was regulated by interactions with FeS(s) (e.g. co-precipitation, adsorption, and ion substitution) in addition to precipitation/dissolution of discrete NiS(s) phase and formation of aqueous Ni-sulfide complexes.

  12. Aperiodicity resulting from two-cycle coupling in the Belousov-Zhabotinskii reaction. III. Analysis of a model of the effect of spatial inhomogeneities at the input ports of a continuous-flow, stirred tank reactor

    Science.gov (United States)

    Györgyi, László; Field, Richard J.

    1989-11-01

    Deterministic chaos is a well-established phenomenon in continuous-flow, stirred tank reactor (CSTR) experiments with the oscillatory Belousov-Zhabotinskii (BZ) reaction. However, it has not yet been possible to reproduce the experimentally observed, robust chaos in simulations using realistic models of the homogeneous chemical kinetics of the BZ reaction. That it may be necessary to consider spatial inhomogeneities in modeling the BZ chaos is suggested by the existence of strong stirring effects on the aperiodic behavior and by the difficulty of reproducing chaos under the same conditions in reactors of different physical configuration. Such inhomogeneity might result from a lack of perfect mixing in the CSTR, especially near the inlets, or from diffusion of species at low flow rates from the CSTR reaction mixture into the tips of the inlets. The presence of spatial inhomogeneities allows coupling between essentially independent oscillators, a well-known source of chaos. Such a model using a realistic representation of the BZ kinetics leads to an eight-variable set of ordinary differential equations. Numerical analysis of these equations by continuation methods and by numerical integration shows the existence of broad regions of chaos and various hysteresis effects involving limit cycles, a steady state and/or a strange attractor. Tristability was found in calculations in a narrow flow rate range. The computed behavior appears for parameter values closely related to the values used experimentally to obtain similar phenomena, and the visual similarity of the computed and experimental strange attractors is striking. The experimental routes to chaos, period doubling, intermittency, and secondary Hopf bifurcations are all reproduced in the simulations. The computed and experimental structures of periodic windows observed within chaotic regions also are very similar.

  13. Neural network predictive control of continuous stirred-tank reactor based on Hammerstein-Wiener model%基于Hammerstein-Wiener模型的连续搅拌反应釜神经网络预测控制

    Institute of Scientific and Technical Information of China (English)

    满红; 邵诚

    2011-01-01

    针对化工过程中广泛使用的连续搅拌反应釜(CSTR),提出一种基于神经网络的模型预测控制策略,采用分段最小二乘支持向量机辨识Hammerstein-Wiener模型系数的方法,在此基础上建立线性自回归模式(ARX)结构和高斯径向基神经网络串联的非线性预测控制器.利用BP神经网络训练预测控制输入序列和拟牛顿算法求解非线性预测控制律,从而实现一种基于支持向量机Hammerstein-Wiener辨识模型的非线性神经网络预测控制算法.对CSTR的仿真结果表明,该方法能够更有效地跟踪控制反应物浓度.%A model predictive control strategy based on neural network is presented for a continuous stirred tank reactor (CSTR). A segmentation method was adopted to identify Hammerstein-Wiener model coefficient by least squares support vector machines and then to construct a nonlinear predictive controller which was by a linear optimal component and radial basis function neural networks in series. A nonlinear predictive control algorithm based on least support vector machines Hammerstein-Wiener model was realized by using BP neural network to train predictive input sequences and to solve nonlinear predictive control rules by Quasi-Newton method. The simulation results of CSTR illustrate that this approach is effective tracking and controlling product concentration.

  14. Evaluation of the Small-Tank Tetraphenylborate Process Using a Bench-Scale, 20-L Continuous Stirred Tank Reactor System at Oak Ridge National Laboratory: Results of Test 5

    Energy Technology Data Exchange (ETDEWEB)

    Lee, D.D.

    2001-08-30

    The goal of the Savannah River Salt Waste Processing Program (SPP) is to evaluate the presently available technologies and select the most effective approach for treatment of high-level waste salt solutions currently stored in underground tanks at the U.S. Department of Energy's Savannah River Site in Aiken, South Carolina. One of the three technologies currently being developed for this application is the Small-Tank Tetraphenylborate Process (STTP). This process uses sodium tetraphenylborate (TPB) to precipitate and remove radioactive cesium from the waste and monosodium titanate (MST) to sorb and remove radioactive strontium and actinides. Oak Ridge National Laboratory is demonstrating this process at the 1:4000 scale using a 20-L-capacity continuous-flow stirred-tank reactor (CSTR) system. Since March 1999, five operating campaigns of the 20-L CSTR have been conducted. The ultimate goal is to verify that this process, under certain extremes of operating conditions, can meet the minimum treatment criteria necessary for processing and disposing of the salt waste at the Savannah River Saltstone Facility. The waste acceptance criteria (WAC) for {sup 137}Cs, {sup 90}Sr, and total alpha nuclides are <40 nCi/g, <40 nCi/g, and <18 nCi/g, respectively. However, to allow for changes in process conditions, the SPP is seeking a level of treatment that is about 50% of the WAC. The bounding separation goals for {sup 137}Cs and {sup 90}Sr are to obtain decontamination factors (DFs) of 40,000 (99.998% removal) and 26 (96.15% removal), respectively. (DF is mathematically defined as the concentration of contaminant in the waste feed divided by the concentration of contaminant in the effluent stream.)

  15. 涡流桨搅拌槽内流动非稳定性的大涡模拟%Large Eddy Simulations of Flow Instabilities in a Stirred Tank Generated by a Rushton Turbine

    Institute of Scientific and Technical Information of China (English)

    樊建华; 王运东; 费维扬

    2007-01-01

    The aim of this work is to investigate the flow instabilities in a baffled,stirred tank generated by a single Rushton turbine by means of large eddy simulation (LES).The sliding mesh method was used for the coupling between the rotating and the stationary frame of references.The calculations were carried out on the "Shengcao-21C" supercomputer using a computational fluid dynamics (CFD) code CFX5.The flow fields predicted by the LES simulation and the simulation using standard k-ε model were compared to the results from particle image velocimetry (PIV) measurements.It is shown that the CFD simulations using the LES approach and the standard k-ε model agree well with the PIV measurements.Fluctuations of the radial and axial velocity are predicted at different frequencies by the LES simulation.Velocity fluctuations of high frequencies are seen in the impeller region,while low frequencies velocity fluctuations are observed in the bulk flow.A low frequency velocity fluctuation with a nondimensional frequency of 0.027Hz is predicted by the LES simulation,which agrees with experimental investigations in the literature.Flow circulation patterns predicted by the LES simulation are asymmetric,stochastic and complex,spanning a large portion of the tanks and varying with time,While circulation patterns calculated by the simulation using the standard k-ε model are symmetric.The results of the present work give better understanding to the flow instabilities in the mechanically agitated tank.However,further analysis of the LES calculated velocity Series by means of fast Fourier transform (FFT) and/or spectra analysis are recommended in future work in order to gain more knowledge of the complicated flow phenomena.

  16. Bioleaching of marmatite using moderately thermophilic bacteria

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hong-bo; LIU Fei-fei; ZOU Ying-qin; ZENG Xiao-xi; QIU Guan-zhou

    2008-01-01

    The process of bioleaching marmatite using moderately thermophilic bacteria was studied by comparing marmatite leaching performance of mesophiles and moderate thermophiles and valuating the effect of venting capacity as well as pulp density on marmatite leaching performance of moderate thermophiles. The results show that moderate thermophiles have more advantages over mesophilies in bioleaching marmatite at 45℃ and the pulp density of 50g/L, and the zinc extraction efficiency reaches 93.1% in 20d. Aeration agitation can improve the transfer of O2 and CO2 in solution and promote the growth of bacteria and therefore, enhance the leaching efficiency. Under the venting levels of 50, 200 and 800mL/min, the zinc extraction efficiencies by moderate thermophiles are 57.8%, 92.5% and 96.0%, respectively. With the increase of pulp density, the total leaching amount of valuable metals increases, however, the extraction efficiency decreases due to many reasons, such as increasing shear force leading to poorly growth condition for bacteria, etc. The zinc extraction decreases remarkably to 58.9% while the pulp density mounts up 20%.

  17. Bioleaching of pollymetallic sulphide concentrate using thermophilic bacteria

    Directory of Open Access Journals (Sweden)

    Vuković Milovan

    2014-01-01

    Full Text Available An extreme thermophilic, iron-sulphur oxidising bacterial culture was isolated and adapted to tolerate high metal and solids concentrations at 70°C. Following isolation and adaptation, the culture was used in a batch bioleach test employing a 5-l glass standard magnetic agitated and aerated reactor, for the bioleaching of a copper-lead-zinc collective concentrate. The culture exhibited stable leach performance over the period of leach operation and overall copper and zinc extractions higher than 97%. Lead sulphide is transformed into lead sulphate remaining in the bioleach residue due to the low solubility in sulphate media. Brine leaching of bioleach residue yields 95% lead extraction. [Projekat Ministarstva nauke Republike Srbije, br. 34023

  18. Stepwise dissolution of chalcopyrite bioleaching by thermophileA.manzaensis and mesophileL. ferriphilum

    Institute of Scientific and Technical Information of China (English)

    顾帼华; 熊先学; 胡可婷; 李双棵; 王重庆

    2015-01-01

    Chalcopyrite dissolution was evaluated by bioleaching and electrochemical experiments with thermophileA. manzaensis (Acidianus manzaensis) and mesophileL. ferriphilum (Leptospirillum ferriphium) cultures at 65 °C and 40 °C, respectively. It was investigated that the bioleaching of chalcopyrite was stepwise. It was reduced to Cu2S at a lower redox potential locating in the whole bioleaching process byA. manzaensisat high temperature while only at initial days of bioleaching byL. ferriphilum at a relative low temperature. No reduced product was detected when the redox potential was beyond a high level (e.g., 550 mV (vs SCE)) bioleached byL. ferriphilum. Chalcopyrite bioleaching efficiency was substantially improved bioleached byA. manaensis compared to that byL. ferriphilum, which was mainly attributed to the reduction reaction occurring during bioleaching. The reductive intermediate Cu2S was more amenable to oxidation than chalcopyrite, causing enhanced copper extraction.

  19. Modelling of the temperature-phased batch anaerobic digestion of raw sludge from an urban wastewater treatment plant

    OpenAIRE

    Riau, Víctor; Rubia, M. Ángeles de la; Pérez, Montserrat; Martín, Antonio; Borja Padilla, Rafael

    2012-01-01

    The disposal of excess sludge from wastewater treatment plants is a serious problem that needs to be addressed. Temperature-phased anaerobic digestion (TPAD) which combines thermophilic and mesophilic processes in one, brings together the advantages of both systems. The aim of the present work was to develop a simple kinetic model to describe the TPAD of sewage sludge in batch completely stirred tank reactors (CSTRs) and to determine the kinetic parameters of both thermophilic and mesophilic ...

  20. 直叶涡轮及斜四叶桨搅拌槽层流流场的数值分析%NUMERICAL ANALYSIS OF LAMINAR FLOW FIELD IN A STIRRED TANK WITH A RUSHTON IMPELLER AND PITCH 4-BLADED TURBINES

    Institute of Scientific and Technical Information of China (English)

    田华; 栾德玉

    2011-01-01

    采用计算流体力学(CFD)方法,对直叶圆盘涡轮桨(Rushton)和斜四叶桨(PBT)搅拌槽流场进行研究.利用Laminar层流模型对其在甘油中产生的流场进行数值计算,得到四种形式的搅拌桨以恒定转速200r/min在搅拌槽内转动时所产生的流场结构,对比分析轴向、径向和切向的速度矢量图、速度云图以及速度分布曲线,比较所需的搅拌功率.结果表明:Rushton桨的搅拌效果优于PBT桨,但能量损耗较高;不同倾角的PBT 桨具有类似的流动特性.%Computational fluid dynamics (CFD) method was applied to the study of flow field in stirred tank with a Rushton impeller and pitch 4-bladed turbines. The laminar model was employed to simulate the flow field of stirred tank with glycerin fluid, and the flow structure in a stirred tank with four different impellers rotating at constant speed of 200 r/min was obtained. By comparing the velocity vector plots,velocity contours and velocity distribution curves in the directions of axial, radial and tangent, it was found that the stirring effect of Rushton impeller was better than that of pitch 4-bladed turbines,however,high power consumption was accompanied according to the calculated values of required power. The flow characteristics of the pitch 4-bladed turbines with various blade pitch angles were similar.

  1. 搅拌槽内液-固两相体系的数值研究(Ⅱ)临界搅拌转速的预测%Numerical Study of Solid-Liquid Two-Phase Flow in Stirred Tanks with Rushton Impeller(Ⅱ) Prediction of Critical Impeller Speed

    Institute of Scientific and Technical Information of China (English)

    王峰; 毛在砂; 沈湘黔

    2004-01-01

    The critical impeller speed, NJs, for complete suspension of solid particles in the agitated solid-liquid two-phase system in baffled stirred tanks with a standard Rushton impeller is predicted using the computational procedure proposed in Part I. Three different numerical criteria are tested for determining the critical solid suspension. The predicted NJS is compared with those obtained from several empirical correlations. It is suggested the most reasonable criterion for determining the complete suspension of solid particles is the positive sign of simulated axial velocity of solid phase at the location where the solid particles are most difficult to be suspended.

  2. Anaerobic bioleaching of metals from waste activated sludge

    KAUST Repository

    Meulepas, Roel J W

    2015-05-01

    Heavy metal contamination of anaerobically digested waste activated sludge hampers its reuse as fertilizer or soil conditioner. Conventional methods to leach metals require aeration or the addition of leaching agents. This paper investigates whether metals can be leached from waste activated sludge during the first, acidifying stage of two-stage anaerobic digestion without the supply of leaching agents. These leaching experiments were done with waste activated sludge from the Hoek van Holland municipal wastewater treatment plant (The Netherlands), which contained 342μgg-1 of copper, 487μgg-1 of lead, 793μgg-1 of zinc, 27μgg-1 of nickel and 2.3μgg-1 of cadmium. During the anaerobic acidification of 3gdry weightL-1 waste activated sludge, 80-85% of the copper, 66-69% of the lead, 87% of the zinc, 94-99% of the nickel and 73-83% of the cadmium were leached. The first stage of two-stage anaerobic digestion can thus be optimized as an anaerobic bioleaching process and produce a treated sludge (i.e., digestate) that meets the land-use standards in The Netherlands for copper, zinc, nickel and cadmium, but not for lead.

  3. Continuous stirred tank reactor mechanical modelling and opening virtual simulation system development%连续搅拌反应釜机理建模与开放式虚拟仿真系统开发

    Institute of Scientific and Technical Information of China (English)

    邓晓刚; 于佐军

    2016-01-01

    This paper proposes an opening virtual simulation system design method based on the chemical reactor mechanism model.One common chemical reactor referred to as continuous stirred tank reactor (CSTR) is used as the simulation objective.Firstly,its mathematical models are built using the mechanism analysis technique.Then the process flow diagram is constructed by LabVIEW software and the simulation programs are established using the four-order Runge-Kutta method.With the help of shared variable engine (SVE),the simulation data are deployed to OPC server,which leads to good system open performances.Matlab is used to illustrate the calling procedure of sharing data.This system can simulate the CSTR device characteristics well. Also the openness of simulation helps students to design their own control strategy and provides a platform for the innovative experiment.%以一类常见的化学反应器———连续搅拌反应釜(CSTR)为虚拟仿真对象,提出一种基于化学反应器装置机理模型的开放式虚拟仿真系统开发方法。首先,使用机理分析法建立数学模型;然后,在 LabVIEW 软件中构建工艺流程界面,并基于四阶龙格-库塔法编制虚拟仿真程序;进一步,利用共享变量引擎将虚拟装置数据发布到 OPC Server 中,使虚拟系统具有良好的开放性。以 Matlab 软件为例,说明了共享数据的调用过程。该虚拟仿真系统不但能够较好地模拟 CSTR 的工艺特性,而且其数据的开放性有助于学生自行设计控制方案、自主开展创新性实验研究。

  4. Internal filtration in liquid fuel synthesis stirred tank slurry reactor%液体燃料合成浆态反应器内部过滤的研究

    Institute of Scientific and Technical Information of China (English)

    李建文; 钱炜鑫; 李涛; 应卫勇; 房鼎业

    2012-01-01

    The internal filter made of sintered metal plate as filter media was installed to achieve solid-liquid separation in the stirred tank slurry reactor. The influences of pressure drop, temperature, rotational speed, solid content,filter media pore size, and particle diameter on filtration rate were investigated. The results show that clarified and stable filtrate is gained through internal filtration in the slurry reactor, and the cake thickness reaches dynamic balance and the filtration rate tends to stabilize with the operation carrying out. The filtration rate increases with the increase of pressure drop, temperature , filter media pore diameter, particle diameter and the decrease of rotational speed, solid content. The present investigation is useful to practical production. Filtration model is established through dimensional analysis, and values of parameter are gained by using Michael Marquardt algorithm. The statistical test and the comparison between calculated data and experimental data reveal that the model is reliable.%在液体燃料合成浆态搅拌反应器中设置了以金属烧结板为过滤介质的内过滤器,实现固液分离.研究了压降、温度、搅拌转速、固含率、过滤介质孔径及颗粒粒径对过滤速率的影响.实验结果表明:在浆态反应器中进行内过滤可以得到澄清稳定的滤液;随着操作进行,滤饼厚度达到动态平衡,过滤速率最终趋于稳定;过滤速率随着压降、温度、过滤介质孔径、颗粒粒径的增大及搅拌转速、固含率的减小而增大.应用因次分析法建立过滤模型,通过麦夸特算法对实验数据进行最优拟合得到模型的参数值,统计检验以及模型计算值与实验值的比较表明该模型可靠.

  5. Application of Box-Wilson experimental design method for 2,4-dinitrotoluene treatment in a sequential anaerobic migrating blanket reactor (AMBR)/aerobic completely stirred tank reactor (CSTR) system

    Energy Technology Data Exchange (ETDEWEB)

    Kuscu, Ozlem Selcuk, E-mail: oselcuk@mmf.sdu.edu.tr [Department of Environmental Engineering, Engineering and Architecture Faculty, Sueleyman Demirel University, Cuenuer Campus, 32260 Isparta (Turkey); Sponza, Delia Teresa [Dokuz Eyluel University, Engineering Faculty, Environmental Engineering Department, Buca Kaynaklar campus, Izmir (Turkey)

    2011-03-15

    A sequential aerobic completely stirred tank reactor (CSTR) following the anaerobic migrating blanket reactor (AMBR) was used to treat a synthetic wastewater containing 2,4-dinitrotoluene (2,4-DNT). A Box-Wilson statistical experiment design was used to determine the effects of 2,4-DNT and the hydraulic retention times (HRTs) on 2,4-DNT and COD removal efficiencies in the AMBR reactor. The 2,4-DNT concentrations in the feed (0-280 mg/L) and the HRT (0.5-10 days) were considered as the independent variables while the 2,4-DNT and chemical oxygen demand (COD) removal efficiencies, total and methane gas productions, methane gas percentage, pH, total volatile fatty acid (TVFA) and total volatile fatty acid/bicarbonate alkalinity (TVFA/Bic.Alk.) ratio were considered as the objective functions in the Box-Wilson statistical experiment design in the AMBR. The predicted data for the parameters given above were determined from the response functions by regression analysis of the experimental data and exhibited excellent agreement with the experimental results. The optimum HRT which gave the maximum COD (97.00%) and 2,4-DNT removal (99.90%) efficiencies was between 5 and 10 days at influent 2,4-DNT concentrations 1-280 mg/L in the AMBR. The aerobic CSTR was used for removals of residual COD remaining from the AMBR, and for metabolites of 2,4-DNT. The maximum COD removal efficiency was 99% at an HRT of 1.89 days at a 2,4-DNT concentration of 239 mg/L in the aerobic CSTR. It was found that 280 mg/L 2,4-DNT transformed to 2,4-diaminotoluene (2,4-DAT) via 2-amino-4-nitrotoluene (2-A-4-NT) and 4-amino-2-nitrotoluene (4-A-2-NT) in the AMBR. The maximum 2,4-DAT removal was 82% at an HRT of 8.61 days in the aerobic CSTR. The maximum total COD and 2,4-DNT removal efficiencies were 99.00% and 99.99%, respectively, at an influent 2,4-DNT concentration of 239 mg/L and at 1.89 days of HRT in the sequential AMBR/CSTR.

  6. 固体颗粒对搅拌罐中气液传质的影响%Influence of Solid Particles on Gas-liquid Mass Transfer in a Stirred Tank

    Institute of Scientific and Technical Information of China (English)

    沙作良; 韩冰; Louhi-Kultanen Marjatta

    2015-01-01

    在带有Rushton搅拌桨的搅拌罐中,研究了恒定温度和恒定气体流量条件下不同粒径的固体颗粒和搅拌速率对气液传质速率的影响.结果表明:固体体积分数小于0.08%,时,石英砂(41.1,µm和640,µm)对气液体积传质系数kLa没有影响;而对于碳酸钙颗粒(5.07,µm),当其体积分数大于0.4%,时,kLa 随着固体含量的增加而增大.通过对实验数据的拟合,得到一个含有功率输入、浆液有效黏度、颗粒粒径和固含量的半经验公式,该公式能够很好地表达颗粒对气液传质的影响.%Gas-liquid mass transfer in a stirred tank was studied with a Rushton impeller. Mass transfer rate was investigated using various concentration of different-sized solid particles,as well as different rotation speed at a constant temperature and gas flow rate. When the solid volume fraction was less than 0.08%,no effect of quartz sands(41.1,µm and 640,µm)on the volumetric mass transfer kLa was observed. However,kLa was increased when the solid volume fraction of calcium carbonate particles(5.07,µm)was above 0.4%,. A semi-empirical equation of specific power input,effective viscosity of slurry,particle size,and solid loading was obtained by fitting the experimental data. This equation can successfully describe the effect of particles on gas-liquid mass transfer.

  7. 侧进式搅拌釜内气液两相流的数值模拟%Gas-liquid flow dynamics simulation in side-entering stirred tank

    Institute of Scientific and Technical Information of China (English)

    陈佳; 肖文德

    2013-01-01

    采用计算流体力学(CFD)技术对φ1.5 m×1.2 m侧进式气液搅拌釜内气液两相流场进行数值模拟,检验了3种气液分界面边界条件和两种相间曳力模型.通过UDF程序将上述模型分别与欧拉双流体模型和dispersed k-ε两相湍流模型进行耦合计算,得到搅拌功率准数、总体气含率和气相分布,并与冷模实验结果进行对比,得到能准确预测的CFD模型.研究结果表明,3种气液界面边界条件下采用标准S-N模型计算所得的功率准数和气体分布误差均较大,而Brucato Tsuchiya模型的预测结果更接近实验结果;气液界面边界条件对总体气含率的预测影响较大,采用速度进口或脱气边界和Brucato-Tsuchiya模型耦合计算所得的结果误差比压力出口边界明显要小.%Gas-liquid turbulent flow in a side-entering stirred tank with φ1.5 m× 1.2 m was simulated with computational fluid dynamics (CFD).Three interface boundary conditions (pressure-outlet,velocity-inlet and degassing boundary) and two drag force models (standard S-N model and Brucato-Tsuchiya model) were presented and respectively coupled with the Euler-Euler model and dispersed two-phase k-ε turbulence model by using user define function (UDF).The impeller power number,total gas holdup and gas phase distribution in the tank were calculated and compared with the measurements of the cold model experiments to investigate the effect of boundary condition of gas-liquid interface and drag force model on prediction accuracy.The results indicated that the predicted results calculated with the CFD model coupled with the Brucato-Tsuchiya model and adopting the velocity-inlet or degassing boundary condition,were in agreement with the experimental results,much better than the pressure-outlet boundary condition.

  8. Effects of shock 2,4-dichlorophenol (DCP) and cod loading rates on the removal of 2,4-DCP in a sequential upflow anaerobic sludge blanket/aerobic completely stirred tank reactor system.

    Science.gov (United States)

    Uluköy, A; Sponza, D T

    2008-04-01

    The treatability of 2,4-dwichlorophenol (DCP) was studied in an anaerobic/aerobic sequential reactor system. Laboratory scale upflow anaerobic sludge blanket (UASB) reactor/completely stirred tank reactors (CSTR) were operated at constant 2,4-DCP concentrations, and increasing chemical oxygen demand (COD) loading rates. The effect of shock organic loading rates on 2,4-DCP, COD removal efficiencies and methane gas production were investigated in the UASB reactor. When the organic loading rate was increased from 3.6 g l(-1) d(-1) to 30.16 g l(-1) d(-1), the COD and 2,4-DCP removal efficiencies decreased from 80 to 25% and from 99 to 60% in the UASB reactor. The optimum organic loading rates for maximum 2,4-DCP (E=99-100%) and COD (E=65-85%) removal efficiencies were 25-30 and 8-20 g-COD l(-1) d(-1), respectively. The percentage of methane of the total gas varied between 70 and 80 while the organic loadings were 18 g-COD l(-1) d(-1) and 20.36 g-COD l(-1) d(-1), respectively. During 80 days of operation, 2,4-DCP concentration was found to be below 0.5 and 0.1 mg l(-1) in aerobic reactor effluent resulting in 78 and 100% removal efficiencies. When the hydraulic retention time (HRT) was 18.72 h, the 2,4-DCP removal efficiency was 97% in the aerobic reactor. The optimum COD removal efficiency was 78.83% in anaerobic reactor effluent at an influent COD loading rate of 7.238 g-COD l(-1) d(-1) while 83.6% maximum COD removal efficiency was obtained in the aerobic reactor, resulting in a total COD removal efficiency of 96.83% in the whole system. The 2,4-DCP removal efficiency was 99% in the sequential anaerobic (UASB)/aerobic (CSTR) reactor system at COD loading rates varying between 11.46 and 30.16 g-COD l(-1) d(-1).

  9. Application of Box-Wilson experimental design method for 2,4-dinitrotoluene treatment in a sequential anaerobic migrating blanket reactor (AMBR)/aerobic completely stirred tank reactor (CSTR) system.

    Science.gov (United States)

    Kuşçu, Özlem Selçuk; Sponza, Delia Teresa

    2011-03-15

    A sequential aerobic completely stirred tank reactor (CSTR) following the anaerobic migrating blanket reactor (AMBR) was used to treat a synthetic wastewater containing 2,4-dinitrotoluene (2,4-DNT). A Box-Wilson statistical experiment design was used to determine the effects of 2,4-DNT and the hydraulic retention times (HRTs) on 2,4-DNT and COD removal efficiencies in the AMBR reactor. The 2,4-DNT concentrations in the feed (0-280 mg/L) and the HRT (0.5-10 days) were considered as the independent variables while the 2,4-DNT and chemical oxygen demand (COD) removal efficiencies, total and methane gas productions, methane gas percentage, pH, total volatile fatty acid (TVFA) and total volatile fatty acid/bicarbonate alkalinity (TVFA/Bic.Alk.) ratio were considered as the objective functions in the Box-Wilson statistical experiment design in the AMBR. The predicted data for the parameters given above were determined from the response functions by regression analysis of the experimental data and exhibited excellent agreement with the experimental results. The optimum HRT which gave the maximum COD (97.00%) and 2,4-DNT removal (99.90%) efficiencies was between 5 and 10 days at influent 2,4-DNT concentrations 1-280 mg/L in the AMBR. The aerobic CSTR was used for removals of residual COD remaining from the AMBR, and for metabolites of 2,4-DNT. The maximum COD removal efficiency was 99% at an HRT of 1.89 days at a 2,4-DNT concentration of 239 mg/L in the aerobic CSTR. It was found that 280 mg/L 2,4-DNT transformed to 2,4-diaminotoluene (2,4-DAT) via 2-amino-4-nitrotoluene (2-A-4-NT) and 4-amino-2-nitrotoluene (4-A-2-NT) in the AMBR. The maximum 2,4-DAT removal was 82% at an HRT of 8.61 days in the aerobic CSTR. The maximum total COD and 2,4-DNT removal efficiencies were 99.00% and 99.99%, respectively, at an influent 2,4-DNT concentration of 239 mg/L and at 1.89 days of HRT in the sequential AMBR/CSTR.

  10. 双层半圆管盘式涡轮桨搅拌槽气液分散特性的数值模拟%Numerical simulation of gas-liquid flow in a dual CD-6 impeller stirred tank

    Institute of Scientific and Technical Information of China (English)

    张雪雯; 李志鹏; 高正明

    2011-01-01

    The gas dispersion characteristics in a dual CD-6 impeller stirred tank have been numerically simulated using the population balance model (PBM) combined with the multiple size group (MUSIG) model, which is based on the principle of bubble coalescence and breakup. The effects of varying the gas flow rate and rotation speed on the fluid field, local void fraction distribution and bubble size distribution have been investigated. The results show that the liquid flow adopts a dual loop flow pattern under gas dispersion operating conditions. The local void fraction distributions simulated using the PBM-MUSIG model are in good agreement with the experimental data from the literature. Bubble size decreases as the rotation speed increases, and increases as the gas flow rate increases. The bubble size is smaller in the impeller discharge region, and larger in the near-wall and circulation regions.%采用基于气泡聚并和破碎机理的群体平衡(PBM-MUSIG)模型,对双层半圆管盘式涡轮桨搅拌槽内的气液分散特性进行了数值模拟;考察了不同通气量和操作转速下气液搅拌槽内流体流动,局部气含率和气泡尺寸的分布规律.模拟结果表明:通气工况下搅拌槽内的液相流场具有双循环流动形式;采用PBM-MUSIG模型预测的局部气含率分布与文献实验数据吻合较好;搅拌槽内气泡尺寸随转速增加而减小,随气量增加而增大;桨叶排出流区域内气泡尺寸较小,近壁区和循环区内气泡尺寸较大.

  11. Changes in nutrient profile of soil subjected to bioleaching for removal of heavy metals using Acidithiobacillus thiooxidans

    Energy Technology Data Exchange (ETDEWEB)

    NareshKumar, R. [Centre for Environmental Studies, Anna University, Chennai 600025 (India)], E-mail: nareshkrish@hotmail.com; Nagendran, R. [Centre for Environmental Studies, Anna University, Chennai 600025 (India)

    2008-08-15

    Studies were carried out to assess changes in nitrogen, phosphorus and potassium contents in soil during bioleaching of heavy metals from soil contaminated by tannery effluents. Indigenous sulfur oxidizing bacteria Acidithiobacillus thiooxidans isolated from the contaminated soil were used for bioremediation. Solubilization efficiency of chromium, cadmium, copper and zinc from soil was 88, 93, 92 and 97%, respectively. However, loss of nitrogen, phosphorus and potassium from the soil was 30, 70 and 68%, respectively. These findings indicate that despite its high potential for removal of heavy metals from contaminated soils, bioleaching results in undesirable dissolution/loss of essential plant nutrients. This aspect warrants urgent attention and detailed studies to evaluate the appropriateness of the technique for field application.

  12. Changes in nutrient profile of soil subjected to bioleaching for removal of heavy metals using Acidithiobacillus thiooxidans.

    Science.gov (United States)

    NareshKumar, R; Nagendran, R

    2008-08-15

    Studies were carried out to assess changes in nitrogen, phosphorus and potassium contents in soil during bioleaching of heavy metals from soil contaminated by tannery effluents. Indigenous sulfur oxidizing bacteria Acidithiobacillus thiooxidans isolated from the contaminated soil were used for bioremediation. Solubilization efficiency of chromium, cadmium, copper and zinc from soil was 88, 93, 92 and 97%, respectively. However, loss of nitrogen, phosphorus and potassium from the soil was 30, 70 and 68%, respectively. These findings indicate that despite its high potential for removal of heavy metals from contaminated soils, bioleaching results in undesirable dissolution/loss of essential plant nutrients. This aspect warrants urgent attention and detailed studies to evaluate the appropriateness of the technique for field application.

  13. Copper bioleaching from after-flotation waste using microfungi

    Directory of Open Access Journals (Sweden)

    Ewelina Kasińska-Pilut

    2005-11-01

    Full Text Available The aim of the research presented is an analysis of ways of utilizing microfloral autochthonous organisms from the after-flotation waste of the Gilow stockpile in order to bioleach copper. The alkaline character of the environment disables the use of the traditional processes of acid bioleaching, because of both the economical and environmental aspects. A research of the bioleaching process of the after-flotation waste was conducted using microfungi of the Aspergillus niger species, which dominate in the autochthonous environment. The metabolism of these microfungi, connected with the production of large amounts of organic acids, allowed to conceptualize their usage in the biohydrometalurgy copper processes. After isolating in a pure culture and multiplying the microfungal biomass Aspergillus niger, the experiments began. Weighed samples of the waste were covered with a selective medium and then inoculated with the microfungal biomass, playing the role of the bioleaching agent. After thirty days of incubation, the end product was chemically analyzed, showing effects of the conducted copper bioleaching process (81,23–87,98 %.

  14. Effects of microorganisms on surface properties of chalcopyrite and bioleaching

    Institute of Scientific and Technical Information of China (English)

    CHEN Ming-lian; ZHANG Lin; GU Guo-hua; HU Yue-hua; SU Li-jun

    2008-01-01

    The alteration of surface properties of chalcopyrite after biological conditioning with Acidithiobacillus ferrooxidans and Acidithiobacillus caldus was evaluated by Zeta-potential,adsorption studies,FT-IR spectra and contact angle measurement.The Zeta-potential studies show that the iso-electric point(IEP) of chalcopyrite after bacterial treatment moves towards the IEP of pure cells,indicating the adsorption of cells on chalcopyrite surface.The FT-IR spectra of chalcopyrite treated with bacterial cells show the presence of the cell functional groups signifying cells adsorption.Due to the formation of elemental sulfur and intermediate copper sulphides on chalcopyrite surface,the contact angle and surface hydrophobicity of chalcopyrite increase at the initial bioleaching stage.Chalcopyrite bioleaching by Acidithiobacillus ferrooxidans has higher copper extraction,which agrees with the fact that Acidithiobacillus ferrooxidans adsorbed on chalcopyrite surface is much more than Acidithiobacillus caldus.The results support the direct mechanism of sulfide oxidations in bioleaching chalcopyrite.

  15. Bioleaching of heavy metals from sewage sludge: a review.

    Science.gov (United States)

    Pathak, Ashish; Dastidar, M G; Sreekrishnan, T R

    2009-06-01

    During the treatment of sewage, a huge volume of sludge is generated, which is disposed of on land as soil fertilizer/conditioner due to the presence of nitrogen, phosphorus, potassium and other nutrients. However, the presence of toxic heavy metals and other toxic compounds in the sludge restricts its use as a fertilizer. Over the years, bioleaching has been developed as an environmentally friendly and cost-effective technology for the removal of heavy metals from the sludge. The present paper gives an overview of the various bioleaching studies carried out in different modes of operation. The various important aspects such as pathogen destruction, odor reduction and metal recovery from acidic leachate also have been discussed. Further, a detailed discussion was made on the various technical problems associated with the bioleaching process, which need to be addressed while developing the process on a larger scale.

  16. Effect of Cu2+ ions on bioleaching of marmatite

    Institute of Scientific and Technical Information of China (English)

    CHEN Song; QIN Wen-qing; QIU Guan-zhou

    2008-01-01

    The effect of Cu2+ ions on bioleaching of marmatite was investigated through shake leaching experiments.The bacteria inoculated are a mixed culture of Acidithiobacillus ferrooxidans,Acidithiobacillus thiooxidans and Lepthospirillum ferrooxidans.The results show that zinc is selectively leached,and the addition of appropriate content of Cu2+ ions has positive effect on the bioleaching of marmatite.SEM and EDX analyses of the leaching residue reveal that a product layer composed of iron sulfide,elemental sulfur and jarosite forms on the mineral surface.The biooxidation of elemental sulfur is catalyzed by the Cu2+ ions,which eliminate the barrier to bioleaching of marmatite and keep low pH value.With the addition of 0.5 g/L Cu2+ ions,the maximum zinc extraction rate reaches 73% after 23 d at the temperature of 30 ℃ with the pulp density of 10%,while that of iron is only about 10%.

  17. Arsenic Precipitation in the Bioleaching of Realgar Using Acidithiobacillus ferrooxidans

    Directory of Open Access Journals (Sweden)

    Peng Chen

    2013-01-01

    Full Text Available The current study investigates the characteristics of arsenic precipitation during the bioleaching of realgar. The bioleaching performance of Acidithiobacillus ferrooxidans BY-3 (A. ferrooxidans was investigated through scanning electron microscopy (SEM, transmission electron microscopy (TEM, X-ray diffraction (XRD, and Fourier transform infrared (FT-IR spectrophotometry. SEM and XRD analyses revealed that the arsenic-adapted strain of A. ferrooxidans was more hydrophobic and showed higher attachment efficiency to realgar compared with the wild strain. The arsenic precipitation using A. ferrooxidans resulted in the precipitation of an arsenic-rich compound on the surface of the bacterial cell, as shown in the TEM images. The FT-IR spectra suggested that the −OH and −NH groups were closely involved in the biosorption process. The observations above strongly suggest that the cell surface of A. ferrooxidans plays a role in the induction of arsenic tolerance during the bioleaching of realgar.

  18. EFFECT OF INFLUENT COD CONCENTRATION ON PERFORMANCE OF BIOHYDROGEN PRODUCTION IN CONTINOUS STIRRED TANK REACTOR%进水COD浓度变化对连续流搅拌槽式发酵制氢系统的影响

    Institute of Scientific and Technical Information of China (English)

    韩伟; 陈红; 王占青; 李永峰; 杨传平

    2012-01-01

    利用糖蜜废水作为发酵底物,以连续流搅拌槽式反应器(CSTR)作为反应装置,探讨进水COD浓度变化对厌氧发酵产氢效能的影响.结果表明:在水力停留时间(HRT)为6h,温度为36℃时,CSTR反应器进水COD浓度在2~8g/L范围内变化,即有机负荷(OLR)=8~32kg/(m3 ·d),系统产氢效率和生物量(以挥发性悬浮固体VSS计)随进水浓度的提高而增加,并在进水COD浓度为6g/L时,得到最大产气量和产氢量分别为23.49L/d和8.19L/d.在液相末端产物中,乙醇和乙酸为主要代谢产物,占液相产物总量的82%,为乙醇型发酵.然而,当进水COD浓度升高到8g/L后,生物量和产氢量呈下降趋势,这表明产氢污泥的形成在高浓度底物下可能受到抑制.系统中的产酸发酵类型由乙醇型发酵变为混合酸发酵.发酵气体中H2含量并未随进水浓度的变化而出现明显差异,这反映出CSTR反应器是一个相对稳定的制氢系统.%The continuous stirred tank reactor (CSTR) for bio-hydrogen production was operated under the organic loading rates (OLR) of 8-32kg COD/( m3·d) (COD: Chemical Oxygen Demand) with molasses as the substrate. Increasing substrate concentration (2.0-6.0g/L) gave better biomass content and hydrogen production, signifying that the average cellular activity for H2 production may be enhanced as the substrate concentration increased. The overall maximal biogas and hydrogen production yield were 23.49L/d and 8.19L/d, respectively, both of them occurred at 6g/L. The major soluble products from hydrogen fermentation were ethanol and acetic acid, accounting for 59% and 23% of total liquid fermentation products, respectively. Thus, the dominant H2 producers in the mixed culture belonged to acidogenic bacteria that underwent ethanol-type fermentation. However, the biomass content and hydrogen production yield tended to decrease as the substrate concentration increased to 8g/L, suggesting that granular sludge formation and

  19. Research on Change Process of Nitrosation Granular Sludge in Continuous Stirred-Tank Reactor%CSTR 中亚硝化颗粒污泥的变化过程研究

    Institute of Scientific and Technical Information of China (English)

    阴方芳; 刘文如; 王建芳; 吴鹏; 沈耀良

    2014-01-01

    在连续全混反应器(CSTR)中接种 SBR 培养成熟的亚硝化颗粒污泥,考察反应器构型对亚硝化颗粒污泥生长和运行的影响特性.结果表明,反应器构型和进水模式变化初期部分颗粒污泥解体,污泥平均沉速下降;但随着反应器的进一步运行, CSTR 中实现了亚硝化絮体污泥的快速颗粒化过程;整个研究过程中,虽颗粒粒径分布存较大变化,如粒径>2.5 mm 颗粒的减少和粒径《0.3 mm 颗粒的增加,但颗粒态污泥始终是 CSTR 中占优势的污泥形态.另外,研究表明反应器构型和进水模式的改变对出水中亚硝酸盐累积率(保持在85%左右)无显著影响,并且新生的小粒径颗粒污泥比大粒径颗粒具有更高的比反应活性,此 CSTR 中污泥的平均活性亦高于接种污泥平均活性.%In order to investigate the effect of different types of reactors on the nitrosation granular sludge, a continuous stirred-tank reactor (CSTR) was studied, using mature nitrosation granular sludge cultivated in sequencing batch reactor (SBR) as seed sludge. Results indicated that the change of reactor type and influent mode could induce part of granules to lose stability with gradual decrease in sludge settling ability during the initial period of operation. However, the flocs in CSTR achieved fast granulation in the following reactor operation. In spite of the changes of particle size distribution, e. g. the decreasing number of granules with diameter larger than 2. 5 mm and the increasing number of granules with diameter smaller than 0. 3 mm, granular sludge held the absolute predominance of sludge morphology in CSTR during the entire experimental period. Moreover, results showed that the change of reactor type and influent mode didn't affect the nitrite accumulation rate which was still kept at about 85% in effluent. Additionally, the average activity of the sludge in CSTR was stronger than that of the seed sludge, because

  20. Study of characteristics of gas holdup in stirred tank under three turbulence models%三种湍流模型下搅拌釜内气含率特性的模拟

    Institute of Scientific and Technical Information of China (English)

    丁程兵; 陈迁乔; 钟秦

    2013-01-01

    采用计算流体力学(CFD)方法,应用Euler-Euler双流体模型,桨叶采用多重参考系法(MFR),与考虑气泡聚并与破碎对气泡尺寸影响的群体平衡模型(PBM)相结合,比较了标准k-ε、Realizable k-ε和RNG k-ε3种湍流模型对双层涡轮搅拌釜内气-液两相液相流场、局部气含率及气泡尺寸分布的影响。结果表明:3种湍流模型预测的液相流场流型相似,总体气含率预测值相差不大,均与实验值吻合较好。对于局部气含率,标准k-ε和RNG k-ε模型在桨叶区的预测值偏大,在接近自由液面处三者预测值均偏低,Realizable k-ε模型预测结果与实验值符合最好;对于气泡尺寸,3种湍流模型预测结果均与实验值较吻合,在靠近自由液面处预测值均偏小,气泡尺寸分布与湍流长度分布相吻合。%This paper investigated the simulation of liquid velocity, local gas holdup and bubble size in a stirred tank with dual turbine impellers using computational fluid dynamics(CFD). The results from three different turbulence models (Standard k-ε,RNG k-ε,Realizable k-ε) were compared. The Euler-Euler multiphase flow model and multiple frames of reference(MFR) method were used in the simulations. A population balance model(PBM) was implemented in order to account for the combined effect of bubble break-up and coalescence in the tank. The results showed that the flow patterns of liquid phase and the total gas holdups predicted by the three models had no significant difference, and the total gas holdups agreed well with the experimental data. The standard k-ε and RNG k-ε models over predicted the local gas holdup values at the impeller regions, and in the upper part of the vessel near the liquid-free surface where the local gas holdups predicted all were lower than the measurements. The realizable k-ε model gave the best result compared with the experimental data. The simulated results and

  1. Column bioleaching copper and its kinetics of waste printed circuit boards (WPCBs) by Acidithiobacillus ferrooxidans.

    Science.gov (United States)

    Chen, Shu; Yang, Yuankun; Liu, Congqiang; Dong, Faqin; Liu, Bijun

    2015-12-01

    Application of bioleaching process for metal recovery from electronic waste has received an increasing attention in recent years. In this work, a column bioleaching of copper from waste printed circuit boards (WPCBs) by Acidithiobacillus ferrooxidans has been investigated. After column bioleaching for 28d, the copper recovery reached at 94.8% from the starting materials contained 24.8% copper. Additionally, the concentration of Fe(3+) concentration varied significantly during bioleaching, which inevitably will influence the Cu oxidation, thus bioleaching process. Thus the variation in Fe(3+) concentration should be taken into consideration in the conventional kinetic models of bioleaching process. Experimental results show that the rate of copper dissolution is controlled by external diffusion rather than internal one because of the iron hydrolysis and formation of jarosite precipitates at the surface of the material. The kinetics of column bioleaching WPCBs remains unchanged because the size and morphology of precipitates are unaffected by maintaining the pH of solution at 2.25 level. In bioleaching process, the formation of jarosite precipitate can be prevented by adding dilute sulfuric acid and maintaining an acidic condition of the leaching medium. In such way, the Fe(2)(+)-Fe(3+) cycle process can kept going and create a favorable condition for Cu bioleaching. Our experimental results show that column Cu bioleaching from WPCBs by A. ferrooxidans is promising.

  2. Anaerobic bioleaching of metals from waste activated sludge

    Energy Technology Data Exchange (ETDEWEB)

    Meulepas, Roel J.W., E-mail: roel.meulepas@wetsus.nl [UNESCO-IHE, Westvest 7, 2611 AX Delft (Netherlands); Gonzalez-Gil, Graciela [UNESCO-IHE, Westvest 7, 2611 AX Delft (Netherlands); King Abdullah University of Science and Technology, Water Desalination and Reuse Center, Thuwal 13955-69000 (Saudi Arabia); Teshager, Fitfety Melese; Witharana, Ayoma [UNESCO-IHE, Westvest 7, 2611 AX Delft (Netherlands); Saikaly, Pascal E. [King Abdullah University of Science and Technology, Water Desalination and Reuse Center, Thuwal 13955-69000 (Saudi Arabia); Lens, Piet N.L. [UNESCO-IHE, Westvest 7, 2611 AX Delft (Netherlands)

    2015-05-01

    Heavy metal contamination of anaerobically digested waste activated sludge hampers its reuse as fertilizer or soil conditioner. Conventional methods to leach metals require aeration or the addition of leaching agents. This paper investigates whether metals can be leached from waste activated sludge during the first, acidifying stage of two-stage anaerobic digestion without the supply of leaching agents. These leaching experiments were done with waste activated sludge from the Hoek van Holland municipal wastewater treatment plant (The Netherlands), which contained 342 μg g{sup −1} of copper, 487 μg g{sup −1} of lead, 793 μg g{sup −1} of zinc, 27 μg g{sup −1} of nickel and 2.3 μg g{sup −1} of cadmium. During the anaerobic acidification of 3 g{sub dry} {sub weight} L{sup −1} waste activated sludge, 80–85% of the copper, 66–69% of the lead, 87% of the zinc, 94–99% of the nickel and 73–83% of the cadmium were leached. The first stage of two-stage anaerobic digestion can thus be optimized as an anaerobic bioleaching process and produce a treated sludge (i.e., digestate) that meets the land-use standards in The Netherlands for copper, zinc, nickel and cadmium, but not for lead. - Highlights: • Heavy metals were leached during anaerobic acidification of waste activated sludge. • The process does not require the addition of chelating or oxidizing agents. • The metal leaching efficiencies (66 to 99%) were comparable to chemical leaching. • The produced leachate may be used for metal recovery and biogas production. • The produced digested sludge may be used as soil conditioner.

  3. Experiences and Future Challenges of Bioleaching Research in South Korea

    Directory of Open Access Journals (Sweden)

    Danilo Borja

    2016-12-01

    Full Text Available This article addresses the state of the art of bioleaching research published in South Korean Journals. Our research team reviewed the available articles registered in the Korean Citation Index (KCI, Korean Journal Database addressing the relevant aspects of bioleaching. We systematically categorized the target metal sources as follows: mine tailings, electronic waste, mineral ores and metal concentrates, spent catalysts, contaminated soil, and other materials. Molecular studies were also addressed in this review. The classification provided in the present manuscript details information about microbial species, parameters of operation (e.g., temperature, particle size, pH, and process length, and target metals to compare recoveries among the bioleaching processes. The findings show an increasing interest in the technology from research institutes and mineral processing-related companies over the last decade. The current research trends demonstrate that investigations are mainly focused on determining the optimum parameters of operations for different techniques and minor applications at the industrial scale, which opens the opportunity for greater technological developments. An overview of bioleaching of each metal substrate and opportunities for future research development are also included.

  4. Bioleaching of rare earth elements from monazite sand.

    Science.gov (United States)

    Brisson, Vanessa L; Zhuang, Wei-Qin; Alvarez-Cohen, Lisa

    2016-02-01

    Three fungal strains were found to be capable of bioleaching rare earth elements from monazite, a rare earth phosphate mineral, utilizing the monazite as a phosphate source and releasing rare earth cations into solution. These organisms include one known phosphate solubilizing fungus, Aspergillus niger ATCC 1015, as well as two newly isolated fungi: an Aspergillus terreus strain ML3-1 and a Paecilomyces spp. strain WE3-F. Although monazite also contains the radioactive element Thorium, bioleaching by these fungi preferentially solubilized rare earth elements over Thorium, leaving the Thorium in the solid residual. Adjustments in growth media composition improved bioleaching performance measured as rare earth release. Cell-free spent medium generated during growth of A. terreus strain ML3-1 and Paecilomyces spp. strain WE3-F in the presence of monazite leached rare earths to concentrations 1.7-3.8 times those of HCl solutions of comparable pH, indicating that compounds exogenously released by these organisms contribute substantially to leaching. Organic acids released by the organisms included acetic, citric, gluconic, itaconic, oxalic, and succinic acids. Abiotic leaching with laboratory prepared solutions of these acids was not as effective as bioleaching or leaching with cell-free spent medium at releasing rare earths from monazite, indicating that compounds other than the identified organic acids contribute to leaching performance.

  5. 用数值模拟方法分析混合和导流筒对搅拌槽中沉淀硫酸钡的影响%Computational Fluid Dynamics Approach to the Effect of Mixing and Draft Tube on the Precipitation of Barium Sulfate in a Continuous Stirred Tank

    Institute of Scientific and Technical Information of China (English)

    王正; 毛在砂; 杨超; 沈湘黔

    2006-01-01

    The effect of mixing on the precipitation of barium sulfate in a continuous stirred tank is simulated numerically with different feeding location, feed concentration, impeller speed and residence time through solving the standard momentum and mass transport equations in combination with the moment equations for crystal population balance. The numerical method was validated with the literature data. The simulation results including the distribution of the local supersaturation ratio distribution in the precipitator, mean crystal size and coefficient of variation under different operating conditions compared well with experimental data in the literature. The effect of the presence of a draft tube on precipitation were also investigated, and it is suggested that the installation of a draft tube increased the mean crystal size, in general agreement with experimental work in the literature.

  6. Impact of solvent extraction organics on adsorption and bioleaching of A. ferrooxidans and L. ferriphilum

    Science.gov (United States)

    Hualong, Yu; Xiaorong, Liu

    2017-04-01

    Copper solvent extraction entrained and dissoluted organics (SX organics) in the raffinate during SX operation can contaminated chalcopyrite ores and influence bioleaching efficiency by raffinate recycling. The adsorption and bioleaching of A. ferrooxidans and L. ferriphilum with contaminated ores were investigated. The results showed that, A. ferrooxidans and L. ferriphilum cells could adsorb quickly on minerals, the adsorption rate on contaminated ores were 83% and 60%, respectively, larger than on uncontaminated ores. However, in the bioleaching by the two kinds of acid bacterias, contaminated ores presented a lower bioleaching efficiency.

  7. Elective culture of bacteria used in bioleaching on pyrrhotite

    Institute of Scientific and Technical Information of China (English)

    邱冠周; 覃文庆; 蓝卓越; 黎维中

    2003-01-01

    Elective culture of bacteria on pyrrhotite was researched, and the selected bacteria were tested on bi-oleaching of marmatite and zinc sulfide ore. The results show that the microorganism cultured on pyrrhotite with va-rious S/Fe ratios is a mixed culture of thiobacillus ferrooxidans and thiobacillus thiooxidans, of which the integral ac-tivity and the oxidation capability of Fe2+ and S are enhanced. With the high Fe and low S content of pyrrhotite, the oxida-tion capacity of ferrous ion is improved; on the contrary, the oxidation capacity of sulfur is advanced. The bioleaching ca-pacity of bacteria cultured on marmatite is better than that of the bacteria cultivated by conventional methods.

  8. Macroscopic mass and energy balance of a pilot plant anaerobic bioreactor operated under thermophilic conditions.

    Science.gov (United States)

    Espinosa-Solares, Teodoro; Bombardiere, John; Chatfield, Mark; Domaschko, Max; Easter, Michael; Stafford, David A; Castillo-Angeles, Saul; Castellanos-Hernandez, Nehemias

    2006-01-01

    Intensive poultry production generates over 100,000 t of litter annually in West Virginia and 9 x 10(6) t nationwide. Current available technological alternatives based on thermophilic anaerobic digestion for residuals treatment are diverse. A modification of the typical continuous stirred tank reactor is a promising process being relatively stable and owing to its capability to manage considerable amounts of residuals at low operational cost. A 40-m3 pilot plant digester was used for performance evaluation considering energy input and methane production. Results suggest some changes to the pilot plant configuration are necessary to reduce power consumption although maximizing biodigester performance.

  9. STUDY ON BIOLEACHING OF PRIMARY CHALCOPYRITE ORE WITH THERMOACIDOPHLIC ARCHAE

    Institute of Scientific and Technical Information of China (English)

    P. Zou; W.B. Zhang; T. Lei; J.K. Wang

    2006-01-01

    A high temperature-tolerating thermoacidophilic archae (TA) was isolated from water samples collected from a hot sulfur-containing spring in the Yunnan Province, China, and was used in bioleaching experiments of a low-grade chalcopyrite ore. The TA grow at temperatures ranging from 40 to 80℃, with 65℃ being the optimum temperature, and at pH values of 1.5 to 4.0, with an optimum pH value of 2.0. The bioleaching experiments of the chalcopyrite ore were conducted in both laboratory batch bioreactors and leaching columns. The results obtained from the bioreactor experiments showed that the TA bioleaching rate of copper reached 97% for a 12-day leaching period, while the bioleaching rate was 32.43% for thiobacillus ferrooxidans (Tf) leaching for the same leaching time. In the case of column leaching, tests of a two-phase leaching (196 days), that is,a two-month (56 days) Tf leaching in the first phase, followed by a 140-day TA leaching in the second phase were performed. The average leaching rate of copper achieved for the 140-day TA leaching was 195mg/(L· d), while for the control experiments, it was as low as 78mg/(L· d) for the Tf leaching, indicating that the TA possesses a more powerful oxidizing ability to the chalcopyrite than Tf. Therefore, it is suggested that the two-phase leaching process be applied to for the heap leaching operations, whereas, the TA can be used in the second phase when the temperature inside the heap has increased, and the primary copper sulfide minerals have already been partially oxidized with Tf beforehand in the first phase.

  10. The potential of amino acids in alkaliphilic bioleaching

    Energy Technology Data Exchange (ETDEWEB)

    Barthen, Robert; Karimzadeh, Lotfallah; Gruendig, Marion; Franke, Karsten; Lippmann-Pipke, Johanna [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Reactive Transport; Heim, J. [Technische Univ. Bergakademie Freiberg (Germany)

    2017-06-01

    Bioleaching has become a major production process for copper contributing currently to around 15 % of the world wide copper production. However, non-sulfidic and/or complex ores are still not efficiently minable by conventional methods. In this study, we investigated the effect of copper complexing molecules such as amino acids on Cu{sup 2+} and S{sup 2-} solubilization from covellite.

  11. Mechanism of bioleaching of coal fly ash by Thiobacillus thiooxidans

    Energy Technology Data Exchange (ETDEWEB)

    Seidel, A.; Zimmels, Y.; Armon, R. [Technion Israel Institute of Technology, Haifa (Israel). Faculty of Civil Engineering

    2001-06-15

    Bioleaching of aluminum and iron from coal fly ash (CFA) by Thiobacillus thiooxidans (T thiooxidans) bacteria is considered. The interactions between bacteria, metabolic products, CFA particles, and leaching products were studied. It is demonstrated that bacterial growth and the amount of metals leached from the CFA are coupled through biological and chemical interactions, which involve the various components in this system. Bioleaching experiments were performed batch wise by suspending up to 10% (w/v) CFA in T thiooxidans growth medium containing cell inoculum for a typical 3 week period of time. The results show that under the same conditions, similar leaching levels are obtained by sulfuric acid and bioleaching of CFA, and the contribution of other metabolites is insignificant. CFA inhibits the growth rate through two major effects. The first is due to the alkaline components released by the CFA that cause a rise in the pH, and a corresponding delay in growth. The second is attributed to the random attachment of the bacteria to both the sulfur particles (the energy source) and the barren CFA particles, resulting in a so-called 'dilution effect' of the sulfur particles, and an inhibition of the initial growth rate. However, after an adaptation period of the bacteria the subsequent growth rate, the maximal cell concentration and minimal pH were similar to those obtained in the control experiment, irrespective of CFA content.

  12. Bioleaching of chalcopyrite by pure and mixed culture

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yan-sheng; QIN Wen-qing; WANG Jun; ZHEN Shi-jie; YANG Cong-ren; ZHANG Jian-wen; NAI Shao-shi; QIU Guan-zhou

    2008-01-01

    The bioleaching of chalcopyrite in shake flasks was investigated by using pure Acidithiobacillus ferrooxidans and mixed culture isolated from the acid mine drainage in Yushui and Dabaoshan Copper Mine in China,marked as YS and DB,respectively.The mixed culture consisted mainly of Acidithiobacillus ferrooxidans,Acidithiobacillus thiooxidans,and Leptospirillum spp.(Leptospirillum ferriphilum and Leptospirillum ferrooxians).The results show that the mixed culture is more efficient than the pure Acidithiobacillus ferrooxidans because of the presence of the sulfur-oxidizing cultures that positively increase the dissolution rate and the recovery of copper from chalcopyrite.The pH value decreases with the decrease of chalcopyrite leaching rate,because of the formation of jarosite as a passivation layer on the mineral surface during bioleaching.In the bioleaching using the mixed culture,low pH is got from the sulfur oxidizing inhibiting,the formation of jarosite.The copper extraction reaches 46.27% in mixed culture and 30.37% in pure Acidithiobacillus ferrooxidans after leaching for 75 d.

  13. Does bioleaching represent a biotechnological strategy for remediation of contaminated sediments?

    Energy Technology Data Exchange (ETDEWEB)

    Fonti, Viviana, E-mail: v.fonti@univpm.it; Dell' Anno, Antonio; Beolchini, Francesca

    2016-09-01

    Bioleaching is a consolidated biotechnology in the mining industry and in bio-hydrometallurgy, where microorganisms mediate the solubilisation of metals and semi-metals from mineral ores and concentrates. Bioleaching also has the potential for ex-situ/on-site remediation of aquatic sediments that are contaminated with metals, which represent a key environmental issue of global concern. By eliminating or reducing (semi-)metal contamination of aquatic sediments, bioleaching may represent an environmentally friendly and low-cost strategy for management of contaminated dredged sediments. Nevertheless, the efficiency of bioleaching in this context is greatly influenced by several abiotic and biotic factors. These factors need to be carefully taken into account before selecting bioleaching as a suitable remediation strategy. Here we review the application of bioleaching for sediment bioremediation, and provide a critical view of the main factors that affect its performance. We also discuss future research needs to improve bioleaching strategies for contaminated aquatic sediments, in view of large-scale applications. - Highlights: • Bioleaching may represent a sustainable strategy for contaminated dredged sediments • The performance is greatly influenced by several abiotic and biotic factors • Geochemical characteristics and metal partitioning have a key role • Sulphide minerals in the sediment are a favorable element • Microorganisms other than Fe/S oxidisers may open new perspectives.

  14. Enhanced bioleaching efficiency of metals from E-wastes driven by biochar

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shuhua; Zheng, Yue; Yan, Weifu; Chen, Lixiang [CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021 (China); University of Chinese Academy of Sciences, Beijing, 100049 (China); Dummi Mahadevan, Gurumurthy [CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021 (China); Zhao, Feng, E-mail: fzhao@iue.ac.cn [CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021 (China)

    2016-12-15

    Electronic wastes (E-wastes) contain a huge amount of valuable metals that are worth recovering. Bioleaching has attracted widespread attention as an environment-friendly and low-cost technology for the recycling of E-wastes. To avoid the disadvantages of being time-consuming or having a relatively low efficiency, biochar with redox activity was used to enhance bioleaching efficiency of metals from a basic E-waste (i.e., printed circuit boards in this study). The role of biochar was examined through three basic processes: Carbon-mediated, Sulfur-mediated and Iron-mediated bioleaching pathways. Although no obvious enhancement of bioleaching performance was observed in the C-mediated and S-mediated systems, Fe-mediated bioleaching was significantly promoted by the participation of biochar, and its leaching time was decreased by one-third compared with that of a biochar-free system. By mapping the dynamic concentration of Fe(II) and Cu(II), biochar was proved to facilitate the redox action between Fe(II) to Fe(III), which resulted in effective leaching of Cu. Two dominant functional species consisting of Alicyclobacillus spp. and Sulfobacillus spp. may cooperate in the Fe-mediated bioleaching system, and the ratio of these two species was regulated by biochar for enhancing the efficiency of bioleaching. Hence, this work provides a method to improve bioleaching efficiency with low-cost solid redox media.

  15. Fractionation behavior of heavy metals in soil during bioleaching with Acidithiobacillus thiooxidans.

    Science.gov (United States)

    Naresh Kumar, R; Nagendran, R

    2009-09-30

    The effects of bioleaching on the fractionation of soil heavy metals were investigated in this study. Bioleaching of heavy metals from contaminated soil was carried out in shake flask experiments. Acidophilic sulfur oxidizing bacteria Acidithiobacillus thiooxidans isolated from soil was used for bioleaching. Bioleaching resulted in removal of heavy metals at higher levels. Variations in the binding forms of heavy metals before, during and after bioleaching were evaluated. It was noticed that bioleaching affected the binding forms of all the heavy metals present in the soil. The major contaminant chromium bound mainly to the fractions of soil which are not very reactive (organic and residual fractions) also showed good removal efficiency. Bioleaching influenced the fractionation of metals in soil after treatment and most of the remnant heavy metals were bound either to residual fraction or to other not easily mobile fractions of soil. The results of this study indicated that the bioleaching process can be useful for efficient removal of heavy metals from soil. Further, the soil with remnant metals can be disposed off safely.

  16. Bioleaching of rare earth and radioactive elements from red mud using Penicillium tricolor RM-10.

    Science.gov (United States)

    Qu, Yang; Lian, Bin

    2013-05-01

    The aim of this work is to investigate biological leaching of rare earth elements (REEs) and radioactive elements from red mud, and to evaluate the radioactivity of the bioleached red mud used for construction materials. A filamentous, acid-producing fungi named RM-10, identified as Penicillium tricolor, is isolated from red mud. In our bioleaching experiments by using RM-10, a total concentration of 2% (w/v) red mud under one-step bioleaching process was generally found to give the maximum leaching ratios of the REEs and radioactive elements. However, the highest extraction yields are achieved under two-step bioleaching process at 10% (w/v) pulp density. At pulp densities of 2% and 5% (w/v), red mud processed under both one- and two-step bioleaching can meet the radioactivity regulations in China.

  17. Bioleaching of chalcopyrite and bornite by moderately thermophilic bacteria:an emphasis on their interactions

    Institute of Scientific and Technical Information of China (English)

    Hong-bo Zhao; Jun Wang; Xiao-wen Gan; Wen-qing Qin; Ming-hao Hu; Guan-zhou Qiu

    2015-01-01

    Interactions between chalcopyrite and bornite during bioleaching by moderately thermophilic bacteria were investigated mainly by X-ray diffraction, scanning electron microscopy, and electrochemical measurements performed in conjunction with bioleaching experiments. The results showed that a synergistic effect existed between chalcopyrite and bornite during bioleaching by bothAcidithiobacillus caldus and Leptospirillum ferriphilum and that extremely high copper extraction could be achieved when chalcopyrite and bornite coexisted in a bioleaching system. Bornite dissolved preferentially because of its lower corrosion potential, and its dissolution was accelerated by the gal-vanic current during the initial stage of bioleaching. The galvanic current and optimum redox potential of 390−480 mV vs. Ag/AgCl pro-moted the reduction of chalcopyrite to chalcocite (Cu2S), thus accelerating its dissolution.

  18. Removal of copper from acid wastewater of bioleaching by adsorption onto ramie residue and uptake by Trichoderma viride.

    Science.gov (United States)

    Wang, Buyun; Wang, Kai

    2013-05-01

    A continuous batch bioleaching was built to realize the bioleaching of sewage sludge in large scale. In the treatment, heavy metal in acid wastewater of bioleaching was removed by adsorption onto ramie residue. Then, acid wastewater was reused in next bioleaching batch. In this way, most time and water of bioleaching was saved and leaching efficiency of copper, lead and chromium kept at a high level in continuous batch bioleaching. It was found that residual heavy metal in sewage sludge is highly related to that in acid wastewater after bioleaching. To get a high leaching efficiency, concentration of heavy metal in acid wastewater should be low. Adsorption of copper from acid wastewater onto ramie residue can be described by pseudo first-order kinetics equation and Freundlich isotherm model. Trichoderma viride has the potential to be used for the concentration and recovery of heavy metal adsorbed onto ramie residue. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Continued Multicolumns Bioleaching for Low Grade Uranium Ore at a Certain Uranium Deposit

    Directory of Open Access Journals (Sweden)

    Gongxin Chen

    2016-01-01

    Full Text Available Bioleaching has lots of advantages compared with traditional heap leaching. In industry, bioleaching of uranium is still facing many problems such as site space, high cost of production, and limited industrial facilities. In this paper, a continued column bioleaching system has been established for leaching a certain uranium ore which contains high fluoride. The analysis of chemical composition of ore shows that the grade of uranium is 0.208%, which is lower than that of other deposits. However, the fluoride content (1.8% of weight is greater than that of other deposits. This can be toxic for bacteria growth in bioleaching progress. In our continued multicolumns bioleaching experiment, the uranium recovery (89.5% of 4th column is greater than those of other columns in 120 days, as well as the acid consumption (33.6 g/kg. These results indicate that continued multicolumns bioleaching technology is suitable for leaching this type of ore. The uranium concentration of PLS can be effectively improved, where uranium recovery can be enhanced by the iron exchange system. Furthermore, this continued multicolumns bioleaching system can effectively utilize the remaining acid of PLS, which can reduce the sulfuric acid consumption. The cost of production of uranium can be reduced and this benefits the environment too.

  20. Effects of sulfur forms on heavy metals bioleaching from contaminated sediments.

    Science.gov (United States)

    Fang, D; Zhao, L; Zhou, L X; Shan, H X

    2009-06-01

    The use of recyclable forms of sulfur will exclude the risk of sediment reacidification and reduce the cost of bioleaching process. Three different forms of sulfur (namely sulfur powder, prills and pieces) were used to examine the utilization and recycle of sulfur, used as energy substrate for sulfur-oxidizing bacteria (SOB) in the bioleaching of heavy metal-contaminated sediments. The results showed that despite their relatively smaller surface areas, the efficiency of metal bioleaching with sulfur prills and pieces were comparable to that with sulfur powder. After 13 days of bioleaching, 71-74% of Zn, 58-62% of Cu, and 22-31% of Cr could be leached from the sediments, respectively. During bioleaching, most of the oxidizable and reducible forms of metals were transformed to acid soluble, posing a favorable condition for final metals removal. Sulfur recycling experiments showed that the recovered sulfur prills and pieces were as the same effective in pH reduction as fresh sulfur, revealing the feasibility of eventual reuse of the recycled sulfur in the bioleaching process. Further studies are required to testify the performance of these recyclable forms of sulfur in future large-scale bioleaching reactor.

  1. Behavior of Fe and S in bioleaching of pentlandite

    Institute of Scientific and Technical Information of China (English)

    张广积; 方兆珩

    2002-01-01

    The reaction behavior of Fe and S in bioleaching of pentlandite with Thiobacillus ferrooxidans was investigated. The results of leaching experiments and XRD pattern show that pentlandite can not be oxidized easily by 2.8g/L Fe3+ at 35℃, and H+ was released while Fe3+ precipitates to form jarosite. Bacteria oxidize the sulfide in the mineral to produce element sulfur, meanwhile, H+ in the solution is consumed and this process results in pH value increasing about 0.3 everyday in the solution, and this process is supported by SEM morphology and EDS patterns.

  2. Simultaneous heavy metals removal and municipal sewage sludge dewaterability improvement in bioleaching processes by various inoculums.

    Science.gov (United States)

    Shi, Chaohong; Zhu, Nengwu; Shang, Ru; Kang, Naixin; Wu, Pingxiao

    2015-11-01

    The heavy metals content and dewaterability of municipal sewage sludge (MSS) are important parameters affecting its subsequent disposal and land application. Six kinds of inoculums were prepared to examine the characteristics of heavy metals removal and MSS dewaterability improvement in bioleaching processes. The results showed that Cu, Zn and Cd bioleaching efficiencies (12 days) were 81-91, 87-93 and 81-89%, respectively, which were significantly higher than those of Fe-S control (P heavy metals removal and dewaterability improvement. It also suggested that the synergy of sulfur/ferrous-oxidizing bacteria (SFOB) enriched from AMD and the cooperation of exogenous and indigenous SFOB significantly promoted bioleaching efficiencies.

  3. Bioleaching of low grade nickel sulfide mineral in column reactor

    Institute of Scientific and Technical Information of China (English)

    ZHEN Shi-jie; QIN Wen-qing; YAN Zhong-qiang; ZHANG Yan-sheng; WANG Jun; REN Liu-yi

    2008-01-01

    Jinchuan low grade nickel (0.4%-0.6% Ni,mass fraction) sulfide mineral ore contains a remarkably high content of magnesia (30%-35% MgO,mass fraction) present in the main gangue minerals.Bioleaching was performed to investigate the feasibility to process the mineral due to its relative simplicity,eco-friendly operation and low capital cost requirements.The mixed mesophiles were enriched from acid mine drainage samples collected from several acid mines in China.Considering that the magnesia is easily extracted by acid solution and the excessive Mg2+ will exceed the tolerance of the mixed mesophiles,three effective means were used to reduce the disadvantage of magnesia during the bioleaching operation.They were adaptation of the mixed mesophiles to improve the tolerance; pre-leaching to remove most leachable magnesia and periodic bleeds of a portion of the pregnant leaching solution to control the level of Mg2+ based on the tolerance of the mixed mesophiles.An extraction of nickel (90.3%) and cobalt (88.6%) was successfully achieved within a 300 d leaching process from the Jinchuan low grade nickel sulfide mineral ore using a column reactor at ambient temperature.

  4. A Novel Approach to Bioleach Soluble Phosphorus from Rock Phosphate

    Institute of Scientific and Technical Information of China (English)

    池汝安; 肖春桥; 黄晓慧; 王存文; 吴元欣

    2007-01-01

    A novel approach to bioleach soluble phosphorus from rock phosphate, involving the bio-oxidation of pyrite by adaptated Acidithiobacillus ferrooxidans (At. f) and the product of sulfuric acid to dissolve rock phosphate, has been proposed in this paper. The soluble phosphorus could be leached more effectively in the presence of pyrite by At. f than that leached directly by sulfuric acid. The optimal technological parameters are presented. The highest phosphorus leaching rate is 9.00% when the culture substrate is the mixture of FeSO4·7H2O and pyrite, the phosphorus leaching rate is 8.00% when the initial pH and culture time are 2.5 and 5 d, respectively. The optimal rock phosphate particle size is 0.05 mm for the leaching of phosphorus. The bigger the grains of pyrite, the lower the phosphorus leaching rate. The bacterium At. f should be appropriately adaptated, which makes it easier to bioleach soluble phosphorus from rock phosphate.

  5. Hydrodynamic study to the bioreactor at the Granollers wastewater plant; Estudio hidrodinamico del reactor biologia de la EDAR Granollers

    Energy Technology Data Exchange (ETDEWEB)

    Olivet Santana, D.; Valls Puig, J.; Gordillo Bolasell, M. A.; Sanchez Ferrer, A.; Freixo Rey, A.

    2002-07-01

    One of the most important parameters affecting the operation of bioreactors used in the wastewater treatment is their hydrodynamic behaviour. Usually, bioreactors are designed according to ideal flow models, concretely stirred tank and plug flow models. However, actual bioreactors show a different behaviour from that predicted from ideal modelling. This fact is due to the presence of multiphase systems (e. g. biomass, liquid phase, air, etc.) and the yield obtained can significantly differ from theoretical design values. In the present work, residence-time distribution (RTD) is used to study a plug-flow bioreactor, which is currently working at the plant placed in Granollers (Barcelona). (Author) 5 refs.

  6. Bioleaching of metals from electronic scrap by moderately thermophilic acidophilic bacteria

    NARCIS (Netherlands)

    Ilyas, Sadia; Anwar, Munir A.; Niazi, Shahida B.; Ghauri, M. Afzal

    2007-01-01

    The present work was aimed at studying the bioleachability of metals from electronic scrap by the selected moderately thermophilic strains of acidophilic chemolithotrophic and acidophilic heterotrophic bacteria. These included Sulfobacillus thermosulfidooxidans and an unidentified acidophilic hetero

  7. Effects of bioleaching on the mechanical and chemical properties of waste rocks

    Science.gov (United States)

    Yin, Sheng-Hua; Wu, Ai-Xiang; Wang, Shao-Yong; Ai, Chun-Ming

    2012-01-01

    Bioleaching processes cause dramatic changes in the mechanical and chemical properties of waste rocks, and play an important role in metal recovery and dump stability. This study focused on the characteristics of waste rocks subjected to bioleaching. A series of experiments were conducted to investigate the evolution of rock properties during the bioleaching process. Mechanical behaviors of the leached waste rocks, such as failure patterns, normal stress, shear strength, and cohesion were determined through mechanical tests. The results of SEM imaging show considerable differences in the surface morphology of leached rocks located at different parts of the dump. The mineralogical content of the leached rocks reflects the extent of dissolution and precipitation during bioleaching. The dump porosity and rock size change under the effect of dissolution, precipitation, and clay transportation. The particle size of the leached rocks decreased due to the loss of rock integrity and the conversion of dry precipitation into fine particles.

  8. Development of bioleaching: proteomics and genomics approach in metals extraction process

    Directory of Open Access Journals (Sweden)

    M. Azizur Rahman

    2016-08-01

    Full Text Available Microbes are key components of the structure and function of bioleaching process. Increasing consciousness of the role of microbes has led to a quick growth of descriptive and investigational studies of their abundance and activities. However, the detail information of complex functional molecules contain in promising microbes which are very important for understanding microbial processes in bioleaching, are lacking. Therefore, molecular functions of microbes in the bioleaching process are very essential to understand about the microbial activities, especially in the process of the extraction of metals in mineral industries. In this review, the current state of proteomics and genomics of bioleaching in metals extraction processes and the major developments of these analytical methods at industrial scales are highlighted.

  9. Effect of two kinds of amino-acids on bioleaching metal sulfide

    Institute of Scientific and Technical Information of China (English)

    胡岳华; 贺治国; 胡维新; 彭宏; 钟慧

    2004-01-01

    By adding suitable amount of amino acid L-cysteine to acidic solution in contact with sphalerite or pyrite,the activity of Thiobacillus Ferrooxidans is largely enhanced. But, at comparable higher concentration of L-cysteine, a deleterious effect on bacterial activity was found, which can be due to the toxic effect of this amino acid at higher concentrations to microbes. The addition of L-methionine would be great inhibition to the bioleaching no matter how much it was applied, which indicates that L-methionine is harmful for bioleaching. The quite different effect on bioleaching between L-cysteine and L-methionine lies in that L-cysteine has a SH group which is useful in helping metal sulfide bioleaching by Thiobacillus ferrooxidans.

  10. A New Heterotrophic Strain for Bioleaching of Low Grade Complex Copper Ore

    Directory of Open Access Journals (Sweden)

    Kaijian Hu

    2016-02-01

    Full Text Available A new heterotrophic strain, named Providencia sp. JAT-1, was isolated and used in bioleaching of low-grade complex copper ore. The strain uses sodium citrate as a carbon source and urea as a nitrogen source to produce ammonia. The optimal growth condition of the strain is 30 C, initial pH 8, sodium citrate 10 g/L and urea 20 g/L, under which the cell density and ammonia concentration in the medium reached a maximum of 4.83 × 108 cells/mL and 14 g/L, respectively. Ammonia produced by the strain is used as the main lixiviant in bioleaching. Bioleaching results revealed that higher strain growth led to a higher copper recovery, while higher pulp density will cause a greater inhibitory effect on strain growth and ammonia production. The copper extraction reached the highest value of 54.5% at the pulp density of 1%. Malachite, chrysocolla and chalcocite are easy to leach out in this bioleaching system while chalcopyrite is difficult. Results of comparative leaching experiments show that bioleaching using JAT-1 is superior to ammonia leaching at the same condition. The metabolites produced by the strain other than ammonia are also involved in bioleaching.

  11. Alkaline bioleaching of municipal solid waste incineration fly ash by autochthonous extremophiles.

    Science.gov (United States)

    Ramanathan, Thulasya; Ting, Yen-Peng

    2016-10-01

    The increasing demand for energy and the generation of solid waste have caused an alarming rise in fly ash production globally. Since heavy metals continue to be in demand for the production of materials, resource recovery from the recycling of these wastes has the potential to delay the depletion of natural ores. The use of microorganisms for the leaching of metals, in a process called bioleaching, is an eco-friendly and economical way to treat the metal-laden wastes. Bioleaching of fly ash is challenging due largely to the alkaline nature and toxic levels of heavy metals which are detrimental to microbial growth and bioleaching activity. The present work reports the isolation of indigenous bacteria from a local fly ash landfill site and their bioleaching performance. 38 autochthonous strains of bacteria were isolated from eight samples collected and plated on five different media. 18 of the isolates showed bioleaching potential, with significant alkaline pH or fly ash tolerance. Genetic characterization of the strains revealed a dominance of Firmicutes, with Alkalibacterium sp. TRTYP6 showing highest fly ash tolerance of up to 20% w/v fly ash, and growth over a pH range 8-12.5. The organism selectively recovered about 52% Cu from the waste. To the best of our knowledge, this is the first time a study on bioleaching with extreme alkaliphiles is reported.

  12. A Comparative Study of the Microbial Communities Between the Mineral Surface and the Bioleaching Solution Using the Microarray Method

    Institute of Scientific and Technical Information of China (English)

    GAO Jian; KANG Jian

    2011-01-01

    In order to explore the bioleaching mechanism and improve the bioleaching efficiency,the microbial community in the bioleaching solution was compared with that on the surface of minerals based on the microarray analysis.Meanwhile,the elements composition in the bioleaching solution was analyzed using the ICP-AES method.Results showed that there was a high concentration of S and Cu in the leaching solution which up to 2380 mg/L and 1378 mg/L,respectively,after continuously bioleaching of copper-ore concentrate for 30 days by a mixed culture associated with 12 species of bioleaching microorganisms.Based on the data of microarray,the total of cell number in the surface of minerals was far higher than that in the bioleaching solution.Furthermore,the dominant communities on the surface of minerals,such as Acidithiobacillus ferrooxidans,Acidithiobacillus thiooxidans and Acidithiobacillus caldus,were similar to that in the bioleaching solution.However,the relative level of some bacteria,such as Sulfobacillus acidophilus and Sulfobacillus thermosulfidooxidans,showed great discrepancy with lower presence in the bioleaching solution with respect to the mineral surface.

  13. Quantification of acetone emission from pine plants

    Institute of Scientific and Technical Information of China (English)

    SHAO; Min; (邵敏); Jürgen; Wildt

    2002-01-01

    Acetone emission from pine plants (pinus sylvestris) is measured by continuously stirred tank reactor. Under a constant light intensity, acetone emission rates increase exponentially with leaf temperature. When leaf temperature is kept constant, acetone emission increases with light intensity. And acetone emission in darkness is also detected. Acetone emitted from pine is quickly labeled by 13C when the plants are exposed to air with 630 mg/m3 13CO2. However, no more than 20% of acetone is 13C labeled. Acetone emission from pine may be due to both leaf temperature- controlled process and light intensity-controlled process. Based on these understandings, an algorithm is used to describe the short term acetone emission rates from pine.

  14. Interfacial interaction of bio-leaching of pyrite mineral

    Institute of Scientific and Technical Information of China (English)

    GU Guo-hua; WANG nui; SUO Jun; QIU Guan-zhou; HAO Ye

    2008-01-01

    Electrokinetic and contact angle measurements were used to discuss the interracial interaction on bio-leaching of pyrite mineral. Surface energy parameters of pyrite mineral and thiobaeillus ferrooxidans were Gbtained by calculating according to formula of Young's equation and contact angle measurements. The results show that surface energy of thiobacillus ferrooxidans is much higher than that of pyrite mineral, and the reaction of pyrite mineral with thiobacillus ferrooxidans causes the reduction of the pyrite surface energy. The interfacial interaction energies between pyrite mineral and thiobacillus ferrooxidans were also obtained based onpolar interfacial interaction theory and electrokinetic and contact angle measurements. The thermodynamics approach only considering Lifshitz-van der Waals and Lewis acid-base interaction fails to explain the adhesion behavior of the bacteria, but theextended Derjaguin-Landan-Verwey-Overbeek theory concerning Lifshitz-van der Waals and Lewis acid-base and the electrostatic can exactly predict interracial interaction.

  15. pH对发酵系统的产甲烷活性抑制及产氢强化%Enhancement of the fermentative hydrogen production in a continuous-flow stirred tank reactor by decreasing pH to inhibit methanogenesis

    Institute of Scientific and Technical Information of China (English)

    李建政; 苏晓煜; 昌盛; 张立国; 于泽

    2012-01-01

    To develop a feasible method for inhibiting methanogenesis while enhancing fermentative hydrogen production in anaerobic organic wastewater fermentation process, a continuous - flow stirred tank reactor (CSTR) a methane production feature was introduced and used as the base-line condition. The CSTR was op- erated at (35 ± 1 )℃ with an influent COD 7 000 mg/L and a hydraulic retention time (HRT) 8 h throughout the performance test. When the pH in the CSTR decreased from 6. 5 - 7.2 to 6. 0 - 6. 5, the methane yield decreased remarkably and could not be inspected in the biogas at last, while the percentage of hydrogen in bio- gas kept at a low level less than 3 %. When the CSTR operated with a lower pH 4. 0 -5.0, the acidogenesis was further enhanced with a total organic intermediate of 2 052 rag/L, dominated by ethanol and acetic acid, indicating a typical ethanol-type fermentation established in the CSTR. During the ethanol-type fermentation process, a biogas yield of 26 L/d was obtained with a hydrogen percentage about 45%. The specific hydrogen producing rate of the anaerobic activated sludge reached at 1.67 L/( g · d) averagely. Key words: organic wastewater; methanogenesis; fermentative hydrogen production; pH adjustment; continu- ous-flow stirred tank reactor (CSTR)%为抑制厌氧发酵系统的产甲烷活性,强化其发酵产氢性能,采用逐级降低pH的调控方法,探讨连续流搅拌槽式反应器(CSTR)从具有显著甲烷发酵特征的厌氧发酵系统向发酵产氢系统转变的运行特征.在进水COD7000mg/L、水力停留时间(HRT)8h条件下,发酵体系在pH由6.5~7.2降低到6.0~6.5时,虽然发酵气中的甲烷体积分数逐渐减少乃至消失,但氢气体积分数一直在3%以下;当pH下降到4.0~5.0时,系统中的产酸发酵作用得到了进一步强化,挥发性发酵产物总量平均为2052mg/L,呈现为典型的乙醇型发酵

  16. 运用粒子图像测速仪研究双层桨搅拌林下风槽内流全流动%Investigation of Fluid Flow in a Dual Rushton Impeller Stirred Tank Using Particle Image Velocimetry

    Institute of Scientific and Technical Information of China (English)

    潘春妹; 闵健; 刘心洪; 高正明

    2008-01-01

    The flow fields in a dual Rushton impeller stirred tank with diameter of 0.48 m(T)were measured by using Particle Image Velocimetry(PIV).Three different size impellers were used in the experiments wlth diameters of D=33T.0.40T and 0.507,respectively.The multi-block and 360°ensemble-averaged approaches were used to measure the radial and axial angle-resolved velocity distributions.Three typical flow patterns,named,merging flow,parallel flow and diverging flow,were obtained by changing the clearance of the bottom impeller above the tank base(C1)and the spacing between the two impellers(C2).The results show that while C1 is equal to D,the parallel flow occurs as C2≥0.40T,C2≥0.38T and C2≥0.32T and the merging flow occurs as C2≤0.38T,C2≤o.36T and C2≤0.27T for the impellers with diameter of D=0.33T,0.40T and 0.50T,respectively.When C2 is equal to D,the diverging flow occurs in the value of C1≤0.15T for all three impellers.Thc flow numbers of these impellers were calculated for the parallel flow.Trailing vortices generated by the lower impeller for the diverging flow were shown bv the 10°angle-resolved velocity measurements.The peak Value of turbulence kinetic energy(k/V2tip=0.12-0.15 or above)appears along the center of the impeller discharging stream.

  17. Tuning of a Proportional-Integral-Derivative Controller using Multi-Objective Non Dominated Sorting Particle Swarm Optimization Applied to pH Control in Continuous Stirred Tank Reactor

    Directory of Open Access Journals (Sweden)

    C. A. Kumar

    2011-01-01

    Full Text Available Problem statement: Most of the control engineering problems are characterized by several, contradicting, conflicting objectives, which have to be satisfied simultaneously. Two widely used methods for finding the optimal solution to such problems are aggregating to a single criterion and using Pareto-optimal solutions. Approach: Non-Dominated Sorting Particle Swarm Optimization algorithm (NSPSO based approach is used in the design of multiobjective PID controller to find the constant proportional-integral-derivative gains for a chemical neutralization plant. The plant considered in this study is highly non-linear and with varying time delay, provides a challenging test bed for nonlinear control problems. Results: Experimental results confirm that a multi-objective, Paretobased GA search gives a better performance than a single objective GA. Conclusion: Finally, the results for single objective and multiobjective optimization using NSPSO for the neutralization plant are compared. Gain scheduled PID controllers are designed from Pareto front obtained with NSPSO which exhibit good disturbance rejection capability.

  18. Comparison and evaluation of immobilization methods for preparing bacterial probes using acidophilic bioleaching bacteria Acidithiobacillus thiooxidans for AFM studies.

    Science.gov (United States)

    Diao, Mengxue; Taran, Elena; Mahler, Stephen M; Nguyen, Anh V

    2014-07-01

    We evaluated different strategies for constructing bacterial probes for atomic force microscopy studies of bioleaching Acidithiobacillus thiooxidans interacting with pyrite mineral surfaces. Of three available techniques, the bacterial colloidal probe technique is the most reliable and provides a versatile platform for quantifying true interactive forces between bioleaching microorganisms and mineral surfaces.

  19. The effects of metabolites from the indigenous Acidithiobacillus thiooxidans and temperature on the bioleaching of cadmium from soil.

    Science.gov (United States)

    Liu, Hsuan-Liang; Chiu, Chi-Wei; Cheng, Yang-Chu

    2003-09-20

    The effect of metabolites from the indigenous Acidithiobacillus thiooxidans and temperature on the bioleaching of cadmium from soil was investigated in the present study. Bioleaching was found to be more effective than chemical leaching of cadmium. The metabolite, mainly sulfuric acid, which was shown to be growth-associated in the exponential phase, plays a major role in bioleaching. The maximum amount of cadmium leached was obtained after 8 days of precultivation when cells were directly involved in the leaching process. It indicates that cells in the exponential growth phase exhibit higher activity toward bioleaching. In contrast, the maximum amount of cadmium leached and the maximum initial rate for bioleaching were reached after 16 days of precultivation when only metabolites were involved in the bioleaching process. It implies that higher sulfuric acid concentration results in higher leaching efficiency. In addition, higher temperature leads to higher leaching efficiency. The optimal operation condition for bioleaching was determined to be a two-stage process: The first stage involves the precultivation of the indigenous A. thiooxidans at 30 degrees C for 8 days followed by 20 minutes of centrifugation to discard cells. The second stage involves the bioleaching with the subsequent supernatant at 50 degrees C.

  20. Influence of initial pH on bioleaching of heavy metals from contaminated soil employing indigenous Acidithiobacillus thiooxidans.

    Science.gov (United States)

    Kumar, R Naresh; Nagendran, R

    2007-01-01

    Bioleaching of heavy metals from contaminated soil was carried out employing indigenous sulfur oxidizing bacterium Acidithiobacillus thiooxidans. Experiments were carried out to assess the influence of initial pH of the system on bioleaching of chromium, zinc, copper, lead and cadmium from metal contaminated soil. pH at the end of four weeks of bioleaching at different initial pH of 3-7 was between 0.9 and 1.3, ORP between 567 and 617mV and sulfate production was in the range of 6090-8418mgl(-1). Chromium, zinc, copper, lead and cadmium solubilization ranged from "59% to 98%" at different initial pH. A. thiooxidans was not affected by the increasing pH of the bioleaching system towards neutral and it was able to utilize elemental sulfur. The results of the present study are encouraging to develop the bioleaching process for decontamination of heavy metal contaminated soil.

  1. Bioleaching of copper from old flotation tailings samples (Copper Mine Bor, Serbia

    Directory of Open Access Journals (Sweden)

    Stanković Srđan

    2015-01-01

    Full Text Available Bioleaching of samples taken from depths of 10, 15, and 20 meters from old flotation tailings of the Copper Mine Bor was conducted in shaken flasks using extremely acidic water of Lake Robuleas lixiviant. Yield of copper after five weeks of the bioleaching experiment was 68.34±1.21% for 15 m sample, 72.57±0.57% for 20 m sample and 97.78±5.50% for 10 m sample. The obtained results were compared to the results of acid leaching of the same samples and it was concluded that bioleaching was generally more efficient for the treatment of samples taken from depths of 10 m and 20 m. The content of pyrite in the 20 m sample, which contained the highest amount of this mineral, was reduced after bioleaching. Benefits of this approach are: recovery of substantial amounts of copper, reducing the environmental impact of flotation tailings and the application of abundant and free water from the Robule acidic lake as lixiviant. Results of the experiment showed that bioleaching can be more efficient than acid leaching for copper extraction from flotation tailings with higher sulfide contents. [Projekat Ministarstva nauke Republike Srbije, br. 176016 i br. 173048

  2. Bioleaching of valuable metals from spent lithium-ion mobile phone batteries using Aspergillus niger

    Science.gov (United States)

    Horeh, N. Bahaloo; Mousavi, S. M.; Shojaosadati, S. A.

    2016-07-01

    In this paper, a bio-hydrometallurgical route based on fungal activity of Aspergillus niger was evaluated for the detoxification and recovery of Cu, Li, Mn, Al, Co and Ni metals from spent lithium-ion phone mobile batteries under various conditions (one-step, two-step and spent medium bioleaching). The maximum recovery efficiency of 100% for Cu, 95% for Li, 70% for Mn, 65% for Al, 45% for Co, and 38% for Ni was obtained at a pulp density of 1% in spent medium bioleaching. The HPLC results indicated that citric acid in comparison with other detected organic acids (gluconic, oxalic and malic acid) had an important role in the effectiveness of bioleaching using A. niger. The results of FTIR, XRD and FE-SEM analysis of battery powder before and after bioleaching process confirmed that the fungal activities were quite effective. In addition, bioleaching achieved higher removal efficiency for heavy metals than the chemical leaching. This research demonstrated the great potential of bio-hydrometallurgical route to recover heavy metals from spent lithium-ion mobile phone batteries.

  3. Bioleaching of metals from steel slag by Acidithiobacillus thiooxidans culture supernatant.

    Science.gov (United States)

    Hocheng, Hong; Su, Cheer; Jadhav, Umesh U

    2014-12-01

    The generation of 300–500 kg of slag per ton of the steel produced is a formidable amount of solid waste available for treatment. They usually contain considerable quantities of valuable metals. In this sense, they may become either important secondary resource if processed in eco-friendly manner for secured supply of contained metals or potential pollutants, if not treated properly. It is possible to recover metals from steel slag by applying bioleaching process. Electric arc furnace (EAF) slag sample was used for bioleaching of metals. In the present study, before bioleaching experiment water washing of an EAF slag was carried out. This reduced slag pH from 11.2 to 8.3. Culture supernatants of Acidithiobacillus thiooxidans (At. thiooxidans), Acidithiobacillus ferrooxidans (At. ferrooxidans), and Aspergillus niger (A. niger) were used for metal solubilization. At. thiooxidans culture supernatant containing 0.016 M sulfuric acid was found most effective for bioleaching of metals from an EAF slag. Maximum metal extraction was found for Mg (28%), while it was least for Mo (0.1%) in six days. Repeated bioleaching cycles increased metal recovery from 28% to 75%, from 14% to 60% and from 11% to 27%, for Mg, Zn and Cu respectively.

  4. Metals bioleaching from electronic waste by Chromobacterium violaceum and Pseudomonads sp.

    Science.gov (United States)

    Pradhan, Jatindra Kumar; Kumar, Sudhir

    2012-11-01

    These days, electronic waste needs to be taken into consideration due to its materials content, but due to the heterogeneity of the metals present, reprocessing of electronic waste is quite limited. The bioleaching of metals from electronic waste was investigated by using cyanogenic bacterial strains (Chromobacterium violaceum, Pseudomonas aeruginosa and Pseudomonas fluorescens). A two-step bioleaching process was followed under cyanide-forming conditions for maximum metals mobilization. Both single and mixed cultures of cyanogenic bacteria were able to mobilize metals from electronic waste with different efficiencies. In all the flasks in which high metal mobilizations were observed, the consequent biomass productions were also high. Pseudomonas aeruginosa was applied in the bioleaching process for the first time and this achieved its bioleaching ability of mobilization of metals from electronic waste. Chromobacterium violaceum as a single culture and a mixture of C. violaceum and P. aeruginosa exhibited maximum metal mobilization. Chromobacterium violaceum was capable of leaching more than 79, 69, 46, 9 and 7% of Cu, Au, Zn, Fe and Ag, respectively at an electronic waste concentration of 1% w/v. Moreover, the mixture of C. violaceum and P. aeruginosa exhibited metals leaching of more than 83, 73, 49, 13 and 8% of total Cu, Au, Zn, Fe, and Ag, respectively. Precious metals were mobilized through bioleaching which might be considered as an industrial application for recycling of electronic waste in the near future.

  5. Effect of sediment size on bioleaching of heavy metals from contaminated sediments of Izmir Inner Bay

    Institute of Scientific and Technical Information of China (English)

    Duyusen E.Guven; Gorkem Akinci

    2013-01-01

    The effect of sediment size on metals bioleaching from bay sediments was investigated by using fine (< 45 μm),medium (45-300 μm),and coarse (300-2000μm) size fractions of a sediment sample contaminated with Cr,Cu,Pb,and Zn.Chemical speciation of the metals in bulk and size fractions of sediment were studied before and after bioleaching.Microbial activity was provided with mixed cultures of Acidithiobacillus thiooxidans and Acidithiobacillusferrooxidans.The bioleaching process was carried out in flask experiments for 48 days,by using 5% (W/V) of solid concentration in suspension.Bioleaching was found to be efficient for the removal of selected heavy metals from every size fraction of sediments,where the experiments with the smaller particles resulted in the highest solubilization ratios.At the end of the experimental period,Cr,Cu,Pb and Zn were solubilized to the ratios of 68%,88%,72%,and 91% from the fine sediment,respectively.Higher removal efficiencies can be explained by the larger surface area provided by the smaller particles.The changes in the chemical forms of metals were determined and most of the metal releases were observed from the reducible and organic fractions independent from grain size.Higher concentrations were monitored in the residual fraction after bioleaching period,suggesting they are trapped in this fraction,and cannot be solubilized under natural conditions.

  6. Thermodynamic properties of bioleaching liquid mixtures with and without mesophilic bacteria at different temperatures

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this work, low-grade copper sulfide mine has been treated by the bioleaching process using native cultures of Acidithiobacillus ferrooxidans. The bioleaching experiments were carried out in shake flasks at pH 2.0, 180 r·min-1 and 30°C for mesophilic bacteria. The conductivity of copper bioleaching liquid was determined by the electric conductivity method at temperatures ranging from 298 K to 313 K. The ionic activity coefficients were estimated using Debye-Hücker and Osager-Falkenlagen equations. Meanwhile, the effects of temperature and concentration on the mean ionic activity co efficients were discussed. The relative partial molar free energies, enthalpies and entropies of copper leaching solution at above experimental temperatures were calculated The behaviors of change of relative partial molar quantities were dis cussed on the basis of electrolytic solution theory. Simultaneously, the thermodynamic characters of bioleaching solution with and without mesophilic bacteria were compared. The existence of mesophilic bacteria changed the Fe3+/Fe2+ ratio, which resulted in the difference of ionic interaction. The experimental data show that the determination of the thermody namic properties during the bioleaching processes should be important

  7. Bioleaching of nickel from spent petroleum catalyst using Acidithiobacillus thiooxidans DSM- 11478.

    Science.gov (United States)

    Sharma, Mohita; Bisht, Varsha; Singh, Bina; Jain, Pratiksha; Mandal, Ajoy K; Lal, Banwari; Sarma, Priyangshu M

    2015-06-01

    The present work deals with optimization of culture conditions and process parameters for bioleaching of spent petroleum catalyst collected from a petroleum refinery. The efficacy of Ni bioleaching from spent petroleum catalyst was determined using pure culture of Acidithiobacillus thiooxidans DSM- 11478. The culture conditions of pH, temperature and headspace volume to media volume ratio were optimized. EDX analysis was done to confirm the presence of Ni in the spent catalyst after roasting it to decoke its surface. The optimum temperature for A. thiooxidans DSM-11478 growth was found to be 32 degrees C. The enhanced recovery of nickel at very low pH was attributed to the higher acidic strength of sulfuric acid produced in the culture medium by the bacterium. During the bioleaching process, 89% of the Ni present in the catalyst waste could be successfully recovered in optimized conditions. This environment friendly bioleaching process proved efficient than the chemical method. Taking leads from the lab scale results, bioleaching in larger volumes (1, 5 and 10 L) was also performed to provide guidelines for taking up this technology for in situ industrial waste management.

  8. Bioleaching combined brine leaching of heavy metals from lead-zinc mine tailings: Transformations during the leaching process.

    Science.gov (United States)

    Ye, Maoyou; Yan, Pingfang; Sun, Shuiyu; Han, Dajian; Xiao, Xiao; Zheng, Li; Huang, Shaosong; Chen, Yun; Zhuang, Shengwei

    2017-02-01

    During the process of bioleaching, lead (Pb) recovery is low. This low recovery is caused by a problem with the bioleaching technique. This research investigated the bioleaching combination of bioleaching with brine leaching to remove heavy metals from lead-zinc mine tailings. The impact of different parameters were studied, including the effects of initial pH (1.5-3.0) and solid concentration (5-20%) for bioleaching, and the effects of sodium chloride (NaCl) concentration (10-200 g/L) and temperature (25 and 50 °C) for brine leaching. Complementary characterization experiments (Sequential extraction, X-ray diffractometer (XRD), scanning electronic microscope (SEM)) were also conducted to explore the transformation of tailings during the leaching process. The results showed that bioleaching efficiency was significantly influenced by initial pH and solid concentration. Approximately 85.45% of iron (Fe), 4.12% of Pb, and 97.85% of zinc (Zn) were recovered through bioleaching in optimum conditions. Increasing the brine concentration and temperature promoted lead recovery. Lead was recovered from the bioleaching residues at a rate of 94.70% at 25 °C and at a rate of 99.46% at 50 °C when the NaCl concentration was 150 g/L. The study showed that bioleaching significantly changed the speciation of heavy metals and the formation and surface morphology of tailings. The metals were mainly bound in stable fractions after bioleaching. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. The role of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans in arsenic bioleaching from soil.

    Science.gov (United States)

    Ko, Myoung-Soo; Park, Hyun-Sung; Kim, Kyoung-Woong; Lee, Jong-Un

    2013-12-01

    Bioleaching of As from the soil in an abandoned Ag-Au mine was carried out using Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. A. ferrooxidans is an iron oxidizer and A. thiooxidans is a sulfur oxidizer. These two microbes are acidophilic and chemoautotrophic microbes. Soil samples were collected from the Myoungbong and Songcheon mines. The main contaminant of the soil was As, with an average concentration of 4,624 mg/kg at Myoungbong and 5,590 mg/kg at Songcheon. A. ferrooxidans and A. thiooxidans generated lower pH conditions during their metabolism process. The bioleaching of As from soil has a higher removal efficiency than chemical leaching. A. ferrooxidans could remove 70 % of the As from the Myoungbong and Songcheon soils; however, A. thiooxidans extracted only 40 % of the As from the Myoungbong soil. This study shows that bioleaching is an effective process for As removal from soil.

  10. SEM and AFM images of pyrite surfaces after bioleaching by the indigenous Thiobacillus thiooxidans.

    Science.gov (United States)

    Liu, H-L; Chen, B-Y; Lan, Y-W; Cheng, Y-C

    2003-09-01

    The bioleaching mechanism of pyrite by the indigenous Thiobacillus thiooxidans was examined with the aid of scanning electron microscopy (SEM) and atomic force microscopy (AFM) images of the pyrite surface. The presence of pyrite eliminated the lag phase during growth of this microorganism. This was due to the stimulatory effect on cell growth of the slight amount of Cu2+ that had leached from the pyrite. Zn2+ was found to be much more readily solubilized than Cu2+. The efficiency of bioleaching was four times higher than that of chemical leaching. SEM images provided evidence of direct cell attachment onto the pyrite surface, thereby enhancing the bioleaching rate. Furthermore, extracellular polymeric substances (EPSs) were found on the pyrite surface after 4 days of oxidation. AFM images showed that the pyrite surface area positively correlated with the oxidation rate. A combination of direct and indirect mechanism is probably responsible for the oxidation of pyrite by T. thiooxidans.

  11. Influence Of Used Bacterial Culture On Zinc And Aluminium Bioleaching From Printed Circuit Boards

    Directory of Open Access Journals (Sweden)

    Mrazikova Anna

    2015-06-01

    Full Text Available Bioleaching processes were used to solubilize metals (Cu, Ni, Zn and Al from printed circuit boards (PCBs. In this study, a PCBs-adapted pure culture of Acidithiobacillus ferrooxidans, pure culture of Acidithiobacillus thiooxidans and PCBs-adapted mixed culture of A. ferrooxidans and A. thiooxidans were used for recovery of the metals. The study showed that the mixed bacterial culture has the greatest potential to dissolve metals. The maximum metal bioleaching efficiencies were found to be 100, 92, 89 and 20% of Cu, Ni, Zn and Al, respectively. The mixed culture revealed higher bacterial stability. The main factor responsible for high metal recovery was the ability of the mixed culture to maintain the low pH during the whole process. The pure culture of A. thiooxidans had no significant effect on metal bioleaching from PCBs.

  12. Arsenopyrite and pyrite bioleaching: evidence from XPS, XRD and ICP techniques.

    Science.gov (United States)

    Fantauzzi, Marzia; Licheri, Cristina; Atzei, Davide; Loi, Giovanni; Elsener, Bernhard; Rossi, Giovanni; Rossi, Antonella

    2011-10-01

    In this work, a multi-technical bulk and surface analytical approach was used to investigate the bioleaching of a pyrite and arsenopyrite flotation concentrate with a mixed microflora mainly consisting of Acidithiobacillus ferrooxidans. X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and X-ray-induced Auger electron spectroscopy mineral surfaces investigations, along with inductively coupled plasma-atomic emission spectroscopy and carbon, hydrogen, nitrogen and sulphur determination (CHNS) analyses, were carried out prior and after bioleaching. The flotation concentrate was a mixture of pyrite (FeS(2)) and arsenopyrite (FeAsS); after bioleaching, 95% of the initial content of pyrite and 85% of arsenopyrite were dissolved. The chemical state of the main elements (Fe, As and S) at the surface of the bioreactor feed particles and of the residue after bioleaching was investigated by X-ray photoelectron and X-ray excited Auger electron spectroscopy. After bioleaching, no signals of iron, arsenic and sulphur originating from pyrite and arsenopyrite were detected, confirming a strong oxidation and the dissolution of the particles. On the surfaces of the mineral residue particles, elemental sulphur as reaction intermediate of the leaching process and precipitated secondary phases (Fe-OOH and jarosite), together with adsorbed arsenates, was detected. Evidence of microbial cells adhesion at mineral surfaces was also produced: carbon and nitrogen were revealed by CHNS, and nitrogen was also detected on the bioleached surfaces by XPS. This was attributed to the deposition, on the mineral surfaces, of the remnants of a bio-film consisting of an extra-cellular polymer layer that had favoured the bacterial action.

  13. Acclimation of Methane-fermenting Anaerobic Flocs in a Continuous Flow Stirred Tank Reactor for Treating Beet-sugar Processing Wastewater%制糖废水CSTR甲烷发酵系统的污泥驯化与运行特征

    Institute of Scientific and Technical Information of China (English)

    李建政; 叶菁菁; 王卫娜; 马超; 昌盛

    2008-01-01

    与厌氧颗粒污泥相比,絮状悬浮活性污泥具有传质界面大、速度快的突出优点,但要形成具有完整甲烷发酵过程的微生物生态系统则比较困难.采用连续搅拌槽式反应器(Continuous flow Stirred-Tank Reactor,CSTR),探讨了制糖废水厌氧生物处理系统的絮状污泥驯化与运行特征.研究表明,以有机废水好氧处理工艺的剩余污泥为种泥,在接种量MLVSS为8.52g/L,温度为(35±1)℃,COD浓度为4000mg/L,HRT为18 h,系统pH值保持在6.5~7.5等条件下,CSTR可在84d左右形成具有完整甲烷发酵过程的絮状是浮厌氧活性污泥系统.CSTR甲烷发酵系统对负荷冲击表现出了良好的调节能力,在有机负荷从5.3 kg COD/(m3·d)提高到9.33 kg COD/(m3·d)时,反应系统可在16d内重新达到稳定运行状态,其出水COD可稳定在1100mg/L左右,COD去除率和产气量平均为84%和38L/d,发酵气中的CO2和CH4含量分别为41%和48%.

  14. Toluene emissions from plants

    Science.gov (United States)

    Heiden, A. C.; Kobel, K.; Komenda, M.; Koppmann, R.; Shao, M.; Wildt, J.

    The emission of toluene from different plants was observed in continuously stirred tank reactors and in field measurements. For plants growing without stress, emission rates were low and ranged from the detection limit up to 2·10-16 mol·cm-2·s-1. Under conditions of stress, the emission rates exceeded 10-14 mol·cm-2·s-1. Exposure of sunflower (Helianthus annuus L. cv. Gigantheus) to 13CO2 resulted in 13C-labeling of the emitted toluene on a time scale of hours. Although no biochemical pathway for the production of toluene is known, these results indicate that toluene is synthesized by the plants. The emission rates of toluene from sunflower are dependent on nutrient supply and wounding. Since α-pinene emission rates are also influenced by these factors, toluene and α-pinene emissions show a high correlation. During pathogen attack on Scots pines (Pinus sylvestris L.) significant toluene emissions were observed. In this case emissions of toluene and α-pinene also show a good correlation. Toluene emissions were also found in field experiments with pines using branch enclosures.

  15. One Step Bioleaching of Sulphide Ore with Low Concentration of Arsenic by Aspergiilus niger and Taguchi Orthogonal Array Optimization

    Institute of Scientific and Technical Information of China (English)

    Sadia Ilyas; 池汝安; Jae Chun Leet; Haq Nawaz Bhatti

    2012-01-01

    A study was carried out to examine the possibility for Aspergillus niger strain KBS4 to bioleach metals from sulphide ore with low concentration of arsenic and to optimize the parameters that affect this process by orthogonal array optimization. Fungal sample was collected, purified and sequenced. The bioleaching process was optimized with L25 Taguchi orthogonal experimental array design. Five factors were investigated and 25 batch bioleaching tests were run at five levels for each factor. The parameters were initial pH, particle size, pulp density, initial inoculums and residence time for bioleaching. The experimental results showed that under optimized leaching conditions: pH 5.5, particle size 180 μm, initial inoculums size 3×10 7 spores per ml, pulp density 15% and residence time of 20 days, the bioleach ability of metals were 63% Fe, 68% Zn, 60% As, 79% Cu and 54% Al. The biosorption of metal ions by fungal biomass might occur during the bioleaching process but it did not hinder the removal of metal ions by bioleaching.

  16. Kinetics of propionate conversion in anaerobic continuously stirred tank reactors

    DEFF Research Database (Denmark)

    Bangsø Nielsen, Henrik; Mladenovska, Zuzana; Ahring, Birgitte Kiær

    2008-01-01

    (max), and the half saturation constant, K-m, were initially estimated by applying the integrated Michaelis-Menten equation. A(max) was in the range from 22.8 to 29.1 mu mol gVS(-1) h(-1) while K-m, was in the range from 0.46-0.95 mM. In general, A(max) gave a good reflection of the reactor performances. Secondly...

  17. Robust Nonlinear Control of Continuous Stirred Tank Reactors

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    1IntroductionRobustcontrolofuncertainsystemsisacentralissueincontroltheory.Inthepastfewyearsmuchinteresthasbeendevotedtothede...

  18. Gas-Liquid Mass Transfer Coefficient in Stirred Tank Reactors

    NARCIS (Netherlands)

    Yawalkar, Archis A.; Heesink, Albertus B.M.; Versteeg, Geert F.; Pangarkar, Vishwas G.

    2002-01-01

    Volumetric gas—liquid mass transfer coefficient (kLa) data available in the literature for larger tanks (T = 0.39 m to 2.7 m) have been analyzed on the basis of relative dispersion parameter, N/Ncd. It was observed that at a given superficial gas velocity (VG), kLa values were approximately the same

  19. Gas–Liquid Mass Transfer Coefficient in Stirred Tank Reactors

    NARCIS (Netherlands)

    Yawalkar, Archis A.; Heesink, Albertus B.M.; Versteeg, Geert F.; Pangarkar, Vishwas G.

    2002-01-01

    Volumetric gas–liquid mass transfer coefficient (kLa) data available in the literature for larger tanks (T = 0.39 m to 2.7 m) have been analyzed on the basis of relative dispersion parameter, N/Ncd. It was observed that at a given superficial gas velocity (VG), kLa values were approximately the same

  20. Fractionation study in bioleached metallurgy wastes using six-step sequential extraction.

    Science.gov (United States)

    Krasnodebska-Ostrega, Beata; Pałdyna, Joanna; Kowalska, Joanna; Jedynak, Łukasz; Golimowski, Jerzy

    2009-08-15

    The stored metallurgy wastes contain residues from ore processing operations that are characterized by relatively high concentrations of heavy metals. The bioleaching process makes use of bacteria to recover elements from industrial wastes and to decrease potential risk of environmental contamination. Wastes were treated by solutions containing bacteria. In this work, the optimized six-stage sequential extraction procedure was applied for the fractionation of Ni, Cr, Fe, Mn, Cu and Zn in iron-nickel metallurgy wastes deposited in Southern Poland (Szklary). Fractionation and total concentrations of elements in wastes before and after various bioleaching treatments were studied. Analyses of the extracts were performed by ICP-MS and FAAS. To achieve the most effective bioleaching of Zn, Cr, Ni, Cu, Mn, Fe the usage of both autotrophic and heterotrophic bacteria in sequence, combined with flushing of the residue after bioleaching is required. 80-100% of total metal concentrations were mobilized after the proposed treatment. Wastes treated according to this procedure could be deposited without any risk of environmental contamination and additionally the metals could be recovered for industrial purposes.

  1. Bioleaching of metals from printed wire boards by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans and their mixture.

    Science.gov (United States)

    Wang, Jingwei; Bai, Jianfeng; Xu, Jinqiu; Liang, Bo

    2009-12-30

    Bioleaching processes were used to mobilize metals from printed wire boards (PWBs). The bacteria Acidithiobacillus ferrooxidans (A. ferrooxidans) and Acidithiobacillus thiooxidans (A. thiooxidans) isolated from an acidic mine drainage were grown and acclimated in presence of PWBs and then used as bioleaching bacteria to solubilize metals from PWBs. The experimental results demonstrate that all the percentages of copper, lead, zinc solubilized into the leaching solution from actual PWBs basically increased with decrease of sieve fraction of sample and decrease of PWBs concentration. The concentration of PWBs should be controlled under the range from 7.8 to 19.5 g l(-1). Under 7.8 g l(-1) of the concentration of PWBs, the percentages of copper solubilized are 99.0%, 74.9%, 99.9% at 0.5-1.0mm of sieve fraction at 9 d of leaching time by the pure culture of A. ferrooxidans, the pure culture of A. thiooxidans, and mixed culture of A. ferrooxidans and A. thiooxidans, respectively, while the percentages of copper, lead and zinc solubilized are all more than 88.9% at thiooxidans were able to grow in the presence of PWBs and the pure culture of A. ferrooxidans, and the mixed culture of A. ferrooxidans and A. thiooxidans can not only efficiently bioleach the main metal copper but also bioleach other minor metals such as lead, zinc as well.

  2. Acidithiobacillus thiooxidans secretome containing a newly described lipoprotein Licanantase enhances chalcopyrite bioleaching rate.

    Science.gov (United States)

    Bobadilla Fazzini, Roberto A; Levican, Gloria; Parada, Pilar

    2011-02-01

    The nature of the mineral-bacteria interphase where electron and mass transfer processes occur is a key element of the bioleaching processes of sulfide minerals. This interphase is composed of proteins, metabolites, and other compounds embedded in extracellular polymeric substances mainly consisting of sugars and lipids (Gehrke et al., Appl Environ Microbiol 64(7):2743-2747, 1998). On this respect, despite Acidithiobacilli-a ubiquitous bacterial genera in bioleaching processes (Rawlings, Microb Cell Fact 4(1):13, 2005)-has long been recognized as secreting bacteria (Jones and Starkey, J Bacteriol 82:788-789, 1961; Schaeffer and Umbreit, J Bacteriol 85:492-493, 1963), few studies have been carried out in order to clarify the nature and the role of the secreted protein component: the secretome. This work characterizes for the first time the sulfur (meta)secretome of Acidithiobacillus thiooxidans strain DSM 17318 in pure and mixed cultures with Acidithiobacillus ferrooxidans DSM 16786, identifying the major component of these secreted fractions as a single lipoprotein named here as Licanantase. Bioleaching assays with the addition of Licanantase-enriched concentrated secretome fractions show that this newly found lipoprotein as an active protein additive exerts an increasing effect on chalcopyrite bioleaching rate.

  3. Bioleaching of refractory gold ore (Ⅲ)--Fluid leaching Jinya refractory gold concentrate by Thiobacillus ferrooxidans

    Institute of Scientific and Technical Information of China (English)

    闵小波; 柴立元; 陈为亮; 于霞; 张传福; 邝中

    2002-01-01

    A novel fluidized-bed reactor was designed and installed for bioleaching in a semi-continuous way,by which a process for bioleaching-cyanidation of Jinya refractory gold arsenical concentrate was studied.The arsenic extraction rate reaches 82.5% after 4-day batch biooxidation of the concentrate under the optimized condition of pH 2.0,ferric ion concentration 6.5 g/L and pulp concentration 10%.And leached rate of gold in the following cyanidation is over 90%.The parameters of three series fluidized-bed reactors exhibit stability during the semi-continuous bioleaching of the concentrate.Arsenic in the concentrate can be got rid of 91% after 6-day leaching.Even after 4 days,82% of arsenic extraction rate was still obtained.The recovery rates of gold are 92% and 87.5% respectively in cyaniding the above bioleached residues.The results will provide a base for further commercial production of gold development.

  4. Bioleaching of heavy metals from a contaminated soil using indigenous Penicillium chrysogenum strain F1.

    Science.gov (United States)

    Deng, Xinhui; Chai, Liyuan; Yang, Zhihui; Tang, Chongjian; Tong, Haixia; Yuan, Pingfu

    2012-09-30

    Bioleaching of heavy metals from contaminated soil using Penicillium chrysogenum strain F1 was investigated. Batch experiments were performed to compare leaching efficiencies of heavy metals between one-step and two-step processes and to determine the transformation of heavy metal fractions before and after bioleaching. The results showed that two-step process had higher leaching efficiencies of heavy metals than one-step process. When the mass ratio of soil to culture medium containing P. chrysogenum strain F1 was 5% (w/v), 50%, 35%, 9% and 40% of Cd, Cu, Pb and Zn were removed in one-step process, respectively. The two-step process had higher removals of 63% Cd, 56% Cu, 14% Pb and 54% Zn as compared with one-step process. The results of the sequential extraction showed that the metals remaining in the soil were mainly bonded in stable fractions after bioleaching. The results of TEM and SEM showed that during bioleaching process, although the mycelium of P. chrysogenum was broken into fragments, no damage was obviously observed on the surface of the living cell except for thinner cell wall, smaller vacuoles and concentrated cytoplasm. The result implied that P. chrysogenum strain F1 can be used to remove heavy metals from polluted soil.

  5. Enhancing sewage sludge dewaterability by bioleaching approach with comparison to other physical and chemical conditioning methods

    Institute of Scientific and Technical Information of China (English)

    Fenwu Liu; Jun Zhou; Dianzhan Wang; Lixiang Zhou

    2012-01-01

    The sewage sludge conditioning process is critical to improve the sludge dewaterability prior to mechanical dewatering.Traditionally,sludge is conditioned by physical or chemical approaches,mostly with the addition of inorganic or organic chemicals.Here we report that bioleaching,an efficient and economical microbial method for the removal of sludge-borne heavy metals,also plays a significant role in enhancing sludge dewaterability.The effects of bioleaching and physical or chemical approaches on sludge dewaterability were compared.The conditioning result of bioleaching by Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans on sludge dewatering was investigated and compared with the effects of hydrothermal(121 ℃ for 2 hr),microwave(1050 W for 50 sec),ultrasonic (250 W for 2 min),and chemical conditioning(24% ferric chloride and 68% calcium oxide; dry basis).The results show that the specific resistance to filtration(SRF)or capillary suction time(CST)of sludge is decreased by 93.1% or 74.1%,respectively,after fresh sludge is conditioned by bioleaching,which is similar to chemical conditioning treatment with ferric chloride and calcium oxide but much more effective than other conditioning approaches including hydrothermal,microwave,and ultrasonic conditioning.Furthermore,after sludge dewatering,bioleached sludge filtrate contains the lowest concentrations of chroma(18 times),COD(542 mg/L),total N(TN,300 mg/L),NH4+-N(208 mg/L),and total P(TP,2 mg/L)while the hydrothermal process resulted in the highest concentration of chroma(660 times),COD(18,155 mg/L),TN(472 mg/L),NH4+-N(381 mg/L),and TP(191 mg/L)among these selected conditioning methods.Moreover,unlike chemical conditioning,sludge bioleaching does not result in a significant reduction of organic matter,TN,and TP in the resulting dewatered sludge cake.Therefore,considering sludge dewaterability and the chemical properties of sludge filtrate and resulting dewatered sludge cakes,bioleaching has

  6. Enhancing sewage sludge dewaterability by bioleaching approach with comparison to other physical and chemical conditioning methods.

    Science.gov (United States)

    Liu, Fenwu; Zhou, Jun; Wang, Dianzhan; Zhou, Lixiang

    2012-01-01

    The sewage sludge conditioning process is critical to improve the sludge dewaterability prior to mechanical dewatering. Traditionally, sludge is conditioned by physical or chemical approaches, mostly with the addition of inorganic or organic chemicals. Here we report that bioleaching, an efficient and economical microbial method for the removal of sludge-borne heavy metals, also plays a significant role in enhancing sludge dewaterability. The effects of bioleaching and physical or chemical approaches on sludge dewaterability were compared. The conditioning result of bioleaching by Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans on sludge dewatering was investigated and compared with the effects of hydrothermal (121 degrees C for 2 hr), microwave (1050 W for 50 sec), ultrasonic (250 W for 2 min), and chemical conditioning (24% ferric chloride and 68% calcium oxide; dry basis). The results show that the specific resistance to filtration (SRF) or capillary suction time (CST) of sludge is decreased by 93.1% or 74.1%, respectively, after fresh sludge is conditioned by bioleaching, which is similar to chemical conditioning treatment with ferric chloride and calcium oxide but much more effective than other conditioning approaches including hydrothermal, microwave, and ultrasonic conditioning. Furthermore, after sludge dewatering, bioleached sludge filtrate contains the lowest concentrations of chroma (18 times), COD (542 mg/L), total N (TN, 300 mg/L), NH4(+)-N (208 mg/L), and total P (TP, 2 mg/L) while the hydrothermal process resulted in the highest concentration of chroma (660 times), COD (18,155 mg/L), TN (472 mg/L), NH4(+)-N (381 mg/L), and TP (191 mg/L) among these selected conditioning methods. Moreover, unlike chemical conditioning, sludge bioleaching does not result in a significant reduction of organic matter, TN, and TP in the resulting dewatered sludge cake. Therefore, considering sludge dewaterability and the chemical properties of sludge

  7. Effects of stimulation of copper bioleaching on microbial community in vineyard soil and copper mining waste.

    Science.gov (United States)

    Andreazza, Robson; Okeke, Benedict C; Pieniz, Simone; Bortolon, Leandro; Lambais, Márcio R; Camargo, Flávio A O

    2012-04-01

    Long-term copper application in vineyards and copper mining activities cause heavy metal pollution sites. Such sites need remediation to protect soil and water quality. Bioremediation of contaminated areas through bioleaching can help to remove copper ions from the contaminated soils. Thus, the aim of this work was to evaluate the effects of different treatments for copper bioleaching in two diverse copper-contaminated soils (a 40-year-old vineyard and a copper mining waste) and to evaluate the effect on microbial community by applying denaturing gradient gel electrophoresis (DGGE) of 16S ribosomal DNA amplicons and DNA sequence analysis. Several treatments with HCl, H(2)SO(4), and FeSO(4) were evaluated by stimulation of bioleaching of copper in the soils. Treatments and extractions using FeSO(4) and H(2)SO(4) mixture at 30°C displayed more copper leaching than extractions with deionized water at room temperature. Treatment with H(2)SO(4) supported bioleaching of as much as 120 mg kg(-1) of copper from vineyard soil after 115 days of incubation. DGGE analysis of the treatments revealed that some treatments caused greater diversity of microorganisms in the vineyard soil compared to the copper mining waste. Nucleotide Blast of PCR-amplified fragments of 16S rRNA gene bands from DGGE indicated the presence of Rhodobacter sp., Silicibacter sp., Bacillus sp., Paracoccus sp., Pediococcus sp., a Myxococcales, Clostridium sp., Thiomonas sp., a firmicute, Caulobacter vibrioides, Serratia sp., and an actinomycetales in vineyard soil. Contrarily, Sphingomonas was the predominant genus in copper mining waste in most treatments. Paracoccus sp. and Enterobacter sp. were also identified from DGGE bands of the copper mining waste. Paracoccus species is involved in the copper bioleaching by sulfur oxidation system, liberating the copper bounded in the soils and hence promoting copper bioremediation. Results indicate that stimulation of bioleaching with a combination of FeSO(4

  8. Technological assessment of a mining-waste dump at the Dexing copper mine, China, for possible conversion to an in situ bioleaching operation.

    Science.gov (United States)

    Wu, Aixiang; Yin, Shenghua; Wang, Hongjiang; Qin, Wenqin; Qiu, Guanzhou

    2009-03-01

    In order to extract copper metal from the waste dump of Dexing copper mine and resolve the environmental problems caused by acidic water and heavy metals, a dump bioleaching plant was designed based on a series of experimental investigations. The investigation shown that the low-grade of the dump, refractoriness of chalcopyrite, leakage of pad, small Acidithiobacillus population and low dump permeability are the main factors that contribute to the challenges faced by the plant. Stability of the high and steep slope of the dump is the other hidden danger to which much attention is not paid. To evaluate the potential unstability of the dump, the leaching process, ore surface erosion, particle size, chemical elements and mechanical properties of the waste rock in DCM were investigated through experiment in this paper.

  9. Bioleaching of arsenic from highly contaminated mine tailings using Acidithiobacillus thiooxidans.

    Science.gov (United States)

    Lee, Eunseong; Han, Yosep; Park, Jeonghyun; Hong, Jeongsik; Silva, Rene A; Kim, Seungkon; Kim, Hyunjung

    2015-01-01

    The behavior of arsenic (As) bioleaching from mine tailings containing high amount of As (ca. 34,000 mg/kg) was investigated using Acidithiobacillus thiooxidans to get an insight on the optimal conditions that would be applied to practical heap and/or tank bioleaching tests. Initial pH (1.8-2.2), temperature (25-40 °C), and solid concentration (0.5-4.0%) were employed as experimental parameters. Complementary characterization experiments (e.g., XRD, SEM-EDS, electrophoretic mobility, cell density, and sulfate production) were also carried out to better understand the mechanism of As bioleaching. The results showed that final As leaching efficiency was similar regardless of initial pH. However, greater initial As leaching rate was observed at initial pH 1.8 than other conditions, which could be attributed to greater initial cell attachment to mine tailings. Unlike the trend observed when varying the initial pH, the final As leaching efficiency varied with the changes in temperature and solid concentration. Specifically, As leaching efficiency tended to decrease with increasing temperature due to the decrease in the bacterial growth rate at higher temperature. Meanwhile, As leaching efficiency tended to increase with decreasing solid concentration. The results for jarosite contents in mine tailings residue after bioleaching revealed that much greater amount of the jarosite was formed during the bioleaching reaction at higher solid concentration, suggesting that the coverage of the surface of the mine tailings by jarosite and/or the co-precipitation of the leached As with jarosite could be a dominant factor reducing As leaching efficiency. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Bioleaching of some Rare Earth Elements from Egyptian Monazite using Aspergillus ficuum and Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Wesam Abdel Ghany HASSANIEN

    2013-12-01

    Full Text Available Aspergillus ficuum and Pseudomonas aeruginosa exhibit good potential in generating varieties of organic acids effective for bioleaching some rare earth elements (REEs from Egyptian monazite (purity 97 % and (thorium-uranium concentrate. Batch experiments are performed to compare the bioleaching efficiencies of the one and 2-step bioleaching processes. The highest percentages of bioleached REEs from monazite and (Th-U concentrate directly by A. ficuum are found to be 75.4, 63.8 % at a pulp density 0.6, 1.2 % (w/v, respectively, after 9 days of incubation at 30 °C and 63.5, 52.6 % by P. aeruginosa after 8 days of incubation at 35 °C using a shaking incubator at 175 rpm. It is also found that 14.3 and 1.4 g/l of citric and oxalic acid, respectively, are produced by A. ficuum, while 6.3 g/l of 2-ketogluconic acid is produced by P. aeruginosa. The highest percentages of chemical leaching of REEs from 0.6 % monazite using citric acid 14.3 g/l, oxalic acid 1.4 g/l, citric/oxalic acids 15.7 g/l and 2- ketogluconic acid 6.3 g/l after 24 h are 55.7, 26.0, 58.8 and 45.6 %, respectively. This work addresses the area of beneficiation of the used mineral to solubilize REEs through the biotechnological route in Egypt, where the bioleaching method is more effective than the chemical one using organic acids.doi:10.14456/WJST.2014.85

  11. Influences of Extracellular Polymeric Substances on the Dewaterability of Sewage Sludge during Bioleaching

    Science.gov (United States)

    Zhang, Xueying; Zhou, Lixiang

    2014-01-01

    Extracellular polymeric substances (EPS) play important roles in regulating the dewaterability of sludge. This study sought to elucidate the influence of EPS on the dewaterability of sludge during bioleaching process. Results showed that, in bioleaching system with the co-inoculation of Acidithiobacillus thiooxidans TS6 and Acidithiobacillus ferrooxidans LX5 (A. t+A. f system), the capillary suction time (CST) of sludge reduced from 255.9 s to 25.45 s within 48 h, which was obviously better than the controls. The correlation analysis between sludge CST and sludge EPS revealed that the sludge EPS significantly impacted the dewaterability of sludge. Sludge CST had correlation with protein content in slime and both protein and polysaccharide contents in TB-EPS and Slime+LB+TB layers, and the decrease of protein content in slime and decreases of both protein and polysaccharide contents in TB-EPS and Slime+LB+TB layers improved sludge dewaterability during sludge bioleaching process. Moreover, the low sludge pH (2.92) and the increasing distribution of Fe in the solid phase were another two factors responsible for the improvement of sludge dewaterability during bioleaching. This study suggested that during sludge bioleaching the growth of Acidithiobacillus species resulted in the decrease of sludge pH, the increasing distribution of Fe in the solid phase, and the decrease of EPS content (mainly including protein and/or polysaccharide) in the slime, TB-EPS, and Slime+LB+TB layers, all of which are helpful for sludge dewaterability enhancement. PMID:25050971

  12. Influences of extracellular polymeric substances on the dewaterability of sewage sludge during bioleaching.

    Directory of Open Access Journals (Sweden)

    Jun Zhou

    Full Text Available Extracellular polymeric substances (EPS play important roles in regulating the dewaterability of sludge. This study sought to elucidate the influence of EPS on the dewaterability of sludge during bioleaching process. Results showed that, in bioleaching system with the co-inoculation of Acidithiobacillus thiooxidans TS6 and Acidithiobacillus ferrooxidans LX5 (A. t+A. f system, the capillary suction time (CST of sludge reduced from 255.9 s to 25.45 s within 48 h, which was obviously better than the controls. The correlation analysis between sludge CST and sludge EPS revealed that the sludge EPS significantly impacted the dewaterability of sludge. Sludge CST had correlation with protein content in slime and both protein and polysaccharide contents in TB-EPS and Slime+LB+TB layers, and the decrease of protein content in slime and decreases of both protein and polysaccharide contents in TB-EPS and Slime+LB+TB layers improved sludge dewaterability during sludge bioleaching process. Moreover, the low sludge pH (2.92 and the increasing distribution of Fe in the solid phase were another two factors responsible for the improvement of sludge dewaterability during bioleaching. This study suggested that during sludge bioleaching the growth of Acidithiobacillus species resulted in the decrease of sludge pH, the increasing distribution of Fe in the solid phase, and the decrease of EPS content (mainly including protein and/or polysaccharide in the slime, TB-EPS, and Slime+LB+TB layers, all of which are helpful for sludge dewaterability enhancement.

  13. Bioleaching of gold, copper and nickel from waste cellular phone PCBs and computer goldfinger motherboards by two Aspergillus nigerstrains

    National Research Council Canada - National Science Library

    Madrigal-Arias, Jorge Enrique; Argumedo-Delira, Rosalba; Alarcón, Alejandro; Mendoza-López, Ma. Remedios; García-Barradas, Oscar; Cruz-Sánchez, Jesús Samuel; Ferrera-Cerrato, Ronald; Jiménez-Fernández, Maribel

    2015-01-01

    ...), this research evaluated the bioleaching efficiency of gold (Au), copper (Cu) and nickel (Ni) by two strains of Aspergillus niger in the presence of gold-plated finger integrated circuits found in computer motherboards (GFICMs...

  14. Insights to the effects of free cells on community structure of attached cells and chalcopyrite bioleaching during different stages.

    Science.gov (United States)

    Feng, Shoushuai; Yang, Hailin; Wang, Wu

    2016-01-01

    The effects of free cells on community structure of attached cells and chalcopyrite bioleaching by Acidithiobacillus sp. during different stages were investigated. The attached cells of Acidithiobacillus thiooxidans owned the community advantage from 14thd to the end of bioprocess in the normal system. The community structure of attached cells was greatly influenced in the free cells-deficient systems. Compared to A. thiooxidans, the attached cells community of Acidithiobacillus ferrooxidans had a higher dependence on its free cells. Meanwhile, the analysis of key biochemical parameters revealed that the effects of free cells on chalcopyrite bioleaching in different stages were diverse, ranging from 32.8% to 64.3%. The bioleaching contribution of free cells of A. ferrooxidans in the stationary stage (8-14thd) was higher than those of A. thiooxidans, while the situation was gradually reversed in the jarosite passivation inhibited stage (26-40thd). These results may be useful in guiding chalcopyrite bioleaching.

  15. Community dynamics of attached and free cells and the effects of attached cells on chalcopyrite bioleaching by Acidithiobacillus sp.

    Science.gov (United States)

    Yang, Hailin; Feng, Shoushuai; Xin, Yu; Wang, Wu

    2014-02-01

    The community dynamics of attached and free cells of Acidithiobacillus sp. were investigated and compared during chalcopyrite bioleaching process. In the mixed strains system, Acidithiobacillus ferrooxidans was the dominant species at the early stage while Acidithiobacillus thiooxidans owned competitive advantage from the middle stage to the end of bioprocess. Meanwhile, compared to A. ferrooxidans, more significant effects of attached cells on free biomass with A. thiooxidans were shown in either the pure or mixed strains systems. Moreover, the effects of attached cells on key chemical parameters were also studied in different adsorption-deficient systems. Consistently, the greatest reduction of key chemical ion was shown with A. thiooxidans and the loss of bioleaching efficiency was high to 50.5%. These results all demonstrated the bioleaching function of attached cells was more efficient than the free cells, especially with A. thiooxidans. These notable results would help us to further understand the chalcopyrite bioleaching.

  16. Effect of pH values on the extracellular polysaccharide secreted by Acidithiobacillus ferrooxidans during chalcopyrite bioleaching

    Institute of Scientific and Technical Information of China (English)

    Run-lan Yu; Jing Liu; Jian-xi Tan; Wei-min Zeng; Li-juan Shi; Guo-hua Gu; Wen-qing Qin; Guan-zhou Qiu

    2014-01-01

    The pH value plays an important role in the bioleaching of sulphide minerals. The effect of pH values on the extracellular poly-saccharide secreted by Acidithiobacillus ferrooxidans was investigated in different phases of bacterial growth during chalcopyrite bioleach-ing. It is found that extracellular polysaccharide secretion from the cells attached to chalcopyrite is more efficiently than that of the free cells in the bioleaching solution. Three factors, pH values, the concentration of soluble metal ions, and the bacterial growth and metabolism, affect extracellular polysaccharide secretion in the free cells, and are related to the bacterial growth phase. Extracellular polysaccharide secretion from the attached cells is mainly dependent on the pH value of the bacterial culture.

  17. Response of selected plant and insect species to simulated solid rocket exhaust mixtures and to exhaust components from solid rocket fuels

    Science.gov (United States)

    Heck, W. W.; Knott, W. M.; Stahel, E. P.; Ambrose, J. T.; Mccrimmon, J. N.; Engle, M.; Romanow, L. A.; Sawyer, A. G.; Tyson, J. D.

    1980-01-01

    The effects of solid rocket fuel (SRF) exhaust on selected plant and and insect species in the Merritt Island, Florida area was investigated in order to determine if the exhaust clouds generated by shuttle launches would adversely affect the native, plants of the Merritt Island Wildlife Refuge, the citrus production, or the beekeeping industry of the island. Conditions were simulated in greenhouse exposure chambers and field chambers constructed to model the ideal continuous stirred tank reactor. A plant exposure system was developed for dispensing and monitoring the two major chemicals in SRF exhaust, HCl and Al203, and for dispensing and monitoring SRF exhaust (controlled fuel burns). Plants native to Merritt Island, Florida were grown and used as test species. Dose-response relationships were determined for short term exposure of selected plant species to HCl, Al203, and mixtures of the two to SRF exhaust.

  18. Bioleaching of incineration fly ash by Aspergillus niger – precipitation of metallic salt crystals and morphological alteration of the fungus

    Directory of Open Access Journals (Sweden)

    Tong-Jiang Xu

    2014-09-01

    Full Text Available This study examines the bioleaching of municipal solid waste incineration fly ash by Aspergillus niger, and its effect on the fungal morphology, the fate of the ash particles, and the precipitation of metallic salt crystals during bioleaching. The fungal morphology was significantly affected during one-step and two-step bioleaching; scanning electron microscopy revealed that bioleaching caused distortion of the fungal hyphae (with up to 10 μm hyphae diameter and a swollen pellet structure. In the absence of the fly ash, the fungi showed a linear structure (with 2–4 μm hyphae diameter. Energy-dispersive X-ray spectroscopy and X-ray diffraction confirmed the precipitation of calcium oxalate hydrate crystals at the surface of hyphae in both one-step and two-step bioleaching. Calcium oxalate precipitation affects bioleaching via the weakening of the fly ash, thus facilitating the release of other tightly bound metals in the matrix.

  19. Investigation of energy gene expressions and community structures of free and attached acidophilic bacteria in chalcopyrite bioleaching.

    Science.gov (United States)

    Zhu, Jianyu; Jiao, Weifeng; Li, Qian; Liu, Xueduan; Qin, Wenqing; Qiu, Guanzhou; Hu, Yuehua; Chai, Liyuan

    2012-12-01

    In order to better understand the bioleaching mechanism, expression of genes involved in energy conservation and community structure of free and attached acidophilic bacteria in chalcopyrite bioleaching were investigated. Using quantitative real-time PCR, we studied the expression of genes involved in energy conservation in free and attached Acidithiobacillus ferrooxidans during bioleaching of chalcopyrite. Sulfur oxidation genes of attached A. ferrooxidans were up-regulated while ferrous iron oxidation genes were down-regulated compared with free A. ferrooxidans in the solution. The up-regulation may be induced by elemental sulfur on the mineral surface. This conclusion was supported by the results of HPLC analysis. Sulfur-oxidizing Acidithiobacillus thiooxidans and ferrous-oxidizing Leptospirillum ferrooxidans were the members of the mixed culture in chalcopyrite bioleaching. Study of the community structure of free and attached bacteria showed that A. thiooxidans dominated the attached bacteria while L. ferrooxidans dominated the free bacteria. With respect to available energy sources during bioleaching of chalcopyrite, sulfur-oxidizers tend to be on the mineral surfaces whereas ferrous iron-oxidizers tend to be suspended in the aqueous phase. Taken together, these results indicate that the main role of attached acidophilic bacteria was to oxidize elemental sulfur and dissolution of chalcopyrite involved chiefly an indirect bioleaching mechanism.

  20. 搅拌式光生物反应器培养海带配子体细胞:不同脉冲补料方式的研究%Photolithotrophic Cultivation of Laminaria japonica Gametophyte Cells in Stirred Tank Photobioreactors: Studies in Different Pulse Feeding Modes

    Institute of Scientific and Technical Information of China (English)

    陈思晔; 齐瀚实

    2008-01-01

    以批次培养为对照,研究了7种脉冲补料方式对搅拌式光生物反应器中培养大型褐藻海带配子体细胞生长和培养液内氮磷营养盐消耗的影响,并首次探讨了脉冲补料方式下不同补料时间点和补料量的影响作用.培养条件设定为50 mg DCW (细胞干重)/L接种密度、培养液为改良的APSW人工海水、光强60μE/m2.s、光周期16/8h L/D、通气速率和搅拌速率分别为50ml/min和100r/min.结果表明少量补料利于细胞对氮磷的协同吸收,进而利于生物量扩增.当培养液内氮磷富足或耗尽时补料对于生物量大量生产效果甚微,可能由于氮磷吸收变缓、其储存现象显著,或是其吸收协同性降低.当细胞生长至对数中期开始频繁补加少量氮磷营养盐,即维持培养液内氮磷浓度在各自起始浓度的1/3至1/2之间,对生物量生产最有效,生物量增长倍数高达12.270倍.%Photoautotrophic gametophyte cells of the brown macroalgae Laminaria japonica were cultivated in 500ml stirred tank photobioreactors under seven pulse feeding modes and one batch mode.It is the first time for the study of effects of the feeding time points and feeding quantity on macroalgal cell growth and nutrient consumption.Results showed that, with inoculum density of 50mg DCW/L, in modified APSW artificial seawater medium at 13℃, light intensity of 60μE/m2.s, light cycle of 16/8h L/D, aeration rate of 50ml/min, and agitation speed of 100r/min, feeding the culture with small nutrient quantity was beneficial for the synchronization between nitrate and phosphate absorption, and further for biomass production.Feeding when ambient nutrient was abundant or depleted was quite weak for large amount of biomass accumulation, which might be due to the slowing nutrient absorption, nutrient storage, or the divergence absorption between nitrate and phosphate.Feeding nutrient frequently with small quantity from mid-exponential growth of macroalgal cells

  1. 升流式厌氧污泥床和连续流搅拌槽式反应器的废水处理效能及产甲烷菌群组成的对比分析%Comparative Analysis of the Efficiency and the Methanogens Composition in Upflow Anaerobic Sludge Blanket and Continuous Stirred-Tank Reactor

    Institute of Scientific and Technical Information of China (English)

    张立国; 李建政; 班巧英; 许一平

    2012-01-01

    分别运行升流式厌氧污泥床(UASB)反应器和连续流搅拌槽式反应器(CSTR)并使其达到稳定运行状态,在有机负荷率(OLR)均为6.0kg·m-3·d-1的条件下,对比分析了二者在稳定期的运行特性和产甲烷菌群的组成.结果表明,UASB的化学需氧量(COD)去除率为95%,显著高于CSTR的COD去除率(84%).然而,CSTR系统中的活性污泥的比产甲烷速率(315L·kg-1·d-1)和比COD去除率(0.85kg·kg-1·d-1)则显著高于UASB的260L·kg-1·d-1和0.67kg·kg-1·d-1.采用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)指纹分析技术对系统稳定期的活性污泥进行分析的结果表明,UASB系统的优势产甲烷菌为Methanosaeta concilii 和 Methanospirillum hungatei,而CSTR系统中的优势产甲烷菌为Methanosarcina mazeii和Methanobacterium formicicum.污泥微生物群落组成及其代谢特征的不同是造成厌氧处理系统效能差异的内在原因.UASB和CSTR在COD去除效能和污泥比活性方面各有所长,在实际应用中,须根据废水水质和预期处理程度合理选用.%The efficiency and the methanogens composition in an Upflow Anaerobic Sludge Blanket (UASB) reactor and a Continuous Stirred-Tank Reactor (CSTR) are investigated after achieving steady states at the same Organic Loading Rate (OLR) of 6.0kg· m-3 · d-1. The results show that the average removal rate of COD reaches 95% in the UASB, significantly higher than 84% of the CSTR. However, the specific methane production rate and the specific COD removal rate of the activated sludge are SlSL·kg-1·d-1 and 0.85kg·kg-1·d-1, respectively, in the CSTR, notably higher than those of the UASB of 260L·kg-1·d-1 and 0.67kg· kg-1·d-1, respectively. The analysis of the methanogens composition of the activated sludge by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) indicates that Methanosaeta concilii and Methanospirillum hungatei are the dominant methanogens in the UASB, while

  2. Enhanced Cr bioleaching efficiency from tannery sludge with coinoculation of Acidithiobacillus thiooxidans TS6 and Brettanomyces B65 in an air-lift reactor.

    Science.gov (United States)

    Fang, Di; Zhou, Li-Xiang

    2007-09-01

    Bioleaching process has been demonstrated to be an effective technology in removing Cr from tannery sludge, but a large quantity of dissolved organic matter (DOM) present in tannery sludge often exhibits a marked toxicity to chemolithoautotrophic bioleaching bacteria such as Acidithiobacillus thiooxidans. The purpose of the present study was therefore to enhance Cr bioleaching efficiencies through introducing sludge DOM-degrading heterotrophic microorganism into the sulfur-based sludge bioleaching system. An acid-tolerant DOM-degrading yeast strain Brettanomyces B65 was successfully isolated from a local Haining tannery sludge and it could metabolize sludge DOM as a source of energy and carbon for growth. A combined bioleaching experiment (coupling Brettanomyces B65 and A. thiooxidans TS6) performed in an air-lift reactor indicated that the rates of sludge pH reduction and ORP increase were greatly improved, resulting in enhanced Cr solubilization. Compared with the 5 days required for maximum solubilization of Cr for the control (single bioleaching process without inoculation of Brettanomyces B65), the bioleaching period was significantly shorten to 3 days for the combined bioleaching system. Moreover, little nitrogen and phosphorous were lost and the content of Cr was below the permitted levels for land application after 3 days of bioleaching treatment.

  3. Bioleaching of serpentine group mineral by fungus Talaromyces flavus: application for mineral carbonation

    Science.gov (United States)

    Li, Z.; Lianwen, L.; Zhao, L.; Teng, H.

    2011-12-01

    Many studies of serpentine group mineral dissolution for mineral carbonation have been published in recent years. However, most of them focus mainly on either physical and chemical processes or on bacterial function, rather than fungal involvement in the bioleaching of serpentine group mineral. Due to the excessive costs of the magnesium dissolution process, finding a lower energy consumption method will be meaningful. A fungal strain Talaromyces flavus was isolated from serpentinic rock of Donghai (China). No study of its bioleaching ability is currently available. It is thus of great significance to explore the impact of T. flavus on the dissolution of serpentine group mineral. Serpentine rock-inhabiting fungi belonging to Acremonium, Alternaria, Aspergillus, Botryotinia, Cladosporium, Clavicipitaceae, Cosmospora, Fusarium, Monascus, Paecilomyces, Penicillium, Talaromyces, Trichoderma were isolated. These strains were chosen on the basis of resistance to magnesium and nickel characterized in terms of minimum inhibiting concentration (MIC). Specifically, the strain Talaromyces flavus has a high tolerance to both magnesium (1 mol/L) and nickel (10 mM/L), and we examine its bioleaching ability on serpentine group mineral. Contact and separation experiments (cut-off 8 000-14 000 Da), as well as three control experiments, were set up for 30 days. At least three repeated tests were performed for each individual experiment. The results of our experiments demonstrate that the bioleaching ability of T. flavus towards serpentine group mineral is evident. 39.39 wt% of magnesium was extracted from lizardite during the bioleaching period in the contact experiment, which showed a dissolution rate at about a constant 0.126 mM/d before reaching equilibrium in 13 days. The amount of solubilized Mg from chrysotile and antigorite were respectively 37.79 wt% and 29.78 wt% in the contact experiment. These results make clear the influence of mineral structure on mineral bioleaching

  4. Biofilm forming and leaching mechanism during bioleaching chalcopyrite by Thiobacillus ferrooxidans

    Institute of Scientific and Technical Information of China (English)

    傅建华; 胡岳华; 邱冠周; 柳建设; 徐竞

    2004-01-01

    The mechanism of attachment and leaching of thiobacillus ferrooxcidans (T. f. ) on chalcopyrite were studied. The shaking flasks with bacteria were observed by SEM. The process of T. f attached to the surface of the mineral sample and the biofilm forming were described. The promoting role of the biofilm for bioleaching was discussed. The existence of Fe2+ in the exopolysaccharide layer of T. f was demonstrated by EM(electronic microscope)cell-chemistry analysis. These results show that under the proper growth condition of bacteria, bioleaching of chalcopyrite results in the formation of complete biofilm after 2 - 3 weeks. There are iron ions in the outer layer polymer of T. f. , which provides the micro-environment for themselves, and can guaruntee the energy needed for the bacteria growth in the biofilm. At the same time, Fe3+ ions produced oxidize sulfide which brings about the increase of both growth rate of the bacterial and leaching rate of sulfide minerals.

  5. Dominance of Acidithiobacillus at ore surface of Zijinshan commercial low-grade copper bioleaching heap

    Institute of Scientific and Technical Information of China (English)

    LIU Xing-yu; CHEN Bo-wei; WEN Jian-kang

    2008-01-01

    The microbial community structure in the ore surface of Zijinshan commercial low-grade copper bioleaching heap was investigated by 16S rRNA gene clone library.For both bacteria and Archaea,105 clones were sequenced.The dominant bacteria species present in the ore surface were Acidithiobacillus and Leptospirillum,accounting for 51.42% and 48.57%,respectively.However,for the Archaea,only one operational taxonomic unit (OUT) belonged to Ferroplasma acidiphilum.These results indicate that function of genus Acidithiobacillus in the commercial low-grade copper bioleaching heap may be underestimated.More detailed and quantitative information on microbial community structure over time are now under investigation.

  6. Silver-catalyzed bioleaching for raw low-grade copper sulphide ores

    Institute of Scientific and Technical Information of China (English)

    Tianlong DENG; Yafei GUO; Mengxia LIAO; Dongchan LI

    2009-01-01

    This research was conducted to investigate the biooxidation and copper dissolution from raw low-grade refractory copper sulphide ores located in the Xinjiang Autonomous Region of China using adapted Thiobacillus ferrooxidans bacteria. In order to accelerate the bioleach-ing rate, the adapted mixed bacteria and silver ion catalyst were tested in the leach columns at laboratory scale. The overall acid consumption was 4.3 kg sulphuric acid per kg of dissolved copper and was linearly related to the percent copper dissolution. The calculated copper dissolution rates obey the Shrinking Core Model. The relative activation energy of the whole biooxidative leaching stages was calculated to be 48.58 kJ/mol.

  7. Influences of silver sulfide on the bioleaching of chalcopyrite, pyrite and chalcopyrite-containing ore

    Institute of Scientific and Technical Information of China (English)

    胡岳华; 王军; 邱冠周; 王淀佐

    2002-01-01

    The effects of silver sulfide (Ag2S) on the bioleaching of chalcopyrite and pyrite were investigated in this paper. It has been shown that Ag2S enhanced the yields of bioleaching of chalcopyrite but inhibited the bio-oxidation of pyrite. The addition of Ag2S selectively increased the copper dissolution from the chalcopyrite-containing ores in shake flasks with a recovery of 85.3% compared with 24.3% without Ag2S, while slightly decreased the iron yields from 51% to 41.8%. The copper extraction of the chalcoopyrite-containing waste rock in column leaching charged with 18 kg mass increased up to 21.7% in the presence of Ag2S, while only 3.4% in the absence of the catalyst. The mechanism of Ag2S catalysis could be explained well by the "Mixed potential model".

  8. Iron removal on feldspar by using Averrhoa bilimbii as bioleaching agent

    Science.gov (United States)

    Amin, Muhammad; Aji, Bramantyo B.; Supriyatna, Yayat Iman; Bahfie, Fathan

    2017-01-01

    Investigation of Averrhoa bilimbii as bioleaching agent was carried out. Parameters of leaching duration, acid concentration, and temperature were performed in iron removal process. Feldspar with sized 149 µm was diluted in 30 ml acid solution in order to reduce its iron content. The experimental results showed a good technical feasibility of the process which iron oxide content of feldspar was decreased from 2.24% to 0.29%. The lowest iron concentration remained was obtained after 5 hours of leaching treatment at 60 °C, and concentrated (100 vol%) Averrhoa bilimbii extract as bioleaching agent. SEM characterizations were carried out on the feldspar before and after the leaching treatment. The result shows that there were no significant effect of leaching process on the ore morphology.

  9. Bioleaching of marmatite flotation concentrate by Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans

    Institute of Scientific and Technical Information of China (English)

    石绍渊; 方兆珩

    2004-01-01

    Bioleaching of marmatite flotation concentrate by Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans was investigated at 35 ℃, the initial pH value of 2.0 on an orbital shaker with 160 min-1 over a period of 10 days. Experimental results indicate that the adapted strains increase markedly the dissolution rate and the leaching ratio of marmatite. Pulp density also affects the bioleaching of marmatite. Massive elemental sulfur and jarosite form during the leaching process in the systems inoculating the adapted strains in pure and mixed cultures; and acid product is enhanced, which decreases the pH below to 2.0 in latter leaching period. Marmatite preferentially dissolves during the bacterial leaching of complex sulfides. Compared with the pure cultures of original and adapted strains, the adapted strains of Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans in mixed cultures are more efficient in the oxidation of marmatite.

  10. Efficacy of chalcopyrite bioleaching using a pure and a mixed bacterium

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    To determine the efficacy of chalcopyrite bioleaching using pure cultures of Thiobacillus ferrooxidans or Thiobacillus thiooxidans and a mixed culture composed of Thiobacillus ferrooxidans and Thiobacillus thiooxidans, experiments were carried out mixed culture composed of Thiobacillusferrooxidans and Thiobacillus thiooxidans is higher than that in a pure culture. On the other hand, an important potential of Thiobacillus thiooxidans to leaching chalcopyrite was indicated. Thiobacillus thiooxidans can prevent jarosites accumulating on the substrate and allow further copper to dissolute through the action of ferric ion. The selection of the suitable pH in a leaching solution would be significant. Thiobacillus thiooxidans and Thiobacillus ferrooxidans play an important role in the bioleaching process. Finally, the mechanism and the reason for iron precipitation were also discussed in detail.

  11. Bioleaching of spent hydrotreating catalyst by acidophilic thermophile Acidianus brierleyi: Leaching mechanism and effect of decoking.

    Science.gov (United States)

    Bharadwaj, Abhilasha; Ting, Yen-Peng

    2013-02-01

    Bioleaching of spent hydrotreating catalyst by thermophillic archae Acidianus brierleyi was investigated. The spent catalyst (containing Al, Fe, Ni and Mo as major elements) was characterized, and the effect of pretreatment (decoking) on two-step and spent medium leaching was examined at 1% w/v pulp density. Decoking resulted in removal of carbonaceous deposits and volatile impurities, and affected the solubility of metal compounds through oxidization of the metal sulfides. Nearly 100% extraction was achieved using spent medium leaching for Fe, Ni and Mo, and 67% for Al. Bioleaching reduced nickel concentration in the leachate below the regulated levels for safe waste disposal. Chemical (i.e. abiotic) leaching using equimolar concentration of sulfuric acid produced by the bacteria during two-step process achieved a lower leaching efficiency (by up to 30%). Results indicated that A. brierleyi successfully leached heavy metals from spent catalyst.

  12. Changes in Texture and Retorting Yield in Oil Shale During Its Bioleaching by Bacillus Mucilaginosus

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xue-qing; REN He-jun; LIU Na; ZHANG Lan-ying; ZHOU Rui

    2013-01-01

    Bioleaching of oil shale by Bacillus mucilaginosus was carried out in a reaction column for 13 d.The pH value of the leaching liquor decreased steadily from 7.5 to 5.5 and the free silicon dioxide concentration reached approximately 200 mg/L in it.Scanning electron microscopy(SEM) observations revealed that a mass of small particles separated from the matrix of oil shale.Energy dispersive spectrometry(EDS) analysis implied that the total content of Si,O,A1 was decreased in the particle area of the matrix.These facts indicate that the silicate was removed,leading to the structural transformation of oil shale.Comparison of the shale oil yields before and after bioleaching illustrated that approximately 10% extra shale oil was obtained.This finding suggests that the demineralisation of the oil shale by silicate bacteria improves shale oil yield.

  13. Bioleaching of Arsenic-Rich Gold Concentrates by Bacterial Flora before and after Mutation

    Directory of Open Access Journals (Sweden)

    Xuehui Xie

    2013-01-01

    Full Text Available In order to improve the bioleaching efficiency of arsenic-rich gold concentrates, a mixed bacterial flora had been developed, and the mutation breeding method was adopted to conduct the research. The original mixed bacterial flora had been enrichedin acid mine drainage of Dexing copper mine, Jiangxi Province, China. It was induced by UV (ultraviolet, ultrasonic, and microwave, and their combination mutation. The most efficient bacterial flora after mutation was collected for further bioleaching of arsenic-rich gold concentrates. Results indicated that the bacterial flora after mutation by UV 60 s combined with ultrasonic 10 min had the best oxidation rate of ferrous, the biggest density of cells, and the most activity of total protein. During bioleaching of arsenic-rich gold concentrates, the density of the mutant bacterial cells reached to 1.13×108 cells/mL at 15 days, more than 10 times compared with that of the original culture. The extraction of iron reached to 95.7% after 15 days, increased by 9.9% compared with that of the original culture. The extraction of arsenic reached to 92.6% after 12 days, which was increased by 46.1%. These results suggested that optimum combined mutation could improve leaching ability of the bacterial flora more significantly.

  14. Bioleaching of arsenic-rich gold concentrates by bacterial flora before and after mutation.

    Science.gov (United States)

    Xie, Xuehui; Yuan, Xuewu; Liu, Na; Chen, Xiaoguang; Abdelgadir, Awad; Liu, Jianshe

    2013-01-01

    In order to improve the bioleaching efficiency of arsenic-rich gold concentrates, a mixed bacterial flora had been developed, and the mutation breeding method was adopted to conduct the research. The original mixed bacterial flora had been enrichedin acid mine drainage of Dexing copper mine, Jiangxi Province, China. It was induced by UV (ultraviolet), ultrasonic, and microwave, and their combination mutation. The most efficient bacterial flora after mutation was collected for further bioleaching of arsenic-rich gold concentrates. Results indicated that the bacterial flora after mutation by UV 60 s combined with ultrasonic 10 min had the best oxidation rate of ferrous, the biggest density of cells, and the most activity of total protein. During bioleaching of arsenic-rich gold concentrates, the density of the mutant bacterial cells reached to 1.13 × 10⁸ cells/mL at 15 days, more than 10 times compared with that of the original culture. The extraction of iron reached to 95.7% after 15 days, increased by 9.9% compared with that of the original culture. The extraction of arsenic reached to 92.6% after 12 days, which was increased by 46.1%. These results suggested that optimum combined mutation could improve leaching ability of the bacterial flora more significantly.

  15. Metal removal from Municipal Solid Waste Incineration fly ash: A comparison between chemical leaching and bioleaching.

    Science.gov (United States)

    Funari, V; Mäkinen, J; Salminen, J; Braga, R; Dinelli, E; Revitzer, H

    2017-02-01

    Bio- and hydrometallurgical experimental setups at 2-l reactor scale for the processing of fly ash from municipal waste incinerators were explored. We aimed to compare chemical H2SO4 leaching and bioleaching; the latter involved the use of H2SO4 and a mixed culture of acidophilic bacteria. The leaching yields of several elements, including some of those considered as critical (Mg, Co, Ce, Cr, Ga, Nb, Nd, Sb and Sm), are provided. At the end of the experiments, both leaching methods resulted in comparable yields for Mg and Zn (>90%), Al and Mn (>85%), Cr (∼65%), Ga (∼60%), and Ce (∼50%). Chemical leaching showed the best yields for Cu (95%), Fe (91%), and Ni (93%), whereas bioleaching was effective for Nd (76%), Pb (59%), and Co (55%). The two leaching methods generated solids of different quality with respect to the original material as we removed and significantly reduced the metals amounts, and enriched solutions where metals can be recovered for example as mixed salts for further treatment. Compared to chemical leaching the bioleaching halved the use of H2SO4, i.e., a part of agent costs, as a likely consequence of bio-produced acid and improved metal solubility.

  16. Zinc bioleaching from an iron concentrate using Acidithiobacillus ferrooxidans strain from Hercules Mine of Coahuila, Mexico

    Science.gov (United States)

    Núñez-Ramírez, Diola Marina; Solís-Soto, Aquiles; López-Miranda, Javier; Pereyra-Alférez, Benito; Rutiaga-Quiñónes, Miriam; Medina-Torres, Luis; Medrano-Roldán, Hiram

    2011-10-01

    The iron concentrate from Hercules Mine of Coahuila, Mexico, which mainly contained pyrite and pyrrhotite, was treated by the bioleaching process using native strain Acidithiobacillus ferrooxidans ( A. ferrooxidans) to determine the ability of these bacteria on the leaching of zinc. The native bacteria were isolated from the iron concentrate of the mine. The bioleaching experiments were carried out in shake flasks to analyze the effects of pH values, pulp density, and the ferrous sulfate concentration on the bioleaching process. The results obtained by microbial kinetic analyses for the evaluation of some aspects of zinc leaching show that the native bacteria A. ferrooxidans, which is enriched with a 9K Silverman medium under the optimum conditions of pH 2.0, 20 g/L pulp density, and 40 g/L FeSO4, increases the zinc extraction considerably observed by monitoring during15 d, i.e., the zinc concentration has a decrease of about 95% in the iron concentrate.

  17. Lessons from the genomes of extremely acidophilic bacteria and archaea with special emphasis on bioleaching microorganisms.

    Science.gov (United States)

    Cárdenas, Juan Pablo; Valdés, Jorge; Quatrini, Raquel; Duarte, Francisco; Holmes, David S

    2010-10-01

    This mini-review describes the current status of recent genome sequencing projects of extremely acidophilic microorganisms and highlights the most current scientific advances emerging from their analysis. There are now at least 56 draft or completely sequenced genomes of acidophiles including 30 bacteria and 26 archaea. There are also complete sequences for 38 plasmids, 29 viruses, and additional DNA sequence information of acidic environments is available from eight metagenomic projects. A special focus is provided on the genomics of acidophiles from industrial bioleaching operations. It is shown how this initial information provides a rich intellectual resource for microbiologists that has potential to open innovative and efficient research avenues. Examples presented illustrate the use of genomic information to construct preliminary models of metabolism of individual microorganisms. Most importantly, access to multiple genomes allows the prediction of metabolic and genetic interactions between members of the bioleaching microbial community (ecophysiology) and the investigation of major evolutionary trends that shape genome architecture and evolution. Despite these promising beginnings, a major conclusion is that the genome projects help focus attention on the tremendous effort still required to understand the biological principles that support life in extremely acidic environments, including those that might allow engineers to take appropriate action designed to improve the efficiency and rate of bioleaching and to protect the environment.

  18. Effect of substrate concentration on the bioleaching of heavy metals from sewage sludge

    Institute of Scientific and Technical Information of China (English)

    CHEN Ying-xu; HUA Yu-mei; ZHANG Shao-hui

    2004-01-01

    The effect of elemental sulfur concentration on bioleaching of Cu, Zn and Pb and loss of fertilizer value from sewage sludge was investigated in flasks by batch experiments. The results showed that the ultimate pH of sludges with 3-5 g/L of sulfur added was about 1.3 and the production of SO42- had good correlation with the elemental sulfur concentration. The sensitivity of removal efficiency of metals to sulfur concentration was: Pb>Cu>Zn. The sulfur concentration except for 3-5 g/L had significant effect on the solubilization of Cu, Pb and Zn. The highest solubilization efficiency for sludge with 3 g/L of sulfur was 87.86% for Cu, 32.72% for Pb and 92.14% for Zn, which could make the treated sludge easily meet the metal limitations for land application. The sulfur concentration of 3 g/L was enough for the solubilization of all three heavy metals. The influence of sulfur concentration on solubilization of total nitrogen and potassium from sludge was negligible, but that on solublization of total phosphorus was of great importance. The loss of nitrogen, phosphorus and potassium of sludge with 3 g/L of sulfur by bioleaching was 38.2%, 52.1% and 42.8% respectively, and the sludge still remained satisfactory fertilizer value after bioleaching.

  19. Intermediary sulfur compounds in pyrite oxidation: implications for bioleaching and biodepyritization of coal

    Energy Technology Data Exchange (ETDEWEB)

    Schippers, A.; Rohwerder, T.; Sand, W. [Hamburg Univ. (Germany). Inst. fuer Allgemeine Botanik und Botanischer Garten

    1999-07-01

    Accumulation of elemental sulfur during pyrite oxidation lowers the efficiency of coal desulfurization and bioleaching. In the case of pyrite bioleaching by Leptospirillum ferrooxidans, an iron(II)-ion-oxidizing organism without sulfur-oxidizing capacity, from the pyritic sulfur moiety about 10% elemental sulfur, 2% pentathionate, and 1% tetrathionate accumulated by a recently described cyclic pyrite oxidation mechanism. In the case of pure cultures of Thiobacillus ferrooxidans and mixed cultures of L. ferrooxidans and T. thiooxidans, pyrite was nearly completely oxidized to sulfate because of the capacity of these cultures to oxidize both iron(II) ions and sulfur compounds. Pyrite oxidation in acidic solutions, mediated chemically by iron(III) ion, resulted in an accumulation of similar amounts of sulfur compounds as obtained with L. ferrooxidans. Changes of pH to values below 2 or in the iron ion concentration are not decisive for diverting the flux of sulfur compounds. The literature on pyrite bioleaching is in agreement with the findings indicating that the chemistry of direct and indirect pyrite leaching is identical. (orig.)

  20. Penetration analysis of elements and bioleaching treatment of spent refractory for recycling

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Acidithiobacillus ferrooxidans ATCC23270 and Acidithiobacillus thiooxidans TM-32 were used for bioleaching of spent refractories of aluminium and copper melting furnaces for their recycling.Firstly,penetration of elements into aluminium melting furnace refractory was investigated and it was found that up to 7 cm from surface was contaminated.Comparison on leaching efficiency by the strains ATCC23270 and TM-32 found that the strain ATCC23270 could treat larger amount of the refractories than the strain TM-32 could do.In the experiment of bioleaching of spent refractory aluminium melting furnace by the strain ATCC23270,high leaching efficiency were obtained on A1,Si,and Ca,and extremely low leaching performance was,however,shown on the rest of elements i.e.,Na,Mn,and Zn.Under the strain TM-32 use,relatively high leaching performance was recognized on Al,Si,Ca,Na,Mn,and Zn.In the experiment of bioleaching for spent refractory copper melting furnace,almost the same leaching trends were shown on Cu,Zn,Al,and Si under the strains ACTT23270 and TM-32 uses.

  1. Effect of salinity and acidity on bioleaching activity of mesophilic and extremely thermophilic bacteria

    Institute of Scientific and Technical Information of China (English)

    H.DEVECI; M.A.JORDAN; N.POWELL; I.ALP

    2008-01-01

    The effects of bacterial strain,salinity and pH on the bioleaching of a complex ore using mesophilic and extremely thermophilic bacteria were investigated and the statistical analysis of the results was performed using ERGUN's test.The extreme thermophiles were shown to display superior kinetics of dissolution of zinc compared with the mesophiles as confirmed by the statistical analysis.Bioleaching performance of the extreme thermophiles is found to improve in response to the increase in acidity (pH from 2.0 to 1.0) whilst the activity of the mesophiles is adversely affected by decreasing pH.Statistical analysis of the bioleaching data indicates that the effect of pH is insignificant in the range of pH 1.0-1.2 for the extreme thermophiles and pH 1.4-2.0 for the mesophiles.Salinity is shown to have a suppressing effect on the mesophiles.However,the extreme thermophiles appear to be halophilic in character as they could operate efficiently under saline conditions (1%-4%C1- (w/v)).

  2. Bioleaching of electronic waste using bacteria isolated from the marine sponge Hymeniacidon heliophila (Porifera).

    Science.gov (United States)

    Rozas, Enrique E; Mendes, Maria A; Nascimento, Claudio A O; Espinosa, Denise C R; Oliveira, Renato; Oliveira, Guilherme; Custodio, Marcio R

    2017-05-05

    The bacteria isolated from Hymeniacidon heliophila sponge cells showed bioleaching activity. The most active strain, Hyhel-1, identified as Bacillus sp., was selected for bioleaching tests under two different temperatures, 30°C and 40°C, showing rod-shaped cells and filamentous growth, respectively. At 30°C, the bacteria secreted substances which linked to the leached copper, and at 40°C metallic nanoparticles were produced inside the cells. In addition, infrared analysis detected COOH groups and linear peptides in the tested bacteria at both temperatures. The Hyhel-1 strain in presence of electronic waste (e-waste) induced the formation of crust, which could be observed due to bacteria growing on the e-waste fragment. SEM-EDS measurements showed that the bacterial net surface was composed mostly of iron (16.1% w/w), while a higher concentration of copper was observed in the supernatant (1.7% w/w) and in the precipitated (49.8% w/w). The substances linked to copper in the supernatant were sequenced by MALDI-TOF-ms/ms and identified as macrocyclic surfactin-like peptides, similar to the basic sequence of Iturin, a lipopeptide from Bacillus subtilis. Finally, the results showed that Hyhel-1 is a bioleaching bacteria and cooper nanoparticles producer and that this bacteria could be used as a copper recovery tool from electronic waste. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Significance of bioleaching method in dissolution of iron and in the quality improvement of non-metallics

    Directory of Open Access Journals (Sweden)

    Iveta Štyriaková

    2006-12-01

    Full Text Available Simple laboratory bioleaching experiments for the iron removal with heterotrophic bacteria on natural raw materials were conducted to explore a simple cyclic operation for a potential use at the industrial scale. Heterotrophic bacteria of Bacillus spp. growing in the presence of feldspar raw materials are able to dissolve iron. Anaerobic conditions Quickly formed by bacteria enable a simple manipulation with the sample solution. Insoluble Fe(III in the feldspars sample could be enzymatically dissolved as Fe3+ and also reduced to soluble Fe2+ by silicate bacteria of Bacillus spp. This metal was efficiently removed from the feldspars sample as documented by a Fe2O3 decrease (from 0.29 % to 0.12 % after bioleaching in the conical flask and by a Fe2O3 decrease (from 0.29 % to 0.19 % after bioleaching in the percolate column. Bioleaching of Fe was more effective in the conical flask. Iron-bearing minerals can be easily removed by magnetic separation, but ultra fine iron particles are difficult to treat by conventional mineral processing methods. Thus bioleaching is an attractive alternative for effective removal of iron minerals. The removal of iron with the whiteness increase should give a product, which is fit for industrial ceramic applications.

  4. Modeling and Simulation of Enargite Bioleaching%硫砷铜矿生物浸出模型与模拟

    Institute of Scientific and Technical Information of China (English)

    宋健; 林建群; 高玲; 林建强; 曲音波

    2008-01-01

    A mathematical model for enargite bioleaching at 70℃by Sulfolobus BC in shake-flasks has been con-structed.The model included(1)the indirect leaching by-Fe3+and Fe3+regeneration by suspended Sulfolobus,and (2)the direct leaching by the attached Sulfolobus.The model parameters were optimized using genetic algorithm (GA).Simulations of the ferric leaching.,and bioleaching processes were done using this model The dynamic changes of the concentrations of Cu2+,As3+,As5+,Fe3+and/or Fe2+,as well as ferric-arsenate precipitation were ac-curately predicted.

  5. Bioleaching of metals from printed circuit boards supported with surfactant-producing bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Karwowska, Ewa, E-mail: ewa.karwowska@is.pw.edu.pl [Warsaw University of Technology, Faculty of Environmental Engineering, Biology Division, Nowowiejska 20, 00-653 Warsaw (Poland); Andrzejewska-Morzuch, Dorota; Łebkowska, Maria [Warsaw University of Technology, Faculty of Environmental Engineering, Biology Division, Nowowiejska 20, 00-653 Warsaw (Poland); Tabernacka, Agnieszka, E-mail: agnieszka.tabernacka@is.pw.edu.pl [Warsaw University of Technology, Faculty of Environmental Engineering, Biology Division, Nowowiejska 20, 00-653 Warsaw (Poland); Wojtkowska, Małgorzata; Telepko, Alicja; Konarzewska, Agnieszka [Warsaw University of Technology, Faculty of Environmental Engineering, Nowowiejska 20, 00-653 Warsaw (Poland)

    2014-01-15

    Highlights: • Bioleaching of metals from printed circuit boards by BSAC-producing bacteria was estimated. • Aeration increased the release of all metals in medium with sulphur and biosurfactant. • Increase in Cu, Pb, Ni and Cr removal rate was observed at 37 °C in acidic medium. -- Abstract: This study has evaluated the possibility of bioleaching zinc, copper, lead, nickel, cadmium and chromium from printed circuit boards by applying a culture of sulphur-oxidising bacteria and a mixed culture of biosurfactant-producing bacteria and sulphur-oxidising bacteria. It was revealed that zinc was removed effectively both in a traditional solution acidified by a way of microbial oxidation of sulphur and when using a microbial culture containing sulphur-oxidising and biosurfactant-producing bacteria. The average process efficiency was 48% for Zn dissolution. Cadmium removal was similar in both media, with a highest metal release of 93%. For nickel and copper, a better effect was obtained in the acidic medium, with a process effectiveness of 48.5% and 53%, respectively. Chromium was the only metal that was removed more effectively in the bioleaching medium containing both sulphur-oxidising and biosurfactant-producing bacteria. Lead was removed from the printed circuit boards with very low effectiveness (below 0.5%). Aerating the culture medium with compressed air increased the release of all metals in the medium with sulphur and biosurfactant, and of Ni, Cu, Zn and Cr in the acidic medium. Increasing the temperature of the medium (to 37 °C) had a more significant impact in the acidic environment than in the neutral environment.

  6. A study on the selection of indigenous leaching-bacteria for effective bioleaching

    Science.gov (United States)

    Oh, S. J.; Cho, K. H.; Kim, B. J.; Choi, N. C.; Park, C. Y.

    2012-04-01

    Bioleaching technology, which is based on the ability of microorganisms to transform solid compounds into soluble and extractable valuable elements that can be recovered, has been rapidly developed in recent decades for its advantages, which include mild reaction condition, low energy consumption, simple process, low environmental impact and being suitable for low grade mine tailings and residues. The bacteria activities (survival, adaptation of toxically environments etc.) in the bioleaching technology play a key role in the solubilization of metals. The purpose of this study was to selection of optimal leaching-bacteria through changed pH and redox potential on bio-oxidation in batch experiments for successful bioleaching technology. Twenty three indigenous bacteria used throughout this study, leaching-bacteria were obtained from various geochemical conditions; bacteria inhabitation type (acid mine drainage, mine wastes leachate and sulfur hot springs) and base-metal type (sulfur, sulfide, iron and coal). Bio-oxidation experiment result was showed that 9 cycles (1 cycle - 28days) after the leaching-bacteria were inoculated to a leaching medium, pH was observed decreasing and redox potential increased. In the bacteria inhabitation type, bio-oxidation of sulfur hot springs bacteria was greater than other types (acid mine drainage and mine wastes leachate). In addition, bio-oxidation on base-metal type was appeared sulfur was greater than other types (sulfide, iron and coal). This study informs basic knowledge when bacteria apply to eco-/economic resources utilization studies including the biomining and the recycling of mine waste system.

  7. Electrochemical studies on interplay of mineralogical variation and particle size on bioleaching low grade complex sulphide ores

    Institute of Scientific and Technical Information of China (English)

    P. A. OLUBAMBI; J. H. POTGIETER; S. NDLOVU; J. O. BORODE

    2009-01-01

    The interplay of mineralogical variation and mineral phase distribution within varying particle sizes on the dissolution behaviour of a low grade complex sulphide ore was investigated through bioleaching experiments and electrochemical technique. Investigations were carried out utilizing mineralogical data on the variations in mineral and phase distribution within particle sizes of<53 μm, 53-75 μm, 75-106 μm and 106-150 μm in mixed mesophilic cultures of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans. Electrochemical behaviour was studied using particulate electrodes from the four varying particle sizes and from massive electrodes prepared from the two major sulphide mineral rich phases (sphalerite-rich and galena-rich) and a complex mineralogical phase of the bulk ore. Bioleaching studies reveal the highest recoveries at a particle size of 75 μm, while electrochemical investigations reveal the highest dissolution at particle size of 106 μm. Electrochemical results show that sphalerite rich phase has the highest dissolution rate while galena-rich complex phase has the least. SEM studies confirm the highest bacterial attack at the sphalerite-rich phase. The discrepancies between the dissolutions within particle sizes obtained from bioleaching experiments and electrochemical studies are consistent with and attributed both to the physical and mineralogical influences. Electrochemical behaviour is influenced and controlled by galvanic interaction resulting from mineralogical variation, while bioleaching behaviour is influenced by mineralogical variation as well as physical effect of particle size.

  8. The shift of microbial communities and their roles in sulfur and iron cycling in a copper ore bioleaching system.

    Science.gov (United States)

    Niu, Jiaojiao; Deng, Jie; Xiao, Yunhua; He, Zhili; Zhang, Xian; Van Nostrand, J D; Liang, Yili; Deng, Ye; Liu, Xueduan; Yin, Huaqun

    2016-10-04

    Bioleaching has been employed commercially to recover metals from low grade ores, but the production efficiency remains to be improved due to limited understanding of the system. This study examined the shift of microbial communities and S&Fe cycling in three subsystems within a copper ore bioleaching system: leaching heap (LH), leaching solution (LS) and sediment under LS. Results showed that both LH and LS had higher relative abundance of S and Fe oxidizing bacteria, while S and Fe reducing bacteria were more abundant in the Sediment. GeoChip analysis showed a stronger functional potential for S(0) oxidation in LH microbial communities. These findings were consistent with measured oxidation activities to S(0) and Fe(2+), which were highest by microbial communities from LH, lower by those from LS and lowest form Sediment. Moreover, phylogenetic molecular ecological network analysis indicated that these differences might be related to interactions among microbial taxa. Last but not the least, a conceptual model was proposed, linking the S&Fe cycling with responsible microbial populations in the bioleaching systems. Collectively, this study revealed the microbial community and functional structures in all three subsystems of the copper ore, and advanced a holistic understanding of the whole bioleaching system.

  9. Extraction, isolation and NMR data of the tetraether lipid calditoglycerocaldarchaeol (GDNT) from Sulfolobus metallicus harvested from a bioleaching reactor

    CSIR Research Space (South Africa)

    Bode, ML

    2008-08-01

    Full Text Available thermophilic (68 C) bioleaching tank reactor used to extract nickel from a pentlandite mineral concentrate. The initial Soxhlet extraction method employed was scaled to a bench-scale extraction procedure suitable for the preparation of gram-scale quantities...

  10. 黄铜矿生物浸出机制研究进展%Research Progress of Chalcopyrite Bioleaching Mechanism

    Institute of Scientific and Technical Information of China (English)

    曾伟民; 邱冠周

    2012-01-01

    ItS necessary to solve the problem of low efficiency of chalcopyrite bioleaching by the bioleaching mechanism. Reviewed the development progress of bioleaching mechanism from "direct and indirect action" theory to "contact action" theory,then "indirect action-direct contact action-indirect contact action" theory and introduced the correlation model and explanation in detail. The chalcopyrite bioleaching mechanism isnt verdict and needs to continue thorough research.%要解决黄铜矿生物浸出效率较低的难题,需要从生物浸出机制人手.回顾了生物浸出机制从“直接作用”和“间接作用”理论到“接触作用”理论,再到“间接作用-直接接触作用-间接接触作用”理论的发展历程,并对这些理论的相关模型和解释进行了详细介绍.最后指出黄铜矿生物浸出机制尚未定论,还有待于继续深入研究.

  11. Bioleaching of gold, copper and nickel from waste cellular phone PCBs and computer goldfinger motherboards by two Aspergillus nigerstrains

    Directory of Open Access Journals (Sweden)

    Jorge Enrique Madrigal-Arias

    2015-09-01

    Full Text Available In an effort to develop alternate techniques to recover metals from waste electrical and electronic equipment (WEEE, this research evaluated the bioleaching efficiency of gold (Au, copper (Cu and nickel (Ni by two strains of Aspergillus niger in the presence of gold-plated finger integrated circuits found in computer motherboards (GFICMs and cellular phone printed circuit boards (PCBs. These three metals were analyzed for their commercial value and their diverse applications in the industry. Au-bioleaching ranged from 42 to 1% for Aspergillus niger strain MXPE6; with the combination of Aspergillus niger MXPE6 + Aspergillus niger MX7, the Au-bioleaching was 87 and 28% for PCBs and GFICMs, respectively. In contrast, the bioleaching of Cu by Aspergillus niger MXPE6 was 24 and 5%; using the combination of both strains, the values were 0.2 and 29% for PCBs and GFICMs, respectively. Fungal Ni-leaching was only found for PCBs, but with no significant differences among treatments. Improvement of the metal recovery efficiency by means of fungal metabolism is also discussed.

  12. Comparison of microbial communities in three different mine drainages and their bioleaching efficiencies to low grade of chalcopyrite

    Institute of Scientific and Technical Information of China (English)

    YIN Hua-qun; QIU Guan-zhou; WANG Dian-zuo; CAO Lin-hui; DAI Zhi-min; WANG Jie-wei; LIU Xue-duan

    2007-01-01

    Microbial community diversities in the drainage from three mines (Dexing Copper Mine, Qibaoshan Copper Mine and Yaogangxian Tungsten Mine, China) were analyzed using 16S rDNA PCR-RFLP approach. The efficiencies of chalcopyrite bioleaching were compared using enrichment of the three cultures. Phylogenetic analysis indicates that the dominant microorganisms are clustered with the Proteobacteria, the remaining is affiliated with Nitrospira, Acidobacteria and Actinobacteria.At the genus level, Acidithiobacillus is the dominant group in both YTW and QBS samples, while Spingomonas is dominant in YGX sample. Moreover, the principal component analysis (PCA) reveals that QBS and YTW have similar geochemical character and microbial communities. The results also show that pH value and tungsten concentration play a key role in microbial community distribution and relative abundance. The bioleaching efficiency of the enrichment cultures from YTW and QBS is similar. After 15 d,the bioleaching rates of low grade chalcopyrite (0.99%) are both up to 99.5% when using 10 g/L pulp density due to the similar microbial composition of YTW and QBS. Moreover, the leaching efficiencies of enrichment cultures containing multiple bioleaching microorganisms are higher than that of pure culture Acidithiobacillus ferrooxidans.

  13. Catalytic potential of selected metal ions for bioleaching, and potential techno-economic and environmental issues: A critical review.

    Science.gov (United States)

    Pathak, Ashish; Morrison, Liam; Healy, Mark Gerard

    2017-04-01

    Bioleaching is considered to be a low-cost, eco-friendly technique for leaching valuable metals from a variety of matrixes. However, the inherent slow dissolution kinetics and low metal leaching yields have restricted its wider commercial applicability. Recent advancements in bio-hydrometallurgy have suggested that these critical issues can be successfully alleviated through the addition of a catalyst. The catalyzing properties of a variety of metals ions (Ag(+), Hg(++), Bi(+++), Cu(++), Co(++) etc.) during bioleaching have been successfully demonstrated. In this article, the role and mechanisms of these metal species in catalyzing bioleaching from different minerals (chalcopyrite, complex sulfides, etc.) and waste materials (spent batteries) are reviewed, techno-economic and environmental challenges associated with the use of metals ions as catalysts are identified, and future prospectives are discussed. Based on the analysis, it is suggested that metal ion-catalyzed bioleaching will play a key role in the development of future industrial bio-hydrometallurgical processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Single and cooperative bioleaching of sphalerite by two kinds of bacteria——Acidithiobacillus ferriooxidans and Acidithiobacillus thiooxidans

    Institute of Scientific and Technical Information of China (English)

    XIA Le-xian; LIU Jian-she; XIAO Li; ZENG Jia; LI Ban-mei; GENG Mei-mei; QIU Guan-zhou

    2008-01-01

    A cooperative bioleaching (Acidithiobacillus ferriooxidans and Acidithiobacillus thiooxidans) and single bioleaching (Acidithiobacillus ferriooxidans or Acidithiobacillus thiooxidans) of sphalerite were investigated by X-ray diffractometry, energy dispersive spectrography and scanning electron microscopy. The experimental results show that the leaching rate of zinc in the mixed culture is higher than that in pure culture and the sterile control. In these processes, two kinds of bacteria perform different functions and play a cooperative role during leaching of sphalerite. The bioleaching action carried out by Acidithiobacillus ferriooxidans (A. ferriooxidans) is not directly performed through Fe2+ but Fe3+, and its role is to oxidize Fe2+ to Fe 3+ and maintain a high redox potential. Moreover, the addition of an appropriate concentration of ferric iron to the leaching systems is beneficial to zinc dissolution. In the leaching systems without Acidithiobacillus thiooxidans (A. thiooxidans), elemental sulfur layers are formed on mineral surface during the dissolution of zinc and block continuous leaching. Acidithiobacillus thiooxidans, however, eliminate the passivation and cause the bioleaching process to continue in the leaching systems. At the same time, protons from the bacterial oxidization of the elemental sulfur layers also accelerate the leaching of zinc.

  15. Bioleaching of gold, copper and nickel from waste cellular phone PCBs and computer goldfinger motherboards by two Aspergillus nigerstrains.

    Science.gov (United States)

    Madrigal-Arias, Jorge Enrique; Argumedo-Delira, Rosalba; Alarcón, Alejandro; Mendoza-López, Ma Remedios; García-Barradas, Oscar; Cruz-Sánchez, Jesús Samuel; Ferrera-Cerrato, Ronald; Jiménez-Fernández, Maribel

    2015-01-01

    In an effort to develop alternate techniques to recover metals from waste electrical and electronic equipment (WEEE), this research evaluated the bioleaching efficiency of gold (Au), copper (Cu) and nickel (Ni) by two strains of Aspergillus niger in the presence of gold-plated finger integrated circuits found in computer motherboards (GFICMs) and cellular phone printed circuit boards (PCBs). These three metals were analyzed for their commercial value and their diverse applications in the industry. Au-bioleaching ranged from 42 to 1% for Aspergillus niger strain MXPE6; with the combination of Aspergillus niger MXPE6 + Aspergillus niger MX7, the Au-bioleaching was 87 and 28% for PCBs and GFICMs, respectively. In contrast, the bioleaching of Cu by Aspergillus niger MXPE6 was 24 and 5%; using the combination of both strains, the values were 0.2 and 29% for PCBs and GFICMs, respectively. Fungal Ni-leaching was only found for PCBs, but with no significant differences among treatments. Improvement of the metal recovery efficiency by means of fungal metabolism is also discussed.

  16. Bioleaching remediation of heavy metal-contaminated soils using Burkholderia sp. Z-90.

    Science.gov (United States)

    Yang, Zhihui; Zhang, Zhi; Chai, Liyuan; Wang, Yong; Liu, Yi; Xiao, Ruiyang

    2016-01-15

    Bioleaching is an environment-friendly and economical technology to remove heavy metals from contaminated soils. In this study, a biosurfactant-producing strain with capacity of alkaline production was isolated from cafeteria sewer sludge and its capability for removing Zn, Pb, Mn, Cd, Cu, and As was investigated. Phylogenetic analysis using 16S rDNA gene sequences confirmed that the strain belonged to Burkholderia sp. and named as Z-90. The biosurfactant was glycolipid confirmed by thin layer chromatography and Fourier-transform infrared spectroscopy. Z-90 broth was then used for bioleaching remediation of heavy metal-contaminated soils. The removal efficiency was 44.0% for Zn, 32.5% for Pb, 52.2% for Mn, 37.7% for Cd, 24.1% for Cu and 31.6% for As, respectively. Mn, Zn and Cd were more easily removed from soil than Cu, Pb and As, which was attributed to the presence of high acid-soluble fraction of Mn, Zn and Cd and high residual fraction of Cu, Pb and As. The heavy metal removal in soils was contributed to the adhesion of heavy metal-contaminated soil minerals with strain Z-90 and the formation of a metal complex with biosurfactant.

  17. Cr and Ni recovery during bioleaching of dewatered metal-plating sludge using Acidithiobacillus ferrooxidans.

    Science.gov (United States)

    Rastegar, S O; Mousavi, S M; Shojaosadati, S A

    2014-09-01

    This study determined the optimal conditions required to attain maximum metal recovery in the bioleaching process of dewatered metal-plating sludge using Acidithiobacillus ferrooxidans (A. ferrooxidans). Adaptation of this strain was carried up to 1% (w/v) of the sample. Three factors including initial pH, initial Fe(3+) concentration and pulp density were selected as the effective factors and were optimized using a central composite design of response surface methodology. An initial pH of 1, pulp density of 9 g/l and initial Fe(3+) concentration of 1g/l were determined to be optimum values by the statistical models. The highest extractions for Cr and Ni under optimal conditions were 55.6% and 58.2%, respectively. Bioleaching kinetics was investigated using a modified shrinking core model to better understand the mechanism of the leaching reaction. The model predictions indicate that the diffusion step controlled the overall dissolution kinetics and is the rate controlling step.

  18. Comparative assessment of metallurgical recovery of metals from electronic waste with special emphasis on bioleaching.

    Science.gov (United States)

    Priya, Anshu; Hait, Subrata

    2017-01-14

    Waste electrical and electronic equipment (WEEE) or electronic waste (e-waste) is one of the fastest growing waste streams in the urban environment worldwide. The core component of printed circuit board (PCB) in e-waste contains a complex array of metals in rich quantity, some of which are toxic to the environment and all of which are valuable resources. Therefore, the recycling of e-waste is an important aspect not only from the point of waste treatment but also from the recovery of metals for economic growth. Conventional approaches for recovery of metals from e-waste, viz. pyrometallurgical and hydrometallurgical techniques, are rapid and efficient, but cause secondary pollution and economically unviable. Limitations of the conventional techniques have led to a shift towards biometallurgical technique involving microbiological leaching of metals from e-waste in eco-friendly manner. However, optimization of certain biotic and abiotic factors such as microbial species, pH, temperature, nutrients, and aeration rate affect the bioleaching process and can lead to profitable recovery of metals from e-waste. The present review provides a comprehensive assessment on the metallurgical techniques for recovery of metals from e-waste with special emphasis on bioleaching process and the associated factors.

  19. Immobilization of Acidithiobacillus ferrooxidans on Cotton Gauze for the Bioleaching of Waste Printed Circuit Boards.

    Science.gov (United States)

    Nie, Hongyan; Zhu, Nengwu; Cao, Yanlan; Xu, Zhiguo; Wu, Pingxiao

    2015-10-01

    The bioleaching parameters of metal concentrates from waste printed circuit boards by Acidithiobacillus ferrooxidans immobilized on cotton gauze in a two-step reactor were investigated in this study. The results indicated that an average ferrous iron oxidation rate of 0.54 g/(L·h) and a ferrous iron oxidation ratio of 96.90 % were obtained after 12 h at aeration rate of 1 L/min in bio-oxidation reactor. After 96 h, the highest leaching efficiency of copper reached 91.68 % under the conditions of the content of the metal powder 12 g/L, the retention time 6 h, and the aeration rate 1 L/min. The bioleaching efficiency of copper could be above 91.12 % under repeated continuous batch operation. Meanwhile, 95.32 % of zinc, 90.32 % of magnesium, 86.31 % of aluminum, and 59.07 % of nickel were extracted after 96 h. All the findings suggested that the recovery of metal concentrates from waste printed circuit boards via immobilization of A. ferrooxidans on cotton gauze was feasible.

  20. An experimental study of pyrite bio-leaching as a way to control spontaneous combustion

    Institute of Scientific and Technical Information of China (English)

    Yin Shenghua; Wu Aixiang; Liu Jinzhi; Huang Mingqing; Wang Hongjiang

    2011-01-01

    Bio-leaching of pyrite by native strains of acidophilic bacteria was examined by laboratory scale tests.Three groups of batch trials in agitated flasks and three continuous column leaching tests were performed.The leaching ability and efficiency of native bacteria was greatly improved by adaptation of the bacteria to the test conditions.These cultivated bacteria were then used for the leaching process.The changes in solution pH,Eh,Fe2+ concentration,and sulfate ion concentration were monitored throughout the tests.A portion of the pyritic sulfur is transformed into soluble sulfate ion.The desulfurization ratio of 42.6% was obtained in a flask shaking test and a ratio of 39.4% was obtained during column leaching.A weight gain test was performed on leached and unleached samples by exposing the samples to humid air for several days.A smaller weight gain of the bio-leached samples indicates that removing sulfur from the sulphide ore helps reduce its oxidation rate and the potential for spontaneous combustion.

  1. An effective method of DNA extraction for bioleaching bacteria from acid mine drainage.

    Science.gov (United States)

    Zeng, Leping; Huang, Jufang; Zhang, Yanfei; Qiu, Guanzhou; Tong, Jianbin; Chen, Dan; Zhou, Jin; Luo, Xuegang

    2008-07-01

    An effective and versatile method for microorganism lysis and direct extraction of DNA from bioleaching bacteria was developed using pure cultures and an acid mine drainage (AMD) sediment sample. In the described method, microorganisms are treated at three different incubation temperatures: boiling water incubation for 6-10 min, followed by 60 +/- 5 degrees C for 30 min, then 72 degrees C for 30 min. The extracted DNA is purified using a phenol/chloroform/alcohol mixture and precipitated in absolute alcohol. The 16S ribosomal RNA (rRNA) and gyrB genes of the pure cultures were amplified using the polymerase chain reaction (PCR) and differentiated using repetitive intergenic DNA sequences amplification (Rep-PCR). For the AMD sediment sample, the 16S rRNA and gyrB genes of the amplicons were digested with Hin6I and MspI, and the restriction fragment length polymorphism analysis patterns were used as a fingerprint to discern community diversity. The results indicated that this method is a versatile, reproducible, effective, and rapid technique for routine DNA extraction from bioleaching bacteria. The low cost of this method also makes it attractive for large-scale studies.

  2. Improved chalcopyrite bioleaching by Acidithiobacillus sp. via direct step-wise regulation of microbial community structure.

    Science.gov (United States)

    Feng, Shoushuai; Yang, Hailin; Wang, Wu

    2015-09-01

    A direct step-wise regulation strategy of microbial community structure was developed for improving chalcopyrite bioleaching by Acidithiobacillus sp. Specially, the initial microbial proportion between Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans was controlled at 3:1 with additional 2 g/L Fe(2+) for faster initiating iron metabolism. A. thiooxidans biomass was fed via a step-wise strategy (8-12th d) with the microbial proportion 1:1 for balancing community structure and promoting sulfur metabolism in the stationary phase. A. thiooxidans proportion was further improved via another step-wise feeding strategy (14-18th d) with the microbial proportion 1:2 for enhancing sulfur metabolism and weakening jarosite passivation in the later phase. With the community structure-shift control strategy, biochemical reaction was directly regulated for creating a better balance in different phases. Moreover, the final copper ion was increased from 57.1 to 93.2 mg/L, with the productivity 2.33 mg/(Ld). The novel strategy may be valuable in optimization of similar bioleaching process.

  3. A new genome of Acidithiobacillus thiooxidans provides insights into adaptation to a bioleaching environment.

    Science.gov (United States)

    Travisany, Dante; Cortés, María Paz; Latorre, Mauricio; Di Genova, Alex; Budinich, Marko; Bobadilla-Fazzini, Roberto A; Parada, Pilar; González, Mauricio; Maass, Alejandro

    2014-11-01

    Acidithiobacillus thiooxidans is a sulfur oxidizing acidophilic bacterium found in many sulfur-rich environments. It is particularly interesting due to its role in bioleaching of sulphide minerals. In this work, we report the genome sequence of At. thiooxidans Licanantay, the first strain from a copper mine to be sequenced and currently used in bioleaching industrial processes. Through comparative genomic analysis with two other At. thiooxidans non-metal mining strains (ATCC 19377 and A01) we determined that these strains share a large core genome of 2109 coding sequences and a high average nucleotide identity over 98%. Nevertheless, the presence of 841 strain-specific genes (absent in other At. thiooxidans strains) suggests a particular adaptation of Licanantay to its specific biomining environment. Among this group, we highlight genes encoding for proteins involved in heavy metal tolerance, mineral cell attachment and cysteine biosynthesis. Several of these genes were located near genetic motility genes (e.g. transposases and integrases) in genomic regions of over 10 kbp absent in the other strains, suggesting the presence of genomic islands in the Licanantay genome probably produced by horizontal gene transfer in mining environments.

  4. Role of ore mineralogy in optimizing conditions for bioleaching low-grade complex sulphide ores

    Institute of Scientific and Technical Information of China (English)

    P. A. OLUBAMBI; S. NDLOVU; J. H. POTGIETER; J. O. BORODE

    2008-01-01

    The role that ore mineralogy plays in understanding and optimizing the conditions favouring the bioleaching of complex sulphide ore containing high amounts of siderite was studied using mixed cultures of mesophilic bacteria, with emphasis on zinc,lead and copper recoveries. The influencing parameters investigated include particle size, stirring speed, volume of inoculum, pulp density, and pH. The results show that the mixed mesophilic cultures can extract about two and a half times the amount of zinc than copper over an equivalent period of time. The highest zinc and copper recoveries of 89.2% and 36.4% respectively are obtained at particle size of 75 μm, stirring speed of 150 r/min, pulp density of 10% (w/v), 12% (v/v) inoculum concentration, and a pH of 1.6. Variations in elemental composition within different particle sizes resulting from the mineralogy of the ore account for the bioleaching behaviour at varying particle sizes. The dissolution at varying pulp density, volume of inoculum, solution pH and the low solution potential observed are also influenced by ore mineralogy.

  5. Isolation and identification of moderately thermophilic acidophilic iron-oxidizing bacterium and its bioleaching characterization

    Institute of Scientific and Technical Information of China (English)

    ZENG Wei-min; WU Chang-bin; ZHANG Ru-bing; HU Pei-lei; QIU Guan-zhou; GU Guo-hua; ZHOU Hong-bo

    2009-01-01

    A moderately thermophilic acidophilic iron-oxidizing bacterium ZW-1 was isolated from Dexing mine, Jiangxi Province, China. The morphological, biochemical and physiological characteristics, 16S rRNA sequence and bioleaching characterization of strain ZW-1 were studied. The optimum growth temperature is 48 ℃, and the optimum initial pH is 1.9. The strain can grow autotrophically by using ferrous iron or elemental sulfur as sole energy sources. The strain is also able to grow heterotrophically by using peptone and yeast extract powder, but not glucose. The cell density of strain ZW-1 can reach up to 1.02×108 /mL with addition of 0.4 g/L peptone. A phylogenetic tree was constructed by comparing with the published 16S rRNA sequences of the relative bacteria species. In the phylogenetic tree, strain ZW-1 is closely relative to Sulfobacilus acidophilus with more than 99% sequence similarity. The results of bioleaching experiments indicate that the strain could oxidize Fe2+ efficiently, and the maximum oxidizing rate is 0.295 g/(L·h). It could tolerate high concentration of Fe3+ and Cu2+ (35 g/L and 25 g/L, respectively). After 20 d, 44.6% of copper is extracted from chalcopyrite by using strain ZW-1 as inocula.

  6. Catalytic effect of activated carbon on bioleaching of low-grade primary copper sulfide ores

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The catalytic effect of activated carbon on the bioleaching of low-grade primary copper sulfide ores using mixture of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans was investigated. The results show that the addition of activated carbon can greatly accelerate the rate and efficiency of copper dissolution from low-grade primary copper sulfide ores. The solution with the concentration of 3.0 g/L activated carbon is most beneficial to the dissolution of copper. The resting time of the mixture of activated carbon and ores has an impact on the bioleaching of low-grade primary copper sulfide ores. The 2 d resting time is most favorable to the dissolution of copper. The enhanced dissolution rate and efficiency of copper can be attributed to the galvanic interaction between activated carbon and chalcopyrite. The addition of activated carbon obviously depresses the dissolution of iron and the bacterial oxidation of ferrous ions in solution. The lower redox potentials are more favorable to the copper dissolution than the higher potentials for low-grade primary copper sulfide ores in the presence of activated carbon.

  7. Bioleaching mechanism of heavy metals in the mixture of contaminated soil and slag by using indigenous Penicillium chrysogenum strain F1

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Xinhui [College of Metallurgical Science and Engineering, Central South University (China); College of Packing and Material Engineering, Hunan University of Technology (China); Chai, Liyuan, E-mail: liyuan.chai@yahoo.com [College of Metallurgical Science and Engineering, Central South University (China); Chinese National Engineering Research Center for Control and Treatment of Heavy Metal Pollution (China); Yang, Zhihui; Tang, Chongjian [College of Metallurgical Science and Engineering, Central South University (China); Chinese National Engineering Research Center for Control and Treatment of Heavy Metal Pollution (China); Wang, Yangyang; Shi, Yan [College of Metallurgical Science and Engineering, Central South University (China)

    2013-03-15

    Highlights: ► We use Penicillium chrysogenum growth experiment data to fit Gompertz model. ► We compared the removal efficiencies of bioleaching with chemical bioleaching. ► The morphology and resistant mechanism of P. chrysogenum were preliminary examined. ► Glucose oxidase activity produced by P. chrysogenum during bioleaching was studied. -- Abstract: The ability and bioleaching mechanism of heavy metals by Penicillium chrysogenum in soils contaminated with smelting slag were examined in this study. Batch experiments were performed to investigate the growth kinetics of P. chrysogenum, organic acids production and to compare the removal efficiencies of heavy metals between bioleaching with P. chrysogenum and chemical organic acids. The results showed that the bioleaching had higher removals than chemical leaching, and the removal percentages of Cd, Cu, Pb, Zn, Mn and Cr reached up to 74%, 59%, 24%, 55%, 57% and 25%, respectively. Removal efficiencies of heavy metals (15.41 mg/50 mL) by bioleaching were higher than chemical leaching with 0.5% of citric acid (15.15 mg/50 mL), oxalic acid (8.46 mg/50 mL), malic acid (11.35 mg/50 mL) and succinic acid (10.85 mg/50 mL). The results of transmission electron microscope (TEM) showed that no damage was obviously observed on the surface of the living cell except for thinner cell wall, discontinuous plasma membrane, compartmentalized lumen and concentrated cytoplasm during bioleaching process. The activity of extracellular glucose oxidase (GOD) produced by P. chrysogenum is influenced severely by the multi-heavy metal ions. The result implied that P. chrysogenum can be used to remove heavy metals from polluted soil and smeltery slag.

  8. Use of large pieces of printed circuit boards for bioleaching to avoid 'precipitate contamination problem' and to simplify overall metal recovery.

    Science.gov (United States)

    Adhapure, N N; Dhakephalkar, P K; Dhakephalkar, A P; Tembhurkar, V R; Rajgure, A V; Deshmukh, A M

    2014-01-01

    Very recently bioleaching has been used for removing metals from electronic waste. Most of the research has been targeted to using pulverized PCBs for bioleaching where precipitate formed during bioleaching contaminates the pulverized PCB sample and making the overall metal recovery process more complicated. In addition to that, such mixing of pulverized sample with precipitate also creates problems for the final separation of non metallic fraction of PCB sample. In the present investigation we attempted the use of large pieces of printed circuit boards instead of pulverized sample for removal of metals. Use of large pieces of PCBs for bioleaching was restricted due to the chemical coating present on PCBs, the problem has been solved by chemical treatment of PCBs prior to bioleaching. In short,•Large pieces of PCB can be used for bioleaching instead of pulverized PCB sample.•Metallic portion on PCBs can be made accessible to bacteria with prior chemical treatment of PCBs.•Complete metal removal obtained on PCB pieces of size 4 cm × 2.5 cm with the exception of solder traces. The final metal free PCBs (non metallic) can be easily recycled and in this way the overall recycling process (metallic and non metallic part) of PCBs becomes simple.

  9. Use of large pieces of printed circuit boards for bioleaching to avoid ‘precipitate contamination problem’ and to simplify overall metal recovery

    Science.gov (United States)

    Adhapure, N.N.; Dhakephalkar, P.K.; Dhakephalkar, A.P.; Tembhurkar, V.R.; Rajgure, A.V.; Deshmukh, A.M.

    2014-01-01

    Very recently bioleaching has been used for removing metals from electronic waste. Most of the research has been targeted to using pulverized PCBs for bioleaching where precipitate formed during bioleaching contaminates the pulverized PCB sample and making the overall metal recovery process more complicated. In addition to that, such mixing of pulverized sample with precipitate also creates problems for the final separation of non metallic fraction of PCB sample. In the present investigation we attempted the use of large pieces of printed circuit boards instead of pulverized sample for removal of metals. Use of large pieces of PCBs for bioleaching was restricted due to the chemical coating present on PCBs, the problem has been solved by chemical treatment of PCBs prior to bioleaching. In short,•Large pieces of PCB can be used for bioleaching instead of pulverized PCB sample.•Metallic portion on PCBs can be made accessible to bacteria with prior chemical treatment of PCBs.•Complete metal removal obtained on PCB pieces of size 4 cm × 2.5 cm with the exception of solder traces. The final metal free PCBs (non metallic) can be easily recycled and in this way the overall recycling process (metallic and non metallic part) of PCBs becomes simple. PMID:26150951

  10. Simulation of Bioleaching Heat Effects for Enhancement of Copper Recovery from Sarcheshmeh Chalcopyrite

    Science.gov (United States)

    Mahmoudian, Ali Reza; Sadrnezhaad, S. K.; Manafi, Zahra

    2014-08-01

    A heat-transfer model was formulated to determine the distribution of temperature within a bioheap of chalcopyrite of Sarcheshmeh copper mine. Bioleaching employs mixed mesophilic and thermophilic microbes for Cu extraction. Thermophiles are better than mesophiles to dissolve CuFeS2. The solution irrigation and aeration rates were taken into account as the main operational factors. The model was validated by comparing the temperature profiles of test columns with those of bioheap. The model was used to find the optimal ratio of irrigation to aeration. It was found that when the solution was fed at a flow rate of 5 kg/m2 h and air was blown at a flow rate of 7.5 kg/m2 h, the transition from a mesophilic to thermophilic state inside the heap was possible. In this situation, the maximum temperature rise inside the heap was about 332 K (59 °C) after 60 days.

  11. Microbial community succession mechanism coupling with adaptive evolution of adsorption performance in chalcopyrite bioleaching.

    Science.gov (United States)

    Feng, Shoushuai; Yang, Hailin; Wang, Wu

    2015-09-01

    The community succession mechanism of Acidithiobacillus sp. coupling with adaptive evolution of adsorption performance were systematically investigated. Specifically, the μmax of attached and free cells was increased and peak time was moved ahead, indicating both cell growth of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans was promoted. In the mixed strains system, the domination courses of A. thiooxidans was dramatically shortened from 22th day to 15th day, although community structure finally approached to the normal system. Compared to A. ferrooxidans, more positive effects of adaptive evolution on cell growth of A. thiooxidans were shown in either single or mixed strains system. Moreover, higher concentrations of sulfate and ferric ions indicated that both sulfur and iron metabolism was enhanced, especially of A. thiooxidans. Consistently, copper ion production was improved from 65.5 to 88.5 mg/L. This new adaptive evolution and community succession mechanism may be useful for guiding similar bioleaching processes.

  12. The method of contact angle measurements and estimation of work of adhesion in bioleaching of metals

    Directory of Open Access Journals (Sweden)

    Matlakowska Renata

    1999-01-01

    Full Text Available In this paper, we present our method for the measurement of contact angles on the surface of minerals during the bioleaching process because the standard deviation obtained in our measurements achieved unexpectedly low error. Construction of a goniometer connected with a specially prepared computer program allowed us to repeat measurements several times over a short time course, yielding excellent results. After defining points on the outline of the image of a drop and its baseline as well of the first approximation of the outline of the drop, an iterative process is initiated that is aimed at fitting the model of the drop and baseline. In turn, after defining the medium for which measurements were made, the work of adhesion is determined according to Young-Dupré equation. Calculations were made with the use of two methods named the L-M and L-Q methods.

  13. Quantifying adhesion of acidophilic bioleaching bacteria to silica and pyrite by atomic force microscopy with a bacterial probe.

    Science.gov (United States)

    Diao, Mengxue; Taran, Elena; Mahler, Stephen; Nguyen, Tuan A H; Nguyen, Anh V

    2014-03-01

    The adhesion of acidophilic bacteria to mineral surfaces is an important phenomenon in bioleaching processes. In this study, functionalized colloidal probes covered by bioleaching bacterial cells (Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans) were developed and used to sense specific adhesion forces to a silica surface and a pyrite surface in various solutions. Experimentally, recorded retraction curves of A. thiooxidans revealed sawtooth features that were in good agreement with the wormlike chain model, while that of L. ferrooxidans exhibited stair-step separation. The magnitudes of adhesion forces and snap-off distances were strongly influenced by the ionic strength and pH. Macroscopic surface properties including hydrophobicity and surface potential for bacterial cells and substrata were measured by a sessile drop method and microelectrophoresis. The ATR-FTIR spectra indicated the presence of different types of biopolymers on two strains of bacteria.

  14. Integrated bioleaching of copper metal from waste printed circuit board-a comprehensive review of approaches and challenges.

    Science.gov (United States)

    Awasthi, Abhishek Kumar; Zeng, Xianlai; Li, Jinhui

    2016-11-01

    Waste electrical and electronic equipment (e-waste) is the most rapidly growing waste stream in the world, and the majority of the residues are openly disposed of in developing countries. Waste printed circuit boards (WPCBs) make up the major portion of e-waste, and their informal recycling can cause environmental pollution and health risks. Furthermore, the conventional disposal and recycling techniques-mechanical treatments used to recover valuable metals, including copper-are not sustainable in the long term. Chemical leaching is rapid and efficient but causes secondary pollution. Bioleaching is a promising approach, eco-friendly and economically feasible, but it is slower process. This review considers the recycling potential of microbes and suggests an integrated bioleaching approach for Cu extraction and recovery from WPCBs. The proposed recycling system should be more effective, efficient and both technically and economically feasible.

  15. Thin-layer heap bioleaching of copper flotation tailings containing high levels of fine grains and microbial community succession analysis

    Science.gov (United States)

    Hao, Xiao-dong; Liang, Yi-li; Yin, Hua-qun; Liu, Hong-wei; Zeng, Wei-min; Liu, Xue-duan

    2017-04-01

    Thin-layer heap bioleaching of copper flotation tailings containing high levels of fine grains was carried out by mixed cultures on a small scale over a period of 210 d. Lump ores as a framework were loaded at the bottom of the ore heap. The overall copper leaching rates of tailings and lump ores were 57.10wt% and 65.52wt%, respectively. The dynamic shifts of microbial community structures about attached microorganisms were determined using the Illumina MiSeq sequencing platform based on 16S rRNA amplification strategy. The results indicated that chemolithotrophic genera Acidithiobacillus and Leptospirillum were always detected and dominated the microbial community in the initial and middle stages of the heap bioleaching process; both genera might be responsible for improving the copper extraction. However, Thermogymnomonas and Ferroplasma increased gradually in the final stage. Moreover, the effects of various physicochemical parameters and microbial community shifts on the leaching efficiency were further investigated and these associations provided some important clues for facilitating the effective application of bioleaching.

  16. A copper-catalyzed bioleaching process for enhancement of cobalt dissolution from spent lithium-ion batteries.

    Science.gov (United States)

    Zeng, Guisheng; Deng, Xiaorong; Luo, Shenglian; Luo, Xubiao; Zou, Jianping

    2012-01-15

    A copper-catalyzed bioleaching process was developed to recycle cobalt from spent lithium-ion batteries (mainly LiCoO(2)) in this paper. The influence of copper ions on bioleaching of LiCoO(2) by Acidithiobacillus ferrooxidans (A.f) was investigated. It was shown that almost all cobalt (99.9%) went into solution after being bioleached for 6 days in the presence of 0.75 g/L copper ions, while only 43.1% of cobalt dissolution was obtained after 10 days without copper ions. EDX, XRD and SEM analyses additionally confirmed that the cobalt dissolution from spent lithium-ion batteries could be improved in the presence of copper ions. The catalytic mechanism was investigated to explain the enhancement of cobalt dissolution by copper ions, in which LiCoO(2) underwent a cationic interchange reaction with copper ions to form CuCo(2)O(4) on the surface of the sample, which could be easily dissolved by Fe(3+).

  17. Bioleaching of chalcopyrite concentrate using Leptospirillum ferriphilum, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans in a continuous bubble column reactor.

    Science.gov (United States)

    Xia, Lexian; Yin, Chu; Dai, Songlin; Qiu, Guanzhou; Chen, Xinhua; Liu, Jianshe

    2010-03-01

    To estimate the bioleaching performance of chalcopyrite for various hydraulic residence times (HRTs), laboratory-scale bioleaching of chalcopyrite concentrate was carried out in a continuous bubble column reactor with three different HRTs of 120, 80 and 40 h, respectively. An extraction rate and ratio of 0.578 g Cu l(-1) h(-1) and 39.7%, respectively, were achieved for an HRT of 80 h at a solids concentration of 10% (w/v). Lower bioleaching performances than this were obtained for a longer HRT of 120 h and a shorter HRT of 40 h. In addition, there was obvious competition between Leptospirillum ferriphilum and Acidithiobacillus ferrooxidans to oxidize ferrous iron, causing large compositional differences between the microbial communities obtained for the different HRTs. Leptospirillum ferriphilum and Acidithiobacillus thiooxidans were found to be the dominant microbes for the longer HRT (120 h). Acidithiobacillus ferrooxidans became the dominant species when the HRT was decreased. The proportion of Acidithiobacillus thiooxidans was comparatively constant in the microbial community throughout the three process stages.

  18. Comparative genomic analysis of carbon and nitrogen assimilation mechanisms in three indigenous bioleaching bacteria: predictions and validations

    Directory of Open Access Journals (Sweden)

    Ehrenfeld Nicole

    2008-12-01

    Full Text Available Abstract Background Carbon and nitrogen fixation are essential pathways for autotrophic bacteria living in extreme environments. These bacteria can use carbon dioxide directly from the air as their sole carbon source and can use different sources of nitrogen such as ammonia, nitrate, nitrite, or even nitrogen from the air. To have a better understanding of how these processes occur and to determine how we can make them more efficient, a comparative genomic analysis of three bioleaching bacteria isolated from mine sites in Chile was performed. This study demonstrated that there are important differences in the carbon dioxide and nitrogen fixation mechanisms among bioleaching bacteria that coexist in mining environments. Results In this study, we probed that both Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans incorporate CO2 via the Calvin-Benson-Bassham cycle; however, the former bacterium has two copies of the Rubisco type I gene whereas the latter has only one copy. In contrast, we demonstrated that Leptospirillum ferriphilum utilizes the reductive tricarboxylic acid cycle for carbon fixation. Although all the species analyzed in our study can incorporate ammonia by an ammonia transporter, we demonstrated that Acidithiobacillus thiooxidans could also assimilate nitrate and nitrite but only Acidithiobacillus ferrooxidans could fix nitrogen directly from the air. Conclusion The current study utilized genomic and molecular evidence to verify carbon and nitrogen fixation mechanisms for three bioleaching bacteria and provided an analysis of the potential regulatory pathways and functional networks that control carbon and nitrogen fixation in these microorganisms.

  19. Systematic simulation of a tubular recycle reactor on the basis of pilot plant experiments

    Energy Technology Data Exchange (ETDEWEB)

    Paar, H.; Narodoslawsky, M.; Moser, A. (Technische Univ., Graz (Austria). Inst. fuer Biotechnologie, Mikrobiologie und Abfalltechnologie)

    1990-10-10

    Systematic simulatiom may decisively help in development and optimization of bioprocesses. By applying simulation techniques, optimal use can be made of experimental data, decreasing development costs and increasing the accuracy in predicting the behavior of an industrial scale plant. The procedure of the dialogue between simulation and experimental efforts will be exemplified in a case study. Alcoholic fermentation of glucose by zymomonas mobilis bacteria in a gasified turbular recycle reactor was studied first by systematic simulation, using a computer model based solely on literature data. On the base of the results of this simulation, a 0.013 m{sup 3} pilot plant reactor was constructed. The pilot plant experiments, too, were based on the results of the systematic simulation. Simulated and experimental data were well in agreement. The pilot plant experiments reiterated the trends and limits of the process as shown by the simulation results. Data from the pilot plant runs were then used to improve the simulation model. This improved model was subsequently used to simulate the performances of an industrial scale plant. The results of this simulation are presented. They show that the alcohol fermentation in a tubular recycle reactor is potentially advantageous to other reactor configurations, especially to continuous stirred tanks. (orig.).

  20. Metallic ions catalysis for improving bioleaching yield of Zn and Mn from spent Zn-Mn batteries at high pulp density of 10.

    Science.gov (United States)

    Niu, Zhirui; Huang, Qifei; Wang, Jia; Yang, Yiran; Xin, Baoping; Chen, Shi

    2015-11-15

    Bioleaching of spent batteries was often conducted at pulp density of 1.0% or lower. In this work, metallic ions catalytic bioleaching was used for release Zn and Mn from spent ZMBs at 10% of pulp density. The results showed only Cu(2+) improved mobilization of Zn and Mn from the spent batteries among tested four metallic ions. When Cu(2+) content increased from 0 to 0.8 g/L, the maximum release efficiency elevated from 47.7% to 62.5% for Zn and from 30.9% to 62.4% for Mn, respectively. The Cu(2+) catalysis boosted bioleaching of resistant hetaerolite through forming a possible intermediate CuMn2O4 which was subject to be attacked by Fe(3+) based on a cycle of Fe(3+)/Fe(2+). However, poor growth of cells, formation of KFe3(SO4)2(OH)6 and its possible blockage between cells and energy matters destroyed the cycle of Fe(3+)/Fe(2+), stopping bioleaching of hetaerolite. The chemical reaction controlled model fitted best for describing Cu(2+) catalytic bioleaching of spent ZMBs.

  1. Optimization of staged bioleaching of low-grade chalcopyrite ore in the presence and absence of chloride in the irrigating lixiviant: ANFIS simulation.

    Science.gov (United States)

    Vakylabad, Ali Behrad; Schaffie, Mahin; Naseri, Ali; Ranjbar, Mohammad; Manafi, Zahra

    2016-07-01

    In this investigation, copper was bioleached from a low-grade chalcopyrite ore using a chloride-containing lixiviant. In this regard, firstly, the composition of the bacterial culture media was designed to control the cost in commercial application. The bacterial culture used in this process was acclimated to the presence of chloride in the lixiviant. Practically speaking, the modified culture helped the bio-heap-leaching system operate in the chloridic media. Compared to the copper recovery from the low-grade chalcopyrite by bioleaching in the absence of chloride, bioleaching in the presence of chloride resulted in improved copper recovery. The composition of the lixiviant used in this study was a modification with respect to the basal salts in 9 K medium to optimize the leaching process. When leaching the ore in columns, 76.81 % Cu (based on solid residues of bioleaching operation) was recovered by staged leaching with lixiviant containing 34.22 mM NaCl. The quantitative findings were supported by SEM/EDS observations, X-ray elemental mapping, and mineralogical analysis of the ore before and after leaching. Finally, Adaptive neuro-fuzzy inference system (ANFIS) was used to simulate the operational parameters affecting the bioleaching operation in chloride-sulfate system.

  2. Bioleaching mechanism of heavy metals in the mixture of contaminated soil and slag by using indigenous Penicillium chrysogenum strain F1.

    Science.gov (United States)

    Deng, Xinhui; Chai, Liyuan; Yang, Zhihui; Tang, Chongjian; Wang, Yangyang; Shi, Yan

    2013-03-15

    The ability and bioleaching mechanism of heavy metals by Penicillium chrysogenum in soils contaminated with smelting slag were examined in this study. Batch experiments were performed to investigate the growth kinetics of P. chrysogenum, organic acids production and to compare the removal efficiencies of heavy metals between bioleaching with P. chrysogenum and chemical organic acids. The results showed that the bioleaching had higher removals than chemical leaching, and the removal percentages of Cd, Cu, Pb, Zn, Mn and Cr reached up to 74%, 59%, 24%, 55%, 57% and 25%, respectively. Removal efficiencies of heavy metals (15.41 mg/50 mL) by bioleaching were higher than chemical leaching with 0.5% of citric acid (15.15 mg/50 mL), oxalic acid (8.46 mg/50 mL), malic acid (11.35 mg/50 mL) and succinic acid (10.85 mg/50 mL). The results of transmission electron microscope (TEM) showed that no damage was obviously observed on the surface of the living cell except for thinner cell wall, discontinuous plasma membrane, compartmentalized lumen and concentrated cytoplasm during bioleaching process. The activity of extracellular glucose oxidase (GOD) produced by P. chrysogenum is influenced severely by the multi-heavy metal ions. The result implied that P. chrysogenum can be used to remove heavy metals from polluted soil and smeltery slag.

  3. 污泥生物淋滤过程中Cd及Pb形态变化研究%Research on morphological changes of Cd and Pb in sludge bioleaching process

    Institute of Scientific and Technical Information of China (English)

    原武斌

    2011-01-01

    The paper undertakes the sequencing batch experimental research on the bioleaching over the sludge of the Sewage Treatment Plant of Taiyuan, adopts 5% inoculation amount and substrate concentration 4 g/L elemental sulfur as the craft parameter, uses the sequence extraction method to test the interchange between heavy metals in the bioleaching, analyzes the leaching mechanism and leaching ability according to the morphological changes of the heavy metals before and after the leaching, and proves by the results that Cd can be leached by the indirect mechanism, and the leached things of Pb are completed by the mutual effect of the direct and indirect mechanisms , so the result of the research is positive to forecast the agricultural environment risks of the sludge.%对太原市污水处理厂的污泥进行了生物淋滤序批实验研究,采用5%接种量和底物浓度4g/L单质硫为工艺参数,采用顺序浸提法测定了生物沥滤中重金属形态之间的转化,通过淋滤前后重金属形态变化分析了其沥滤机制及浸出能力。结果表明,cd是通过间接机制沥出,Pb的沥出主要是由直接机制和间接机制的共同作用完成的。研究结果对预测污泥农用的环境风险有积极意义。

  4. Effects of plant roots on the hydraulic performance during the clogging process in mesocosm vertical flow constructed wetlands.

    Science.gov (United States)

    Hua, G F; Zhao, Z W; Kong, J; Guo, R; Zeng, Y T; Zhao, L F; Zhu, Q D

    2014-11-01

    The aim of this study was to evaluate the effects of plant roots (Typha angustifolia roots) on the hydraulic performance during the clogging process from the perspective of time and space distributions in mesocosm vertical flow-constructed wetlands with coarse sand matrix. For this purpose, a pair of lab-scale experiments was conducted to compare planted and unplanted systems by measuring the effective porosity and hydraulic conductivity of the substrate within different operation periods. Furthermore, the flow pattern of the clogging process in the planted and unplanted wetland systems were evaluated by their hydraulic performance (e.g., mean residence time, short circuiting, volumetric efficiency, number of continuously stirred tank reactors, and hydraulic efficiency factor) in salt tracer experiments. The results showed that the flow conditions would change in different clogging stages, which indicated that plants played different roles related to time and space. In the early clogging stages, plant roots restricted the flow of water, while in the middle and later clogging stages, especially the later stage, growing roots opened new pore spaces in the substrate. The roots played an important role in affecting the hydraulic performance in the upper layer (0-30 cm) where the sand matrix had a larger root volume fraction. Finally, the causes of the controversy over plant roots' effects on clogging were discussed. The results helped further understand the effects of plant roots on hydraulic performance during the clogging process.

  5. Bioleaching of Zn, Ni and Fe from contaminated sediments of water reservoir Ružín I with using heterotrophic bacterial strains

    Directory of Open Access Journals (Sweden)

    Katarína Jablonovská

    2012-12-01

    Full Text Available This study investigates the bioleaching of the zinc polluted sediment from water reservoir Ružín I using heterotrophic bacterialstrains ubiquitous in sediment environment. The effect of bacterial activity, pH, iron solubilization and precipitation and bioleachingmedium were evaluated. The pH value controls the bacterial activity during the leaching process. Addition of glucose to the bioleachingmedium accelerated the bioleaching rate. The results indicates, that the leachibility of zinc depend on the geochemical formsand surface interaction between metal and sediment fraction. Sequential chemical extraction confirm, that Zn was predominantly boundto the iron-manganese oxides.

  6. Bioinformatic Prediction of Gene Functions Regulated by Quorum Sensing in the Bioleaching Bacterium Acidithiobacillus ferrooxidans

    Directory of Open Access Journals (Sweden)

    Alvaro Banderas

    2013-08-01

    Full Text Available The biomining bacterium Acidithiobacillus ferrooxidans oxidizes sulfide ores and promotes metal solubilization. The efficiency of this process depends on the attachment of cells to surfaces, a process regulated by quorum sensing (QS cell-to-cell signalling in many Gram-negative bacteria. At. ferrooxidans has a functional QS system and the presence of AHLs enhances its attachment to pyrite. However, direct targets of the QS transcription factor AfeR remain unknown. In this study, a bioinformatic approach was used to infer possible AfeR direct targets based on the particular palindromic features of the AfeR binding site. A set of Hidden Markov Models designed to maintain palindromic regions and vary non-palindromic regions was used to screen for putative binding sites. By annotating the context of each predicted binding site (PBS, we classified them according to their positional coherence relative to other putative genomic structures such as start codons, RNA polymerase promoter elements and intergenic regions. We further used the Multiple EM for Motif Elicitation algorithm (MEME to further filter out low homology PBSs. In summary, 75 target-genes were identified, 34 of which have a higher confidence level. Among the identified genes, we found afeR itself, zwf, genes encoding glycosyltransferase activities, metallo-beta lactamases, and active transport-related proteins. Glycosyltransferases and Zwf (Glucose 6-phosphate-1-dehydrogenase might be directly involved in polysaccharide biosynthesis and attachment to minerals by At. ferrooxidans cells during the bioleaching process.

  7. Heavy metal bioleaching and sludge stabilization in a single-stage reactor using indigenous acidophilic heterotrophs.

    Science.gov (United States)

    Mehrotra, Akanksha; Sreekrishnan, T R

    2017-01-10

    Simultaneous sludge digestion and metal leaching (SSDML) have been reported at mesophilic temperature. It is generally perceived that while sludge stabilization is effected by heterotrophs at neutral pH, metal bioleaching is done by acidophilic autotrophs. However, little information is available on the microbial communities involved in the process. This study carried out SSDML in a single-stage reactor using sludge indigenous microorganisms and looked at the bacterial communities responsible for the process. Volatile suspended solids were reduced by more than 40%. The concentration of zinc, copper, chromium, cadmium and nickel decreased by more than 45% in the dry sludge. Acidophilic species of Alicyclobacillus genus were the dominant heterotrophs. A few heterotrophic bacteria were detected which can oxidize iron (Alicyclobacillus ferrooxydans, Alicyclobacillus ferripilum and Ferrimicrobium acidiphilum). Acidithiobacillus ferrooxidans (autotroph) was responsible for the oxidation of both iron and sulfur which lead to a change in the pH from neutral to acidic. The presence of acidophilic heterotrophs, which can oxidize either iron or sulfur, enhanced the efficiency of SSDML process with respect to sludge stabilization and metal leaching. This study shows that it is possible to carry out the SSDML in a single-stage reactor with indigenous microorganisms.

  8. Solvent extraction of copper and zinc from bioleaching solutions with LIX984 and D2EHPA

    Institute of Scientific and Technical Information of China (English)

    LAN Zhuo-yue; HU Yue-hua; LIU Jian-she; WANG Jun

    2005-01-01

    The solvent extraction of copper and zinc from the bioleaching solutions of low-grade sulfide ores with LIX984 and D2EHPA was investigated. The influences of extractant content, aqueous pH value, phase ratio and equilibration time on metals extraction were studied. The results show that LIX984 has a higher selectivity for copper than for iron, zinc and other metals, and has the copper extraction rate above 97%,while the zinc and iron extraction rate is less than 1.6% respectively. Zinc extraction is carried out following the copper extraction from the raffinate. The zinc extraction with di(2-ethylhexyl) phosphoric acid(D2EHPA) is low due to its poor cation exchange. A sodium salt of D2EHPA is used and the zinc extraction rate is enhanced to above 98%. Though iron (Ⅲ) is strongly extracted before the extraction of zinc by D2EHPA, it is difficult to strip iron from the organic phase by sulfuric acid. The zinc stripping rate is above 99% with 100 g/L sulfuric acid, while that of iron is 0.16%. Hence, the separation of zinc from iron can be achieved by the selective stripping.

  9. The Confluence of Heavy Metal Biooxidation and Heavy Metal Resistance: Implications for Bioleaching by Extreme Thermoacidophiles

    Directory of Open Access Journals (Sweden)

    Garrett Wheaton

    2015-07-01

    Full Text Available Extreme thermoacidophiles (Topt > 65 °C, pHopt < 3.5 inhabit unique environments fraught with challenges, including extremely high temperatures, low pH, as well as high levels of soluble metal species. In fact, certain members of this group thrive by metabolizing heavy metals, creating a dynamic equilibrium between biooxidation to meet bioenergetic needs and mechanisms for tolerating and resisting the toxic effects of solubilized metals. Extremely thermoacidophilic archaea dominate bioleaching operations at elevated temperatures and have been considered for processing certain mineral types (e.g., chalcopyrite, some of which are recalcitrant to their mesophilic counterparts. A key issue to consider, in addition to temperature and pH, is the extent to which solid phase heavy metals are solubilized and the concomitant impact of these mobilized metals on the microorganism’s growth physiology. Here, extreme thermoacidophiles are examined from the perspectives of biodiversity, heavy metal biooxidation, metal resistance mechanisms, microbe-solid interactions, and application of these archaea in biomining operations.

  10. Bioleaching of ultramafic tailings by acidithiobacillus spp. for CO2 sequestration.

    Science.gov (United States)

    Power, Ian M; Dipple, Gregory M; Southam, Gordon

    2010-01-01

    Bioleaching experiments using various acid-generating substances, i.e., metal sulfides and elemental sulfur, were conducted to demonstrate the accelerated dissolution of chrysotile tailings collected from an asbestos mine near Clinton Creek, Yukon, Canada. Columns, possessing an acid-generating substance colonized with Acidithiobacillus sp., produced leachates with magnesium concentrations that were an order of magnitude greater than mine site waters or control column leachates. In addition, chrysotile tailings were efficient at neutralizing acidity, which resulted in the immobilization of metals (Fe, Cu, Zn) associated with the metal sulfide mine tailings that were used to generate acid. This suggests that tailings from acid mine drainage environments may be utilized to enhance chrysotile dissolution without polluting "downstream" ecosystems. These results demonstrate that the addition of an acid-generating substance in conjunction with a microbial catalyst can significantly enhance the release of magnesium ions, which are then available for the precipitation of carbonate minerals. This process, as part of a carbon dioxide sequestration program, has implications for reducing net greenhouse gas emissions in the mining industry.

  11. A new strain Acidithiobacillus albertensis BY-05 for bioleaching of metal sulfides ores

    Institute of Scientific and Technical Information of China (English)

    XIA Jin-lan; PENG An-an; HE Huan; YANG Yu; LIU Xue-duan; QIU Guan-zhou

    2007-01-01

    An acidophilic, rod-shaped Gram-negative sulfur oxidizing strain BY-05 was isolated from an acid mine drainage of copper ore in Baiyin area, Gansu Province, China. Ultrastructural studies show that the isolate has a tuft of polar flagella and possesses sulfur granules with clear membrane adhering to the cell innermembrane. Physiological study shows that this isolate grows autotrophically and aerobically by oxidizing S0 and reduced inorganic sulfur compounds (S2O2-3,S2O2-4,S2- and ZnS) with the optimum growth at pH 3.5-4.0 and at the temperature range of 25-30 ℃. The 16S rRNA gene sequence (DQ 423683) of strain BY-05 has 100% sequence similarity to that of Acidithiobacillus albertensis (DSM 14366). So it is identified and named as A. albertensis BY-05. Bioleaching experiments with this new strain show that it can play an important role in recovery of metals from chalcopyrite and sphalerite.

  12. A combination of bioleaching and electromagnetic separation in the treatment of quartz sands

    Directory of Open Access Journals (Sweden)

    Lovás Michal

    2006-12-01

    Full Text Available This contribution deals with the treatment of Slovakian eolic quartz sands by bioleaching and magnetic separation with the aim to remove iron. The X-ray study of sand patterns confirms that quartz occurs as a dominant mineral. Accompanying minerals are represented by smectite and feldspars. As to the sample of unground sand, bacterial leaching resulted in a Fe2O3 reduction to the content of 0.13 %. Similarly, in case of ground sample, the Fe2O3 content was decreased to the value of 0.19 %. Thus, biological leaching removed 60 % of Fe and by following leaching by oxalic acid total the iron removal was 70.5 %. Finally, the application of magnetic separation resulted in the total iron removal of 93 % and, in such combined way, the prepared product contained 0.024 % of Fe2O3. Achieved results on the iron removal points to the fact that the combination of leaching and magnetic separation enables to obtain a product usable in glass industry.

  13. The role of biostimulation in iron bioleaching and purification of quartz sands

    Directory of Open Access Journals (Sweden)

    Iveta Štyriaková

    2011-12-01

    Full Text Available The biostimulation for iron mineral dissolution and reduction with chelators and organic source were investigated on ferrihydriteand quartz sands contaminated with iron minerals. The finding that bacteria can donate electrons to chelators has importantimplications for the removal of iron impurities from industrial minerals such as quartz sands. The effect of media composition withchelators (EDTA, NTA, AQDS on the extent of bacterial dissolution of iron mineral was studied under laboratory condition andselected a chelator Na2EDTA was studied under in-situ conditions.A stronger stimulation and continuos Fe dissolution by the form ofEDTA favors its in-situ use. Ultra-fine iron particles coating and impregnating quartz particles are difficult to treat by conventionalmineral processing methods. Biological leaching appears to be the alternative for the effective removal of iron minerals. The in-situremoval of Fe-phases from quartz sands via bioleaching was optimized with regard to the rate of iron reduction and dissolution bybiostimulation with Na2EDTA.

  14. Optimization of separation processing of copper and iron of dump bioleaching solution by Lix 984N in Dexing Copper Mine

    Institute of Scientific and Technical Information of China (English)

    LIU Qing-ming; YU Run-lan; QIU Guan-zhou; FANG Zheng; CHEN Ai-liang; ZHAO Zhong-wei

    2008-01-01

    The effects of the concentration of Lix 984N, phase ratio, initial pH value of aqueous phase and extraction time on the extraction of copper and iron under the condition of low Cu2+/Fe3+ ratio in dump bioleaching solution of Dexing Copper Mine were explored. The optimal conditions of extraction are as follows: the concentration of Lix 984N 10%; the phase ratio (O/A) 1:1; the initial pH value of aqueous phase 1.5 and the mixing time 2 min. The stripping experiments show that H2SO4 solution could efficiently recover copper from the organic phase under the optimal conditions.

  15. Towards a "crippled-mode" operation of an industrial wastewater treatment plant.

    Science.gov (United States)

    Szafnicki, Konrad; Narce, Cécile

    2006-02-01

    In house treatment of metal plating wastewater mainly involves chemical treatments performed in continuous flow stirred tank reactors (CFSTR). The inflow of these tanks is directly produced by the plating shops activity, and the storage capacity never exceeds a few hours of incoming flow. Thus, any fault on one of the CFSTR may impose a complete stop of the whole manufacturing process, which is unacceptable for the manufacturer. Another solution would be having "spare" CFSTRs ready to be used as alternative in case of any CFSTR fault or maintenance. The latter solution however implies additional costs in equipment, storage space and maintenance so as to keep this equipment fit and ready for operation. The paper presents the study of a "crippled-mode" wastewater treatment (WWT) operation which enables a sufficiently efficient working of the WWT plant during maintenance phases and failure repairing on any of the CFSTR, without any extra equipment needed. This survey has been performed on real industrial WWT plants, with a continuous influent and under industrial operation constraints. The performances of the detoxication have been analysed when a CFSTR is short-circuited and the corresponding chemical treatment is shunt in the upstream or downstream CSFTR. This work shows the possibility of satisfying the environmental regulations with a WWT plant functioning under subnormal conditions.

  16. Optimization of two-step bioleaching of spent petroleum refinery catalyst by Acidithiobacillus thiooxidans using response surface methodology.

    Science.gov (United States)

    Srichandan, Haragobinda; Pathak, Ashish; Kim, Dong Jin; Lee, Seoung-Won

    2014-01-01

    A central composite design (CCD) combined with response surface methodology (RSM) was employed for maximizing bioleaching yields of metals (Al, Mo, Ni, and V) from as-received spent refinery catalyst using Acidithiobacillus thiooxidans. Three independent variables, namely initial pH, sulfur concentration, and pulp density were investigated. The pH was found to be the most influential parameter with leaching yields of metals varying inversely with pH. Analysis of variance (ANOVA) of the quadratic model indicated that the predicted values were in good agreement with experimental data. Under optimized conditions of 1.0% pulp density, 1.5% sulfur and pH 1.5, about 93% Ni, 44% Al, 34% Mo, and 94% V was leached from the spent refinery catalyst. Among all the metals, V had the highest maximum rate of leaching (Vmax) according to the Michaelis-Menten equation. The results of the study suggested that two-step bioleaching is efficient in leaching of metals from spent refinery catalyst. Moreover, the process can be conducted with as received spent refinery catalyst, thus making the process cost effective for large-scale applications.

  17. Application of indigenous sulfur-oxidizing bacteria from municipal wastewater to selectively bioleach phosphorus from high-phosphorus iron ore: effect of particle size.

    Science.gov (United States)

    Shen, Shaobo; Rao, Ruirui; Wang, Jincao

    2013-01-01

    The effects of ore particle size on selectively bioleaching phosphorus (P) from high-phosphorus iron ore were studied. The average contents of P and Fe in the iron ore were 1.06 and 47.90% (w/w), respectively. The particle sizes of the ores used ranged from 58 to 3350 microm. It was found that the indigenous sulfur-oxidizing bacteria from municipal wastewater could grow well in the slurries of solid high-phosphorus iron ore and municipal wastewater. The minimum bioleaching pH reached for the current work was 0.33. The P content in bioleached iron ore reduced slightly with decreasing particle size, while the removal percentage of Fe decreased appreciably with decreasing particle size. The optimal particle size fraction was 58-75 microm, because the P content in bioleached iron ore reached a minimum of 0.16% (w/w), the removal percentage of P attained a maximum of 86.7%, while the removal percentage of Fe dropped to a minimum of 1.3% and the Fe content in bioleached iron ore was a maximum of 56.4% (w/w) in this case. The iron ores thus obtained were suitable to be used in the iron-making process. The removal percentage of ore solid decreased with decreasing particle size at particle size range of 106-3350 microm. The possible reasons resulting in above phenomena were explored in the current work. It was inferred that the particle sizes of the iron ore used in this work have no significant effect on the viability of the sulfur-oxidizing bacteria.

  18. Electric Energy Consumption of the Full Scale Research Biogas Plant “Unterer Lindenhof”: Results of Longterm and Full Detail Measurements

    Directory of Open Access Journals (Sweden)

    Thomas Jungbluth

    2012-12-01

    Full Text Available This work thoroughly evaluates the electric power consumption of a full scale, 3 × 923 m3 complete stirred tank reactor (CSTR research biogas plant with a production capacity of 186 kW of electric power. The plant was fed with a mixture of livestock manure and renewable energy crops and was operated under mesophilic conditions. This paper will provide an insight into precise electric energy consumption measurements of a full scale biogas plant over a period of two years. The results showed that a percentage of 8.5% (in 2010 and 8.7% (in 2011 of the produced electric energy was consumed by the combined heat and power unit (CHP, which was required to operate the biogas plant. The consumer unit agitators with 4.3% (in 2010 and 4.0% (in 2011 and CHP unit with 2.5% (in 2010 and 2011 accounted for the highest electrical power demand, in relation to the electric energy produced by the CHP unit. Calculations show that 51% (in 2010 and 46% (in 2011 of the total electric energy demand was due to the agitators. The results finally showed the need for permanent measurements to identify and quantify the electric energy saving potentials of full scale biogas plants.

  19. Remediation of heavy-metal contaminated sediments by means of bioleaching. Study: project results - economic efficiency - market assessment. Final report; Reinigung schwermetallbelasteter Sedimente durch Bioleaching. Studie: Projektergebnisse - Wirtschaftlichkeit - Marktbewertung. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Loeser, C.; Zehnsdorf, A.; Hoffmann, P.; Seidel, H.; Schmerold, R.

    2002-07-01

    Sediments in running and stationary waters continue to pose environmental as well as cost problems. In Saxonian waters alone some 3.7 million m{sup 3} of sediments mostly contaminated with heavy metals from mining or industrial activities are in need of remediation. For lack of practicable remediation methods excavated sediments nowadays are landfilled. However, due to its persisting hazard potential this solution is ecologically unsatisfactory. Exposure of these sediments to oxygen leads to microbial oxidation and acidification processes and hence partial solubilisation of heavy metals. If allowed to proceed uncontrolled this natural bioleaching process poses an environmental hazard. However, if accelerated artificially through activation of autochtonous sulphur oxidising bacteria (e.g. thiobacilli) it can be used to remediate sediments. The goal is to provide a semi-natural sediment decontamination process based on natural biological solubilisation potentials After decontamination, sediments can be returned to the materials cycle as soil substrates. The present process was developed using heavily contaminated sediments from the Weisse Elster region south of Leipzig as example material. For economic reasons it was decided to use a fixed-bed leaching process based on percolation. It proved necessary to use a multistage process. The laboratory and technical-scale experiments were dedicated to developing and implementing measures for faster metal solubilisation. [German] Gewaessersedimente sind ein bisher ungeloestes Umwelt- und Kostenproblem. Allein aus den Gewaessern Sachsens muessen ca. 3,7 Millionen m{sup 3} Sedimente beraeumt werden, diese sind zum grossen Teil mit Schwermetallen aus bergbaulichen und industriellen Aktivitaeten belastet. Gegenwaertig werden die ausgebaggerten Sedimente deponiert, da praktikable Sanierungsverfahren fehlen. Die Deoponierung ist wegen des weiter bestehenden Gefaehrdungspotentials keine oekologisch befriedigende Loesung. Kommen die

  20. Synthesis of argentojarosite with simulated bioleaching solutions produced by Acidithiobacillus ferrooxidans

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, Chiranjit [Department of Microbiology, Ohio State University, 484 West 12" t" h Avenue, Columbus, OH 43210 (United States); Jones, F. Sandy; Bigham, Jerry M. [School of Environment and Natural Resources, Ohio State University, 2021 Coffey Road, Columbus, OH 43210 (United States); Tuovinen, Olli H., E-mail: tuovinen.1@osu.edu [Department of Microbiology, Ohio State University, 484 West 12" t" h Avenue, Columbus, OH 43210 (United States)

    2016-09-01

    Argentojarosite (AgFe{sub 3}(SO{sub 4}){sub 2}(OH){sub 6}) is formed as a secondary phase in Ag-catalyzed bioleaching of chalcopyrite (CuFeS{sub 2}), but to date very little is known about the paragenesis or characteristics of this silver-containing compound. The purpose of this study was to synthesize argentojarosite via biological oxidation of 120 mM ferrous sulfate by Acidithiobacillus ferrooxidans. Because of its toxicity to A. ferrooxidans, Ag{sup +} (as AgNO{sub 3}) was added to spent culture media (pH 2) after complete oxidation of ferrous sulfate. Schwertmannite (ideally Fe{sub 8}O{sub 8}(OH){sub 6}(SO{sub 4})) was precipitated during the iron oxidation phase, and subsequent Ag{sup +} addition resulted in the formation of argentojarosite. Contact time (8 h, 5 d, and 14 d) and Ag{sup +} concentration (0, 5, 20, and 40 mM) were used as variables in these experiments. Synthesis of argentojarosite, schwertmannite and other mineral phases was confirmed through X-ray diffraction analysis. Additional analyses of solid-phase oxidation products included elemental composition, color and specific surface area. The sample synthesized in the presence of 40 mM Ag{sup +} and with 14 d contact time yielded an X-ray diffraction pattern of well crystallized argentojarosite, and its elemental composition closely matched the calculated Ag, Fe, and S contents of ideal argentojarosite. The color and surface area of the remaining samples were influenced by the presence of residual schwertmannite. This phase remained stable over the time course of 14 d when no Ag{sup +} was present in the system. When equilibrations were extended to 42 d, partial conversion of reference schwertmannite to goethite was noted in the absence of Ag. In the presence of 20 mM or 40 mM Ag over the same time course, some formation of argentojarosite was also noted. In this case, schwertmannite was the only source of Fe and SO{sub 4} for argentojarosite formation. - Highlights: • Iron-oxidizing bacteria

  1. Comparisons of optically monitored small-scale stirred tank vessels to optically controlled disposable bag bioreactors

    Directory of Open Access Journals (Sweden)

    Brorson Kurt A

    2009-08-01

    Full Text Available Abstract Background Upstream bioprocesses are extremely complex since living organisms are used to generate active pharmaceutical ingredients (APIs. Cells in culture behave uniquely in response to their environment, thus culture conditions must be precisely defined and controlled in order for productivity and product quality to be reproducible. Thus, development culturing platforms are needed where many experiments can be carried out at once and pertinent scale-up information can be obtained. Results Here we have tested a High Throughput Bioreactor (HTBR as a scale-down model for a lab-scale wave-type bioreactor (CultiBag. Mass transfer was characterized in both systems and scaling based on volumetric oxygen mass transfer coefficient (kLa was sufficient to give similar DO trends. HTBR and CultiBag cell growth and mAb production were highly comparable in the first experiment where DO and pH were allowed to vary freely. In the second experiment, growth and mAb production rates were lower in the HTBR as compared to the CultiBag, where pH was controlled. The differences in magnitude were not considered significant for biological systems. Conclusion Similar oxygen delivery rates were achieved in both systems, leading to comparable culture performance (growth and mAb production across scales and mode of mixing. HTBR model was most fitting when neither system was pH-controlled, providing an information-rich alternative to typically non-monitored mL-scale platforms.

  2. Performance and simulation of ozone absorption and reactions in a stirred-tank reactor.

    Science.gov (United States)

    Qiu, Y; Kuo, C H; Zappi, M E

    2001-01-01

    This research investigates the mass transport of gaseous ozone accompanied by decomposition and ozonation reactions in the liquid phase. Absorption experiments were carried out under semibatch mode by continued injection of gaseous ozone into an agitated vessel containing an aqueous solution of 2,4- or 2,6-dichlorophenol at 25 degrees C. Under the influence of a fast reaction between the dissolved ozone and dichlorophenol, the mass transfer rate of ozone is enhanced greatly resulting in rapid destruction of the dichlorophenol. Simulations of the experimental results suggest that the complete mixing model can be applied to describe the fluid flow patterns in both the gas and liquid phases. The results of this study indicate that dichlorophenols can be removed effectively from aqueous solutions of pH near neutrality and that there is little additional advantage in carrying out the treatment process in alkaline solutions.

  3. A Mathematical model for ethanol production by extractive fermentation in a continuous stirred tank fermentor.

    Science.gov (United States)

    Kollerup, F; Daugulis, A J

    1985-09-01

    Extractive fermentation is a technique that can be used to reduce the effect of end product inhibition through the use of a water-immiscible phase that removes fermentation products in situ. This has the beneficial effect of not only removing inhibitory products as they are formed (thus keeping reaction rates high) but also has the potential for reducing product recovery costs. We have chosen to examine the ethanol fermentation as a model system for end product inhibition and extractive fermentation and have developed a computer model predicting the productivity enhancement possible with this technique together with other key parameters such as extraction efficiency and residual glucose concentration. The model accommodates variable liquid flowrates entering and leaving the system, since it was found that the aqueous outlet flowrate could be up to 35% lower than the inlet flowrate during extractive fermentation of concentrated glucose feeds due to the continuous removal of ethanol from the fermentation broth by solvent extraction. The model predicts a total ethanol productivity of 82.6 g/L h if a glucose feed of 750 g/L is fermented with a solvent having a distribution coefficient of 0.5 at a solvent dilution rate of 5.0 h(-1). This is more than 10 times higher than for a conventional chemostat fermentation of a 250 g/L glucose feed. The model has furthermore illustrated the possible trade-offs that exist between obtaining a high extraction efficiency and a low residual glucose concentration.

  4. A Multiple-objective Optimization of Whey Fermentation in Stirred Tank Bioreactors

    Directory of Open Access Journals (Sweden)

    Mitko Petrov

    2006-12-01

    Full Text Available A multiple-objective optimization is applied to find an optimal policy of a fed-batch fermentation process for lactose oxidation from a natural substratum of the strain Kluyveromyces marxianus var. lactis MC5. The optimal policy is consisted of feed flow rate, agitation speed, and gas flow rate. The multiple-objective problem includes: the total price of the biomass production, the second objective functions are the separation cost in downstream processing and the third objective function corresponds to the oxygen mass-transfer in the bioreactor. The multiple-objective optimization are transforming to standard problem for optimization with single-objective function. Local criteria are defined utility function with different weight for single-type vector task. A fuzzy sets method is applied to be solved the maximizing decision problem. A simple combined algorithm guideline to find a satisfactory solution to the general multiple-objective optimization problem. The obtained optimal control results have shown an increase of the process productiveness and a decrease of the residual substrate concentration.

  5. Fungi solubilisation of low rank coal: performances of stirred tank, fluidised bed and packed bed reactors

    CSIR Research Space (South Africa)

    Oboirien, BO

    2013-02-01

    Full Text Available to the large coal particle size fraction (1.5–2 mm) used. Minimal damage to the fungal culture was observed. However, clogging of bed by fungi resulted in channelling or misdistribution that ultimately leads to poor and unpredictable internal mass transport....

  6. Quantification of brewers' yeast flocculation in a stirred tank: effect of physical parameters on flocculation.

    Science.gov (United States)

    van Hamersveld, E H; van der Lans, R G; Luyben, K C

    1997-10-20

    Quantification of yeast flocculation under defined conditions will help to understand the physical mechanisms of the flocculation process used in beer fermentation. Flocculation was quantified by measuring the size of yeast flocs and the number of single cells. For this purpose, a method to measure floc size and number of single cells in situ was developed. In this way, it was possible to quantify the actual flocculation during fermentation, without influencing flocculation. The effects of three physical parameters, floc strength, fluid shear, and yeast cell concentration, on flocculation during beer fermentation, were examined. Increasing floc strength results in larger flocs and lower numbers of single cells. If the fluid shear is increased, the size of the flocs decreases, and the number of single cells remains constant at approximately 10% of the total cells present. The cell concentration also influences flocculation, a reduction of 50% in cell concentration leads to a decrease of about 25% in floc size. The number of single cells decreases in linear proportion to the cell concentration. This means that, during yeast settling at full scale, the number of single cells decreases. The results of this study are used in a model for yeast flocculation. With respect to full scale fermentation the effect of cell concentration will play an important role, for flocculation and sedimentation will occur simultaneously leading to a quasi steady state between these phenomena. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 190-200, 1997.

  7. Measurement of Gas Hold-up Profiles in Stirred Tank Reactors by Gamma Ray Attenuation Technique

    NARCIS (Netherlands)

    Parasu Veera, U.; Patwardhan, A.W.; Joshi, J.B.

    2001-01-01

    Gas hold-up is one of the most important hydrodynamic characteristics that is needed for performance estimation, design and scale-up of reactors. The performance of large-scale reactors can be reliably evaluated by measuring the gas hold-up in such reactors. In the present work, local gas hold-up in

  8. Design of nonlinear PID controller and nonlinear model predictive controller for a continuous stirred tank reactor.

    Science.gov (United States)

    Prakash, J; Srinivasan, K

    2009-07-01

    In this paper, the authors have represented the nonlinear system as a family of local linear state space models, local PID controllers have been designed on the basis of linear models, and the weighted sum of the output from the local PID controllers (Nonlinear PID controller) has been used to control the nonlinear process. Further, Nonlinear Model Predictive Controller using the family of local linear state space models (F-NMPC) has been developed. The effectiveness of the proposed control schemes has been demonstrated on a CSTR process, which exhibits dynamic nonlinearity.

  9. Application of a stir-tank bioreactor for perfusion culture and ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-01-18

    Jan 18, 2010 ... ISSN 1684–5315 © 2010 Academic Journals. Full Length ... reused by the cells or degraded in the medium. (Dobbeleer .... remove residual sugar. The filtered ... The KLa was measured with water by a dynamic gassing-in and.

  10. Stabilization of unstable steady states of a continuous stirred tank bioreactor with predator-prey kinetics.

    Science.gov (United States)

    Tabiś, Bolesław; Skoneczny, Szymon

    2013-07-20

    Nonlinear properties of a bioreactor with a developed microbiological predator-prey food chain are discussed. The presence of the predator microorganism completely changes the position and stability of the stationary states. A wide range of unstable steady states appears, associated with high amplitude oscillations of the state variables. Without automatic control such a system can only operate in transient states, with the yield undergoing periodic changes following the dynamics of the stable limit cycle. Technologically, this is undesirable. It has been shown that the oscillations can be removed by employing continuous P or PI controllers. Moreover, with a PI-controller, the predator can be eliminated from the system.

  11. Mass transfer in stirred tank for phenolic extraction from coal tar

    Science.gov (United States)

    Fardhyanti, Dewi Selvia; Wibowo, Bahy; Rafiqi, Muhammad

    2017-01-01

    Coal production in Indonesia on 2014 reached 368.9 million tons. The used of coal utilization using pyrolysis process to produce coal tar is 15.8% by weight. Coal tar solution containing phenol as much as 8.06% (v / v) were extracted using a solvent of 80 % methanol. Time extraction is conducted for 30 minutes by making every 5 minutes. Samples are then separated to form two layers so that become layer of extract and raffinate. Extract and raffinate layer was then tested by using UV - Vis sektrofotometer so that the data obtained experimental results.The reserach about phenomenon and models of mass transfering and taking the phenol compound from coal tir is less. The result shows, the highest extracted of concentration phenol in 40°C, tank diameter 9cm, stirrer diameter 3,5cm, stirring speed of 250rpm and at 20 minutes extraction time got 2,35% concentration of phenol. Thus, the increasing temperature and stirred velocity will increase phenol concentration. In other hand, decreasing tank diameter will increase phenol concentration.

  12. Numerical simulation on macro-instability of coupling flow field structure in jet-stirred tank

    Science.gov (United States)

    Luan, D. Y.; Lu, J. P.; Bu, Q. X.; Zhang, S. F.; Zheng, S. X.

    2016-05-01

    The velocity field macro-instability (MI) can help to improve the mixing efficiency. In this work, the MI features of flow field induced by jet-stirred coupling action is studied by using computational fluid dynamics (CFD) simulations. The numerical simulation method of jet-stirred model was established based on standard turbulent equations, and the impeller rotation was modeled by means of the Sliding Mesh (SM) technology. The numerical results of test fluid (water) power consumption were compared with the data obtained by power test experiments. The effects of jet flow velocity and impeller speed on MI frequency were analyzed thoroughly. The results show that the calculated values of power consumption agree well with the experiment measured data, which validates the turbulent model, and the flow structure and MI frequency distribution are affected by both impeller speed and jet flow rate. The amplitude of MI frequency increases obviously with the increasing rotation speed of impeller and the eccentric jet rate, and it can be enhanced observably by eccentric jet rate, in condition of comparatively high impeller speed. At this time, the MI phenomenon disappears with the overall chaotic mixing.

  13. Effect of Temperature on Gas Hold—up in Aerated Stirred Tanks

    Institute of Scientific and Technical Information of China (English)

    高正明; 施力田

    2003-01-01

    Gas holdups in ambient gassed and hot sparged systems with multiple modern impellers and the effect of temperature on gas holdup are reported,The operating temperature has a great impact on gas holdup though the gas dispersion regime in the hot sparged system is similar to the ambient gassed condition,The gas holdup under the elevated temperature and the ambient gassed operation is successfully correlated.With the sarme total gas flow rate and power input,the gas holdup in the hot sparged system(say near the boiling point)is only about half of that in the ambient system ,The results imply that almost all existing hot sparged reactors have been designed on the basis of incorrect estimates of the gas holdup during operation.

  14. Modeling of Oxygen Transfer Correlations for Stirred Tank Bioreactor Agitated with Atypical Helical Ribbon Impeller

    Directory of Open Access Journals (Sweden)

    Mohd S. Mohamed

    2009-01-01

    Full Text Available Problem Statement: Mixing filamentous fungi entails delicate balance between promoting high volumetric oxygen transfer coefficient (kLa while keeping low hydrodynamic stresses in the microenvironment of cultures. This study examined the oxygen transfer capability of a prototype low shear helical impeller as a potential replacement for the standard Rushton turbine. Approach: The dependence of kLa upon specific power uptake, superficial gas velocity and apparent viscosity were examined under coalescent, non-coalescent and viscous pseudoplastic fluids scenario using dynamic gassing out technique. Subsequently, collected data were treated under historical data design of response surface methodology. Results: Three empirical power law kLa correlations were developed for each fluid. Correlation comparison with literature models for single turbine agitation suggest higher kLa augmentation within 1.5-3.6 folds for helical impeller in distilled water and as high as 78% improvement in electrolytes fluid. However impeller performance is comparatively 10% lower against theoretical kLa of triple turbines arrangement for power uptake between 0-1600 W m-3. In case of carboxymethylcellulose, better oxygen transfer is expected for design with higher proportionality of impeller-to-tank internal diameter. Conclusions: Helical impeller performance as gas-liquid contactor is comparable to single and triple Rushtons turbines, with superficial gas velocity proved to be more influential than power uptake in non-viscous liquids and vice versa in viscous pseudoplastic fluids.

  15. Numerical Bifurcation Analysis of Delayed Recycle Stream in a Continuously Stirred Tank Reactor

    Science.gov (United States)

    Gangadhar, Nalwala Rohitbabu; Balasubramanian, Periyasamy

    2010-10-01

    In this paper, we present the stability analysis of delay differential equations which arise as a result of transportation lag in the CSTR-mechanical separator recycle system. A first order irreversible elementary reaction is considered to model the system and is governed by the delay differential equations. The DDE-BIFTOOL software package is used to analyze the stability of the delay system. The present analysis reveals that the system exhibits delay independent stability for isothermal operation of the CSTR. In the absence of delay, the system is dynamically unstable for non-isothermal operation of the CSTR, and as a result of delay, the system exhibits delay dependent stability.

  16. MULTI-LOOP CONTROL DESIGN IN MULTIVARIABLE (2X2 CONTINUOUS STIRRED TANK REACTOR

    Directory of Open Access Journals (Sweden)

    Abdul Wahid

    2015-06-01

    Full Text Available With this study, the design and tuning of multi-loop for multivariable (2x2 CSTR will be made in order to achieve optimum CSTR control performance. This study used Bequette model reactor and MATLAB software and is expected to be able to cope with disturbances in the reactor so that the reactor system is able to stabilize quickly despite the distractions. In this study, the design will be made using multi-loop approach, along with PI controller as the next step. Then, BLT and auto-tune tuning method will be used in PI controller and given disturbances to both of tuning method. The controller performances are then compared. Results of the study are then analyzed for discussions and conclusions. Results from this study have shown that in terms of disturbance rejection, BLT is better than auto-tune based on comparison between both of controller performances. For IAE for the case of temperature, BLT is 30% better than auto-tune, but it is almost the same for the case of concentration. For settling time for the case of concentration, BLT is 30% better than auto-tune, and for the case of temperature, BLT is 18% better than auto-tune. For rise time for the case of concentration and temperature, BLT is 30% better than auto-tune.

  17. Leaching characteristics of encapsulated controlled low-strength materials containing arsenic-bearing waste precipitates from refractory gold bioleaching.

    Science.gov (United States)

    Bouzalakos, S; Dudeney, A W L; Chan, B K C

    2016-07-01

    We report on the leaching of heavy elements from cemented waste flowable fill, known as controlled low-strength materials (CLSM), for potential mine backfill application. Semi-dynamic tank leaching tests were carried out on laboratory-scale monoliths cured for 28 days and tested over 64 days of leaching with pure de-ionised water as leachant. Mineral processing waste include flotation tailings from a Spanish nickel-copper sulphide concentrate, and two bioleach neutralisation precipitates (from processing at 35°C and 70°C) from a South African arsenopyrite concentrate. Encapsulated CLSM formulations were evaluated to assess the reduction in leaching by encapsulating a 'hazardous' CLSM core within a layer of relatively 'inert' CLSM. The effect of each bioleach waste in CLSM core and tailings in CLSM encapsulating medium, are assessed in combination and in addition to CLSM with ordinary silica sand. Results show that replacing silica sand with tailings, both as core and encapsulating matrix, significantly reduced leachability of heavy elements, particularly As (from 0.008-0.190 mg/l to 0.008-0.060 mg/l), Ba (from 0.435-1.540 mg/l to 0.050-0.565 mg/l), and Cr (from 0.006-0.458 mg/l to 0.004-0.229 mg/l), to below the 'Dutch List' of groundwater contamination intervention values. Arsenic leaching was inherently high from both bioleach precipitates but was significantly reduced to below guideline values with encapsulation and replacing silica sand with tailings. Tailings proved to be a valuable encapsulating matrix largely owing to small particle size and lower hydraulic conductivity reducing diffusion transport of heavy elements. Field-scale trials would be necessary to prove this concept of encapsulation in terms of scale and construction practicalities, and further geochemical investigation to optimise leaching performance. Nevertheless, this work substantiates the need for alternative backfill techniques for sustainable management of hazardous finely-sized bulk

  18. Mass flow and energy balance plus economic analysis of a full-scale biogas plant in the rice-wine-pig system.

    Science.gov (United States)

    Li, Jiang; Kong, Chuixue; Duan, Qiwu; Luo, Tao; Mei, Zili; Lei, Yunhui

    2015-10-01

    This paper presents mass flow and energy balance as well as an economic analysis for a biogas plant in a rice-wine-pig system at a practical rather than laboratory scale. Results showed feeding amount was 65.30 t d(-1) (total solid matter (TSM) 1.3%) for the normal temperature continuous stirred tank reactor (CSTR), and 16.20 t d(-1) (TSM 8.4%) for the mesophilic CSTR. The digestion produced 80.50 t d(-1) of mass, with 76.41 t d(-1) flowing into rice fields and 4.49 t d(-1) into composting. Energy consumption of this plant fluctuated with seasons, and surplus energy was 823, 221 kWh/year. Thus, biogas plant was critical for material recycling and energy transformation of this agro-ecosystem. The economic analysis showed that the payback time of the plant was 10.9 years. It also revealed application of biogas as a conventional energy replacement would be attractive for a crop-wine-livestock ecosystem with anaerobic digestion of manure.

  19. Bioleaching of sphalerite by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans cultured in 9K medium modified with pyrrhotite

    Institute of Scientific and Technical Information of China (English)

    CHEN Song; QIU Guan-zhou; QIN Wen-qing; LAN Zhuo-yue

    2008-01-01

    Elective culture of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans in 9K medium modified with pyrrhotite was studied. Bioleaching of flotation concentrate of sphalerite by the selected bacteria was carried out. The results show that the microorganisms cultured by pyrrhotite are a mixture of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans, of which the capability to oxidize ferrous to ferric irons is enhanced by the high mass ratio of Fe to S in pyrrhotite. Three pyrrhotite samples were separated into various parts with corresponding S/Fe ratios by magnetic separation and were used to culture the elective bacteria as the substrate. The association of the cultures could provide a more rapid and complete oxidation of sphalerite than that of bacteria cultivated by conventional methods.

  20. The use of co-digested solid fraction as feedstock for biogas plants

    Directory of Open Access Journals (Sweden)

    E. Dinuccio

    2013-09-01

    Full Text Available A comparative study was set up in order to assess the technical feasibility of the long-term reuse of the mechanically separated co-digested solid fraction as a feedstock for anaerobic digestion plants (ADP. The biogas yields of two feedstock mixtures (A and B were assessed in mesophilic conditions (40 °C ± 2 °C using 8 lab-scale continuous stirred-tank reactors (CSRT. Feedstock mixture A (control consisted of pig slurry (70%, farmyard manure (4%, sorghum silage (12% and maize silage (14%. Feedstock mixture B was the same as the control plus the solid fraction derived from the mechanical separation of the output raw co-digestate collected on daily basis from the reactors. All reactors were fed simultaneously, three times a week, over a period of nine month. According to the study results, the reuse of the co-digested solid fraction as feedstock for ADP could increase the methane yield by approximately 4%. However, ADP efficiency evaluation (e.g., daily yield of methane per m3 of digester suggest to limit this practice to a maximum time period of 120 days.

  1. Extracellular polymeric substances mediate bioleaching/biocorrosion via interfacial processes involving iron(III) ions and acidophilic bacteria.

    Science.gov (United States)

    Sand, Wolfgang; Gehrke, Tilman

    2006-01-01

    Extracellular polymeric substances seem to play a pivotal role in biocorrosion of metals and bioleaching, biocorrosion of metal sulfides for the winning of precious metals as well as acid rock drainage. For better control of both processes, the structure and function of extracellular polymeric substances of corrosion-causing or leaching bacteria are of crucial importance. Our research focused on the extremophilic bacteria Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans, because of the "simplicity" and knowledge about the interactions of these bacteria with their substrate/substratum and their environment. For this purpose, the composition of the corresponding extracellular polymeric substances and their functions were analyzed. The extracellular polymeric substances of both species consist mainly of neutral sugars and lipids. The functions of the exopolymers seem to be: (i) to mediate attachment to a (metal) sulfide surface, and (ii) to concentrate iron(III) ions by complexation through uronic acids or other residues at the mineral surface, thus, allowing an oxidative attack on the sulfide. Consequently, dissolution of the metal sulfide is enhanced, which may result in an acceleration of 20- to 100-fold of the bioleaching process over chemical leaching. Experiments were performed to elucidate the importance of the iron(III) ions complexed by extracellular polymeric substances for strain-specific differences in oxidative activity for pyrite. Strains of A. ferrooxidans with a high amount of iron(III) ions in their extracellular polymeric substances possess greater oxidation activity than those with fewer iron(III) ions. These data provide insight into the function of and consequently the advantages that extracellular polymeric substances provide to bacteria. The role of extracellular polymeric substances for attachment under the conditions of a space station and resulting effects like biofouling, biocorrosion, malodorous gases, etc. will be discussed.

  2. Effect of CO2 and N2 on microbial community changes during column bioleaching of low-grade high pyrite-bearing chalcocite ore

    Institute of Scientific and Technical Information of China (English)

    陈勃伟; 武彪; 刘兴宇; 温建康

    2015-01-01

    Simulated heap bioleaching of low-grade high pyrite-bearing chalcocite ore was conducted at 40 °C with aeration of CO2 and N2. Ore samples were collected at day 43, 64, 85, 106 and subjected to microbial community analysis by 16S rRNA gene clone library. Phylogenetic analyses of 16S rDNA fragments revealed that the retrieved sequences are mainly related to genus Acidithiobacillus,Leptospirillum andSulfobacillus. Aeration of CO2 and N2 significantly impacted the microbial community composition. When CO2 was aerated, the proportion of genusAcidithiobacillus considerably increased, whereas the proportion of genusLeptospirillum and genusSulfobacillus declined. However, with the aeration of N2, the proportion of genusAcidithiobacillus andLeptospirillum increased, but genusSulfobacillus decreased. When there was no aeration, the microbial community was similar to the inocula with the proportion of genusLeptospirillum mounted. These results indicated that the limitation of oxygen could change the bioleaching microbial community and the aeration of CO2 and N2 was favourable for the growth of sulfur-oxidizer (At. caldus) and iron-oxidizer (L. ferriphilum) respectively, which could be used for the regulation of microorganisms’ role in mineral bioleaching.

  3. Two-stage digestion of renewable raw materials. Applying bioleaching for utilizing grass silage; Zweiphasige Vergaerung nachwachsender Rohstoffe. Einsatz des Bioleaching-Verfahrens zur Verwertung von Grassilage

    Energy Technology Data Exchange (ETDEWEB)

    Zielonka, S.; Lemmer, A.; Oechsner, H. [Hohenheim Univ., Stuttgart (Germany). Landesanstalt fuer Landwirtschaftliches Maschinen- und Bauwesen; Jungbluth, T. [Hohenheim Univ., Stuttgart (Germany). Inst. fuer Agrartechnik

    2007-07-01

    Currently renewable raw materials are being used in full scale biogas plants as co-substrates. Using grass silage frequently caused technical problems till now. Within the framework of this project, a process to digest grass silage as a single substrate is being developed. An intermittently operating two-stage process is used. As far as the degree of degradation and methane yields are concerned, good and promising results have been achieved. (orig.)

  4. 白银含铜废石生物柱浸试验研究%Experimental Research on Column Bioleaching of Copper-containing Waste Rock in Baiyin

    Institute of Scientific and Technical Information of China (English)

    刘厚明; 舒荣波; 王晓慧; 程蓉; 梁友伟

    2012-01-01

    Research on leaching experiment by adopting bioleaching method was carried on the copper-containing waste rock in Baiyin. According to the ore properties and bioleaching characteristic, the influence of grain size,types of leaching bacteria, leaching temperature and leaching time on leaching results was studied. The results showed that the bioleaching of copper-containing waste rock using moderate thermoacidophile BioMetal SM-3 was feasible. And the relatively high leaching rate ofcopper( >60% ) was obtained for size of ?5mm after being bioleached for 190 days. The influence of ore size on metal leaching rate and column stability was also researched. When it was applied to industry, the ore should be crushed to -20mm before ore stacking to ensure the stability of ore heap and metal leaching rate. The obtained experimental parameter revealed the rule and process-controlled factors of the copper-containing waste rock in Baiyin, which can guide the industrial production of the copper-containing waste rock in Baiyin by adopting the method of bioleaching.%以白银矿区存有的大量含铜废石为研究对象,采用生物柱浸法对其进行浸出试验研究.结合白银废石铜矿特点与细菌浸出特性,分别研究不同矿样粒度,浸矿菌种,浸矿温度以及浸出时间等对浸出结果的影响.研究结果表明,采用BioMetal SM-3中等嗜热嗜酸菌浸出白银废石堆矿样是可行的,可在较短的浸出时间(190d)内获得较高的铜浸出率(-15mm粒级Cu浸出率>60%).通过对比不同矿样粒度对金属浸出率与矿柱稳定性的影响,在工业应用时,为保证矿堆的稳定性和金属浸出速率,建议将矿石破碎到-20 mm粒级然后筑堆..本试验研究所取得的试验参数揭示了白银含铜废石生物浸出规律及过程控制因素,对白银含铜废石采用生物堆浸工业生产具有指导意义.

  5. Modelling of the temperature-phased batch anaerobic digestion of raw sludge from an urban wastewater treatment plant.

    Science.gov (United States)

    Riau, Víctor; De la Rubia, M Angeles; Pérez, Montserrat; Martín, Antonio; Borja, Rafael

    2012-01-01

    The disposal of excess sludge from wastewater treatment plants is a serious problem that needs to be addressed. Temperature-phased anaerobic digestion (TPAD) which combines thermophilic and mesophilic processes in one, brings together the advantages of both systems. The aim of the present work was to develop a simple kinetic model to describe the TPAD of sewage sludge in batch completely stirred tank reactors (CSTRs) and to determine the kinetic parameters of both thermophilic and mesophilic stages. A zero-order kinetic equation described the thermophilic step after 2, 4 and 6 days of digestion time (experiment 1, 2 and 3, respectively), yet a first-order equation was found to be adequate to correlate the methane gas accumulated with time in the mesophilic step, the kinetic constant being 0.21 days(-1). The methane yield coefficient obtained was found to be almost proportional to the digestion time used in the thermophilic step with values of 0.067, 0.132 and 0.193 L CH(4) STP/g VS(added) for experiments 1, 2 and 3, respectively. By contrast, the kinetic constant of the mesophilic stage was not influenced by the digestion time used in the thermophilic phase.

  6. Experimental Study on a Two-step Bioleaching Removal of Phosphorus from High-phosphorus Iron Ore%高磷赤铁矿两步法生物除磷实验研究

    Institute of Scientific and Technical Information of China (English)

    钟乐乐; 龚文琪; 李育彪; 王楠; 陆玉; 刘时健; 张鹏超

    2012-01-01

    Acidithiobacillus thiooxidans {At, t) was used in bioleaching removal of phosphorus from the high-phosphorus iron ore (iron grade 43. 50%, p content 0. 85%) by direct bioleaching and two-step bioleaching, respectively. The experimental results showed that with the pulp density of 2%, by direct bioleaching the phosphorus removal rate reached 62. 35% and the sulfur content reached up to 28. 57%; At. t bacteria were used in bioleaching removal of phosphorus by the two-step bioleaching in a shaking table. After 24 d, the pH of the bacteria solution was close to 0, 8, the phosphorus concentration was reduced to 0. 15%, and the sulfur content was reduced to 1. 09%. After cultivation in the self-fabricated bioreactor for 8 d the pH of the At. t solution was close to 0. 98. The phosphorus concentration of the iron ore was reduced to 0. 18% after leaching in the supernatant of the bacteria solution for 12 h. The bioleaching of the magnetic separation concentrate by the two-step bioleaching method showed a remarkable efficiency of phosphorus removal when the pulp density was below 3%.%采用嗜酸氧化硫硫杆菌(At.t)直接浸出和两步法浸出,对鄂西高磷鲕状赤铁矿(铁品位43.50%,磷含量0.85%)进行生物除磷的实验研究.结果表明:矿浆浓度为2%时,At.t菌直接浸出除磷率为62.35%,且硫含量高达28.57%;采用两步法摇床培养At.t菌,24 d菌液pH值接近0.8,磷含量可降至0.15%,硫含量为1.09%;采用自行设计制作的生物反应器培养At.t菌8d,菌液pH值接近0.98,分离菌液浸出原矿12 h磷含量为0.18%.对磁选精矿进行的两步法浸出表明,当矿浆浓度为3%以下时菌液的徐磷效果明显.

  7. Interactions of the metal tolerant heterotrophic microorganisms and iron oxidizing autotrophic bacteria from sulphidic mine environment during bioleaching experiments.

    Science.gov (United States)

    Jeremic, Sanja; Beškoski, Vladimir P; Djokic, Lidija; Vasiljevic, Branka; Vrvić, Miroslav M; Avdalović, Jelena; Gojgić Cvijović, Gordana; Beškoski, Latinka Slavković; Nikodinovic-Runic, Jasmina

    2016-05-01

    Iron and sulfur oxidizing chemolithoautotrophic acidophilic bacteria, such as Acidithiobacillus species, hold the dominant role in mine environments characterized by low pH values and high concentrations of reduced sulfur and iron compounds, such as ores, rocks and acid drainage waters from mines. On the other hand, heterotrophic microorganisms, especially their biofilms, from these specific niches are receiving increased attention, but their potential eco-physiological roles have not been fully understood. Biofilms are considered a threat to human health, but biofilms also have beneficial properties as they are deployed in waste recycling and bioremediation systems. We have analyzed interactions of the metal tolerant heterotrophic microorganisms in biofilms with iron oxidizing autotrophic bacteria both from the sulphidic mine environment (copper mine Bor, Serbia). High tolerance to Cu(2+), Cd(2+) and Cr(6+) and the presence of genetic determinants for the respective metal tolerance and biofilm-forming ability was shown for indigenous heterotrophic bacteria that included strains of Staphylococcus and Rhodococcus. Two well characterized bacteria- Pseudomonas aeruginosa PAO1 (known biofilm former) and Cupriavidus metallidurans CH34 (known metal resistant representative) were also included in the study. The interaction and survivability of autotrophic iron oxidizing Acidithiobacillus bacteria and biofilms of heterotrophic bacteria during co-cultivation was revealed. Finally, the effect of heterotrophic biofilms on bioleaching process with indigenous iron oxidizing Acidithiobacillus species was shown not to be inhibitory under in vitro conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Bioleaching of spent Ni-Cd batteries and phylogenetic analysis of an acidophilic strain in acidified sludge

    Institute of Scientific and Technical Information of China (English)

    ZHAO Ling; WANG Liang; YANG Dong; ZHU Nanwen

    2007-01-01

    Biohydrometallurgy is a novel method to recycle discarded batteries,in which sewage sludge is used as microorganisms and culture due to the presence of indigenous Thiobacilli.A two-step continuous flow.leaching system consisting of an acidifying reactor and a leaching reactor was introduced to achieve the bioleaching of spent nickelcadmium (Ni-Cd) batteries.The acid supematant produced in the acidifying reactor by the microorganisms with ferrous ions as the substrate was conducted into the leaching reactor to dissolve electrode materials.The efficiency of a batch treatment of batteries was examined.The results showed that the complete dissolution of two AA-sized Ni-Cd batteries with 0.6 L/d acid supernatant took about 30,20,and 35 days for Ni,Cd,and Co,respectively.But the dissolution ability of the three metals was different.Cd and Co can be leached mostly for pH below 4.0 while the complete dissolution of Ni can be achieved for pH below 2.5.Meanwhile,a strain (named Thiooxidans.WL) accounting for the reduction of pH in the acidified sludge was isolated and sequenced.It was identified to be 100% similar to Acidithiobacillus ferrooxidans strain Tf-49 based on 16S rDNA sequence analysis.The relevant phylogenetic tree constructed indicates that the strain should be classified into genus Acidithiobacillus ferrooxidans.

  9. Bioleach: a mathematical model for the joint evaluation of leachate and biogas production in urban solid waste landfills

    Science.gov (United States)

    Rodrigo-Clavero, Maria-Elena; Rodrigo-Ilarri, Javier

    2017-04-01

    One of the most serious environmental problems in modern societies is the management and disposal of urban solid waste (MSW). Despite the efforts of the administration to promote recycling and reuse policies and energy recovery technologies, nowadays the majority of MSW still is disposed in sanitary landfills. During the phases of operation and post-closure maintenance of any solid waste disposal site, two of the most relevant problems are the production of leachate and the generation of biogas. The leachate and biogas production formation processes occur simultaneously over time and are coupled together through the consumption and/or production of water. However, no mathematical models have been easily identified that allow to the evaluation of the joint production of leachate and biogas, during the operational and the post-closure phase of an urban waste landfill. This paper introduces BIOLEACH, a new mathematical model programmed on a monthly scale, that evaluates the joint production of leachate and biogas applying water balance techniques and considers the management of the landfill as a bioreactor. The application of such a model on real landfills allows to perform an environmentally sustainable management that minimizes the environmental impacts produced being also economically more profitable.

  10. Bioleached sludge composting drastically reducing ammonia volatilization as well as decreasing bulking agent dosage and improving compost quality: A case study.

    Science.gov (United States)

    Hu, Weitong; Zheng, Guanyu; Fang, Di; Cui, Chunhong; Liang, Jianru; Zhou, Lixiang

    2015-10-01

    Sludge bioleaching technology with Acidithiobacillus species has been commercially adopted for improving advanced dewatering of sludge in China since 2010. However, up to now, little information on bioleached dewatered sludge (BS) composting is available. Here, we report the changes of physicochemical and biological properties in BS composting and evaluate compost product quality compared to conventional dewatered sludge (CS) composting in an engineering scale composting facility. The results showed that the amount of bulking agents required in BS composting was only about 10% of CS composting to obtain optimum moisture content, reducing about 700 kg bulking agents per ton fresh sludge. pH of BS composting mixture was slightly lower consistently by about 0.2-0.3 pH units than that in CS mixture in the first 30 days. Organic matter biodegradation in BS system mainly occurred in the first 9 days of composting. In spite of higher content of NH4(+)-N was found in BS mixture in related to CS mixture; unexpectedly the cumulative ammonia volatilization in the former was only 51% of the latter, indicating that BS composting drastically reduced nitrogen loss. Compared to CS composting system, the relative lower pH, the higher intensity of microbial assimilation, and the presence of water soluble Fe in BS system might jointly reduce ammonia volatilization. Consequently, BS compost product exhibited higher fertilizer values (N+P2O5+K2O=8.38%) as well as lower heavy metal levels due to the solubilization of sludge-borne heavy metals during bioleaching process. Therefore, composting of BS possesses more advantages over the CS composting process.

  11. The in-line measurement of plant cell biomass using radio frequency impedance spectroscopy as a component of process analytical technology.

    Science.gov (United States)

    Holland, Tanja; Blessing, Daniel; Hellwig, Stephan; Sack, Markus

    2013-10-01

    Radio frequency impedance spectroscopy (RFIS) is a robust method for the determination of cell biomass during fermentation. RFIS allows non-invasive in-line monitoring of the passive electrical properties of cells in suspension and can distinguish between living and dead cells based on their distinct behavior in an applied radio frequency field. We used continuous in situ RFIS to monitor batch-cultivated plant suspension cell cultures in stirred-tank bioreactors and compared the in-line data to conventional off-line measurements. RFIS-based analysis was more rapid and more accurate than conventional biomass determination, and was sensitive to changes in cell viability. The higher resolution of the in-line measurement revealed subtle changes in cell growth which were not accessible using conventional methods. Thus, RFIS is well suited for correlating such changes with intracellular states and product accumulation, providing unique opportunities for employing systems biotechnology and process analytical technology approaches to increase product yield and quality. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. 元素硫对黄铜矿生物浸出行为及群落结构的影响%Relationships among bioleaching performance, additional elemental sulfur,microbial population dynamics and its energy metabolism in bioleaching of chalcopyrite

    Institute of Scientific and Technical Information of China (English)

    夏乐先; 汤露; 夏金兰; 尹礎; 柴立元; 赵小娟; 聂珍媛; 柳建设; 邱冠周

    2012-01-01

    To estimate the relationships among bioleaching performance,additional elemental sulfur (S0),microbial population dynamics and its energy metabolism,bioleaching of chalcopyrite by three typical sulfur- and/or iron-oxidizing bacteria,Acidithiobacillus ferrooxidans,Leptospirillum ferriphilum and Acidithiobacillus thiooxidans with different levels of sulfur were studied in batch shake flask cultures incubated at 30 ℃.Copper dissolution capability (71%) was increased with the addition of 3.193 g/L S0,compared to that (67%) without S0.However,lower copper extraction was obtained in bioleaching with excessive sulfur.Microbial population dynamics during chalcopyrite bioleaching process was monitored by using PCR-restrietion fragment length polymorphism (PCR-RFLP).Additional S0 accelerated the growth of sulfur-oxidizing bacteria,inhibited the iron-oxidizing metabolism and led to the decrease of iron-oxidizing microorganisms,finally affected iron concentration,redox potential and bioleaching performance.It is suggested that mixed iron and sulfur-oxidizing microorganisms with further optimized additional S0 concentration could improve copper recovery from chalcopyrite.%研究3种典型铁/硫代谢菌-Acidithiobacillus ferrooxidans,Leptospirillum ferriphilum及Acidithiobacillus thiooxidans混合浸出黄铜矿过程中铁/硫氧化活性、群落结构(PCR-RFLP)的变化,以及不同浓度的元素硫对其影响.结果发现,加入3.193 g/L元素硫能促进细菌的表观硫氧化活性,改变浸矿体系的群落结构,并进一步影响钝化层的形成、金属离子的溶出,其浸出率(71%)较未添加硫的(67%)有一定程度的提高.而过量的元素硫会抑制铜的浸出(浸出率44%).

  13. 生物淋滤法对污水污泥中重金属去除效果研究%Removal of Heavy Metals in Urban Sewage Sludg by Bioleaching

    Institute of Scientific and Technical Information of China (English)

    崔佳丽; 王增长

    2011-01-01

    Chemical forms of heavy metals from concentrated sludge from certain sewage treatment plants in Taiyuan were analyzed by Sequential Extraction Technique. All the heavy metals measured did not exceed the standard of alkalescent soil; only the content of Zn and Cu exceeded the standard of acidic soil. The unsteady chemical forms of element Zn took a high percentage in sludge, other metals were more steady. On the basis of the results, influence on removal effect with different inoculum sizes and sulfur concentration by bioleaching was investigated. The results show that efficiency was optimum with inoculum sizes of 3 % and sulfur concentration of 3 g/L.%利用Tessier五步法,对某污水处理厂初沉池和二沉池混合的浓缩污泥进行重金属形态分析和测定,结果显示,所测定的重金属均未超过我国污泥农林利用碱性土壤标准,只有Cu和Zn超过了污泥农林利用酸性土壤标准;污泥中Zn不稳定形态所占比例较高,其余重金属稳定性较好.在此基础上,研究了用生物淋滤法去除Cu、Zn时,不同接种量和不同底物投加量的溶出率.结果表明,当接种量体积分数为3%、硫的质量浓度为3 g/L时去除效果最好.本研究结果为城市污泥农用前降低重金属毒性奠定了基础.

  14. Bioleaching of ilmenite and basalt in the presence of iron-oxidizing and iron-scavenging bacteria

    Science.gov (United States)

    Navarrete, Jesica U.; Cappelle, Ian J.; Schnittker, Kimberlin; Borrok, David M.

    2013-04-01

    Bioleaching has been suggested as an alternative to traditional mining techniques in extraterrestrial environments because it does not require extensive infrastructure and bulky hardware. In situ bioleaching of silicate minerals, such as those found on the moon or Mars, has been proposed as a feasible alternative to traditional extraction techniques that require either extreme heat and/or substantial chemical treatment. In this study, we investigated the biotic and abiotic leaching of basaltic rocks (analogues to those found on the moon and Mars) and the mineral ilmenite (FeTiO3) in aqueous environments under acidic (pH ˜ 2.5) and circumneutral pH conditions. The biological leaching experiments were conducted using Acidithiobacillus ferrooxidans, an iron (Fe)-oxidizing bacteria, and Pseudomonas mendocina, an Fe-scavenging bacteria. We found that both strains were able to grow using the Fe(II) derived from the tested basaltic rocks and ilmenite. Although silica leaching rates were the same or slightly less in the bacterial systems with A. ferrooxidans than in the abiotic control systems, the extent of Fe, Al and Ti released (and re-precipitated in new solid phases) was actually greater in the biotic systems. This is likely because the Fe(II) leached from the basalt was immediately oxidized by A. ferrooxidans, and precipitated into Fe(III) phases which causes a change in the equilibrium of the system, i.e. Le Chatelier's principle. Iron(II) in the abiotic experiment was allowed to build up in solution which led to a decrease in its overall release rate. For example, the percentage of Fe, Al and Ti leached (dissolved + reactive mineral precipitates) from the Mars simulant in the A. ferrooxidans experimental system was 34, 41 and 13% of the total Fe, Al and Ti in the basalt, respectively, while the abiotic experimental system released totals of only 11, 25 and 2%. There was, however, no measurable difference in the amounts of Fe and Ti released from ilmenite in the

  15. Studies on effects of superiority strains on bioleaching of Mn from electrolytic manganese residues%优势菌种浸取电解锰渣中锰的影响因素研究

    Institute of Scientific and Technical Information of China (English)

    黄华军; 李小明; 曹建兵; 张忠辉; 李焕利; 方丽; 杨慧; 杨麒; 刘精今

    2011-01-01

    采用电解锰废渣中分离出的一种锰抗性强的微生物Fusarium sp.浸取电解锰渣中的锰。研究了不同矿浆浓度、微生物生长活动、锰渣和培养基等对锰浸取效率的影响。结果表明,接种体积比为2%(v/v)时,矿浆浓度(m/v)对锰浸取效率影响显著,矿浆浓度过低(〈2%)或者过高(〉10%)对锰浸取效率都有不利影响。矿浆浓度为10%时锰浸取效率最高,达80%以上;微生物的生长活动对浸取过程有显著的影响;而锰渣的存在则能在一定程度上影响溶液的pH,进而影响锰浸取效率;培养基对锰浸取效率的贡献达50%左右。%The micro-organism named Fusarium sp.,which was separated from electrolytic manganese residues,has strong resistance of manganese.A series of microbioleaching experiments were performed using Fusarium sp.to extract manganese from electrolytic manganese residues.The effects of different factors such as pulp density,microbial growth and activity,electrolytic manganese residues and culture medium on the Mn bioleaching efficiency were studied.The results showed that the pulp densities had a significant influence on the Mn bioleaching efficiency when the inoculation volume ratio was 2%.The Mn bioleaching efficiency was inhibited when the pulp densities were too low(〈2%) or too high(〉10%).The highest Mn bioleaching efficiency was obtained when the pulp density was 10%,and it reached more than 80%;microbial growth and activity had a significant impact on bioleaching process.The existence of electrolytic manganese residues affected the pH of the solution to some extent,thereby affecting the Mn bioleaching efficiency.The contribution of culture medium to Mn bioleaching efficiency was about 50%.

  16. Foaming and cell flotation in suspended plant cell cultures and the effect of chemical antifoams.

    Science.gov (United States)

    Wongsamuth, R; Doran, P M

    1994-08-01

    Foam development and stability in Atropa belladonna suspensions were investigated as a function of culture conditions. Foaming was due mainly to properties of the cell-free broth and was correlated with protein content; effects due to presence of cells increased towards the end of batch culture. Highest foam levels were measured 11 days after inoculation. Air flow rate was of major importance in determining foam volume; foam volume and stability were also strongly dependent on pH. Foam flotation of plant cells was very effective. After 30 min foaming, ca. 55% of cells were found in the foam; this increased to ca. 75% after 90 min. Polypropylene glycol 1025 and 2025, Pluronic PE 6100, and Antifoam-C emulsion were tested as chemical antifoams. Polypropylene glycol 1025 and Antifoam C at concentrations up to 600 ppm had no adverse effect on growth in shake flasks; Pluronic PE 6100 has an inhibitory effect at all levels tested. Concentrations of polypropylene glycol 2025 and Pluronic PE 6100 as low as 20 ppm reduced foam volumes by a factor of ca. 10. Addition of antifoam reduced k(L)a values in bubble-column and stirred-tank bioreactors. After operation of a stirred reactor for 2 days using Antifoam C for foam control, cell production was limited by oxygen due to the effect of antifoam on mass transfer. Theoretical analysis showed that maximum cell concentrations and biomass levels decline with increasing reactors working volume due to greater consumption of antifoam to prevent foam overflow. The results indicate that when chemical foam control is used in plant cell cultures, head-space volume and tolerable foam levels must be considered to optimize biomass production. (c) 1994 John Wiley & Sons, Inc.

  17. Synergistic effect of biogenic Fe(3+) coupled to S° oxidation on simultaneous bioleaching of Cu, Co, Zn and As from hazardous Pyrite Ash Waste.

    Science.gov (United States)

    Panda, Sandeep; Akcil, Ata; Mishra, Srabani; Erust, Ceren

    2017-03-05

    Pyrite ash, a waste by-product formed during roasting of pyrite ores, is a good source of valuable metals. The waste is associated with several environmental issues due to its dumping in sea and/or land filling. Although several other management practices are available for its utilization, the waste still awaits and calls for an eco-friendly biotechnological application for metal recovery. In the present study, chemolithotrophic meso-acidophilic iron and sulphur oxidisers were evaluated for the first time towards simultaneous mutli-metal recovery from pyrite ash. XRD and XRF analysis indicated higher amount of Hematite (Fe2O3) in the sample. ICP-OES analysis indicated concentrations of Cu>Zn>Co>As that were considered for bioleaching. Optimization studies indicated Cu - 95%, Co - 97%, Zn - 78% and As - 60% recovery within 8days at 10% pulp density, pH - 1.75, 10% (v/v) inoculum and 9g/L Fe(2+). The productivity of the bioleaching system was found to be Cu - 1696ppm/d (12% dissolution/d), Co - 338ppm/d (12.2% dissolution/d), Zn k 576ppm/d (9.8% dissolution/d) and As - 75ppm/d (7.5% dissolution/d). Synergistic actions for Fe(2+) - S° oxidation by iron and sulphur oxidisers were identified as the key drivers for enhanced metal dissolution from pyrite ash sample.

  18. Degradation of inhibitory substances in sludge by Galactomyces sp. Z3 and the role of its extracellular polymeric substances in improving bioleaching.

    Science.gov (United States)

    Zhou, Jun; Zheng, Guanyu; Wong, Jonathan W C; Zhou, Lixiang

    2013-03-01

    This study sought to elucidate the effect and mechanism of Galactomyces sp. Z3 in improving the bioleaching of heavy metals from sludge. Results showed that co-inoculation of Galactomyces sp. Z3 and two Acidithiobacillus strains (Acidithiobacillus ferrooxidans LX5 and Acidithiobacillus thiooxidans TS6) reduced the period required for sludge bioleaching by 4.5days compared to Acidithiobacillus alone. Further, removal efficiencies of Cu, Zn and oxidation rate of Fe(2+) and S(0) were higher in co-inoculation system than the Acidithiobacillus alone. Galactomyces sp. Z3 consumed the acetate, propionate, iso-butyrate, butyrate, and iso-valerate in sludge from the initial concentrations of 109.50, 28.80, 7.70, 34.30, and 18.40mg/L to 10.20, 0.61, 0.63, 19.40 and 1.30mg/L, respectively, after 12h in the co-inoculation system, significantly lower than the concentrations observed in the Acidithiobacillus alone. Meanwhile, the surfactant properties of the extracellular polymeric substances produced by the Galactomyces accelerated the rate of sulfur oxidization by A. thiooxidans.

  19. The effect of the introduction of exogenous strain Acidithiobacillus thiooxidans A01 on functional gene expression, structure and function of indigenous consortium during pyrite bioleaching.

    Science.gov (United States)

    Liu, Yi; Yin, Huaqun; Zeng, Weimin; Liang, Yili; Liu, Yao; Baba, Ngom; Qiu, Guanzhou; Shen, Li; Fu, Xian; Liu, Xueduan

    2011-09-01

    Acidithiobacillus thiooxidans A01 was added to a consortium of bioleaching bacteria including Acidithiobacilluscaldus, Leptospirillumferriphilum, Acidithiobacillus ferrooxidans, Sulfobacillus thermosulfidooxidans, Acidiphilium spp., and Ferroplasma thermophilum cultured in modified 9 K medium containing 0.5% (w/v) pyrite, and 10.7% increase of bioleaching rate was observed. Changes in community structure and gene expression were monitored with real-time PCR and functional gene arrays (FGAs). Real-time PCR showed that addition of At. thiooxidans caused increased numbers of all consortium members except At. caldus, and At. caldus, L. ferriphilum, and F. thermophilum remained dominant in this community. FGAs results showed that after addition of At. thiooxidans, most genes involved in iron, sulfur, carbon, and nitrogen metabolisms, metal resistance, electron transport, and extracellular polymeric substances of L. ferriphilum, F. thermophilum, and Acidiphilium spp., were up-regulated while most of these genes were down-regulated at 70-78 h in At. caldus and up-regulated in At. ferrooxidans, then down-regulated at 82-86 h.

  20. Co-gasification of biomass and plastics: pyrolysis kinetics studies, experiments on 100 kW dual fluidized bed pilot plant and development of thermodynamic equilibrium model and balances.

    Science.gov (United States)

    Narobe, M; Golob, J; Klinar, D; Francetič, V; Likozar, B

    2014-06-01

    Thermo-gravimetric analysis (TGA) of volatilization reaction kinetics for 50 wt.% mixtures of plastics (PE) and biomass (wood pellets) as well as for 100 wt.% plastics was conducted to predict decomposition times at 850°C and 900°C using iso-conversional model method. For mixtures, agreement with residence time of dual fluidized bed (DFB) reactor, treated as continuous stirred-tank reactor (CSTR), was obtained at large conversions. Mono-gasification of plastics and its co-gasification with biomass were performed in DFB pilot plant, using olivine as heterogeneous catalyst and heat transfer agent. It was found that co-gasification led to successful thermochemical conversion of plastics as opposed to mono-gasification. Unknown flow rates were determined applying nonlinear regression to energy and mass balances acknowledging combustion fuel, air, steam, feedstock, but also exiting char, tar, steam and other components in DFB gasification unit. Water-gas shift equilibrium and methanol synthesis requirements were incorporated into gasification model, based on measurements.

  1. An assessment of acid wash and bioleaching pre-treating options to remove mercury from coal

    Energy Technology Data Exchange (ETDEWEB)

    Laura C. Dronen; April E. Moore; Evguenii I. Kozliak; Wayne S. Seames [University of North Dakota, Grand Forks, ND (USA). Department of Chemical Engineering

    2004-01-01

    The United States Environmental Protection Agency is expected to begin regulating the release of vapor-phase mercury from coal-fired power plants in the year 2007. Chemical pre-treatment methods were investigated for mercury removal effectiveness from pulverized low-sulfur North Dakota lignite coal. More limited results were obtained for a pulverized high-sulfur Blacksville bituminous coal. A two-step acid wash treatment showed removal rates of 60 90%, compared to one-step treatments with concentrated HCl, which yielded removals of 30 38%. Removal effectiveness is similar for first step solvents of water, pH 5.0 acid, or pH 2.0 acid followed by concentrated HCl as the second step solvent, and is independent of first step incubation time. Neither of two bacterial strains, Thiobacillus ferrooxidans and T. thiooxidans, was found effective for mercury removal. 23 refs., 5 tabs.

  2. Fungus-mediated preferential bioleaching of waste material such as fly - ash as a means of producing extracellular, protein capped, fluorescent and water soluble silica nanoparticles.

    Directory of Open Access Journals (Sweden)

    Shadab Ali Khan

    Full Text Available In this paper, we for the first time show the ability of the mesophilic fungus Fusarium oxysporum in the bioleaching of waste material such as Fly-ash for the extracellular production of highly crystalline and highly stable, protein capped, fluorescent and water soluble silica nanoparticles at ambient conditions. When the fungus Fusarium oxysporum is exposed to Fly-ash, it is capable of selectively leaching out silica nanoparticles of quasi-spherical morphology within 24 h of reaction. These silica nanoparticles have been completely characterized by UV-vis spectroscopy, Photoluminescence (PL, Transmission electron microscopy (TEM, X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and Energy dispersive analysis of X-rays (EDAX.

  3. Influence factors of pyrite promotion on the bioleaching of chalcopyrite%黄铁矿促进黄铜矿微生物浸出影响因素

    Institute of Scientific and Technical Information of China (English)

    莫晓兰; 林海; 傅开彬; 徐承焱; 汪涵

    2012-01-01

    Chalcopyrite-pyrite bioleaching tests were performed with shaking flasks by Aeidithiobacillusferrooxidans. The research focused on the effects of basic salt mediums, pyrite-to-chalcopyrite mass ratio and mineral size distribution. It is found that chaleopyrite bioleaching can be promoted by pyrite, The leaching rate of copper in the iron-free 9K medium in pyrite-chaleopyrite bioleaching is 1.68 times as large as that in the 9K medium. The leaching of copper is better using a wide size range of minerals and the leaching rate of copper is related to the mass ratio of pyrite to chalcopyrite. When the mass ratio is 2: 2, the highest leaching rate of copper is ob- tained to be 45.58%. The content of pyrite is of the essence in affecting the leaching rate level of copper. At a mass ratio of pyrite to chalcopyrite no more than 5:2 the oxidation of Acidithiobacillus ferrooxidans plays an important role in the bioleaching, but when the mass ratio is 10:2 the galvanic effect between the two sulphide minerals mainly influences the bioleaehing. X-ray diffraction analyses of leaching residues indicate that the generation of jarosite in the iron-free 9K medium is less than that in the 9K medium, FeSO4 in the 9K medium can be replaced by pyrite, the galvanic effect forms with chaleopyrite, and therefore the bioleaehing efficiency of copper is increased.%采用摇瓶实验,以氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans,At.f)浸出黄铁矿--黄铜矿,重点研究了基础培养基、矿物配比和粒度组成等因素的影响.黄铁矿能促进黄铜矿的微生物浸出,以采用无Fe 9K培养基效果较好,它对应铜浸出率是9K培养基的1.68倍;采用宽粒级矿物时铜浸出效果较好,且铜浸出率与黄铁矿和黄铜矿的质量比有关,当质量比为2∶2时铜浸出率最高可达45.58%;黄铁矿含量大小是影响铜浸出率高低的实质,当质量比小于等于5∶2时以At.f菌的氧化作用为主,当质量比为10∶2时以硫

  4. Study on Uranium Recovery from Uranium-Containing Waste Dump Using Heap-Bioleaching%含铀废矿石细菌堆浸试验

    Institute of Scientific and Technical Information of China (English)

    袁保华; 孙占学; 史维浚

    2011-01-01

    采用05B混合菌种对含铀废石进行堆浸回收铀的可行性研究,并确定该废石细菌堆浸工艺流程与工艺参数.结果表明:05B菌种组合具有优良的适应性、活性和很强的耐氟性,能完全适应该废石细菌堆浸的要求.渣计铀浸出率为50.0%,渣品位已达到环境允许要求(0.01%).堆浸试验酸耗2.6%,浸铀期146天,每吨含铀废石消耗硫酸亚铁12 kg.%The feasibility of uranium-containing waste dump-bioleaching using 05B mixed strains was studied, and the technological process and technical parameters were determined.The results indicated that 05B mixed strains was of fine adaptability, activity and high tolerance of fluorine and suitable for uraniumcontaining waste dump-bioleaching.The leaching rate value of 50.0% was achieved, and the uranium content in the heap leaching residue met the environmental requirement (0.01%).The experiment was completed in 146 days, the FeSO4 · 7H2O consumption was 12 kg per ton of uranium-containing waste dump, and sulfuric acid consumption rate was 2.6%.

  5. Column Bioleaching of Low-grade Uranium Ore%低品位铀矿石微生物柱浸试验

    Institute of Scientific and Technical Information of China (English)

    李江; 刘亚洁; 周谷春; 车江华

    2012-01-01

    Column bioleaching of a low-grade uranium ore with a variety of spraying methods was carried out. The results show that the mixed culture of acidophilic microorganisms in use have a high adaptation to the uranium minerals, and the average uranium leaching rates are 87. 70% and 88. 53%, the acid consumption is 5.36% and 5.37% within 172 days, at 5% and 10% spraying condition, respectively. A bigger spray liquid quantity could increase uranium leaching rate at the bioleaching stage, however, the ratio of liquid to solid rises greatly as well, which resulted in a rise of cost for uranium recovery. Therefore, the optimum spray liquid quantity should be confirmed with a consideration of both uranium recovery and leaching cost.%对某低品位铀矿石进行了不同喷淋条件的微生物柱浸试验.结果表明,试验用混合菌群对目标铀矿石具有较强适应性,浸出周期172 d,菌浸期间5%和10%喷淋量条件下渣计平均浸出率分别为87.70%和88.53%,耗酸率分别为5.36%和5.37%.菌浸阶段采用较大喷淋量可提高浸出率,但液固比会显著增加,综合成本相应提高.因此,喷淋量的选择应综合考虑铀资源回收率与浸出成本.

  6. Co-digestion of food and garden waste with mixed sludge from wastewater treatment in continuously stirred tank reactors

    DEFF Research Database (Denmark)

    Fitamo, Temesgen Mathewos; Boldrin, Alessio; Boe, Kanokwan

    2016-01-01

    Co-digestions of urban organic waste were conducted to investigate the effect of the mixing ratio between sludge, food waste, grass clippings and green waste at different hydraulic retention times (HRTs). Compared to the digestion of 100% sludge, the methane yield increased by 48% and 35%, when co......-digesting sludge with food waste, grass clippings and garden waste with a corresponding % VS of 10:67.5:15.75:6.75 (R1) and 10:45:31.5:13.5 (R2), respectively. The methane yield remained constant at around 425 and 385 NmL CH4/g VS in R1 and R2, respectively, when the reactors were operated at HRTs of 15, 20 and 30...

  7. Biogas Upgrading via Hydrogenotrophic Methanogenesis in Two-Stage Continuous Stirred Tank Reactors at Mesophilic and Thermophilic Conditions.

    Science.gov (United States)

    Bassani, Ilaria; Kougias, Panagiotis G; Treu, Laura; Angelidaki, Irini

    2015-10-20

    This study proposes an innovative setup composed by two stage reactors to achieve biogas upgrading coupling the CO2 in the biogas with external H2 and subsequent conversion into CH4 by hydrogenotrophic methanogenesis. In this configuration, the biogas produced in the first reactor was transferred to the second one, where H2 was injected. This configuration was tested at both mesophilic and thermophilic conditions. After H2 addition, the produced biogas was upgraded to average CH4 content of 89% in the mesophilic reactor and 85% in the thermophilic. At thermophilic conditions, a higher efficiency of CH4 production and CO2 conversion was recorded. The consequent increase of pH did not inhibit the process indicating adaptation of microorganisms to higher pH levels. The effects of H2 on the microbial community were studied using high-throughput Illumina random sequences and full-length 16S rRNA genes extracted from the total sequences. The relative abundance of archaeal community markedly increased upon H2 addition with Methanoculleus as dominant genus. The increase of hydrogenotrophic methanogens and syntrophic Desulfovibrio and the decrease of aceticlastic methanogens indicate a H2-mediated shift toward the hydrogenotrophic pathway enhancing biogas upgrading. Moreover, Thermoanaerobacteraceae were likely involved in syntrophic acetate oxidation with hydrogenotrophic methanogens in absence of aceticlastic methanogenesis.

  8. Theoretical and experimental study of the effects of scale-up on mixing time for a stirred-tank bioreactor

    Directory of Open Access Journals (Sweden)

    P. Bonvillani

    2006-03-01

    Full Text Available Mixing time is one of the criteria most widely used to characterize mixing intensity in bioprocesses. In bioreactors, mixing mainly depends on amount of energy consumed, reactor and stirrer shapes, airing speed and the rheology of the medium. In this work we experimentally determined the mixing times for a lab-scale bioreactor equipped with a stirrer propelled by two Rushton turbines. From these experiments we could obtain expressions to evaluate the effects of stirring speed, superficial gas velocity, specific power consumption and system geometry on mixing times under various flow regimes. The resulting correlations were employed to analyze the effect of scale-up on mixing times for the production of Staphylococcus aureus Smith.

  9. Optimization of ethanol production from carob pod extract using immobilized Saccharomyces cerevisiae cells in a stirred tank bioreactor.

    Science.gov (United States)

    Ercan, Yatmaz; Irfan, Turhan; Mustafa, Karhan

    2013-05-01

    In this study, optimization of ethanol production from carob pod extract was carried out by immobilized Saccharomyces cerevisiae. Results showed that Ca-alginate concentration and the amount of immobilized cells had significant effects on yield. Optimum conditions for ethanol fermentation were determined to be 2% Ca-alginate concentration, 150 rpm agitation rate, 5% yeast cells entrapped in beads and pH 5.5. After validation experiments; ethanol concentration, yield, production rate and sugar utilization rate were respectively 40.10 g/L, 46.32%, 3.19 g/L/h and 90.66%; and the fermentation time was decreased to 24 h. In addition, the immobilized cells were shown to be reusable for five cycles, though a decrease in yield was observed. Finally, carob pod extract was used for ethanol fermentation by controlled and uncontrolled pH without any enrichment, and the results suggest that carob extract can be utilized effectively by immobilized-cell fermentation without the use of enrichments to facilitate yeast growth.

  10. Effect of oxygen transfer rate on cellulases production in stirred tank and internal-loop airlift bioreactors

    OpenAIRE

    Michelin, Michele; Mota,André; Silva,Daniel Pereira da; A.A. Vicente; Teixeira, J. A; Polizeli, Maria de Lourdes T. M.

    2013-01-01

    In an aerobic process, such as enzymes production by fungi, the oxygen supply into fermentation medium is an important factor in order to achieve good productivities. Oxygen has an important role in metabolism and microorganism growth, being of extreme importance the control of both the dissolved oxygen transfer rate into the bioreactor and the oxygen consumption by the microorganism [1,2]. Dissolved oxygen transfer rate can be analyzed and described by means of the mass transfer coefficient,...

  11. Dynamic bioconversion mathematical modelling and simulation of urban organic waste co-digestion in continuously stirred tank reactor

    DEFF Research Database (Denmark)

    Fitamo, Temesgen Mathewos; Boldrin, Alessio; Dorini, G.

    waste. However, the successful operation of AD processes is challenged by economic and technological issues. To overcome these barriers, mathematical modelling of the bioconversion process can provide support to develop strategies for controlling and optimizing the AD process. The objective......The application of anaerobic digestion (AD) as process technology is increasing worldwide: the production of biogas, a versatile form of renewable energy, from biomass and organic waste materials allows mitigating greenhouse gas emission from the energy and transportation sectors while treating...... (55 oC). Sludge, food waste, grass clippings, garden waste were co-digested with VS-based mixing ratios of 10:67.5:15.75:6.75 and 10:45:31.5:13.5 in R1 and R2 respectively. The BioModel (Angelidaki et al., 1999) was then employed with minor modifications of model parameters. The model outputs were...

  12. Biogas Upgrading via Hydrogenotrophic Methanogenesis in Two-Stage Continuous Stirred Tank Reactors at Mesophilic and Thermophilic Conditions

    DEFF Research Database (Denmark)

    Bassani, Ilaria; Kougias, Panagiotis; Treu, Laura;

    2015-01-01

    to the second one, where H2 was injected. This configuration was tested at both mesophilic and thermophilic conditions. After H2 addition, the produced biogas was upgraded to average CH4 content of 89% in the mesophilic reactor and 85% in the thermophilic. At thermophilic conditions, a higher efficiency of CH4...... production and CO2 conversion was recorded. The consequent increase of pH did not inhibit the process indicating adaptation of microorganisms to higher pH levels. The effects of H2 on the microbial community were studied using high-throughput Illumina random sequences and full-length 16S rRNA genes extracted...

  13. Design of an Adaptive PID Neural Controller for Continuous Stirred Tank Reactor based on Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    Khulood A. Dagher

    2013-12-01

    Full Text Available A particle swarm optimization algorithm and neural network like self-tuning PID controller for CSTR system is presented. The scheme of the discrete-time PID control structure is based on neural network and tuned the parameters of the PID controller by using a particle swarm optimization PSO technique as a simple and fast training algorithm. The proposed method has advantage that it is not necessary to use a combined structure of identification and decision because it used PSO. Simulation results show the effectiveness of the proposed adaptive PID neural control algorithm in terms of minimum tracking error and smoothness control signal obtained for non-linear dynamical CSTR system.

  14. Increasing Vero viable cell densities for yellow fever virus production in stirred-tank bioreactors using serum-free medium.

    Science.gov (United States)

    Mattos, Diogo A; Silva, Marlon V; Gaspar, Luciane P; Castilho, Leda R

    2015-08-20

    In this work, changes in Vero cell cultivation methods have been employed in order to improve cell growth conditions to obtain higher viable cell densities and to increase viral titers. The propagation of the 17DD yellow fever virus (YFV) in Vero cells grown on Cytodex I microcarriers was evaluated in 3-L bioreactor vessels. Prior to the current changes, Vero cells were repeatedly displaying insufficient microcarrier colonization. A modified cultivation process with four changes has resulted in higher cell densities and higher virus titers than previously observed for 17DD YFV.

  15. Optimisation of Cellulase Production by Penicillium funiculosum in a Stirred Tank Bioreactor Using Multivariate Response Surface Analysis

    Directory of Open Access Journals (Sweden)

    Marcelle Lins de Albuquerque de Carvalho

    2014-01-01

    Full Text Available Increasing interest in the production of second-generation ethanol necessitates the low-cost production of enzymes from the cellulolytic complex (endoglucanases, exoglucanases, and β-glucosidases, which act synergistically in cellulose breakdown. The present work aimed to optimise a bioprocess to produce these biocatalysts from the fungus Penicillium funiculosum ATCC11797. A statistical full factorial design (FFD was employed to determine the optimal conditions for cellulase production. The optimal composition of culture media using Avicel (10 g·L−1 as carbon source was determined to include urea (1.2 g·L−1, yeast extract (1.0 g·L−1, KH2PO4 (6.0 g·L−1, and MgSO4·7H2O (1.2 g·L−1. The growth process was performed in batches in a bioreactor. Using a different FFD strategy, the optimised bioreactor operational conditions of an agitation speed of 220 rpm and aeration rate of 0.6 vvm allowed the obtainment of an enzyme pool with activities of 508 U·L−1 for FPase, 9,204 U·L−1 for endoglucanase, and 2,395 U·L−1 for β-glucosidase. The sequential optimisation strategy was effective and afforded increased cellulase production in the order from 3.6 to 9.5 times higher than production using nonoptimised conditions.

  16. Optimisation of Cellulase Production by Penicillium funiculosum in a Stirred Tank Bioreactor Using Multivariate Response Surface Analysis.

    Science.gov (United States)

    de Albuquerque de Carvalho, Marcelle Lins; Carvalho, Daniele Fernandes; de Barros Gomes, Edelvio; Nobuyuki Maeda, Roberto; Melo Santa Anna, Lidia Maria; de Castro, Aline Machado; Pereira, Nei

    2014-01-01

    Increasing interest in the production of second-generation ethanol necessitates the low-cost production of enzymes from the cellulolytic complex (endoglucanases, exoglucanases, and β-glucosidases), which act synergistically in cellulose breakdown. The present work aimed to optimise a bioprocess to produce these biocatalysts from the fungus Penicillium funiculosum ATCC11797. A statistical full factorial design (FFD) was employed to determine the optimal conditions for cellulase production. The optimal composition of culture media using Avicel (10 g·L(-1)) as carbon source was determined to include urea (1.2 g·L(-1)), yeast extract (1.0 g·L(-1)), KH2PO4 (6.0 g·L(-1)), and MgSO4 ·7H2O (1.2 g·L(-1)). The growth process was performed in batches in a bioreactor. Using a different FFD strategy, the optimised bioreactor operational conditions of an agitation speed of 220 rpm and aeration rate of 0.6 vvm allowed the obtainment of an enzyme pool with activities of 508 U·L(-1) for FPase, 9,204 U·L(-1) for endoglucanase, and 2,395 U·L(-1) for β-glucosidase. The sequential optimisation strategy was effective and afforded increased cellulase production in the order from 3.6 to 9.5 times higher than production using nonoptimised conditions.

  17. Co-digestion of food and garden waste with mixed sludge from wastewater treatment in continuously stirred tank reactors.

    Science.gov (United States)

    Fitamo, T; Boldrin, A; Boe, K; Angelidaki, I; Scheutz, C

    2016-04-01

    Co-digestions of urban organic waste were conducted to investigate the effect of the mixing ratio between sludge, food waste, grass clippings and green waste at different hydraulic retention times (HRTs). Compared to the digestion of 100% sludge, the methane yield increased by 48% and 35%, when co-digesting sludge with food waste, grass clippings and garden waste with a corresponding %VS of 10:67.5:15.75:6.75 (R1) and 10:45:31.5:13.5 (R2), respectively. The methane yield remained constant at around 425 and 385 NmL CH4/g VS in R1 and R2, respectively, when the reactors were operated at HRTs of 15, 20 and 30 days. However, the methane yield dropped significantly to 356 (R1) and 315 (R2) NmL CH4/g VS when reducing the HRT to 10 days, indicating that the process was stressed. Since the methane production rate improved significantly with decreasing HRT, the trade-off between yield and productivity was obtained at 15 days HRT.

  18. Anaerobic co-digestion of chicken manure and corn stover in batch and continuously stirred tank reactor (CSTR).

    Science.gov (United States)

    Li, Yeqing; Zhang, Ruihong; He, Yanfeng; Zhang, Chenyu; Liu, Xiaoying; Chen, Chang; Liu, Guangqing

    2014-03-01

    Anaerobic co-digestion of chicken manure and corn stover in batch and CSTR were investigated. The batch co-digestion tests were performed at an initial volatile solid (VS) concentration of 3gVS/L, carbon-to-nitrogen (C/N) ratio of 20, and retention time of 30d. The methane yield was determined to be 281±12mL/gVSadded. Continuous reactor was carried out with feeding concentration of 12% total solids and C/N ratio of 20 at organic loading rates (OLRs) of 1-4gVS/L/d. Results showed that at OLR of 4gVS/L/d, stable and preferable methane yield of 223±7mL/gVSadded was found, which was equal to energy yield (EY) of 8.0±0.3MJ/kgVSadded. Post-digestion of digestate gave extra EY of 1.5-2.6MJ/kgVSadded. Pyrolysis of digestate provided additional EY of 6.1MJ/kgVSadded. Pyrolysis can be a promising technique to reduce biogas residues and to produce valuable gas products simultaneously.

  19. Anaerobic digestion of blackwater from vacuum toilets and kitchen refuse in a continuous stirred tank reactor (CSTR).

    Science.gov (United States)

    Wendland, C; Deegener, S; Behrendt, J; Toshev, P; Otterpohl, R

    2007-01-01

    The objective of this research was mesophilic anaerobic digestion of blackwater from vacuum toilets (BW) and kitchen refuse (KR) in a CSTR within an ecological sanitation system. A detailed investigation of the BW characteristics was carried out. Research on anaerobic digestion was performed with CSTR of 101 volume at HRT of 10, 15 and 20 days. The digestion of BW at 20 days HRT showed stable performance without inhibition effects, in spite of relatively high ammonium concentrations. The removal of total and particulate COD was 61% and 53%, respectively, and the methane yield 10/CH4/cap/day. The addition of kitchen refuse (KR) improved the performance of the CSTR in terms of COD removal efficiency and methane yield. At 20 days HRT the removal of total and particulate COD increased up to 71% and 67%, respectively, and the methane yield to 27/CH4/cap/day. The results at 15 days HRT showed similar performance. At HRT of 10 days, the anaerobic treatment was limited but reached steady state conditions at higher VFA concentrations in the effluent, with a decrease of COD removal of 30 to 33% and of methane yields of 19 to 21%.

  20. Biogas upgrading by injection of hydrogen in a two-stage Continuous Stirred-Tank Reactor system

    DEFF Research Database (Denmark)

    Bassani, Ilaria; Kougias, Panagiotis; Treu, Laura;

    An innovative method for biogas upgrading (i.e. CH4 content more than 90%) combines the coupling of H2, which could be produced by water electrolysis using surplus renewable electricity produced from wind mills, with the CO2 of the biogas. CO2 is biologically converted to CH4 by hydrogenotrophic...... methanogens. In this study, a novel serial biogas reactor system is presented, in which the produced biogas from the first stage reactor was introduced in the second stage, where also H2 was injected. The effects of the H2 addition on the process performance and on the microbial community were investigated...

  1. Factors affecting the production of a single-chain antibody fragment by Aspergillus awamori in a stirred tank reactor.

    Science.gov (United States)

    Sotiriadis, A; Keshavarz, T; Keshavarz-Moore, E

    2001-01-01

    A recombinant strain of Aspergillus awamori expressing anti-lysozyme single chain antibody fragments (scFv), under the control of a xylanase promoter, was studied in order to investigate the impact of medium, induction regime and protease production on the expression of the product. Experiments with the time of induction showed that the optimum results are achieved when induction is started in the late exponential phase (21 h after inoculation) improving the titer of the product from 14.5 mg L(-1), obtained in the early exponential phase (7 h after inoculation), to 16.2 mg L(-1). A 100% increase of the carbon (fructose) and nitrogen (ammonium sulfate) sources in the growth medium resulted in an increase in product concentration from 16.2 to 108.9 mg L(-1) and an increase in maximum dry cell weight from 7.5 to 11.5 g L(-1). A 50% reduction in the concentration of the inducer resulted in an increase in the product yield from 10 mg g(-1) dry cell weight to 12 mg g(-1). Proteolytic enzymes were produced during the fermentation up to concentrations equivalent to 1.4 g L(-1) trypsin, but they had no detrimental effect on the concentration of the antibody fragment.

  2. L-glutamic acid production in a continuous stirred tank bioreactor using coimmobilized bio-catalyst using a fluorosensor.

    Science.gov (United States)

    Prabhu, N; Babu, J Sarat Chandra; Sundaram, S

    2002-01-01

    The production of L-Glutamic acid has been studied using coimmobilized whole cells of pseudomonas reptilivora and micrococcus glutamicus in a two litre Tokyo Rikakikai fermentor using glucose as selected production medium. The process was carried out at an optimum temperature of 32 degree Celsius and a pH of 7.2. The progress of the reaction was recorded using Dr. Ingold fluorosensor. The effect of initial substrate concentration, speed of agitation, volume ofcalcium alginate beads and aeration rate on the yield of glutamic acid has been investigated. It has been found that the acid production increases exponentially with substrate concentration, and mass transfer co-efficient varied linearly with aeration rate. The kinetic parameters also had been estimated.

  3. Operational strategies for thermophilic anaerobic digestion of organic fraction of municipal solid waste in continuously stirred tank reactors

    DEFF Research Database (Denmark)

    Angelidaki, Irini; Cui, J.; Chen, X.;

    2006-01-01

    Three operational strategies to reduce inhibition due to ammonia during thermophilic anaerobic digestion of source-sorted organic fraction of municipal solid waste (SS-OFMSW) rich in proteins were investigated. Feed was prepared by diluting SS-OFMSW (ratio of 1:4) with tap water or reactor proces...

  4. Environmentally-safe process control and state diagnostic in chemical plants by neuronal network. Subproject 2. Final report; Umweltgerechte Prozessfuehrung und Zustandserkennung in Chemieanlagen mit neuronalen Netzen. Teilvorhaben 2: Konzipierung und Erprobung des Zustandserkennungsverfahrens. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Hessel, G.; Heidrich, J.; Hilpert, R.; Roth, M. [Degussa AG (Germany); Kryk, H.; Schmitt, W.; Seiler, T.; Weiss, F.P.

    2002-12-01

    In the frame of the sub-project, an on-line monitoring system for strongly exothermic reactions was developed to support the operational personnel in the optimal and environmentally compatible process control of complex or safety-difficult reactions in semibatch-mode in stirred tank reactors (batch reactor). The Monitoring System (MoSys) based on dimensionless mass and heat balances with adaptive functions has first to be trained using process data from normal and undesired courses of batches carried out in a miniplant under conditions of the industrial process. The adaptation of balance models to the target plant is done by two-layer perceptron networks. To ensure a complete scale-up, MoSys should be adapted and validated using process data of at least one normal batch course in the chemical plant. MoSys was designed for both a homogeneous exothermic esterification reaction and a heterogeneous exothermic hydrogenation process. Experimental tests were carried out in a pilot plant (esterification) and in an industrial plant (hydrogenation). For industrial testing, MoSys was integrated into a Batch-Information-Management System (BIMS) which was also developed and implemented in the Process Control System (PCS) of a multi-purpose reactor installation in the fine chemical factory at Radebeul (Degussa Inc.). As a result, the MoSys outputs can simultaneously be visualised with important process signals on the terminals of PCS. For example, the progress of hydrogenation, the predictive end of reaction and the concentration profiles of the educt, intermediate and product are displayed on the terminals of operator stations. Furthermore, when undesired operating states occur, the operational personnel is early alarmed and recommendation are given for countermeasures that are allowed to be only done by the operator. The efficiency of BIMS/MoSys could be proven during two industrial hydrogenation campaigns. (orig.)

  5. 污泥生物沥滤中硫细菌变化和胞外多聚物作用的研究%Variation in sulfur bacteria and extracellular polymeric substances during sewage sludge bioleaching

    Institute of Scientific and Technical Information of China (English)

    华玉妹; 陈英旭; 张少辉

    2011-01-01

    通过序批试验,分析污泥生物沥滤过程中pH值、异养菌数量变化以及硫细菌的形态,探讨了污泥中重金属在胞外多聚物(EPS)中的分布变化.结果表明,污泥经生物沥滤后异养菌大量死亡.扫描电镜和透射电镜对污泥微生物形态的观测发现,随着生物沥滤时间的延长,生物沥滤污泥明显比对照污泥中的微生物分布紧密,而且杆状和短杆状菌呈现逐渐增多趋势.生物沥滤后期出现受损的细菌胞体以及释放了细胞物质的细菌空壳.污泥沥滤液中EPS含量有所增加,沥滤过程中EPS的松散结合态与紧密结合态的比值呈现先上升后下降趋势,可反映沥滤前期细菌处于加速生长期的居多,而后期处于减速生长期的细菌逐渐增多.污泥 EPS 中重金属含量在生物沥滤几天后表现持续增长,Cu、Pb和Zn分布于EPS中的最高含量分别占污泥中总量的14.7%、20.3%和24.2%.延长酸化时间,EPS可被水解,而导致其中重金属含量呈现一定下降趋势.%Lots of heterotrophic bacteria died after sewage sludge bioleaching. The exploration of microbial communities using scanning electron microscopy and transmission electron microscopy illustrated that the bacteria distribution in bioleaching sludge was more intensive than that in the control sludge, and the rod-shaped and short rod-shaped bacteria appeared to increase with the extension of time. The damaged bacteria cell and residual cell without intracellular matter emerged at the anaphase of bioleaching. The weight percentage of extracellular polymeric substances (EPS) in the sludge leachate increased after bioleaching. The EPS ratio of loosely bound fraction to tightly bound fraction exhibited an upward trend followed with a downward trend, which indicated that large quantities of bacteria were at accelerated growth phase during the prophase of bioleaching while at deceleration growth phase during the anaphase of bioleaching. The content of

  6. Heterotrophic Bioleaching of Sulfur, Iron, and Silicon Impurities from Coal by Fusarium oxysporum FE and Exophiala spinifera FM with Growing and Resting Cells.

    Science.gov (United States)

    Etemadzadeh, Shekoofeh Sadat; Emtiazi, Giti; Etemadifar, Zahra

    2016-06-01

    Coal is the most abundant fossil fuel containing sulfur and other elements which promote environmental pollution after burning. Also the silicon impurities make the transportation of coal expensive. In this research, two isolated fungi from oil contaminated soil with accessory number KF554100 (Fusarium oxysporum FE) and KC925672 (Exophiala spinifera FM) were used for heterotrophic biological leaching of coal. The leaching were detected by FTIR, CHNS, XRF analyzer and compared with iron and sulfate released in the supernatant. The results showed that E. spinifera FM produced more acidic metabolites in growing cells, promoting the iron and sulfate ions removal while resting cells of F. oxysporum FE enhanced the removal of aromatic sulfur. XRF analysis showed that the resting cells of E. spinifera FM proceeded maximum leaching for iron and silicon (48.8, 43.2 %, respectively). CHNS analysis demonstrated that 34.21 % of sulfur leaching was due to the activities of resting cells of F. oxysporum FE. Also F. oxysporum FE removed organic sulfur more than E. spinifera FM in both growing and resting cells. FTIR data showed that both fungi had the ability to remove pyrite and quartz from coal. These data indicated that inoculations of these fungi to the coal are cheap and impurity removals were faster than autotrophic bacteria. Also due to the removal of dibenzothiophene, pyrite, and quartz, we speculated that they are excellent candidates for bioleaching of coal, oil, and gas.

  7. DEVELOPMENT OF TECHNOLOGIES AND ANALYTICAL CAPABILITIES FOR VISION 21 ENERGY PLANTS

    Energy Technology Data Exchange (ETDEWEB)

    Madhava Syamlal, Ph.D.`

    2001-04-20

    The project management plan was finalized during a project kick off meeting held on January 16, 2001 in Lebanon, NH, which was attended by all project participants. The project management plan was submitted to DOE and was revised based on comments from DOE (Task 1.0). A survey of the potential users of the integrated software was conducted. A web-based survey form was developed and was announced in the ProcessCity discussion forum and in AspenTech's e-mail digest Aspen e-Flash. Several Fluent clients were individually contacted. A user requirements document was written (Task 2.2). As a prototype of AspenPlus-Fluent integration, the flowsheet for allyl alcohol production via the isomerization of propylene oxide was developed. A stirred tank reactor in the flowsheet for converting the byproduct acetone into n-propyl propionate was modeled with Fluent, version 5.4. The convergence of the AspenPlus-Fluent integrated model was demonstrated, and a list of data exchanges required between AspenPlus and Fluent was developed (Task 2.6). As the first demonstration case, the RP and L power plant was selected. A planning meeting was held on February 13, 2001 in Cambridge, MA to discuss this demonstration case. It was decided that the steam-side of the power plant would be modeled with AspenPlus and the gas-side, with the ALSTOM Power in-house code INDVU. A flowsheet model of the power plant was developed (Task 3.1). Three positive responses were received for the invitation to join the project Advisory Board. It was decided to expand the membership on the Advisory Board to include other industrial users interested in integrating AspenPlus and Fluent. Additional invitations were sent out (Task 5.0). Integraph's role in the project was restructured based on discussions among the project participants. Fluent hired Dr. Maxwell Osawe to work on the project. Dr. Osawe brings to the project a unique combination of skills (expertise in CFD and object-oriented design and

  8. Copper, zinc, and iron bioleaching from polymetallic sulphide concentrate%多金属硫化精矿中铜、锌和铁的生物浸出

    Institute of Scientific and Technical Information of China (English)

    Vesna T. CONIĆ; Mirjana M. RAJČIĆ VUJASINOVIĆ; Vlastimir K. TRUJIĆ; Vladimir B. CVETKOVSKI

    2014-01-01

    Bioleaching of low-grade complex Cu−Zn−Pb−Fe−Ag−Au sulphide concentrate (of Majdanpek ore body, RTB Bor, Serbia) was carried out in an aerated bioleach reactor in the presence of mesophilic mixed bacterial culture ofAcidithiobacillus ferrooxidans,Acidithiobacillus thiooxidans, andLeptospirillum ferrooxidans. A mesophilic acidophiles culture was isolated from the acidic solution of the underground copper mine of Bor, Serbia. The nutrient medium was 9K at pH 1.6. 87% of the particles were<10 µm in size, with a pulp density of 8% (w/v). Bioleaching efficiencies of 89% for zinc, 83% for copper, and 68% for iron can be achieved in the examined conditions. Kinetic analysis shows that the change in leaching corresponds to the Spencer-Topley kinetic model for diffusion-controlled topochemical reactions.%利用嗜温混合菌Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans和 Leptospirillum ferrooxidans对低品位复杂Cu−Zn−Pb−Fe−Ag−Au硫化精矿在曝气生物浸出反应器中进行生物浸出。该菌种为从塞尔维亚Bor地下铜矿的酸性溶液中筛选出一种嗜热嗜酸菌。营养液为pH 1.6的9K营养液。87%的矿物粒度大于10μm,矿浆密度为8%(w/v)。在测试条件下,锌、铜和铁的浸出率分别达到89%、83%和68%。动力学分析表明,浸出过程与Spencer-Topley模型相符,受局部反应扩散控制。

  9. Surface species of chalcopyrite during bioleaching by moderately thermophilic bacteria%中度嗜热菌浸出黄铜矿过程表面产物解析

    Institute of Scientific and Technical Information of China (English)

    赵红波; 王军; 覃文庆; 郑细华; 陶浪; 甘晓文; 邱冠周

    2015-01-01

    采用X射线衍射(XRD)与X射线光电子能谱(XPS)研究黄铜矿在中度嗜热菌浸出过程中的表面产物变化。结果表明,在A. caldus,S. thermosulfidooxidans与L. ferriphilum浸出过程中,一硫化物(CuS)、二硫化物(S22−)、元素硫(S0)、多硫化物(Sn2−)与硫酸盐(SO42−)是黄铜矿表面的主要产物。在A. caldus浸出黄铜矿过程速率较慢,这主要是由于黄铜矿的不完全溶解产生多硫化物,限制了进一步的溶解。在S. thermosulfidooxidans与L. ferriphilum浸出黄铜矿过程中,多硫化物与黄钾铁矾是钝化膜的主要成分。元素硫不是导致黄铜矿生物冶金过程钝化的主要物质。%X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses were carried out to investigate the surface species and interfacial reactions during bioleaching of chalcopyrite by different strains of moderately thermophilic bacteria (45 °C). Results show that monosulfide (CuS), disulfide (S22−), polysulfide (Sn2−), elemental sulfur (S0) and sulfate (SO42−) are the main intermediate species on the surface of chalcopyrite during bioleaching byA. caldus,S. thermosulfidooxidans andL. ferriphilum. The low kinetics of dissolution of chalcopyrite inA. caldus can be mainly attributed to the incomplete dissolution of chalcopyrite and the passivation layer of polysulfide. Polysulfide and jarosite should be mainly responsible for the passivation of chalcopyrite in bioleaching byL. ferriphilumorS. thermosulfidooxidans. However, elemental sulfur should not be the main composition of passivation layer of chalcopyrite during bioleaching.

  10. Biomining: metal recovery from ores with microorganisms.

    Science.gov (United States)

    Schippers, Axel; Hedrich, Sabrina; Vasters, Jürgen; Drobe, Malte; Sand, Wolfgang; Willscher, Sabine

    2014-01-01

    Biomining is an increasingly applied biotechnological procedure for processing of ores in the mining industry (biohydrometallurgy). Nowadays the production of copper from low-grade ores is the most important industrial application and a significant part of world copper production already originates from heap or dump/stockpile bioleaching. Conceptual differences exist between the industrial processes of bioleaching and biooxidation. Bioleaching is a conversion of an insoluble valuable metal into a soluble form by means of microorganisms. In biooxidation, on the other hand, gold is predominantly unlocked from refractory ores in large-scale stirred-tank biooxidation arrangements for further processing steps. In addition to copper and gold production, biomining is also used to produce cobalt, nickel, zinc, and uranium. Up to now, biomining has merely been used as a procedure in the processing of sulfide ores and uranium ore, but laboratory and pilot procedures already exist for the processing of silicate and oxide ores (e.g., laterites), for leaching of processing residues or mine waste dumps (mine tailings), as well as for the extraction of metals from industrial residues and waste (recycling). This chapter estimates the world production of copper, gold, and other metals by means of biomining and chemical leaching (bio-/hydrometallurgy) compared with metal production by pyrometallurgical procedures, and describes new developments in biomining. In addition, an overview is given about metal sulfide oxidizing microorganisms, fundamentals of biomining including bioleaching mechanisms and interface processes, as well as anaerobic bioleaching and bioleaching with heterotrophic microorganisms.

  11. 硫杆菌浸出低品位镍铜硫化矿%Bioleaching of Low-grade Ni-Cu Sulfide Ore

    Institute of Scientific and Technical Information of China (English)

    陈泉军; 方兆珩

    2001-01-01

    阐述了氧化亚铁硫杆菌(TF5)和氧化硫硫杆菌(TT)在摇瓶中浸出金川低品位含钴、镍、铜硫化矿的工艺条件实验. 结果表明,浸出过程的pH值应控制在2.0左右;细菌的接种量应控制在3.0′109个/ml左右;低矿浆浓度有利于浸出的进行;氧化亚铁硫杆菌和氧化硫硫杆菌混合浸出,以2:1的比例混合比1:1的比例浸出率要高.%Bioleaching of low-grade Ni-Cu sulfide ore from Jin-chuan with thiobacillus ferrooxidans (TF5) and thiobacillus thiooxidans (TT) is investigated. The effect of pH, inoculation, pulp density on leaching is presented. The leaching process inoculated with different blend of TF5 and TT is also examined. These experiments confirm that the leaching pH should be controlled at about 2.0, the best inoculation quantity 3.0′109 cells/ml, low pulp density is more favorable for leaching, and the extraction of nickel is increased by inoculation with the blend of TF5 and TT.

  12. Bioleaching of metal from municipal waste incineration fly ash using a mixed culture of sulfur-oxidizing and iron-oxidizing bacteria.

    Science.gov (United States)

    Ishigaki, Tomonori; Nakanishi, Akane; Tateda, Masafumi; Ike, Michihiko; Fujita, Masanori

    2005-08-01

    We investigated the behavior and characteristics of metal leaching from municipal solid waste incineration (MSWI) fly ash among pure cultures of a sulfur-oxidizing bacterium (SOB) and an iron-oxidizing bacterium (IOB) and a mixed culture. The IOB has a high metal-leaching ability, though its tolerability against the ash addition is low. The SOB might better tolerate an increase in ash addition than the IOB, though metal leaching ability of the SOB is limited. Mixed culture could compensate for these deficiencies, and high metal leachability was exhibited in the 1% ash culture, i.e., 67% and 78% of leachabilities for Cu and Zn, respectively, and 100% for Cr and Cd. Furthermore, comparably high leachabilities such as 42% and 78% for Cu and Zn were observed even in the 3% ash cultures. Characterization of metal leaching by the mixed culture revealed that the acidic and oxidizing condition had remained stable thorough the experimental period. Ferric iron remained in the mixed culture, and the metal leaching was enhanced by redox mechanisms coupling with the leaching by sulfate. An increase of ferrous iron enhanced the Cr, Cu, and As leaching. The optimum concentration of sulfur existed for As and Cr (5 gl(-1)) and Cu (2 gl(-1)). The presence of the degradable and non-degradable organic compound that must be existed in the natural environment or waste landfills made no significant change in the leachability of metals other than Zn. These results suggested that bioleaching using a mixed culture of SOB and IOB is a promising technology for recovering the valuable metals from MSWI fly ash.

  13. Continuous plant cell perfusion culture: bioreactor characterization and secreted enzyme production.

    Science.gov (United States)

    Su, Wei Wen; Arias, Renee

    2003-01-01

    Culture perfusion is widely practiced in mammalian cell processes to enhance secreted antibody production. Here, we report the development of an efficient continuous perfusion process for the cultivation of plant cell suspensions. The key to this process is a perfusion bioreactor that incorporates an annular settling zone into a stirred-tank bioreactor to achieve continuous cell/medium separation via gravitational sedimentation. From washout experiments, we found that under typical operating conditions (e.g., 200 rpm and 0.3 vvm) the liquid phase in the entire perfusion bioreactor was homogeneous despite the presence of the cylindrical baffle. Using secreted acid phosphatase (APase) produced in Anchusa officinalis cell culture as a model we have studied the perfusion cultures under complete or partial cell retention. The perfusion culture was operated under phosphate limitation to stimulate APase production. Successful operation of the perfusion process over four weeks has been achieved in this work. When A. officinalis cells were grown in the perfusion reactor and perfused at up to 0.4 vvd with complete cell retention, a cell dry weight exceeding 20 g/l could be achieved while secreted APase productivity leveled off at approximately 300 units/l/d. The culture became extremely dense with the maximum packed cell volume (PCV) surpassing 70%. In comparison, the maximum cell dry weight and overall secreted APase productivity in a typical batch culture were 10-12 g/l and 100-150 units/l/d, respectively. Operation of the perfusion culture under extremely high PCV for a prolonged period, however, led to declined oxygen uptake and reduced viability. Subsequently, cell removal via a bleed stream at up to 0.11 vvd was tested and shown to stabilize the culture at a PCV below 60%. With culture bleeding, both specific oxygen uptake rate and viability were shown to increase. This also led to a higher cell dry weight exceeding 25 g/l, and further improvement of secreted APase

  14. 复合硫杆菌生物淋滤对Mn去除的研究%Study on Mn Removal by Composite Thiobacillus Bioleaching

    Institute of Scientific and Technical Information of China (English)

    霍金枝; 张弛; 王增长

    2012-01-01

    By use of composite Thiobacillus (Thiobacillus ferrooxidans and Thiobacillus thiooxidans) at different inoculum quantity (5%,10%,20%) for municipal sludge bioleaching experiments, it investigated the changes of pH and redox potential (ORP) 、 leaching effects on Mn and Mn form variation during the process.The results showed that: the method could leach Mn out of the sludge effectively .After 12 days, the leaching out rate of Mn in reactor reached 100% under 10% inoculation rate. Leaching out rate of Mn was affected by pH and ORP, and the relationship was that the leaching out rate was 2.439-0.452pH-0.002ORP, changes of the exchangeable form and the residual form of Mn were great, the morphological changes indicated that Mn was leaching out effectively; the leaching abilities of various forms of Mn were as follow: carbonate bound> Fe-Mn oxides bound > residual fraction> organic bound.%通过利用复合硫杆菌(氧化亚铁硫杆菌和氧化硫硫杆菌)在不同接种量(5%,10%,20%)对市政污泥进行生物淋滤实验,探讨了淋滤过程中pH和氧化还原电位( ORP)、Mn的淋滤效果及淋滤过程中其形态的变化.结果表明:该方法能有效淋出污泥中的Mn,生物淋滤12d后,10%接种量反应器Mn的淋出率达到100%; Mn的淋出率受pH和ORP的双重影响,与pH和ORP的关系为:淋出率等于2.439-0.452pH-0.0020RP;各形态中Mn的可交换态和残渣态变化幅度大,从形态变化上表明该淋滤反应对Mn具有有效的淋出;Mn各形态的淋滤能力是:碳酸盐结合态>铁锰氧化物结合态>残渣态>有机物结合态.

  15. 嗜酸菌对废旧印刷线路板金属铜的浸出研究%Research of Bio-leaching Cu from Printed-circuit Board by Acidophilus Strains

    Institute of Scientific and Technical Information of China (English)

    赵德龙; 谌书; 王中琪

    2012-01-01

    选用嗜酸性氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans,简称T.f)、氧化硫硫杆菌(Thiobacillus thiooxidans,简称T.t)作为实验菌种研究其对线路板(Printed circuit board)粉金属铜的浸出;试验以单一菌种、混合菌种、无菌培养基及酸性蒸馏水进行浸出实验研究,通过对比不同条件下的浸出效果,得出单一氧化亚铁硫杆菌(T.f)的浸出效果最好,浸出率达到92.1%.通过对浸出过程中pH、ORP及Fe2+、Fe3+变化分析,发现Fe3+的氧化作用在铜的浸出过程中起主导作用,酸浸也有一定的贡献;对浸出后残余的PCB进行XRD及SEM观察分析发现,PCB组成成分中含有大量的酚烃、苯酚及邻、对位取代酚以及少量的长链烷烃及其脂肪烃,此类有机物在浸出过程中均与细菌或其代谢物发生了作用.%Two acidophilic strains, i.e, Acidithiobacillus ferrooxidans and Thiobacillus thiooxidans, were used to extract copper from the powder of printed circuit board (PCB). The experiment was conducted using different single strains and mixed bacteria, compared with others showing, the leaching behavior of, single Acidithiobacillus ferrooxidans was the best with leaching rate up to 92.1%. It was found that oxidation of Fe3+ was essential in bio-leaching of copper, and some organic compounds remained in PCB residues after the bio-leaching treatment, such as phenol hydrocarbons, phenol and osubstituted phenol and a small amount of long-chain alkanes and aliphatic hydrocarbons, with which the bacteria and their metabolites had reacted during the bio-leaching process.

  16. Optimization of plant mineral nutrition under growth-limiting conditions in a lunar greenhouse

    Science.gov (United States)

    Zaets, I.; Voznyuk, T.; Kovalchuk, M.; Rogutskyy, I.; Lukashov, D.; Mytrokhyn, O.; Mashkovska, S.; Foing, B.; Kozyrovska, N.

    It may be assumed that the first plants in a lunar base will play a main role in forming a protosoil of acceptable fertility needed for purposively growing second generation plants like wheat, rice, tulips, etc. The residues of the first-generation plants could be composted and transformed by microorganisms into a soil-like substrate within a loop of regenerative life support system. The lunar regolith may be used as a substrate for plant growth at the very beginning of a mission to reduce its cost. The use of microbial communities for priming plants will allow one to facilitate adaption to stressful conditions and to support the plant development under growth limiting conditions. Well-defined plant-associated bacteria were used for growing three cultivars to colonize French marigold (Tagetes patula L.) in anorthosite, a substrate of low bioavailability, analogous to a lunar rock. The consortium was composed of plant growth promoting rhizobacteria and the bacterium Paenibacillus sp. IMBG156 which stimulated seed germination, better plant development, and finally, the flowering of inoculated tagetes. In contrast, control plants grew poorly in the anorthosite and practically did not survive until flowering. Analysis of bacterial community composition showed that all species colonized plant roots, however, the rate of colonization depended on the allelopatic characteristics of marigold varieties. Bacteria of consortium were able to liberate some elements (Ca, Fe, Mn, Si, Ni, Cu, Zn) from substrate anorthosite. Plant colonization by mixed culture of bacterial strains resulted in the increase of accumulation of K, Mg, Mn by the plant and in the lowering of the level of toxic metal accumulation. It was assumed that a rationally assembled consortium of bacterial strains promoted germination of marygold seeds and supported the plant development under growth limiting conditions by means of bioleaching plant essential nutritional elements and by protecting the plant against

  17. THE INFLUENCE OF VARIOUS METALLIC IONS ON THE BIOLEACHING OF COMPLEX METAL SULPHIDES%金属离子对细菌浸出复杂金属硫化矿的影响

    Institute of Scientific and Technical Information of China (English)

    蒋金龙; 汪模辉; 王康林

    2001-01-01

    研究了金属催化离子Ag+,Hg2+,Bi3+对细菌浸出复杂金属硫化矿的影响。发现Ag+ 能极大的提高金属浸出率,将Cu的浸出率从30.27%提高到99.99%,钴的浸出率从19.10%提高到31.79%。三种金属对Cu浸出的影响大小顺序为Ag+>Hg2+>Bi3+,对Co浸出的影响大小顺序为Ag+>Bi3+>Hg2+。催化离子浸出效果的差异主要是由于催化离子毒性对细菌生长影响造成的。%This paper studies the catalytic effect of various metallic ions (Ag+, Bi3+, Hg2+) in the bioleaching of complex metal sulphides. The cations studied increase the copper and cobalt dissolution from complex metal sulphides, and Ag+ is prominent with an extraction efficiency of 99.99% and 31.79%, respectively, compared with 30.27% and 19.10% recovery in the absence of a catalyst. The order of influence of different cations on the final recovery of Cu from the ore is Ag+> Hg2+> Bi3+. However, it is Ag+> Bi3+> Hg2+ for Co. The difference of the catalytic effect of metallic ions (Ag+, Bi3+, Hg2+) in the bioleaching is because the poison of metallic ions affects the living of bacteria.

  18. Influence of phenylacetic acid pulses on anaerobic digestion performance and archaeal community structure in WWTP sewage sludge digesters

    NARCIS (Netherlands)

    Cabrol, L.; Urra, J.; Rosenkranz, F.; Kroff, P.A.; Plugge, C.M.; Lesty, Y.; Chamy, R.

    2015-01-01

    The effect of phenylacetic acid (PAA) pulses on anaerobic digestion (AD) performance and archaeal community structure was evaluated in anaerobic digesters treating sewage sludge from a wastewater treatment plant (WWTP). Four pilot-scale continuous stirred tank reactors were set up at a full-scale

  19. Influence of phenylacetic acid pulses on anaerobic digestion performance and archaeal community structure in WWTP sewage sludge digesters

    NARCIS (Netherlands)

    Cabrol, L.; Urra, J.; Rosenkranz, F.; Kroff, P.A.; Plugge, C.M.; Lesty, Y.; Chamy, R.

    2015-01-01

    The effect of phenylacetic acid (PAA) pulses on anaerobic digestion (AD) performance and archaeal community structure was evaluated in anaerobic digesters treating sewage sludge from a wastewater treatment plant (WWTP). Four pilot-scale continuous stirred tank reactors were set up at a full-scale mu

  20. Synthesis and properties of ternary (K, NH{sub 4}, H{sub 3}O)-jarosites precipitated from Acidithiobacillus ferrooxidans cultures in simulated bioleaching solutions

    Energy Technology Data Exchange (ETDEWEB)

    Sandy Jones, F.; Bigham, Jerry M. [School of Environment and Natural Resources, Ohio State University, 2021 Coffey Road, Columbus, OH 43210 (United States); Gramp, Jonathan P. [Department of Microbiology, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210 (United States); Tuovinen, Olli H., E-mail: tuovinen.1@osu.edu [Department of Microbiology, Ohio State University, 484 West 12th Avenue, Columbus, OH 43210 (United States)

    2014-11-01

    The purpose of this study was to synthesize a series of solid solution jarosites by biological oxidation of ferrous iron at pH 2.2–4.4 and ambient temperature in media containing mixtures of K{sup +} (0, 1, 4, 6, 12, 31 mM) and NH{sub 4}{sup +} (6.1, 80, 160, 320 mM). The starting material was a liquid medium for Acidithiobacillus ferrooxidans comprised of 120 mM FeSO{sub 4} solution and mineral salts at pH 2.2. Following inoculation with A. ferrooxidans, the cultures were incubated in shake flasks at 22 °C. As bacteria oxidized ferrous iron, ferric iron hydrolyzed and precipitated as jarosite-group minerals (AFe{sub 3}(SO{sub 4}){sub 2}(OH){sub 6}) and/or schwertmannite (idealized formula Fe{sub 8}O{sub 8}(OH){sub 6}(SO{sub 4})·nH{sub 2}O). The precipitates were characterized by X-ray diffraction (XRD), elemental analysis, and Munsell color. Schwertmannite was the dominant mineral product at low combinations of K{sup +} (≤ 4 mM) and NH{sub 4}{sup +} (≤ 80 mM) in the media. At higher single or combined concentrations, yellowish jarosite phases were produced, and Munsell hue provided a sensitive means of detecting minor schwertmannite in the oxidation products. Although the hydrated ionic radii of K{sup +} and NH{sub 4}{sup +} are similar, K{sup +} greatly facilitated the formation of a jarosite phase compared to NH{sub 4}{sup +}. Unit cell and cell volume calculations from refinements of the powder XRD patterns indicated that the jarosite phases produced were mostly ternary (K, NH{sub 4}, H{sub 3}O)-solid solutions that were also deficient in structural Fe, especially at low NH{sub 4} contents. Thus, ferric iron precipitation from the simulated bioleaching systems yielded solid solutions of jarosite with chemical compositions that were dependent on the relative concentrations of K{sup +} and NH{sub 4}{sup +} in the synthesis media. No phase separations involving discrete, end-member K-jarosite or NH{sub 4}-jarosite were detected in the un-aged precipitates

  1. Removal of Heavy Metals from Activated Sludge by Bioleaching Method%污泥中重金属的生物淋滤

    Institute of Scientific and Technical Information of China (English)

    邱并生

    2010-01-01

    生物淋滤法(Bioleaching)是指利用自然界中一些微生物(硫细菌)的直接作用或其代谢产物的间接作用,产生氧化、还原、络合、吸附或溶解反应,将固相中某些不溶性成分(如重金属、硫及其他金属)分离浸提出来的技术.在生物淋滤中,嗜酸性氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans,A.f)和嗜酸性氧化硫硫杆菌(Acidithiobacillus thiooxidans,A.f)被用作有效的淋滤载体[1].这种嗜酸性的化能自养型细菌以大气中的CO2为碳源,以无机物铁或硫为能源来维持生长,不需要提供外来的碳源和电子供体.另外,由于pH值很低,抑制了其他细菌的生长,所以在实际的操作过程中不需要严格的无菌条件.氧化亚铁硫杆菌和氧化硫硫杆菌去除重金属适宜于污水处理厂的开放系统,采用土著嗜酸性氧化亚铁硫杆菌(A.f)和氧化硫硫杆菌(A.f)进行重金属去除.也就是说,处理什么地方的污泥,就在什么地方分离A.f和A.t,这样分离的微生物在生物淋滤过程中能发挥较好的作用.这也是微生物在自然界生长繁殖的特点之一. 本期介绍了王聪、宋存江等[2]从剩余活性污泥中分离得到两株土著硫杆菌,对两株菌进行了分类鉴定,确定二者分别为嗜酸性氧化亚铁硫杆菌杆(Acidithiobacillus ferrooxidans,A.f)和嗜酸性氧化硫硫杆菌(Acidithiobacillus thiooxidans,A.t),将二者的单菌和混合菌分别接种于剩余活性污泥中,进行了为期9 d的生物淋滤,对淋滤过程中的pH变化、氧化还原电位(ORP)以及重金属含量进行了检测.结果表明,生物淋滤9 d的混合菌对于As、Cr、Cu、Ni和Zn的去除效果最好,去除率分别达到了96.09%、93.47%、98.32%、97.88%和98.60%.混合菌生物淋滤对于Cd和Pb的去除率在第6天之后迅速下降,但是A.t单菌淋滤保持较高的去除率,此结果为进一步的应用打下了良好的基础.

  2. Acquired changes in stomatal characteristics in response to ozone during plant growth and leaf development of bush beans (Phaseolus vulgaris L.) indicate phenotypic plasticity

    Energy Technology Data Exchange (ETDEWEB)

    Elagoez, Vahram [Plant Biology Graduate Program, University of Massachusetts, Amherst, MA 01003 (United States)]. E-mail: velagoz@nsm.umass.edu; Han, Susan S. [Department of Plant, Soil and Insect Sciences, University of Massachusetts, Amherst, MA 01003 (United States); Manning, William J. [Department of Plant, Soil and Insect Sciences, University of Massachusetts, Amherst, MA 01003 (United States)

    2006-04-15

    Bush bean (Phaseolus vulgaris L.) lines 'S156' (O{sub 3}-sensitive)/'R123' (O{sub 3}-tolerant) and cultivars 'BBL 290' (O{sub 3}-sensitive)/'BBL 274' (O{sub 3}-tolerant) were used to study the effects of O{sub 3} on stomatal conductance (g {sub s}), density, and aperture size on leaf and pod surfaces with the objective of establishing links between the degree of plant sensitivity to O{sub 3} and plasticity of stomatal properties in response to O{sub 3}. Studies in open-top chambers (OTCs) and in continuously stirred tank reactors (CSTRs) established a clear relationship between plant developmental stages, degrees of O{sub 3} sensitivity and g {sub s}: while 'S156' had higher g {sub s} rates than 'R123' earlier in development, similar differences between 'BBL 290' and 'BBL 274' were observed at later stages. G {sub s} rates on the abaxial leaf surfaces of 'S156' and 'BBL 290', accompanied by low leaf temperatures, were significantly higher than their O{sub 3}-tolerant counterparts. Exposure to O{sub 3} in CSTRs had greater and more consistent impacts on both stomatal densities and aperture sizes of O{sub 3}-sensitive cultivars. Stomatal densities were highest on the abaxial leaf surfaces of 'S156' and 'BBL 290' at higher O{sub 3} concentrations (60 ppb), but the largest aperture sizes were recorded on the adaxial leaf surfaces at moderate O{sub 3} concentrations (30 ppb). Exposure to O{sub 3} eliminated aperture size differences on the adaxial leaf surfaces between sensitive and tolerant cultivars. Regardless of sensitivity to O{sub 3} and treatment regimes, the smallest aperture sizes and highest stomatal densities were found on the abaxial leaf surface. Our studies showed that O{sub 3} has the potential to affect stomatal plasticity and confirmed the presence of different control mechanisms for stomatal development on each leaf surface. This

  3. Use of Model-Based Nutrient Feeding for Improved Production of Artemisinin by Hairy Roots of Artemisia Annua in a Modified Stirred Tank Bioreactor.

    Science.gov (United States)

    Patra, Nivedita; Srivastava, Ashok K

    2015-09-01

    Artemisinin has been indicated to be a potent drug for the cure of malaria. Batch growth and artemisinin production kinetics of hairy root cultures of Artemisia annua were studied under shake flask conditions which resulted in accumulation of 12.49 g/L biomass and 0.27 mg/g artemisinin. Using the kinetic data, a mathematical model was identified to understand and optimize the system behavior. The developed model was then extrapolated to design nutrient feeding strategies during fed-batch cultivation for enhanced production of artemisinin. In one of the fed-batch cultivation, sucrose (37 g/L) feeding was done at a constant feed rate of 0.1 L/day during 10-15 days, which led to improved artemisinin accumulation of 0.77 mg/g. The second strategy of fed-batch hairy root cultivation involved maintenance of pseudo-steady state sucrose concentration (20.8 g/L) during 10-15 days which resulted in artemisinin accumulation of 0.99 mg/g. Fed-batch cultivation (with the maintenance of pseudo-steady state of substrate) of Artemisia annua hairy roots was, thereafter, implemented in bioreactor cultivation, which featured artemisinin accumulation of 1.0 mg/g artemisinin in 16 days of cultivation. This is the highest reported artemisinin yield by hairy root cultivation in a bioreactor.

  4. 连续搅拌反应釜的非线性H∞控制%Nonlinear H∞ control of continuous stirred tank reactor

    Institute of Scientific and Technical Information of China (English)

    韩光信; 王立国; 杨世儒; 翟玉文; 王庆伟

    2003-01-01

    以连续搅拌反应釜(CSTR)为例,研究了非线性系统存在控制量约束时的H∞控制问题,基于Hamilton-Jacobi不等式,得到了系统的L2增益有限的充分条件,在这个条件下,得到了使闭环系统满足H∞扰动衰减性能准则的状态反馈控制器.

  5. Linear analysis on continuous stirred tank reactor non-linear model%CSTR模型中非线性因素线性化的分析

    Institute of Scientific and Technical Information of China (English)

    王宗刚; 史军; 刘春元

    2012-01-01

    针对目前化工过程中常包含的带有加热的CSTR装置以实验为主建立一种包括容积平衡和热平衡方程的数据和机理相结合的模型,对由加热元件本身体积导致的容积与液位的非线性关系做了详细分析,在两个稳态工作点得出了线性化的状态空间和传递函数模型,通过对基础模型的开、闭环测试和扰动测试,在slmulink中仿真验证了模型的正确性.

  6. A Hybrid Supervised Learning Control of Continuous Stirred Tank Reactor%连续搅拌反应釜的混合监督学习控制

    Institute of Scientific and Technical Information of China (English)

    杨东勇; 许力; 蒋静坪

    2001-01-01

    提出了一种连续搅拌反应釜(CSTR)的混合监督学习控制方法.控制系统有远程控制与极值控制两种模式.极值控制时神经网络进行有监督的学习,远程控制时神经网络进行无监督的学习.控制系统的设计不需要CSTR系统的精确模型.仿真实验结果表明,所提出的混合控制方案具有满意的动态和稳态控制性能,并有很强的自适应性.

  7. 连续搅拌反应釜浓度的滚动时域估计%Moving Horizon Estimation of Concentrations in a Continuous Stirred Tank Reactor

    Institute of Scientific and Technical Information of China (English)

    陈虹; 邹卫平; 孙鹏远

    2001-01-01

    化学组分浓度大于零以及反应釜的进料温度和浓度等在给定范围内波动对估计问题来说是以约束形式出现的附加已知信息.本文基于预测控制的滚动优化原理,讨论了一种能利用这些已知约束信息来提高估计的合理性与准确性的滚动时域估计方法.最后给出了对CSTR系统的仿真结果并与Kalman估计进行了比较.

  8. Data Pre-Processing Method to Remove Interference of Gas Bubbles and Cell Clusters During Anaerobic and Aerobic Yeast Fermentations in a Stirred Tank Bioreactor

    Science.gov (United States)

    Princz, S.; Wenzel, U.; Miller, R.; Hessling, M.

    2014-11-01

    One aerobic and four anaerobic batch fermentations of the yeast Saccharomyces cerevisiae were conducted in a stirred bioreactor and monitored inline by NIR spectroscopy and a transflectance dip probe. From the acquired NIR spectra, chemometric partial least squares regression (PLSR) models for predicting biomass, glucose and ethanol were constructed. The spectra were directly measured in the fermentation broth and successfully inspected for adulteration using our novel data pre-processing method. These adulterations manifested as strong fluctuations in the shape and offset of the absorption spectra. They resulted from cells, cell clusters, or gas bubbles intercepting the optical path of the dip probe. In the proposed data pre-processing method, adulterated signals are removed by passing the time-scanned non-averaged spectra through two filter algorithms with a 5% quantile cutoff. The filtered spectra containing meaningful data are then averaged. A second step checks whether the whole time scan is analyzable. If true, the average is calculated and used to prepare the PLSR models. This new method distinctly improved the prediction results. To dissociate possible correlations between analyte concentrations, such as glucose and ethanol, the feeding analytes were alternately supplied at different concentrations (spiking) at the end of the four anaerobic fermentations. This procedure yielded low-error (anaerobic) PLSR models for predicting analyte concentrations of 0.31 g/l for biomass, 3.41 g/l for glucose, and 2.17 g/l for ethanol. The maximum concentrations were 14 g/l biomass, 167 g/l glucose, and 80 g/l ethanol. Data from the aerobic fermentation, carried out under high agitation and high aeration, were incorporated to realize combined PLSR models, which have not been previously reported to our knowledge.

  9. Reactor models for a series of continuous stirred tank reactors with a gas-liquid-solid leaching system: Part II. Gas-transfer control

    Science.gov (United States)

    Papangelakis, V. G.; Demopoulos, G. P.

    1992-12-01

    This article is the second in a three-article series devoted to the development of comprehensive three-phase steady-state reactor models. In this article in particular, model equations are developed for the case of a leaching reactor operating under pure gas-transfer control. That is, the transfer of a gaseous reactant at the g-1 interface is considered to be the controlling step of the process rather than the particle dissolution reaction itself. For the derivation of the appropriate model equations, the gas-transfer capacity of the reactor is coupled with the particle dissolution kinetics. Two model versions are developed. In model version 1, the dissolved gas is assumed to be distributed equally among all particles. On the basis of this assumption, a gastransfer control-shrinking core model (GTC-SCM) equation is formulated which, along with the segregated flow model, helps to calculate the conversion of the solid phase. The size distribution of the particles at the exit of the reactor is computed via a mass-particle size density (PSD) function derived with the use of the population balance model (PBM). In model version 2, the dissolved gas is assumed to be distributed among particles in proportion to their surface area. Using the PBM, equations are developed suitable for the calculation of the total specific surface area of the reacting solids and their conversion. Single as well as multiple parallel leaching reactions are considered in developing the two model versions.

  10. Reactor models for a series of continuous stirred tank reactors with a gas-liquid-solid leaching system: Part III. Model application

    Science.gov (United States)

    Papangelakis, V. G.; Demopoulos, G. P.

    1992-12-01

    A mathematical model developed to describe the steady-state performance of a three-phase leaching reactor is applied to the analysis and simulation of an industrial process: the high-temperature (180 °C to 200 °C) aqueous pressure oxidation (O2-H2SO4) of refractory pyrite-arsenopyrite (FeS2-FeAsS) gold concentrates. The simulation work reported here centers on the analysis of the autothermal operation of a continuous multistage horizontal autoclave. The focus is on the performance of the first autoclave compartment, since its autothermal “initialization” determines the rate of the whole process. The analysis of the whole autoclave is subsequently done on a stage-by-stage basis. The model considers both possible reaction control regimes, that is, reactor operation limited by the rate of the particle dissolution reaction (surface reaction control) or limited by the rate of O2 transfer at the g-1 interface (gas-transfer control). The decision whether the reactor operates under surface reaction control or gas transfer control is based on whether the gas-transfer capacity of the reactor can or cannot satisfy the oxygen demands of the leaching reactions. With the aid of the model, the effects of feed rate, feed preheating, cooling with water injection, slurry recycling, and autoclave configuration are critically evaluated from the standpoint of optimum autoclave performance.

  11. 基于ESN网络的连续搅拌反应釜(CSTR)辨识%Identification of Continuous Stirred Tank Reactor Based on Echo State Network

    Institute of Scientific and Technical Information of China (English)

    李晓华; 李军

    2014-01-01

    针对以往递归神经网络(RNN)训练算法难,连续搅拌反应釜(CSTR)的强非线性等问题,将回声状态网络(echo state network,ESN)方法应用于模型不确定的CSTR系统辨识中.ESN具有较强的非线性逼近能力和良好的短期记忆能力,且只需要训练网络输出权值,简化了网络训练算法.仿真结果表明,在相同条件下,与带动量的BP(back propagation)神经网络、BP-MLP(back propagation multilayer perceptron)神经网络、最小二乘支持向量机(LS-SVM)、模糊神经网络(FNN)、GAP-RBF神经网络、MGAP-RBF神经网络相比,ESN能给出相当好的性能,表现出较高的辨识精度,ESN比带动量的BP、BP-MLP、LS-SVM神经网络的逼近精度提高了4个数量级,表明了该方法的有效性.

  12. pH-control modes in a 5-L stirred-tank bioreactor for cell biomass and exopolysaccharide production by Tremella fuciformis spore.

    Science.gov (United States)

    Zhu, Hu; Cao, Chunxu; Zhang, Shuaishuai; Zhang, Yan; Zou, Weisheng

    2011-10-01

    The effect of pH-control modes on cell growth and exopolysaccharide production by Tremella fuciformis was evaluated in a 5-L bioreactor. The results show that the maximal dry cell weight (DCW) and exopolysaccharide production were 23.57 and 4.48 g L⁻¹ in pH-stat fermentation, where the maximal specific growth rate (μ(max)) and specific production rate of exopolysaccharide (P(P/X)) were 1.03 and 0.24 d⁻¹, respectively; under pH-shift cultivation, the maximal DCW and exopolysaccharide production were 30.57 and 3.90 g L⁻¹, where the μ(max) and P(P/X) were 1.21 and 0.06 d⁻¹. Unlike batch fermentation, maximal DCW and exopolysaccharide production merely reached 15.04 and 2.0 g L⁻¹, where the μ(max) and P(P/X) were 0.86 and 0.05 d⁻¹, respectively. These results suggest that a pH-stat strategy is a more efficient way of performing the fermentation process to increase exopolysaccharide production. Furthermore, this research has also proved that the three-stage pH-control mode is effective for cell growth.

  13. On-line estimation of the dissolved zinc concentration during ZnS precipitation in a continuous stirred tank reactor (CSTR)

    NARCIS (Netherlands)

    Grootscholten, T.I.M.; Keesman, K.J.; Lens, P.N.L.

    2008-01-01

    In this paper a method is presented to estimate the reaction term of zinc sulphide precipitation and the zinc concentration in a CSTR, using the read-out signal of a sulphide selective electrode. The reaction between zinc and sulphide is described by a non-linear model and therefore classical observ

  14. Enhancement of Oxygen Mass Transfer and Gas Holdup Using Palm Oil in Stirred Tank Bioreactors with Xanthan Solutions as Simulated Viscous Fermentation Broths

    Directory of Open Access Journals (Sweden)

    Suhaila Mohd Sauid

    2013-01-01

    Full Text Available Volumetric mass transfer coefficient (kLa is an important parameter in bioreactors handling viscous fermentations such as xanthan gum production, as it affects the reactor performance and productivity. Published literatures showed that adding an organic phase such as hydrocarbons or vegetable oil could increase the kLa. The present study opted for palm oil as the organic phase as it is plentiful in Malaysia. Experiments were carried out to study the effect of viscosity, gas holdup, and kLa on the xanthan solution with different palm oil fractions by varying the agitation rate and aeration rate in a 5 L bench-top bioreactor fitted with twin Rushton turbines. Results showed that 10% (v/v of palm oil raised the kLa of xanthan solution by 1.5 to 3 folds with the highest kLa value of 84.44 h−1. It was also found that palm oil increased the gas holdup and viscosity of the xanthan solution. The kLa values obtained as a function of power input, superficial gas velocity, and palm oil fraction were validated by two different empirical equations. Similarly, the gas holdup obtained as a function of power input and superficial gas velocity was validated by another empirical equation. All correlations were found to fit well with higher determination coefficients.

  15. Modeling of 1,2-Dichloroethane Biodegradation by Xanthobacter autotrophicus GJ10 under Shock Loading of Other Halogenated Compounds in Continuous Stirred Tank Bioreactor

    NARCIS (Netherlands)

    Beschkov, V.; Sapundzhiev, Ts.; Torz, M.; Wietzes, P.; Janssen, D. B.

    2008-01-01

    A mathematical model describing the behavior of a continuous culture that degrades 1,2-dichloroethane and receives a shock loading of another compound was developed. The model takes into account possible cell death due to toxicity, growth inhibition and additional growth of cells on the second carbo

  16. Modeling of gas-liquid mass transfer in a stirred tank bioreactor agitated by a Rushton turbine or a new pitched blade impeller.

    Science.gov (United States)

    Gelves, Ricardo; Dietrich, A; Takors, Ralf

    2014-03-01

    A combined computational fluid dynamics (CFD) and population balance model (PBM) approach has been applied to simulate hydrodynamics and mass transfer in a 0.18 m(3) gas-liquid stirred bioreactor agitated by (1) a Rushton turbine, and (2) a new pitched blade geometry with rotating cartridges. The operating conditions chosen were motivated by typical settings used for culturing mammalian cells. The effects of turbulence, rotating flow, bubbles breakage and coalescence were simulated using the k-ε, multiple reference frame (MRF), Sliding mesh (SM) and PBM approaches, respectively. Considering the new pitched blade geometry with rotating aeration microspargers, [Formula: see text] mass transfer was estimated to be 34 times higher than the conventional Rushton turbine set-up. Notably, the impeller power consumption was modeled to be about 50 % lower. Independent [Formula: see text] measurements applying the same operational conditions confirmed this finding. Motivated by these simulated and experimental results, the new aeration and stirring device is qualified as a very promising tool especially useful for cell culture applications which are characterized by the challenging problem of achieving relatively high mass transfer conditions while inserting only low stirrer energy.

  17. Simulink在全混流反应器中的应用%The application of simulink to the simulation system of the continuous stirred tank reactor

    Institute of Scientific and Technical Information of China (English)

    孙翔; 毛先萍

    2005-01-01

    尝试一种进行化工过程仿真的新方法,利用Matlab的仿真工具箱Simulink,对全混流反应器进行可视化建模和仿真计算,以一个一级不可逆放热反应为例,进行稳态模拟及动态模拟,根据模拟结果提出反应器最优操作状态,并对动态模拟的各稳态操作点进行详细分析,同时提出了避免不稳定性的方法.结果表明,使用Simulink所建立的模型,具有很好的开放性和可移植性,还能轻松地分析过程动态特性,是进行建模仿真的好工具.

  18. 搅拌槽内温度对气含率的影响%Effect of Temperature on Gas Hold-up in Aerated Stirred Tanks

    Institute of Scientific and Technical Information of China (English)

    高正明; 施力田

    2003-01-01

    Gas holdups in ambient gassed and hot sparged systems with multiple modern impellers and the effect of temperature on gas holdup are reported. The operating temperature has a great impact on gas holdup though the gas dispersion regime in the hot sparged system is similar to the ambient gassed condition. The gas holdup under the elevated temperature and the ambient gassed operation is successfully correlated. With the same total gas flow rate and power input, the gas holdup in the hot sparged system (say near the boiling point) is only about half of that in the ambient system. The results imply that almost all existing hot sparged reactors have been designed on the basis of incorrect estimates of the gas holdup during operation.

  19. New models of radical polymerization with branching and scission predicting molecular weight distribution in tubular and series of continuous stirred tank reactors allowing for multiradicals and gelation

    NARCIS (Netherlands)

    Yaghini, N.; Iedema, P.D.

    2015-01-01

    Modeling of the mol. wt. distribution (MWD) of low-​d. Polyethylene (ldPE) has been carried out for a tubular reactor under realistic non-​isothermal conditions and for a series of CSTR's. The model allows for the existence of multiradicals and the occurrence of gelation. The deterministic model is

  20. Microbial community structure and dynamics during co-digestion of whey permeate and cow manure in continuous stirred tank reactor systems.

    Science.gov (United States)

    Hagen, Live Heldal; Vivekanand, Vivekanand; Linjordet, Roar; Pope, Phillip B; Eijsink, Vincent G H; Horn, Svein J

    2014-11-01

    Microbial community profiles in two parallel CSTR biogas reactors fed with whey permeate and cow manure were investigated. The operating conditions for these two reactors were identical, yet only one of them (R1) showed stable performance, whereas the other (R2) showed a decrease in methane production accompanied by accumulation of propionic acid and, later, acetic acid. This gave a unique opportunity to study the dynamics of the microbial communities in two biogas reactors apparently operating close to the edge of stability. The microbial community was dominated by Bacteroidetes and Firmicutes, and the methanogens Methanobacteriales and Methanomicrobiales in both reactors, but with larger fluctuations in R2. Correlation analyses showed that the depletion of propionic acid in R1 and the late increase of acetic acid in R2 was related to several bacterial groups. The biogas production in R1 shows that stable co-digestion of manure and whey can be achieved with reasonable yields.