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Sample records for sludge bed reactor

  1. Modelling of a falling sludge bed reactor using AQUASIM | Ristow ...

    African Journals Online (AJOL)

    Modelling of a falling sludge bed reactor using AQUASIM. ... AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search · USING AJOL · RESOURCES ... a system of mixed reactors connected by water flow and mass flux streams.

  2. 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

  3. Celebrating 40 years anaerobic sludge bed reactors for industrial wastewater treatment

    NARCIS (Netherlands)

    Van Lier, J.B.; Van der Zee, F.P.; Frijters, C.T.M.J.; Ersahin, M.E.

    2015-01-01

    In the last 40 years, anaerobic sludge bed reactor technology evolved from localized lab-scale trials to worldwide successful implementations at a variety of industries. High-rate sludge bed reactors are characterized by a very small foot print and high applicable volumetric loading rates. Best

  4. Sludge combustion in fluidized bed reactors at laboratory scale

    International Nuclear Information System (INIS)

    Chirone, R.; Cammarota, A.

    2001-01-01

    The combustion of a dried sewage sludge in laboratory scale fluidized bed has been studied in Naples by the Istituto di ricerche sulla combustione (Irc) in the framework of a National project named Thermal Process with Energy Recovery to be used in laboratory and pre-pilot scale apparatus. The attention has been focused on emissions of unreacted carbon as elutriated fines, on the emissions of pollutant gases and on the assessment of the inventory of fly- and bottom ashes. The combustion behaviour of sewage sludge has been compared with those of a market available Tyre Derived Fuel (TDF) and a biomass from Mediterranean area (Robinia Pseudoacacia) and with that of a South African bituminous coal. Stationary combustion tests were carried out at 850 0 C by feeding particles in the size range 0-1 mm into a bed of silica sand without any sorbent addition. The fluidized bed combustor has been operated, at a superficial gas velocity of 0.4 m/s and different excesses of air ranging between 14 and 98%. Relatively high combustion efficiency, larger than 98.9% has been obtained in experiments carried out with sewage sludge and excess of air larger than 20%. These values, are comparable with those obtained in previously experimental activity carried out under similar operative conditions with a South Africa Bituminous coal (97-98%). It is larger than those obtained by using a Tyre Derived Fuel (89-90%) and the Robinia Pseudoacacia Biomass (93-93%). The relative importance of carbon fines elutriation, CO emissions and volatile bypassing the bed in determining the loss of combustion efficiency has been evaluated for the different fuels tested [it

  5. 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

  6. 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.

  7. 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.

  8. Recovery of energy and iron from oily sludge pyrolysis in a fluidized bed reactor.

    Science.gov (United States)

    Qin, Linbo; Han, Jun; He, Xiang; Zhan, Yiqiu; Yu, Fei

    2015-05-01

    In the steel industry, about 0.86 ton of oily sludge is produced for every 1000 tons of rolling steel. Due to the adverse impact on human health and the environment, oily sludge is designated as a hazardous waste in the Resource Conservation and Recovery Act (RCRT). In this paper, the pyrolysis treatment of oily sludge is studied in a fluidized bed reactor at a temperature range of 400-600 °C. During oily sludge pyrolysis, a maximum oil yield of 59.2% and a minimum energy loss of 19.0% are achieved at 500 °C. The energy consumption of treating 1 kg oily sludge is only 2.4-2.9 MJ. At the same time, the energy of produced oil, gas and solid residue are 20.8, 6.32, and 0.83 MJ, respectively. In particular, it is found that the solid residue contains more than 42% iron oxide, which can be used as the raw material for iron production. Thus, the simultaneous recovery of energy and iron from oil sludge by pyrolysis is feasible. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Modelling of a falling sludge bed reactor using AQUASIM

    African Journals Online (AJOL)

    drinie

    2001-10-04

    Oct 4, 2001 ... products are then used for the biological treatment of acid mine drainage. A mathematical ... solid matter into three valleys inside the reactor, as opposed to an ... conversion of PSS in the presence of sulphate-reducing bacteria ... indicate substrate flow (stoichiometrically) in the form of COD ..... fermentation.

  10. Influence of mass transfer resistance on overall nitrate removal rate in upflow sludge bed reactors.

    Science.gov (United States)

    Ting, Wen-Huei; Huang, Ju-Sheng

    2006-09-01

    A kinetic model with intrinsic reaction kinetics and a simplified model with apparent reaction kinetics for denitrification in upflow sludge bed (USB) reactors were proposed. USB-reactor performance data with and without sludge wasting were also obtained for model verification. An independent batch study showed that the apparent kinetic constants k' did not differ from the intrinsic k but the apparent Ks' was significantly larger than the intrinsic Ks suggesting that the intra-granule mass transfer resistance can be modeled by changes in Ks. Calculations of the overall effectiveness factor, Thiele modulus, and Biot number combined with parametric sensitivity analysis showed that the influence of internal mass transfer resistance on the overall nitrate removal rate in USB reactors is more significant than the external mass transfer resistance. The simulated residual nitrate concentrations using the simplified model were in good agreement with the experimental data; the simulated results using the simplified model were also close to those using the kinetic model. Accordingly, the simplified model adequately described the overall nitrate removal rate and can be used for process design.

  11. 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.

  12. 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.

  13. Combustion of Dried Sewage Sludge in a Fluidized-Bed Reactor

    Czech Academy of Sciences Publication Activity Database

    Hartman, Miloslav; Svoboda, Karel; Pohořelý, Michael; Trnka, Otakar

    2005-01-01

    Roč. 44, č. 10 (2005), s. 3432-3441 ISSN 0888-5885 R&D Projects: GA AV ČR(CZ) IAA4072201 Institutional research plan: CEZ:AV0Z40720504 Keywords : fluidized-bed combustion * dried sewage sludge * CO, NOx, and N2O emissions Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.504, year: 2005

  14. Bio-oil production from dry sewage sludge by fast pyrolysis in an electrically-heated fluidized bed reactor

    Directory of Open Access Journals (Sweden)

    Renato O. Arazo

    2017-01-01

    Full Text Available The optimization of bio-oil produced from sewage sludge using fast pyrolysis in a fluidized bed reactor was investigated. Effects of temperature, sludge particle size and vapor residence time on bio-oil properties, such as yield, high heating value (HHV and moisture content were evaluated through experimental and statistical analyses. Characterization of the pyrolysis products (bio-oil and biogas was also done. Optimum conditions produced a bio-oil product with an HHV that is nearly twice as much as lignocellulosic-derived bio-oil, and with properties comparable to heavy fuel oil. Contrary to generally acidic bio-oil, the sludge-derived bio-oil has almost neutral pH which could minimize the pipeline and engine corrosions. The Fourier Transform Infrared and gas-chromatography and mass spectrometry analyses of bio-oil showed a dominant presence of gasoline-like compounds. These results demonstrate that fast pyrolysis of sewage sludge from domestic wastewater treatment plant is a favorable technology to produce biofuels for various applications.

  15. Antibiotic Fermentation Broth Treatment by a pilot upflow anaerobic sludge bed reactor and kinetic modeling.

    Science.gov (United States)

    Coskun, T; Kabuk, H A; Varinca, K B; Debik, E; Durak, I; Kavurt, C

    2012-10-01

    In this study, an upflow anaerobic sludge blanket (UASB) mesophilic reactor was used to remove antibiotic fermentation broth wastewater. The hydraulic retention time was held constant at 13.3 days. The volumetric organic loading value increased from 0.33 to 7.43 kg(COD)m(-3)d(-1) using antibiotic fermentation broth wastewater gradually diluted with various ratios of domestic wastewater. A COD removal efficiency of 95.7% was obtained with a maximum yield of 3,700 L d(-1) methane gas production. The results of the study were interpreted using the modified Stover-Kincannon, first-order, substrate mass balance and Van der Meer and Heertjes kinetic models. The obtained kinetic coefficients showed that antibiotic fermentation broth wastewater can be successfully treated using a UASB reactor while taking COD removal and methane production into account. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Chemical and ecotoxicological characterization of ashes obtained from sewage sludge combustion in a fluidised-bed reactor.

    Science.gov (United States)

    Lapa, N; Barbosa, R; Lopes, M H; Mendes, B; Abelha, P; Boavida, D; Gulyurtlu, I; Oliveira, J Santos

    2007-08-17

    In 1999, the DEECA/INETI and the UBiA/FCT/UNL started a researching project on the partition of heavy metals during the combustion of stabilised sewage sludge (Biogran), in a fluidised-bed reactor, and on the quality of the bottom ashes and fly ashes produced. This project was entitled Bimetal and was funded by the Portuguese Foundation for Science and Technology. In this paper only the results on the combustion of Biogran are reported. The combustion process was performed in two different trials, in which different amounts of sewage sludge and time of combustion were applied. Several ash samples were collected from the bed (bottom ashes) and from two cyclones (first cyclone and second cyclone ashes). Sewage sludge, bed material (sand) and ash samples were submitted to the leaching process defined in the European leaching standard EN 12457-2. The eluates were characterized for a set of inorganic chemical species. The ecotoxicological levels of the eluates were determined for two biological indicators (Vibrio fischeri and Daphnia magna). The results were compared with the limit values of the CEMWE French Regulation. The samples were also ranked according to an index based on the chemical characterization of the eluates. It was observed an increase of the concentration of metals along the combustion system. The ashes trapped in the second cyclone, for both combustion trials, showed the highest concentration of metals in the eluates. Chemically, the ashes of the second cyclone were the most different ones. In the ecotoxicological point of view, the ecotoxicity levels of the eluates of the ashes, for both combustion cycles, did not follow the same pattern as observed for the chemical characterization. The ashes of the first cyclone showed the highest ecotoxicity levels for V. fischeri and D. magna. This difference on chemical and ecotoxicological results proves the need for performing both chemical and ecotoxicological characterizations of the sub-products of such type

  17. Chemical and ecotoxicological characterization of ashes obtained from sewage sludge combustion in a fluidised-bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lapa, N. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal)]. E-mail: ncsn@fct.unl.pt; Barbosa, R. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal); Lopes, M.H. [National Institute of Engineering, Technology and Innovation (INETI), Department of Energetic Engineering and Environmental Control (DEECA). Edificio J, Estrada do Paco do Lumiar, 22, 1649-038 Lisbon (Portugal); Mendes, B. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal); Abelha, P. [National Institute of Engineering, Technology and Innovation (INETI), Department of Energetic Engineering and Environmental Control (DEECA). Edificio J, Estrada do Paco do Lumiar, 22, 1649-038 Lisbon (Portugal); Gulyurtlu, I. [National Institute of Engineering, Technology and Innovation (INETI), Department of Energetic Engineering and Environmental Control (DEECA). Edificio J, Estrada do Paco do Lumiar, 22, 1649-038 Lisbon (Portugal); Santos Oliveira, J. [Environmental Biotechnology Researching Unit (UBiA), Faculty of Science and Technology (FCT), New University of Lisbon - UNL, Ed. Departamental, piso 3, gabinete 377, Quinta da Torre, 2829-516 Caparica (Portugal)

    2007-08-17

    In 1999, the DEECA/INETI and the UBiA/FCT/UNL started a researching project on the partition of heavy metals during the combustion of stabilised sewage sludge (Biogran[reg]), in a fluidised-bed reactor, and on the quality of the bottom ashes and fly ashes produced. This project was entitled Bimetal and was funded by the Portuguese Foundation for Science and Technology. In this paper only the results on the combustion of Biogran[reg]) are reported. The combustion process was performed in two different trials, in which different amounts of sewage sludge and time of combustion were applied. Several ash samples were collected from the bed (bottom ashes) and from two cyclones (first cyclone and second cyclone ashes). Sewage sludge, bed material (sand) and ash samples were submitted to the leaching process defined in the European leaching standard EN 12457-2. The eluates were characterized for a set of inorganic chemical species. The ecotoxicological levels of the eluates were determined for two biological indicators (Vibrio fischeri and Daphnia magna). The results were compared with the limit values of the CEMWE French Regulation. The samples were also ranked according to an index based on the chemical characterization of the eluates. It was observed an increase of the concentration of metals along the combustion system. The ashes trapped in the second cyclone, for both combustion trials, showed the highest concentration of metals in the eluates. Chemically, the ashes of the second cyclone were the most different ones. In the ecotoxicological point of view, the ecotoxicity levels of the eluates of the ashes, for both combustion cycles, did not follow the same pattern as observed for the chemical characterization. The ashes of the first cyclone showed the highest ecotoxicity levels for V. fischeri and D. magna. This difference on chemical and ecotoxicological results proves the need for performing both chemical and ecotoxicological characterizations of the sub

  18. Chemical and ecotoxicological characterization of ashes obtained from sewage sludge combustion in a fluidised-bed reactor

    International Nuclear Information System (INIS)

    Lapa, N.; Barbosa, R.; Lopes, M.H.; Mendes, B.; Abelha, P.; Gulyurtlu, I.; Santos Oliveira, J.

    2007-01-01

    In 1999, the DEECA/INETI and the UBiA/FCT/UNL started a researching project on the partition of heavy metals during the combustion of stabilised sewage sludge (Biogran[reg]), in a fluidised-bed reactor, and on the quality of the bottom ashes and fly ashes produced. This project was entitled Bimetal and was funded by the Portuguese Foundation for Science and Technology. In this paper only the results on the combustion of Biogran[reg]) are reported. The combustion process was performed in two different trials, in which different amounts of sewage sludge and time of combustion were applied. Several ash samples were collected from the bed (bottom ashes) and from two cyclones (first cyclone and second cyclone ashes). Sewage sludge, bed material (sand) and ash samples were submitted to the leaching process defined in the European leaching standard EN 12457-2. The eluates were characterized for a set of inorganic chemical species. The ecotoxicological levels of the eluates were determined for two biological indicators (Vibrio fischeri and Daphnia magna). The results were compared with the limit values of the CEMWE French Regulation. The samples were also ranked according to an index based on the chemical characterization of the eluates. It was observed an increase of the concentration of metals along the combustion system. The ashes trapped in the second cyclone, for both combustion trials, showed the highest concentration of metals in the eluates. Chemically, the ashes of the second cyclone were the most different ones. In the ecotoxicological point of view, the ecotoxicity levels of the eluates of the ashes, for both combustion cycles, did not follow the same pattern as observed for the chemical characterization. The ashes of the first cyclone showed the highest ecotoxicity levels for V. fischeri and D. magna. This difference on chemical and ecotoxicological results proves the need for performing both chemical and ecotoxicological characterizations of the sub

  19. 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

  20. Formation of metabolites during biodegradation of linear alkylbenzene sulfonate in an upflow anaerobic sludge bed reactor under thermophilic conditions

    DEFF Research Database (Denmark)

    Mogensen, Anders Skibsted; Ahring, Birgitte Kiær

    2002-01-01

    Biodegradation of linear alkylbenzene sulfonate (LAS) was shown in an upflow anaerobic sludge blanket reactor under thermophilic conditions. The reactor was inoculated with granular biomass and fed with a synthetic medium and 3 mumol/L of a mixture of LAS with alkylchain length of 10 to 13 carbon...

  1. Pyrolysis of high-ash sewage sludge in a circulating fluidized bed reactor for production of liquids rich in heterocyclic nitrogenated compounds.

    Science.gov (United States)

    Zuo, Wu; Jin, Baosheng; Huang, Yaji; Sun, Yu; Li, Rui; Jia, Jiqiang

    2013-01-01

    A circulating fluidized bed reactor was used for pyrolyzing sewage sludge with a high ash content to produce liquids rich in heterocyclic nitrogenated compounds. GC/MS and FTIR analyses showed that heterocyclic nitrogenated compounds and hydrocarbons made up 38.5-61.21% and 2.24-17.48% of the pyrolysis liquids, respectively. A fluidized gas velocity of 1.13 m/s, a sludge feed rate of 10.78 kg/h and a particle size of 1-2mm promoted heterocyclic nitrogenated compound production. Utilizing heterocyclic nitrogenated compounds as chemical feedstock could be a way for offsetting the cost of sewage sludge treatment. Copyright © 2012 Elsevier Ltd. All rights reserved.

  2. Synergetic effect of sewage sludge and biomass co-pyrolysis: A combined study in thermogravimetric analyzer and a fixed bed reactor

    International Nuclear Information System (INIS)

    Wang, Xuebin; Deng, Shuanghui; Tan, Houzhang; Adeosun, Adewale; Vujanović, Milan; Yang, Fuxin; Duić, Neven

    2016-01-01

    Highlights: • The synergetic effect of sewage sludge and wheat straw co-pyrolysis was studied. • The mass balance measurement of gas, tar, and char was performed. • The synergetic effect shows strongest under a certain biomass addition ratio around 60%. • The required heat of co-pyrolysis is significantly reduced. - Abstract: Much attention has been given to the valuable products from the pyrolysis of sewage sludge. In this study, the pyrolysis of sewage sludge, biomass (wheat straw) and their mixtures in different proportions were carried out in a thermogravimetric analyzer (TGA) and fixed-bed reactor. The effects of pyrolysis temperature and percentage of wheat straw in wheat straw–sewage sludge mixtures on product distributions in terms of gas, liquid and char and the gas composition were investigated. Results indicate that there is a significantly synergetic effect during the co-pyrolysis processes of sewage sludge and wheat straw, accelerating the pyrolysis reactions. The synergetic effect resulted in an increase in gas and liquid yields but a decrease in char yield. The gas composition and the synergetic effect degree are strongly affected by the wheat straw proportions, and the strongest synergetic effect of sewage sludge and wheat straw co-pyrolysis appears at the biomass proportion of 60 wt.%. With an increase of temperature, the gas yield from the pyrolysis of sewage sludge increased but the liquid and char yields decreased. Moreover, the required heat of co-pyrolysis is significantly reduced compared with the pyrolysis of sewage sludge and wheat straw pyrolysis alone, because of the exothermic reactions between the ash components in two fuel samples.

  3. Biohydrogen production from ethanol-type fermentation of molasses in an expanded granular sludge bed (EGSB) reactor

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Wan-Qian; Ren, Nan-Qi; Ding, Jie; Qu, Yuan-Yuan; Zhang, Lu-Si [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Haihe Road 204, Nangang District, Harbin, Heilongjiang 150090 (China); Wang, Xiang-Jing; Xiang, Wen-Sheng [Research Center of Life Science and Biotechnology, Northeast Agricultural University, Harbin 150030 (China); Meng, Zhao-Hui [The Architectural Design and Research Institute of Harbin Institute of Technology, Harbin 150090 (China)

    2008-10-15

    An expanded granular sludge bed (EGSB) process with granular activated carbon (GAC) was developed for fermentative hydrogen production from molasses-containing wastewater by mixed microbial cultures. No pH regulation was performed during the whole operation period. Running at the temperature of 35 C, the EGSB reactor presented a high hydrogen production ability as the hydrogen production rate (HPR) maximized at 0.71 L/L h. At the same time, the hydrogen yield (HY) peaked at 3.47 mol/mol sucrose and the maximum specific hydrogen production rate (SHPR) was found to be 3.16 mmol H{sub 2}/g VSS h. Hydrogen volume content was estimated to be 30-53% of the total biogas and the biogas was free of methane throughout the study. Dissolved fermentation products were predominated by acetate and ethanol, with smaller quantities of propionate, butyrate and valerate. It was found that high hydrogen yield was always associated with a high level of ethanol production. When the pH value and alkalinity ranged from 4.2-4.4 mg CaCO{sub 3}/L to 280-340 mg CaCO{sub 3}/L, respectively, stable ethanol-type fermentation was formed with the sum of ethanol and acetate concentration ratio of 89.1% to the total liquid products. The average attached biofilm concentration was estimated to be 17.1 g/L, which favored hydrogen production efficiently. With high biomass retention at high organic loading rate (OLR), this EGSB system showed to be a promising high-efficient bioprocess for hydrogen production from high-strength wastewater. (author)

  4. Anaerobic expanded granular sludge bed (EGSB) reactor for the removal of sulphide by autotrophic denitrification

    Energy Technology Data Exchange (ETDEWEB)

    Dinamarca, Carlos [Department of Process, Energy and Environment, Faculty of Technology, Telemark University College Kjolnes ring 56, 3918 Porsgrunn (Norway)

    2013-07-01

    The Removal efficiency, load and N/S molar ratio, of an EGSB reactor for autotrophic sulphide denitrification operated for 96 days, were studied. The reactor was operated at high inlet sulphide concentrations between 0.25 to 3.00 g HS--S/L equivalents to loads between 5 to 250 g HS--S/m3-h. Sulphide removals higher than 99 % were achieved. At a N/S molar ratio of 0.3 and 12 hours HRT the process was stable even during transition periods of influent sulphide concentration and pH (9.0-12.1). At N/S molar ratio of 1.3, granules lost some of their sedimentation properties and appeared to disintegrate. On average 94 ± 4 % of the equivalent inlet sulphur ended as elemental sulphur.

  5. Evaluation of co-pyrolysis petrochemical wastewater sludge with lignite in a thermogravimetric analyzer and a packed-bed reactor: Pyrolysis characteristics, kinetics, and products analysis.

    Science.gov (United States)

    Mu, Lin; Chen, Jianbiao; Yao, Pikai; Zhou, Dapeng; Zhao, Liang; Yin, Hongchao

    2016-12-01

    Co-pyrolysis characteristics of petrochemical wastewater sludge and Huolinhe lignite were investigated using thermogravimetric analyzer and packed-bed reactor coupled with Fourier transform infrared spectrometer and gas chromatography. The pyrolysis characteristics of the blends at various sludge blending ratios were compared with those of the individual materials. Thermogravimetric experiments showed that the interactions between the blends were beneficial to generate more residues. In packed-bed reactor, synergetic effects promoted the release of gas products and left less liquid and solid products than those calculated by additive manner. Fourier transform infrared spectrometer analysis showed that main functional groups in chars gradually disappeared with pyrolysis temperatures increasing, and H 2 O, CH 4 , CO, and CO 2 appeared in volatiles during pyrolysis. Gas compositions analysis indicated that, the yields of H 2 and CO clearly increased as the pyrolysis temperature and sludge blending ratio increasing, while the changes of CH 4 and CO 2 yields were relatively complex. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. 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.

  7. Biodegradation of benzotriazoles and hydroxy-benzothiazole in wastewater by activated sludge and moving bed biofilm reactor systems

    DEFF Research Database (Denmark)

    Mazioti, Aikaterini A.; Stasinakis, Athanasios S.; Pantazi, Ypapanti

    2015-01-01

    Two laboratory scale fully aerated continuous flow wastewater treatment systems were used to compare the removal of five benzotriazoles and one benzothiazole by suspended and attached growth biomass. The Activated Sludge system was operated under low organic loading conditions. The Moving Bed...... in significantly lower biodegradation for 4 out of 6 examined compounds. Calculation of specific removal rates (normalised to biomass) revealed that attached biomass had higher biodegradation potential for target compounds comparing to suspended biomass. Clear differences in the biodegradation ability of attached...... biomass grown in different bioreactors of MBBR systems were also observed. Batch experiments showed that micropollutants biodegradation by both types of biomass is co-metabolic....

  8. Pressurized Fluidized Bed Combustion of Sewage Sludge

    Science.gov (United States)

    Suzuki, Yoshizo; Nojima, Tomoyuki; Kakuta, Akihiko; Moritomi, Hiroshi

    A conceptual design of an energy recovering system from sewage sludge was proposed. This system consists of a pressurized fluidized bed combustor, a gas turbine, and a heat exchanger for preheating of combustion air. Thermal efficiency was estimated roughly as 10-25%. In order to know the combustion characteristics of the sewage sludge under the elevated pressure condition, combustion tests of the dry and wet sewage sludge were carried out by using laboratory scale pressurized fluidized bed combustors. Combustibility of the sewage sludge was good enough and almost complete combustion was achieved in the combustion of the actual wet sludge. CO emission and NOx emission were marvelously low especially during the combustion of wet sewage sludge regardless of high volatile and nitrogen content of the sewage sludge. However, nitrous oxide (N2O) emission was very high. Hence, almost all nitrogen oxides were emitted as the form of N2O. From these combustion tests, we judged combustion of the sewage sludge with the pressurized fluidized bed combustor is suitable, and the conceptual design of the power generation system is available.

  9. 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

  10. System for the Reduction of Substances in Reject Water from Reed-Bed Sludge Mineralization Plants

    DEFF Research Database (Denmark)

    2004-01-01

    The invention is a system for the reduction of substances in reject water from reed-bed sludge mineralization plants (also referred to as sludge dewatering reed-beds). The systems utilizes the composition of substances in reject water from reed-beds and that of sludge to reduce substance mass from...... the reject water via recirculation into a mixed reactor and back onto the reed-beds. The mixed rector consists of a container in which sludge (that is typically loaded directly on to reed-beds) is mixed with recirculated reject water from reed-beds. The sludge mixture has a definable hydraulic retention time...... of by sending it back to the head of a wastewater treatment plant. The system has proven to reduce the mass of nitrogen, COD, and water in the reject water, and can possibly reduce phosphorus and other substances. The overall effect is a reduction in the substance recycle within a wastewater treatment plant...

  11. Simultaneous biohydrogen production and starch wastewater treatment in an acidogenic expanded granular sludge bed reactor by mixed culture for long-term operation

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Wan-Qian; Ren, Nan-Qi; Liu, Bing-Feng; Ding, Jie [State Key Lab of Urban Water Resource and Environ, Harbin Institute of Technology, Harbin 150090 (China); Chen, Zhao-Bo [School of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Wang, Xiang-Jing; Xiang, Wen-Sheng [Research Center of Life Science and Biotechnology, Northeast Agricultural University, Harbin 150030 (China)

    2008-12-15

    The biofilm-based expanded granular sludge bed (EGSB) reactor was developed to treat starch-containing wastewater and simultaneously recovery hydrogen by mixed microbial culture. Granular activated carbon (GAC) was used as the support media. Operating at the temperature of 30 C for over 400 days (data not shown), the EGSB reactor presented high efficiency in hydrogen production and COD removal ability. The maximum hydrogen production rate (HPR) was found to be 1.64 L/L.d under the organic loading rate (OLR) of 1.0 g-starch/L.d, pH of 4.42 and HRT of 4 h. The hydrogen yield (HY) peaked at 0.11 L/g-COD, under the OLR of 0.5 g-starch/L.d, pH of 3.95 and HRT of 8 h. Hydrogen volume content was estimated to be 35-65% of the total biogas. The average COD removal rate was 31.1% under the OLR of 0.125 g-starch/L.d and HRT of 24 h. The main dissolved fermentation products were ethanol, acetate and butyrate. The average attached biofilm concentration was estimated to be 8.26 g/L, which favored hydrogen production and COD removal. It is speculated that the low pH operation in the present system would contribute significantly to lower the cost of alkaline amount required for pH control in the continuous operation, especially in the scale-up biohydrogen producing system. A model, built on the back propagation neural network (BPNN) theory and linear regression techniques, was developed for the simulation of EGSB system performance in the biodegradation of starch synthesis-based wastewater and simultaneous hydrogen production. The model well fitted the laboratory data, and could well simulate the removal of COD and the production of hydrogen in the EGSB reactor. (author)

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. Particle bed reactor modeling

    Science.gov (United States)

    Sapyta, Joe; Reid, Hank; Walton, Lew

    The topics are presented in viewgraph form and include the following: particle bed reactor (PBR) core cross section; PBR bleed cycle; fuel and moderator flow paths; PBR modeling requirements; characteristics of PBR and nuclear thermal propulsion (NTP) modeling; challenges for PBR and NTP modeling; thermal hydraulic computer codes; capabilities for PBR/reactor application; thermal/hydralic codes; limitations; physical correlations; comparison of predicted friction factor and experimental data; frit pressure drop testing; cold frit mask factor; decay heat flow rate; startup transient simulation; and philosophy of systems modeling.

  17. Pebble-bed reactor

    International Nuclear Information System (INIS)

    Lohnert, G.; Mueller-Frank, U.; Heil, J.

    1976-01-01

    A pebble-bed nuclear reactor of large power rating comprises a container having a funnel-shaped bottom forming a pebble run-out having a centrally positioned outlet. A bed of downwardly-flowing substantially spherical nuclear fuel pebbles is positioned in the container and forms a reactive nuclear core maintained by feeding unused pebbles to the bed's top surface while used or burned-out pebbles run out and discharge through the outlet. A substantially conical body with its apex pointing upwardly and its periphery spaced from the periphery of the container spreads the bottom of the bed outwardly to provide an annular flow down the funnel-shaped bottom forming the runout, to the discharge outlet. This provides a largely constant downward velocity of the spheres throughout the diameter of the bed throughout a substantial portion of the down travel, so that all spheres reach about the same burned-out condition when they leave the core, after a single pass through the core area

  18. Modeling of Seepage Losses in Sewage Sludge Drying Bed ...

    African Journals Online (AJOL)

    This research was carried out to develop a model governing seepage losses in sewage sludge drying bed. The model will assist in the design of sludge drying beds for effective management of wastes derived from households' septic systems. In the experiment conducted this study, 125kg of sewage sludge, 90.7% moisture ...

  19. Biogas production from potato-juice, a by-product from potato-starch processing, in upflow anaerobic sludge blanket (UASB) and expanded granular sludge bed (EGSB) reactors

    DEFF Research Database (Denmark)

    Fang, Cheng; Boe, Kanokwan; Angelidaki, Irini

    2011-01-01

    In this study, the utilization of potato-juice, the organic by-product from potato-starch processing, for biogas production was investigated in batch assay and in high rate anaerobic reactors. The maximum methane potential of the potato-juice determined by batch assay was 470mL-CH4/gVS-added. Ana......In this study, the utilization of potato-juice, the organic by-product from potato-starch processing, for biogas production was investigated in batch assay and in high rate anaerobic reactors. The maximum methane potential of the potato-juice determined by batch assay was 470mL-CH4/g...

  20. 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).

  1. 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)

  2. Gas fluidized bed reactor

    International Nuclear Information System (INIS)

    Bernardelli, H. da C.

    1976-03-01

    The equations of motion for both gas and particles in a gas fluidised system are stablished through general assumptions which are generally accepted on physical grounds. The resulting model is used to study the velocity fields of each phase in the case of an isolated bubble rising close to the flat distributor plate. A well posed problem results for the solution of Laplace's equation of the potential flow of the particles when consideration is given to the presence of the distributor as a boundary condition. The corresponding stream functions are also obtained which enable the drawing of the motion patterns using numerical techniques. The following two dimensional cases are analysed: S/b=1; S/b=1,5; S/b=2,5; S/b=5 and the limiting case S/b→αinfinite. The results for the interphase exchange between bubbles and particulate phases are applied to a gas fluidised bed reactor and its effect on the chemical conversion is studied for the simplest cases of piston flow and perfect mixing in the particulate phase [pt

  3. 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.

  4. Gravity Drainage of Activated Sludge on Reed Beds

    DEFF Research Database (Denmark)

    Christensen, Morten Lykkegaard; Dominiak, Dominik Marek; Keiding, Kristian

    and operation of reed beds and the efficiencies are often lower than predicted. One reason is that the sludge quality varies from plant to plant and even within plants from time to time. No good method exists for measuring the sludge quality with respect to drainage characteristics. A new experimental method...... has therefore been developed to measure relevant quality parameters: specific cake resistance, settling velocity and cake compressibility. It has been found that activated sludge form highly compressible cake even at the low compressive pressures obtained during drainage. Numerical simulation shows......Activated sludge is a by-product from waste water treatment plants, and the water content in the sludge is high (> 90%). Among several methods to remove the water, sludge drying reed beds are often used to dewater the sludge by drainage. There is, however, no well-defined criterion for design...

  5. Particle Bed Reactor scaling relationships

    International Nuclear Information System (INIS)

    Slovik, G.; Araj, K.; Horn, F.L.; Ludewig, H.; Benenati, R.

    1987-01-01

    Scaling relationships for Particle Bed Reactors (PBRs) are discussed. The particular applications are short duration systems, i.e., for propulsion or burst power. Particle Bed Reactors can use a wide selection of different moderators and reflectors and be designed for such a wide range of power and bed power densities. Additional design considerations include the effect of varying the number of fuel elements, outlet Mach number in hot gas channel, etc. All of these variables and options result in a wide range of reactor weights and performance. Extremely light weight reactors (approximately 1 kg/MW) are possible with the appropriate choice of moderator/reflector and power density. Such systems are very attractive for propulsion systems where parasitic weight has to be minimized

  6. A biodegradation and treatment of palm oil mill effluent (POME) using a hybrid up-flow anaerobic sludge bed (HUASB) Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Habeeb, S.A.; Latiff, AB. Aziz Abdul; Daud, Zawawi; Ahmad, Zulkifli [Faculty of Civil and Enviromental Engineering, University Tun Hussein Onn (Malaysia)

    2011-07-01

    Generally, anaerobic treatment has become a viable alternative in support of industrial wastewater treatment. Particularly, it is used in common to treat the palm oil mill effluent (POME). This study was carried out to assess the start-up performance of a bioreactor hybrid up-flow anaerobic sludge blanket (HUASB). Whereby, three identical reactors of 7.85-l capacity R1, R2, and R3 were operated for 57 days in order to provide two alienated comparisons. Identical operation conditions of organic loading rate (OLR) and hydraulic retention time (HRT) of 1.85 kg.m-3.day-1, and 2.6 day, respectively. R1 was operated in room temperature of 28{+-}2 C, and packed with palm oil shell as filter medium support. R2 was set with room temperature but packed with course gravel. R3 was provided with water bath system to adjust its temperature at 37{+-}1 C mesophilic, while its filter material had to be palm oil shell. During the whole operation period R3 was more efficient for organic materials, where a chemical oxygen demand (COD) removal efficiency of 82% was registered, while R1 and R2 were relatively less efficient of 78%, and 76%, respectively. Furthermore, TSS removal of R3 was also higher than R1, and R2 as registered 80%, 77% and 76%, respectively. On the other hand, turbidity and colour removal were not efficient and needed a post treatment. The seeded sludge was developed in each reactor as illustrated in this paper. Therefore, all reactors show favorable performance of anaerobic treatability of POME as well as good response of microbial species development.

  7. Activated Sludge and Aerobic Biofilm Reactors

    OpenAIRE

    Von Sperling, Marcos

    2007-01-01

    "Activated Sludge and Aerobic Biofilm Reactors is the fifth volume in the series Biological Wastewater Treatment. The first part of the book is devoted to the activated sludge process, covering the removal of organic matter, nitrogen and phosphorus.A detailed analysis of the biological reactor (aeration tank) and the final sedimentation tanks is provided. The second part of the book covers aerobic biofilm reactors, especially trickling filters, rotating biological contractors and submerged ae...

  8. Sludge combustion in fluidized bed reactors at laboratory scale; Esperienze di combustione di fanghi in reattori a letto fluido in scala di laboratorio

    Energy Technology Data Exchange (ETDEWEB)

    Chirone, R.; Cammarota, A. [Consiglio Nazionale delle Ricerche, Istituto di Ricerche sulla Combustione, Naples (Italy)

    2001-03-01

    The combustion of a dried sewage sludge in laboratory scale fluidized bed has been studied in Naples by the Istituto di ricerche sulla combustione (Irc) in the framework of a National project named Thermal Process with Energy Recovery to be used in laboratory and pre-pilot scale apparatus. The attention has been focused on emissions of unreacted carbon as elutriated fines, on the emissions of pollutant gases and on the assessment of the inventory of fly- and bottom ashes. The combustion behaviour of sewage sludge has been compared with those of a market available Tyre Derived Fuel (TDF) and a biomass from Mediterranean area (Robinia Pseudoacacia) and with that of a South African bituminous coal. Stationary combustion tests were carried out at 850{sup 0} C by feeding particles in the size range 0-1 mm into a bed of silica sand without any sorbent addition. The fluidized bed combustor has been operated, at a superficial gas velocity of 0.4 m/s and different excesses of air ranging between 14 and 98%. Relatively high combustion efficiency, larger than 98.9% has been obtained in experiments carried out with sewage sludge and excess of air larger than 20%. These values, are comparable with those obtained in previously experimental activity carried out under similar operative conditions with a South Africa Bituminous coal (97-98%). It is larger than those obtained by using a Tyre Derived Fuel (89-90%) and the Robinia Pseudoacacia Biomass (93-93%). The relative importance of carbon fines elutriation, CO emissions and volatile bypassing the bed in determining the loss of combustion efficiency has been evaluated for the different fuels tested. [Italian] Il lavoro riporta l'attivita' di ricerca condotta presso l'Istituto di ricerche sulla combustione (Irc-Cnr) nell'ambito del Progetto Processi termici con recupero di energia per lo smaltimento di fanghi e rifiuti speciali, sottoprogetto Combustione in letti fluidi in scala di laboratorio e pre-pilota di

  9. Performance of Sandy Dry Beds for sludge dewatering

    International Nuclear Information System (INIS)

    Al-Muzaini, S.

    2003-01-01

    Sludge produced by the Jahra treatment plant was assessed. The assessment was directed at determining the performance of sand drying beds. The assessment of quality of the sludge produced was based on the standards for land application of sewage sludge. Analyses were carried out for trace heavy metals and bacteria. The results of analyses showed that the sludge produced was high in organic matter and sand content but low in heavy metals. The collected data indicated that the sand drying beds at the Jahra treatment plant are at present inadequate to handle the projected sludge production. The investigation showed that the sand drying beds are fully used and the plant will require 3-4 times the capacity of the existing drying beds when the plant becomes fully operational. In addition, these sand drying beds are subjected to uncontrollable conditions such as temperature, rainfall and sludge drainage rate. Thus, sand drying beds have become less popular as a dewatering system. This paper evaluates the performance of the existing sand drying beds and suggests the most appropriate technology to alleviate the above mentioned problems. (author)

  10. Fluidized-bed nuclear reactor

    International Nuclear Information System (INIS)

    Grimmett, E.S.; Kunze, J.F.

    1975-01-01

    A reactor vessel containing a fluidized-bed region of particulate material including both a neutron-moderating and a fertile substance is described. A gas flow including fissile material passes through the vessel at a sufficient rate to fluidize the particulate material and at a sufficient density to support a thermal fission reaction within the fluidized-bed region. The high-temperature portion of a heat transfer system is located within the fluidized-bed region of the reactor vessel in direct contact with the fluidized particles. Heat released by fission is thereby transferred at an enhanced rate to a coolant circulating within the heat transfer system. Fission products are continuously removed from the gas flow and supplemental fissile material added during the reactor operation. (U.S.)

  11. Incineration of Sludge in a Fluidized-Bed Combustor

    OpenAIRE

    Chien-Song Chyang; Yu-Chi Wang

    2017-01-01

    For sludge disposal, incineration is considered to be better than direct burial because of regulations and space limitations in Taiwan. Additionally, burial after incineration can effectively prolong the lifespan of a landfill. Therefore, it is the most satisfactory method for treating sludge at present. Of the various incineration technologies, the fluidized bed incinerator is a suitable choice due to its fuel flexibility. In this work, sludge generated from industrial plants was treated in ...

  12. Modeling of Evaporation Losses in Sewage Sludge Drying Bed ...

    African Journals Online (AJOL)

    A model for evaporation losses in sewage sludge drying bed was derived from first principles. This model was developed based on the reasoning that the rate at which evaporation is taking place is directly proportional to the instantaneous quantity of water in the sludge. The aim of this work was to develop a model to assist ...

  13. 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.

  14. Anaerobic Treatment Of Percolate From Faecal Sludge Drying Beds ...

    African Journals Online (AJOL)

    Composite percolate samples, from sludge drying beds of a pilot co-composting plant in Kumasi, Ghana, were characterised and subjected to laboratory scale anaerobic treatment. Two categories of percolate samples were investigated; samples seeded with anaerobic sludge and samples without seeding. The average ...

  15. Gas composition of sludge residue profiles in a sludge treatment reed bed between loadings

    DEFF Research Database (Denmark)

    Larsen, Julie Dam; Nielsen, Steen M; Scheutz, Charlotte

    2017-01-01

    Treatment of sludge in sludge treatment reed bed systems includes dewatering and mineralization. The mineralization process, which is driven by microorganisms, produces different gas species as by-products. The pore space composition of the gas species provides useful information on the biological...... processes occurring in the sludge residue. In this study, we measured the change in composition of gas species in the pore space at different depth levels in vertical sludge residue profiles during a resting period of 32 days. The gas composition of the pore space in the sludge residue changed during...

  16. Phenotypic properties and microbial diversity of methanogenic granules from a full-scale upflow anaerobic sludge bed reactor treating brewery wastewater.

    Science.gov (United States)

    Díaz, Emiliano E; Stams, Alfons J M; Amils, Ricardo; Sanz, José L

    2006-07-01

    Methanogenic granules from an anaerobic bioreactor that treated wastewater of a beer brewery consisted of different morphological types of granules. In this study, the microbial compositions of the different granules were analyzed by molecular microbiological techniques: cloning, denaturing gradient gel electrophoresis and fluorescent in situ hybridization (FISH), and scanning and transmission electron microscopy. We propose here that the different types of granules reflect the different stages in the life cycle of granules. Young granules were small, black, and compact and harbored active cells. Gray granules were the most abundant granules. These granules have a multilayer structure with channels and void areas. The core was composed of dead or starving cells with low activity. The brown granules, which were the largest granules, showed a loose and amorphous structure with big channels that resulted in fractured zones and corresponded to the older granules. Firmicutes (as determined by FISH) and Nitrospira and Deferribacteres (as determined by cloning and sequencing) were the predominant Bacteria. Remarkably, Firmicutes could not be detected in the brown granules. The methanogenic Archaea identified were Methanosaeta concilii (70 to 90% by FISH and cloning), Methanosarcina mazei, and Methanospirillum spp. The phenotypic appearance of the granules reflected the physiological condition of the granules. This may be valuable to easily select appropriate seed sludges to start up other reactors.

  17. 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.

  18. Methanol degradation in granular sludge reactors at sub-optimal metal concentrations: role of iron, nickel and cobalt

    NARCIS (Netherlands)

    Zandvoort, M.H.; Geerts, R.; Lettinga, G.; Lens, P.N.L.

    2003-01-01

    The effect of sub-optimal trace metal concentrations on the conversion of methanol in an upflow anaerobic sludge bed (UASB) reactor was investigated by studying the effect of decreased influent trace metal concentrations on the reactor efficiency, methanol conversion route and sludge

  19. 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

  20. Anaerobic granular sludge and biofilm reactors

    DEFF Research Database (Denmark)

    Skiadas, Ioannis V.; Gavala, Hariklia N.; Schmidt, Jens Ejbye

    2003-01-01

    by the immobilization of the biomass, which forms static biofilms, particle-supported biofilms, or granules depending on the reactor's operational conditions. The advantages of the high-rate anaerobic digestion over the conventional aerobic wastewater treatment methods has created a clear trend for the change......-rate anaerobic treatment systems based on anaerobic granular sludge and biofilm are described in this chapter. Emphasis is given to a) the Up-flow Anaerobic Sludge Blanket (UASB) systems, b) the main characteristics of the anaerobic granular sludge, and c) the factors that control the granulation process...

  1. MIT pebble bed reactor project

    Energy Technology Data Exchange (ETDEWEB)

    Kadak, Andrew C. [Massachusetts Institute of Technology, Cambridge (United States)

    2007-03-15

    The conceptual design of the MIT modular pebble bed reactor is described. This reactor plant is a 250 Mwth, 120 Mwe indirect cycle plant that is designed to be deployed in the near term using demonstrated helium system components. The primary system is a conventional pebble bed reactor with a dynamic central column with an outlet temperature of 900 C providing helium to an intermediate helium to helium heat exchanger (IHX). The outlet of the IHX is input to a three shaft horizontal Brayton Cycle power conversion system. The design constraint used in sizing the plant is based on a factory modularity principle which allows the plant to be assembled 'Lego' style instead of constructed piece by piece. This principle employs space frames which contain the power conversion system that permits the Lego-like modules to be shipped by truck or train to sites. This paper also describes the research that has been conducted at MIT since 1998 on fuel modeling, silver leakage from coated fuel particles, dynamic simulation, MCNP reactor physics modeling and air ingress analysis.

  2. MIT pebble bed reactor project

    International Nuclear Information System (INIS)

    Kadak, Andrew C.

    2007-01-01

    The conceptual design of the MIT modular pebble bed reactor is described. This reactor plant is a 250 Mwth, 120 Mwe indirect cycle plant that is designed to be deployed in the near term using demonstrated helium system components. The primary system is a conventional pebble bed reactor with a dynamic central column with an outlet temperature of 900 C providing helium to an intermediate helium to helium heat exchanger (IHX). The outlet of the IHX is input to a three shaft horizontal Brayton Cycle power conversion system. The design constraint used in sizing the plant is based on a factory modularity principle which allows the plant to be assembled 'Lego' style instead of constructed piece by piece. This principle employs space frames which contain the power conversion system that permits the Lego-like modules to be shipped by truck or train to sites. This paper also describes the research that has been conducted at MIT since 1998 on fuel modeling, silver leakage from coated fuel particles, dynamic simulation, MCNP reactor physics modeling and air ingress analysis

  3. Particle bed reactor scaling relationships

    Science.gov (United States)

    Slovik, G.; Araj, K.; Horn, F. L.; Ludewig, H.; Benenati, R.

    The Particle Bed Reactor (PBR) concept can be used in several applications both as part of a power generating system or as a direct propulsion unit. In order to carry out optimization studies of systems involving a PBR, it is necessary to know the variation of the critical mass with pertinent system parameters such as weight, size, power level and thrust level. A parametric study is presented for all the practical combinations of fuel and moderating material. The PBR is described, the practical combinations of materials and dimensions are discussed, and an example is presented.

  4. Gas composition of sludge residue profiles in a sludge treatment reed bed between loadings.

    Science.gov (United States)

    Larsen, Julie D; Nielsen, Steen M; Scheutz, Charlotte

    2017-11-01

    Treatment of sludge in sludge treatment reed bed systems includes dewatering and mineralization. The mineralization process, which is driven by microorganisms, produces different gas species as by-products. The pore space composition of the gas species provides useful information on the biological processes occurring in the sludge residue. In this study, we measured the change in composition of gas species in the pore space at different depth levels in vertical sludge residue profiles during a resting period of 32 days. The gas composition of the pore space in the sludge residue changed during the resting period. As the resting period proceeded, atmospheric air re-entered the pore space at all depth levels. The methane (CH 4 ) concentration was at its highest during the first part of the resting period, and then declined as the sludge residue became more dewatered and thereby aerated. In the pore space, the concentration of CH 4 often exceeded the concentration of carbon dioxide (CO 2 ). However, the total emission of CO 2 from the surface of the sludge residue exceeded the total emission of CH 4 , suggesting that CO 2 was mainly produced in the layer of newly applied sludge and/or that CO 2 was emitted from the sludge residue more readily compared to CH 4 .

  5. Bacterial regrowth potential in alkaline sludges from open-sun and covered sludge drying beds

    Energy Technology Data Exchange (ETDEWEB)

    Alkan, U.; Topac, F.O.; Birden, B.; Baskaya, H.S. [Uludag University, Gorukle (Turkey). Dept. of Environmnetal Engineering

    2007-10-15

    The aim of this study was to compare the regrowth potentials of wastewater sludges dried in two pilot-scale drying processes namely, Open-Sun Sludge Drying Bed (OSDB) and Covered Sludge Drying Bed (CSDB). Quicklime and/or coal fly ash were added to raw sludge samples prior to drying processes in order to enhance bacterial inactivation. Following three drying cycles (March-April, June-July and August-October), sludge samples were taken from the beds for the regrowth experiments. Addition of alkaline materials prevented the regrowth of faecal coliforms in all rewetted samples except for the samples obtained after the rainfall events in OSDB. Rewetting of these samples in the regrowth experiments increased faecal coliform numbers by 3.5-7 log units. In contradiction, the observed bacterial numbers in rewetted alkaline samples from CSDB were below the EPA Class B criterion (2 million MPN g{center_dot} 1) dry sludge). The combination of additional heat from solar collectors, protection from the rain and the unfavourable living conditions owing to alkaline materials appeared to inactivate bacteria more effectively in CSDB and hence eliminated regrowth potential more efficiently.

  6. Particle Bed Reactor engine technology

    Science.gov (United States)

    Sandler, S.; Feddersen, R.

    1992-03-01

    This paper discusses the Particle Bed Reactor (PBR) based propulsion system being developed under the Space Nuclear Thermal Propulsion (SNTP) program. A PBR engine is a light weight, compact propulsion system which offers significant improvement over current technology systems. Current performance goals are a system thrust of 75,000 pounds at an Isp of 1000 sec. A target thrust to weight ratio (T/W) of 30 has been established for an unshielded engine. The functionality of the PBR, its pertinent technology issues and the systems required to make up a propulsion system are described herein. Accomplishments to date which include hardware development and tests for the PBR engine are also discussed. This paper is intended to provide information on and describe the current state-of-the-art of PBR technology.

  7. Particle Bed Reactor engine technology

    International Nuclear Information System (INIS)

    Sandler, S.; Feddersen, R.

    1992-01-01

    This paper discusses the Particle Bed Reactor (PBR) based propulsion system being developed under the Space Nuclear Thermal Propulsion (SNTP) program. A PBR engine is a light weight, compact propulsion system which offers significant improvement over current technology systems. Current performance goals are a system thrust of 75,000 pounds at an Isp of 1000 sec. A target thrust to weight ratio (T/W) of 30 has been established for an unshielded engine. The functionality of the PBR, its pertinent technology issues and the systems required to make up a propulsion system are described herein. Accomplishments to date which include hardware development and tests for the PBR engine are also discussed. This paper is intended to provide information on and describe the current state-of-the-art of PBR technology. 4 refs

  8. Effect of NaCl on thermophilic (55°C) methanol degradation in sulfate reducing granular sludge reactors

    NARCIS (Netherlands)

    Vallero, M.V.G.; Hulshoff Pol, L.W.; Lettinga, G.; Lens, P.N.L.

    2003-01-01

    The effect of NaCl on thermophilic (55degreesC) methanol conversion in the presence of excess of sulfate (COD/SO42-=0.5) was investigated in two 6.5L lab-scale upflow anaerobic sludge bed reactors inoculated with granular sludge previously not adapted to NaCl
    The effect of NaCl on thermophilic

  9. DEGRADATION OF AROMATIC COMPOUNDS USING MOVING BED BIOFILM REACTORS

    Directory of Open Access Journals (Sweden)

    B. Ayati, H. Ganjidoust, M. Mir Fattah

    2007-04-01

    Full Text Available For biological treatment of water, there are many different biofilm systems in use. Examples of them are trickling filters, rotating biological contactors, fixed media submerged biofilters, granular media biofilters and fluidized bed reactors. They all have their advantages and disadvantages. Hence, the Moving Bed Biofilm Reactor process was developed in Norway in the late 1980s and early 1990s to adopt the best features of the activated sludge process as well as those of the biofilter processes, without including the worst. Two cylindrical moving bed biofilm reactors were used in this study working in upflow stream conditions. Experiments have been done in aerobic batch flow regime. Laboratory experiments were conducted at room temperature (23–28C and synthetic wastewater comprising a composition of phenol and hydroquinone in each reactor as the main organic constituents, plus balanced nutrients and alkalinity were used to feed the reactor. The ratio of influent to effluent COD was determined at different retention times. The results indicated that the removal efficiency of each selected compound is affected by the detention time. At low phenol and hydroquinone concentration (from 700 to 1000 mg/L maximum removal efficiency (over 80 % was obtained. By further increasing in COD loading rate up to 3000 mg/L, a decrease in COD removal rate was occurred. In the reactor containing pyrogallol in COD of 1500 mg/L, the removal rate decreased to 10 percent because of its toxicity for microorganisms.

  10. Fluidized Bed Reactor as Solid State Fermenter

    Directory of Open Access Journals (Sweden)

    Krishnaiah, K.

    2005-01-01

    Full Text Available Various reactors such as tray, packed bed, rotating drum can be used for solid-state fermentation. In this paper the possibility of fluidized bed reactor as solid-state fermenter is considered. The design parameters, which affect the performances are identified and discussed. This information, in general can be used in the design and the development of an efficient fluidized bed solid-state fermenter. However, the objective here is to develop fluidized bed solid-state fermenter for palm kernel cake conversion into enriched animal and poultry feed.

  11. Comparison of biomass from integrated fixed-film activated sludge (IFAS), moving bed biofilm reactor (MBBR) and membrane bioreactor (MBR) treating recalcitrant organics: Importance of attached biomass.

    Science.gov (United States)

    Huang, Chunkai; Shi, Yijing; Xue, Jinkai; Zhang, Yanyan; Gamal El-Din, Mohamed; Liu, Yang

    2017-03-15

    This study compared microbial characteristics and oil sands process-affected water (OSPW) treatment performance of five types of microbial biomass (MBBR-biofilm, IFAS-biofilm, IFAS-floc, MBR-aerobic-floc, and MBR-anoxic-floc) cultivated from three types of bioreactors (MBBR, IFAS, and MBR) in batch experiments. Chemical oxygen demand (COD), ammonium, acid extractable fraction (AEF), and naphthenic acids (NAs) removals efficiencies were distinctly different between suspended and attached bacterial aggregates and between aerobic and anoxic suspended flocs. MBR-aerobic-floc and MBR-anoxic-floc demonstrated COD removal efficiencies higher than microbial aggregates obtained from MBBR and IFAS, MBBR and IFAS biofilm had higher AEF removal efficiencies than those obtained using flocs. MBBR-biofilm demonstrated the most efficient NAs removal from OSPW. NAs degradation efficiency was highly dependent on the carbon number and NA cyclization number according to UPLC/HRMS analysis. Mono- and di-oxidized NAs were the dominant oxy-NA species in OSPW samples. Microbial analysis with quantitative polymerase chain reaction (q-PCR) indicated that the bacterial 16S rRNA gene abundance was significantly higher in the batch bioreactors with suspended flocs than in those with biofilm, the NSR gene abundance in the MBR-anoxic bioreactor was significantly lower than that in aerobic batch bioreactors, and denitrifiers were more abundant in the suspended phase of the activated sludge flocs. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Modelling of sludge blanket height and flow pattern in UASB reactors treating municipal wastewater

    International Nuclear Information System (INIS)

    Singh, K.S.; Viraraghavan, T.

    2002-01-01

    Two upflow anaerobic sludge blanket (UASB) reactors were started-up and operated for approximately 900 days to examine the feasibility of treating municipal wastewater under low temperature conditions. A modified solid distribution model was formulated by incorporating the variation of biogas production rate with a change in temperature. This model was used to optimize the sludge blanket height of UASB reactors for an effective operation of gas-liquid-solid (GLS) separation device. This model was found to simulate well the solid distribution as confirmed experimental observation of solid profile along the height of the reactor. Mathematical analysis of tracer curves indicated the presence of a mixed type of flow pattern in the sludge-bed zone of the reactor. It was found that the dead-zone and by-pass flow fraction were impacted by the change in operating temperatures. (author)

  13. Gaseous emissions from sewage sludge combustion in a moving bed combustor.

    Science.gov (United States)

    Batistella, Luciane; Silva, Valdemar; Suzin, Renato C; Virmond, Elaine; Althoff, Chrtistine A; Moreira, Regina F P M; José, Humberto J

    2015-12-01

    Substantial increase in sewage sludge generation in recent years requires suitable destination for this residue. This study evaluated the gaseous emissions generated during combustion of an aerobic sewage sludge in a pilot scale moving bed reactor. To utilize the heat generated during combustion, the exhaust gas was applied to the raw sludge drying process. The gaseous emissions were analyzed both after the combustion and drying steps. The results of the sewage sludge characterization showed the energy potential of this residue (LHV equal to 14.5 MJ kg(-1), db) and low concentration of metals, polycyclic aromatic hydrocarbons (PAH), polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF). The concentration of CO, NOx, BTEX (benzene, toluene, ethylbenzene and xylenes) emitted from the sludge combustion process were lower than the legal limits. The overall sludge combustion and drying process showed low emissions of PCDD/PCDF (0.42 ng I-TEQ N m(-3)). BTEX and PAH emissions were not detected. Even with the high nitrogen concentration in the raw feed (5.88% db), the sludge combustion process presented NOx emissions below the legal limit, which results from the combination of appropriate feed rate (A/F ratio), excess air, and mainly the low temperature kept inside the combustion chamber. It was found that the level of CO emissions from the overall sludge process depends on the dryer operating conditions, such as the oxygen content and the drying temperature, which have to be controlled throughout the process in order to achieve low CO levels. The aerobic sewage sludge combustion process generated high SO2 concentration due to the high sulfur content (0.67 wt%, db) and low calcium concentration (22.99 g kg(-1)) found in the sludge. The high concentration of SO2 in the flue gas (4776.77 mg N m(-3)) is the main factor inhibiting PCDD/PCDF formation. Further changes are needed in the pilot plant scheme to reduce SO2 and particulate matter emissions

  14. Optimization of up-flow anaerobic sludge blanket reactor for ...

    African Journals Online (AJOL)

    Optimization of up-flow anaerobic sludge blanket reactor for treatment of composite ... AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search ... Granules grown in the bottom part of UASB reactor were more compact and tense ...

  15. 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).

  16. 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).

  17. Prevention of Bed Agglomeration Problems in a Fluidized Bed Boiler by Finding the Trigging Value of Sewage Sludge Dosage Added to Combustion of Biofuels

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Kajsa; Gervind, Pernilla

    2009-07-01

    Agglomeration of bed sand is a common problem during combustion of biofuels with high ash content in fluidized bed boilers. Former studies have shown that co-combustion of biofuels with sewage sludge increases the agglomeration temperature. Sewage sludge has a low heating value and high ash content. It would therefore be better to use sludge as an additive to the combustion than as a co-combusted biofuel. In this study the trigging value of sludge addition to the combustion of some biofuel was investigated. The effect of adding sludge with different precipitation chemicals, iron sulphate and aluminium sulphate, was investigated. The biofuels used for the experiments were bark, refused derived fuel (RDF) and a mixture of wood and straw, 75/25 % on energy basis. All experiments were carried out in a laboratory scale fluidized bed reactor. Analyses of chemical composition of bed sand and SEM/EDX analyses were performed after the combustion. Eventually agglomeration tests were performed in order to find the agglomeration temperature of the samples. Some of the samples sintered during the combustion and were not tested for the agglomeration temperature. SEM/EDX showed that all samples of bed sand contained sand particles with more or less coatings. In some cases the coatings seemed to consist of one dense inner layer and one more porous outer layer. From SEM/EDX and chemical composition analyses it was found that the total amount of phosphorous in the bed sand samples was increased with an increased addition of sludge in all experiments. The concentration of phosphorous was especially higher in the outer layers/coatings. It was also found that elements from the sludge seem to get caught by a sticky layer at the bed sand surface and form a non-sticky or less sticky layer that prevents agglomeration. The total amount of aluminium was increased with an increased addition of sludge for the wood/straw samples, while it increased with an increased amount of combusted fuel for

  18. Core homogenization method for pebble bed reactors

    International Nuclear Information System (INIS)

    Kulik, V.; Sanchez, R.

    2005-01-01

    This work presents a core homogenization scheme for treating a stochastic pebble bed loading in pebble bed reactors. The reactor core is decomposed into macro-domains that contain several pebble types characterized by different degrees of burnup. A stochastic description is introduced to account for pebble-to-pebble and pebble-to-helium interactions within a macro-domain as well as for interactions between macro-domains. Performance of the proposed method is tested for the PROTEUS and ASTRA critical reactor facilities. Numerical simulations accomplished with the APOLLO2 transport lattice code show good agreement with the experimental data for the PROTEUS reactor facility and with the TRIPOLI4 Monte Carlo simulations for the ASTRA reactor configuration. The difference between the proposed method and the traditional volume-averaged homogenization technique is negligible while only one type of fuel pebbles present in the system, but it grows rapidly with the level of pebble heterogeneity. (authors)

  19. Transformation products of clindamycin in moving bed biofilm reactor (MBBR)

    DEFF Research Database (Denmark)

    Ooi, Gordon Tze Hoong; Escola Casas, Monica; Andersen, Henrik Rasmus

    2017-01-01

    Clindamycin is widely prescribed for its ability to treat a number of common bacterial infections. Thus, clindamycin enters wastewater via human excretion or disposal of unused medication and widespread detection of pharmaceuticals in rivers proves the insufficiency of conventional wastewater...... treatment plants in removing clindamycin. Recently, it has been discovered that attached biofilm reactors, e.g., moving bed biofilm reactors (MBBRs) obtain a higher removal of pharmaceuticals than conventional sludge wastewater treatment plants. Therefore, this study investigated the capability of MBBRs...... process converts clindamycin into the, possibly persistent, products clindamycin sulfoxide and N-desmethyl clindamycin as well as 3 other mono-oxygenated products. Subsequently, the removal kinetics of clindamycin and the formation of the two identified products were investigated in batch experiments...

  20. ADM1 applications for a hybrid up-flow anaerobic sludge-filter bed reactor performance and for a batch thermophilic anaerobic digestion of thermally pretreated waste activated sludge

    Directory of Open Access Journals (Sweden)

    lván Ramirez

    2012-01-01

    Full Text Available Los procesos de la digestión anaerobia comprenden una red completa de reacciones bioquimicas y fisicoquímicas, secuenciales y paralelas. Los digestores anaerobios a menudo exhiben importantes problemas de estabilidad que sólo pueden ser evitados a través de apropiadas estrategias de control. Tales estrategias requieren, en general, para su implementación, del desarrollo de modelos matemáticos cuya finalidad es el de permitirnos mejor comprensión y optimización de los procesos de la digestión anaerobia, describiendo estas reacciones de una manera estructurada. Este trabajo revisa el modelo ADMI de la IWAy discute dos aplicaciones del modelo: la digestión anaerobia de las aguas residuales vinazas de las destilerias de vino corno sustrato en un reactor hibrido (UASFB y la digestión anaerobia termófila en batch de lodos activados con pre-tratamiento térmico. Las predicciones del modelo, usando los parámetros establecidos en este estudio, concuerdan bien con los resultados de las mediciones en las diferentes condiciones ensayadas. Los modelos resultantes explicaron la evolución dinámica de las principales variables, tanto en la fase liquida corno la fase gaseosa.

  1. 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

  2. A new fluidized bed nuclear reactor

    International Nuclear Information System (INIS)

    Sefidvash, F.

    1986-01-01

    A new nuclear reactor design based on the fluidized bed concept is proposed. A current design utilizes spherical fuel of slightly enriched Zircaloy-clad uranium dioxide fluidized by light water under pressure. The reactor is modular in system; therefore, any size reactor can be constructed from the basic standard modul. The reactor physics calculations show that reactivity increases with porosity to a maximum value and thereafter decreases. This produces inherent safety and eliminates the need for control rods and burnable poisons. The heat transfer calculations show that the maximum power extracted from the reactor core is not limited to the material temperature limits but to the maximum mass flow of coolant, which corresponds to the desired operating porosity. Design simplicity and inherent safety make it an attractive small reactor design. (Author) [pt

  3. 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.

  4. 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

  5. Design parameters for sludge reduction in an aquatic worm reactor

    NARCIS (Netherlands)

    Hendrickx, T.L.G.; Temmink, B.G.; Elissen, H.J.H.; Buisman, C.J.N.

    2010-01-01

    Reduction and compaction of biological waste sludge from waste water treatment plants (WWTPs) can be achieved with the aquatic worm Lumbriculus variegatus. In our reactor concept for a worm reactor, the worms are immobilised in a carrier material. The size of a worm reactor will therefore mainly be

  6. Particle bed reactor nuclear rocket concept

    International Nuclear Information System (INIS)

    Ludewig, H.

    1991-01-01

    The particle bed reactor nuclear rocket concept consists of fuel particles (in this case (U,Zr)C with an outer coat of zirconium carbide). These particles are packed in an annular bed surrounded by two frits (porous tubes) forming a fuel element; the outer one being a cold frit, the inner one being a hot frit. The fuel element are cooled by hydrogen passing in through the moderator. These elements are assembled in a reactor assembly in a hexagonal pattern. The reactor can be either reflected or not, depending on the design, and either 19 or 37 elements, are used. Propellant enters in the top, passes through the moderator fuel element and out through the nozzle. Beryllium used for the moderator in this particular design to withstand the high radiation exposure implied by the long run times

  7. 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...

  8. 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)

  9. Pebble Bed Reactor Dust Production Model

    Energy Technology Data Exchange (ETDEWEB)

    Abderrafi M. Ougouag; Joshua J. Cogliati

    2008-09-01

    The operation of pebble bed reactors, including fuel circulation, can generate graphite dust, which in turn could be a concern for internal components; and to the near field in the remote event of a break in the coolant circuits. The design of the reactor system must, therefore, take the dust into account and the operation must include contingencies for dust removal and for mitigation of potential releases. Such planning requires a proper assessment of the dust inventory. This paper presents a predictive model of dust generation in an operating pebble bed with recirculating fuel. In this preliminary work the production model is based on the use of the assumption of proportionality between the dust production and the normal force and distance traveled. The model developed in this work uses the slip distances and the inter-pebble forces computed by the authors’ PEBBLES. The code, based on the discrete element method, simulates the relevant static and kinetic friction interactions between the pebbles as well as the recirculation of the pebbles through the reactor vessel. The interaction between pebbles and walls of the reactor vat is treated using the same approach. The amount of dust produced is proportional to the wear coefficient for adhesive wear (taken from literature) and to the slip volume, the product of the contact area and the slip distance. The paper will compare the predicted volume with the measured production rates. The simulation tallies the dust production based on the location of creation. Two peak production zones from intra pebble forces are predicted within the bed. The first zone is located near the pebble inlet chute due to the speed of the dropping pebbles. The second peak zone occurs lower in the reactor with increased pebble contact force due to the weight of supported pebbles. This paper presents the first use of a Discrete Element Method simulation of pebble bed dust production.

  10. Pebble Bed Reactor Dust Production Model

    International Nuclear Information System (INIS)

    Abderrafi M. Ougouag; Joshua J. Cogliati

    2008-01-01

    The operation of pebble bed reactors, including fuel circulation, can generate graphite dust, which in turn could be a concern for internal components; and to the near field in the remote event of a break in the coolant circuits. The design of the reactor system must, therefore, take the dust into account and the operation must include contingencies for dust removal and for mitigation of potential releases. Such planning requires a proper assessment of the dust inventory. This paper presents a predictive model of dust generation in an operating pebble bed with recirculating fuel. In this preliminary work the production model is based on the use of the assumption of proportionality between the dust production and the normal force and distance traveled. The model developed in this work uses the slip distances and the inter-pebble forces computed by the authors PEBBLES. The code, based on the discrete element method, simulates the relevant static and kinetic friction interactions between the pebbles as well as the recirculation of the pebbles through the reactor vessel. The interaction between pebbles and walls of the reactor vat is treated using the same approach. The amount of dust produced is proportional to the wear coefficient for adhesive wear (taken from literature) and to the slip volume, the product of the contact area and the slip distance. The paper will compare the predicted volume with the measured production rates. The simulation tallies the dust production based on the location of creation. Two peak production zones from intra pebble forces are predicted within the bed. The first zone is located near the pebble inlet chute due to the speed of the dropping pebbles. The second peak zone occurs lower in the reactor with increased pebble contact force due to the weight of supported pebbles. This paper presents the first use of a Discrete Element Method simulation of pebble bed dust production

  11. Small propulsion reactor design based on particle bed reactor concept

    International Nuclear Information System (INIS)

    Ludewig, H.; Lazareth, O.; Mughabghab, S.; Perkins, K.; Powell, J.R.

    1989-01-01

    In this paper Particle Bed Reactor (PBR) designs are discussed which use 233 U and /sup 242m/Am as fissile materials. A constant total power of 100MW is assumed for all reactors in this study. Three broad aspects of these reactors is discussed. First, possible reactor designs are developed, second physics calculations are outlined and discussed and third mass estimates of the various candidates reactors are made. It is concluded that reactors with a specific mass of 1 kg/MW can be envisioned of 233 U is used and approximately a quarter of this value can be achieved if /sup 242m/Am is used. If this power level is increased by increasing the power density lower specific mass values are achievable. The limit will be determined by uncertainties in the thermal-hydraulic analysis. 5 refs., 5 figs., 6 tabs

  12. Hydrodynamics of multi-phase packed bed micro-reactors

    NARCIS (Netherlands)

    Márquez Luzardo, N.M.

    2010-01-01

    Why to use packed bed micro-reactors for catalyst testing? Miniaturized packed bed reactors have a large surface-to-volume ratio at the reactor and particle level that favors the heat- and mass-transfer processes at all scales (intra-particle, inter-phase and inter-particle or reactor level). If the

  13. 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.

  14. Electrodialytic treatment for metal removal from sewage sludge ash from fluidized bed combustion

    DEFF Research Database (Denmark)

    Pazos, Marta; Kirkelund, Gunvor Marie; Ottosen, Lisbeth M.

    2010-01-01

    Sewage sludge contains several potentially hazardous compounds such as heavy metals, PCBs, PAHs, etc. However, elements with high agricultural value (P, K or Ca) are also present. During the last years, the fluidized bed sludge combustor (FBSC) is considered an effective and novel alternative to ...

  15. Mathematical modelling of fluidized bed reactors

    Energy Technology Data Exchange (ETDEWEB)

    Werther, J [BASF A.G., Ludwigshafen am Rhein (Germany, F.R.)

    1978-11-01

    Among the many fluidized bed models to be found in the literature, the two-phase model originally proposed by May has proved most suitable for accomodation of recent advances in flow mechanics: this model resolves the gas/solids fluidized bed into a bubble phase and a suspension phase surrounding the bubbles. Its limitation to slow reactions is a disadvantage. On the basis of the analogy between fluidized beds and gas/liquid systems, a general two-phase model that is valid for fast reactions has therefore been developed and its validity is confirmed by comparison with the experimental results obtained by others. The model describes mass transfer across the phase interface with the aid of the film theory known from gas/liquid reactor technology, and the reaction occurring in the suspension phase as a pseudo-homogeneous reaction. Since the dependence of the performance of fluidized bed reactors upon geometry is accounted for, the model can also be used for scale-up calculations. Its use is illustrated with the aid of design diagrams.

  16. Method and apparatus for a combination moving bed thermal treatment reactor and moving bed filter

    Energy Technology Data Exchange (ETDEWEB)

    Badger, Phillip C.; Dunn, Jr., Kenneth J.

    2015-09-01

    A moving bed gasification/thermal treatment reactor includes a geometry in which moving bed reactor particles serve as both a moving bed filter and a heat carrier to provide thermal energy for thermal treatment reactions, such that the moving bed filter and the heat carrier are one and the same to remove solid particulates or droplets generated by thermal treatment processes or injected into the moving bed filter from other sources.

  17. The Pebble Bed Modular Reactor: An obituary

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Steve, E-mail: stephen.thomas@gre.ac.u [Public Services International Research Unit (PSIRU), Business School, University of Greenwich, 30 Park Row, London SE10 9LS (United Kingdom)

    2011-05-15

    The High Temperature Gas-cooled Reactor (HTGR) has exerted a peculiar attraction over nuclear engineers. Despite many unsuccessful attempts over half a century to develop it as a commercial power reactor, there is still a strong belief amongst many nuclear advocates that a highly successful HTGR technology will emerge. The most recent attempt to commercialize an HTGR design, the Pebble Bed Modular Reactor (PBMR), was abandoned in 2010 after 12 years of effort and the expenditure of a large amount of South African public money. This article reviews this latest attempt to commercialize an HTGR design and attempts to identify which issues have led to its failure and what lessons can be learnt from this experience. It concludes that any further attempts to develop HTGRs using Pebble Bed technology should only be undertaken if there is a clear understanding of why earlier attempts have failed and a high level of confidence that earlier problems have been overcome. It argues that the PBMR project has exposed serious weaknesses in accountability mechanisms for the expenditure of South African public money. - Research highlights: {yields} In this study we examine the reasons behind the failure of the South African PBMR programme. {yields} The study reviews the technical issues that have arisen and lessons for future reactor developments. {yields} The study also identifies weaknesses in the accountability mechanisms for public spending.

  18. Integrated drying and incineration of wet sewage sludge in combined bubbling and circulating fluidized bed units.

    Science.gov (United States)

    Li, Shiyuan; Li, Yunyu; Lu, Qinggang; Zhu, Jianguo; Yao, Yao; Bao, Shaolin

    2014-12-01

    An original integrated drying and incineration technique is proposed to dispose of sewage sludge with moisture content of about 80% in a circulating fluidized bed. This system combines a bubbling fluidized bed dryer with a circulating fluidized bed incinerator. After drying, sewage sludge with moisture less than 20% is transported directly and continuously from the fluidized bed dryer into a circulating fluidized bed incinerator. Pilot plant results showed that integrated drying and incineration is feasible in a unique single system. A 100 t/d Sewage Sludge Incineration Demonstration Project was constructed at the Qige sewage treatment plant in Hangzhou City in China. The operational performance showed that the main operation results conformed to the design values, from which it can be concluded that the scale-up of this technique is deemed both feasible and successful. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. The ESKOM pebble bed modular reactor

    International Nuclear Information System (INIS)

    Gittus, J.H.

    1999-01-01

    An audit has been made of the design, construction, safety, economics and marketability of the ESKOM pebble bed modular reactor (PBMR). In this paper that audit is briefly summarized. The principal conclusions of the audit are as follows. The design is sound. It is a logical development of the designs proposed for other, modern, high-temperature gas-cooled reactors. More than 80% of the cost of constructing and commissioning a series of PBMRs would be spent in South Africa. The PBMR is much safer than existing nuclear power reactors and for many practical purposes it may be treated as a conventional chemical plant. The PBMR is economically competitive with thermal power stations. There is a substantial global market for the PBMR. (author)

  20. Thermoradiation treatment of sewage sludge using reactor waste fission products

    International Nuclear Information System (INIS)

    Reynolds, M.C.; Hagengruber, R.L.; Zuppero, A.C.

    1974-06-01

    The hazards to public health associated with the application of municipal sewage sludge to land usage are reviewed to establish the need for disinfection of sludge prior to its distribution as a fertilizer, especially in the production of food and fodder. The use of ionizing radiation in conjunction with mild heating is shown to be an effective disinfection treatment and an economical one when reactor waste fission products are utilized. A program for researching and experimental demonstration of the process on sludges is also outlined

  1. Life cycle assessment comparing the treatment of surplus activated sludge in a sludge treatment reed bed system with mechanical treatment on centrifuge

    DEFF Research Database (Denmark)

    Larsen, Julie Dam; Hoeve, Marieke ten; Nielsen, Steen

    2018-01-01

    or the centrifuge and terminated by land application of the final sludge product. The environmental impacts caused by the sludge treatment reed bed system strategy were comparable to or lower than those caused by the mechanical sludge treatment method. The impacts on climate change were the same for all...

  2. Biological sulphate reduction with primary sewage sludge in an ...

    African Journals Online (AJOL)

    The success of the UASB reactor depends largely on the settling properties and stability of the sludge bed which comprises the anaerobic active biomass. The solid-liquid separation behaviour of the sludge bed in 2 UASB reactors (R1 at 35oC and R2 at 20oC) fed with primary sewage sludge and sulphate was investigated ...

  3. Efficiency of a pilot-scale integrated sludge thickening and digestion reactor in treating low-organic excess sludge.

    Science.gov (United States)

    He, Qiang; Li, Jiang; Liu, Hongxia; Tang, Chuandong; de Koning, Jaap; Spanjers, Henri

    2012-06-01

    The sludge production from medium- and small-scale wastewater treatment plants in the Three Gorges Reservoir Region is low and non-stable; especially, the organic content in this sludge is low (near 40% of VS/TS). An integrated thickening and digestion (ISTD) reactor was developed to treat this low-organic excess sludge. After a flow test and start-up experiment of the reactor, a running experiment was used to investigate the excess sludge treatment efficiency under five different excess sludge inflows: 200, 300, 400, 500 and 400 L/d (a mixture of excess sludge and primary sludge in a volume ratio of 9:1). This trial was carried out in the wastewater treatment plant in Chongqing, which covers 80% of the Three Gorges Reservoir Region, under the following conditions: (1) sludge was heated to 38-40 degrees C using an electrical heater to maintain anaerobic mesophilic digestion; (2) the biogas produced was recirculated to mix raw sludge with anaerobic sludge in the reactor under the flow rate of 12.5 L/min. There were three main results. Firstly, the flow pattern of the inner reactor was almost completely mixed under the air flow of 12.0 L/min using clear water. Secondly, under all the different sludge inflows, the water content in the outlet sludge was below 93%. Thirdly, the organic content in the outlet sludge was decreased from 37% to 30% and from 24% to 20%, whose removal ratio was in relation to the organic content of the inlet sludge. The excess sludge treatment capacity of the ISTD reactor was according to the organic content in the excess sludge.

  4. Nitrification of industrial and domestic saline wastewaters in moving bed biofilm reactor and sequencing batch reactor

    International Nuclear Information System (INIS)

    Bassin, Joao P.; Dezotti, Marcia; Sant'Anna, Geraldo L.

    2011-01-01

    Nitrification of saline wastewaters was investigated in bench-scale moving-bed biofilm reactors (MBBR). Wastewater from a chemical industry and domestic sewage, both treated by the activated sludge process, were fed to moving-bed reactors. The industrial wastewater contained 8000 mg Cl - /L and the salinity of the treated sewage was gradually increased until that level. Residual substances present in the treated industrial wastewater had a strong inhibitory effect on the nitrification process. Assays to determine inhibitory effects were performed with the industrial wastewater, which was submitted to ozonation and carbon adsorption pretreatments. The latter treatment was effective for dissolved organic carbon (DOC) removal and improved nitrification efficiency. Nitrification percentage of the treated domestic sewage was higher than 90% for all tested chloride concentrations up to 8000 mg/L. Results obtained in a sequencing batch reactor (SBR) were consistent with those attained in the MBBR systems, allowing tertiary nitrification and providing adequate conditions for adaptation of nitrifying microorganisms even under stressing and inhibitory conditions.

  5. A Numerical Model for Trickle Bed Reactors

    Science.gov (United States)

    Propp, Richard M.; Colella, Phillip; Crutchfield, William Y.; Day, Marcus S.

    2000-12-01

    Trickle bed reactors are governed by equations of flow in porous media such as Darcy's law and the conservation of mass. Our numerical method for solving these equations is based on a total-velocity splitting, sequential formulation which leads to an implicit pressure equation and a semi-implicit mass conservation equation. We use high-resolution finite-difference methods to discretize these equations. Our solution scheme extends previous work in modeling porous media flows in two ways. First, we incorporate physical effects due to capillary pressure, a nonlinear inlet boundary condition, spatial porosity variations, and inertial effects on phase mobilities. In particular, capillary forces introduce a parabolic component into the recast evolution equation, and the inertial effects give rise to hyperbolic nonconvexity. Second, we introduce a modification of the slope-limiting algorithm to prevent our numerical method from producing spurious shocks. We present a numerical algorithm for accommodating these difficulties, show the algorithm is second-order accurate, and demonstrate its performance on a number of simplified problems relevant to trickle bed reactor modeling.

  6. Combustion in fluidized bed reactors; Verbrennung in Wirbelschichtreaktoren

    Energy Technology Data Exchange (ETDEWEB)

    Thome-Kozmiensky, Karl J. [vivis CONSULT GmbH, Nietwerder (Germany)

    2013-03-01

    Since the first application for the coal gasification, the fluidized bed technology has passed an impressive development. Nowadays, the fluidized bed technology is utilized at chemical processes, drying and cooling, gasification, combustion and purification of exhaust gas. In the firing technology, the fluidized technology initially has been proved in the combustion of very high ash coal and sewage sludge. Recently, the fluidized bed technology also is applied in the drying of sewage sludge, combustion of domestic waste - as in Japan and Sweden - as well as in the gasification and combustion of substitute fuels, biomass - wood pellets, wood chips, straw, cocoa shells and so forth - and residues from the paper manufacturing - such as in Germany and Austria. Under this aspect, the author of the contribution under consideration reports on the combustion of sewage sludge, substitute fuels and biomass.

  7. Wastewater treatment in a hybrid activated sludge baffled reactor

    Energy Technology Data Exchange (ETDEWEB)

    Tizghadam, Mostafa [Laboratoire des Sciences de l' Eau et de l' Environnement, Universite de Limoges, ENSIL, Parc ESTER, 16 Rue Atlantis, F-87068 Limoges Cedex (France); Dagot, Christophe [Laboratoire des Sciences de l' Eau et de l' Environnement, Universite de Limoges, ENSIL, Parc ESTER, 16 Rue Atlantis, F-87068 Limoges Cedex (France)], E-mail: dagot@ensil.unilim.fr; Baudu, Michel [Laboratoire des Sciences de l' Eau et de l' Environnement, Universite de Limoges, ENSIL, Parc ESTER, 16 Rue Atlantis, F-87068 Limoges Cedex (France)

    2008-06-15

    A novel hybrid activated sludge baffled reactor (HASBR), which contained both suspended and attached-growth biomass perfect mixing cells in series, was developed by installing standing and hanging baffles and introducing plastic brushes into a conventional activated sludge (CAS) reactor. It was used for the treatment of domestic wastewater. The effects on the operational performance of developing the suspended and attached-growth biomass and reactor configuration were investigated. The change of the flow regime from complete-mix to plug-flow, and the addition of plastic brushes as a support for biofilm, resulted in considerable improvements in the COD, nitrogen removal efficiency of domestic wastewater and sludge settling properties. In steady state, approximately 98 {+-} 2% of the total COD and 98 {+-} 2% of the ammonia of the influent were removed in the HASBR, when the influent wastewater concentration was 593 {+-} 11 mg COD/L and 43 {+-} 5 mg N/L, respectively, at a HRT of 10 h. These results were 93 {+-} 3 and 6 {+-} 3% for the CAS reactor, respectively. Approximately 90 {+-} 7% of the total COD was removed in the HASBR, when the influent wastewater concentration was 654 {+-} 16 mg COD/L at a 3 h HRT, and in the organic loading rate (OLR) of 5.36 kg COD m{sup -3} day{sup -1}. The result for the CAS reactor was 60 {+-} 3%. Existing CAS plants can be upgraded by changing the reactor configuration and introducing biofilm support media into the aeration tank.

  8. Devolatilization of oil sludge in a lab-scale bubbling fluidized bed.

    Science.gov (United States)

    Liu, Jianguo; Jiang, Xiumin; Han, Xiangxin

    2011-01-30

    Devolatilization of oil sludge pellets was investigated in nitrogen and air atmosphere in a lab-scale bubbling fluidized bed (BFB). Devolatilization times were measured by the degree of completion of the evolution of the volatiles for individual oil sludge pellets in the 5-15 mm diameter range. The influences of pellet size, bed temperature and superficial fluidization velocity on devolatilization time were evaluated. The variation of devolatilization time with particle diameter was expressed by the correlation, τ(d) = Ad(p)(N). The devolatilization time to pellet diameter curve shows nearly a linear increase in nitrogen, whereas an exponential increase in air. No noticeable effect of superficial fluidization velocity on devolatilization time in air atmosphere was observed. The behavior of the sludge pellets in the BFB was also focused during combustion experiments, primary fragmentation (a micro-explosive combustion phenomenon) was observed for bigger pellets (>10mm) at high bed temperatures (>700 °C), which occurred towards the end of combustion and remarkably reduce the devolatilization time of the oil sludge pellet. The size analysis of bed materials and fly ash showed that entire ash particle was entrained or elutriated out of the BFB furnace due to the fragile structure of oil sludge ash particles. Copyright © 2010 Elsevier B.V. All rights reserved.

  9. Evaluation of sludge from paper recycling as bedding material for broilers.

    Science.gov (United States)

    Villagrá, A; Olivas, I; Benitez, V; Lainez, M

    2011-05-01

    Several materials have been used as bedding substrates in broiler production. In this work, the sludge from paper recycling was tested for its potential use as litter material and was compared with wood shavings. Moisture content, apparent density, and water-holding capacity were measured and characterized in both materials. Later, 192 male broiler chickens were distributed among 16 experimental pens, 8 of which contained wood shavings as bedding material and 8 of which contained the sludge. Growth rate, consumption, tonic immobility, gait score, breast lesions, foot pad dermatitis, hock burn, tibial dyschondroplasia, and metatarsal thickness were determined in the birds. Although the moisture content of the sludge was high, it decreased strongly after 7 d of drying, reaching lower values than those of wood shavings. In general, few differences were found between the materials in terms of bird performance and welfare and only the incidence of hock burn was higher in the sludge than in the wood shavings. Although further research is needed, sludge from paper recycling is a possible alternative to traditional bedding materials because it achieves most of the requirements for broiler bedding materials and does not show negative effects on the birds.

  10. Hydrothermal Testing of K Basin Sludge and N Reactor Fuel at Sludge Treatment Project Operating Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Delegard, Calvin H.; Schmidt, Andrew J.; Thornton, Brenda M.

    2007-03-30

    The Sludge Treatment Project (STP), managed for the U. S. DOE by Fluor Hanford (FH), was created to design and operate a process to eliminate uranium metal from K Basin sludge prior to packaging for Waste Isolation Pilot Plant (WIPP). The STP process uses high temperature liquid water to accelerate the reaction, produce uranium dioxide from the uranium metal, and safely discharge the hydrogen. Under nominal process conditions, the sludge will be heated in pressurized water at 185°C for as long as 72 hours to assure the complete reaction (corrosion) of up to 0.25-inch diameter uranium metal pieces. Under contract to FH, the Pacific Northwest National Laboratory (PNNL) conducted bench-scale testing of the STP hydrothermal process in November and December 2006. Five tests (~50 ml each) were conducted in sealed, un-agitated reaction vessels under the hydrothermal conditions (e.g., 7 to 72 h at 185°C) of the STP corrosion process using radioactive sludge samples collected from the K East Basin and particles/coupons of N Reactor fuel also taken from the K Basins. The tests were designed to evaluate and understand the chemical changes that may be occurring and the effects that any changes would have on sludge rheological properties. The tests were not designed to evaluate engineering aspects of the process. The hydrothermal treatment affected the chemical and physical properties of the sludge. In each test, significant uranium compound phase changes were identified, resulting from dehydration and chemical reduction reactions. Physical properties of the sludge were significantly altered from their initial, as-settled sludge values, including, shear strength, settled density, weight percent water, and gas retention.

  11. Extracellular Polymers in Granular Sludge from Different Upflow Anaerobic Sludge Blanket (UASB) Reactors

    DEFF Research Database (Denmark)

    Schmidt, Jens Ejbye; Ahring, Birgitte Kiær

    1994-01-01

    lysis. ECP contents of 41 to 92 mg · g−1 volatile suspended solids of granules were found depending on the type of granular sludge examined. The content of polysaccharides, protein and lipids in the extracted ECP was quantified. Furthermore, the different methyl esters of the lipids were determined...... of an upflow anaerobic sludge blanket reactor from a sugar-containing waste-water to a synthetic waste-water containing acetate, propionate and butyrate resulted in a decrease in both the protein and polysaccharide content and an increase in the lipid content of the extracellular material. Furthermore...

  12. Evolution of Particle Bed Reactor Fuel

    Science.gov (United States)

    Jensen, Russell R.; Evans, Robert S.; Husser, Dewayne L.; Kerr, John M.

    1994-07-01

    To realize the potential performance advantages inherent in a particle bed reactor (PBR) for nuclear thermal propulsion (NTP) applications, high performance particle fuel is required. This fuel must operate safely and without failure at high temperature in high pressure, flowing hydrogen propellant. The mixed mean outlet temperature of the propellant is an important characteristic of PBR performance. This temperature is also a critical parameter for fuel particle design because it dictates the required maximum fuel operating temperature. In this paper, the evolution in PBR fuel form to achieve higher operating temperatures is discussed and the potential thermal performance of the different fuel types is evaluated. It is shown that the optimum fuel type for operation under the demanding conditions in a PBR is a coated, solid carbide particle.

  13. Fluidized-bed reactors processes and operating conditions

    CERN Document Server

    Yates, John G

    2016-01-01

    The fluidized-bed reactor is the centerpiece of industrial fluidization processes. This book focuses on the design and operation of fluidized beds in many different industrial processes, emphasizing the rationale for choosing fluidized beds for each particular process. The book starts with a brief history of fluidization from its inception in the 1940’s. The authors present both the fluid dynamics of gas-solid fluidized beds and the extensive experimental studies of operating systems and they set them in the context of operating processes that use fluid-bed reactors. Chemical engineering students and postdocs as well as practicing engineers will find great interest in this book.

  14. Theoretical comparison of packed bed and fluidized bed membrane reactors for methane reforming

    NARCIS (Netherlands)

    Gallucci, F.; van Sint Annaland, M.; Kuipers, J.A.M.

    2010-01-01

    In this theoretical work the performance of different membrane reactor concepts, both fluidized bed and packed bed membrane reactors, has been compared for ultra-pure hydrogen production via methane reforming. Using detailed theoretical models, the required membrane area to reach a given conversion

  15. Comparison of packed bed and fluidized bed membrane reactors for methane reforming

    NARCIS (Netherlands)

    Gallucci, F.; van Sint Annaland, M.; Kuipers, J.A.M.

    2009-01-01

    In this work the performance of different membrane reactor concepts, both fluidized bed and packed bed membrane reactors, have been compared for the reforming of methane for the production of ultra-pure hydrogen. Using detailed theoretical models, the required membrane area to reach a given

  16. Experimental studies on pulp and paper mill sludge ash behavior in fluidized bed combustors

    Energy Technology Data Exchange (ETDEWEB)

    Latva-Somppi, J. [VTT Chemical Technology, Espoo (Finland). Process Technology

    1998-11-01

    Ash formation during the fluidized bed combustion (FBC) of pulp and paper mill sludges has been experimentally studied on an industrial and bench scale. The methods included aerosol measurements, chemical and crystalline composition analyses, thermogravimetry and electron microscopy. Fly ash mass and number size distributions and elemental enrichment in submicron particles and bottom ash were measured. Fly ash, bottom ash and ash deposits were characterized and their formation mechanisms are discussed. During combustion the fine paper-making additives in sludge, clay minerals and calcite, sintered fanning porous agglomerates. The fly ash mass mean size was 7.5 - 15 lam and the supermicron particles included 93.6 - 97.3 % of the fly ash. Condensation of the volatilized inorganic species formed spherical submicron particles in the fly ash. Their mass concentration was almost negligible when co-firing paper mill sludges and wood. This suggests that the fraction of the volatilized inorganic species in the paper mill sludges was low. Results from pulp mill sludge and bark co-firing were different. A clear mass mode below 0.3 pm, presenting 2.2 - 5.0 weight-% of the fly ash was detected. The condensed species included K, Na, S and Cl. Their mass fraction was higher in the pulp mill sludge than in the paper mill sludge. Evidently this resulted in increased volatilization and formation of condensed particles. The following trace elements were enriched in the submicron ash during pulp mill sludge and wood co-firing: As, Cd, Rb and Pb. The main part of the volatile species was, however, captured in the bulk ash. Presumably, this was due to the high surface area concentration in the bulk ash. Sludge moisture was observed to reduce the inorganic species volatilization. Probably steam vaporization from the wet sludge through the burning layer decreased combustion temperatures on char surface and less char was produced. Hence, the volatilization of ash forming species was

  17. Fixed-bed Reactor Dynamics and Control - A Review

    DEFF Research Database (Denmark)

    Jørgensen, S. B.

    1986-01-01

    The industrial diversity of fixed bed reactors offers a challenging and relevant set of control problems. These intricate problems arise due to the rather complex dynamics of fixed bed reactors and to the complexity of actual reactor configurations. Many of these control problems are nonlinear...... and multi-variable. During the last decade fixed bed reactor control strategies have been proposed and investigated experimentally. This paper reviews research on these complex control problems with an emphasis upon solutions which have been demon-strated to work in the laboratory and hold promise...

  18. 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

  19. Temperature effects on biohydrogen production in a granular sludge bed induced by activated carbon carriers

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kuo-Shing [Department of Safety Health and Environmental Engineering, Chung tai Institute of Health Sciences and Technology, Taichung (China); Lin, Ping-Jei [Department of Chemical Engineering, Feng Chia University, Taichung (China); Chang, Jo-Shu [Department of Chemical Engineering, National Cheng Kung University, Tainan (China)

    2006-03-15

    Temperature effects on H{sub 2} production performance of a novel carrier-induced granular sludge bed (CIGSB) reactor were investigated. Using sucrose-based synthetic wastewater as the feed, the CIGSB system was operated at 30-45 {sup 0}C to identify the optimal working temperature. It was found that H{sub 2} production was the most efficient at 40 {sup 0}C, especially when it was operated at a low hydraulic retention time (HRT) of 0.5h. The overall maximal hydrogen production rate and yield were 7.66l/h/l and 3.88mol H{sub 2}/mol sucrose, respectively, both of them occurred at 40 {sup 0}C. The biomass content tended to decrease as the temperature was increased, suggesting that granular sludge formation may be inhibited at high temperatures. However, increasing temperature gave better specific H{sub 2} production rate, signifying that the average cellular activity for H{sub 2} production may be enhanced as the temperature was increased. The H{sub 2} yield and gas phase H{sub 2} content did not vary considerably regardless of changes in temperature and HRT. This reflects that the CIGSB was a relatively stable H{sub 2}-producing system. The major soluble products from hydrogen fermentation were butyric acid and acetic acid, accounting for 46+-3% and 28+-2% of total soluble microbial products (SMP), respectively. Thus, the dominant H{sub 2} producers in the mixed culture belonged to acidogenic bacteria that underwent butyrate-type fermentation. (author)

  20. An Evaluation of Reed Bed Technology to Dewater Army Wastewater Treatment Plant Sludge

    Science.gov (United States)

    1993-09-01

    speculated that the plants produced "root exudations" that were active against pathogens , and that the plants specifically showed an affinity for cadmium, zinc...mineralize and for pathogens to be destroyed. This downtime makes multiple beds necessary. The USEPA also reports that the major advantage of the reed...employee to regulate the sludge applications. This employee would also visually assess the beds for possible problems such as weed or insect ( aphid

  1. Study of reactivity of fluidized bed nuclear reactor

    International Nuclear Information System (INIS)

    Rammsy, J.E.M.

    1985-01-01

    The reactor physics calculations of a 19 module Fluidized Bed Nuclear Reactor using Leopard and Odog codes are performed. The behaviour of the reactor was studied by calculating the reactivity of the reactor as a function of the parameters governing the operational and accidental conditions of the reactor. The effects of temperature, pressure, and vapor generation in the core on the reactivity are calculated. Also the start up behaviour of the reactor is analyzed. For the purpose of the study of a prototype research reactor, the calculations on a one module reactor have been performed. (Author) [pt

  2. Efficiency of Worm Reactors in Reducing Sludge Volume in Activated Sludge Systems

    Directory of Open Access Journals (Sweden)

    Azam Naderi

    2017-01-01

    Full Text Available The activated sludge process is the most widely used on a global scale for the biological treatment of both domestic and industrial effluents. One problem associated with the process, however, is the high volume of sludge produced. Excess sludge treatment and disposal account for up to 60% of the total operating costs of urban wastewater treatment plants due to the stringent environmental regulations on excess sludge disposal. These strict requirements have encouraged a growing interest over the last few years in reducing sludge volumes produced at biological treatment plants and a number of physical, chemical, and mechanical methods have been accordingly developed for this purpose. The proposed methods are disadvantaged due to their rather high investment and operation costs. An alternative technology that avoids many of these limitations is the worm reactor. In this study, the characteristics of this technology are investigated while the related literature is reviewed to derive the optimal conditions for the operation of this process in different situations.

  3. 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.

  4. Fluidized bed nuclear reactor as a IV generation reactor

    International Nuclear Information System (INIS)

    Sefidvash, Farhang

    2002-01-01

    The object of this paper is to analyze the characteristics of the Fluidized Bed Nuclear Reactor (FBNR) concept under the light of the requirements set for the IV generation nuclear reactors. It is seen that FBNR generally meets the goals of providing sustainable energy generation that meets clean air objectives and promotes long-term availability of systems and effective fuel utilization for worldwide energy production; minimize and manage their nuclear waste and notably reduce the long term stewardship burden in the future, thereby improving protection for the public health and the environment; increase the assurance that it is a very unattractive and least desirable route for diversion or theft of weapons-usable materials; excel in safety and reliability; have a very low likelihood and degree of reactor core damage; eliminate the need for offsite emergency response; have a clear life-cycle cost advantage over other energy sources; have a level of financial risk comparable to other energy projects. The other advantages of the proposed design are being modular, low environmental impact, exclusion of severe accidents, short construction period, flexible adaptation to demand, excellent load following characteristics, and competitive economics. (author)

  5. Nitrogen mineralisation and greenhouse gas emission from the soil application of sludge from reed bed mineralisation systems

    DEFF Research Database (Denmark)

    Gómez-Muñoz, B; Larsen, Julie Dam; Bekiaris, G

    2017-01-01

    A sludge treatment reed bed system (STRB) is a technology used for dewatering and stabilising sewage sludge via assisted biological mineralisation, which creates a sludge residue suitable for use as fertiliser on agricultural land. We evaluated the effect of sludge residue storage time (stabilisa......A sludge treatment reed bed system (STRB) is a technology used for dewatering and stabilising sewage sludge via assisted biological mineralisation, which creates a sludge residue suitable for use as fertiliser on agricultural land. We evaluated the effect of sludge residue storage time...... (stabilisation time) for three STRBs on soil N mineralisation and CO2 and N2O emissions in soil. The experiment revealed that the N mineralisation rate and emissions of CO2 and N2O decreased as a function of treatment time in the STRBs. Mixed sludge residue (sludge residue subjected to different treatment times......) for the three STRBs resulted in N mineralisation rates similar to the sludge residue subjected to a shorter treatment time but lower N2O emissions similar to the values of the older sludge residue. This finding reveals that combining fresh and more stabilised sludge residue ensures high N availability...

  6. Behaviour of Inorganic Constituents of Municipal Sewage Sludge during Fluidized-Bed Combustion.

    Czech Academy of Sciences Publication Activity Database

    Hartman, Miloslav; Pohořelý, Michael; Trnka, Otakar

    2007-01-01

    Roč. 61, 3 (2007) , s. 181-185 ISSN 0366-6352 R&D Projects: GA AV ČR(CZ) IAA4072201 Institutional research plan: CEZ:AV0Z40720504 Keywords : sewage sludge * heavy metals * fluidized-bed combustion Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.367, year: 2007

  7. An energy amplifier fluidized bed nuclear reactor concept

    International Nuclear Information System (INIS)

    Sefidvash, F.; Seifritz, W.

    2001-01-01

    The concept of a fluidized bed nuclear reactor driven by an energy amplifier system is described. The reactor has promising characteristics of inherent safety and passive cooling. The reactor can easily operate with any desired spectrum in order to be a plutonium burner or have it operate with thorium fuel cycle. (orig.) [de

  8. Operational methods of the fluidized bed nuclear reactor

    International Nuclear Information System (INIS)

    Borges, V.; Sefidvash, F.

    1993-01-01

    The operational curve of reactivity as a function of porosity of the Fluidized Bed Nuclear Reactor is presented. The strategies for start-up, shut-down and maintaining the reactor critical during operation are described. The inherent safety of the reactor from neutronic point of view under steady state condition is demonstrated. (author)

  9. Co-Combustion of Municipal Sewage Sludge and Hard Coal on Fluidized Bed Boiler WF-6

    Directory of Open Access Journals (Sweden)

    Rajczyk Rafał

    2014-12-01

    Full Text Available According to data of the Central Statistical Office, the amount of sludge produced in municipal wastewater treatment plants in 2010 amounted to 526000 Mg d.m. The forecast of municipal sewage sludge amount in 2015 according to KPGO2014 will reach 642400 Mg d.m. and is expected to increase in subsequent years. Significant amounts of sludge will create problems due to its utilization. In order to solve this problem the use of thermal methods for sludge utilization is expected. According to the National Waste Management Plan nearly 30% of sewage sludge mass should be thermally utilized by 2022. The article presents the results of co-combustion of coal and municipal sewage sludge in a bubbling fluidized bed boiler made by SEFAKO and located in the Municipal Heating Company in Morag. Four tests of hard coal and sewage sludge co-combustion have been conducted. Boiler performance, emissions and ash quality were investigated.

  10. A Pebble Bed Reactor cross section methodology

    International Nuclear Information System (INIS)

    Hudson, Nathanael H.; Ougouag, Abderrafi M.; Rahnema, Farzad; Gougar, Hans

    2009-01-01

    A method is presented for the evaluation of microscopic cross sections for the Pebble Bed Reactor (PBR) neutron diffusion computational models during convergence to an equilibrium (asymptotic) fuel cycle. This method considers the isotopics within a core spectral zone and the leakages from such a zone as they arise during reactor operation. The randomness of the spatial distribution of fuel grains within the fuel pebbles and that of the fuel and moderator pebbles within the core, the double heterogeneity of the fuel, and the indeterminate burnup of the spectral zones all pose a unique challenge for the computation of the local microscopic cross sections. As prior knowledge of the equilibrium composition and leakage is not available, it is necessary to repeatedly re-compute the group constants with updated zone information. A method is presented to account for local spectral zone composition and leakage effects without resorting to frequent spectrum code calls. Fine group data are pre-computed for a range of isotopic states. Microscopic cross sections and zone nuclide number densities are used to construct fine group macroscopic cross sections, which, together with fission spectra, flux modulation factors, and zone buckling, are used in the solution of the slowing down balance to generate a new or updated spectrum. The microscopic cross-sections are then re-collapsed with the new spectrum for the local spectral zone. This technique is named the Spectral History Correction (SHC) method. It is found that this method accurately recalculates local broad group microscopic cross sections. Significant improvement in the core eigenvalue, flux, and power peaking factor is observed when the local cross sections are corrected for the effects of the spectral zone composition and leakage in two-dimensional PBR test problems.

  11. Wastewater treatment in a hybrid activated sludge baffled reactor

    International Nuclear Information System (INIS)

    Tizghadam, Mostafa; Dagot, Christophe; Baudu, Michel

    2008-01-01

    A novel hybrid activated sludge baffled reactor (HASBR), which contained both suspended and attached-growth biomass perfect mixing cells in series, was developed by installing standing and hanging baffles and introducing plastic brushes into a conventional activated sludge (CAS) reactor. It was used for the treatment of domestic wastewater. The effects on the operational performance of developing the suspended and attached-growth biomass and reactor configuration were investigated. The change of the flow regime from complete-mix to plug-flow, and the addition of plastic brushes as a support for biofilm, resulted in considerable improvements in the COD, nitrogen removal efficiency of domestic wastewater and sludge settling properties. In steady state, approximately 98 ± 2% of the total COD and 98 ± 2% of the ammonia of the influent were removed in the HASBR, when the influent wastewater concentration was 593 ± 11 mg COD/L and 43 ± 5 mg N/L, respectively, at a HRT of 10 h. These results were 93 ± 3 and 6 ± 3% for the CAS reactor, respectively. Approximately 90 ± 7% of the total COD was removed in the HASBR, when the influent wastewater concentration was 654 ± 16 mg COD/L at a 3 h HRT, and in the organic loading rate (OLR) of 5.36 kg COD m -3 day -1 . The result for the CAS reactor was 60 ± 3%. Existing CAS plants can be upgraded by changing the reactor configuration and introducing biofilm support media into the aeration tank

  12. Co-combustion of tannery sludge in a commercial circulating fluidized bed boiler.

    Science.gov (United States)

    Dong, Hao; Jiang, Xuguang; Lv, Guojun; Chi, Yong; Yan, Jianhua

    2015-12-01

    Co-combusting hazardous wastes in existing fluidized bed combustors is an alternative to hazardous waste treatment facilities, in shortage in China. Tannery sludge is a kind of hazardous waste, considered fit for co-combusting with coal in fluidized bedboilers. In this work, co-combustion tests of tannery sludge and bituminous coal were conducted in a power plant in Jiaxing, Zhejiang province. Before that, the combustion behavior of tannery sludge and bituminous were studied by thermogravimetric analysis. Tannery sludge presented higher reactivity than bituminous coal. During the co-combustion tests, the emissions of harmful gases were monitored. The results showed that the pollutant emissions met the Chinese standard except for NOx. The Concentrations of seven trace elements (As, Cr, Cd, Ni, Cu, Pb, Mn) in three exit ash flows (bottom ash in bed, fly ash in filter, and submicrometer aerosol in flue gas) were analyzed. The results of mono-combustion of bituminous coal were compared with those of co-combustion with tannery sludge. It was found that chromium enriched in fly ash. At last, the leachability of fly ash and bottom ash was analyzed. The results showed that most species were almost equal to or below the limits except for As in bottom ashes and Cr in the fly ash of co-combustion test. The concentrations of Cr in leachates of co-combustion ashes are markedly higher than that of coal mono-combustion ashes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. 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.).

  14. Use of nitrogen stable isotope analysis to understand char nitrogen evolution during the fluidized-bed co-combustion of coal and sewage sludge

    Energy Technology Data Exchange (ETDEWEB)

    Ana Arenillas; Roberto Garcia; Chenggong Sun; Colin E. Snape; Angel H. Moreno; Fernando Rubiera; Jose J. Pis [University of Nottingham, Nottingham (United Kingdom). Nottingham Fuel and Energy Centre, School of Chemical, Environmental and Mining Engineering

    2005-04-01

    NOx emissions from sewage sludge combustion are a concern, because of the usually high nitrogen content of this fuel. The interactions during co-combustion in a fluidized-bed reactor of sewage sludge and a bituminous coal were evaluated, in relation to the nitrogen evolution during the combustion process. The nitrogen stable isotope measurements provide novel results regarding the tracing of nitrogen during combustion. Our preliminary results show that the co-combustion chars retain more nitrogen than expected, with the additional nitrogen being mainly derived from the sludge. Additional measurements are planned on the resultant co-combustion gases, to aid source apportionment of the NOx arising from coal/sewage interactions. 14 refs., 3 figs., 2 tabs.

  15. [Rapid startup and nitrogen removal characteristic of anaerobic ammonium oxidation reactor in packed bed biofilm reactor with suspended carrier].

    Science.gov (United States)

    Chen, Sheng; Sun, De-zhi; Yu, Guang-lu

    2010-03-01

    Packed bed biofilm reactor with suspended carrier was used to cultivate ANAMMOX bacteria with sludge inoculums from WWTP secondary settler. The startup of ANAMMOX reactor was comparatively studied using high nitrogen loading method and low nitrogen loading method with aerobically biofilmed on the carrier, and the nitrogen removal characteristic was further investigated. The results showed that the reactor could be started up successfully within 90 days using low nitrogen loading method, the removal efficiencies of ammonium and nitrite were nearly 100% and the TN removal efficiencywas over 75% , however, the high nitrogen loading method was proved unsuccessfully for startup of ANAMMOX reactor probably because of the inhibition effect of high concentration of ammonium and nitrite. The pH value of effluent was slightly higher than the influent and the pH value can be used as an indicator for the process of ANAMMOX reaction. The packed bed ANAMMOX reactor with suspended carrier showed good characteristics of high nitrogen loading and high removal efficiency, 100% of removal efficiency could be achieved when the influent ammonium and nitrite concentration was lower than 800 mg/L.

  16. Immobilization patterns and dynamics of acetate-utilizing methanogens in sterile granular sludge from upflow anaerobic sludge blanket (UASB) reactors

    DEFF Research Database (Denmark)

    Schmidt, Jens Ejbye; Ahring, Birgitte Kiær

    1999-01-01

    Sterile granular sludge was inoculated with either Methanosarcina mazeii S-6, Methanosaeta concilii GP-6, or both species in acetate-fea upflow anaerobic sludge blanket (UASB) reactors to investigate the immobilization patterns and dynamics of aceticlastic methanogens in granular sludge. After......, but where the acetate concentration was low this strain was immobilized on support material as single cells or small clumps, The data clearly show that the two aceticlastic methanogens immobilize differently in UASB systems, depending on the conditions found throughout the UASB reactor....

  17. Immobilization patterns and dynamics of acetate-utilizing methanogens immobilized in sterile granular sludge in upflow anaerobic sludge blanket reactors

    DEFF Research Database (Denmark)

    Schmidt, Jens Ejbye; Ahring, Birgitte Kiær

    1999-01-01

    Sterile granular sludge was inoculated with either Methanosarcina mazeii S-6, Methanosaeta concilii GP-6, or both species in acetate-fea upflow anaerobic sludge blanket (UASB) reactors to investigate the immobilization patterns and dynamics of aceticlastic methanogens in granular sludge. After......, but where the acetate concentration was low this strain was immobilized on support material as single cells or small clumps, The data clearly show that the two aceticlastic methanogens immobilize differently in UASB systems, depending on the conditions found throughout the UASB reactor....

  18. 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...

  19. Las degradation in a fluidized bed reactor and phylogenetic characterization of the biofilm

    Directory of Open Access Journals (Sweden)

    L. L. Oliveira

    2013-09-01

    Full Text Available A fluidized bed reactor was used to study the degradation of the surfactant linear alkylbenzene sulfonate (LAS. The reactor was inoculated with anaerobic sludge and was fed with a synthetic substrate supplemented with LAS in increasing concentrations (8.2 to 45.8 mg l-1. The removal efficiency of 93% was obtained after 270 days of operation. Subsequently, 16S rRNA gene sequencing and phylogenetic analysis of the sample at the last stage of the reactor operation recovered 105 clones belonging to the domain Bacteria. These clones represented a variety of phyla with significant homology to Bacteroidetes (40%, Proteobacteria (42%, Verrucomicrobia (4%, Acidobacteria (3%, Firmicutes (2%, and Gemmatimonadetes (1%. A small fraction of the clones (8% was not related to any phylum. Such phyla variety indicated the role of microbial consortia in degrading the surfactant LAS.

  20. Sequential UASB and dual media packed-bed reactors for domestic wastewater treatment - experiment and simulation.

    Science.gov (United States)

    Rodríguez-Gómez, Raúl; Renman, Gunno

    2016-01-01

    A wastewater treatment system composed of an upflow anaerobic sludge blanket (UASB) reactor followed by a packed-bed reactor (PBR) filled with Sorbulite(®) and Polonite(®) filter material was tested in a laboratory bench-scale experiment. The system was operated for 50 weeks and achieved very efficient total phosphorus (P) removal (99%), 7-day biochemical oxygen demand removal (99%) and pathogenic bacteria reduction (99%). However, total nitrogen was only moderately reduced in the system (40%). A model focusing on simulation of organic material, solids and size of granules was then implemented and validated for the UASB reactor. Good agreement between the simulated and measured results demonstrated the capacity of the model to predict the behaviour of solids and chemical oxygen demand, which is critical for successful P removal and recovery in the PBR.

  1. Low temperature circulating fluidized bed gasification and co-gasification of municipal sewage sludge

    DEFF Research Database (Denmark)

    Thomsen, Tobias Pape; Hauggaard-Nielsen, Henrik; Gøbel, Benny

    2017-01-01

    to the mono-sludge ashes, thereby showing the best fertilizer qualities among all assessed materials. It was also found that bottom ashes from the char reactor contained even less heavy metals than cyclone ashes. It is concluded that LT-CFB gasification and co-gasification is a highly effective way to purify...

  2. Aerobic biodegradation of organotin compounds in activated sludge batch reactors

    Energy Technology Data Exchange (ETDEWEB)

    Stasinakis, Athanasios S. [Department of Environmental Studies, Water and Air Quality Laboratory, University of the Aegean, University Hill, Mytilene 81 100 (Greece)]. E-mail: astas@env.aegean.gr; Thomaidis, Nikolaos S. [Laboratory of Analytical Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Zografou, Athens 157 71 (Greece); Nikolaou, Anastasia [Department of Environmental Studies, Water and Air Quality Laboratory, University of the Aegean, University Hill, Mytilene 81 100 (Greece); Kantifes, Andreas [Department of Environmental Studies, Water and Air Quality Laboratory, University of the Aegean, University Hill, Mytilene 81 100 (Greece)

    2005-04-01

    The biodegradation behavior of four organotin (OT) compounds, namely tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT) and triphenyltin (TPhT), was studied in lab-scale activated sludge batch reactors. The activated sludge was spiked with the OT compounds at a level of 100 {mu}g l{sup -1} as Sn. Determination of the OT compounds by GC-FPD after ethylation in the dissolved and particulate phase revealed that 24 h after the start of the experiments, almost the total of OT compounds has been removed from the dissolved phase and is associated with the suspended solids. Calculation of mass balance in batch reactors showed that OT compounds biodegradation was performed via a sequential dealkylation process. Removals due to biodegradation were differentiated according to the parent compound. In experiments with non-acclimatized biomass, a percentage of 27.1, 8.3, 73.8 and 51.3 was still present as TBT, DBT, MBT and TPhT, respectively, at the end of the experiment (18th day). Half-lives (t{sub 1/2}) of 10.2 and 5.1 days were calculated for TBT and DBT, respectively, whereas apparent t{sub 1/2} values could not be determined for MBT and TPhT (t{sub 1/2} > 18 days). The capacity of activated sludge to biodegrade OT compounds in the absence of supplemental substrate indicated that these compounds can be metabolized as single sources of carbon and energy in activated sludge systems. Excluding TBT, the presence of low concentrations of supplemental substrate did not affect the biodegradation potential of activated sludge. The acclimatization of biomass on OT compounds enhanced significantly biodegradation, resulting in significant decreases of half-lives of OT compounds. As a result in the presence of acclimatized biomass, half-lives of 1.4, 3.6, 9.8 and 5.0 days were calculated for TBT, DBT, MBT and TPhT, respectively. - The fate of organotins is assessed in activated sludge systems.

  3. Aerobic biodegradation of organotin compounds in activated sludge batch reactors

    International Nuclear Information System (INIS)

    Stasinakis, Athanasios S.; Thomaidis, Nikolaos S.; Nikolaou, Anastasia; Kantifes, Andreas

    2005-01-01

    The biodegradation behavior of four organotin (OT) compounds, namely tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT) and triphenyltin (TPhT), was studied in lab-scale activated sludge batch reactors. The activated sludge was spiked with the OT compounds at a level of 100 μg l -1 as Sn. Determination of the OT compounds by GC-FPD after ethylation in the dissolved and particulate phase revealed that 24 h after the start of the experiments, almost the total of OT compounds has been removed from the dissolved phase and is associated with the suspended solids. Calculation of mass balance in batch reactors showed that OT compounds biodegradation was performed via a sequential dealkylation process. Removals due to biodegradation were differentiated according to the parent compound. In experiments with non-acclimatized biomass, a percentage of 27.1, 8.3, 73.8 and 51.3 was still present as TBT, DBT, MBT and TPhT, respectively, at the end of the experiment (18th day). Half-lives (t 1/2 ) of 10.2 and 5.1 days were calculated for TBT and DBT, respectively, whereas apparent t 1/2 values could not be determined for MBT and TPhT (t 1/2 > 18 days). The capacity of activated sludge to biodegrade OT compounds in the absence of supplemental substrate indicated that these compounds can be metabolized as single sources of carbon and energy in activated sludge systems. Excluding TBT, the presence of low concentrations of supplemental substrate did not affect the biodegradation potential of activated sludge. The acclimatization of biomass on OT compounds enhanced significantly biodegradation, resulting in significant decreases of half-lives of OT compounds. As a result in the presence of acclimatized biomass, half-lives of 1.4, 3.6, 9.8 and 5.0 days were calculated for TBT, DBT, MBT and TPhT, respectively. - The fate of organotins is assessed in activated sludge systems

  4. Packed Bed Reactor Technology for Chemical-Looping Combustion

    NARCIS (Netherlands)

    Noorman, S.; Sint Annaland, van M.; Kuipers, J.A.M.

    2007-01-01

    Chemical-looping combustion (CLC) has emerged as an alternative for conventional power production processes to intrinsically integrate power production and CO2 capture. In this work a new reactor concept for CLC is proposed, based on dynamically operated packed bed reactors. With analytical

  5. Biological Phosphorus Removal in a Moving Bed Biofilm Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Helness, Herman

    2007-09-15

    The scope of this study was to investigate use of the moving bed biofilm reactor (MBBR) process for biological phosphorus removal. The goal has been to describe the operating conditions required for biological phosphorus and nitrogen removal in a MBBR operated as a sequencing batch reactor (SBR), and determine dimensioning criteria for such a process

  6. Mixing and scale affect moving bed biofilm reactor (MBBR) performance

    NARCIS (Netherlands)

    Kamstra, Andries; Blom, Ewout; Terjesen, Bendik Fyhn

    2017-01-01

    Moving Bed Biofilm Reactors (MBBR) are used increasingly in closed systems for farming of fish. Scaling, i.e. design of units of increasing size, is an important issue in general bio-reactor design since mixing behaviour will differ between small and large scale. Research is mostly performed on

  7. Fluidized-bed-combustion ash for the solidification and stabilization of a metal-hydroxide sludge.

    Science.gov (United States)

    Knoll, K L; Behr-Andres, C

    1998-01-01

    Fluidized-bed-combustion (FBC) ash is a by-product from a developing technology for coal-fired power plants that will economically reduce air emissions to meet requirements of the Clean Air Act. FBC ash has physical and chemical properties similar to Portland cement, but only has moderate success as a pozzolan in concrete applications due to low compressive strengths. However, FBC ash has proven effective for use as a binder for the solidification and stabilization (S/S) of metal-bearing sludges. Physical and chemical characterization procedures were used to analyze FBC ash and a metal-bearing sludge obtained from a hazardous waste treatment facility to develop 12 different S/S mix designs. The mix designs consist of four binder designs to evaluate sludge-to-binder ratios of approximately 0, 0.5, and 1. Portland cement is used as a control binder to compare unconfined compressive strengths and Toxicity Characteristic Leaching Procedure (TCLP) analyses from different ratios of the FBC ash streams: fly ash, char, and spent bed material (SBM). Compressive strengths ranging from 84 lbs per square inch (psi) to 298 psi were obtained from various mix designs containing different sludge-to-ash ratios cured for 28 days. All the mix designs passed the TCLP. Recoveries from leaching for each metal were less than 5% for most mix designs. Results of unconfined compressive strengths, TCLP, and percent recovery calculations indicate that the mix design containing approximately a 1:1 ratio of fly ash to char-and-sludge is the best mix design for the S/S of the metal-bearing sludge.

  8. Energy recovery from sewage sludge by means of fluidised bed gasification

    International Nuclear Information System (INIS)

    Gross, Bodo; Eder, Christian; Grziwa, Peter; Horst, Juri; Kimmerle, Klaus

    2008-01-01

    Because of its potential harmful impact on the environment, disposal of sewage sludge is becoming a major problem all over the world. Today the available disposal measures are at the crossroads. One alternative would be to continue its usage as fertiliser or to abandon it. Due to the discussions about soil contamination caused by sewage sludge, some countries have already prohibited its application in agriculture. In these countries, thermal treatment is now presenting the most common alternative. This report describes two suitable methods to directly convert sewage sludge into useful energy on-site at the wastewater treatment plant. Both processes consist mainly of four devices: dewatering and drying of the sewage sludge, gasification by means of fluidised bed technology (followed by a gas cleaning step) and production of useful energy via CHP units as the final step. The process described first (ETVS-Process) is using a high pressure technique for the initial dewatering and a fluidised bed technology utilising waste heat from the overall process for drying. In the second process (NTVS-Process) in addition to the waste heat, solar radiation is utilised. The subsequent measures - gasification, gas cleaning and electric and thermal power generation - are identical in both processes. The ETVS-Process and the NTVS-Process are self-sustaining in terms of energy use; actually a surplus of heat and electricity is generated in both processes

  9. Fluidized bed reactor for working up carbon coated particles

    International Nuclear Information System (INIS)

    Marschollek, M.; Simon, W.; Walter, C.

    1981-01-01

    A fluidized bed reactor is described for working up carbon coated particles, particularly nuclear fuel particles or fertile material particles consisting essentially of a cylindrical portion connected to a conical portion. Gas supply pipes, gas distribution space and gas distribution heads are provided within the conical reactor lower portion, the gas distribution members being arranged in at least two superimposed planes and distributed symmetrically over the cross-section of the reactor

  10. Gaseous Emissions from the Fluidized-bed Incineration of Sewage Sludge

    Czech Academy of Sciences Publication Activity Database

    Pohořelý, Michael; Svoboda, Karel; Trnka, Otakar; Baxter, D.; Hartman, Miloslav

    2005-01-01

    Roč. 59, 6b (2005), s. 458-463 ISSN 0366-6352. [International Conference SSCHE /32./. Tatranské Matliare, 23.05.2005-27.05.2005] R&D Projects: GA AV ČR IAA4072201; GA AV ČR KSK4040110 Institutional research plan: CEZ:AV0Z40720504 Keywords : sewage sludge * fluidized-bed incineration * solid fuels Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.409, year: 2005

  11. Operation of an aquatic worm reactor suitable for sludge reduction at large scale

    NARCIS (Netherlands)

    Hendrickx, T.L.G.; Elissen, H.J.H.; Temmink, B.G.; Buisman, C.J.N.

    2011-01-01

    Treatment of domestic waste water results in the production of waste sludge, which requires costly further processing. A biological method to reduce the amount of waste sludge and its volume is treatment in an aquatic worm reactor. The potential of such a worm reactor with the oligochaete

  12. Environmental Assessment of Sewage Sludge Management – Focusing on Sludge Treatment Reed Bed Systems

    DEFF Research Database (Denmark)

    Larsen, Julie Dam

    profiles of the STRB system technology and a mechanical treatment technology, constituting a basis for decision-making in relation to choice of technology. A major part of the project involved performance of fieldwork and laboratory work. Data were collected at three Danish, well-operated STRB systems...... assessment were based on international acknowledged standards and recommendations. An attributional LCA approach was chosen, and the loadings and savings for all impact categories were normalised to people equivalents (PE) (the annual loadings and savings provided by one average person). Three sludge...... gasses CH4 and N2O were larger for mechanical dewatered sludge, the net environmental loadings provided to the impact category Climate Change by this technology (S-CEN) and the STRB system technology (S-STRB and S-SPA) ended up being equally sized (9.010-4 PE), despite of higher biological activity...

  13. 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.

  14. The study of partitioning of heavy metals during fluidized bed combustion of sewage sludge and coal

    Energy Technology Data Exchange (ETDEWEB)

    Gulyurtlu, I.; Lopes, M.H.; Abelha, P.; Cabrita, I.; Oliveira, J.F.S. [INETI, Lisbon (Portugal)

    2006-06-15

    The behavior of Cd, Cr, Cu, Co, Mn, Ni, Pb, Zn, and Hg during the combustion tests of a dry granular sewage sludge on a fluidized bed combustor pilot (FBC) of about 0.3 MW was evaluated. The emissions of these heavy metals from mono-combustion were compared with those of co-combustion of the sludge with a bituminous coal. The effect of the addition of limestone was also studied in order to retain sulphur compounds and to verify its influence on the retention of heavy metals (HM). Heavy metals were collected and analyzed from different locations of the installation, which included the stack, the two cyclones, and the material removed from the bed. The results showed that the volatility of metals was rather low, resulting in emissions below the legal limits of the new directive on incineration, with the exception of Hg during the mono-combustion tests. The partitioning of metals, except for Hg, appeared to follow that of ashes, amounting to levels above 90% in the bed streams in the mono-combustion case. For co-combustion, there was a lower fixation of HM in the bed ashes, mostly originating essentially from the sewage sludge, ranging between 40% and 80%. It is believed that in this latter case, a slightly higher temperature could have enhanced the volatilization, especially of Cd and Pb. However these metals were then retained in fly ashes captured in the cyclones. In the case of Hg, the volatilisation was complete. The bed ashes were free of Hg and part of Hg was retained in the cyclones and the rest was emitted either with fine ash particles or in gaseous forms. In mono-combustion the Hg emissions from the stack (particles and gas) accounted, for about 50%. This appeared to have significantly decreased in the case of co-combustion, as only about 75% has been emitted, due to the retention effect of cyclone ashes.

  15. The study of partitioning of heavy metals during fluidized bed combustion of sewage sludge and coal

    Energy Technology Data Exchange (ETDEWEB)

    Gulyurtlu, Ibrahim; Lopes, M. Helena; Abelha, Pedro; Cabrita, Isabel; Oliveira, J.F. Santos

    2003-07-01

    The behaviour of Cd, Cr, Cu, Co, Mn, Pb, Zn and Hg during the combustion tests of granular dry sewage sludges on a pilot FBC of about 0,3 MW was evaluated. The emissions of these heavy metals from mono-combustion were compared with those of co-combustion of the sludge with a bituminous coal. The effect of the addition of limestone was also studied in order to retain sulphur compounds and to verify its influence on the retention of heavy metals. Heavy metals were collected and analysed from different locations of the installation, which included the stack, the two cyclones and the material removed from the bed. The results showed that the volatility of metals was rather low, resulting in emissions below the legal limits of the new directive on incineration, with the exception of Hg during the mono-combustion tests. The partitioning of metals, except for Hg, appeared to follow that of ashes, amounting to levels above 90% in the bed streams in the mono-combustion case. For co-combustion, there was a lower fixation of HM in the bed ashes, mostly originating essentially from the sewage sludge, ranging between 40 and 80%. It is believed that in this latter case, a slightly higher bed temperature could have enhanced the volatilisation, especially of Cd and Pb. However these metals were then retained in cyclone ashes. In the case of Hg, the volatilisation was complete. The bed ashes were free of Hg and part of it was retained in the cyclone and emitted as both fine ash particles and in gaseous forms. In mono-combustion the Hg emissions from the stack (particles and gas) accounted for about 50%, although there was a significant amount unaccounted for. This appeared to have significantly decreased in the case of co-combustion, as only about 15% has been emitted, due to the retention effect of cyclone ashes which presented high quantities of unburned carton and possibly condensed sulphur species.

  16. Characterization of the insoluble sludge from the dissolution of irradiated fast breeder reactor fuel

    Energy Technology Data Exchange (ETDEWEB)

    Aihara, Haruka; Arai, Yoichi; Shibata, Atsuhiro; Nomura, K.; Takeuchi, M. [Japan Atomic Energy Agency - JAEA, 4-33 Muramatsu, Tokai-mura, Naka-gun, Ibaraki, 319-1194 (Japan)

    2016-07-01

    Insoluble sludge is generated in the reprocessing of spent fuel. The sludge obtained from the dissolution of irradiated fuel from the Joyo experimental fast reactor was analyzed to evaluate its chemical form. The sludge was collected by the filtration of the dissolved fuel solution, and then washed in nitric acid. The yields of the sludge weight were less than 1% of the total fuel weight. The chemical composition of the sludge was analyzed after decomposition by alkaline fusion. Molybdenum, technetium, ruthenium, rhodium, and palladium were found to be the main constituent elements of the sludge. X-ray diffraction patterns of the sludge were attributable to Mo{sub 4}Ru{sub 4}RhPd, regardless of the experimental conditions. The concentrations of molybdenum and zirconium in the dissolved fast reactor fuel solutions were low, indicating that zirconium molybdate hydrate (ZMH) is produced in negligible amounts in the process. (authors)

  17. Improved Dechlorinating Performance of Upflow Anaerobic Sludge Blanket Reactors by Incorporation of Dehalospirillum multivorans into Granular Sludge

    Science.gov (United States)

    Hörber, Christine; Christiansen, Nina; Arvin, Erik; Ahring, Birgitte K.

    1998-01-01

    Dechlorination of tetrachloroethene, also known as perchloroethylene (PCE), was investigated in an upflow anaerobic sludge blanket (UASB) reactor after incorporation of the strictly anaerobic, reductively dechlorinating bacterium Dehalospirillum multivorans into granular sludge. This reactor was compared to the reference 1 (R1) reactor, where the granules were autoclaved to remove all dechlorinating abilities before inoculation, and to the reference 2 (R2) reactor, containing only living granular sludge. All three reactors were fed mineral medium containing 3 to 57 μM PCE, 2 mM formate, and 0.5 mM acetate and were operated under sterile conditions. In the test reactor, an average of 93% (mole/mole) of the effluent chloroethenes was dichloroethene (DCE), compared to 99% (mole/mole) in the R1 reactor. The R2 reactor, with no inoculation, produced only trichloroethene (TCE), averaging 43% (mole/mole) of the effluent chloroethenes. No dechlorination of PCE was observed in an abiotic control consisting of sterile granules without inoculum. During continuous operation with stepwise-reduced hydraulic retention times (HRTs), both the test reactor and the R1 reactor showed conversion of PCE to DCE, even at HRTs much lower than the reciprocal maximum specific growth rate of D. multivorans, indicating that this bacterium was immobilized in the living and autoclaved granular sludge. In contrast, the R2 reactor, with no inoculation of D. multivorans, only converted PCE to TCE under the same conditions. Immobilization could be confirmed by using fluorescein-labeled antibody probes raised against D. multivorans. In granules obtained from the R1 reactor, D. multivorans grew mainly in microcolonies located in the centers of the granules, while in the test reactor, the bacterium mainly covered the surfaces of granules. PMID:9572963

  18. Inhibition and recovery of nitrification in treating real coal gasification wastewater with moving bed biofilm reactor

    Institute of Scientific and Technical Information of China (English)

    Huiqiang Li; Hongjun Han; Maoan Du; Wei Wang

    2011-01-01

    Moving bed biofilm reactor (MBBR) was used to treat real coal gasification wastewater.Nitrification of the MBBR was inhibited almost completely during start-up period.Sudden increase of influent total NH3 concentration was the main factor inducing nitrification inhibition.Increasing DO concentration in the bulk liquid (from 2 to 3 mg/L) had little effect on nitrification recovery.Nitrification of the MBBR recovered partially by the addition of nitrifying sludge into the reactor and almost ceased within 5 days.Nitrification ratio of the MBBR achieved 65% within 12 days by increasing dilute ratio of the influent wastewater with tap water.The ratio of nitrification decreased to 25% when infiuent COD concentration increased from 650 to 1000 mg/L after nitrification recovery and recovered 70%for another 4 days.

  19. 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)

  20. Optimizing aeration rates for minimizing membrane fouling and its effect on sludge characteristics in a moving bed membrane bioreactor

    International Nuclear Information System (INIS)

    Rahimi, Yousef; Torabian, Ali; Mehrdadi, Naser; Habibi-Rezaie, Mehran; Pezeshk, Hamid; Nabi-Bidhendi, Gholam-Reza

    2011-01-01

    Research highlights: → There is an optimum aeration rate in the MBMBR process compartments. → Optimum aeration rate maximizes nutrients removal. → Optimum aeration rate minimizes membrane fouling. → Both aeration rates in MBBR and membrane compartment can affect on membrane permeability. - Abstract: In MBR processes, sufficient aeration is necessary to maintain sustainable flux and to retard membrane fouling. Membrane permeability, sludge characteristics, nutrient removal and biomass growth at various air flow rates in the membrane and moving bed biofilm reactor (MBBR) compartments were studied in a pilot plant. The highest nitrogen and phosphorous removal rates were found at MBBR aeration rates of 151 and 85 L h -1 and a specific aeration demand per membrane area (SAD m ) of 1.2 and 0.4m air 3 m -2 h -1 , respectively. A linear correlation was found between the amount of attached biofilm and the nutrient removal rate. The aeration rate in the MBBR compartment and SAD m significantly influenced the sludge characteristics and membrane permeability. The optimum combination of the aeration rate in the MBBR compartment and SAD m were 151 L h -1 and 0.8-1.2m air 3 m membrane -2 h -1 , respectively.

  1. Optimizing aeration rates for minimizing membrane fouling and its effect on sludge characteristics in a moving bed membrane bioreactor

    Energy Technology Data Exchange (ETDEWEB)

    Rahimi, Yousef, E-mail: yrahimi@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); 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); Habibi-Rezaie, Mehran, E-mail: mhabibi@khayam.ut.ac.ir [Department of Biotechnology, Faculty of Biology, College of Science, University of Tehran, No. 25 Qods St., Enghelab Ave., Tehran (Iran, Islamic Republic of); Pezeshk, Hamid, E-mail: pezeshk@khayam.ut.ac.ir [Department of Statistics, Faculty of Mathematics and Computer, College of Science, University of Tehran, No. 25 Qods St., Enghelab Ave., Tehran (Iran, Islamic Republic of); Nabi-Bidhendi, Gholam-Reza, E-mail: ghhendi@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)

    2011-02-28

    Research highlights: {yields} There is an optimum aeration rate in the MBMBR process compartments. {yields} Optimum aeration rate maximizes nutrients removal. {yields} Optimum aeration rate minimizes membrane fouling. {yields} Both aeration rates in MBBR and membrane compartment can affect on membrane permeability. - Abstract: In MBR processes, sufficient aeration is necessary to maintain sustainable flux and to retard membrane fouling. Membrane permeability, sludge characteristics, nutrient removal and biomass growth at various air flow rates in the membrane and moving bed biofilm reactor (MBBR) compartments were studied in a pilot plant. The highest nitrogen and phosphorous removal rates were found at MBBR aeration rates of 151 and 85 L h{sup -1} and a specific aeration demand per membrane area (SAD{sub m}) of 1.2 and 0.4m{sub air}{sup 3} m{sup -2} h{sup -1}, respectively. A linear correlation was found between the amount of attached biofilm and the nutrient removal rate. The aeration rate in the MBBR compartment and SAD{sub m} significantly influenced the sludge characteristics and membrane permeability. The optimum combination of the aeration rate in the MBBR compartment and SAD{sub m} were 151 L h{sup -1} and 0.8-1.2m{sub air}{sup 3}m{sub membrane}{sup -2} h{sup -1}, respectively.

  2. Performance Evaluation of Moving Bed Bio Film Reactor in Saline Wastewater Treatment

    Directory of Open Access Journals (Sweden)

    M Ahmadi

    2013-06-01

    Full Text Available Background and purpose:Moving Bed Biofilm Reactor is an aerobic attached growth with better biofilm thickness control, lack of plugging and lower head loss. Consequently, this system is greatly used by different wastewater treatment plants. High TDS wastewater produced petrochemical, leather tanning, sea food processing, cannery, pickling and dairy industries. The aim of this study was to evaluate the performance of MBBR in saline wastewater treatment. Materials and methods: In this study, 50 percent of a cylindrical reactor with 9.5 liter occupied media with 650 m2.m-3. In the first step, hydraulic regime was evaluated and startup reactor was done by sanitary sludge. Bio film was generated with glucose as the sole carbon source in synthetic wastewater. MBBR performance evaluation was performed in 6:30 and 8:45 with saline wastewater after bio film produced on media. Results: After 83 days of passing MBBR operation with saline wastewater containing 3000-12000 mg.L-1 TDS, organic loading rate of 2.2-3.5 kg/m3.d COD removal efficiency reached 80-92%. Conclusion: Moving bed biofilm reactor is effective in organic load elimination from saline wastewater.

  3. Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor

    Science.gov (United States)

    Guerrero-Barajas, Claudia; Ordaz, Alberto; García-Solares, Selene Montserrat; Garibay-Orijel, Claudio; Bastida-González, Fernando; Zárate-Segura, Paola Berenice

    2015-01-01

    The importance of microbial sulfate reduction relies on the various applications that it offers in environmental biotechnology. Engineered sulfate reduction is used in industrial wastewater treatment to remove large concentrations of sulfate along with the chemical oxygen demand (COD) and heavy metals. The most common approach to the process is with anaerobic bioreactors in which sulfidogenic sludge is obtained through adaptation of predominantly methanogenic granular sludge to sulfidogenesis. This process may take a long time and does not always eliminate the competition for substrate due to the presence of methanogens in the sludge. In this work, we propose a novel approach to obtain sulfidogenic sludge in which hydrothermal vents sediments are the original source of microorganisms. The microbial community developed in the presence of sulfate and volatile fatty acids is wide enough to sustain sulfate reduction over a long period of time without exhibiting inhibition due to sulfide. This protocol describes the procedure to generate the sludge from the sediments in an upflow anaerobic sludge blanket (UASB) type of reactor. Furthermore, the protocol presents the procedure to demonstrate the capability of the sludge to remove by reductive dechlorination a model of a highly toxic organic pollutant such as trichloroethylene (TCE). The protocol is divided in three stages: (1) the formation of the sludge and the determination of its sulfate reducing activity in the UASB, (2) the experiment to remove the TCE by the sludge, and (3) the identification of microorganisms in the sludge after the TCE reduction. Although in this case the sediments were taken from a site located in Mexico, the generation of a sulfidogenic sludge by using this procedure may work if a different source of sediments is taken since marine sediments are a natural pool of microorganisms that may be enriched in sulfate reducing bacteria. PMID:26555802

  4. Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor.

    Science.gov (United States)

    Guerrero-Barajas, Claudia; Ordaz, Alberto; García-Solares, Selene Montserrat; Garibay-Orijel, Claudio; Bastida-González, Fernando; Zárate-Segura, Paola Berenice

    2015-10-15

    The importance of microbial sulfate reduction relies on the various applications that it offers in environmental biotechnology. Engineered sulfate reduction is used in industrial wastewater treatment to remove large concentrations of sulfate along with the chemical oxygen demand (COD) and heavy metals. The most common approach to the process is with anaerobic bioreactors in which sulfidogenic sludge is obtained through adaptation of predominantly methanogenic granular sludge to sulfidogenesis. This process may take a long time and does not always eliminate the competition for substrate due to the presence of methanogens in the sludge. In this work, we propose a novel approach to obtain sulfidogenic sludge in which hydrothermal vents sediments are the original source of microorganisms. The microbial community developed in the presence of sulfate and volatile fatty acids is wide enough to sustain sulfate reduction over a long period of time without exhibiting inhibition due to sulfide. This protocol describes the procedure to generate the sludge from the sediments in an upflow anaerobic sludge blanket (UASB) type of reactor. Furthermore, the protocol presents the procedure to demonstrate the capability of the sludge to remove by reductive dechlorination a model of a highly toxic organic pollutant such as trichloroethylene (TCE). The protocol is divided in three stages: (1) the formation of the sludge and the determination of its sulfate reducing activity in the UASB, (2) the experiment to remove the TCE by the sludge, and (3) the identification of microorganisms in the sludge after the TCE reduction. Although in this case the sediments were taken from a site located in Mexico, the generation of a sulfidogenic sludge by using this procedure may work if a different source of sediments is taken since marine sediments are a natural pool of microorganisms that may be enriched in sulfate reducing bacteria.

  5. Experimental study of flow field characteristics on bed configurations in the pebble bed reactor

    International Nuclear Information System (INIS)

    Jia, Xinlong; Gui, Nan; Yang, Xingtuan; Tu, Jiyuan; Jia, Haijun; Jiang, Shengyao

    2017-01-01

    Highlights: • PTV study of flow fields of pebble bed reactor with different configurations are carried out. • Some criteria are proposed to quantify vertical velocity field and flow uniformity. • The effect of different pebble bed configurations is also compared by the proposed criteria. • The displacement thickness is used analogically to analyze flow field characteristics. • The effect of mass flow variation in the stagnated region of the funnel flow is measured. - Abstract: The flow field characteristics are of fundamental importance in the design work of the pebble bed high temperature gas cooled reactor (HTGR). The different effects of bed configurations on the flow characteristics of pebble bed are studied through the PTV (Particle Tracking Velocimetry) experiment. Some criteria, e.g. flow uniformity (σ) and mass flow level (α), are proposed to estimate vertical velocity field and compare the bed configurations. The distribution of the Δθ (angle difference between the individual particle velocity and the velocity vector sum of all particles) is also used to estimate the resultant motion consistency level. Moreover, for each bed configuration, the thickness of displacement is analyzed to measure the effect of the funnel flow zone based on the boundary layer theory. Detailed information shows the quantified characteristics of bed configuration effects on flow uniformity and other characteristics; and the sequence of levels of each estimation criterion is obtained for all bed configurations. In addition, a good design of the pebble bed configuration is suggested and these estimation criteria can be also applied and adopted in testing other geometry designs of pebble bed.

  6. Anaerobic digestion of cheese whey using up-flow anaerobic sludge blanket reactor

    Energy Technology Data Exchange (ETDEWEB)

    Yan, J.Q.; Lo, K.V.; Liao, P.H.

    1989-01-01

    Anaerobic treatment of cheese whey using a 17.5-litre up-flow anaerobic sludge blanket reactor was investigated in the laboratory. The reactor was studied over a range of influent concentration from 4.5 to 38.1 g chemical oxygen demand per litre at a constant hydraulic retention time of 5 days. The reactor start-up and the sludge acclimatization were discussed. The reactor performance in terms of methane production, volatile fatty acids conversion, sludge net growth and chemical oxygen demand reduction were also presented in this paper. Over 97% chemical oxygen demand reduction was achieved in this experiment. At the influent concentration of 38.1 g chemical oxygen demand per litre, an instability of the reactor was observed. The results indicated that the up-flow anaerobic sludge blanket reactor process could treat cheese whey effectively.

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

    Science.gov (United States)

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

    2014-11-01

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

  8. 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.)

  9. 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...

  10. Thermalhydraulics of flowing particle-bed-type fusion reactor blankets

    International Nuclear Information System (INIS)

    Nietert, R.E.; Abdelk-Khalik, S.I.

    1982-01-01

    An experimental investigation has been conducted to determine the heat transfer characteristics of gravity-flowing particle beds using a special heat transfer loop. Glass microspheres were allowed to flow by gravity at controlled rates through an electrically heated stainless steel tubular test section. Values of the local and average convective heat transfer coefficient as a function of the average bed velocity, particle size and heat flux were determined. Such information is necessary for the design of gravity-flowing particle-bed type fusion reactor-blankets and associated tritium recovery systems. (orig.)

  11. Operational strategy, economic and environmental performance of sludge treatment reed bed systems - based on 28 years of experience

    DEFF Research Database (Denmark)

    Nielsen, S.; Larsen, Julie Dam

    2016-01-01

    Sludge treatment reed bed (STRB) systems have been used for dewatering and mineralisation of sludge in Europe since 1988. STRB systems provide substantial environmental, economic, and operational benefits compared to mechanical sludge dewatering solutions such as belt presses and centrifuges....... They require less energy, no chemicals, reduce the sludge volume and produce bio solids with dry solid contents up to 20-40% under Danish climate conditions, depending on the sludge quality. Experience has shown that sludge treated in STRBs represents a high quality product with a low content of pathogens...... compared to conventional mechanical dewatering devices, delivering an economic break-even of about 3-5 years. This paper provides an overview of the operation and maintenance costs and environmental benefits of a typical STRB based on the experiences gained from the operation of a large number of STRBs...

  12. Low temperature circulating fluidized bed gasification and co-gasification of municipal sewage sludge. Part 2: Evaluation of ash materials as phosphorus fertilizer.

    Science.gov (United States)

    Thomsen, Tobias Pape; Hauggaard-Nielsen, Henrik; Gøbel, Benny; Stoholm, Peder; Ahrenfeldt, Jesper; Henriksen, Ulrik B; Müller-Stöver, Dorette Sophie

    2017-08-01

    The study is part 2 of 2 in an investigation of gasification and co-gasification of municipal sewage sludge in low temperature gasifiers. In this work, solid residuals from thermal gasification and co-gasification of municipal sewage sludge were investigated for their potential use as fertilizer. Ashes from five different low temperature circulating fluidized bed (LT-CFB) gasification campaigns including two mono-sludge campaigns, two sludge/straw mixed fuels campaigns and a straw reference campaign were compared. Experiments were conducted on two different LT-CFBs with thermal capacities of 100kW and 6MW, respectively. The assessment included: (i) Elemental composition and recovery of key elements and heavy metals; (ii) content of total carbon (C) and total nitrogen (N); (iii) pH; (iv) water extractability of phosphorus after incubation in soil; and (v) plant phosphorus response measured in a pot experiment with the most promising ash material. Co-gasification of straw and sludge in LT-CFB gasifiers produced ashes with a high content of recalcitrant C, phosphorus (P) and potassium (K), a low content of heavy metals (especially cadmium) and an improved plant P availability compared to the mono-sludge ashes, thereby showing the best fertilizer qualities among all assessed materials. It was also found that bottom ashes from the char reactor contained even less heavy metals than cyclone ashes. It is concluded that LT-CFB gasification and co-gasification is a highly effective way to purify and sanitize sewage sludge for subsequent use in agricultural systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Effect of bed configuration on pebble flow uniformity and stagnation in the pebble bed reactor

    International Nuclear Information System (INIS)

    Gui, Nan; Yang, Xingtuan; Tu, Jiyuan; Jiang, Shengyao

    2014-01-01

    Highlights: • Pebble flow uniformity and stagnation characteristics are very important for HTR-PM. • Arc- and brachistochrone-shaped configuration effects are studied by DEM simulation. • Best bed configurations with uniform flow and no stagnated pebbles are suggested. • Detailed quantified characteristics of bed configuration effects are shown for explanation. - Abstract: Pebble flow uniformity and stagnation characteristics are very important for the design of pebble bed high temperature gas-cooled reactor. Pebble flows inside some specifically designed contraction configurations of pebble bed are studied by discrete element method. The results show the characteristics of stagnation rates, recycling rates, radial distribution of pebble velocity and residence time. It is demonstrated clearly that the bed with a brachistochrone-shaped configuration achieves optimum levels of flow uniformity and recycling rate concentration, and almost no pebbles are stagnated in the bed. Moreover, the optimum choice among the arc-shaped bed configurations is demonstrated too. Detailed information shows the quantified characteristics of bed configuration effects on flow uniformity. In addition, a good design of the pebble bed configuration is suggested

  14. Nonproliferation and safeguard considerations: Pebble Bed reactor fuel cycle evaluation

    International Nuclear Information System (INIS)

    1978-09-01

    Nuclear fuel cycles were evaluated for the Pebble Bed Gas Cooled Reactor under development in the Federal Republic of Germany. The basic fuel cycle specified for the HTR-K and PNP is well qualified and will meet the requirements of these reactors. Twenty alternate fuel cycles are described, including high-conversion cycles, net-breeding cycles, and proliferation-resistant cycles. High-conversion cycles, which have a high probability of being successfully developed, promise a significant improvement in resource utilization. Proliferation-resistant cycles, also with a high probability of successful development, conpare very favorably with those for other types of reactors. Most of the advanced cycles could be adapted to first-generation pebble bed reactors with no significant modifications

  15. High power density reactors based on direct cooled particle beds

    Science.gov (United States)

    Powell, J. R.; Horn, F. L.

    Reactors based on direct cooled High Temperature Gas Cooled Reactor (HTGR) type particle fuel are described. The small diameter particle fuel is packed between concentric porous cylinders to make annular fuel elements, with the inlet coolant gas flowing inwards. Hot exit gas flows out along the central channel of each element. Because of the very large heat transfer area in the packed beds, power densities in particle bed reactors (PBRs) are extremely high resulting in compact, lightweight systems. Coolant exit temperatures are high, because of the ceramic fuel temperature capabilities, and the reactors can be ramped to full power and temperature very rapidly. PBR systems can generate very high burst power levels using open cycle hydrogen coolant, or high continuous powers using closed cycle helium coolant. PBR technology is described and development requirements assessed.

  16. Steam reforming of heptane in a fluidized bed membrane reactor

    Science.gov (United States)

    Rakib, Mohammad A.; Grace, John R.; Lim, C. Jim; Elnashaie, Said S. E. H.

    n-Heptane served as a model compound to study steam reforming of naphtha as an alternative feedstock to natural gas for production of pure hydrogen in a fluidized bed membrane reactor. Selective removal of hydrogen using Pd 77Ag 23 membrane panels shifted the equilibrium-limited reactions to greater conversion of the hydrocarbons and lower yields of methane, an intermediate product. Experiments were conducted with no membranes, with one membrane panel, and with six panels along the height of the reactor to understand the performance improvement due to hydrogen removal in a reactor where catalyst particles were fluidized. Results indicate that a fluidized bed membrane reactor (FBMR) can provide a compact reformer for pure hydrogen production from a liquid hydrocarbon feedstock at moderate temperatures (475-550 °C). Under the experimental conditions investigated, the maximum achieved yield of pure hydrogen was 14.7 moles of pure hydrogen per mole of heptane fed.

  17. Biological sulphate reduction with primary sewage sludge in an ...

    African Journals Online (AJOL)

    2009-07-31

    Jul 31, 2009 ... The success of the UASB reactor depends largely on the settling properties and stability of the sludge bed which comprises the anaerobic active biomass. The solid-liquid separation behaviour of the sludge bed in 2 UASB reactors (R1 at 35oC and. R2 at 20oC) fed with primary sewage sludge and sulphate ...

  18. Anaerobic treatment of winery wastewater in fixed bed reactors.

    Science.gov (United States)

    Ganesh, Rangaraj; Rajinikanth, Rajagopal; Thanikal, Joseph V; Ramanujam, Ramamoorty Alwar; Torrijos, Michel

    2010-06-01

    The treatment of winery wastewater in three upflow anaerobic fixed-bed reactors (S9, S30 and S40) with low density floating supports of varying size and specific surface area was investigated. A maximum OLR of 42 g/l day with 80 +/- 0.5% removal efficiency was attained in S9, which had supports with the highest specific surface area. It was found that the efficiency of the reactors increased with decrease in size and increase in specific surface area of the support media. Total biomass accumulation in the reactors was also found to vary as a function of specific surface area and size of the support medium. The Stover-Kincannon kinetic model predicted satisfactorily the performance of the reactors. The maximum removal rate constant (U(max)) was 161.3, 99.0 and 77.5 g/l day and the saturation value constant (K(B)) was 162.0, 99.5 and 78.0 g/l day for S9, S30 and S40, respectively. Due to their higher biomass retention potential, the supports used in this study offer great promise as media in anaerobic fixed bed reactors. Anaerobic fixed-bed reactors with these supports can be applied as high-rate systems for the treatment of large volumes of wastewaters typically containing readily biodegradable organics, such as the winery wastewater.

  19. 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)

  20. Aquatic worm reactor for improved sludge processing and resource recovery

    OpenAIRE

    Hendrickx, T.L.G.

    2009-01-01

    Municipal waste water treatment is mainly achieved by biological processes. These processes produce huge volumes of waste sludge (up 1.5 million m3/year in the Netherlands). Further processing of the waste sludge involves transportation, thickening and incineration. A decrease in the amount of waste sludge would be both environmentally and economically attractive. Aquatic worms can be used to reduce the amount of waste sludge. After predation by the worms, the amount of final sludge is lower....

  1. Parametric study for high conversion pebble bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Teuchert, E.; Ruetten, H. J.

    1975-06-15

    Tables are presented of fuel cycle costs, conversion ratios and accompanying variations in fuel element designs for a 3,00 MWth high conversion pebble bed reactor with initial high enriched uranium/thorium cycle and subsequent recycling of U-233, Pu-239 and Pu-241.

  2. The Performance of Structured Packings in Trickle-Bed Reactors

    NARCIS (Netherlands)

    Frank, M.J.W.; Kuipers, J.A.M.; Versteeg, G.F.; Swaaij, W.P.M. van

    1999-01-01

    An experimental study was carried out to investigate whether the use of structured packings might improve the mass transfer characteristics and the catalyst effectiveness of a trickle-bed reactor. Therefore, the performances of a structured packing, consisting of KATAPAK elements, and a dumped

  3. 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 ...

  4. Thymol Hydrogenation in Bench Scale Trickle Bed Reactor

    Czech Academy of Sciences Publication Activity Database

    Dudas, J.; Hanika, Jiří; Lepuru, J.; Barkhuysen, M.

    2005-01-01

    Roč. 19, č. 3 (2005), s. 255-262 ISSN 0352-9568 Institutional research plan: CEZ:AV0Z40720504 Keywords : thymol hydrogenation * trickle bed reactor * gas-liquid-solid reaction Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 0.632, year: 2005

  5. Trickle Bed Reactor Operation under Forced Liquid Feed Rate Modulation

    Czech Academy of Sciences Publication Activity Database

    Hanika, Jiří; Jiřičný, Vladimír; Karnetová, P.; Kolena, J.; Lederer, J.; Skála, D.; Staněk, Vladimír; Tukač, V.

    2007-01-01

    Roč. 13, č. 4 (2007), s. 192-198 ISSN 1451-9372 R&D Projects: GA MPO(CZ) FT-TA/039 Institutional research plan: CEZ:AV0Z40720504 Keywords : trickle -bed reactor * period * feed rate Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  6. Dicyclopentadiene Hydrogenation in Trickle Bed Reactor under Forced Periodic Control

    Czech Academy of Sciences Publication Activity Database

    Skála, D.; Hanika, Jiří

    2008-01-01

    Roč. 62, č. 2 (2008), s. 215-218 ISSN 1336-7242 R&D Projects: GA MPO(CZ) FT-TA/039 Institutional research plan: CEZ:AV0Z40720504 Keywords : periodic control * trickle -bed reactor * dicyclopentadiene Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  7. Small particle bed reactors: Sensitivity to Brayton cycle parameters

    Science.gov (United States)

    Coiner, John R.; Short, Barry J.

    Relatively simple particle bed reactor (PBR) algorithms were developed for optimizing low power closed Brayton cycle (CBC) systems. These algorithms allow the system designer to understand the relationship among key system parameters as well as the sensitivity of the PBR size and mass (a major system component) to variations in these parameters. Thus, system optimization can be achieved.

  8. Thermal-hydraulic modeling of porous bed reactors

    International Nuclear Information System (INIS)

    Araj, K.J.; Nourbakhsh, H.P.

    1987-01-01

    Optimum design of nuclear reactor core requires an iterative approach between the thermal-hydraulic, neutronic and operational analysis. This paper concentrates on the thermal-hydraulic behavior of a hydrogen cooled, small particle bed reactor (PBR). The PBR core, modeled here, consists of a hexagonal array of fuel elements embedded in a moderator matrix. The fuel elements are annular packed beds of fuel particles held between two porous cylindrical frits. These particles, 500 to 600 μm in diameter, have a uranium carbide core, which is coated by two layers of graphite and an outer coating of zirconium carbide. Coolant flow, radially inward, from the cold frit through the packed bed and hot frit and axially out the channel, formed by the hot frit, to a common plenum. 5 refs., 1 fig., 2 tabs

  9. Study on transient of fluidized bed nuclear reactor

    International Nuclear Information System (INIS)

    Streck, E.E.

    1988-01-01

    The point kinetic equations for a Fluidized-Bed Nuclear Reactor are solved by the method of Hansen. Due to the time varying nature of the reactor volume, the equations have a non-conventional formulation (moving boundary problem), but the method of solution preserves its asymptotic convergence and efficiency characteristics under this formulation. A one dimensional and linearized thermal hydraulics feedback model was coupled to the point kinetic equations in order to obtain a more realistic representation of the reactor power. The resulting equations are solved by the Euler explicit method. (author)

  10. COMPARISON OF UASB AND FLUIDIZED-BED REACTORS FOR SULFATE REDUCTION

    Directory of Open Access Journals (Sweden)

    S. M. Bertolino

    2015-03-01

    Full Text Available Abstract Reactor hydrodynamics is important for sulfidogenesis because sulfate reduction bacteria (SRB do not granulate easily. In this work, the sulfate reduction performance of two continuous anaerobic bioreactors was investigated: (i an upflow anaerobic sludge blanket (UASB reactor and (ii a fluidized bed reactor (FBR. Organic loading, sulfate reduction, and COD removal were the main parameters monitored during lactate and glycerol degradation. The UASB reactor with biomass recirculation showed a specific sulfate reduction rate of 0.089±0.014 g.gSSV-1.d-1 (89% reduction, whereas values twice as high were achieved in the FBR treating either lactate (0.200±0.017 g.gSSV-1.d-1 or glycerol (0.178±0.010 g.gSSV-1.d-1. Sulfate reduction with pure glycerol produced a smaller residual COD (1700 mg.L-1 than that produced with lactate (2500 mg.L-1 at the same COD.sulfate-1 mass ratio. It was estimated that 50% of glycerol degradation was due to sulfate reduction and 50% to fermentation, which was supported by the presence of butyrate in the FBR effluent. The UASB reactor was unable to produce effluents with sulfate concentrations below 250 mg.L-1 due to poor mixing conditions, whereas the FBR consistently ensured residual sulfate concentrations below such a value.

  11. Pellet bed reactor for multi-modal space power

    International Nuclear Information System (INIS)

    Buden, D.; Williams, K.; Mast, P.; Mims, J.

    1987-01-01

    A review of forthcoming space power needs for both civil and military missions indicates that power requirements will be in the tens of megawatts. The electrical power requirements are envisioned to be twofold: long-duration lower power levels will be needed for station keeping, communications, and/or surveillance; short-duration higher power levels will be required for pulsed power devices. These power characteristics led to the proposal of a multi-modal space power reactor using a pellet bed design. Characteristics desired for such a multimegawatt reactor power source are standby, alert, and pulsed power modes; high-thermal output heat source (approximately 1000 MWt peak power); long lifetime station keeping power (10 to 30 years); high temperature output (1500 K to 1800 K); rapid-burst power transition; high reliability (above 95 percent); and stringent safety standards compliance. The proposed pellet bed reactor is designed to satisfy these characteristics

  12. 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.

  13. High power density reactors based on direct cooled particle beds

    International Nuclear Information System (INIS)

    Powell, J.R.; Horn, F.L.

    1985-01-01

    Reactors based on direct cooled HTGR type particle fuel are described. The small diameter particle fuel is packed between concentric porous cylinders to make annular fuel elements, with the inlet coolant gas flowing inwards. Hot exit gas flows out long the central channel of each element. Because of the very large heat transfer area in the packed beds, power densities in particle bed reactors (PBR's) are extremely high resulting in compact, lightweight systems. Coolant exit temperatures are high, because of the ceramic fuel temperature capabilities, and the reactors can be ramped to full power and temperature very rapidly. PBR systems can generate very high burst power levels using open cycle hydrogen coolant, or high continuous powers using closed cycle helium coolant. PBR technology is described and development requirements assessed. 12 figs

  14. Improved dechlorinating performance of upflow anaerobic sludge blanket reactors by incorporation of Dehalospirillum multivorans into granular sludge

    DEFF Research Database (Denmark)

    Hörber, Christine; Christiansen, Nina; Arvin, Erik

    1998-01-01

    .5 mM acetate and were operated under sterile conditions. In the test reactor, an average of 93% (mole/mole) of the effluent chloroethenes was dichloroethene (DCE), compared to 99% (mole/mole) in the Ri reactor. The R2 reactor, with no inoculation, produced only trichloroethene (TCE), averaging 43...... to DCE, even at HRTs much lower than the reciprocal maximum specific growth rate of D. multivorans, indicating that this bacterium was immobilized in the living and autoclaved granular sludge. In contrast, the R2 reactor, with no inoculation of D. multivorans, only converted PCE to TCE under the same...

  15. Pebble Bed Reactor: core physics and fuel cycle analysis

    Energy Technology Data Exchange (ETDEWEB)

    Vondy, D.R.; Worley, B.A.

    1979-10-01

    The Pebble Bed Reactor is a gas-cooled, graphite-moderated high-temperature reactor that is continuously fueled with small spherical fuel elements. The projected performance was studied over a broad range of reactor applicability. Calculations were done for a burner on a throwaway cycle, a converter with recycle, a prebreeder and breeder. The thorium fuel cycle was considered using low, medium (denatured), and highly enriched uranium. The base calculations were carried out for electrical energy generation in a 1200 MW/sub e/ plant. A steady-state, continuous-fueling model was developed and one- and two-dimensional calculations were used to characterize performance. Treating a single point in time effects considerable savings in computer time as opposed to following a long reactor history, permitting evaluation of reactor performance over a broad range of design parameters and operating modes.

  16. Research results of sewage sludge and waste oil disposal by entrained bed gasification

    Energy Technology Data Exchange (ETDEWEB)

    Schingnitz, M.; Goehler, P.; Wenzel, W.; Seidel, W. (Noell-DBI Energie- und Entsorgungstechnik GmbH, Freiberg (Germany))

    1992-01-01

    Presents results of gasifying sewage sludge and waste oil with the GSP technology, developed by the Freiberg Fuel Institute (FRG). The GSP reactor was developed in 1976 for gasification of pulverized brown coal. An industrial reactor of this design operated for over 5 years with a total coal throughput of more than 300,000 t. The design of the gasification generator and the flowsheet of a 3 MW experimental pilot plant for waste gasification are presented. The PCB content in the gasification sludge is 6.14 mg/kg, in waste oil - 160 mg/kg. Gasification takes place at high temperatures of more than 1,400 C for complete destruction of toxic pollutants. Gasification results compare composition of raw gas produced by gasification of brown coal, sewage sludge and waste oil. A detailed list of content of pollutants (PCDD, PCDF, PAH, dioxin and furan) in the gasification gas, in process waters and in solid residue of the process water is provided. It is concluded that the GSP gasification process is suitable for safe disposal of waste with toxic content. 3 refs.

  17. Rotating bed reactor for CLC: Bed characteristics dependencies on internal gas mixing

    International Nuclear Information System (INIS)

    Håkonsen, Silje Fosse; Grande, Carlos A.; Blom, Richard

    2014-01-01

    Highlights: • A mathematical model for the rotating CLC reactor has been developed. • The model reflects the gas distribution in the reactor during CLC operation. • Radial dispersion in the rotating bed is the main cause for internal gas mixing. • The model can be used to optimize the reactor design and particle characteristics. - Abstract: A newly designed continuous lab-scale rotating bed reactor for chemical looping combustion using CuO/Al 2 O 3 oxygen carrier spheres and methane as fuel gives around 90% CH 4 conversion and >90% CO 2 capture efficiency based on converted methane at 800 °C. However, from a series of experiments using a broad range of operating conditions potential CO 2 purities only in the range 20–65% were yielded, mostly due to nitrogen slip from the air side of the reactor into the effluent CO 2 stream. A mathematical model was developed intending to understand the air-mixing phenomena. The model clearly reflects the gas slippage tendencies observed when varying the process conditions such as rotation frequency, gas flow and the flow if inert gas in the two sectors dividing the air and fuel side of the reactor. Based on the results, it is believed that significant improvements can be made to reduce gas mixing in future modified and scaled-up reactor versions

  18. Removal of personal care compounds from sewage sludge in reed bed container (lysimeter) studies--effects of macrophytes.

    Science.gov (United States)

    Chen, Xijuan; Pauly, Udo; Rehfus, Stefan; Bester, Kai

    2009-10-15

    Sludge reed beds have been used for dewatering (draining and evapotranspiration) and mineralisation of sludge in Europe since 1988. Although reed beds are considered as a low cost and low contamination method in reducing volume, breaking down organic matter and increasing the density of sludge, it is not yet clear whether this enhanced biological treatment is suitable for degradation of organic micro-pollutants such as personal care products. Within this project the effect of biological sludge treatment in a reed bed on reducing the concentrations of the fragrances HHCB, AHTN, OTNE was studied as on the bactericide Triclosan. Additionally, the capacity of different macrophytes species to affect the treatment process was examined. Three different macrophyte species were compared: bulrush (Typha latifolia), reed (Phragmites australis) and reed canary grass (Phalaris arundinacea). They were planted into containers (lysimeters) with a size of 1 m x 1 m x 1 m which were filled with 20 cm gravel at the bottom and 50 cm sludge on top, into which the macrophytes were planted. During the twelve months experiment reduction of 20-30% for HHCB and AHTN, 70% for Triclosan and 70% for OTNE were determined under environmental conditions. The reduction is most likely due to degradation, since volatilization, uptake into plants and leaching are insignificant. No difference between the containers with different macrophyte species or the unplanted containers was observed. Considering the usual operation time of 10 years for reed beds, an assessment was made for the whole life time.

  19. Biodenitrification of gaseous diffusion plant aqueous wastes: stirred bed reactor

    International Nuclear Information System (INIS)

    Holland, M.E.

    1980-01-01

    Approximately 30 kilograms of nitrates per day are discarded in the raffinates (acid wastes) of the Portsmouth Gaseous Diffusion Plant's X-705 Uranium Recovery and Decontamination Facility. A biodenitrification process employing continuous-flow, stirred-bed reactors has been successfully used to remove nitrates from similar acid wastes at the Oak Ridge Y-12 Plant. Laboratory studies have been made at Portsmouth to characterize the X-705 raffinates and to test the stirred-bed biodenitrification process on such raffinates. Raffinates which had been previously characterized were pumped through continuous-flow, stirred-bed, laboratory-scale reactors. Tests were conducted over a period of 146 days and involved variations in composition, mixing requirements, and the fate of several metal ions in the raffinates. Tests results show that 20 weight percent nitrates were reduced to a target nitrate effluent concentration of 100 μg/ml with a 99.64 percent efficiency. However, the average denitrification rate achieved was only 33% of that demonstrated with the Y-12 stirred-bed system. These low rates were probably due to the toxic effects of heavy metal ions on the denitrifying bacteria. Also, most of the uranium in the raffinate feed remained in the biomass and calcite, which collected in the reactor. This could cause criticality problems. For these reasons, it was decided not to make use of the stirred-bed bioreactor at Portsmouth. Instead, the biodenitrification installation now planned will use fluidized bed columns whose performance will be the subject of a subsequent report

  20. Removal of micropollutants in Moving Bed Biofilm reactors (MBBRs)

    DEFF Research Database (Denmark)

    Torresi, Elena

    Numerous pollutants such as pharmaceuticals and personal care products are continuously released into municipal wastewater treatment plants (WWTP). Present at concentration of nano- to milligram per liter, they are defined as micropollutants. Micropollutants are only partially removed, possibly due...... compared to conventional activated sludge. In MBBRs, biofilm grow on plastic carriers kept in suspension in the reactor basin via mechanical mixing or aeration, offering a suit of benefits, amongst all comparably small footprint. Despite few existing evidences in aerobic MBBR, an in-depth understanding...

  1. Researchers solve big mysteries of pebble bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Shams, Afaque; Roelofs, Ferry; Komen, E.M.J. [Nuclear Research and Consultancy Group (NRG), Petten (Netherlands); Baglietto, Emilio [Massachusetts Institute of Technology, Cambridge, MA (United States). Dept. of Nuclear Science and Engineering; Sgro, Titus [CD-adapco, London (United Kingdom). Technical Marketing

    2014-03-15

    The PBR is one type of High Temperature Reactors, which allows high temperature work while preventing the fuel from melting (bringing huge safety margins to the reactor) and high electricity efficiency. The design is also highly scalable; a plant could be designed to be as large or small as needed, and can even be made mobile, allowing it to be used onboard a ship. In a PBR, small particles of nuclear fuel, embedded in a moderating graphite pebble, are dropped into the reactor as needed. At the bottom, the pebbles can be removed simply by opening a small hatch and letting gravity pull them down. To cool the reactor and create electricity, helium gas is pumped through the reactor to pull heat out which is then run through generators. One of the most difficult problems to deal with has been the possible appearance of local temperature hotspots within the pebble bed heating to the point of melting the graphite moderators surrounding the fuel. Obviously, constructing a reactor and experimenting to investigate this possibility is out of the question. Instead, nuclear engineers have been attempting to simulate a PBR with various CFD codes. The thermo-dynamic analysis to simulate realistic conditions in a pebble bed are described and the results are shown. (orig.)

  2. Thermal-hydraulic considerations for particle bed reactors

    Science.gov (United States)

    Benenati, R.; Araj, K. J.; Horn, F.

    In the design of particle bed reactor (PBR) cores, consideration must be given to the gas coolant channels and their configuration. Neutronics analysis provides the relative volume fractions of the component materials, but these must be arranged in such a manner as to allow proper cooling of all components by the gas flow at relatively low pressure drops. The thermal hydraulic aspects of this problem are addressed. A description of the computer model used in the analysis of the steady state condition is also included. Blowdown tests on hot particle bed fuel elements were carried out and are described.

  3. Elutriation characteristics of fine particles from bubbling fluidized bed incineration for sludge cake treatment.

    Science.gov (United States)

    Chang, Yu-Min; Chou, Chih-Mei; Su, Kuo-Tung; Hung, Chao-Yang; Wu, Chao-Hsiung

    2005-01-01

    In this study, measurements of elutriation rate were carried out in a bench scale bubbling fluidized bed incinerator, which was used to combust sludge cake. The particle size distribution and ignition loss were analyzed to study the elutriation characteristics of bubbling fluidized bed incineration. Drawn from the experimental data, the elutriation rate constant K(i)* for fine particles were obtained and correlated with parameters. It was found that most of the solid particles (about 95%) elutriated came from the fluidized medium (inorganic matters), but few came from unburned carbon particles or soot (about 5%). Finally, this paper lists a comparison of K(i)* between this study and the published prediction equations derived or studied in non-incineration modes of fluidized bed. A new and modified correlation is proposed here to estimate the elutriation rate of fine particles emitted from a bubbling fluidized bed incinerator. Primary operation variables (superficial gas velocity and incineration temperature) affecting the elutriation rate are also discussed in the paper.

  4. A new reactor concept for sludge reduction using aquatic worms

    NARCIS (Netherlands)

    Elissen, H.J.H.; Hendrickx, T.L.G.; Temmink, B.G.; Buisman, C.J.N.

    2006-01-01

    Biological waste water treatment results in the production of waste sludge. The final treatment option in The Netherlands for this waste sludge is usually incineration. A biological approach to reduce the amount of waste sludge is through predation by aquatic worms. In this paper we test the

  5. Optimization of up-flow anaerobic sludge blanket reactor for ...

    African Journals Online (AJOL)

    aghomotsegin

    2013-06-05

    Jun 5, 2013 ... sludge instead of imported commercial anaerobic granulated sludge. Over the ... biogas, granulated anaerobic sludge, industrial wastewater. ... production of methane by methanogenic bacteria. Compared with other treatment processes, USAB ... effluent collector; 8, gas outlet; 9, gas collector; 10, side-arm ...

  6. Mathematical modelling of sewage sludge incineration in a bubbling fluidised bed with special consideration for thermally-thick fuel particles.

    Science.gov (United States)

    Yang, Yao Bin; Sharifi, Vida; Swithenbank, Jim

    2008-11-01

    Fluidised bed combustor (FBC) is one of the key technologies for sewage sludge incineration. In this paper, a mathematical model is developed for the simulation of a large-scale sewage sludge incineration plant. The model assumes the bed consisting of a fast-gas phase, an emulsion phase and a fuel particle phase with specific consideration for thermally-thick fuel particles. The model further improves over previous works by taking into account throughflow inside the bubbles as well as the floating and random movement of the fuel particles inside the bed. Validation against both previous lab-scale experiments and operational data of a large-scale industrial plant was made. Calculation results indicate that combustion split between the bed and the freeboard can range from 60/40 to 90/10 depending on the fuel particle distribution across the bed height under the specific conditions. The bed performance is heavily affected by the variation in sludge moisture level. The response time to variation in feeding rate is different for different parameters, from 6 min for outlet H2O, 10 min for O2, to 34 min for bed temperature.

  7. Micropollutant removal from black water and grey water sludge in a UASB-GAC reactor.

    Science.gov (United States)

    Butkovskyi, A; Sevenou, L; Meulepas, R J W; Hernandez Leal, L; Zeeman, G; Rijnaarts, H H M

    2018-02-01

    The effect of granular activated carbon (GAC) addition on the removal of diclofenac, ibuprofen, metoprolol, galaxolide and triclosan in a up-flow anaerobic sludge blanket (UASB) reactor was studied. Prior to the reactor studies, batch experiments indicated that addition of activated carbon to UASB sludge can decrease micropollutant concentrations in both liquid phase and sludge. In continuous experiments, two UASB reactors were operated for 260 days at an HRT of 20 days, using a mixture of source separated black water and sludge from aerobic grey water treatment as influent. GAC (5.7 g per liter of reactor volume) was added to one of the reactors on day 138. No significant difference in COD removal and biogas production between reactors with and without GAC addition was observed. In the presence of GAC, fewer micropollutants were washed out with the effluent and a lower accumulation of micropollutants in sludge and particulate organic matter occurred, which is an advantage in micropollutant emission reduction from wastewater. However, the removal of micropollutants by adding GAC to a UASB reactor would require more activated carbon compared to effluent post-treatment. Additional research is needed to estimate the effect of bioregeneration on the lifetime of activated carbon in a UASB-GAC reactor.

  8. Preliminary Study of 20 MWth Experiment Power Reactor based on Pebble Bed Reactor

    Science.gov (United States)

    Irwanto, Dwi; Permana, Sidik; Pramuditya, Syeilendra

    2017-07-01

    In this study, preliminary design calculations for experimental small power reactor (20 MWt) based on Pebble Bed Reactor (PBR) are performed. PBR technology chosen due to its advantages in neutronic and safety aspects. Several important parameters, such as fissile enrichment, number of fuel passes, burnup and effective multiplication factor are taken into account in the calculation to find neutronic characteristics of the present reactor design.

  9. 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 (

  10. Fluidized bed reactor for processing particles coated with carbon

    International Nuclear Information System (INIS)

    Marschollek, M.; Simon, W.; Walter, C.

    1978-01-01

    The carbon coating of production returns of these particles first has to be removed before the heavy metal core released can be reprocessed. For reasons of criticality, removal of burnt-up particles downwards must be possible in the fluidized bed reactor even if the reactor diameter is greater than 800 mm, and the material temperatures must not exceed 650 0 C. It consists of an upper cylindrical and a lower conical part, where, according to the invention, the gas distributor heads in the conical part are situated in several planes above one another for the fluidisation and combustion gas and where they are evently distributed over the reactor crossection, so that an even flow profile is achieved over the reactor cross section. (HP) [de

  11. Improved lignin pyrolysis for phenolics production in a bubbling bed reactor--Effect of bed materials.

    Science.gov (United States)

    Li, Dongbing; Briens, Cedric; Berruti, Franco

    2015-01-01

    Lignin pyrolysis was studied in a bubbling fluidized bed reactor equipped with a fractional condensation train, using nitrogen as the fluidization gas. The effect of different bed materials (silica sand, lignin char, activated lignin char, birch bark char, and foamed glass beads) on bio-oil yield and quality was investigated for a pyrolysis temperature of 550 °C. Results how that a bed of activated lignin char is preferable to the commonly used silica sand: pyrolysis of Kraft lignin with a bed of activated lignin char not only provides a pure char product, but also a higher dry bio-oil yield (with a relative increase of 43%), lower pyrolytic water production, and better bio-oil quality. The bio-oil obtained from Kraft lignin pyrolysis with a bed of activated lignin char has a lower average molecular weight, less tar, more phenolics, and less acidity than when sand is used as bed material. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Modeling a Packed Bed Reactor Utilizing the Sabatier Process

    Science.gov (United States)

    Shah, Malay G.; Meier, Anne J.; Hintze, Paul E.

    2017-01-01

    A numerical model is being developed using Python which characterizes the conversion and temperature profiles of a packed bed reactor (PBR) that utilizes the Sabatier process; the reaction produces methane and water from carbon dioxide and hydrogen. While the specific kinetics of the Sabatier reaction on the RuAl2O3 catalyst pellets are unknown, an empirical reaction rate equation1 is used for the overall reaction. As this reaction is highly exothermic, proper thermal control is of the utmost importance to ensure maximum conversion and to avoid reactor runaway. It is therefore necessary to determine what wall temperature profile will ensure safe and efficient operation of the reactor. This wall temperature will be maintained by active thermal controls on the outer surface of the reactor. Two cylindrical PBRs are currently being tested experimentally and will be used for validation of the Python model. They are similar in design except one of them is larger and incorporates a preheat loop by feeding the reactant gas through a pipe along the center of the catalyst bed. The further complexity of adding a preheat pipe to the model to mimic the larger reactor is yet to be implemented and validated; preliminary validation is done using the smaller PBR with no reactant preheating. When mapping experimental values of the wall temperature from the smaller PBR into the Python model, a good approximation of the total conversion and temperature profile has been achieved. A separate CFD model incorporates more complex three-dimensional effects by including the solid catalyst pellets within the domain. The goal is to improve the Python model to the point where the results of other reactor geometry can be reasonably predicted relatively quickly when compared to the much more computationally expensive CFD approach. Once a reactor size is narrowed down using the Python approach, CFD will be used to generate a more thorough prediction of the reactors performance.

  13. Optimization of a packed bed reactor for liquid waste treatment

    International Nuclear Information System (INIS)

    Schmidt, C.A.; Brower, M.J.; Coogan, J.J.; Tennant, R.A.

    1993-01-01

    The authors describe an optimization study of a packed bed reactor (PBR), developed for the treatment of hazardous liquid wastes. The focus is on the destruction of trichloroethylene (TCE). The PBR technology offers many distinct advantages over other processes: simple design, high destruction rates (99.99%), low costs, ambient pressure operation, easy maintenance and scaleability. The cost effectiveness, optimal operating parameters and scaleability were determined. As a second stage of treatment, a silent discharge plasma (SDP) reactor was installed to further treat offgases from the PBR. A primary advantage of this system is closed loop operation, where exhaust gases are continuously recycled and not released into the atmosphere

  14. 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.

  15. Cleaning of porous filters in fossilized bed reactors

    International Nuclear Information System (INIS)

    Rodrigo Otero, A.; Sancho Rod, J.

    1965-01-01

    In this report are established the optimum working conditions of a filter cleaning system by blow back. For this purpose it was determined in the first place the blow back air rate necessary to have a good cleaning. The reasons for which it was not possible until now to control the pressure in a fluidized bed calcination reactor are analyzed and a criteria is established to calculate the optimum floe necessary to clean efficiently a porous by this procedures. (Author)

  16. Automated Design and Optimization of Pebble-bed Reactor Cores

    International Nuclear Information System (INIS)

    Gougar, Hans D.; Ougouag, Abderrafi M.; Terry, William K.

    2010-01-01

    We present a conceptual design approach for high-temperature gas-cooled reactors using recirculating pebble-bed cores. The design approach employs PEBBED, a reactor physics code specifically designed to solve for and analyze the asymptotic burnup state of pebble-bed reactors, in conjunction with a genetic algorithm to obtain a core that maximizes a fitness value that is a function of user-specified parameters. The uniqueness of the asymptotic core state and the small number of independent parameters that define it suggest that core geometry and fuel cycle can be efficiently optimized toward a specified objective. PEBBED exploits a novel representation of the distribution of pebbles that enables efficient coupling of the burnup and neutron diffusion solvers. With this method, even complex pebble recirculation schemes can be expressed in terms of a few parameters that are amenable to modern optimization techniques. With PEBBED, the user chooses the type and range of core physics parameters that represent the design space. A set of traits, each with acceptable and preferred values expressed by a simple fitness function, is used to evaluate the candidate reactor cores. The stochastic search algorithm automatically drives the generation of core parameters toward the optimal core as defined by the user. The optimized design can then be modeled and analyzed in greater detail using higher resolution and more computationally demanding tools to confirm the desired characteristics. For this study, the design of pebble-bed high temperature reactor concepts subjected to demanding physical constraints demonstrated the efficacy of the PEBBED algorithm.

  17. Nuclear Safeguards Considerations For The Pebble Bed Modular Reactor (PBMR)

    Energy Technology Data Exchange (ETDEWEB)

    Phillip Casey Durst; David Beddingfield; Brian Boyer; Robert Bean; Michael Collins; Michael Ehinger; David Hanks; David L. Moses; Lee Refalo

    2009-10-01

    High temperature reactors (HTRs) have been considered since the 1940s, and have been constructed and demonstrated in the United Kingdom (Dragon), United States (Peach Bottom and Fort Saint Vrain), Japan (HTTR), Germany (AVR and THTR-300), and have been the subject of conceptual studies in Russia (VGM). The attraction to these reactors is that they can use a variety of reactor fuels, including abundant thorium, which upon reprocessing of the spent fuel can produce fissile U-233. Hence, they could extend the stocks of available uranium, provided the fuel is reprocessed. Another attractive attribute is that HTRs typically operate at a much higher temperature than conventional light water reactors (LWRs), because of the use of pyrolytic carbon and silicon carbide coated (TRISO) fuel particles embedded in ceramic graphite. Rather than simply discharge most of the unused heat from the working fluid in the power plant to the environment, engineers have been designing reactors for 40 years to recover this heat and make it available for district heating or chemical conversion plants. Demonstrating high-temperature nuclear energy conversion was the purpose behind Fort Saint Vrain in the United States, THTR-300 in Germany, HTTR in Japan, and HTR-10 and HTR-PM, being built in China. This resulted in nuclear reactors at least 30% or more thermodynamically efficient than conventional LWRs, especially if the waste heat can be effectively utilized in chemical processing plants. A modern variant of high temperature reactors is the Pebble Bed Modular Reactor (PBMR). Originally developed in the United States and Germany, it is now being redesigned and marketed by the Republic of South Africa and China. The team examined historical high temperature and high temperature gas reactors (HTR and HTGR) and reviewed safeguards considerations for this reactor. The following is a preliminary report on this topic prepared under the ASA-100 Advanced Safeguards Project in support of the NNSA Next

  18. Reducing the startup time of aerobic granular sludge reactors through seeding floccular sludge with crushed aerobic granules.

    Science.gov (United States)

    Pijuan, Maite; Werner, Ursula; Yuan, Zhiguo

    2011-10-15

    One of the main challenging issues for the aerobic granular sludge technology is the long startup time when dealing with real wastewaters. This study presents a novel strategy to reduce the time required for granulation while ensuring a high level of nutrient removal. This new approach consists of seeding the reactor with a mixture of crushed aerobic granules and floccular sludge. The effectiveness of the strategy was demonstrated using abattoir wastewater, containing nitrogen and phosphorus at approximately 250 mgN/L and 30 mgP/L, respectively. Seven different mixtures of crushed granules and floccular sludge at granular sludge fractions (w/w in dry mass) of 0%, 5%, 10%, 15%, 25%, 30% and 50% were used to start eight granulation processes. The granulation time (defined as the time when the 10th percentile bacterial aggregate size is larger than 200 μm) displayed a strong dependency on the fraction of granular sludge. The shortest granulation time of 18 days was obtained with 50% crushed granules, in comparison with 133 days with 5% crushed granules. Full granulation was not achieved in the two trials without seeding with crushed granules. In contrast to the 100% floccular sludge cases, where a substantial loss of biomass occurred during granulation, the biomass concentration in all other trails did not decrease during granulation. This allowed that good nitrogen removal was maintained in all the reactors during the granulation process. However, enhanced biological phosphorus removal was achieved in only one of the eight trials. This was likely due to the temporary accumulation of nitrite, a strong inhibitor of polyphosphate accumulating organisms. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Greenhouse gas emissions from the mineralisation process in a Sludge Treatment Reed Bed system: Seasonal variation and environmental impact

    DEFF Research Database (Denmark)

    Larsen, Julie Dam; Nielsen, Steen; Scheutz, Charlotte

    2017-01-01

    Greenhouse gas emission data from the mineralisation process in Sludge Treatment Reed Bed systems (STRB) are scarce. The aim of this study was to quantify the emission rates of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) and to investigate seasonal variations in order to estimate ...

  20. Mineral and chemical composition of mine wastes of Markusovce sludge bed; Mineralne a chemicke zlozenie banskych odpadov odkaliska Markusovce

    Energy Technology Data Exchange (ETDEWEB)

    Radkova, A; Volekova, B [Univerzita Komenskeho v Bratislave, Prirodovedecka fakulta, Katedra mineralogie a petrologie, 84215 Bratislava (Slovakia)

    2012-04-25

    Identification of minerals occurring in sludge bed material allows to assess the extent of migration of elements in the actual body of the sludge bed. It provides important information on the potential environmental pollution as well as on possible contamination of groundwater by potentially toxic elements. In Markusovce sludge bed there is saved about 9.9 million tons of waste material after flotation treatment of barytes - siderite-sulphide ore. Currently, the sludge bed is being extracted again due to the high content of barite. Concentrations of potentially toxic elements can be considered as relatively low. The most commonly occurring minerals in the samples are siderite and quartz, with minor rates are represented muscovite and dolomite. The content of barite increases towards the depth, which may be due to imperfect ore processing technology during the early stages of mining. Hematite is abundantly presented in the heavy fraction of the samples. The sulphide content is generally low, pyrite, chalcopyrite, tetrahedrite and cinnabar are most frequently presented. Monitored potentially toxic elements are mainly bounded to the primary sulfide minerals that are poorly oxidized. (authors)

  1. 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.

  2. Immobilization Patterns and Dynamics of Acetate-Utilizing Methanogens Immobilized in Sterile Granular Sludge in Upflow Anaerobic Sludge Blanket Reactors

    Science.gov (United States)

    Schmidt, Jens Ejbye; Ahring, Birgitte Kjær

    1999-01-01

    Sterile granular sludge was inoculated with either Methanosarcina mazeii S-6, Methanosaeta concilii GP-6, or both species in acetate-fed upflow anaerobic sludge blanket (UASB) reactors to investigate the immobilization patterns and dynamics of aceticlastic methanogens in granular sludge. After several months of reactor operation, the methanogens were immobilized, either separately or together. The fastest immobilization was observed in the reactor containing M. mazeii S-6. The highest effluent concentration of acetate was observed in the reactor with only M. mazeii S-6 immobilized, while the lowest effluent concentration of acetate was observed in the reactor where both types of methanogens were immobilized together. No changes were observed in the kinetic parameters (Ks and μmax) of immobilized M. concilii GP-6 or M. mazeii S-6 compared with suspended cultures, indicating that immobilization does not affect the growth kinetics of these methanogens. An enzyme-linked immunosorbent assay using polyclonal antibodies against either M. concilii GP-6 or M. mazeii S-6 showed significant variations in the two methanogenic populations in the different reactors. Polyclonal antibodies were further used to study the spatial distribution of the two methanogens. M. concilii GP-6 was immobilized only on existing support material without any specific pattern. M. mazeii S-6, however, showed a different immobilization pattern: large clumps were formed when the concentration of acetate was high, but where the acetate concentration was low this strain was immobilized on support material as single cells or small clumps. The data clearly show that the two aceticlastic methanogens immobilize differently in UASB systems, depending on the conditions found throughout the UASB reactor. PMID:10049862

  3. Biogas recirculation for simultaneous calcium removal and biogas purification within an expanded granular sludge bed system treating leachate.

    Science.gov (United States)

    Luo, Jinghuan; Lu, Xueqin; Liu, Jianyong; Qian, Guangren; Lu, Yongsheng

    2014-12-01

    Biogas, generated from an expanded granular sludge bed (EGSB) reactor treating municipal solid waste (MSW) leachate, was recirculated for calcium removal from the leachate via a carbonation process with simultaneous biogas purification. Batch trials were performed to optimize the solution pH and imported biogas (CO2) for CaCO3 precipitation. With applicable pH of 10-11 obtained, continuous trials achieved final calcium concentrations of 181-375 mg/L (removal efficiencies≈92.8-96.5%) in the leachate and methane contents of 87.1-91.4% (purification efficiencies≈65.4-82.2%) in the biogas. Calcium-balance study indicates that 23-986 mg Ca/d was released from the bio-system under the carbonized condition where CaCO3 precipitating was moved outside the bioreactor, whereas 7918-9517 mg Ca/d was trapped into the system for the controlled one. These findings demonstrate that carbonation removal of calcium by biogas recirculation could be a promising alternative to pretreat calcium-rich MSW leachate and synergistically to improve methane content. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Tightly Coupled Multiphysics Algorithm for Pebble Bed Reactors

    International Nuclear Information System (INIS)

    Park, HyeongKae; Knoll, Dana; Gaston, Derek; Martineau, Richard

    2010-01-01

    We have developed a tightly coupled multiphysics simulation tool for the pebble-bed reactor (PBR) concept, a type of Very High-Temperature gas-cooled Reactor (VHTR). The simulation tool, PRONGHORN, takes advantages of the Multiphysics Object-Oriented Simulation Environment library, and is capable of solving multidimensional thermal-fluid and neutronics problems implicitly with a Newton-based approach. Expensive Jacobian matrix formation is alleviated via the Jacobian-free Newton-Krylov method, and physics-based preconditioning is applied to minimize Krylov iterations. Motivation for the work is provided via analysis and numerical experiments on simpler multiphysics reactor models. We then provide detail of the physical models and numerical methods in PRONGHORN. Finally, PRONGHORN's algorithmic capability is demonstrated on a number of PBR test cases.

  5. Reduction of excess sludge production in sequencing batch reactor through incorporation of chlorine dioxide oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Wang Guanghua [Ministry of Education Key Laboratory of Pollution Control and Ecological Remediation for Industrial Agglomeration area, College of Environmental Science and Engineering, South China University of Technology, Guangzhou, 510006 (China); Guangzhou municipal engineering design and research institute, Guangzhou, 510060 (China); Sui Jun [Guangzhou municipal engineering design and research institute, Guangzhou, 510060 (China); Shen Huishan; Liang Shukun [Ministry of Education Key Laboratory of Pollution Control and Ecological Remediation for Industrial Agglomeration area, College of Environmental Science and Engineering, South China University of Technology, Guangzhou, 510006 (China); He Xiangming; Zhang Minju; Xie Yizhong; Li Lingyun [Nanhai Limited Liability Development Company, Foshan, 528200 (China); Hu Yongyou, E-mail: ppyyhu@scut.edu.cn [Ministry of Education Key Laboratory of Pollution Control and Ecological Remediation for Industrial Agglomeration area, College of Environmental Science and Engineering, South China University of Technology, Guangzhou, 510006 (China) and State Key Lab of Pulp and Paper Engineering, College of Light Industry and Food Science, South China University of Technology; Guangzhou, 510640 (China)

    2011-08-15

    In this study, chlorine dioxide (ClO{sub 2}) instead of chlorine (Cl{sub 2}) was proposed to minimize the formation of chlorine-based by-products and was incorporated into a sequencing batch reactor (SBR) for excess sludge reduction. The results showed that the sludge disintegrability of ClO{sub 2} was excellent. The waste activated sludge at an initial concentration of 15 g MLSS/L was rapidly reduced by 36% using ClO{sub 2} doses of 10 mg ClO{sub 2}/g dry sludge which was much lower than that obtained using Cl{sub 2} based on similar sludge reduction efficiency. Maximum sludge disintegration was achieved at 10 mg ClO{sub 2}/g dry sludge for 40 min. ClO{sub 2} oxidation can be successfully incorporated into a SBR for excess sludge reduction without significantly harming the bioreactor performance. The incorporation of ClO{sub 2} oxidation resulted in a 58% reduction in excess sludge production, and the quality of the effluent was not significantly affected.

  6. Reduction of excess sludge production in sequencing batch reactor through incorporation of chlorine dioxide oxidation

    International Nuclear Information System (INIS)

    Wang Guanghua; Sui Jun; Shen Huishan; Liang Shukun; He Xiangming; Zhang Minju; Xie Yizhong; Li Lingyun; Hu Yongyou

    2011-01-01

    In this study, chlorine dioxide (ClO 2 ) instead of chlorine (Cl 2 ) was proposed to minimize the formation of chlorine-based by-products and was incorporated into a sequencing batch reactor (SBR) for excess sludge reduction. The results showed that the sludge disintegrability of ClO 2 was excellent. The waste activated sludge at an initial concentration of 15 g MLSS/L was rapidly reduced by 36% using ClO 2 doses of 10 mg ClO 2 /g dry sludge which was much lower than that obtained using Cl 2 based on similar sludge reduction efficiency. Maximum sludge disintegration was achieved at 10 mg ClO 2 /g dry sludge for 40 min. ClO 2 oxidation can be successfully incorporated into a SBR for excess sludge reduction without significantly harming the bioreactor performance. The incorporation of ClO 2 oxidation resulted in a 58% reduction in excess sludge production, and the quality of the effluent was not significantly affected.

  7. Pellet bed reactor for nuclear thermal propelled vehicles

    International Nuclear Information System (INIS)

    El-Genk, M.; Morley, N.J.; Haloulakos, V.E.

    1991-01-01

    The Pellet Bed Reactor (PeBR) concept is capable of operating at a high power density of up to 3.0 kWt/cu cm and an exit hydrogen gas temperature of 3000 K. The nominal reactor thermal power is 1500 MW and the reactor core is 0.80 m in diameter and 1.3 m high. The nominal PeBR engine generates a thrust of approximately 315 kN at a specific impulse of 1000 s for a mission duration to Mars of 250 days requiring a total firing time of 170 minutes. Because of its low diameter-to-height ratio, PeBR has enough surface area for passive removal of the decay heat from the reactor core. The reactor is equipped with two independent shutdown mechanisms; 8-B4C safety rods and 26 BeO/B4C control drums; each system is capable of operating and scraming the reactor safely. Due to the absence of core internal support structures, the PeBR can be fueled and refueled in orbit using the vacuum of space. These unique features of the PeBR provide for safety during launch, simplicity of handling, deployment, and end-of-life disposal, and vehicle extended lifetime. 11 refs

  8. Comparison of some characteristics of aerobic granules and sludge flocs from sequencing batch reactors.

    Science.gov (United States)

    Li, J; Garny, K; Neu, T; He, M; Lindenblatt, C; Horn, H

    2007-01-01

    Physical, chemical and biological characteristics were investigated for aerobic granules and sludge flocs from three laboratory-scale sequencing batch reactors (SBRs). One reactor was operated as normal SBR (N-SBR) and two reactors were operated as granular SBRs (G-SBR1 and G-SBR2). G-SBR1 was inoculated with activated sludge and G-SBR2 with granules from the municipal wastewater plant in Garching (Germany). The following major parameters and functions were measured and compared between the three reactors: morphology, settling velocity, specific gravity (SG), sludge volume index (SVI), specific oxygen uptake rate (SOUR), distribution of the volume fraction of extracellular polymeric substances (EPS) and bacteria, organic carbon and nitrogen removal. Compared with sludge flocs, granular sludge had excellent settling properties, good solid-liquid separation, high biomass concentration, simultaneous nitrification and denitrification. Aerobic granular sludge does not have a higher microbial activity and there are some problems including higher effluent suspended solids, lower ratio of VSS/SS and no nitrification at the beginning of cultivation. Measurement with CLSM and additional image analysis showed that EPS glycoconjugates build one main fraction inside the granules. The aerobic granules from G-SBR1 prove to be heavier, smaller and have a higher microbial activity compared with G-SBR2. Furthermore, the granules were more compact, with lower SVI and less filamentous bacteria.

  9. Micropollutant removal from black water and grey water sludge in a UASB-GAC reactor

    NARCIS (Netherlands)

    Butkovskyi, A.; Sevenou, L.; Meulepas, R.J.W.; Hernandez Leal, L.; Zeeman, G.; Rijnaarts, H.H.M.

    2018-01-01

    The effect of granular activated carbon (GAC) addition on the removal of diclofenac, ibuprofen, metoprolol, galaxolide and triclosan in a up-flow anaerobic sludge blanket (UASB) reactor was studied. Prior to the reactor studies, batch experiments indicated that addition of activated carbon to UASB

  10. Start-up and bacterial community compositions of partial nitrification in moving bed biofilm reactor.

    Science.gov (United States)

    Liu, Tao; Mao, Yan-Jun; Shi, Yan-Ping; Quan, Xie

    2017-03-01

    Partial nitrification (PN) has been considered as one of the promising processes for pretreatment of ammonium-rich wastewater. In this study, a kind of novel carriers with enhanced hydrophilicity and electrophilicity was implemented in a moving bed biofilm reactor (MBBR) to start up PN process. Results indicated that biofilm formation rate was higher on modified carriers. In comparison with the reactor filled with traditional carriers (start-up period of 21 days), it took only 14 days to start up PN successfully with ammonia removal efficiency and nitrite accumulation rate of 90 and 91%, respectively, in the reactor filled with modified carriers. Evident changes of spatial distributions and community structures had been detected during the start-up. Free-floating cells existed in planktonic sludge, while these microorganisms trended to form flocs in the biofilm. High-throughput pyrosequencing results indicated that Nitrosomonas was the predominant ammonia-oxidizing bacterium (AOB) in the PN system, while Comamonas might also play a vital role for nitrogen oxidation. Additionally, some other bacteria such as Ferruginibacter, Ottowia, Saprospiraceae, and Rhizobacter were selected to establish stable footholds. This study would be potentially significant for better understanding the microbial features and developing efficient strategies accordingly for MBBR-based PN operation.

  11. Thermal-hydraulic modeling of porous bed reactors

    International Nuclear Information System (INIS)

    Araj, K.J.; Nourbakhsh, H.P.

    1987-01-01

    Optimum design of nuclear reactor cores requires an iterative approach between the thermal-hydraulic, neutronic, and operational analysis. This paper will concentrate on the thermal-hydraulic behavior of a hydrogen-cooled small particle bed reactor (PBR). The PBR core modeled here consists of a hexagonal array of fuel elements embedded in a moderator matrix. The fuel elements are annular packed beds of fuel particles held between two porous cylindrical frits. These particles, 500 to 600 μm in diameter, have a uranium carbide core, which is coated by two layers of graphite and an outer coating of zirconium carbide. Coolant flows, radially inward, from the cold frit through the packed bed and hot frit and axially out the channel, formed by the hot frit to a common plenum. A fast running one-dimensional lumped-parameter steady-state code (FTHP) was developed to evaluate the effects of design changes in fuel assembly and power distribution. Another objective for the code was to investigate various methods of coolant control to minimize hot channel effects and maximize outlet temperatures

  12. Thermal hydraulic and neutronic interaction in the rotating bed reactor

    International Nuclear Information System (INIS)

    Lee, C.C.

    1986-01-01

    Power transient characteristics in a rotating fluidized bed reactor (RBR) are investigated theoretically. A propellant flow perturbation is assumed to occur in an initially equilibrium state of the core. Transfer functions representing quasi-one-dimensional mutual feedback between thermal hydraulics and neutronics are developed and analyzed in the frequency domain. Neutronic responses are determined by Fermi-age theory for slowing down of fast neutrons and diffusion theory for thermal neutron distribution. Neutron leakage through the exhaust nozzle is accounted for by applying diffuse view factors similar to those applied in radiative heat transfer. The bed expansion behavior is described by a kinematic wave equation derived from the continuity of the gas phase. The drift flux approach is used to determine the yield fractions in the equilibrium bed. Thermal responses of fuel are evaluated by dividing it into several volume-averaged zones to better account for the transient effects over single zone models. Sample calculations are undertaken for the various operation conditions and design parameters of the RBR based on 250 MW/sub t/, 1000 MW/sub t/, and 5000 MW/sub t/ power reactors. The results show that power transients are dependent on the parametric changes of optical thickness and view factors

  13. Gas reactor international cooperative program interim report. Pebble bed reactor fuel cycle evaluation

    International Nuclear Information System (INIS)

    1978-09-01

    Nuclear fuel cycles were evaluated for the Pebble Bed Gas Cooled Reactor under development in the Federal Republic of Germany. The basic fuel cycle specified for the HTR-K and PNP is well qualified and will meet the requirements of these reactors. Twenty alternate fuel cycles are described, including high-conversion cycles, net-breeding cycles, and proliferation-resistant cycles. High-conversion cycles, which have a high probability of being successfully developed, promise a significant improvement in resource utilization. Proliferation-resistant cycles, also with a high probability of successful development, compare very favorably with those for other types of reactors. Most of the advanced cycles could be adapted to first-generation pebble bed reactors with no significant modifications

  14. 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

  15. Aquatic worm reactor for improved sludge processing and resource recovery

    NARCIS (Netherlands)

    Hendrickx, T.L.G.

    2009-01-01

    Municipal waste water treatment is mainly achieved by biological processes. These processes produce huge volumes of waste sludge (up 1.5 million m3/year in the Netherlands). Further processing of the waste sludge involves transportation, thickening and incineration. A decrease in the amount of waste

  16. Pellet bed reactor for nuclear propelled vehicles: Part 1: Reactor technology

    Science.gov (United States)

    El-Genk, Mohamed S.

    1991-01-01

    The pellet bed reactor (PBR) for nuclear propelled vehicles is briefly discussed. Much of the information is given in viewgraph form. Viewgraphs include information on the layout for a Mars mission using a PBR nuclear thermal rocket, the rocket reactor layout, the fuel pellet design, materials compatibility, fuel microspheres, microsphere coating, melting points in quasibinary systems, stress analysis of microspheres, safety features, and advantages of the PBR concept.

  17. Pellet bed reactor for nuclear propelled vehicles: Part 1: Reactor technology

    International Nuclear Information System (INIS)

    El-genk, M.S.

    1991-01-01

    The pellet bed reactor (PBR) for nuclear propelled vehicles is briefly discussed. Much of the information is given in viewgraph form. Viewgraphs include information on the layout for a Mars mission using a PBR nuclear thermal rocket, the rocket reactor layout, the fuel pellet design, materials compatibility, fuel microspheres, microsphere coating, melting points in quasibinary systems, stress analysis of microspheres, safety features, and advantages of the PBR concept

  18. PERKEMBANGAN BIOFILM NITRIFIKASI DI FIXED BED REACTOR PADA SALINITAS TINGGI

    Directory of Open Access Journals (Sweden)

    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.

  19. Treatment of sludge containing nitro-aromatic compounds in reed-bed mesocosms – Water, BOD, carbon and nutrient removal

    International Nuclear Information System (INIS)

    Gustavsson, L.; Engwall, M.

    2012-01-01

    Highlights: ► It is necessary to improve existing and develop new sludge management techniques. ► One method is dewatering and biodegradation of compounds in constructed wetlands. ► The result showed high reduction of all tested parameters after treatment. ► Plants improve degradation and Phragmites australis is tolerant to xenobiotics. ► The amount of sludge could be reduced by 50–70%. - Abstract: Since the mid-1970s, Sweden has been depositing 1 million ton d.w sludge/year, produced at waste water treatment plants. Due to recent legislation this practice is no longer a viable method of waste management. It is necessary to improve existing and develop new sludge management techniques and one promising alternative is the dewatering and treatment of sludge in constructed wetlands. The aim of this study was to follow reduction of organic carbon, BOD and nutrients in an industrial sludge containing nitro-aromatic compounds passing through constructed small-scale wetlands, and to investigate any toxic effect such as growth inhibition of the common reed Phragmites australis. The result showed high reduction of all tested parameters in all the outgoing water samples, which shows that constructed wetlands are suitable for carbon and nutrient removal. The results also showed that P. australis is tolerant to xenobiotics and did not appear to be affected by the toxic compounds in the sludge. The sludge residual on the top of the beds contained low levels of organic carbon and is considered non-organic and could therefore be landfilled. Using this type of secondary treatment method, the amount of sludge could be reduced by 50–70%, mainly by dewatering and biodegradation of organic compounds.

  20. 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.

  1. Hydrodynamic Studies on a Trickle Bed Reactor for Foaming Liquids

    Directory of Open Access Journals (Sweden)

    Renu Gupta

    2010-10-01

    Full Text Available Hydrodynamic studies of trickle bed reactors (TBRs are essential for the design and prediction of their performance. The hydrodynamic characteristics involving pressure drop and dynamic liquid saturation are greatly affected by the physical properties of the liquids. In the present study experiments have been carried out in a concurrent downflow air - liquid trickle bed reactor to investigate the dynamic liquid saturation and pressure drop for the water (non-foaming and 3% polyethylene glycol and 4% polyethylene glycol foaming liquids in the gas continuous regime (GCF and foaming pulsing regime (FP. In the GCF regime the dynamic liquid saturation was found to increase with increase in liquid flow rate for non-foaming and foaming liquids. While for 3% and 4% polyethylene glycol solutions the severe foaming was observed in the high interaction regime and the regime is referred to as foaming pulsing (FP regime. The decrease in dynamic liquid saturation followed by a sharp rise in the pressure drop was observed during transition from gas GCF to FP regime. However in the FP regime, a dip in the dynamic liquid saturation was observed. The pressure drop for foaming liquids is observed to be manifolds higher compared to non-foaming liquid in the GCF regime. ©2010 BCREC UNDIP. All rights reserved(Received: 16th January 2010, Revised: 10th February 2010, Accepted: 21st Feberuary 2010[How to Cite: R. Gupta, A. Bansal. (2010. Hydrodynamic Studies on a Trickle Bed Reactor for Foaming Liquids. Bulletin of Chemical Reaction Engineering & Catalysis, 5 (1: 31-37. doi:10.9767/bcrec.5.1.7127.31-37][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.5.1.7127.31-37 || or local:  http://ejournal.undip.ac.id/index.php/bcrec/article/view/7127][Cited by: Scopus 1 | ] 

  2. Hydrodynamic Studies on a Trickle Bed Reactor for Foaming Liquids

    Directory of Open Access Journals (Sweden)

    Ajay Bansal

    2010-10-01

    Full Text Available Hydrodynamic studies of trickle bed reactors (TBRs are essential for the design and prediction of their performance. The hydrodynamic characteristics involving pressure drop and dynamic liquid saturation are greatly affected by the physical properties of the liquids. In the present study experiments have been carried out in a concurrent downflow air - liquid trickle bed reactor to investigate the dynamic liquid saturation and pressure drop for the water (non-foaming and 3% polyethylene glycol and 4% polyethylene glycol foaming liquids in the gas continuous regime (GCF and foaming pulsing regime (FP. In the GCF regime the dynamic liquid saturation was found to increase with increase in liquid flow rate for non-foaming and foaming liquids. While for 3% and 4% polyethylene glycol solutions the severe foaming was observed in the high interaction regime and the regime is referred to as foaming pulsing (FP regime. The decrease in dynamic liquid saturation followed by a sharp rise in the pressure drop was observed during transition from gas GCF to FP regime. However in the FP regime, a dip in the dynamic liquid saturation was observed. The pressure drop for foaming liquids is observed to be manifolds higher compared to non-foaming liquid in the GCF regime. ©2010 BCREC UNDIP. All rights reserved(Received: 16th January 2010, Revised: 10th February 2010, Accepted: 21st Feberuary 2010[How to Cite: R. Gupta, A. Bansal. (2010. Hydrodynamic Studies on a Trickle Bed Reactor for Foaming Liquids. Bulletin of Chemical Reaction Engineering & Catalysis, 5 (1: 31-37. doi:10.9767/bcrec.5.1.775.31-37][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.5.1.775.31-37 ][Cited by: Scopus 1 |

  3. 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.

  4. Safety aspects of Particle Bed Reactor plutonium burner system

    International Nuclear Information System (INIS)

    Powell, J.R.; Ludewig, H.; Todosow, M.

    1993-01-01

    An assessment is made of the safety aspects peculiar to using the Particle Bed Reactor (PBR) as the burner in a plutonium disposal system. It is found that a combination of the graphitic fuel, high power density possible with the PBR and engineered design features results in an attractive concept. The high power density potentially makes it possible to complete the plutonium burning without requiring reprocessing and remanufacturing fuel. This possibility removes two hazardous steps from a plutonium burning complex. Finally, two backup cooling systems depending on thermo-electric converters and heat pipes act as ultimate heat removal sinks in the event of accident scenarios which result in loss of fuel cooling

  5. Modeling stationary and dynamic pebbles in a pebble bed reactor

    International Nuclear Information System (INIS)

    Zhao, Xiang; Montgomery, Trent; Zhang, Sijun

    2011-01-01

    This paper presents a numerical study of the stationary and dynamic pebbles in a pebble bed reactor (PBR) by means of discrete element method (DEM). At first, the packing structure of stationary pebbles is simulated by filling process until the settling of pebbles into PBR. The packing structural properties are obtained and analyzed. Subsequently, when the outlet of PBR is open during the operational maintenance of PBR, the stationary pebbles start to flow downward and are removed at the bottom of PBR. The dynamic behavior of pebbles is predicted and discussed. Our results indicate the DEM can offer both macroscopic and microscopic information for PBR design calculations and safety assessment. (author)

  6. Critical Issues for Particle-Bed Reactor Fuels

    Science.gov (United States)

    Evans, Robert S.; Husser, Dewayne L.; Jensen, Russell R.; Kerr, John M.

    1994-07-01

    Particle-Bed Reactors (PBRs) potentially offer performance advantages for nuclear thermal propulsion, including very high power densities, thrust-to-weight ratios, and specific impulses. A key factor in achieving all of these is the development of a very-high-temperature fuel. The critical issues for all such PBR fuels are uranium loading, thermomechanical and thermochemical stability, compatibility with contacting materials, fission product retention, manufacturability, and operational tolerance for particle failures. Each issue is discussed with respect to its importance to PBR operation, its status among current fuels, and additional development needs. Mixed-carbide-based fuels are recommended for further development to support high-performance PBRs.

  7. Glucose isomerization in simulated moving bed reactor by Glucose isomerase

    Directory of Open Access Journals (Sweden)

    Eduardo Alberto Borges da Silva

    2006-05-01

    Full Text Available Studies were carried out on the production of high-fructose syrup by Simulated Moving Bed (SMB technology. A mathematical model and numerical methodology were used to predict the behavior and performance of the simulated moving bed reactors and to verify some important aspects for application of this technology in the isomerization process. The developed algorithm used the strategy that considered equivalences between simulated moving bed reactors and true moving bed reactors. The kinetic parameters of the enzymatic reaction were obtained experimentally using discontinuous reactors by the Lineweaver-Burk technique. Mass transfer effects in the reaction conversion using the immobilized enzyme glucose isomerase were investigated. In the SMB reactive system, the operational variable flow rate of feed stream was evaluated to determine its influence on system performance. Results showed that there were some flow rate values at which greater purities could be obtained.Neste trabalho a tecnologia de Leito Móvel Simulado (LMS reativo é aplicada no processo de isomerização da glicose visando à produção de xarope concentrado de frutose. É apresentada a modelagem matemática e uma metodologia numérica para predizer o comportamento e o desempenho de unidades reativas de leito móvel simulado para verificar alguns aspectos importantes para o emprego desta tecnologia no processo de isomerização. O algoritmo desenvolvido utiliza a abordagem que considera as equivalências entre as unidades reativas de leito móvel simulado e leito móvel verdadeiro. Parâmetros cinéticos da reação enzimática são obtidos experimentalmente usando reatores em batelada pela técnica Lineweaver-Burk. Efeitos da transferência de massa na conversão de reação usando a enzima imobilizada glicose isomerase são verificados. No sistema reativo de LMS, a variável operacional vazão da corrente de alimentação é avaliada para conhecer o efeito de sua influência no

  8. Safe design and operation of fluidized-bed reactors: Choice between reactor models

    NARCIS (Netherlands)

    Westerink, E.J.; Westerterp, K.R.

    1990-01-01

    For three different catalytic fluidized bed reactor models, two models presented by Werther and a model presented by van Deemter, the region of safe and unique operation for a chosen reaction system was investigated. Three reaction systems were used: the oxidation of benzene to maleic anhydride, the

  9. 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

  10. ITER: a technology test bed for a fusion reactor

    International Nuclear Information System (INIS)

    Huguet, M.; Green, B.J.

    1996-01-01

    The ITER Project aims to establish nuclear fusion as an energy source that has potential safety and environmental advantages, and to develop the technologies required for a fusion reactor. ITER is a collaborative project between the European Union, Japan, the Russian Federation and the United States of America. During the current phase of the Project, an R and D programme of about 850 million dollars is underway to develop the technologies required for ITER. This technological effort should culminate in the construction of the components and systems of the ITER machine and its auxiliaries. The main areas of technological development include the first wall and divertor technology, the blanket technology and tritium breeding, superconducting magnet technology, pulsed power technology and remote handling. ITER is a test bed and an essential step to establish the technology of future fusion reactors. Many of the ITER technologies are of potential interest to other fields and their development is expected to benefit the industries involved. (author)

  11. Pyrolysis of Softwood Carbohydrates in a Fluidized Bed Reactor

    Directory of Open Access Journals (Sweden)

    Dmitry Yu. Murzin

    2008-09-01

    Full Text Available In the present work pyrolysis of pure pine wood and softwood carbohydrates, namely cellulose and galactoglucomannan (the major hemicellulose in coniferous wood, was conducted in a batch mode operated fluidized bed reactor. Temperature ramping (5°C/min was applied to the heating until a reactor temperature of 460 °C was reached. Thereafter the temperature was kept until the release of non-condensable gases stopped. The different raw materials gave significantly different bio-oils. Levoglucosan was the dominant product in the cellulose pyrolysis oil. Acetic acid was found in the highest concentrations in both the galactoglucomannan and in the pine wood pyrolysis oils. Acetic acid is most likely formed by removal of O-acetyl groups from mannose units present in GGM structure.

  12. Pyrolysis of softwood carbohydrates in a fluidized bed reactor.

    Science.gov (United States)

    Aho, Atte; Kumar, Narendra; Eränen, Kari; Holmbom, Bjarne; Hupa, Mikko; Salmi, Tapio; Murzin, Dmitry Yu

    2008-09-01

    In the present work pyrolysis of pure pine wood and softwood carbohydrates, namely cellulose and galactoglucomannan (the major hemicellulose in coniferous wood), was conducted in a batch mode operated fluidized bed reactor. Temperature ramping (5 degrees C/min) was applied to the heating until a reactor temperature of 460 degrees C was reached. Thereafter the temperature was kept until the release of non-condensable gases stopped. The different raw materials gave significantly different bio-oils. Levoglucosan was the dominant product in the cellulose pyrolysis oil. Acetic acid was found in the highest concentrations in both the galactoglucomannan and in the pine wood pyrolysis oils. Acetic acid is most likely formed by removal of O-acetyl groups from mannose units present in GGM structure.

  13. Pebble bed reactor fuel cycle optimization using particle swarm algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Tavron, Barak, E-mail: btavron@bgu.ac.il [Planning, Development and Technology Division, Israel Electric Corporation Ltd., P.O. Box 10, Haifa 31000 (Israel); Shwageraus, Eugene, E-mail: es607@cam.ac.uk [Department of Engineering, University of Cambridge, Trumpington Street, Cambridge CB2 1PZ (United Kingdom)

    2016-10-15

    Highlights: • Particle swarm method has been developed for fuel cycle optimization of PBR reactor. • Results show uranium utilization low sensitivity to fuel and core design parameters. • Multi-zone fuel loading pattern leads to a small improvement in uranium utilization. • Thorium mixes with highly enriched uranium yields the best uranium utilization. - Abstract: Pebble bed reactors (PBR) features, such as robust thermo-mechanical fuel design and on-line continuous fueling, facilitate wide range of fuel cycle alternatives. A range off fuel pebble types, containing different amounts of fertile or fissile fuel material, may be loaded into the reactor core. Several fuel loading zones may be used since radial mixing of the pebbles was shown to be limited. This radial separation suggests the possibility to implement the “seed-blanket” concept for the utilization of fertile fuels such as thorium, and for enhancing reactor fuel utilization. In this study, the particle-swarm meta-heuristic evolutionary optimization method (PSO) has been used to find optimal fuel cycle design which yields the highest natural uranium utilization. The PSO method is known for solving efficiently complex problems with non-linear objective function, continuous or discrete parameters and complex constrains. The VSOP system of codes has been used for PBR fuel utilization calculations and MATLAB script has been used to implement the PSO algorithm. Optimization of PBR natural uranium utilization (NUU) has been carried out for 3000 MWth High Temperature Reactor design (HTR) operating on the Once Trough Then Out (OTTO) fuel management scheme, and for 400 MWth Pebble Bed Modular Reactor (PBMR) operating on the multi-pass (MEDUL) fuel management scheme. Results showed only a modest improvement in the NUU (<5%) over reference designs. Investigation of thorium fuel cases showed that the use of HEU in combination with thorium results in the most favorable reactor performance in terms of

  14. Pebble bed reactor fuel cycle optimization using particle swarm algorithm

    International Nuclear Information System (INIS)

    Tavron, Barak; Shwageraus, Eugene

    2016-01-01

    Highlights: • Particle swarm method has been developed for fuel cycle optimization of PBR reactor. • Results show uranium utilization low sensitivity to fuel and core design parameters. • Multi-zone fuel loading pattern leads to a small improvement in uranium utilization. • Thorium mixes with highly enriched uranium yields the best uranium utilization. - Abstract: Pebble bed reactors (PBR) features, such as robust thermo-mechanical fuel design and on-line continuous fueling, facilitate wide range of fuel cycle alternatives. A range off fuel pebble types, containing different amounts of fertile or fissile fuel material, may be loaded into the reactor core. Several fuel loading zones may be used since radial mixing of the pebbles was shown to be limited. This radial separation suggests the possibility to implement the “seed-blanket” concept for the utilization of fertile fuels such as thorium, and for enhancing reactor fuel utilization. In this study, the particle-swarm meta-heuristic evolutionary optimization method (PSO) has been used to find optimal fuel cycle design which yields the highest natural uranium utilization. The PSO method is known for solving efficiently complex problems with non-linear objective function, continuous or discrete parameters and complex constrains. The VSOP system of codes has been used for PBR fuel utilization calculations and MATLAB script has been used to implement the PSO algorithm. Optimization of PBR natural uranium utilization (NUU) has been carried out for 3000 MWth High Temperature Reactor design (HTR) operating on the Once Trough Then Out (OTTO) fuel management scheme, and for 400 MWth Pebble Bed Modular Reactor (PBMR) operating on the multi-pass (MEDUL) fuel management scheme. Results showed only a modest improvement in the NUU (<5%) over reference designs. Investigation of thorium fuel cases showed that the use of HEU in combination with thorium results in the most favorable reactor performance in terms of

  15. Anaerobic biodegradability and treatment of grey water in upflow anaerobic sludge blanket (UASB) reactor.

    Science.gov (United States)

    Elmitwalli, Tarek A; Otterpohl, Ralf

    2007-03-01

    Feasibility of grey water treatment in an upflow anaerobic sludge blanket (UASB) reactor operated at different hydraulic retention time (HRT) of 16, 10 and 6h and controlled temperature of 30 degrees C was investigated. Moreover, the maximum anaerobic biodegradability without inoculum addition and maximum removal of chemical oxygen demand (COD) fractions in grey water were determined in batch experiments. High values of maximum anaerobic biodegradability (76%) and maximum COD removal in the UASB reactor (84%) were achieved. The results showed that the colloidal COD had the highest maximum anaerobic biodegradability (86%) and the suspended and dissolved COD had similar maximum anaerobic biodegradability of 70%. Furthermore, the results of the UASB reactor demonstrated that a total COD removal of 52-64% was obtained at HRT between 6 and 16 h. The UASB reactor removed 22-30% and 15-21% of total nitrogen and total phosphorous in the grey water, respectively, mainly due to the removal of particulate nutrients. The characteristics of the sludge in the UASB reactor confirmed that the reactor had a stable performance. The minimum sludge residence time and the maximum specific methanogenic activity of the sludge ranged between 27 and 93 days and 0.18 and 0.28 kg COD/(kg VS d).

  16. KMT moving bed biofilm reactor (KMT MBBR) experience of a pilot plant in Spain. Proceso KMT de biomasa fija sobre lecho movil. Experiencias en planta piloto en Espaa

    Energy Technology Data Exchange (ETDEWEB)

    Montoya Aranda, A.; Rodrigo Alonso, J.C.

    1994-01-01

    It describes the experiments carried out by INFILCO ESPAOLA, S.A. in a pilot plant using the KMT Moving Bed Biofilm Reactor process involving a fixed biomass on a moveable bed. This is an innovative process for treating both industrial and urban waste waters with or without the elimination of nutrients. The experimental findings demonstrate the need for a minimum amount of space for the biologial reagent (in comparison with that required for active sludge EDARs). They also show the ease with which existing EDARs can be adapted with very little civil engineering work by increasing either the design capacity or the elimination of nutrients. 10 refs.

  17. Biological perchlorate reduction in packed bed reactors using elemental sulfur.

    Science.gov (United States)

    Sahu, Ashish K; Conneely, Teresa; Nüsslein, Klaus R; Ergas, Sarina J

    2009-06-15

    Sulfur-utilizing perchlorate (ClO4-)-reducing bacteria were enriched from a denitrifying wastewater seed with elemental sulfur (S0) as an electron donor. The enrichment was composed of a diverse microbial community, with the majority identified as members of the phylum Proteobacteria. Cultures were inoculated into bench-scale packed bed reactors (PBR) with S0 and crushed oyster shell packing media. High ClO4-concentrations (5-8 mg/L) were reduced to PBR performance decreased when effluent recirculation was applied or when smaller S0 particle sizes were used, indicating that mass transfer of ClO4- to the attached biofilm was not the limiting mechanism in this process, and that biofilm acclimation and growth were key factors in overall reactor performance. The presence of nitrate (6.5 mg N/L) inhibited ClO4- reduction. The microbial community composition was found to change with ClO4- availability from a majority of Beta-Proteobacteria near the influent end of the reactor to primarily sulfur-oxidizing bacteria near the effluent end of the reactor.

  18. Studies on air ingress for pebble bed reactors

    International Nuclear Information System (INIS)

    Moore, R.L.; Oh, C.H.; Merrill, B.J.; Petti, D.A.

    2002-01-01

    A loss-of-coolant accident (LOCA) has been considered a critical event for helium-cooled pebbled bed reactors. Following helium depressurization, it is anticipated that unless countermeasures are taken air will enter the core through the break and then by molecular diffusion and ultimately by natural convection leading to oxidation of the in-core graphite structure and graphite pebbles. Thus, without any mitigating features a LOCA will lead to an air ingress event. The INEEL is studying such an event with two well-respected light water reactor transient response codes: RELAP5/ATHENA and MELCOR. To study the degree of graphite oxidation occurring due to an air ingress event, a MELCOR model of a reference pebble bed design was constructed. A modified version of MELCOR developed at INEEL, which includes graphite oxidation capabilities, and molecular diffusion of air into helium was used for these calculations. Results show that the lower reflector graphite consumes all of the oxygen before reaching the core. The results also show a long time delay between the time that the depressurization phase of the accident is over and the time that natural circulation air through the core occurs. (author)

  19. Coal-char combustion in a fluidised bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Mehrotra, S.P.; Pande, M. [Indian Institute of Technolgy, Kanpur (India)

    2001-12-01

    Combustion of bituminous coal chars ranging from 0.8 mm to 1.8 mm has been studied in a fluidised bed reactor at temperatures ranging from 500 to 850{sup o}C. The fluidised bed consists of inert sand particles of average size of 0.5 mm and reactive coal char particles. A heat balance has been worked out to calculate the rate of combustion of char from measured incremental changes in the bed temperature during combustion. Investigations on partially burnt particles suggest that the ash layer which builds up around the burning core of char particles is non-flaking and the particles burn in a shrinking core manner. Analysis of rate data indicates that the rate of combustion is controlled by chemical reaction kinetics, though diffusion of oxygen through the bundary layer begins to influence the overall reaction kinetics at higher temperatures. The burnt out time varies linearly with particle size. Activation energy for the chemical reaction control regime is found to be around 68 kJ/mole.

  20. Performance of a system with full- and pilot-scale sludge drying reed bed units treating septic tank sludge in Brazil.

    Science.gov (United States)

    Calderón-Vallejo, Luisa Fernanda; Andrade, Cynthia Franco; Manjate, Elias Sete; Madera-Parra, Carlos Arturo; von Sperling, Marcos

    2015-01-01

    This study investigated the performance of sludge drying reed beds (SDRB) at full- and pilot-scale treating sludge from septic tanks in the city of Belo Horizonte, Brazil. The treatment units, planted with Cynodon spp., were based on an adaptation of the first-stage of the French vertical-flow constructed wetland, originally developed for treating sewage. Two different operational phases were investigated; in the first one, the full-scale unit was used together with six pilot-scale columns in order to test different feeding strategies. For the second phase, only the full-scale unit was used, including a recirculation of the filtered effluent (percolate) to one of the units of the French vertical wetland. Sludge application was done once a week emptying a full truck, during 25 weeks. The sludge was predominantly diluted, leading to low solids loading rates (median values of 18 kgTS m(-2) year(-1)). Chemical oxygen demand removal efficiency in the full-scale unit was reasonable (median of 71%), but the total solids removal was only moderate (median of 44%) in the full-scale unit without recirculation. Recirculation did not bring substantial improvements in the overall performance. The other loading conditions implemented in the pilot columns also did not show statistically different performances.

  1. State of the art of the fluidized bed nuclear reactor concept

    International Nuclear Information System (INIS)

    Sefidvash, F.; Vilhena, M.T.M.B. de; Streck, E.; Borges, V.; Johansson, M.

    1987-01-01

    A small and simple nuclear reactors with inherent safety using the fluidized bed concept is under research and study. In this paper a brief study neutronics and thermal hydraulics of this reactor concept is presented. (Author) [pt

  2. Aerobic Sludge Granulation in a Full-Scale Sequencing Batch Reactor

    Directory of Open Access Journals (Sweden)

    Jun Li

    2014-01-01

    Full Text Available Aerobic granulation of activated sludge was successfully achieved in a full-scale sequencing batch reactor (SBR with 50,000 m3 d−1 for treating a town’s wastewater. After operation for 337 days, in this full-scale SBR, aerobic granules with an average SVI30 of 47.1 mL g−1, diameter of 0.5 mm, and settling velocity of 42 m h−1 were obtained. Compared to an anaerobic/oxic plug flow (A/O reactor and an oxidation ditch (OD being operated in this wastewater treatment plant, the sludge from full-scale SBR has more compact structure and excellent settling ability. Denaturing gradient gel electrophoresis (DGGE analysis indicated that Flavobacterium sp., uncultured beta proteobacterium, uncultured Aquabacterium sp., and uncultured Leptothrix sp. were just dominant in SBR, whereas uncultured bacteroidetes were only found in A/O and OD. Three kinds of sludge had a high content of protein in extracellular polymeric substances (EPS. X-ray fluorescence (XRF analysis revealed that metal ions and some inorganics from raw wastewater precipitated in sludge acted as core to enhance granulation. Raw wastewater characteristics had a positive effect on the granule formation, but the SBR mode operating with periodic feast-famine, shorter settling time, and no return sludge pump played a crucial role in aerobic sludge granulation.

  3. [Formation Mechanism of Aerobic Granular Sludge and Removal Efficiencies in Integrated ABR-CSTR Reactor].

    Science.gov (United States)

    Wu, Kai-cheng; Wu, Peng; Xu, Yue-zhong; Li, Yue-han; Shen, Yao-liang

    2015-08-01

    Anaerobic Baffled Reactor (ABR) was altered to make an integrated anaerobic-aerobic reactor. The research investigated the mechanism of aerobic sludge granulation, under the condition of continuous-flow. The last two compartments of the ABR were altered into aeration tank and sedimentation tank respectively with seeded sludge of anaerobic granular sludge in anaerobic zone and conventional activated sludge in aerobic zone. The HRT was gradually decreased in sedimentation tank from 2.0 h to 0.75 h and organic loading rate was increased from 1.5 kg x (M3 x d)(-1) to 2.0 kg x (M3 x d)(-1) while the C/N of 2 was controlled in aerobic zone. When the system operated for 110 days, the mature granular sludge in aerobic zone were characterized by compact structure, excellent sedimentation performance (average sedimentation rate was 20.8 m x h(-1)) and slight yellow color. The system performed well in nitrogen and phosphorus removal under the conditions of setting time of 0.75 h and organic loading rate of 2.0 kg (m3 x d)(-1) in aerobic zone, the removal efficiencies of COD, NH4+ -N, TP and TN were 90%, 80%, 65% and 45%, respectively. The results showed that the increasing selection pressure and the high organic loading rate were the main propulsions of the aerobic sludge granulation.

  4. Preliminary Neutronic Design of High Burnup OTTO Cycle Pebble Bed Reactor

    OpenAIRE

    Setiadipura, T; Irwanto, D; Zuhair, Zuhair

    2015-01-01

    The pebble bed type High Temperature Gas-cooled Reactor (HTGR) is among the interesting nuclear reactor designs in terms of safety and flexibility for co-generation applications. In addition, the strong inherent safety characteristics of the pebble bed reactor (PBR) which is based on natural mechanisms improve the simplicity of the PBR design, in particular for the Once-Through-Then-Out (OTTO) cycle PBR design. One of the important challenges of the OTTO cycle PBR design, and nuclear reactor ...

  5. Co-firing of oil sludge with coal-water slurry in an industrial internal circulating fluidized bed boiler.

    Science.gov (United States)

    Liu, Jianguo; Jiang, Xiumin; Zhou, Lingsheng; Wang, Hui; Han, Xiangxin

    2009-08-15

    Incineration has been proven to be an alternative for disposal of sludge with its unique characteristics to minimize the volume and recover energy. In this paper, a new fluidized bed (FB) incineration system for treating oil sludge is presented. Co-firing of oil sludge with coal-water slurry (CWS) was investigated in the new incineration system to study combustion characteristics, gaseous pollutant emissions and ash management. The study results show the co-firing of oil sludge with CWS in FB has good operating characteristic. CWS as an auxiliary fuel can flexibly control the dense bed temperatures by adjusting its feeding rate. All emissions met the local environmental requirements. The CO emission was less than 1 ppm or essentially zero; the emissions of SO(2) and NO(x) were 120-220 and 120-160 mg/Nm(3), respectively. The heavy metal analyses of the bottom ash and the fly ash by ICP/AES show that the combustion ashes could be recycled as soil for farming.

  6. 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)

  7. Semi-dry flue gas desulfurization using Ca(OH)2 in a fluidized bed reactor with bed materials

    International Nuclear Information System (INIS)

    Park, Young Oak; Roh, Hak Jae; Oh, Chang Sup; Kim, Yong Ha

    2010-01-01

    The main objective of present work is to reduce sulfur dioxide emission from power plant for the environment protection. The fluidized bed (FB) was used as the reactor with bed materials in a new semi-dry flue gas desulfurization (FGD) process to achieve high desulfurization efficiency (>98%). Fine powder of Ca(OH) 2 as sorbent and water were continuously fed separately to the bed reactor where bed materials (2 mm glass beads) were fluidized vigorously with flue gas (flow 720 Nm 3 / hr) using bench scale plant of stainless steel column. We have investigated different effects of water injection flow rate, Ca/ S molar ratio and weight of bed materials on SO 2 removal. The increments in the Ca/ S molar ratio and water injection flow rate have been resulted higher desulfurization efficiency with certain disadvantages such as higher sorbent cost and lower temperature of the treated flue gas, respectively. (author)

  8. Risk-informed design of a pebble bed gas reactor

    International Nuclear Information System (INIS)

    Ritterbusch, Stanley; Dimitrijevic, Vesna; Simic Zdenko; Savkina Marina

    2003-01-01

    One of the major challenges to the successful deployment of new nuclear plants in the United States is the regulatory process, which is largely based on water-reactor design technology and operating experience. While ongoing and expected efforts to license new LWR designs are based primarily on current regulations, guidance, and past experience, the pre-application review of the gas-cooled Pebble Bed Modular Reactor (PBMR) has shown that efforts are being made to provide additional 'risk-informed' improvements to the licensing process. These improvements are aimed at resolving new design and regulatory issues using a plant-wide integrated evaluation method - state-of-the-art Probabilistic Risk Assessment - which addresses all significant design features and operating modes. The integrated PRA evaluation is supported by the usual deterministic design analyses, engineering judgments, and margins added to address uncertainties (i.e., defense-in-depth). The work performed for this paper was completed as part of the United States Department of Energy's Nuclear Energy Research Initiative. The purpose of this particular project was to develop the methods for a new 'highly risk-informed' design and regulatory process. In this work. PRA techniques were applied in order to provide an integrated and systematic analysis of the plant design, to quantify uncertainties and explicitly account for defense-in-depth features. This work concentrates on the application of the risk-informed principles to a new plant design such as the PBMR. The implementation example completed for this project included specification of the design configuration, use of the PRA to evaluate the design, and iterations to identify design changes that improve the overall level of safety and system reliability. This paper summarizes the new 'highly risk-informed' design process, the design of the PBMR, and the results obtained. These results, consistent with the known inherent safety features of a pebble-bed

  9. Mathematical modeling of a three-phase trickle bed reactor

    Directory of Open Access Journals (Sweden)

    J. D. Silva

    2012-09-01

    Full Text Available The transient behavior in a three-phase trickle bed reactor system (N2/H2O-KCl/activated carbon, 298 K, 1.01 bar was evaluated using a dynamic tracer method. The system operated with liquid and gas phases flowing downward with constant gas flow Q G = 2.50 x 10-6 m³ s-1 and the liquid phase flow (Q L varying in the range from 4.25x10-6 m³ s-1 to 0.50x10-6 m³ s-1. The evolution of the KCl concentration in the aqueous liquid phase was measured at the outlet of the reactor in response to the concentration increase at reactor inlet. A mathematical model was formulated and the solutions of the equations fitted to the measured tracer concentrations. The order of magnitude of the axial dispersion, liquid-solid mass transfer and partial wetting efficiency coefficients were estimated based on a numerical optimization procedure where the initial values of these coefficients, obtained by empirical correlations, were modified by comparing experimental and calculated tracer concentrations. The final optimized values of the coefficients were calculated by the minimization of a quadratic objective function. Three correlations were proposed to estimate the parameters values under the conditions employed. By comparing experimental and predicted tracer concentration step evolutions under different operating conditions the model was validated.

  10. Power Peaking Effect of OTTO Fuel Scheme Pebble Bed Reactor

    Science.gov (United States)

    Setiadipura, T.; Suwoto; Zuhair; Bakhri, S.; Sunaryo, G. R.

    2018-02-01

    Pebble Bed Reactor (PBR) type of Hight Temperature Gas-cooled Reactor (HTGR) is a very interesting nuclear reactor design to fulfill the growing electricity and heat demand with a superior passive safety features. Effort to introduce the PBR design to the market can be strengthen by simplifying its system with the Once-through-then-out (OTTO) cycle PBR in which the pebble fuel only pass the core once. Important challenge in the OTTO fuel scheme is the power peaking effect which limit the maximum nominal power or burnup of the design. Parametric survey is perform in this study to investigate the contribution of different design parameters to power peaking effect of OTTO cycle PBR. PEBBED code is utilized in this study to perform the equilibrium PBR core analysis for different design parameter and fuel scheme. The parameters include its core diameter, height-per-diameter (H/D), power density, and core nominal power. Results of this study show that diameter and H/D effectsare stronger compare to the power density and nominal core power. Results of this study might become an importance guidance for design optimization of OTTO fuel scheme PBR.

  11. Gas Reactor International Cooperative Program. Interim report. Safety and licensing evaluaion of German Pebble Bed Reactor concepts

    International Nuclear Information System (INIS)

    1978-09-01

    The Pebble Bed Gas Cooled Reactor, as developed in the Federal Republic of Germany, was reviewed from a United States Safety and Licensing perspective. The primary concepts considered were the steam cycle electric generating pebble bed (HTR-K) and the process heat pebble bed (PNP), although generic consideration of the direct cycle gas turbine pebble bed (HHT) was included. The study examines potential U.S. licensing issues and offers some suggestions as to required development areas

  12. An Experimental Study on Axial Temperature Distribution of Combustion of Dewatered Poultry Sludge in Fluidized bed combustor

    Directory of Open Access Journals (Sweden)

    Abbas A.H.

    2016-01-01

    Full Text Available A laboratory scale bubbling fluidized bed combustor was designed and fabricated to study the combustion of dewatered poultry sludge at different operational parameters. This paper present a study on the influence of equivalent ratio, secondary to primary air ratio and the fuel feed rate on the temperature distribution along the combustor. The equivalent ratio has been changed between 0.8 to 1.4% under poultry sludge feed rate of 10 kg/h and from 0.8 to 1 under poultry sludge feed rate of 15 kg/h. The secondary to primary air ratio was varied from 0.1 to 0.5 at 0.65 m injection height and 1.25 equivalent ratio. The results showed that these factors had a significant influence on the combustion characteristics of poultry sludge. The temperature distribution along the combustor was found to be strongly dependent on the fuel feed rate and the equivalent ratio and it increased when these two factors increased. However, the secondary air ratio increased the temperature in the lower region of the combustor while no significant effect was observed at the upper region of the combustor. The results suggested that the poultry sludge can be used as a fuel with high thermal combustor efficiency.

  13. 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.

  14. 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.

  15. Assessment of effluent turbidity in mesophilic and thermophilic sludge reactors - origin of effluent colloidal material

    NARCIS (Netherlands)

    Vogelaar, J.C.T.; Lier, van J.B.; Klapwijk, B.; Vries, M.C.; Lettinga, G.

    2002-01-01

    Two lab-scale plug flow activated sludge reactors were run in parallel for 4 months at 30 and 55°C. Research focussed on: (1) COD (chemical oxygen demand) removal, (2) effluent turbidity at both temperatures, (3) the origin of effluent colloidal material and (4) the possible role of protozoa on

  16. Thermal disposal of sewage sludges by fluidised bed combustion with low emissions of pollutants. Thermische Entsorgung kommunaler Klaerschlaemme durch schadstoffarme Verbrennung in der Wirbelschicht

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, B. (Technische Univ. Magdeburg (Germany). Inst. fuer Thermische Apparate- und Umwelttechnik, Abt. Umwelttechnik); Lindau, S. (Technische Univ. Magdeburg (Germany). Inst. fuer Thermische Apparate- und Umwelttechnik, Abt. Umwelttechnik); Busse, U. (Technische Univ. Magdeburg (Germany). Inst. fuer Thermische Apparate- und Umwelttechnik, Abt. Umwelttechnik)

    1992-04-01

    The volume of sludge from the sewage treatment represents the largest problem in the waste management in Germany recently. The thermal treatment is inevitable for the solution of the problem. The fluidised bed combustion is suitable for a very good usability of sewage sludge. Experimental investigations carried out in a stationary fluidised bed in laboratory scale. The emissions of gaseous air pollutants are influenced by the properties of the sludge and the parameters of the process. The dependence of the formation and the reactions of the pollutants from various parameters are analysed and judged. (orig.)

  17. Localization of the hot spots in a pebble bed reactor

    International Nuclear Information System (INIS)

    Chen, Leisheng; Lee, Wooram; Lee, Jaeyoung

    2016-01-01

    The pebble bed reactor (PBR) is a candidate reactor type for the very high temperature reactor (VHTR), which is one of the Generation-IV reactor types. The HTGR design concept exhibits excellent safety features due to the low power density and the large amount of graphite present in the core which gives a large thermal inertia in an accident such as loss of coolant. The conclusions are made and may contribute to a better design of a PBR core and a closer inspection of the local hot spots to avoid destruction of pebbles from happening. Thermal field of a PBR core is investigated in this study. Specifically, experiments on measuring the pebbles' surface temperature are performed. It is found that the upper pebble has an overall higher temperature profile than the other pebbles and the stagnation zone under does not increase its surface's temperature. In addition, the temperature profile of the side pebble shows a concave form and it keeps decreasing from the contact point to the vertex in the lower pebble. Lastly, the maximum temperature difference among these points is 5.83 deg. C. These findings above are validated by CFX simulations under two different turbulence models (k-e, SST) and two contact areas (diameter of 6mm and 3.5mm). By contrasting the temperature variation trends of all simulation cases, it is concluded that SST turbulence model with 20% intensity shows a better agreement with the experiment result, nevertheless, slightly deviation is also found in terms of total temperature difference and the peak appears in position 17-19 in experiments

  18. Localization of the hot spots in a pebble bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Leisheng; Lee, Wooram; Lee, Jaeyoung [Handong Global University, Pohang (Korea, Republic of)

    2016-05-15

    The pebble bed reactor (PBR) is a candidate reactor type for the very high temperature reactor (VHTR), which is one of the Generation-IV reactor types. The HTGR design concept exhibits excellent safety features due to the low power density and the large amount of graphite present in the core which gives a large thermal inertia in an accident such as loss of coolant. The conclusions are made and may contribute to a better design of a PBR core and a closer inspection of the local hot spots to avoid destruction of pebbles from happening. Thermal field of a PBR core is investigated in this study. Specifically, experiments on measuring the pebbles' surface temperature are performed. It is found that the upper pebble has an overall higher temperature profile than the other pebbles and the stagnation zone under does not increase its surface's temperature. In addition, the temperature profile of the side pebble shows a concave form and it keeps decreasing from the contact point to the vertex in the lower pebble. Lastly, the maximum temperature difference among these points is 5.83 deg. C. These findings above are validated by CFX simulations under two different turbulence models (k-e, SST) and two contact areas (diameter of 6mm and 3.5mm). By contrasting the temperature variation trends of all simulation cases, it is concluded that SST turbulence model with 20% intensity shows a better agreement with the experiment result, nevertheless, slightly deviation is also found in terms of total temperature difference and the peak appears in position 17-19 in experiments.

  19. Spectral zone selection methodology for pebble bed reactors

    International Nuclear Information System (INIS)

    Mphahlele, Ramatsemela; Ougouag, Abderrafi M.; Ivanov, Kostadin N.; Gougar, Hans D.

    2011-01-01

    A methodology is developed for determining boundaries of spectral zones for pebble bed reactors. A spectral zone is defined as a region made up of a number of nodes whose characteristics are collectively similar and that are assigned the same few-group diffusion constants. The spectral zones are selected in such a manner that the difference (error) between the reference transport solution and the diffusion code solution takes a minimum value. This is achieved by choosing spectral zones through optimally minimizing this error. The objective function for the optimization algorithm is the total reaction rate error, which is defined as the sum of the leakage, absorption and fission reaction rates errors in each zone. The selection of these spectral zones is such that the core calculation results based on diffusion theory are within an acceptable tolerance as compared to a proper transport reference solution. Through this work, a consistent approach for identifying spectral zones that yield more accurate diffusion results is introduced.

  20. Pebble bed reactor with one-zone core

    International Nuclear Information System (INIS)

    Mueller-Frank, U.; Lohnert, G.

    1977-01-01

    The claim deals with measures to differentiate the flow rate and to remove spherical fuel elements in the core of a pebble bed reactor. Hence the vertical rate of the fuel elements in the border region is for example twice as much as in the centre. A central funnel-shaped outlet on the floor of the core container over which a conical body is placed with its peak pointing upwards, or also the forming of several outlets can be used to adjust to a certain exit rate for the fuel elements. The main target of the invention is a radially extensively constant coolant outlet temperature at the outlet of the core which determines the effectiveness of the connected heat exchanger and thus contributes to economy. (UA) [de

  1. Modeling stationary and moving pebbles in a pebble bed reactor

    International Nuclear Information System (INIS)

    Zhao, Xiang; Montgomery, Trent; Zhang, Sijun

    2015-01-01

    Highlights: • The stationary and moving pebbles in a PBR are numerically studied by DEM. • The packing structure of stationary pebbles is simulated by a filling process. • The packing structural properties are obtained and analyzed. • The dynamic behavior of pebbles is predicted and discussed. - Abstract: This paper presents a numerical study of the stationary and moving pebbles in a pebble bed reactor (PBR) by means of discrete element method (DEM). The packing structure of stationary pebbles is simulated by a filling process that terminates with the settling of the pebbles into a PBR. The packing structural properties are obtained and analyzed. Subsequently, when the outlet of the PBR is opened during the operation of the PBR, the stationary pebbles start to flow downward and are removed at the bottom of the PBR. The dynamic behavior of pebbles is predicted and discussed. Our results indicate the DEM can offer both macroscopic and microscopic information for PBR design calculations and safety assessment

  2. Continuous thermophilic biohydrogen production in packed bed reactor

    International Nuclear Information System (INIS)

    Roy, Shantonu; Vishnuvardhan, M.; Das, Debabrata

    2014-01-01

    Highlights: • Continuous H 2 production in whole cell immobilized system was compared with CSTR. • Suitability of environment friendly support matrix for immobilization of whole cells was explored. • Pack bed reactor showed higher stability as compared to CSTR at lower HRTs. • Flow cytometry study showed the influence of recycle ratio on viability of cells. • Novel approach to find out the effect of NADH/NAD + ratio during H 2 production. - Abstract: The present research work deals with the performance of packed bed reactor for continuous H 2 production using cane molasses as a carbon source. Maximum H 2 production rate of 1.7 L L −1 h −1 was observed at a dilution rate and recycle ratio of 0.8 h −1 and 0.6, respectively which was corresponding to the lowest NADH/NAD + ratio. This suggests that the utilization of NADH pool for H 2 and metabolite production might lead to decrement in NADH/NAD + ratio. Thus NADH/NAD + ratio show inverse relation with hydrogen production. The substrate degradation kinetics was investigated as a function of flow rate considering the external film diffusion model. At a flow rate of 245 mL h −1 , the contribution of external film mass transfer coefficient and first order substrate degradation constant were 55.4% and 44.6% respectively. Recycle ratio of 0.6 improved the hydrogen production rates by 9%. The viable cell count was directly proportional to the recycle ratio (within the range 0.1–0.6). Taguchi design showed the significant influence of the feed pH on continuous H 2 production followed by dilution rate and recycle ratio. Thus environmentally friendly and cheaper solid matrix like coconut coir could be efficiently used for thermophilic continuous hydrogen production

  3. Thermofluid effect on energy storage in fluidized bed reactor

    Science.gov (United States)

    Mahfoudi, Nadjiba; El Ganaoui, Mohammed; Moummi, Abdelhafid

    2016-05-01

    The development of innovative systems of heat storage is imperative to improve the efficiency of the existing systems used in the thermal solar energy applications. Several techniques were developed and realized in this context. The technology of the sand fluidized bed (sandTES) offers a promising alternative to the current state-of-the-art of the heat storage systems, such as fixed bed using a storage materials, as sand, ceramic, and stones, etc. Indeed, the use of the fluidization technique allows an effective heat transfer to the solid particles. With the sand, an important capacity of storage is obtained by an economic and ecological material [N. Mahfoudi, A. Moummi, M. El Ganaoui, Appl. Mech. Mater. 621, 214 (2014); N. Mahfoudi, A. Khachkouch, A. Moummi B. Benhaoua, M. El Ganaoui, Mech. Ind. 16, 411 (2015); N. Mahfoudi, A. Moummi, M. El Ganaoui, F. Mnasri, K.M. Aboudou, 3e Colloque internationale Francophone d"énergétique et mécanique, Comores, 2014, p. 91]. This paper presents a CFD simulation of the hydrodynamics and the thermal transient behavior of a fluidized bed reactor of sand, to determine the characteristics of storage. The simulation shows a symmetry breaking that occurs and gave way to chaotic transient generation of bubble formation after 3 s. Furthermore, the predicted average temperature of the solid phase (sand) increases gradually versus the time with a gain of 1 °C in an interval of 10 s. Contribution to the topical issue "Materials for Energy Harvesting, Conversion and Storage (ICOME 2015) - Elected submissions", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui

  4. Pebble bed blanket design for deuterium burning tandem mirror reactors

    International Nuclear Information System (INIS)

    Grotz, S.P.; Dhir, V.K.

    1983-01-01

    The UCLA tandem mirror reactor, SATYR, was developed around the capability of tandem mirrors with thermal barriers to burn deuterium at reasonable efficiency levels. The pebble bed concept has been incorporated into our blanket design for the following reasons: 1) Large area-to-volume ratio for purposes of heat removal; 2) Large volume of structure for high thermal capacity thus increasing the safety margin during off-normal incidents; 3) Relatively inexpensive manufacturing costs because of large acceptable tolerances and lack of exotic materials (i.e., lithium). A simplified stress analysis of the blanket module was performed to optimize and simplify the design. The pre-specified stress intensity limitations used were based upon a 30-year predicted lifetime for each module. Along with stress analysis of the vessel a detailed thermal hydraulic analysis of the pebble bed has been completed. Parameters affecting the pebble bed design are fluidization velocity, pressure drop, heat transfer coefficient, thermally induced stress in the spheres and spatial variation of the power density. Although reasonable gross thermal efficiencies of the 2 designs has been achieved (28% for H 2 O and 39% for He) the high net recirculating power fraction for heating and neutral beams results in relatively low net plant efficiencies (21% and 27%). The results show that a blanket can be designed with good thermal efficiency and a relative-ly simple configuration. However, application of this concept to the high Q deuterium-tritium fuel cycle would have difficulties resulting from the need for continuous removal of the tritium. (orig./HP)

  5. Emissions of CO2 and CH4 from sludge treatment reed beds depend on system management and sludge loading

    DEFF Research Database (Denmark)

    Olsson, Linda; Dam Larsen, Julie; Ye, Siyuan

    2014-01-01

    , the SD had no vegetation and a poor dewatering capacity, which resulted in anaerobic conditions favoring CH4 emission. In contrast, the well-managed STRB had more aerobic conditions in the sludge residue resulting in low CH4 emission rates. We conclude that well-designed and well-managed STRBs have a low...

  6. Sludge accumulation in shallow maturation ponds treating UASB reactor effluent: results after 11 years of operation.

    Science.gov (United States)

    Possmoser-Nascimento, Thiago Emanuel; Rodrigues, Valéria Antônia Justino; von Sperling, Marcos; Vasel, Jean-Luc

    2014-01-01

    Polishing ponds are natural systems used for the post-treatment of upflow anaerobic sludge blanket (UASB) effluents. They are designed as maturation ponds and their main goal is the removal of pathogens and nitrogen and an additional removal of residual organic matter from the UASB reactor. This study aimed to evaluate organic matter and suspended solids removal as well as sludge accumulation in two shallow polishing ponds in series treating sanitary effluent from a UASB reactor with a population equivalent of 200 inhabitants in Brazil, operating since 2002. For this evaluation, long-term monitoring of biochemical oxygen demand and total suspended solids and bathymetric surveys have been undertaken. The ponds showed an irregular distribution of total solids mass in the sludge layer of the two ponds, with mean accumulation values of 0.020 m(3) person(-1) year(-1) and 0.004 m(3) person(-1) year(-1) in Ponds 1 and 2, leading to around 40% and 8% of the liquid volume occupied by the sediments after 11 years of operation. The first pond showed better efficiency in relation to organic matter removal, although its contribution was limited, due to algal growth. No simple input-output mass balance of solids can be applied to the ponds due to algal growth in the liquid phase and sludge digestion in the sludge.

  7. [Research on Cultivation and Stability of Nitritation Granular Sludge in Integrated ABR-CSTR Reactor].

    Science.gov (United States)

    Wu, Kai-cheng; Wu, Peng; Shen, Yao-liang; Li, Yue-han; Wang, Han-fang; Xu, Yue-zhong

    2015-11-01

    Abstract: The last two compartments of the Anaerobic Baffled Readtor ( ABR) were altered into aeration tank and sedimentation tank respectively to get an integrated anaerobic-aerobic reactor, using anaerobic granular sludge in anaerobic zone and aerobic granular sludge in aerobic zone as seed sludge. The research explored the condition to cultivate nitritation granular sludge, under the condition of continuous flow. The C/N rate was decreased from 1 to 0.4 and the ammonia nitrogen volumetric loading rate was increased from 0.89 kg x ( m3 x d)(-1) to 2.23 kg x (m3 x d)(-1) while the setting time of 1 h was controlled in the aerobic zone. After the system was operated for 45 days, the mature nitritation granular sludge in aerobic zone showed a compact structure and yellow color while the nitrite accumulation rate was about 80% in the effluent. The associated inhibition of free ammonia (FA) and free nitrous acid (FNA) dominated the nitritation. Part of granules lost stability during the initial period of operation and flocs appeared in the aerobic zone. However, the flocs were transformed into newly generated small particles in the following reactor operation, demonstrating that organic carbon was benefit to granulation and the enrichment of slow-growing nitrifying played an important role in the stability of granules.

  8. Advanced modularity design for the MIT pebble bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kadak, Andrew C. [Department of Nuclear Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, 24-202 Cambridge, MA 02139-4307 (United States)]. E-mail: kadak@mit.edu; Berte, Marc V. [Department of Nuclear Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, 24-202 Cambridge, MA 02139-4307 (United States)]. E-mail: mvberte@yahoo.com

    2006-03-15

    The future of all reactors will depend on whether they can be economically built and operated. One of the major impediments to new nuclear construction is the capital cost due in large part to the length of construction time and complexity of the plant. Pebble bed reactors offer the opportunity to reduce the complexity of the plant because the number of safety systems required is significantly reduced due to the inherent safety of the technology. However, because of its small size, the capital cost per kilowatt is likely to be large if traditional construction approaches are followed. This strongly suggests the need for innovative construction concepts to reduce the construction time and cost. MIT has proposed a modularity approach in which the plant is pre-built in space-frame type modules which are built in factories. These space frames would contain all the equipment contained in a given volume. Once equipment in the space frame is installed, the space frame would then be shipped to the site and assembled 'lego-style.' Studies presently underway have demonstrated the feasibility of the concept. Thermal stress analysis has been performed and an integrated design with the space frames has been developed. It is expected that this modularity approach will significantly shorten construction time and expense. This paper proposes a concept for further development, not a final design for the entire plant.

  9. Advanced modularity design for the MIT pebble bed reactor

    International Nuclear Information System (INIS)

    Kadak, Andrew C.; Berte, Marc V.

    2006-01-01

    The future of all reactors will depend on whether they can be economically built and operated. One of the major impediments to new nuclear construction is the capital cost due in large part to the length of construction time and complexity of the plant. Pebble bed reactors offer the opportunity to reduce the complexity of the plant because the number of safety systems required is significantly reduced due to the inherent safety of the technology. However, because of its small size, the capital cost per kilowatt is likely to be large if traditional construction approaches are followed. This strongly suggests the need for innovative construction concepts to reduce the construction time and cost. MIT has proposed a modularity approach in which the plant is pre-built in space-frame type modules which are built in factories. These space frames would contain all the equipment contained in a given volume. Once equipment in the space frame is installed, the space frame would then be shipped to the site and assembled 'lego-style.' Studies presently underway have demonstrated the feasibility of the concept. Thermal stress analysis has been performed and an integrated design with the space frames has been developed. It is expected that this modularity approach will significantly shorten construction time and expense. This paper proposes a concept for further development, not a final design for the entire plant

  10. Transmutation of plutonium in pebble bed type high temperature reactors

    International Nuclear Information System (INIS)

    Bende, E.E.

    1997-01-01

    The pebble bed type High Temperature Reactor (HTR) has been studied as a uranium-free burner of reactor grade plutonium. In a parametric study, the plutonium loading per pebble as well as the type and size of the coated particles (CPs) have been varied to determine the plutonium consumption, the final plutonium burnup, the k ∞ and the temperature coefficients as a function of burnup. The plutonium loading per pebble is bounded between 1 and 3 gr Pu per pebble. The upper limit is imposed by the maximal allowable fast fluence for the CPs. A higher plutonium loading requires a longer irradiation time to reach a desired burnup, so that the CPs are exposed to a higher fast fluence. The lower limit is determined by the temperature coefficients, which become less negative with increasing moderator-actinide ratio. A burnup of about 600 MWd/kgHM can be reached. With the HTR's high efficiency of 40%, a plutonium supply of 1520 kg/GW e a is achieved. The discharges of plutonium and minor actinides are then 450 and 110 kg/GW e a, respectively. (author)

  11. 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.

  12. Design and simulation of an activated sludge unit associated to a continuous reactor to remove heavy metals

    Energy Technology Data Exchange (ETDEWEB)

    D`Avila, J.S.; Nascimento, R.R. [Ambientec Consultoria Ltda., Aracaju, SE (Brazil)

    1993-12-31

    A software was developed to design and simulate an activated sludge unit associated to a new technology to remove heavy metals from wastewater. In this process, a continuous high efficiency biphasic reactor operates by using particles of activated peat in conjugation with the sludge unit. The results obtained may be useful to increase the efficiency or to reduce the design and operational costs involved in a activated sludge unit. (author). 5 refs., 2 tabs.

  13. Design and simulation of an activated sludge unit associated to a continuous reactor to remove heavy metals

    Energy Technology Data Exchange (ETDEWEB)

    D` Avila, J S; Nascimento, R R [Ambientec Consultoria Ltda., Aracaju, SE (Brazil)

    1994-12-31

    A software was developed to design and simulate an activated sludge unit associated to a new technology to remove heavy metals from wastewater. In this process, a continuous high efficiency biphasic reactor operates by using particles of activated peat in conjugation with the sludge unit. The results obtained may be useful to increase the efficiency or to reduce the design and operational costs involved in a activated sludge unit. (author). 5 refs., 2 tabs.

  14. Anaerobic treatment of slaughterhouse waste using a flocculant sludge UASB reactor. [Upflow Anaerobic Sludge Blanket

    Energy Technology Data Exchange (ETDEWEB)

    Sayed, S.; de Zeeuw, W.; Lettinga, G.

    1984-01-01

    This study was carried out to assess the feasibility of using the upflow anaerobic sludge blanket (UASB) process for the one-step anaerobic treatment of slaughterhouse waste, which contains approximately 50% insoluble suspended COD. Batch experiments, as well as continuous experiments, were conducted. The continuous experiments were carried out in a 30 cubic m UASB pilot-plant with digested sewage sludge from the municipal sewage treatment plant of Ede, The Netherlands (Ede-2 sludge), used as seed. Initially the UASB pilot-plant was operated at a temperature of 30 degrees C, but, 20 weeks after the start-up, the temperature was reduced to 20 degrees C, because application of the process at this lower temperature might be quite attractive for economic reasons. The process can be started up at an organic space load of 1 kg COD/m/sup 3/ day (sludge load, 0.11 kg/COD kg VSSday) and at a liquid detention time of 35 h at a process temperature of 30 degrees C. Once started up, the system can satisfactorily handle organic space loads up to 3.5 kg COD/m/sup 3/ day at a liquid detention time of 8 hours at temperatures as low as 20 degrees C. A treatment efficiency up to 70% on a COD tot basis, 90% on a COD sol basis and 95% on a BOD5 sol basis was smoothly approached. Temporary shock loads up to 7 kg COD/m/sup 3/ day during the daytime at a liquid detention time of 5 h can well be accommodated provided such a shock load is followed by a period of underloading, e.g. at night. The methane yield amounted to 0.28 NM/sup 3/ per kilogram of COD removed: the methane content of the biogas from the wastewater varied between 65 and 75%. 19 references.

  15. Septage unit treatment by sludge treatment reed beds for easy management and reuse: performance and design considerations.

    Science.gov (United States)

    Kim, Boram; Bel, Thomas; Bourdoncle, Pascal; Dimare, Jocelyne; Troesch, Stéphane; Molle, Pascal

    2018-01-01

    Sustainable treatment and management of fecal sludge in rural areas require adapted solutions. Rustic and simple operating processes such as sludge treatment reed beds (STRB) have been increasingly considered for this purpose. The biggest full scale (2,600 m 2 of STRB) septage treatment unit in France had been built in Nègrepelisse with the final objectives of reusing treated sludge and leachates for agriculture spreading and tree irrigation, respectively. The aim of this investigation was to validate the treatment chain of this installation. The obtained field data showed firstly that the overall removal efficiencies of STRB were satisfactory and stable. Removal rates higher than 98% for chemical oxygen demand and suspended solids and a 95% for Kjeldahl nitrogen represented so far a beneficial septage treatment by STRB. The highlighted necessity of a suitable complementary leachate treatment (before tree irrigation) justified the presence of the second stage of vertical flow constructed wetland. The sludge deposit drying and mineralization efficiencies were on the right track. According to hydrotextural diagram analysis, surface deposit was however found to have high deformability probably due to the youth of the installation. An in-depth understanding of STRB system needs continuous long-term studies.

  16. Evaluation of sludge properties in a pilot-scale UASB reactor for sewage treatment in a temperate region.

    Science.gov (United States)

    Syutsubo, K; Yoochatchaval, W; Tsushima, I; Araki, N; Kubota, K; Onodera, T; Takahashi, M; Yamaguchi, T; Yoneyama, Y

    2011-01-01

    In this study, continuous operation of a pilot-scale upflow anaerobic sludge blanket (UASB) reactor for sewage treatment was conducted for 630 days to investigate the physical and microbial characteristics of the retained sludge. The UASB reactor with a working volume of 20.2 m(3) was operated at ambient temperature (16-29 °C) and seeded with digested sludge. After 180 days of operation, when the sewage temperature had dropped to 20 °C or lower, the removal efficiency of both total suspended solids (TSS) and total biochemical oxygen demand (BOD) deteriorated due to washout of retained sludge. At low temperature, the cellulose concentration of the UASB sludge increased owing to the rate limitation of the hydrolytic reaction of suspended solids in the sewage. However, after an improvement in sludge retention (settleability and concentration) in the UASB reactor, the process performance stabilized and gave sufficient results (68% of TSS removal, 75% of total BOD removal) at an hydraulic retention time (HRT) of 9.7 h. The methanogenic activity of the retained sludge significantly increased after day 246 due to the accumulation of Methanosaeta and Methanobacterium following the improvement in sludge retention in the UASB reactor. Acid-forming bacteria from phylum Bacteroidetes were detected at high frequency; thus, these bacteria may have an important role in suspended solids degradation.

  17. Sorption-enhanced steam methane reforming in fluidized bed reactors

    Energy Technology Data Exchange (ETDEWEB)

    Johnsen, Kim

    2006-10-15

    Hydrogen is considered to be an important potential energy carrier; however, its advantages are unlikely to be realized unless efficient means can be found to produce it without generation of CO{sub 2}. Sorption-enhanced steam methane reforming (SE-SMR) represent a novel, energy-efficient hydrogen production route with in situ CO{sub 2} capture, shifting the reforming and water gas shift reactions beyond their conventional thermodynamic limits. The use of fluidized bed reactors for SE-SMR has been investigated. Arctic dolomite, a calcium-based natural sorbent, was chosen as the primary CO{sub 2}-acceptor in this study due to high absorption capacity, relatively high reaction rate and low cost. An experimental investigation was conducted in a bubbling fluidized bed reactor of diameter 0.1 m, which was operated cyclically and batch wise, alternating between reforming/carbonation conditions and higher-temperature calcination conditions. Hydrogen concentrations of >98 mole% on a dry basis were reached at 600 C and 1 atm, for superficial gas velocities in the range of {approx}0.03-0.1 m/s. Multiple reforming-regeneration cycles showed that the hydrogen concentration remained at {approx}98 mole% after four cycles. The total production time was reduced with an increasing number of cycles due to loss of CO{sub 2}-uptake capacity of the dolomite, but the reaction rates of steam reforming and carbonation seemed to be unaffected for the conditions investigated. A modified shrinking core model was applied for deriving carbonation kinetics of Arctic dolomite, using experimental data from a novel thermo gravimetric reactor. An apparent activation energy of 32.6 kj/mole was found from parameter fitting, which is in good agreement with previous reported results. The derived rate expression was able to predict experimental conversion up to {approx}30% very well, whereas the prediction of higher conversion levels was poorer. However, the residence time of sorbent in a continuous

  18. Upflow anaerobic sludge reactors for the treatment of combined industrial effluent in subtropical conditions: a comparison between UASB and UASF reactors

    International Nuclear Information System (INIS)

    Yasar, A.; Ahmad, N.; Chaudhry, M.N.; Sarwar, M.; Masood, T.; Yaqub, A.

    2005-01-01

    The performance of anaerobic biological process is heavily process conditions dependent. In this study, an attempt has been made to investigate the influence of process conditions like temperature, sludge age and hydraulic retention time (HRT) on the efficiency of an upflow anaerobic sludge blanket (UASB) reactor and upflow anaerobic sludge filter (UASF) to treat combined industrial wastewater. Reactors were operated at easing ambient temperatures (38, 30, 20 and 14 deg. C) and correspondingly increasing sludge ages (60, 90, 120 and 150 days). At temperature 38 deg. C and sludge age of 60 days, UASF showed better performance than VASE reactor. This mainly due to the enhanced filtration through well-graded sand filter and fairly good biological activity in UASF. At this stage, lack of sludge granulation in VASE reactor resulted in poor biological activity; hence, relatively poor performance. At temperatures 30 and 20 deg. C with sludge ages of 90 and 120 days, respectively, UASB gave better results than UASF. The reason was rapid biological degradation due to proper sludge granulation and favorable temperature. At temperature 14 deg. C, a substantial decrease in the efficiency of UASB reactor as compared to the UASF was evident. Drop in efficiency was because of inhabitation of methanogenic bacteria and liquidation of sludge granules. These factors mounted to a decrease in biological activity, stoppage as production and an increase in total suspended solids (TSS) in the effluent. The influence of hydraulic retention time (ranging between 3-12 hours at an increment of 3 hours) on the removal efficiency of both UASB and UASF was not significant. At favorable temperature (20 to 30 deg. C) and sludge age (90 to 120 days) UASB reactor appeared to be more efficient than UASF.(author)

  19. Energy production from distillery wastewater using single and double-phase upflow anaerobic sludge blanket (UASB) reactor

    Energy Technology Data Exchange (ETDEWEB)

    Muyodi, F J; Rubindamayugi, M S.T. [Univ. of Dar es Salaam, Applied Microbiology Unit (Tanzania, United Republic of)

    1998-12-31

    A Single-phase (SP) and Double-phase (DP) Upflow Anaerobic Sludge Blanket (UASB) reactors treating distillery wastewater were operated in parallel. The DP UASB reactor showed better performance than the SP UASB reactor in terms of maximum methane production rate, methane content and Chemical Oxygen Demand (COD) removal efficiency. (au) 20 refs.

  20. Energy production from distillery wastewater using single and double-phase upflow anaerobic sludge blanket (UASB) reactor

    Energy Technology Data Exchange (ETDEWEB)

    Muyodi, F.J.; Rubindamayugi, M.S.T. [Univ. of Dar es Salaam, Applied Microbiology Unit (Tanzania, United Republic of)

    1997-12-31

    A Single-phase (SP) and Double-phase (DP) Upflow Anaerobic Sludge Blanket (UASB) reactors treating distillery wastewater were operated in parallel. The DP UASB reactor showed better performance than the SP UASB reactor in terms of maximum methane production rate, methane content and Chemical Oxygen Demand (COD) removal efficiency. (au) 20 refs.

  1. Nuclear safeguards considerations for pebble bed reactors (PBRs)

    International Nuclear Information System (INIS)

    Moses, David L.

    2012-01-01

    Recent reports by the Department of Energy National Laboratories have discussed safeguards considerations for low enriched uranium (LEU)-fueled pebble bed reactors (PBRs) and the need for bulk accountancy of the plutonium in “used fuel.” These reports fail to account for the degree of plutonium dilution in the graphitized-carbon pebbles that is sufficient to meet the International Atomic Energy Agency (IAEA) “provisional” guidelines for termination of safeguards on “measured discards.” The thrust of this finding is not to terminate safeguards but to limit the need for specific accountancy of plutonium in stored used fuel. While the residual uranium in the used fuel is not sufficiently diluted to meet the IAEA provisional guidelines for termination of safeguards, the estimated quantities of the uranium minor isotopes 232 U and 236 U in the used fuel at the target burnup of ∼90 Gigawatt-days per metric ton (GWD/MT) exceed standard specification limits for reprocessed uranium and will require extensive blending with either natural uranium or uranium enrichment tails to dilute the 236 U content to fall within specification. Hence, the PBR used fuel is less desirable for commercial reprocessing and reuse than that from light water reactors. Also the PBR specific activity of a reprocessed uranium isotopic mixture and its A 2 values for effective dose limits if released in a dispersible form during a transportation accident are more limiting than the equivalent values for light-water-reactor used fuel at 55 GWD/MT without accounting for the presence of the principal carry-over fission product (technetium, 99 Tc) and plutonium contamination. Thus, the potentially recoverable uranium from PBR used fuel carries reactivity penalties and radiological penalties likely greater than those for reprocessed uranium from light water reactors. These factors impact the economics of reprocessing, but a more significant consideration is that reprocessing technologies for

  2. Gas-solid hydroxyethylation of potato starch in a stirred vibrating fluidized bed reactor

    NARCIS (Netherlands)

    Kuipers, N.J M; Stamhuis, Eize; Beenackers, A.A C M

    A novel reactor for modifying cohesive C-powders such as in the gas-solid hydroxyethylation of semidry potato starch is characterized, the so-called stirred vibrating fluidized bed reactor. Good fluidization characteristics are obtained in this reactor for certain combinations of stirring and

  3. Performance of a continuously operated flocculent sludge UASB reactor with slaughterhouse wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Sayed, S.; Zeeuw, W. de

    1988-01-01

    This investigation was carried out to assess the performance of a continuously operated, one-stage, flocculent sludge upflow anaerobic sludge blanket (UASB) reactor treating slaughterhouse wastewater at a process temperature of 30/sup 0/C. The results indicate that the type of substrate ingredients, coarse suspended solids, colloidal and soluble compounds in the wastewater, affect the performance of the reactor because of different mechanisms involved in their removal and their subsequent conversion into methane. Two different mechanisms are distinguished. An entrapment mechanism prevails for the elimination of coarse suspended solids while an adsorption mechanism is involved in the removal of the colloidal and soluble fractions of the wastewater. The results obtained lead to the conclusion that the system can satisfactorily handle organic space loads up to 5 kg COD m/sup -3/ day/sup -1/ at 30/sup 0/C. The data indicate, however, that continuing heavy accumulation of substrate components in the reactor is detrimental to the stability of the anaerobic treatment process as the accumulation can lead to sludge flotation and consequently to a complete loss of the active biomass from the reactor.

  4. Fate of xenobiotic compounds and plants activity in reed bed sludge treatment

    DEFF Research Database (Denmark)

    Chen, Xijuan; Pauli, Udo; Rehfus, Stefan

    different plants: bulrush (Typha), reed (Phragmites australis) and reed canary grass (Phalaris arundinacea) were planted into 12 containers with a size of 1m Х 1m X 1m which were builded with 20cm gravel and 50cm sludge to study the plants activity in sludge degradation process, 4 containers were left...

  5. Grey water treatment in upflow anaerobic sludge blanket (UASB) reactor at different temperatures.

    Science.gov (United States)

    Elmitwalli, Tarek; Otterpohl, Ralf

    2011-01-01

    The treatment of grey water in two upflow anaerobic sludge blanket (UASB) reactors, operated at different hydraulic retention times (HRTs) and temperatures, was investigated. The first reactor (UASB-A) was operated at ambient temperature (14-25 degrees C) and HRT of 20, 12 and 8 h, while the second reactor (UASB-30) was operated at controlled temperature of 30 degrees C and HRT of 16, 10 and 6 h. The two reactors were fed with grey water from 'Flintenbreite' settlement in Luebeck, Germany. When the grey water was treated in the UASB reactor at 30 degrees C, total chemical oxygen demand (CODt) removal of 52-64% was achieved at HRT between 6 and 16 h, while at lower temperature lower removal (31-41%) was obtained at HRT between 8 and 20 h. Total nitrogen and phosphorous removal in the UASB reactors were limited (22-36 and 10-24%, respectively) at all operational conditions. The results showed that at increasing temperature or decreasing HRT of the reactors, maximum specific methanogenic activity of the sludge in the reactors improved. As the UASB reactor showed a significantly higher COD removal (31-64%) than the septic tank (11-14%) even at low temperature, it is recommended to use UASB reactor instead of septic tank (the most common system) for grey water pre-treatment. Based on the achieved results and due to high peak flow factor, a HRT between 8 and 12 h can be considered the suitable HRT for the UASB reactor treating grey water at temperature 20-30 degrees C, while a HRT of 12-24 h can be applied at temperature lower than 20 degrees C.

  6. Pebble bed modular reactor - The first Generation IV reactor to be constructed

    International Nuclear Information System (INIS)

    Ion, S.; Nicholls, D.; Matzie, R.; Matzner, D.

    2004-01-01

    Substantial interest has been generated in advanced reactors over the past few years. This interest is motivated by the view that new nuclear power reactors will be needed to provide low carbon generation of electricity and possibly hydrogen to support the future growth in demand for both of these commodities. Some governments feel that substantially different designs will be needed to satisfy the desires for public perception, improved safety, proliferation resistance, reduced waste and competitive economics. This has motivated the creation of the Generation IV Nuclear Energy Systems programme in which ten countries have agreed on a framework for international cooperation in research for advanced reactors. Six designs have been selected for continued evaluation, with the objective of deployment by 2030. One of these designs is the very high temperature reactor (VHTR), which is a thermal neutron spectrum system with a helium-cooled core utilising carbon-based fuel. The pebble bed modular reactor (PBMR), being developed in South Africa through a worldwide international collaborative effort led by Eskom, the national utility, will represent a key milestone on the way to achievement of the VHTR design objectives, but in the much nearer term. This paper outlines the design objectives, safety approach and design details of the PBMR, which is already at a very advanced stage of development. (author)

  7. Hydrolysis of cellulose in a cellulase-bead fluidized bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Karube, I; Tanaka, S; Shirai, T; Suzuki, S

    1977-08-01

    Cellulase was immobilized in a collagen fibril matrix, and no leakage of cellulase from the collagen fibril matrix was observed. The immobilized cellulase was more stable than the native cellulase. The substrate cellulose was hydrolyzed quantitatively with immobilized cellulase. The final reaction product was identified as glucose. Immobilized cellulase was used in a fluidized bed reactor where the pressure drop of the fluidized bed reactor was low and constant. Cellulose was hydrolyzed to glucose by the cellulase-bead fluidized bed reactor. The minimum flow velocity (U/sub mf/) was 0.5 cm/sec and the optimum flow velocity of the cellulose hydrolysis was 1 cm/sec.

  8. Rheology and Microbiology of Sludge from a Thermophilic Aerobic Membrane Reactor

    Directory of Open Access Journals (Sweden)

    Alessandro Abbà

    2017-01-01

    Full Text Available A thermophilic aerobic membrane reactor (TAMR treating high-strength COD liquid wastes was submitted to an integrated investigation, with the aim of characterizing the biomass and its rheological behaviour. These processes are still scarcely adopted, also because the knowledge of their biology as well as of the physical-chemical properties of the sludge needs to be improved. In this paper, samples of mixed liquor were taken from a TAMR and submitted to fluorescent in situ hybridization for the identification and quantification of main bacterial groups. Measurements were also targeted at flocs features, filamentous bacteria, and microfauna, in order to characterize the sludge. The studied rheological properties were selected as they influence significantly the performances of membrane bioreactors (MBR and, in particular, of the TAMR systems that operate under thermophilic conditions (i.e., around 50°C with high MLSS concentrations (up to 200 gTS L−1. The proper description of the rheological behaviour of sludge represents a useful and fundamental aspect that allows characterizing the hydrodynamics of sludge suspension devoted to the optimization of the related processes. Therefore, in this study, the effects on the sludge rheology produced by the biomass concentration, pH, temperature, and aeration were analysed.

  9. Anaerobic degradation of landfill leachate using an upflow anaerobic fixed-bed reactor with microbial sulfate reduction

    International Nuclear Information System (INIS)

    Ben Dhia Thabet, Olfa; Bouallagui, Hassib; Cayol, Jean-luc; Ollivier, Bernard; Fardeau, Marie-Laure; Hamdi, Moktar

    2009-01-01

    This study evaluated the anaerobic degradation of landfill leachate and sulfate reduction as a function of COD/(SO 4 2- ) ratio in an upflow anaerobic fixed-bed reactor. The reactor, which was inoculated with a mixed consortium, was operated under a constant hydraulic retention time (HRT) of 5 days. We investigated the effect of COD/(SO 4 2- ) ratio variation on the sulfate reduction efficiency, hydrogen sulfide production, chemical oxygen demand (COD) removal, conductivity, and pH variation. The best reactor performance, with significant sulfate reduction efficiency and COD removal efficiency of 91% and 87%, respectively, was reached under a COD/(SO 4 2- ) ratio of 1.17. Under these conditions, microscopic analysis showed the abundance of vibrios and rod-shaped bacterial cells. Two anaerobic bacteria were isolated from the reactor sludge. Phylogenetic studies performed on these strains identified strain A1 as affiliated to Clostridium genus and strain H1 as a new species of sulfate-reducing bacteria affiliated to the Desulfovibrio genus. The closest phylogenetic relative of strain H1 was Desulfovibrio desulfuricans, at 96% similarity for partial 16S RNA gene sequence data. Physiological and metabolic characterization was performed for this strain.

  10. Accurate evaluation for the biofilm-activated sludge reactor using graphical techniques

    Science.gov (United States)

    Fouad, Moharram; Bhargava, Renu

    2018-05-01

    A complete graphical solution is obtained for the completely mixed biofilm-activated sludge reactor (hybrid reactor). The solution consists of a series of curves deduced from the principal equations of the hybrid system after converting them in dimensionless form. The curves estimate the basic parameters of the hybrid system such as suspended biomass concentration, sludge residence time, wasted mass of sludge, and food to biomass ratio. All of these parameters can be expressed as functions of hydraulic retention time, influent substrate concentration, substrate concentration in the bulk, stagnant liquid layer thickness, and the minimum substrate concentration which can maintain the biofilm growth in addition to the basic kinetics of the activated sludge process in which all these variables are expressed in a dimensionless form. Compared to other solutions of such system these curves are simple, easy to use, and provide an accurate tool for analyzing such system based on fundamental principles. Further, these curves may be used as a quick tool to get the effect of variables change on the other parameters and the whole system.

  11. 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

  12. 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.

  13. Packed bed reactor treatment of liquid hazardous and mixed wastes

    International Nuclear Information System (INIS)

    Tennant, R.A.; Wantuck, P.J.; Vargas, R.

    1992-01-01

    We are developing thermal-based packed bed reactor (PBR) technology as an alternative to incineration for treatment of hazardous organic liquid wastes. The waste streams targeted by this technology are machining fluids contaminated with chlorocarbons and/or chlorofluorocarbons and low levels of plutonium or tritium The PBR offers several distinct advantages including simplistic design, rugged construction, ambient pressure processing, economical operations, as well as ease of scalability and maintainability. In this paper, we provide a description of the apparatus as well as test results using prepared mixtures of machining oils/emulsions with trichloroethylene (TCE), carbon tetrachloride (CCl 4 ), trichloroethane (TCA), and Freon TF. The current treatment system is configured as a two stage device with the PBR (1st stage) coupled to a silent discharge plasma (SDP) cell. The SDP serves as a second stage for further treatment of the gaseous effluent from the PBR. One of the primary advantages of this two stage system is that its suitability for closed loop operation where radioactive components are well contained and even CO 2 is not released to the environment

  14. Properties Influencing Plasma Discharges in Packed Bed Reactors

    Science.gov (United States)

    Kruszelnicki, Juliusz; Engeling, Kenneth W.; Foster, John E.; Kushner, Mark J.

    2016-09-01

    Atmospheric pressure dielectric barrier discharges (DBDs) sustained in packed bed reactors (PBRs) are being investigated for CO2 removal and conversion of waste gases into higher value compounds. We report on results of a computational investigation of PBR-DBD properties using the plasma hydrodynamics simulator nonPDPSIM with a comparison to experiments. Dielectric beads (rods in 2D) were inserted between two coplanar electrodes, 1 cm apart filled by humid air. A step-pulse of -30 kV was applied to the top electrode. Material properties of the beads (dielectric constant, secondary emission coefficient) and gas properties (photoionization and photo-absorption cross-sections, temperature) were varied. We found that photoionization plays a critical role in the propagation of the discharge through the PBR, as it serves to seed charges in regions of high electric field. Increasing rates of photo-ionization enable increases in the discharge propagation velocity, ionization rates and production of radicals. A transition between DBD-like and arc-like discharges occurs as the radiation mean free path decreases. Increasing the dielectric constant of the beads increased electric fields in the gas, which translated to increased discharge propagation velocity and charge density until ɛ/ɛ0 100. Secondary electron emission coefficient and gas temperature have minimal impacts on the discharge propagation though the latter did affect the production of reactive species. Work supported by US DOE Office of Fusion Energy Science and the National Science Foundation.

  15. Treatment of slaughterhouse wastewater in an upflow anaerobic sludge blanket reactor: Sludge characteristics

    Directory of Open Access Journals (Sweden)

    Mohammad Mehdi Amin

    2016-01-01

    Conclusion: Application of slaughterhouse wastewater as feed wastewater demonstrated that the slaughterhouse wastewater to be more effective in promoting the formation of anaerobic granules and granule size in UASB reactor.

  16. 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

  17. Gas reactor international cooperative program interim report: German Pebble Bed Reactor design and technology review

    International Nuclear Information System (INIS)

    1978-09-01

    This report describes and evaluates several gas-cooled reactor plant concepts under development within the Federal Republic of Germany (FRG). The concepts, based upon the use of a proven Pebble Bed Reactor (PBR) fuel element design, include nuclear heat generation for chemical processes and electrical power generation. Processes under consideration for the nuclear process heat plant (PNP) include hydrogasification of coal, steam gasification of coal, combined process, and long-distance chemical heat transportation. The electric plant emphasized in the report is the steam turbine cycle (HTR-K), although the gas turbine cycle (HHT) is also discussed. The study is a detailed description and evaluation of the nuclear portion of the various plants. The general conclusions are that the PBR technology is sound and that the HTR-K and PNP plant concepts appear to be achievable through appropriate continuing development programs, most of which are either under way or planned

  18. Energy potential and alternative usages of biogas and sludge from UASB reactors: case study of the Laboreaux wastewater treatment plant.

    Science.gov (United States)

    Rosa, A P; Conesa, J A; Fullana, A; Melo, G C B; Borges, J M; Chernicharo, C A L

    2016-01-01

    This work assessed the energy potential and alternative usages of biogas and sludge generated in upflow anaerobic sludge blanket reactors at the Laboreaux sewage treatment plant (STP), Brazil. Two scenarios were considered: (i) priority use of biogas for the thermal drying of dehydrated sludge and the use of the excess biogas for electricity generation in an ICE (internal combustion engine); and (ii) priority use of biogas for electricity generation and the use of the heat of the engine exhaust gases for the thermal drying of the sludge. Scenario 1 showed that the electricity generated is able to supply 22.2% of the STP power demand, but the thermal drying process enables a greater reduction or even elimination of the final volume of sludge to be disposed. In Scenario 2, the electricity generated is able to supply 57.6% of the STP power demand; however, the heat in the exhaust gases is not enough to dry the total amount of dehydrated sludge.

  19. Neutronic modeling of pebble bed reactors in APOLLO2

    International Nuclear Information System (INIS)

    Grimod, M.

    2010-01-01

    In this thesis we develop a new iterative homogenization technique for pebble bed reactors, based on a 'macro-stochastic' transport approximation in the collision probability method. A model has been developed to deal with the stochastic distribution of pebbles with different burnup in the core, considering spectral differences in homogenization and depletion calculations. This is generally not done in the codes presently used for pebble bed analyses, where a pebble with average isotopic composition is considered to perform the cell calculation. Also an iterative core calculation scheme has been set up, where the low-order RZ S N full-core calculation computes the entering currents in the spectrum zones subdividing the core. These currents, together with the core k eff , are then used as surface source in the fine-group heterogeneous calculation of the multi-pebble geometries. The developed method has been verified using reference Monte Carlo simulations of a simplified PBMR- 400 model. The pebbles in this model are individually positioned and have different randomly assigned burnup values. The APOLLO2 developed method matches the reference core k eff within ± 100 pcm, with relative differences on the production shape factors within ± 4%, and maximum discrepancy of 3% at the hotspot. Moreover, the first criticality experiment of the HTR-10 reactor was used to perform a first validation of the developed model. The computed critical number of pebbles to be loaded in the core is very close to the experimental value of 16890, only 77 pebbles less. A method to calculate the equilibrium reactor state was also developed and applied to analyze the simplified PBMR-400 model loaded with different fuel types (UO 2 , Pu, Pu + MA). The potential of the APOLLO2 method to compute different fluxes for the different pebble types of a multi-pebble geometry was used to evaluate the bias committed by the average composition pebble approximation. Thanks to a 'compensation of error

  20. 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.

  1. Microbial community variation and functions to excess sludge reduction in a novel gravel contact oxidation reactor

    Energy Technology Data Exchange (ETDEWEB)

    Lin Shanshan; Jin, Y.; Fu, L. [School of Urban and Environmental Science, Northeast Normal University, Changchun (China); Quan, C. [Jilin University, College of medicine, Changchun (China); Yang, Y.S., E-mail: yangy6@cf.ac.uk [Cardiff University, School of Earth and Ocean Sciences, Cardiff CF10 3YE (United Kingdom)

    2009-06-15

    Excess biomass produced within the degradation processes of organic pollutants is creating environmental challenges. The gravel contact oxidation reactor (GCOR) filled with crushed stone globular aggregates as carriers, has been demonstrated capable of reducing the excess sludge effectively in some pilot and small-scale engineering studies. In order to evaluate the variation and structure of the microbial community and their functions to excess sludge reduction in GCOR, a conventional activated sludge reactor (ASR) was studied as a comparison. The 16S rDNA library of the universal bacteria was constructed, Shannon's diversity index (H) and Species evenness (E) were calculated with distance-based operational taxonomic unit and richness (DOTUR) for microbial diversity. Real-time quantity PCR and optical microscope were used for absolute bacterial DNA concentration and eukarya identification, respectively. Meanwhile, the suspended solid index in GCOR and ASR was detected for assessing the excess sludge production. The results indicated that the most abundant bacteria in GCOR were those related to the {beta}-Proteobacteria group, then {gamma}-Proteobacteria and to Cytophaga-Flexibacter-Bacteriode (CFB). In the ASR samples major bacteria were in the closest match with {gamma}-Proteobacteria, then {beta}-Proteobacteria and CFB. Shannon's index (H) was higher (3.41) for diversity of bacteria extracted from the carrier samples in GCOR than that (2.71) from the sludge sample in ASR. Species evenness (E) for the isolates from GCOR and ASR samples was 0.97 and 0.96, respectively. Comparison of the universal bacteria population in GCOR and ASR shows that the total bacterial DNA concentration on the GCOR carriers were 8.98 x 10{sup 5} {mu}g/{mu}l, twice that in ASR of 4.67 x 10{sup 5} {mu}g/{mu}l under normal operation of two reactors. But the MLSS in GCOR was only 4.5 mg/L, 25 times less than that in ASR of 115.4 mg/L. The most representative eukarya were protozoa

  2. Microbial community variation and functions to excess sludge reduction in a novel gravel contact oxidation reactor

    International Nuclear Information System (INIS)

    Lin Shanshan; Jin, Y.; Fu, L.; Quan, C.; Yang, Y.S.

    2009-01-01

    Excess biomass produced within the degradation processes of organic pollutants is creating environmental challenges. The gravel contact oxidation reactor (GCOR) filled with crushed stone globular aggregates as carriers, has been demonstrated capable of reducing the excess sludge effectively in some pilot and small-scale engineering studies. In order to evaluate the variation and structure of the microbial community and their functions to excess sludge reduction in GCOR, a conventional activated sludge reactor (ASR) was studied as a comparison. The 16S rDNA library of the universal bacteria was constructed, Shannon's diversity index (H) and Species evenness (E) were calculated with distance-based operational taxonomic unit and richness (DOTUR) for microbial diversity. Real-time quantity PCR and optical microscope were used for absolute bacterial DNA concentration and eukarya identification, respectively. Meanwhile, the suspended solid index in GCOR and ASR was detected for assessing the excess sludge production. The results indicated that the most abundant bacteria in GCOR were those related to the β-Proteobacteria group, then γ-Proteobacteria and to Cytophaga-Flexibacter-Bacteriode (CFB). In the ASR samples major bacteria were in the closest match with γ-Proteobacteria, then β-Proteobacteria and CFB. Shannon's index (H) was higher (3.41) for diversity of bacteria extracted from the carrier samples in GCOR than that (2.71) from the sludge sample in ASR. Species evenness (E) for the isolates from GCOR and ASR samples was 0.97 and 0.96, respectively. Comparison of the universal bacteria population in GCOR and ASR shows that the total bacterial DNA concentration on the GCOR carriers were 8.98 x 10 5 μg/μl, twice that in ASR of 4.67 x 10 5 μg/μl under normal operation of two reactors. But the MLSS in GCOR was only 4.5 mg/L, 25 times less than that in ASR of 115.4 mg/L. The most representative eukarya were protozoa both in GCOR (15 no. per 20 ml) and in ASR (15

  3. Response of aerobic granular sludge to the long-term presence to nanosilver in sequencing batch reactors: Reactor performance, sludge property, microbial activity and community

    Energy Technology Data Exchange (ETDEWEB)

    Quan, Xiangchun, E-mail: xchquan@bnu.edu.cn; Cen, Yan; Lu, Fang; Gu, Lingyun; Ma, Jingyun

    2015-02-15

    The increasing use of silver nanoparticles (Ag NPs) raises concerns about their potential toxic effects on the environment. Granular shape sludge is a special type of microbial aggregate. The response of aerobic granular sludge (AGS) to the long-term presence of Ag NPs has not been well studied. In this study, AGS was exposed to 5 and 50 mg/L Ag NPs in sequence batch reactors (SBRs) for 69 days, and its response was evaluated based on the sludge properties, microbial activity and community, and reactor performance. The results showed that Ag NPs caused inhibition to microbial activities of AGS from Day 35. At the end of 69 days of Ag NPs exposure, the microbial activity of AGS was significantly inhibited in terms of inhibitions of the ammonia oxidizing rate (33.0%), respiration rate (17.7% and 45.6%) and denitrification rate (6.8%), as well as decreases in the ammonia mono-oxygenase and nitrate reductase activities. During the long-term exposure, the AGS maintained its granular shape and large granule size (approximately 900 μm); the microbial community of AGS slightly changed, but the dominant microbial population remained. Overall, the AGS tolerated the toxicity of Ag NPs well, but a long-term exposure may produce chronic toxicity to the AGS, which is concerning. - Highlights: • AGS demonstrated a good tolerance to the long-term presence of Ag NPs. • Ag NPs did not produce acute toxicity but cause chronic toxicity to AGS. • AGS maintained granular shape, granule size and good settling ability. • The microbial community of AGS slightly changed after long-term Ag NPs exposure.

  4. Response of aerobic granular sludge to the long-term presence to nanosilver in sequencing batch reactors: Reactor performance, sludge property, microbial activity and community

    International Nuclear Information System (INIS)

    Quan, Xiangchun; Cen, Yan; Lu, Fang; Gu, Lingyun; Ma, Jingyun

    2015-01-01

    The increasing use of silver nanoparticles (Ag NPs) raises concerns about their potential toxic effects on the environment. Granular shape sludge is a special type of microbial aggregate. The response of aerobic granular sludge (AGS) to the long-term presence of Ag NPs has not been well studied. In this study, AGS was exposed to 5 and 50 mg/L Ag NPs in sequence batch reactors (SBRs) for 69 days, and its response was evaluated based on the sludge properties, microbial activity and community, and reactor performance. The results showed that Ag NPs caused inhibition to microbial activities of AGS from Day 35. At the end of 69 days of Ag NPs exposure, the microbial activity of AGS was significantly inhibited in terms of inhibitions of the ammonia oxidizing rate (33.0%), respiration rate (17.7% and 45.6%) and denitrification rate (6.8%), as well as decreases in the ammonia mono-oxygenase and nitrate reductase activities. During the long-term exposure, the AGS maintained its granular shape and large granule size (approximately 900 μm); the microbial community of AGS slightly changed, but the dominant microbial population remained. Overall, the AGS tolerated the toxicity of Ag NPs well, but a long-term exposure may produce chronic toxicity to the AGS, which is concerning. - Highlights: • AGS demonstrated a good tolerance to the long-term presence of Ag NPs. • Ag NPs did not produce acute toxicity but cause chronic toxicity to AGS. • AGS maintained granular shape, granule size and good settling ability. • The microbial community of AGS slightly changed after long-term Ag NPs exposure

  5. Production of specific-structured lipids by enzymatic interesterification in a pilot continuous enzyme bed reactor

    DEFF Research Database (Denmark)

    Xu, Xuebing; Balchen, Steen; Høy, Carl-Erik

    1998-01-01

    Production of specific-structured lipids (interesterified lipids with a specific structure) by enzymatic interesterification was carried out in a continuous enzyme bed pilot scale reactor. Commercial immobilized lipase (Lipozyme IM) was used and investigations of acyl migration, pressure drop...

  6. 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....

  7. A novel approach for harnessing biofilm communities in moving bed biofilm reactors for industrial wastewater treatment

    OpenAIRE

    Joe A. Lemire; Marc A. Demeter; Iain George; Howard Ceri; Raymond J. Turner

    2015-01-01

    Moving bed biofilm reactors (MBBRs) are an effective biotechnology for treating industrial wastewater. Biomass retention on moving bed biofilm reactor (MBBR) carriers (biofilm support materials), allows for the ease-of-operation and high treatment capacity of MBBR systems. Optimization of MBBR systems has largely focused on aspects of carrier design, while little attention has been paid to enhancing strategies for harnessing microbial biomass. Previously, our research group demonstrated that ...

  8. Leaching and accumulation of trace elements in sulfate reducing granular sludge under concomitant thermophilic and low pH conditions

    NARCIS (Netherlands)

    Gonzalez-Gil, G.; Lopes, S.I.C.; Saikaly, P.E.; Lens, P.N.L.

    2012-01-01

    The leaching and/or accumulation of trace elements in sulfate reducing granular sludge systems was investigated. Two thermophilic up-flow anaerobic sludge bed (UASB) reactors operated at pH 5 were fed with sucrose (4 g COD l(reactor)(-1) d(-1)) and sulfate at different COD/SO42- ratios. During the

  9. Application of semifluidized bed bioreactor as novel bioreactor ...

    African Journals Online (AJOL)

    The conventional bioreactors such as pond digester, anaerobic filtration, up-flow anaerobic sludge blanket (UASB), up-flow anaerobic sludge fixed-film (UASFF), continuous stirred tank reactor (CSTR), anaerobic contact digestion and fluidized bed, used over the past decades are largely operated anaerobically. They have ...

  10. Sewage Sludge Disposal with Energy Recovery by Fluidized Bed Gasification and CHP-Units

    Energy Technology Data Exchange (ETDEWEB)

    Horst, J.; Gross, B.; Kimmerle, K. [Inst. fuer ZukunftsEnergieSysteme, Saarbruecken (Germany); Eder, C. [Christian Eder Technology e.K., Neunkirchen (Germany)

    2006-07-15

    Sewage sludge is a composition of by-products collected during the different stages of the waste water cleaning process of communal and industrial treatment plants. Because of its harmful impacts on environment as well as animals - and mankind - health sewage sludge has become a problem. Therefore disposal of sludge is today on a crossroad depending on the discussion about soil contamination by using the sludge as fertiliser. Some countries are now abandoning disposal to agriculture and are entering into thermal treatment with the argument: 'Harmful substances already separated with high financial effort should definitely be removed from the food cycle and should not return indirectly via the fields to food and water'. The SEDIS project - a project funded by the European Commission under the specific research and technological development programme 'Promotion of innovation and encouragement of SME participation' - is aimed at eliminating the rising disposal problem of sewage sludge by an energy-related use of the raw sludge directly on site of wastewater treatment plants. SEDIS is developing an innovative, self-sustaining system to process liquid and pasty waste such as sewage sludge and solid biomass to utilise product-gas for power-generation direct on site. This process is called ETVS-process and is patented by Christian Eder Technology e.K. Today, where each company has to look for sustainable savings, the SEDIS concept offers a decentralised process, self-sustaining from other energy sources and able to provide the whole treatment plant with energy. Furthermore the treatment plant would be independent of price policy of sludge disposers.

  11. Oxidation of ethene in a wall-cooled packed-bed reactor

    NARCIS (Netherlands)

    Schouten, E.P.S.; Borman, P.C.; Westerterp, K.R.

    1994-01-01

    The selective oxidation of ethene over a silver on α-alumina catalyst was studied in a pilot plant with a wall-cooled tubular packed bed reactor. Gas and solid temperatures in the catalyst bed were measured at different axial and radial positions as well as concentrations at different axial

  12. Advantages of forced non-steady operated trickle-bed reactors

    NARCIS (Netherlands)

    Boelhouwer, J.G.; Piepers, H.W.; Drinkenburg, A.A.H.

    2002-01-01

    Trickle-bed reactors are usually operated in the steady state trickle flow regime. Uneven liquid distribution and the formation of hot spots are the most serious problems experienced during trickle flow operation. In this paper, we advocate the use of non-steady state operation of trickle-bed

  13. Catalytic fast pyrolysis of white oak wood in-situ using a bubbling fluidized bed reactor

    Science.gov (United States)

    Catalytic fast pyrolysis was performed on white oak wood using two zeolite-type catalysts as bed material in a bubbling fluidized bed reactor. The two catalysts chosen, based on a previous screening study, were Ca2+ exchanged Y54 (Ca-Y54) and a proprietary ß-zeolite type catalyst (catalyst M) both ...

  14. A Single-Granule-Level Approach Reveals Ecological Heterogeneity in an Upflow Anaerobic Sludge Blanket Reactor.

    Directory of Open Access Journals (Sweden)

    Kyohei Kuroda

    Full Text Available Upflow anaerobic sludge blanket (UASB reactor has served as an effective process to treat industrial wastewater such as purified terephthalic acid (PTA wastewater. For optimal UASB performance, balanced ecological interactions between syntrophs, methanogens, and fermenters are critical. However, much of the interactions remain unclear because UASB have been studied at a "macro"-level perspective of the reactor ecosystem. In reality, such reactors are composed of a suite of granules, each forming individual micro-ecosystems treating wastewater. Thus, typical approaches may be oversimplifying the complexity of the microbial ecology and granular development. To identify critical microbial interactions at both macro- and micro- level ecosystem ecology, we perform community and network analyses on 300 PTA-degrading granules from a lab-scale UASB reactor and two full-scale reactors. Based on MiSeq-based 16S rRNA gene sequencing of individual granules, different granule-types co-exist in both full-scale reactors regardless of granule size and reactor sampling depth, suggesting that distinct microbial interactions occur in different granules throughout the reactor. In addition, we identify novel networks of syntrophic metabolic interactions in different granules, perhaps caused by distinct thermodynamic conditions. Moreover, unseen methanogenic relationships (e.g. "Candidatus Aminicenantes" and Methanosaeta are observed in UASB reactors. In total, we discover unexpected microbial interactions in granular micro-ecosystems supporting UASB ecology and treatment through a unique single-granule level approach.

  15. A Single-Granule-Level Approach Reveals Ecological Heterogeneity in an Upflow Anaerobic Sludge Blanket Reactor

    Science.gov (United States)

    Mei, Ran; Narihiro, Takashi; Bocher, Benjamin T. W.; Yamaguchi, Takashi; Liu, Wen-Tso

    2016-01-01

    Upflow anaerobic sludge blanket (UASB) reactor has served as an effective process to treat industrial wastewater such as purified terephthalic acid (PTA) wastewater. For optimal UASB performance, balanced ecological interactions between syntrophs, methanogens, and fermenters are critical. However, much of the interactions remain unclear because UASB have been studied at a “macro”-level perspective of the reactor ecosystem. In reality, such reactors are composed of a suite of granules, each forming individual micro-ecosystems treating wastewater. Thus, typical approaches may be oversimplifying the complexity of the microbial ecology and granular development. To identify critical microbial interactions at both macro- and micro- level ecosystem ecology, we perform community and network analyses on 300 PTA–degrading granules from a lab-scale UASB reactor and two full-scale reactors. Based on MiSeq-based 16S rRNA gene sequencing of individual granules, different granule-types co-exist in both full-scale reactors regardless of granule size and reactor sampling depth, suggesting that distinct microbial interactions occur in different granules throughout the reactor. In addition, we identify novel networks of syntrophic metabolic interactions in different granules, perhaps caused by distinct thermodynamic conditions. Moreover, unseen methanogenic relationships (e.g. “Candidatus Aminicenantes” and Methanosaeta) are observed in UASB reactors. In total, we discover unexpected microbial interactions in granular micro-ecosystems supporting UASB ecology and treatment through a unique single-granule level approach. PMID:27936088

  16. Successful bioaugmentation of an activated sludge reactor with Rhodococcus sp. YYL for efficient tetrahydrofuran degradation

    International Nuclear Information System (INIS)

    Yao, Yanlai; Lu, Zhenmei; Zhu, Fengxiang; Min, Hang; Bian, Caimiao

    2013-01-01

    Highlights: • Rhodococcus sp. YYL is an efficient tetrahydrofuran-degrading strain. • Strain YYL was used to augment an activated sludge system for THF degradation. • Successful bioaugmentation was achieved only by coinoculation of strain YYL and the two bacilli. • Successful bioaugmentation of the system resulted in efficient THF degradation. -- Abstract: The exchange of tetrahydrofuran (THF)-containing wastewater should significantly affect the performance of an activated sludge system. In this study, the feasibility of using THF-degrading Rhodococcus sp. strain YYL to bioaugment an activated sludge system treating THF wastewater was explored. As indicated by a DGGE analysis, strain YYL alone could not dominate the system, with the concentration of mixed liquor suspended solids (MLSS) decreasing to nearly half of the initial concentration after 45 d, and the microbial diversity was found to be significantly reduced. However, after the reactor was augmented with the mixed culture of strain YYL and two bacilli initially coexisting in the enriched isolation source, strain YYL quickly became dominant in the system and was incorporated into the activated sludge. The concentration of MLSS increased from 2.1 g/L to 7.3 g/L in 20 d, and the efficiency of THF removal from the system was remarkably improved. After the successful bioaugmentation, more than 95% of THF was completely removed from the wastewater when 20 mM THF was continuously loaded into the system. In conclusion, our research first demonstrates that bioaugmentation of activated sludge system for THF degradation is feasible but that successful bioaugmentation should utilize a THF-degrading mixed culture as the inoculum, in which the two bacilli might help strain YYL colonize in activated sludge by co-aggregation

  17. Chemical-looping combustion in a reverse-flow fixed bed reactor

    International Nuclear Information System (INIS)

    Han, Lu; Bollas, George M.

    2016-01-01

    A reverse-flow fixed bed reactor concept for CLC (chemical-looping combustion) is explored. The limitations of conventional fixed bed reactors, as applied to CLC, are overcome by reversing the gas flow direction periodically to enhance the mixing characteristics of the bed, thus improving oxygen carrier utilization and energy efficiency with respect to power generation. The reverse-flow reactor is simulated by a dusty-gas model and compared with an equivalent fixed bed reactor without flow reversal. Dynamic optimization is used to calculate conditions at which each reactor operates at maximum energy efficiency. Several cases studies illustrate the benefits of reverse-flow operation for the CLC with CuO and NiO oxygen carriers and methane and syngas fuels. The results show that periodic reversal of the flow during reduction improves the contact between the fuel and unconverted oxygen carrier, enabling the system to suppress unwanted catalytic reactions and axial temperature and conversion gradients. The operational scheme presented reduces the fluctuations of temperature during oxidation and increases the high-temperature heat produced by the process. CLC in a reverse-flow reactor has the potential to achieve higher energy efficiency than conventional fixed bed CLC reactors, when integrated with a downstream gas turbine of a combined cycle power plant. - Highlights: • Reverse-flow fixed bed CLC reactors for combined cycle power systems. • Dynamic optimization tunes operation of batch and transient CLC systems. • The reverse-flow CLC system provides stable turbine-ready gas stream. • Reverse-flow CLC fixed bed reactor has superior CO 2 capture and thermal efficiency.

  18. Development of a trickle bed reactor of electro-Fenton process for wastewater treatment

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Yangming [Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 401122 (China); School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Liu, Hong, E-mail: liuhong@cigit.ac.cn [Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 401122 (China); Shen, Zhemin, E-mail: zmshen@sjtu.edu.cn [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Wang, Wenhua [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2013-10-15

    Highlights: • An electrochemical trickle bed reactor was composed of C-PTFE-coated graphite chips. • The trickle bed reactor had a high H{sub 2}O{sub 2} production rate in a dilute electrolyte. • An azo dye was effectively decomposed by the electro-Fenton process in the reactor. -- Abstract: To avoid electrolyte leakage and gas bubbles in the electro-Fenton (E-Fenton) reactors using a gas diffusion cathode, we developed a trickle bed cathode by coating a layer composed of carbon black and polytetrafluoroethylene (C-PTFE) onto graphite chips instead of carbon cloth. The trickle bed cathode was optimized by single-factor and orthogonal experiments, in which carbon black, PTFE, and a surfactant were considered as the determinant of the performance of graphite chips. In the reactor assembled by the trickle bed cathode, H{sub 2}O{sub 2} was generated with a current of 0.3 A and a current efficiency of 60%. This performance was attributed to the fine distribution of electrolyte and air, as well as the effective oxygen transfer from the gas phase to the electrolyte–cathode interface. In terms of H{sub 2}O{sub 2} generation and current efficiency, the developed trickle bed reactor had a performance comparable to that of the conventional E-Fenton reactor using a gas diffusion cathode. Further, 123 mg L{sup −1} of reactive brilliant red X-3B in aqueous solution was decomposed in the optimized trickle bed reactor as E-Fenton reactor. The decolorization ratio reached 97% within 20 min, and the mineralization reached 87% within 3 h.

  19. Development of a trickle bed reactor of electro-Fenton process for wastewater treatment

    International Nuclear Information System (INIS)

    Lei, Yangming; Liu, Hong; Shen, Zhemin; Wang, Wenhua

    2013-01-01

    Highlights: • An electrochemical trickle bed reactor was composed of C-PTFE-coated graphite chips. • The trickle bed reactor had a high H 2 O 2 production rate in a dilute electrolyte. • An azo dye was effectively decomposed by the electro-Fenton process in the reactor. -- Abstract: To avoid electrolyte leakage and gas bubbles in the electro-Fenton (E-Fenton) reactors using a gas diffusion cathode, we developed a trickle bed cathode by coating a layer composed of carbon black and polytetrafluoroethylene (C-PTFE) onto graphite chips instead of carbon cloth. The trickle bed cathode was optimized by single-factor and orthogonal experiments, in which carbon black, PTFE, and a surfactant were considered as the determinant of the performance of graphite chips. In the reactor assembled by the trickle bed cathode, H 2 O 2 was generated with a current of 0.3 A and a current efficiency of 60%. This performance was attributed to the fine distribution of electrolyte and air, as well as the effective oxygen transfer from the gas phase to the electrolyte–cathode interface. In terms of H 2 O 2 generation and current efficiency, the developed trickle bed reactor had a performance comparable to that of the conventional E-Fenton reactor using a gas diffusion cathode. Further, 123 mg L −1 of reactive brilliant red X-3B in aqueous solution was decomposed in the optimized trickle bed reactor as E-Fenton reactor. The decolorization ratio reached 97% within 20 min, and the mineralization reached 87% within 3 h

  20. A CFD Study on Inlet Plenum Flow Field of Pebble Bed Reactor

    International Nuclear Information System (INIS)

    Kim, Min Hwan; Lee, Won Jae; Chang, Jong Hwa

    2005-01-01

    High temperature gas cooled reactor, largely divided into two types of PBR (Pebble Bed Reactor) and PMR (Prismatic Modular Reactor), has becomes great interest of researchers in connection with the hydrogen production. KAERI has started a project to develop the gas cooled reactor for the hydrogen production and has been doing in-depth study for selecting the reactor type between PBR and PMR. As a part of the study, PBMR (Pebble Bed Modular Reactor) was selected as a reference PBR reactor for the CFD analysis and the flow field of its inlet plenum was simulated with computational fluid dynamics program CFX5. Due to asymmetrical arrangement of pipes to the inlet plenum, non-uniform flow distribution has been expected to occur, giving rise to non-uniform power distribution at the core. Flow fields of different arrangement of inlet pipes were also investigated, as one of measures to reduce the non-uniformity

  1. Neutron Fluence And DPA Rate Analysis In Pebble-Bed HTR Reactor Vessel Using MCNP

    Science.gov (United States)

    Hamzah, Amir; Suwoto; Rohanda, Anis; Adrial, Hery; Bakhri, Syaiful; Sunaryo, Geni Rina

    2018-02-01

    In the Pebble-bed HTR reactor, the distance between the core and the reactor vessel is very close and the media inside are carbon and He gas. Neutron moderation capability of graphite material is theoretically lower than that of water-moderated reactors. Thus, it is estimated much more the fast neutrons will reach the reactor vessel. The fast neutron collisions with the atoms in the reactor vessel will result in radiation damage and could be reducing the vessel life. The purpose of this study was to obtain the magnitude of neutron fluence in the Pebble-bed HTR reactor vessel. Neutron fluence calculations in the pebble-bed HTR reactor vessel were performed using the MCNP computer program. By determining the tally position, it can be calculated flux, spectrum and neutron fluence in the position of Pebble-bed HTR reactor vessel. The calculations results of total neutron flux and fast neutron flux in the reactor vessel of 1.82x108 n/cm2/s and 1.79x108 n/cm2/s respectively. The fast neutron fluence in the reactor vessel is 3.4x1017 n/cm2 for 60 years reactor operation. Radiation damage in stainless steel material caused by high-energy neutrons (> 1.0 MeV) will occur when it has reached the neutron flux level of 1.0x1024 n/cm2. The neutron fluence results show that there is no radiation damage in the Pebble-bed HTR reactor vessel, so it is predicted that it will be safe to operate at least for 60 years.

  2. Digestion of thermally hydrolyzed sewage sludge by anaerobic sequencing batch reactor

    International Nuclear Information System (INIS)

    Wang Zhijun; Wang Wei; Zhang Xihui; Zhang Guangming

    2009-01-01

    Laboratory experiments were conducted to investigate the performance of an anaerobic sequencing batch reactor (ASBR) for the digestion of thermally hydrolyzed sewage sludge. Both mesophilic ASBR and continuous-flow stirred tank reactors (CSTR) were evaluated with an equivalent loading rate of 2.71 kg COD/m 3 day at 20-day hydraulic retention time (HRT) and 5.42 kg COD/m 3 day at 10-day HRT. The average total chemical oxygen demand (TCOD) removals of the ASBR at the 20-day and 10-day HRT were 67.71% and 61.66%, respectively. These were 12.38% and 27.92% higher than those obtained by CSTR. As a result, the average daily gas production of ASBR was 15% higher than that of the CSTR at 20-day HRT, and 31% higher than that of the CSTR at 10-day HRT. Solids in thermally hydrolyzed sludge accumulated within ASBR were able to reach a high steady state with solid content of 65-80 g/L. This resulted in a relatively high solid retention time (SRT) of 34-40 days in the ASBR at 10-day HRT. However, too much solid accumulation resulted in the unsteadiness of the ASBR, making regular discharge of digested sludge from the bottom of the ASBR necessary to keep the reactor stable. The evolution of the gas production, soluble chemical oxygen demand (SCOD) and volatile fatty acids (VFAs) in an operation cycle of ASBR also showed that the ASBR was steady and feasible for the treatment of thermally hydrolyzed sludge

  3. Solid phase transport in series fluidised bed reactors

    International Nuclear Information System (INIS)

    Hayes, M.R.

    1980-01-01

    In a multistage counter-current fluidised bed column, fluidised bed material is recycled within each stage and a fraction is continuously withdrawn to the next lower stage at a rate dependent only on the rate of removal of the fluidised bed material from the base of the column. It has a particular application to the ion exchange treatment of liquids containing suspended solids, for example leach solutions from uranium ores. (author)

  4. Start-up of horizontal anaerobic reactors with sludge blanket and fixed bed for wastewater treatment from coffee processing by wet method Partida de reatores anaeróbios horizontais com manta de lodo e de leito fixo para tratamento de águas residuárias do beneficiamento de frutos do cafeeiro por via úmida

    Directory of Open Access Journals (Sweden)

    Roberto A. de Oliveira

    2013-04-01

    Full Text Available In this study it was evaluated the start-up procedures of anaerobic treatment system with three horizontal anaerobic reactors (R1, R2 and R3, installed in series, with volume of 1.2 L each. R1 had sludge blanket, and R2 and R3 had half supporter of bamboo and coconut fiber, respectively. As an affluent, it was synthesized wastewater from mechanical pulping of the coffee fruit by wet method, with a mean value of total chemical oxygen demand (CODtotal of 16,003 mg L-1. The hydraulic retention time (HRT in each reactor was 30 h. The volumetric organic loading (VOL applied in R1 varied from 8.9 to 25.0 g of CODtotal (L d-1. The mean removal efficiencies of CODtotal varied from 43 to 97% in the treatment system (R1+R2+R3, stabilizing above 80% after 30 days of operation. The mean content of methane in the biogas were of 70 to 76%, the mean volumetric production was 1.7 L CH4 (L reactor d-1 in the system, and the higher conversions were around at 0.20 L CH4 (g CODremoved-1 in R1 and R2. The mean values of pH in the effluents ranged from 6.8 to 8.3 and the mean values of total volatile acids remained below 200 mg L-1 in the effluent of R3. The concentrations of total phenols of the affluent ranged from 45 to 278 mg L-1, and the mean removal efficiency was of 52%. The start-up of the anaerobic treatment system occurred after 30 days of operation as a result of inoculation with anaerobic sludge with active microbiota.Foram avaliados os procedimentos de partida de sistema de tratamento com três reatores anaeróbios horizontais (R1, R2 e R3, instalados em série, com volume de 1,2 L cada. O R1 com manta de lodo e o R2 e R3 através de suporte de bambu e fibra de coco, respectivamente. Como afluente,foram sintetizadas águas residuárias do despolpamento mecânico dos frutos do cafeeiro por via úmida, com valor médio de demanda química de oxigênio total (DQOtotal de 16.003 mg L-1. O tempo de detenção hidráulica (TDH em cada reator foi de 30 h. As

  5. 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

  6. Optimization of food waste hydrolysis in leach bed coupled with methanogenic reactor: effect of pH and bulking agent.

    Science.gov (United States)

    Xu, Su Yun; Lam, Hoi Pui; Karthikeyan, O Parthiba; Wong, Jonathan W C

    2011-02-01

    The effects of pH and bulking agents on hydrolysis/acidogenesis of food waste were studied using leach bed reactor (LBR) coupled with methanogenic up-flow anaerobic sludge blanket (UASB) reactor. The hydrolysis rate under regulated pH (6.0) was studied and compared with unregulated one during initial experiment. Then, the efficacies of five different bulking agents, i.e. plastic full particles, plastic hollow sphere, bottom ash, wood chip and saw dust were experimented under the regulated pH condition. Leachate recirculation with 50% water replacement was practiced throughout the experiment. Results proved that the daily leachate recirculation with pH control (6.0) accelerated the hydrolysis rate (59% higher volatile fatty acids) and methane production (up to 88%) compared to that of control without pH control. Furthermore, bottom ash improved the reactor alkalinity, which internally buffered the system that improved the methane production rate (0.182 l CH(4)/g VS(added)) than other bulking agents. Copyright © 2010 Elsevier Ltd. All rights reserved.

  7. Biological treatment of petroleum sludges in liquid/solids contact reactors

    Energy Technology Data Exchange (ETDEWEB)

    Stroo, H F [Remediation Technologies, Inc., Kent, WA (USA)

    1989-10-01

    Biological treatment of hazardous wastes (bioremediation) is now recognized as an effective and cost-efficient approach for on-site cleanup of petroleum-contaminated soils and sludges. These strategies may require pretreatment of oily sludges produced as refinery wastes. Recent work has shown that liquid/solids contact (LSC) bioreactors are capable of adequate pretreatment at lower cost than competing technologies. Since LSC operations aim to maximize microbial numbers and activity, inexpensive microbiological monitoring can provide rapid feedback on performance. LSC technology represents a method for rapid biological treatment of petroleum sludges in a contained reactor. The technology has proven highly effective for a variety of oil refinery sludges, with degradation rates up to ten times faster than those observed during land treatment. The most promising use of LSC is a pretreatment. Because biological treatment in LSC can degrade and detoxify contaminants rapidly and relatively inexpensively, with little risk of off-site contamination, this technology should be considered by refiners having to close sites or treat current waste-streams. 7 refs., 1 figs., 1 tab.

  8. Design of particle bed reactors for the space nuclear thermal propulsion program

    International Nuclear Information System (INIS)

    Ludewig, H.; Powell, J.R.; Todosow, M.; Maise, G.; Barletta, R.; Schweitzer, D.G.

    1996-01-01

    This paper describes the design for the Particle Bed Reactor (PBR) that was considered for the Space Nuclear Thermal Propulsion (SNTP) Program. The methods of analysis and their validation are outlined first. Monte Carlo methods were used for the physics analysis, several new algorithms were developed for the fluid dynamics, heat transfer and transient analysis; and commercial codes were used for the stress analysis. We carried out a critical experiment, prototypic of the PBR to validate the reactor physics; blowdown experiments with beds of prototypic dimensions were undertaken to validate the power-extraction capabilities from particle beds. In addition, materials and mechanical design concepts for the fuel elements were experimentally validated. (author)

  9. Microbial community composition and dynamics of moving bed biofilm reactor systems treating municipal sewage.

    Science.gov (United States)

    Biswas, Kristi; Turner, Susan J

    2012-02-01

    Moving bed biofilm reactor (MBBR) systems are increasingly used for municipal and industrial wastewater treatment, yet in contrast to activated sludge (AS) systems, little is known about their constituent microbial communities. This study investigated the community composition of two municipal MBBR wastewater treatment plants (WWTPs) in Wellington, New Zealand. Monthly samples comprising biofilm and suspended biomass were collected over a 12-month period. Bacterial and archaeal community composition was determined using a full-cycle community approach, including analysis of 16S rRNA gene libraries, fluorescence in situ hybridization (FISH) and automated ribosomal intergenic spacer analysis (ARISA). Differences in microbial community structure and abundance were observed between the two WWTPs and between biofilm and suspended biomass. Biofilms from both plants were dominated by Clostridia and sulfate-reducing members of the Deltaproteobacteria (SRBs). FISH analyses indicated morphological differences in the Deltaproteobacteria detected at the two plants and also revealed distinctive clustering between SRBs and members of the Methanosarcinales, which were the only Archaea detected and were present in low abundance (<5%). Biovolume estimates of the SRBs were higher in biofilm samples from one of the WWTPs which receives both domestic and industrial waste and is influenced by seawater infiltration. The suspended communities from both plants were diverse and dominated by aerobic members of the Gammaproteobacteria and Betaproteobacteria. This study represents the first detailed analysis of microbial communities in full-scale MBBR systems and indicates that this process selects for distinctive biofilm and planktonic communities, both of which differ from those found in conventional AS systems.

  10. Conceptual design of a fluidized bed nuclear reactor : Statics, dynamics and safety-related aspects

    NARCIS (Netherlands)

    Agung, A.

    2007-01-01

    In this thesis a conceptual design of an innovative high temperature reactor based on the fluidization principle (FLUBER) is proposed. The reactor should satisfy the following requirements: (a) modular and low power, (b)) large shutdown margin, (c) able to produce power when the bed of particles

  11. Model description and kinetic parameter analysis of MTBE biodegradation in a packed bed reactor

    DEFF Research Database (Denmark)

    Waul, Christopher Kevin; Arvin, Erik; Schmidt, Jens Ejbye

    2008-01-01

    A dynamic modeling approach was used to estimate in-situ model parameters, which describe the degradation of methyl tert-butyl ether (MTBE) in a laboratory packed bed reactor. The measured dynamic response of MTBE pulses injected at the reactor's inlet was analyzed by least squares and parameter...

  12. Discharge Characteristics of Series Surface/Packed-Bed Discharge Reactor Diven by Bipolar Pulsed Power

    International Nuclear Information System (INIS)

    Hu Jian; Jiang Nan; Li Jie; Shang Kefeng; Lu Na; Wu Yan; Mizuno Akira

    2016-01-01

    The discharge characteristics of the series surface/packed-bed discharge (SSPBD) reactor driven by bipolar pulse power were systemically investigated in this study. In order to evaluate the advantages of the SSPBD reactor, it was compared with traditional surface discharge (SD) reactor and packed-bed discharge (PBD) reactor in terms of the discharge voltage, discharge current, and ozone formation. The SSPBD reactor exhibited a faster rising time and lower tail voltage than the SD and PBD reactors. The distribution of the active species generated in different discharge regions of the SSPBD reactor was analyzed by optical emission spectra and ozone analysis. It was found that the packed-bed discharge region (3.5 mg/L), rather than the surface discharge region (1.3 mg/L) in the SSPBD reactor played a more important role in ozone generation. The optical emission spectroscopy analysis indicated that more intense peaks of the active species (e.g. N2 and OI) in the optical emission spectra were observed in the packed-bed region. (paper)

  13. Discharge Characteristics of Series Surface/Packed-Bed Discharge Reactor Diven by Bipolar Pulsed Power

    Science.gov (United States)

    Hu, Jian; Jiang, Nan; Li, Jie; Shang, Kefeng; Lu, Na; Wu, Yan; Mizuno, Akira

    2016-03-01

    The discharge characteristics of the series surface/packed-bed discharge (SSPBD) reactor driven by bipolar pulse power were systemically investigated in this study. In order to evaluate the advantages of the SSPBD reactor, it was compared with traditional surface discharge (SD) reactor and packed-bed discharge (PBD) reactor in terms of the discharge voltage, discharge current, and ozone formation. The SSPBD reactor exhibited a faster rising time and lower tail voltage than the SD and PBD reactors. The distribution of the active species generated in different discharge regions of the SSPBD reactor was analyzed by optical emission spectra and ozone analysis. It was found that the packed-bed discharge region (3.5 mg/L), rather than the surface discharge region (1.3 mg/L) in the SSPBD reactor played a more important role in ozone generation. The optical emission spectroscopy analysis indicated that more intense peaks of the active species (e.g. N2 and OI) in the optical emission spectra were observed in the packed-bed region. supported by National Natural Science Foundation of China (No. 51177007), the Joint Funds of National Natural Science Foundation of China (No. U1462105), and Dalian University of Technology Fundamental Research Fund of China (No. DUT15RC(3)030)

  14. Cost analysis of enzymatic biodiesel production in small-scaled packed-bed reactors

    NARCIS (Netherlands)

    Budzaki, S.; Miljic, G.; Sundaram, S.; Tisma, M.; Hessel, V.

    2017-01-01

    A cost analysis of enzymatic biodiesel production in small-scaled packed-bed reactors using refined sunflower oil is performed in this work. A few enzymatic micro-flow reactors have so far reached a performance close to gram-scale, which might be sufficient for the pharmaceutical industry. This

  15. Thermofluid-neutronic stability of the rotating, fluidized bed, space-power reactor

    International Nuclear Information System (INIS)

    Lee, C.C.; Jones, O.C.; Becker, M.

    1993-01-01

    A rotating fluidized bed nuclear reactor has the potential of being a vary attractive option for ultra-high power space systems, especially for propulsion. Research has already examined fuel bed expansion due to variations in state variables, propellant flow rate, and rotational speed, and has also considered problems related to thermal stress. This paper describes the results of a coupled thermofluid-neutronic analysis where perturbations in fuel bed height caused by maneuvering changes in operating conditions alter power levels due to varying absorption of neutrons which would otherwise leak from the system, mainly through the nozzle. This first analysis was not a detailed stability analysis. Rather, it utilized simplified neutronic methods, and was intended to provide an order-of-magnitude assessment of the stability of the reactor with the intention to determine whether or not stability might be a 'concept killer'. Stability was compared with a fixed-fuel-bed reactor of identical geometry for three different cases comprising a set of small, medium and large sizes/powers from 250 MW to 5 GW. It was found that power fluctuations in the fluidized bed reactor were larger by 100 db or more than expected in a packed bed reactor of the same geometry, but never resulted in power excursions. Margins to unit gain in some cases, however, were sufficiently small that the approximations in this quasi-2-dimensional model may not be sufficiently accurate to preclude significant excursions. (orig.)

  16. Computational and experimental prediction of dust production in pebble bed reactors, Part II

    Energy Technology Data Exchange (ETDEWEB)

    Hiruta, Mie; Johnson, Gannon [Department of Mechanical Engineering, University of Idaho, 1776 Science Center Drive, Idaho Falls, ID 83401 (United States); Rostamian, Maziar, E-mail: mrostamian@asme.org [Department of Mechanical Engineering, University of Idaho, 1776 Science Center Drive, Idaho Falls, ID 83401 (United States); Potirniche, Gabriel P. [Department of Mechanical Engineering, University of Idaho, 1776 Science Center Drive, Idaho Falls, ID 83401 (United States); Ougouag, Abderrafi M. [Idaho National Laboratory, 2525 N Fremont Avenue, Idaho Falls, ID 83401 (United States); Bertino, Massimo; Franzel, Louis [Department of Physics, Virginia Commonwealth University, Richmond, VA 23284 (United States); Tokuhiro, Akira [Department of Mechanical Engineering, University of Idaho, 1776 Science Center Drive, Idaho Falls, ID 83401 (United States)

    2013-10-15

    Highlights: • Custom-built high temperature, high pressure tribometer is designed. • Two different wear phenomena at high temperatures are observed. • Experimental wear results for graphite are presented. • The graphite wear dust production in a typical Pebble Bed Reactor is predicted. -- Abstract: This paper is the continuation of Part I, which describes the high temperature and high pressure helium environment wear tests of graphite–graphite in frictional contact. In the present work, it has been attempted to simulate a Pebble Bed Reactor core environment as compared to Part I. The experimental apparatus, which is a custom-designed tribometer, is capable of performing wear tests at PBR relevant higher temperatures and pressures under a helium environment. This environment facilitates prediction of wear mass loss of graphite as dust particulates from the pebble bed. The experimental results of high temperature helium environment are used to anticipate the amount of wear mass produced in a pebble bed nuclear reactor.

  17. The behaviour of ashes and heavy metals during the co-combustion of sewage sludges in a fluidised bed

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, M.H.; Abelha, P.; Lapa, N.; Oliveira, J.S.; Cabrita, I.; Gulyurtlu, I. [INETI, Lisbon (Portugal)

    2003-07-01

    Co-combustion tests of dry sewage sludges with coal were performed in a pilot bubbling FBC with the aim of characterizating the ashes and determining the behaviour of heavy metals in the process. The tests showed compliance with the regulatory levels as far as heavy metal emissions were concerned. The bottom ashes, which accounted for about 70% of the total ash production, were obtained in a granular form, with diameters ranging from 0.5 to 4 mm. The heavy metals were distributed in ashes obtained from different locations of the installation and their concentrations were found to vary depending on the location of capture. The increase in heavy metals content in bottom ashes was not found to lead to higher leachability and ecotoxicity compared to sewage sludges. Mercury suffered vaporisation inside the reactor, thus leaving bottom ashes free of contamination by it. However, there was observed a strong retention of mercury in cyclone ashes due to the presence of unburned carbon which probably acted as an adsorbent. The effluent mercury was also found to be mostly associated with the particulate fraction, being less than 20% emitted in gaseous forms. The results suggested that the combustion of the sewage sludge could successfully be carried out and the amount of unburned carbon leaving the combustor but captured in cyclone was large enough to ensure substantial retention of mercury at low temperatures, hence could contribute to an improvement of the mercury release which still remains an issue of great concern to resolve during combustion of waste materials.

  18. Review of PSI studies on reactor physics and thermal fluid dynamics of pebble bed reactors

    International Nuclear Information System (INIS)

    Prasser, Horst-Michael

    2014-01-01

    Switzerland is member of the Generation IV International Forum (GIF). The related work takes entirely place at PSI in the working groups of Gas-Cooled Fast Reactors and Very High Temperature Reactors. In the past, PSI has performed experimental and theoretical studies on criticality issues of pebble beds at the PROTEUS reactor, as well as a preliminary risk assessment of a prototypal HTR as an input for a comparison of energy supply options. PROTEUS was a critical assembly with an annular driver zone. The central region was filled by arrangements of fuel spheres. The reactivity effect of a water ingress was investigated by simulating the water by polyethylene rods of different diameter inserted into the gaps of a regular package. For sub-criticality measurements in pebble beds, a built-in pulsed neutron source was used. The experimental results were used to validate diffusion and higher order neutron transport models. Concerning thermal hydraulics of gas flows, the vast experience of PSI is focused on hydrogen transport, accumulation, and dispersion in containments of light water reactors. The phenomena are comparable in many aspects to the fluid dynamic issues relevant to HTR. Experiments on hydrogen flows are performed for numerous scenarios in the large-scale containment test facility PANDA. Hydrogen is substituted by helium as a model fluid. An important generic aspect is turbulent mixing in the presence of strong stratification, which is relevant for HTR as well. In a parallel project, generic small-scale mixing experiments with a high density ratio of 1:7 are carried out in a horizontal rectangular channel, where helium and nitrogen flows are brought into contact downstream of the rear edge of a splitter plate. Due to the high density ratio, turbulent mixing is affected by strong non-Boussinesq effects. The measurements taken by Particle Imaging Velocimetry (PIV) and Laser Induced Fluorescence techniques are compared to RANS and LES simulations. Similar large

  19. Development of a trickle bed reactor of electro-Fenton process for wastewater treatment.

    Science.gov (United States)

    Lei, Yangming; Liu, Hong; Shen, Zhemin; Wang, Wenhua

    2013-10-15

    To avoid electrolyte leakage and gas bubbles in the electro-Fenton (E-Fenton) reactors using a gas diffusion cathode, we developed a trickle bed cathode by coating a layer composed of carbon black and polytetrafluoroethylene (C-PTFE) onto graphite chips instead of carbon cloth. The trickle bed cathode was optimized by single-factor and orthogonal experiments, in which carbon black, PTFE, and a surfactant were considered as the determinant of the performance of graphite chips. In the reactor assembled by the trickle bed cathode, H2O2 was generated with a current of 0.3A and a current efficiency of 60%. This performance was attributed to the fine distribution of electrolyte and air, as well as the effective oxygen transfer from the gas phase to the electrolyte-cathode interface. In terms of H2O2 generation and current efficiency, the developed trickle bed reactor had a performance comparable to that of the conventional E-Fenton reactor using a gas diffusion cathode. Further, 123 mg L(-1) of reactive brilliant red X-3B in aqueous solution was decomposed in the optimized trickle bed reactor as E-Fenton reactor. The decolorization ratio reached 97% within 20 min, and the mineralization reached 87% within 3h. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. 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.)

  1. Thermal safety analysis for pebble bed blanket fusion-fission hybrid reactor

    International Nuclear Information System (INIS)

    Wei Renjie

    1998-01-01

    Pebble bed blanket hybrid reactor may have more advantages than slab element blanket hybrid reactor in nuclear fuel production and nuclear safety. The thermo-hydraulic calculations of the blanket in the Tokamak helium cooling pebble bed blanket fusion-fission hybrid reactor developed in China are carried out using the Code THERMIX and auxiliary code. In the calculations different fuel pebble material and steady state, depressurization and total loss of flow accident conditions are included. The results demonstrate that the conceptual design of the Tokamak helium cooling pebble bed blanket fusion-fission hybrid reactor with dump tank is feasible and safe enough only if the suitable fuel pebble material is selected and the suitable control system and protection system are established. Some recommendations for due conceptual design are also presented

  2. Converting mesophilic upflow sludge blanket (UASB) reactors to thermophilic by applying axenic methanogenic culture bioaugmentation

    DEFF Research Database (Denmark)

    Zhu, Xinyu; Treu, Laura; Kougias, Panagiotis G.

    2018-01-01

    on the microbial consortium. The adaptation of microbial community to a new environment or condition can be accelerated by a process known as “bioaugmentation” or “microbial community manipulation”, during which exogenous microorganisms harbouring specific metabolic activities are introduced to the reactor....... The aim of the current study was to rapidly convert the operational temperature of up-flow anaerobic sludge blanket (UASB) reactors from mesophilic to thermophilic conditions by applying microbial community manipulation techniques. Three different bioaugmentation strategies were compared and it was proven...... that the injection of axenic methanogenic culture was the most efficient approach leading to improved biomethanation process with 40% higher methane production rate compared to the control reactor. Microbial community analyses revealed that during bioaugmentation, the exogenous hydrogenotrophic methanogen could...

  3. The behavior of ashes and heavy metals during the co-combustion of sewage sludges in a fluidised bed

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Helena M.; Abelha, P.; Cabrita, I. [INETI-DEECA, Lisboa (Portugal); Lapa, N.; Oliveira, J.S. [UNL-Ubia, Monte de Caparica (Portugal)

    2003-07-01

    Co-combustion tests of dry sewage sludges with coal were performed in a pilot bubbling FRC aiming at the characterization of ashes and determining the behaviour of heavy metals in the process. The tests showed compliance with the regulatory levels as far as heavy metal emissions were concerned. The bottom ashes, which accounted for about 70% of the total ash production, were obtained in a granular form, with diameters ranging from 0.5 to 4 mm. The heavy metals were distributed in ashes obtained from different locations of the installation and their concentrations were found to vary depending on the location of capture. The increase in heavy metals content in bottom ashes was not found to lead to higher leachability and ecotoxicity compared to sewage sludges, suggesting that there could be opportunities for their reactor further use. Mercury suffered vaporisation inside the reactor, thus leaving bottom ashes free of contamination by it. However, there was observed a strong retention of mercury in cyclone ashes due to the presence of unburned carbon which probably acted as an adsorbent. The effluent mercury was also found to be mostly associated with the particulate fraction, being less than 20% emitted in gaseous forms. The results suggested that the combustion of the sewage sludge could successfully be carried out, and the amount of unburned carbon leaving the combustor but captured in the cyclone was large enough to ensure substantial retention of mercury at low temperatures, and, hence, could contribute to an improvement of the mercury release, which still remains an issue of great concern to resolve during combustion of waste materials.

  4. Continuous biological waste gas treatment in stirred trickle-bed reactor with discontinuous removal of biomass.

    Science.gov (United States)

    Laurenzis, A; Heits, H; Wübker, S; Heinze, U; Friedrich, C; Werner, U

    1998-02-20

    A new reactor for biological waste gas treatment was developed to eliminate continuous solvents from waste gases. A trickle-bed reactor was chosen with discontinuous movement of the packed bed and intermittent percolation. The reactor was operated with toluene as the solvent and an optimum average biomass concentration of between 5 and 30 kg dry cell weight per cubic meter packed bed (m3pb). This biomass concentration resulted in a high volumetric degradation rate. Reduction of surplus biomass by stirring and trickling caused a prolonged service life and prevented clogging of the trickle bed and a pressure drop increase. The pressure drop after biomass reduction was almost identical to the theoretical pressure drop as calculated for the irregular packed bed without biomass. The reduction in biomass and intermittent percolation of mineral medium resulted in high volumetric degradation rates of about 100 g of toluene m-3pb h-1 at a load of 150 g of toluene m-3pb h-1. Such a removal rate with a trickle-bed reactor was not reported before. Copyright 1998 John Wiley & Sons, Inc.

  5. Numerical simulation for debris bed behavior in sodium cooled fast reactor

    International Nuclear Information System (INIS)

    Tagami, Hirotaka; Tobita, Yoshiharu

    2014-01-01

    For safety analysis of SFR, it is necessary to evaluate behavior along with coolability of debris bed in lower plenum which is formed in severe accident. In order to analyze debris behavior, model for dense sediment particles behavior was proposed and installed in SFR safety analysis code SIMMER. SIMMER code could adequately reproduce experimental results simulating the self-leveling phenomena with appropriate model parameters for bed stiffness. In reactor condition, the self-leveling experiment for prototypical debris bed has not been performed. Additionally, the prototypical debris bed consists of non-spherical particles and it is difficult to quantify model parameters. This situation brings sensitivity analysis to investigate effect of model parameters on the self-leveling phenomena of prototypical debris bed in present paper. As initial condition for sensitivity analysis, simple mound-like debris bed in sodium-filled lower plenum in reactor vessel is considered. The bed consists of the mixture of fuel debris of 3,300 kg and steel debris of 1,570 kg. Decay heat is given to this fuel debris. The model parameter is chosen as sensitivity parameter. Sensitivity analysis shows that the model parameters can effect on intensity of self-leveling phenomena and eventual flatness of bed. In all analyses, however, coolant and sodium vapor break the debris bed at mainly center part of bed and the debris is relocated to outside of bed. Through this process, the initial debris bed is almost planarized before re-melting of debris. This result shows that the model parameters affect the self-leveling phenomena, but its effect in the safety analysis of SFRs is limited. (author)

  6. Elemental mercury vapor capture by powdered activated carbon in a fluidized bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Fabrizio Scala; Riccardo Chirone; Amedeo Lancia [Istituto di Ricerche sulla Combustione - CNR, Napoli (Italy)

    2011-06-15

    A bubbling fluidized bed of inert material was used to increase the activated carbon residence time in the reaction zone and to improve its performance for mercury vapor capture. Elemental mercury capture experiments were conducted at 100{sup o}C in a purposely designed 65 mm ID lab-scale pyrex reactor, that could be operated both in the fluidized bed and in the entrained bed configurations. Commercial powdered activated carbon was pneumatically injected in the reactor and mercury concentration at the outlet was monitored continuously. Experiments were carried out at different inert particle sizes, bed masses, fluidization velocities and carbon feed rates. Experimental results showed that the presence of a bubbling fluidized bed led to an increase of the mercury capture efficiency and, in turn, of the activated carbon utilization. This was explained by the enhanced activated carbon loading and gas-solid contact time that establishes in the reaction zone, because of the large surface area available for activated carbon adhesion/deposition in the fluidized bed. Transient mercury concentration profiles at the bed outlet during the runs were used to discriminate between the controlling phenomena in the process. Experimental data have been analyzed in the light of a phenomenological framework that takes into account the presence of both free and adhered carbon in the reactor as well as mercury saturation of the adsorbent. 14 refs., 7 figs.

  7. Behavior and fate of copper ions in an anammox granular sludge reactor and strategies for remediation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zheng-Zhe; Deng, Rui; Cheng, Ya-Fei; Zhou, Yu-Huang; Buayi, Xiemuguli [College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036 (China); Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, Hangzhou Normal University, Hangzhou 310036 (China); Zhang, Xian; Wang, Hui-Zhong [College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036 (China); Jin, Ren-Cun, E-mail: jrczju@aliyun.com [College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036 (China); Key Laboratory of Hangzhou City for Ecosystem Protection and Restoration, Hangzhou Normal University, Hangzhou 310036 (China)

    2015-12-30

    Highlights: • The Cu partition in an anammox UASB reactor was predicted by models. • The distribution and form dynamics of Cu in anammox reactors were tracked. • The response of the EPS to Cu(II) was characterized by 3D-EEM spectra. • The mechanism of Cu inhibition on anammox granules was updated. • The feasibilities of two novel remediation strategies were investigated. - Abstract: In this study, the behavior, distribution and form dynamics of overloaded Cu(II) in anaerobic ammonium oxidation (anammox) granular sludge reactors were investigated. The performance and physiological characteristics were tracked by continuous-flow monitoring to evaluate the long-term effects. High Cu loading (0.24 g L{sup −1} d{sup −1}) exceeded sludge bearing capacity, and precipitation dominated the removal pathway. The Cu distribution migrated from the extracellular polymeric substances-bound to the cell-associated Cu and the Cu forms shifted from the weakly bound to strongly bound fractions over time. Pearson correlation and fluorescence spectra analyses showed that the increase in protein concentrations in the EPS was a clear self-defense response to Cu(II) stress. Two remediation strategies, i.e., ethylenediamine tetraacetic acid (EDTA) washing and ultrasound-enhanced EDTA washing, weakened the equilibrium metal partition coefficient from 5.8 to 0.45 and 0.34 L mg{sup −1}SS, respectively, thereby accelerating the external diffusion of the Cu that had accumulated in the anammox granules.

  8. Behavior and fate of copper ions in an anammox granular sludge reactor and strategies for remediation

    International Nuclear Information System (INIS)

    Zhang, Zheng-Zhe; Deng, Rui; Cheng, Ya-Fei; Zhou, Yu-Huang; Buayi, Xiemuguli; Zhang, Xian; Wang, Hui-Zhong; Jin, Ren-Cun

    2015-01-01

    Highlights: • The Cu partition in an anammox UASB reactor was predicted by models. • The distribution and form dynamics of Cu in anammox reactors were tracked. • The response of the EPS to Cu(II) was characterized by 3D-EEM spectra. • The mechanism of Cu inhibition on anammox granules was updated. • The feasibilities of two novel remediation strategies were investigated. - Abstract: In this study, the behavior, distribution and form dynamics of overloaded Cu(II) in anaerobic ammonium oxidation (anammox) granular sludge reactors were investigated. The performance and physiological characteristics were tracked by continuous-flow monitoring to evaluate the long-term effects. High Cu loading (0.24 g L −1 d −1 ) exceeded sludge bearing capacity, and precipitation dominated the removal pathway. The Cu distribution migrated from the extracellular polymeric substances-bound to the cell-associated Cu and the Cu forms shifted from the weakly bound to strongly bound fractions over time. Pearson correlation and fluorescence spectra analyses showed that the increase in protein concentrations in the EPS was a clear self-defense response to Cu(II) stress. Two remediation strategies, i.e., ethylenediamine tetraacetic acid (EDTA) washing and ultrasound-enhanced EDTA washing, weakened the equilibrium metal partition coefficient from 5.8 to 0.45 and 0.34 L mg −1 SS, respectively, thereby accelerating the external diffusion of the Cu that had accumulated in the anammox granules.

  9. CFD study on the supercritical carbon dioxide cooled pebble bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Dali, E-mail: ydlmitd@outlook.com; Peng, Minjun; Wang, Zhongyi

    2015-01-15

    Highlights: • An innovation concept of supercritical carbon dioxide cooled pebble bed reactor is proposed. • Body-centered cuboid (BCCa) arrangement is adopted for the pebbles. • S-CO{sub 2} would be a good candidate coolant for using in pebble bed reactor. - Abstract: The thermal hydraulic study of using supercritical carbon dioxide (S-CO{sub 2}), a superior fluid state brayton cycle medium, in pebble bed type nuclear reactor is assessed through computational fluid dynamics (CFD) methodology. Preliminary concept design of this S-CO{sub 2} cooled pebble bed reactor (PBR) is implemented by the well-known KTA heat transfer correlation and Ergun pressure drop equation. Eddy viscosity transport turbulence model is adopted and verified by KTA calculated results. Distributions of the temperature, velocity, pressure and Nusselt (Nu) number of the coolant near the surface of the middle spherical fuel element are obtained and analyzed. The conclusion of the assessment is that S-CO{sub 2} would be a good candidate coolant for using in pebble bed reactor due primarily to its good heat transfer characteristic and large mass density, which could lead to achieve lower pressure drop and higher power density.

  10. 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

  11. Conversion of metallurgical coke and coal using a Coal Direct Chemical Looping (CDCL) moving bed reactor

    International Nuclear Information System (INIS)

    Luo, Siwei; Bayham, Samuel; Zeng, Liang; McGiveron, Omar; Chung, Elena; Majumder, Ankita; Fan, Liang-Shih

    2014-01-01

    Highlights: • Accumulated more than 300 operation hours were accomplished for the moving bed reducer reactor. • Different reactor operation variables were investigated with optimal conditions identified. • High conversions of sub-bituminous coal and bituminous coal were achieved without flow problems. • Co-current and counter-current contact modes were tested and their applicability was discussed. - Abstract: The CLC process has the potential to be a transformative commercial technology for a carbon-constrained economy. The Ohio State University Coal Direct Chemical Looping (CDCL) process directly converts coal, eliminating the need for a coal gasifier oran air separation unit (ASU). Compared to other solid-fuel CLC processes, the CDCL process is unique in that it consists of a countercurrent moving bed reducer reactor. In the proposed process, coal is injected into the middle of the moving bed, whereby the coal quickly heats up and devolatilizes, splitting the reactor roughly into two sections with no axial mixing. The top section consists of gaseous fuel produced from the coal volatiles, and the bottom section consists of the coal char mixed with the oxygen carrier. A bench-scale moving bed reactor was used to study the coal conversion with CO 2 as the enhancing gas. Initial tests using metallurgical cokefines as feedstock were conducted to test the effects of operational variables in the bottom section of the moving bed reducer, e.g., reactor temperature, oxygen carrier to char ratio, enhancer gas CO 2 flow rate, and oxygen carrier flow rates. Experiments directly using coal as the feedstock were subsequently carried out based on these test results. Powder River Basin (PRB) coal and Illinois #6 coal were tested as representative sub-bituminous and bituminous coals, respectively. Nearly complete coal conversion was achieved using composite iron oxide particles as the oxygen carriers without any flow problems. The operational results demonstrated that a

  12. Evaluation of Packed-Bed Reactor and Continuous Stirred Tank Reactor for the Production of Colchicine Derivatives

    OpenAIRE

    Dubey, Kashyap Kumar; Kumar, Dhirendra; Kumar, Punit; Haque, Shafiul; Jawed, Arshad

    2013-01-01

    Bioconversion of colchicine into its pharmacologically active derivative 3-demethylated colchicine (3-DMC) mediated by P450BM3 enzyme is an economic and promising strategy for the production of this inexpensive and potent anticancer drug. Continuous stirred tank reactor (CSTR) and packed-bed reactor (PBR) of 3 L and 2 L total volumes were compared for the production of 3-demethylated colchicine (3-DMC) a colchicine derivative using Bacillus megaterium MTCC*420 under aerobic conditions. Statis...

  13. Nitrate removal from high strength nitrate-bearing wastes in granular sludge sequencing batch reactors.

    Science.gov (United States)

    Krishna Mohan, Tulasi Venkata; Renu, Kadali; Nancharaiah, Yarlagadda Venkata; Satya Sai, Pedapati Murali; Venugopalan, Vayalam Purath

    2016-02-01

    A 6-L sequencing batch reactor (SBR) was operated for development of granular sludge capable of denitrification of high strength nitrates. Complete and stable denitrification of up to 5420 mg L(-1) nitrate-N (2710 mg L(-1) nitrate-N in reactor) was achieved by feeding simulated nitrate waste at a C/N ratio of 3. Compact and dense denitrifying granular sludge with relatively stable microbial community was developed during reactor operation. Accumulation of large amounts of nitrite due to incomplete denitrification occurred when the SBR was fed with 5420 mg L(-1) NO3-N at a C/N ratio of 2. Complete denitrification could not be achieved at this C/N ratio, even after one week of reactor operation as the nitrite levels continued to accumulate. In order to improve denitrification performance, the reactor was fed with nitrate concentrations of 1354 mg L(-1), while keeping C/N ratio at 2. Subsequently, nitrate concentration in the feed was increased in a step-wise manner to establish complete denitrification of 5420 mg L(-1) NO3-N at a C/N ratio of 2. The results show that substrate concentration plays an important role in denitrification of high strength nitrate by influencing nitrite accumulation. Complete denitrification of high strength nitrates can be achieved at lower substrate concentrations, by an appropriate acclimatization strategy. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  14. Pebble bed test reactor in peu-a-peu load

    International Nuclear Information System (INIS)

    Kranz, L.

    1988-03-01

    The presented work deals with a new type of load model for high temperature reactors with spherical fuels: the peu-a-peu load system. Using this load system the reactor core is only filled partially in the beginning of the power operation. But it has to be a critical base core. With proceeding burn-off the reactor is filled up with further fuel elements the way that it stays always just critically. When the reactor is filled up completely with fuel elements, the reactor operation has to be interrupted and the reactor has to be discharged. Afterwards a new cycle can start like the one just described. A reference reactor with 100 MW thermal power is investigated in this work in detail and should make clear the way of function of the load system and the base idea of 'simplicity and safety'. The improvement proposal to use again a part of the fuel elements of a cycle for the next cycle minimizes the higher specific uranium need of a peu-a-peu reactor decisively. (orig.) [de

  15. Pebble bed reactor fiscal year 1980: review summary report

    International Nuclear Information System (INIS)

    1980-07-01

    Information on high-temperature reactor development is presented concerning reactor operating experience; core performance assessment; core control and shutdown; reflector and core support; maintenance and availability; safety aspects of PBR and prismatic comparison; PCRV dimensions; and fuel reprocessing cost estimate

  16. 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

  17. Coagulant recovery from water treatment plant sludge and reuse in post-treatment of UASB reactor effluent treating municipal wastewater.

    Science.gov (United States)

    Nair, Abhilash T; Ahammed, M Mansoor

    2014-09-01

    In the present study, feasibility of recovering the coagulant from water treatment plant sludge with sulphuric acid and reusing it in post-treatment of upflow anaerobic sludge blanket (UASB) reactor effluent treating municipal wastewater were studied. The optimum conditions for coagulant recovery from water treatment plant sludge were investigated using response surface methodology (RSM). Sludge obtained from plants that use polyaluminium chloride (PACl) and alum coagulant was utilised for the study. Effect of three variables, pH, solid content and mixing time was studied using a Box-Behnken statistical experimental design. RSM model was developed based on the experimental aluminium recovery, and the response plots were developed. Results of the study showed significant effects of all the three variables and their interactions in the recovery process. The optimum aluminium recovery of 73.26 and 62.73 % from PACl sludge and alum sludge, respectively, was obtained at pH of 2.0, solid content of 0.5 % and mixing time of 30 min. The recovered coagulant solution had elevated concentrations of certain metals and chemical oxygen demand (COD) which raised concern about its reuse potential in water treatment. Hence, the coagulant recovered from PACl sludge was reused as coagulant for post-treatment of UASB reactor effluent treating municipal wastewater. The recovered coagulant gave 71 % COD, 80 % turbidity, 89 % phosphate, 77 % suspended solids and 99.5 % total coliform removal at 25 mg Al/L. Fresh PACl also gave similar performance but at higher dose of 40 mg Al/L. The results suggest that coagulant can be recovered from water treatment plant sludge and can be used to treat UASB reactor effluent treating municipal wastewater which can reduce the consumption of fresh coagulant in wastewater treatment.

  18. Thermal-hydraulic analysis techniques for axisymmetric pebble bed nuclear reactor cores

    International Nuclear Information System (INIS)

    Stroh, K.R.

    1979-03-01

    The pebble bed reactor's cylindrical core volume contains a random bed of small, spherical fuel-moderator elements. These graphite spheres, containing a central region of dispersed coated-particle fissile and fertile material, are cooled by high pressure helium flowing through the connected interstitial voids. A mathematical model and numerical solution technique have been developed which allow calculation of macroscopic values of thermal-hydraulic variables in an axisymmetric pebble bed nuclear reactor core. The computer program PEBBLE is based on a mathematical model which treats the bed macroscopically as a generating, conducting porous medium. The steady-state model uses a nonlinear Forchheimer-type relation between the coolant pressure gradient and mass flux, with newly derived coefficients for the linear and quadratic resistance terms. The remaining equations in the model make use of mass continuity, and thermal energy balances for the solid and fluid phases

  19. The effects of baffles and gas superficial velocity on a bubble fluidized bed reactor's applications

    International Nuclear Information System (INIS)

    Ghorbanpour, A.; Ghannadi Maragheh, M.; Mallah, M. H.

    2008-01-01

    Baffles are used for decreasing bubbles diameter in order to increase the conversion rate along the bubbling fluidized bed reactors. The appearance of this phenomenon is due to bursting of the bubbles during the pass of bubbles from baffles. In this work, a computerized modeling and simulation have been performed in order to obtain a fundamental knowledge of the influence of the baffles on the bubble diameter and the specific mass transfer area. The height of the bed is 5 meters and its diameter is 0.3 meter. Baffles are located at 1 and 2 meters from the bottom of the bed. A two phase model together with a comprehensive fluid dynamical description of bubbling fluidized is presented. The effects of baffles and gas superficial velocity on the operating behavior of fluidized bed reactors are considered. The results are compared to the previously reported documents, and the experiments which have been carried out. MATLAB software is used in this simulation

  20. Thermal denitrification of evaporators concentrates in reactor with fluidized bed

    International Nuclear Information System (INIS)

    Brugnot, C.

    1993-11-01

    As part of the treatments of liquid wastes coming from the Marcoule reprocessing plant, the study of a thermal denitrification process for evaporator concentrates has been chosen by the CEA/CEN Cadarache: the fluidized-bed calcination. This work presents the study of a calcination pilot-plant for wastes with a very high sodium nitrate content. After a reactional analysis carried out in a thermobalance on samples which are representative of the fluidized-bed compounds, the perfecting of many of the plant parameters - such as the solution injection system - was carried out on a scale-model at first. Then, it was verified on the pilot-plant, and some experiments have been carried out. A mathematical model for the particle growth inside the fluidized-bed is proposed. (author). 179 refs., 65 figs., 23 tabs

  1. Simulation of petcoke gasification in slagging moving bed reactors

    Energy Technology Data Exchange (ETDEWEB)

    Nagpal, Soumitro; Sarkar, T.K.; Sen, P.K. [Research and Development Center, Engineers India Limited, Gurgaon 122001 (India)

    2005-03-25

    A mathematical model for simulation of moving bed petcoke gasifiers was developed. The model introduces a new feed characterization method, gas-phase resistance and volatilization models. The model is validated using reported data for a slagging gasifier. Effect of feed oxygen-to-coke and steam-to-coke ratios and feed coke rates on gasification performance was examined. Slagging zone moving bed gasifier operation with very high petcoke fluxes of over 4000 kg/m{sup 2}/h was possible with high petcoke conversion. Peak gas temperatures exceeded 1500 {sup o}C. Fluxes higher than 5000 kg/m{sup 2}/h are limited by an approach to fluidization of small particles in the combustion zone. The moving bed gasifier performance was found superior to performance of an entrained flow gasifier (EFG) with respect to energy efficiency and oxygen consumption.

  2. Organics removal from landfill leachate and activated sludge production in SBR reactors

    International Nuclear Information System (INIS)

    Klimiuk, Ewa; Kulikowska, Dorota

    2006-01-01

    This study is aimed at estimating organic compounds removal and sludge production in SBR during treatment of landfill leachate. Four series were performed. At each series, experiments were carried out at the hydraulic retention time (HRT) of 12, 6, 3 and 2 d. The series varied in SBR filling strategies, duration of the mixing and aeration phases, and the sludge age. In series 1 and 2 (a short filling period, mixing and aeration phases in the operating cycle), the relationship between organics concentration (COD) in the leachate treated and HRT was pseudo-first-order kinetics. In series 3 (with mixing and aeration phases) and series 4 (only aeration phase) with leachate supplied by means of a peristaltic pump for 4 h of the cycle (filling during reaction period) - this relationship was zero-order kinetics. Activated sludge production expressed as the observed coefficient of biomass production (Y obs ) decreased correspondingly with increasing HRT. The smallest differences between reactors were observed in series 3 in which Y obs was almost stable (0.55-0.6 mg VSS/mg COD). The elimination of the mixing phase in the cycle (series 4) caused the Y obs to decrease significantly from 0.32 mg VSS/mg COD at HRT 2 d to 0.04 mg VSS/mg COD at HRT 12 d. The theoretical yield coefficient Y accounted for 0.534 mg VSS/mg COD (series 1) and 0.583 mg VSS/mg COD (series 2). In series 3 and 4, it was almost stable (0.628 mg VSS/mg COD and 0.616 mg VSS/mg COD, respectively). After the elimination of the mixing phase in the operating cycle, the specific biomass decay rate increased from 0.006 d -1 (series 3) to 0.032 d -1 (series 4). The operating conditions employing mixing/aeration or only aeration phases enable regulation of the sludge production. The SBRs operated under aerobic conditions are more favourable at a short hydraulic retention time. At long hydraulic retention time, it can lead to a decrease in biomass concentration in the SBR as a result of cell decay. On the contrary

  3. Thermo-catalytic pyrolysis of waste polyethylene bottles in a packed bed reactor with different bed materials and catalysts

    International Nuclear Information System (INIS)

    Obeid, Farah; Zeaiter, Joseph; Al-Muhtaseb, Ala’a H.; Bouhadir, Kamal

    2014-01-01

    Highlights: • Thermo-catalytic pyrolysis of waste polyethylene bottles was investigated. • The highest yield of liquid (82%) was obtained over a cement powder bed. • Acidic catalysts narrowed the carbon chain length of the paraffins to C 10 –C 28 . • Combination of cement bed with HBeta catalyst gave the highest yield of liquid. • Significant yield of aromatics was obtained mainly naphthalene and D-limonene. - Abstract: Plastic waste is an increasing economic and environmental problem as such there is a great need to process this waste and reduce its environmental impact. In this work, the pyrolysis of high density polyethylene (HDPE) waste products was investigated using both thermal and catalytic cracking techniques. The experimental work was carried out using packed bed reactor operating under an inert atmosphere at 450 °C. Different reactor bed materials, including sand, cement and white clay were used to enhance the thermal cracking of HDPE. In addition, the catalytic effect of sodium hydroxide, HUSY and HBeta zeolite catalysts on the degradation of HDPE waste was also investigated. The reactor beds were found to significantly alter the yield as well as the product composition. Products such as paraffins (⩽C 44 ), olefins (⩽C 22 ), aromatics (⩽C 14 ) and alcohols (C 16 and C 17 ) were obtained at varying rates. The highest yield of liquid (82%) was obtained over a cement powder bed with a paraffin yield of 58%. The yield of paraffins and olefins followed separate paths, for paraffins it was found to increase in the order or Cement > White clay > Silica Sand, whereas for the olefins it was in the reverse order Silica Sand > White clay > Cement. The results obtained in this work exhibited a higher P/O ratio than expected, where the amount of generated paraffins was greater than 60% in most cases. Less olefin was generated as a consequence. This indicates that the product generated is more suited to be used as a fuel rather than as a chemical

  4. Pellet bed reactor for nuclear propelled vehicles: Part 2: Missions and vehicle integration trades

    International Nuclear Information System (INIS)

    Haloulakos, V.E.

    1991-01-01

    Mission and vehicle integration tradeoffs involving the use of the pellet bed reactor (PBR) for nuclear powered vehicles is discussed, with much of the information being given in viewgraph form. Information is given on propellant tank geometries, shield weight requirements for conventional tank configurations, effective specific impulse, radiation mapping, radiation dose rate after shutdown, space transfer vehicle design data, a Mars mission summary, sample pellet bed nuclear orbit transfer vehicle mass breakdown, and payload fraction vs. velocity increment

  5. Pellet bed reactor for nuclear propelled vehicles: Part 2: Missions and vehicle integration trades

    Science.gov (United States)

    Haloulakos, V. E.

    1991-01-01

    Mission and vehicle integration tradeoffs involving the use of the pellet bed reactor (PBR) for nuclear powered vehicles is discussed, with much of the information being given in viewgraph form. Information is given on propellant tank geometries, shield weight requirements for conventional tank configurations, effective specific impulse, radiation mapping, radiation dose rate after shutdown, space transfer vehicle design data, a Mars mission summary, sample pellet bed nuclear orbit transfer vehicle mass breakdown, and payload fraction vs. velocity increment.

  6. Rotary Bed Reactor for Chemical-Looping Combustion with Carbon Capture. Part 1: Reactor Design and Model Development

    KAUST Repository

    Zhao, Zhenlong; Chen, Tianjiao; Ghoniem, Ahmed F.

    2013-01-01

    Chemical-looping combustion (CLC) is a novel and promising technology for power generation with inherent CO2 capture. Currently, almost all of the research has been focused on developing CLC-based interconnected fluidized-bed reactors. In this two

  7. Chemical looping reforming in packed-bed reactors : modelling, experimental validation and large-scale reactor design

    NARCIS (Netherlands)

    Spallina, V.; Marinello, B.; Gallucci, F.; Romano, M.C.; van Sint Annaland, M.

    This paper addresses the experimental demonstration and model validation of chemical looping reforming in dynamically operated packed-bed reactors for the production of H2 or CH3OH with integrated CO2 capture. This process is a combination of auto-thermal and steam methane reforming and is carried

  8. Effect of temperature, hydraulic residence time and elevated PCO2 on acid neutralization within a pulsed limestone bed reactor

    Science.gov (United States)

    Watten, B.J.; Lee, P.C.; Sibrell, P.L.; Timmons, M.B.

    2007-01-01

    Limestone has potential for reducing reagent costs and sludge volume associated with treatment of acid mine drainage, but its use is restricted by slow dissolution rates and the deposition of Fe, Al and Mn-based hydrolysis products on reactive surfaces. We evaluated a pulsed limestone bed (PLB) reactor (15 L/min capacity) that uses a CO2 pretreatment step to accelerate dissolution and hydraulic shearing forces provided by intermittent fluidization to abrade and carry away surface scales. We established the effects of hydraulic residence time (HRT, 5.1-15.9 min), temperature (T, 12-22 ??C) and CO2 tension (PCO2, 34.5-206.8 kPa) on effluent quality when inlet acidity (Acy) was fixed at 440 mg/L (pH=2.48) with H2SO4. The PLB reactor neutralized all H+ acidity (N=80) while concurrently providing unusually high levels of effluent alkalinity (247-1028 mg/L as CaCO3) that allow for side-stream treatment with blending. Alkalinity (Alk) yields rose with increases in PCO2, HRT and settled bed height (BH, cm) and decreased with T following the relationship (R2=0.926; p<0.001): (Alk)non-filtered=-548.726+33.571??(PCO2)0.5+33.671??(HRT)+7.734??(BH)-5.197??(T). Numerical modeling showed CO2 feed requirements for a target Alk yield decrease with increases in HRT, T and the efficiency of off-gas (CO2) recycling. ?? 2007 Elsevier Ltd. All rights reserved.

  9. Burnup performance of OTTO cycle pebble bed reactors with ROX fuel

    International Nuclear Information System (INIS)

    Ho, Hai Quan; Obara, Toru

    2015-01-01

    Highlights: • A 300 MW t Small Pebble Bed Reactor with Rock-like oxide fuel is proposed. • Using ROX fuel can achieve high discharged burnup of spent fuel. • High geological stability can be expected in direct disposal of the spent ROX fuel. • The Pebble Bed Reactor with ROX fuel can be critical at steady state operation. • All the reactor designs have a negative temperature coefficient. - Abstract: A pebble bed high-temperature gas-cooled reactor (PBR) with rock-like oxide (ROX) fuel was designed to achieve high discharged burnup and improve the integrity of the spent fuel in geological disposal. The MCPBR code with a JENDL-4.0 library, which developed the analysis of the Once-Through-Then-Out (OTTO) cycle in PBR, was used to perform the criticality and burnup analysis. Burnup calculations for eight cases were carried out for both ROX fuel and a UO 2 fuel reactor with different heavy-metal loading conditions. The effective multiplication factor of all cases approximately equalled unity in the equilibrium condition. The ROX fuel reactor showed lower FIFA than the UO 2 fuel reactor at the same heavy-metal loading, about 5–15%. However, the power peaking factor and maximum power per fuel ball in the ROX fuel core were lower than that of UO 2 fuel core. This effect makes it possible to compensate for the lower-FIFA disadvantage in a ROX fuel core. All reactor designs had a negative temperature coefficient that is needed for the passive safety features of a pebble bed reactor

  10. Comparison of Several Thermal Conductivity Constants for Thermal Hydraulic Calculation of Pebble Bed Reactor

    Science.gov (United States)

    Irwanto, Dwi; Setiadipura, Topan; Pramutadi, Asril

    2017-07-01

    There are two type of High Temperature Gas Reactor (HTGR), prismatic and pebble bed. Pebble Bed type has unique configuration because the fuels are randomly distributed inside the reactor core. In term of safety features, Pebble Bed Reactor (PBR) is one of the most promising reactor type in avoiding severe nuclear accidents. In order to analyze heat transfer and safety of this reactor type, a computer code is now under development. As a first step, calculation method proposed by Stroh [1] is adopted. An approach has been made to treat randomly distributed pebble balls contains fissile material inside the reactor core as a porous medium. Helium gas act as coolant on the reactor system are carrying heat flowing in the area between the pebble balls. Several parameters and constants are taken into account in the new developed code. Progress of the development of the code especially comparison of several thermal conductivity constants for a certain PBR-case are reported in the present study.

  11. Gasification of Coal and PET in Fluidized Bed Reactor

    Czech Academy of Sciences Publication Activity Database

    Pohořelý, Michael; Vosecký, Martin; Kameníková, Petra; Punčochář, Miroslav; Skoblia, Sergej; Staf, M.; Vošta, J.; Koutský, B.; Svoboda, Karel

    2006-01-01

    Roč. 85, 17-18 (2006), s. 2458-2468 ISSN 0016-2361 R&D Projects: GA ČR(CZ) GA104/04/0829 Institutional research plan: CEZ:AV0Z40720504 Keywords : fludized bed * gasification * plastic waste Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.358, year: 2006

  12. Styrene biofiltration in a trickle-bed reactor

    Directory of Open Access Journals (Sweden)

    V. Novak

    2008-04-01

    Full Text Available The biological treatment of styrene waste gas in a trickle-bed filter (TBF was investigated. The bioreactor consisted of a two-part glass cylinder (ID 150 mm filled with 25 mm polypropylene Pall rings serving as packing material. The bed height was 1m. Although the laboratory temperature was maintained at 22 ºC, the water temperature in the trickle-bed filter was slightly lower (about 18 ºC.The main aim of our study was to observe the effect of empty-bed residence time (EBRT on bioreactor performance at a constant pollutant concentration over an extended time period. The bioreactor was inoculated with a mixed microbial consortium isolated from a styrene-degrading biofilter that had been running for the previous two years. After three weeks of acclimation period, the bioreactor was loaded with styrene (100 mg.m-3. EBRT was in the range of 53 s to 13 s. A maximum elimination capacity (EC of 11.3 gC.m-3.h-1 was reached at an organic loading (OL rate of 18.6 gC.m-3.h-1.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-12-15

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

  14. Removal of pharmaceuticals, polybrominated flame retardants and UV-filters from sludge by the fungus Trametes versicolor in bioslurry reactor

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Rodriguez, Carlos E. [Unitat Asociada de Biocatalisi Aplicada IQAC-CSIC, Escola d' Enginyeria, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain); Centro de Investigacion en Contaminacion Ambiental, Universidad de Costa Rica, 2060 San Jose (Costa Rica); Baron, Enrique; Gago-Ferrero, Pablo; Jelic, Aleksandra; Llorca, Marta; Farre, Marinella; Diaz-Cruz, M. Silvia; Eljarrat, Ethel [Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA), Spanish Council for Scientific Research (CSIC), Jordi Girona 18-26, 08034 Barcelona (Spain); Petrovic, Mira [Institucio Catalana de Reserca i Estudis Avancats (ICREA), Passeig Lluis Companys 23, 80010 Barcelona (Spain); Catalan Institute for Water Research (ICRA), H2O Building, Scientific and Technological Park of the University of Girona, 101-E-17003 Girona (Spain); Caminal, Gloria, E-mail: Gloria.Caminal@uab.cat [Unitat Asociada de Biocatalisi Aplicada IQAC-CSIC, Escola d' Enginyeria, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain); Barcelo, Damia [Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research (IDAEA), Spanish Council for Scientific Research (CSIC), Jordi Girona 18-26, 08034 Barcelona (Spain); Catalan Institute for Water Research (ICRA), H2O Building, Scientific and Technological Park of the University of Girona, 101-E-17003 Girona (Spain); King Saud University (KSU), P.O. Box 2455, 11451 Riyadh (Saudi Arabia); and others

    2012-09-30

    Highlights: Black-Right-Pointing-Pointer Sludge from a WWTP was treated in a fungal slurry reactor with Trametes versicolor. Black-Right-Pointing-Pointer Twenty-four pharmaceuticals were removed at important extents. Black-Right-Pointing-Pointer UV-filters and brominated flame retardants were also degraded. Black-Right-Pointing-Pointer Overall toxicity of sludge increased despite the pollutant removal. - Abstract: Conventional wastewater treatments are inefficient in the removal of many organic pollutants. The presence of these contaminants in the final sludge represents a source of environmental pollution due to the increasing use of biosolids in land application. A biotechnological approach which employed the fungus Trametes versicolor in a sludge-bioslurry reactor was assessed in order to remove several groups of emerging pollutants. Biological fungal activity was monitored by means of ergosterol and laccase determinations. Fifteen out of 24 detected pharmaceuticals were removed at efficiencies over 50% after the treatment, including eight completely degraded. Removal ranged between 16-53% and 22-100% for the brominated flame retardants and the UV-filters, respectively. Only two of all the detected compounds remained unchanged after the treatment. Although elimination results are promising, the toxicity of the final sludge increased after the treatment. This finding is contrary to the toxicity results obtained in similar treatments of sludge with T. versicolor in solid-phase.

  15. Removal of pharmaceuticals, polybrominated flame retardants and UV-filters from sludge by the fungus Trametes versicolor in bioslurry reactor

    International Nuclear Information System (INIS)

    Rodríguez-Rodríguez, Carlos E.; Barón, Enrique; Gago-Ferrero, Pablo; Jelić, Aleksandra; Llorca, Marta; Farré, Marinella; Díaz-Cruz, M. Silvia; Eljarrat, Ethel; Petrović, Mira; Caminal, Glòria; Barceló, Damià

    2012-01-01

    Highlights: ► Sludge from a WWTP was treated in a fungal slurry reactor with Trametes versicolor. ► Twenty-four pharmaceuticals were removed at important extents. ► UV-filters and brominated flame retardants were also degraded. ► Overall toxicity of sludge increased despite the pollutant removal. - Abstract: Conventional wastewater treatments are inefficient in the removal of many organic pollutants. The presence of these contaminants in the final sludge represents a source of environmental pollution due to the increasing use of biosolids in land application. A biotechnological approach which employed the fungus Trametes versicolor in a sludge-bioslurry reactor was assessed in order to remove several groups of emerging pollutants. Biological fungal activity was monitored by means of ergosterol and laccase determinations. Fifteen out of 24 detected pharmaceuticals were removed at efficiencies over 50% after the treatment, including eight completely degraded. Removal ranged between 16–53% and 22–100% for the brominated flame retardants and the UV-filters, respectively. Only two of all the detected compounds remained unchanged after the treatment. Although elimination results are promising, the toxicity of the final sludge increased after the treatment. This finding is contrary to the toxicity results obtained in similar treatments of sludge with T. versicolor in solid-phase.

  16. Treatment of high-strength synthetic sewage in a laboratory-scale upflow anaerobic sludge bed (UASB) with aerobic activated sludge (AS) post-treatment.

    Science.gov (United States)

    Banihani, Qais H; Field, Jim A

    2013-01-01

    Performance of a combined system up-flow anaerobic sludge blanket (UASB) followed by aerobic treatment activated sludge (AS) for removal of carbonaceous and nitrogenous contaminants at an average temperature of 25°C was investigated. The combined system was fed with high strength synthetic sewage having chemical oxygen demand (COD) of 2500 mg L(-1). The organic loading rate (OLR) of the UASB reactor was increased gradually from 1.1 to 3.8 gCOD L(r) (-1) d(-1). At steady state condition, the UASB reactor achieved removal efficiency up to 83.5% of total COD (COD(tot)), 74.0% of volatile fatty acid (VFA) and 94.0% of protein. The combined system performed an excellent organic removal pushing the overall removal efficiency of COD(tot), VFA and protein to 91.0%, 99.9% and 98.2%, respectively. When the OLR of the UASB increased to 4.4 g COD L(r) (-1) d(-1), the UASB was overloaded and; thus, its effluent quality deteriorated. In respect to nitrogen removal, both partial nitrification and complete nitrification took place in aerobic post-treatment. When the dissolved oxygen (DO) concentration was >2.0 mg L(-1), complete nitrification (period B) occurred with an average nitrification efficiency of 96.2%. The partial nitrification occurred due to high OLR to AS during the overloading event (period A) and when DO concentration was <2.0 mg L(-1) (period C). The maximum accumulated nitrite concentration in periods A, B and C were 90.0, 0.9 and 75.8 mg NO(-) (2) -N L(-1), respectively. The nitrogen balance results of periods A and C indicated that there was a discrepancy between the amount of ammonium nitrogen removed and the amount of oxidized nitrogen formed. This suggests the occurrence of simultaneous nitrification/denitrification (SND) in aerobic post-treatment.

  17. The behaviour of ashes and heavy metals during the co-combustion of sewage sludges in a fluidised bed.

    Science.gov (United States)

    Helena Lopes, M; Abelha, P; Lapa, N; Oliveira, J S; Cabrita, I; Gulyurtlu, I

    2003-01-01

    Co-combustion tests of dry sewage sludges with coal were performed in a pilot bubbling FBC aiming at the characterization of ashes and determining the behaviour of heavy metals in the process. The tests showed compliance with the regulatory levels as far as heavy metal emissions were concerned. The bottom ashes, which accounted for about 70% of the total ash production, were obtained in a granular form, with diameters ranging from 0.5 to 4 mm. The heavy metals were distributed in ashes obtained from different locations of the installation and their concentrations were found to vary depending on the location of capture. The increase in heavy metals content in bottom ashes was not found to lead to higher leachability and ecotoxicity compared to sewage sludges, suggesting that there could be opportunities for their further use. Mercury suffered vaporisation inside the reactor, thus leaving bottom ashes free of contamination by it. However, there was observed a strong retention of mercury in cyclone ashes due to the presence of unburned carbon which probably acted as an adsorbent. The effluent mercury was also found to be mostly associated with the particulate fraction, being less than 20% emitted in gaseous forms. The results suggested that the combustion of the sewage sludge could successfully be carried out and the amount of unburned carbon leaving the combustor but captured in cyclone was large enough to ensure substantial retention of mercury at low temperatures, hence could contribute to an improvement of the mercury release which still remains an issue of great concern to resolve during combustion of waste materials.

  18. The behaviour of ashes and heavy metals during the co-combustion of sewage sludges in a fluidised bed

    International Nuclear Information System (INIS)

    Helena Lopes, M.; Abelha, P.; Lapa, N.; Oliveira, J.S.; Cabrita, I.; Gulyurtlu, I.

    2003-01-01

    Co-combustion tests of dry sewage sludges with coal were performed in a pilot bubbling FBC aiming at the characterization of ashes and determining the behaviour of heavy metals in the process. The tests showed compliance with the regulatory levels as far as heavy metal emissions were concerned. The bottom ashes, which accounted for about 70% of the total ash production, were obtained in a granular form, with diameters ranging from 0.5 to 4 mm. The heavy metals were distributed in ashes obtained from different locations of the installation and their concentrations were found to vary depending on the location of capture. The increase in heavy metals content in bottom ashes was not found to lead to higher leachability and ecotoxicity compared to sewage sludges, suggesting that there could be opportunities for their further use. Mercury suffered vaporisation inside the reactor, thus leaving bottom ashes free of contamination by it. However, there was observed a strong retention of mercury in cyclone ashes due to the presence of unburned carbon which probably acted as an adsorbent. The effluent mercury was also found to be mostly associated with the particulate fraction, being less than 20% emitted in gaseous forms. The results suggested that the combustion of the sewage sludge could successfully be carried out and the amount of unburned carbon leaving the combustor but captured in cyclone was large enough to ensure substantial retention of mercury at low temperatures, hence could contribute to an improvement of the mercury release which still remains an issue of great concern to resolve during combustion of waste materials

  19. Domestic sewage sludge composting in a rotary drum reactor: optimizing the thermophilic stage.

    Science.gov (United States)

    Rodríguez, Luis; Cerrillo, María I; García-Albiach, Valentín; Villaseñor, José

    2012-12-15

    The aim of this paper was to study the influence of four process variables (turning frequency, gas-phase oxygen level, type of bulking agent and sludge/bulking agent mixing ratio) on the performance of the sewage sludge composting process using a rotary drum pilot scale reactor, in order to optimize the thermophilic stage and reduce the processing time. Powdered sawdust, wood shavings, wood chips, prunings waste and straw were used as bulking agents and the thermophilic stage temperature profile was used as the main indicator for gauging if the composting process was developing correctly. Our results showed that a 12 h(-1) turning frequency and an oxygen concentration of 10% were the optimal conditions for the composting process to develop. The best results were obtained by mixing the sewage sludge with wood shavings in a 3:1 w/w ratio (on a wet basis), which adapted the initial moisture content and porosity to an optimal range and led to a maximum temperature of 70 °C being reached thus ensuring the complete removal of pathogens. Moisture, C:N ratio, pH, organic matter, heavy metals, pathogens and stability were all analysed for every mixture obtained at the end of the thermophilic stage. These parameters were compared with the limits established by the Spanish regulation on fertilizers (RD 824/2005) in order to assess if the compost obtained could be used on agricultural soils. The right combination of having optimal process variables combined with an appropriate reactor design allowed the thermophilic stage of the composting process to be speeded up, hence obtaining a compost product, after just two weeks of processing that (with the exception of the moisture content) complied with the Spanish legal requirements for fertilizers, without requiring a later maturation stage. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. Determination of pressure distribution in an aerated bed in a controlled pilot-scale compost reactor

    Energy Technology Data Exchange (ETDEWEB)

    Solowiej, P. [Warmia and Mazury Univ., Olsztyn (Poland)

    2010-07-01

    This study investigated the effectiveness of dealing with biological waste by composting. In particular, it examined the feasibility of recovering excess thermal energy produced in the process of composting biological waste in terms of mass and energy transport parameters required in the aerated compost bed. An experiment was performed in which a 100 dm{sup 3} adiabatic, leak-tight reactor equipped with a controlled aeration system was constructed to study the temperature and pressure distribution in the bed. Sensors were used to determine the amount and humidity of emitted gases under variable external physical conditions. The perforated bottom of the reactor allowed for bed aeration. As such, the humidity and heat were transported upwards, forced by the air pumped in and by natural convection. In terms of pressure distribution inside the composted and aerated bed, the study results showed that there were considerable differences in pressure for the selected places of the bed of the composted biological material. An increase in upwards pressure was observed in the heap throughout the experiment. Pressure differences in the same plane of the bed were also noted. The study results should facilitate the development of a model of mass and energy transport in a bed of composted material.

  1. Immobilization of biogenic Pd(0) in anaerobic granular sludge for the biotransformation of recalcitrant halogenated pollutants in UASB reactors.

    Science.gov (United States)

    Pat-Espadas, Aurora M; Razo-Flores, Elías; Rangel-Mendez, J Rene; Ascacio-Valdes, Juan A; Aguilar, Cristobal N; Cervantes, Francisco J

    2015-10-19

    The capacity of anaerobic granular sludge to reduce Pd(II), using ethanol as electron donor, in an upflow anaerobic sludge blanket (UASB) reactor was demonstrated. Results confirmed complete reduction of Pd(II) and immobilization as Pd(0) in the granular sludge. The Pd-enriched sludge was further evaluated regarding biotransformation of two recalcitrant halogenated pollutants: 3-chloro-nitrobenzene (3-CNB) and iopromide (IOP) in batch and continuous operation in UASB reactors. The superior removal capacity of the Pd-enriched biomass when compared with the control (not exposed to Pd) was demonstrated in both cases. Results revealed 80 % of IOP removal efficiency after 100 h of incubation in batch experiments performed with Pd-enriched biomass whereas only 28 % of removal efficiency was achieved in incubations with biomass lacking Pd. The UASB reactor operated with the Pd-enriched biomass achieved 81 ± 9.5 % removal efficiency of IOP and only 61 ± 8.3 % occurred in the control reactor lacking Pd. Regarding 3-CNB, it was demonstrated that biogenic Pd(0) promoted both nitro-reduction and dehalogenation resulting in the complete conversion of 3-CNB to aniline while in the control experiment only nitro-reduction was documented. The complete biotransformation pathway of both contaminants was proposed by high-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis evidencing a higher degree of nitro-reduction and dehalogenation of both contaminants in the experiments with Pd-enriched anaerobic sludge as compared with the control. A biotechnological process is proposed to recover Pd(II) from industrial streams and to immobilize it in anaerobic granular sludge. The Pd-enriched biomass is also proposed as a biocatalyst to achieve the biotransformation of recalcitrant compounds in UASB reactors.

  2. Discussion on Design Transients of Pebble-bed High Temperature Gas-cooled Reactor

    International Nuclear Information System (INIS)

    Wang Yan; Li Fu; Zheng Yanhua

    2014-01-01

    In order to assure high quality for the components and their supports in the reactor coolant system, etc., some thermal-hydraulic transient conditions will be selected and researched for equipment design evaluation to satisfy the requirements ASME code, which are based on the conservative estimates of the magnitude and frequency of the temperature and pressure transients resulting from various operating conditions in the plant. In the mature design on pressurized water reactor, five conditions are considered. For the developing advanced pebble-bed high temperature gas-cooled reactor(HTGR), its design and operation has much difference with other reactors, so the transients of the pebble-bed high temperature gas-cooled reactor have distinctive characteristics. In this paper, the possible design transients of the pebble-bed HTGR will be discussed, and the frequency of design transients for equipment fatigue analysis and stress analysis due to cyclic stresses is also studied. The results will provide support for the design and construct of the pebble-bed HTGR. (author)

  3. Air gasification of rice husk in bubbling fluidized bed reactor with bed heating by conventional charcoal.

    Science.gov (United States)

    Makwana, J P; Joshi, Asim Kumar; Athawale, Gaurav; Singh, Dharminder; Mohanty, Pravakar

    2015-02-01

    An experimental study of air gasification of rice husk was conducted in a bench-scale fluidized bed gasifier (FBG) having 210 mm diameter and 1600 mm height. Heating of sand bed material was performed using conventional charcoal fuel. Different operating conditions like bed temperature, feeding rate and equivalence ratio (ER) varied in the range of 750-850 °C, 25-31.3 kg/h, and 0.3-0.38, respectively. Flow rate of air was kept constant (37 m(3)/h) during FBG experiments. The carbon conversion efficiencies (CCE), cold gas efficiency, and thermal efficiency were evaluated, where maximum CCE was found as 91%. By increasing ER, the carbon conversion efficiency was decreased. Drastic reduction in electric consumption for initial heating of gasifier bed with charcoal compared to ceramic heater was ∼45%. Hence rice husk is found as a potential candidate to use directly (without any processing) in FBG as an alternative renewable energy source from agricultural field. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. 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.

  5. Start-Up Characteristics of a Granule-Based Anammox UASB Reactor Seeded with Anaerobic Granular Sludge

    Directory of Open Access Journals (Sweden)

    Lei Xiong

    2013-01-01

    Full Text Available The granulation of anammox sludge plays an important role in the high nitrogen removal performance of the anammox reactor. In this study, anaerobic granular sludge was selected as the seeding sludge to start up anammox reactor in order to directly obtain anammox granules. Results showed that the anammox UASB reactor was successfully started up by inoculating anaerobic granular sludge, with substrate capacity of 4435.2 mg/(L·d and average ammonium and nitrite removal efficiency of 90.36% and 93.29%, respectively. During the start-up course, the granular sludge initially disintegrated and then reaggregated and turned red, suggesting the high anammox performance. Zn-Fe precipitation was observed on the surface of granules during the operation by SEM-EDS, which would impose inhibition to the anammox activity of the granules. Accordingly, it is suggested to relatively reduce the trace metals concentrations, of Fe and Zn in the conventional medium. The findings of this study are expected to be used for a shorter start-up and more stable operation of anammox system.

  6. Start-Up Characteristics of a Granule-Based Anammox UASB Reactor Seeded with Anaerobic Granular Sludge

    Science.gov (United States)

    Wang, Yun-Yan; Tang, Chong-Jian; Chai, Li-Yuan; Xu, Kang-Que; Song, Yu-Xia

    2013-01-01

    The granulation of anammox sludge plays an important role in the high nitrogen removal performance of the anammox reactor. In this study, anaerobic granular sludge was selected as the seeding sludge to start up anammox reactor in order to directly obtain anammox granules. Results showed that the anammox UASB reactor was successfully started up by inoculating anaerobic granular sludge, with substrate capacity of 4435.2 mg/(L·d) and average ammonium and nitrite removal efficiency of 90.36% and 93.29%, respectively. During the start-up course, the granular sludge initially disintegrated and then reaggregated and turned red, suggesting the high anammox performance. Zn-Fe precipitation was observed on the surface of granules during the operation by SEM-EDS, which would impose inhibition to the anammox activity of the granules. Accordingly, it is suggested to relatively reduce the trace metals concentrations, of Fe and Zn in the conventional medium. The findings of this study are expected to be used for a shorter start-up and more stable operation of anammox system. PMID:24455691

  7. Design of a power conversion system for an indirect cycle, helium cooled pebble bed reactor system

    International Nuclear Information System (INIS)

    Wang, C.; Ballinger, R.G.; Stahle, P.W.; Demetri, E.; Koronowski, M.

    2002-01-01

    A design is presented for the turbomachinery for an indirect cycle, closed, helium cooled modular pebble bed reactor system. The design makes use of current technology and will operate with an overall efficiency of 45%. The design uses an intermediate heat exchanger which isolated the reactor cycle from the turbomachinery. This design excludes radioactive fission products from the turbomachinery. This minimizes the probability of an air ingress accident and greatly simplifies maintenance. (author)

  8. CFD Model of HDS Catalyst Tests in Trickle-Bed Reactor

    OpenAIRE

    Tukač, V.

    2014-01-01

    The goal of this study was to evaluate hydrodynamic influence on experimental HDS catalyst activity measurement carried out in pilot scale trickle-bed reactor. Hydrodynamic data were evaluated by RTD method in laboratory glass model of pilot reactor. Mathematical models of the process were formulated both like 1D pseudohomogeneou and 3D heterogeneous ones. The aim of this work was to forecast interaction between intrinsic reaction kinetic, hydrodynamics and mass transfer.

  9. Probabilistic safety assessment framework of pebble-bed modular high-temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Liu Tao; Tong Jiejuan; Zhao Jun; Cao Jianzhu; Zhang Liguo

    2009-01-01

    After an investigation of similar reactor type probabilistic safety assessment (PSA) framework, Pebble-bed Modular High-Temperature Gas-cooled Reactor (HTR-PM) PSA framework was presented in correlate with its own design characteristics. That is an integral framework which spreads through event sequence structure with initiating events at the beginning and source term categories in the end. The analysis shows that it is HTR-PM design feature that determines its PSA framework. (authors)

  10. Development of a safeguards system for the THTR pebble bed reactor

    International Nuclear Information System (INIS)

    Engelhardt, H.

    1978-08-01

    This report provides a survey of the technical possibilities of safeguarding the THTR-300 pebble bed reactor in accordance with the NPT. Description of the reactor system, the operational mode, and the operator's material control system are presented in Sections 2, 3 and 4. A suggested safeguards approach which is based on an item counting of pebble elements with containment and surveillance as a supplementary measure is described in the Sections 5 and 6

  11. Carbon Shale Combustion in the Fluidized Bed Reactor

    Directory of Open Access Journals (Sweden)

    Olek Małgorzata

    2014-06-01

    Full Text Available The purpose of this article is to present the possibilities of coal shale combustion in furnaces with bubbling fluidized bed. Coal shale can be autothermally combusted in the fluidized bed, despite the low calorie value and high ash content of fuel. Established concentrations of CO (500 ppm and VOC (30 mg/m3 have indicated a high conversion degree of combustible material during combustion process. Average concentrations of SO2 and NOx in the flue gas were higher than this received from the combustion of high quality hard coal, 600 ppm and 500 ppm, respectively. Optional reduction of SO2 and NOx emission may require the installation of flue gas desulphurization and de-NOx systems.

  12. Experimental, kinetic and numerical modeling of hydrogen production by catalytic reforming of crude ethanol over a commercial catalyst in packed bed tubular reactor and packed bed membrane reactor

    International Nuclear Information System (INIS)

    Aboudheir, Ahmed; Akande, Abayomi; Idem, Raphael

    2006-01-01

    The demand for hydrogen energy has increased tremendously in recent years essentially because of the increase in the word energy consumption as well as recent developments in fuel cell technologies. The energy information administration has projected that world energy consumption will increase by 59% over the next two decades, from 1999 to 2020, in which the largest share is still dominated by fossil fuels (oil, natural gas and coal). Carbon dioxide (CO 2 ) emissions resulting from the combustion of these fossil fuels currently are estimated to account for three-fourth of human-caused CO 2 emissions worldwide. Greenhouse gas emission, including CO 2 , should be limited, as recommended at the Kyoto Conference, Japan, in December 1997. In this regard, hydrogen (H 2 ) has a significant future potential as an alternative fuel that can solve the problems of CO 2 emissions as well as the emissions of other air contaminants. One of the techniques to produce hydrogen is by reforming of hydrocarbons or biomass. Crude ethanol (a form of biomass, which essentially is fermentation broth) is easy to produce, is free of sulphur, has low toxicity, and is also safe to handle, transport and store. In addition, crude ethanol consists of oxygenated hydrocarbons, such as ethanol, lactic acid, glycerol, and maltose. These oxygenated hydrocarbons can be reformed completely to H 2 and CO 2 , the latter of which could be separated from H 2 by membrane technology. This provides for CO 2 capture for eventual storage or destruction. In the case of using crude ethanol, this will result in negative CO 2 , emissions. In this paper, we conducted experimental work on production of hydrogen by the catalytic reforming of crude ethanol over a commercial promoted Ni-based catalyst in a packed bed tubular reactor as well as a packed bed membrane reactor. As well, a rigorous numerical model was developed to simulate this process in both the catalytic packed bed tubular reactor and packed bed membrane

  13. Efficient anaerobic treatment of synthetic textile wastewater in a UASB reactor with granular sludge enriched with humic acids supported on alumina nanoparticles.

    Science.gov (United States)

    Cervantes, Francisco J; Gómez, Rafael; Alvarez, Luis H; Martinez, Claudia M; Hernandez-Montoya, Virginia

    2015-07-01

    A novel technique to co-immobilize humus-reducing microorganisms and humic substances (HS), supported on γ-Al2O3 nanoparticles (NP), by a granulation process in an upflow anaerobic sludge bed (UASB) reactor is reported in the present work. Larger granules (predominantly between 1 and 1.7 mm) were produced using NP coated with HS compared to those obtained with uncoated NP (mostly between 0.25 and 0.5 mm). The HS-enriched granular biomass was then tested for its capacity to achieve the reductive decolorization of the recalcitrant azo dye, reactive red 2 (RR2), in the same UASB reactor operated with a hydraulic residence time of 12 h and with glucose as electron donor. HS-enriched granules achieved higher decolorization and COD removal efficiencies, as compared to the control reactor operated in the absence of HS, in long term operation and applying high concentrations of RR2 (40-400 mg/L). This co-immobilizing technique could be attractive for its application in UASB reactors for the reductive biotransformation of several contaminants, such as nitroaromatics, poly-halogenated compounds, metalloids, among others.

  14. Gasification of wood in a fluidized bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, L.C. de; Marti, T; Frankenhaeuser, M [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    A first series of gasification experiments with our fluidized bed gasifier was performed using clean sawdust as fuel. The installation and the analytical systems were tested in a parametric study in which gasification temperature and equivalence ratio were varied. The data acquired will serve to establish the differences between the gasification of clean wood and the gasification of Altholz (scrapwood) and wood/plastics mixtures. (author) 1 fig., 3 tabs., 5 refs.

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

    Directory of Open Access Journals (Sweden)

    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.

  16. Distributed secondary gas injection via a fractal injector : A nature-inspired approach to improving conversion in fluidized bed reactors

    NARCIS (Netherlands)

    Christensen, D.O.

    2008-01-01

    The conversion in bubbling fluidized bed reactors is suppressed because the interphase mass transfer and gas-solid contact in bubbling fluidized bed reactors are often poor. Most of the gas is present in the form of bubbles, which have low surface-to-volume ratios and are nearly devoid of catalyst

  17. Design and development of fluidized bed reactor system for production of trichlorosilane as a precursor for high purity silicon

    International Nuclear Information System (INIS)

    Kumar, Rajesh; Mohan, Sadhana; Bhanja, K.; Nayak, S.; Bhattacharya, S.K.

    2009-01-01

    Trichlorosilane is widely used as precursor material for production of high purity silicon. It is mainly produced by reaction of metallurgical grade silicon with anhydrous HCl gas in a fluidized bed reactor. To develop this process on commercial scale a pilot size fluidized bed reactor system was designed and developed and successfully operated. This paper discusses the critical issues related to these activities. (author)

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

    Directory of Open Access Journals (Sweden)

    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.

  19. Deposition reactors for solar grade silicon: A comparative thermal analysis of a Siemens reactor and a fluidized bed reactor

    Science.gov (United States)

    Ramos, A.; Filtvedt, W. O.; Lindholm, D.; Ramachandran, P. A.; Rodríguez, A.; del Cañizo, C.

    2015-12-01

    Polysilicon production costs contribute approximately to 25-33% of the overall cost of the solar panels and a similar fraction of the total energy invested in their fabrication. Understanding the energy losses and the behaviour of process temperature is an essential requirement as one moves forward to design and build large scale polysilicon manufacturing plants. In this paper we present thermal models for two processes for poly production, viz., the Siemens process using trichlorosilane (TCS) as precursor and the fluid bed process using silane (monosilane, MS). We validate the models with some experimental measurements on prototype laboratory reactors relating the temperature profiles to product quality. A model sensitivity analysis is also performed, and the effects of some key parameters such as reactor wall emissivity and gas distributor temperature, on temperature distribution and product quality are examined. The information presented in this paper is useful for further understanding of the strengths and weaknesses of both deposition technologies, and will help in optimal temperature profiling of these systems aiming at lowering production costs without compromising the solar cell quality.

  20. A Pebble-Bed Breed-and-Burn Reactor

    International Nuclear Information System (INIS)

    Greenspan, Ehud

    2016-01-01

    The primary objective of this project is to use three-dimensional fuel shuffling in order to reduce the minimum peak radiation damage of ~550 dpa present Breed-and-Burn (B&B) fast nuclear reactor cores designs (they feature 2-D fuel shuffling) call for to as close as possible to the presently accepted value of 200 dpa thereby enabling earlier commercialization of B&B reactors which could make substantial contribution to energy sustainability and economic stability without need for fuel recycling. Another objective is increasing the average discharge burnup for the same peak discharge burnup thereby (1) increasing the fuel utilization of 2-D shuffled B&B reactors and (2) reducing the reprocessing capacity required to support a given capacity of FRs that are to recycle fuel.

  1. A Pebble-Bed Breed-and-Burn Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Greenspan, Ehud [Univ. of California, Berkeley, CA (United States)

    2016-03-31

    The primary objective of this project is to use three-dimensional fuel shuffling in order to reduce the minimum peak radiation damage of ~550 dpa present Breed-and-Burn (B&B) fast nuclear reactor cores designs (they feature 2-D fuel shuffling) call for to as close as possible to the presently accepted value of 200 dpa thereby enabling earlier commercialization of B&B reactors which could make substantial contribution to energy sustainability and economic stability without need for fuel recycling. Another objective is increasing the average discharge burnup for the same peak discharge burnup thereby (1) increasing the fuel utilization of 2-D shuffled B&B reactors and (2) reducing the reprocessing capacity required to support a given capacity of FRs that are to recycle fuel.

  2. 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.

  3. Low temperature circulating fluidized bed gasification and co-gasification of municipal sewage sludge. Part 2: Evaluation of ash materials as phosphorus fertilizer

    DEFF Research Database (Denmark)

    Thomsen, Tobias Pape; Hauggaard-Nielsen, Henrik; Gøbel, Benny

    2017-01-01

    to the mono-sludge ashes, thereby showing the best fertilizer qualities among all assessed materials. It was also found that bottomashes from the char reactor contained even less heavy metals than cyclone ashes. It is concluded thatLT-CFB gasification and co-gasification is a highly effective way to purify...

  4. Continuosly Stirred Tank Reactor Parameters That Affect Sludge Batch 6 Simulant Properties

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  5. How to prevent runaways in trickle-bed reactors for Pygas hydrogenation

    NARCIS (Netherlands)

    Westerterp, K.R.; Kronberg, Alexandre E.

    2002-01-01

    In the past, several runaways have occurred in Trickle-Bed Reactors (TBR) used for the hydrogenation of pyrolysis gasoline as produced in ethylene cracking installations. This phenomenon has been studied in the framework of a special program in the Netherlands, which is administered by the National

  6. Optimized core design and fuel management of a pebble-bed type nuclear reactor

    NARCIS (Netherlands)

    Boer, B.

    2009-01-01

    The core design of a pebble-bed type Very High Temperature Reactor (VHTR) is optimized, aiming for an increase of the coolant outlet temperature to 1000 C, while retaining its inherent safety features. The VHTR has been selected by the international Generation IV research initiative as one of the

  7. Fast pyrolysis of biomass in a fluidized bed reactor: in-situ filtering of the vapors

    NARCIS (Netherlands)

    Hoekstra, E.; Hogendoorn, Kees; Wang, X.; Westerhof, Roel Johannes Maria; Kersten, Sascha R.A.; van Swaaij, Willibrordus Petrus Maria; Groeneveld, M.J.

    2009-01-01

    A system to remove in situ char/ash from hot pyrolysis vapors has been developed and tested at the University of Twente. The system consists of a continuous fluidized bed reactor (0.7 kg/h) with immersed filters (wire mesh, pore size 5 μm) for extracting pyrolysis vapors. Integration of the filter

  8. Nature and characteristics of pulsing flow in trickle-bed reactors

    NARCIS (Netherlands)

    Boelhouwer, J.G.; Piepers, H.W.; Drinkenburg, A.A.H.

    2002-01-01

    Pulsing flow is well known for its advantages in terms of an increase in mass and heat transfer rates, complete catalyst wetting and a decrease in axial dispersion compared to trickle flow. The operation of a trickle-bed reactor in the pulsing flow regime is favorable in terms of a capacity increase

  9. Enlargement of the pulsing flow regime by periodic operation of a trickle-bed reactor.

    NARCIS (Netherlands)

    Boelhouwer, J.G.; Piepers, H.W.; Drinkenburg, A.A.H.

    1999-01-01

    Potential advantages of pulsing flow in trickle-bed reactors include capacity increase and elimination of hot spots through the enhanced mass and heat transfer rates. A disadvantage of naturally occurring pulsing flow is the necessity of relatively high gas and liquid flow rates, especially at

  10. Application of point kinetic model in the study of fluidized bed reactor dynamic

    International Nuclear Information System (INIS)

    Borges, Volnei; Vilhena, Marco Tullio de; Streck, Elaine E.

    1995-01-01

    In this work the dynamical behavior of the fluidized bed nuclear reactor is analysed. The main goal consist to study the effect of the acceleration term in the point kinetic equations. Numerical simulations are reported considering constant acceleration. (author). 7 refs, 4 figs

  11. Fabrication of the fuel elements cladding for utilization in the fluidized bed nuclear reactor

    International Nuclear Information System (INIS)

    Schaeffer, L.; Sefidvash, F.

    1986-01-01

    A method for the fabrication of cladding of the spherical fuel elements for the utilization in the fluidized bed nuclear reactor is presented. Some prelimminary experiments were performed to adopt a method which adapt itself to mass production with the desired high quality. Still methods for cladding fabrication are under study. (Author) [pt

  12. Membrane assisted fluidized bed reactor: experimental demonstration for partial oxidation of methanol

    NARCIS (Netherlands)

    Deshmukh, S.A.R.K.

    2004-01-01

    In this thesis the reactor concept has been developed on the basis of an experimental study on the effect of fluidization conditions on the membrane permeation rate in a MAFBR, the extent of gas back mixing and the tube-to-bed heat transfer rates in the presence of membrane bundles with and without

  13. Modelling of an adiabatic trickle-bed reactor with phase change

    DEFF Research Database (Denmark)

    Ramirez Castelan, Carlos Eduardo; Hidalgo-Vivas, Angelica; Brix, Jacob

    2017-01-01

    This paper describes a modelling approach of the behavior of trickle-bed reactors used for catalytic hydrotreating of oil fractions. A dynamic plug-flow heterogeneous one-dimensional adiabatic model was used to describe the main reactions present in the hydrotreating process: hydrodesulfurization...

  14. CFD-DEM simulation of a conceptual gas-cooled fluidized bed nuclear reactor

    International Nuclear Information System (INIS)

    Almeida, Lucilla C.; Su, Jian

    2015-01-01

    Several conceptual designs of the fluidized-bed nuclear reactor have been proposed due to its many advantages over conventional nuclear reactors such as PWRs and BWRs. Amongst their characteristics, the enhanced heat transfer and mixing enables a more uniform temperature distribution, reducing the risk of hot-spot and excessive fuel temperature, in addition to resulting in a higher burnup of the fuel. Furthermore, the relationship between the bed height and reactor neutronics turns the coolant flow rate control into a power production mechanism. Moreover, the possibility of removing the fuel by gravity from the movable core in case of a loss-of-cooling accident increases its safety. High-accuracy modeling of particles and coolant flow in fluidized bed reactors is needed to evaluate reliably the thermal-hydraulic efficiency and safety margin. The two-way coupling between solid and fluid can account for high-fidelity solid-solid interaction and reasonable accuracy in fluid calculation and fluid-solid interaction. In the CFD-DEM model, the particles are modeled as a discrete phase, following the DEM approach, whereas the fluid flow is treated as a continuous phase, described by the averaged Navier-Stokes equations on a computational cell scale. In this work, the coupling methodology between Fluent and Rocky is described. The numerical approach was applied to the simulation of a bubbling fluidized bed and the results were compared to experimental data and showed good agreement. (author)

  15. Production of structured lipids in a packed-bed reactor with Thermomyces lanuginosa lipase

    DEFF Research Database (Denmark)

    Xu, Xuebing; Porsgaard, Trine; Zhang, Hong

    2002-01-01

    Lipase-catalyzed interesterification between fish oil and medium-chain TAG has been investigated in a packed-bed reactor with a commercially immobilized enzyme. The enzyme, a Thermomyces lanuginosa lipase immobilized on silica by granulation (Lipozyme TL IM; Novozymes A/S, Bagsvaerd, Denmark), ha...

  16. Consideration of emergency source terms for pebble-bed high temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Tao, Liu; Jun, Zhao; Jiejuan, Tong; Jianzhu, Cao

    2009-01-01

    Being the last barrier in the nuclear power plant defense-in-depth strategy, emergency planning (EP) is an integrated project. One of the key elements in this process is emergency source terms selection. Emergency Source terms for light water reactor (LWR) nuclear power plant (NPP) have been introduced in many technical documents, and advanced NPP emergency planning is attracting attention recently. Commercial practices of advanced NPP are undergoing in the world, pebble-bed high-temperature gas-cooled reactor (HTGR) power plant is under construction in China which is considered as a representative of advanced NPP. The paper tries to find some pieces of suggestion from our investigation. The discussion of advanced NPP EP will be summarized first, and then the characteristics of pebble-bed HTGR relating to EP will be described. Finally, PSA insights on emergency source terms selection and current pebble-bed HTGR emergency source terms suggestions are proposed

  17. Computational and experimental prediction of dust production in pebble bed reactors, Part II

    Energy Technology Data Exchange (ETDEWEB)

    Mie Hiruta; Gannon Johnson; Maziar Rostamian; Gabriel P. Potirniche; Abderrafi M. Ougouag; Massimo Bertino; Louis Franzel; Akira Tokuhiro

    2013-10-01

    This paper is the continuation of Part I, which describes the high temperature and high pressure helium environment wear tests of graphite–graphite in frictional contact. In the present work, it has been attempted to simulate a Pebble Bed Reactor core environment as compared to Part I. The experimental apparatus, which is a custom-designed tribometer, is capable of performing wear tests at PBR relevant higher temperatures and pressures under a helium environment. This environment facilitates prediction of wear mass loss of graphite as dust particulates from the pebble bed. The experimental results of high temperature helium environment are used to anticipate the amount of wear mass produced in a pebble bed nuclear reactor.

  18. Overview of municipal sludge fluid bed incineration in North America--from green to greener--the Lakeview, the Duffin Creek and the Southerly experiences.

    Science.gov (United States)

    Dangtran, K; Takmaz, L; Pham, H; Bergel, J Y; Welp, J; Burrowes, P

    2011-01-01

    Thermal processes used in sludge disposal have become more attractive as process improvements have been introduced, such as power generation and efficient heat recovery. More and more utilities and agencies are reevaluating their sludge management practices to ensure that they are providing sustainable management solutions for their clients. The thermal process design approach to the disposal of sludge is not only designed to achieve stricter emission limits but also is more energy efficient compared to its predecessors. Increasing numbers of new plants are being built every year with more energy efficient heat recovery features such as air preheating and cogeneration with steam and electricity production. This paper presents an overview of fluid bed incineration in North America and its evolution over the last decades. Case studies of the last three newest and largest plants in North America are presented, including the Lakeview Plant, Duffin Creek Plant, both in Ontario, Canada and the Southerly Plant in Cleveland, Ohio, USA.

  19. High flux Particle Bed Reactor systems for rapid transmutation of actinides and long lived fission products

    International Nuclear Information System (INIS)

    Powell, J.; Ludewig, H.; Maise, G.; Steinberg, M.; Todosow, M.

    1993-01-01

    An initial assessment of several actinide/LLFP burner concepts based on the Particle Bed Reactor (PBR) is described. The high power density/flux level achievable with the PBR make it an attractive candidate for this application. The PBR based actinide burner concept also possesses a number of safety and economic benefits relative to other reactor based transmutation approaches including a low inventory of radionuclides, and high integrity, coated fuel particles which can withstand extremely high in temperatures while retaining virtually all fission products. In addition the reactor also posesses a number of ''engineered safety features,'' which, along with the use of high temperature capable materials further enhance its safety characteristics

  20. Degradation of whey in an anaerobic fixed bed (AnFB) reactor

    OpenAIRE

    Handajani, Marisa

    2004-01-01

    An Anaerobic Fixed Bed (AnFB) reactor was run as an upflow anaerobic reactor with an arrangement of supporting material for growth of a biofilm. The supporting material was made from Liapor-clay-polyethylene sinter lamellas (Herding Co., Amberg). The AnFB reactor was used for treating high concentrations of whey-containing wastewater. Optimal operating conditions for whey treatment at a concentration of COD in the influent of around 50 g whey·l-1 were found for a hydraulic retention ...

  1. Effects of random pebble distribution on the multiplication factor in HTR pebble bed reactors

    Energy Technology Data Exchange (ETDEWEB)

    Auwerda, G.J., E-mail: g.j.auwerda@tudelft.n [Department of Physics of Nuclear Reactors at the Delft University of Technology, Mekelweg 15, Delft (Netherlands); Kloosterman, J.L.; Lathouwers, D.; Hagen, T.H.J.J. van der [Department of Physics of Nuclear Reactors at the Delft University of Technology, Mekelweg 15, Delft (Netherlands)

    2010-08-15

    In pebble bed reactors the pebbles have a random distribution within the core. The usual approach in modeling the bed is homogenizing the entire bed. To quantify the errors arising in such a model, this article investigates the effect on k{sub eff} of three phenomena in random pebble distributions: non-uniform packing density, neutron streaming in between the pebbles, and variations in Dancoff factor. For a 100 cm high cylinder with reflective top and bottom boundary conditions 25 pebble beds were generated. Of each bed three core models were made: a homogeneous model, a zones model including density fluctuations, and an exact model with all pebbles modeled individually. The same was done for a model of the PROTEUS facility. k{sub eff} calculations were performed with three codes: Monte Carlo, diffusion, and finite element transport. By comparing k{sub eff} of the homogenized and zones model the effect of including density fluctuations in the pebble bed was found to increase k{sub eff} by 71 pcm for the infinite cylinder and 649 pcm for PROTEUS. The large value for PROTEUS is due to the low packing fraction near the top of the pebble bed, causing a significant lower packing fraction for the bulk of the pebble bed in the homogenized model. The effect of neutron streaming was calculated by comparing the zones model with the exact model, and was found to decrease k{sub eff} by 606 pcm for the infinite cylinder, and by 1240 pcm for PROTEUS. This was compared with the effect of using a streaming correction factor on the diffusion coefficient in the zones model, which resulted in {Delta}{sub streaming} values of 340 and 1085 pcm. From this we conclude neutron streaming is an important effect in pebble bed reactors, and is not accurately described by the correction factor on the diffusion coefficient. Changing the Dancoff factor in the outer part of the pebble bed to compensate for the lower probability of neutrons to enter other fuel pebbles caused no significant changes

  2. Experimental and Computational Study of Multiphase Flow Hydrodynamics in 2D Trickle Bed Reactors

    Science.gov (United States)

    Nadeem, H.; Ben Salem, I.; Kurnia, J. C.; Rabbani, S.; Shamim, T.; Sassi, M.

    2014-12-01

    Trickle bed reactors are largely used in the refining processes. Co-current heavy oil and hydrogen gas flow downward on catalytic particle bed. Fine particles in the heavy oil and/or soot formed by the exothermic catalytic reactions deposit on the bed and clog the flow channels. This work is funded by the refining company of Abu Dhabi and aims at mitigating pressure buildup due to fine deposition in the TBR. In this work, we focus on meso-scale experimental and computational investigations of the interplay between flow regimes and the various parameters that affect them. A 2D experimental apparatus has been built to investigate the flow regimes with an average pore diameter close to the values encountered in trickle beds. A parametric study is done for the development of flow regimes and the transition between them when the geometry and arrangement of the particles within the porous medium are varied. Liquid and gas flow velocities have also been varied to capture the different flow regimes. Real time images of the multiphase flow are captured using a high speed camera, which were then used to characterize the transition between the different flow regimes. A diffused light source was used behind the 2D Trickle Bed Reactor to enhance visualizations. Experimental data shows very good agreement with the published literature. The computational study focuses on the hydrodynamics of multiphase flow and to identify the flow regime developed inside TBRs using the ANSYS Fluent Software package. Multiphase flow inside TBRs is investigated using the "discrete particle" approach together with Volume of Fluid (VoF) multiphase flow modeling. The effect of the bed particle diameter, spacing, and arrangement are presented that may be used to provide guidelines for designing trickle bed reactors.

  3. The performance enhancements of upflow anaerobic sludge blanket (UASB) reactors for domestic sludge treatment--a state-of-the-art review.

    Science.gov (United States)

    Chong, Siewhui; Sen, Tushar Kanti; Kayaalp, Ahmet; Ang, Ha Ming

    2012-07-01

    Nowadays, carbon emission and therefore carbon footprint of water utilities is an important issue. In this respect, we should consider the opportunities to reduce carbon footprint for small and large wastewater treatment plants. The use of anaerobic rather than aerobic treatment processes would achieve this aim because no aeration is required and the generation of methane can be used within the plant. High-rate anaerobic digesters receive great interests due to their high loading capacity and low sludge production. Among them, the upflow anaerobic sludge blanket (UASB) reactors have been most widely used. However, there are still unresolved issues inhibiting the widespread of this technology in developing countries or countries with climate temperature fluctuations (such as subtropical regions). A large number of studies have been carried out in order to enhance the performance of UASB reactors but there is a lack of updated documentation. In face of the existing limitations and the increasing importance of this technology, the authors present an up-to-date review on the performance enhancements of UASB reactors over the last decade. The important aspects of this article are: (i) enhancing the start-up and granulation in UASB reactors, (ii) coupling with post-treatment unit to overcome the temperature constraint, and (iii) improving the removal efficiencies of the organic matter, nutrients and pathogens in the final effluent. Finally the authors have highlighted future research direction based on their critical analysis. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

  4. Kinetics of concentration decay of specific organic matter in UASB reactors operating with and without return of aerobic sludge.

    Science.gov (United States)

    Pontes, P P; Chernicharo, C A L; Von Sperling, M

    2014-08-01

    This study aimed at assessing the influence of the return of excess aerobic sludge from a trickling filter (TF) upon the anaerobic digestion process in an upflow anaerobic sludge blanket (UASB) reactor, by evaluating its effect on the kinetics of the decay of specific organic matter (carbohydrates, proteins and lipids), as well as on the concentrations of volatile fatty acids in the UASB reactor. A pilot-scale UASB/TF system was used to perform the experiments, operating with (phase 2) and without (phase 1) excess sludge return from the TF to the UASB reactor. Sampling was carried out at different heights of the UASB reactor (0, 25, 125 and 225-cm height), and profile concentrations were determined for the following parameters: carbohydrates, proteins, lipids and volatile fatty acids. First-order kinetics showed the best fit to the decay of concentrations of carbohydrates, proteins, lipids and chemical oxygen demand (COD) in the UASB reactor. The parameters showing the best fit to the first-order kinetics were proteins and COD, during the sludge return phase. The occurrence of higher apparent reaction constants was further observed during the sludge return phase. For an influent COD concentration of 600 mg L-1 and hydraulic retention times of 2.1, 2.6 and 3.0 h in phase 1, the effluent COD concentrations were 125.3, 88.4 and 62.4 mg L-1, respectively, whereas in phase 2, the effluent COD concentrations were 75.5, 47.6 and 30.1 mg L-1, respectively.

  5. Development of research reactor simulator and its application to dynamic test-bed

    International Nuclear Information System (INIS)

    Kwon, Kee-Choon; Baang, Dane; Park, Jae-Chang; Lee, Seung-Wook; Bae, Sung Won

    2014-01-01

    We developed a real-time simulator for 'High-flux Advanced Neutron Application ReactOr (HANARO), and the Jordan Research and Training Reactor (JRTR). The main purpose of this simulator is operator training, but we modified this simulator into a dynamic test-bed (DTB) to test the functions and dynamic control performance of reactor regulating system (RRS) in HANARO or JRTR before installation. The simulator hardware consists of a host computer, 6 operator stations, a network switch, and a large display panel. The software includes a mathematical model that implements plant dynamics in real-time, an instructor station module that manages user instructions, and a human machine interface module. The developed research reactor simulators are installed in the Korea Atomic Energy Research Institute nuclear training center for reactor operator training. To use the simulator as a dynamic test-bed, the reactor regulating system modeling software of the simulator was replaced by actual RRS cabinet, and was interfaced using a hard-wired and network-based interface. RRS cabinet generates control signals for reactor power control based on the various feedback signals from DTB, and the DTB runs plant dynamics based on the RRS control signals. Thus the Hardware-In-the-Loop Simulation between RRS and the emulated plant (DTB) has been implemented and tested in this configuration. The test result shows that the developed DTB and actual RRS cabinet works together simultaneously resulting in quite good dynamic control performances. (author)

  6. Failure analysis of pebble bed reactors during earthquake by discrete element method

    International Nuclear Information System (INIS)

    Keppler, Istvan

    2013-01-01

    Highlights: ► We evaluated the load acting on the central reflector beam of a pebble bed reactor. ► The load acting on the reflector beam highly depends on fuel element distribution. ► The contact force values do not show high dependence on fuel element distribution. ► Earthquake increases the load of the reflector, not the contact forces. -- Abstract: Pebble bed reactors (PBR) are graphite-moderated, gas-cooled nuclear reactors. PBR reactors use a large number of spherical fuel elements called pebbles. From mechanical point of view, the arrangement of “small” spherical fuel elements in a container poses the same problem, as the so-called silo problem in powder technology and agricultural engineering. To get more exact information about the contact forces arising between the fuel elements in static and dynamic case, we simulated the static case and the effects of an earthquake on a model reactor by using discrete element method. We determined the maximal contact forces acting between the individual fuel elements. We found that the value of the maximal bending moment in the central reflector beam has a high deviation from the average value even in static case, and it can significantly increase in case of an earthquake. Our results can help the engineers working on the design of such types of reactors to get information about the contact forces, to determine the dust production and the crush probability of fuel elements within the reactor, and to model different accident scenarios

  7. Failure analysis of pebble bed reactors during earthquake by discrete element method

    Energy Technology Data Exchange (ETDEWEB)

    Keppler, Istvan, E-mail: keppler.istvan@gek.szie.hu [Department of Mechanics and Engineering Design, Szent István University, Páter K.u.1., Gödöllő H-2103 (Hungary)

    2013-05-15

    Highlights: ► We evaluated the load acting on the central reflector beam of a pebble bed reactor. ► The load acting on the reflector beam highly depends on fuel element distribution. ► The contact force values do not show high dependence on fuel element distribution. ► Earthquake increases the load of the reflector, not the contact forces. -- Abstract: Pebble bed reactors (PBR) are graphite-moderated, gas-cooled nuclear reactors. PBR reactors use a large number of spherical fuel elements called pebbles. From mechanical point of view, the arrangement of “small” spherical fuel elements in a container poses the same problem, as the so-called silo problem in powder technology and agricultural engineering. To get more exact information about the contact forces arising between the fuel elements in static and dynamic case, we simulated the static case and the effects of an earthquake on a model reactor by using discrete element method. We determined the maximal contact forces acting between the individual fuel elements. We found that the value of the maximal bending moment in the central reflector beam has a high deviation from the average value even in static case, and it can significantly increase in case of an earthquake. Our results can help the engineers working on the design of such types of reactors to get information about the contact forces, to determine the dust production and the crush probability of fuel elements within the reactor, and to model different accident scenarios.

  8. Breakthrough of toluene vapours in granular activated carbon filled packed bed reactor

    International Nuclear Information System (INIS)

    Mohan, N.; Kannan, G.K.; Upendra, S.; Subha, R.; Kumar, N.S.

    2009-01-01

    The objective of this research was to determine the toluene removal efficiency and breakthrough time using commercially available coconut shell-based granular activated carbon in packed bed reactor. To study the effect of toluene removal and break point time of the granular activated carbon (GAC), the parameters studied were bed lengths (2, 3, and 4 cm), concentrations (5, 10, and 15 mg l -1 ) and flow rates (20, 40, and 60 ml/min). The maximum percentage removal of 90% was achieved and the maximum carbon capacity for 5 mg l -1 of toluene, 60 ml/min flow rate and 3 cm bed length shows 607.14 mg/g. The results of dynamic adsorption in a packed bed were consistent with those of equilibrium adsorption by gravimetric method. The breakthrough time and quantity shows that GAC with appropriate surface area can be utilized for air cleaning filters. The result shows that the physisorption plays main role in toluene removal.

  9. Accounting for porous structure in effective thermal conductivity calculations in a pebble bed reactor

    International Nuclear Information System (INIS)

    Antwerpen, W. van; Rousseau, P.G.; Toit, C.G. du

    2009-01-01

    A proper understanding of the mechanisms of heat transfer, flow and pressure drop through a packed bed of spheres is of utmost importance in the design of a high temperature pebble bed reactor. A thorough knowledge of the porous structure within the packed bed is important to any rigorous analysis of the transport phenomena, as all the heat and flow mechanisms are influenced by the porous structure. In this paper a new approach is proposed to simulate the effective thermal conductivity employing a combination of new and existing correlations for randomly packed beds. More attention is given to packing structure based on coordination number and contact angles, resulting in a more rigorous differentiation between the bulk and near-wall regions. The model accounts for solid conduction, gas conduction, contact area, surface roughness as well as radiation. (author)

  10. The importance of the AVR pebble-bed reactor for the future of nuclear power

    International Nuclear Information System (INIS)

    Pohl, P.

    2006-01-01

    The AVR pebble-bed high temperature gas-cooled reactor (HTGR) at Juelich (Germany)) operated from 1967 to 1988 and was certainly the most important HTGR project of the past. The reactor was the mass test bed for all development steps of HTGR pebble fuel. Some early fuel charges failed under high temperature conditions and contaminated the reactor. An accurate pebble measurement (Cs 137) allowed to clean the core from unwanted pebbles after 1981. The coolant activity went down and remained very low for the remaining reactor operation. A melt-wire experiment in 1986 revealed max. coolant temperatures of >1280 deg. C and fuel temperatures of >1350 deg. C, explained by under-estimated bypasses. The fuel still in the core achieved high burn-ups and showed under the extreme temperature conditions excellent fission product retention. Thus, the AVR operation qualified the HTGR fuel, and an average discharge burn-up of 112% fifa revealed an excellent fuel economy of the pebble-bed reactor. Furthermore, the AVR operation offers many meaningful data for code-to-experiment comparisons. (authors)

  11. Rotary Bed Reactor for Chemical-Looping Combustion with Carbon Capture. Part 1: Reactor Design and Model Development

    KAUST Repository

    Zhao, Zhenlong

    2013-01-17

    Chemical-looping combustion (CLC) is a novel and promising technology for power generation with inherent CO2 capture. Currently, almost all of the research has been focused on developing CLC-based interconnected fluidized-bed reactors. In this two-part series, a new rotary reactor concept for gas-fueled CLC is proposed and analyzed. In part 1, the detailed configuration of the rotary reactor is described. In the reactor, a solid wheel rotates between the fuel and air streams at the reactor inlet and exit. Two purging sectors are used to avoid the mixing between the fuel stream and the air stream. The rotary wheel consists of a large number of channels with copper oxide coated on the inner surface of the channels. The support material is boron nitride, which has high specific heat and thermal conductivity. Gas flows through the reactor at elevated pressure, and it is heated to a high temperature by fuel combustion. Typical design parameters for a thermal capacity of 1 MW have been proposed, and a simplified model is developed to predict the performances of the reactor. The potential drawbacks of the rotary reactor are also discussed. © 2012 American Chemical Society.

  12. Effect of Mass-Transport Limitations on the Performance of a Packed Bed Membrane Reactor for Partial Oxidations. Transport from the Membrane to the Packed Bed

    NARCIS (Netherlands)

    van Sint Annaland, M.; Kurten, U.; Kuipers, J.A.M.

    2007-01-01

    With a packed bed membrane reactor, the product yield can be significantly enhanced for partial oxidation systems, via distributive addition of oxygen to the reaction mixture along the axial coordinate of the reactor, provided that the reaction order in oxygen of the formation rate of the target

  13. Effect of mass-transport limitations on the performance of a packed bed membrane reactor for partial oxidations. Transport from the membrane to the packed bed

    NARCIS (Netherlands)

    Sint Annaland, van M.; Kurten, U.; Kuipers, J.A.M.

    2007-01-01

    With a packed bed membrane reactor, the product yield can be significantly enhanced for partial oxidation systems, via distributive addition of oxygen to the reaction mixture along the axial coordinate of the reactor, provided that the reaction order in oxygen of the formation rate of the target

  14. Denitrification performance of Pseudomonas denitrificans in a fluidized-bed biofilm reactor and in a stirred tank reactor

    Energy Technology Data Exchange (ETDEWEB)

    Cattaneo, C.; Nicolella, C.; Rovatti, M. [Department of Chemical and Process Engineering, Faculty of Engineering, University of Genoa, Via Opera Pia 15, 16145 Genoa (Italy)

    2003-04-09

    Denitrification of a synthetic wastewater containing nitrates and methanol as carbon source was carried out in two systems - a fluidized-bed biofilm reactor (FBBR) and a stirred tank reactor (STR) - using Pseudomonas denitrificans over a period of five months. Nitrogen loading was varied during operation of both reactors to assess differences in the response to transient conditions. Experimental data were analyzed to obtain a comparison of denitrification kinetics in biofilm and suspended growth reactors. The comparison showed that the volumetric degradation capacity in the FBBR (5.36 kg {sub N} . m{sup -3} . d{sup -1}) was higher than in the STR, due to higher biomass concentration (10 kg {sub BM} . m{sup -3} vs 1.2 kg {sub BM} m{sup -3}). (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  15. Trickle bed reactor model to simulate the performance of commercial diesel hydrotreating unit

    Energy Technology Data Exchange (ETDEWEB)

    C. Murali; R.K. Voolapalli; N. Ravichander; D.T. Gokak; N.V. Choudary [Bharat Petroleum Corporation Ltd., Udyog Kendra (India). Corporate R& amp; D Centre

    2007-05-15

    A two phase mathematical model was developed to simulate the performance of bench scale and commercial hydrotreating reactors. Major hydrotreating reactions, namely, hydrodesulphurization, hydrodearomatization and olefins saturation were modeled. Experiments were carried out in a fixed bed reactor to study the effect of different process variables and these results were used for estimating kinetic parameters. Significant amount of feed vaporization (20-50%) was estimated under normal operating conditions of DHDS suggesting the importance of considering feed vaporization in DHDS modeling. The model was validated with plant operating data, under close to ultra low sulphur levels by correctly accounting for feed vaporization in heat balance relations and appropriate use of hydrodynamic correlations. The model could predict the product quality, reactor bed temperature profiles and chemical hydrogen consumption in commercial plant adequately. 14 refs., 7 figs., 6 tabs.

  16. 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

  17. Analysis of startup strategies for a particle bed reactor nuclear rocket engine

    Science.gov (United States)

    Suzuki, D. E.

    1993-06-01

    This paper develops and analyzes engine system startup strategies for a particle bed reactor (PBR) nuclear rocket engine. The strategies are designed to maintain stable flow through the PBR fuel element while reaching the design conditions as quickly as possible. The analyses are conducted using a computer model of a representative particle bed reactor and engine system. Elements of the startup strategy considered include: the coordinated control of reactor power and coolant flow; turbine inlet temperature and flow control; and use of an external starter system. The simulation results indicate that the use of an external starter system enables the engine to reach design conditions very quickly while maintaining the flow well away from the unstable regime. If a bootstrap start is used instead, the transient does not progress as fast and approaches closer to the unstable flow regime, but allows for greater engine reusability. These results can provide important information for engine designers and mission planners.

  18. Fluid flow and heat transfer investigation of pebble bed reactors using mesh-adaptive LES

    International Nuclear Information System (INIS)

    Pavlidis, Dimitrios; Lathouwers, Danny

    2013-01-01

    The very high temperature reactor is one of the designs currently being considered for nuclear power generation. One its variants is the pebble bed reactor in which the coolant passes through complex geometries (pores) at high Reynolds numbers. A computational fluid dynamics model with anisotropic mesh adaptivity is used to investigate coolant flow and heat transfer in such reactors. A novel method for implicitly incorporating solid boundaries based on multi-fluid flow modelling is adopted. The resulting model is able to resolve and simulate flow and heat transfer in randomly packed beds, regardless of the actual geometry, starting off with arbitrarily coarse meshes. The model is initially evaluated using an orderly stacked square channel of channel-height-to-particle diameter ratio of unity for a range of Reynolds numbers. The model is then applied to the face-centred cubical geometry. coolant flow and heat transfer patterns are investigated

  19. Improved performance of parallel surface/packed-bed discharge reactor for indoor VOCs decomposition: optimization of the reactor structure

    International Nuclear Information System (INIS)

    Jiang, Nan; Hui, Chun-Xue; Li, Jie; Lu, Na; Shang, Ke-Feng; Wu, Yan; Mizuno, Akira

    2015-01-01

    The purpose of this paper is to develop a high-efficiency air-cleaning system for volatile organic compounds (VOCs) existing in the workshop of a chemical factory. A novel parallel surface/packed-bed discharge (PSPBD) reactor, which utilized a combination of surface discharge (SD) plasma with packed-bed discharge (PBD) plasma, was designed and employed for VOCs removal in a closed vessel. In order to optimize the structure of the PSPBD reactor, the discharge characteristic, benzene removal efficiency, and energy yield were compared for different discharge lengths, quartz tube diameters, shapes of external high-voltage electrode, packed-bed discharge gaps, and packing pellet sizes, respectively. In the circulation test, 52.8% of benzene was removed and the energy yield achieved 0.79 mg kJ −1 after a 210 min discharge treatment in the PSPBD reactor, which was 10.3% and 0.18 mg kJ −1 higher, respectively, than in the SD reactor, 21.8% and 0.34 mg kJ −1 higher, respectively, than in the PBD reactor at 53 J l −1 . The improved performance in benzene removal and energy yield can be attributed to the plasma chemistry effect of the sequential processing in the PSPBD reactor. The VOCs mineralization and organic intermediates generated during discharge treatment were followed by CO x selectivity and FT-IR analyses. The experimental results indicate that the PSPBD plasma process is an effective and energy-efficient approach for VOCs removal in an indoor environment. (paper)

  20. 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

  1. Hydrodynamic characteristics of airlift nitrifying reactor using carrier-induced granular sludge

    International Nuclear Information System (INIS)

    Jin Rencun; Zheng Ping; Mahmood, Qaisar; Zhang Lei

    2008-01-01

    Since nitrification is the rate-limiting step in the biological nitrogen removal from wastewater, many studies have been conducted on the immobilization of nitrifying bacteria. A laboratory-scale investigation was carried out to scrutinize the effectiveness of activated carbon carrier addition for granulation of nitrifying sludge in a continuous-flow airlift bioreactor and to study the hydrodynamics of the reactor with carrier-induced granules. The results showed that the granular sludge began to appear and matured 60 and 108 days, respectively, after addition of carriers, while no granule was observed in the absence of carriers in the control test. The mature granules had a diameter of 0.5-5 mm (1.6 mm in average), settling velocity 22.3-55.8 m h -1 and specific gravity of 1.086. The relationship between the two important hydrodynamic coefficients, i.e. gas holdup and liquid circulation velocity, and the superficial gas velocity were established by a simple model and were confirmed experimentally. The model also could predict the critical superficial gas velocity for liquid circulation and that for granules circulation, with respective values of 1.017 and 2.662 cm min -1 , accurately

  2. Hydrodynamic characteristics of airlift nitrifying reactor using carrier-induced granular sludge

    Energy Technology Data Exchange (ETDEWEB)

    Jin Rencun [Department of Environmental Engineering, Zhejiang University, Hangzhou 310029 (China); Department of Environmental Science, Hangzhou Normal University, Hangzhou 310036 (China); Zheng Ping [Department of Environmental Engineering, Zhejiang University, Hangzhou 310029 (China)], E-mail: pzheng@zju.edu.cn; Mahmood, Qaisar; Zhang Lei [Department of Environmental Engineering, Zhejiang University, Hangzhou 310029 (China)

    2008-09-15

    Since nitrification is the rate-limiting step in the biological nitrogen removal from wastewater, many studies have been conducted on the immobilization of nitrifying bacteria. A laboratory-scale investigation was carried out to scrutinize the effectiveness of activated carbon carrier addition for granulation of nitrifying sludge in a continuous-flow airlift bioreactor and to study the hydrodynamics of the reactor with carrier-induced granules. The results showed that the granular sludge began to appear and matured 60 and 108 days, respectively, after addition of carriers, while no granule was observed in the absence of carriers in the control test. The mature granules had a diameter of 0.5-5 mm (1.6 mm in average), settling velocity 22.3-55.8 m h{sup -1} and specific gravity of 1.086. The relationship between the two important hydrodynamic coefficients, i.e. gas holdup and liquid circulation velocity, and the superficial gas velocity were established by a simple model and were confirmed experimentally. The model also could predict the critical superficial gas velocity for liquid circulation and that for granules circulation, with respective values of 1.017 and 2.662 cm min{sup -1}, accurately.

  3. Deleterious Thermal Effects due to Randomized Flow Paths in Pebble Bed, and Particle Bed Style Reactors

    Science.gov (United States)

    Moran, Robert P.

    2013-01-01

    Reactor fuel rod surface area that is perpendicular to coolant flow direction (+S) i.e. perpendicular to the P creates areas of coolant stagnation leading to increased coolant temperatures resulting in localized changes in fluid properties. Changes in coolant fluid properties caused by minor increases in temperature lead to localized reductions in coolant mass flow rates leading to localized thermal instabilities. Reductions in coolant mass flow rates result in further increases in local temperatures exacerbating changes to coolant fluid properties leading to localized thermal runaway. Unchecked localized thermal runaway leads to localized fuel melting. Reactor designs with randomized flow paths are vulnerable to localized thermal instabilities, localized thermal runaway, and localized fuel melting.

  4. Tests of candidate materials for particle bed reactors

    International Nuclear Information System (INIS)

    Horn, F.L.; Powell, J.R.; Wales, D.

    1987-01-01

    Rhenium metal hot frits and zirconium carbide-coated fuel particles appear suitable for use in flowing hydrogen to at least 2000 K, based on previous tests. Recent tests on alternate candidate cooled particle and frit materials are described. Silicon carbide-coated particles began to react with rhenium frit material at 1600 K, forming a molten silicide at 2000 K. Silicon carbide was extensively attacked by hydrogen at 2066 K for 30 minutes, losing 3.25% of its weight. Vitrous carbon was also rapidly attacked by hydrogen at 2123 K, losing 10% of its weight in two minutes. Long term material tests on candidate materials for closed cycle helium cooled particle bed fuel elements are also described. Surface imperfections were found on the surface of pyrocarbon-coated fuel particles after ninety days exposure to flowing (∼500 ppM) impure helium at 1143 K. The imperfections were superficial and did not affect particle strength

  5. CFD simulation of fluid dynamic and biokinetic processes within activated sludge reactors under intermittent aeration regime.

    Science.gov (United States)

    Sánchez, F; Rey, H; Viedma, A; Nicolás-Pérez, F; Kaiser, A S; Martínez, M

    2018-08-01

    Due to the aeration system, biological reactors are the most energy-consuming facilities of convectional WWTPs. Many biological reactors work under intermittent aeration regime; the optimization of the aeration process (air diffuser layout, air flow rate per diffuser, aeration length …) is necessary to ensure an efficient performance; satisfying the effluent requirements with the minimum energy consumption. This work develops a CFD modelling of an activated sludge reactor (ASR) which works under intermittent aeration regime. The model considers the fluid dynamic and biological processes within the ASR. The biological simulation, which is transient, takes into account the intermittent aeration regime. The CFD modelling is employed for the selection of the aeration system of an ASR. Two different aeration configurations are simulated. The model evaluates the aeration power consumption necessary to satisfy the effluent requirements. An improvement of 2.8% in terms of energy consumption is achieved by modifying the air diffuser layout. An analysis of the influence of the air flow rate per diffuser on the ASR performance is carried out. The results show a reduction of 14.5% in the energy consumption of the aeration system when the air flow rate per diffuser is reduced. The model provides an insight into the aeration inefficiencies produced within ASRs. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Cleaning of porous filters in fossilized bed reactors; Estudio de limpieza de filtros porosos en reactores de lecho fluidizado

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigo Otero, A; Sancho Rod, J

    1965-07-01

    In this report are established the optimum working conditions of a filter cleaning system by blow back. For this purpose it was determined in the first place the blow back air rate necessary to have a good cleaning. The reasons for which it was not possible until now to control the pressure in a fluidized bed calcination reactor are analyzed and a criteria is established to calculate the optimum floe necessary to clean efficiently a porous by this procedures. (Author)

  7. Effect of dissolved oxygen on nitrogen removal and process control in aerobic granular sludge reactor

    International Nuclear Information System (INIS)

    Yuan Xiangjuan; Gao Dawen

    2010-01-01

    A sequencing batch reactor (SBR) with aerobic granular sludge was operated to determine the effect of different DO concentrations on biological nitrogen removal process and to investigate the spatial profiles of DO, ORP and pH as online control parameters in such systems. The results showed that DO concentration had a significant effect on nitrification efficiencies and the profiles of DO, ORP and pH. The specific nitrification rate was decreased from 0.0595 mgNH 4 + -N/(gMLSS min) to 0.0251 mgNH 4 + -N/(gMLSS min) after DO concentration was dropped off from 4.5 mg/L to 1.0 mg/L. High DO concentration improved the nitrification and increased the volumetric NH 4 + -N removal. Low DO concentration enhanced TIN removal, while prolonged the nitrification duration. Also there existed a good correlation between online control parameters (ORP, pH) and nutrient (COD, NH 4 + -N, NO 2 - -N, NO 3 - -N) variations in aerobic granular sludge reactor when DO was 2.5 mg/L, 3.5 mg/L and 4.5 mg/L. However it was difficult to identify the end of nitrification and denitrification when DO was 1.0 mg/L, due to no apparent bending points on ORP and pH curves. In conclusion, the optimal DO concentration was suggested at 2.5 mg/L as it not only achieved high nitrogen removal efficiency and decreased the reaction duration, but also saved operation cost by aeration and mixing.

  8. The effect of toxic carbon source on the reaction of activated sludge in the batch reactor.

    Science.gov (United States)

    Wu, Changyong; Zhou, Yuexi; Zhang, Siyu; Xu, Min; Song, Jiamei

    2018-03-01

    The toxic carbon source can cause higher residual effluent dissolved organic carbon than easily biodegraded carbon source in activated sludge process. In this study, an integrated activated sludge model is developed as the tool to understand the mechanism of toxic carbon source (phenol) on the reaction, regarding the carbon flows during the aeration period in the batch reactor. To estimate the toxic function of phenol, the microbial cells death rate (k death ) is introduced into the model. The integrated model was calibrated and validated by the experimental data and it was found the model simulations matched the all experimental measurements. In the steady state, the toxicity of phenol can result in higher microbial cells death rate (0.1637 h -1 vs 0.0028 h -1 ) and decay rate coefficient of biomass (0.0115 h -1 vs 0.0107 h -1 ) than acetate. In addition, the utilization-associated products (UAP) and extracellular polymeric substances (EPS) formation coefficients of phenol are higher than that of acetate, indicating that more carbon flows into the extracellular components, such as soluble microbial products (SMP), when degrading toxic organics. In the non-steady state of feeding phenol, the yield coefficient for growth and maximum specific growth rate are very low in the first few days (1-10 d), while the decay rate coefficient of biomass and microbial cells death rate are relatively high. The model provides insights into the difference of the dynamic reaction with different carbon sources in the batch reactor. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Effect of a flow-corrective insert on the flow pattern in a pebble bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yu; Gui, Nan; Yang, Xingtuan [Institute of Nuclear and New Energy Technology, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Tsinghua University, Beijing 100084 (China); Tu, Jiyuan [Institute of Nuclear and New Energy Technology, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Tsinghua University, Beijing 100084 (China); School of Aerospace, Mechanical & Manufacturing Engineering, RMIT University, Melbourne 3083, VIC (Australia); Jiang, Shengyao, E-mail: shengyaojiang@sina.com [Institute of Nuclear and New Energy Technology, Collaborative Innovation Center of Advanced Nuclear Energy Technology, Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education, Tsinghua University, Beijing 100084 (China)

    2016-04-15

    Highlights: • Effect of an insert on improving flow uniformity and eliminating stagnant zone is studied. • Three values concerned with the stagnant zone, radial uniformity and flow sequence are used. • Outlet diameter is a critical parameter that determines balancing mechanism of the insert. • Height/location is varied to let the insert work in unbalanced region and avoid adverse effect. - Abstract: A flow-corrective insert is adopted in the pebble-bed high temperature gas-cooled reactor (HTGR) to improve flow performance of the pebble flow for the first time. 3D discrete element method (DEM) modeling is employed to study this slow and dense granular flow. It is verified that locating a properly designed insert in the bed can help transform unsatisfactory flow field to the preferred flow pattern for pebble bed reactors. Three characteristic values on the stagnant zone, radial uniformity and flow sequence of pebble flow are defined to evaluate uniformity of the overall flow field quantitatively. The results demonstrate that the pebble bed equipped with an insert performs better than normal beds from all these three aspects. Moreover, based on numerical experiments, several universal tips for insert design on height, location and outlet diameter are suggested.

  10. Effect of friction on pebble flow pattern in pebble bed reactor

    International Nuclear Information System (INIS)

    Li, Yu; Gui, Nan; Yang, Xingtuan; Tu, Jiyuan; Jiang, Shengyao

    2016-01-01

    Highlights: • A 3D DEM study on particle–wall/particle friction in pebble bed reactor is carried out. • Characteristic values are defined to evaluate features of pebble flow pattern quantitatively. • Particle–wall friction is dominant to determine flow pattern in a specific pebble bed. • Friction effect of hopper part on flow field is more critical than that of cylinder part. • Three cases of 1:1 full scale practical pebble beds are simulated for demonstration. - Abstract: Friction affects pebble flow pattern in pebble-bed high temperature gas-cooled reactor (HTGR) significantly. Through a series of three dimensional DEM (discrete element method) simulations it is shown that reducing friction can be beneficial and create a uniform and consistent flow field required by nuclear engineering. Particle–wall friction poses a decisive impact on flow pattern, and particle–particle friction usually plays a secondary role; relation between particle–wall friction and flow pattern transition is also concluded. Moreover, new criteria are created to describe flow patterns quantitatively according to crucial issues in HTGR like stagnant zone, radial uniformity and flow sequence. Last but not least, it is proved that friction control of hopper part is more important than that of cylinder part in practical pebble beds, so reducing friction between pebbles and hopper surface is the engineering priority.

  11. 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

  12. Experimental and computational investigation of flow of pebbles in a pebble bed nuclear reactor

    Science.gov (United States)

    Khane, Vaibhav B.

    The Pebble Bed Reactor (PBR) is a 4th generation nuclear reactor which is conceptually similar to moving bed reactors used in the chemical and petrochemical industries. In a PBR core, nuclear fuel in the form of pebbles moves slowly under the influence of gravity. Due to the dynamic nature of the core, a thorough understanding about slow and dense granular flow of pebbles is required from both a reactor safety and performance evaluation point of view. In this dissertation, a new integrated experimental and computational study of granular flow in a PBR has been performed. Continuous pebble re-circulation experimental set-up, mimicking flow of pebbles in a PBR, is designed and developed. Experimental investigation of the flow of pebbles in a mimicked test reactor was carried out for the first time using non-invasive radioactive particle tracking (RPT) and residence time distribution (RTD) techniques to measure the pebble trajectory, velocity, overall/zonal residence times, flow patterns etc. The tracer trajectory length and overall/zonal residence time is found to increase with change in pebble's initial seeding position from the center towards the wall of the test reactor. Overall and zonal average velocities of pebbles are found to decrease from the center towards the wall. Discrete element method (DEM) based simulations of test reactor geometry were also carried out using commercial code EDEM(TM) and simulation results were validated using the obtained benchmark experimental data. In addition, EDEM(TM) based parametric sensitivity study of interaction properties was carried out which suggests that static friction characteristics play an important role from a packed/pebble beds structural characterization point of view. To make the RPT technique viable for practical applications and to enhance its accuracy, a novel and dynamic technique for RPT calibration was designed and developed. Preliminary feasibility results suggest that it can be implemented as a non

  13. Experiment and modeling of low-concentration methane catalytic combustion in a fluidized bed reactor

    International Nuclear Information System (INIS)

    Yang, Zhongqing; Yang, Peng; Zhang, Li; Guo, Mingnv; Ran, Jingyu

    2016-01-01

    Highlights: • The catalytic combustion of 0.15~3 vol. % low concentration methane in a fluidized bed was studied. • A mathematical model was proposed on the basis of gas–solid flow theory. • A comparative analysis of the established model with plug flow, mixed flow and K-L models was carried out. • The axial methane profile along fluidized bed was predicted by using the mathematical model. • The bed temperature has greater impact on methane conversion than fluidized velocity. - Abstract: This study undertakes a theoretical analysis and an experimental investigation into the characteristics of low-concentration methane catalytic combustion in a bubbling fluidized bed reactor using 0.5 wt.% Pd/Al_2O_3 as catalytic particles. A mathematical model is established based on gas–solid flow theory and is used to study the effects of bed temperature and fluidized velocity on methane catalytic combustion, and predict the dimensionless methane concentration axial profile in reactor. It is shown that methane conversion increases with bed temperature, but decreases with increasing fluidized velocity. These theoretical results are found to correlate well with the experimental measurement, with a deviation within 5%. A comparative analysis of the developed model with plug flow, mixed flow and K-L models is also carried out, and this further verifies that the established model better reflects the characteristics of low-concentration methane catalytic combustion in a bubbling fluidized bed. Using this reaction model, it was found that the difference in methane conversion between dense and freeboard zones gradually increases with bed temperature; the dense zone reaction levels off at 650 °C, thereby minimizing the difference between the dense and freeboard regions to around 15%. With an increase in bed temperature, the dimensionless methane concentration in the dense zone decreases exponentially, while in the splash zone, it varies from an exponential decay to a slow

  14. Catalytic wet oxidation of phenol in a trickle bed reactor over a Pt/TiO2 catalyst.

    Science.gov (United States)

    Maugans, Clayton B; Akgerman, Aydin

    2003-01-01

    Catalytic wet oxidation of phenol was studied in a batch and a trickle bed reactor using 4.45% Pt/TiO2 catalyst in the temperature range 150-205 degrees C. Kinetic data were obtained from batch reactor studies and used to model the reaction kinetics for phenol disappearance and for total organic carbon disappearance. Trickle bed experiments were then performed to generate data from a heterogeneous flow reactor. Catalyst deactivation was observed in the trickle bed reactor, although the exact cause was not determined. Deactivation was observed to linearly increase with the cumulative amount of phenol that had passed over the catalyst bed. Trickle bed reactor modeling was performed using a three-phase heterogeneous model. Model parameters were determined from literature correlations, batch derived kinetic data, and trickle bed derived catalyst deactivation data. The model equations were solved using orthogonal collocations on finite elements. Trickle bed performance was successfully predicted using the batch derived kinetic model and the three-phase reactor model. Thus, using the kinetics determined from limited data in the batch mode, it is possible to predict continuous flow multiphase reactor performance.

  15. Analysis of the start-up and control of a particle bed reactor

    International Nuclear Information System (INIS)

    Lazareth, O.W.; Araj, K.J.; Horn, F.L.; Ludewig, H.; Powell, J.R.

    1987-01-01

    This study describes the modeling of start-up transients in Particle Bed Reactors (PBR) for burst electric power. Two computer programs have been developed to analyze the start-up process. The first program (named KINETIC) analyzes the entire fuel element, calculating time dependent solutions for power and the temperature distribution in the packed bed. The second program (named SPHEAT, for Spherical Heating) calculates time-dependent temperatures inside individual, cladded fuel particles. The two programs provide powerful analytical tools for evaluation of material and geometrical options, power and time constraints, and conditions that could lead to element failures

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

    Directory of Open Access Journals (Sweden)

    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.

  17. Neutronic design of a Liquid Salt-cooled Pebble Bed Reactor (LSPBR)

    International Nuclear Information System (INIS)

    De Zwaan, S. J.; Boer, B.; Lathouwers, D.; Kloosterman, J. L.

    2006-01-01

    A renewed interest has been raised for liquid salt cooled nuclear reactors. The excellent heat transfer properties of liquid salt coolants provide several benefits, like lower fuel temperatures, higher coolant outlet temperatures, increased core power density and better decay heat removal. In order to benefit from the online refueling capability of a pebble bed reactor, the Liquid Salt Pebble Bed Reactor (LSPBR) is proposed. This is a high temperature pebble-bed reactor with a fuel design similar to existing HTRs, but using a liquid salt as a coolant. In this paper, the selection criteria for the liquid salt coolant are described. Based on its neutronic properties, LiF-BeF 2 (FLIBE) was selected for the LSPBR. Two designs of the LSPBR were considered: a cylindrical core and an annular core with a graphite inner reflector. Coupled neutronic-thermal hydraulic calculations were performed to obtain the steady state power distribution and the corresponding fuel temperatures. Finally, calculations were performed to investigate the decay heat removal capability in a protected loss-of-forced cooling accident. The maximum allowable power that can be produced with the LSPBR is hereby determined. (authors)

  18. The combustion of coal blends in a fluidised bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Boavida, Dulce; Abelha, Pedro; Gulyurtlu, Ibrahim; Cabrita, Isabel

    1999-07-01

    Combustion studies of five coals of different origin were carried out in a laboratory scale fluidised bed combustor. Five blends prepared by mixing two coals based on their petrological characterisation, in varying amounts, were selected to study the possibility of reduction NO{sub x}, N{sub 2}O and SO{sub 2} emissions. The results showed that some blends had the opposite behaviour concerning the release of NO{sub x} and SO{sub 2} in relation to parent coals, and the emissions were higher than expected. The N{sub 2}O amounts observed were, however, in almost all blends tested, lower than predicted values. With some blends, the mixing levels intended to reduce SO{sub 2} were not always found to correspond to those for simultaneous decrease of Nox. Most of the blends studied showed some evidence of interaction between them. Varying the proportion of the blend components was observed to alter the temperatures at which interactions were stronger.

  19. Experimental and numerical validation of a two-region-designed pebble bed reactor with dynamic core

    International Nuclear Information System (INIS)

    Jiang, S.Y.; Yang, X.T.; Tang, Z.W.; Wang, W.J.; Tu, J.Y.; Liu, Z.Y.; Li, J.

    2012-01-01

    Highlights: ► The experimental installation has been built to investigate the pebble flow. ► The feasibility of two-region pebble bed reactor has been verified. ► The pebble flow is more uniform in a taller vessel than that in a lower vessel. ► Larger base cone angle will decrease the scale of the stagnant zone. - Abstract: The pebble flow is the principal issue for the design of the pebble bed reactor. In order to verify the feasibility of a two-region-designed pebble bed reactor, the experimental installation with a taller vessel has been built, which is proportional to the real pebble bed reactor. With the aid of the experimental installation, the stable establishment and maintenance of the two-region arrangement has been verified, at the same time, the applicability of the DEM program has been also validated. Research results show: (1) The pebble's bouncing on the free surface is an important factor for the mixing of the different colored pebbles. (2) Through the guide plates installed in the top of the pebble packing, the size of the mixing zone can be reduced from 6–7 times to 3–4 times the pebble diameter. (3) The relationship between the width of the central region and the ratio of loading pebbles is approximately linear in the taller vessel. (4) The heighten part of the pebble packing can improve the uniformity of the flowing in the lower. (5) To increase the base cone angle can decrease the scale of the stagnant zone. All of these conclusions are meaningful to the design of the real pebble reactor.

  20. Radioisotope tracer study in a pilot-scale trickle bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Pant, H.J.; Pendharkar, A.S. [Bhabha Atomic Research Centre, Isotope Applications Div, Bombay (India); Prasad, J.S.; Maiti, R.N.; Chawla, R.; Lahri, R.N.; Ram Babu, D. [Engineers India Limited, Gurgaon, Haryana (India); Berne, Ph. [CEA Grenoble, DTEN/SAT, 38 (France)

    2001-07-01

    Trickle bed reactor (TBR) is a reactor in which a liquid and a gas phase flow concurrently downwards through a fixed bed of catalyst particles while the reaction takes place. The trickle bed reactors find a number of applications in petroleum refining, chemical. petro-chemical and bio-chemical processes due to their suitability for hydro-processing operations.The knowledge of radial distribution, mean residence time (MRT). liquid holdup and degree of axial mixing is a basic requirement to evaluate the reactor performance of a TBR, its optimal size, the physical and chemical interactions and the pumping requirements. Measurement and analysis of residence time distribution (RTD) of liquid phase facilitate the determination of these parameters. This paper describes the measurement of RTD of liquid phase in a pilot-scale trickle bed reactor operating at high pressure. Kerosene and nitrogen were used as liquid and gas phase, respectively. Porous alumina catalyst particles were used as packing. Bromine-82 as para-di-bromo benzene was used as a tracer to measure RTD of organic liquid phase. The RTD of kerosene was measured as a function of liquid and gas flow rates and pressure. The axial dispersion model with exchange between active and dead zones was proposed and used to simulate the measured RTD data and model parameters i.e mean residence time ({tau}), Peclet Number (Pe), dynamic fraction of the liquid ({phi}) and the number of transfer units (N) were obtained. The results of the simulations indicated intermediate degree of axial mixing of liquid phase. The RTD predicted by the axial dispersion model with exchange between active and dead zones fits well to the experimentally measured RTD data and thus is a suitable model to describe the dynamics of the liquid phase in TBRs filled with porous catalyst particles. (authors)

  1. Decreased activity of a propionate degrading community in a UASB reactor fed with synthetic medium without molybdenum, tungsten and selenium

    NARCIS (Netherlands)

    Worm, P.; Fermoso, F.G.; Lens, P.N.L.; Plugge, C.M.

    2009-01-01

    The composition and dynamics of the propionate degrading community in a propionate-fed upflow anaerobic sludge bed (UASB) reactor with sludge originating from an alcohol distillery wastewater treating UASB reactor was studied. The rather stable propionate degrading microbial community comprised

  2. Pebble Bed Reactors Design Optimization Methods and their Application to the Pebble Bed Fluoride Salt Cooled High Temperature Reactor (PB-FHR)

    Science.gov (United States)

    Cisneros, Anselmo Tomas, Jr.

    The Fluoride salt cooled High temperature Reactor (FHR) is a class of advanced nuclear reactors that combine the robust coated particle fuel form from high temperature gas cooled reactors, direct reactor auxillary cooling system (DRACS) passive decay removal of liquid metal fast reactors, and the transparent, high volumetric heat capacitance liquid fluoride salt working fluids---flibe (33%7Li2F-67%BeF)---from molten salt reactors. This combination of fuel and coolant enables FHRs to operate in a high-temperature low-pressure design space that has beneficial safety and economic implications. In 2012, UC Berkeley was charged with developing a pre-conceptual design of a commercial prototype FHR---the Pebble Bed- Fluoride Salt Cooled High Temperature Reactor (PB-FHR)---as part of the Nuclear Energy University Programs' (NEUP) integrated research project. The Mark 1 design of the PB-FHR (Mk1 PB-FHR) is 236 MWt flibe cooled pebble bed nuclear heat source that drives an open-air Brayton combine-cycle power conversion system. The PB-FHR's pebble bed consists of a 19.8% enriched uranium fuel core surrounded by an inert graphite pebble reflector that shields the outer solid graphite reflector, core barrel and reactor vessel. The fuel reaches an average burnup of 178000 MWt-d/MT. The Mk1 PB-FHR exhibits strong negative temperature reactivity feedback from the fuel, graphite moderator and the flibe coolant but a small positive temperature reactivity feedback of the inner reflector and from the outer graphite pebble reflector. A novel neutronics and depletion methodology---the multiple burnup state methodology was developed for an accurate and efficient search for the equilibrium composition of an arbitrary continuously refueled pebble bed reactor core. The Burnup Equilibrium Analysis Utility (BEAU) computer program was developed to implement this methodology. BEAU was successfully benchmarked against published results generated with existing equilibrium depletion codes VSOP

  3. 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

  4. 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.

  5. Prevention of clogging in a biological trickle-bed reactor removing toluene from contaminated air.

    Science.gov (United States)

    Weber, F J; Hartmans, S

    1996-04-05

    Removal of organic compounds like toluene from waste gases with a trickle-bed reactor can result in clogging of the reactor due to the formation of an excessive amount of biomass. We therefore limited the amount of nutrients available for growth, to prevent clogging of the reactor. As a consequence of this nutrient limitation a lower removal rate was observed. However, when a fungal culture was used to inoculate the reactor, the toluene removal rate under nutrient limiting conditions was higher. Over a period of 375 days, an average removal rate of 27 g C/(m(3) h) was obtained with the reactor inoculated with the fungal culture. From the carbon balance over the reactor and the nitrogen availability it was concluded that, under these nutrient-limited conditions, large amounts of carbohydrates are probably formed. We also studied the application of a NaOH wash to remove excess biomass, as a method to prevent clogging. Under these conditions an average toluene removal rate of 35 g C/(m(3) h) was obtained. After about 50 days there was no net increase in the biomass content of the reactor. The amount of biomass which was formed in the reactor equaled the amount removed by the NaOH wash.

  6. Diversity Profile of Microbes Associated with Anaerobic Sulfur Oxidation in an Upflow Anaerobic Sludge Blanket Reactor Treating Municipal Sewage

    Science.gov (United States)

    Aida, Azrina A.; Kuroda, Kyohei; Yamamoto, Masamitsu; Nakamura, Akinobu; Hatamoto, Masashi; Yamaguchi, Takashi

    2015-01-01

    We herein analyzed the diversity of microbes involved in anaerobic sulfur oxidation in an upflow anaerobic sludge blanket (UASB) reactor used for treating municipal sewage under low-temperature conditions. Anaerobic sulfur oxidation occurred in the absence of oxygen, with nitrite and nitrate as electron acceptors; however, reactor performance parameters demonstrated that anaerobic conditions were maintained. In order to gain insights into the underlying basis of anaerobic sulfur oxidation, the microbial diversity that exists in the UASB sludge was analyzed comprehensively to determine their identities and contribution to sulfur oxidation. Sludge samples were collected from the UASB reactor over a period of 2 years and used for bacterial 16S rRNA gene-based terminal restriction fragment length polymorphism (T-RFLP) and next-generation sequencing analyses. T-RFLP and sequencing results both showed that microbial community patterns changed markedly from day 537 onwards. Bacteria belonging to the genus Desulforhabdus within the phylum Proteobacteria and uncultured bacteria within the phylum Fusobacteria were the main groups observed during the period of anaerobic sulfur oxidation. Their abundance correlated with temperature, suggesting that these bacterial groups played roles in anaerobic sulfur oxidation in UASB reactors. PMID:25817585

  7. Modeling of reaction kinetics in bubbling fluidized bed biomass gasification reactor

    Energy Technology Data Exchange (ETDEWEB)

    Thapa, R.K.; Halvorsen, B.M. [Telemark University College, Kjolnes ring 56, P.O. Box 203, 3901 Porsgrunn (Norway); Pfeifer, C. [University of Natural Resources and Life Sciences, Vienna (Austria)

    2013-07-01

    Bubbling fluidized beds are widely used as biomass gasification reactors as at the biomass gasification plant in Gussing, Austria. The reactor in the plant is a dual circulating bubbling fluidized bed gasification reactor. The plant produces 2MW electricity and 4.5MW heat from the gasification of biomass. Wood chips as biomass and olivine particles as hot bed materials are fluidized with high temperature steam in the reactor. As a result, biomass undergoes endothermic chemical reaction to produce a mixture of combustible gases in addition to some carbon-dioxide (CO2). The combustible gases are mainly hydrogen (H2), carbon monoxide (CO) and methane (CH4). The gas is used to produce electricity and heat via utilization in a gas engine. Alternatively, the gas is further processed for gaseous or liquid fuels, but still on the process of development level. Composition and quality of the gas determine the efficiency of the reactor. A computational model has been developed for the study of reaction kinetics in the gasification rector. The simulation is performed using commercial software Barracuda virtual reactor, VR15. Eulerian-Lagrangian approach in coupling of gas-solid flow has been implemented. Fluid phase is treated with an Eulerian formulation. Discrete phase is treated with a Lagrangian formulation. Particle-particle and particle-wall interactions and inter-phase heat and mass transfer have been taken into account. Series of simulations have been performed to study model prediction of the gas composition. The composition is compared with data from the gasifier at the CHP plant in Güssing, Austria. The model prediction of the composition of gases has good agreements with the result of the operating plant.

  8. Pressurizing Behavior on Ingress of Coolant into Pebble Bed of Blanket of Fusion DEMO Reactor

    International Nuclear Information System (INIS)

    Daigo Tsuru; Mikio Enoeda; Masato Akiba

    2006-01-01

    Solid breeder blankets are being developed as candidate blankets for the Fusion DEMO reactor in Japan. JAEA is performing the development of the water cooled and helium cooled solid breeder blankets. The blanket utilizes ceramic breeder pebbles and multiplier pebbles beds cooled by high pressure water or high pressure helium in the cooling tubes placed in the blanket box structure. In the development of the blanket, it is very important to incorporate the safety technology as well as the performance improvement on tritium production and energy conversion. In the safety design and technology, coolant ingress in the blanket box structure is one of the most important events as the initiators. Especially the thermal hydraulics in the pebble bed in the case of the high pressure coolant ingress is very important to evaluate the pressure propagation and coolant flow behavior. This paper presents the preliminary results of the pressure loss characteristics by the coolant ingress in the pebble bed. Experiments have been performed by using alumina pebble bed (4 litter maximum volume of the pebble bed) and nitrogen gas to simulate the helium coolant ingress into breeder and multiplier pebble beds. Reservoir tank of 10 liter is filled with 1.0 MPa nitrogen. The nitrogen gas is released at the bottom part of the alumina pebble bed whose upper part is open to the atmosphere. The pressure change in the pebble bed is measured to identify the pressure loss. The measured values are compared with the predicted values by Ergun's equation, which is the correlation equation on pressure loss of the flow through porous medium. By the results of the experiments with no constraint on the alumina pebble bed, it was clarified that the measured value agreed in the lower flow rate. However, in the higher flow rate where the pressure loss is high, the measured value is about half of the predicted value. The differences between the measured values and the predicted values will be discussed from

  9. Development of Research Reactor Simulator and Its Application to Dynamic Test-bed

    International Nuclear Information System (INIS)

    Kwon, Kee Choon; Park, Jae Chang; Lee, Seung Wook; Bang, Dane; Bae, Sung Won

    2014-01-01

    We developed HANARO and the Jordan Research and Training Reactor (JRTR) real-time simulator for operating staff training. The main purpose of this simulator is operator training, but we modified this simulator as a dynamic test-bed to test the reactor regulating system in HANARO or JRTR before installation. The simulator configuration is divided into hardware and software. The simulator hardware consists of a host computer, 6 operator stations, a network switch, and a large display panel. The simulator software is divided into three major parts: a mathematical modeling module, which executes the plant dynamic modeling program in real-time, an instructor station module that manages user instructions, and a human machine interface (HMI) module. The developed research reactors are installed in the Korea Atomic Energy Research Institute nuclear training center for reactor operator training. To use the simulator as a dynamic test-bed, the reactor regulating system modeling software of the simulator was replaced by a hardware controller and the simulator and target controller were interfaced with a hard-wired and network-based interface

  10. Integrated design approach of the pebble BeD modular reactor using models

    International Nuclear Information System (INIS)

    Venter, Pieter J.; Mitchell, Mark N.

    2007-01-01

    The pebble bed modular reactor (PBMR) is the first pebble bed reactor that will be utilised in a high temperature direct Brayton cycle configuration. This implies that there are a number of unique features in the PBMR that extend from the German experience base. One of the challenges in the design of the PBMR is developing an understanding of the expected behaviour of the reactor through analyses and simulations and managing the integrated design process between the designers, the physicists and the analysts. This integrated design process is managed through model-based development work. Three-dimensional CAD models are constructed of the components and parts in the reactor. From the CAD models, CFD models, neutronic models, shielding models, FEM models and other thermodynamic models are derived. These models range from very simple models to extremely detailed and complex models. The models are used in legacy software as well as commercial off-the-shelf software. The different models are also used in code-to-code comparisons to verify the results. This paper will briefly discuss the different models and the interaction between the models, and how the models are used in the iterative design process that is used in the development of the reactor at PBMR

  11. Development of Research Reactor Simulator and Its Application to Dynamic Test-bed

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Kee Choon; Park, Jae Chang; Lee, Seung Wook; Bang, Dane; Bae, Sung Won [KAERI, Daejeon (Korea, Republic of)

    2014-08-15

    We developed HANARO and the Jordan Research and Training Reactor (JRTR) real-time simulator for operating staff training. The main purpose of this simulator is operator training, but we modified this simulator as a dynamic test-bed to test the reactor regulating system in HANARO or JRTR before installation. The simulator configuration is divided into hardware and software. The simulator hardware consists of a host computer, 6 operator stations, a network switch, and a large display panel. The simulator software is divided into three major parts: a mathematical modeling module, which executes the plant dynamic modeling program in real-time, an instructor station module that manages user instructions, and a human machine interface (HMI) module. The developed research reactors are installed in the Korea Atomic Energy Research Institute nuclear training center for reactor operator training. To use the simulator as a dynamic test-bed, the reactor regulating system modeling software of the simulator was replaced by a hardware controller and the simulator and target controller were interfaced with a hard-wired and network-based interface.

  12. Study on neutron diffusion and time dependence heat ina fluidized bed nuclear reactor

    International Nuclear Information System (INIS)

    Vilhena, M.T. de.

    1988-01-01

    The purpose of this work is to model the neutron diffusion and heat transfer for a Fluidized Bed Nuclear Reactor and its solution by Laplace Transform Technique with numerical inversion using Fourier Series. Also Gaussian quadrature and residues techniques were applied for numerical inversion. The neutron transport, diffusion, and point Kinetic equation for this nuclear reactor concept are developed. A matricial and Taylor Series methods are proposed for the solution of the point Kinetic equation which is a time scale problem of Stiff type

  13. Packed-fluidized-bed blanket concept for a thorium-fueled commercial tokamak hybrid reactor

    International Nuclear Information System (INIS)

    Chi, J.W.H.; Miller, J.W.; Karbowski, J.S.; Chapin, D.L.; Kelly, J.L.

    1980-09-01

    A preliminary design of a thorium blanket was carried out as a part of the Commercial Tokamak Hybrid Reactor (CTHR) study. A fixed fuel blanket concept was developed as the reference CTHR blanket with uranium carbide fuel and helium coolant. A fixed fuel blanket was initially evaluated for the thorium blanket study. Subsequently, a new type of hybrid blanket, a packed-fluidized bed (PFB), was conceived. The PFB blanket concept has a number of unique features that may solve some of the problems encountered in the design of tokamak hybrid reactor blankets. This report documents the thorium blanket study and describes the feasibility assessment of the PFB blanket concept

  14. Rotating-bed reactor as a power source for EM gun applications

    Energy Technology Data Exchange (ETDEWEB)

    Powell, J.; Botts, T.; Stickley, C.M.; Meth, S.

    1980-01-01

    Electromagnetic gun applications of the Rotating Bed Reactor (RBR) are examined. The RBR is a compact (approx. 1 m/sup 3/), (up to several thousand MW(th)), high-power reactor concept, capable of producing a high-temperature (up to approx. 300/sup 0/K) gas stream with a MHD generator coupled to it, the RBR can generate electric power (up to approx. 1000 MW(e)) in the pulsed or cw modes. Three EM gun applications are investigated: a rail gun thruster for orbit transfer, a rapid-fire EM gun for point defense, and a direct ground-to-space launch. The RBR appears suitable for all applications.

  15. Adjustement of Dancoff factor for calculating the cell of fluidized bed nuclear reactor

    International Nuclear Information System (INIS)

    Borges, V.; Sefidvash, F.

    1988-01-01

    A new nuclear reactor design based on the fluidized bed concept is under reserch and development. It utilized spherical fuel of slightly enriched zircaloy-clad uranium dioxide fluidized by light water under pressure since the Leopard code has been developed for light water reactor analysis, it was necessary to develop a method to determine the dimensions of the hypothetical fuel rod lattice, which are neutronically equivalent to the spherical fuel pellet lattice. This method is shown to calculate the Dancoff factor correctly. (author) [pt

  16. Rotating-bed reactor as a power source for EM gun applications

    International Nuclear Information System (INIS)

    Powell, J.; Botts, T.; Stickley, C.M.; Meth, S.

    1980-01-01

    Electromagnetic gun applications of the Rotating Bed Reactor (RBR) are examined. The RBR is a compact (approx. 1 m 3 ), (up to several thousand MW(th)), high-power reactor concept, capable of producing a high-temperature (up to approx. 300 0 K) gas stream with a MHD generator coupled to it, the RBR can generate electric power (up to approx. 1000 MW(e)) in the pulsed or cw modes. Three EM gun applications are investigated: a rail gun thruster for orbit transfer, a rapid-fire EM gun for point defense, and a direct ground-to-space launch. The RBR appears suitable for all applications

  17. AQUAPONIC SLUDGE DIGESTION FOR ORGANIC REDUCTION AND NUTRIENT REMINERALIZATION IN UASB REACTOR.

    OpenAIRE

    Delaide, Boris

    2017-01-01

    These first results on aquaponic sludge digestion are promising and highlight the interest to treat sludge directly onsite in order to reduce aquaponic system wastes and thus its impact on the environment and at the same time increase plant yield.

  18. 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.

  19. Hydrogen sulfide removal from air by Acidithiobacillus thiooxidans in a trickle bed reactor.

    Science.gov (United States)

    Ramirez, M; Gómez, J M; Cantero, D; Páca, J; Halecký, M; Kozliak, E I; Sobotka, M

    2009-09-01

    A strain of Acidithiobacillus thiooxidans immobilized in polyurethane foam was utilized for H(2)S removal in a bench-scale trickle-bed reactor, testing the limits of acidity and SO(4) (2-) accumulation. The use of this acidophilic strain resulted in remarkable stability in the performance of the system. The reactor maintained a >98-99 % H(2)S removal efficiency for c of up to 66 ppmv and empty bed residence time 98 % H(2)S was achieved under steady-state conditions, over the pH range of 0.44-7.30. Despite the accumulation of acidity and SO(4) (2-) (up to 97 g/L), the system operated without inhibition.

  20. Immobilized glucose oxidase--catalase and their deactivation in a differential-bed loop reactor.

    Science.gov (United States)

    Prenosil, J E

    1979-01-01

    Glucose oxidase containing catalase was immobilized with a copolymer of phenylenediamine and glutaraldehyde on pumice and titania carrier to study the enzymatic oxidation of glucose in a differential-bed loop reactor. The reaction rate was found to be first order with respect to the concentration of limiting oxygen substrate, suggesting a strong external mass-transfer resistance for all the flow rates used. The partial pressure of oxygen was varied from 21.3 up to 202.6 kPa. The use of a differential-bed loop reactor for the determination of the active enzyme concentration in the catalyst with negligible internal pore diffusion resistance is shown. Catalyst deactivation was studied, especially with respect to the presence of catalase. It is believed that the hydrogen peroxide formed in the oxidation reaction deactivates catalase first; if an excess of catalase is present, the deactivation of glucose oxidase remains small. The mathematical model subsequently developed adequately describes the experimental results.