Dynamic transition between fixed- and mobile-bed: mathematical and numerical aspects

Science.gov (United States)

Zugliani, Daniel; Pasqualini, Matteo; Rosatti, Giorgio

2017-04-01

Free-surface flows with high sediment transport (as debris flow or hyper-concentrated flow) are composed by a mixture of fluid and solid phase, usually water and sediment. When these flows propagate over loose beds, particles constituting the mixture of water and sediments strongly interact with the ones forming the bed, leading to erosion or deposition. However, there are lots of other situations when the mixture flows over rigid bedrocks or over artificially paved transects, so there is no mass exchange between bed and mixture. The two situations are usually referred to as, respectively, mobile- and fixed-bed conditions. From a mathematical point of view, the systems of Partial Differential Equations (PDEs) that describe these flows derive from mass and momentum balance of both phases, but, the two resulting PDEs systems are different. The main difference concerns the concentration: in the mobile-bed condition, the concentration is linked to the local flow conditions by means of a suitable rheological relation, while in the fixed-bed case, the concentration is an unknown of the problem. It is quite common that a free surface flow with high sediment transport, in its path, encounters both conditions. In the recent work of Rosatti & Zugliani 2015, the mathematical and numerical description of the transition between fixed- and mobile-bed was successfully resolved, for the case of low sediment transport phenomena, by the introduction of a suitable erodibility variable and satisfactory results were obtained. The main disadvantage of the approach is related to the erodibility variable, that changes in space, based on bed characteristics, but remains constant in time. However, the nature of the bed can change dynamically as result of deposition over fixed bed or high erosion over mobile bed. With this work, we extend the applicability of the mentioned approach to the more complex PDEs describing the hyper-concentrated flow. Moreover, we introduce a strategy that allows

Numerical modeling of straw combustion in a fixed bed

DEFF Research Database (Denmark)

Zhou, Haosheng; Jensen, Anker; Glarborg, Peter

2005-01-01

. The straw combustion processes include moisture evaporation, straw pyrolysis, gas combustion, and char combustion. The model provides detailed information of the structure of the ignition flame front. Simulated gas species concentrations at the bed surface, ignition flame front rate, and bed temperature......Straw is being used as main renewable energy source in grate boilers in Denmark. For optimizing operating conditions and design parameters, a one-dimensional unsteady heterogeneous mathematical model has been developed and experiments have been carried out for straw combustion in a fixed bed...... are in good agreement with measurements at different operating conditions such as primary air-flow rate, pre-heating of the primary air, oxygen concentration, moisture content in straw, and bulk density of the straw in the fixed bed. A parametric study indicates that the effective heat conductivity, straw...

STUDY OF GAS SEPARATION PROCESS BY DYNAMIC ADSORPTION IN FIXED BED

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Ioan Solomon

2010-10-01

Full Text Available An experimental study of mass transfer at gas separation by dynamic adsorption in fixed bed of impregnated silica gel is presented in this work. By means of a mathematical model based on constants and coefficient easy to evaluate, the distributions of adsorbate concentration in gas and solid phases were determined as a function of time and throughout the height of the fixed bed, under isothermal conditions.With this aim, water vapors from air were adsorbed in a fixed bed of impregnated silica gel. The values of the volumetric mass transfer coefficient, Kv, were determined experimentally at several values of air superficial velocity, an air relative humidity of 69�20at 38 °C. The influence of the gas flow velocity and initial water concentration in adsorbent on the distribution of water concentration in both phases was established as a function of time and throughout the height of the fixed bed. The results obtained allow one to determination of the local adsorption rate.

Performance of an anaerobic, static bed, fixed film bioreactor for chlorinated solvent treatment

Science.gov (United States)

Lorah, Michelle M.; Walker, Charles; Graves, Duane

2015-01-01

Anaerobic, fixed film, bioreactors bioaugmented with a dechlorinating microbial consortium were evaluated as a potential technology for cost effective, sustainable, and reliable treatment of mixed chlorinated ethanes and ethenes in groundwater from a large groundwater recovery system. Bench- and pilot-scale testing at about 3 and 13,500 L, respectively, demonstrated that total chlorinated solvent removal to less than the permitted discharge limit of 100 μg/L. Various planned and unexpected upsets, interruptions, and changes demonstrated the robustness and reliability of the bioreactor system, which handled the operational variations with no observable change in performance. Key operating parameters included an adequately long hydraulic retention time for the surface area, a constant supply of electron donor, pH control with a buffer to minimize pH variance, an oxidation reduction potential of approximately −200 millivolts or lower, and a well-adapted biomass capable of degrading the full suite of chlorinated solvents in the groundwater. Results indicated that the current discharge criteria can be met using a bioreactor technology that is less complex and has less downtime than the sorption based technology currently being used to treat the groundwater.

Morphological study of biomass during the start-up period of a fixed-bed anaerobic reactor treating domestic sewage

Directory of Open Access Journals (Sweden)

Cláudio Antonio Andrade Lima

2005-09-01

Full Text Available This work focused on a morphological study of the microorganisms attached to polyurethane foam matrices in a horizontal-flow anaerobic immobilized biomass (HAIB reactor treating domestic sewage. The experiments consisted of monitoring the biomass colonization process of foam matrices in terms of the amount of retained biomass and the morphological characteristics of the cells attached to the support during the start-up period. Non-fluorescent rods and cocci were found to predominate in the process of attachment to the polyurethane foam surface. From the 10th week of operation onwards, an increase was observed in the morphological diversity, mainly due to rods, cocci, and Methanosaeta-like archaeal cells. Hydrodynamic problems, such as bed clogging and channeling occurred in the fixed-bed reactor, mainly due to the production of extracellular polymeric substances and their accumulation in the interstices of the bed causing a gradual deterioration of its performance, which eventually led to the system's collapse. These results demonstrated the importance and usefulness of monitoring the dynamics of the formation of biofilm during the start-up period of HAIB reactors, since it allowed the identification of operational problems.Este trabalho apresenta um estudo morfológico de microrganismos aderidos à espuma de poliuretano em reator anaeróbio horizontal de leito fixo (RAHLF, aplicado ao tratamento de esgoto sanitário. O processo de colonização do suporte pela biomassa anaeróbia e as características morfológicas das células aderidas foram monitorados durante o período de partida do reator. Bacilos e cocos não fluorescentes foram predominantes no processo de aderência direta à espuma de poliuretano. Aumento na diversidade biológica foi observado a partir da 10ª semana de operação do reator, com predominância de bacilos, cocos e arqueas metanogênicas semelhantes a Methanosaeta. Problemas hidrodinâmicos, tais como formação de

Theory and measurements of electrophoretic effects in monolith, fixed-bed, and fluidized-bed plasma reactors

International Nuclear Information System (INIS)

Morin, T.J.

1989-01-01

Pressure gradients and secondary flow fields generated by the passage of electrical current in a d.c. gas discharge or gas laser are topics of longstanding interest in the gaseous electronics literature. These hydrodynamic effects of space charge fields and charged particle density gradients have been principally exploited in the development of gas separation and purification processes. In recent characterization studies of fixed-bed and fluidized-bed plasma reactors several anomalous flow features have been observed. These reactors involve the contacting of a high-frequency, resonantly-sustained, disperse gas discharge with granular solids in a fixed or fluidized bed. Anomalies in the measured pressure drops and fluidization velocities have motivated the development of an appropriate theoretical approach to, and some additional experimental investigations of electrophoretic effects in disperse gas discharges. In this paper, a theory which includes the effects of space charge and diffusion is used to estimate the electric field and charged particle density profiles. These profiles are then used to calculate velocity fields and gas flow rates for monolith, fixed-bed, and fluidized-bed reactors. These results are used to rationalize measurements of gas flow rates and axial pressure gradients in high-frequency disperse gas discharges with and without an additional d.c. axial electric field

Kinetic evaluation of an anaerobic fluidised-bed reactor treating slaughterhouse wastewater

Energy Technology Data Exchange (ETDEWEB)

Borja, R. [Consejo Superior de Investigaciones Cientificas, Seville (Spain). Inst. de la Grasa; Banks, C.J.; Zhengjian Wang [Manchester Univ. (United Kingdom). Inst. of Science and Technology

1995-09-01

An anaerobic fluidised-bed reactor for purification of slaughterhouse wastewater was modelled as a continuous-flow, completely-mixed homogeneous microbial system, with the feed COD as the limiting-substrate concentration. The average microbial residence time in the reactor was defined in terms of conventional sludge-retention-time. The experimental data obtained indicated that the Michaelis-Menten expression was applicable to a description of substrate utilisation (i.e. COD removal) in the anaerobic fluidised-bed system. The maximum substrate utilisation rate, k, and the Michaelis constant, K{sub s}, were determined to be 1.2/day and 0.039 g/l. The observed biomass yield in the reactor decreased with increasing sludge-retention-time. The specific methane production rate observed was a linear function of the specific substrate-utilisation rate. (Author)

Kraft pulp and paper mill wastewater treatment using fixed bed anaerobic reactors

International Nuclear Information System (INIS)

Damianovic, M. H. R. Z; Ruas, D.; Pires, E. C.; Foresti, E.

2009-01-01

The effluents of pulp mills contain a myriad of toxic compounds, biodegradable organic matter and sulfur compounds. to decrease the amount of fresh water required for pulp and paper production closed circuits are in use, however, higher concentrations of slat, as oxidized sulfur compounds, are encountered in the wastewaters. energy costs and new environmental concerns are motivating the use of anaerobic pretreatment as a way to decrease energy expenditure in the treatment plant together with lower sludge production. In anaerobic environment, the organic matter removal can follow methanogenic or sulfidogenic paths and with the latter simultaneous reduction of the oxidized sulfur compounds also occurs. (Author)

Complex nonlinear behaviour of a fixed bed reactor with reactant recycle

DEFF Research Database (Denmark)

Recke, Bodil; Jørgensen, Sten Bay

1999-01-01

The fixed bed reactor with reactant recycle investigated in this paper can exhibit periodic solutions. These solutions bifurcate from the steady state in a Hopf bifurcation. The Hopf bifurcation encountered at the lowest value of the inlet concentration turns the steady state unstable and marks......,that the dynamic behaviour of a fixed bed reactor with reactant recycle is much more complex than previously reported....

Comparative study between fluidized bed and fixed bed reactors in methane reforming with CO2 and O2 to produce syngas

International Nuclear Information System (INIS)

Jing Qiangshan; Lou Hui; Mo Liuye; Zheng Xiaoming

2006-01-01

Reforming of methane with carbon dioxide and oxygen was investigated over Ni/MgO-SiO 2 catalysts using fixed bed and fluidized bed reactors. The conversions of CH 4 and CO 2 in a fluidized bed reactor were close to thermodynamic equilibrium. The activity and stability of the catalyst in the fixed bed reactor were lower than that in the fluidized bed reactor due to carbon deposition and nickel sintering. TGA and TEM techniques were used to characterize the spent catalysts. The results showed that a lot of whisker carbon was found on the catalyst in the rear of the fixed bed reactor, and no deposited carbon was observed on the catalysts in the fluidized bed reactor after reaction. It is suggested that this phenomenon is related to a permanent circulation of catalyst particles between the oxygen rich and oxygen free zones. That is, fluidization of the catalysts in the fluidized bed reactor favors inhibiting deposited carbon and thermal uniformity in the reactor

Nonlinear dynamics and control of a recycle fixed bed reactor

DEFF Research Database (Denmark)

Recke, Bodil; Jørgensen, Sten Bay

1997-01-01

The purpose of this paper is twofold. Primarily to describe the dynamic behaviour that can be observed in a fixed bed reactor with recycle of unconverted reactant. Secondly to describe the possibilities of model reduction in order to facilitate control design. Reactant recycle has been shown...... to introduce periodic solution to the fixed bed reactor, a phenomenon which is not seen for the system without the recycle, at least not within the Peclet number range investigated in the present work. The possibility of model reduction by the methods of modal decomposition, and by characteristics...

Fluidized bed anaerobic biodegration of food industry wastewaters

Energy Technology Data Exchange (ETDEWEB)

Toldra, F.; Flors, A.; Lequerica, J.L.; Valles, S.

1987-01-01

Anaerobic fluidized bed reactors were used to reduce the COD of low-strength food industry wastewaters. Soluble organic removal efficiencies of 75%, 80% and 50% were obtained for hog slaughterhouse, dairy and brewery wastewaters, respectively, at 35 degrees C and 8 hours hydraulic retention time. Removal efficiencies decreased with decreasing temperature (35 degrees C to 20 degrees C); no detrimental effect of temperature was observed when treating the slaughterhouse wastewater. Methane production rate was only relevant on brewery wastewater treatment. (Refs. 17).

Anaerobic treatment of distillery spent wash - a study on upflow anaerobic fixed film bioreactor.

Science.gov (United States)

Acharya, Bhavik K; Mohana, Sarayu; Madamwar, Datta

2008-07-01

Anaerobic digestion of wastewater from a distillery industry having very high COD (1,10,000-1,90,000 mg/L) and BOD (50,000-60,000 mg/L) was studied in a continuously fed, up flow fixed film column reactor using different support materials such as charcoal, coconut coir and nylon fibers under varying hydraulic retention time and organic loading rates. The seed consortium was prepared by enrichment with distillery spent wash in a conventional type reactor having working capacity of 3 L and was used for charging the anaerobic column reactor. Amongst the various support materials studied the reactor having coconut coir could treat distillery spent wash at 8d hydraulic retention time with organic loading rate of 23.25 kg COD m(-3)d(-1) leading to 64% COD reduction with biogas production of 7.2 m3 m(-3)d(-1) having high methane yield without any pretreatment or neutralization of the distillery spent wash. This study indicates fixed film biomethanation of distillery spent wash using coconut coir as the support material appears to be a cost effective and promising technology for mitigating the problems caused by distillery effluent.

Development of an energy-saving anaerobic hybrid membrane bioreactors for 2-chlorophenol-contained wastewater treatment.

Science.gov (United States)

Wang, Yun-Kun; Pan, Xin-Rong; Sheng, Guo-Ping; Li, Wen-Wei; Shi, Bing-Jing; Yu, Han-Qing

2015-12-01

A novel energy-saving anaerobic hybrid membrane bioreactor (AnHMBR) with mesh filter, which takes advantage of anaerobic membrane bioreactor and fixed-bed biofilm reactor, is developed for low-strength 2-chlorophenol (2-CP)-contained wastewater treatment. In this system, the anaerobic membrane bioreactor is stuffed with granular activated carbon to construct an anaerobic hybrid fixed-bed biofilm membrane bioreactor. The effluent turbidity from the AnHMBR system was low during most of the operation period, and the chemical oxygen demand and 2-CP removal efficiencies averaged 82.3% and 92.6%, respectively. Furthermore, a low membrane fouling rate was achieved during the operation. During the AnHMBR operation, the only energy consumption was for feed pump. And a low energy demand of 0.0045-0.0063kWhm(-3) was estimated under the current operation conditions. All these results demonstrated that this novel AnHMBR is a sustainable technology for treating 2-CP-contained wastewater. Copyright © 2014 Elsevier Ltd. All rights reserved.

Adsorption of aromatic amino acids in a fixed bed column

Directory of Open Access Journals (Sweden)

Cremasco M.A.

2003-01-01

Full Text Available Phenylalanine (Phe and tyrosine (Tyr are two of the twenty amino acids in proteins; they are classified as aromatic amino acids, because both have a benzene ring in their structures. These amino acids are important in the synthesis of several biologically active amines, such as beta-endorphin, a neurotransmitter. Amino acids can be separated by ion-exchange chromatography. In this case, it is important that fixed-bed adsorber design adequately predict the breakthrough curve. This work presents a mathematical model for both fluid and porous phases. In the solution proposed for this model the liquid-phase concentration inside the particles is solved analytically and is related to the liquid-phase concentration in the bed using Duhamel's theorem. The solution for liquid-phase concentration in the bed is then solved numerically instead of analytically. The basic mass transfer parameters are from the literature. The results from the model are compared with those obtained experimentally using Phe and Tyr diluted in aqueous solutions in a fixed bed of PVP (poly-4-vinylpyridine resin.

Physical-Mathematical Model for Fixed-Bed Solid Fuel Gasification Process Simulation

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Slyusarskiy Konstantin V.

2017-01-01

Full Text Available Phycial-mathmatical model for fixed-bed coal gasification process simulation is proposed. The heterogeneous carbon oxidation chemical reactions were simulated via Arrhenius equation while homogeneous reactions in gas phase were calculated using Gibbs free energy minimization procedure. The syngas component concentration field and fuel conversion distribution as well as syngas final temperature and composition were defined for fixed bed gasification of T-grade coal of Kuznetskiy deposit. The optimal fuel residence time and gasifyer specific productivity were defined. The prevail reactions in oxidizing and reduction zones together with its height were defined.

Biological Phosphorus Release and Uptake Under Alternating Anaerobic and Anoxic Conditions In a Fixed-Film Reactor

DEFF Research Database (Denmark)

Kerrn-Jespersen, Jens Peter; Henze, Mogens; Strube, Rune

1994-01-01

Biological phosphorus removal was investigated in a fixed-film reactor with alternating anaerobic and anoxic conditions. The tests showed that biological phosphorus removal can be obtained in a fixed-film reactor with nitrate as oxidising agent. In the anaerobic period, 0.52 mg of PO4-P...... was released per mg of acetate taken up on an average. In the anoxic period, 2.0 mg of PO4-P was taken up per mg of NO3-N reduced on an average. The relationship between potassium released and phosphate released in the anaerobic phase was determined to be 0.37 mg K/mg P, while the relationship between...

Dimensioning of aerated submerged fixed bed biofilm reactors ...

African Journals Online (AJOL)

The description of a biofilm mathematical model application for dimensioning an aerated fixed bed biofilm reactor (ASFBBR) for petrochemical wastewater polishing is presented. A simple one-dimensional model of biofilm, developed by P Harremöes, was chosen for this purpose. The model was calibrated and verified ...

Selenate removal in methanogenic and sulfate-reducing upflow anaerobic sludge bed reactors

NARCIS (Netherlands)

Lenz, M.; Hullebusch, van E.D.; Hommes, G.; Corvini, P.F.X.; Lens, P.N.L.

2008-01-01

This paper evaluates the use of upflow anaerobic sludge bed (UASB) bioreactors (30 degrees C, pH = 7.0) to remove selenium oxyanions from contaminated waters (790 mu g Se L-1) under methanogenic and sulfate-reducing conditions using lactate as electron donor. One UASB reactor received sulfate at

Comparative experimental studies of different fluidized-bed reactor systems with regard to their anaerobic sewage treatment suitability; Vergleichende experimentelle Untersuchung verschiedener Wirbelbett-Reaktorsysteme im Hinblick auf ihre Eignung fuer die anaerobe Abwasserreinigung

Energy Technology Data Exchange (ETDEWEB)

Buettgenbach, L.

1991-12-12

Gas-induced fluidized-bed reactors are suited for permanent anaerobic digestion without runbacks. The carrier particles must have a high fixing capacity and mechanical stability for permanent-biofilm formation. The suitability of macroporous polyurethane carrier materials, the biofilm formation properties, the digestion of substrates and the production of biogas were investigated for synthetic waste water and potato starch waste water in 70 l liquid upward current reactors, bubble column reactors and gas lift loop reactors with/out gas recirculation. (LU) [Deutsch] In gasinduzierten Wirbelbett-Reaktoren ist eine prozessstabile anaerobe Abbaureaktion ohne Abwasserruecklauf moeglich. Die Anforderungen an die Fixierkapazitaet und die mechanische Stabilitaet der Traegerpartikel zur Erzeugung stabiler Biofilme ist hoch. Experimentell wurden in begasten und unbegasten Systemen (Fluessigkeits-Aufstromreaktor, Blasensaeulenreaktor, Gaslift-Schlaufenreaktor, Reaktorvolumen jeweils 70 l) die Eignung makroporoeser Traegermaterialien aus Polyurethanmasse, die Biofilmbildung, der Substratabbau und die Biogasproduktion untersucht. Eingesetzt wurde ein synthetisches Abwasser und ein Abwasser aus der Staerkeindustrie (Kartoffelfruchtwasser). (LU)

STUDY OF HYDRODYNAMICS IN FIXED BED OF COMPOSITE GRANULAR MATERIALS

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Stelian Petrescu

2010-12-01

Full Text Available This study aims at the experimental determination of pressure drop and friction factor at gas flow through fixed beds of granular silica gel, alumina and activated carbon, and establishment of an equation containing a modified friction factor Fm to calculate pressure drop. In order to calculate the modified friction factor, an equation was suggested.The experimental values for pressure drop and friction factor were determined using spherical grains of silica gel, cylindrical grains of alumina and silica gel, alumina and activated carbon impregnated with calcium chloride. By means of the suggested equation, the values of pressure drop in fixed bed were calculated and compared with the experimental values. A good agreement between the predicted and experimental data is noticed.

Degradation of TCE using sequential anaerobic biofilm and aerobic immobilized bed reactor

Science.gov (United States)

Chapatwala, Kirit D.; Babu, G. R. V.; Baresi, Larry; Trunzo, Richard M.

1995-01-01

Bacteria capable of degrading trichloroethylene (TCE) were isolated from contaminated wastewaters and soil sites. The aerobic cultures were identified as Pseudomonas aeruginosa (four species) and Pseudomonas fluorescens. The optimal conditions for the growth of aerobic cultures were determined. The minimal inhibitory concentration values of TCE for Pseudomonas sps. were also determined. The aerobic cells were immobilized in calcium alginate in the form of beads. Degradation of TCE by the anaerobic and dichloroethylene (DCE) by aerobic cultures was studied using dual reactors - anaerobic biofilm and aerobic immobilized bed reactor. The minimal mineral salt (MMS) medium saturated with TCE was pumped at the rate of 1 ml per hour into the anaerobic reactor. The MMS medium saturated with DCE and supplemented with xylenes and toluene (3 ppm each) was pumped at the rate of 1 ml per hour into the fluidized air-uplift-type reactor containing the immobilized aerobic cells. The concentrations of TCE and DCE and the metabolites formed during their degradation by the anaerobic and aerobic cultures were monitored by GC. The preliminary study suggests that the anaerobic and aerobic cultures of our isolates can degrade TCE and DCE.

Adsorption of ciprofloxacin and norfloxacin from aqueous solution onto granular activated carbon in fixed bed column.

Science.gov (United States)

Darweesh, Teeba M; Ahmed, Muthanna J

2017-04-01

Carbonization of Phoenix dactylifera L stones followed by microwave K 2 CO 3 activation was adopted for preparation of granular activated carbon (KAC). High yield and favorable pore characteristics in terms of surface area and pore volume were reported for KAC as follows: 44%, 852m 2 /g, and 0.671cm 3 /g, respectively. The application of KAC as adsorbent for attraction of ciprofloxacin (CIP) and norfloxacin (NOR) was investigated using fixed bed systems. The effect of flow rate (0.5-1.5ml/min), bed height (15-25cm), and initial drug concentration (75-225mg/l) on the behavior of breakthrough curves was explained. The fixed bed analysis showed the better correlation of breakthrough data by both Thomas and Yoon-Nelson models. Inlet drug concentration was of greatest effect on breakthrough data compared to other fixed bed variables. Experimental and calculated breakthrough data were obtained for CIP and NOR adsorption on KAC, thus being important for design of fixed bed column. Copyright © 2016 Elsevier Inc. All rights reserved.

Nitrification in moving bed and fixed bed biofilters treating effluent water from a large commercial outdoor rainbow trout RAS

DEFF Research Database (Denmark)

Suhr, Karin; Pedersen, Per Bovbjerg

2010-01-01

The nitrification performance of two fixed bed (FB) biofilters and two moving bed (MB) biofilters was evaluated. They received the same cold (8 degrees C) influent water from a commercial outdoor RAS facility producing rainbow trout (average density 32 kg m(-3)). The filters were constructed as f...

Experimental and theoretical investigation of anaerobic fluidized bed biofilm reactors

Directory of Open Access Journals (Sweden)

M. Fuentes

2009-09-01

Full Text Available This work presents an experimental and theoretical investigation of anaerobic fluidized bed reactors (AFBRs. The bioreactors are modeled as dynamic three-phase systems. Biochemical transformations are assumed to occur only in the fluidized bed zone. The biofilm process model is coupled to the system hydrodynamic model through the biofilm detachment rate; which is assumed to be a first-order function of the energy dissipation parameter and a second order function of biofilm thickness. Non-active biomass is considered to be particulate material subject to hydrolysis. The model includes the anaerobic conversion for complex substrate degradation and kinetic parameters selected from the literature. The experimental set-up consisted of two mesophilic (36±1ºC lab-scale AFBRs (R1 and R2 loaded with sand as inert support for biofilm development. The reactor start-up policy was based on gradual increments in the organic loading rate (OLR, over a four month period. Step-type disturbances were applied on the inlet (glucose and acetic acid substrate concentration (chemical oxygen demand (COD from 0.85 to 2.66 g L-1 and on the feed flow rate (from 3.2 up to 6.0 L d-1 considering the maximum efficiency as the reactor loading rate switching. The predicted and measured responses of the total and soluble COD, volatile fatty acid (VFA concentrations, biogas production rate and pH were investigated. Regarding hydrodynamic and fluidization aspects, variations of the bed expansion due to disturbances in the inlet flow rate and the biofilm growth were measured. As rate coefficients for the biofilm detachment model, empirical values of 3.73⋅10(4 and 0.75⋅10(4 s² kg-1 m-1 for R1 and R2, respectively, were estimated.

Comparison of the Effects of Fluidized-Bed and Fixed-Bed Reactors in Microwave-Assisted Catalytic Decomposition of TCE by Hydrogen

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Lili Ren

2012-01-01

Full Text Available Trichloroethylene (TCE decomposition by hydrogen with microwave heating under different reaction systems was investigated. The activities of a series of catalysts for microwave-assisted TCE hydrodechlorination were tested through the fixed-bed and the fluidized-bed reactor systems. This study found that the different reaction system is suitable for different catalyst type. And there is an interactive relationship between the catalyst type and the reaction bed type.

Uptake of Cd(II Using Natural Zeolite: Batch and Continuous Fixed-Bed Studies

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Luna M. LMarashdeh

2009-12-01

Full Text Available Uptake of Cd(II ions by natural phillipsite tuff was investigated both in shake-flask and fixed-bed columns. Equilibrium uptake, qe, was found to best fit Langmuir adsorption isotherm with a maximum value of 25.78 mg/g. Percent removal of Cd ions was close to 100% from initial metal ion concentrations in the range 50 - 75 mg/L at 5.0 g zeolite/L. Also, qe was found to vary exponentially with zeolite dose. Break points as high as 350 minutes were obtained from bed treatment at favorable conditions of a low solution flow rate and high bed depth. In batch experiments, equilibrium pH increased to < 8.0 excluding chemical precipitation as part of the removal while in fixed-beds the final pH exceeded 9.0. It is suggested that a sieve action of zeolite porous structure plays a role as an uptake mechanism in addition to the ion exchange.

Solid-State Anaerobic Digestion of Dairy Manure from a Sawdust-Bedded Pack Barn: Moisture Responses

Directory of Open Access Journals (Sweden)

Eunjong Kim

2018-02-01

Full Text Available Bedded pack manure has long been considered an unsuitable feedstock for conventional anaerobic digestion systems due to its high solids content. However, solid-state anaerobic digestion (SS-AD provides an opportunity to generate methane from such high-solids feedstocks. This study was conducted to determine the influence of moisture content on the digestion of bedded pack dairy manure using SS-AD. Mixtures of sawdust bedding and dairy manure were prepared with moisture contents (MCs of 70, 76, and 83% and digested at 37 °C for 85 days. The performance of digesters containing manure at 83% MC was 1.3 to 1.4-fold higher than that of digesters containing 70% MC manure in terms of volatile solids (VS reduction and biogas production. VS reduction rates were 55 to 75% and cumulative methane yield ranged from 64 to 90 NmL (gVS−1. These values are lower than those from SS-AD of fresh manure and this is likely due to the partial decomposition of biodegradable materials during the two to three-month period before the manure was removed from the barn. However, in terms of efficient management of farm odors and providing a renewable energy source for heating, SS-AD of bedded pack manure offers a potential alternative to the conventional composting systems currently in use.

Aerobic and anaerobic nitrogen transformation processes in N2-fixing cyanobacterial aggregates.

Science.gov (United States)

Klawonn, Isabell; Bonaglia, Stefano; Brüchert, Volker; Ploug, Helle

2015-06-01

Colonies of N(2)-fixing cyanobacteria are key players in supplying new nitrogen to the ocean, but the biological fate of this fixed nitrogen remains poorly constrained. Here, we report on aerobic and anaerobic microbial nitrogen transformation processes that co-occur within millimetre-sized cyanobacterial aggregates (Nodularia spumigena) collected in aerated surface waters in the Baltic Sea. Microelectrode profiles showed steep oxygen gradients inside the aggregates and the potential for nitrous oxide production in the aggregates' anoxic centres. (15)N-isotope labelling experiments and nutrient analyses revealed that N(2) fixation, ammonification, nitrification, nitrate reduction to ammonium, denitrification and possibly anaerobic ammonium oxidation (anammox) can co-occur within these consortia. Thus, N. spumigena aggregates are potential sites of nitrogen gain, recycling and loss. Rates of nitrate reduction to ammonium and N(2) were limited by low internal nitrification rates and low concentrations of nitrate in the ambient water. Presumably, patterns of N-transformation processes similar to those observed in this study arise also in other phytoplankton colonies, marine snow and fecal pellets. Anoxic microniches, as a pre-condition for anaerobic nitrogen transformations, may occur within large aggregates (⩾1 mm) even when suspended in fully oxygenated waters, whereas anoxia in small aggregates (1.5 μM), O(2)-depleted water layers, for example, in the chemocline of the Baltic Sea or the oceanic mesopelagic zone, aggregates may promote N-recycling and -loss processes.

Particle Distribution in a Fixed Bed Down Draft Wood Gasifier

DEFF Research Database (Denmark)

Hindsgaul, Claus

2005-01-01

Char particle samples were collected from six distances above the grate in a fixed bed of a down draft biomass gasifier. Each sample was separated into twelve size fractions by screening through standard sieves in order to determine the local particle size distribution. The ash contents of each...

Application of acidogenic fixed-bed reactor prior to anaerobic membrane bioreactor for sustainable slaughterhouse wastewater treatment.

Science.gov (United States)

Saddoud, Ahlem; Sayadi, Sami

2007-11-19

High rate anaerobic treatment systems such as anaerobic membrane bioreactors (AMBR) are less popular for slaughterhouse wastewater due to the presence of high fat oil and suspended matters in the effluent. This affects the performance and efficiency of the treatment system. In this work, AMBR has been tried for slaughterhouse wastewater treatment. After the start up period, the reactor was operated with an average organic loading rate (OLR) of 4.37 kg TCODm(-3)d(-1) with gradual increase to an average of 13.27 kg TCODm(-3)d(-1). At stable conditions, the treatment efficiency was high with an average COD and BOD(5) reduction of 93.7 and 93.96%, respectively. However, a reduction in the AMBR performance was shown with the increase of the OLR to 16.32 kg TCODm(-3)d(-1). The removal efficiencies of SCOD and BOD(5) were drastically decreased to below 53.6 and 73.3%, respectively. The decrease of the AMBR performance was due to the accumulation of VFAs. Thus, a new integrated system composed of a FBR for the acidogenesis step followed by the AMBR for methanogenesis step was developed. At high ORL, the integrated system improved the performance of the anaerobic digestion and it successfully overcame the VFA accumulation problem in the AMBR. The anaerobic treatment led to a total removal of all tested pathogens. Thus, the microbiological quality of treated wastewater fits largely with WHO guidelines.

Application of acidogenic fixed-bed reactor prior to anaerobic membrane bioreactor for sustainable slaughterhouse wastewater treatment

International Nuclear Information System (INIS)

Saddoud, Ahlem; Sayadi, Sami

2007-01-01

High rate anaerobic treatment systems such as anaerobic membrane bioreactors (AMBR) are less popular for slaughterhouse wastewater due to the presence of high fat oil and suspended matters in the effluent. This affects the performance and efficiency of the treatment system. In this work, AMBR has been tried for slaughterhouse wastewater treatment. After the start up period, the reactor was operated with an average organic loading rate (OLR) of 4.37 kg TCOD m -3 d -1 with gradual increase to an average of 13.27 kg TCOD m -3 d -1 . At stable conditions, the treatment efficiency was high with an average COD and BOD 5 reduction of 93.7 and 93.96%, respectively. However, a reduction in the AMBR performance was shown with the increase of the OLR to 16.32 kg TCOD m -3 d -1 . The removal efficiencies of SCOD and BOD 5 were drastically decreased to below 53.6 and 73.3%, respectively. The decrease of the AMBR performance was due to the accumulation of VFAs. Thus, a new integrated system composed of a FBR for the acidogenesis step followed by the AMBR for methanogenesis step was developed. At high ORL, the integrated system improved the performance of the anaerobic digestion and it successfully overcame the VFA accumulation problem in the AMBR. The anaerobic treatment led to a total removal of all tested pathogens. Thus, the microbiological quality of treated wastewater fits largely with WHO guidelines

Enhanced removal of sulfonamide antibiotics by KOH-activated anthracite coal: Batch and fixed-bed studies

International Nuclear Information System (INIS)

Zuo, Linzi; Ai, Jing; Fu, Heyun; Chen, Wei; Zheng, Shourong; Xu, Zhaoyi; Zhu, Dongqiang

2016-01-01

The presence of sulfonamide antibiotics in aquatic environments poses potential risks to human health and ecosystems. In the present study, a highly porous activated carbon was prepared by KOH activation of an anthracite coal (Anth-KOH), and its adsorption properties toward two sulfonamides (sulfamethoxazole and sulfapyridine) and three smaller-sized monoaromatics (phenol, 4-nitrophenol and 1,3-dinitrobenzene) were examined in both batch and fixed-bed adsorption experiments to probe the interplay between adsorbate molecular size and adsorbent pore structure. A commercial powder microporous activated carbon (PAC) and a commercial mesoporous carbon (CMK-3) possessing distinct pore properties were included as comparative adsorbents. Among the three adsorbents Anth-KOH exhibited the largest adsorption capacities for all test adsorbates (especially the two sulfonamides) in both batch mode and fixed-bed mode. After being normalized by the adsorbent surface area, the batch adsorption isotherms of sulfonamides on PAC and Anth-KOH were displaced upward relative to the isotherms on CMK-3, likely due to the micropore-filling effect facilitated by the microporosity of adsorbents. In the fixed-bed mode, the surface area-normalized adsorption capacities of Anth-KOH for sulfonamides were close to that of CMK-3, and higher than that of PAC. The irregular, closed micropores of PAC might impede the diffusion of the relatively large-sized sulfonamide molecules and in turn led to lowered fixed-bed adsorption capacities. The overall superior adsorption of sulfonamides on Anth-KOH can be attributed to its large specific surface area (2514 m"2/g), high pore volume (1.23 cm"3/g) and large micropore sizes (centered at 2.0 nm). These findings imply that KOH-activated anthracite coal is a promising adsorbent for the removal of sulfonamide antibiotics from aqueous solution. - Highlights: • A high efficiency adsorbent for sulfonamide removal is prepared from anthracite. • Effects of

Transformation of carbon tetrachloride in an anaerobic packed-bed reactor without addition of another electron donor

NARCIS (Netherlands)

de Best, JH; Hunneman, P; Doddema, HJ; Janssen, DB; Harder, W; Doddema, Hans J.

1999-01-01

Carbon tetrachloride (52 mu M) was biodegraded for more than 72% in an anaerobic packed-bed reactor without addition of an external electron donor. The chloride mass balance demonstrated that all carbon tetrachloride transformed was completely dechlorinated. Chloroform and dichloromethane were

Transformation of carbon tetrachloride in an anaerobic packed-bed reactor without addition of another electron donor

NARCIS (Netherlands)

Best, J.H. de; Hunneman, P.; Doddema, H.J.; Janssen, D.B.; Harder, W.

1999-01-01

Carbon tetrachloride (52 μM) was biodegraded for more than 72% in an anaerobic packed-bed reactor without addition of an external electron donor. The chloride mass balance demonstrated that all carbon tetrachloride transformed was completely dechlorinated. Chloroform and dichloromethane were

Application of acidogenic fixed-bed reactor prior to anaerobic membrane bioreactor for sustainable slaughterhouse wastewater treatment

Energy Technology Data Exchange (ETDEWEB)

Saddoud, Ahlem [Laboratoire des Bio-procedes, Centre de Biotechnologie de Sfax, BP: K, Sfax 3038 (Tunisia); Sayadi, Sami [Laboratoire des Bio-procedes, Centre de Biotechnologie de Sfax, BP: K, Sfax 3038 (Tunisia)], E-mail: sami.sayadi@cbs.rnrt.tn

2007-11-19

High rate anaerobic treatment systems such as anaerobic membrane bioreactors (AMBR) are less popular for slaughterhouse wastewater due to the presence of high fat oil and suspended matters in the effluent. This affects the performance and efficiency of the treatment system. In this work, AMBR has been tried for slaughterhouse wastewater treatment. After the start up period, the reactor was operated with an average organic loading rate (OLR) of 4.37 kg TCOD m{sup -3} d{sup -1} with gradual increase to an average of 13.27 kg TCOD m{sup -3} d{sup -1}. At stable conditions, the treatment efficiency was high with an average COD and BOD{sub 5} reduction of 93.7 and 93.96%, respectively. However, a reduction in the AMBR performance was shown with the increase of the OLR to 16.32 kg TCOD m{sup -3} d{sup -1}. The removal efficiencies of SCOD and BOD{sub 5} were drastically decreased to below 53.6 and 73.3%, respectively. The decrease of the AMBR performance was due to the accumulation of VFAs. Thus, a new integrated system composed of a FBR for the acidogenesis step followed by the AMBR for methanogenesis step was developed. At high ORL, the integrated system improved the performance of the anaerobic digestion and it successfully overcame the VFA accumulation problem in the AMBR. The anaerobic treatment led to a total removal of all tested pathogens. Thus, the microbiological quality of treated wastewater fits largely with WHO guidelines.

PERKEMBANGAN BIOFILM NITRIFIKASI DI FIXED BED REACTOR PADA SALINITAS TINGGI

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Sudarno

2012-03-01

Full Text Available Development of nitrification biomass that is growing attached on carried material was examined by measuring its ammonium or nitrit oxidation rates. Porous ceramic rings (36 pieces were put into the fixed bed reactor (FBR . The fixed bed reactor that was operated continuously for more than 500 day was continued to be operated at a HRT of 1 day, a DO of above 5 mg L-1 and pH of 8. Ammonia concentration in the feeding was 50 mg NH4+-N L-1. At days 1, 5, 12, 20, 33 and 50, six porous ceramic rings were taken out and then ammonia and nitrite removal rate by biofilm in the ceramic rings was separately measured. The measurement of rates was done in small cylindrical glass reactors with initial concentration of ammonia and nitrite was 10 mg N L-1. Until 50 days of incubation AORs were always higher than NORs. Additionally, ammonia oxidizers attach or grow faster in the porous ceramic material than nitrite oxidizers.

The fluidized bed reactor in the anaerobic treatment of wine wastewater

Energy Technology Data Exchange (ETDEWEB)

Converti, A; Zilli, M; Del Borghi, M; Ferraiolo, G [Genoa Univ. (Italy). Inst. of Chemical Engineering Science and Technology

1990-02-13

The aim of the present work is the performance evaluation of a fluidized bed reactor in the anaerobic treatment of a wastewater deriving from the washing operations of the wine industry. The results are in agreement with the ones obtained using a mixture of municipal and food processing waste waters containing high organic contents. A comparison with other liquid wastes shows that no subtrate inhibition phenomenon occurs with the above substrates. A saturation kinetic model is also presented for describing the dependence of the COD removal rate on the organic loading rate. (orig.).

Hydrodynamic characteristics of a two-phase gas-liquid flow upward through a fixed bed of spherical particles

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VELIZAR D. STANKOVIC

2001-01-01

Full Text Available The influence of an electrochemically generated gas phase on the hydrodynamic characteristics of a three-phase system has been examined. The two-phase fluid, (gas-liquid, in which the liquid phase is the continuous one, flows through a packed bed with glass spheres. The influence of the liquid velocity was examined, as well as the gas velocity and particle diameter on the pressure drop through the fixed bed. It was found that with increasing liquid velocity (wl = 0.0162–0.03 m/s, the relative pressure drop decreases through the fixed bed. With increasing current density, the pressure drop increases, since greater gas quantities stay behind in the fixed bed. Besides, it was found that with decreasing diameter of the glass particles, the relative pressure drop also decreases. The relationship betweeen the experimentally obtained friction factor and the Reynolds number was established.

A batch and fixed bed column study for fluorescein removal using chitosan modified by epichlorohydrin.

Science.gov (United States)

Silva, P M O; Francisco, J E; Cajé, J C M; Cassella, R J; Pacheco, W F

2018-01-02

This study evaluates the feasibility of commercial chitosan (CQ) and modified chitosan (MQ) by epichlorohydrin to be used as a solid phase to remove fluorescein (FSC) from aqueous solutions by two different approaches: in batch and on a fixed column bed. For the batch study, all parameters that influence sorption capacity were evaluated, such as: pH, mass, ionic strength, temperature and time of contact. In the optimized condition, 75% removal was obtained for FSC using CQ, while the modification allowed an increase up to 99%, as well as an increase in the stability of the polymer. In the fixed column bed study, the influence of all the parameters was evaluated through breakthrough curves, and the thermodynamics parameters of each approach were obtained. The results of these studies demonstrate that the modification with epichlorohydrin enhanced the sorptive properties (from 35% to 95% in fixed bed experiments) and the polymer stability (making it insoluble), making it suitable to be used in wastewater treatment.

Fixed-bed column adsorption of methyl blue using carbon derived ...

African Journals Online (AJOL)

Axle Wood Carbon (AWC) was used to study the removal of Methyl Blue (MB) from its aqueous solution in a fixed-bed column adsorption system. The adsorbent (AWC) was characterized using SEM and pHPZC. SEM revealed the surface morphology and from the pHPZC determination, it was found that at pH of 8.21 the ...

Dispersed plug flow model for upflow anaerobic sludge bed reactors with focus on granular sludge dynamics

NARCIS (Netherlands)

Kalyuzhnyi, S.V.; Fedorovich, V.V.; Lens, P.N.L.

2006-01-01

A new approach to model upflow anaerobic sludge bed (UASB)-reactors, referred to as a one-dimensional dispersed plug flow model, was developed. This model focusses on the granular sludge dynamics along the reactor height, based on the balance between dispersion, sedimentation and convection using

Parameters estimation for amino acids adsorption in a fixed bed by moment analysis

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M.A. Cremasco

2001-06-01

Full Text Available Equilibrium constant and mass transfer parameters are needed for the study of amino acid separation in any process involving adsorption in fixed beds. The adsorption constants, effective diffusion coefficients, and axial dispersion coefficients for two amino acids, L-phenylalanine (Phe and L-tyrosine (Tyr, are determined from a series of pulse tests in a fixed bed packed with PVP (poly-4-vinylpyridine resin. Total bed voidage at different flow rates is estimated from NaCl pulse test data. The effective pore diffusivities of Phe, Tyr, and NaCl are estimated from moment analysis of pulse data. A detailed rate model is then solved numerically and adsorption constants, effective diffusion coefficients, axial dispersion coefficients are determined by moment analysis and compared with the pulse data. The advantage of this method is that the effective intraparticle diffusivities can be determined without the influence of extracolumn dispersion or intracolumn axial dispersion effects.

Passive cooling of a fixed bed nuclear reactor

International Nuclear Information System (INIS)

Petry, V.J.; Bortoli, A.L. de; Sefidwash, F.

2005-01-01

Small nuclear reactors without the need for on-site refuelling have greater simplicity, better compliance with passive safety systems, and are more adequate for countries with small electric grids and limited investment capabilities. Here the passive cooling characteristic of the fixed bed nuclear reactor (FBNR), that is being developed under the International Atomic Energy Agency (IAEA) Coordinated Research Project, is studied. A mathematical model is developed to calculate the temperature distribution in the fuel chamber of the reactor. The results demonstrate the passive cooling of this nuclear reactor concept. (authors)

Characteristic Studies of Micron Zinc Particle Hydrolysis in a Fixed Bed Reactor

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Lv Ming

2015-09-01

Full Text Available Zinc fuel is considered as a kind of promising energy sources for marine propeller. As one of the key steps for zinc marine energy power system, zinc hydrolysis process had been studied experimentally in a fixed bed reactor. In this study, we focus on the characteristics of micron zinc particle hydrolysis. The experimental results suggested that the steam inner diffusion is the controlling step of accumulative zinc particles hydrolysis reaction at a relative lower temperature and a relative higher water partial pressure. In other conditions, the chemical reaction kinetics was the controlling step. And two kinds of chemical reaction kinetics appeared in experiments: the surface reaction and the gas-gas reaction. The latter one occurs usually for larger zinc particles and high reaction temperature. Temperature seems to be one of the most important parameters for the dividing of different reaction mechanisms. Several parameters of the hydrolysis process including heating rate, water partial pressure, the particle size and temperature were also studied in this paper. Results show that the initial reaction temperature of zinc hydrolysis in fixed bed is about 410°C. And the initial reaction temperature increases as the heating rate increases and as the water partial pressure decreases. The total hydrogen yield increases as the heating rate decreases, as the water partial pressure increases, as the zinc particle size decreases, and as the reaction temperature increases. A hydrogen yield of more than 81.5% was obtained in the fixed bed experiments.

ELECTRODEPOSITION OF COPPER IONS ON FIXED BED ELECTRODES: KINETIC AND HYDRODYNAMIC STUDY

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L.A.M. Ruotolo

2002-03-01

Full Text Available The kinetic and hydrodynamic behaviour of a fixed-bed electrochemical reactor was studied in terms of current efficiency (CE and energy efficiency (EE. In the kinetic experiments the effects of fixed bed thickness (L, current density (i and initial concentration of copper (C0 were studied. In the hydrodynamic experiments the permeability (k of the electrode and the coefficient for inertial forces (c were also studied as functions of the applied current density. At low current densities and bed thicknesses greater than 1.0 cm, negative CE and EE were observed as a consequence of the dissolution of the porous matrix. At high current densities low CE and EE were observed and a powdery deposit was formed on the surface of the particles. From the results of the kinetic study bed thickness and the range of current densities employed in the hydrodynamic experiments were chosen. In these experiments the electrodeposition process continued until the whole electrode had been clogged and no more electrolyte could pass through it. The relationship between pressure drop and flow rate was well described by the Forchheimer equation. It was observed that the reduction in porosity due to copper electrodeposition causes the flow rate to decrease because of the decrease in electrode permeability, but it had no influence on current efficiency.

Exchange between the stagnant and flowing zone in gas-flowing solids-fixed bed contactors

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ALEKSANDAR P. DUDUKOVIC

2005-02-01

Full Text Available In countercurrent gas – flowing solids – fixed bed contactors, a fraction of the flowing solids is in motion (dynamic holdup, while the other fraction is resting on the fixed bed elements. In this study it was experimentally proved that the stagnant zone should not be considered as a dead part of the column, but that there is a dynamic exchange between these two portions of flowing solids particles. Combining a mathematical model with tracer experiments, the rate of exchange was determined and it was shown that only a small part (ca. 20 % of the stagnant region should be considered as a dead one.

Innovative biological systems for anaerobic treatment of grain and food processing wastewaters

Energy Technology Data Exchange (ETDEWEB)

Sutton, P M

1986-09-01

The application of two innovative fixed film and suspended growth anaerobic biological systems to the treatment of grain and food processing wastewaters is discussed. A fluidized bed fixed film system and a suspended growth membrane system are described. The technical and economic factors dictating which system is selected for treatment of a specific industrial wastewater are discussed. Case history results from successful operation of full-scale, demonstration, and pilot-scale systems treating respectively, soy whey, cheese whey, and wheat flour processing wastewaters are presented.

Post-combustion CO2 capture with activated carbons using fixed bed adsorption

Science.gov (United States)

Al Mesfer, Mohammed K.; Danish, Mohd; Fahmy, Yasser M.; Rashid, Md. Mamoon

2018-03-01

In the current work, the capturing of carbon dioxide from flue gases of post combustion emission using fixed bed adsorption has been carried out. Two grades of commercial activated carbon (sorbent-1 and sorbent-2) were used as adsorbent. Feed consisting of CO2 and N2 mixture was used for carrying out the adsorption. The influence of bed temperature, feed rate, equilibrium partial pressure and initial % CO2 in feed were considered for analyzing adsorption-desorption process. It was found that the total adsorption-desorption cycle time decreases with increased column temperature and feed rates. The time required to achieve the condition of bed saturation decreases with increased bed temperature and feed rates. The amount of CO2 adsorbed/Kg of the adsorbent declines with increased bed temperature with in studied range for sorbent-1 and sorbent-2. It was suggested that the adsorption capacity of the both the sorbents increases with increased partial pressure of the gas.

Anaerobic biodegradation of diesel fuel-contaminated wastewater in a fluidized bed reactor.

Science.gov (United States)

Cuenca, M Alvarez; Vezuli, J; Lohi, A; Upreti, S R

2006-06-01

Diesel fuel spills have a major impact on the quality of groundwater. In this work, the performance of an Anaerobic Fluidized Bed Reactor (AFBR) treating synthetic wastewater is experimentally evaluated. The wastewater comprises tap water containing 100, 200 and 300 mg/L of diesel fuel and nutrients. Granular, inert, activated carbon particles are employed to provide support for biomass inside the reactor where diesel fuel is the sole source of carbon for anaerobic microorganisms. For different rates of organic loading, the AFBR performance is evaluated in terms of the removal of diesel fuel as well as chemical oxygen demand (COD) from wastewater. For the aforementioned diesel fuel concentrations and a wastewater flow rate of 1,200 L/day, the COD removal ranges between 61.9 and 84.1%. The concentration of diesel fuel in the effluent is less than 50 mg/L, and meets the Level II groundwater standards of the MUST guidelines of Alberta.

Method for the combustion of a gas, in fixed bed, with an oxidized solid and associated installation

OpenAIRE

Abanades García, Juan Carlos; Fernández García, José Ramón

2014-01-01

[EN] The present invention pertains to the field of the generation of energy from combustible gases, incorporating the capture of carbon dioxide for use or permanent storage and, specifically relates to cyclical methods of gas combustion with oxidized solids (chemical looping processes), in fixed bed, for solving the problem of controlling temperature in the combustion of gaseous fuels in fixed beds of metal oxides operating at high pressures, and also the associated installation.

Temperature prediction in a coal fired boiler with a fixed bed by fuzzy logic based on numerical solution

International Nuclear Information System (INIS)

Biyikoglu, A.; Akcayol, M.A.; Oezdemir, V.; Sivrioglu, M.

2005-01-01

In this study, steady state combustion in boilers with a fixed bed has been investigated. Temperature distributions in the combustion chamber of a coal fired boiler with a fixed bed are predicted using fuzzy logic based on data obtained from the numerical solution method for various coal and air feeding rates. The numerical solution method and the discretization of the governing equations of two dimensional turbulent flow in the combustion chamber and one dimensional coal combustion in the fixed bed are explained. Control Volume and Finite Difference Methods are used in the discretization of the equations in the combustion chamber and in the fixed bed, respectively. Results are presented as contours within the solution domain and compared with numerical ones. Comparison of the results shows that the difference between the numerical solution and fuzzy logic prediction throughout the computational domain is less than 1.5%. The statistical coefficient of multiple determinations for the investigated cases is about 0.9993 to 0.9998. This accuracy degree is acceptable in predicting the temperature values. So, it can be concluded that fuzzy logic provides a feasible method for defining the system properties

Study of Pressure Drop in Fixed Bed Reactor Using a Computational Fluid Dynamics (CFD Code

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Soroush Ahmadi

2018-04-01

Full Text Available Pressure drops of water and critical steam flowing in the fixed bed of mono-sized spheres are studied using SolidWorks 2017 Flow Simulation CFD code. The effects of the type of bed formation, flow velocity, density, and pebble size are evaluated. A new equation is concluded from the data, which is able to estimate pressure drop of a packed bed for high particle Reynolds number, from 15,000 to 1,000,000.

A Photocatalytic Active Adsorbent for Gas Cleaning in a Fixed Bed Reactor

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Peter Pucher

2008-01-01

Full Text Available Efficient photocatalysis for gas cleaning purposes requires a large accessible, illuminated active surface in a simple and compact reactor. Conventional concepts use powdered catalysts, which are nontransparent. Hence a uniform distribution of light is difficult to be attained. Our approach is based on a coarse granular, UV-A light transparent, and highly porous adsorbent that can be used in a simple fixed bed reactor. A novel sol-gel process with rapid micro mixing is used to coat a porous silica substrate with TiO2-based nanoparticles. The resulting material posses a high adsorption capacity and a photocatalytic activity under UV-A illumination (PCAA = photocatalytic active adsorbent. Its photocatalytic performance was studied on the oxidation of trichloroethylene (TCE in a fixed bed reactor setup in continuous and discontinuous operation modes. Continuous operation resulted in a higher conversion rate due to less slip while discontinuous operation is superior for a total oxidation to CO2 due to a user-defined longer residence time.

PENGOLAHAN LIMBAH CAIR INDUSTRI FARMASI FORMULASI DENGAN METODE ANAEROB-AEROB DAN ANAEROB-KOAGULASI

OpenAIRE

Farida Crisnaningtyas; Hanny Vistanty

2016-01-01

Studi ini membahas mengenai pengolahan limbah cair industri farmasi dalam skala laboratorium dengan menggunakan konsep anaerob-kimia-fisika dan anaerob-aerob. Proses anaerob dilakukan dengan menggunakan reaktor Upflow Anaerobic Sludge Bed reactor (UASBr) pada kisaran OLR (Organic Loading Rate) 0,5 – 2 kg COD/m3hari, yang didahului dengan proses aklimatisasi menggunakan substrat gula. Proses anaerob mampu memberikan efisiensi penurunan COD hingga 74%. Keluaran dari proses anaerob diolah lebih ...

Anaerobic treatment of textile dyeing wastewater.

Science.gov (United States)

Stern, S R; Szpyrkowicz, L; Rodighiero, I

2003-01-01

Aerobic treatment commonly applied to textile wastewater results in good or even excellent removal of organic load. This is not, however, accompanied by an equally good removal of colour. Traditional or advanced chemical methods of decolourisation are costly and not always reliable in justifying an interest in microbial decolourisation. Among several processes anaerobic methods seem most promising. In this paper, the results of a study conducted in two pilot-scale plants comprising anaerobic fixed bed biofilters of 15 L and 5 m3 operating as continuous reactors are presented, along with evaluation of the microbial kinetics. As is shown the process proved efficient in a long-term study with no stability problems of the biofilters. The six-month performance of the pilot plant confirmed also that the pre-treated wastewater could be applied in the operation of dyeing. For the majority of the colours applied in the factory no problems were encountered when the dyeing baths were prepared by substituting 90% of fresh water to the effluent treated by a sequence of activated sludge processes: anaerobic-aerobic.

Carbon dioxide hydrate formation in a fixed-bed reactor

Energy Technology Data Exchange (ETDEWEB)

Fan, S.; Lang, X. [South China Univ. of Technology, Guangzhou (China). Key Laboratory of Enhanced Heat Transfer and Energy Conservation; Wang, Y.; Liang, D. [Chinese Academy of Sciences, Guangzhou (China). Guangzhou Inst. of Energy Conversion and Guangzhou Center of Natural Gas Hydrate; Sun, X.; Jurcik, B. [Air Liquide Laboratories, Tsukuba (Japan)

2008-07-01

Gas hydrates are thermodynamically stable at high pressures and near the freezing temperature of pure water. Methane hydrates occur naturally in sediments in the deep oceans and permafrost regions and constitute an extensive hydrocarbon reservoir. Carbon dioxide (CO{sub 2}) hydrates are of interest as a medium for marine sequestration of anthropogenic carbon dioxide. Sequestering CO{sub 2} as hydrate has potential advantages over most methods proposed for marine CO{sub 2} sequestration. Because this technique requires a shallower depth of injection when compared with other ocean sequestration methods, the costs of CO{sub 2} hydrate sequestration may be lower. Many studies have successfully used different continuous reactor designs to produce CO{sub 2} hydrates in both laboratory and field settings. This paper discussed a study that involved the design and construction of a fixed-bed reactor for simulation of hydrate formation system. Water, river sands and carbon dioxide were used to simulate the seep kind of hydrate formation. Carbon dioxide gas was distributed as small bubbles to enter from the bottom of the fixed-bed reactor. The paper discussed the experimental data and presented a diagram of the gas hydrate reactor system. The morphology as well as the reaction characters of CO{sub 2} hydrate was presented in detail. The results were discussed in terms of experimental phenomena and hydrate formation rate. A mathematical model was proposed for describing the process. 17 refs., 7 figs.

Homogeneity of Continuum Model of an Unsteady State Fixed Bed Reactor for Lean CH4 Oxidation

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Subagjo

2014-07-01

Full Text Available In this study, the homogeneity of the continuum model of a fixed bed reactor operated in steady state and unsteady state systems for lean CH4 oxidation is investigated. The steady-state fixed bed reactor system was operated under once-through direction, while the unsteady-state fixed bed reactor system was operated under flow reversal. The governing equations consisting of mass and energy balances were solved using the FlexPDE software package, version 6. The model selection is indispensable for an effective calculation since the simulation of a reverse flow reactor is time-consuming. The homogeneous and heterogeneous models for steady state operation gave similar conversions and temperature profiles, with a deviation of 0.12 to 0.14%. For reverse flow operation, the deviations of the continuum models of thepseudo-homogeneous and heterogeneous models were in the range of 25-65%. It is suggested that pseudo-homogeneous models can be applied to steady state systems, whereas heterogeneous models have to be applied to unsteady state systems.

High performance biological methanation in a thermophilic anaerobic trickle bed reactor.

Science.gov (United States)

Strübing, Dietmar; Huber, Bettina; Lebuhn, Michael; Drewes, Jörg E; Koch, Konrad

2017-12-01

In order to enhance energy efficiency of biological methanation of CO 2 and H 2 , this study investigated the performance of a thermophilic (55°C) anaerobic trickle bed reactor (ATBR) (58.1L) at ambient pressure. With a methane production rate of up to 15.4m 3 CH4 /(m 3 trickle bed ·d) at methane concentrations above 98%, the ATBR can easily compete with the performance of other mixed culture methanation reactors. Control of pH and nutrient supply turned out to be crucial for stable operation and was affected significantly by dilution due to metabolic water production, especially during demand-orientated operation. Considering practical applications, inoculation with digested sludge, containing a diverse biocenosis, showed high adaptive capacity due to intrinsic biological diversity. However, no macroscopic biofilm formation was observed at thermophilic conditions even after 313days of operation. The applied approach illustrates the high potential of thermophilic ATBRs as a very efficient energy conversion and storage technology. Copyright © 2017 Elsevier Ltd. All rights reserved.

Molecular analysis of the biomass of a fluidized bed reactor treating synthetic vinasse at anaerobic and micro-aerobic conditions

NARCIS (Netherlands)

Rodriguez, E.; Lopes, A.; Fdz-Polanco, M.; Stams, A.J.M.; Garcia Encina, P.A.

2012-01-01

The microbial communities (Bacteria and Archaea) established in an anaerobic fluidized bed reactor used to treat synthetic vinasse (betaine, glucose, acetate, propionate, and butyrate) were characterized by denaturing gradient gel electrophoresis (DGGE) and phylogenetic analysis. This study was

Esterification of oleic acid in a three-phase, fixed-bed reactor packed with a cation exchange resin catalyst.

Science.gov (United States)

Son, Sung Mo; Kimura, Hiroko; Kusakabe, Katsuki

2011-01-01

Esterification of oleic acid was performed in a three-phase fixed-bed reactor with a cation exchange resin catalyst (Amberlyst-15) at high temperature, which was varied from 80 to 120 °C. The fatty acid methyl ester (FAME) yields in the fixed-bed reactor were increased with increases in the reaction temperature, methanol flow rate and bed height. Moreover, the FAME yields were higher than those obtained using a batch reactor due to an equilibrium shift toward the product that resulted from continuous evaporation of the produced water. In addition, there was no catalyst deactivation during the esterification of oleic acid. However, addition of sunflower oil to the oleic acid reduced the FAME yield obtained from simultaneous esterification and transesterification. The FAME yield was 97.5% at a reaction temperature of 100 °C in the fixed-bed with a height of 5 cm when the methanol and oleic acid feed rates were 8.6 and 9.0 mL/h, respectively. Copyright © 2010 Elsevier Ltd. All rights reserved.

Enhanced removal of sulfonamide antibiotics by KOH-activated anthracite coal: Batch and fixed-bed studies.

Science.gov (United States)

Zuo, Linzi; Ai, Jing; Fu, Heyun; Chen, Wei; Zheng, Shourong; Xu, Zhaoyi; Zhu, Dongqiang

2016-04-01

The presence of sulfonamide antibiotics in aquatic environments poses potential risks to human health and ecosystems. In the present study, a highly porous activated carbon was prepared by KOH activation of an anthracite coal (Anth-KOH), and its adsorption properties toward two sulfonamides (sulfamethoxazole and sulfapyridine) and three smaller-sized monoaromatics (phenol, 4-nitrophenol and 1,3-dinitrobenzene) were examined in both batch and fixed-bed adsorption experiments to probe the interplay between adsorbate molecular size and adsorbent pore structure. A commercial powder microporous activated carbon (PAC) and a commercial mesoporous carbon (CMK-3) possessing distinct pore properties were included as comparative adsorbents. Among the three adsorbents Anth-KOH exhibited the largest adsorption capacities for all test adsorbates (especially the two sulfonamides) in both batch mode and fixed-bed mode. After being normalized by the adsorbent surface area, the batch adsorption isotherms of sulfonamides on PAC and Anth-KOH were displaced upward relative to the isotherms on CMK-3, likely due to the micropore-filling effect facilitated by the microporosity of adsorbents. In the fixed-bed mode, the surface area-normalized adsorption capacities of Anth-KOH for sulfonamides were close to that of CMK-3, and higher than that of PAC. The irregular, closed micropores of PAC might impede the diffusion of the relatively large-sized sulfonamide molecules and in turn led to lowered fixed-bed adsorption capacities. The overall superior adsorption of sulfonamides on Anth-KOH can be attributed to its large specific surface area (2514 m(2)/g), high pore volume (1.23 cm(3)/g) and large micropore sizes (centered at 2.0 nm). These findings imply that KOH-activated anthracite coal is a promising adsorbent for the removal of sulfonamide antibiotics from aqueous solution. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fixed bed gasification of solid biomass fuels

Energy Technology Data Exchange (ETDEWEB)

Haavisto, I [Condens Oy, Haemeenlinna (Finland)

1997-12-31

Fixed bed biomass gasifiers are feasible in the effect range of 100 kW -10 MW. Co-current gasification is available only up to 1 MW for technical reasons. Counter-current gasifiers have been used in Finland and Sweden for 10 years in gasification heating plants, which are a combination of a gasifier and an oil boiler. The plants have proved to have a wide control range, flexible and uncomplicated unmanned operation and an excellent reliability. Counter-current gasifiers can be applied for new heating plants or for converting existing oil and natural gas boilers into using solid fuels. There is a new process development underway, aiming at motor use of the producer gas. The development work involves a new, more flexible cocurrent gasifier and a cleaning step for the counter-current producer gas. (orig.)

Fixed bed gasification of solid biomass fuels

Energy Technology Data Exchange (ETDEWEB)

Haavisto, I. [Condens Oy, Haemeenlinna (Finland)

1996-12-31

Fixed bed biomass gasifiers are feasible in the effect range of 100 kW -10 MW. Co-current gasification is available only up to 1 MW for technical reasons. Counter-current gasifiers have been used in Finland and Sweden for 10 years in gasification heating plants, which are a combination of a gasifier and an oil boiler. The plants have proved to have a wide control range, flexible and uncomplicated unmanned operation and an excellent reliability. Counter-current gasifiers can be applied for new heating plants or for converting existing oil and natural gas boilers into using solid fuels. There is a new process development underway, aiming at motor use of the producer gas. The development work involves a new, more flexible cocurrent gasifier and a cleaning step for the counter-current producer gas. (orig.)

Biodegradation of Methylene Blue Dye by Sequential Treatment Using Anaerobic Hybrid Reactor and Submerged Aerobic Fixed Film Bioreactor

Science.gov (United States)

Farooqi, Izharul H.; Basheer, Farrukh; Tiwari, Pradeepika

2017-12-01

Laboratory scale experiments were carried out to access the feasibility of sequential anaerobic/aerobic biological treatment for the biodegradation of Methylene Blue (MB) dye. Anaerobic studies were performed using anaerobic hybrid reactor (consisting of UASB and Anaerobic filter) whereas submerged aerobic fixed film reactor was used as aerobic reactor. Degradation of MB dye was attempted using neutralized acetic acid (1000 mg/L) as co-substrate. MB dye concentration was stepwise increased from 10 to 70 mg/L after reaching steady state in each dye concentration. Such a gradual increase in the dye concentration helps in the proper acclimatization of the sludge to dyes thereby avoiding the possible inhibitory effects to biological activities at high dye concentrations. The overall treatment efficiency of MB through sequential anaerobic-aerobic reactor operation was 90% at maximum attempted dye concentration of 70 mg/L. The effluent from anaerobic reactor was analysed for intermediate biodegradation products through HPLC. It was observed that catechol, quinone, amino pyrine, 1,4 diamino benzene were present. However they were absent in final effluent.

Anaerobic Digestion of Sugarcane Vinasse Through a Methanogenic UASB Reactor Followed by a Packed Bed Reactor.

Science.gov (United States)

Cabrera-Díaz, A; Pereda-Reyes, I; Oliva-Merencio, D; Lebrero, R; Zaiat, M

2017-12-01

The anaerobic treatment of raw vinasse in a combined system consisting in two methanogenic reactors, up-flow anaerobic sludge blanket (UASB) + anaerobic packed bed reactors (APBR), was evaluated. The organic loading rate (OLR) was varied, and the best condition for the combined system was 12.5 kg COD m -3 day -1 with averages of 0.289 m 3 CH 4  kg COD r -1 for the UASB reactor and 4.4 kg COD m -3 day -1 with 0.207 m 3 CH 4  kg COD r -1 for APBR. The OLR played a major role in the emission of H 2 S conducting to relatively stable quality of biogas emitted from the APBR, with H 2 S concentrations <10 mg L -1 . The importance of the sulphate to COD ratio was demonstrated as a result of the low biogas quality recorded at the lowest ratio. It was possible to develop a proper anaerobic digestion of raw vinasse through the combined system with COD removal efficiency of 86.7% and higher CH 4 and a lower H 2 S content in biogas.

Arsenic removal in a sulfidogenic fixed-bed column bioreactor

Energy Technology Data Exchange (ETDEWEB)

Altun, Muslum, E-mail: muslumaltun@hotmail.com [Hacettepe University, Department of Chemistry, Beytepe, Ankara (Turkey); Sahinkaya, Erkan [Istanbul Medeniyet University, Bioengineering Department, Goztepe, Istanbul (Turkey); Durukan, Ilknur; Bektas, Sema [Hacettepe University, Department of Chemistry, Beytepe, Ankara (Turkey); Komnitsas, Kostas [Technical University of Crete, Department of Mineral Resources Engineering, Chania (Greece)

2014-03-01

Highlights: • Sulfidogenic treatment of As-containing AMD was investigated. • High rate simultaneous removal of As and Fe was achieved. • As was removed without adding alkalinity or adjusting pH. • As and Fe removal mechanisms were elucidated. - Abstract: In the present study, the bioremoval of arsenic from synthetic acidic wastewater containing arsenate (As{sup 5+}) (0.5–20 mg/L), ferrous iron (Fe{sup 2+}) (100–200 mg/L) and sulfate (2000 mg/L) was investigated in an ethanol fed (780–1560 mg/L chemical oxygen demand (COD)) anaerobic up-flow fixed bed column bioreactor at constant hydraulic retention time (HRT) of 9.6 h. Arsenic removal efficiency was low and averaged 8% in case iron was not supplemented to the synthetic wastewater. Neutral to slightly alkaline pH and high sulfide concentration in the bioreactor retarded the precipitation of arsenic. Addition of 100 mg/L Fe{sup 2+} increased arsenic removal efficiency to 63%. Further increase of influent Fe{sup 2+} concentration to 200 mg/L improved arsenic removal to 85%. Decrease of influent COD concentration to its half, 780 mg/L, resulted in further increase of As removal to 96% when Fe{sup 2+} and As{sup 5+} concentrations remained at 200 mg/L and 20 mg/L, respectively. As a result of the sulfidogenic activity in the bioreactor the effluent pH and alkalinity concentration averaged 7.4 ± 0.2 and 1736 ± 239 mg CaCO{sub 3}/L respectively. Electron flow from ethanol to sulfate averaged 72 ± 10%. X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analyses were carried out to identify the nature of the precipitate generated by sulfate reducing bacteria (SRB) activity. Precipitation of arsenic in the form of As{sub 2}S{sub 3} (orpiment) and co-precipitation with ferrous sulfide (FeS), pyrite (FeS{sub 2}) or arsenopyrite (FeAsS) were the main arsenic removal mechanisms.

Two-step upflow anaerobic sludge bed system for sewage treatment under subtropical conditions with posttreatment in waste stabilization ponds

NARCIS (Netherlands)

Seghezzo, L.; Trupiano, A.P.; Liberal, V.; Todd, P.G.; Figueroa, M.E.; Gutierrez, M.A.; Silva Wilches, Da A.C.; Iribarnegaray, M.; Guerra, R.G.; Arena, A.; Cuevas, C.M.; Zeeman, G.; Lettinga, G.

2003-01-01

A pilot-scale sewage treatment system consisting of two upflow anaerobic sludge bed (UASB) reactors followed by five waste stabilization ponds (WSPs) in series was studied under subtropical conditions. The first UASB reactor started up in only 1 mo (stable operation, high chemical oxygen demand

Coupling membrane pervaporation with a fixed-bed reactor for enhanced esterification of oleic acid with ethanol

International Nuclear Information System (INIS)

Han, Ying; Lv, Enmin; Ma, Lingling; Lu, Jie; Chen, Kexun; Ding, Jincheng

2015-01-01

Highlights: • The reactor coupling membrane pervaporation with a fixed-bed reactor was studied. • The factors effecting the esterification of oleic acid were investigated. • NaA zeolite membrane was used for dehydration in the coupled reactor. - Abstract: Process intensification through membrane pervaporation (PV) integrated with a fixed-bed reactor could be successfully applied to the esterification of oleic acid and ethanol, which is a crucial step in the biodiesel synthesis using waste oil and grease as resource. The properties of the NaA zeolite membrane such as structure, formulation and separation were investigated by scanning electronic microscopy–energy dispersive spectrometry (SEM–EDS), X-ray diffractometry (XRD) and PV dehydration. Results showed that the NaA zeolite membrane had good separating property for removing water from the organics mixture. The operating conditions were optimized as the ethanol to oleic acid molar ratio of 15:1, feedstock flow rate of 1.0 ml/min, reaction temperature of 80.0 °C and catalyst bed height of 132 mm. The final conversion of oleic acid increased from 84.23% to 87.18% by PV using the NaA zeolite membrane at 24.0 h of operation. The membrane showed good PV performance after used for eight successive runs in the PV-assisted esterification. The resin exhibited a much high catalytic activity and operation stability after used for 100 h in the consecutive single pass fixed-bed esterification.

Post-treatment of anaerobically degraded azo dye Acid Red 18 using aerobic moving bed biofilm process: Enhanced removal of aromatic amines

International Nuclear Information System (INIS)

Hosseini Koupaie, E.; Alavi Moghaddam, M.R.; Hashemi, S.H.

2011-01-01

Highlights: → Biofilm process was applied as post-treatment of anaerobically degraded an azo dye. → More than 65% of the dye total metabolites was completely mineralized. → Based on HPLC analysis, more than 80% of 1-naphthylamine-4-sulfonate was removed. → Inhibition of biofilm growth was increased with increasing the initial dye concentration. → Considerable porous morphology was observed in the SEM photographs of the biofilm. - Abstract: The application of aerobic moving bed biofilm process as post-treatment of anaerobically degraded azo dye Acid Red 18 was investigated in this study. The main objective of this work was to enhance removal of anaerobically formed the dye aromatic metabolites. Three separate sequential treatment systems were operated with different initial dye concentrations of 100, 500 and 1000 mg/L. Each treatment system consisted of an anaerobic sequencing batch reactor (An-SBR) followed by an aerobic moving bed sequencing batch biofilm reactor (MB-SBBR). Up to 98% of the dye decolorization and more than 80% of the COD removal occurred anaerobically. The obtained results suggested no significant difference in COD removal as well as the dye decolorization efficiency using three An-SBRs receiving different initial dye concentrations. Monitoring the dye metabolites through HPLC suggested that more than 80% of anaerobically formed 1-naphthylamine-4-sulfonate was completely removed in the aerobic biofilm reactors. Based on COD analysis results, at least 65-72% of the dye total metabolites were mineralized during the applied treatment systems. According to the measured biofilm mass and also based on respiration-inhibition test results, increasing the initial dye concentration inhibited the growth and final mass of the attached-growth biofilm in MB-SBBRs.

Treatment of petroleum refinery wastewater using a sequential anaerobic-aerobic moving-bed biofilm reactor system based on suspended ceramsite.

Science.gov (United States)

Lu, Mang; Gu, Li-Peng; Xu, Wen-Hao

2013-01-01

In this study, a novel suspended ceramsite was prepared, which has high strength, optimum density (close to water), and high porosity. The ceramsite was used to feed a moving-bed biofilm reactor (MBBR) system with an anaerobic-aerobic (A/O) arrangement to treat petroleum refinery wastewater for simultaneous removal of chemical oxygen demand (COD) and ammonium. The hydraulic retention time (HRT) of the anaerobic-aerobic MBBR system was varied from 72 to 18 h. The anaerobic-aerobic system had a strong tolerance to shock loading. Compared with the professional emission standard of China, the effluent concentrations of COD and NH3-N in the system could satisfy grade I at HRTs of 72 and 36 h, and grade II at HRT of 18 h. The average sludge yield of the anaerobic reactor was estimated to be 0.0575 g suspended solid/g CODremoved. This work demonstrated that the anaerobic-aerobic MBBR system using the suspended ceramsite as bio-carrier could be applied to achieving high wastewater treatment efficiency.

Numerical and experimental studies on effects of moisture content on combustion characteristics of simulated municipal solid wastes in a fixed bed

International Nuclear Information System (INIS)

Sun, Rui; Ismail, Tamer M.; Ren, Xiaohan; Abd El-Salam, M.

2015-01-01

Highlights: • The effects of moisture content on the burning process of MSW are investigated. • A two-dimensional mathematical model was built to simulate the combustion process. • Temperature distributions, process rates, gas species were measured and simulated. • The The conversion ratio of C/CO and N/NO in MSW are inverse to moisture content. - Abstract: In order to reveal the features of the combustion process in the porous bed of a waste incinerator, a two-dimensional unsteady state model and experimental study were employed to investigate the combustion process in a fixed bed of municipal solid waste (MSW) on the combustion process in a fixed bed reactor. Conservation equations of the waste bed were implemented to describe the incineration process. The gas phase turbulence was modeled using the k–ε turbulent model and the particle phase was modeled using the kinetic theory of granular flow. The rate of moisture evaporation, devolatilization rate, and char burnout was calculated according to the waste property characters. The simulation results were then compared with experimental data for different moisture content of MSW, which shows that the incineration process of waste in the fixed bed is reasonably simulated. The simulation results of solid temperature, gas species and process rate in the bed are accordant with experimental data. Due to the high moisture content of fuel, moisture evaporation consumes a vast amount of heat, and the evaporation takes up most of the combustion time (about 2/3 of the whole combustion process). The whole bed combustion process reduces greatly as MSW moisture content increases. The experimental and simulation results provide direction for design and optimization of the fixed bed of MSW

Numerical and experimental studies on effects of moisture content on combustion characteristics of simulated municipal solid wastes in a fixed bed

Energy Technology Data Exchange (ETDEWEB)

Sun, Rui, E-mail: Sunsr@hit.edu.cn [School of Energy Science and Engineering, Harbin Institute of Technology, 92, West Dazhi Street, Harbin 150001 (China); Ismail, Tamer M., E-mail: temoil@aucegypt.edu [Department of Mechanical Engineering, Suez Canal University, Ismailia (Egypt); Ren, Xiaohan [School of Energy Science and Engineering, Harbin Institute of Technology, 92, West Dazhi Street, Harbin 150001 (China); Abd El-Salam, M. [Department of Basic Science, Cairo University, Giza (Egypt)

2015-05-15

Highlights: • The effects of moisture content on the burning process of MSW are investigated. • A two-dimensional mathematical model was built to simulate the combustion process. • Temperature distributions, process rates, gas species were measured and simulated. • The The conversion ratio of C/CO and N/NO in MSW are inverse to moisture content. - Abstract: In order to reveal the features of the combustion process in the porous bed of a waste incinerator, a two-dimensional unsteady state model and experimental study were employed to investigate the combustion process in a fixed bed of municipal solid waste (MSW) on the combustion process in a fixed bed reactor. Conservation equations of the waste bed were implemented to describe the incineration process. The gas phase turbulence was modeled using the k–ε turbulent model and the particle phase was modeled using the kinetic theory of granular flow. The rate of moisture evaporation, devolatilization rate, and char burnout was calculated according to the waste property characters. The simulation results were then compared with experimental data for different moisture content of MSW, which shows that the incineration process of waste in the fixed bed is reasonably simulated. The simulation results of solid temperature, gas species and process rate in the bed are accordant with experimental data. Due to the high moisture content of fuel, moisture evaporation consumes a vast amount of heat, and the evaporation takes up most of the combustion time (about 2/3 of the whole combustion process). The whole bed combustion process reduces greatly as MSW moisture content increases. The experimental and simulation results provide direction for design and optimization of the fixed bed of MSW.

Demonstration of the Anaerobic Fluidized Bed Reactor for Pinkwater Treatment at McAlester Army Ammunition Plant

National Research Council Canada - National Science Library

Maloney, Stephen W; Heine, Robert L

2005-01-01

.... The bacteria are cultivated on granules of activated carbon contained in a fluidized bed. The demonstration equipment controlled the conditions to maintain favorable conditions for anaerobic bacteria through control of temperature, pH, and nutrients. Fuel grade ethanol was used as the substrate to maintain the bacterial population. The results show that this technique can be successful and less costly than the existing granular activated carbon adsorption process.

Impact of acclimation methods on microbial communities and performance of anaerobic fluidized bed membrane bioreactors

KAUST Repository

Labarge, Nicole

2016-10-17

An anaerobic fluidized bed membrane bioreactor (AFMBR) is a new and effective method for energy-efficient treatment of low strength wastewater, but the factors that affect performance are not well known. Different inocula and acclimation methods of the granular activated carbon (GAC) used in the reactor were examined here to determine their impact on chemical oxygen demand (COD) removal and microbial community composition of domestic wastewater-fed AFMBRs. AFMBRs inoculated with anaerobic digester sludge (D) or domestic wastewater (W) and fed domestic wastewater, or inoculated with a microbiologically diverse anaerobic bog sediment and acclimated using methanol (M), all produced the same COD removal of 63 ± 12% using a diluted wastewater feed (100 ± 21 mg L−1 COD). However, an AFMBR with GAC inoculated with anaerobic digester sludge and acclimated using acetate (A) showed significantly increased wastewater COD removal to 84 ± 6%. In addition, feeding the AFMBR with the M-acclimated GAC with an acetate medium for one week subsequently increased COD removal to 70 ± 6%. Microbial communities enriched on the GAC included Geobacter, sulfur-reducing bacteria, Syntrophaceae, and Chlorobiaceae, with reactor A having the highest relative abundance of Geobacter. These results showed that acetate was the most useful substrate for acclimation of GAC communities, and GAC harbors unique communities relative to those in the AFMBR influent and recirculated solution.

Biodegradation of phenol with chromium(VI) reduction in an anaerobic fixed-biofilm process-Kinetic model and reactor performance

International Nuclear Information System (INIS)

Lin, Yen-Hui; Wu, Chih-Lung; Hsu, Chih-Hao; Li, Hsin-Lung

2009-01-01

A mathematical model system was derived to describe the simultaneous removal of phenol biodegradation with chromium(VI) reduction in an anaerobic fixed-biofilm reactor. The model system incorporates diffusive mass transport and double Monod kinetics. The model was solved using a combination of the orthogonal collocation method and Gear's method. A laboratory-scale column reactor was employed to validate the kinetic model system. Batch kinetic tests were conducted independently to evaluate the biokinetic parameters used in the model simulation. The removal efficiencies of phenol and chromium(VI) in an anaerobic fixed-biofilm process were approximately 980 mg/g and 910 mg/g, respectively, under a steady-state condition. In the steady state, model-predicted biofilm thickness reached up to 350 μm and suspended cells in the effluent were 85 mg cell/l. The experimental results agree closely with the results of the model simulations.

The effect of moisture content on solid-state anaerobic digestion of dairy manure from a sawdust-bedded pack barn

Science.gov (United States)

The effect of moisture content on solid-state anaerobic digestion of dairy manure from a Korean sawdust-bedded pack barn was determined using laboratory-scale digesters operated at three moisture levels (70, 76, and 83% on a wet basis) at 37 C for 85 days. Results showed that digesters containing m...

The influence of bamboo-packed configuration to mixing characteristics in a fixed-bed reactor

Science.gov (United States)

Detalina, M.; Pradanawati, S. A.; Widyarani; Mamat; Nilawati, D.; Sintawardani, N.

2018-03-01

Fixed-bed reactors are commonly used as bioreactors for various applications, including chemicals production and organic wastewater treatment. Bioreactors are fixed with packing materials for attaching microorganisms. Packing materials should have high surface area and enable sufficient fluid flow in the reactor. Natural materials e.g. rocks and fibres are often used as packing materials. Commercially, packing materials are also produced from polymer with the advantage of customizable shapes. The objective of this research was to study the mixing pattern in a packed-bed reactor using bamboo as packing material. Bamboo was selected for its pipe-like and porous form, as well as its abundant availability in Indonesia. The cut bamboo sticks were installed in a reactor in different configurations namely vertical, horizontal, and random. Textile dye was used as a tracer. Our results show that the vertical configuration gave the least liquid resistant flow. Yet, the random configuration was the best configuration during mixing process.

Drying kinetics characteristic of Indonesia lignite coal (IBC) using lab scale fixed bed reactor

Energy Technology Data Exchange (ETDEWEB)

Kang, TaeJin; Jeon, DoMan; Namkung, Hueon; Jang, DongHa; Jeon, Youngshin; Kim, Hyungtaek [Ajou Univ., Suwon (Korea, Republic of). Div. of Energy Systems Research

2013-07-01

Recent instability of energy market arouse a lot of interest about coal which has a tremendous amount of proven coal reserves worldwide. South Korea hold the second rank by importing 80 million tons of coal in 2007 following by Japan. Among various coals, there is disused coal. It's called Low Rank Coal (LRC). Drying process has to be preceded before being utilized as power plant. In this study, drying kinetics of LRC is induced by using a fixed bed reactor. The drying kinetics was deduced from particle size, the inlet gas temperature, the drying time, the gas velocity, and the L/D ratio. The consideration on Reynold's number was taken for correction of gas velocity, particle size, and the L/D ratio was taken for correction packing height of coal. It can be found that active drying of free water and phase boundary reaction is suitable mechanism through the fixed bed reactor experiments.

Simultaneous denitrification and anaerobic digestion in GRAnular Bed Baffled Reactor (GRABBR)

International Nuclear Information System (INIS)

Baloch, M.I.; Akunna, J.C.

2002-01-01

This study elucidates the characteristics of compartmentalised anaerobic system seeded with UASB granules, called GRAanular Bed Baffled Reactor (GRABBR), for combined denitrification and anaerobic digestion processes. The reactor was used for the treatment of glucose enriched synthetic wastewater with various nitrate concentrations. The study was carried out with a 10 litre working volume GRABBR divided into 5 equal compartments operating at organic loading rate (OLR) of 20 kg COD/m 3 .d with a hydraulic retention time (HRT) of 6 hours. At these conditions, phase separation (between acidogenesis and methanogenesis) was created in the system and then the effect of varying nitrate concentrations (50-200 mg/l NO 3 -N) in the acidogenic zone (i.e. first compartment) was studied. Due to its unique compartmentalised design, denitrification was the major pathway for nitrate reduction with no noticeable dissimilatory nitrate reduction to ammonia (DNRA). More than 84% of all added nitrates were removed in the acidogenic zone, showing that acidogens possess high denitrifying capabilities. The denitrification rate increased with increase in nitrate concentration, with maximum value estimated as 175 mg NO 3 -N/l.h at influent nitrate concentration of 200 mg/l NO 3 -N in the acidogenic zone. Although nitrate addition resulted in lower methane production, COD removal efficiencies improved by up to 8% when compared with the reactor performance before nitrate addition. Furthermore, the alkalinity produced during denitrification improved the stability of the system by controlling the decrease in pH resulting from acidogenesis. The system encouraged simultaneous denitrification and anaerobic digestion in a single unit by accommodating denitrifiers in the early compartments and allowing methanogenesis to flourish in the downstream compartments of the system, thus minimising inhibition to methane producing bacteria by nitrates. (author)

Feasibility analysis of As(III) removal in a continuous flow fixed bed system by modified calcined bauxite (MCB)

International Nuclear Information System (INIS)

Bhakat, P.B.; Gupta, A.K.; Ayoob, S.

2007-01-01

This study examine the feasibility of As(III) removal from aqueous environment by an adsorbent, modified calcined bauxite (MCB) in a continuous flow fixed bed system. MCB exhibited excellent adsorption capacity of 520.2 mg/L (0.39 mg/g) with an adsorption rate constant 0.7658 L/mg h for an influent As(III) concentration of 1 mg/L. In a 2 cm diameter continuous flow fixed MCB bed, a depth of only 1.765 cm was found necessary to produce effluent As(III) concentration of 0.01 mg/L, from an influent of 1 mg/L at a flow rate of 8 mL/min. Also, bed heights of 10, 20, and 30 cm could treat 427.85, 473.88 and 489.17 bed volumes of water, respectively, to breakthrough. A reduction in adsorption capacity of MCB was observed with increase in flow rates. The theoretical service times evaluated from bed depth service time (BDST) approach for different flow rates and influent As(III) concentrations had shown good correlation with the corresponding experimental values. The theoretical breakthrough curve developed from constantly mixed batch reactor (CMBR) isotherm data also correlated well with experimental breakthrough curve

Fixed bed sorption of phosphorus from wastewater using iron oxide-based media derived from acid mine drainage

Science.gov (United States)

Sibrell, Philip L.; Tucker, T.W.

2012-01-01

Phosphorus (P) releases to the environment have been implicated in the eutrophication of important water bodies worldwide. Current technology for the removal of P from wastewaters consists of treatment with aluminum (Al) or iron (Fe) salts, but is expensive. The neutralization of acid mine drainage (AMD) generates sludge rich in Fe and Al oxides that has hitherto been considered a waste product, but these sludges could serve as an economical adsorption media for the removal of P from wastewaters. Therefore, we have evaluated an AMD-derived media as a sorbent for P in fixed bed sorption systems. The homogenous surface diffusion model (HSDM) was used to analyze fixed bed test data and to determine the value of related sorption parameters. The surface diffusion modulus Ed was found to be a useful predictor of sorption kinetics. Values of Ed < 0.2 were associated with early breakthrough of P, while more desirable S-shaped breakthrough curves resulted when 0.2 < Ed < 0.5. Computer simulations of the fixed bed process with the HSDM confirmed that if Ed was known, the shape of the breakthrough curve could be calculated. The surface diffusion coefficient D s was a critical factor in the calculation of Ed and could be estimated based on the sorption test conditions such as media characteristics, and influent flow rate and concentration. Optimal test results were obtained with a relatively small media particle size (average particle radius 0.028 cm) and resulted in 96 % removal of P from the influent over 46 days of continuous operation. These results indicate that fixed bed sorption of P would be a feasible option for the utilization of AMD residues, thus helping to decrease AMD treatment costs while at the same time ameliorating the impacts of P contamination.

Empirical correlations for axial dispersion coefficient and Peclet number in fixed-bed columns.

Science.gov (United States)

Rastegar, Seyed Omid; Gu, Tingyue

2017-03-24

In this work, a new correlation for the axial dispersion coefficient was obtained using experimental data in the literature for axial dispersion in fixed-bed columns packed with particles. The Chung and Wen correlation, the De Ligny correlation are two popular empirical correlations. However, the former lacks the molecular diffusion term and the latter does not consider bed voidage. The new axial dispersion coefficient correlation in this work was based on additional experimental data in the literature by considering both molecular diffusion and bed voidage. It is more comprehensive and accurate. The Peclet number correlation from the new axial dispersion coefficient correlation on the average leads to 12% lower Peclet number values compared to the values from the Chung and Wen correlation, and in many cases much smaller than those from the De Ligny correlation. Copyright © 2017 Elsevier B.V. All rights reserved.

Modeling and Experimental Studies of Mercury Oxidation and Adsorption in a Fixed-Bed Reactor

Energy Technology Data Exchange (ETDEWEB)

Buitrago, Paula A.; Morrill, Mike; Lighty, JoAnn S.; Silcox, Geoffrey D.

2009-06-15

This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO₂, and halogen species were introduced through the burner to produce a radical pool representative of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO₂ increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO₂ concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO₂. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO₂, and NO₂. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and

A green strategy for desorption of trihalomethanes adsorbed by humin and reuse of the fixed bed column.

Science.gov (United States)

Cunha, G C; Romão, L P C; Santos, M C; Costa, A S; Alexandre, M R

2012-03-30

The objective of the present work was to develop a thermal desorption method for the removal of trihalomethanes (THM) adsorbed by humin, followed by multiple recycling of the fixed bed column in order to avoid excessive consumption of materials and reduce operating costs. The results obtained for adsorption on a fixed bed column confirmed the effectiveness of humin as an adsorbent, extracting between 45.9% and 90.1% of the total THM (TTHM). In none of the tests was the column fully saturated after 10h. Experiments involving thermal desorption were used to evaluate the potential of the technique for column regeneration. The adsorptive capacity of the humin bed increased significantly (p<0.05) between the first and fifth desorption cycle, by 18.9%, 18.1%, 24.2%, 20.2% and 24.2% for CHBr(3), CHBr(2)Cl, CHBrCl(2), CHCl(3) and TTHM, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

Fixed-bed biosorption of cadmium using immobilized Scenedesmus obliquus CNW-N cells on loofa (Luffa cylindrica) sponge.

Science.gov (United States)

Chen, Bor-Yann; Chen, Chun-Yen; Guo, Wan-Qian; Chang, Hao-Wei; Chen, Wen-Ming; Lee, Duu-Jong; Huang, Chieh-Chen; Ren, Nan-Qi; Chang, Jo-Shu

2014-05-01

A continuous fixed-bed biosorption process was established for cadmium (Cd) removal by Scenedesmus obliquus CNW-N (isolated from southern Taiwan) cells immobilized onto loofa sponge. This immobilized-cell biosorption process allows better recovery and reusability of the microalgal biomass. The growth of microalgae on the matrix support with appropriate nutrient supplementation could enhance the overall metal removal activity. Major operating parameters (e.g., feeding flow rate, cycle number of medium replacement, and particle diameter of the sponge) were studied for treatability evaluation. The most promising cell growth on the sponge support was obtained at a flow rate of 0.284 bed volume (BV)/min, sponge particle diameter of 1 cm, and with one cycle of medium replacement. The performance of fixed-bed biosorption (adsorption capacity of 38.4 mg, breakthrough time at 15.5 h) was achieved at a flow rate of 5 ml/min with an influent concentration of 7.5 mg Cd/l. Copyright © 2014 Elsevier Ltd. All rights reserved.

Performances and microbial features of an aerobic packed-bed biofilm reactor developed to post-treat an olive mill effluent from an anaerobic GAC reactor

Directory of Open Access Journals (Sweden)

Marchetti Leonardo

2006-04-01

Full Text Available Abstract Background Olive mill wastewater (OMW is the aqueous effluent of olive oil producing processes. Given its high COD and content of phenols, it has to be decontaminated before being discharged. Anaerobic digestion is one of the most promising treatment process for such an effluent, as it combines high decontamination efficiency with methane production. The large scale anaerobic digestion of OMWs is normally conducted in dispersed-growth reactors, where however are generally achieved unsatisfactory COD removal and methane production yields. The possibility of intensifying the performance of the process using a packed bed biofilm reactor, as anaerobic treatment alternative, was demonstrated. Even in this case, however, a post-treatment step is required to further reduce the COD. In this work, a biological post-treatment, consisting of an aerobic biological "Manville" silica bead-packed bed aerobic reactor, was developed, tested for its ability to complete COD removal from the anaerobic digestion effluents, and characterized biologically through molecular tools. Results The aerobic post-treatment was assessed through a 2 month-continuous feeding with the digested effluent at 50.42 and 2.04 gl-1day-1 of COD and phenol loading rates, respectively. It was found to be a stable process, able to remove 24 and 39% of such organic loads, respectively, and to account for 1/4 of the overall decontamination efficiency displayed by the anaerobic-aerobic integrated system when fed with an amended OMW at 31.74 and 1.70 gl-1day-1 of COD and phenol loading rates, respectively. Analysis of 16S rRNA gene sequences of biomass samples from the aerobic reactor biofilm revealed that it was colonized by Rhodobacterales, Bacteroidales, Pseudomonadales, Enterobacteriales, Rhodocyclales and genera incertae sedis TM7. Some taxons occurring in the influent were not detected in the biofilm, whereas others, such as Paracoccus, Pseudomonas, Acinetobacter and Enterobacter

Mathematical simulation of hazardous ion retention from radioactive waste in fixed bed reactor

International Nuclear Information System (INIS)

Sohsah, M.A.; Gohneim, M.M.; Othman, S.H.; El-Anadouli, B.E.

2007-01-01

Reactor design for fluid-solid, noncatalytic reaction depends on the prediction of the performance of the reactor kinetically. The most mathematical models used to handle fixed bed reactor in which the solid bed constitute one of the reactants, while a second reactant is in the fluid phase are complex and difficult to handle. A new mathematical model which easier to handle has been developed to describe the system under investigation. The model was examined theoretically and experimentally. A column backed with chelating cloth filter to separate radionuclide form radioactive waste solution is used as a practical application for the model. Comparison of the model predictions with the experimental results gives satisfactory agreement at most of the process stages

Thermal activation and characterization of clay aiming their use as sorbent in fixed bed columns to remove cadmium

International Nuclear Information System (INIS)

Silva, M.M. da; Rodrigues, M.G.F.; Silva, M.L.P.; Kleinübing, S.J.; Silva, M.G.C.

2011-01-01

In this work we studied the removal of cadmium in a synthetic wastewater using clay of Pernambuco - Brazil, in systems of fixed bed column. Clay was thermally activated at 500 °C. The materials were characterized using X-ray Fluorescence (XRF), X-ray Diffraction (XRD) and nitrogen adsorption (BET method). For tests in fixed bed column, we applied a factorial design 2"2 and found that increasing the flow adversely affects the process of removing cadmium concentration while acting positively. The studies showed these materials as promising for the removal of Cd"2"+ ions in synthetic wastewater containing low levels of this metal. (author)

Anaerobic up flow fluidized bed reactor performance as a primary treatment unit in domestic wastewater treatment

Directory of Open Access Journals (Sweden)

M.A. Moharram

2016-04-01

The efficiencies of Total nitrogen removal ranged between 2.23 and 10.83% with an apparent decrease during the low temperature high rate stages. Nitrite removal was in the range of (23.08–77% with up to the 2 mg/L in the effluent water when obtaining high organic loading and warm temperature. These results demonstrated that the domestic wastewater could be anaerobically treated in a fluidized bed UASB reactor with very low HRT reaching 2.5 h.

High temperature CO2 capture using calcium oxide sorbent in a fixed-bed reactor

International Nuclear Information System (INIS)

Dou Binlin; Song Yongchen; Liu Yingguang; Feng Cong

2010-01-01

The gas-solid reaction and breakthrough curve of CO 2 capture using calcium oxide sorbent at high temperature in a fixed-bed reactor are of great importance, and being influenced by a number of factors makes the characterization and prediction of these a difficult problem. In this study, the operating parameters on reaction between solid sorbent and CO 2 gas at high temperature were investigated. The results of the breakthrough curves showed that calcium oxide sorbent in the fixed-bed reactor was capable of reducing the CO 2 level to near zero level with the steam of 10 vol%, and the sorbent in CaO mixed with MgO of 40 wt% had extremely low capacity for CO 2 capture at 550 deg. C. Calcium oxide sorbent after reaction can be easily regenerated at 900 deg. C by pure N 2 flow. The experimental data were analyzed by shrinking core model, and the results showed reaction rates of both fresh and regeneration sorbents with CO 2 were controlled by a combination of the surface chemical reaction and diffusion of product layer.

Fixed bed column study for Cu (II) removal from aqueous solution using water hyacinth (Eichornia crassipes) biomass.

Science.gov (United States)

Gandhimathi, R; Ramesh, S T; Yadu, Anubhav; Bharathi, K S

2013-07-01

This paper reports the results of the study on the performance of low-cost biosorbent water hyacinth (WH) in removing Cu (II) from aqueous solution. The adsorbent material adopted was found to be an efficient media for the removal of Cu (II) in continuous mode using fixed bed column. The column studies were conducted with 10 mg/L metal solution with a flow rate of 10 mL/min with different bed depths such as 10, 20 and 30 cm. The column design parameters like adsorption rate constant, adsorption capacity and minimum bed depth were calculated. It was found that, the adsorption capacity of copper ions by water hyacinth increased by increasing the bed depth and the contact time.

Fixed bed adsorption of hexavalent chromium onto natural zeolite from air stream

OpenAIRE

F. Golbabaei; E. Rahmanzadeh; G. R. Moussavi; A. Faghihi zarandi; M. R. Baneshi

2014-01-01

Introduction: Chromium (VI) is a known human carcinogenic agent which is used in numerous industrial processes such as electroplating, welding, textile, cement and steel fabrication. The aim of this study was to determine the effectiveness of natural zeolite on the fixed bed adsorption of Cr (VI) from air stream. . Material and Method: In this experimental study, chromium mists were generated by a nebulizer (3A model, Italy). Performance of natural zeolite in the Cr (VI) adsorption and ...

Pyrolysis of the lignocellulose fermentation residue by fixed-bed micro reactor

International Nuclear Information System (INIS)

Wang, Ze; Lin, Weigang; Song, Wenli; Wu, Xuexing

2012-01-01

Thermal gravimetric (TG) analysis was conducted to compare the fundamental pyrolytic behaviors between the lignocellulose fermentation residue (LFR) and three other biomass raw materials. It was found that the TG weight loss curve of LFR appeared very close to the curve of acidified alkaline lignin (AAL), but different to the material of dried distillers grains with solubles (DDGS, also a fermentation residue but obtained from liquor producing process). Pyrolysis of LFR by fixed-bed micro reactor in the range of 430 °C–700 °C was carried out. It was found that the liquid yield had a maximum value at the pyrolytic temperature of 475 °C. The oil phase of the liquid was mainly composed of phenols, and the content of dimethyl phenol and fatty acids decreased with increasing pyrolytic temperature. In the aqueous liquid, besides the most abundant phenol derivatives, small acids and nitrogen containing compounds appeared more. -- Highlights: ► The tense of the paper has been revised. ► The description of the experimental procedure was kept in past tense. ► The expression of ‘fixed bed’ was changed to ‘fixed-bed’.

Distribution of volatile sulphur containing products during fixed bed pyrolysis and gasification of coals

Energy Technology Data Exchange (ETDEWEB)

Furimsky, E.

1991-08-01

Various coals were used to study the evolution of H{sub 2}S COS, and SO{sub 2} in a fixed bed reactor. For all types of coal, most of H{sub 2}S and SO{sub 2} were released during the devolatilization stage. COS was formed only during the gasification stage in the presence of CO{sub 2}.

Sorptive Removal of Cesium and Cobalt Ions in a Fixed bed Column Using Lewatit S100 Cation Exchange Resin

International Nuclear Information System (INIS)

El-Naggar, M.R.; Ibrahim, H.A.; El-Kamash, A.M.

2014-01-01

The sorptive removal of cesium and cobalt ions from aqueous solutions in a fixed bed column packed with Lewatit S100® cation exchange resin has been investigated. A preliminary batch studies were performed to estimate the effect of pH and contact time on the sorption process. Results indicated that Cs + and Co 2+ could be efficiently removed using Lewatit S100® at a ph range of 4-7 with more affinity towards Cs than Co 2+ . Kinetic models have been applied to the sorption rate data and the relevant parameters were determined. The obtained results indicated that the sorption of both Cs + and Co 2+ on Lewatit S100 followed pseudo second-order rather than pseudo first-order or Morris-Webber model. Fixed bed experiments were conducted at a constant initial concentration of 100 mg/l whereas the effect of bed depth (3, 4.5 and 6 cm) and volumetric flow rate (3 and 5 ml/min.) on the breakthrough characteristics of the fixed bed sorption systems were determined. The experimental sorption data were fitted to the well-established column models namely; Thomas and BDST models to compute the different model parameters. The higher column sorption capacities were obtained at bed depth of 3 cm with a flow rate of 3 ml/min., for both Cs + and Co 2+ . The BDST model appeared to describe experimental results better than Thomas model. Results indicate that Lewatit S100® is an efficient material for the removal of cesium and cobalt ions from aqueous solutions.

Scale-up and design optimisation of anaerobic immobilised cell reactors for wastewater treatment

Energy Technology Data Exchange (ETDEWEB)

Melidis, P.; Georgiou, D.; Aivasidis, A. [Department of Environmental Engineering, Demokritos University of Thrace, Xanthi (Greece)

2003-07-01

The legitimacy of model transfer in process technology has to date found no noteworthy influence on the design and dimensioning of immobilized cell bioreactors for anaerobic wastewater treatment. The latter still takes place solely on the basis of purely empirical rather than scientific considerations. However, it is possible to carry out design dimensioning on the basis of model theory considerations founded on process technology, as the examples of the design of fixed-bed-loop reactors and that of fluidized-bed reactors demonstrate. Together with the spatial separation of fermentative acid formation and methanogenesis (through a two-stage biology with two different microbial populations), a multi-stage design of methanisation through cascade connection of fixed-bed-loop reactors (for the narrowing of the residence time distribution) has proved particularly advantageous when applied to highly loaded and complex constituted wastewater. Technical reaction investigations on appropriately configured variants showed that for a COD conversion of 80-90% (wastewater from the foodstuffs industry), the reactor volume of the two-stage methanisation cascade could be reduced by 40-50% compared to that of the simply performed methanisation stage. (author)

Anaerobic biodegradation of cyanide under methanogenic conditions.

Science.gov (United States)

Fallon, R D; Cooper, D A; Speece, R; Henson, M

1991-01-01

Upflow, anaerobic, fixed-bed, activated charcoal biotreatment columns capable of operating at free cyanide concentrations of greater than 100 mg liter-1 with a hydraulic retention time of less than 48 h were developed. Methanogenesis was maintained under a variety of feed medium conditions which included ethanol, phenol, or methanol as the primary reduced carbon source. Under optimal conditions, greater than 70% of the inflow free cyanide was removed in the first 30% of the column height. Strongly complexed cyanides were resistant to removal. Ammonia was the nitrogen end product of cyanide transformation. In cell material removed from the charcoal columns, [14C]bicarbonate was the major carbon end product of [14C]cyanide transformation. PMID:1872600

Partial oxidation of Raffinate II and other mixtures of n-Butane and n-Butenes to maleic anhydride in a fixed-bed reactor

OpenAIRE

Brandstädter, Willi Michael

2008-01-01

The utilisation of the C4 streams of steamcrackers by converting raffinate II to maleic anhydride was studied. The oxidation reactions were investigated in a laboratory-scale fixed-bed reactor to determine reaction kinetics. The effects of pore diffusional resistance were investigated and explained. A two-dimensional pseudo-homogeneous reactor model was used for the simulation of a production-scale fixed-bed reactor. A flow scheme of the reactor section including a recycle was proposed.

A FIXED BED SORPTION SYSTEM FOR DEFLUORIDATION OF GROUND WATER

Directory of Open Access Journals (Sweden)

Ayoob Sulaiman

2009-06-01

Full Text Available The presence of excess fluoride in ground water has become a global threat with as many as 200 million people affected in more than 35 countries in all the continents. Of late, there have been significant advances in the knowledge base regarding the effects of excess fluoride on human health. As a result, defluoridation of ground water is regarded as one of the key areas of attention among the universal water community triggering global research. This study describes the sorptive responses of a newly developed adsorbent, alumina cement granules (ALC, in its real-life application in fixed beds, for removing fluoride from the ground waters of a rural Indian village. ALC exhibited almost consistent scavenging capacity at various bed depths in column studies with an enhanced adsorption potential of 0.818 mg/g at a flow rate of 4 ml/min. The Thomas model was examined to describe the sorption process. The process design parameters of the column were obtained by linear regression of the model. In all the conditions examined, the Thomas model could consistently predict its characteristic parameters and describe the breakthrough sorption profiles in the whole range of sorption process.

The fixed bed nuclear reactor concept

International Nuclear Information System (INIS)

Sahin, S.; Sefidvash, F.

2007-01-01

The core of a water moderated Fixed Bed Nuclear Reactor (FBNR), possessing, for instance, an electrical power of 40 MW, consists of 1.35 million fuel pellets (9.5 t) with a diameter of 1.5 cm each. The low enriched uranium fuel is made of TRISO type microspheres used in the HTGR, embedded in a graphite matrix and cladded by a shell of 1 mm SiC. Under any thinkable operational condition the fuel temperature will be below 400 C whereas its stability limit is at about 1600 C. The first characteristic of the FBNR is, therefore, its robust fuel under relatively 'cold' operating conditions and - due to the outer SiC - shell layer - the freedom from any hydrogen production. To operate the reactor the fuel pellets are pumped by a flow of water from below into the core regions where they form a stable fixed bed of about 4 cubic meter and become critical for energy production heating the outlet water to about 330 C (at 160 bar) which feeds a steam generator. The new safety feature is now the following: In case of any abnormity (e.g. external power failure, overheating etc.) the circulating pump stops and - due to gravity - the fuel pellets fall automatically out of the core region into a helical 'fuel chamber' underneath the core where their decay heat is transferred passively by natural circulation to a water tank housing the fuel chamber. The safety principle, applied here, is: The loss of an active component (circulating pump) induces a self-controlled, passively working shut-down manoeuvre accompanied by a foolproof decay heat removal without any emergency power system or any human interaction. The fuel chamber is sealed and is transported as the only reactor component to and from the reactor site. There is no possibility to irradiate fertile fuel, too. For a long-life core (larger than a 10 years cycle time) the fuel can either be poisoned by gadolinium-oxide or by a piston type core limiter adjusting the height and controlling thereby the number of the fuel pellets in

Benzene and ethylbenzene removal by denitrifying culture in a horizontal fixed bed anaerobic reactor

Energy Technology Data Exchange (ETDEWEB)

Gusmao, V.R.; Chinalia, F.A.; Sakamoto, I.K.; Varesche [Univ. de Sao Paulo (Brazil). Dept. de Hidraulica e Saneamento; Thiemann, O.H. [Univ. de Sao Paulo (Brazil). Inst. de Fisica de Sao Carlos

2004-07-01

Benzene, ethylbenzene, toluene, and xylene are toxic and are important constituents of gasoline and other petroleum fuels. These compounds are potential health hazards because of their high solubility and hence their ability to contaminate groundwater. Anaerobic immobilized biomass is a way of treating wastewater contaminated with the above compounds. The performance of a specially adapted biofilm is critical in the viability of this idea. In this investigation, an especially adapted biofilm was obtained using a denitrifying bacterial strain isolated from a slaughterhouse wastewater treatment plant. The strain was cultured in a liquid medium with added ethanol, nitrate, ethylbenzene, and benzene. To assess the viability of the strain for the purposes of degradation of ethylbenzene, and benzene two separate horizontal reactors were prepared with polyurethane foam in order to immobilize the biomass. Various concentrations of the two compounds were admitted. At high concentrations chemical oxygen demand decreased dramatically and benzene and ethylbenzene removal almost 100 per cent. DNA sequencing of the biofilm showed that Paracoccus versutus was the dominant species in the ethylbenzene reactor. 7 refs., 6 figs.

Solid diffusion control of the adsorption of basic dyes onto granular activated carbon and natural zeolite in fixed bed columns

Directory of Open Access Journals (Sweden)

M. MARINKOVSKI

2001-07-01

Full Text Available The adsorption of basic dyes from aqueous solutions onto granular activated carbon and natural zeolite was studied using a fixed bed column. The design procedures for fixed bed adsorption columns were investigated for two basic dyes Maxilon Goldgelb GL EC 400 % (MG-400 and Maxilon Schwarz FBL-01 300 % (MS-300. A computer program based on the solid diffusion control model has been developed. The model parameters: solid diffusion coefficient, DS, axial dispersion coefficient, DL and external mass transfer coefficient, kf for all the investigated systems were estimated by means of a best fit approach.

Design Strategy for CO2 Adsorption from Ambient Air Using a Supported Amine Based Sorbent in a Fixed Bed Reactor

NARCIS (Netherlands)

Yu, Qian; Brilman, D. W.F.

In this work, a fixed bed reactor is evaluated for CO2 capture from ambient air using an amine based ion exchange resin. Using adsorption experiments, the effect of superficial velocity and bed length on process economics is investigated. It is shown that the optimal conditions are found at an

Remediation of trichloroethylene by bio-precipitated and encapsulated palladium nanoparticles in a fixed bed reactor.

Science.gov (United States)

Hennebel, Tom; Verhagen, Pieter; Simoen, Henri; De Gusseme, Bart; Vlaeminck, Siegfried E; Boon, Nico; Verstraete, Willy

2009-08-01

Trichloroethylene is a toxic and recalcitrant groundwater pollutant. Palladium nanoparticles bio-precipitated on Shewanella oneidensis were encapsulated in polyurethane, polyacrylamide, alginate, silica or coated on zeolites. The reactivity of these bio-Pd beads and zeolites was tested in batch experiments and trichloroethylene dechlorination followed first order reaction kinetics. The calculated k-values of the encapsulated catalysts were a factor of six lower compared to non-encapsulated bio-Pd. Bio-Pd, used as a catalyst, was able to dechlorinate 100 mgL(-1) trichloroethylene within a time period of 1h. The main reaction product was ethane; yet small levels of chlorinated intermediates were detected. Subsequently polyurethane cubes empowered with bio-Pd were implemented in a fixed bed reactor for the treatment of water containing trichloroethylene. The influent recycle configuration resulted in a cumulative removal of 98% after 22 h. The same reactor in a flow through configuration achieved removal rates up to 1059 mg trichloroethylene g Pd(-1)d(-1). This work showed that fixed bed reactors with bio-Pd polyurethane cubes can be instrumental for remediation of water contaminated with trichloroethylene.

Temperature profile in a fix-bed reactor and with cylindrical geometry by the method of orthogonal collocation

International Nuclear Information System (INIS)

Basta, C.

1982-01-01

Using the method of orthogonal colocation the boundary problem for a fix bed with cylindrical geometry was solved. The axial disposal term was despicable and the results were compared with those the explicit finite difference method. (E.G.) [pt

TiO2-photocatalyzed As(III) oxidation in a fixed-bed, flow-through reactor.

Science.gov (United States)

Ferguson, Megan A; Hering, Janet G

2006-07-01

Compliance with the U.S. drinking water standard for arsenic (As) of 10 microg L(-1) is required in January 2006. This will necessitate implementation of treatment technologies for As removal by thousands of water suppliers. Although a variety of such technologies is available, most require preoxidation of As(III) to As(V) for efficient performance. Previous batch studies with illuminated TiO2 slurries have demonstrated that TiO2-photocatalyzed AS(III) oxidation occurs rapidly. This study examined reaction efficiency in a flow-through, fixed-bed reactor that provides a better model for treatment in practice. Glass beads were coated with mixed P25/sol gel TiO2 and employed in an upflow reactor irradiated from above. The reactor residence time, influent As(III) concentration, number of TiO2 coatings on the beads, solution matrix, and light source were varied to characterize this reaction and determine its feasibility for water treatment. Repeated usage of the same beads in multiple experiments or extended use was found to affect effluent As(V) concentrations but not the steady-state effluent As(III) concentration, which suggests that As(III) oxidation at the TiO2 surface undergoes dynamic sorption equilibration. Catalyst poisoning was not observed either from As(V) or from competitively adsorbing anions, although the higher steady-state effluent As(III) concentrations in synthetic groundwater compared to 5 mM NaNO3 indicated that competitive sorbates in the matrix partially hinder the reaction. A reactive transport model with rate constants proportional to incident light at each bead layer fit the experimental data well despite simplifying assumptions. TiO2-photocatalyzed oxidation of As(III) was also effective under natural sunlight. Limitations to the efficiency of As(III) oxidation in the fixed-bed reactor were attributable to constraints of the reactor geometry, which could be overcome by improved design. The fixed-bed TiO2 reactor offers an environmentally

Fixed bed sorption of phosphorus from wastewater using iron oxide-based media derived from acid mine drainage

Science.gov (United States)

Sibrell, Philip L.; Tucker, T.W.

2012-01-01

Phosphorus (P) releases to the environment have been implicated in the eutrophication of important water bodies worldwide. Current technology for the removal of P from wastewaters consists of treatment with aluminum (Al) or iron (Fe) salts, but is expensive. The neutralization of acid mine drainage (AMD) generates sludge rich in Fe and Al oxides that has hitherto been considered a waste product, but these sludges could serve as an economical adsorption media for the removal of P from wastewaters. Therefore, we have evaluated an AMD-derived media as a sorbent for P in fixed bed sorption systems. The homogenous surface diffusion model (HSDM) was used to analyze fixed bed test data and to determine the value of related sorption parameters. The surface diffusion modulus Ed was found to be a useful predictor of sorption kinetics. Values of Ed treatment costs while at the same time ameliorating the impacts of P contamination.

Sustainability and the Fixed Bed Nuclear Reactor (FBNR

Directory of Open Access Journals (Sweden)

Farhang Sefidvash

2012-08-01

Full Text Available Sustainability as a multifaceted and holistic concept is analyzed. Sustainability involves human relationship with elements such as natural environment, economy, power, governance, education and technology with the ultimate purpose of carrying forward an ever-advancing civilization. The Fixed Bed Nuclear Reactor (FBNR is an innovative, small, simple in design, inherently safe, non-proliferating, and environmentally friendly concept that its deployment can generate energy in a sustainable manner contributing to the prosperity of humanity. The development of FBNR will provide electricity as well as desalinated water through a simple but advanced technology for the developing, as well as developed countries. FBNR is environmentally friendly due to its inherent safety and the convenience of using its spent fuel as the source of radiation for irradiation purposes in agriculture, industry, and medicine. Politically, if a ping pong game brought peace between China and USA, a program of development of FBNR supported by the peace loving international community can become a more mature means to bring peace among certain apparently hostile nations who crave sustainable energy, desalinated water and simple advanced technology.

Batch and continuous (fixed-bed column) biosorption of crystal violet by Artocarpus heterophyllus (jackfruit) leaf powder.

Science.gov (United States)

Saha, Papita Das; Chakraborty, Sagnik; Chowdhury, Shamik

2012-04-01

In this study, batch and fixed-bed column experiments were performed to investigate the biosorption potential of Artocarpus heterophyllus (jackfruit) leaf powder (JLP) to remove crystal violet (CV) from aqueous solutions. Batch biosorption studies were carried out as a function of solution pH, contact time, initial dye concentration and temperature. The biosorption equilibrium data showed excellent fit to the Langmuir isotherm model with maximum monolayer biosorption capacity of 43.39 mg g(-1) at pH 7.0, initial dye concentration=50 mg L(-1), temperature=293 K and contact time=120 min. According to Dubinin-Radushkevich (D-R) isotherm model, biosorption of CV by JLP was chemisorption. The biosorption kinetics followed the pseudo-second-order kinetic model. Thermodynamic analysis revealed that biosorption of CV from aqueous solution by JLP was a spontaneous and exothermic process. In order to ascertain the practical applicability of the biosorbent, fixed-bed column studies were also performed. The breakthrough time increased with increasing bed height and decreased with increasing flow rate. The Thomas model as well as the BDST model showed good agreement with the experimental results at all the process parameters studied. It can be concluded that JLP is a promising biosorbent for removal of CV from aqueous solutions. Copyright © 2011 Elsevier B.V. All rights reserved.

PENGOLAHAN LIMBAH CAIR INDUSTRI FARMASI FORMULASI DENGAN METODE ANAEROB-AEROB DAN ANAEROB-KOAGULASI

Directory of Open Access Journals (Sweden)

Farida Crisnaningtyas

2016-05-01

Full Text Available Studi ini membahas mengenai pengolahan limbah cair industri farmasi dalam skala laboratorium dengan menggunakan konsep anaerob-kimia-fisika dan anaerob-aerob. Proses anaerob dilakukan dengan menggunakan reaktor Upflow Anaerobic Sludge Bed reactor (UASBr pada kisaran OLR (Organic Loading Rate 0,5 – 2 kg COD/m3hari, yang didahului dengan proses aklimatisasi menggunakan substrat gula. Proses anaerob mampu memberikan efisiensi penurunan COD hingga 74%. Keluaran dari proses anaerob diolah lebih lanjut dengan menggunakan dua opsi proses: (1 fisika-kimia, dan (2 aerob. Koagulan alumunium sulfat dan flokulan kationik memberikan efisiensi penurunan COD tertinggi (73% pada kecepatan putaran masing-masing 100 rpm dan 40 rpm. Uji coba aerob dilakukan pada kisaran MLSS antara 4000-5000 mg/L dan mampu memberikan efisiensi penurunan COD hingga 97%. Hasil uji coba menunjukkan bahwa efisiensi penurunan COD total yang dapat dicapai dengan menggunakan teknologi anaerob-aerob adalah 97%, sedangkan kombinasi anaerob-koagulasi-flokulasi hanya mampu menurunkan COD total sebesar 72,53%. Berdasarkan hasil tersebut, kombinasi proses anaerob-aerob merupakan teknologi yang potensial untuk diaplikasikan dalam sistem pengolahan limbah cair industri farmasi. 

Integrated anaerobic and aerobic treatment of sewage

NARCIS (Netherlands)

Wang, K.

1994-01-01

This thesis describes results of investigations dealing with sequential concept of anaerobic-aerobic treatment of municipal wastewater. The main purposes of the study were 1) to develop a proper anaerobic hydrolytic pretreatment unit, consisting of a Hydrolysis Upflow Sludge Bed (HUSB-)

Entrapment and degradation of particulate organics in anaerobic fluidized bed reactor. Kenkisei ryudosho ni yoru fuyusei yuki kokeibutsu no hosoku to bunkai

Energy Technology Data Exchange (ETDEWEB)

Araki, N. (Nagaoka National College of Technology, Niigata (Japan)); Harada, H.; Momonoi, K. (Nagaoka University of Technology, Niigata (Japan))

1993-08-10

A start-up experiment on an anaerobic fluidized bed reactor has been performed using simulated wastewater added with cellulose as a suspended substance to discuss behavior of suspended base materials and change in bacterial phases of biofilm constituting bacteria cluster. Cellulose removal efficiency of the reactor was 98% of a volumetric load of up to 2 g COD[center dot]1[sup -1][center dot]d[sup -1] performing efficient decomposition including methane. Cellulose content in the fluidized bed increased to 3% to 16% of the fluidized bed MLVSS with increase in a volumetric load from 3 to 10 g COD[center dot]1[sup -1][center dot]d[sup -1]. Bacteria, of which activity changes largely with growth of biofilms among other anaerobic bacteria clusters, are acid producing bacteria and acetic acid-selective methane bacteria, which have grown to 31 times and 70 times at maximum respectively as compared to their species sludge. Sludge resident time in the reactor has dropped rapidly from 80 days to 2.6 days as a result of accumulation of cellulose in the biofilms. The cellulose decomposing activity of the biofilms increases as the biofilms grow. The maximum value was 0.20 Cellulose[center dot]g[sup -1] VSS[center dot]d[sup -1]. 19 refs., 8 figs., 4 tabs.

Morphological study of biomass during the start-up period of a fixed-bed anaerobic reactor treating domestic sewage

OpenAIRE

Lima,Cláudio Antonio Andrade; Ribeiro,Rogers; Foresti,Eugenio; Zaiat,Marcelo

2005-01-01

This work focused on a morphological study of the microorganisms attached to polyurethane foam matrices in a horizontal-flow anaerobic immobilized biomass (HAIB) reactor treating domestic sewage. The experiments consisted of monitoring the biomass colonization process of foam matrices in terms of the amount of retained biomass and the morphological characteristics of the cells attached to the support during the start-up period. Non-fluorescent rods and cocci were found to predominate in the p...

Dynamic modeling of fixed-bed adsorption of flue gas using a variable mass transfer model

International Nuclear Information System (INIS)

Park, Jehun; Lee, Jae W.

2016-01-01

This study introduces a dynamic mass transfer model for the fixed-bed adsorption of a flue gas. The derivation of the variable mass transfer coefficient is based on pore diffusion theory and it is a function of effective porosity, temperature, and pressure as well as the adsorbate composition. Adsorption experiments were done at four different pressures (1.8, 5, 10 and 20 bars) and three different temperatures (30, 50 and 70 .deg. C) with zeolite 13X as the adsorbent. To explain the equilibrium adsorption capacity, the Langmuir-Freundlich isotherm model was adopted, and the parameters of the isotherm equation were fitted to the experimental data for a wide range of pressures and temperatures. Then, dynamic simulations were performed using the system equations for material and energy balance with the equilibrium adsorption isotherm data. The optimal mass transfer and heat transfer coefficients were determined after iterative calculations. As a result, the dynamic variable mass transfer model can estimate the adsorption rate for a wide range of concentrations and precisely simulate the fixed-bed adsorption process of a flue gas mixture of carbon dioxide and nitrogen.

Discussion on 'Solar detoxification of fuel-contaminated groundwater using fixed-bed photocatalysts'

Energy Technology Data Exchange (ETDEWEB)

Farrell, Joseph B.

1997-03-15

In a discussion of the 1997 paper by J. C. Crittenden et al. on the solar detoxification of fuel-contaminated groundwater using fixed-bed photocatalysts, the writer indicates a number of problems with the interpretation of the data and invites the authors to speculate on the reaction mechanism in the photocatalytic destruction of BTEX compounds in groundwater. In reply, Crittenden points out that it is not easy to speculate on the reaction mechanism because there are many compounds other than BTEX compounds contained in the water matrix, as well as many unknown compounds and by-products.

Fixed-bed hydrogen pyrolysis of rapeseed: product yields and compositions

International Nuclear Information System (INIS)

Onay, O.; Kockar, O.M.; Gaines, A.F.; Snape, C.E.

2006-01-01

The fixed-bed hydro pyrolysis tests have been conducted on a sample of rapeseed to investigate the effect of hydro pyrolysis on the yields and chemical structures of bio-oils, with a view to improving overall product quality. A ammonium dioxydithiomolybdenate catalyst has been used in some tests to further increase conversion. The maximum bio-oil yield of 84% was obtained in hydrogen atmosphere (with catalyst) at hydrogen pressure of 15 MPa, hydrogen flow rate of 10 dm 3 min -1 , hydro pyrolysis temperature of 520 degree C, and heating rate of 5 o Cmin -1 . Then this bio-oil was characterized by elemental analysis and some spectroscopic and chromatographic techniques. And finally, this bio-oil yield and chemical composition compared with oil obtained from fast pyrolysis condition

Effect of various drying bed on thermodynamic characteristics

Directory of Open Access Journals (Sweden)

Ali Motevali

2017-09-01

Full Text Available In this study thermodynamic parameter and energy consumption in drying of two plant dill and mint in three bed drying including fix, semi fix and fluid with using a hot air drying was investigated. Experimental was conducted in three bed drying including fix, semi fix and fluid and four levels temperature (30, 40, 50 and 60 °C. Maximum energy consumption in dill drying at 40 °C and fluid bed to be 16.41 MJ and minimum energy consumption at 30 °C and fix bed to be 2.77 MJ. Also minimum energy consumption in mint drying at 60 °C and fix bed to be 3.64 MJ and maximum energy consumption at 40 °C and fluid bed to be 28.65 MJ. The highest energy, drying and thermal efficiency for both mint and dill was achieved at 60 °C on the fixed bed, whereas the lowest efficiency was at 40 °C and on the fluidized bed. Also the highest power and specific heat consumption for both mint and dill was achieved at 40 °C on the fluid bed, whereas the lowest efficiency was at 30 °C and on the fluidized bed.

Design and optimization of a fixed - bed reactor for hydrogen production via bio-ethanol steam reforming

International Nuclear Information System (INIS)

Maria A Goula; Olga A Bereketidou; Costas G Economopoulos; Olga A Bereketidou; Costas G Economopoulos

2006-01-01

Global climate changes caused by CO 2 emissions are currently debated around the world. Renewable sources of energy are being sought as alternatives to replace fossil fuels. Hydrogen is theoretically the best fuel, environmentally friendly and its combustion reaction leads only to the production of water. Bio-ethanol has been proven to be effective in the production of hydrogen via steam reforming reaction. In this research the steam reforming reaction of bio-ethanol is studied at low temperatures over 15,3 % Ni/La 2 O 3 catalyst. The reaction and kinetic analysis takes place in a fixed - bed reactor in 130 - 250 C in atmospheric pressure. This study lays emphasis on the design and the optimization of the fixed - bed reactor, including the total volume of the reactor, the number and length of the tubes and the degree of ethanol conversion. Finally, it is represented an approach of the total cost of the reactor, according to the design characteristics and the materials that can be used for its construction. (authors)

Study of the obtainment of Mo_2C by gas-solid reaction in a fixed and rotary bed reactor

International Nuclear Information System (INIS)

Araujo, C.P.B. de; Souza, C.P. de; Souto, M.V.M.; Barbosa, C.M.; Frota, A.V.V.M.

2016-01-01

Carbides' synthesis via gas-solid reaction overcomes many of the difficulties found in other processes, requiring lower temperatures and reaction times than traditional metallurgic routes, for example. In carbides' synthesis in fixed bed reactors (FB) the solid precursor is permeated by the reducing/carburizing gas stream forming a packed bed without mobility. The use of a rotary kiln reactor (RK) adds a mixing character to this process, changing its fluid-particle dynamics. In this work ammonium molybdate was subjected to carbo-reduction reaction (CH4 / H2) in both reactors under the same gas flow (15L / h) and temperature (660 ° C) for 180 minutes. Complete conversion was observed Mo2C (dp = 18.9nm modal particles sizes' distribution) in the fixed bed reactor. In the RK reactor this conversion was only partial (∼ 40%) and Mo2C and MoO3 (34nm dp = bimodal) could be observed on the produced XRD pattern. Partial conversion was attributed to the need to use higher solids loading in the reactor CR (50% higher) to avoid solids to centrifuge. (author)

The phenomenon of granulation of anaerobic sludge

NARCIS (Netherlands)

Hulshoff Pol, L.

1989-01-01

Successful high-rate anaerobic wastewater treatment can only be accomplished when the slowgrowing anaerobic biomass is efficiently held back in the anaerobic treatment system. This biomass retention can be achieved in various ways including immobilization of the organisms on fixed materials

Transformation of 1,1,1-trichloroethane in an anaerobic packed-bed reactor at various concentrations of 1,1,1-trichloroethane, acetate and sulfate

NARCIS (Netherlands)

deBest, JH; Jongema, H; Weijling, A; Doddema, HJ; Janssen, DB; Harder, W

Biotransformation of 1,1,1-trichloroethane (CH3CCl3) was observed in an anaerobic packed-bed reactor under conditions of both sulfate reduction and methanogenesis. Acetate (1 mM) served as an electron donor. CH3CCl3 was completely converted up to the highest investigated concentration of 10 mu M.

Simultaneous Coproduction of Hydrogen and Ethanol in Anaerobic Packed-Bed Reactors

Directory of Open Access Journals (Sweden)

Cristiane Marques dos Reis

2014-01-01

Full Text Available This study evaluated the use of an anaerobic packed-bed reactor for hydrogen production at different hydraulic retention times (HRT (1–8 h. Two reactors filled with expanded clay and fed with glucose (3136–3875 mg L−1 were operated at different total upflow velocities: 0.30 cm s−1 (R030 and 0.60 cm s−1 (R060. The effluent pH of the reactors was maintained between 4 and 5 by adding NaHCO3 and HCl solutions. It was observed a maximum hydrogen production rate of 0.92 L H2 h−1 L−1 in R030 at HRT of 1 h. Furthermore, the highest hydrogen yield of 2.39 mol H2 mol−1 glucose was obtained in R060. No clear trend was observed by doubling the upflow velocities at this experiment. High ethanol production was also observed, indicating that the ethanol-pathway prevailed throughout the experiment.

Performance of the fixed-bed of granular activated carbon for the removal of pesticides from water supply.

Science.gov (United States)

Alves, Alcione Aparecida de Almeida; Ruiz, Giselle Louise de Oliveira; Nonato, Thyara Campos Martins; Müller, Laura Cecilia; Sens, Maurício Luiz

2018-02-26

The application of a fixed bed adsorption column of granular activated carbon (FBAC-GAC), in the removal of carbaryl, methomyl and carbofuran at a concentration of 25 μg L -1 for each carbamate, from the public water supply was investigated. For the determination of the presence of pesticides in the water supply, the analytical technique of high-performance liquid chromatography with post-column derivatization was used. Under conditions of constant diffusivity, the FBAC-GAC was saturated after 196 h of operation on a pilot scale. The exhaust rate of the granular activated carbon (GAC) in the FBAC-GAC until the point of saturation was 0.02 kg GAC m -3 of treated water. By comparing a rapid small-scale column test and FBAC-GAC, it was confirmed that the predominant intraparticle diffusivity in the adsorption column was constant diffusivity. Based on the results obtained on a pilot scale, it was possible to estimate the values to be applied in the FBAC-GAC (full scale) to remove the pesticides, which are particle size with an average diameter of 1.5 mm GAC; relationship between the internal diameter of the column and the average diameter of GAC ≥50 in order to avoid preferential flow near the adsorption column wall; surface application rate 240 m 3  m -2  d -1 and an empty bed contact time of 3 min. BV: bed volume; CD: constant diffusivity; EBCT: empty bed contact time; FBAC-GAC: fixed bed adsorption column of granular activated carbon; GAC: granular activated carbon; MPV: maximum permitted values; NOM: natural organic matter; PD: proportional diffusivity; pH PCZ : pH of the zero charge point; SAR: surface application rate; RSSCT: rapid small-scale column test; WTCS: water treated conventional system.

Fixed (slow moving) bed updraft gasification of agricultural residues

Energy Technology Data Exchange (ETDEWEB)

Vigouroux, Rolando Zanzi [Royal Institute of Technology (KTH), Stockholm (Sweden). Dept. of Chemical Engineering and Technology], E-mail: rolando@ket.kth.se; Escalona, Ronoldy Faxas [University of Oriente, Santiago de Cuba (Cuba). Fac. of Mechanical Engineering], E-mail: faxas@fim.uo.edu.cu

2009-07-01

Birch, in form of pellets has been gasified in updraft fixed-bed gasifier using air as oxidation agent. The main objectives were to study the effect of the treatment conditions on the distribution of the products and the composition of product gas. The influence of the air flow rates on the composition of the producer gas has been studied. The amount of the biomass used in the experiments was varied between 1 and 4 kg and the flow rate of the air was varied from 1.1 to 2.6 m3/h. Increased airflow rates favored higher temperatures. Excessively high airflow rates resulted in fast consumption of the biomass and it also favored combustion over gasification and thus formation of lower amounts of combustible products. High airflow rates caused also higher yields of tars, due to the shorter residence time of the tar-rich gas in the gasifier and thus unfavorable conditions for tar cracking. (author)

Modeling and Experimental Studies of Mercury Oxidation and Adsorption in a Fixed-Bed and Entrained-Flow Reactor

Energy Technology Data Exchange (ETDEWEB)

Buitrago, Paula A. [Univ. of Utah, Salt Lake City, UT (United States); Morrill, Mike [Univ. of Utah, Salt Lake City, UT (United States); Lighty, JoAnn S. [Univ. of Utah, Salt Lake City, UT (United States); Silcox, Geoffrey D. [Univ. of Utah, Salt Lake City, UT (United States)

2009-06-01

This report presents experimental and modeling mercury oxidation and adsorption data. Fixed-bed and single-particle models of mercury adsorption were developed. The experimental data were obtained with two reactors: a 300-W, methane-fired, tubular, quartz-lined reactor for studying homogeneous oxidation reactions and a fixed-bed reactor, also of quartz, for studying heterogeneous reactions. The latter was attached to the exit of the former to provide realistic combustion gases. The fixed-bed reactor contained one gram of coconut-shell carbon and remained at a temperature of 150°C. All methane, air, SO₂, and halogen species were introduced through the burner to produce a radical pool representative of real combustion systems. A Tekran 2537A Analyzer coupled with a wet conditioning system provided speciated mercury concentrations. At 150°C and in the absence of HCl or HBr, the mercury uptake was about 20%. The addition of 50 ppm HCl caused complete capture of all elemental and oxidized mercury species. In the absence of halogens, SO₂ increased the mercury adsorption efficiency to up to 30 percent. The extent of adsorption decreased with increasing SO₂ concentration when halogens were present. Increasing the HCl concentration to 100 ppm lessened the effect of SO₂. The fixed-bed model incorporates Langmuir adsorption kinetics and was developed to predict adsorption of elemental mercury and the effect of multiple flue gas components. This model neglects intraparticle diffusional resistances and is only applicable to pulverized carbon sorbents. It roughly describes experimental data from the literature. The current version includes the ability to account for competitive adsorption between mercury, SO₂, and NO₂. The single particle model simulates in-flight sorbent capture of elemental mercury. This model was developed to include Langmuir and Freundlich isotherms, rate equations, sorbent feed rate, and

Feasibility analysis of color removal from textile dyeing wastewater in a fixed-bed column system by surfactant-modified zeolite (SMZ)

International Nuclear Information System (INIS)

Ozdemir, Ozgur; Turan, Mustafa; Turan, Abdullah Zahid; Faki, Aysegul; Engin, Ahmet Baki

2009-01-01

In this study, the ability of surfactant-modified zeolite (SMZ) to remove color from real textile wastewater was investigated. Tests were performed in a fixed-bed column reactor and the surface of natural zeolite was modified with a quaternary amine surfactant hexadecyltrimethylammonium bromide (HTAB). The zeolite bed that was modified at 1 g L -1 HTAB concentration and HTAB flow rate of 0.015 L min -1 showed good performance in removing color. Effects of wastewater color intensity, flow rates and bed heights were also studied. Wastewater was diluted several times in the ratios of 25%, 50% and 75% in order to assess the influence of wastewater strength. The breakthrough curves of the original and diluted wastewaters are dispersed due to the fact that breakthrough came late at lower color intensities and saturation of the bed appeared faster at higher color intensities. The column had a 3-cm diameter and four different bed heights of 12.5, 25, 37.5 and 50 cm, which treated 5.25, 19.50, 35.25 and 51 L original textile wastewater, respectively, at the breakthrough time at a flow rate of 0.025 L min -1 . The theoretical service times evaluated from bed depth service time (BDST) approach for different column variables. The calculated and theoretical values of the exchange zone height were found with a difference of 27%. The various design parameters obtained from fixed-bed experimental studies showed good correlation with corresponding theoretical values, under different bed heights. The regeneration of the SMZ was also evaluated using a solution consisting of 30 g L -1 NaCl and 1.5 g L -1 NaOH at pH 12 and temperature 30 o C. Twice-regenerated SMZ showed the best performance compared with the others while first- and thrice-regenerated perform lower than the original SMZ.

Biological phosphorus removal during high-rate, low-temperature, anaerobic digestion of wastewater

Directory of Open Access Journals (Sweden)

Ciara eKeating

2016-03-01

Full Text Available We report, for the first time, extensive biologically-mediated phosphate removal from wastewater during high-rate anaerobic digestion (AD. A hybrid sludge bed/fixed-film (packed pumice stone reactor was employed for low-temperature (12°C anaerobic treatment of synthetic sewage wastewater. Successful phosphate removal from the wastewater (up to 78% of influent phosphate was observed, mediated by biofilms in the reactor. Scanning electron microscopy and energy dispersive X-ray analysis revealed the accumulation of elemental phosphorus (~2% within the sludge bed and fixed-film biofilms. 4’, 6-diamidino-2-phenylindole (DAPI staining indicated phosphorus accumulation was biological in nature and mediated through the formation of intracellular inorganic polyphosphate (polyP granules within these biofilms. DAPI staining further indicated that polyP accumulation was rarely associated with free cells. Efficient and consistent chemical oxygen demand (COD removal was recorded, throughout the 732-day trial, at applied organic loading rates between 0.4-1.5 kg COD m-3 d-1 and hydraulic retention times of 8-24 hours, while phosphate removal efficiency ranged from 28-78% on average per phase. Analysis of protein hydrolysis kinetics and the methanogenic activity profiles of the biomass revealed the development, at 12˚C, of active hydrolytic and methanogenic populations. Temporal microbial changes were monitored using Illumina Miseq analysis of bacterial and archaeal 16S rRNA gene sequences. The dominant bacterial phyla present in the biomass at the conclusion of the trial were the Proteobacteria and Firmicutes and the dominant archaeal genus was Methanosaeta. Trichococcus and Flavobacterium populations, previously associated with low temperature protein degradation, developed in the reactor biomass. The presence of previously characterised polyphosphate accumulating organisms (PAOs such as Rhodocyclus, Chromatiales, Actinobacter and Acinetobacter was

An overview of CFD modelling of small-scale fixed-bed biomass pellet boilers with preliminary results from a simplified approach

International Nuclear Information System (INIS)

Chaney, Joel; Liu Hao; Li Jinxing

2012-01-01

Highlights: ► Overview of the overall approach of modelling fixed-bed biomass boilers in CFD. ► Bed sub-models of moisture evaporation, devolatisation and char combustion reviewed. ► A method of embedding a combustion model in discrete fuel zones within the CFD is suggested. ► Includes sample of preliminary results for a 50 kW pellet boiler. ► Clear physical trends predicted. - Abstract: The increasing global energy demand and mounting pressures for CO 2 mitigation call for increased efficient utilization of biomass, particularly for heating domestic and commercial buildings. The authors of the present paper are investigating the optimization of the combustion performance and NO x emissions of a 50 kW biomass pellet boiler fabricated by a UK manufacturer. The boiler has a number of adjustable parameters including the ratio of air flow split between the primary and secondary supplies, the orientation, height, direction and number of the secondary inlets. The optimization of these parameters provides opportunities to improve both the combustion efficiency and NO x emissions. When used carefully in conjunction with experiments, Computational Fluid Dynamics (CFD) modelling is a useful tool for rapidly and at minimum cost examining the combustion performance and emissions from a boiler with multiple variable parameters. However, modelling combustion and emissions of a small-scale biomass pellet boiler is not trivial and appropriate fixed-bed models that can be coupled with the CFD code are required. This paper reviews previous approaches specifically relevant to simulating fixed-bed biomass boilers. In the first part it considers approaches to modelling the heterogeneous solid phase and coupling this with the gas phase. The essential components of the sub-models are then overviewed. Importantly, for the optimization process a model is required that has a good balance between accuracy in predicting physical trends, with low computational run time. Finally, a

Optimization of annatto (Bixa orellana L. drying in fixed bed

Directory of Open Access Journals (Sweden)

Faria L.J.G.

2000-01-01

Full Text Available The drying of annatto seeds (Bixa orellana L., red piave cultivate, was studied in a fixed bed dryer. The best conditions were estimated to minimize the loss of coloring and to obtain final moisture of the seeds in appropriate levels to its conservation and maintenance of quality. The quantification of the influence of entrance variables in the final contents of bixin and moisture seeds and the identification of the optimal point was performed through the techniques of factorial design, response surfaces methodology, canonical analysis and desirability function. It was verified that the final moisture of the seeds may be estimated by a second-order polynomial model and that the final content of bixin is only significantly influenced by the time of drying being described properly by a linear model, for the seeds used in this study.

Experimental studies of the influence of fuel properties and operational conditions on stoking when combusting fuels in a fixed-bed reactor

Energy Technology Data Exchange (ETDEWEB)

Arias, Fabiana; Kolb, T.; Seifert, H.; Gehrmann, Hans-Joachim [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. for Technical Chemistry (ITC)

2013-09-01

Besides from knowledge about pollutant emission, knowledge of the combustion behavior of fuels plays a major role in the operation and optimization of combustion plants for waste and biomass. If the fuel is exchanged partly or completely in existing or newly designed grate-type combustion plants, adaptation of technical parameters is usually based on purely empirical studies. In the KLEAA fixed-bed reactor of KIT, Institute for Technical Chemistry (ITC), quantitative data on the combustion behavior can be determined from experimental investigations on the laboratory scale. Based on the characteristics obtained, the combustion behavior on a continuous grate can be estimated, This estimation is based on the assumption that no back mixing of the fuel occurs on the grate. Depending on the type of grate, however, stoking and back mixing play an important role. To improve the quality of the characteristics determined in KLEAA and enhance their transferability to the continuous process, it is necessary to determine the influence of fuel properties and operation conditions on stoking. Work is aimed at further developing the characteristics model taking into account a stoking factor describing the combustion behavior of a non-stoked fixed bed compared to a stoked fixed bed. The main task is to make a systematic study of the major parameters influencing stoking (e.g. stroke length, stroke frequency, geometry of the stoking unit, and fuel properties) in a fixed-bed reactor. The results shall be presented in the form of a semi-empirical equation. It is recommended to first study a model fuel, whose fuel properties are defined exactly and can be adjusted variably. Then, a stoking factor shall be derived from the studies. Possibly, a dimension analysis may be helpful. Finally, the results obtained are to be verified for residue-derived fuel. (orig.)

Cultivation and Differentiation of Encapsulated hMSC-TERT in a Disposable Small-Scale Syringe-Like Fixed Bed Reactor

DEFF Research Database (Denmark)

Weber, Christian; Pohl, Sebastian; Pörtner, Ralf

2007-01-01

The use of commercially available plastic syringes is introduced as disposable small-scale fixed bed bioreactors for the cultivation of implantable therapeutic cell systems on the basis of an alginate-encapsulated human mesenchymal stem cell line. The system introduced is fitted with a noninvasiv...

Techniques for controlling variability in gram staining of obligate anaerobes.

Science.gov (United States)

Johnson, M J; Thatcher, E; Cox, M E

1995-01-01

Identification of anaerobes recovered from clinical samples is complicated by the fact that certain gram-positive anaerobes routinely stain gram negative; Peptostreptococcus asaccharolyticus, Eubacterium plautii, Clostridium ramosum, Clostridium symbiosum, and Clostridium clostridiiforme are among the nonconformists with regard to conventional Gram-staining procedures. Accurate Gram staining of American Type Culture Collection strains of these anaerobic bacteria is possible by implementing fixing and staining techniques within a gloveless anaerobic chamber. Under anaerobic conditions, gram-positive staining occurred in all test organisms with "quick" fixing techniques with both absolute methanol and formalin. The results support the hypothesis that, when anaerobic bacteria are exposed to oxygen, a breakdown of the physical integrity of the cell wall occurs, introducing Gram stain variability in gram-positive anaerobes. PMID:7538512

Post-treatment of Fly Ash by Ozone in a Fixed Bed Reactor

DEFF Research Database (Denmark)

Pedersen, Kim Hougaard; Melia, M. C.; Jensen, Anker Degn

2009-01-01

to be fast. A kinetic model has been formulated, describing the passivation of carbon, and it includes the stoichiometry of the ozone consumption (0.8 mol of O-3/kg of C) and an ineffective ozone loss caused by catalytic decomposition. The simulated results correlated well with the experimental data....... prevents the AEA to be adsorbed. In the present work, two fly ashes have been ozonated in a fixed bed reactor and the results showed that ozonation is a potential post-treatment method that can lower the AEA requirements of a fly ash up to 6 times. The kinetics of the carbon oxidation by ozone was found...

Effect of organic loading rate on anaerobic treatment of slaughterhouse wastewater in a fluidised-bed reactor

Energy Technology Data Exchange (ETDEWEB)

Borja, R. [Consejo Superior de Investigaciones Cientificas, Seville (Spain). Inst. de la Grasa; Banks, C.J.; Zhengjian Wang [Manchester Univ. (United Kingdom). Inst. of Science and Technology

1995-09-01

COD removal efficiencies in the range 75.0-98.9% were achieved in an aerobic fluidised-bed reactor treating slaughterhouse wastewater, when evaluated at organic loading rates (OLR) of between 2.9 and 54.0 g COD/l.d, hydraulic retention times (HRT) of between 0.5 and 8 h and feed COD concentrations of between 250 and 4500 mg/l. More than 94% of feed COD could be removed up to OLR of about 27 g COD/l.d. Up to 0.320 litres of methane were produced per gram of COD removed and this methane production rate was independent of the OLR applied in this investigation. Volatile fatty acid (VFA) concentration in the reactor increased sharply at an OLR of about 30 g COD/l.d and, therefore, sufficient alkalinity should be provided to prevent pH from dropping to an undesirable level. The anaerobic fluidised-bed system can be operated at a significantly higher liquid throughput than other previously reported systems while maintaining its excellent efficiency. (Author)

Microbial community dynamics and biogas production from manure fractions in sludge bed anaerobic digestion.

Science.gov (United States)

Nordgård, A S R; Bergland, W H; Bakke, R; Vadstein, O; Østgaard, K; Bakke, I

2015-12-01

To elucidate how granular sludge inoculum and particle-rich organic loading affect the structure of the microbial communities and process performance in upflow anaerobic sludge bed (UASB) reactors. We investigated four reactors run on dairy manure filtrate and four on pig manure supernatant for three months achieving similar methane yields. The reactors fed with less particle rich pig manure stabilized faster and had highest capacity. Microbial community dynamics analysed by a PCR/denaturing gradient gel electrophoresis approach showed that influent was a major determinant for the composition of the reactor communities. Comparisons of pre- and non-adapted inoculum in the reactors run on pig manure supernatant showed that the community structure of the nonadapted inoculum adapted in approximately two months. Microbiota variance partitioning analysis revealed that running time, organic loading rate and inoculum together explained 26 and 31% of the variance in bacterial and archaeal communities respectively. The microbial communities of UASBs adapted to the reactor conditions in treatment of particle rich manure fractions, obtaining high capacity, especially on pig manure supernatant. These findings provide relevant insight into the microbial community dynamics in startup and operation of sludge bed reactors for methane production from slurry fractions, a major potential source of biogas. © 2015 The Society for Applied Microbiology.

Heat Transfer in a Fixed Biomass Char Bed

DEFF Research Database (Denmark)

Fjellerup, Jan Søren; Henriksen, Ulrik Birk; Glarborg, P.

2002-01-01

A thermal conductivity model based on the Yagi and Kunii model together with a bed model was developed to describe the thermal conductivity of a straw char bed. The bed model describes the relationship between the distance between particles and the external porosity. To verify the model, thermal ...

Fixed-bed adsorption separation of xylene isomers over sio2/silicallite-1 core-shell adsorbents

KAUST Repository

Khan, Easir A.

2013-12-29

SiO2/Silicalite-1 core-shell material has been demonstrated as potential shape selective adsorbent in gas phase separation of p-xylene from a mixture of p/o-xylene isomers. The core-shell composite comprised of large silica core and thin polycrystalline silicalite-1 shell which was synthesized via a self-assembly of silicalite-1 nanocrystals on core silica surface followed by a secondary seeded growth method. The core materials, SiO2 used in this study has mesoporosity with an average pore diameter of 60Å and hence offers no shape selectivity for xylene isomers. However, the shell, silicalite-1 contains rigid pore structures and preferentially adsorbs p-xylene from their isomers mixtures. A series of adsorption fixed bed breakthrough adsorption/desorption experiment was performed to obtain the equilibrium isotherms and adsorption isotherm parameters of xylene isomers. The equilibrium isotherms of xylene isomers follow the Langmuir\\'s model. A chromatographic adsorption model has been used to describe the fixed-bed breakthrough profiles of xylene isomers. The model has successfully predicted the responses of the binary mixtures of p/o-xylene isomers. The SiO2/silicalite-1 core-shell adsorbents have shown para-selectivity as high as 15. © Bangladesh Uni. of Engg. & Tech.

NUMERICAL SOLUTION OF STEADY STATE DISPERSION FLOW MODEL FOR LACTOSE-LACTASE HYDROLYSIS WITH DIFFERENT KINETICS IN FIXED BED

Directory of Open Access Journals (Sweden)

OLAOSEBIKAN ABIDOYE OLAFADEHAN

2010-06-01

Full Text Available A detailed computational procedure for evaluating lactose hydrolysis with immobilized enzyme in a packed bed tubular reactor under dispersion flow conditions is presented. The dispersion flow model for lactose hydrolysis using different kinetics, taking cognizance of external mass transfer resistances, was solved by the method of orthogonal collocation. The reliability of model simulations was tested using experimental data from a laboratory packed bed column, where the -galactosidase of Kluyveromyces fragilis was immobilized on spherical chitosan beads. Comparison of the simulated results with experimental exit conversion shows that the dispersion flow model and using Michaelis-Menten kinetics with competitive product (galactose inhibition are appropriate to interpret the experimental results and simulate the process of lactose hydrolysis in a fixed bed.

HgCl{sub 2} sorption on lignite activated carbon: Analysis of fixed-bed results

Energy Technology Data Exchange (ETDEWEB)

Mibeck, Blaise A.F.; Olson, Edwin S.; Miller, Stanley J. [University of North Dakota Energy and Environmental Research Center, 15 North 23rd Street, Stop 9018, Grand Forks, ND 58202-9018 (United States)

2009-11-15

Factors that influence kinetic reactivity and equilibrium between elemental mercury, carbon, and flue gas components have been the focus of numerous studies. This study pertains to recent bench-scale fixed-bed tests in which activated carbon was exposed to HgCl{sub 2} in a flue gas composition typical of an unscrubbed eastern bituminous coal. Results are discussed in light of a refined binding site model based on the zigzag carbene structures recently proposed for electronic states at the edges of the carbon graphene layers. (author)

Phenol degradation in an anaerobic fluidized bed reactor packed with low density support materials

Directory of Open Access Journals (Sweden)

G. P. Sancinetti

2012-03-01

Full Text Available The objective of this research was to study phenol degradation in anaerobic fluidized bed reactors (AFBR packed with polymeric particulate supports (polystyrene - PS, polyethylene terephthalate - PET, and polyvinyl chloride - PVC. The reactors were operated with a hydraulic retention time (HRT of 24 h. The influent phenol concentration in the AFBR varied from 100 to 400 mg L-1, resulting in phenol removal efficiencies of ~100%. The formation of extracellular polymeric substances yielded better results with the PVC particles; however, deformations in these particles proved detrimental to reactor operation. PS was found to be the best support for biomass attachment in an AFBR for phenol removal. The AFBR loaded with PS was operated to analyze the performance and stability for phenol removal at feed concentrations ranging from 50 to 500 mg L-1. The phenol removal efficiency ranged from 90-100%.

Near-Bed Turbulent Kinetic Energy Budget Under a Large-Scale Plunging Breaking Wave Over a Fixed Bar

Science.gov (United States)

van der Zanden, Joep; van der A, Dominic A.; Cáceres, Iván.; Hurther, David; McLelland, Stuart J.; Ribberink, Jan S.; O'Donoghue, Tom

2018-02-01

Hydrodynamics under regular plunging breaking waves over a fixed breaker bar were studied in a large-scale wave flume. A previous paper reported on the outer flow hydrodynamics; the present paper focuses on the turbulence dynamics near the bed (up to 0.10 m from the bed). Velocities were measured with high spatial and temporal resolution using a two component laser Doppler anemometer. The results show that even at close distance from the bed (1 mm), the turbulent kinetic energy (TKE) increases by a factor five between the shoaling, and breaking regions because of invasion of wave breaking turbulence. The sign and phase behavior of the time-dependent Reynolds shear stresses at elevations up to approximately 0.02 m from the bed (roughly twice the elevation of the boundary layer overshoot) are mainly controlled by local bed-shear-generated turbulence, but at higher elevations Reynolds stresses are controlled by wave breaking turbulence. The measurements are subsequently analyzed to investigate the TKE budget at wave-averaged and intrawave time scales. Horizontal and vertical turbulence advection, production, and dissipation are the major terms. A two-dimensional wave-averaged circulation drives advection of wave breaking turbulence through the near-bed layer, resulting in a net downward influx in the bar trough region, followed by seaward advection along the bar's shoreward slope, and an upward outflux above the bar crest. The strongly nonuniform flow across the bar combined with the presence of anisotropic turbulence enhances turbulent production rates near the bed.

Acclimatization of anaerobic sludge for UASB-reactor start-up

NARCIS (Netherlands)

Zeeuw, de W.J.

1984-01-01

The Upflow Anaerobic Sludge Bed (UASB) reactor represents a high rate anaerobic wastewater treatment system. The majority of the active biomass in the reactor is present in the form of sludge granules which possess excellent settling properties.
If no acclimatized (granular)

Fixed-bed gasifier and cleanup system engineering summary report through Test Run No. 100

Energy Technology Data Exchange (ETDEWEB)

Pater, K. Jr.; Headley, L.; Kovach, J.; Stopek, D.

1984-06-01

The state-of-the-art of high-pressure, fixed-bed gasification has been advanced by the many refinements developed over the last 5 years. A novel full-flow gas cleanup system has been installed and tested to clean coal-derived gases. This report summarizes the results of tests conducted on the gasifier and cleanup system from its inception through 1982. Selected process summary data are presented along with results from complementary programs in the areas of environmental research, process simulation, analytical methods development, and component testing. 20 references, 32 figures, 42 tables.

Process Optimization for Ethyl Ester Production in Fixed Bed Reactor Using Calcium Oxide Impregnated Palm Shell Activated Carbon (CaO/PSAC

Directory of Open Access Journals (Sweden)

A Buasri

2012-11-01

Full Text Available : The continuous production of ethyl ester was studied by using a steady-state fixed bed reactor (FBR. Transesterification of palm stearin (PS and waste cooking palm oil (WCPO with ethanol in the presence of calcium oxide impregnated palm shell activated carbon (CaO/PSAC solid catalyst was investigated. This work was determined the optimum conditions for the production of ethyl ester from PS and WCPO in order to obtain fatty acid ethyl ester (FAEE with the highest yield. The effects of reaction variables such as residence time, ethanol/oil molar ratio, reaction temperature, catalyst bed height and reusability of catalyst in a reactor system on the yield of biodiesel were considered. The optimum conditions were the residence time 2-3 h, ethanol/oil molar ratio 16-20, reaction temperature at 800C, and catalyst bed height 300 mm which yielded 89.46% and 83.32% of the PS and WCPO conversion, respectively. CaO/PSAC could be used repeatedly for 4 times without any activation treatment and no obvious activity loss was observed. It has potential for industrial application in the transesterification of triglyceride (TG. The fuel properties of biodiesel were determined. Keywords: biodiesel, calcium oxide, ethyl ester, fixed bed reactor, palm shell activated carbon

Pyrolysis of Jatropha curcas pressed cake for bio-oil production in a fixed-bed system

International Nuclear Information System (INIS)

Jourabchi, Seyed Amirmostafa; Gan, Suyin; Ng, Hoon Kiat

2014-01-01

Highlights: • The pyrolysis of Jatropha curcas waste in a fixed-bed rig was studied. • Yield, calorific value, water content and acidity of bio-oil were compared. • Empirical correlations for bio-oil yield and specifications were developed. • Optimisation of bio-oil production based on combined specifications was achieved. - Abstract: This study investigated the effects of pyrolysis parameters on the yield and quality of bio-oil from Jatropha curcas pressed cake. This biomass was pyrolysed in a fixed-bed reactor over a temperature range of 573.15 K to 1073.15 K and a nitrogen linear speed range of 7.8 × 10 −5 m/s to 6.7 × 10 −2 m/s. The heating rate and biomass grain size were 50 K/min and <2 mm, respectively. The bio-oils were tested for the gross calorific value, water content and acidity. The pyrolysis process was simulated using Thermo-Gravimetric Analysis (TGA) and Differential Scanning Calorimeter (DSC) for mass and energy balances analyses. Empirical correlations between the bio-oil specifications and pyrolysis parameters were developed using linear and nonlinear multiple regression methods for process optimisation. At optimum pyrolysis conditions, above 50% of the waste is converted to bio-oil with less than 30% water content, a gross calorific value of 15.12 MJ/kg and a pH of 6.77

Determination of the enzyme reaction rate in a differential fixed-bed reactor: a case study

Directory of Open Access Journals (Sweden)

Baruque Filho E.A.

2001-01-01

Full Text Available The reaction rate of starch hydrolysis catalyzed by a glucoamylase covalently bound to chitin particles was measured in a Differential Fixed-Bed Reactor (DFBR. Under selected test conditions the initial reaction rate may represent biocatalyst activity. Some aspects which influence measurement of the initial reaction rate of an immobilized enzyme were studied: the amount of desorbed enzyme and its hydrolytic activity, the extent of pore blockage of the biocatalyst caused by substrate solution impurities and the internal and external diffusional mass transfer effects. The results showed that the enzyme glucoamylase was firmly bound to the support, as indicated by the very low amount of desorbed protein found in the recirculating liquid. Although this protein was very active, its contribution to the overall reaction rate was negligible. It was observed that the biocatalyst pores were susceptible to being blocked by the impurities of the starch solution. This latter effect was accumulative, increasing with the number of sequential experiments carried out. When the substrate solution was filtered before use, very reliable determinations of immobilized enzyme reaction rates could be performed in the DFBR. External and internal diffusional resistences usually play a significant role in fixed-bed reactors. However, for the experimental system studied, internal mass transfer effects were not significant, and it was possible to select an operational condition (recirculation flow rate value that minimized the external diffusional limitations.

Batch and fixed bed adsorption of levofloxacin on granular activated carbon from date (Phoenix dactylifera L.) stones by KOH chemical activation.

Science.gov (United States)

Darweesh, Teeba M; Ahmed, Muthanna J

2017-03-01

Granular activated carbon (KAC) was prepared from abundant Phoenix dactylifera L. stones by microwave- assisted KOH activation. The characteristics of KAC were tested by pore analyses, scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FTIR). The adsorption behavior of levofloxacin (LEV) antibiotic on KAC with surface area of 817m 2 /g and pore volume of 0.638cm 3 /g were analyzed using batch and fixed bed systems. The equilibrium data collected by batch experiments were well fitted with Langmuir compared to Freundlich and Temkin isotherms. The effect of flow rate (0.5-1.5ml/min), bed height (15-25cm), and initial LEV concentration (75-225mg/l) on the behavior of breakthrough curves was explained. The fixed bed analysis showed the better correlation of breakthrough data by both Thomas and Yoon-Nelson models. High LEV adsorption capacity of 100.3mg/g was reported on KAC, thus being an efficient adsorbent for antibiotic pollutants to protect ecological systems. Copyright © 2017 Elsevier B.V. All rights reserved.

Coefficient of solid-gas heat transfer in particle fixed bed; Coeficiente de transferencia de calor gas-solido em leito fixo de particulas

Energy Technology Data Exchange (ETDEWEB)

Fernandes Filho, Francisco

1991-03-01

The work presents a study on heat transfer between gas and solid phases for fixed beds in the absence of mass transfer and chemical reactions. Mathematical models presented in the literature were analyzed concerning to the assumptions made on axial dispersion in the fluid phase and interparticle thermal conductivity. Heat transfer coefficients and their dependency on flow conditions, particles and packed bed characteristics were experimentally determined through the solution of the previous mathematical models. Pressure drop behaviour for the packed beds used for the heat transfer study was also included. (author) 32 refs., 12 figs.

Numerical modelling of biomass combustion: Solid conversion processes in a fixed bed furnace

Science.gov (United States)

Karim, Md. Rezwanul; Naser, Jamal

2017-06-01

Increasing demand for energy and rising concerns over global warming has urged the use of renewable energy sources to carry a sustainable development of the world. Bio mass is a renewable energy which has become an important fuel to produce thermal energy or electricity. It is an eco-friendly source of energy as it reduces carbon dioxide emissions. Combustion of solid biomass is a complex phenomenon due to its large varieties and physical structures. Among various systems, fixed bed combustion is the most commonly used technique for thermal conversion of solid biomass. But inadequate knowledge on complex solid conversion processes has limited the development of such combustion system. Numerical modelling of this combustion system has some advantages over experimental analysis. Many important system parameters (e.g. temperature, density, solid fraction) can be estimated inside the entire domain under different working conditions. In this work, a complete numerical model is used for solid conversion processes of biomass combustion in a fixed bed furnace. The combustion system is divided in to solid and gas phase. This model includes several sub models to characterize the solid phase of the combustion with several variables. User defined subroutines are used to introduce solid phase variables in commercial CFD code. Gas phase of combustion is resolved using built-in module of CFD code. Heat transfer model is modified to predict the temperature of solid and gas phases with special radiation heat transfer solution for considering the high absorptivity of the medium. Considering all solid conversion processes the solid phase variables are evaluated. Results obtained are discussed with reference from an experimental burner.

Flow of power-law fluids in fixed beds of cylinders or spheres

KAUST Repository

Singh, John P.

2012-10-29

An ensemble average of the equations of motion for a Newtonian fluid over particle configurations in a dilute fixed bed of spheres or cylinders yields Brinkman\\'s equations of motion, where the disturbance velocity produced by a test particle is influenced by the Newtonian fluid stress and a body force representing the linear drag on the surrounding particles. We consider a similar analysis for a power-law fluid where the stress τ is related to the rate of strain e by τ = 2m en-1e, where m and n are constants. In this case, the ensemble-averaged momentum equation includes a body force resulting from the nonlinear drag exerted on the surrounding particles, a power-law stress associated with the disturbance velocity of the test particle, and a stress term that is linear with respect to the test particle\\'s disturbance velocity. The latter term results from the interaction of the test particle\\'s velocity disturbance with the random straining motions produced by the neighbouring particles and is important only in shear-thickening fluids where the velocity disturbances of the particles are long-ranged. The solutions to these equations using scaling analyses for dilute beds and numerical simulations using the finite element method are presented. We show that the drag force acting on a particle in a fixed bed can be written as a function of a particle-concentration-dependent length scale at which the fluid velocity disturbance produced by a particle is modified by hydrodynamic interactions with its neighbours. This is also true of the drag on a particle in a periodic array where the length scale is the lattice spacing. The effects of particle interactions on the drag in dilute arrays (periodic or random) of cylinders and spheres in shear-thickening fluids is dramatic, where it arrests the algebraic growth of the disturbance velocity with radial position when n≥ 1 for cylinders and n≥ 2 for spheres. For concentrated random arrays of particles, we adopt an

Structural characterisation of pretreated solids from flow-through liquid hot water treatment of sugarcane bagasse in a fixed-bed reactor

CSIR Research Space (South Africa)

Reddy, P

2015-05-01

Full Text Available Untreated sugarcane bagasse and sugarcane bagasse pretreated with flow-through liquid hot water (LHW) treatment (170-207°C and 204-250 ml/min) in a fixed-bed reactor have been structurally characterised. Field emission gun scanning electron...

Computer-aided modeling framework – a generic modeling template for catalytic membrane fixed bed reactors

DEFF Research Database (Denmark)

Fedorova, Marina; Sin, Gürkan; Gani, Rafiqul

2013-01-01

and users to generate and test models systematically, efficiently and reliably. In this way, development of products and processes can be faster, cheaper and very efficient. In this contribution, as part of the framework a generic modeling template for the systematic derivation of problem specific catalytic...... membrane fixed bed models is developed. The application of the modeling template is highlighted with a case study related to the modeling of a catalytic membrane reactor coupling dehydrogenation of ethylbenzene with hydrogenation of nitrobenzene....

An investigation of the physical and chemical changes occuring in a Fischer-Tropsch fixed bed catalyst during hydrocarbon synthesis

International Nuclear Information System (INIS)

Duvenhage, D.J.

1990-01-01

Deactivation studies: making use of fixed bed reactors, wet chemical analysis, surface area, pore volume determinations and X-ray diffraction spectrometry, scanning electron microscope spectrometry and secondary ion mass spectrometry techniques; were performed on a low temperature iron Fischer-Tropsch catalyst. It was revealed that this catalyst is mainly deactivated by sulphur poisoning, oxidation of the catalytic reactive phases, sintering of the iron crystallites and to a lesser extent deactivation through fouling of the catalytic surface by carbonaceous deposits. It was found that the top entry section of the catalyst bed deactivated relatively fast, the bottom exit section also deactivated, but not as fast as the top section. The central portion of the catalyst bed was least affected. Sulphur contaminants in the feed gas, even though present in only minute quantities, results in a loss of catalyst performance of the top section of the catalyst bed, while water, produced as a product from the Fischer-Tropsch reaction, oxidized and sintered the catalyst over the bottom section of the catalyst bed. 88 figs., 7 tabs., 224 refs

Decoloration of textile wastewater by means of a fluidized-bed loop reactor and immobilized anaerobic bacteria

International Nuclear Information System (INIS)

Georgiou, D.; Aivasidis, A.

2006-01-01

Textile wastewater was treated by means of a fluidized-bed loop reactor and immobilized anaerobic bacteria. The main target of this treatment was decoloration of the wastewater and transformation of the non-biodegradable azo-reactive dyes to the degradable, under aerobic biological conditions, aromatic amines. Special porous beads (Siran'' (registered)) were utilized as the microbial carriers. Acetic acid solution, enriched with nutrients and trace elements, served both as a pH-regulator and as an external substrate for the growth of methanogenic bacteria. The above technique was firstly applied on synthetic wastewater (an aqueous solution of a mixture of different azo-reactive dyes). Hydraulic residence time was gradually decreased from 24 to 6 h over a period of 3 months. Full decoloration of the wastewater could be achieved even at such a low hydraulic residence time (6 h), while methane-rich biogas was also produced. The same technique was then applied on real textile wastewater with excellent results (full decoloration at a hydraulic residence time of 6 h). Furthermore, the effluent proved to be highly biodegradable by aerobic microbes (activated-sludge). Thus, the above-described anaerobic/aerobic biological technique seems to be a very attractive method for treating textile wastewater since it is cost-effective and environment-friendly

A model for complex flows of soft glassy materials with application to flows through fixed fiber beds

Energy Technology Data Exchange (ETDEWEB)

Sarkar, Arijit; Koch, Donald L., E-mail: dlk15@cornell.edu [School of Chemical and Biomolecular Engineering, Cornell University, 120 Olin Hall, Ithaca, New York 14853-5201 (United States)

2015-11-15

The soft glassy rheology (SGR) model has successfully described the time dependent simple shear rheology of a broad class of complex fluids including foams, concentrated emulsions, colloidal glasses, and solvent-free nanoparticle-organic hybrid materials (NOHMs). The model considers a distribution of mesoscopic fluid elements that hop from trap to trap at a rate which is enhanced by the work done to strain the fluid element. While an SGR fluid has a broad exponential distribution of trap energies, the rheology of NOHMs is better described by a narrower energy distribution and we consider both types of trap energy distributions in this study. We introduce a tensorial version of these models with a hopping rate that depends on the orientation of the element relative to the mean stress field, allowing a range of relative strengths of the extensional and simple shear responses of the fluid. As an application of these models we consider the flow of a soft glassy material through a dilute fixed bed of fibers. The dilute fixed bed exhibits a range of local linear flows which alternate in a chaotic manner with time in a Lagrangian reference frame. It is amenable to an analytical treatment and has been used to characterize the strong flow response of many complex fluids including fiber suspensions, dilute polymer solutions and emulsions. We show that the accumulated strain in the fluid elements has an abrupt nonlinear growth at a Deborah number of order one in a manner similar to that observed for polymer solutions. The exponential dependence of the hopping rate on strain leads to a fluid element deformation that grows logarithmically with Deborah number at high Deborah numbers. SGR fluids having a broad range of trap energies flowing through fixed beds can exhibit a range of rheological behaviors at small Deborah numbers ranging from a yield stress, to a power law response and finally to Newtonian behavior.

A model for complex flows of soft glassy materials with application to flows through fixed fiber beds

KAUST Repository

Sarkar, Arijit

2015-11-01

© 2015 The Society of Rheology. The soft glassy rheology (SGR) model has successfully described the time dependent simple shear rheology of a broad class of complex fluids including foams, concentrated emulsions, colloidal glasses, and solvent-free nanoparticle-organic hybrid materials (NOHMs). The model considers a distribution of mesoscopic fluid elements that hop from trap to trap at a rate which is enhanced by the work done to strain the fluid element. While an SGR fluid has a broad exponential distribution of trap energies, the rheology of NOHMs is better described by a narrower energy distribution and we consider both types of trap energy distributions in this study. We introduce a tensorial version of these models with a hopping rate that depends on the orientation of the element relative to the mean stress field, allowing a range of relative strengths of the extensional and simple shear responses of the fluid. As an application of these models we consider the flow of a soft glassy material through a dilute fixed bed of fibers. The dilute fixed bed exhibits a range of local linear flows which alternate in a chaotic manner with time in a Lagrangian reference frame. It is amenable to an analytical treatment and has been used to characterize the strong flow response of many complex fluids including fiber suspensions, dilute polymer solutions and emulsions. We show that the accumulated strain in the fluid elements has an abrupt nonlinear growth at a Deborah number of order one in a manner similar to that observed for polymer solutions. The exponential dependence of the hopping rate on strain leads to a fluid element deformation that grows logarithmically with Deborah number at high Deborah numbers. SGR fluids having a broad range of trap energies flowing through fixed beds can exhibit a range of rheological behaviors at small Deborah numbers ranging from a yield stress, to a power law response and finally to Newtonian behavior.

A model for complex flows of soft glassy materials with application to flows through fixed fiber beds

KAUST Repository

Sarkar, Arijit; Koch, Donald L.

2015-01-01

© 2015 The Society of Rheology. The soft glassy rheology (SGR) model has successfully described the time dependent simple shear rheology of a broad class of complex fluids including foams, concentrated emulsions, colloidal glasses, and solvent-free nanoparticle-organic hybrid materials (NOHMs). The model considers a distribution of mesoscopic fluid elements that hop from trap to trap at a rate which is enhanced by the work done to strain the fluid element. While an SGR fluid has a broad exponential distribution of trap energies, the rheology of NOHMs is better described by a narrower energy distribution and we consider both types of trap energy distributions in this study. We introduce a tensorial version of these models with a hopping rate that depends on the orientation of the element relative to the mean stress field, allowing a range of relative strengths of the extensional and simple shear responses of the fluid. As an application of these models we consider the flow of a soft glassy material through a dilute fixed bed of fibers. The dilute fixed bed exhibits a range of local linear flows which alternate in a chaotic manner with time in a Lagrangian reference frame. It is amenable to an analytical treatment and has been used to characterize the strong flow response of many complex fluids including fiber suspensions, dilute polymer solutions and emulsions. We show that the accumulated strain in the fluid elements has an abrupt nonlinear growth at a Deborah number of order one in a manner similar to that observed for polymer solutions. The exponential dependence of the hopping rate on strain leads to a fluid element deformation that grows logarithmically with Deborah number at high Deborah numbers. SGR fluids having a broad range of trap energies flowing through fixed beds can exhibit a range of rheological behaviors at small Deborah numbers ranging from a yield stress, to a power law response and finally to Newtonian behavior.

Fixed-film processes. Part 1

International Nuclear Information System (INIS)

Canziani, R.

1999-01-01

Recently, full scale fixed-film or mixed suspended and fixed biomass bioreactors have been applied in many wastewater treatments plants. These process no longer depend on biomass settle ability and can be used to improve the performance of existing plants as required by more stringent discharge permit limits, especially for nutrients and suspended solid. Also, processes may work at high rates making it possible to build small footprint installations. Fixed-film process include trickling filter, moving bed reactors fluidized bed reactors. In the first part, the theoretical base governing fixed-film processes are briefly outlined with some simple examples of calculations underlining the main differences with conventional activated sludge processes [it

Performance of novel sludge-bed anaerobic membrane bioreactor (SB-AnMBR) treating prehydrolysis liquor.

Science.gov (United States)

Kale, Mayur M; Singh, Kripa S

2014-01-01

The feasibility of a novel sludge-bed anaerobic membrane bioreactor (SB-AnMBR) configuration for treating a waste stream from a dissolving pulp production industry was evaluated. The waste stream, called prehydrolysis liquor (PHL), is generated after the wood chips are subjected to high temperature steam to remove unwanted hemicelluloses. The PHL with total chemical oxygen demand (COD) of approximately 100 g/L contained mainly sugars, furfural, lignin, and acetic acid. The SB-AnMBR was fed with the PHL at organic loading rates in a range of 0.8 to10 kg-COD/(m(3)·d). The COD removal efficiency of more than 85% and an average rate of methane production of 0.35 m(3)/(kg-COD·d) were observed at each loading rate. No detectable sugars or furfural were present in the treated effluent from SB-AnMBR. Lignin removal varied from 60 to 90%. Flat-sheet membranes performed well with one fouling event during first 400 days of operation.

Long Term Performance of an Arsenite-Oxidizing-Chlorate-Reducing Microbial Consortium in an Upflow Anaerobic Sludge Bed (UASB) Bioreactor

Science.gov (United States)

Sun, Wenjie; Sierra-Alvarez, Reyes; Field, Jim A.

2011-01-01

A chlorate (ClO3−) reducing microbial consortium oxidized arsenite (As(III)) to arsenate (As(V)) in an upflow anaerobic sludge-bed bioreactor over 550 d operation. As(III) was converted with high conversion efficiencies (>98%) at volumetric loadings ranging from 0.45 to 1.92 mmol As/(Lreactor d). The oxidation of As(III) was linked to the complete reduction of ClO3− to Cl− and H2O, as demonstrated by a molar ratio of approximately 3.0 mol As(III) oxidized per mole of Cl− formed and by the greatly lowered ClO3−-reducing capacity without As(III) feeding. An autotrophic enrichment culture was established from the bioreactor biofilm. A 16S rRNA gene clone library indicated that the culture was dominated by Dechloromonas, and Stenotrophomonas as well as genera within the family Comamonadaceae. The results indicate that the oxidation of As(III) to less mobile As(V) utilizing ClO3− as a terminal electron acceptor provides a sustainable bioremediation strategy for arsenic contamination in anaerobic environments. PMID:21333531

Models comparative study for heat storage in fixed beds; Estudo comparativo de modelos para armazenamento de calor em leitos fixos

Energy Technology Data Exchange (ETDEWEB)

Stuginski, Junior, Rubens

1991-07-01

This work presents comparative results of a numerical investigation of four possible models for the prediction of thermal performance of fixed bed storage units and their thermal design. These models includes Schumann's model, the radial dispersion model, a model that include both axial heat conduction in the fluid phase and admits thermal gradient in the solids particles and finally a two dimensional single phase model. For each of these models a computer code was written and tested to evaluate the computing time of same data and analyze any other computational problems. The tests of thermal performance included particle size, porosity, particle material, flow rate, inlet temperature and heat losses form tank walls and extremities. Dynamics behaviour of the storage units due to transient variation in either flow rate or inlet temperature was also investigated. The results presented include temperature gradients, pressure drop and heat storage. The results obtained are very useful for analysis and design of fixed bed storage units. (author)

Removal of furan and phenolic compounds from simulated biomass hydrolysates by batch adsorption and continuous fixed-bed column adsorption methods.

Science.gov (United States)

Lee, Sang Cheol; Park, Sunkyu

2016-09-01

It has been proposed to remove all potential inhibitors and sulfuric acid in biomass hydrolysates generated from dilute-acid pretreatment of biomass, based on three steps of sugar purification process. This study focused on its first step in which furan and phenolic compounds were selectively removed from the simulated hydrolysates using activated charcoal. Batch adsorption experiments demonstrated that the affinity of activated charcoal for each component was highest in the order of vanillic acid, 4-hydroxybenzoic acid, furfural, acetic acid, sulfuric acid, and xylose. The affinity of activated charcoal for furan and phenolic compounds proved to be significantly higher than that of the other three components. Four separation strategies were conducted with a combination of batch adsorption and continuous fixed-bed column adsorption methods. It was observed that xylose loss was negligible with near complete removal of furan and phenolic compounds, when at least one fixed-bed column adsorption was implemented in the strategy. Copyright © 2016 Elsevier Ltd. All rights reserved.

Treatment of thin stillage in a high-rate anaerobic fluidized bed bioreactor (AFBR).

Science.gov (United States)

Andalib, Mehran; Hafez, Hisham; Elbeshbishy, Elsayed; Nakhla, George; Zhu, Jesse

2012-10-01

The primary objective of this work was to investigate the treatability of thin stillage as a by-product of bioethanol production plants using an anaerobic fluidized bed bioreactor (AFBR) employing zeolite with average diameter of (d(m)) of 425-610 μm and specific surface area (SSA) of 26.5m(2)/g as the carrier media. Despite the very high strength of thin stillage with chemical oxygen demand of 130,000 mg TCOD/L and suspended solids of 47,000 mg TSS/L, the AFBR showed up to 88% TCOD and 78% TSS removal at very high organic and solids loading rates (OLR and SLR) of 29 kg COD/m(3)d and 10.5 kg TSS/m(3)d respectively and hydraulic retention time (HRT) of 3.5 days. Methane production rates of up to 160 L/d at the steady state equivalent to 40 L(CH4)/L(thin stillage)d and biogas production rate per reactor volume of 15.8L(gas)/L(reactor)d were achieved. Copyright © 2012 Elsevier Ltd. All rights reserved.

Pre-combustion capture of carbon dioxide in a fixed bed reactor using the clathrate hydrate process

International Nuclear Information System (INIS)

Babu, Ponnivalavan; Kumar, Rajnish; Linga, Praveen

2013-01-01

Hydrate based gas separation (HBGS) process with silica sand and silica gel as contact medium was employed to capture CO 2 from fuel gas mixture. Gas uptake measurement at three different pressures (7.5, 8.5 and 9.0 MPa) and 274.15 K were conducted for hydrate formation kinetics and overall conversion of water to hydrate, rate of hydrate formation were determined. Water conversion of up to 36% was achieved with silica sand bed compared to 13% conversion in the silica gel bed. Effect of driving force on the rate of hydrate formation and gas consumption was significant in silica sand bed whereas it was found to be insignificant in silica gel bed. Hydrate dissociation experiments by thermal stimulation (at constant pressure) alone and a combination of depressurization and thermal stimulation were carried out for complete recovery of the hydrated gas. A driving force of 23 K was found to be sufficient to recover all the hydrated gas within 1 h. This study indicates that silica sand can be an effective porous media for separation of CO 2 from fuel gas when compared to silica gel. - Highlights: ► The clathrate process for pre-combustion capture of carbon dioxide in a novel fixed bed reactor is presented. ► Performance of two contact media (silica gel and silica sand) was investigated. ► Water to hydrate conversion was higher in a silica sand column. ► A pressure reduction and thermal stimulation approach is presented for a complete recovery of the hydrated gas

Continuous synthesis of methanol: heterogeneous hydrogenation of ethylene carbonate over Cu/HMS catalysts in a fixed bed reactor system.

Science.gov (United States)

Chen, Xi; Cui, Yuanyuan; Wen, Chao; Wang, Bin; Dai, Wei-Lin

2015-09-18

Continuous fixed-bed catalytic hydrogenation of ethylene carbonate (EC) to methanol and ethylene glycol (EG), an emerging synthetic process of methanol via indirect conversion of CO2, was successfully performed over Cu/HMS catalysts prepared by the ammonia evaporation (AE) method. The catalysts possessed superb performance with a conversion of 100% and a selectivity to methanol of 74%.

Carbonaceous materials in petrochemical wastewater before and after treatment in an aerated submerged fixed-bed biofilm reactor

OpenAIRE

Trojanowicz Karol; Wojcik Wlodzimierz

2016-01-01

Results of the studies for determining fractions of organic contaminants in a pretreated petrochemical wastewater flowing into a pilot Aerated Submerged Fixed-Bed Biofilm Reactor (ASFBBR) are presented and discussed. The method of chemical oxygen demand (COD) fractionation consisted of physical tests and biological assays. It was found that the main part of the total COD in the petrochemical, pretreated wastewater was soluble organic substance with average value of 57.6%. The fractions of par...

Wastewater treatment with submerged fixed bed biofilm reactor systems--design rules, operating experiences and ongoing developments.

Science.gov (United States)

Schlegel, S; Koeser, H

2007-01-01

Wastewater treatment systems using bio-films that grow attached to a support media are an alternative to the widely used suspended growth activated sludge process. Different fixed growth biofilm reactors are commercially used for the treatment of municipal as well as industrial wastewater. In this paper a fairly new fixed growth biofilm system, the submerged fixed bed biofilm reactor (SFBBR), is discussed. SFBBRs are based on aerated submerged fixed open structured plastic media for the support of the biofilm. They are generally operated without sludge recirculation in order to avoid clogging of the support media and problems with the control of the biofilm. Reactor and process design considerations for these reactors are reviewed. Measures to ensure the development and maintenance of an active biofilm are examined. SFBBRs have been applied successfully to small wastewater treatment plants where complete nitrification but no high degree of denitrification is necessary. For the pre-treatment of industrial wastewater the use of SFBBRs is advantageous, especially in cases of wastewater with high organic loading or high content of compounds with low biodegradability. Performance data from exemplary commercial plants are given. Ongoing research and development efforts aim at achieving a high simultaneous total nitrogen (TN) removal of aerated SFBBRs and at improving the efficiency of TN removal in anoxic SFBBRs.

Anaerobic treatment of olive mill wastewater and piggery effluents fermented with Candida tropicalis

International Nuclear Information System (INIS)

Martinez-Garcia, Gregorio; Johnson, Anbu Clemensis; Bachmann, Robert T.; Williams, Ceri J.; Burgoyne, Andrea; Edyvean, Robert G.J.

2009-01-01

Olive mill wastewater (OMW) contains high concentrations of phenolic compounds that are inhibitory to many microorganisms making it difficult to treat biologically prior to discharge in waterways. The total mono-cyclic phenol reduction in OMW in this study was carried out by aerobic pre-treatment using the yeast Candida tropicalis in a 18 L batch reactor at 30 deg. C for 12 days followed by anaerobic co-digestion. A COD removal of 62% and a reduction in the total mono-cyclic phenol content by 51% of the mixture was achieved in the aerobic pre-treatment. Pig slurry was added as co-substrate to supplement the low nitrogen levels in the olive mill wastewater. Subsequent anaerobic treatment was carried out in a 20 L fixed-bed reactor at 37 deg. C and HRT between 11 and 45 days. After a long start-up period, the OLR was increased from 1.25 to 5 kg COD m -3 day -1 during the last 30 days, resulting in subsequent increase in overall COD removal and biogas production, up to maximum values of 85% and 29 L biogas L reactor -1 day -1 , respectively. Methane content of the biogas produced from the anaerobic digestion ranged between 65% and 74%.

Anaerobic treatment of olive mill wastewater and piggery effluents fermented with Candida tropicalis

Energy Technology Data Exchange (ETDEWEB)

Martinez-Garcia, Gregorio [Department of Chemical and Process Engineering, University of Sheffield, S1 3JD Sheffield (United Kingdom); Johnson, Anbu Clemensis, E-mail: acj265@yahoo.com [Department of Chemical and Process Engineering, University of Sheffield, S1 3JD Sheffield (United Kingdom)] [School of Environmental Engineering, Universiti Malaysia Perlis, 02600 Jejawi, Perlis (Malaysia); Bachmann, Robert T. [Department of Chemical and Process Engineering, University of Sheffield, S1 3JD Sheffield (United Kingdom)] [Malaysian Institute of Chemical and Bioengineering Technology, Universiti Kuala Lumpur, 1988 Vendor City, 7800 Taboh Naning, Alor Gajah, Melaka (Malaysia); Williams, Ceri J. [Yorkshire-Forward, Victoria House, Victoria Place, LS11 5AE Leeds (United Kingdom); Burgoyne, Andrea; Edyvean, Robert G.J. [Department of Chemical and Process Engineering, University of Sheffield, S1 3JD Sheffield (United Kingdom)

2009-05-30

Olive mill wastewater (OMW) contains high concentrations of phenolic compounds that are inhibitory to many microorganisms making it difficult to treat biologically prior to discharge in waterways. The total mono-cyclic phenol reduction in OMW in this study was carried out by aerobic pre-treatment using the yeast Candida tropicalis in a 18 L batch reactor at 30 deg. C for 12 days followed by anaerobic co-digestion. A COD removal of 62% and a reduction in the total mono-cyclic phenol content by 51% of the mixture was achieved in the aerobic pre-treatment. Pig slurry was added as co-substrate to supplement the low nitrogen levels in the olive mill wastewater. Subsequent anaerobic treatment was carried out in a 20 L fixed-bed reactor at 37 deg. C and HRT between 11 and 45 days. After a long start-up period, the OLR was increased from 1.25 to 5 kg COD m{sup -3} day{sup -1} during the last 30 days, resulting in subsequent increase in overall COD removal and biogas production, up to maximum values of 85% and 29 L{sub biogas}L{sub reactor}{sup -1}day{sup -1}, respectively. Methane content of the biogas produced from the anaerobic digestion ranged between 65% and 74%.

Effect of process parameters on removal and recovery of Cd(II) and Cu(II) from electroplating wastewater by fixed-bed column of nano-dimensional titanium (IV) oxide agglomerates

CSIR Research Space (South Africa)

Debnath, S

2014-01-01

Full Text Available Removal performances of Cd(II) and Cu(II) from water was investigated using agglomerated nanoparticle of hydrous titanium(IV) oxide (NTO) packed fixed bed. The parameters varied were the bed depth, flow rate and feed solution concentrations...

Effect of bacterial lipase on anaerobic co-digestion of slaughterhouse wastewater and grease in batch condition and continuous fixed-bed reactor

OpenAIRE

Affes, Maha; Aloui, Fathi; Hadrich, Fatma; Loukil, Slim; Sayadi, Sami

2017-01-01

Background This study aimed to investigate the effects of bacterial lipase on biogas production of anaerobic co-digestion of slaughterhouse wastewater (SHWW) and hydrolyzed grease (HG). A neutrophilic Staphylococcus xylosus strain exhibiting lipolytic activity was used to perform microbial hydrolysis pretreatment of poultry slaughterhouse lipid rich waste. Results Optimum proportion of hydrolyzed grease was evaluated by determining biochemical methane potential. A high biogas production was o...

Sintering study in vertical fixed bed reactor for synthetic aggregate production

International Nuclear Information System (INIS)

Quaresma, D.S.; Neves, A.S.S.; Melo, A.O.; Pereira, L.F.S.; Bezerra, P.T.S.; Macedo, E.N.; Souza, J.A.S.

2017-01-01

The synthetic aggregates are being employed in civil construction for the reduction of mineral extraction activities. Within this context, the recycling of industrial waste is the basis of the majority of processes to reduce the exploitation of mineral resources. In this work the sintering in a vertical fixed bed reactor for synthetic aggregate production using 20% pellets and 80% charcoal was studied. The pellets were prepared from a mixture containing clay, charcoal and fly ash. Two experiments varying the speed of air sucking were carried out. The material produced was analyzed by X-ray diffraction, scanning electron microscopy, measures of their ceramic properties, and particle size analysis. The results showed that the solid-state reactions, during the sintering process, were efficient and the produced material was classified as coarse lightweight aggregate. The process is interesting for the sintering of aggregates, and can be controlled by composition, particle size, temperature gradient and gaseous flow. (author)

Molecular analysis of the biomass of a fluidized bed reactor treating synthetic vinasse at anaerobic and micro-aerobic conditions.

Science.gov (United States)

Rodríguez, Elisa; Lopes, Alexandre; Fdz-Polanco, María; Stams, Alfons J M; García-Encina, Pedro A

2012-03-01

The microbial communities (Bacteria and Archaea) established in an anaerobic fluidized bed reactor used to treat synthetic vinasse (betaine, glucose, acetate, propionate, and butyrate) were characterized by denaturing gradient gel electrophoresis (DGGE) and phylogenetic analysis. This study was focused on the competitive and syntrophic interactions between the different microbial groups at varying influent substrate to sulfate ratios of 8, 4, and 2 and anaerobic or micro-aerobic conditions. Acetogens detected along the anaerobic phases at substrate to sulfate ratios of 8 and 4 seemed to be mainly involved in the fermentation of glucose and betaine, but they were substituted by other sugar or betaine degraders after oxygen application. Typical fatty acid degraders that grow in syntrophy with methanogens were not detected during the entire reactor run. Likely, sugar and betaine degraders outnumbered them in the DGGE analysis. The detected sulfate-reducing bacteria (SRB) belonged to the hydrogen-utilizing Desulfovibrio. The introduction of oxygen led to the formation of elemental sulfur (S(0)) and probably other sulfur compounds by sulfide-oxidizing bacteria (γ-Proteobacteria). It is likely that the sulfur intermediates produced from sulfide oxidation were used by SRB and other microorganisms as electron acceptors, as was supported by the detection of the sulfur respiring Wolinella succinogenes. Within the Archaea population, members of Methanomethylovorans and Methanosaeta were detected throughout the entire reactor operation. Hydrogenotrophic methanogens mainly belonging to the genus Methanobacterium were detected at the highest substrate to sulfate ratio but rapidly disappeared by increasing the sulfate concentration.

Hydropyrolysis of extracted Euphorbia rigida in a well-swept fixed-bed tubular reactor

Energy Technology Data Exchange (ETDEWEB)

Gercel, H.F.; Putun, A.E.; Putun, E.

2002-05-01

Tubular reactor fixed-bed hydropyrolysis experiments have been conducted on a sample of extracted Euphorbia rigida to determine the possibility of being a potential source of renewable fuels and chemical feedstock. The effects of hydropyrolysis temperature and heating rate on the hydropyrolysis yields and chemical compositions have been investigated. The maximum bio-oil yield of 39.8 wt% was obtained in H{sub 2} atmosphere at a hydrogen pressure of 150 bar, a hydrogen flow rate of 5 dm{sup 3} min{sup -} {sup 1}, a hydropyrolysis temperature of 550{sup o}C, and a heating rate of 100{sup o}C min{sup -1}. Then this bio-oil was characterized by elemental analysis and {sup 1}H nuclear magnetic resonance (NMR) techniques. (author)

Fluid flow with heat transfer in a fix-bed

International Nuclear Information System (INIS)

Gasparetto, C.A.

1982-01-01

Tests with two different fluids, water and air, flowing in a bed with irregular particles of silica were done. The bed was confined inside a tube, which was heated by an external jacket. The bed is characterized by permeability and porosity. The tests showed a wall effect face to the relation between the tube diameter and the medium dimension of the particles. The results are presented as a relation between Nusselt number / Peclet number. (E.G.) [pt

Thin-film fixed-bed reactor (TFFBR for solar photocatalytic inactivation of aquaculture pathogen Aeromonas hydrophila

Directory of Open Access Journals (Sweden)

Khan Sadia J

2012-01-01

Full Text Available Abstract Background Outbreaks of infectious diseases by microbial pathogens can cause substantial losses of stock in aquaculture systems. There are several ways to eliminate these pathogens including the use of antibiotics, biocides and conventional disinfectants, but these leave undesirable chemical residues. Conversely, using sunlight for disinfection has the advantage of leaving no chemical residue and is particularly suited to countries with sunny climates. Titanium dioxide (TiO2 is a photocatalyst that increases the effectiveness of solar disinfection. In recent years, several different types of solar photocatalytic reactors coated with TiO2 have been developed for waste water and drinking water treatment. In this study a thin-film fixed-bed reactor (TFFBR, designed as a sloping flat plate reactor coated with P25 DEGUSSA TiO2, was used. Results The level of inactivation of the aquaculture pathogen Aeromonas hydrophila ATCC 35654 was determined after travelling across the TFFBR under various natural sunlight conditions (300-1200 W m-2, at 3 different flow rates (4.8, 8.4 and 16.8 L h-1. Bacterial numbers were determined by conventional plate counting using selective agar media, cultured (i under conventional aerobic conditions to detect healthy cells and (ii under conditions designed to neutralise reactive oxygen species (agar medium supplemented with the peroxide scavenger sodium pyruvate at 0.05% w/v, incubated under anaerobic conditions, to detect both healthy and sub-lethally injured (oxygen-sensitive cells. The results clearly demonstrate that high sunlight intensities (≥ 600 W m-2 and low flow rates (4.8 L h-1 provided optimum conditions for inactivation of A. hydrophila ATCC 3564, with greater overall inactivation and fewer sub-lethally injured cells than at low sunlight intensities or high flow rates. Low sunlight intensities resulted in reduced overall inactivation and greater sub-lethal injury at all flow rates. Conclusions This

Anaerobic depuration of waste waters; Depuracion anaerobia de aguas residuales

Energy Technology Data Exchange (ETDEWEB)

Mejias Sanchez, G.; Vazquez Berger, E.; Magana Pietra, A.H. [Facultad de Ingenieria, Universidad Autonoma de yucatan, Merida (Mexico)

1996-08-01

Trials were carried out at a 500 l semi-experimental plant using there reactor models-anaerobic filter, fixed film and UASB type-for the anaerobic treatment of waste from different sources. The results after 24 and 48 hours were compared. The greatest efficiency was obtained after 48 hours the aerobic filter reactor (66% displacement), followed by the fixed film reactor (50%) and the UASB model (41%). (Author) 16 refs.

Continuous removal and recovery of tellurium in an upflow anaerobic granular sludge bed reactor

International Nuclear Information System (INIS)

Mal, Joyabrata; Nancharaiah, Yarlagadda V.; Maheshwari, Neeraj; Hullebusch, Eric D. van; Lens, Piet N.L.

2017-01-01

Highlights: • Tellurite bioreduction coupled to recovery of biogenic Te(0) nanocrystals. • First report on continuous tellurite removal in a UASB reactor. • Biogenic Te(0) was mainly associated with loosely-bound EPS of granular sludge. • Repeated exposure to tellurite caused compositional changes in the EPS matrix. - Abstract: Continuous removal of tellurite (TeO 3 2− ) from synthetic wastewater and subsequent recovery in the form of elemental tellurium was studied in an upflow anaerobic granular sludge bed (UASB) reactor operated at 30 °C. The UASB reactor was inoculated with anaerobic granular sludge and fed with lactate as carbon source and electron donor at an organic loading rate of 0.6 g COD L −1 d −1 . After establishing efficient and stable COD removal, the reactor was fed with 10 mg TeO 3 2− L −1 for 42 d before increasing the influent concentration to 20 mg TeO 3 2− L −1 . Tellurite removal (98 and 92%, respectively, from 10 and 20 mg Te L −1 ) was primarily mediated through bioreduction and most of the removed Te was retained in the bioreactor. Characterization using XRD, Raman spectroscopy, SEM-EDX and TEM confirmed association of tellurium with the granular sludge, typically in the form of elemental Te(0) deposits. Furthermore, application of an extracellular polymeric substances (EPS) extraction method to the tellurite reducing sludge recovered up to 78% of the tellurium retained in the granular sludge. This study demonstrates for the first time the application of a UASB reactor for continuous tellurite removal from tellurite-containing wastewater coupled to elemental Te(0) recovery.

Heat Transfer in a Fixed Bed of Straw Char

DEFF Research Database (Denmark)

Fjellerup, Jan Søren; Henriksen, Ulrik Birk; Jensen, Anker

2003-01-01

A model for the thermal conductivity of a straw char bed has been developed. The model extends the work of Yagi and Kunii to describe heat transfer in a bed of cylinders, using a relationship between the interparticle distance and the external porosity. To verify the model, thermal conductivity...... the experimental uncertainty over the range of conditions investigated. The heat transfer model was used in a parametric study to evaluate the effect of gas flow rate, particle diameter, porosity, and temperature on the thermal conductivity in a straw char bed....... experiments were performed on shredded and un-shredded straw char samples, varying particle size, bed packing (loose or dense), and temperature. Predictions with the model, using the measured external porosity and particle diameter as input parameters, are in agreement with measurements within...

Characterization and anaerobic treatment of the sanitary landfill leachate in Istanbul.

Science.gov (United States)

Inanc, B; Calli, B; Saatci, A

2000-01-01

In this study, characterization and anaerobic treatability of leachate from Komurcuoda Sanitary Landfill located on the Asian part of Istanbul were investigated. Time based fluctuations in characteristics of leachate were monitored for an 8 month period. Samples were taken from a 200 m3 holding tank located at the lowest elevation of the landfill. COD concentrations have ranged between 18,800 and 47,800 mg/l while BOD5 between 6820 and 38,500 mg/L. COD and BOD5 values were higher in summer and lower in winter due to dilution by precipitation. On the other hand, it was quite interesting that such a dilution effect was not observed for ammonia. The highest ammonia concentration, 2690 mg/L was in November 1998. BOD5/COD ratio was larger than 0.7 for most samples indicating high biodegradability, and acidic phase of decomposition in the landfill. For anaerobic treatability, three different reactors, namely an upflow anaerobic sludge bed reactor, an anaerobic upflow filter and a hybrid bed reactor, were used. The anaerobic reactors were operated for more than 230 days and were continuing operation when this paper was prepared. Organic loading was increased gradually from 1.3 kg COD/m3.day to 8.2 kg COD/m3.day while hydraulic retention time was reduced from 2.4 days to 2.0 days. All the reactors showed similar performances against organic loadings with efficiencies between 80% and 90%. However the reactors have experienced high ammonia concentrations several times throughout the experimental period, and showed different inhibition levels. Anaerobic filter was the least affected reactor while UASB was the most. Hybrid bed reactor has exhibited a similar performance to anaerobic filter although not to the same degree.

The anaerobic co-digestion of sheep bedding and ⩾ 50% cattle manure increases biogas production and improves biofertilizer quality.

Science.gov (United States)

Cestonaro, Taiana; Costa, Mônica Sarolli Silva de Mendonça; Costa, Luiz Antônio de Mendonça; Rozatti, Marcos Antonio Teofilo; Pereira, Dercio Ceri; Lorin, Higor Eisten Francisconi; Carneiro, Leocir José

2015-12-01

Sheep manure pellets are peculiarly shaped as small 'capsules' of limited permeability and thus are difficult to degrade. Fragmentation of manure pellets into a homogeneous mass is important for decomposition by microorganisms, and occurs naturally by physical shearing due to animal trampling, when sheep bedding is used. However, the high lignocellulose content of sheep bedding may limit decomposition of sheep manure. Here, we evaluated if co-digestion of sheep bedding with cattle manure would improve the yield and quality of the useful products of anaerobic digestion of sheep bedding--biogas and biofertilizer--by providing a source of nutrients and readily available carbon. Mixtures of sheep bedding and cattle manure in varying proportions (0%, 25%, 50%, 75%, or 100% cattle manure) were added to 6-L digesters, used in a batch system, and analyzed by uni and multivariate statistical tools. PC1, which explained 64.96% of data variability, can be referred to as 'organic fraction/productivity', because higher rates of organic fraction consumption (COD, cellulose and hemicellulose contents) led to higher digester productivity (biogas production, nutrient concentration, and sample stability changes). Therefore, productivity and organic fraction variables were most influenced by manure mixtures with higher (⩾ 50%) or lower (⩽ 25%) ratios of cattle manure, respectively. Increasing the amount of cattle manure up to 50% enhanced the biogas potential production from 142 L kg(-1)TS (0% of cattle manure) to 165, 171, 160 L biogas kg(-1)TS for the mixtures containing 100%, 75% and 50% of cattle manure, respectively. Our results show that the addition of ⩾ 50% cattle manure to the mixture increases biogas production and improves the quality of the final biofertilizer. Copyright © 2015 Elsevier Ltd. All rights reserved.

Treatment of chemical-pharmaceutical wastewater in packed bed anaerobic reactors

Energy Technology Data Exchange (ETDEWEB)

Nacheva, P.M.; Pena-Loera, B.; Moralez-Guzman, F. [Mexican Institute for Water Technology, Jiutepec (Mexico)

2006-07-01

Biological degradation in packed bed anaerobic mesophilic reactors with five different support materials was studied for the treatment of chemical-pharmaceutical wastewater with high COD (23-31 g/L), which contains toxic organic compounds. Experimental up-flow bio-filters were operated at different organic loads for a two-year period. Removals of 80-98% were obtained in the reactors with sand, anthracite and black tezontle, but at relatively low organic loads, less than 3.6 kg m{sup -3} d{sup -1}. The reactor with granular activated carbon (GAC) had a better performance; efficiencies higher than 95% were obtained at loads up to 17kg m{sup -3} d{sup -1} and higher than 80% with loads up to 26 kg m{sup -3} d{sup -1}. Second in performance was the reactor with red tezontle which allows COD removals higher than 80% with loads up to 6 kg m{sup -3} d{sup -1}. The use of GAC as support material allows greater biodegradation rates than the rest of the materials and it makes the process more resistant to organic load increases, inhibition effects and toxicity. Methanogenic activity was inhibited at loads higher than 21.9 kg m{sup -3} d{sup -1} in the GAC-reactor and at loads higher than 3.6 kg m{sup -3} d{sup -1} in the rest of the reactors. At loads lower than the previously mentioned, high methane production yield was obtained, 0.32-0.35 m{sup 33}CH4/kg CODremoved.

Modelling the transition between fixed and mobile bed conditions in two-phase free-surface flows: The Composite Riemann Problem and its numerical solution

Science.gov (United States)

Rosatti, Giorgio; Zugliani, Daniel

2015-03-01

In a two-phase free-surface flow, the transition from a mobile-bed condition to a fixed-bed one (and vice versa) occurs at a sharp interface across which the relevant system of partial differential equations changes abruptly. This leads to the possibility of conceiving a new type of Riemann Problem (RP), which we have called Composite Riemann Problem (CRP), where not only the initial constant values of the variables but also the system of equations change from left to right of a discontinuity. In this paper, we present a strategy for solving a CRP by reducing it to a standard RP of a single, composite system of equations. This can be obtained by combining the two original systems by means of a suitable weighting function, namely the erodibility variable, and the introduction of an appropriate differential equation for this quantity. In this way, the CRP problem can be analyzed theoretically with standard methods, and the features of the solutions can be clearly identified. In particular, a stationary contact wave is able to correctly describe the sharp transition between mobile- and fixed-bed conditions. A finite volume scheme based on the Multiple Averages Generalized Roe approach (Rosatti and Begnudelli (2013) [22]) was used to numerically solve the fixed-mobile CRP. Several test cases demonstrate the effectiveness, exact well balanceness and high accuracy of the scheme when applied to problems that fall within the physical range of applicability of the relevant mathematical model.

Fixed-bed column study for hexavalent chromium removal and recovery by short-chain polyaniline synthesized on jute fiber

Energy Technology Data Exchange (ETDEWEB)

Kumar, Potsangbam Albino [Department of Civil Engineering, Indian Institute of Technology Guwahati, Assam 781039 (India); Chakraborty, Saswati [Department of Civil Engineering, Indian Institute of Technology Guwahati, Assam 781039 (India)], E-mail: saswati@iitg.ernet.in

2009-03-15

Fixed-bed column studies were conducted to evaluate performance of a short-chain polymer, polyaniline, synthesized on the surface of jute fiber (PANI-jute) for the removal of hexavalent chromium [Cr(VI)] in aqueous environment. Influent pH, column bed depth, influent Cr(VI) concentrations and influent flow rate were variable parameters for the present study. Optimum pH for total chromium removal was observed as 3 by electrostatic attraction of acid chromate ion (HCrO{sub 4}{sup -}) with protonated amine group (NH{sub 3}{sup +}) of PANI-jute. With increase in column bed depth from 40 to 60 cm, total chromium uptake by PANI-jute increased from 4.14 to 4.66 mg/g with subsequent increase in throughput volume from 9.84 to 12.6 L at exhaustion point. The data obtained for total chromium removal were well described by BDST equation till 10% breakthrough. Adsorption rate constant and dynamic bed capacity at 10% breakthrough were observed as 0.01 L/mg h and 1069.46 mg/L, respectively. Adsorbed total chromium was recovered back from PANI-jute as non-toxic Cr(III) after ignition with more than 97% reduction in weight, minimizing the problem of solid waste disposal.

Low energy single-staged anaerobic fluidized bed ceramic membrane bioreactor (AFCMBR) for wastewater treatment.

Science.gov (United States)

Aslam, Muhammad; McCarty, Perry L; Shin, Chungheon; Bae, Jaeho; Kim, Jeonghwan

2017-09-01

An aluminum dioxide (Al 2 O 3 ) ceramic membrane was used in a single-stage anaerobic fluidized bed ceramic membrane bioreactor (AFCMBR) for low-strength wastewater treatment. The AFCMBR was operated continuously for 395days at 25°C using a synthetic wastewater having a chemical oxygen demand (COD) averaging 260mg/L. A membrane net flux as high as 14.5-17L/m 2 h was achieved with only periodic maintenance cleaning, obtained by adding 25mg/L of sodium hypochlorite solution. No adverse effect of the maintenance cleaning on organic removal was observed. An average SCOD in the membrane permeate of 23mg/L was achieved with a 1h hydraulic retention time (HRT). Biosolids production averaged 0.014±0.007gVSS/gCOD removed. The estimated electrical energy required to operate the AFCMBR system was 0.039kWh/m 3 , which is only about 17% of the electrical energy that could be generated with the methane produced. Copyright © 2017 Elsevier Ltd. All rights reserved.

Optimal oxygen feeding policy to maximize the production of Maleic anhydride in unsteady state fixed bed catalytic reactors

Directory of Open Access Journals (Sweden)

E. Ali

2017-07-01

Full Text Available The effect of different oxygen feeding scenarios in a fixed bed reactor for the production of Maleic anhydride (MA is studied. Two reactor configurations were examined. In the first configuration, a cross flow reactor (CFR with 4 discrete feeding points is considered. Another configuration is the conventional packed-bed reactor (PBR with a single feed. Nonlinear Model Predictive Controller (NLMPC was used as optimal controller to operate the CFR in dynamic mode and to optimize the multiple feed dosages in order to enhance the MA yield. The simulation results indicated that different combinations of the four feed ratios can operate the reactor at the best value for the yield provided the first feeding point is kept as low as possible. For the packed bed reactor configuration, a single oxygen feed is considered and is optimized transiently by NLMPC. The simulation outcomes showed that the reactor performance in terms of the produced MA mole fraction can also be enhanced to the same magnitude obtained by CFR configuration. This improvement requires decreasing the oxygen ratio in the reactor single feed by 70%.

Anaerobic treatment of complex wastewater and waste activated sludge - Appl. of an upflow anaerobic solid removal (UASR).

NARCIS (Netherlands)

Zeeman, G.; Sanders, W.T.M.; Wang, K.Y.; Lettinga, G.

1997-01-01

The application of one phase anaerobic wastewater systems for the treatment of complex wastewaters containing high amounts of suspended solids or lipids is usually limited by accumulation of these compounds in the sludge bed. This accumulation reduces the solid retention time and methanogenic

Fixed-film processes. Part 2

International Nuclear Information System (INIS)

Canziani, R.

1999-01-01

Recently, full scale fixed-film or mixed suspended have been applied in many wastewater treatments plants. These processes no longer depend on biomass settle ability and can be used to improve the performance of existing plants as required by more stringent discharge permit limits, especially for nutrients suspended solids. Also, processes may work at high rates making is possible to build small footprint installations. Fixed-film processes include trickling filters (and combined suspended and fixed-films processes), rotating biological contactors, biological aerated submerged, filters moving bed reactors, fluidized bed reactors. In the first part, the theoretical based governing fixed-film processes are briefly outlined, with some simple examples of calculations, underlining the main differences with conventional activate sludge processes. In the second part, the most common types of reactors are reviewed [it

Biosorption of cobalt(II) with sunflower biomass from aqueous solutions in a fixed bed column and neural networks modelling.

Science.gov (United States)

Oguz, Ensar; Ersoy, Muhammed

2014-01-01

The effects of inlet cobalt(II) concentration (20-60 ppm), feed flow rate (8-19 ml/min) and bed height (5-15 cm), initial solution pH (3-5) and particle size (0.25shells of sunflower biomass was found to be 1.82 m(2)/g. A relationship between the predicted results of the ANN model and experimental data was conducted. The ANN model yielded determination coefficient of (R(2) 0.972), standard deviation ratio (0.166), mean absolute error (0.0158) and root mean square error (0.0141). The results indicated that the shells of the sunflower biomass is a suitable biosorbent for the uptake of cobalt(II) in fixed bed columns. © 2013 Published by Elsevier Inc.

Continuous removal and recovery of tellurium in an upflow anaerobic granular sludge bed reactor

Energy Technology Data Exchange (ETDEWEB)

Mal, Joyabrata, E-mail: joyabrata2006@gmail.com [UNESCO-IHE, Westvest 7, 2611 AX Delft (Netherlands); Nancharaiah, Yarlagadda V. [Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Bhabha Atomic Research Centre, Kalpakkam, 603102, Tamil Nadu (India); Homi Bhabha National Institute, Anushakti Nagar Complex, Mumbai 400094 (India); Maheshwari, Neeraj [CNRS UMR 7338, BMBI University de Technologie Compiegne, 60200 Compiegne (France); Hullebusch, Eric D. van [UNESCO-IHE, Westvest 7, 2611 AX Delft (Netherlands); Université Paris-Est, Laboratoire Géomatériaux et Environnement (LGE), EA 4508, UPEM, 77454, Marne-la-Vallée (France); Lens, Piet N.L. [UNESCO-IHE, Westvest 7, 2611 AX Delft (Netherlands); Department of Chemistry and Bioengineering, Tampere University of Technology, P.O-Box 541, Tampere (Finland)

2017-04-05

Highlights: • Tellurite bioreduction coupled to recovery of biogenic Te(0) nanocrystals. • First report on continuous tellurite removal in a UASB reactor. • Biogenic Te(0) was mainly associated with loosely-bound EPS of granular sludge. • Repeated exposure to tellurite caused compositional changes in the EPS matrix. - Abstract: Continuous removal of tellurite (TeO{sub 3}{sup 2−}) from synthetic wastewater and subsequent recovery in the form of elemental tellurium was studied in an upflow anaerobic granular sludge bed (UASB) reactor operated at 30 °C. The UASB reactor was inoculated with anaerobic granular sludge and fed with lactate as carbon source and electron donor at an organic loading rate of 0.6 g COD L{sup −1} d{sup −1}. After establishing efficient and stable COD removal, the reactor was fed with 10 mg TeO{sub 3}{sup 2−} L{sup −1} for 42 d before increasing the influent concentration to 20 mg TeO{sub 3}{sup 2−} L{sup −1}. Tellurite removal (98 and 92%, respectively, from 10 and 20 mg Te L{sup −1}) was primarily mediated through bioreduction and most of the removed Te was retained in the bioreactor. Characterization using XRD, Raman spectroscopy, SEM-EDX and TEM confirmed association of tellurium with the granular sludge, typically in the form of elemental Te(0) deposits. Furthermore, application of an extracellular polymeric substances (EPS) extraction method to the tellurite reducing sludge recovered up to 78% of the tellurium retained in the granular sludge. This study demonstrates for the first time the application of a UASB reactor for continuous tellurite removal from tellurite-containing wastewater coupled to elemental Te(0) recovery.

Performance evaluation and phylogenetic characterization of anaerobic fluidized bed reactors using ground tire and pet as support materials for biohydrogen production.

Science.gov (United States)

Barros, Aruana Rocha; Adorno, Maria Angela Tallarico; Sakamoto, Isabel Kimiko; Maintinguer, Sandra Imaculada; Varesche, Maria Bernadete Amâncio; Silva, Edson Luiz

2011-02-01

This study evaluated two different support materials (ground tire and polyethylene terephthalate [PET]) for biohydrogen production in an anaerobic fluidized bed reactor (AFBR) treating synthetic wastewater containing glucose (4000 mg L(-1)). The AFBR, which contained either ground tire (R1) or PET (R2) as support materials, were inoculated with thermally pretreated anaerobic sludge and operated at a temperature of 30°C. The AFBR were operated with a range of hydraulic retention times (HRT) between 1 and 8h. The reactor R1 operating with a HRT of 2h showed better performance than reactor R2, reaching a maximum hydrogen yield of 2.25 mol H(2)mol(-1) glucose with 1.3mg of biomass (as the total volatile solids) attached to each gram of ground tire. Subsequent 16S rRNA gene sequencing and phylogenetic analysis of particle samples revealed that reactor R1 favored the presence of hydrogen-producing bacteria such as Clostridium, Bacillus, and Enterobacter. Copyright © 2010 Elsevier Ltd. All rights reserved.

Computational Fluid Dynamics Simulations of Gas-Phase Radial Dispersion in Fixed Beds with Wall Effects

Directory of Open Access Journals (Sweden)

Anthony G. Dixon

2017-10-01

Full Text Available The effective medium approach to radial fixed bed dispersion models, in which radial dispersion of mass is superimposed on axial plug flow, is based on a constant effective dispersion coefficient, DT. For packed beds of a small tube-to-particle diameter ratio (N, the experimentally-observed decrease in this parameter near the tube wall is accounted for by a lumped resistance located at the tube wall, the wall mass transfer coefficient km. This work presents validated computational fluid dynamics (CFD simulations to obtain detailed radial velocity and concentration profiles for eight different computer-generated packed tubes of spheres in the range 5.04 ≤ N ≤ 9.3 and over a range of flow rates 87 ≤ Re ≤ 870 where Re is based on superficial velocity and the particle diameter dp. Initial runs with pure air gave axial velocity profiles vz(r averaged over the length of the packing. Then, simulations with the tube wall coated with methane yielded radial concentration profiles. A model with only DT could not describe the radial concentration profiles. The two-parameter model with DT and km agreed better with the bed-center concentration profiles, but not with the sharp decreases in concentration close to the tube wall. A three-parameter model based on classical two-layer mixing length theory, with a wall-function for the decrease in transverse radial convective transport in the near-wall region, showed greatly improved ability to reproduce the near-wall concentration profiles.

Packed- and fluidized-bed biofilm reactor performance for anaerobic wastewater treatment.

Science.gov (United States)

Denac, M; Dunn, I J

1988-07-05

Anaerobic degradation performance of a laboratory-scale packed-bed reactor (PBR) was compared with two fluidized-bed biofilm reactors (FBRs) on molasses and whey feeds. The reactors were operated under constant pH (7) and temperature (35 degrees C) conditions and were well mixed with high recirculation rates. The measured variables were chemical oxygen demand (COD), individual organic acids, gas composition, and gas rates. As carrier, sand of 0.3-0.5 mm diameter was used in the FBR, and porous clay spheres of 6 mm diameter were used in the PBR. Startup of the PBR was achieved with 1-5 day residence times. Start-up of the FBR was only successful if liquid residence times were held low at 2-3 h. COD degradations of 86% with molasses (90% was biodegradable) were reached in both the FBR and PBR at 6 h residence time and loadings of 10 g COD/L day. At higher loadings the FBR gave the best performance; even at 40-45 g COD/L day, with 6 h residence times, 70% COD was degraded. The PBR could not be operated above 20 g COD/L day without clogging. A comparison of the reaction rates show that the PBR and FBR per formed similarly at low concentrations in the reactors up to 1 g COD/L, while above 3 g COD/L the rates were 17.4 g COD/L day for the PBR and 38.4 g COD/L day for the FBR. This difference is probably due to diffusion limitations and a less active biomass content of the PBR compared with the fluidized bed.The results of dynamic step change experiments, in which residence times and feed concentrations were changed hanged at constant loading, demonstrated the rapid response of the reactors. Thus, the response times for an increase in gas rate or an increase in organic acids due to an increase in feed concentration were less than 1 day and could be explained by substrate limitation. Other slower responses were observed in which the reactor culture adapted over periods of 5-10 days; these were apparently growth related. An increase in loading of over 100% always resulted

Axial Changes of Catalyst Structure and Temperature in a Fixed-Bed Microreactor During Noble Metal Catalysed Partial Oxidation of Methane

DEFF Research Database (Denmark)

Hannemann, S.; Grunwaldt, Jan-Dierk; Kimmerle, B.

2009-01-01

The catalytic partial oxidation of methane (CPO) over flame-made 2.5%Rh-2.5%Pt/Al2O3 and 2.5%Rh/Al2O3 in 6%CH4/3%O-2/He shows the potential of in situ studies using miniaturized fixed-bed reactors, the importance of spatially resolved studies and its combination with infrared thermography and on-...

Biothane process. Methane-producing treatment of wastewaters in a granular sludge bed

Energy Technology Data Exchange (ETDEWEB)

Boulenger, P; Vesprille, B

1982-01-01

The Biothane-UASB (upflow anaerobic sludge blanket) process, an anaerobic fermentation system with 2 granular sludge beds, effectively treats wastewaters from cheese and starch manufacture and is suitable for other industrial effluents, such as sugar beet alcohol distillation wastewaters and biosynthesis wases.

Anaerobic digestion of grain stillage at high organic loading rates in three different reactor systems

International Nuclear Information System (INIS)

Schmidt, Thomas; Pröter, Jürgen; Scholwin, Frank; Nelles, Michael

2013-01-01

In this study the anaerobic digestion of grain stillage in three different reactor systems (continuous stirred tank reactor, anaerobic sequencing batch reactor, fixed bed reactor) with and without immobilization of microorganisms was investigated to evaluate the performance during increase of the organic loading rate (OLR) from 1 to 10 g of volatile solids (VS) per liter reactor volume and day and decrease of the hydraulic retention time (HRT) from 40 to 6 days. No significant differences have been observed between the performances of the three examined reactor systems. The changes in OLR and HRT caused a reduction of the specific biogas production (SBP) of about 25% from about 650 to 550 L kg −1 of VS but would also diminish the necessary digester volume and investment costs of about 75% compared to the state of the art. -- Highlights: ► It was shown that without immobilization of microorganisms low HRT's are possible. ► No significant differences have been observed between different digester designs. ► Trace element supplementation is obligatory with grain stillage as substrate

Stabilization of fine fraction from landfill mining in anaerobic and aerobic laboratory leach bed reactors.

Science.gov (United States)

Mönkäre, Tiina J; Palmroth, Marja R T; Rintala, Jukka A

2015-11-01

Fine fraction (FF, mined landfill was stabilized in four laboratory-scale leach bed reactors (LBR) over 180 days. The aim was to study feasibility of biotechnological methods to treat FF and if further stabilization of FF is possible. Four different stabilization methods were compared and their effects upon quality of FF were evaluated. Also during the stabilization experiment, leachate quality as well as gas composition and quantity were analyzed. The methods studied included three anaerobic LBRs (one without water addition, one with water addition, and one with leachate recirculation) and one aerobic LBR (with water addition). During the experiment, the most methane was produced in anaerobic LBR without water addition (18.0 L CH4/kg VS), while water addition and leachate recirculation depressed methane production slightly, to 16.1 and 16.4 L CH4/kg VS, respectively. Organic matter was also removed via the leachate and was measured as chemical oxygen demand (COD). Calculated removal of organic matter in gas and leachate was highest in LBR with water addition (59 g COD/kg VS), compared with LBR without water addition or with leachate recirculation (51 g COD/kg VS). Concentrations of COD, ammonium nitrogen and anions in leachate decreased during the experiment, indicating washout mechanism caused by water additions. Aeration increased sulfate and nitrate concentrations in leachate due to oxidized sulfide and ammonium. Molecular weight distributions of leachates showed that all the size categories decreased, especially low molecular weight compounds, which were reduced the most. Aerobic stabilization resulted in the lowest final VS/TS (13.1%), lowest respiration activity (0.9-1.2 mg O2/g TS), and lowest methane production after treatment (0.0-0.8 L CH4/kg VS), with 29% of VS being removed from FF. Anaerobic stabilization methods also reduced organic matter by 9-20% compared with the initial amount. Stabilization reduced the quantity of soluble nitrogen in FF and did

Transient Effects in Fischer-Tropsch Reactor with a Fixed Bed of Catalyst Particles

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I. V. Derevich

2015-01-01

Full Text Available Based on analysis of small temperature disturbances in the Fischer-Tropsch reactor with a fixed bed of catalyst particles various scenarios of thermal instability were investigated. There are two possible scenarios of thermal instability of the reactor. First, thermal explosion may occur due to growth of temperature disturbances inside a catalytic granule. Second scenario connected with loss of thermal stability as a result of an initial increase in temperature in the reactor volume. The boundaries of thermal stability of the reactor were estimated by solving the eigenvalue problems for spherical catalyst particles and cylindrical reactor. Processes of diffusional resistance inside the catalytic granule and heat transfer from wall of the reactor tube are taken into account. Estimation of thermal stability area is compared with the results of numerical simulation of behavior of temperature and concentration of synthesis gas.

Development of a computer program for the simulation of one-dimensional fixed- and moving-bed reactors

International Nuclear Information System (INIS)

Hartner, P.

1996-11-01

Chemical reactors with a flow through a bed of solid particles are of great importance in the processing industry. Modern computational tools allow for an improved characterization of the complex facts in such reactors leading to new opportunities of optimizing the reactor operation and environmental effects. This thesis is concerned with the development of the one-dimensional simulation software REASIM. The program covers the effects within a reacting bed and is designed for fixed and moving beds. To describe the reactor the balances for energy, momentum and mass are solved. The drying of the particles, pyrolysis and chemical gas-solid and gas-gas reactions are considered. For the description of the chemical gas-solid reactions a particle model for porous solids is developed. The calculation of mass transfer and of chemical reactions is strictly separated. All parameters necessary for the model can be measured in the laboratory. The model equations form a system of partial differential equations. This system is transformed to a set of ordinary differential equations. It is found that the best discretization method is the method of finite differences with the upwind-scheme for situations where convection is strong. The program has a modular structure making it is easy to replace parts of the program by new, improved modules if they become available. (author)

Integral urban wastewater treatment process with a combined anaerobic and aerobic system; Tratamiento integral de aguas residuales urbanas mediante procesos combinados anaerobios y aerobios. Aplicacion de sistema Bioredox a escala piloto

Energy Technology Data Exchange (ETDEWEB)

Moreno Carmona, A; Angulo Sanchez, R.

1997-04-01

A pilot study was carried out of an integral urban sewage treatment process involving a combined anaerobic and aerobic system. the anaerobic digester has a fixed bed on a ceramic support and a 10m``3 upward flow. It operates at ambient temperature (12-15 degree centigree) with hydraulic retention to,es (HRTs) of 24-12 hours and a load of 4-2.6 kg DQO/m``3/day. Anaerobic digestion reduced SSt by over 90% for HRT of 16 and 12 hours. The 20 m``3 prolonged oxidation reactor operates with a load of 0.17-0.45 kg DQO/m``3/day. the plant`s DQO and SST reduction varied between 81% and 89% for the 16 and 12 hour tests and 85-92% (HRT=16 hours and 12 hours respectively). the overall proportions of pathogenic microorganisms eliminated in the experimental plant was greater than 97%. (Author) 23 refs.

Anaerobic treatment of wastewater with high suspended solids from a bulk drug industry using fixed film reactor (AFFR).

Science.gov (United States)

Gangagni Rao, A; Venkata Naidu, G; Krishna Prasad, K; Chandrasekhar Rao, N; Venkata Mohan, S; Jetty, Annapurna; Sarma, P N

2005-01-01

Studies were carried out on the treatment of wastewater from a bulk drug industry using an anaerobic fixed film reactor (AFFR) designed and fabricated in the laboratory. The chemical oxygen demand (COD) and total dissolved solids (TDS) of the wastewater were found to be very high with low biochemical oxygen demand (BOD) to COD ratio and high total suspended solid (TSS) concentration. Acclimatization of seed consortia and startup of the reactor was carried out by directly using the wastewater, which resulted in reducing the period of startup to 30 days. The reactor was studied at different organic loading rates (OLR) and it was found that the optimum OLR was 10 kg COD/m(3)/day. The wastewater under investigation, which had a considerable quantity of SS, was treated anaerobically without any pretreatment. COD and BOD of the reactor outlet wastewater were monitored and at steady state and optimum OLR 60-70% of COD and 80-90% of BOD were removed. The reactor was subjected to organic shock loads at two different OLR and the reaction could withstand the shocks and performance could be restored to normalcy at that OLR. The results obtained indicated that AFFR could be used efficiently for the treatment of wastewater from a bulk drug industry having high COD, TDS and TSS.

Anaerobic treatment of agro-industrial wastewaters for COD removal in expanded granular sludge bed bioreactor

Directory of Open Access Journals (Sweden)

Abumalé Cruz-Salomón

2017-12-01

Full Text Available Untreated agro-industrial wastewaters are undesirable in the aquatic environment due to the presence of high organic matter contents. However, they may constitute a large potential for biogas production. The present investigation is focused on three laboratory-scale anaerobic expanded granular sludge bed (EGSB bioreactors, continuously operated for 60 d under mesophilic condition with the aim of exploring the feasibility of treating three most significant agro-industrial wastewaters in Chiapas, Mexico (i.e., cheese whey, vinasse, and coffee-processing wastewater. The EGSB bioreactors were operated with a hydraulic retention time (HRT of 6 d under stable conditions (i.e., buffer index (BI of 0.31, 0.34, and 0.03, generating a maximum chemical oxygen demand (COD removal efficiency of 91, 74, and 96% with an average methane production of 340, 245, and 300 mL/g COD∙d for cheese whey, vinasse, and coffee-processing wastewater, respectively. According to the obtained results, the EGSB bioreactors could be a sustainable alternative to simultaneously solve the environmental problems and to produce bioenergy.

BATCH AND FIXED BED ADSORPTION STUDIES OF LEAD (II CATIONS FROM AQUEOUS SOLUTIONS ONTO GRANULAR ACTIVATED CARBON DERIVED FROM MANGOSTANA GARCINIA SHELL

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Zaira Zaman Chowdhury,

2012-05-01

Full Text Available The feasibility of granular activated carbon (GAC derived from Mangostene (Mangostana garcinia fruit shell to remove lead, Pb2+ cations was investigated in batch and fixed bed sorption systems. Batch experiments were carried out to study equilibrium isotherms, kinetics, and thermodynamics by using an initial lead (Pb2+ ions concentration of 50 to 100 mg/L at pH 5.5. Equilibrium data were fitted using Langmuir, Freundlich, and Temkin linear equation models at temperatures 30°C, 50°C, and 70°C. Langmuir maximum monolayer sorption capacity was 25.00 mg/g at 30°C. The experimental data were best represented by pseudo-second-order and Elovich models. The sorption process was found to be feasible, endothermic, and spontaneous. In column experiments, the effects of initial cation concentration (50 mg/L, 70 mg/L, and 100 mg/L, bed height (4.5 cm and 3 cm, and flow rate (1 mL/min and 3 mL/min on the breakthrough characteristics were evaluated. Breakthrough curves were further analyzed by using Thomas and Yoon Nelson models to study column dynamics. The column was regenerated and reused consecutively for four cycles. The result demonstrated that the prepared activated carbon was suitable for removal of Pb2+ from synthetic aqueous solution using batch, as well as fixed bed sorption systems.

Simultaneous nitrification-denitrification and phosphorus removal in a fixed bed sequencing batch reactor (FBSBR)

International Nuclear Information System (INIS)

Rahimi, Yousef; Torabian, Ali; Mehrdadi, Naser; Shahmoradi, Behzad

2011-01-01

Research highlights: → Sludge production in FSBR reactor is 20-30% less than SBR reactor. → FSBR reactor showed more nutrient removal rate than SBR reactor. → FSBR reactor showed less VSS/TSS ratio than SBR reactor. - Abstract: Biological nutrient removal (BNR) was investigated in a fixed bed sequencing batch reactor (FBSBR) in which instead of activated sludge polypropylene carriers were used. The FBSBR performance on carbon and nitrogen removal at different loading rates was significant. COD, TN, and phosphorus removal efficiencies were at range of 90-96%, 60-88%, and 76-90% respectively while these values at SBR reactor were 85-95%, 38-60%, and 20-79% respectively. These results show that the simultaneous nitrification-denitrification (SND) is significantly higher than conventional SBR reactor. The higher total phosphorus (TP) removal in FBSBR correlates with oxygen gradient in biofilm layer. The influence of fixed media on biomass production yield was assessed by monitoring the MLSS concentrations versus COD removal for both reactors and results revealed that the sludge production yield (Y obs ) is significantly less in FBSBR reactors compared with SBR reactor. The FBSBR was more efficient in SND and phosphorus removal. Moreover, it produced less excess sludge but higher in nutrient content and stabilization ratio (less VSS/TSS ratio).

Simultaneous nitrification-denitrification and phosphorus removal in a fixed bed sequencing batch reactor (FBSBR)

Energy Technology Data Exchange (ETDEWEB)

Rahimi, Yousef, E-mail: you.rahimi@gmail.com [Department of Civil and Environmental Engineering, Graduate Faculty of Environment, University of Tehran, No. 25 Qods St., Enghelab Ave, Tehran (Iran, Islamic Republic of); Torabian, Ali, E-mail: atorabi@ut.ac.ir [Department of Civil and Environmental Engineering, Graduate Faculty of Environment, University of Tehran, No. 25 Qods St., Enghelab Ave, Tehran (Iran, Islamic Republic of); Mehrdadi, Naser, E-mail: mehrdadi@ut.ac.ir [Department of Civil and Environmental Engineering, Graduate Faculty of Environment, University of Tehran, No. 25 Qods St., Enghelab Ave, Tehran (Iran, Islamic Republic of); Shahmoradi, Behzad, E-mail: bshahmorady@gmail.com [Department of Environmental Science, University of Mysore, MGM-06 Mysore (India)

2011-01-30

Research highlights: {yields} Sludge production in FSBR reactor is 20-30% less than SBR reactor. {yields} FSBR reactor showed more nutrient removal rate than SBR reactor. {yields} FSBR reactor showed less VSS/TSS ratio than SBR reactor. - Abstract: Biological nutrient removal (BNR) was investigated in a fixed bed sequencing batch reactor (FBSBR) in which instead of activated sludge polypropylene carriers were used. The FBSBR performance on carbon and nitrogen removal at different loading rates was significant. COD, TN, and phosphorus removal efficiencies were at range of 90-96%, 60-88%, and 76-90% respectively while these values at SBR reactor were 85-95%, 38-60%, and 20-79% respectively. These results show that the simultaneous nitrification-denitrification (SND) is significantly higher than conventional SBR reactor. The higher total phosphorus (TP) removal in FBSBR correlates with oxygen gradient in biofilm layer. The influence of fixed media on biomass production yield was assessed by monitoring the MLSS concentrations versus COD removal for both reactors and results revealed that the sludge production yield (Y{sub obs}) is significantly less in FBSBR reactors compared with SBR reactor. The FBSBR was more efficient in SND and phosphorus removal. Moreover, it produced less excess sludge but higher in nutrient content and stabilization ratio (less VSS/TSS ratio).

HIGH-RATE ANAEROBIC TREATMENT OF ALCOHOLIC WASTEWATERS

Directory of Open Access Journals (Sweden)

Florencio L.

1997-01-01

Full Text Available Modern high-rate anaerobic wastewater treatment processes are rapidly becoming popular for industrial wastewater treatment. However, until recently stable process conditions could not be guaranteed for alcoholic wastewaters containing higher concentrations of methanol. Although methanol can be directly converted into methane by methanogens, under specific conditions it can also be converted into acetate and butyrate by acetogens. The accumulation of volatile fatty acids can lead to reactor instability in a weakly buffered reactor. Since this process was insufficiently understood, the application of high-rate anaerobic reactors was highly questionable. This research investigated the environmental factors that are of importance in the predominance of methylotrophic methanogens over acetogens in a natural mixed culture during anaerobic wastewater treatment in upflow anaerobic sludge bed reactors. Technological and microbiological aspects were investigated. Additionally, the route by which methanol is converted into methane is also presented

PENGOLAHAN LIMBAH CAIR ORGANIK SECARA BIOLOGI MENGGUNAKAN REAKTOR ANAEROBIK LEKAT DIAM

OpenAIRE

Indriyati, Indriyati

2018-01-01

   Organic waste water can be treated biolocally by using anaerobic fixed bed reactor. Fixed bed reactor is bioreactor which is compleeted with support material inside reactor for bacteria fixation in the surface area of support material. The benefit of using this kind of technology are it needs low energy, low nutrien, low sludge production and could treat high organic concentraion waste water.   The support material  has important role in the  Fixed Bed reactor performance, therefore it mus...

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 Coal biosolubilisation was investigated in stirred tank reactor, fluidised bed and fixed bed bioreactors with a view to highlight the advantages and shortcomings of each of these reactor configurations. The stirred aerated bioreactor and fluidised...

Synthesis and characterization of organic–inorganic core–shell structure nanocomposite and application for Zn ions removal from aqueous solution in a fixed-bed column

Energy Technology Data Exchange (ETDEWEB)

Ghasemi, Shokoofeh [Faculty of Chemical, Gas and Petroleum Engineering, Semnan University, Semnan 35131-19111 (Iran, Islamic Republic of); Ghorbani, Mohsen, E-mail: M.ghorbani@nit.ac.ir [Faculty of Chemical Engineering, Babol University of Technology, P.O. Box 484, Babol (Iran, Islamic Republic of); Ghazi, Mohsen Mehdipour [Faculty of Chemical, Gas and Petroleum Engineering, Semnan University, Semnan 35131-19111 (Iran, Islamic Republic of)

2015-12-30

Graphical abstract: - Highlights: • The γ-Fe{sub 2}O{sub 3} nanoparticles were prepared in one step using ultrasonic radiation and coated by polyrhodanine. • Nanocomposite synthesized with core average diameter of 15 nm and polyrhodanine as shell with thickness of 1.5 nm • Application of products was investigated to separate zinc ions from aqueous solution in a fixed-bed column. • The Adams–Bohart, BDST, Thomas and Yoon–Nelson models used to predict model parameters. • The models were nearly in good agreement with the experimental data. - Abstract: An organic–inorganic core/shell structure, γ-Fe{sub 2}O{sub 3}/polyrhodanine nanocomposite with γ-Fe{sub 2}O{sub 3} nanoparticle as core with average diameter of 15 nm and polyrhodanine as shell with thickness of 1.5 nm, has been synthesized via chemical oxidation polymerization and applied for adsorption of Zn ions from aqueous solution in a fixed-bed column. The properties of nanocomposite were characterized with transmission electron microscope (TEM), Fourier transform infrared (FT-IR) spectroscopy and vibrating sample magnetometer (VSM). The performance of the column was assessed under variable bed heights (10, 15 and 20 cm) and influent Zn concentrations (50, 100 and 150 ppm) at a constant flow rate (0.5 mL/min). The results demonstrated that the breakthrough curves are S-shaped and the breakthrough time increases with increasing bed height and decreases with increasing influent concentration. Moreover, the dynamics of the adsorption process were evaluated by using Adams–Bohart, bed depth service time (BDST), Thomas and Yoon–Nelson kinetic models. The models were nearly in good agreement with the experimental data.

Mathematical Modeling and Simulation of the Dehydrogenation of Ethyl Benzene to Form Styrene Using Steady-State Fixed Bed Reactor

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Zaidon M. Shakoor

2013-05-01

Full Text Available In this research, two models are developed to simulate the steady state fixed bed reactor used for styrene production by ethylbenzene dehydrogenation. The first is one-dimensional model, considered axial gradient only while the second is two-dimensional model considered axial and radial gradients for same variables.The developed mathematical models consisted of nonlinear simultaneous equations in multiple dependent variables. A complete description of the reactor bed involves partial, ordinary differential and algebraic equations (PDEs, ODEs and AEs describing the temperatures, concentrations and pressure drop across the reactor was given. The model equations are solved by finite differences method. The reactor models were coded with Mat lab 6.5 program and various numerical techniques were used to obtain the desired solution.The simulation data for both models were validated with industrial reactor results with a very good concordance.

Batch and fixed-bed adsorption of tartrazine azo-dye onto activated carbon prepared from apricot stones

Science.gov (United States)

Albroomi, H. I.; Elsayed, M. A.; Baraka, A.; Abdelmaged, M. A.

2017-07-01

This work describes the potential of utilizing prepared activated carbon from apricot stones as an efficient adsorbent material for tartrazine (TZ) azo-dye removal in a batch and dynamic adsorption system. The results revealed that activated carbons with well-developed surface area (774 m2/g) and pore volume (1.26 cm3/g) can be manufactured from apricot stones by H3PO4 activation. In batch experiments, effects of the parameters such as initial dye concentration and temperature on the removal of the dye were studied. Equilibrium was achieved in 120 min. Adsorption capacity was found to be dependent on the initial concentration of dye solution, and maximum adsorption was found to be 76 mg/g at 100 mg/L of TZ. The adsorption capacity at equilibrium ( q e) increased from 22.6 to 76 mg/g with an increase in the initial dye concentrations from 25 to 100 mg/L. The thermodynamic parameters such as change in free energy (Δ G 0), enthalpy (Δ H 0) and entropy (Δ S 0) were determined and the positive value of (Δ H) 78.1 (K J mol-1) revealed that adsorption efficiency increased with an increase in the process temperature. In fixed-bed column experiments, the effect of selected operating parameters such as bed depth, flow rate and initial dye concentration on the adsorption capacity was evaluated. Increase in bed height of adsorption columns leads to an extension of breakthrough point as well as the exhaustion time of adsorbent. However, the maximum adsorption capacities decrease with increases of flow rate. The breakthrough data fitted well to bed depth service time and Thomas models with high coefficient of determination, R 2 ≥ 94.

Mathematical Modelling of Catalytic Fixed-Bed Reactor for Carbon Dioxide Reforming of Methane over Rh/Al2O3 Catalyst

Directory of Open Access Journals (Sweden)

New Pei Yee

2008-04-01

Full Text Available A one-dimensional mathematical model was developed to simulate the performance of catalytic fixed bedreactor for carbon dioxide reforming of methane over Rh/Al2O3 catalyst at atmospheric pressure. The reactionsinvolved in the system are carbon dioxide reforming of methane (CORM and reverse water gas shiftreaction (RWGS. The profiles of CH4 and CO2 conversions, CO and H2 yields, molar flow rate and molefraction of all species as well as reactor temperature along the axial bed of catalyst were simulated. In addition,the effects of different reactor temperature on the reactor performance were also studied. The modelscan also be applied to analyze the performances of lab-scale micro reactor as well as pilot-plant scale reactorwith certain modifications and model verification with experimental data. © 2008 BCREC UNDIP. All rights reserved.[Received: 20 August 2008; Accepted: 25 September 2008][How to Cite: N.A.S. Amin, I. Istadi, N.P. Yee. (2008. Mathematical Modelling of Catalytic Fixed-Bed Reactor for Carbon Dioxide Reforming of Methane over Rh/Al2O3 Catalyst. Bulletin of Chemical Reaction Engineering and Catalysis, 3 (1-3: 21-29. doi:10.9767/bcrec.3.1-3.19.21-29

Evaluating Design Parameters for Breakthrough Curve Analysis and Kinetics of Fixed Bed Columns for Cu(II Cations Using Lignocellulosic Wastes

Directory of Open Access Journals (Sweden)

Zaira Zaman Chowdhury

2014-12-01

Full Text Available A continuous adsorption study for removal of Cu(II cations from wastewater using a fixed-bed column was conducted. A granular carbonaceous activated adsorbent produced by carbonization of the outer rind, or exocarp, of mangostene fruit shell was used for column packing. The effects of feed flow rate, influent cation concentration, and bed depth on the breakthrough curve were investigated at pH 5.5. Experimental analysis confirmed that the breakthrough curves were dependent on flow rate, initial concentration of Cu(II cations, and bed height related to the amount of activated carbon used for column packing. Thomas, Yoon–Nelson, and Adams–Bohart models were applied to analyze the breakthrough curves at different conditions. Linear regression analysis of experimental data demonstrated that Thomas and Yoon–Nelson models were appropriate to explain the breakthrough curve, while the Adams–Bohart model was only applicable to predict the initial part of the dynamic process. It was concluded that the column packed with fruit rind based activated carbon can be used to treat Cu(II-enriched wastewater.

Biomass gasification in fixed bed type down draft: theoretical and experimental aspects; Gasificacao de biomassa em leito fixo tipo concorrente: aspectos teoricos e experimentais

Energy Technology Data Exchange (ETDEWEB)

Martinez, Juan Daniel; Andrade, Rubenildo Vieira; Lora, Electo Eduardo Silva [Universidade Federal de Itajuba (UNIFEI), MG (Brazil). Inst. de Engenharia Mecanica. Nucleo de Excelencia em Geracao Termeletrica e Distribuida

2008-07-01

Actually are recognizing the advantages of biomass in reducing dependence on fossil fuels and significant reduction in emissions of greenhouse effect gases such as Co2. Also are known the different conversion of biomass routes for their use or exploitation, such as thermochemical process (gasification, pyrolysis and combustion), the biological process (fermentation and transesterification) and the physical process (densification, reducing grain and mechanical pressing). In this sense, the gasification is regarded as the most promising mechanism to obtain a homogeneous gaseous fuel with sufficient quality in the small scale distributed generation. This work presents some aspects of biomass gasification in fixed bed, as well as some preliminary results in the evaluation and operation of fixed bed down draft gasifier with double stage air supply of the NEST, identifying the adequate air supply quantity (equivalence ratio in the range of 0,35 to 0,45) for obtaining a fuel gas with lower heating value around 4 MJ/N m3. (author)

Horse manure as feedstock for anaerobic digestion.

Science.gov (United States)

Hadin, Sa; Eriksson, Ola

2016-10-01

Horse keeping is of great economic, social and environmental benefit for society, but causes environmental impacts throughout the whole chain from feed production to manure treatment. According to national statistics, the number of horses in Sweden is continually increasing and is currently approximately 360,000. This in turn leads to increasing amounts of horse manure that have to be managed and treated. Current practices could cause local and global environmental impacts due to poor performance or lack of proper management. Horse manure with its content of nutrients and organic material can however contribute to fertilisation of arable land and recovery of renewable energy following anaerobic digestion. At present anaerobic digestion of horse manure is not a common treatment. In this paper the potential for producing biogas and biofertiliser from horse manure is analysed based on a thorough literature review in combination with mathematical modelling and simulations. Anaerobic digestion was chosen as it has a high degree of resource conservation, both in terms of energy (biogas) and nutrients (digestate). Important factors regarding manure characteristics and operating factors in the biogas plant are identified. Two crucial factors are the type and amount of bedding material used, which has strong implications for feedstock characteristics, and the type of digestion method applied (dry or wet process). Straw and waste paper are identified as the best materials in an energy point of view. While the specific methane yield decreases with a high amount of bedding, the bedding material still makes a positive contribution to the energy balance. Thermophilic digestion increases the methane generation rate and yield, compared with mesophilic digestion, but the total effect is negligible. Copyright © 2016. Published by Elsevier Ltd.

Efficiency comparison of different biofilm carriers concerning the P- and N-elimination in a fluidized bed system under alternating anaerobic/anoxic conditions; Leistungsvergleich verschiedener Traegermaterialien - hinsichtlich ihrer Eignung zur N- und P-Elimination in einem alternierend anaerob/anoxisch betriebenen Wirbelbettverfahren

Energy Technology Data Exchange (ETDEWEB)

Brandt, D.; Hegemann, W. [Techn. Univ. Berlin, Fachgebiet Siedlungswasserwirtschaft, Berlin (Germany)

2001-09-01

Objective of the depicted research was the selection of a carrier material that is suitable for the the use in the Sorption-Denitrification-P-Removal-process (S-DN-P-process) realized in a Fluidized-Bed-Biofilm-Reactor. The S-DN-P-process is a biofilmprocess which combines denitrification and biological P-removal in a new way. The biomass is exposed to a sequential change of anaerobic, substrate-rich wastewater and anoxic, substrate-poor wastewater. Under these conditions phosphate-accumulating organisms (PAO) are enriched which are able to use nitrate as electron acceptor. Consequently, the readily biodegradable wastewater components are used simultaneously for denitrification and biological P-removal. In the described investigations special carriers were compared which were especially developed for fluidized-bed-processes and moving-bed-processes. With one exception, it was established that all materials had similar performances although they had different specific surfaces. Therefore the material costs will be crucially for a particular application case. At the moment the costs per m{sup 3} carrier material range between 450 and 1000 DM. (orig.)

Design of adiabatic fixed-bed reactors for the partial oxidation of methane to synthesis gas. Application to production of methanol and hydrogen-for-fuel-cells

NARCIS (Netherlands)

Smet, de C.R.H.; Croon, de M.H.J.M.; Berger, R.J.; Marin, G.B.M.M.; Schouten, J.C.

2001-01-01

Adiabatic fixed-bed reactors for the catalytic partial oxidn. (CPO) of methane to synthesis gas were designed at conditions suitable for the prodn. of methanol and hydrogen-for-fuel-cells. A steady-state, one-dimensional heterogeneous reactor model was applied in the simulations. Intra-particle

Volatile organic compound adsorption in a gas-solid fluidized bed.

Science.gov (United States)

Ng, Y L; Yan, R; Tsen, L T S; Yong, L C; Liu, M; Liang, D T

2004-01-01

Fluidization finds many process applications in the areas of catalytic reactions, drying, coating, combustion, gasification and microbial culturing. This work aims to compare the dynamic adsorption characteristics and adsorption rates in a bubbling fluidized bed and a fixed bed at the same gas flow-rate, gas residence time and bed height. Adsorption with 520 ppm methanol and 489 ppm isobutane by the ZSM-5 zeolite of different particle size in the two beds enabled the differentiation of the adsorption characteristics and rates due to bed type, intraparticle mass transfer and adsorbate-adsorbent interaction. Adsorption of isobutane by the more commonly used activated carbon provided the comparison of adsorption between the two adsorbent types. With the same gas residence time of 0.79 seconds in both the bubbling bed and fixed bed of the same bed size of 40 mm diameter and 48 mm height, the experimental results showed a higher rate of adsorption in the bubbling bed as compared to the fixed bed. Intraparticle mass transfer and adsorbent-adsorbate interaction played significant roles in affecting the rate of adsorption, with intraparticle mass transfer being more dominant. The bubbling bed was observed to have a steeper decline in adsorption rate with respect to increasing outlet concentration compared to the fixed bed. The adsorption capacities of zeolite for the adsorbates studied were comparatively similar in both beds; fluidizing, and using smaller particles in the bubbling bed did not increase the adsorption capacity of the ZSM-5 zeolite. The adsorption capacity of activated carbon for isobutane was much higher than the ZSM-5 zeolite for isobutane, although at a lower adsorption rate. Fourier transform infra-red (FTIR) spectroscopy was used as an analytical tool for the quantification of gas concentration. Calibration was done using a series of standards prepared by in situ dilution with nitrogen gas, based on the ideal gas law and relating partial pressure to gas

Co-pyrolysis of rice straw and polypropylene using fixed-bed pyrolyzer

Science.gov (United States)

Izzatie, N. I.; Basha, M. H.; Uemura, Y.; Mazlan, M. A.; Hashim, M. S. M.; Amin, N. A. M.; Hamid, M. F.

2016-11-01

The present work encompasses the impact of temperature (450, 500, 550, 600 °C) on the properties of pyrolysis oil and on other product yield for the co-pyrolysis of Polypropylene (PP) plastics and rice straw. Co-pyrolysis of PP plastic and rice straw were conducted in a fixed-bed drop type pyrolyzer under an inert condition to attain maximum oil yield. Physically, the pyrolysis oil is dark-brown in colour with free flowing and has a strong acrid smell. Copyrolysis between these typically obtained in maximum pyrolysis oil yields up to 69% by ratio 1:1 at a maximum temperature of 550 °C. From the maximum yield of pyrolysis oil, characterization of pyrolysis product and effect of biomass type of the composition were evaluated. Pyrolysis oil contains a high water content of 66.137 wt.%. Furfural, 2- methylnaphthalene, tetrahydrofuran (THF), toluene and acetaldehyde were the major organic compounds found in pyrolysis oil of rice straw mixed with PP. Bio-char collected from co-pyrolysis of rice straw mixed with PP plastic has high calorific value of 21.190 kJ/g and also carbon content with 59.02 wt.% and could contribute to high heating value. The non-condensable gases consist of hydrogen, carbon monoxide, and methane as the major gas components.

Anaerobic digestion of cheese whey using an upflow anaerobic sludge blanket reactor: Pt. 3; Sludge and substrate profiles

Energy Technology Data Exchange (ETDEWEB)

Yan, J.Q.; Lo, K.V.; Liao, P.H. (British Columbia Univ., Vancouver (CA). Dept. of Bio-Resource Engineering)

1990-01-01

Anaerobic treatment of cheese whey using a 17.5 litre upflow anaerobic sludge blanket reactor was investigated in the laboratory over a range of influent concentration from 4.5 to 38.1 g COD litre{sup -1} at a constant hydraulic retention time of 5 days. The results indicated that two sludge distribution regions, a sludge bed and a sludge blanket, as well as two distinct reaction phases, acidogenic and methanogenic, were formed. However, as the substrate loading was increased, the acidogenic region extended into the methanogenic region in the upper portion of the reactor until the whole region was acidogenic, leading to the failure of the reactor. (author).

Numerical investigation of flow and heat transfer in a novel configuration multi-tubular fixed bed reactor for propylene to acrolein process

Science.gov (United States)

Jiang, Bin; Hao, Li; Zhang, Luhong; Sun, Yongli; Xiao, Xiaoming

2015-01-01

In the present contribution, a numerical study of fluid flow and heat transfer performance in a pilot-scale multi-tubular fixed bed reactor for propylene to acrolein oxidation reaction is presented using computational fluid dynamics (CFD) method. Firstly, a two-dimensional CFD model is developed to simulate flow behaviors, catalytic oxidation reaction, heat and mass transfer adopting porous medium model on tube side to achieve the temperature distribution and investigate the effect of operation parameters on hot spot temperature. Secondly, based on the conclusions of tube-side, a novel configuration multi-tubular fixed-bed reactor comprising 790 tubes design with disk-and-doughnut baffles is proposed by comparing with segmental baffles reactor and their performance of fluid flow and heat transfer is analyzed to ensure the uniformity condition using molten salt as heat carrier medium on shell-side by three-dimensional CFD method. The results reveal that comprehensive performance of the reactor with disk-and-doughnut baffles is better than that of with segmental baffles. Finally, the effects of operating conditions to control the hot spots are investigated. The results show that the flow velocity range about 0.65 m/s is applicable and the co-current cooling system flow direction is better than counter-current flow to control the hottest temperature.

Determination of the Removal Efficiency of Linear Alkyl Benzene Sulphonate Acids (LAS in Fixed Bed Aeration Tank and Conventional Activated Sludge

Directory of Open Access Journals (Sweden)

Asghar Ebrahimi

2011-03-01

Full Text Available Linear Alkyl Benzene Sulphonate Acids (LAS are one of the anionic surfactants that are produced and used in large quantities in different countries and find their way into the natural environment through sewer systems. These compounds may potentially cause environmental hazards in such surface waters as rivers. It is, therefore, necessary to remove as much of these compounds as possible by biological processes in wastewater treatment plants. For this purpose, four parallel biological reactors were constructed that used the conventional activated sludge and aeration tanks with fixed bed on the bench scale in order to evaluate the removal efficiency of LAS. The reactors were operated under conditions similar to domestic wastewater treatment plants. Parameters of interest were measured according to standard methods and ANOVA and T-test were used for the statistical analysis of the data. The results showed that aeration tanks with fixed beds yielded higher values of LAS and COD removal and air consumption compared to the conventional activated sludge system. It was shown that the two systems studied achieved LAS removal efficiencies of 96% and 94% for an influent LAS concentration of 5 mg/L. Further, it was found that the effluents from both systems satisfied water quality standards for discharge into surface waters (

Adsorption of phosphate from aqueous solutions and sewage using zirconium loaded okara (ZLO): Fixed-bed column study

International Nuclear Information System (INIS)

Nguyen, T.A.H.; Ngo, H.H.; Guo, W.S.; Pham, T.Q.; Li, F.M.; Nguyen, T.V.; Bui, X.T.

2015-01-01

This study explores the potential of removing phosphorus from aqueous solutions and sewage by Zr(IV)-loaded okara (ZLO) in the fixed-bed column. Soybean residue (okara) was impregnated with 0.25 M Zr(IV) solution to prepare active binding sites for phosphate. The effect of several factors, including flow rate, bed height, initial phosphorus concentration, pH and adsorbent particle size on the performance of ZLO was examined. The maximum dynamic adsorption capacity of ZLO for phosphorus was estimated to be 16.43 mg/g. Breakthrough curve modeling indicated that Adams–Bohart model and Thomas model fitted the experimental data better than Yoon–Nelson model. After treatment with ZLO packed bed column, the effluent could meet the discharge standard for phosphorus in Australia. Successful desorption and regeneration were achieved with 0.2 NaOH and 0.1 HCl, respectively. The results prove that ZLO can be used as a promising phosphorus adsorbent in the dynamic adsorption system. - Highlights: • Dynamic adsorption of P from water and wastewater by Zr(IV)-loaded okara was tested. • Effects of column design parameters on the adsorption performance were investigated. • The dynamic adsorption capacity of Zr(IV)-loaded okara for P was reasonably high. • The spent column was effectively regenerated with 0.2 M NaOH followed by 0.1 M HCl. • Zr(IV)-loaded okara column was efficient in eliminating P from municipal sewage

Adsorption of phosphate from aqueous solutions and sewage using zirconium loaded okara (ZLO): Fixed-bed column study

Energy Technology Data Exchange (ETDEWEB)

Nguyen, T.A.H. [Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology, Sydney (UTS), 15 Broadway, Ultimo, NSW 2007 (Australia); Ngo, H.H., E-mail: ngohuuhao121@gmail.com [Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology, Sydney (UTS), 15 Broadway, Ultimo, NSW 2007 (Australia); Guo, W.S. [Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology, Sydney (UTS), 15 Broadway, Ultimo, NSW 2007 (Australia); Pham, T.Q. [Faculty of Geography, University of Science, Vietnam National University, Hanoi (Viet Nam); Li, F.M. [College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100 (China); Nguyen, T.V. [Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology, Sydney (UTS), 15 Broadway, Ultimo, NSW 2007 (Australia); Bui, X.T. [Environmental Engineering and Management Research Group, Ton Duc Thang University, Ho Chi Minh City (Viet Nam); Faculty of Environment and Natural Resources, Ho Chi Minh City University of Technology-Vietnam National University, Ho Chi Minh City (Viet Nam)

2015-08-01

This study explores the potential of removing phosphorus from aqueous solutions and sewage by Zr(IV)-loaded okara (ZLO) in the fixed-bed column. Soybean residue (okara) was impregnated with 0.25 M Zr(IV) solution to prepare active binding sites for phosphate. The effect of several factors, including flow rate, bed height, initial phosphorus concentration, pH and adsorbent particle size on the performance of ZLO was examined. The maximum dynamic adsorption capacity of ZLO for phosphorus was estimated to be 16.43 mg/g. Breakthrough curve modeling indicated that Adams–Bohart model and Thomas model fitted the experimental data better than Yoon–Nelson model. After treatment with ZLO packed bed column, the effluent could meet the discharge standard for phosphorus in Australia. Successful desorption and regeneration were achieved with 0.2 NaOH and 0.1 HCl, respectively. The results prove that ZLO can be used as a promising phosphorus adsorbent in the dynamic adsorption system. - Highlights: • Dynamic adsorption of P from water and wastewater by Zr(IV)-loaded okara was tested. • Effects of column design parameters on the adsorption performance were investigated. • The dynamic adsorption capacity of Zr(IV)-loaded okara for P was reasonably high. • The spent column was effectively regenerated with 0.2 M NaOH followed by 0.1 M HCl. • Zr(IV)-loaded okara column was efficient in eliminating P from municipal sewage.

Methanol steam-reforming in a catalytic fixed bed reactor

Energy Technology Data Exchange (ETDEWEB)

Duesterwald, H G; Hoehlein, B; Kraut, H; Meusinger, J; Peters, R [Research Centre Juelich (KFA) (Germany). Inst. of Energy Process Engineering; Stimming, U [Technische Univ. Muenchen, Garching (Germany). Inst. fuer Festkoerperphysik und Techn. Phys.

1997-12-01

Designing an appropriate methanol steam reformer requires detailed knowledge about the processes within such a reactor. Thus, the axial temperature and concentration gradients and catalyst ageing were investigated. It was found that for a fresh catalyst load, the catalyst located in the reactor entrance was most active during the experiment. The activity of this part of the catalyst bed decreased after some time of operation due to ageing. With further operation, the most active zone moved through the catalyst bed. From the results concerning hydrogen production and catalyst degradation, the necessary amount of catalyst for a mobile PEMFC-system can be estimated. (orig.)

Anaerobic degradation of dairy wastewater in intermittent UASB reactors: influence of effluent recirculation.

Science.gov (United States)

Couras, C S; Louros, V L; Gameiro, T; Alves, N; Silva, A; Capela, M I; Arroja, L M; Nadais, H

2015-01-01

This work studied the influence of effluent recirculation upon the kinetics of anaerobic degradation of dairy wastewater in the feedless phase of intermittent upflow anaerobic sludge bed (UASB) reactors. Several laboratory-scale tests were performed with different organic loads in closed circuit UASB reactors inoculated with adapted flocculent sludge. The data obtained were used for determination of specific substrate removal rates and specific methane production rates, and adjusted to kinetic models. A high initial substrate removal was observed in all tests due to adsorption of organic matter onto the anaerobic biomass which was not accompanied by biological substrate degradation as measured by methane production. Initial methane production rate was about 45% of initial soluble and colloidal substrate removal rate. This discrepancy between methane production rate and substrate removal rate was observed mainly on the first day of all experiments and was attenuated on the second day, suggesting that the feedless period of intermittent UASB reactors treating dairy wastewater should be longer than one day. Effluent recirculation expressively raised the rate of removal of soluble and colloidal substrate and methane productivity, as compared with results for similar assays in batch reactors without recirculation. The observed bed expansion was due to the biogas production and the application of effluent recirculation led to a sludge bed contraction after all the substrates were degraded. The settleability of the anaerobic sludge improved by the introduction of effluent recirculation this effect being more pronounced for the higher loads.

Characterization, morphology and composition of biofilm and precipitates from a sulphate-reducing fixed-bed reactor

International Nuclear Information System (INIS)

Remoundaki, Emmanouela; Kousi, Pavlina; Joulian, Catherine; Battaglia-Brunet, Fabienne; Hatzikioseyian, Artin; Tsezos, Marios

2008-01-01

The characteristics of the biofilm and the solids formed during the operation of a sulphate-reducing fixed-bed reactor, fed with a moderately acidic synthetic effluent containing zinc and iron, are presented. A diverse population of δ-Proteobacteria SRB, affiliated to four distinct genera, colonized the system. The morphology, mineralogy and surface chemistry of the precipitates were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). The XRD patterns observed are characteristic of amorphous solid phases. Peaks corresponding to crystalline iron sulphide, marcasite, sphalerite and wurtzite were also identified. SEM-EDX results confirm the predominance of amorphous phases appearing as a cloudy haze. EDX spectra of spots on the surface of these amorphous phases reveal the predominance of iron, zinc and sulphur indicating the formation of iron and zinc sulphides. The predominance of these amorphous phases and the formation of very fine particles, during the operation of the SRB column, are in agreement and can be explained by the formation pathways of metal sulphides at ambient temperature, alkaline pH and reducing conditions. Solids are precipitated either as (i) amorphous phases deposited on the bed material, as well as on surface of crystals, e.g. Mg 3 (PO 4 ) 2 and (ii) as rod-shaped solids characterized by a rough hazy surface, indicating the encapsulation of bacterial cells by amorphous metal sulphides

Formation of N{sub 2} during the fixed-bed pyrolysis of coals

Energy Technology Data Exchange (ETDEWEB)

Wu, Zhiheng; Ohtsuka, Yasuo [Tohoku Univ., Sendai (Japan); Furimsky, E. [Natural Resources Canada, Ottawa, Ontario (Canada)

1995-12-31

Research on the fate of the nitrogen in coal during pyrolysis has attracted increased attention, since it is related with the NO{sub x} and N{sub 2}O emissions during subsequent combustion. It has been reported that coal nitrogen is initially released as tar, which is then converted to HCN and NH{sub 3} through secondary decomposition reactions. However, little attention to N{sub 2} has been paid so far. We have recently found that N{sub 2} is the dominant product in slow heating rate pyrolysis of a subbituminous coal, and that the finely dispersed iron catalyst promotes drastically the formation of N{sub 2} from a brown coal. If coal nitrogen can be removed efficiently as N{sub 2} during pyrolysis, this method would contribute to the reduction of the NO{sub x} and N{sub 2}O emissions, since such pollutants originate mostly from coal nitrogen. Therefore the present study aims at making clear the influence of coal type, pyrolysis conditions, demineralization, and iron catalyst on the formation of N{sub 2} during the fix-bed pyrolysis of several coals with different ranks.

Chromate (CrO2-4) Reduction in Groundwaters by Using Reductive Bacteria in Fixed-Bed Bioreactors

International Nuclear Information System (INIS)

Battaglia-Brunet, F.; Foucher, S.; Morin, D.; Ignatiadis, I.

2004-01-01

A biological method for the reduction Cr(VI), using sulphate-reducing bacteria (SRB), was tested in 2-L then 20-L fixed-bed reactors, with H 2 as a low-cost and clean substrate. The systems were inoculated with Desulfomicrobium norvegicum, that proved to be particularly efficient for direct Cr(VI) enzymatic reduction. The bacterial reduction was efficient when some SO 2- 4 was provided in the feeding, in order to allow their growth and to combine the direct enzymatic reduction to the indirect chemical reduction by dissolved H 2 S. The Cr(VI)/SO 2- 4 , ratio in the influent was adjusted in order to avoid excess sulphide production. A real polluted groundwater and an industrial electroplating effluent were treated in the 20-L pilot plant

Anaerobic biological treatment

International Nuclear Information System (INIS)

Speece, R.E.

1990-01-01

The Enso-Fenox process has been very successfully used to remove chlorinated phenolic compounds from pulp bleaching effluents. It is a two-stage anaerobic/aerobic process consisting of a nonmethanogenic anaerobic fluidized bed followed by a trickling filter. Studies have been conducted on reductive dechlorination of chlorinated aromatic compounds under anaerobic conditions with chlorinated phenols as the sole carbon and energy source. Approximately 40% of the added chlorophenols was converted to CH 4 and CO 2 . Substrate loading rates were 20 mg/L/d at hydraulic detention times of 2-4 days with 90% substrate conversion efficiency. Reductive dechlorination of mono, di-, tri-, and pentachlorophenols has been demonstrated in anaerobic sewage sludge. The following constituents were tested in the laboratory at their approximate concentrations in coal conversion wastewater (CCWW) and were anaerobically degraded in serum bottles: 1,000 mg/L phenol; 500 mg/L resorcinol; 1,000 mg/L benzoic acid; 500 mg/L p-cresol; 200 mg/L pyridine; 2,000 mg/L benzoic acid; 250 mg/L 40 methylcatechol; 500 mg/L 4-ethylpyridine; and 2,000 mg/L hexanoic acid. A petrochemical may initially exhibit toxicity to an unacclimated population of methane-fermenting bacteria, but with acclimation the toxicity may be greatly reduced or disappear. In addition, the microorganisms may develop the capacity to actually degrade compounds which showed initial toxicity. Since biomass digestion requires a complete consortium of bacteria, it is relevant to study the effect of a given process as well as to individual steps within the process. A toxicant can inhibit the rate-limiting step and/or change the step that is rate-limiting. Both manifestations of toxicity can severely affect the overall process

Anaerobic wastewater treatment in single-and double-stage digesters; Tratamiento anaerobio de aguas residuales en digestores de simple y doble etapa

Energy Technology Data Exchange (ETDEWEB)

Gomez Lopez, M.; Vazquez Garcia, M. J.; Pena Caamano, P.; Soto Castineira, M. [Universidad da Coruna (Spain)

2000-07-01

Anaerobic treatment are a major alternative in wastewater treatment due to simplicity and lower power requirements, although greater understanding of this process and its technology is needed to make it possible. The most important concepts and parameters developed to treat medium-and high-load effluents are defined and various technologies are discussed, including: anaerobic filter (AF), upflow anaerobic sludge blanket (UASB) reactors, fluidized bed (FB) reactors, expanded granular sludge beds (EGSB). To determine the efficiency in municipal wastewater treatment, a pilot plant was constructed with a UASB reactor, obtaining elimination efficiency values of 60-65% for total COD and 55% for TSS. Finally a comparative chart of aerobic versus anaerobic treatment is provided, high-lighting the major possibilities offered by the latter. (Author) 28 refs.

Zinc deprivation of methanol fed anaerobic granular sludge bioreactors

NARCIS (Netherlands)

Fermoso, F.G.; Collins, G.; Bartacek, J.; Lens, P.N.L.

2008-01-01

The effect of omitting zinc from the influent of mesophilic (30 degrees C) methanol fed upflow anaerobic sludge bed (UASB) reactors, and latter zinc supplementation to the influent to counteract the deprivation, was investigated by coupling the UASB reactor performance to the microbial ecology of

Inactivation of dairy manure-borne pathogens by anaerobic digestion

Science.gov (United States)

Background: Anaerobic digestion of animal manure has the potential to inactivate enteric pathogens, thereby reducing exposures to livestock and humans when the products of digestion are disposed by land-spreading or irrigation or returned to livestock uses such as bedding. Data on digester effectiv...

Biomethanation of salty cheese whey using multichamber anaerobic bioreactor

Energy Technology Data Exchange (ETDEWEB)

Patel, Chirag; Madamwar, Datta [Sardar Patel Univ., Gujarat (India)

1998-07-01

To obtain enriched methane content and improve anaerobic digestion of salty cheese whey after diluting with total dairy waste water, a multichamber anaerobic bioreactor has been developed using different combination of bedding materials in different chambers. Best performance has been obtained at 37''oC under the combination of polystyrene chips, pumice stones and PVC beads as supporting materials, and operating at 2 day hydraulic retention time. Maximum gas production of 3.2 litre/litre of digester/day with methane content of 68% and 83% reduction in COD have been noticed. (Author)

Anaerobic digestion of corn ethanol thin stillage in batch and by high-rate down-flow fixed film reactors.

Science.gov (United States)

Wilkinson, A; Kennedy, K J

2012-01-01

Thin stillage (CTS) from a dry-grind corn ethanol plant was evaluated as a carbon source for anaerobic digestion (AD) by batch and high rate semi-continuous down-flow stationary fixed film (DSFF) reactors. Biochemical methane potential (BMP) assays were carried out with CTS concentrations ranging from approximately 2,460-27,172 mg total chemical oxygen demand (TCOD) per litre, achieved by diluting CTS with clean water or a combination of clean water and treated effluent. High TCOD, SCOD and volatile solids (VS) removal efficiencies of 85 ± 2, 94 ± 0 and 82 ± 1% were achieved for CTS diluted with only clean water at an organic concentration of 21,177 mg TCOD per litre, with a methane yield of 0.30 L methane per gram TCOD(removed) at standard temperature and pressure (STP, 0 °C and 1 atmosphere). Batch studies investigating the use of treated effluent for dilution showed promising results. Continuous studies employed two mesophilic DSFF anaerobic digesters treating thin stillage, operated at hydraulic retention times (HRT) of 20, 14.3, 8.7, 6.3, 5 and 4.2 d. Successful digestion was achieved up to an organic loading rate (OLR) of approximately 7.4 g TCOD L(-1)d(-1) at a 5 d HRT with a yield of 2.05 LCH(4) L(-1)d(-1) (at STP) and TCOD and VS removal efficiencies of 89 ± 3 and 85 ± 3%, respectively.

Anaerobic treatment of domestic wastewater in subtropical regions

NARCIS (Netherlands)

Seghezzo, L.

2004-01-01

In this thesis, the application of upflow anaerobic sludge bed (UASB) reactors for the treatment of low-strength domestic sewage was studied for the city ofSalta

Modeling of convective drying kinetics of Pistachio kernels in a fixed bed drying system

Directory of Open Access Journals (Sweden)

Balbay Asım

2013-01-01

Full Text Available Drying kinetics of Pistachio kernels (PKs with initial moisture content of 32.4% (w.b was investigated as a function of drying conditions in a fixed bed drying system. The drying experiments were carried out at different temperatures of drying air (40, 60 and 80°C and air velocities (0.05, 0.075 and 0.1 m/s. Several experiments were performed in terms of mass of PKs (15g and 30g using a constant air velocity of 0.075 m/s. The fit quality of models was evaluated using the determination coefficient (R2, sum square error (SSE and root mean square error (RMSE. Among the selected models, the Midilli et al model was found to be the best models for describing the drying behavior of PKs. The activation energies were calculated as 29.2 kJ/mol and effective diffusivity values were calculated between 1.38 and 4.94x10-10 m2/s depending on air temperatures.

Anaerobic fluidized bed reactor with expanded clay as support for hydrogen production through dark fermentation of glucose

Energy Technology Data Exchange (ETDEWEB)

Cavalcante de Amorim, Eduardo Lucena [Department of Hydraulic and Sanitation, University of Sao Paulo. Av. Trabalhador Saocarlense, 400 Centro, CEP 13566-590 Sao Carlos, SP (Brazil); Barros, Aruana Rocha; Rissato Zamariolli Damianovic, Marcia Helena; Silva, Edson Luiz [Department of Chemical Engineering, Federal University of Sao Carlos, Rodovia Washington Luis, km 235, CEP 13565-905 Sao Carlos, SP (Brazil)

2009-01-15

This study evaluated hydrogen production in an anaerobic fluidized bed reactor (AFBR) fed with glucose-based synthetic wastewater. Particles of expanded clay (2.8-3.35 mm) were used as a support material for biomass immobilization. The reactor was operated with hydraulic retention times (HRT) ranging from 8 to 1 h. The hydrogen yield production increased from 1.41 to 2.49 mol H{sub 2} mol{sup -1} glucose as HRT decreased from 8 to 2 h. However, when HRT was 1 h, there was a slight decrease to 2.41 mol H{sub 2} mol{sup -1} glucose. The biogas produced was composed of H{sub 2} and CO{sub 2}, and the H{sub 2} content increased from 8% to 35% as HRT decreased. The major soluble metabolites during H{sub 2} fermentation were acetic acid (HAc) and butyric acid (HBu), accounting for 36.1-53.3% and 37.7-44.9% of total soluble metabolites, respectively. Overall, the results demonstrate the potential of using expanded clay as support material for hydrogen production in AFBRs. (author)

Cold adaptation and replicable microbial community development during long-term low-temperature anaerobic digestion treatment of synthetic sewage.

Science.gov (United States)

Keating, C; Hughes, D; Mahony, T; Cysneiros, D; Ijaz, U Z; Smith, C J; O'Flaherty, V

2018-07-01

The development and activity of a cold-adapting microbial community was monitored during low-temperature anaerobic digestion (LtAD) treatment of wastewater. Two replicate hybrid anaerobic sludge bed-fixed-film reactors treated a synthetic sewage wastewater at 12°C, at organic loading rates of 0.25-1.0 kg chemical oxygen demand (COD) m-3 d-1, over 889 days. The inoculum was obtained from a full-scale anaerobic digestion reactor, which was operated at 37°C. Both LtAD reactors readily degraded the influent with COD removal efficiencies regularly exceeding 78% for both the total and soluble COD fractions. The biomass from both reactors was sampled temporally and tested for activity against hydrolytic and methanogenic substrates at 12°C and 37°C. Data indicated that significantly enhanced low-temperature hydrolytic and methanogenic activity developed in both systems. For example, the hydrolysis rate constant (k) at 12°C had increased 20-30-fold by comparison to the inoculum by day 500. Substrate affinity also increased for hydrolytic substrates at low temperature. Next generation sequencing demonstrated that a shift in a community structure occurred over the trial, involving a 1-log-fold change in 25 SEQS (OTU-free approach) from the inoculum. Microbial community structure changes and process performance were replicable in the LtAD reactors.

Effects of disintegration on anaerobic degradation of sewage excess sludge in downflow stationary fixed film digesters.

Science.gov (United States)

Engelhart, M; Krüger, M; Kopp, J; Dichtl, N

2000-01-01

The effects of mechanical disintegration on anaerobic digestibility of sewage excess sludge in downflow stationary fixed film (DSFF) digesters were investigated on laboratory scale. Mechanical pretreatment using a high pressure homogenizer led to significantly enhanced concentrations of soluble proteins and carbohydrates in the feed sludge. Using DSFF digesters with two different tubular plastic media as support material it was shown that a stable digestion process could be achieved at hydraulic retention times (HRT) down to 5 days. Compared to conventional digesters at 10 d and 15 d HRT respectively, the degradation of volatile solids was enhanced up to 25%, also resulting in a higher specific biogas production. Further investigations on degradation of soluble proteins and carbohydrates showed that a slowly degradable fraction of carbohydrates was released via disintegration. Using the distribution of chain length and the concentrations of volatile fatty acids as process parameters, the dependability on the HRT and the degree of disintegration (the release of soluble COD) predominated the effects of specific surface area of the support media.

Application of response surface methodology and semi-mechanistic model to optimize fluoride removal using crushed concrete in a fixed-bed column.

Science.gov (United States)

Gu, Bon-Wun; Lee, Chang-Gu; Park, Seong-Jik

2018-03-01

The aim of this study was to investigate the removal of fluoride from aqueous solutions by using crushed concrete fines as a filter medium under varying conditions of pH 3-7, flow rate of 0.3-0.7 mL/min, and filter depth of 10-20 cm. The performance of fixed-bed columns was evaluated on the basis of the removal ratio (Re), uptake capacity (qe), degree of sorbent used (DoSU), and sorbent usage rate (SUR) obtained from breakthrough curves (BTCs). Three widely used semi-mechanistic models, that is, Bohart-Adams, Thomas, and Yoon-Nelson models, were applied to simulate the BTCs and to derive the design parameters. The Box-Behnken design of response surface methodology (RSM) was used to elucidate the individual and interactive effects of the three operational parameters on the column performance and to optimize these parameters. The results demonstrated that pH is the most important factor in the performance of fluoride removal by a fixed-bed column. The flow rate had a significant negative influence on Re and DoSU, and the effect of filter depth was observed only in the regression model for DoSU. Statistical analysis indicated that the model attained from the RSM study is suitable for describing the semi-mechanistic model parameters.

Effect of small-scale biomass gasification at the state of refractory lining the fixed bed reactor

Energy Technology Data Exchange (ETDEWEB)

Janša, Jan, E-mail: jan.jansa@vsb.cz; Peer, Vaclav, E-mail: vaclav.peer@vsb.cz; Pavloková, Petra, E-mail: petra.pavlokova@vsb.cz [VŠB – Technical University of Ostrava, Energy Research Center, 708 33 Ostrava (Czech Republic)

2016-06-30

The article deals with the influence of biomass gasification on the condition of the refractory lining of a fixed bed reactor. The refractory lining of the gasifier is one part of the device, which significantly affects the operational reliability and durability. After removing the refractory lining of the gasifier from the experimental reactor, there was done an assessment how gasification of different kinds of biomass reflected on its condition in terms of the main factors affecting its life. Gasification of biomass is reflected on the lining, especially through sticking at the bottom of the reactor. Measures for prolonging the life of lining consist in the reduction of temperature in the reactor, in this case, in order to avoid ash fusion biomass which it is difficult for this type of gasifier.

Anaerobic soil disinfestation for controlling Fusarium wilt in strawberies

Science.gov (United States)

A strategy to apply a high rate of carbon resource in the conduct of a fall bed anaerobic soil disinfestation (ASD) treatment did not provide effective control of Fusarium wilt in California strawberries. The lack of disease control efficacy resulted from an increase in soil populations of the caus...

Discussion of the applicability of overdammed fixed-bed reactors in nitrification processes; Beitrag zum Einsatz von ueberstauten Festbettreaktoren zur Nitrifikation

Energy Technology Data Exchange (ETDEWEB)

Guenter, H.O.

1996-12-31

The investigation aimed at developing a dimensioning method for overdammed fixed bed nitrification reactors with plug flow which takes account of the reactor height. Further, information was to be obtained for assessing sudden loads and for comparing energy consumption with the data of conventional activated sludge plants. (orig./SR) [Deutsch] Ziel dieser Arbeit ist es, fuer ueberstaute, pfropfendurchstroemte Festbettreaktoren zur Nitrifikation einen Bemessungsansatz aufzustellen, welcher den Einfluss der Reaktorhoehe mit beruecksichtigt. Ferner sollten Erkenntnisse zur Beurteilung von Stossbelastungen sowie zum Energiebedarf im Vergleich zu herkoemmlichen Belebungsanlagen gewonnen werden. (orig./SR)

Continuous adsorption of Pb(II) and methylene blue by engineered graphite oxide coated sand in fixed-bed column

Energy Technology Data Exchange (ETDEWEB)

Gong, Ji-Lai, E-mail: jilaigong@gmail.com [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Zhang, Yong-Liang; Jiang, Yan [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Zeng, Guang-Ming, E-mail: zgming@hnu.edu.cn [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Cui, Zhi-Hui; Liu, Ke; Deng, Can-Hui; Niu, Qiu-Ya; Deng, Jiu-Hua [College of Environmental Science and Engineering, Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education, Hunan University, Changsha 410082 (China); Huan, Shuang-Yan [State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

2015-03-01

Highlights: • GO-sand was prepared by coating GO on the surface of sand. • Pb(II) and MB were efficiently removed by GO-sand filter in column. • The removal of MB was enhanced with the presence of Pb(II). • GO-sand is low-cost and convenient for its application as packed bed filter. - Abstract: The mixture of several effluents, caused by the improper handling and management of effluents, generated multi-component wastewater containing both metals and dyes, leading to the complicated treatment process. In this study, a continuous adsorption of Pb(II) and methylene blue (MB) has been studied in single and binary solutions by using graphite oxide coated sand (GO-sand) as an adsorbent in a fixed-bed column. GO-sand was analyzed by X-ray photoelectron spectroscopy before and after analyte adsorption. Compared with sand filter, adsorption quantity and capacity for Pb(II) and MB by GO-sand filter were greatly increased. In Pb(II) and MB single solutions, the experimental parameters were investigated in detail including initial concentration, flow rate, bed depth and pH. Exhaustion time decreased with increasing initial concentration and flow rate, and increased with increasing bed depth and pH. In the Pb(II)-MB binary solution, exhaustion time significantly decreased for Pb(II) adsorption, but increased for MB adsorption. The reason was explained that the more favorable adsorption for MB onto the surface of GO-sand than that for Pb(II), which was derived from π–π interaction between MB and GO on sand surface in packed filter. The Yoon–Nelson model was applied at different concentration of Pb(II) and MB to predict the breakthrough curves. The experimental data were well fit with the model indicating that it was suitable for this column design.

Synthesis of zeolites coal ash in surfactant modified in application and removal of orange 8 acid solution: study in batch, fixed bed column and evaluation ecotoxicological

International Nuclear Information System (INIS)

Magdalena, Carina Pitwak

2015-01-01

In this study, synthesized zeolitic material from coal ash and modified cationic surfactant was used for removing the acid dye Orange 8 (AL8) by adsorption process using moving bed and fixed-bed column. The raw material and adsorbents were characterized by different techniques, such as X-ray diffraction, X-ray fluorescence spectroscopy, among others. The adsorption of AL8 was performed by moving bed in order to optimize the results when they are launched in a fixed bed. The effects of adsorption on zeolite AL8 were compared: (1) Effect of counterions Br - and Cl - surfactant used in the modification of the zeolite; (2) effect of type of coal ash used as raw material in the synthesis of zeolites (fly and bottom). The following adsorbents were used in the study: fly and bottom zeolite modified by surfactant hexadecyltrimethylammonium bromide (ZLMS-Br-Br and ZPMS-Br) and fly zeolite modified by surfactant hexadecyltrimethylammonium chloride (ZLMS-Cl). The pseudo-second-order kinetic described the adsorption of the dye on all adsorbents. The equilibrium time was reached 40, 60 and 120 min for ZLMS-Br, ZLMS-Cl and ZPMS-Br, respectively. The adsorption equilibrium was analyzed by the equations of the models of linear and nonlinear isotherms of Langmuir, Freundlich, Temkin and Dubinin- Radushkevivh (DR) and the criterion of best fit was evaluated using the error functions.The DR model was adjusted better to the experimental data for the system AL8 / ZLMS-Br, the Freundlich model for AL8 / ZLMS-Cl and Langmuir for AL8 / ZPMS. According to the Langmuir maximum adsorption capacity was 4.67, 1.48 and 1.38 mg g -1 for ZLMS-Br, ZLMS-Cl and ZPMS-Br, in order. In studies employing fixed bed columns, the effects of inlet concentration (20- 30 mg L -1 ), flow rate (4.0 -5.3 mL min -1 ) and the bed height (5, 5 - 6.5 cm) above the breakthrough curves characteristics in the adsorption system were determined. The Adams-Bohart, Thomas, Yoon-Nelson models were applied to experimental

Absorption of CO2 and H2S in Aqueous Alkanolamine Solutions using a Fixed-Bed Reactor with Cocurrent Downflow Operation in the Pulsing Flow Regime

NARCIS (Netherlands)

Versteeg, G.F.; Swaaij, W.P.M. van

1988-01-01

Absorption rates of H2S and CO2 in several aqueous alkanolamines in a cocurrent downflow fixed-bed reactor operated in the pulse flow regime have been measured in order to obtain information on the potential selectivity and on the mass transfer parameters. From these experiments it can be concluded

Evolution of Molybdenum Nitrogenase during the Transition from Anaerobic to Aerobic Metabolism

Science.gov (United States)

Boyd, Eric S.; Costas, Amaya M. Garcia; Hamilton, Trinity L.; Mus, Florence

2015-01-01

ABSTRACT Molybdenum nitrogenase (Nif), which catalyzes the reduction of dinitrogen to ammonium, has modulated the availability of fixed nitrogen in the biosphere since early in Earth's history. Phylogenetic evidence indicates that oxygen (O2)-sensitive Nif emerged in an anaerobic archaeon and later diversified into an aerobic bacterium. Aerobic bacteria that fix N2 have adapted a number of strategies to protect Nif from inactivation by O2, including spatial and temporal segregation of Nif from O2 and respiratory consumption of O2. Here we report the complement of Nif-encoding genes in 189 diazotrophic genomes. We show that the evolution of Nif during the transition from anaerobic to aerobic metabolism was accompanied by both gene recruitment and loss, resulting in a substantial increase in the number of nif genes. While the observed increase in the number of nif genes and their phylogenetic distribution are strongly correlated with adaptation to utilize O2 in metabolism, the increase is not correlated with any of the known O2 protection mechanisms. Rather, gene recruitment appears to have been in response to selective pressure to optimize Nif synthesis to meet fixed N demands associated with aerobic productivity and to more efficiently regulate Nif under oxic conditions that favor protein turnover. Consistent with this hypothesis, the transition of Nif from anoxic to oxic environments is associated with a shift from posttranslational regulation in anaerobes to transcriptional regulation in obligate aerobes and facultative anaerobes. Given that fixed nitrogen typically limits ecosystem productivity, our observations further underscore the dynamic interplay between the evolution of Earth's oxygen, nitrogen, and carbon biogeochemical cycles. IMPORTANCE Molybdenum nitrogenase (Nif), which catalyzes the reduction of dinitrogen to ammonium, has modulated the availability of fixed nitrogen in the biosphere since early in Earth's history. Nif emerged in an anaerobe and

Evolution of molybdenum nitrogenase during the transition from anaerobic to aerobic metabolism.

Science.gov (United States)

Boyd, Eric S; Costas, Amaya M Garcia; Hamilton, Trinity L; Mus, Florence; Peters, John W

2015-05-01

Molybdenum nitrogenase (Nif), which catalyzes the reduction of dinitrogen to ammonium, has modulated the availability of fixed nitrogen in the biosphere since early in Earth's history. Phylogenetic evidence indicates that oxygen (O2)-sensitive Nif emerged in an anaerobic archaeon and later diversified into an aerobic bacterium. Aerobic bacteria that fix N2 have adapted a number of strategies to protect Nif from inactivation by O2, including spatial and temporal segregation of Nif from O2 and respiratory consumption of O2. Here we report the complement of Nif-encoding genes in 189 diazotrophic genomes. We show that the evolution of Nif during the transition from anaerobic to aerobic metabolism was accompanied by both gene recruitment and loss, resulting in a substantial increase in the number of nif genes. While the observed increase in the number of nif genes and their phylogenetic distribution are strongly correlated with adaptation to utilize O2 in metabolism, the increase is not correlated with any of the known O2 protection mechanisms. Rather, gene recruitment appears to have been in response to selective pressure to optimize Nif synthesis to meet fixed N demands associated with aerobic productivity and to more efficiently regulate Nif under oxic conditions that favor protein turnover. Consistent with this hypothesis, the transition of Nif from anoxic to oxic environments is associated with a shift from posttranslational regulation in anaerobes to transcriptional regulation in obligate aerobes and facultative anaerobes. Given that fixed nitrogen typically limits ecosystem productivity, our observations further underscore the dynamic interplay between the evolution of Earth's oxygen, nitrogen, and carbon biogeochemical cycles. Molybdenum nitrogenase (Nif), which catalyzes the reduction of dinitrogen to ammonium, has modulated the availability of fixed nitrogen in the biosphere since early in Earth's history. Nif emerged in an anaerobe and later diversified into

Syntrophomonas zehnderi sp. nov., an anaerobe that degrades long chain fatty acids in co-culture with Methanobacterium formicicum

NARCIS (Netherlands)

Sousa, D.Z.; Smidt, H.; Alves, M.M.; Stams, A.J.M.

2007-01-01

An anaerobic, mesophilic, syntrophic fatty-acid-oxidizing bacterium, designated strain OL-4T, was isolated as a co-culture with Methanobacterium formicicum DSM 1535NT from an anaerobic expanded granular sludge bed reactor used to treat an oleate-based effluent. Strain OL-4T degraded oleate, a

Passive deca-heat removal in the fixed bed nuclear reactor (FBNR) - 15551

International Nuclear Information System (INIS)

Solano Diaz, E.C.; Luna Aguilera, G.M.; Santos, R.A.; Vaca, D.E.

2015-01-01

The Fixed Bed Nuclear Reactor (FBNR) is a Generation IV small reactor concept, where the spherical elements contain Triso-type microspheres with UO 2 , which serves as nuclear fuel. In the event that adverse operation conditions occur, the water pump is automatically shut off and the fuel pebbles fall back by gravity into the fuel chamber. Since the FBNR relies on passive security systems, the removal of the decay heat in the fuel chamber is achieved by contact with quiescent water. In the present paper, a mathematical simulation of the passive cooling of the system was conducted in SOLIDWORKS so as to obtain a temperature profile in the body during the decay heat removal process. Homogenization techniques were employed to smooth out spatial variations across the multiphase system and to derive expression for the effective thermophysical properties that are valid through the macroscopic entry (the chamber). The simulation showed that the chamber's temperature rose from 573 K to its maximum temperature, 1234 K, in the first hour. Afterwards, the temperature fluctuated, but stayed under 552 K. Since the temperature of the system was always kept under the value of the safety parameter (1200 C. degrees) the simulation confirmed that an effective passive cooling of the fuel chamber is indeed feasible. (authors)

Anaerobic columnar denitrification of high nitrate wastewater

International Nuclear Information System (INIS)

Francis, C.W.; Malone, C.D.

1975-01-01

Anaerobic columns were used to test the effectiveness of biological denitrification of nitrate solutions ranging in concentration from 1 to 10 kg NO 3 /m 3 . Several sources of nitrate (Ca(CNO 3 ) 2 , NaNO 3 , NH 4 NO 3 , and actual nitrate wastes from a UO 2 fuel fabrication plant) were evaluated as well as two packing media. The packing media were anthracite coal particles, whose effective diameter size ranged between 2 and 3 mm, and polypropylene Raschig rings 1.6 x 1.6 diameter. The anthracite coal proved to be the better packing media as excessive hydraulic short circuiting occurred in a 120 x 15 cm diameter glass column packed with the polypropylene rings after 40 days operation. With anthracite coal, floatation of the bed occurred at flow rates greater than 0.80 cm 3 /s. Tapered columns packed with anthracite coal eliminated the floatation problem, even at flow rates as high as 5 cm 3 /s. Under optimum operating conditions the anthracite coal behaved as a fluidized bed. Maximum denitrification rates were 1.0--1.4 g NO 3 /m 3 /s based on initial bed volume. Denitrification kinetics indicated that rates of denitrification became substrate inhibited at nitrate concentrations greater than 6.5 kg NO 3 /m 3 Anaerobic columns packed with anthracite coal appear to be an effective method of nitrate disposal for nitrate rich wastewater generated at UO 2 fuel fabrication plants and fuel reprocessing facilities. (U.S.)

Scaled-up electrochemical reactor with a fixed bed three-dimensional cathode for electro-Fenton process: Application to the treatment of bisphenol A

International Nuclear Information System (INIS)

Chmayssem, Ayman; Taha, Samir; Hauchard, Didier

2017-01-01

In this study, we report on the development of an open undivided electrochemical reactor with a compact fixed bed of glassy carbon pellets as three-dimensional cathode for the application of electro-Fenton process. Bisphenol A (BPA) was chosen as model molecule in order to improve its efficiency to the treatment of persistent pollutants. The study of the BPA removal efficiency in function of the applied current intensity was investigated in order to determine the limiting current of O 2 reduction (optimal conditions of H 2 O 2 production at flow rate of 0.36 m 3 .h −1 ) which was 0.8 A (0.5 A/100 g of glassy carbon pellets). Many parameters have been carried out using this electro-Fenton reactor namely degradation kinetics, influence of anodic reactions on DSA, effect of initial pollutant concentration. In the optimal current condition, the global production rate of H 2 O 2 and ·OH was investigated. The yield of electro-Fenton reaction (conversion of H 2 O 2 to ·OH) was very high (> 90%). The absolute rate of BPA degradation was determined as 4.3 × 10 9 M −1 s −1 . COD, TOC and BOD 5 measurements indicated that only few minutes of treatment by electro-Fenton process were needed to eliminate BPA for dilute solutions (10 and 25 mg.L −1 ). In this case, the biodegradability of the treated solutions occurred rapidly. For higher concentration levels, an efficient removal of BPA appeared for treatment time higher than 1 hour and more than 90 minutes were necessary to obtain the biodegradability of BPA solutions. In optimum conditions, the scale-up of the electrochemical reactor applied to electro-Fenton process was suggested and depended on the concentration level of the pollutant. The operating parameters of the scaled-up reactor might be deduced from the new section of each fixed bed exposed to the flow, from values of liquid flow velocity and from the corresponding limiting current density obtained with the reactor at laboratory scale. The compact fixed bed

Treatment of grain distillation wastewaters in an upflow anaerobic ...

African Journals Online (AJOL)

In operation of the full-scale upflow anaerobic sludge bed (UASB) system at the Stellenbosch Farmers' Winery (SFW) Wellington distillery, a problem encountered in the treatment of grain distillation wastewater was the accumulation of a floating scum layer. On occasion this was so severe that it forced shutdown of the UASB ...

An integrated anaerobic digestion and UV photocatalytic treatment of distillery wastewater

Energy Technology Data Exchange (ETDEWEB)

Apollo, Seth [Department of Chemical Engineering, Vaal University of Technology, Private Bag X021, Vanderbijlpark 1900 (South Africa); Onyango, Maurice S. [Department of Chemical and Metallurgical Engineering, Tshwane University of Technology, Pretoria, Private Bag X680, Pretoria 0001 (South Africa); Ochieng, Aoyi, E-mail: ochienga@vut.ac.za [Department of Chemical Engineering, Vaal University of Technology, Private Bag X021, Vanderbijlpark 1900 (South Africa)

2013-10-15

Highlights: • Integrated AD and photodegradation is suitable for treatment of distillery effluent. • AD process is effective in COD and BOD reduction but not colour removal. • UV photodegradation is efficient in colour and DON removal. • UV photodegradation as a post treatment technique achieved high efficiencies. • UV pre-treatment inhibited biogas production in the succeeding anaerobic process. -- Abstract: Anaerobic up-flow fixed bed reactor and annular photocatalytic reactor were used to study the efficiency of integrated anaerobic digestion (AD) and ultraviolet (UV) photodegradation of real distillery effluent and raw molasses wastewater (MWW). It was found that UV photodegradation as a stand-alone technique achieved colour removal of 54% and 69% for the distillery and MWW, respectively, with a COD reduction of <20% and a negligible BOD reduction. On the other hand, AD as a single treatment technique was found to be effective in COD and BOD reduction with efficiencies of above 75% and 85%, respectively, for both wastewater samples. However, the AD achieved low colour removal efficiency, with an increase in colour intensity of 13% recorded when treating MWW while a colour removal of 51% was achieved for the distillery effluent. The application of UV photodegradation as a pre-treatment method to the AD process reduced the COD removal and biogas production efficiency. However, an integration in which UV photodegradation was employed as a post-treatment to the AD process achieved high COD removal of above 85% for both wastewater samples, and colour removal of 88% for the distillery effluent. Thus, photodegradation can be employed as a post-treatment technique to an AD system treating distillery effluent for complete removal of the biorecalcitrant and colour imparting compounds.

An integrated anaerobic digestion and UV photocatalytic treatment of distillery wastewater

International Nuclear Information System (INIS)

Apollo, Seth; Onyango, Maurice S.; Ochieng, Aoyi

2013-01-01

Highlights: • Integrated AD and photodegradation is suitable for treatment of distillery effluent. • AD process is effective in COD and BOD reduction but not colour removal. • UV photodegradation is efficient in colour and DON removal. • UV photodegradation as a post treatment technique achieved high efficiencies. • UV pre-treatment inhibited biogas production in the succeeding anaerobic process. -- Abstract: Anaerobic up-flow fixed bed reactor and annular photocatalytic reactor were used to study the efficiency of integrated anaerobic digestion (AD) and ultraviolet (UV) photodegradation of real distillery effluent and raw molasses wastewater (MWW). It was found that UV photodegradation as a stand-alone technique achieved colour removal of 54% and 69% for the distillery and MWW, respectively, with a COD reduction of <20% and a negligible BOD reduction. On the other hand, AD as a single treatment technique was found to be effective in COD and BOD reduction with efficiencies of above 75% and 85%, respectively, for both wastewater samples. However, the AD achieved low colour removal efficiency, with an increase in colour intensity of 13% recorded when treating MWW while a colour removal of 51% was achieved for the distillery effluent. The application of UV photodegradation as a pre-treatment method to the AD process reduced the COD removal and biogas production efficiency. However, an integration in which UV photodegradation was employed as a post-treatment to the AD process achieved high COD removal of above 85% for both wastewater samples, and colour removal of 88% for the distillery effluent. Thus, photodegradation can be employed as a post-treatment technique to an AD system treating distillery effluent for complete removal of the biorecalcitrant and colour imparting compounds

Efficient expansion of mesenchymal stromal cells in a disposable fixed bed culture system.

Science.gov (United States)

Mizukami, Amanda; Orellana, Maristela D; Caruso, Sâmia R; de Lima Prata, Karen; Covas, Dimas T; Swiech, Kamilla

2013-01-01

The need for efficient and reliable technologies for clinical-scale expansion of mesenchymal stromal cells (MSC) has led to the use of disposable bioreactors and culture systems. Here, we evaluate the expansion of cord blood-derived MSC in a disposable fixed bed culture system. Starting from an initial cell density of 6.0 × 10(7) cells, after 7 days of culture, it was possible to produce of 4.2(±0.8) × 10(8) cells, which represents a fold increase of 7.0 (±1.4). After enzymatic retrieval from Fibra-Cell disks, the cells were able to maintain their potential for differentiation into adipocytes and osteocytes and were positive for many markers common to MSC (CD73, CD90, and CD105). The results obtained in this study demonstrate that MSC can be efficiently expanded in the culture system. This novel approach presents several advantages over the current expansion systems, based on culture flasks or microcarrier-based spinner flasks and represents a key element for MSC cellular therapy according to GMP compliant clinical-scale production system. Copyright © 2013 American Institute of Chemical Engineers.

Co-pyrolysis of corn cob and waste cooking oil in a fixed bed.

Science.gov (United States)

Chen, Guanyi; Liu, Cong; Ma, Wenchao; Zhang, Xiaoxiong; Li, Yanbin; Yan, Beibei; Zhou, Weihong

2014-08-01

Corn cob (CC) and waste cooking oil (WCO) were co-pyrolyzed in a fixed bed. The effects of various temperatures of 500 °C, 550 °C, 600 °C and CC/WCO mass ratios of 1:0, 1:0.1, 1:0.5, 1:1 and 0:1 were investigated, respectively. Results show that co-pyrolysis of CC/WCO produce more liquid and less bio-char than pyrolysis of CC individually. Bio-oil and bio-char yields were found to be largely dependent on temperature and CC/WCO ratios. GC/MS of bio-oil show it consists of different classes and amounts of organic compounds other than that from CC pyrolysis. Temperature of 550 °C and CC/WCO ratio of 1:1 seem to be the optimum considering high bio-oil yields (68.6 wt.%) and good bio-oil properties (HHV of 32.78 MJ/kg). In this case, bio-char of 24.96 MJ/kg appears attractive as a renewable source, while gas with LHV of 16.06 MJ/Nm(3) can be directly used in boilers as fuel. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fixed-bed column studies of total organic carbon removal from industrial wastewater by use of diatomite decorated with polyethylenimine-functionalized pyroxene nanoparticles.

Science.gov (United States)

Hethnawi, Afif; Manasrah, Abdallah D; Vitale, Gerardo; Nassar, Nashaat N

2018-03-01

In this study, a fixed-bed column adsorption process was employed to remove organic pollutants from a real industrial wastewater effluent using polyethylenimine-functionalized pyroxene nanoparticles (PEI-PY) embedded into Diatomite at very low mass percentage. Various dynamic parameters (e.g., inlet concentration, inlet flow rate, bed height, and PEI-nanoparticle concentration in Diatomite, (%nps)) were investigated to determine the breakthrough behavior. The obtained breakthrough curves were fit with a convection-dispersion model to determine the characteristic parameters based on mass transfer phenomena. The axial dispersion coefficient (D L ) and group of dimensionless numbers; including Renold number (Re), Schmidt number (Sc), and Sherwood number (Sh) were all determined and correlated by Wilson-Geankoplis correlation that was used to estimate the external film diffusion coefficients (Kc) at 0.0015 < Re<55. Copyright © 2017 Elsevier Inc. All rights reserved.

Synthesis of biodiesel from waste cooking oil using immobilized lipase in fixed bed reactor

Energy Technology Data Exchange (ETDEWEB)

Chen Yingming [School of Environment and Urban Construction, Wuhan University of Science and Engineering, Wuhan 430073 (China); Guangzhou Institute of Energy Conversion, Chinese Academy of Science, Guangzhou 510640 (China); Xiao Bo [School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Chang Jie [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China)], E-mail: changjie@scut.edu.cn; Fu Yan [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China); Lv Pengmei; Wang Xuewei [Guangzhou Institute of Energy Conversion, Chinese Academy of Science, Guangzhou 510640 (China)

2009-03-15

Waste cooking oil (WCO) is the residue from the kitchen, restaurants, food factories and even human and animal waste which not only harm people's health but also causes environmental pollution. The production of biodiesel from waste cooking oil to partially substitute petroleum diesel is one of the measures for solving the twin problems of environment pollution and energy shortage. In this project, synthesis of biodiesel was catalyzed by immobilized Candida lipase in a three-step fixed bed reactor. The reaction solution was a mixture of WCO, water, methanol and solvent (hexane). The main product was biodiesel consisted of fatty acid methyl ester (FAME), of which methyl oleate was the main component. Effects of lipase, solvent, water, and temperature and flow of the reaction mixture on the synthesis of biodiesel were analyzed. The results indicate that a 91.08% of FAME can be achieved in the end product under optimum conditions. Most of the chemical and physical characters of the biodiesel were superior to the standards for 0 diesel (GB/T 19147) and biodiesel (DIN V51606 and ASTM D-6751)

Synthesis of biodiesel from waste cooking oil using immobilized lipase in fixed bed reactor

Energy Technology Data Exchange (ETDEWEB)

Chen, Yingming [School of Environment and Urban Construction, Wuhan University of Science and Engineering, Wuhan 430073 (China)]|[Guangzhou Institute of Energy Conversion, Chinese Academy of Science, Guangzhou 510640 (China); Xiao, Bo [School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Chang, Jie; Fu, Yan [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641 (China); Lv, Pengmei; Wang, Xuewei [Guangzhou Institute of Energy Conversion, Chinese Academy of Science, Guangzhou 510640 (China)

2009-03-15

Waste cooking oil (WCO) is the residue from the kitchen, restaurants, food factories and even human and animal waste which not only harm people's health but also causes environmental pollution. The production of biodiesel from waste cooking oil to partially substitute petroleum diesel is one of the measures for solving the twin problems of environment pollution and energy shortage. In this project, synthesis of biodiesel was catalyzed by immobilized Candida lipase in a three-step fixed bed reactor. The reaction solution was a mixture of WCO, water, methanol and solvent (hexane). The main product was biodiesel consisted of fatty acid methyl ester (FAME), of which methyl oleate was the main component. Effects of lipase, solvent, water, and temperature and flow of the reaction mixture on the synthesis of biodiesel were analyzed. The results indicate that a 91.08% of FAME can be achieved in the end product under optimum conditions. Most of the chemical and physical characters of the biodiesel were superior to the standards for 0diesel (GB/T 19147) and biodiesel (DIN V51606 and ASTM D-6751). (author)

Synthesis of biodiesel from waste cooking oil using immobilized lipase in fixed bed reactor

International Nuclear Information System (INIS)

Chen Yingming; Xiao Bo; Chang Jie; Fu Yan; Lv Pengmei; Wang Xuewei

2009-01-01

Waste cooking oil (WCO) is the residue from the kitchen, restaurants, food factories and even human and animal waste which not only harm people's health but also causes environmental pollution. The production of biodiesel from waste cooking oil to partially substitute petroleum diesel is one of the measures for solving the twin problems of environment pollution and energy shortage. In this project, synthesis of biodiesel was catalyzed by immobilized Candida lipase in a three-step fixed bed reactor. The reaction solution was a mixture of WCO, water, methanol and solvent (hexane). The main product was biodiesel consisted of fatty acid methyl ester (FAME), of which methyl oleate was the main component. Effects of lipase, solvent, water, and temperature and flow of the reaction mixture on the synthesis of biodiesel were analyzed. The results indicate that a 91.08% of FAME can be achieved in the end product under optimum conditions. Most of the chemical and physical characters of the biodiesel were superior to the standards for 0 diesel (GB/T 19147) and biodiesel (DIN V51606 and ASTM D-6751)

Effects of high salinity wastewater on methanogenic sludge bed systems

NARCIS (Netherlands)

Ismail, S.; Gonzalez-Contreras, P.A.; Jeison, D.A.; Lier, van J.B.

2008-01-01

The attainable loading potentials of anaerobic sludge bed systems are strongly dependent on the growth of granular biomass with a particular wastewater. Experiments were conducted to determine the effects of high salinity wastewater on the biological and physical properties of methanogenic sludge.

CFD analysis of hot spot formation through a fixed bed reactor of Fischer-Tropsch synthesis

Directory of Open Access Journals (Sweden)

Hamed Aligolzadeh

2015-12-01

Full Text Available One of the interesting methods for conversion of synthesis gas to heavy hydrocarbons is Fischer–Tropsch process. The process has some bottlenecks, such as hot spot formation and low degree of conversion. In this work, computational fluid dynamics technique was used to simulate conversion of synthetic gas and product distribution. Also, hot spot formation in the catalytic fixed-bed reactor was investigated in several runs. Simulation results indicated that hot spot formation occurred more likely in the early and middle part of reactor due to high reaction rates. Based on the simulation results, the temperature of hot spots increased with increase in the inlet temperature as well as pressure. Among the many CFD runs conducted, it is found that the optimal temperature and pressure for Fischer–Tropsch synthesis are 565 K and 20 bar, respectively. As it seems that the reactor shall work very well under optimal conditions, the reaction rates and catalyst duration would simultaneously be maximum .

Anaerobic methanethiol degradation and methanogenic community analysis in an alkaline (pH 10) biological process for liquefied petroleum gas desulfurization

NARCIS (Netherlands)

Leerdam, van R.C.; Bonilla-Salinas, M.; Bok, de F.A.M.; Bruning, H.; Lens, P.N.L.; Stams, A.J.M.; Janssen, A.J.H.

2008-01-01

Anaerobic methanethiol (MT) degradation by mesophilic (30 degrees C) alkaliphilic (pH 10) communities was studied in a lab-scale Upflow Anaerobic Sludge Bed (UASB) reactor inoculated with a mixture of sediments from the Wadden Sea (The Netherlands), Soap Lake (Central Washington), and Russian soda

Propene and l-octene hydroformylation with silica-supported, ionic liquid-phase (SILP) Rh-phosphine catalysts in continuous fixed-bed mode

DEFF Research Database (Denmark)

Riisager, Anders; Eriksen, Kim Michael; Wasserscheid, Peter

2003-01-01

- and liquid-phase hydroformylation of propene and 1-octene, exhibiting TOFs up to 88 h(-1) for SILP Rh-2 catalysts, while only low selectivities up to 74% n-aldehyde (n/iso ratio of 2.8) were obtained. This is the first example of continuous fixed-bed liquid-phase hydroformylation using SILP catalysts.......Supported ionic liquid-phase (SILP) catalysts were made by immobilizing Rh-monophosphine complexes of bis(m-phenylguanidinium) phenylphosphine 1 and NORBOS 2 ligands in 1-n-butyl-3-methylimidazolium hexafluorophosphate, [BMIM] [PF6], on a silica support. The catalysts were active in continuous gas...

In situ magnetic resonance measurement of conversion, hydrodynamics and mass transfer during single- and two-phase flow in fixed-bed reactors.

Science.gov (United States)

Gladden, L F; Alexander, P; Britton, M M; Mantle, M D; Sederman, A J; Yuen, E H L

2003-01-01

In recent years there has been increasing interest in applying magnetic resonance (MR) techniques in areas of engineering and chemical technology. The science that underpins many of these applications is the physics and chemistry of transport and reaction processes in porous materials. Key to the exploitation of MR methods will be our ability to demonstrate that MR yields information that cannot be obtained using conventional measurement techniques in engineering research. This article describes two case studies that highlight the power of MR to give new insights to chemical engineers. First, we demonstrate the application of MR techniques to explore both mass transfer and chemical conversion in situ within a fixed bed of catalyst, and we then use these data to identify the rate-controlling step of the chemical conversion. Second, we implement a rapid imaging technique to study the stability of the gas-liquid distribution in the low- and high-interaction two-phase flow regimes in a trickle-bed reactor.

Design, fabrication and initial evaluation of an upflow fixed-bed adsorption column for lead (Pb2+) using Carica papaya seeds

International Nuclear Information System (INIS)

Piquero, Ronald E.

2005-03-01

The study is about the adsorption pf lead (Pb 2+ ) using Carica papaya as biosorbent in an upflow continuous fixed-bed adsorption column. A column was designed and fabricated which was used in the experiment. It aimed to determine the effect of flowrates in the adsorption mechanism of the biosorbent. Three flowrates were used in the experiment: 100 mL/min, 150 mL/min, and 200 mL/min. A solution of 100 ppm of unbuffered lead was allowed to pass through a bed of biosorbent that has a length of 15 cm and the amount of lead ions was measured using flame atomic absorption spectroscopy in terms of residual concentration of lead in the outlet stream. The result showed that the 100 mL/min flowrate had the lowest amount of residual concentration measured compared to the 150 mL/min and 200 mL/min. This means that the 100 mL/min had the most lead ions adsorbed. Statistical test like the one-factor anova and t-test were also done in the research. Anova result showed that the flowrate has significant effect in the adsorption of lead ions of the biosorbent while the t-test results showed that the 100 ml/min is the most effective flowrate wherein the bed had adsorbed the most amounts of ions. (Author)

Treatment of pig excreta using an SCFBR anaerobic reactor

Directory of Open Access Journals (Sweden)

Kevin G. Molina T.

1999-01-01

Full Text Available A new anaerobic reactor called the Sludge Central Fixed Bed Reactor (SCFBR was built and evaluated for the treatment of liquid residue from the pig farms. The SCFBR has three main parts. The lower area is for sludge, the middle part consists of a concentrically packed zone and an upper area for the separation of solids, liquids and gases. The 28.51 SCFBR reactor was evaluated over a period of 210 days, using three organic loads of 0.548,0.421 and 1.239 g COD/1 day. Initially, the reactor was fed non-continuously using 10 and 10.7 days Hydraulic Retention Times (HRT. The HRT was later decreased to 3.87 days using continuous feeding. For the three 0.548, 0.421 and 1.239 g COD/1 day organic loads, Chemical Oxygen Demand (COD removal was 68%, 81% and 73% respectively and Volatile Solids (VS removal was 53.5%, 55.8% and 50.1% respectively. The SCFBR performed well, as shown by the removal efficiency and stability obtained. A microphotograph of sludge from the lower zone is presented, showing high Methanosaeta (Methanothrix presence.

Neural fuzzy modelization of copper removal from water by biosorption in fixed-bed columns using olive stone and pinion shell.

Science.gov (United States)

Calero, M; Iáñez-Rodríguez, I; Pérez, A; Martín-Lara, M A; Blázquez, G

2018-03-01

Continuous copper biosorption in fixed-bed column by olive stone and pinion shell was studied. The effect of three operational parameters was analyzed: feed flow rate (2-6 ml/min), inlet copper concentration (40-100 mg/L) and bed-height (4.4-13.4 cm). Artificial Neural-Fuzzy Inference System (ANFIS) was used in order to optimize the percentage of copper removal and the retention capacity in the column. The highest percentage of copper retained was achieved at 2 ml/min, 40 mg/L and 4.4 cm. However, the optimum biosorption capacity was obtained at 6 ml/min, 100 mg/L and 13.4 cm. Finally, breakthrough curves were simulated with mathematical traditional models and ANFIS model. The calculated results obtained with each model were compared with experimental data. The best results were given by ANFIS modelling that predicted copper biosorption with high accuracy. Breakthrough curves surfaces, which enable the visualization of the behavior of the system in different process conditions, were represented. Copyright © 2017 Elsevier Ltd. All rights reserved.

Adsorptive removal of heavy metals from water using sodium titanate nanofibres loaded onto GAC in fixed-bed columns.

Science.gov (United States)

Sounthararajah, D P; Loganathan, P; Kandasamy, J; Vigneswaran, S

2015-04-28

Heavy metals are serious pollutants in aquatic environments. A study was undertaken to remove Cu, Cd, Ni, Pb and Zn individually (single metal system) and together (mixed metals system) from water by adsorption onto a sodium titanate nanofibrous material. Langmuir adsorption capacities (mg/g) at 10(-3)M NaNO3 ionic strength in the single metal system were 60, 83, 115 and 149 for Ni, Zn, Cu, and Cd, respectively, at pH 6.5 and 250 for Pb at pH 4.0. In the mixed metals system they decreased at high metals concentrations. In column experiments with 4% titanate material and 96% granular activated carbon (w/w) mixture at pH 5.0, the metals breakthrough times and adsorption capacities (for both single and mixed metals systems) decreased in the order Pb>Cd, Cu>Zn>Ni within 266 bed volumes. The amounts adsorbed were up to 82 times higher depending on the metal in the granular activated carbon+titanate column than in the granular activated carbon column. The study showed that the titanate material has high potential for removing heavy metals from polluted water when used with granular activated carbon at a very low proportion in fixed-bed columns. Copyright © 2015 Elsevier B.V. All rights reserved.

Dimensioning of aerated submerged fixed bed biofilm reactors based on a mathematical biofilm model applied to petrochemical wastewater - the link between theory and practice

OpenAIRE

Trojanowicz, Karol; Wójcik, Wtodzimierz

2014-01-01

The description of a biofilm mathematical model application for dimensioning an aerated fixed bed biofilm reactor (ASFBBR) for petrochemical wastewater polishing is presented. A simple one-dimensional model of biofilm, developed by P Harremöes, was chosen for this purpose. The model was calibrated and verified under conditions of oil-refinery effluent. The results of ASFBBR dimensioning on the basis of the biofilm model were compared with the bioreactor dimensions determined by application of...

Sludge granulation during anaerobic treatment of pre-hydrolysed ...

African Journals Online (AJOL)

An upflow anaerobic sludge bed (UASB) digester was operated at different hydraulic retention times (HRT) ranging from 26.7 h to 2.2 h, while the organic load rate (OLR) ranged from 0.9 to 7.3 kgCOD/m3·d. Sludge granulation was observed after day 150 of operation, at an HRT of 3.4 h, when small granules of less than 2 ...

Organic loading rate impact on biohydrogen production and microbial communities at anaerobic fluidized thermophilic bed reactors treating sugarcane stillage.

Science.gov (United States)

Santos, Samantha Christine; Rosa, Paula Rúbia Ferreira; Sakamoto, Isabel Kimiko; Varesche, Maria Bernadete Amâncio; Silva, Edson Luiz

2014-05-01

This study aimed to evaluate the effect of high organic loading rates (OLR) (60.0-480.00 kg COD m(-3)d(-1)) on biohydrogen production at 55°C, from sugarcane stillage for 15,000 and 20,000 mg CODL(-1), in two anaerobic fluidized bed reactors (AFBR1 and AFBR2). It was obtained, for H2 yield and content, a decreasing trend by increasing the OLR. The maximum H2 yield was observed in AFBR1 (2.23 mmol g COD added(-1)). The volumetric H2 production was proportionally related to the applied hydraulic retention time (HRT) of 6, 4, 2 and 1h and verified in AFBR1 the highest value (1.49 L H2 h(-1)L(-1)). Among the organic acids obtained, there was a predominance of lactic acid (7.5-22.5%) and butyric acid (9.4-23.8%). The microbial population was set with hydrogen-producing fermenters (Megasphaera sp.) and other organisms (Lactobacillus sp.). Copyright © 2014 Elsevier Ltd. All rights reserved.

A kinetic study of gaseous potassium capture by coal minerals in a high temperature fixed-bed reactor

DEFF Research Database (Denmark)

Zheng, Yuanjing; Jensen, Peter Arendt; Jensen, Anker Degn

2008-01-01

The reactions between gaseous potassium chloride and coal minerals were investigated in a lab-scale high temperature fixed-bed reactor using single sorbent pellets. The applied coal minerals included kaolin, mullite, silica, alumina, bituminous coal ash, and lignite coal ash that were formed...... into long cylindrical pellets. Kaolin and bituminous coal ash that both have significant amounts of Si and Al show superior potassium capture characteristics. Experimental results show that capture of potassium by kaolin is independent of the gas oxygen content. Kaolin releases water and forms metakaolin...... when heated at temperatures above 450°C. The amounts of potassium captured by metakaolin pellet decreases with increasing reaction temperature in the range of 900-1300°C and increases again with further increasing the temperature up to 1500°C. There is no reaction of pre-made mullite with KCl...

Emergence of traveling wave endothermic reaction in a catalytic fixed bed under microwave heating

International Nuclear Information System (INIS)

Gerasev, Alexander P.

2017-01-01

This paper presents a new phenomenon in a packed bed catalytic reactor under microwave heating - traveling wave (moving reaction zones) endothermic chemical reaction. A two-phase model is developed to simulate the nonlinear dynamic behavior of the packed bed catalytic reactor with an irreversible first-order chemical reaction. The absorbed microwave power was obtained from Lambert's law. The structure of traveling wave endothermic chemical reaction was explored. The effects of the gas velocity and microwave power on performance of the packed bed catalytic reactor were presented. Finally, the effects of the change in the location of the microwave source at the packed bed reactor was demonstrated. - Highlights: • A new phenomenon - traveling waves of endothermic reaction - is predicted. • The physical and mathematical model of a packed bed catalytic reactor under microwave heating is presented. • The structure of the traveling waves is explored. • The configuration of heating the packed bed reactor via microwave plays a key role.

Modeling N2O Reduction and Decomposition in a Circulating Fluidized bed Boiler

DEFF Research Database (Denmark)

Johnsson, Jan Erik; Åmand, Lars-Erik; Dam-Johansen, Kim

1996-01-01

The N2O concentration was measured in a circulating fluidized bed boiler of commercial size. Kinetics for N2O reduction by char and catalytic reduction and decomposition over bed material from the combustor were determined in a laboratory fixed bed reactor. The destruction rate of N2O in the comb......The N2O concentration was measured in a circulating fluidized bed boiler of commercial size. Kinetics for N2O reduction by char and catalytic reduction and decomposition over bed material from the combustor were determined in a laboratory fixed bed reactor. The destruction rate of N2O...... in the combustion chamber and the cyclone was calculated taking three mechanisms into account: Reduction by char, catalytic decomposition over bed material and thermal decomposition. The calculated destruction rate was in good agreement with the measured destruction of N2O injected at different levels in the boiler...

CFD Simulation of Dimethyl Ether Synthesis from Methanol in an Adiabatic Fixed-bed Reactor

Directory of Open Access Journals (Sweden)

Mohammad Golshadi

2013-04-01

Full Text Available A computational fluid dynamic (CFD study of methanol (MeOH to dimethyl ether (DME process in an adiabatic fixed-bed reactor is presented. One of the methods of industrial DME production is the catalytic dehydration of MeOH. Kinetic model was derived based on Bercic rate. The parameters of this equation for a specific catalyst were tuned by solving a one-dimensional homogenous model using MATLAB optimization module. A two-dimensional CFD simulation of the reaction is demonstrated and considered as numerical experiments. A sensitivity analysis was run in order to find the effect of temperature, pressure, and WHSV on the reactor performance. Good agreement was achieved between bench experimental data and the model. The results show that the maximum conversion of reaction (about 85.03% is obtained at WHSV=10 h-1 and T=563.15 K, whereas the inlet temperature has a greater effect on methanol conversion. Moreover, the effect of water in inlet feed on methanol conversion is quantitatively studied. It was concluded that the results obtained from CFD analysis give precise guidelines for further studies on the optimization of reactor performance.

Electrochemical treatment of water containing Microcystis aeruginosa in a fixed bed reactor with three-dimensional conductive diamond anodes

International Nuclear Information System (INIS)

Mascia, Michele; Monasterio, Sara; Vacca, Annalisa; Palmas, Simonetta

2016-01-01

Highlights: • Inactivation of M. aeruginosa was achieved by electrolysis with BDD anodes. • A fixed bed reactor with 3-D electrodes was tested in batch and continuous mode. • The kinetics of the process was determined from batch experiments. • A mathematical model of the process was implemented and validated. • The model was used to predict the system behaviour under different conditions. - Abstract: An electrochemical treatment was investigated to remove Microcystis aeruginosa from water. A fixed bed reactor in flow was tested, which was equipped with electrodes constituted by stacks of grids electrically connected in parallel, with the electric field parallel to the fluid flow. Conductive diamond were used as anodes, platinised Ti as cathode. Electrolyses were performed in continuous and in batch recirculated mode with flow rates corresponding to Re from 10 to 160, current densities in the range 10–60 A m −2 and Cl − concentrations up to 600 g m −3 . The absorbance of chlorophyll-a pigment and the concentration of products and by-products of electrolysis were measured. In continuous experiments without algae in the inlet stream, total oxidants concentrations as equivalent Cl 2 , of about 0.7 g Cl 2 m −3 were measured; the maximum values were obtained at Re = 10 and i = 25 A m −2 , with values strongly dependent on the concentration of Cl − . The highest algae inactivation was obtained under the operative conditions of maximum generation of oxidants; in the presence of microalgae the oxidants concentrations were generally below the detection limit. Results indicated that most of the bulk oxidants electrogenerated is constituted by active chlorine. The prevailing mechanism of M. aeruginosa inactivation is the disinfection by bulk oxidants. The experimental data were quantitatively interpreted through a simple plug flow model, in which the axial dispersion accounts for the non-ideal flow behaviour of the system; the model was successfully

Contaminant removal performances on domestic sewage using modified anoxic/anaerobic/oxic process and micro-electrolysis.

Science.gov (United States)

Zhou, Jun; Gao, Jingqing; Liu, Yifan; Xiao, Shuai; Zhang, Ruiqin; Zhang, Zhenya

2013-01-01

The objective of this study was to enhance removal of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) from domestic sewage in a sequencing batch reactor with added new materials. A modified anoxic/anaerobic/oxic (MAAO) process, integrating a micro-electrolysis (ME) bed in an anoxic tank, and complex biological media (CBM) in anoxic, anaerobic and oxic tanks to treat domestic sewage, and their performances were investigated. The MAAO system was operated at controlled hydraulic retention time (HRT) of 8 h and mixed liquor recirculation (MLR) at 75%. The results showed that the MAAO system could effectively remove COD, TN and TP with average rates of 93%, 80% and 94%, respectively, in March, and 94%, 76% and 91%, respectively, in August. In this system, TP was primarily removed from the anoxic tank regardless of the operational conditions; removal contribution ratios to TP of the anoxic tank reached 56% both in March and August, indicating that the ME bed can effectively enhance phosphorus removal. TN was primarily removed from the anoxic and anaerobic tanks; removal contribution ratios to TN of anoxic and anaerobic tanks reached 36-38% and 37-38%, respectively. The oxic tank had the highest share of COD removal (56% both in March and August) in the removal of phosphorus. The outflow concentrations of COD, TN and TP were 3-46, 7-14 and 0.3-0.5 mg/L, respectively, in March, and 26-49, 9-15 and 0.04-0.1 mg/L, respectively, in August. COD and TN removal performances indicated that the innovative materials of the ME bed and CBM can effectively enhance COD and TN removal.

Applicability and trends of anaerobic granular sludge treatment processes

International Nuclear Information System (INIS)

Lim, Seung Joo; Kim, Tak-Hyun

2014-01-01

Anaerobic granular sludge treatment processes have been continuously developed, although the anaerobic sludge granulation process was not clearly understood. In this review, an upflow anaerobic sludge blanket (UASB), an expanded granule sludge blanket (EGSB), and a static granular bed reactor (SGBR) were introduced as components of a representative anaerobic granular sludge treatment processes. The characteristics and application trends of each reactor were presented. The UASB reactor was developed in the late 1970s and its use has been rapidly widespread due to the excellent performance. With the active granules, this reactor is able to treat various high-strength wastewaters as well as municipal wastewater. Most soluble industrial wastewaters can be efficiently applied using a UASB. The EGSB reactor was developed owing to give more chance to contact between wastewater and the granules. Dispersed sludge is separated from mature granules using the rapid upward velocity in this reactor. The EGSB reactor shows the excellent performance in treating low-strength and/or high-strength wastewater, especially under low temperatures. The SGBR, developed at Iowa State University, is one of anaerobic granular sludge treatment processes. Although the configuration of the SGBR is very simple, the performance of this system is similar to that of the UASB or EGSB reactor. The anaerobic sludge granulation processes showed excellent performance for various wastewaters at a broad range of organic loading rate in lab-, pilot-scale tests. This leads to erect thousands of full-scale granular processes, which has been widely operated around the world. -- Highlights: • Anaerobic sludge granulation is a key parameter for maintaining granular processes. • Anaerobic granular digestion processes are applicable for various wastewaters. • The UASB is an economic high-rate anaerobic granular process. • The EGSB can treat high-strength wastewater using expanding granules. • The SGBR is

Upflow anaerobic sludge blanket-hollow centered packed bed (UASB-HCPB) reactor for thermophilic palm oil mill effluent (POME) treatment

International Nuclear Information System (INIS)

Poh, P.E.; Chong, M.F.

2014-01-01

Upflow anaerobic sludge blanket-hollow centered packed bed (UASB-HCPB) reactor was developed with the aim to minimize operational problems in the anaerobic treatment of Palm Oil Mill Effluent (POME) under thermophilic conditions. The performance of UASB-HCPB reactor on POME treatment was investigated at 55 °C. Subsequent to start-up, the performance of the UASB-HCPB reactor was evaluated in terms of i) effect of hydraulic retention time (HRT); ii) effect of organic loading rate (OLR); and iii) effect of mixed liquor volatile suspended solid (MLVSS) concentration on thermophilic POME treatment. Start-up up of the UASB-HCPB reactor was completed in 36 days, removing 88% COD and 90% BOD respectively at an OLR of 28.12 g L −1  d −1 , producing biogas with 52% of methane. Results from the performance study of the UASB-HCPB reactor on thermophilic POME treatment indicated that HRT of 2 days, OLR of 27.65 g L −1  d −1 and MLVSS concentration of 14.7 g L −1 was required to remove 90% of COD and BOD, 80% of suspended solid and at the same time produce 60% of methane. - Highlights: • UASB-HCPB was proposed for POME treatment under thermophilic conditions. • Start-up up of the UASB-HCPB reactor was completed in 36 days. • 88% COD and 90% BOD were removed at an OLR of 28.12 g COD/L.day during start-up. • HRT of 2 days and OLR of 27.65 g COD/L.day was required to produce 60% methane. • Methanosarcina sp. forms the majority of microbial population in the UASB section

Evaluation of an up-flow anaerobic sludge bed (UASB) reactor containing diatomite and maifanite for the improved treatment of petroleum wastewater.

Science.gov (United States)

Chen, Chunmao; Liang, Jiahao; Yoza, Brandon A; Li, Qing X; Zhan, Yali; Wang, Qinghong

2017-11-01

Novel diatomite (R1) and maifanite (R2) were utilized as support materials in an up-flow anaerobic sludge bed (UASB) reactor for the treatment of recalcitrant petroleum wastewater. At high organic loadings (11kg-COD/m 3 ·d), these materials were efficient at reducing COD (92.7% and 93.0%) in comparison with controls (R0) (88.4%). Higher percentages of large granular sludge (0.6mm or larger) were observed for R1 (30.3%) and R2 (24.6%) compared with controls (22.6%). The larger portion of granular sludge provided a favorable habitat that resulted in greater microorganism diversity. Increased filamentous bacterial communities are believed to have promoted granular sludge formation promoting a conductive environment for stimulation methanogenic Archaea. These communities had enhanced pH tolerance and produced more methane. This study illustrates a new potential use of diatomite and maifanite as support materials in UASB reactors for increased efficiency when treating refractory wastewaters. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development and evaluation of a radial anaerobic/aerobic reactor treating organic matter and nitrogen in sewage

Directory of Open Access Journals (Sweden)

L. H. P. Garbossa

2005-12-01

Full Text Available The design and performance of a radial anaerobic/aerobic immobilized biomass (RAAIB reactor operating to remove organic matter, solids and nitrogen from sewage are discussed. The bench-scale RAAIB was divided into five concentric chambers. The second and fourth chambers were packed with polyurethane foam matrices. The performance of the reactor in removing organic matter and producing nitrified effluent was good, and its configuration favored the transfer of oxygen to the liquid mass due to its characteristics and the fixed polyurethane foam bed arrangement in concentric chambers. Partial denitrification of the liquid also took place in the RAAIB. The reactor achieved an organic matter removal efficiency of 84%, expressed as chemical oxygen demand (COD, and a total Kjeldahl nitrogen (TKN removal efficiency of 96%. Average COD, nitrite and nitrate values for the final effluent were 54 mg.L-1, 0.3 mg.L-1 and 22.1 mg.L-1, respectively.

Numerical Simulation of Fixed-Bed Catalytic Reforming Reactors: Hydrodynamics / Chemical Kinetics Coupling Simulation numérique des réacteurs de reformage catalytique en lit fixe : couplage hydrodynamique-cinétique chimique

Directory of Open Access Journals (Sweden)

Ferschneider G.

2006-11-01

Full Text Available Fixed bed reactors with a single fluid phase are widely used in the refining or petrochemical industries for reaction processes catalysed by a solid phase. The design criteria for industrial reactors are relatively well known. However, they rely on a one-dimensional writing and on the separate resolution of the equation of conservation of mass and energy, and of momentum. Thus, with complex geometries, the influence of hydrodynamics on the effectiveness of the catalyst bed cannot be taken into account. The calculation method proposed is based on the multi-dimensional writing and the simultaneous resolution of the local conservation equations. The example discussed concerns fixed-bed catalytic reactors. These reactors are distinguished by their annular geometry and the radial circulation of the feedstock. The flow is assumed to be axisymmetric. The reaction process is reflected by a simplified kinetic mechanism involving ten chemical species. Calculation of the hydrodynamic (mean velocities, pressure, thermal and mass fields (concentration of each species serves to identify the influence of internal components in two industrial reactor geometries. The map of the quantity of coke formed and deposited on the catalyst, calculated by the model, reveals potential areas of poor operation. Les réacteurs à lit fixe avec une seule phase fluide sont largement utilisés dans l'industrie du raffinage et de la pétrochimie, pour mettre en oeuvre un processus réactionnel catalysé par une phase solide. Les règles de conception des réacteurs industriels sont relativement bien connues. Cependant, elles reposent sur l'écriture monodimensionnelle et la résolution séparée, d'une part, des équations de conservation de la masse et de l'énergie et d'autre part, de la quantité de mouvement. Ainsi dans le cas de géométries complexes, l'influence de l'hydrodynamique sur l'efficacité du lit catalytique ne peut être prise en compte. La méthode de calcul

Fixed-bed column study for 90Sr removal from solution by sunflower straw

International Nuclear Information System (INIS)

Ai Lian; Luo Xuegang; Lin Xiaoyan; Li Wenming

2014-01-01

This paper deals with removal of strontium ions from solution by sunflower straw. Metal sorption performance of the packed column was assessed under variable operating conditions, such as, bed depths, flow rates and initial influent strontium concentration. It was found that the breakthrough time and the depletion time were extended with increase of bed heights but obviously shortened with increase of influent concentration and flow rates, respectively. The equilibrium uptake (q e(exp) ) of sunflower straw increased with increase in initial influent strontium concentration and flow rates but decreased with increase in bed depth, respectively. The data in regard to the effect of bed depths were fitted well to the Bohrat-Adams model. The saturated column was successfully regenerated by 0.1 mol/L hydrogen chloride solution and sunflower straw could be reused in strontium removal. The results indicated that the column could efficiently remove strontium ions from real industrial effluents, and hence the sunflower straw is a good candidate for commercial application. (authors)

Early stages in biofilm development in methanogenic fluidized-bed reactors

Energy Technology Data Exchange (ETDEWEB)

Lauwers, A.M.; Heinen, W.; Gorris, L.G.M.; Drift, C. van der (Katholieke Univ. Nijmegen (Netherlands). Dept. of Microbiology and Evolution Biology)

1990-06-01

Biofilm development in methanogenic fluidized-bed reactors with sand as the carrier was studied on a laboratory scale. The microorganisms present in consecutive layers of the biofilm of mature sludge granules were prelimilarily characterized on the basis of their morphology, element composition and adhesion capacity and were compared to bacteria which take part in the initial colonization of sand. The early phase of biofilm development was monitored with reactors receiving waste-waters containing different mixtures of volatile fatty acids and inoculated with fluidized-bed reactor effluent for different lengths of time. The results obtained indicate that facultative anaerobic bacteria abundantly present in the outermost biofilm layers of mature sludge granules are probably the main primary colonizers of the sand. Methanothrix spp. or other methanogens were rarely observed among the primary colonizers. The course of biofilm formation was comparable under the various start-up conditions employed including variations in waste-water composition, inoculation and anaerobicity. However, omission of waste-water and thus of substrate resulted in rapid wash-out of the attached biomass. (orig.).

Thermal-hydraulic study of fixed bed nuclear reactor (FBNR), in FCC, BCC and pseudo-random configurations of the core through CFD method

International Nuclear Information System (INIS)

Luna, M.; Chavez, I.; Cajas, D.; Santos, R.

2015-01-01

The study of thermal-hydraulic performance of a fixed bed nuclear reactor (FBNR) core and the effect of the porosity was studied by the CFD method with 'SolidWorks' software. The representative sections of three different packed beds arrangements were analyzed: face-centered cubic (FCC), body-centered cubic (BCC), and a pseudo-random, with values of porosity of 0.28, 0.33 and 0.53 respectively. The minimum coolant flow required to avoid the phase change for each one of the configurations was determined. The results show that the heat transfer rate increases when the porosity value decreases, and consequently the minimum coolant flow in each configuration. The results of minimum coolant flow were: 728.51 kg/s for the FCC structure, 372.72 kg/s for the BCC, and 304.96 kg/s for the pseudo-random. Meanwhile, the heat transfer coefficients in each packed bed were 6480 W/m 2 *K, 3718 W/m 2 *K and 3042 W/m 2 *K respectively. Finally the pressure drop was calculated, and the results were 0.588 MPa for FCC configuration, 0.033 MPa for BCC and 0.017 MPa for the pseudo-random one. This means that with a higher porosity, the fluid can circulate easier because there are fewer obstacles to cross, so there are fewer energy losses. (authors)

Role of nickel in high rate methanol degradation in anaerobic granular sludge bioreactors

NARCIS (Netherlands)

Fermoso, F.G.; Collins, G.; Bartacek, J.; O'Flaherty, V.; Lens, P.N.L.

2008-01-01

The effect of nickel deprivation from the influent of a mesophilic (30 degrees C) methanol fed upflow anaerobic sludge bed (UASB) reactor was investigated by coupling the reactor performance to the evolution of the Methanosarcina population of the bioreactor sludge. The reactor was operated at pH

Effect Of Imposed Anaerobic Conditions On Metals Release From Acid-Mine Drainage Contaminated Streambed Sediments

Science.gov (United States)

Remediation of streams influenced by mine-drainage may require removal and burial of metal-containing bed sediments. Burial of aerobic sediments into an anaerobic environment may release metals, such as through reductive dissolution of metal oxyhydroxides. Mining-impacted aerob...

Note: Small anaerobic chamber for optical spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Chauvet, Adrien A. P., E-mail: adrien.chauvet@gmail.com; Chergui, Majed [Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratoire de Spectroscopie Ultrarapide, ISIC, Faculté des Sciences de Base, Station 6, 1015 Lausanne (Switzerland); Agarwal, Rachna; Cramer, William A. [Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907 (United States)

2015-10-15

The study of oxygen-sensitive biological samples requires an effective control of the atmosphere in which they are housed. In this aim however, no commercial anaerobic chamber is adequate to solely enclose the sample and small enough to fit in a compact spectroscopic system with which analysis can be performed. Furthermore, spectroscopic analysis requires the probe beam to pass through the whole chamber, introducing a requirement for adequate windows. In response to these challenges, we present a 1 l anaerobic chamber that is suitable for broad-band spectroscopic analysis. This chamber has the advantage of (1) providing access, via a septum, to the sample and (2) allows the sample position to be adjusted while keeping the chamber fixed and hermetic during the experiment.

Thermal activation and characterization of clay aiming their use as sorbent in fixed bed columns to remove cadmium; Ativacao termica e caracterizacao da argila visando sua utilizacao como adsorvente em colunas de leito fixo para a remocao de cadmio

Energy Technology Data Exchange (ETDEWEB)

Silva, M.M. da; Rodrigues, M.G.F. [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Silva, M.L.P. [Universidade Federal Rural do Semi-Arido (UFERSA), RN (Brazil); Kleinübing, S.J.; Silva, M.G.C., E-mail: marciliomaximo@yahoo.com.br [Universidade Estadual de Campinas (UNICAMP), SP (Brazil)

2011-07-01

In this work we studied the removal of cadmium in a synthetic wastewater using clay of Pernambuco - Brazil, in systems of fixed bed column. Clay was thermally activated at 500 °C. The materials were characterized using X-ray Fluorescence (XRF), X-ray Diffraction (XRD) and nitrogen adsorption (BET method). For tests in fixed bed column, we applied a factorial design 2{sup 2} and found that increasing the flow adversely affects the process of removing cadmium concentration while acting positively. The studies showed these materials as promising for the removal of Cd{sup 2+} ions in synthetic wastewater containing low levels of this metal. (author)

Comparative study on pyrolysis of lignocellulosic and algal biomass using a thermogravimetric and a fixed-bed reactor.

Science.gov (United States)

Yuan, Ting; Tahmasebi, Arash; Yu, Jianglong

2015-01-01

Pyrolysis characteristics of four algal and lignocellulosic biomass samples were studied by using a thermogravimetric analyzer (TGA) and a fixed-bed reactor. The effects of pyrolysis temperature and biomass type on the yield and composition of pyrolysis products were investigated. The average activation energy for pyrolysis of biomass samples by FWO and KAS methods in this study were in the range of 211.09-291.19kJ/mol. CO2 was the main gas component in the early stage of pyrolysis, whereas H2 and CH4 concentrations increased with increasing pyrolysis temperature. Bio-oil from Chlorellavulgaris showed higher content of nitrogen containing compounds compared to lignocellulosic biomass. The concentration of aromatic organic compounds such as phenol and its derivatives were increased with increasing pyrolysis temperature up to 700°C. FTIR analysis results showed that with increasing pyrolysis temperature, the concentration of OH, CH, CO, OCH3, and CO functional groups in char decreased sharply. Copyright © 2014 Elsevier Ltd. All rights reserved.

performance of a sisal fibre fixed-bed anaerobic digester for biogas

African Journals Online (AJOL)

Mgina

Lund, P.O Box 124, S-22100, Lund, Sweden. ABSTRACT. A single .... with sugar beet tops, operated for 120 days. (Agrigas ... pumping every 6 hours with a flow rate of. 1.0 L day-1 .... methane yield data obtained in this work fall within values ...

Energy positive domestic wastewater treatment: the roles of anaerobic and phototrophic technologies.

Science.gov (United States)

Shoener, B D; Bradley, I M; Cusick, R D; Guest, J S

2014-05-01

The negative energy balance of wastewater treatment could be reversed if anaerobic technologies were implemented for organic carbon oxidation and phototrophic technologies were utilized for nutrient recovery. To characterize the potential for energy positive wastewater treatment by anaerobic and phototrophic biotechnologies we performed a comprehensive literature review and analysis, focusing on energy production (as kJ per capita per day and as kJ m(-3) of wastewater treated), energy consumption, and treatment efficacy. Anaerobic technologies included in this review were the anaerobic baffled reactor (ABR), anaerobic membrane bioreactor (AnMBR), anaerobic fluidized bed reactor (AFB), upflow anaerobic sludge blanket (UASB), anaerobic sequencing batch reactor (ASBR), microbial electrolysis cell (MEC), and microbial fuel cell (MFC). Phototrophic technologies included were the high rate algal pond (HRAP), photobioreactor (PBR), stirred tank reactor, waste stabilization pond (WSP), and algal turf scrubber (ATS). Average energy recovery efficiencies for anaerobic technologies ranged from 1.6% (MFC) to 47.5% (ABR). When including typical percent chemical oxygen demand (COD) removals by each technology, this range would equate to roughly 40-1200 kJ per capita per day or 110-3300 kJ m(-3) of treated wastewater. The average bioenergy feedstock production by phototrophic technologies ranged from 1200-4700 kJ per capita per day or 3400-13 000 kJ m(-3) (exceeding anaerobic technologies and, at times, the energetic content of the influent organic carbon), with usable energy production dependent upon downstream conversion to fuels. Energy consumption analysis showed that energy positive anaerobic wastewater treatment by emerging technologies would require significant reductions of parasitic losses from mechanical mixing and gas sparging. Technology targets and critical barriers for energy-producing technologies are identified, and the role of integrated anaerobic and

Energy positive domestic wastewater treatment: the roles of anaerobic and phototrophic technologies

KAUST Repository

Shoener, B. D.

2014-01-01

The negative energy balance of wastewater treatment could be reversed if anaerobic technologies were implemented for organic carbon oxidation and phototrophic technologies were utilized for nutrient recovery. To characterize the potential for energy positive wastewater treatment by anaerobic and phototrophic biotechnologies we performed a comprehensive literature review and analysis, focusing on energy production (as kJ per capita per day and as kJ m-3 of wastewater treated), energy consumption, and treatment efficacy. Anaerobic technologies included in this review were the anaerobic baffled reactor (ABR), anaerobic membrane bioreactor (AnMBR), anaerobic fluidized bed reactor (AFB), upflow anaerobic sludge blanket (UASB), anaerobic sequencing batch reactor (ASBR), microbial electrolysis cell (MEC), and microbial fuel cell (MFC). Phototrophic technologies included were the high rate algal pond (HRAP), photobioreactor (PBR), stirred tank reactor, waste stabilization pond (WSP), and algal turf scrubber (ATS). Average energy recovery efficiencies for anaerobic technologies ranged from 1.6% (MFC) to 47.5% (ABR). When including typical percent chemical oxygen demand (COD) removals by each technology, this range would equate to roughly 40-1200 kJ per capita per day or 110-3300 kJ m-3 of treated wastewater. The average bioenergy feedstock production by phototrophic technologies ranged from 1200-4700 kJ per capita per day or 3400-13000 kJ m-3 (exceeding anaerobic technologies and, at times, the energetic content of the influent organic carbon), with usable energy production dependent upon downstream conversion to fuels. Energy consumption analysis showed that energy positive anaerobic wastewater treatment by emerging technologies would require significant reductions of parasitic losses from mechanical mixing and gas sparging. Technology targets and critical barriers for energy-producing technologies are identified, and the role of integrated anaerobic and phototrophic

Evaluation of Two Biosorbents in the Removal of Metal Ions in Aqueous Using a Pilot Scale Fixed-bed System

Directory of Open Access Journals (Sweden)

Andre Gadelha Oliveira

2014-05-01

Full Text Available The aim of the present work was to investigate the adsorption of toxic metal ions copper, nickel and zinc from aqueous solutions using low cost natural biomass (sugar cane bagasse and green coconut fiber in pilot scale fixed-bed system. The Hydraulic retention time (HRT was 229 minutes and the lowest adsorbent usage rate (AUR found was 0.10 g.L-1 for copper using green coconut fibers. The highest values of adsorption capacities founded were 1.417 and 2.772 mg.g-1 of Cu(II ions for sugarcane bagasse and green coconut fibers, respectively. The results showed that both sugarcane bagasse and green coconut fiber presented potential in the removal of metal ions copper, nickel and zinc ions from aqueous solution and the possible use in wastewater treatment station.

The pressure effects on two-phase anaerobic digestion

International Nuclear Information System (INIS)

Chen, Yuling; Rößler, Benjamin; Zielonka, Simon; Lemmer, Andreas; Wonneberger, Anna-Maria; Jungbluth, Thomas

2014-01-01

Highlights: • The pressure effect on anaerobic digestion up to 9 bar was examined. • Increasing pressure decreased pH value in the anaerobic filter. • Increasing pressure increased methane content. • Increasing pressure decreased specific methane yield slightly. • The pressurized methane reactor was very stable and performed well. - Abstract: Two-phase pressurized anaerobic digestion is a novel process aimed at facilitating injection of the produced biogas into the natural gas grid by integrating the fermentative biogas production and upgrading it to substitute natural gas. In order to understand the mechanisms, knowledge of pressure effects on anaerobic digestion is required. To examine the effects of pressure on the anaerobic digestion process, a two-phase anaerobic digestion system was built up in laboratory scale, including three acidogenesis-leach-bed-reactors and one pressure-resistant anaerobic filter. Four different pressure levels (the absolute pressure of 1 bar, 3 bar, 6 bar and 9 bar) were applied to the methane reactor in sequence, with the organic loading rate maintained at approximately 5.1 kgCOD m −3 d −1 . Gas production, gas quality, pH value, volatile fatty acids, alcohol, ammonium-nitrogen, chemical oxygen demand (COD) and alkaline buffer capacity were analyzed. No additional caustic chemicals were added for pH adjustment throughout the experiment. With the pressure increasing from 1.07 bar to 8.91 bar, the pH value decreased from 7.2 to 6.5, the methane content increased from 66% to 75%, and the specific methane yield was slightly reduced from 0.33 l N g −1 COD to 0.31 l N g −1 COD. There was almost no acid-accumulation during the entire experiment. The average COD-degradation grade was always more than 93%, and the average alkaline buffering capacity (VFA/TIC ratio) did not exceed 0.2 at any pressure level. The anaerobic filter showed a very stable performance, regardless of the pressure variation

Extraction of uranium from sea water with the granular composite adsorbent by using the fixed bed

International Nuclear Information System (INIS)

Katoh, Shunsaku; Sakane, Kohji; Hirotsu, Takahiro; Fujii, Ayako; Kitamura, Takao

1981-01-01

To clarify the technical problems existing in the extraction process of uranium from sea water, uranium was extracted from natural sea water, with the granulated C-Ti-OH composite adsorbent. The adsorption of uranium from sea water was carried out by using the fixed bed that had been designed in our laboratory. The uranium recovery from the sea water was 13.9% in the adsorption process of 56 d. The adsorbed uranium was eluted from the adsorbent with 0.5 N NaHCO 3 -0.5N Na 2 CO 3 soln. at 70 0 C. The elution recovery was 97.4% for 35 h. The uranium contained in the eluate was concentrated twenty times as much as in the anion exchange process, and then 100 times in the solvent extraction process with oxine-chloroform and TOA-kerosene. About 0.7 g of yellow cake was prepared from natural sea water, and it was identified to be pure 2UO 2 .NH 3 .3H 2 O by X-ray diffraction method and X-ray fluorometry. (author)

Co-pyrolysis of rice straw and Polyethylene Terephthalate (PET) using a fixed bed drop type pyrolyzer

Science.gov (United States)

Izzatie, N. I.; Basha, M. H.; Uemura, Y.; Hashim, M. S. M.; Amin, N. A. M.; Hamid, M. F.

2017-10-01

In this work, co-pyrolysis of rice straw and polyethylene terephthalate (PET) was carried out at different temperatures (450,500,550, and 600°C) at ratio 1:1 by using fixed bed drop-type pyrolyzer. The purpose of this work is to determine the effect of pyrolysis temperature on the product yield. As the temperature increased, the pyrolysis oil increased until it reaches certain high temperature (600°C), the pyrolysis oil decreased as of more NCG were produced. The temperature 550°C is considered as the optimum pyrolysis temperature since it produced the highest amount of pyrolysis oil with 36 wt.%. In pyrolysis oil, the calorific value (13.98kJ/g) was low because of the presence of high water content (52.46 wt.%). Main chemicals group from pyrolysis oil were an aldehyde, ketones, acids, aromatics, and phenol and all compound have abundant of hydrogen and carbon were identified. Co-pyrolysis of rice straw and PET produced a higher amount of carbon oxides and recycling back the NCG could increase liquid and char yields.

Stability and activity of anaerobic sludge from UASB reactors treating sewage in subtropical regions

NARCIS (Netherlands)

Seghezzo, L.; Cuevas, C.M.; Trupiano, A.P.; Guerra, R.G.; Gonzalez, S.M.; Zeeman, G.; Lettinga, G.

2006-01-01

The production of small amounts of well-stabilized biological sludge is one of the main advantages of upflow anaerobic sludge bed (UASB) reactors over aerobic wastewater treatment systems. In this work, sludge produced in three pilot-scale UASB reactors used to treat sewage under subtropical

Electrochemical treatment of water containing Microcystis aeruginosa in a fixed bed reactor with three-dimensional conductive diamond anodes

Energy Technology Data Exchange (ETDEWEB)

Mascia, Michele, E-mail: michele.mascia@unica.it; Monasterio, Sara; Vacca, Annalisa; Palmas, Simonetta

2016-12-05

Highlights: • Inactivation of M. aeruginosa was achieved by electrolysis with BDD anodes. • A fixed bed reactor with 3-D electrodes was tested in batch and continuous mode. • The kinetics of the process was determined from batch experiments. • A mathematical model of the process was implemented and validated. • The model was used to predict the system behaviour under different conditions. - Abstract: An electrochemical treatment was investigated to remove Microcystis aeruginosa from water. A fixed bed reactor in flow was tested, which was equipped with electrodes constituted by stacks of grids electrically connected in parallel, with the electric field parallel to the fluid flow. Conductive diamond were used as anodes, platinised Ti as cathode. Electrolyses were performed in continuous and in batch recirculated mode with flow rates corresponding to Re from 10 to 160, current densities in the range 10–60 A m{sup −2} and Cl{sup −} concentrations up to 600 g m{sup −3}. The absorbance of chlorophyll-a pigment and the concentration of products and by-products of electrolysis were measured. In continuous experiments without algae in the inlet stream, total oxidants concentrations as equivalent Cl{sub 2}, of about 0.7 g Cl{sub 2} m{sup −3} were measured; the maximum values were obtained at Re = 10 and i = 25 A m{sup −2}, with values strongly dependent on the concentration of Cl{sup −}. The highest algae inactivation was obtained under the operative conditions of maximum generation of oxidants; in the presence of microalgae the oxidants concentrations were generally below the detection limit. Results indicated that most of the bulk oxidants electrogenerated is constituted by active chlorine. The prevailing mechanism of M. aeruginosa inactivation is the disinfection by bulk oxidants. The experimental data were quantitatively interpreted through a simple plug flow model, in which the axial dispersion accounts for the non-ideal flow behaviour of the

Treatment of waste gas from the breather vent of a vertical fixed roof p-xylene storage tank by a trickle-bed air biofilter.

Science.gov (United States)

Chang, Shenteng; Lu, Chungsying; Hsu, Shihchieh; Lai, How-Tsan; Shang, Wen-Lin; Chuang, Yeong-Song; Cho, Chi-Huang; Chen, Sheng-Han

2011-01-01

This study applied a pilot-scale trickle-bed air biofilter (TBAB) system for treating waste gas emitted from the breather vent of a vertical fixed roof storage tank containing p-xylene (p-X) liquid. The volatile organic compound (VOC) concentration of the waste gas was related to ambient temperature as well as solar radiation, peaking at above 6300 ppmv of p-X and 25000 ppmv of total hydrocarbons during the hours of 8 AM to 3 PM. When the activated carbon adsorber was employed as a VOC buffer, the peak waste gas VOC concentration was significantly reduced resulting in a stably and efficiently performing TBAB system. The pressure drop appeared to be low, reflecting that the TBAB system could be employed in the prolonged operation with a low running penalty. These advantages suggest that the TBAB system is a cost-effective treatment technology for VOC emission from a fixed roof storage tank. Copyright © 2010 Elsevier Ltd. All rights reserved.

Techno-economic assessment of anaerobic digestion systems for agri-food wastes

Energy Technology Data Exchange (ETDEWEB)

Lau, A.; Baldwin, S.; Wang, M. [British Colombia Univ., Vancouver, BC (Canada)

2010-07-01

Activities in British Columbia's Fraser Valley generate an estimated 3 million tones of agriculture and food wastes annually, of which 85 per cent are readily available for anaerobic digestion. The potential for energy generation from biogas through anaerobic digestion is approximately 30 MW. On-farm manure-based systems represent the most likely scenario for the development of anaerobic digestion in British Columbia in the near future. Off-farm food processing wastes may be an alternative option to large centralized industrial complexes. Odour control, pathogen reduction, improved water quality, reduced greenhouse gas emissions and reduced landfill usage are among the environmental benefits of anaerobic digestion. The economical benefits include power and heat generation, biogas upgrading, and further processing of the residues to produce compost or animal bedding. This paper described a newly developed anaerobic digestion (AD) calculator that helps users regarding their investment decision in AD facilities. The calculator classifies various technology options into several major types of AD systems. It also constructs kinetic and economic models for these systems and provides a fair estimation on biogas yield, digester volume, capital cost and annual income. The calculator takes into consideration factors such as the degradability of wastes with different compositions and different operating parameters.

Modelagem do processo de desidratação de lodo anaeróbio em leitos de secagem simulados Anaerobic sludge dewatering process modeling in simulated drying beds

Directory of Open Access Journals (Sweden)

Sérgio R. A. Soares

2001-05-01

Full Text Available O emprego de leitos de secagem para a desidratação de lodo de descarte de reatores UASB, constitui excelente alternativa, face a sua simplicidade operacional e aos reduzidos custos de implantação. Este trabalho apresenta uma análise dos fenômenos que influenciam o processo de desidratação de lodo anaeróbio, a partir de simulação de leitos de secagem. Neste sentido, são feitas considerações sobre as características e o comportamento do lodo durante cada fase da secagem. Sugere-se também, um modelo matemático para representar o processo de secagem, obtido a partir dos dados experimentais.The employment of drying beds is an excellent option for dewatering of UASB reactor discarded sludge, because of their simple operation and low construction costs. This paper presents an anaerobic sludge dewatering process analysis of the most influential phenomenon based on drying beds simulation. Therefore, some considerations were made about sludge characteristics and behavior during each dewatering stage. A mathematical model for dewatering process representation obtained from experimental data is also suggested.

Mitigation of micropollutants for black water application in agriculture via composting of anaerobic sludge

NARCIS (Netherlands)

Butkovskyi, A.; Ni, G.; Hernandez Leal, L.; Rijnaarts, H.H.M.; Zeeman, G.

2016-01-01

The excess sludge from Up-flow anaerobic sludge bed (UASB) reactor operated on source separated toilet wastewater is a potential source of nutrients and organic matter. It can be further stabilized and dried by composting and applied as a soil amendment. Presence of pathogens, heavy metals and

Microbial sulfate reduction under sequentially acidic conditions in an upflow anaerobic packed bed bioreactor

Energy Technology Data Exchange (ETDEWEB)

Jong, T.; Parry, D.L. [Charles Darwin University, Darwin, NT (Australia). Faculty for Educational Health & Science

2006-07-15

The aim of this study was to operate an upflow anaerobic packed bed reactor (UAPB) containing sulfate reducing bacteria (SRB) under acidic conditions similar to those found in acid mine drainage (AMD). The UAPB was filled with sand and operated under continuous flow at progressively lower pH and was shown to be capable of supporting sulfate reduction at pH values of 6.0, 5.0, 4.5, 4.0 and 3.5 in a synthetic medium containing 53.5 mmol l{sup -1} lactate. Sulfate reduction rates of 553-1052 mmol m{sup -3} d{sup -1} were obtained when the influent solution pH was progressively lowered from pH 6.0 to 4.0, under an optimal flow rate of 2.61 ml min{sup -1}. When the influent pH was further lowered to pH 3.5, sulfate reduction was substantially reduced with only about 1% sulfate removed at a rate of 3.35 mmol m{sup -3} d{sup -1} after 20 days of operation. However, viable SRB were recovered from the column, indicating that the SRB population was capable of surviving and metabolizing at low levels even at pH 3.5 conditions for at least 20 days. The changes in conductivity in the SRB column did not always occur with changes in pH and redox potential, suggesting that conductivity measurements may be more sensitive to SRB activity and could be used as an additional tool for monitoring SRB activity. The bioreactor containing SRB was able to reduce sulfate and generate alkalinity even when challenged with influent as low as pH 3.5, indicating that such treatment systems have potential for bioremediating highly acidic, sulfate contaminated waste waters.

Anaerobic nitrogen turnover by sinking diatom aggregates at varying ambient oxygen levels

DEFF Research Database (Denmark)

Stief, Peter; Kamp, Anja; Thamdrup, Bo

2016-01-01

nitrate supply. Sinking diatom aggregates can contribute directly to fixed-nitrogen loss in low-oxygen environments in the ocean and vastly expand the ocean volume in which anaerobic nitrogen turnover is possible, despite relatively high ambient oxygen levels. Depending on the extent of intracellular......In the world’s oceans, even relatively low oxygen levels inhibit anaerobic nitrogen cycling by free-living microbes. Sinking organic aggregates, however, might provide oxygen-depleted microbial hotspots in otherwise oxygenated surface waters. Here, we show that sinking diatom aggregates can host...

Anaerobic bioprocessing of sewage sludge, focusing on degradation of linear alkylbenzene sulfonates (LAS)

Energy Technology Data Exchange (ETDEWEB)

Angelidaki, I.; Toraeng, L.; Waul, C.M.; Schmidt, J.E.

2003-07-01

Anaerobic degradation of sludge amended with linear alkylbenzene sulfonates (LAS) was tested in one stage continuous stirred tank reactor (CSTR) and a two stages reactor system consisting by a CSTR as first step and upflow anaerobic sludge bed (UASB) reactor in the second step. Anaerobic removal of LAS was only observed at the second step but not at the first step. Removal of LAS in the UASB reactors was approx. 80% where half was due to absorption and the other half was apparently due to biological removal as shown from the LAS mass balance. At the end of the experiment the reactors were spiked with {sup 14}C-LAS which resulted in 5.6% {sup 14}CO{sub 2} in the produced gas. Total mass balance of the radioactivity was however not achieved. In batch experiments it was found that LAS at concentrations higher than 50 mg/l is inhibitory for the most microbial groups of the anaerobic process. Therefore, low initial LAS concentration is a prerequisite for successful LAS degradation. The results from the present study suggest that anaerobic degradation of LAS is possible in UASB reactors when the concentration of LAS is low enough to avoid inhibition of microorganisms active in the anaerobic process. (author)

Fast pyrolysis of hardwood residues using a fixed bed drop-type pyrolyzer

International Nuclear Information System (INIS)

Mazlan, Mohammad Amir Firdaus; Uemura, Yoshimitsu; Osman, Noridah B.; Yusup, Suzana

2015-01-01

Highlights: • Pyrolysis of rubber and Meranti wood was conducted by using a drop-type pyrolyzer. • As temperature increase, char yield decrease, but bio-oil and gas yield increase. • Maximum pyrolysis temperature for pyrolysis of RWS is 550 °C and 600 °C for MWS. • Calorific value of bio-char is very high and potential to be used as a solid fuel. • CO and CO 2 are the major gas components in the non-condensable gases by-product. - Abstract: In this research, rubber wood sawdust (RWS) and Meranti wood sawdust (MWS) were pyrolyzed in a fixed bed drop-type pyrolyzer under an inert condition. The first part of the study is to determine the influence of pyrolysis temperature (450, 500, 550, 600, 650 °C) on the yield of pyrolysis products. Pyrolysis of these different residues generate an almost identical maximum amount of bio-oil close to 33 wt.%, but at different maximum temperature (550 °C for pyrolysis of RWS and 600 °C for pyrolysis of MWS). To evaluate the effect of biomass type on the composition and characterization of pyrolysis products, the second part involves the analyses of pyrolysis products from the maximum pyrolysis temperature. Acetic acid, tetrahydrofuran, and benzene were the main bio-oil components. The bio-oil contained high percentage of oxygen and hydrogen, indicating high water content in the bio-oil. High amount of water in bio-oil significantly reduced its calorific value. Under extensive heating, particle size of the bio-char from SEM images decreased due to breakage and shrinkage mechanisms. The major components of non-condensable gases were CO and CO 2

Municipal Development of Anaerobic Digestion/ Combined Heat and Power in Massachusetts

Science.gov (United States)

Pike, Brenda

With a commercial food waste ban going into effect in Massachusetts in October 2014, businesses, institutions, and municipalities are considering alternatives to landfills and incinerators for organic waste. Anaerobic digestion is one such alternative. Similar to composting, but in an environment devoid of oxygen, anaerobic digestion produces byproducts such as methane (which can be burned for heat or electricity) and liquid or solid digestate (which can be used as fertilizer, cattle bedding, and more). Thus, disposal of food waste and other organic materials can become a source of revenue rather than just an expense. Municipalities interested in developing anaerobic digestion/combined heat and power (AD/CHP) facilities have the benefit of desirable options for sites, such as landfill gas facilities and wastewater treatment plants, and potential feedstocks in source-separated residential or municipal food waste or wastewater. This thesis examines the opportunities and challenges for municipal development of AD/CHP facilities in Massachusetts.

Optimization of fermentative hydrogen production from palm oil mill effluent in an up-flow anaerobic sludge blanket fixed film bioreactor

Directory of Open Access Journals (Sweden)

Parviz Mohammadi

2017-09-01

Full Text Available Response surface methodology with a central composite design was applied to optimize fermentative hydrogen production from palm oil mill effluent (POME in an upflow anaerobic sludge blanket fixed film reactor. In this study, the concurrent effects of up-flow velocity (Vup and feed flow rate (QF as independent operating variables on biological hydrogen production were investigated. A broad range of organic loading rate between 10 and 60 g COD L−1 d−1 was used as the operating variables. The dependent parameters as multiple responses were evaluated. Experimental results showed the highest value of yield at 0.31 L H2 g−1 COD was obtained at Vup and QF of 0.5 m h−1 and 1.7 L d−1, respectively. The optimum conditions for the fermentative hydrogen production using pre-settled POME were QF = 2.0–3.7 L d−1 and Vup = 1.5–2.3 m h−1. The experimental results agreed very well with the model prediction.

Massive nitrogen loss from the Benguela upwelling system through anaerobic ammonium oxidation RID B-8834-2011

DEFF Research Database (Denmark)

Kuypers, MMM; Lavik, G.; Woebken, D.

2005-01-01

) and is commonly attributed to denitrification (reduction of nitrate to N-2 by heterotrophic bacteria). Here, we show that instead, the anammox process (the anaerobic oxidation of ammonium by nitrite to yield N-2) is mainly responsible for nitrogen loss in the OMZ waters of one of the most productive regions......In many oceanic regions, growth of phytoplankton is nitrogen-limited because fixation of N-2 cannot make up for the removal of fixed inorganic nitrogen (NH4+, NO2-, and NO3-) by anaerobic microbial processes. Globally, 30-50% of the total nitrogen loss occurs in oxygen-minimum zones (OMZs...... that anammox bacteria are responsible for massive losses of fixed nitrogen. We have identified and directly linked anammox bacteria to the removal of fixed inorganic nitrogen in the OMZ waters of an open-ocean setting. We hypothesize that anammox could also be responsible for substantial nitrogen loss from...

Use of rice husk for the removal of methylene blue in fixed-bed columns

Directory of Open Access Journals (Sweden)

Yurany A. Villada-Villada

2014-08-01

Full Text Available This work shows the use of rice husk in the removal of cationic dye methylene blue on continuous system. A factorial design 23 with center points and random distribution was implemented to evaluate the correlation of the experimental factors in the adsorption process. The considered variables were pH, particle size, salt presence, flow rate, dye initial concentration, and bed depth. The samples were analyzed in defined time intervals. The amount of removed dye was quantified by UV spectroscopy - Visible. Adams-Bohart, Thomas and BDST (Bed-depht/service time analysis models were used to predict the breakthrough curves using non-linear regression and establish the characteristic parameters of the process. It was found that the transference of dye toward the adsorbent is favored by a basic pH, a small particle size, low flow rate and dye concentration, and high bed depth. The design of experiments established that the initial dye concentration and the bed depth were the most significant factors. Regarding the models, the Thomas provided the best fit to describe the breakthrough curves in experimental conditions and Adams-Bohart was found suitable for dynamic behavior limited to the initial part. Finally, BDST model exhibited a good correlation and allowed to establish that bed depth is a determinant factor for scaling process.

Comparison of two anaerobic systems for hydrogen production from the organic fraction of municipal solid waste and synthetic wastewater

Energy Technology Data Exchange (ETDEWEB)

Alzate-Gaviria, Liliana M. [Centro de Investigacion en Energia-UNAM, 62580 Temixco, Morelos (Mexico); Sebastian, P.J. [Centro de Investigacion en Energia-UNAM, 62580 Temixco, Morelos (Mexico); Universidad Politecnica de Chiapas, 29010 Tuxtla Gutierrez, Chiapas (Mexico); Perez-Hernandez, Antonino [Centro de Investigacion en Materiales Avanzados, Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua 31109 (Mexico); Eapen, D. [Universidad Politecnica de Chiapas, 29010 Tuxtla Gutierrez, Chiapas (Mexico)

2007-10-15

Two laboratory scale anaerobic digestion systems for hydrogen production from organic fraction of municipal solid waste (OFMSW) and synthetic wastewater were compared in this study. One of them was formed by a coupled packed bed reactor (PBR) containing 19.4 L of OFMSW and the other an upflow anaerobic sludge bed (UASB) of 3.85 L. The reactors were inoculated with a mixture of non-anaerobic inocula. In the UASB the percentage of hydrogen yield reached 51% v/v and 127NmLH{sub 2}/gvs removed with a hydraulic retention time (HRT) of 24 h. The concentration of synthetic wastewater in the affluent was 7 g COD/L. For the PBR the percentage yield was 47% v/v and 99NmLH{sub 2}/gvs removed with a mass retention time (MRT) of 50 days and the organic load rate of 16 gvs (Grams Volatile Solids)/(kg-day). The UASB and PBR systems presented maximum hydrogen yields of 30% and 23%, respectively, which correspond to 4molH{sub 2}/mol glucose. These values are similar to those reported in the literature for the hydrogen yield (37%) in mesophilic range. The acetic and butyric acids were present in the effluent as by-products in watery phase. In this work we used non-anaerobic inocula made up of microorganism consortium unlike other works where pure inocula or that from anaerobic sludge was used. (author)

Continuous reduction of tellurite to recoverable tellurium nanoparticles using an upflow anaerobic sludge bed (UASB) reactor.

Science.gov (United States)

Ramos-Ruiz, Adriana; Sesma-Martin, Juan; Sierra-Alvarez, Reyes; Field, Jim A

2017-01-01

According to the U.S. Department of Energy and the European Union, tellurium is a critical element needed for energy and defense technology. Thus methods are needed to recover tellurium from waste streams. The objectives of this study was to determine the feasibility of utilizing upflow anaerobic sludge bed (UASB) reactors to convert toxic tellurite (Te IV ) oxyanions to non-toxic insoluble elemental tellurium (Te 0 ) nanoparticles (NP) that are amendable to separation from aqueous effluents. The reactors were supplied with ethanol as the electron donating substrate to promote the biological reduction of Te IV . One reactor was additionally amended with the redox mediating flavonoid compound, riboflavin (RF), with the goal of enhancing the bioreduction of Te IV . Its performance was compared to a control reactor lacking RF. The continuous formation of Te 0 NPs using the UASB reactors was found to be feasible and remarkably improved by the addition of RF. The presence of this flavonoid was previously shown to enhance the conversion rate of Te IV by approximately 11-fold. In this study, we demonstrated that this was associated with the added benefit of reducing the toxic impact of Te IV towards the methanogenic consortium in the UASB and thus enabled a 4.7-fold higher conversion rate of the chemical oxygen demand. Taken as a whole, this work demonstrates the potential of a methanogenic granular sludge to be applied as a bioreactor technology producing recoverable Te 0 NPs in a continuous fashion. Copyright © 2016 Elsevier Ltd. All rights reserved.

Anaerobic ammonium oxidation by anammox bacteria in the Black Sea RID B-8834-2011

DEFF Research Database (Denmark)

Kuypers, MMM; Sliekers, AO; Lavik, G.

2003-01-01

The availability of fixed inorganic nitrogen (nitrate, nitrite and ammonium) limits primary productivity in many oceanic regions(1). The conversion of nitrate to N(2) by heterotrophic bacteria (denitrification) is believed to be the only important sink for fixed inorganic nitrogen in the ocean(2......). Here we provide evidence for bacteria that anaerobically oxidize ammonium with nitrite to N(2) in the world's largest anoxic basin, the Black Sea. Phylogenetic analysis of 16S ribosomal RNA gene sequences shows that these bacteria are related to members of the order Planctomycetales performing...... the anammox (anaerobic ammonium oxidation) process in ammonium-removing bioreactors(3). Nutrient profiles, fluorescently labelled RNA probes, (15)N tracer experiments and the distribution of specific 'ladderane' membrane lipids(4) indicate that ammonium diffusing upwards from the anoxic deep water is consumed...

Carbonaceous materials in petrochemical wastewater before and after treatment in an aerated submerged fixed-bed biofilm reactor

Directory of Open Access Journals (Sweden)

Trojanowicz Karol

2016-09-01

Full Text Available Results of the studies for determining fractions of organic contaminants in a pretreated petrochemical wastewater flowing into a pilot Aerated Submerged Fixed-Bed Biofilm Reactor (ASFBBR are presented and discussed. The method of chemical oxygen demand (COD fractionation consisted of physical tests and biological assays. It was found that the main part of the total COD in the petrochemical, pretreated wastewater was soluble organic substance with average value of 57.6%. The fractions of particulate and colloidal organic matter were found to be 31.8% and 10.6%, respectively. About 40% of COD in the influent was determined as readily biodegradable COD. The inert fraction of the soluble organic matter in the petrochemical wastewater constituted about 60% of the influent colloidal and soluble COD. Determination of degree of hydrolysis (DH of the colloidal fraction of COD was also included in the paper. The estimated value of DH was about 62%. Values of the assayed COD fractions were compared with the same parameters obtained for municipal wastewater by other authors.

Experimental and theoretical studies on hydrogenation of olefins in multiphase fixed bed reactors

Energy Technology Data Exchange (ETDEWEB)

Battsengel, B.; Datsevitch, L.; Jess, A. [Bayreuth Univ. (Germany). Dept. of Chemical Engineering

2003-07-01

Multi phase reactors like trickle bed systems are frequently used for gas-liquid reactions. In general, they have complex mass and heat transfer characteristics; scale-up is therefore difficult. The present work focuses on the role of mass transfer on the effective reaction rate, taking catalytic octene hydrogenation as a model reaction. The reaction rate in a trickle bed reactor is by a factor of about 20 smaller than (theoretically) in the absence of any mass transfer limitations. Based on the experimental results, the so-called pre-saturation concept is presented, where only the liquid saturated with hydrogen is fed into the reactor. The effective reaction rate in this two phase system (liquid and solid cat.) is equal or even higher than in a trickle bed reactor. Scale-up problems do not occur, and the pre-saturation concept has also other advantages (lower energy consumption), as discussed in detail in this paper. (orig.)

Anaerobic treatment with biogas recovery of beverage industry waste water

International Nuclear Information System (INIS)

Cacciari, E.; Zanoni, G.

1992-01-01

This paper briefly describes the application, by a leading Italian non-alcoholic beverage firm, of an up-flow anaerobic sludge blanket process in the treatment of waste water deriving from the production and bottling of beverages. In addition to describing the key design, operation and performance characteristics of the treatment process, the paper focuses on the economic benefits being obtained through the use of the innovative expansive sludge bed anaerobic digestion system which has proven itself to be particularly suitable for the treatment of food and beverage industry liquid wastes. The system, which has already been operating, with good results, for six months, has shown itself to be capable of yielding overall COD removal efficiencies of up to 94.8% and of producing about 0.43 Ncubic meters of biogas per kg of removed COD

Anaerobic treatment with biogas recovery of beverage industry waste water

Energy Technology Data Exchange (ETDEWEB)

Cacciari, E; Zanoni, G [Passavant Impianti, Novate Milanese (Italy)

1992-03-01

This paper briefly describes the application, by a leading Italian non-alcoholic beverage firm, of an up-flow anaerobic sludge blanket process in the treatment of waste water deriving from the production and bottling of beverages. In addition to describing the key design, operation and performance characteristics of the treatment process, the paper focuses on the economic benefits being obtained through the use of the innovative expansive sludge bed anaerobic digestion system which has proven itself to be particularly suitable for the treatment of food and beverage industry liquid wastes. The system, which has already been operating, with good results, for six months, has shown itself to be capable of yielding overall COD removal efficiencies of up to 94.8% and of producing about 0.43 Ncubic meters of biogas per kg of removed COD.

Production of Bioethanol From Lignocellulosic Biomass Using Thermophilic Anaerobic Bacteria

DEFF Research Database (Denmark)

Georgieva, Tania I.

2006-01-01

and xylose and to tolerate the inhibitory compounds present in lignocellulosic hydrolysates is therefore apparent. Several thermophilic anaerobic xylan degrading bacteria from our culture collection (EMB group at BioCentrum-DTU) have been screened for a potential ethanol producer from hemicellulose...... hydrolysates, and out of the screening test, one particular strain (A10) was selected for the best performance. The strain was morphologically and physiologically characterized as Thermoanaerobacter mathranii strain A10. Unlike other thermophilic anaerobic bacteria, the wild-type strain Thermoanaerobacter...... Thermoanaerobacter BG1L1 was further studied. The experiments were carried out in a continuous immobilized reactor system (a fluidized bed reactor), which is likely to be the process design configuration for xylose fermentation in a Danish biorefinery concept for production of fuel ethanol. The immobilization...

Systematic staging design applied to the fixed-bed reactor series for methanol and one-step methanol/dimethyl ether synthesis

International Nuclear Information System (INIS)

Manenti, Flavio; Leon-Garzon, Andres R.; Ravaghi-Ardebili, Zohreh; Pirola, Carlo

2014-01-01

This work investigates possible design advances in the series of fixed-bed reactors for methanol and dimethyl ether synthesis. Specifically, the systematic staging design proposed by Hillestad [1] is applied to the water-cooled and gas-cooled series of reactors of Lurgi's technology. The procedure leads to new design and operating conditions with respect to the current best industrial practice, with relevant benefits in terms of process yield, energy saving, and net income. The overall mathematical model for the process simulation and optimization is reported in the work together with dedicated sensitivity analysis studies. - Highlights: • Systematic staging design is applied to methanol and methanol/DME synthesis. • New configurations for the synthesis reactor network are proposed and assessed. • Comparison with the industrial best practice is provided. • Energy-process optimization is performed to improve the overall yield of the process

Comparative Evaluation of Anaerobic Bacterial Communities Associated with Roots of Submerged Macrophytes Growing in Marine or Brackish Water Sediments

Science.gov (United States)

Sediment microbial communities are important for seagrass growth and carbon cycling, however relatively few studies have addressed the composition of prokaryotic communities in seagrass bed sediments. Selective media were used enumerate culturable anaerobic bacteria associated ...

Start-up of a sequential dry anaerobic digestion of paunch under psychrophilic and mesophilic temperatures.

Science.gov (United States)

Nkemka, Valentine Nkongndem; Hao, Xiying

2018-04-01

The present laboratory study evaluated the sequential leach bed dry anaerobic digestion (DAD) of paunch under psychrophilic (22°C) and mesophilic (40°C) temperatures. Three leach bed reactors were operated under the mesophilic temperature in sequence at a solid retention time (SRT) of 40d with a new batch started 27d into the run of the previous one. A total of six batches were operated for 135d. The results showed that the mesophilic DAD of paunch was efficient, reaching methane yields of 126.9-212.1mLg -1 volatile solid (VS) and a VS reduction of 32.9-55.5%. The average daily methane production rate increased from 334.3mLd -1 to 571.4mLd -1 and 825.7mLd -1 when one, two and three leach bed reactors were in operation, respectively. The psychrophilic DAD of paunch was operated under a SRT of 100d and a total of three batches were performed in sequence for 300d with each batch starting after completion of the previous one. Improvements in the methane yield from 93.9 to 107.3 and 148.3mLg -1 VS and VS reductions of 24.8, 30.2 and 38.6% were obtained in the consecutive runs, indicating the adaptation of anaerobic microbes from mesophilic to psychrophilic temperatures. In addition, it took three runs for anaerobic microbes to reduce the volatile fatty acid accumulation observed in the first and second trials. This study demonstrates the potential of renewable energy recovery from paunch under psychrophilic and mesophilic temperatures. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Effect of vitamin B12 pulse addition on the performance of cobalt deprived anaerobic granular sludge bioreactors

KAUST Repository

Fermoso, Fernando G.; Bartacek, Jan; Lens, Piet N.L.

2010-01-01

The effect of a pulse addition of vitamin B12 as cobalt source to restore the performance of cobalt depleted methanol-fed bioreactors was investigated. One upflow anaerobic sludge bed (UASB) reactor was supplied with a pulse of vitamin B12, and its

Activated Carbon Adsorption Characteristics of Multi-component Volatile Organic compounds in a Fixed Bed Adsorption Bed

Energy Technology Data Exchange (ETDEWEB)

Cho, Jong Hoon; Rhee, Young Woo [Chungnam National University, Daejeon (Korea, Republic of); Lee, Sihyun [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

2016-04-15

This study aims to examine absorption characteristics of toluene, isopropyl alcohol (IPA), ethyl acetate (EA), and ternary-compounds, all of which are widely used in industrial processes, by means of four types of commercial activated carbon substances. It turned out that among the three types of volatile organic compounds, the breakthrough point of activated carbon and that of IPA, whose affinity was the lowest, were the lowest, and then that of EA and that of toluene in the order. With the breakthrough point of IPA, which was the shortest, as the standard, changes in the breakthrough points of unary-compounds, binary-compounds, and ternary-compounds were examined. As a result, it turned out that the larger the number of elements, the lower the breakthrough point. This resulted from competitive adsorption, that is, substitution of substances with a low level of affinity with those with a high level of affinity. Hence, the adsorption of toluene-IPA-EA and ternary-compounds require a design of the activated carbon bed based on the breakthrough of IPA, and in the design of activated carbon beds in actual industries as well, a substance whose level of affinity is the lowest needs to be the standard.

ANAEROBIC BIOLOGICAL TREATMENT OF PRODUCED WATER

Energy Technology Data Exchange (ETDEWEB)

John R. Gallagher

2001-07-31

During the production of oil and gas, large amounts of water are brought to the surface and must be disposed of in an environmentally sensitive manner. This is an especially difficult problem in offshore production facilities where space is a major constraint. The chief regulatory criterion for produced water is oil and grease. Most facilities have little trouble meeting this criterion using conventional oil-water separation technologies. However, some operations have significant amounts of naphthenic acids in the water that behave as oil and grease but are not well removed by conventional technologies. Aerobic biological treatment of naphthenic acids in simulated-produced water has been demonstrated by others; however, the system was easily overloaded by the large amounts of low-molecular-weight organic acids often found in produced waters. The objective of this research was to determine the ability of an anaerobic biological system to treat these organic acids in a simulated produced water and to examine the potential for biodegradation of the naphthenic acids in the anaerobic environment. A small fixed-film anaerobic biological reactor was constructed and adapted to treat a simulated produced water. The bioreactor was tubular, with a low-density porous glass packing material. The inocula to the reactor was sediment from a produced-water holding pond from a municipal anaerobic digester and two salt-loving methanogenic bacteria. During start-up, the feed to the reactor contained glucose as well as typical produced-water components. When glucose was used, rapid gas production was observed. However, when glucose was eliminated and the major organic component was acetate, little gas was generated. Methane production from acetate may have been inhibited by the high salt concentrations, by sulfide, or because of the lack, despite seeding, of microbes capable of converting acetate to methane. Toluene, a minor component of the produced water (0.1 g/L) was removed in the

Artificial neural network modelling approach for a biomass gasification process in fixed bed gasifiers

International Nuclear Information System (INIS)

Mikulandrić, Robert; Lončar, Dražen; Böhning, Dorith; Böhme, Rene; Beckmann, Michael

2014-01-01

Highlights: • 2 Different equilibrium models are developed and their performance is analysed. • Neural network prediction models for 2 different fixed bed gasifier types are developed. • The influence of different input parameters on neural network model performance is analysed. • Methodology for neural network model development for different gasifier types is described. • Neural network models are verified for various operating conditions based on measured data. - Abstract: The number of the small and middle-scale biomass gasification combined heat and power plants as well as syngas production plants has been significantly increased in the last decade mostly due to extensive incentives. However, existing issues regarding syngas quality, process efficiency, emissions and environmental standards are preventing biomass gasification technology to become more economically viable. To encounter these issues, special attention is given to the development of mathematical models which can be used for a process analysis or plant control purposes. The presented paper analyses possibilities of neural networks to predict process parameters with high speed and accuracy. After a related literature review and measurement data analysis, different modelling approaches for the process parameter prediction that can be used for an on-line process control were developed and their performance were analysed. Neural network models showed good capability to predict biomass gasification process parameters with reasonable accuracy and speed. Measurement data for the model development, verification and performance analysis were derived from biomass gasification plant operated by Technical University Dresden

Autotrophic denitrification of synthetic nitrate-contaminated groundwater in up-flow fixed-bed bioreactor by pumice as porous media

Directory of Open Access Journals (Sweden)

Masoud Tourang1

2018-05-01

Full Text Available Background: Background: Increasing nitrate concentrations in groundwater resources is considered a common environmental and public health problem worldwide. In this research, an autotrophic up-flow bioreactor with pumice as media was used to study the effects of the sulfur-to-nitrogen (S/N ratio and empty bed contact time (EBCT on nitrate removal efficiency and byproducts. Methods: Experiments were carried out in a 3.47 L up-flow, fixed-bed reactor with 3 sampling ports. To evaluate the overall impact of S/N ratio and EBCT on the performance of the bioreactor, several phases with different S/N ratios and EBCTs were applied. Results: At a constant S/N ratio of 3.85 g/g, as EBCT decreased from 24 hours to 2 hours, the nitrate removal efficiency decreased from 98% to 64%. On the other hand, at the desired EBCT of 4 hr, as S/N ratio decreased from 3.85 to 1.51 g/g, nitrate removal efficiency was reduced from 85% to 32%. Changing the EBCT and S/N ratio also affected the effluent nitrite and sulfate concentrations as byproducts. At the S/N ratio of 3.85 g/g and EBCT of 24 hours, effluent nitrite and sulfate concentrations were 0.1 mg NO2--N/L and 463 mg SO4 2-/L, respectively. Decreasing the S/N ratio to 1.51 g/g and the EBCT to 4 hours caused drastic changes in effluent nitrite and sulfate concentrations. Conclusion: The results indicated that the autotrophic denitrification with thiosulfate as electron donor and pumice as media was feasible and applicable for nitrate contaminated groundwater.

Forces on stationary particles in near-bed turbulent flows

Science.gov (United States)

Schmeeckle, Mark W.; Nelson, Jonathan M.; Shreve, Ronald L.

2007-06-01

In natural flows, bed sediment particles are entrained and moved by the fluctuating forces, such as lift and drag, exerted by the overlying flow on the particles. To develop a better understanding of these forces and the relation of the forces to the local flow, the downstream and vertical components of force on near-bed fixed particles and of fluid velocity above or in front of them were measured synchronously at turbulence-resolving frequencies (200 or 500 Hz) in a laboratory flume. Measurements were made for a spherical test particle fixed at various heights above a smooth bed, above a smooth bed downstream of a downstream-facing step, and in a gravel bed of similarly sized particles as well as for a cubical test particle and 7 natural particles above a smooth bed. Horizontal force was well correlated with downstream velocity and not correlated with vertical velocity or vertical momentum flux. The standard drag formula worked well to predict the horizontal force, but the required value of the drag coefficient was significantly higher than generally used to model bed load motion. For the spheres, cubes, and natural particles, average drag coefficients were found to be 0.76, 1.36, and 0.91, respectively. For comparison, the drag coefficient for a sphere settling in still water at similar particle Reynolds numbers is only about 0.4. The variability of the horizontal force relative to its mean was strongly increased by the presence of the step and the gravel bed. Peak deviations were about 30% of the mean force for the sphere over the smooth bed, about twice the mean with the step, and 4 times it for the sphere protruding roughly half its diameter above the gravel bed. Vertical force correlated poorly with downstream velocity, vertical velocity, and vertical momentum flux whether measured over or ahead of the test particle. Typical formulas for shear-induced lift based on Bernoulli's principle poorly predict the vertical forces on near-bed particles. The

Modelling of N2O Reduction in a Circulating Fluidized Bed Boiler

DEFF Research Database (Denmark)

Johnsson, Jan Erik; Åmand, Lars Erik; Dam-Johansen, Kim

1996-01-01

The addition of limestone for sulphur retention in Fluidized Bed Combustion (FBC) has been observed to influence the emission of N2O, and in many cases a lower emission was observed. The catalytic activity of a Danish limestone (Stevns Chalk) for decomposition of N2O in a laboratory fixed bed qua...

Wave Driven Fluid-Sediment Interactions over Rippled Beds

Science.gov (United States)

Foster, Diane; Nichols, Claire

2008-11-01

Empirical investigations relating vortex shedding over rippled beds to oscillatory flows date back to Darwin in 1883. Observations of the shedding induced by oscillating forcing over fixed beds have shown vortical structures to reach maximum strength at 90 degrees when the horizontal velocity is largest. The objective of this effort is to examine the vortex generation and ejection over movable rippled beds in a full-scale, free surface wave environment. Observations of the two-dimensional time-varying velocity field over a movable sediment bed were obtained with a submersible Particle Image Velocimetry (PIV) system in two wave flumes. One wave flume was full scale and had a natural sand bed and the other flume had an artificial sediment bed with a specific gravity of 1.6. Full scale observations over an irregularly rippled bed show that the vortices generated during offshore directed flow over the steeper bed form slope were regularly ejected into the water column and were consistent with conceptual models of the oscillatory flow over a backward facing step. The results also show that vortices remain coherent during ejection when the background flow stalls (i.e. both the velocity and acceleration temporarily approach zero). These results offer new insight into fluid sediment interaction over rippled beds.

Biofilm development in fixed bed biofilm reactors: experiments and simple models for engineering design purposes.

Science.gov (United States)

Szilágyi, N; Kovács, R; Kenyeres, I; Csikor, Zs

2013-01-01

Biofilm development in a fixed bed biofilm reactor system performing municipal wastewater treatment was monitored aiming at accumulating colonization and maximum biofilm mass data usable in engineering practice for process design purposes. Initially a 6 month experimental period was selected for investigations where the biofilm formation and the performance of the reactors were monitored. The results were analyzed by two methods: for simple, steady-state process design purposes the maximum biofilm mass on carriers versus influent load and a time constant of the biofilm growth were determined, whereas for design approaches using dynamic models a simple biofilm mass prediction model including attachment and detachment mechanisms was selected and fitted to the experimental data. According to a detailed statistical analysis, the collected data have not allowed us to determine both the time constant of biofilm growth and the maximum biofilm mass on carriers at the same time. The observed maximum biofilm mass could be determined with a reasonable error and ranged between 438 gTS/m(2) carrier surface and 843 gTS/m(2), depending on influent load, and hydrodynamic conditions. The parallel analysis of the attachment-detachment model showed that the experimental data set allowed us to determine the attachment rate coefficient which was in the range of 0.05-0.4 m d(-1) depending on influent load and hydrodynamic conditions.

An Exploratory Study on the Pathways of Cr (VI) Reduction in Sulfate-reducing Up-flow Anaerobic Sludge Bed (UASB) Reactor.

Science.gov (United States)

Qian, Jin; Wei, Li; Liu, Rulong; Jiang, Feng; Hao, Xiaodi; Chen, Guang-Hao

2016-03-29

Electroplating wastewater contains both Cr (VI) and sulfate. So Cr (VI) removal under sulfate-rich condition is quite complicated. This study mainly investigates the pathways for Cr (VI) removal under biological sulfate-reducing condition in the up-flow anaerobic sludge bed (UASB) reactor. Two potential pathways are found for the removal of Cr (VI). The first one is the sulfidogenesis-induced Cr (VI) reduction pathway (for 90% Cr (VI) removal), in which Cr (VI) is reduced by sulfide generated from biological reduction of sulfate. The second one leads to direct reduction of Cr (VI) which is utilized by bacteria as the electron acceptor (for 10% Cr (VI) removal). Batch test results confirmed that sulfide was oxidized to elemental sulfur instead of sulfate during Cr (VI) reduction. The produced extracellular polymeric substances (EPS) provided protection to the microbes, resulting in effective removal of Cr (VI). Sulfate-reducing bacteria (SRB) genera accounted for 11.1% of the total bacterial community; thus they could be the major organisms mediating the sulfidogenesis-induced reduction of Cr (VI). In addition, chromate-utilizing genera (e.g. Microbacterium) were also detected, which were possibly responsible for the direct reduction of Cr (VI) using organics as the electron donor and Cr (VI) as the electron acceptor.

An Exploratory Study on the Pathways of Cr (VI) Reduction in Sulfate-reducing Up-flow Anaerobic Sludge Bed (UASB) Reactor

Science.gov (United States)

Qian, Jin; Wei, Li; Liu, Rulong; Jiang, Feng; Hao, Xiaodi; Chen, Guang-Hao

2016-01-01

Electroplating wastewater contains both Cr (VI) and sulfate. So Cr (VI) removal under sulfate-rich condition is quite complicated. This study mainly investigates the pathways for Cr (VI) removal under biological sulfate-reducing condition in the up-flow anaerobic sludge bed (UASB) reactor. Two potential pathways are found for the removal of Cr (VI). The first one is the sulfidogenesis-induced Cr (VI) reduction pathway (for 90% Cr (VI) removal), in which Cr (VI) is reduced by sulfide generated from biological reduction of sulfate. The second one leads to direct reduction of Cr (VI) which is utilized by bacteria as the electron acceptor (for 10% Cr (VI) removal). Batch test results confirmed that sulfide was oxidized to elemental sulfur instead of sulfate during Cr (VI) reduction. The produced extracellular polymeric substances (EPS) provided protection to the microbes, resulting in effective removal of Cr (VI). Sulfate-reducing bacteria (SRB) genera accounted for 11.1% of the total bacterial community; thus they could be the major organisms mediating the sulfidogenesis-induced reduction of Cr (VI). In addition, chromate-utilizing genera (e.g. Microbacterium) were also detected, which were possibly responsible for the direct reduction of Cr (VI) using organics as the electron donor and Cr (VI) as the electron acceptor. PMID:27021522

An Exploratory Study on the Pathways of Cr (VI) Reduction in Sulfate-reducing Up-flow Anaerobic Sludge Bed (UASB) Reactor

Science.gov (United States)

Qian, Jin; Wei, Li; Liu, Rulong; Jiang, Feng; Hao, Xiaodi; Chen, Guang-Hao

2016-03-01

Electroplating wastewater contains both Cr (VI) and sulfate. So Cr (VI) removal under sulfate-rich condition is quite complicated. This study mainly investigates the pathways for Cr (VI) removal under biological sulfate-reducing condition in the up-flow anaerobic sludge bed (UASB) reactor. Two potential pathways are found for the removal of Cr (VI). The first one is the sulfidogenesis-induced Cr (VI) reduction pathway (for 90% Cr (VI) removal), in which Cr (VI) is reduced by sulfide generated from biological reduction of sulfate. The second one leads to direct reduction of Cr (VI) which is utilized by bacteria as the electron acceptor (for 10% Cr (VI) removal). Batch test results confirmed that sulfide was oxidized to elemental sulfur instead of sulfate during Cr (VI) reduction. The produced extracellular polymeric substances (EPS) provided protection to the microbes, resulting in effective removal of Cr (VI). Sulfate-reducing bacteria (SRB) genera accounted for 11.1% of the total bacterial community; thus they could be the major organisms mediating the sulfidogenesis-induced reduction of Cr (VI). In addition, chromate-utilizing genera (e.g. Microbacterium) were also detected, which were possibly responsible for the direct reduction of Cr (VI) using organics as the electron donor and Cr (VI) as the electron acceptor.

Inhibitors degradation and microbial response during continuous anaerobic conversion of hydrothermal liquefaction wastewater.

Science.gov (United States)

Si, Buchun; Li, Jiaming; Zhu, Zhangbing; Shen, Mengmeng; Lu, Jianwen; Duan, Na; Zhang, Yuanhui; Liao, Qiang; Huang, Yun; Liu, Zhidan

2018-07-15

One critical challenge of hydrothermal liquefaction (HTL) is its complex aqueous product, which has a high concentration of organic pollutants (up to 100gCOD/L) and diverse fermentation inhibitors, such as furfural, phenolics and N-heterocyclic compounds. Here we report continuous anaerobic digestion of HTL wastewater via an up-flow anaerobic sludge bed reactor (UASB) and packed bed reactor (PBR). Specifically, we investigated the transformation of fermentation inhibitors and microbial response. GC-MS identified the complete degradation of furfural and 5-hydroxymethylfurfural (5-HMF), and partial degradation (54.0-74.6%) of organic nitrogen and phenolic compounds, including 3-hydroxypyridine, phenol and 4-ethyl-phenol. Illumina MiSeq sequencing revealed that the bacteria families related to detoxification increased in response to the HTL aqueous phase. In addition, the increase of acetate-oxidizing bacteria in UASB and acetogens in PBR showed a strengthened acetogenesis. As for the archaeal communities, an increase in hydrogenotrophic methanogens was observed. Based on GC-MS/HPLC and microbial analysis, we speculate that dominant fermentation inhibitors were transformed into intermediates (Acetyl-CoA and acetate), further contributing to biomethane formation. Copyright © 2018 Elsevier B.V. All rights reserved.

Assessing effects of aerobic and anaerobic conditions on phosphorus sorption and retention capacity of water treatment residuals.

Science.gov (United States)

Oliver, Ian W; Grant, Cameron D; Murray, Robert S

2011-03-01

Water treatment residuals (WTRs) are the by-products of drinking water clarification processes, whereby chemical flocculants such as alum or ferric chloride are added to raw water to remove suspended clay particles, organic matter and other materials and impurities. Previous studies have identified a strong phosphorus (P) fixing capacity of WTRs which has led to experimentation with their use as P-sorbing materials for controlling P discharges from agricultural and forestry land. However, the P-fixing capacity of WTRs and its capacity to retain sorbed P under anaerobic conditions have yet to be fully demonstrated, which is an issue that must be addressed for WTR field applications. This study therefore examined the capacity of WTRs to retain sorbed P and sorb further additional P from aqueous solution under both aerobic and anaerobic conditions. An innovative, low cost apparatus was constructed and successfully used to rapidly establish anoxic conditions in anaerobic treatments. The results showed that even in treatments with initial solution P concentrations set at 100 mg l(-1), soluble reactive P concentrations rapidly fell to negligible levels (due to sorption by WTRs), while total P (i.e. dissolved + particulate and colloidal P) was less than 3 mg l(-1). This equated to an added P retention rate of >98% regardless of anaerobic or aerobic status, indicating that WTRs are able to sorb and retain P in both aerobic and anaerobic conditions. Copyright © 2010 Elsevier Ltd. All rights reserved.

Impact of acclimation methods on microbial communities and performance of anaerobic fluidized bed membrane bioreactors

KAUST Repository

Labarge, Nicole; Ye, Yaoli; Kim, Kyoung Yeol; Yilmazel, Yasemin Dilsad; Saikaly, Pascal; Hong, Pei-Ying; Logan, Bruce E.

2016-01-01

of the granular activated carbon (GAC) used in the reactor were examined here to determine their impact on chemical oxygen demand (COD) removal and microbial community composition of domestic wastewater-fed AFMBRs. AFMBRs inoculated with anaerobic digester sludge

Two phases fermentative process for hydrogen and methane production from cassava wastewater

Directory of Open Access Journals (Sweden)

Aryane Mota Oliveira

2017-04-01

Full Text Available Introduction: Hydrogen and methane production was investigated in two phases of fermentative process. Objective: At the acidogenic phase, an anaerobic fluidized bed reactor was fed with cassava wastewater producing hydrogen. Methods: Expanded clay was used as a support material for biomass immobilization. The reactor was operated with HRT ranging from 8-1 h. Results: The best hydrogen yield production was 1.91 mol H2/mol glucose at HRT of 2 h. At the methanogenic phase, the acidogenic process effluent fed a fixed-bed reactor producing methane. Conclusion: Sururu (Mytella falcata shells was used as support acted as pH neutralizer in the fixed-bed reactor, yielding best (0.430±0.150 Lmethane/gCOD with 12h HRT phase.

Study of the obtainment of Mo{sub 2}C by gas-solid reaction in a fixed and rotary bed reactor; Estudo da obtencao de Mo{sub 2}C por reacao gas-solido em reator de leito fixo e rotativo

Energy Technology Data Exchange (ETDEWEB)

Araujo, C.P.B. de; Souza, C.P. de; Souto, M.V.M.; Barbosa, C.M.; Frota, A.V.V.M., E-mail: cpbaraujo@gmail.com [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

2016-07-01

Carbides' synthesis via gas-solid reaction overcomes many of the difficulties found in other processes, requiring lower temperatures and reaction times than traditional metallurgic routes, for example. In carbides' synthesis in fixed bed reactors (FB) the solid precursor is permeated by the reducing/carburizing gas stream forming a packed bed without mobility. The use of a rotary kiln reactor (RK) adds a mixing character to this process, changing its fluid-particle dynamics. In this work ammonium molybdate was subjected to carbo-reduction reaction (CH4 / H2) in both reactors under the same gas flow (15L / h) and temperature (660 ° C) for 180 minutes. Complete conversion was observed Mo2C (dp = 18.9nm modal particles sizes' distribution) in the fixed bed reactor. In the RK reactor this conversion was only partial (∼ 40%) and Mo2C and MoO3 (34nm dp = bimodal) could be observed on the produced XRD pattern. Partial conversion was attributed to the need to use higher solids loading in the reactor CR (50% higher) to avoid solids to centrifuge. (author)

Closing the Loop by Combining UASB Reactor and Reactive Bed Filetr Technology for wastewater Treatment : Modelling and Practical Approaches

OpenAIRE

Rodríguez-Gómez, Raúl

2016-01-01

A laboratory-scale upflow anaerobic sludge blanket (UASB) reactor followed by a packed bed reactor (PBR) filled with Sorbulite® in the lower part and Polonite® in the upper part was used to treat household wastewater in a 50-week experiment. A model was developed to describe the performance of the UASB reactor, including mass transfer through the film around anaerobic granules, intra-particle diffusion and bioconversion of the substrate. In a second model, a numerical expression describing th...

Improving hydrolysis of food waste in a leach bed reactor

Energy Technology Data Exchange (ETDEWEB)

Browne, James D.; Allen, Eoin; Murphy, Jerry D., E-mail: jerry.murphy@ucc.ie

2013-11-15

Highlights: • This paper assesses leaching of food waste in a two phase digestion system. • Leaching is assessed with and without an upflow anaerobic sludge blanket (UASB). • Without the UASB, low pH reduces hydrolysis, while increased flows increase leaching. • Inclusion of the UASB increases pH to optimal levels and greatly improves leaching. • The optimal conditions are suggested as low flow with connection to the UASB. - Abstract: This paper examines the rate of degradation of food waste in a leach bed reactor (LBR) under four different operating conditions. The effects of leachate recirculation at a low and high flow rate are examined with and without connection to an upflow anaerobic sludge blanket (UASB). Two dilution rates of the effective volume of the leach bed reactors were investigated: 1 and 6 dilutions per LBR per day. The increase in dilution rate from 1 to 6 improved the destruction of volatile solids without connection to the UASB. However connection to the UASB greatly improved the destruction of volatile solids (by almost 60%) at the low recirculation rate of 1 dilution per day. The increase in volatile solids destruction with connection to the UASB was attributed to an increase in leachate pH and buffering capacity provided by recirculated effluent from the UASB to the leach beds. The destruction of volatile solids for both the low and high dilution rates was similar with connection to the UASB, giving 82% and 88% volatile solids destruction respectively. This suggests that the most efficient leaching condition is 1 dilution per day with connection to the UASB.

Improving hydrolysis of food waste in a leach bed reactor

International Nuclear Information System (INIS)

Browne, James D.; Allen, Eoin; Murphy, Jerry D.

2013-01-01

Highlights: • This paper assesses leaching of food waste in a two phase digestion system. • Leaching is assessed with and without an upflow anaerobic sludge blanket (UASB). • Without the UASB, low pH reduces hydrolysis, while increased flows increase leaching. • Inclusion of the UASB increases pH to optimal levels and greatly improves leaching. • The optimal conditions are suggested as low flow with connection to the UASB. - Abstract: This paper examines the rate of degradation of food waste in a leach bed reactor (LBR) under four different operating conditions. The effects of leachate recirculation at a low and high flow rate are examined with and without connection to an upflow anaerobic sludge blanket (UASB). Two dilution rates of the effective volume of the leach bed reactors were investigated: 1 and 6 dilutions per LBR per day. The increase in dilution rate from 1 to 6 improved the destruction of volatile solids without connection to the UASB. However connection to the UASB greatly improved the destruction of volatile solids (by almost 60%) at the low recirculation rate of 1 dilution per day. The increase in volatile solids destruction with connection to the UASB was attributed to an increase in leachate pH and buffering capacity provided by recirculated effluent from the UASB to the leach beds. The destruction of volatile solids for both the low and high dilution rates was similar with connection to the UASB, giving 82% and 88% volatile solids destruction respectively. This suggests that the most efficient leaching condition is 1 dilution per day with connection to the UASB

ANAEROBIC BIOLOGICAL TREATMENT OF PRODUCED WATER; TOPICAL

International Nuclear Information System (INIS)

John R. Gallagher

2001-01-01

During the production of oil and gas, large amounts of water are brought to the surface and must be disposed of in an environmentally sensitive manner. This is an especially difficult problem in offshore production facilities where space is a major constraint. The chief regulatory criterion for produced water is oil and grease. Most facilities have little trouble meeting this criterion using conventional oil-water separation technologies. However, some operations have significant amounts of naphthenic acids in the water that behave as oil and grease but are not well removed by conventional technologies. Aerobic biological treatment of naphthenic acids in simulated-produced water has been demonstrated by others; however, the system was easily overloaded by the large amounts of low-molecular-weight organic acids often found in produced waters. The objective of this research was to determine the ability of an anaerobic biological system to treat these organic acids in a simulated produced water and to examine the potential for biodegradation of the naphthenic acids in the anaerobic environment. A small fixed-film anaerobic biological reactor was constructed and adapted to treat a simulated produced water. The bioreactor was tubular, with a low-density porous glass packing material. The inocula to the reactor was sediment from a produced-water holding pond from a municipal anaerobic digester and two salt-loving methanogenic bacteria. During start-up, the feed to the reactor contained glucose as well as typical produced-water components. When glucose was used, rapid gas production was observed. However, when glucose was eliminated and the major organic component was acetate, little gas was generated. Methane production from acetate may have been inhibited by the high salt concentrations, by sulfide, or because of the lack, despite seeding, of microbes capable of converting acetate to methane. Toluene, a minor component of the produced water (0.1 g/L) was removed in the

[Anaerobic bacteria isolated from patients with suspected anaerobic infections].

Science.gov (United States)

Ercis, Serpil; Tunçkanat, Ferda; Hasçelik, Gülşen

2005-10-01

The study involved 394 clinical samples sent to the Clinical Microbiology Laboratory of Hacettepe University Adult Hospital between January 1997 and May 2004 for anaerobic cultivation. Since multiple cultures from the same clinical samples of the same patient were excluded, the study was carried on 367 samples. The anaerobic cultures were performed in anaerobic jar using AnaeroGen kits (Oxoid, Basingstoke, U.K.) or GENbox (bioMérieux, Lyon, France). The isolates were identified by both classical methods and "BBL Crystal System" (Becton Dickinson, U.S.A.). While no growth was detected in 120 (32.7%) of the clinical samples studied, in 144 samples (39.2%) only aerobes, in 28 (7.6%) only anaerobes and in 75 (20.5%) of the samples both aerobes and anaerobes were isolated. The number of the anaerobic isolates was 217 from 103 samples with anaerobic growth. Of these 103 samples 15 showed single bacterial growth whereas in 88 samples multiple bacterial isolates were detected. Anaerobic isolates consisted of 92 Gram negative bacilli (Bacteroides spp. 50, Prevotella spp. 14, Porphyromonas spp. 10, Fusobacterium spp. 7, Tisierella spp. 2, unidentified 9), 57 Gram positive bacilli (Clostridium spp.17, Propionibacterium spp. 16, Lactobacillus spp. 8, Actinomyces spp. 5, Eubacterium spp. 2, Bifidobacterium adolescentis 1, Mobiluncus mulieris 1, unidentified nonspore forming rods 7), 61 Gram positive cocci (anaerobic cocci 44, microaerophilic cocci 17), and 7 Gram negative cocci (Veillonella spp.). In conclusion, in the samples studied with prediagnosis of anaerobic infection, Bacteroides spp. (23%) were the most common bacteria followed by anaerobic Gram positive cocci (20.3%) and Clostridium spp (7.8%).

Dissolved oxygen control in a coupled fluidized bed system

International Nuclear Information System (INIS)

Jones, R.M.; Melcer, H.

1988-01-01

The biological fluidized bed process is a modification of more conventional fixed film processes, such as the trickling filter, in which wastewater is passed upward through a bed of granular support medium, typically sand, at a sufficient velocity to expand or fluidize the medium. The granular medium provides a large surface area for the establishment of a biological film. The fluidized bed process was selected to investigate the treatment of coking plant wastewaters in view of the significant advantages offered in terms of reduced reactor volumes that result from the high biomass concentration maintained on the support medium. The technical feasibility of treating coal distillation condensates was evaluated during a 3-year study at Environment Canada's Wastewater Technology Centre (WTC). The feed to the pilot scale test system consisted of effluent from fixed and free leg ammonia stills at the by-product coke plant of Dofasco Inc. in Hamilton, Ontario. The pilot plant consisted of two fluidized bed reactors in series, coupled to provide carbon oxidation, nitrification and denitrification in the predenitrification operating mode. The anoxic denitrification reactor was 115 mm in diameter and the oxygenic nitrification reactor, 290 mm in diameter. The bed heights and reactor volumes were adjustable by relocation of the position of the sand/biomass wasting valve. The experimental objective of this research was to determine those operating conditions required to maintain stable nitrification and complete denitrification under both steady state and dynamic operating conditions. Details regarding operating, sampling and analytic procedures have been presented elsewhere. A specific operating problem existed relating to the control of the dissolved oxygen concentration in the oxygenic fluidized bed reactor, the solution of which forms the basis of the paper

Effects of Temperature and Residence Time on the Emissions of PIC and Fine Particles during Fixed Bed Combustion of Conifer Stemwood Pellets

Energy Technology Data Exchange (ETDEWEB)

Boman, Christoffer; Lindmark, Fredrik; Oehman, Marcus; Nordin, Anders [Umeaa Univ. (Sweden). Energy Technology and Thermal Process Chemistry; Pettersson, Esbjoern [Energy Technology Centre, Piteaa (Sweden); Westerholm, Roger [Stockholm Univ., Arrhenius Laboratory (Sweden). Dept. of Analytical Chemistry

2006-07-15

The use of wood fuel Pellets has proved to be well suited for the small-scale market enabling controlled and efficient combustion with low emission of products of incomplete combustion (PIC). Still a potential for further emission reduction exists and a thorough understanding of the influence of combustion conditions on the emission characteristics of air pollutants like PAH and particulate matter (PM) is important. The objective was to determine the effects of temperature and residence time on the emission performance and characteristics with focus on hydrocarbons and PM during combustion of conifer stemwood Pellets in a laboratory fixed bed reactor (<5 kW). Temperature and residence time after the bed section were varied according to statistical experimental designs (650-970 deg C and 0.5-3.5 s) with the emission responses; CO, organic gaseous carbon, NO, 20 VOC compounds, 43 PAH compounds, PM{sub tot}, fine particle mass/count median diameter (MMD and CMD) and number concentration. Temperature was negatively correlated with the emissions of all studied PIC with limited effects of residence time. The PM{sub tot} emissions of 15-20 mg/MJ was in all cases dominated by fine (<1 {mu}m) particles of K, Na, S, Cl, C, O and Zn. Increased residence time resulted in increased fine particle sizes (i.e. MMD and CMD) and decreased number concentrations. The importance of high temperature (>850 deg C) in the bed zone with intensive, air rich and well mixed isothermal conditions for 0.5-1.0 s in the post combustion zone was illustrated for wood Pellets combustion with almost a total depletion of all studied PIC. The results emphasize the need for further verification studies and technology development work.

Aerobic exercise deconditioning and countermeasures during bed rest.

Science.gov (United States)

Lee, Stuart M C; Moore, Alan D; Everett, Meghan E; Stenger, Michael B; Platts, Steven H

2010-01-01

Bed rest is a well-accepted model for spaceflight in which the physiologic adaptations, particularly in the cardiovascular system, are studied and potential countermeasures can be tested. Bed rest without countermeasures results in reduced aerobic capacity and altered submaximal exercise responses. Aerobic endurance and factors which may impact prolonged exercise, however, have not been well studied. The initial loss of aerobic capacity is rapid, occurring in parallel with the loss of plasma volume. Thereafter, the reduction in maximal aerobic capacity proceeds more slowly and is influenced by central and peripheral adaptation. Exercise capacity can be maintained during bed rest and may be improved during recovery with appropriate countermeasures. Plasma volume restoration, resistive exercise, orthostatic stress, aerobic exercise, and aerobic exercise plus orthostatic stress all have been tested with varying levels of success. However, the optimal combination of elements-exercise modality, intensity, duration, muscle groups exercised and frequency of aerobic exercise, orthostatic stress, and supplementary resistive or anaerobic exercise training-has not been systematically evaluated. Currently, frequent (at least 3 days per week) bouts of intense exercise (interval-style and near maximal) with orthostatic stress appears to be the most efficacious method to protect aerobic capacity during bed rest. Further refinement of protocols and countermeasure hardware may be necessary to insure the success of countermeasures in the unique environment of space.

Single and multi-component adsorption of salicylic acid, clofibric acid, carbamazepine and caffeine from water onto transition metal modified and partially calcined inorganic-organic pillared clay fixed beds.

Science.gov (United States)

Cabrera-Lafaurie, Wilman A; Román, Félix R; Hernández-Maldonado, Arturo J

2015-01-23

Fixed-beds of transition metal (Co(2+), Ni(2+) or Cu(2+)) inorganic-organic pillared clays (IOCs) were prepared to study single- and multi-component non-equilibrium adsorption of a set of pharmaceutical and personal care products (PPCPs: salicylic acid, clofibric acid, carbamazepine and caffeine) from water. Adsorption capacities for single components revealed that the copper(II) IOCs have better affinity toward salicylic and clofibric acid. However, multi-component adsorption tests showed a considerable decrease in adsorption capacity for the acids and an unusual selectivity toward carbamazepine depending on the transition metal. This was attributed to a combination of competition between PPCPs for adsorption sites, adsorbate-adsorbate interactions, and plausible pore blocking caused by carbamazepine. The cobalt(II) IOC bed that was partially calcined to fractionate the surfactant moiety showcased the best selectivity toward caffeine, even during multi-component adsorption. This was due to a combination of a mildly hydrophobic surface and interaction between the PPCP and cobalt(II). In general, the tests suggest that these IOCs may be a potential solution for the removal of PPCPs if employed in a layered-bed configuration, to take care of families of adsorbates in a sequence that would produce sharpened concentration wavefronts. Copyright © 2014 Elsevier B.V. All rights reserved.

Reduction of the hydraulic retention time at constant high organic loading rate to reach the microbial limits of anaerobic digestion in various reactor systems.

Science.gov (United States)

Ziganshin, Ayrat M; Schmidt, Thomas; Lv, Zuopeng; Liebetrau, Jan; Richnow, Hans Hermann; Kleinsteuber, Sabine; Nikolausz, Marcell

2016-10-01

The effects of hydraulic retention time (HRT) reduction at constant high organic loading rate on the activity of hydrogen-producing bacteria and methanogens were investigated in reactors digesting thin stillage. Stable isotope fingerprinting was additionally applied to assess methanogenic pathways. Based on hydA gene transcripts, Clostridiales was the most active hydrogen-producing order in continuous stirred tank reactor (CSTR), fixed-bed reactor (FBR) and anaerobic sequencing batch reactor (ASBR), but shorter HRT stimulated the activity of Spirochaetales. Further decreasing HRT diminished Spirochaetales activity in systems with biomass retention. Based on mcrA gene transcripts, Methanoculleus and Methanosarcina were the predominantly active in CSTR and ASBR, whereas Methanosaeta and Methanospirillum activity was more significant in stably performing FBR. Isotope values indicated the predominance of aceticlastic pathway in FBR. Interestingly, an increased activity of Methanosaeta was observed during shortening HRT in CSTR and ASBR despite high organic acids concentrations, what was supported by stable isotope data. Copyright © 2016 Elsevier Ltd. All rights reserved.

Pyrolysis of oil palm mesocarp fiber and palm frond in a slow-heating fixed-bed reactor: A comparative study.

Science.gov (United States)

Kabir, G; Mohd Din, A T; Hameed, B H

2017-10-01

Oil palm mesocarp fiber (OPMF) and palm frond (PF) were respectively devolatilized by pyrolysis to OPMF-oil and PF-oil bio-oils and biochars, OPMF-char and PF-char in a slow-heating fixed-bed reactor. In particular, the OPMF-oil and PF-oil were produced to a maximum yield of 48wt% and 47wt% bio-oils at 550°C and 600°C, respectively. The high heating values (HHVs) of OPMF-oil and PF-oil were respectively found to be 23MJ/kg and 21MJ/kg, whereas 24.84MJ/kg and 24.15MJ/kg were for the corresponding biochar. The HHVs of the bio-oils and biochars are associated with low O/C ratios to be higher than those of the corresponding biomass. The Fourier transform infrared spectra and peak area ratios highlighted the effect of pyrolysis temperatures on the bio-oil compositions. The bio-oils are pervaded with numerous oxygenated carbonyl and aromatic compounds as suitable feedstocks for renewable fuels and chemicals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of recirculation rate on the performance of a combined ...

African Journals Online (AJOL)

The objective of this study was to evaluate a combined anaerobic-aerobic upflow fixed-bed reactor with liquid phase recirculation for the removal of nitrogen and organic matter from poultry slaughterhouse wastewater. The reactor performance was evaluated with a hydraulic retention time (HRT) of 11 h and three different ...

Evaluation of ADCP apparent bed load velocity in a large sand-bed river: Moving versus stationary boat conditions

Science.gov (United States)

Jamieson, E.C.; Rennie, C.D.; Jacobson, R.B.; Townsend, R.D.

2011-01-01

Detailed mapping of bathymetry and apparent bed load velocity using a boat-mounted acoustic Doppler current profiler (ADCP) was carried out along a 388-m section of the lower Missouri River near Columbia, Missouri. Sampling transects (moving boat) were completed at 5- and 20-m spacing along the study section. Stationary (fixed-boat) measurements were made by maintaining constant boat position over a target point where the position of the boat did not deviate more than 3 m in any direction. For each transect and stationary measurement, apparent bed load velocity (vb) was estimated using ADCP bottom tracking data and high precision real-time kinematic (RTK) global positioning system (GPS). The principal objectives of this research are to (1) determine whether boat motion introduces a bias in apparent bed load velocity measurements; and (2) evaluate the reliability of ADCP bed velocity measurements for a range of sediment transport environments. Results indicate that both high transport (vb>0.6 m/s) and moving-boat conditions (for both high and low transport environments) increase the relative variability in estimates of mean bed velocity. Despite this, the spatially dense single-transect measurements were capable of producing detailed bed velocity maps that correspond closely with the expected pattern of sediment transport over large dunes. ?? 2011 American Society of Civil Engineers.

Cleansing, methanation is democratizing; Depollution, la methanisation se democratise

Energy Technology Data Exchange (ETDEWEB)

Aumond, N.

2005-06-01

The French company Naskeo is developing a biological treatment method for small industrial pollutant sources. With a treatment capacity of 36 kg COD (chemical oxygen demand) per m{sup 3} and per day, this process is two times more efficient than todays commercialized anaerobic stations. The method involves the classical methanation process and uses the Provae technology developed by the national institute of agronomical research (Inra), which combines the fixed bed and fluidized bed technologies. Short paper. (J.S.)

Simultaneous production of laccase and decolouration of the diazo dye Reactive Black 5 in a fixed-bed bioreactor

International Nuclear Information System (INIS)

Enayatzamir, Kheirghadam; Alikhani, Hossein A.; Rodriguez Couto, Susana

2009-01-01

In this paper the production of laccase and the decolouration of the recalcitrant diazo dye Reactive Black 5 (RB5) by the white-rot fungus Trametes pubescens immobilised on stainless steel sponges in a fixed-bed reactor were studied. Laccase production was increased by 10-fold in the presence of RB5 and reached a maximum value of 1025 U/l. Enhanced laccase production in the presence of RB5 in this fungus is an added advantage during biodegradation of RB5-containing effluents. The decolouration of RB5 was due to two processes: dye adsorption onto the fungal mycelium and dye degradation by the laccase enzymes produced by the fungus. RB5 decolouration was performed during four successive batches obtaining high decolouration percentages (74%, 43% and 52% in 24 h for the first, third and four batch, respectively) without addition of redox mediators. Also, the in vitro decolouration of RB5 by the concentrated culture extract, containing mainly laccase, produced in the above bioreactor was studied. The decolouration percentages obtained were considerably lower (around 20% in 24 h) than that attained with the whole culture

On the effect of cross sectional shape on incipient motion and deposition of sediments in fixed bed channels

Directory of Open Access Journals (Sweden)

Safari Mir-Jafar-Sadegh

2014-03-01

Full Text Available The condition of incipient motion and deposition are of the essential issues for the study of sediment transport. This phenomenon is of great importance to hydraulic engineers for designing sewers, drainage, as well as other rigid boundary channels. This is a study carried out with the objectives of describing the effect of cross-sectional shape on incipient motion and deposition of particles in rigid boundary channels. In this research work, the experimental data given by Loveless (1992 and Mohammadi (2005 are used. On the basis of the critical velocity approach, a new incipient motion equation for a V-shaped bottom channel and incipient deposition of sediment particles equations for rigid boundary channels having circular, rectangular, and U-shaped cross sections are obtained. New equations were compared to the other incipient motion equations. The result shows that the cross-sectional shape is an important factor for defining the minimum velocity for no-deposit particles. This study also distinguishes incipient motion of particles from incipient deposition for particles. The results may be useful for designing fixed bed channels with a limited deposition condition.

Simultaneous production of laccase and decolouration of the diazo dye Reactive Black 5 in a fixed-bed bioreactor

Energy Technology Data Exchange (ETDEWEB)

Enayatzamir, Kheirghadam [Department of Chemical Engineering, Rovira i Virgili University, Av. Paisos Catalans 26, 43007 Tarragona (Spain); Department of Soil Science Engineering, University of Tehran, Karaj (Iran, Islamic Republic of); Alikhani, Hossein A. [Department of Soil Science Engineering, University of Tehran, Karaj (Iran, Islamic Republic of); Rodriguez Couto, Susana [Department of Chemical Engineering, Rovira i Virgili University, Av. Paisos Catalans 26, 43007 Tarragona (Spain)], E-mail: susana.rodriguez@urv.cat

2009-05-15

In this paper the production of laccase and the decolouration of the recalcitrant diazo dye Reactive Black 5 (RB5) by the white-rot fungus Trametes pubescens immobilised on stainless steel sponges in a fixed-bed reactor were studied. Laccase production was increased by 10-fold in the presence of RB5 and reached a maximum value of 1025 U/l. Enhanced laccase production in the presence of RB5 in this fungus is an added advantage during biodegradation of RB5-containing effluents. The decolouration of RB5 was due to two processes: dye adsorption onto the fungal mycelium and dye degradation by the laccase enzymes produced by the fungus. RB5 decolouration was performed during four successive batches obtaining high decolouration percentages (74%, 43% and 52% in 24 h for the first, third and four batch, respectively) without addition of redox mediators. Also, the in vitro decolouration of RB5 by the concentrated culture extract, containing mainly laccase, produced in the above bioreactor was studied. The decolouration percentages obtained were considerably lower (around 20% in 24 h) than that attained with the whole culture.

Porous filtering media comparison through wet and dry sampling of fixed bed gasification products

Science.gov (United States)

Allesina, G.; Pedrazzi, S.; Montermini, L.; Giorgini, L.; Bortolani, G.; Tartarini, P.

2014-11-01

The syngas produced by fixed bed gasifiers contains high quantities of particulate and tars. This issue, together with its high temperature, avoids its direct exploitation without a proper cleaning and cooling process. In fact, when the syngas produced by gasification is used in an Internal Combustion engine (IC), the higher the content of tars and particulate, the higher the risk to damage the engine is. If these compounds are not properly removed, the engine may fail to run. A way to avoid engine fails is to intensify the maintenance schedule, but these stops will reduce the system profitability. From a clean syngas does not only follow higher performance of the generator, but also less pollutants in the atmosphere. When is not possible to work on the gasification reactions, the filter plays the most important role in the engine safeguard process. This work is aimed at developing and comparing different porous filters for biomass gasifiers power plants. A drum filter was developed and tested filling it with different filtering media available on the market. As a starting point, the filter was implemented in a Power Pallet 10 kW gasifier produced by the California-based company "ALL Power Labs". The original filter was replaced with different porous biomasses, such as woodchips and corn cobs. Finally, a synthetic zeolites medium was tested and compared with the biological media previously used. The Tar Sampling Protocol (TSP) and a modified "dry" method using the Silica Gel material were applied to evaluate the tars, particulate and water amount in the syngas after the filtration process. Advantages and disadvantages of every filtering media chosen were reported and discussed.

Adsorptive control of water in esterification with immobilized enzymes: II. fixed-bed reactor behavior.

Science.gov (United States)

Mensah, P; Gainer, J L; Carta, G

1998-11-20

Experimental and theoretical studies are conducted to understand the dynamic behavior of a continuous-flow fixed-bed reactor in which an esterification is catalyzed by an immobilized enzyme in an organic solvent medium. The experimental system consists of a commercial immobilized lipase preparation known as Lipozyme as the biocatalyst, with propionic acid and isoamyl alcohol (dissolved in hexane) as the reaction substrates. A complex dynamic behavior is observed experimentally as a result of the simultaneous occurrence of reaction and adsorption phenomena. Both propionic acid and water are adsorbed by the biocatalyst resulting in lower reaction rates. In addition, an excessive accumulation of water in the reactor leads to a rapid irreversible inactivation of the enzyme. A model based on previously-obtained adsorption isotherms and kinetic expressions, as well as on adsorption rate measurements obtained in this work, is used to predict the concentration and thermodynamic activity of water along the reactor length. The model successfully predicts the dynamic behavior of the reactor and shows that a maximum thermodynamic activity of water occurs at a point at some distance from the reactor entrance. A cation exchange resin in sodium form, packed in the reactor as a selective water adsorbent together with the catalyst particles, is shown to be an effective means for preventing an excessive accumulation of water formed in the reaction. Its use results in longer cycle times and greater productivity. As predicted by the model, the experimental results show that the water adsorbed on the catalyst and on the ion exchange resin can be removed with isoamyl alcohol with no apparent loss in enzyme activity. Copyright 1998 John Wiley & Sons, Inc.

[Prediction model of health workforce and beds in county hospitals of Hunan by multiple linear regression].

Science.gov (United States)

Ling, Ru; Liu, Jiawang

2011-12-01

To construct prediction model for health workforce and hospital beds in county hospitals of Hunan by multiple linear regression. We surveyed 16 counties in Hunan with stratified random sampling according to uniform questionnaires,and multiple linear regression analysis with 20 quotas selected by literature view was done. Independent variables in the multiple linear regression model on medical personnels in county hospitals included the counties' urban residents' income, crude death rate, medical beds, business occupancy, professional equipment value, the number of devices valued above 10 000 yuan, fixed assets, long-term debt, medical income, medical expenses, outpatient and emergency visits, hospital visits, actual available bed days, and utilization rate of hospital beds. Independent variables in the multiple linear regression model on county hospital beds included the the population of aged 65 and above in the counties, disposable income of urban residents, medical personnel of medical institutions in county area, business occupancy, the total value of professional equipment, fixed assets, long-term debt, medical income, medical expenses, outpatient and emergency visits, hospital visits, actual available bed days, utilization rate of hospital beds, and length of hospitalization. The prediction model shows good explanatory and fitting, and may be used for short- and mid-term forecasting.

Relevance of various nitrogen fixing microorganisms in ecology and plant productivity as a basis for evaluating their damage by environmental chemicals

Energy Technology Data Exchange (ETDEWEB)

Jagnow, G

1981-01-01

To evaluate detrimental side-effects of environmental chemicals on the biological N/sub 2/-fixation the relative importance of the N/sub 2/-fixation of legume and non-legume root nodules, of symbiotic and free living blue-green algae, of aerobic and facultatively anaerobic rhizosphere bacteria and of anaerobic bacteria is discussed on the basis of their fixation rate and their contribution to the conservation of ecosystems. From an agricultural and ecological point of view the symbiotic N/sub 2/-fixation of legumes and non-legumes takes the first place, being followed by that of blue-green algae and rhizosphere bacteria. Compared with these, the strictly anaerobic N/sub 2/-fixation has only a minor importance. Variable side-effects of herbicides on N/sub 2/-fixing bacteria are cited to stress the necessity of testing representatives of various ecological groups. Suitable test systems are proposed with soybeans, white clover, Rhizobium cultures, N/sub 2/-fixing blue-green algae and with Azospirillum species.

Comparison of the anaerobic microbiota of deep-water Geodia spp. and sandy sediments in the Straits of Florida.

Science.gov (United States)

Brück, Wolfram M; Brück, Thomas B; Self, William T; Reed, John K; Nitecki, Sonja S; McCarthy, Peter J

2010-05-01

Marine sediments and sponges may show steep variations in redox potential, providing niches for both aerobic and anaerobic microorganisms. Geodia spp. and sediment specimens from the Straits of Florida were fixed using paraformaldehyde and 95% ethanol (v/v) for fluorescence in situ hybridization (FISH). In addition, homogenates of sponge and sediment samples were incubated anaerobically on various cysteine supplemented agars. FISH analysis showed a prominent similarity of microbiota in sediments and Geodia spp. samples. Furthermore, the presence of sulfate-reducing and annamox bacteria as well as other obligate anaerobic microorganisms in both Geodia spp. and sediment samples were also confirmed. Anaerobic cultures obtained from the homogenates allowed the isolation of a variety of facultative anaerobes, primarily Bacillus spp. and Vibrio spp. Obligate anaerobes such as Desulfovibrio spp. and Clostridium spp. were also found. We also provide the first evidence for a culturable marine member of the Chloroflexi, which may enter into symbiotic relationships with deep-water sponges such as Geodia spp. Resuspended sediment particles, may provide a source of microorganisms able to associate or form a symbiotic relationship with sponges.

BED estimates of HIV incidence: resolving the differences, making things simpler.

Directory of Open Access Journals (Sweden)

John Hargrove

Full Text Available Develop a simple method for optimal estimation of HIV incidence using the BED capture enzyme immunoassay.Use existing BED data to estimate mean recency duration, false recency rates and HIV incidence with reference to a fixed time period, T.Compare BED and cohort estimates of incidence referring to identical time frames. Generalize this approach to suggest a method for estimating HIV incidence from any cross-sectional survey.Follow-up and BED analyses of the same, initially HIV negative, cases followed over the same set time period T, produce estimates of the same HIV incidence, permitting the estimation of the BED mean recency period for cases who have been HIV positive for less than T. Follow-up of HIV positive cases over T, similarly, provides estimates of the false-recent rate appropriate for T. Knowledge of these two parameters for a given population allows the estimation of HIV incidence during T by applying the BED method to samples from cross-sectional surveys. An algorithm is derived for providing these estimates, adjusted for the false-recent rate. The resulting estimator is identical to one derived independently using a more formal mathematical analysis. Adjustments improve the accuracy of HIV incidence estimates. Negative incidence estimates result from the use of inappropriate estimates of the false-recent rate and/or from sampling error, not from any error in the adjustment procedure.Referring all estimates of mean recency periods, false-recent rates and incidence estimates to a fixed period T simplifies estimation procedures and allows the development of a consistent method for producing adjusted estimates of HIV incidence of improved accuracy. Unadjusted BED estimates of incidence, based on life-time recency periods, would be both extremely difficult to produce and of doubtful value.

Modeling microbial diversity in anaerobic digestion through an extended ADM1 model.

Science.gov (United States)

Ramirez, Ivan; Volcke, Eveline I P; Rajinikanth, Rajagopal; Steyer, Jean-Philippe

2009-06-01

The anaerobic digestion process comprises a whole network of sequential and parallel reactions, of both biochemical and physicochemical nature. Mathematical models, aiming at understanding and optimization of the anaerobic digestion process, describe these reactions in a structured way, the IWA Anaerobic Digestion Model No. 1 (ADM1) being the most well established example. While these models distinguish between different microorganisms involved in different reactions, to our knowledge they all neglect species diversity between organisms with the same function, i.e. performing the same reaction. Nevertheless, available experimental evidence suggests that the structure and properties of a microbial community may be influenced by process operation and on their turn also determine the reactor functioning. In order to adequately describe these phenomena, mathematical models need to consider the underlying microbial diversity. This is demonstrated in this contribution by extending the ADM1 to describe microbial diversity between organisms of the same functional group. The resulting model has been compared with the traditional ADM1 in describing experimental data of a pilot-scale hybrid Upflow Anaerobic Sludge Filter Bed (UASFB) reactor, as well as in a more detailed simulation study. The presented model is further shown useful in assessing the relationship between reactor performance and microbial community structure in mesophilic CSTRs seeded with slaughterhouse wastewater when facing increasing levels of ammonia.

ADSORPTION OF MANGANESE FROM ACID MINE DRAINAGE EFFLUENTS USING BONE CHAR: CONTINUOUS FIXED BED COLUMN AND BATCH DESORPTION STUDIES

Directory of Open Access Journals (Sweden)

D. C. Sicupira

2015-06-01

Full Text Available AbstractIn the present study, continuous fixed bed column runs were carried out in an attempt to evaluate the feasibility of using bone char for the removal of manganese from acid mine drainage (AMD. Tests using a laboratory solution of pure manganese at typical concentration levels were also performed for comparison purposes. The following operating variables were evaluated: column height, flow rate, and initial pH. Significant variations in resistance to the mass transfer of manganese into the bone char were identified using the Thomas model. A significant effect of the bed height could only be observed in tests using the laboratory solution. No significant change in the breakthrough volume could be observed with different flow rates. By increasing the initial pH from 2.96 to 5.50, the breakthrough volume was also increased. The maximum manganese loading capacity in continuous tests using bone char for AMD effluents was 6.03 mg g-1, as compared to 26.74 mg g-1 when using the laboratory solution. The present study also performed desorption tests, using solutions of HCl, H2SO4, and water, aimed at the reuse of the adsorbent; however, no promising results were obtained due to low desorption levels associated with a relatively high mass loss. Despite the desorption results, the removal of manganese from AMD effluents using bone char as an adsorbent is technically feasible and attends to environmental legislation. It is interesting to note that the use of bone char for manganese removal may avoid the need for pH corrections of effluents after treatment. Moreover, bone char can also serve to remove fluoride ions and other metals, thus representing an interesting alternative material for the treatment of AMD effluents.

Breakthrough analysis for water disinfection using silver nanoparticles coated resin beads in fixed-bed column

International Nuclear Information System (INIS)

Mthombeni, Nomcebo H.; Mpenyana-Monyatsi, Lizzy; Onyango, Maurice S.; Momba, Maggie N.B.

2012-01-01

Highlights: ► Performance of silver nanoparticles coated resin in water disinfection is presented. ► Sigmoidal models are used to describe breakthrough curves. ► The performance of the media in water disinfection is affected by process variables. ► Test with environmental water shows the media is effective in water disinfection. - Abstract: This study demonstrates the use of silver nanoparticles coated resin beads in deactivating microbes in drinking water in a column filtration system. The coated resin beads are characterized using X-ray diffraction (XRD), Fourier transform infra-red (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM) and energy dispersive spectroscopy (EDS) to confirm the functional groups, morphology and the presence of silver nanoparticles on the surface of the resin. The performance of the coated resin is evaluated as a function of bed mass, initial bacterial concentration and flow rate using Escherichia coli as model microbial contaminant in water. The survival curves of E. coli are expressed as breakthrough curves (BTCs), which are modeled using sigmoidal regression equations to obtain relevant rate parameters. The number of bed volumes processed at breakthrough point and capacity of the bed are used as performance indicators. Results show that performance increases with a decrease in initial bacterial concentration, an increase in flow rate and an increase in bed mass.

Mathematical modeling of the adsorption/desorption characteristics of anthocyanins from muscadine (Vitis rotundifolia cv. Noble) juice pomace on Amberlite FPX66 resin in a fixed bed column.

Science.gov (United States)

Uzdevenes, Chad G; Gao, Chi; Sandhu, Amandeep K; Yagiz, Yavuz; Gu, Liwei

2018-03-24

Muscadine grape pomace, a by-product of juicing and wine-making, contains significant amounts of anthocyanin 3,5-diglucosides, known to be beneficial to human health. The objective of this research was to use mathematical modeling to investigate the adsorption/desorption characteristics of these anthocyanins from muscadine grape pomace on Amberlite FPX66 resin in a fixed bed column. Anthocyanins were extracted using hot water and ultrasound, and the extracts were loaded onto a resin column at five bed depths (5, 6, 8, 10 and 12 cm) using three flow rates (4, 6 and 8 mL min -1 ). It was found that adsorption on the column fitted the bed depth service time (BDST) model and the empty bed residence time (EBRT) model. Desorption was achieved by eluting the column using ethanol at four concentrations (25, 40, 55 and 70% v/v) and could be described with an empirical sigmoid model. The breakthrough curves of anthocyanins fitted the BDST model for all three flow rates with R 2 values of 0.983, 0.992 and 0.984 respectively. The EBRT model was successfully employed to find the operating lines, which allow for column scale-up while still achieving similar results to those found in a laboratory operation. Desorption with 40% (v/v) ethanol achieved the highest recovery rate of anthocyanins at 79.6%. The mathematical models established in this study can be used in designing a pilot/industrial- scale column for the separation and concentration of anthocyanins from muscadine juice pomace. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

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. Copyright © 2011 Elsevier Ltd. All rights reserved.

Biodegradation of bilge water: Batch test under anaerobic and aerobic conditions and performance of three pilot aerobic Moving Bed Biofilm Reactors (MBBRs) at different filling fractions.

Science.gov (United States)

Vyrides, Ioannis; Drakou, Efi-Maria; Ioannou, Stavros; Michael, Fotoula; Gatidou, Georgia; Stasinakis, Athanasios S

2018-07-01

The bilge water that is stored at the bottom of the ships is saline and greasy wastewater with a high Chemical Oxygen Demand (COD) fluctuations (2-12 g COD L -1 ). The aim of this study was to examine at a laboratory scale the biodegradation of bilge water using first anaerobic granular sludge followed by aerobic microbial consortium (consisted of 5 strains) and vice versa and then based on this to implement a pilot scale study. Batch results showed that granular sludge and aerobic consortium can remove up to 28% of COD in 13 days and 65% of COD removal in 4 days, respectively. The post treatment of anaerobic and aerobic effluent with aerobic consortium and granular sludge resulted in further 35% and 5% COD removal, respectively. The addition of glycine betaine or nitrates to the aerobic consortium did not enhance significantly its ability to remove COD from bilge water. The aerobic microbial consortium was inoculated in 3 pilot (200 L) Moving Bed Biofilm Reactors (MBBRs) under filling fractions of 10%, 20% and 40% and treated real bilge water for 165 days under 36 h HRT. The MBBR with a filling fraction of 40% resulted in the highest COD decrease (60%) compared to the operation of the MBBRs with a filling fraction of 10% and 20%. GC-MS analysis on 165 day pointed out the main organic compounds presence in the influent and in the MBBR (10% filling fraction) effluent. Copyright © 2018 Elsevier Ltd. All rights reserved.

Adiabatic Fixed-Bed Gasification of Colombian Coffee Husk Using Air-Steam Blends for Partial Oxidation

Directory of Open Access Journals (Sweden)

Javier Bonilla

2017-01-01

Full Text Available The increasing energy consumption, mostly supplied by fossil fuels, has motivated the research and development of alternative fuel technologies to decrease the humanity’s dependence on fossil fuels, which leads to pollution of natural sources. Small-scale biomass gasification, using air-steam blends for partial oxidation, is a good alternative since biomass is a neutral carbon feedstock for sustainable energy generation. This research presents results obtained from an experimental study on coffee husk (CH gasification, using air-steam blends for partial oxidation in a 10 kW fixed-bed gasifier. Parametric studies on equivalence ratio (ER (1.53 < ER < 6.11 and steam-fuel (SF ratio (0.23 < SF < 0.89 were carried out. The results show that increasing both SF and ER results in a syngas rich in CH4 and H2 but poor in CO. Also, decreased SF and ER decrease the peak temperature (Tpeak at the gasifier combustion zone. The syngas high heating value (HHV ranged from 3112 kJ/SATPm3 to 5085 kJ/SATPm3 and its maximum value was obtained at SF = 0.87 and ER = 4.09. The dry basis molar concentrations of the species, produced under those operating conditions (1.53 < ER < 6.11 and 0.23 < SF < 0.89, were between 1.12 and 4.1% for CH4, between 7.77 and 13.49% for CO, and between 7.54 and 19.07% for H2. Other species were in trace amount.

Optimization and control of a novel upflow anaerobic solid-state (UASS) reactor

Energy Technology Data Exchange (ETDEWEB)

Mumme, J.; Linke, B. [Leibniz Inst. for Agricultural Engineering, Potsdam (Germany); Tolle, R. [Humboldt Univ., Berlin (Germany). Dept. of Biosystems Technology

2010-07-01

Optimization and control strategies for a newly developed upflow anaerobic solid-state (UASS) reactor equipped with liquor recirculation were investigated. The UASS reactor converts solid biomass into biogas while the particulate organic matter (POM) ascends in the form of a solid-state bed (SSB) driven by the adherence of self-produced micro gas bubbles. Performance data and technical characteristics were obtained from a technical scale semi-automatic 400 L UASS reactor that operated for 117 days with maize silage under thermophilic conditions at 55 degrees C. The process liquor was continuously recirculated through separate methanogenic reactors in order to prevent an accumulation of volatile fatty acids. Emphasis was placed on determining the gas and metabolite production. The volatile solids (VS) loading rate was fixed at 5 g per litre per day. The methane production rate of the UASS reactor stabilized between 1.5 and 2.0 L per litre per day. The average volatile solids (VS) methane yield of the maize silage was 380 L per kg. The liquor exchange was found to play an important role in the performance and stability of the digestion process. Although low exchange rates can cause process failure by acidification, high exchange rates have the risk of clogging inside the SSB. It was concluded that the UASS reactor is a viable solution for the digestion of various organic matter.

Intrinsic kinetic parameters of substrate utilization by immobilized anaerobic sludge.

Science.gov (United States)

Zaiat, M; Vieira, L G; Foresti, E

1997-01-20

This article presents a method for evaluating the intrinsic kinetic parameters of the specific substrate utilization rate (r) equation and discusses the results obtained for anaerobic sludge-bed samples taken from a horizontal-flow anaerobic immobilized sludge (HAIS) reactor. This method utilizes a differential reactor filled with polyurethane foam matrices containing immobilized anaerobic sludge which is subjected to a range of feeding substrate flow rates. The range of liquid superficial velocities thus obtained are used for generating data of observed specific substrate utilization rates (r(obs)) under a diversity of external mass transfer resistance conditions. The r(obs) curves are then adjusted to permit their extrapolation for the condition of no external mass transfer resistance, and the values determined are used as a test for the condition of absence of limitation of internal mass transfer. The intrinsic parameters r(max), the maximum specific substrate utilization rate, and K(s), the half-velocity coefficient, are evaluated from the r values under no external mass transfer resistance and no internal mass transfer limitation. The application of such a method for anaerobic sludge immobilized in polyurethane foam particles treating a glucose substrate at 30 degrees C resulted in intrinsic r(max) and K(s), respectively, of 0.330 mg chemical oxygen demand (COD) . mg(-1) volatile suspended solids (VSS) . h(-1) and 72 mg COD . L(-1). In comparison with the values found in the literature, intrinsic r(max) is significantly high and intrinsic K(s) is relatively low. (c) 1997 John Wiley & Sons, Inc.

Combustion of peanut shells in a cone-shaped bubbling fluidized-bed combustor using alumina as the bed material

International Nuclear Information System (INIS)

Arromdee, Porametr; Kuprianov, Vladimir I.

2012-01-01

Highlights: ► We propose burning of peanut shells in a conical fluidized bed using alumina sand. ► We examine hydrodynamic, combustion and emission characteristics of the reactor. ► High, over 99%, combustion efficiency is achievable. ► Emissions of CO and NO from the combustor meet the national emission limits. ► Composition of the bed material undergoes significant changes during the combustion. -- Abstract: This paper reports experimental studies on burning peanut shells in the conical fluidized-bed combustor using alumina sand as the fluidizing agent. Prior to combustion tests, hydrodynamic regimes and characteristics of a conical alumina–biomass bed were investigated under cold-state conditions for variable percentage of peanut shells in the mixture and static bed height. With selected particle sizes (300–500 μm) and static bed height (30 cm), alumina ensured bubbling fluidization regime of the bed at operating conditions specified for firing biomass. Combustion tests were performed at 60 kg/h and 45 kg/h fuel feed rates, while ranging excess air from 20% to 80% at a fixed combustor load. Temperature and gas concentrations (O 2 , CO, C x H y as CH 4 , and NO) were measured along radial and axial directions inside the reactor as well as at stack in order to characterize combustion and emission performance of the combustor for the ranges of operating conditions. For firing 60 kg/h peanut shells, excess air of 40% can be selected as an appropriate value ensuring high, about 99%, combustion efficiency and rather low emissions of CO and NO: 520 ppm and 125 ppm, respectively (both on a dry basis and at 6% O 2 ). With reducing combustor load, the combustion efficiency and emission characteristics were improved to a little extent. No evidence of bed agglomeration was found during 30-h combustion tests on this conical fluidized-bed combustor using alumina sand as the bed material. However, the timescale effect on the composition of the bed material was

Anaerobic Digestion: Process

DEFF Research Database (Denmark)

Angelidaki, Irini; Batstone, Damien J.

2011-01-01

Organic waste may degrade anaerobically in nature as well as in engineered systems. The latter is called anaerobic digestion or biogasification. Anaerobic digestion produces two main outputs: An energy-rich gas called biogas and an effluent. The effluent, which may be a solid as well as liquid...... with very little dry matter may also be called a digest. The digest should not be termed compost unless it specifically has been composted in an aerated step. This chapter describes the basic processes of anaerobic digestion. Chapter 9.5 describes the anaerobic treatment technologies, and Chapter 9...

Observations of the vertical structure of turbulent oscillatory boundary layers above fixed roughness beds using a prototype wideband coherent Doppler profiler: 1. The oscillatory component of the flow

Science.gov (United States)

Hay, Alex E.; Zedel, Len; Cheel, Richard; Dillon, Jeremy

2012-03-01

Results are presented from an experimental investigation of rough turbulent oscillatory boundary layers using a prototype wideband bistatic coherent Doppler profiler. The profiler operates in the 1.2 MHz to 2.3 MHz frequency band and uses software-defined radio technologies for digital control of the frequency content and shape of the transmit pulse and for digital complex demodulation of the received signals. Velocity profiles are obtained at sub-millimeter range resolution and 100 Hz profiling rates (each profile being an ensemble average of 10 pulse pairs). The measurements were carried out above beds of fixed sand or gravel particles, with median grain diameters of 0.37 mm and 3.9 mm, respectively, oscillating sinusoidally at a 10 s period through excursions of 0.75 m to 1.5 m. The resulting vertical profiles of horizontal velocity magnitude and phase, with the vertical axis scaled by ℓ = κu∗m/ω, are comparable to similarly scaled profiles obtained using laser Doppler anemometry by Sleath (1987) and Jensen (1988). A key objective of the comparisons between the previous experiments and those reported here was to establish how close to the bed reliable velocity measurements can be made with the sonar. This minimum distance above the bed is estimated to be 5 ± 1 mm, a value approaching the 3 to 4 mm limit set by the path of least time.

Demand-driven biogas production from sugar beet silage in a novel fixed bed disc reactor under mesophilic and thermophilic conditions.

Science.gov (United States)

Terboven, Christiane; Ramm, Patrice; Herrmann, Christiane

2017-10-01

A newly developed fixed bed disc reactor (FBDR) which combines biofilm formation on biofilm carriers and reactor agitation in one single system was assessed for its applicability to demand-driven biogas production by variable feeding of sugar beet silage. Five different feeding patterns were studied at an organic loading of 4g VS L -1 d -1 under mesophilic and thermophilic conditions. High methane yields of 449-462L N kg VS were reached. Feeding variable punctual loadings caused immediate response with 1.2- to 3.5-fold increase in biogas production rates within 15min. Although variable feeding did not induce process instability, a temporary decrease in pH-value and methane concentration below 40% occurred. Thermophilic temperature was advantageous as it resulted in a more rapid, higher methane production and less pronounced decrease in methane content after feeding. The FBDR was demonstrated to be well-suited for flexible biogas production, but further research and comparison with traditional reactor systems are required. Copyright © 2017 Elsevier Ltd. All rights reserved.

Denitrification of groundwater using a sulfur-oxidizing autotrophic denitrifying anaerobic fluidized-bed MBR: performance and bacterial community structure.

Science.gov (United States)

Zhang, Lili; Zhang, Chao; Hu, Chengzhi; Liu, Huijuan; Qu, Jiuhui

2015-03-01

This paper investigates a novel sulfur-oxidizing autotrophic denitrifying anaerobic fluidized bed membrane bioreactor (AnFB-MBR) that has the potential to overcome the limitations of conventional sulfur-oxidizing autotrophic denitrification systems. The AnFB-MBR produced consistent high-quality product water when fed by a synthetic groundwater with NO3 (-)-N ranging 25-80 mg/L and operated at hydraulic retention times of 0.5-5.0 h. A nitrate removal rate of up to 4.0 g NO3 (-)-N/Lreactord was attained by the bioreactor, which exceeded any reported removal capacity. The flux of AnFB-MBR was maintained in the range of 1.5-15 L m(-2) h(-1). Successful membrane cleaning was practiced with cleaning cycles of 35-81 days, which had no obvious effect on the AnFB-MBR performance. The (15) N-tracer analyses elucidated that nitrogen was converted into (15) N2-N and (15) N-biomass accounting for 88.1-93.1 % and 6.4-11.6 % of the total nitrogen produced, respectively. Only 0.3-0.5 % of removed nitrogen was in form of (15)N2O-N in sulfur-oxidizing autotrophic denitrification process, reducing potential risks of a significant amount of N2O emissions. The sulfur-oxidizing autotrophic denitrifying bacterial consortium was composed mainly of bacteria from Proteobacteria, Chlorobi, and Chloroflexi phyla, with genera Thiobacillus, Sulfurimonas, and Ignavibacteriales dominating the consortium. The pyrosequencing assays also suggested that the stable microbial communities corresponded to the elevated performance of the AnFB-MBR. Overall, this research described relatively high nitrate removal, acceptable flux, indicating future potential for the technology in practice.

FBR and RBR particle bed space reactors

International Nuclear Information System (INIS)

Powell, J.R.; Botts, T.E.

1983-01-01

Compact, high-performance nuclear reactor designs based on High-Temperature Gas Reactors (HTGRs) particulate fuel are investigated. The large surface area available with the small-diameter (approx. 500 microns) particulate fuel allows very high power densities (MW's/liter), small temperature differences between fuel and coolant (approx. 10 0 K), high coolant-outlet temperatures (1500 to 3000 0 K, depending on design), and fast reactor startup (approx. 2 to 3 seconds). Two reactor concepts are developed - the Fixed Bed Reactor (FBR), where the fuel particles are packed into a thin annular bed between two porous cylindrical drums, and the Rotating Bed Reactor (RBR), where the fuel particles are held inside a cold rotating (typically approx. 500 rpm) porous cylindrical drum. The FBR can operate steady-state in the closed-cycle He-cooled mode or in the open-cycle H 2 -cooled mode. The RBR will operate only in the open-cycle H 2 -cooled mode

Protection of biofilms against toxic shocks by the adsorption and desorption capacity of carriers in anaerobic fluidized bed reactors

Energy Technology Data Exchange (ETDEWEB)

Petrozzi, S. (Biological Reaction Engineering Group, Chemical Engineering Dept., ETH, Zurich (Switzerland)); Kut, O.M. (Biological Reaction Engineering Group, Chemical Engineering Dept., ETH, Zurich (Switzerland)); Dunn, I.J. (Biological Reaction Engineering Group, Chemical Engineering Dept., ETH, Zurich (Switzerland))

1993-05-01

The aim of this study was to select a support medium for an anaerobic biofilm fluidized bed reactor (AFBR) for waste water treatment. Six materials, shale, pumice, porous glass, quartz sand, activated carbon and anthracite were used as carriers for the biofilm. The reactors were operated in parallel for several months with vapour condensate from a sulfite cellulose process as feed. The criteria used for the evaluation were: (a) Reproducibility of the reactor performance, (b) performance of the different carriers under various loading rates, (c) stability against toxic shock loadings using 2,4,6-trichlorophenol (TCP) as toxicant, (d) recovery capacity after intoxication and starvation, (e) adsorption/desorption behavior of the carriers. A comparison between four runs showed good reproducibility of the steady state removal rates. The performance of the reactors and the stability of the degradation rates were tested for a range of loading conditions. Unbuffered, buffered and pH controlled conditions were compared. The pumice carrier was best with respect to the degradation rate achieved per carrier mass. The response of the reactors to massive TCP step loadings was tested. Loadings less than 1.5 kg TCP/m[sup 3]d resulted in initially normal gas production rates for all the systems, except the activated carbon, whose gas production was partially inhibited from the start. After increasing the load to 1.5 kg TCP/m[sup 3]d the gas production rates of all the other reactors fell abruptly to zero. Restarting after 2 months, all reactors showed methanogenic activity without requiring new inoculum. (orig.)

Anaerobes in pleuropulmonary infections

Directory of Open Access Journals (Sweden)

De A

2002-01-01

Full Text Available A total of 76 anaerobes and 122 aerobes were isolated from 100 patients with pleuropulmonary infections, e.g. empyema (64, pleural effusion (19 and lung abscess (13. In 14% of the patients, only anaerobes were recovered, while a mixture of aerobes and anaerobes was encountered in 58%. From all cases of lung abscess, anaerobic bacteria were isolated, alone (04 or along with aerobic bacteria (13. From empyema and pleural effusion cases, 65.6% and 68.4% anaerobes were recovered respectively. Amongst anaerobes, gram negative anaerobic bacilli predominated (Prevotella melaninogenicus 16, Fusobacterium spp. 10, Bacteroides spp. 9, followed by gram positive anaerobic cocci (Peptostreptococcus spp. 31. Coliform bacteria (45 and Pseudomonas aeruginosa (42 were the predominant aerobic isolates.

Anaerobic digestion of cassava wastewater in fixed bed reactor using bamboo medium support; Digestao anaerobica de agua residuaria de fecularia em reator de leito fixo utilizando meio suporte de aneis de bambu

Energy Technology Data Exchange (ETDEWEB)

Watthier, Elisangela; Andreani, Cristiane L.; Silva, Jefferson L.G. [Universidade Estadual do Oeste do Parana (UNIOESTE), Cascavel, PR (Brazil)], E-mail: eliswa@hotmail.com; Gomes, Simone D. [Universidade Estadual do Oeste do Parana (UNIOESTE), Cascavel, PR (Brazil). Dept. de Recursos Hidricos e Saneamento Ambiental

2012-11-01

Cassava wastewater causes damage to the environment due to high organic loads and presence of cyanide and hydrocyanic acid. An alternative treatment anaerobic which add value for biogas production. To allow use of higher load sand reducing the TDH support means are used. This study aimed to evaluate the performance of the anaerobic treatment of liquid effluent of cassava industry, using bamboo as support media. The wastewater used was derived from starch factory located in Toledo. Was used PVC reactor with a diameter of 15 cm and length 90 cm. Were used as support means 52 bamboo rings and useful reactor volume 61. A total of 13 load increasing, from 1,675 to 15.158 g.L{sup -1}.d{sup -1}, until reaching the maximum load bearable. For each load data was collected for 15 days by daily samples at entrance and exit of the reactors. The samples were analyzed: DQO, alkalinity, volatile acidity and biogas production. There was a system instability in 12,394 g.L{sup -1}.d{sup -1}, with values of AV/AT above 0.5, but the system began to show signs of stability in the next load. The reactor showed biogas production up 1.57 L.L{sup -1}.d{sup -1}. (author)

FY 1996 report on the results of the development of an entrained bed coal gasification power plant. Part 2. Investigational study of verification plant; 1995 nendo seika hokokusho. Funryusho sekitan gaska hatsuden plant kaihatsu - Sono 2. Jissho plant ni kansuru chosa kenkyu hen

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-01-01

For the purpose of developing the technology of the integrated coal gasification combined cycle power generation, an investigational study of verification plant was made, and the FY 1996 results were summarized. In this fiscal year, the conceptual design was made of the Nakoso method based on the method of Nakoso pilot plant, the fixed bed method in which fixed bed gas refining facilities tested in Nakoso pilot plant were adopted, and the packed bed method. In the Nakoso method, 5 cases were studied using the air blown two-stage entrained bed for gasifier, dry two-stage fluidized bed for desulfurization and dry granular bed packed bed for dust removal. In the fixed bed method, 2 cases were studied using the air blown two-stage entrained bed for gasifier and dry fixed bed for gas refining. In the packed bed method, 2 cases were studied using the air blown two-stage entrained bed for gasifier and dry packed bed for gas refining. As to gas turbine facilities, 5 cases were studied in which GT output is 115MW - 215MW (output of combined cycle power generation: 220MW - 420MW). (NEDO)

Possibilités de prise en compte des phénomènes de transferts internes aux grains lors de la modélisation du séchage en lit fixe du maïs : revue

Directory of Open Access Journals (Sweden)

Janas, S.

2012-01-01

Full Text Available Opportunity to take the grain internal transfers into account in the context of the modelization of the fixed bed drying of corn: a review. The fixed-bed drying is a preservation technique widely used in food industries. Its control and optimization require to know the distributions of temperature and water content in the bed depending on the operating conditions used. This information is obtained through modeling of the heat and mass transfers involved. Models of fixed bed drying have two components. The first one is the model at the product level. This model can predict how temperature and water content of the product change at each point of the bed according to local conditions of temperature and humidity. The second component is the model for the entire bed, which describes how heat and water are conveyed by the drying air through the bed. In this literature review, the main models of fixed bed drying are presented, with particular emphasis on the models used for corn drying. In this review, these two components are presented separately. The goal is to idendify the advantages and disadvantages of each approach, and opportunities for future research in this field.

Anaerobic stabilization and conversion of transformed intermediates of antibiotic pharmaceutical effluent in a fluidized bed reactor.

Science.gov (United States)

Tamijevendane, S; Saravanane, R; Rajesh, R; Sivacoumar, R

2011-07-01

The formulation and implementation of regulatory standards for the ultimate disposal and reuse of transformed products of antibiotic drugs and solvents have been a pending issue in the waste management of pharmaceutical industries especially in the developing countries like India. A case study has been identified and the current issues in one of the major pharmaceutical industry (manufacturing cephalosporin drugs) located in Chennai, India, has been discussed for the possible implementation of anaerobically transformed intermediates of antibiotic pharmaceutical waste sludge. The objective of the study was to determine the effect of bioaugmentation on the convertibility of anaerobically transformed intermediates of antibiotic pharmaceutical waste sludge into residuals and biocompost. Cephalosporin is a common name refers to cephradine (C16H19N3O4S) and cephalexin (C16H17N3O4S.H2O). Based on the critical examination of results, the industry is looking for the alternatives of either direct disposal of 7-amino-3-deacetoxycephalosporanic acid (7-ADCA) and phenyl acetic acid or for further degradation and disposal, which will essentially require additional cost and maintenance. The present regulatory standard implemented in India does not envisage such disposal alternatives and hence this would invite suggestions and recommendations of the expertise for the possible implementation on the pending issue in the antibiotic based pharmaceutical industries. The presence of cephalosporin increases total strength (Chemical Oxygen Demand) of the effluent and indirectly increases the cost of the treatment. Hence the biotransformation of cephalosporin either alone or in combination with other energetic compounds, offers the potential for an economical and environment friendly disposal alternative for the anaerobically transformed intermediates of antibiotic pharmaceutical waste sludge.

Dry anaerobic digestion of rejects from pre-treated food waste; Torroetning av rejekt fraan foerbehandling av matavfall

Energy Technology Data Exchange (ETDEWEB)

Bohn, Irene [NSR, Helsingborg (Sweden); Murto, Marika; Bjoernsson, Lovisa [Bioteknik, LTH, Lund (Sweden); Rosqvist, Haakan [Rosqvist Resurs, Klaagerup (Sweden)

2011-11-15

When the organic fraction of source separated municipal solid waste is digested anaerobically in a continuously stirred tank reactor there is a need for a pretreatment to make the waste pumpable and remove contaminants. In one type of pretreatment the material passes through a screw press which separates waste in a liquid fraction and a dry fraction (the reject). At NSR this technique is used and at present the reject is incinerated. A previous study has shown that about 30 % of the methane potential of the incoming organic waste can be found in the reject. The aim of the present project was to investigate the possibilities of realizing the methane potential through batch wise dry anaerobic digestion followed by composting as an alternative to incineration. In the technique used in the present project the material was digested in an anaerobic leach-bed with recirculation of leachate over the bed. It is important that the material is sufficiently porous to let the leachate spread evenly through the leach-bed. Treatment of reject and a mixture of reject and structural material were tested to investigate if the addition of structural material had an effect on the porosity. The flow of liquid through a leach-bed of reject and one of reject mixed with structural material was studied using LiBr as tracer. The digestate from the dry digestion process was composted, and the resulting compost was evaluated. The odor from the digestate, the active compost and the compost product was measured by analyzing the odor in the air of the porous space in heaps of the different materials. This was used to evaluate the risk of odor problems. The dry digestion and the tracer experiment both showed that mixing the reject with structural material had a positive effect on the flow of liquid through the material and the digestion process. Addition of structural material to the reject was needed in order to achieve an efficient digestion process. Using tracers proved to be a useful way of

The utility of anaerobic blood culture in detecting facultative anaerobic bacteremia in children.

Science.gov (United States)

Shoji, Kensuke; Komuro, Hisako; Watanabe, Yasushi; Miyairi, Isao

2013-08-01

Routine anaerobic blood culture is not recommended in children because obligate anaerobic bacteremia is rare in the pediatric population. However, a number of facultative anaerobic bacteria can cause community and hospital acquired infections in children and the utility of anaerobic blood culture for detection of these organisms is still unclear. We conducted a retrospective analysis of all blood culture samples (n = 24,356) at a children's hospital in Japan from October 2009 to June 2012. Among the samples that had paired aerobic and anaerobic blood cultures, 717 samples were considered clinically significant with 418 (58%) organisms detected from both aerobic and anaerobic cultures, 167 (23%) detected only from aerobic culture and 132 (18%) detected only from anaerobic culture. While most facultative anaerobes were detectable by aerobic culture, over 25% of Enterobacteriaceae and 15% of Staphylococcus sp. were detected from anaerobic cultures bottles only, suggesting its potential role in selected settings. Copyright © 2013 Elsevier Inc. All rights reserved.

3D numerical model of the spherical particle saltation in a channel with a rough fixed bed

Czech Academy of Sciences Publication Activity Database

Lukerchenko, Nikolay; Piatsevich, Siarhei; Chára, Zdeněk; Vlasák, Pavel

2009-01-01

Roč. 57, č. 2 (2009), s. 100-112 ISSN 0042-790X R&D Projects: GA ČR GA103/06/1487 Institutional research plan: CEZ:AV0Z20600510 Keywords : 3D Saltation Model * Bed-Load Transport * Particle-Bed Collision * Particle Rotation * Particle Lateral Dispersion Subject RIV: BK - Fluid Dynamics Impact factor: 1.000, year: 2009

A polytropic model of a critical two-phase flow in a bed of spherical particles

Directory of Open Access Journals (Sweden)

Tairov Emir

2017-01-01

Full Text Available The paper is concerned with a model of isenthalpic flow of vapor-water mixture in a fixed bed of solid particles. The mixture expansion process is considered to be polytropic. Similarly to the known problem of gas dynamics of a granular bed we obtained the relationships for calculation of a critical mass velocity. The results of the calculation based on a theoretical model are compared with the experimental data obtained in the packed beds of steel balls, 2 mm and 4 mm in diameter.

Treatment of petroleum refinery wastewater containing heavily polluting substances in an aerobic submerged fixed-bed reactor.

Science.gov (United States)

Vendramel, S; Bassin, J P; Dezotti, M; Sant'Anna, G L

2015-01-01

Petroleum refineries produce large amount of wastewaters, which often contain a wide range of different compounds. Some of these constituents may be recalcitrant and therefore difficult to be treated biologically. This study evaluated the capability of an aerobic submerged fixed-bed reactor (ASFBR) containing a corrugated PVC support material for biofilm attachment to treat a complex and high-strength organic wastewater coming from a petroleum refinery. The reactor operation was divided into five experimental runs which lasted more than 250 days. During the reactor operation, the applied volumetric organic load was varied within the range of 0.5-2.4 kgCOD.m(-3).d(-1). Despite the inherent fluctuations on the characteristics of the complex wastewater and the slight decrease in the reactor performance when the influent organic load was increased, the ASFBR showed good stability and allowed to reach chemical oxygen demand, dissolved organic carbon and total suspended solids removals up to 91%, 90% and 92%, respectively. Appreciable ammonium removal was obtained (around 90%). Some challenging aspects of reactor operation such as biofilm quantification and important biofilm constituents (e.g. polysaccharides (PS) and proteins (PT)) were also addressed in this work. Average PS/volatile attached solids (VAS) and PT/VAS ratios were around 6% and 50%, respectively. The support material promoted biofilm attachment without appreciable loss of solids and allowed long-term operation without clogging. Microscopic observations of the microbial community revealed great diversity of higher organisms, such as protozoa and rotifers, suggesting that toxic compounds found in the wastewater were possibly removed in the biofilm.

Anaerobic biodegradation of pentachlorophenol in a fixed-film reactor inoculated with polluted sediment from Santos-Sao Vicente Estuary, Brazil

Energy Technology Data Exchange (ETDEWEB)

Saia, F.T.; Damianovic, M.H.R.Z.; Cattony, E.B.M.; Brucha, G.; Foresti, E. [Sao Paulo Univ., Sao Carlos (Brazil). Lab. of Biological Processes; Vazoller, R.F. [Sao Paulo Univ., Sao Paulo (Brazil). Lab. of Environmental Microbiology

2007-06-15

This paper discusses the results of pentachlorophenol (PCP) anaerobic biodegradation in a horizontal-flow anaerobic immobilized biomass (HAIB) reactor operated under methanogenic and halophylic conditions. The system was inoculated with autochthonous microorganisms taken from a site in the Santos-Sao Vicente Estuary (state of Sao Paulo, Brazil) severely contaminated with PCP, phenolic compounds, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, and heavy metals. The inoculum was previously enriched for methanogenesis activity by changing glucose concentrations and under halophylic condition. PCP was added to the HAIB reactor as sodium salt (NaPCP) at an initial concentration of 5 mg l{sup -1} and increased to 13, 15, and 21 mg l{sup -1}. Organic matter removal efficiency ranged from 77 to 100%. PCP removal efficiency was 100%. Denaturing gradient gel electrophoresis profile showed changes in the structure of Bacteria domain, which was associated with NaPCP and glucose amendments. The diversity of Archaea remained unaltered during the different phases. Scanning electron microscope examinations showed that cells morphologically resembling Methanosarcina and Methanosaeta predominated in the biofilm. These cells were detected by fluorescence in situ hybridization with the Methanosarcinales (MSMX860) specific probe. The results are of great importance in planning the estuary's restoration by using anaerobic technology and autochthonous microorganisms for bioremediation. (orig.)

A two-stage microbial fuel cell and anaerobic fluidized bed membrane bioreactor (MFC-AFMBR) system for effective domestic wastewater treatment.

KAUST Repository

Ren, Lijiao; Ahn, Yongtae; Logan, Bruce E

2014-01-01

Microbial fuel cells (MFCs) are a promising technology for energy-efficient domestic wastewater treatment, but the effluent quality has typically not been sufficient for discharge without further treatment. A two-stage laboratory-scale combined treatment process, consisting of microbial fuel cells and an anaerobic fluidized bed membrane bioreactor (MFC-AFMBR), was examined here to produce high quality effluent with minimal energy demands. The combined system was operated continuously for 50 days at room temperature (∼25 °C) with domestic wastewater having a total chemical oxygen demand (tCOD) of 210 ± 11 mg/L. At a combined hydraulic retention time (HRT) for both processes of 9 h, the effluent tCOD was reduced to 16 ± 3 mg/L (92.5% removal), and there was nearly complete removal of total suspended solids (TSS; from 45 ± 10 mg/L to <1 mg/L). The AFMBR was operated at a constant high permeate flux of 16 L/m(2)/h over 50 days, without the need or use of any membrane cleaning or backwashing. Total electrical energy required for the operation of the MFC-AFMBR system was 0.0186 kWh/m(3), which was slightly less than the electrical energy produced by the MFCs (0.0197 kWh/m(3)). The energy in the methane produced in the AFMBR was comparatively negligible (0.005 kWh/m(3)). These results show that a combined MFC-AFMBR system could be used to effectively treat domestic primary effluent at ambient temperatures, producing high effluent quality with low energy requirements.

A two-stage microbial fuel cell and anaerobic fluidized bed membrane bioreactor (MFC-AFMBR) system for effective domestic wastewater treatment.

KAUST Repository

Ren, Lijiao

2014-03-10

Microbial fuel cells (MFCs) are a promising technology for energy-efficient domestic wastewater treatment, but the effluent quality has typically not been sufficient for discharge without further treatment. A two-stage laboratory-scale combined treatment process, consisting of microbial fuel cells and an anaerobic fluidized bed membrane bioreactor (MFC-AFMBR), was examined here to produce high quality effluent with minimal energy demands. The combined system was operated continuously for 50 days at room temperature (∼25 °C) with domestic wastewater having a total chemical oxygen demand (tCOD) of 210 ± 11 mg/L. At a combined hydraulic retention time (HRT) for both processes of 9 h, the effluent tCOD was reduced to 16 ± 3 mg/L (92.5% removal), and there was nearly complete removal of total suspended solids (TSS; from 45 ± 10 mg/L to <1 mg/L). The AFMBR was operated at a constant high permeate flux of 16 L/m(2)/h over 50 days, without the need or use of any membrane cleaning or backwashing. Total electrical energy required for the operation of the MFC-AFMBR system was 0.0186 kWh/m(3), which was slightly less than the electrical energy produced by the MFCs (0.0197 kWh/m(3)). The energy in the methane produced in the AFMBR was comparatively negligible (0.005 kWh/m(3)). These results show that a combined MFC-AFMBR system could be used to effectively treat domestic primary effluent at ambient temperatures, producing high effluent quality with low energy requirements.

Effects of the reduction of the hydraulic retention time to 1.5 days at constant organic loading in CSTR, ASBR, and fixed-bed reactors – Performance and methanogenic community composition

International Nuclear Information System (INIS)

Schmidt, Thomas; Ziganshin, Ayrat M.; Nikolausz, Marcell; Scholwin, Frank; Nelles, Michael; Kleinsteuber, Sabine; Pröter, Jürgen

2014-01-01

The hydraulic retention time (HRT) is one of the key parameters in biogas processes and often it is postulated that a minimum HRT of 10–25 days is obligatory in continuous stirred tank reactors (CSTR) to prevent a washout of slow growing methanogens. In this study the effects of the reduction of the HRT from 6 to 1.5 days on performance and methanogenic community composition in different systems with and without immobilization operated with simulated thin stillage (STS) at mesophilic conditions and constant organic loading rates (OLR) of 10 g L −1 d −1 of volatile solids were investigated. With the reduction of the HRT process instability was first observed in the anaerobic sequencing batch reactor (ASBR) (at HRT of 3 days) followed by the CSTR (at HRT of 2 days). The fixed bed reactor (FBR) was stable until the end of the experiment, but the reduction of the HRT to 1.5 days caused a decrease of the specific biogas production to about 450 L kg −1 of VS compared to about 600 L kg −1 of VS at HRTs of 4–5 days. Methanoculleus and Methanosarcina were the dominant genera under stable process conditions in the CSTR and the ASBR and members of Methanosaeta and Methanospirillum were only present at HRT of 4 days and lower. In the effluent of the FBR Methanosarcina spp. were not detected and Methanosaeta spp. were more abundant then in the other reactors. - Highlights: • A CSTR was operated at high OLR of 10 (g L −1  d −1  VS) and low HRT of 3 days. • Exceeding washout of methanogenic archaea did not take place. • pH and nutrient concentrations influenced the reproduction rate more than HRT. • Methanoculleus and Methanosarcina were the dominant genera in the CSTR

Microbial monitoring of ammonia removal in a UASB reactor treating pre-digested chicken manure with anaerobic granular inoculum.

Science.gov (United States)

Yangin-Gomec, Cigdem; Pekyavas, Goksen; Sapmaz, Tugba; Aydin, Sevcan; Ince, Bahar; Akyol, Çağrı; Ince, Orhan

2017-10-01

Performance and microbial community dynamics in an upflow anaerobic sludge bed (UASB) reactor coupled with anaerobic ammonium oxidizing (Anammox) treating diluted chicken manure digestate (Total ammonia nitrogen; TAN=123±10mg/L) were investigated for a 120-d operating period in the presence of anaerobic granular inoculum. Maximum TAN removal efficiency reached to above 80% with as low as 20mg/L TAN concentrations in the effluent. Moreover, total COD (tCOD) with 807±215mg/L in the influent was removed by 60-80%. High-throughput sequencing revealed that Proteobacteria, Actinobacteria, and Firmicutes were dominant phyla followed by Euryarchaeota and Bacteroidetes. The relative abundance of Planctomycetes significantly increased from 4% to 8-9% during the late days of the operation with decreased tCOD concentration, which indicated a more optimum condition to favor ammonia removal through anammox route. There was also significant association between the hzsA gene and ammonia removal in the UASB reactor. Copyright © 2017 Elsevier Ltd. All rights reserved.

Anaerobic bacteria

Science.gov (United States)

Anaerobic bacteria are bacteria that do not live or grow when oxygen is present. In humans, these bacteria ... Brook I. Diseases caused by non-spore-forming anaerobic bacteria. In: Goldman L, Schafer AI, eds. Goldman-Cecil ...

Sludge granulation in an UASB-moving bed biofilm hybrid reactor for efficient organic matter removal and nitrogen removal in biofilm reactor.

Science.gov (United States)

Chatterjee, Pritha; Ghangrekar, M M; Rao, Surampalli

2018-02-01

A hybrid upflow anaerobic sludge blanket (UASB)-moving bed biofilm (MBB) and rope bed biofilm (RBB) reactor was designed for treatment of sewage. Possibility of enhancing granulation in an UASB reactor using moving media to improve sludge retention was explored while treating low-strength wastewater. The presence of moving media in the top portion of the UASB reactor allowed a high solid retention time even at very short hydraulic retention times and helped in maintaining selection pressure in the sludge bed to promote formation of different sized sludge granules with an average settling velocity of 67 m/h. These granules were also found to contain plenty of extracellular polymeric substance (EPS) such as 58 mg of polysaccharides (PS) per gram of volatile suspended solids (VSS) and protein (PN) content of 37 mg/g VSS. Enriched sludge of nitrogen-removing bacteria forming a porous biofilm on the media in RBB was also observed in a concentration of around 894 g/m 2 . The nitrogen removing sludge also had a high EPS content of around 22 mg PS/g VSS and 28 mg PN/g VSS. This hybrid UASB-MBB-RBB reactor with enhanced anaerobic granular sludge treating both carbonaceous and nitrogenous matter may be a sustainable solution for decentralized sewage treatment.

Raising distillate selectivity and catalyst life time in Fischer-Tropsch synthesis by using a novel dual-bed reactor

International Nuclear Information System (INIS)

Tavasoli, A.; Sadaghiani, K.; Khodadadi, A. A.; Mortazavi, Y.

2007-01-01

In a novel dual bed reactor Fischer-Tropsch synthesis was studied by using two diff rent cobalt catalysts. An alkali-promoted cobalt catalyst was used in the first bed of a fixed-bed reactor followed by a Raiment promoted cobalt catalyst in the second bed. The activity, product selectivity and accelerated deactivation of the system were assessed and compared with a conventional single bed reactor system. The methane selectivity in the dual-bed reactor was about 18.9% less compared to that of the single-bed reactor. The C 5+ selectivity for the dual-bed reactor was 10.9% higher than that of the single-bed reactor. Accelerated deactivation of the catalysts in the dual-bed reactor was 42% lower than that of the single-bed reactor. It was revealed that the amount of catalysts activity recovery after regeneration at 400 d eg C in the dual-bed system is higher than that of the single-bed system

Microbial community analysis of ambient temperature anaerobic digesters

Energy Technology Data Exchange (ETDEWEB)

Ciotola, R. [Ohio State Univ., Columbus, OH (United States). Dept. of Food, Agriculture and Biological Engineering

2010-07-01

This paper reported on a study in which designs for Chinese and Indian fixed-dome anaerobic digesters were modified in an effort to produce smaller and more affordable digesters. While these types of systems are common in tropical regions of developing countries, they have not been used in colder climates because of the low biogas yield during the winter months. Although there is evidence that sufficient biogas production can be maintained in colder temperatures through design and operational changes, there is a lack of knowledge about the seasonal changes in the composition of the microbial communities in ambient temperature digesters. More knowledge is needed to design and operate systems for maximum biogas yield in temperate climates. The purpose of this study was to cultivate a microbial community that maximizes biogas production at psychrophilic temperatures. The study was conducted on a 300 gallon experimental anaerobic digester on the campus of Ohio State University. Culture-independent methods were used on weekly samples collected from the digester in order to examine microbial community response to changes in ambient temperature. Microbial community profiles were established using universal bacterial and archaeal primers that targeted the 16S rRNA gene. In addition to the methanogenic archaea, this analysis also targeted some of the other numerically and functionally important microbial taxa in anaerobic digesters, such as hydrolytic, fermentative, acetogenic and sulfate reducing bacteria. According to preliminary results, the composition of the microbial community shifts with changes in seasonal temperature.

Adsorptive Removal of Trichloroethylene in Water by Crop Residue Biochars Pyrolyzed at Contrasting Temperatures: Continuous Fixed-Bed Experiments

Directory of Open Access Journals (Sweden)

Ming Zhang

2015-01-01

Full Text Available Biochar (BC has attracted great attention as an alternative sorbent to activated carbon (AC. Objective of this study was to determine trichloroethylene (TCE removal by soybean stover BC pyrolyzed at 300 (BC300 and 700°C (BC700 in continuous fixed-bed column. Columns packed with BC300, BC700, and AC reached breakthrough time in 1.1, 27.0, and 50.7 h, respectively. BC700 had higher TCE adsorption capacity than BC300 due to its higher surface area, nonpolarity, and aromaticity. The sorption capacities of AC (774.0 mg g−1 and BC700 (515.1 mg g−1 were 21.6 and 14.4 times higher than that of BC300 (35.9 mg g−1. The lower desorption rate of TCE from BC300 than BC700 and AC may be attributed to the strong binding/partition of TCE to the noncarbonized part of BC. Thomas model also adequately described the adsorption data indicating interphase mass transfer. Overall, AC showed best efficiency for removing TCE from water in column experiments. However, although sorption and desorption capabilities of BC700 were a little lower than AC, it is still a good alternative for AC to remove organic contaminants such as TCE from water due to its cost-effectiveness.

Cadmium removal by bioclastic granules (Lithothamnium calcareum): batch and fixed-bed column systems sorption studies.

Science.gov (United States)

Veneu, Diego Macedo; Schneider, Claudio Luiz; de Mello Monte, Marisa Bezerra; Cunha, Osvaldo Galvão Caldas; Yokoyama, Lídia

2017-06-19

The potential of Bioclastic Granules - BG (calcium-carbonate-based material) using the algae Lithothamnium calcareum as sorbent for the removal of Cd(II) from aqueous solutions by sorption was evaluated through batch and continuous systems tests using a fixed-bed column. Sorption process variables, in particular pH (2-7), particle size (<38-300 μm), initial BG concentration (0.1-1.0 g L -1 ), initial Cd(II) concentrations (5-400 mg L -1 ) and contact time (5-240 min), were evaluated. Adsorption isotherm profiles of Cd(II) per BG were similar to an L-type, or Langmuir type, with the adsorption forming a monolayer of approximately 0.61 μm, with a q max of 188.74 mg g -1 and k L of 0.710 L mg -1 . Thomas's model considers that sorption is not limited to a chemical reaction but is controlled by mass transfer at the interface. In the present study, the obtained value of k Th was 0.895 mL h -1  mg -1 , reaching a sorption capacity q o of 124.4 mg g -1 . For the Yoon-Nelson model, it was possible to obtain two important parameters to describe the behavior of the column, the rate constant (k YN ), obtaining a value of 0.09 h -1 and an τ of 82.12 h corresponding to the time required for sorption to occur of 50% of the solute in the rupture curve. X-ray diffraction and scanning electron microscopy analyses coupled to the X-ray dispersive energy system (SEM/EDS) of the BG after the Cd(II) ion sorption tests evidenced the formation of crystals with the prevalence of a new mineral phase (otavite).

Fixed-nitrogen loss associated with sinking zooplankton carcasses in a coastal oxygen minimum zone (Golfo Dulce, Costa Rica)

DEFF Research Database (Denmark)

Stief, Peter; Lundgaard, Ann Sofie Birch; Morales Ramirez, Alvaro

2017-01-01

Oxygen minimum zones (OMZs) in the ocean are of key importance for pelagic fixed-nitrogen loss (N-loss) through microbial denitrification and anaerobic ammonium oxidation (anammox). Recent studies document that zooplankton is surprisingly abundant in and around OMZs and that the microbial community...... associated with carcasses of a large copepod species mediates denitrification. Here, we investigate the complex N-cycling associated with sinking zooplankton carcasses exposed to the steep O2 gradient in a coastal OMZ (Golfo Dulce, Costa Rica). 15N-stable-isotope enrichment experiments revealed...... that the carcasses of abundant copepods and ostracods provide anoxic microbial hotspots in the pelagic zone by hosting intense anaerobic N-cycle activities even in the presence of ambient O2. Carcass-associated anaerobic N-cycling was clearly dominated by dissimilatory nitrate reduction to ammonium (DNRA) at up...

Mathematic modelling of a fixed-bed gasifier as component of a plant for decentral biomass utilisation; Mathematische Modellierung eines Festbettvergasers als Bestandteil einer Anlage zur dezentralen Nutzung von Biomasse

Energy Technology Data Exchange (ETDEWEB)

Funk, G.; Krumm, W. [Siegen Univ. (Gesamthochschule) (Germany). Lehrstuhl fuer Energie- und Umweltverfahrenstechnik

2000-07-01

This paper presents a two-dimensional nonstationary model that describes processes taking place during gasification in a fixed bed. For didactic purposes the process is split up into and described in terms of the partial models ''chemical reaction'', ''drying'', ''heat transfer'' and ''mass flow''. [German] Es wird ein zweidimensionales, instationaeres Modell zur Beschreibung der Vorgaenge bei der Vergasung im Festbett vorgestellt. Dabei werden zylinderfoermige Reaktoren betrachtet. Zur Beschreibung wird der Gesamtvorgang in die Teilmodelle 'chemische Reaktion', 'Trocknung', 'Waermeuebertragung' und 'Massefluss' unterteilt. Die einzelnen Teilmodelle werden vorgestellt. (orig.)

Characterization and performance of carbonaceous materials obtained from exhausted sludges for the anaerobic biodecolorization of the azo dye Acid Orange II

Energy Technology Data Exchange (ETDEWEB)

Athalathil, S.; Stüber, F.; Bengoa, C.; Font, J. [Departament d’Enginyeria Quimica, ETSEQ, Universitat Rovira i Virgili, Av. Paisos Catalans 26, 43007 Tarragona, Catalunya (Spain); Fortuny, A. [Departament d’Enginyeria Quimica, EPSEVG, Universitat Politecnica de Catalunya, Av. Victor Balaguer s/n, 08800 Vilanova i la Geltru, Catalunya (Spain); Fabregat, A., E-mail: azael.fabregat@urv.cat [Departament d’Enginyeria Quimica, ETSEQ, Universitat Rovira i Virgili, Av. Paisos Catalans 26, 43007 Tarragona, Catalunya (Spain)

2014-02-01

Graphical abstract: - Highlights: • Carbonaceous materials were prepared from exhausted sludge materials. • High surface area and good physicochemical properties were achieved. • Utilization of waste sludge materials and mixed anaerobic cultures were used in a continuous anaerobic UPBR system (upflow packed bed biological reactor). • Effective treatment of dye contaminated wastewater in a cheapest and environmental friendly method was demonstrated. - Abstract: This work presents the preliminary study of new carbonaceous materials (CMs) obtained from exhausted sludge, their use in the heterogeneous anaerobic process of biodecolorization of azo dyes and the comparison of their performance with one commercial active carbon. The preparation of carbonaceous materials was conducted through chemical activation and carbonization. Chemical activation was carried out through impregnation of sludge-exhausted materials with ZnCl{sub 2} and the activation by means of carbonization at different temperatures (400, 600 and 800 °C). Their physicochemical and surface characteristics were also investigated. Sludge based carbonaceous (SBC) materials SBC400, SBC600 and SBC800 present values of 13.0, 111.3 and 202.0 m{sup 2}/g of surface area. Biodecolorization levels of 76% were achieved for SBC600 and 86% for SBC800 at space time (τ) of 1.0 min, similar to that obtained with commercial activated carbons in the continuous anaerobic up-flow packed bed reactor (UPBR). The experimental data fit well to the first order kinetic model and equilibrium data are well represented by the Langmuir isotherm model. Carbonaceous materials show high level of biodecolorization even at very short space times. Results indicate that carbonaceous materials prepared from sludge-exhausted materials have outstanding textural properties and significant degradation capacity for treating textile effluents.

Bed composition generation for morphodynamic modeling: Case study of San Pablo Bay in California, USA

Science.gov (United States)

van der Wegen, M.; Dastgheib, A.; Jaffe, B.E.; Roelvink, D.

2011-01-01

Applications of process-based morphodynamic models are often constrained by limited availability of data on bed composition, which may have a considerable impact on the modeled morphodynamic development. One may even distinguish a period of "morphodynamic spin-up" in which the model generates the bed level according to some ill-defined initial bed composition rather than describing the realistic behavior of the system. The present paper proposes a methodology to generate bed composition of multiple sand and/or mud fractions that can act as the initial condition for the process-based numerical model Delft3D. The bed composition generation (BCG) run does not include bed level changes, but does permit the redistribution of multiple sediment fractions over the modeled domain. The model applies the concept of an active layer that may differ in sediment composition above an underlayer with fixed composition. In the case of a BCG run, the bed level is kept constant, whereas the bed composition can change. The approach is applied to San Pablo Bay in California, USA. Model results show that the BCG run reallocates sand and mud fractions over the model domain. Initially, a major sediment reallocation takes place, but development rates decrease in the longer term. Runs that take the outcome of a BCG run as a starting point lead to more gradual morphodynamic development. Sensitivity analysis shows the impact of variations in the morphological factor, the active layer thickness, and wind waves. An important but difficult to characterize criterion for a successful application of a BCG run is that it should not lead to a bed composition that fixes the bed so that it dominates the "natural" morphodynamic development of the system. Future research will focus on a decadal morphodynamic hindcast and comparison with measured bathymetries in San Pablo Bay so that the proposed methodology can be tested and optimized. ?? 2010 The Author(s).

Lagrangian Approach to Study Catalytic Fluidized Bed Reactors

Science.gov (United States)

Madi, Hossein; Hossein Madi Team; Marcelo Kaufman Rechulski Collaboration; Christian Ludwig Collaboration; Tilman Schildhauer Collaboration

2013-03-01

Lagrangian approach of fluidized bed reactors is a method, which simulates the movement of catalyst particles (caused by the fluidization) by changing the gas composition around them. Application of such an investigation is in the analysis of the state of catalysts and surface reactions under quasi-operando conditions. The hydrodynamics of catalyst particles within a fluidized bed reactor was studied to improve a Lagrangian approach. A fluidized bed methanation employed in the production of Synthetic Natural Gas from wood was chosen as the case study. The Lagrangian perspective was modified and improved to include different particle circulation patterns, which were investigated through this study. Experiments were designed to evaluate the concepts of the model. The results indicate that the setup is able to perform the designed experiments and a good agreement between the simulation and the experimental results were observed. It has been shown that fluidized bed reactors, as opposed to fixed beds, can be used to avoid the deactivation of the methanation catalyst due to carbon deposits. Carbon deposition on the catalysts tested with the Lagrangian approach was investigated by temperature programmed oxidation (TPO) analysis of ex-situ catalyst samples. This investigation was done to identify the effects of particles velocity and their circulation patterns on the amount and type of deposited carbon on the catalyst surface. Ecole Polytechnique Federale de Lausanne(EPFL), Paul Scherrer Institute (PSI)

Anaerobic Nitrogen Fixers on Mars

Science.gov (United States)

Lewis, B. G.

2000-07-01

The conversion of atmospheric nitrogen gas to the protein of living systems is an amazing process of nature. The first step in the process is biological nitrogen fixation, the transformation of N2 to NH3. The phenomenon is crucial for feeding the billions of our species on Earth. On Mars, the same process may allow us to discover how life can adapt to a hostile environment, and render it habitable. Hostile environments also exist on Earth. For example, nothing grows in coal refuse piles due to the oxidation of pyrite and marcasite to sulfuric acid. Yet, when the acidity is neutralized, alfalfa and soybean plants develop root nodules typical of symbiotic nitrogen fixation with Rhizobium species possibly living in the pyritic material. When split open, these nodules exhibited the pinkish color of leghemoglobin, a protein in the nodule protecting the active nitrogen-fixing enzyme nitrogenase against the toxic effects of oxygen. Although we have not yet obtained direct evidence of nitrogenase activity in these nodules (reduction of acetylene to ethylene, for example), these findings suggested the possibility that nitrogen fixation was taking place in this hostile, non-soil material. This immediately raises the possibility that freeliving anaerobic bacteria which fix atmospheric nitrogen on Earth, could do the same on Mars.

Accelerated anaerobic hydrolysis rates under a combination of intermittent aeration and anaerobic conditions

DEFF Research Database (Denmark)

Jensen, T. R.; Lastra Milone, T.; Petersen, G.

2017-01-01

Anaerobic hydrolysis in activated return sludge was investigated in laboratory scale experiments to find if intermittent aeration would accelerate anaerobic hydrolysis rates compared to anaerobic hydrolysis rates under strict anaerobic conditions. The intermittent reactors were set up in a 240 h...... for calculating hydrolysis rates based on soluble COD were compared. Two-way ANOVA with the Bonferroni post-test was performed in order to register any significant difference between reactors with intermittent aeration and strictly anaerobic conditions respectively. The experiment demonstrated a statistically...... significant difference in favor of the reactors with intermittent aeration showing a tendency towards accelerated anaerobic hydrolysis rates due to application of intermittent aeration. The conclusion of the work is thus that intermittent aeration applied in the activated return sludge process (ARP) can...

Reduction of SO sub 2 emission from a fluidized-bed under staged combustion by coarse limestone

International Nuclear Information System (INIS)

Khan, W.Z.; Gibbbs, B.M.

1998-01-01

A study was performed to investigate the effect of course limestone on the reduction of SO sub 2 emission from a fluidized-bed under staged combustion. The limestone of 1.2-2.5 mm size was premixed with fine coal of 1-3 mm size and fed under bed. The staging levels, bed height, and Ca/S ratio was fixed at 70:30, 30 cm and 3:1, respectively. A maximum of around 50% reduction in SO sub 2 emissions was achieved at both excess air of 20 and 40% and at 830 deg. C. bed temperature. The SO sub 2 emissions were very sensitive to bed temperature. The course limestone was found better in desulfurization efficiency at lower temperature than fine limestone. (author)

Microbial Communities and Their Performances in Anaerobic Hybrid Sludge Bed-Fixed Film Reactor for Treatment of Palm Oil Mill Effluent under Various Organic Pollutant Concentrations

Directory of Open Access Journals (Sweden)

Kanlayanee Meesap

2012-01-01

Full Text Available The anaerobic hybrid reactor consisting of sludge and packed zones was operated with organic pollutant loading rates from 6.2 to 8.2 g COD/L day, composed mainly of suspended solids (SS and oil and grease (O&G concentrations between 5.2 to 10.2 and 0.9 to 1.9 g/L, respectively. The overall process performance in terms of chemical oxygen demands (COD, SS, and O&G removals was 73, 63, and 56%, respectively. When the organic pollutant concentrations were increased, the resultant methane potentials were higher, and the methane yield increased to 0.30 L CH4/g CODremoved. It was observed these effects on the microbial population and activity in the sludge and packed zones. The eubacterial population and activity in the sludge zone increased to 6.4 × 109 copies rDNA/g VSS and 1.65 g COD/g VSS day, respectively, whereas those in the packed zone were lower. The predominant hydrolytic and fermentative bacteria were Pseudomonas, Clostridium, and Bacteroidetes. In addition, the archaeal population and activity in the packed zone were increased from to 9.1 × 107 copies rDNA/g VSS and 0.34 g COD-CH4/g VSS day, respectively, whereas those in the sludge zone were not much changed. The most represented species of methanogens were the acetoclastic Methanosaeta, the hydrogenotrophic Methanobacterium sp., and the hydrogenotrophic Methanomicrobiaceae.

Transforming anaerobic digestion with the Model T of digesters

Energy Technology Data Exchange (ETDEWEB)

Martin, J.F.; Ciotola, R.; Castano, J.; Eger, C.; Schlea, D. [Ohio State Univ., Columbus, OH (United States). Ecological Engineering Program

2010-07-01

Most livestock farmers in the United States do not take advantage of anaerobic digester technology because of the high cost and large scale. These limitations therefore reduce the production of renewable energy from farmlands. In order to expand anaerobic digestion methods and improve environmental quality, affordable and smaller-scale digesters should be developed to enable most livestock farmers to convert manure to methane. Doing so would improve their economic efficiency and environmental sustainability. This paper provided an analogy to the development of the Model T to better explain the need and potential for this technology. A modified fixed-dome digester was installed on the Ohio State University dairy in Columbus, Ohio. The digester was unheated, buried, had a volume of 1 m{sup 3} and received diluted dairy manure as feedstock. Biogas was produced at digester temperatures as low 10 degrees C during colder ambient temperatures. Water quality also improved. Results from the first year of operation will be analyzed to improve performance and enable future development of this technology.

Cultivation, detection, and ecophysiology of anaerobic ammonium-oxidizing bacteria.

Science.gov (United States)

Kartal, Boran; Geerts, Wim; Jetten, Mike S M

2011-01-01

Anaerobic ammonium-oxidizing (anammox) bacteria oxidize ammonium with nitrite under anoxic conditions. The anammox process is currently used to remove ammonium from wastewater and contributes significantly to the loss of fixed nitrogen from the oceans. In this chapter, we focus on the ecophysiology of anammox bacteria and describe new methodologies to grow these microorganisms. Now, it is possible to enrich anammox bacteria up to 95% with a membrane bioreactor that removes forces of selection for fast settling aggregates and facilitates the growth of planktonic cells. The biomass from this system has a high anaerobic ammonium oxidation rate (50 fmol NH(4)(+) · cell(-1) day(-1)) and is suitable for many ecophysiological and molecular experiments. A high throughput Percoll density gradient centrifugation protocol may be applied on this biomass for further enrichment (>99.5%) of anammox bacteria. Furthermore, we provide an up-to-date list of commonly used primers and introduce protocols for quantification and detection of functional genes of anammox bacteria in their natural environment. Copyright © 2011 Elsevier Inc. All rights reserved.

Anaerobic biodegradability of macropollutants

DEFF Research Database (Denmark)

Angelidaki, Irini

2002-01-01

A variety of test procedures for determination of anaerobic biodegradability has been reported. This paper reviews the methods developed for determination of anaerobic biodegradability of macro-pollutants. Anaerobic biodegradability of micro-pollutants is not included. Furthermore, factors...

Avoiding Carbon Bed Hot Spots in Thermal Process Off-Gas Systems

International Nuclear Information System (INIS)

Soelberg, Nick; Enneking, Joe

2011-01-01

Mercury has had various uses in nuclear fuel reprocessing and other nuclear processes, and so is often present in radioactive and mixed (radioactive and hazardous) wastes. Test programs performed in recent years have shown that mercury in off-gas streams from processes that treat radioactive wastes can be controlled using fixed beds of activated sulfur-impregnated carbon, to levels low enough to comply with air emission regulations such as the Hazardous Waste Combustor (HWC) Maximum Achievable Control Technology (MACT) standards. Carbon bed hot spots or fires have occurred several times during these tests, and also during a remediation of tanks that contained mixed waste. Hot spots occur when localized areas in a carbon bed become heated to temperatures where oxidation occurs. This heating typically occurs due to heat of absorption of gas species onto the carbon, but it can also be caused through external means such as external heaters used to heat the carbon bed vessel. Hot spots, if not promptly mitigated, can grow into bed fires. Carbon bed hot spots and fires must be avoided in processes that treat radioactive and mixed waste. Hot spots are detected by (a) monitoring in-bed and bed outlet gas temperatures, and (b) more important, monitoring of bed outlet gas CO concentrations. Hot spots are mitigated by (a) designing for appropriate in-bed gas velocity, for avoiding gas flow maldistribution, and for sufficient but not excessive bed depth, (b) appropriate monitoring and control of gas and bed temperatures and compositions, and (c) prompt implementation of corrective actions if bed hot spots are detected. Corrective actions must be implemented quickly if bed hot spots are detected, using a graded approach and sequence starting with corrective actions that are simple, quick, cause the least impact to the process, and are easiest to recover from.

Anaerobic Metabolism: Linkages to Trace Gases and Aerobic Processes

Science.gov (United States)

Megonigal, J. P.; Hines, M. E.; Visscher, P. T.

2003-12-01

's surface area, they have a profound influence on the biogeochemistry of the planet. This is evident from the observation that the O2 and CH4 content of Earth's atmosphere are in extreme disequilibrium (Sagan et al., 1993). The combination of high aerobic primary production and anoxic sediments provided the large deposits of fossil fuels that have become vital and contentious sources of energy for modern industrialized societies. Anaerobic metabolism is responsible for the abundance of N2 in the atmosphere; otherwise N2-fixing bacteria would have consumed most of the N2 pool long ago (Schlesinger, 1997). Anaerobic microorganisms are common symbionts of termites, cattle, and many other animals, where they aid digestion. Nutrient and pollutant chemistry are strongly modified by the reduced conditions that prevail in wetland and aquatic ecosystems.This review of anaerobic metabolism emphasizes aerobic oxidation, because the two processes cannot be separated in a complete treatment of the topic. It is process oriented and highlights the fascinating microorganisms that mediate anaerobic biogeochemistry. We begin this review with a brief discussion of CO2 assimilation by autotrophs, the source of most of the reducing power on Earth, and then consider the biological processes that harness this potential energy. Energy liberation begins with the decomposition of organic macromolecules to relatively simple compounds, which are simplified further by fermentation. Methanogenesis is considered next because CH4 is a product of acetate fermentation, and thus completes the catabolism of organic matter, particularly in the absence of inorganic electron acceptors. Finally, the organisms that use nitrogen, manganese, iron, and sulfur for terminal electron acceptors are considered in order of decreasing free-energy yield of the reactions.

Solar detoxification of fuel-contaminated groundwater using fixed-bed photocatalysts

Energy Technology Data Exchange (ETDEWEB)

Crittenden, J. C. [Michigan Technological University, Houghton, Michigan (United States); Zhang, Y.; Hand, D. W.; Perram, D. L.; Marchand, E. G.

1996-05-15

A field test of a solar photocatalytic process for detoxification of water was conducted at Tyndall Air Force Base, Florida, where benzene, toluene, ethylbenzene, and xylene (BTEX) compounds were found in the fuel-contaminated groundwater. Platinized titanium dioxide supported on silica gel is packed in tubular photoreactors and used for single-pass operations. Catalyst fouling, destruction inhibition, and water pretreatment are investigated in addition to BTEX destruction. Ionic species were found to be primarily responsible for photocatalyst fouling and destruction inhibition. A simple pretreatment unit was developed for removing turbidity, adding oxidant, and ionic species. By using pretreatment, the reactor system operated efficiently, and no loss in catalyst photoactivity was found during the month-long test. On a rainy day, BTEX compounds of a total influent concentration of more than 2 mg/L were destroyed within 6.5 minutes of empty-bed contact time. Test results with various flow rates, reactor diameters, influent concentrations, solar irradiances, and weather conditions confirm the application potential of the process.

Solar detoxification of fuel-contaminated groundwater using fixed-bed photocatalysts

International Nuclear Information System (INIS)

Crittenden, J.C.; Zhang, Y.; Hand, D.W.; Perram, D.L.; Marchand, E.G.

1996-01-01

A field test of a solar photocatalytic process for detoxification of water was conducted at Tyndall Air Force Base, Florida, where benzene, toluene, ethylbenzene, and xylene (BTEX) compounds were found in the fuel-contaminated groundwater. Platinized titanium dioxide supported on silica gel is packed in tubular photoreactors and used for single-pass operations. Catalyst fouling, destruction inhibition, and water pretreatment are investigated in addition to BTEX destruction. Ionic species were found to be primarily responsible for photocatalyst fouling and destruction inhibition. A simple pretreatment unit was developed for removing turbidity, adding oxidant, and ionic species. By using pretreatment, the reactor system operated efficiently, and no loss in catalyst photoactivity was found during the month-long test. On a rainy day, BTEX compounds of a total influent concentration of more than 2 mg/L were destroyed within 6.5 minutes of empty-bed contact time. Test results with various flow rates, reactor diameters, influent concentrations, solar irradiances, and weather conditions confirm the application potential of the process

An aerated and fluidized bed membrane bioreactor for effective wastewater treatment with low membrane fouling

KAUST Repository

Ye, Yaoli; Labarge, Nicole; Kashima, Hiroyuki; Kim, Kyoung Yeol; Hong, Pei-Ying; Saikaly, Pascal; Logan, Bruce E.

2016-01-01

Anaerobic fluidized bed membrane bioreactors (AFMBRs) use granular activated carbon (GAC) particles suspended by recirculation to effectively treat low strength wastewaters (∼100–200 mg L−1, chemical oxygen demand, COD), but the effluent can contain dissolved methane. An aerobic fluidized bed membrane bioreactor (AOFMBR) was developed to avoid methane production and the need for wastewater recirculation by using rising air bubbles to suspend GAC particles. The performance of the AOFMBR was compared to an AFMBR and a conventional aerobic membrane bioreactor (AeMBR) for domestic wastewater treatment over 130 d at ambient temperatures (fixed hydraulic retention time of 1.3 h). The effluent of the AOFMBR had a COD of 20 ± 8 mg L−1, and a turbidity of <0.2 NTU, for low-COD influent (153 ± 19 and 214 ± 27 mg L−1), similar to the AeMBR and AFMBR. For the high-COD influent (299 ± 24 mg L−1), higher effluent CODs were obtained for the AeMBR (38 ± 9 mg L−1) and AFMBR (51 ± 11 mg L−1) than the AOFMBR (26 ± 6 mg L−1). Transmembrane pressure of the AOFMBR increased at 0.04 kPa d−1, which was 20% less than the AeMBR and 57% less than the AFMBR, at the low influent COD. Scanning electron microscopy (SEM) analysis indicated a more uniform biofilm on the membrane in AOFMBR than that from the AeMBR biofilm, and no evidence of membrane damage. High similarity was found between communities in the suspended sludge in the AOFMBR and AeMBR (square-root transformed Bray–Curtis similarity, SRBCS, 0.69). Communities on the GAC and suspended sludge were dissimilar in the AOFMBR (SRBCS, 0.52), but clustered in the AFMBR (SRBCS, 0.63).

An aerated and fluidized bed membrane bioreactor for effective wastewater treatment with low membrane fouling

KAUST Repository

Ye, Yaoli

2016-09-24

Anaerobic fluidized bed membrane bioreactors (AFMBRs) use granular activated carbon (GAC) particles suspended by recirculation to effectively treat low strength wastewaters (∼100–200 mg L−1, chemical oxygen demand, COD), but the effluent can contain dissolved methane. An aerobic fluidized bed membrane bioreactor (AOFMBR) was developed to avoid methane production and the need for wastewater recirculation by using rising air bubbles to suspend GAC particles. The performance of the AOFMBR was compared to an AFMBR and a conventional aerobic membrane bioreactor (AeMBR) for domestic wastewater treatment over 130 d at ambient temperatures (fixed hydraulic retention time of 1.3 h). The effluent of the AOFMBR had a COD of 20 ± 8 mg L−1, and a turbidity of <0.2 NTU, for low-COD influent (153 ± 19 and 214 ± 27 mg L−1), similar to the AeMBR and AFMBR. For the high-COD influent (299 ± 24 mg L−1), higher effluent CODs were obtained for the AeMBR (38 ± 9 mg L−1) and AFMBR (51 ± 11 mg L−1) than the AOFMBR (26 ± 6 mg L−1). Transmembrane pressure of the AOFMBR increased at 0.04 kPa d−1, which was 20% less than the AeMBR and 57% less than the AFMBR, at the low influent COD. Scanning electron microscopy (SEM) analysis indicated a more uniform biofilm on the membrane in AOFMBR than that from the AeMBR biofilm, and no evidence of membrane damage. High similarity was found between communities in the suspended sludge in the AOFMBR and AeMBR (square-root transformed Bray–Curtis similarity, SRBCS, 0.69). Communities on the GAC and suspended sludge were dissimilar in the AOFMBR (SRBCS, 0.52), but clustered in the AFMBR (SRBCS, 0.63).

Porphyromonas gingivalis as a Model Organism for Assessing Interaction of Anaerobic Bacteria with Host Cells.

Science.gov (United States)

Wunsch, Christopher M; Lewis, Janina P

2015-12-17

Anaerobic bacteria far outnumber aerobes in many human niches such as the gut, mouth, and vagina. Furthermore, anaerobic infections are common and frequently of indigenous origin. The ability of some anaerobic pathogens to invade human cells gives them adaptive measures to escape innate immunity as well as to modulate host cell behavior. However, ensuring that the anaerobic bacteria are live during experimental investigation of the events may pose challenges. Porphyromonas gingivalis, a Gram-negative anaerobe, is capable of invading a variety of eukaryotic non-phagocytic cells. This article outlines how to successfully culture and assess the ability of P. gingivalis to invade human umbilical vein endothelial cells (HUVECs). Two protocols were developed: one to measure bacteria that can successfully invade and survive within the host, and the other to visualize bacteria interacting with host cells. These techniques necessitate the use of an anaerobic chamber to supply P. gingivalis with an anaerobic environment for optimal growth. The first protocol is based on the antibiotic protection assay, which is largely used to study the invasion of host cells by bacteria. However, the antibiotic protection assay is limited; only intracellular bacteria that are culturable following antibiotic treatment and host cell lysis are measured. To assess all bacteria interacting with host cells, both live and dead, we developed a protocol that uses fluorescent microscopy to examine host-pathogen interaction. Bacteria are fluorescently labeled with 2',7'-Bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester (BCECF-AM) and used to infect eukaryotic cells under anaerobic conditions. Following fixing with paraformaldehyde and permeabilization with 0.2% Triton X-100, host cells are labeled with TRITC phalloidin and DAPI to label the cell cytoskeleton and nucleus, respectively. Multiple images taken at different focal points (Z-stack) are obtained for temporal

Anaerobic Nitrogen Turnover by Sinking Diatom Aggregates at Varying Ambient Oxygen Levels

Directory of Open Access Journals (Sweden)

Peter eStief

2016-02-01

Full Text Available In the world’s oceans, even relatively low oxygen (O2 levels inhibit anaerobic nitrogen cycling by free-living microbes. Sinking organic aggregates, however, might provide oxygen-depleted microbial hotspots in otherwise oxygenated surface waters. Here we show that sinking diatom aggregates can host anaerobic nitrogen cycling at ambient O2 levels well above the hypoxic threshold. Aggregates were produced from the ubiquitous diatom Skeletonema marinoi and the natural microbial community of seawater. Microsensor profiling through the center of sinking aggregates revealed internal anoxia at ambient 40% air saturation (~100 µmol O2 L-1 and below. Accordingly, anaerobic nitrate turnover inside the aggregates was evident within this range of ambient O2 levels. In incubations with 15N-labeled nitrate, individual Skeletonema aggregates produced NO2- (up to 10.7 nmol N h-1 per aggregate, N2 (up to 7.1 nmol N h-1, NH4+ (up to 2.0 nmol N h-1, and N2O (up to 0.2 nmol N h-1. Intriguingly, nitrate stored inside the diatom cells served as an additional, internal nitrate source for N2 production, which may partially uncouple anaerobic nitrate turnover by diatom aggregates from direct ambient nitrate supply. Sinking diatom aggregates can contribute directly to fixed-nitrogen loss in low-oxygen environments in the ocean and vastly expand the ocean volume in which anaerobic nitrogen turnover is possible, despite relatively high ambient O2 levels. Depending on the extent of intracellular nitrate consumption during the sinking process, diatom aggregates may also be involved in the long-distance export of nitrate to the deep ocean.

Computational fluid dynamic modeling of fluidized-bed polymerization reactors

Energy Technology Data Exchange (ETDEWEB)

Rokkam, Ram [Iowa State Univ., Ames, IA (United States)

2012-01-01

Polyethylene is one of the most widely used plastics, and over 60 million tons are produced worldwide every year. Polyethylene is obtained by the catalytic polymerization of ethylene in gas and liquid phase reactors. The gas phase processes are more advantageous, and use fluidized-bed reactors for production of polyethylene. Since they operate so close to the melting point of the polymer, agglomeration is an operational concern in all slurry and gas polymerization processes. Electrostatics and hot spot formation are the main factors that contribute to agglomeration in gas-phase processes. Electrostatic charges in gas phase polymerization fluidized bed reactors are known to influence the bed hydrodynamics, particle elutriation, bubble size, bubble shape etc. Accumulation of electrostatic charges in the fluidized-bed can lead to operational issues. In this work a first-principles electrostatic model is developed and coupled with a multi-fluid computational fluid dynamic (CFD) model to understand the effect of electrostatics on the dynamics of a fluidized-bed. The multi-fluid CFD model for gas-particle flow is based on the kinetic theory of granular flows closures. The electrostatic model is developed based on a fixed, size-dependent charge for each type of particle (catalyst, polymer, polymer fines) phase. The combined CFD model is first verified using simple test cases, validated with experiments and applied to a pilot-scale polymerization fluidized-bed reactor. The CFD model reproduced qualitative trends in particle segregation and entrainment due to electrostatic charges observed in experiments. For the scale up of fluidized bed reactor, filtered models are developed and implemented on pilot scale reactor.

Anaerobic Digestion and its Applications

Science.gov (United States)

Anaerobic digestion is a natural biological process. The initials "AD" may refer to the process of anaerobic digestion, or the built systems of anaerobic digesters. While there are many kinds of digesters, the biology is basically the same for all. Anaerobic digesters are built...

Visualization of channels connecting cells in filamentous nitrogen-fixing cyanobacteria.

Science.gov (United States)

Omairi-Nasser, Amin; Haselkorn, Robert; Austin, Jotham

2014-07-01

Cyanobacteria, formerly called blue-green algae, are abundant bacteria that carry out green plant photosynthesis, fixing CO2 and generating O2. Many species can also fix N2 when reduced nitrogen sources are scarce. Many studies imply the existence of intracellular communicating channels in filamentous cyanobacteria, in particular, the nitrogen-fixing species. In a species such as Anabaena, growth in nitrogen-depleted medium, in which ∼10% of the cells differentiate into anaerobic factories for nitrogen fixation (heterocysts), requires the transport of amino acids from heterocysts to vegetative cells, and reciprocally, the transport of sugar from vegetative cells to heterocysts. Convincing physical evidence for such channels has been slim. Using improved preservation of structure by high-pressure rapid freezing of samples for electron microscopy, coupled with high-resolution 3D tomography, it has been possible to visualize and measure the dimensions of channels that breach the peptidoglycan between vegetative cells and between heterocysts and vegetative cells. The channels appear to be straight tubes, 21 nm long and 14 nm in diameter for the latter and 12 nm long and 12 nm in diameter for the former.-Omairi-Nasser, A., Haselkorn, R., Austin, J. II. Visualization of channels connecting cells in filamentous nitrogen-fixing cyanobacteria. © FASEB.

Validation of the catalytic properties of Cu-Os/13X using single fixed bed reactor in selective catalytic reduction of NO

International Nuclear Information System (INIS)

Oh, Kwang Seok; Woo, Seong Ihl

2007-01-01

Catalytic decomposition of NO over Cu-Os/13X has been carried out in a tubular fixed bed reactor at atmospheric pressure and the results were compared with literature data performed by high-throughput screening (HTS). The activity and durability of Cu-Os/13X prepared by conventional ion-exchange method have been investigated in the presence of H 2 O and SO 2 . It was found that Cu-Os/13X prepared by ion-exchange shows a high activity in a wide temperature range in selective catalytic reduction (SCR) of NO with C 3 H 6 compared to Cu/13X, proving the existence of more NO adsorption site on Cu-Os/13X. However, Cu-Os/13X exhibited low activity in the presence of water, and was quite different from the result reported in literature. SO 2 resistance is also low and does not recover its original activity when the SO 2 was blocked in the feed gas stream. This result suggested that catalytic activity between combinatorial screening and conventional testing should be compared to confirm the validity of high-throughput screening

Optimization of the pyrolysis process of empty fruit bunch (EFB) in a fixed-bed reactor through a central composite design (CCD)

Science.gov (United States)

Mohamed, Alina Rahayu; Hamzah, Zainab; Daud, Mohamed Zulkali Mohamed

2014-07-01

The production of crude palm oil from the processing of palm fresh fruit bunches in the palm oil mills in Malaysia hs resulted in a huge quantity of empty fruit bunch (EFB) accumulated. The EFB was used as a feedstock in the pyrolysis process using a fixed-bed reactor in the present study. The optimization of process parameters such as pyrolysis temperature (factor A), biomass particle size (factor B) and holding time (factor C) were investigated through Central Composite Design (CCD) using Stat-Ease Design Expert software version 7 with bio-oil yield considered as the response. Twenty experimental runs were conducted. The results were completely analyzed by Analysis of Variance (ANOVA). The model was statistically significant. All factors studied were significant with p-values oil from EFB pyrolysis process. A quadratic model equation was developed and employed to predict the highest theoretical bio-oil yield. The maximum bio-oil yield of 46.2 % was achieved at pyrolysis temperature of 442.15 °C using the EFB particle size of 866 μm which corresponded to the EFB particle size in the range of 710-1000 μm and holding time of 483 seconds.

Dynamics of Archaeal and Bacterial Communities in Response to Variations of Hydraulic Retention Time in an Integrated Anaerobic Fluidized-Bed Membrane Bioreactor Treating Benzothiazole Wastewater

Directory of Open Access Journals (Sweden)

Yue Li

2018-01-01

Full Text Available An integrated anaerobic fluidized-bed membrane bioreactor (IAFMBR was investigated to treat synthetic high-strength benzothiazole wastewater (50 mg/L at a hydraulic retention time (HRT of 24, 18, and 12 h. The chemical oxygen demand (COD removal efficiency (from 93.6% to 90.9%, the methane percentage (from 70.9% to 69.27%, and the methane yield (from 0.309 m3 CH4/kg·CODremoved to 0.316 m3 CH4/kg·CODremoved were not affected by decreasing HRTs. However, it had an adverse effect on membrane fouling (decreasing service period from 5.3 d to 3.2 d and benzothiazole removal efficiency (reducing it from 97.5% to 82.3%. Three sludge samples that were collected on day 185, day 240, and day 297 were analyzed using an Illumina® MiSeq platform. It is striking that the dominant genus of archaea was always Methanosaeta despite of HRTs. The proportions of Methanosaeta were 80.6% (HRT 24, 91.9% (HRT 18, and 91.2% (HRT 12. The dominant bacterial genera were Clostridium in proportions of 23.9% (HRT 24, 16.4% (HRT 18, and 15.3% (HRT 12, respectively.

SU-F-T-208: An Efficient Planning Approach to Posterior Fossa Tumor Bed Boosts Using Proton Pencil Beam Scanning in Fixed-Beam Room

International Nuclear Information System (INIS)

Ju, N; Chen, C; Gans, S; Hug, E; Cahlon, O; Chon, B; Tsai, H; Sine, K; Mah, D; Wolden, S; Yeh, B

2016-01-01

Purpose: A fixed-beam room could be underutilized in a multi-room proton center. We investigated the use of proton pencil beam scanning (PBS) on a fixed-beam as an alternative for posterior fossa tumor bed (PF-TB) boost treatments which were usually treating on a gantry with uniform scanning. Methods: Five patients were treated with craniospinal irradiation (CSI, 23.4 or 36.0 Gy(RBE)) followed by a PF-TB boost to 54 Gy(RBE) with proton beams. Three PF-TB boost plans were generated for each patient: (1) a uniform scanning (US) gantry plan with 4–7 posterior fields shaped with apertures and compensators (2) a PBS plan using bi-lateral and vertex fields with a 3-mm planning organ-at-risk volume (PRV) expansion around the brainstem and (3) PBS fields using same beam arrangement but replacing the PRV with robust optimization considering a 3-mm setup uncertainty. Results: A concave 54-Gy(RBE) isodose line surrounding the brainstem could be achieved using all three techniques. The mean V95% of the PTV was 99.7% (range: 97.6% to 100%) while the V100% of the PTV ranged from 56.3% to 93.1% depending on the involvement of the brainstem with the PTV. The mean doses received by 0.05 cm"3 of the brainstem were effectively identical: 54.0 Gy(RBE), 53.4 Gy(RBE) and 53.3 Gy(RBE) for US, PBS optimized with PRV, and PBS optimized with robustness plans respectively. The cochlea mean dose increased by 23% of the prescribed boost dose in average from the bi-lateral fields used in the PBS plan. Planning time for the PBS plan with PRV was 5–10 times less than the US plan and the robustly optimized PBS plan. Conclusion: We have demonstrated that a fixed-beam with PBS can deliver a dose distribution comparable to a gantry plan using uniform scanning. Planning time can be reduced substantially using a PRV around the brainstem instead of robust optimization.

SU-F-T-208: An Efficient Planning Approach to Posterior Fossa Tumor Bed Boosts Using Proton Pencil Beam Scanning in Fixed-Beam Room

Energy Technology Data Exchange (ETDEWEB)

Ju, N; Chen, C; Gans, S; Hug, E; Cahlon, O; Chon, B; Tsai, H; Sine, K; Mah, D [Procure Treatment Center, Somerset, New Jersey (United States); Wolden, S [Memorial Sloan Kettering Cancer Center, New York, NY (United States); Yeh, B [Mount Sinai Hospital, New York, NY (United States)

2016-06-15

Purpose: A fixed-beam room could be underutilized in a multi-room proton center. We investigated the use of proton pencil beam scanning (PBS) on a fixed-beam as an alternative for posterior fossa tumor bed (PF-TB) boost treatments which were usually treating on a gantry with uniform scanning. Methods: Five patients were treated with craniospinal irradiation (CSI, 23.4 or 36.0 Gy(RBE)) followed by a PF-TB boost to 54 Gy(RBE) with proton beams. Three PF-TB boost plans were generated for each patient: (1) a uniform scanning (US) gantry plan with 4–7 posterior fields shaped with apertures and compensators (2) a PBS plan using bi-lateral and vertex fields with a 3-mm planning organ-at-risk volume (PRV) expansion around the brainstem and (3) PBS fields using same beam arrangement but replacing the PRV with robust optimization considering a 3-mm setup uncertainty. Results: A concave 54-Gy(RBE) isodose line surrounding the brainstem could be achieved using all three techniques. The mean V95% of the PTV was 99.7% (range: 97.6% to 100%) while the V100% of the PTV ranged from 56.3% to 93.1% depending on the involvement of the brainstem with the PTV. The mean doses received by 0.05 cm{sup 3} of the brainstem were effectively identical: 54.0 Gy(RBE), 53.4 Gy(RBE) and 53.3 Gy(RBE) for US, PBS optimized with PRV, and PBS optimized with robustness plans respectively. The cochlea mean dose increased by 23% of the prescribed boost dose in average from the bi-lateral fields used in the PBS plan. Planning time for the PBS plan with PRV was 5–10 times less than the US plan and the robustly optimized PBS plan. Conclusion: We have demonstrated that a fixed-beam with PBS can deliver a dose distribution comparable to a gantry plan using uniform scanning. Planning time can be reduced substantially using a PRV around the brainstem instead of robust optimization.

Operation of Packed-Bed Reactors Studied in Microgravity

Science.gov (United States)

Motil, Brian J.; Balakotaiah, Vemuri

2004-01-01

The operation of a packed bed reactor (PBR) involves gas and liquid flowing simultaneously through a fixed-bed of solid particles. Depending on the application, the particles can be various shapes and sizes but are generally designed to force the two fluid phases through a tortuous route of narrow channels connecting the interstitial space. The PBR is the most common type of reactor in industry because it provides for intimate contact and high rates of transport between the phases needed to sustain chemical or biological reactions. The packing may also serve as either a catalyst or as a support for growing biological material. Furthermore, this type of reactor is relatively compact and requires minimal power to operate. This makes it an excellent candidate for unit operations in support of long-duration human space activities.

Electricity purchase agreements and distributed energy policies for anaerobic digesters

International Nuclear Information System (INIS)

Binkley, David; Harsh, Stephen; Wolf, Christopher A.; Safferman, Steven; Kirk, Dana

2013-01-01

Anaerobic digestion is increasingly recognized for its ability to produce renewable energy and reduce greenhouse gas emissions from livestock operations. In 2010, there were 2645 U.S. dairy farms with herd sizes large enough to support anaerobic digesters, yet only 156 systems were in operation (U.S. Environmental Protection Agency (U.S. EPA), 2010a. Market Opportunities for Biogas Recovery Systems at U.S. Livestock Facilities. AgSTAR Program; U.S. Environmental Protection Agency (U.S. EPA), 2011. Operational Anaerobic Digesters, Sorted by State (Dairy). AgSTAR Program.). This study analyzes the net present value of digester systems under alternative electricity purchase agreements and how returns are affected by standby charges, net metering policies and the use of feed-in-tariffs. In order for digester potential to be fully realized on a state or national level, changes to distributed energy policy are required. Results indicated that standby charges can reduce revenues from offsetting electricity by an average of nearly 20%. Net metering rules limit participation among larger farms and negatively affect profitability by restricting engine–generator size. Lastly, the effectiveness of a fixed price feed-in-tariff policy for digesters is significantly affected by project size differentiation. Digester energy policies are similar nationwide, making this study useful for government regulatory agencies and digester owners throughout the U.S. - Highlights: ► Anaerobic digester net present value was examined over a range of herd sizes. ► Standby charges reduce electricity sales revenues by an average of nearly 20%. ► Net metering rules reduce profitability by restricting engine–generator size. ► Feed-in-tariffs for digesters are significantly affected by project size.

[Current clinical significance of anaerobic bacteremia].

Science.gov (United States)

Jirsa, Roman; Marešová, Veronika; Brož, Zdeněk

2010-10-01

to estimate tje current clinical significance of anaerobic bacteremia in a group of Czech hospitals. this retrospective analysis comprised 8 444 anaerobic blood cultures in patients admitted to four Czech hospitals between 2004 and 2007. in 16 patients, blood cultures yielded significant anaerobic bacteria. Thus, anaerobic bacteremia accounted for less than 2 % of clinically significant bacteremia. Four patients (18 %) died but none of the deaths could be clearly attributable to anaerobic bacteria in the bloodstream. The most common comorbidities predisposing to anaerobic bacteremia and the most frequent sources of infection were similar to those reported by other authors. The majority of anaerobic bacteremia cases were due to gram-negative bacteria, followed by Clostridium perfringens and, surprisingly, Eubacterium spp. (particularly Eubacterium lentum). anaerobic bacteremia remains rare. The comparison of our data with those by other authors suggests that (despite the reported high mortality) the actual clinical significance of anaerobic bacteremia is rather controversial and that the anaerobic bacteremia might not correspond to more serious pathogenic role of the anaerobic bacteria as the source of infection.

Pyrolysis of waste animal fats in a fixed-bed reactor: Production and characterization of bio-oil and bio-char

Energy Technology Data Exchange (ETDEWEB)

Ben Hassen-Trabelsi, A., E-mail: aidabenhassen@yahoo.fr [Centre de Recherche et de Technologies de l’Energie (CRTEn), Technopôle Borj-Cédria, B.P 95, 2050, Hammam Lif (Tunisia); Kraiem, T. [Centre de Recherche et de Technologies de l’Energie (CRTEn), Technopôle Borj-Cédria, B.P 95, 2050, Hammam Lif (Tunisia); Département de Géologie, Université de Tunis, 2092, Tunis (Tunisia); Naoui, S. [Centre de Recherche et de Technologies de l’Energie (CRTEn), Technopôle Borj-Cédria, B.P 95, 2050, Hammam Lif (Tunisia); Belayouni, H. [Département de Géologie, Université de Tunis, 2092, Tunis (Tunisia)

2014-01-15

Highlights: • Produced bio-fuels (bio-oil and bio-char) from some animal fatty wastes. • Investigated the effects of main parameters on pyrolysis products distribution. • Determined the suitable conditions for the production of the maximum of bio-oil. • Characterized bio-oils and bio-chars obtained from several animal fatty wastes. - Abstract: Several animal (lamb, poultry and swine) fatty wastes were pyrolyzed under nitrogen, in a laboratory scale fixed-bed reactor and the main products (liquid bio-oil, solid bio-char and syngas) were obtained. The purpose of this study is to produce and characterize bio-oil and bio-char obtained from pyrolysis of animal fatty wastes. The maximum production of bio-oil was achieved at a pyrolysis temperature of 500 °C and a heating rate of 5 °C/min. The chemical (GC–MS analyses) and spectroscopic analyses (FTIR analyses) of bio-oil showed that it is a complex mixture consisting of different classes of organic compounds, i.e., hydrocarbons (alkanes, alkenes, cyclic compounds…etc.), carboxylic acids, aldehydes, ketones, esters,…etc. According to fuel properties, produced bio-oils showed good properties, suitable for its use as an engine fuel or as a potential source for synthetic fuels and chemical feedstock. Obtained bio-chars had low carbon content and high ash content which make them unattractive for as renewable source energy.

Pyrolysis of waste animal fats in a fixed-bed reactor: Production and characterization of bio-oil and bio-char

International Nuclear Information System (INIS)

Ben Hassen-Trabelsi, A.; Kraiem, T.; Naoui, S.; Belayouni, H.

2014-01-01

Highlights: • Produced bio-fuels (bio-oil and bio-char) from some animal fatty wastes. • Investigated the effects of main parameters on pyrolysis products distribution. • Determined the suitable conditions for the production of the maximum of bio-oil. • Characterized bio-oils and bio-chars obtained from several animal fatty wastes. - Abstract: Several animal (lamb, poultry and swine) fatty wastes were pyrolyzed under nitrogen, in a laboratory scale fixed-bed reactor and the main products (liquid bio-oil, solid bio-char and syngas) were obtained. The purpose of this study is to produce and characterize bio-oil and bio-char obtained from pyrolysis of animal fatty wastes. The maximum production of bio-oil was achieved at a pyrolysis temperature of 500 °C and a heating rate of 5 °C/min. The chemical (GC–MS analyses) and spectroscopic analyses (FTIR analyses) of bio-oil showed that it is a complex mixture consisting of different classes of organic compounds, i.e., hydrocarbons (alkanes, alkenes, cyclic compounds…etc.), carboxylic acids, aldehydes, ketones, esters,…etc. According to fuel properties, produced bio-oils showed good properties, suitable for its use as an engine fuel or as a potential source for synthetic fuels and chemical feedstock. Obtained bio-chars had low carbon content and high ash content which make them unattractive for as renewable source energy

A Downflow Hanging Sponge (DHS) reactor for faecal coliform removal from an Upflow Anaerobic Sludge Bed (UASB) effluent

NARCIS (Netherlands)

Yaya Beas, R.E.; Kujawa-Roeleveld, K.; Lier, van J.B.; Zeeman, G.

2015-01-01

This research was conducted to study the faecal coliforms removal capacity of Downflow Hanging Sponge (DHS) reactors as a post-treatment for an Upflow Anaerobic Sludge Blanket (UASB) reactor. Three long-term continuous lab-scale DHS reactors i.e. a reactor with cube type sponges without

Anaerobe Tolerance to Oxygen and the Potentials of Anaerobic and Aerobic Cocultures for Wastewater Treatment

Directory of Open Access Journals (Sweden)

M.T. Kato

1997-12-01

Full Text Available The anaerobic treatment processes are considered to be well-established methods for the elimination of easily biodegradable organic matter from wastewaters. Some difficulties concerning certain wastewaters are related to the possible presence of dissolved oxygen. The common belief is that anaerobes are oxygen intolerant. Therefore, the common practice is to use sequencing anaerobic and aerobic steps in separate tanks. Enhanced treatment by polishing off the residual biodegradable oxygen demand from effluents of anaerobic reactors, or the biodegradation of recalcitrant wastewater pollutants, usually requires sequenced anaerobic and aerobic bacteria activities. However, the combined activity of both bacteria can also be obtained in a single reactor. Previous experiments with either pure or mixed cultures showed that anaerobes can tolerate oxygen to a certain extent. The oxygen toxicity to methanogens in anaerobic sludges was quantified in batch experiments, as well as in anaerobic reactors. The results showed that methanogens have a high tolerance to oxygen. In practice, it was confirmed that dissolved oxygen does not constitute any detrimental effect on reactor treatment performance. This means that the coexistence of anaerobic and aerobic bacteria in one single reactor is feasible and increases the potentials of new applications in wastewater treatment

Thin-film fixed-bed reactor for solar photocatalytic inactivation of Aeromonas hydrophila: influence of water quality

Directory of Open Access Journals (Sweden)

Khan Sadia J

2012-11-01

Full Text Available Abstract Background Controlling fish disease is one of the major concerns in contemporary aquaculture. The use of antibiotics or chemical disinfection cannot provide a healthy aquaculture system without residual effects. Water quality is also important in determining the success or failure of fish production. Several solar photocatalytic reactors have been used to treat drinking water or waste water without leaving chemical residues. This study has investigated the impact of several key aspects of water quality on the inactivation of the pathogenic bacterium Aeromonas hydrophila using a pilot-scale thin-film fixed-bed reactor (TFFBR system. Results The level of inactivation of Aeromonas hydrophila ATCC 35654 was determined using a TFFBR with a photocatalytic area of 0.47 m2 under the influence of various water quality variables (pH, conductivity, turbidity and colour under high solar irradiance conditions (980–1100 W m-2, at a flow rate of 4.8 L h-1 through the reactor. Bacterial enumeration were obtained through conventional plate count using trypticase soy agar media, cultured in conventional aerobic conditions to detect healthy cells and under ROS-neutralised conditions to detect both healthy and sub-lethally injured (oxygen-sensitive cells. The results showed that turbidity has a major influence on solar photocatalytic inactivation of A. hydrophila. Humic acids appear to decrease TiO2 effectiveness under full sunlight and reduce microbial inactivation. pH in the range 7–9 and salinity both have no major effect on the extent of photoinactivation or sub-lethal injury. Conclusions This study demonstrates the effectiveness of the TFFBR in the inactivation of Aeromonas hydrophila under the influence of several water quality variables at high solar irradiance, providing an opportunity for the application of solar photocatalysis in aquaculture systems, as long as turbidity remains low.

Pathways of 3-biofules (hydrogen, ethanol and methane) production from petrochemical industry wastewater via anaerobic packed bed baffled reactor inoculated with mixed culture bacteria

International Nuclear Information System (INIS)

Elreedy, Ahmed; Tawfik, Ahmed; Enitan, Abimbola; Kumari, Sheena; Bux, Faizal

2016-01-01

Highlights: • Bio-energy production from MEG contaminated wastewater via AnPBBR, was assessed. • Maximum concurrent H_2 and CH_4 production of 6.57 and 3.57 L/d were obtained. • Maximum ethanol generation of 237.13 mg/L was observed at a HRT of 9 h. • At OLRs up to 4 gCOD/L/d, MEG biodegradability of 71–98% was achieved. • AnPBBR economically achieved shorter payback period (6.25 y), compared to ABR. - Abstract: Simultaneous production of 3-biofuels (hydrogen, ethanol and methane) as by-products of the biodegradation of petrochemical wastewater containing MEG via anaerobic packed bed baffled reactor (AnPBBR), was extensively investigated. A four-chambered reactor supported by polyurethane sheets, was operated at a constant hydraulic retention time (HRT) of 36 h and different organic loading rates (OLRs) of 0.67, 1, 2 and 4 gCOD/L/d. The maximum specific H_2 and CH_4 production rates of 438.07 ± 43.02 and 237.80 ± 21.67 ml/L/d were respectively achieved at OLR of 4 gCOD/L/d. The residual bio-ethanol significantly increased from 57.15 ± 2.31 to 240.19 ± 34.69 mg/L at increasing the OLR from 0.67 to 4 gCOD/L/d, respectively. The maximum MEG biodegradability of 98% was attained at the lowest OLR. Compartment-wise profiles revealed that the maximum H_2 and ethanol production were achieved at HRT of 9 h (1st compartment), while the CH_4 production was peaked at HRTs of 27 and 36 h (last two compartments). Kinetic studies using Stover–Kincannon and completely stirred tank reactor (CSTR) in series models were successfully applied to the AnPBBR overall and compartment-to-compartment performance, respectively. The economic evaluation strongly revealed the potentials of using AnPBBR for simultaneous treatment and bio-energy production from petrochemical wastewater as compared to the classical anaerobic baffled reactor (ABR). Microbial analysis using Illumina MiSeq sequencing showed a diversity of bacterial community in AnPBBR. Proteobacteria (36

Anaerobic treatment techniques

International Nuclear Information System (INIS)

Boehnke, B.; Bischofsberger, W.; Seyfried, C.F.

1993-01-01

This practical and theoretical guide presents the current state of knowledge in anaerobic treatment of industrial effluents with a high organic pollutant load and sewage sludges resulting from the treatment of municipal and industrial waste water. Starting from the microbiological bases of anaerobic degradation processes including a description and critical evaluation of executed plants, the book evolves the process-technical bases of anaerobic treatment techniques, derives relative applications, and discusses these with reference to excuted examples. (orig./UWA). 232 figs [de

A CFD model for biomass combustion in a packed bed furnace

Energy Technology Data Exchange (ETDEWEB)

Karim, Md. Rezwanul [Faculty of Science, Engineering and Technology, Swinburne University of Technology, VIC 3122 (Australia); Department of Mechanical & Chemical Engineering, Islamic University of Technology, Gazipur 1704 (Bangladesh); Ovi, Ifat Rabbil Qudrat [Department of Mechanical & Chemical Engineering, Islamic University of Technology, Gazipur 1704 (Bangladesh); Naser, Jamal, E-mail: jnaser@swin.edu.au [Faculty of Science, Engineering and Technology, Swinburne University of Technology, VIC 3122 (Australia)

2016-07-12

Climate change has now become an important issue which is affecting environment and people around the world. Global warming is the main reason of climate change which is increasing day by day due to the growing demand of energy in developed countries. Use of renewable energy is now an established technique to decrease the adverse effect of global warming. Biomass is a widely accessible renewable energy source which reduces CO{sub 2} emissions for producing thermal energy or electricity. But the combustion of biomass is complex due its large variations and physical structures. Packed bed or fixed bed combustion is the most common method for the energy conversion of biomass. Experimental investigation of packed bed biomass combustion is difficult as the data collection inside the bed is challenging. CFD simulation of these combustion systems can be helpful to investigate different operational conditions and to evaluate the local values inside the investigation area. Available CFD codes can model the gas phase combustion but it can’t model the solid phase of biomass conversion. In this work, a complete three-dimensional CFD model is presented for numerical investigation of packed bed biomass combustion. The model describes the solid phase along with the interface between solid and gas phase. It also includes the bed shrinkage due to the continuous movement of the bed during solid fuel combustion. Several variables are employed to represent different parameters of solid mass. Packed bed is considered as a porous bed and User Defined Functions (UDFs) platform is used to introduce solid phase user defined variables in the CFD. Modified standard discrete transfer radiation method (DTRM) is applied to model the radiation heat transfer. Preliminary results of gas phase velocity and pressure drop over packed bed have been shown. The model can be useful for investigation of movement of the packed bed during solid fuel combustion.

Innovative microbial fuel cell for electricity production from anaerobic reactors

DEFF Research Database (Denmark)

Min, Booki; Angelidaki, Irini

2008-01-01

A submersible microbial fuel cell (SMFC) was developed by immersing an anode electrode and a cathode chamber in an anaerobic reactor. Domestic wastewater was used as the medium and the inoculum in the experiments. The SMFC could successfully generate a stable voltage of 0.428 ± 0.003 V with a fixed......, a large portion of voltage drop was caused by the ohmic (electrolyte) resistance of the medium present between two electrodes, although the two electrodes were closely positioned (about 3 cm distance; internal resistance = 35 ± 2 Ω). The open circuit potential (0.393 V vs. a standard hydrogen electrode...

[Anaerobic hydrolysis of terramycin crystallizing mother solution].

Science.gov (United States)

Ma, W; Wang, J; Liang, C; Qi, R; Yang, M

2001-09-01

The terramycin crystallizing mother solution contained high organics and high nitrogen. There were many kinds of bioinhibition in it but not enough electronic donor. Anaerobic hydrolysis of terramycin crystallizing mother solution was completed with up anarobic sludge bed in order to improve the biodegradability of wastewater and electronic donor in it. The variations of pH, COD, NH4+, and SO4(2-) were monitored. The COD removal was in a narrow range between 10% and 16.4% even when the HRT of the reactor was changed from 1.5 h to 6 h. pH increased because of formation of NH3 and reduction of SO4(2-). Most of SO4(2-) was reduced to S2- when the HRT was longer than 2 h. Batch experiments on hydrolyzed wastewater demonstrated that reaction rates of nitrification and denitrification increased by 90.9% and 45.2%, respectively.

Biological nutrients removal from the supernatant originating from the anaerobic digestion of the organic fraction of municipal solid waste.

Science.gov (United States)

Malamis, S; Katsou, E; Di Fabio, S; Bolzonella, D; Fatone, F

2014-09-01

This study critically evaluates the biological processes and techniques applied to remove nitrogen and phosphorus from the anaerobic supernatant produced from the treatment of the organic fraction of municipal solid waste (OFMSW) and from its co-digestion with other biodegradable organic waste (BOW) streams. The wide application of anaerobic digestion for the treatment of several organic waste streams results in the production of high quantities of anaerobic effluents. Such effluents are characterized by high nutrient content, because organic and particulate nitrogen and phosphorus are hydrolyzed in the anaerobic digestion process. Consequently, adequate post-treatment is required in order to comply with the existing land application and discharge legislation in the European Union countries. This may include physicochemical and biological processes, with the latter being more advantageous due to their lower cost. Nitrogen removal is accomplished through the conventional nitrification/denitrification, nitritation/denitritation and the complete autotrophic nitrogen removal process; the latter is accomplished by nitritation coupled with the anoxic ammonium oxidation process. As anaerobic digestion effluents are characterized by low COD/TKN ratio, conventional denitrification/nitrification is not an attractive option; short-cut nitrogen removal processes are more promising. Both suspended and attached growth processes have been employed to treat the anaerobic supernatant. Specifically, the sequencing batch reactor, the membrane bioreactor, the conventional activated sludge and the moving bed biofilm reactor processes have been investigated. Physicochemical phosphorus removal via struvite precipitation has been extensively examined. Enhanced biological phosphorus removal from the anaerobic supernatant can take place through the sequencing anaerobic/aerobic process. More recently, denitrifying phosphorus removal via nitrite or nitrate has been explored. The removal of

Clinical features of anaerobic orthopaedic infections.

Science.gov (United States)

Lebowitz, Dan; Kressmann, Benjamin; Gjoni, Shpresa; Zenelaj, Besa; Grosgurin, Olivier; Marti, Christophe; Zingg, Matthieu; Uçkay, Ilker

2017-02-01

Some patient populations and types of orthopaedic surgery could be at particular risk for anaerobic infections. In this retrospective cohort study of operated adult patients with infections from 2004 to 2014, we assessed obligate anaerobes and considered first clinical infection episodes. Anaerobes, isolated from intra-operative samples, were identified in 2.4% of 2740 surgical procedures, of which half (33/65; 51%) were anaerobic monomicrobial infections. Propionibacterium acnes, a penicillin and vancomycin susceptible pathogen, was the predominantly isolated anaerobe. By multivariate analysis, the presence of fracture fixation plates was the variable most strongly associated with anaerobic infection (odds ratio: 2.1, 95% CI: 1.3-3.5). Anaerobes were also associated with spondylodesis and polymicrobial infections. In contrast, it revealed less likely in native bone or prosthetic joint infections and was not related to prior antibiotic use. In conclusion, obligate anaerobes in our case series of orthopaedic infections were rare, and mostly encountered in infections related to trauma with open-fracture fixation devices rather than clean surgical site infection. Anaerobes were often co-pathogens, and cultures most frequently recovered P. acnes. These observations thus do not support changes in current practices such as broader anaerobe coverage for perioperative prophylaxis.

Modeling Lab-sized Anaerobic Fluidized Bed Reactor (AFBR) for Palm Oil Mill Effluent (POME) treatment: from Batch to Continuous Reactors

Science.gov (United States)

Mufti Azis, Muhammad; Sudibyo, Hanifrahmawan; Budhijanto, Wiratni

2018-03-01

Indonesia is aiming to produce 30 million tones/year of crude palm oil (CPO) by 2020. As a result, 90 million tones/year of POME will be produced. POME is highly polluting wastewater which may cause severe environmental problem due to its high chemical oxygen demand (COD) and biochemical oxygen demand (BOD). Due to the limitation of open pond treatment, the use of AFBR has been considered as a potential technology to treat POME. This study aims to develop mathematical models of lab-sized Anaerobic Fluidized Bed Reactor (AFBR) in batch and continuous processes. In addition, the AFBR also utilized natural zeolite as an immobilized media for microbes. To initiate the biomass growth, biodiesel waste has been used as an inoculum. In the first part of this study, a batch AFBR was operated to evaluate the COD, VFA, and CH4 concentrations. By comparing the batch results with and without zeolite, it showed that the addition of 17 g/gSCOD zeolite gave larger COD decrease within 20 days of operation. In order to elucidate the mechanism, parameter estimations of 12 kinetic parameters were proposed to describe the batch reactor performance. The model in general could describe the batch experimental data well. In the second part of this study, the kinetic parameters obtained from batch reactor were used to simulate the performance of double column AFBR where the acidogenic and methanogenic biomass were separated. The simulation showed that a relatively long residence time (Hydraulic Residence Time, HRT) was required to treat POME using the proposed double column AFBR. Sensitivity analyses was conducted and revealed that μm1 appeared to be the most sensitive parameter to reduce the HRT of double column AFBR.

RISK FACTORS IN NEONATAL ANAEROBIC INFECTIONS

Directory of Open Access Journals (Sweden)

M. S. Tabib

2008-06-01

Full Text Available Anaerobic bacteria are well known causes of sepsis in adults but there are few studies regarding their role in neonatal sepsis. In an attempt to define the incidence of neonatal anaerobic infections a prospective study was performed during one year period. A total number of 400 neonates under sepsis study were entered this investigation. Anaerobic as well as aerobic cultures were sent. The patients were subjected to comparison in two groups: anaerobic culture positive and anaerobic culture negative and this comparison were analyzed statistically. There were 7 neonates with positive anaerobic culture and 35 neonates with positive aerobic culture. A significant statistical relationship was found between anaerobic infections and abdominal distention and pneumonia. It is recommended for those neonates with abdominal distention and pneumonia refractory to antibiotic treatment to be started on antibiotics with anaerobic coverage.

Preparation of a carbon molecular sieve and application to separation of N2, O2 and CO2 in a fixed bed

Directory of Open Access Journals (Sweden)

Soares J.L.

2003-01-01

Full Text Available The emission of CO2 from power plants that burn fossil fuels is the major cause of the accumulation of CO2 in the atmosphere. The separation of CO2 from CO2/air mixtures can play a key role in alleviating this problem. This separation can be carried out by using suitable adsorbents, such as carbon molecular sieves. In this work, a CMS was prepared by deposition of polyfurfuryl alcohol polymer on activated carbon. After deposition of the polymer, the material was carbonized at 800masculineC for 2 hours. This material was used to separate O2/N2 mixtures and CO2 in a fixed bed at room temperature. Experimental breakthrough curves obtained were fitted to theoretical models in order to establish the main mechanisms of mass transfer. The breakthrough curves showed that it is possible to separate O2, N2 and CO2. The shape of the breakthrough curves was not influenced by the total flow, indicating that the gas contact for the gas mixture was good. The experimental data were fitted to theoretical models and it was established that the main mechanism of mass transfer was intraparticle diffusion.

A potential application of sludge-based catalysts for the anaerobic bio-decolorization of tartrazine dye.

Science.gov (United States)

Athalathil, Sunil; Fortuny, Agusti; Font, Josep; Stüber, Frank; Bengoa, Christophe; Fabregat, Azael

2015-01-01

Two highly efficient (K2CO3/sludge carbon and ZnCl2/sludge carbon) solids were prepared by chemical addition following carbonization at 800 °C and were tested for anaerobic reduction of tartrazine dye in a continuous upflow packed-bed biological reactor, and their performance was compared to that of commercial activated carbon (CAC). The chemical and structural information of the solids was subjected to various characterizations in order to understand the mechanism for anaerobic decolorization, and efficiency for SBCZN800 and SBCPC800 materials was 87% and 74%, respectively, at a short space time (τ) of 2.0 min. A first-order kinetic model fitted the experimental points and kinetic constants of 0.40, 0.92 and 1.46 min(-1) were obtained for SBCZN800, SBCPC800 and CAC, respectively. The experimental results revealed that performance of solids in the anaerobic reduction of tartrazine dye can depend on several factors including chemical agents, carbonization, microbial population, chemical groups and surface chemistry. The Langmuir and Freundlich models are successfully described in the batch adsorption data. Based on these observations, a cost-effective sludge-based catalyst can be produced from harmful sewage sludge for the treatment of industrial effluents.

Sintering study in vertical fixed bed reactor for synthetic aggregate production; Estudo da sinterizacao em reator vertical de leito fixo para producao de agregado sintetico

Energy Technology Data Exchange (ETDEWEB)

Quaresma, D.S.; Neves, A.S.S.; Melo, A.O.; Pereira, L.F.S.; Bezerra, P.T.S.; Macedo, E.N.; Souza, J.A.S., E-mail: danysq@gmail.com [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Faculdade de Engenharia Quimica

2017-04-15

The synthetic aggregates are being employed in civil construction for the reduction of mineral extraction activities. Within this context, the recycling of industrial waste is the basis of the majority of processes to reduce the exploitation of mineral resources. In this work the sintering in a vertical fixed bed reactor for synthetic aggregate production using 20% pellets and 80% charcoal was studied. The pellets were prepared from a mixture containing clay, charcoal and fly ash. Two experiments varying the speed of air sucking were carried out. The material produced was analyzed by X-ray diffraction, scanning electron microscopy, measures of their ceramic properties, and particle size analysis. The results showed that the solid-state reactions, during the sintering process, were efficient and the produced material was classified as coarse lightweight aggregate. The process is interesting for the sintering of aggregates, and can be controlled by composition, particle size, temperature gradient and gaseous flow. (author)

Uso de leitos cultivados de fluxo vertical por batelada no pós-tratamento de efluente de reator anaeróbio compartimentado Post-treatment of effluent of anaerobic baffled reactor using batchwise vertical flow constructed wetland beds

Directory of Open Access Journals (Sweden)

Marcelo Mazzola

2005-06-01

Full Text Available Neste trabalho avaliou-se o desempenho de um Reator Anaeróbio Compartimentado (RAC de duas câmaras em série, seguido de três leitos cultivados (constructed wetlands de fluxo vertical por batelada. A unidade experimental, em escala piloto, foi instalada na Faculdade de Engenharia Agrícola - UNICAMP, Campinas, SP, Brasil. O volume total do reator era de 2,3 m³ (TDH de 12 h. O efluente do RAC foi tratado em três leitos, dois cultivados com macrófitas (gêneros Typha sp. e Eleocharis sp. e um utilizado como controle (não cultivado. Os leitos, com 2,0 m³ cada um e brita #2 (24 - 35 mm como meio suporte, operaram com fluxo vertical por batelada (com tempos de reação de 24, 48, 72 e 96 h. Na avaliação do RAC, observou-se tendência de estabilização dos parâmetros pH, alcalinidade, ácidos voláteis, sólidos sedimentáveis e suspensos totais, porém a remoção de DQO revelou-se limitada (50%. Nos leitos cultivados o aumento do tempo de reação (até 72 h foi acompanhado pelo aumento de remoção de turbidez, DQO, fósforo e nitrato. O melhor desempenho de remoção de fósforo total foi obtido no leito vegetado com Typha sp para os tempos de 72 e 96 h, respectivamente, de 30 e 25%.This study evaluated the performance of vertical constructed wetlands treating effluent of anaerobic baffled reactor. The anaerobic reactor volume was 2.3 m³; it was operated with daily flow of 4.6 m³ (12 hours Hydraulic Retention Time. The reactor effluent was split into three wetlands beds, two of them cultivated with macrophytes (Typha sp. and Eleocharis sp., and one control. The wetlands were operated as a batch reactor. The medium utilized was gravel, the size ranging from 7 to 12 mm. The reaction time for each cycle (filling - reaction - drainage was 24, 48, 72, and 96 h. The anaerobic reactor achieved the following removal rates: settable solids, 93%; suspended solids, 80%; and COD 39%. The increase in reaction time (up to 72 h for the constructed

Using multiple bed load measurements: Toward the identification of bed dilation and contraction in gravel-bed rivers

Science.gov (United States)

Marquis, G. A.; Roy, A. G.

2012-02-01

This study examines bed load transport processes in a small gravel-bed river (Béard Creek, Québec) using three complementary methods: bed elevation changes between successive floods, bed activity surveys using tags inserted into the bed, and bed load transport rates from bed load traps. The analysis of 20 flood events capable of mobilizing bed material led to the identification of divergent results among the methods. In particular, bed elevation changes were not consistent with the bed activity surveys. In many cases, bed elevation changes were significant (1 to 2 times the D50) even if the bed surface had not been activated during the flood, leading to the identification of processes of bed dilation and contraction that occurred over 10% to 40% of the bed surface. These dynamics of the river bed prevent accurate derivation of bed load transport rates from topographic changes, especially for low magnitude floods. This paper discusses the mechanisms that could explain the dilation and contraction of particles within the bed and their implications in fluvial dynamics. Bed contraction seems to be the result of the winnowing of the fine sediments under very low gravel transport. Bed dilation seems to occur on patches of the bed at the threshold of motion where various processes such as fine sediment infiltration lead to the maintenance of a larger sediment framework volume. Both processes are also influenced by flood history and the initial local bed state and in turn may have a significant impact on sediment transport and morphological changes in gravel-bed rivers.

Interactive model to assess economics of anaerobic digestion of the farm

Science.gov (United States)

1981-08-01

An interactive computer model, to provide economic assessment for on the farm anaerobic digestion systems was designed. The model is accessed as part of the MASEC Models Library. It consists of two phases: engineering analysis and economic analysis. User inputs are stored in a data base and may be retained for future use. Model outputs include a recap of user inputs, calculations for gas production, digester heat requirements, system revenues, yearly cash flow, and a graph of the net present value of the investment. The model is generalized so that nonfarm applications may also be analyzed. The program will work equally well for various digester designs such as continuously stirred reactors, plug flow systems, and fluidized bed columns.

Anaerobic digestion and co-digestion of slaughterhouse wastes

Directory of Open Access Journals (Sweden)

Sonia Castellucci

2013-09-01

Full Text Available The use of renewable energy is becoming increasingly necessary in order to address the global warming problem and, as a consequence, has become an high priority for many countries. Biomass is a clean and renewable energy source with growing potential to replace conventional fossil fuels. Among biomass, residual and waste ones represent a great resource for energy generation since they permit both to eliminate a possible waste and to produce energy. In the present work, the case of slaughterhouse wastes (SHWs has been investigated. Anaerobic digestion is nowadays considered as one of the most important and sustainable conversion technology exploiting organic matter and biodegradable wastes. Biogas results from this bio-chemical process and mainly consists of methane and carbon dioxide, leading to produce thermal energy and/or electricity. In this paper, the European Regulations on animal by-products (ABPs are described, and some previous study on anaerobic digestion and co-digestion of ABPs - more precisely SHWs - are considered and compared in order to fix a starting point for future tests on their co-digestion in a micro-scale pilot digester. This is to define optimal feed ratio values which ensure an increasing content of methane in the outgoing biogas.

Estimativa das propriedades térmicas efetivas de grãos em um secador de leito fixo Estimation of effective grain thermal properties in a fixed bed dryer

Directory of Open Access Journals (Sweden)

L. V. Fregolente

2004-06-01

Full Text Available A secagem de grãos em leito fixo é um processo complexo, ocorrendo simultaneamente a transferência de calor e de massa, dificultando a estimativa dos parâmetros térmicos efetivos, pois estes podem sofrer variações significativas no decorrer da secagem em função de alterações no teor de umidade. Neste trabalho, este problema foi contornado estimando-se os parâmetros térmicos efetivos no final da secagem, quando o teor de umidade dos grãos que compõem o leito alcança valores de equilíbrio, deixando de existir a transferência de massa, persistindo apenas a transferência de calor em regime permanente. Nestas condições, o leito possui um teor de umidade constante e a estimativa dos parâmetros térmicos efetivos pode ser efetuada a partir do ajuste de um modelo pseudo-homogêneo bidimensional estático à várias medidas de temperatura no leito de grãos no final da secagem. Os resultados indicam que a estratégia utilizada para estimativa da condutividade térmica efetiva radial e do coeficiente efetivo de transferência de calor parede-leito foi adequada. Além do que, constatou-se que dentre os grãos estudados - soja, feijão, milho e trigo - a soja apresenta os menores valores de condutividade efetiva radial, enquanto o trigo apresenta o maior valor do coeficiente de transferência de calor parede-leito.Fixed bed grain drying is a complex process, where mass and heat transfer occur simultaneously, complicating the estimation of the effective thermal parameters, because they can go through significant variations along the drying process, due to moisture content variations. In this work, this problem was avoided by estimating the effective thermal parameters at the end of the drying process, when the grain moisture content reaches equilibrium, and mass transfer stops, persisting only the steady state heat transfer. In these conditions, the bed has a constant moisture content and the estimation of the effective thermal

Carbon Bed Mercury Emissions Control For Mixed Waste Treatment

International Nuclear Information System (INIS)

Soelberg, Nick; Enneking, Joe

2010-01-01

Mercury has had various uses in nuclear fuel reprocessing and other nuclear processes, and so is often present in radioactive and mixed (both radioactive and hazardous according to the Resource Conservation and Recovery Act) wastes. Depending on regulatory requirements, the mercury in the off-gas must be controlled with sometimes very high efficiencies. Compliance to the Hazardous Waste Combustor (HWC) Maximum Achievable Control Technology (MACT) standards can require off-gas mercury removal efficiencies up to 99.999% for thermally treating some mixed waste streams. Several test programs have demonstrated this level of off-gas mercury control using fixed beds of granular sulfur-impregnated activated carbon. Other results of these tests include: (a) The depth of the mercury control mass transfer zone was less than 15-30 cm for the operating conditions of these tests, (b) MERSORB(reg s ign) carbon can sorb Hg up to 19 wt% of the carbon mass, and (c) the spent carbon retained almost all (98-99.99%) of the Hg; but when even a small fraction of the total Hg dissolves, the spent carbon can fail the TCLP test when the spent carbon contains high Hg concentrations. Localized areas in a carbon bed that become heated through heat of adsorption, to temperatures where oxidation occurs, are referred to as 'bed hot spots.' Carbon bed hot spots must be avoided in processes that treat radioactive and mixed waste. Key to carbon bed hot spot mitigation are (a) designing for sufficient gas velocity, for avoiding gas flow maldistribution, and for sufficient but not excessive bed depth, (b) monitoring and control of inlet gas flowrate, temperature, and composition, (c) monitoring and control of in-bed and bed outlet gas temperatures, and (d) most important, monitoring of bed outlet CO concentrations. An increase of CO levels in the off-gas downstream of the carbon bed to levels about 50-100 ppm higher than the inlet CO concentration indicate CO formation in the bed, caused by carbon bed

In-situ catalytic upgrading of biomass pyrolysis vapor: Co-feeding with methanol in a multi-zone fixed bed reactor

International Nuclear Information System (INIS)

Asadieraghi, Masoud; Wan Daud, Wan Mohd Ashri

2015-01-01

Highlights: • Aromatics yield improved with increasing H/C eff ratio of the feed. • HZSM-5 catalyst was an effective catalyst for in-situ bio-oil upgrading. • Biomass/methanol co-feeding attenuated the coke formation. • Methanol co-feeding enhanced the bio-oil quality. - Abstract: The in-situ catalytic upgrading of the biomass pyrolysis vapor and its mixture with methanol were conducted in a fixed bed multi-zone reactor. The steps were comprised; thermally converting the biomass in the pyrolysis reactor, passing its vapor in contact with the HZSM-5 zeolite catalyst in the presence of methanol vapor, and transformation of the resulting upgraded pyrolysis vapor into the liquid product. The biomass pyrolysis and catalytic pyrolysis vapor upgrading were performed at 500 °C. The highly valuable chemicals production was a function of the hydrogen to carbon effective ratio (H/C eff ) of the feed. This ratio was regulated by changing the relative amount of biomass and methanol. More aromatic hydrocarbons (50.02 wt.%) and less coke deposition on the catalyst (1.3 wt.%) were yielded from the biomass, when methanol was co-fed to the catalytic pyrolysis process (H/C eff = 1.35). In this contribution, the deposited coke on the catalyst was profoundly investigated. The coke, with high contents of oxo-aromatics and aromatic compounds, was generated by polymerization of biomass lignin derived components activated by catalyst acid sites

Characterization of biofilm in 200W fluidized bed reactors

Energy Technology Data Exchange (ETDEWEB)

Lee, Michelle H. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Saurey, Sabrina D. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Lee, Brady D. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Parker, Kent E. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Eisenhauer, Emalee E. R. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Cordova, Elsa A. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Golovich, Elizabeth C. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

2014-09-29

Contaminated groundwater beneath the 200 West Area at the Hanford Site in Southeast Washington is currently being treated using a pump and treat system to remove organics, inorganics, radionuclides, and metals. A granular activated carbon-based fluidized bed reactor (FBR) has been added to remove nitrate, hexavalent chromium and carbon tetrachloride. Initial analytical results indicated the microorganisms effectively reduced many of the contaminants to less than cleanup levels. However shortly thereafter operational upsets of the FBR include carbon carry over, over production of microbial extracellular polymeric substance (biofilm) materials, and over production of hydrogen sulfide. As a result detailed investigations were undertaken to understand the functional diversity and activity of the microbial community present in the FBR over time. Molecular analyses including terminal restriction fragment length polymorphism analysis, quantitative polymerase chain reaction and fluorescent in situ hybridization analyses were performed on the microbial community extracted from the biofilm within the bed and from the inoculum, to determine functional dynamics of the FBR bed over time and following operational changes. Findings from these analyses indicated: 1) the microbial community within the bed was completely different than community used for inoculation, and was likely from the groundwater; 2) analyses early in the testing showed an FBR community dominated by a few Curvibacter and Flavobacterium species; 3) the final sample taken indicated that the microbial community in the FBR bed had become more diverse; and 4) qPCR analyses indicated that bacteria involved in nitrogen cycling, including denitrifiers and anaerobic ammonia oxidizing bacteria, were dominant in the bed. These results indicate that molecular tools can be powerful for determining functional diversity within FBR type reactors. Coupled with micronutrient, influent and effluent chemistry

Modeling and Performance of Waste Tires as Media in Fixed Bed Sequence Batch Reactor

Directory of Open Access Journals (Sweden)

Zahra Derakhshan

2016-12-01

Results: The maximum removal efficiencies of dissolved chemical oxygen demand for FBSBR and SBR reactors were 98.3 % and 97.9 %, respectively. In addition, Stover-Kincannon model provided a very suitable fitness (R2   > 0.99 for loading the bioreactor FBSBR. Conclusion: According to the results, not only waste tires can be reused, but also these wastes can be employed as a proper biological bed in wastewater refineries to improve their efficiency.