Home About us Contact
|
Home About us Contact | ||
|
|
||
Membrane Bioreactor (membrane + bioreactor)
Selected AbstractsMembrane bioreactors for regenerative medicine: an example of the bioartificial liverASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010Sabrina Morelli Abstract Liver transplantation is the only established treatment for liver failure. Because of the organ scarsity, liver support strategies are being developed with the aim of either supporting patients with the borderline functional liver cell mass until the organ transplantation or liver regeneration. A bioartificial liver (BAL) consisting of functional liver cells supported by an artificial cell culture material could provide a vital temporary support to patients with liver failure, and could serve as a bridge to transplantation while awaiting a suitable donor. In this paper, we discuss the critical issues for the development of BAL such as bioreactor configuration, mass transfer, cell source and culture technique. The characteristics of membrane BAL systems in clinical, preclinical and in vitro tests are reviewed. Membrane bioreactors used for the generation of in vitro physiological model systems for studying biological mechanisms and testing the efficacy of potential therapies are also discussed. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Membrane bioreactors: overview of the effects of module geometry on mixing energyASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009Yuan Wang Abstract Membranes used in municipal membrane bioreactor (MBR) plants can be configured as flat sheet (FS) membranes or hollow fibre (HF) membranes. The HFs can be mounted either horizontally or vertically. The membranes can be immersed in their own vessel or within the aerobic vessel. These various configurations combine to give a unique reactor design. Current methods of design assume the mixing characteristics (e.g. each reactor vessel is completely mixed); hence the energy necessary to achieve complete mixing cannot be optimised. This paper presents an overview of mixing studies undertaken by the authors' research group on pilot- and full-scale MBRs through residence time distribution (RTD) analysis and computational fluid dynamics (CFD) modelling. The drawbacks of current technique for the sizing of MBRs (e.g. compartmental modelling) are highlighted. The use of CFD as a design tool to evaluate the mixing and energy of MBRs with different configurations (e.g. HF vs FS, inside submerged vs outside submerged) is presented. The MBR CFD model was validated using field-measured RTD data and compared with compartmental model. Results from mixing studies suggest that HF membranes are more energy efficient in terms of creating completely mixed conditions than the FS membranes. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Post-treatment of anaerobically treated medium-age landfill leachateENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2010Ebru Akkaya Abstract This study focused on the removal of COD and NH4+ from medium-age leachate. Experiments were performed in a laboratory-scale upflow anaerobic sludge blanket (UASB), a membrane bioreactor (MBR), and using magnesium ammonium phosphate (MAP) precipitation. MBR and MAP were used for the post-treatment steps for anaerobically treated leachate to increase the removal of organics and ammonium. The UASB reactor removed nearly all biodegradable organics and supplied constant effluent COD for all concentration ranges of influent leachate. Ammonium removal efficiency in the UASB reactor was relatively low and the average value was ,7.9%. Integration of MBR to the effluent of UASB reactor increased the average COD removal efficiency from 51.8 to 65.6% and maximum removal efficiency increased to 74.3%. MAP precipitation was applied as a final step to decrease the ammonium concentration in the effluent of UASB+MBR reactors. The effect of pH and the molar ratio of MAP constituents on the removal of ammonium were evaluated. At optimal conditions (pH: 9.0 and Mg/NH4/PO4: 1/1.2/1.2), 96.6% of ammonium was removed and MAP provided additional COD and turbidity treatment. Consequently, the combined system of MBR and MAP precipitation could be used as an appropriate post treatment option for the anaerobically treated medium-age landfill leachate. © 2009 American Institute of Chemical Engineers Environ Prog, 2010 [source] Industrial wastewater treatment in a membrane bioreactor: A reviewENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2004B. Marrot Abstract This paper provides a detailed literature review of wastewater treatment in a membrane bioreactor process (MBR) with special focus on industrial wastewater treatment. MBR systems are compared with conventional wastewater treatment systems. The characteristics of the bioreactor treatment process (biomass concentration and floc size, organic and mass loading rates, etc.) are examined. The membrane separation of microorganisms from the treated wastewater is discussed in detail. Problems of membrane fouling and membrane washing and regeneration, linked to activated sludge characteristics, are examined. © 2004 American Institute of Chemical Engineers Environ Prog, 23: 59,68, 2004 [source] Effect of thermochemical sludge pretreatment on sludge reduction and on performances of anoxic-aerobic membrane bioreactor treating low strength domestic wastewaterJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2009Khac-Uan Do Abstract BACKGROUND: Reduction of excess sludge production has become an urgent issue. An investigation into the influence of thermochemical sludge pretreatment on sludge reduction in a bench-scale anoxic-aerobic membrane bioreactor was performed. Two systems were operated. In one system, part of the mixed liquid (1.5% of the influent flow rate) was pretreated thermochemically (at 80 °C, pH 11 and 3 h) and returned to the bioreactor. This study examined and evaluated the effect of thermochemical sludge pretreatment on the reduction of excess sludge and on the performance of the system. RESULTS: The average solubilization efficiency of the pretreated sludge was found to be about 0.2. The sludge production rate of the experimental system (E-MBR) was less than that of the control (C-MBR) by about 33%. The total phosphorus was removed mainly by normal cell synthesis, with removal efficiencies of 38,40% and 40,42% for the E-MBR and C-MBR, respectively. The total nitrogen removal in the E-MBR was slightly higher than in the C-MBR due to supply of soluble chemical oxygen demand (SCOD) from the digested sludge solution as an external carbon source. The mixed liquor volatile suspended solids (MLVSS) and mixed liquor suspended solids (MLSS) ratios for the two systems were almost identical, in the range 74,77%, indicating that the inorganics from the disintegrated cells do not accumulate as particulates in the reactor. The TMP was maintained at less than 6 cmHg for 180 days without membrane cleaning. CONCLUSION: Thermochemical sludge pretreatment can play an important role in reducing sludge production. The qualities of the effluent water were not significantly affected during 6 months of operation. Copyright © 2009 Society of Chemical Industry [source] The beneficial role of intermediate clarification in a novel MBR based process for biological nitrogen and phosphorus removalJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2009MinGu Kim Abstract BACKGROUND: A novel membrane bioreactor (MBR) is described, employing an intermediate clarifier. Unlike the established function of a final clarifier in a conventional biological nutrient removal system, the role of an intermediate clarifier has rarely been studied. Thus, this work focused on explaining the fate of nutrients in the intermediate clarifier, as influenced by the hydraulic retention time (HRT) of the preceding anaerobic bioreactor. RESULTS: The system was tested with two different anaerobic/anoxic/aerobic biomass fractions of 0.25/0.25/0.5 (run 1) and 0.15/0.35/0.45 (run 2) using synthetic wastewater. The major findings of the study were that phosphorus (P) removal was affected by the role of the intermediate clarifier. In run 1, P was removed at a rate 0.16 g d,1 in the intermediate clarifier while in run 2, additional P was released at 0.49 g d,1. The nitrogen (N) removal efficiencies were 74 and 75% for runs 1 and 2 respectively, while P removal was 91 and 96%. P uptake by denitrifying phosphate accumulating organisms (DPAOs) accounted for 41,52% of the total uptake in the MBR. CONCLUSIONS: This study found that the intermediate clarifier assisted chemical oxygen demand (COD), N, and P removal. With respect to the fate of P, the intermediate clarifier functioned as an extended anaerobic zone when the HRT of the preceding anaerobic zone was insufficient for P release, and as a pre-anoxic zone when the anaerobic HRT was adequate for P release. Copyright © 2008 Society of Chemical Industry [source] Enhanced ethanol production from enzymatically treated steam-exploded rice straw using extractive fermentationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 8 2001Yoshitoshi Nakamura Abstract Alcohol fermentation of an enzymatic hydrolyzate of exploded rice straw was studied experimentally. Rice straw was treated under variable conditions, such as steam pressure and steaming time. The exploded rice straw was separated into water-soluble material, methanol-soluble lignin, Klason lignin, and a mixture of cellulose and a low molecular weight substance. The effects of steam explosion on the characteristics of the exploded rice straw were clarified from the point of view of the amounts of extractive components. Steam explosion was found to be effective for the delignification of rice straw and for increasing its susceptibility to enzyme hydrolysis and alcohol fermentation. The polysaccharides (cellulose and hemicellulose) in the rice straw treated at a steam pressure of 3.5,MPa with a steaming time of 2,min were hydrolyzed almost completely into monosaccharides, (ie glucose and xylose) by a mixture of Trichoderma viride cellulase (Meicelase) and Aspergillus aculeatus cellulase (Acucelase). The enzymatic hydrolyzate of exploded rice straw was converted into ethanol efficiently by Pichia stipitis and the ethanol yield from sugar was about 86%(w/w) of the theoretical value. The ethanol concentration in a membrane bioreactor coupled with a pervaporation system reached 50,gdm,3 and was about five times higher than that in the culture broth. The energy efficiency (ratio of combustion energy of ethanol produced to energy for steam explosion) reached a maximum value at a pressure of 3.5,MPa for 2,min. © 2001 Society of Chemical Industry [source] Double-deck aerated biofilm membrane bioreactor with sludge control for municipal wastewater treatmentAICHE JOURNAL, Issue 5 2009Jirachote Phattaranawik Abstract Alternative designs of an aerated moving-bed biofilm reactor and a flat-sheet membrane module for a biofilm membrane bioreactor process have been investigated to overcome a membrane clogging problem and to determine the performance of a new membrane module. Double-deck aerated biofilm reactor with integrated designs of sludge hopper, thickener, and velocity-zone concept for particle settlement was evaluated for the suspended solid control and removal. Hydrodynamics of bubbling, liquid, and solid particles were arranged in the bioreactor to obtain a particle settlement. New membrane modules used under low suspended solid environment having smaller membrane gaps were evaluated for filtration performance and clogging problems for long-term operation. The average suspended solids concentration in the bioreactor effluent was 44.6 mg/L. Relaxation applied with the membrane module provided the most optimum result for fouling control, and no clogging problems in the modules were observed in the system after continuous operation of 3 weeks. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Design and application of a membrane bioreactor unit to upgrade and enhance the required performance of an installed wastewater treatment plantASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010Teresa Castelo-Grande Abstract Wastewater treatment plants (WWTPs) are nowadays common solutions to improve the quality of streams and soils. However, there are still many issues required to be solved within these plants. We were commissioned to redesign a WWTP in Amarante, Portugal, which was not working properly. Among the several units we have designed, there is a membrane bioreactor representing one of the main units of this remodelled WWTP. The biological treatment stage at the upgraded WWTP will take place in the remodelled primary and secondary settlers and in the remodelled and improved biological reactor. Hence, the primary settler is readapted in such a way that it functions as the anoxic area of the biological treatment, while the aerobic treatment will be sequentially performed at the remodelled biological reactor and at the actual secondary settler. Membrane treatment will be performed by using ultrafiltration membranes. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Basic equations of mass transfer through biocatalytic membrane layerASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009Endre Nagy Abstract The diffusive and convective mass transport through biocatalytic membrane layer (membrane bioreactor), without and with biochemical reactions, have been investigated. Similarly to the two-film theory for gas-liquid system with diffusive mass transport, only, mass transfer rates have been developed for the biocatalytic membrane layer and for the concentration boundary layer on the feed side of the membrane. Overall mass transfer coefficient has also been defined involving the two-layer, simultaneous mass transfer, namely the mass transfer through the concentration boundary layer and biocatalytic membrane layer. The effect of the convective velocity (Pe number) and the biochemical reaction rate, namely first-order and zero-order reactions as limiting cases of the Monod kinetics, are demonstrated on the mass transfer coefficients accompanied by chemical reaction and on the concentration profiles. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Membrane bioreactors: overview of the effects of module geometry on mixing energyASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009Yuan Wang Abstract Membranes used in municipal membrane bioreactor (MBR) plants can be configured as flat sheet (FS) membranes or hollow fibre (HF) membranes. The HFs can be mounted either horizontally or vertically. The membranes can be immersed in their own vessel or within the aerobic vessel. These various configurations combine to give a unique reactor design. Current methods of design assume the mixing characteristics (e.g. each reactor vessel is completely mixed); hence the energy necessary to achieve complete mixing cannot be optimised. This paper presents an overview of mixing studies undertaken by the authors' research group on pilot- and full-scale MBRs through residence time distribution (RTD) analysis and computational fluid dynamics (CFD) modelling. The drawbacks of current technique for the sizing of MBRs (e.g. compartmental modelling) are highlighted. The use of CFD as a design tool to evaluate the mixing and energy of MBRs with different configurations (e.g. HF vs FS, inside submerged vs outside submerged) is presented. The MBR CFD model was validated using field-measured RTD data and compared with compartmental model. Results from mixing studies suggest that HF membranes are more energy efficient in terms of creating completely mixed conditions than the FS membranes. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] A novel biphasic extractive membrane bioreactor for minimization of membrane-attached biofilmsBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2003Antonietta Splendiani Abstract Extractive membrane bioreactor (EMB) systems offer a means of biologically treating wastewaters, but, like other membrane processes, are constrained by their tendency to be fouled by membrane-attached biofilms (MABs). This study describes a new approach to eradicate MAB formation and accumulation in EMB systems. To this end, an innovative EMB configuration, the biphasic extractive membrane bioreactor (BEMB), has been developed. In BEMB systems, the two main constituents of the EMB process, membrane and bacteria, are kept separated and interact via a suitable recirculating solvent. Nineteen candidate solvents were tested to assess their suitability for BEMB application. Based on the results of the solvent selection, guidelines are provided to screen solvents for BEMB application. BEMB and EMB runs were carried out to demonstrate the effectiveness of BEMB technology in avoiding MAB accumulation and to compare BEMB and EMB performance. A synthetic wastewater containing monochlorobenzene (MCB) was used as a model system. Abiotic BEMB and EMB runs were carried out and used as comparative references for estimating the effect of MAB accumulation on system performance. MAB thickness in the BEMB systems was controlled at 18 ,m during 1 month of operation, whereas, in the EMB systems, MAB thickness reached 1250 ,m. Analysis of mass transport in EMB and BEMB systems revealed that the high affinity of the permeating molecules for the solvent may contribute to a reduction in shell-side mass transfer resistance. This reduction of shell-side mass transfer resistance and the absence of MAB accumulation led to overall mass transfer coefficients of about sevenfold greater (4.5 × 10,5 m s,1) in the BEMB system than in the EMB system (0.6 × 10,5 m s,1). © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 8,19, 2003. [source] Experimental Study and Design of a Submerged Membrane Distillation BioreactorCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 1 2009J. Phattaranawik Abstract A hybrid process incorporating membrane distillation in a submerged membrane bioreactor operated at elevated temperature is developed and experimentally demonstrated in this article. Since organic particles are rejected by an ,evaporation' mechanism, the retention time of non-volatile soluble and small organics in the submerged membrane distillation bioreactor (MDBR) is independent of the hydraulic retention time (mainly water and volatiles). A high permeate quality can be obtained in the one-step compact process. The submerged MD modules were designed for both flat-sheet membranes and tubular membrane configurations. The process performance was preliminarily evaluated by the permeate flux stabilities. The module configuration design and air sparging used in the MDBR process were tested. Flux declines were observed for the thin flat-sheet hydrophobic membranes. Tubular membrane modules provided more stable permeate fluxes probably due to the turbulent condition generated from air sparging injected inside the tubular membrane bundles. The experiments with the submerged tubular MD module gave stable fluxes of approximately 5,L/m2 h over 2,weeks at a bioreactor temperature of 56,°C. The total organic carbon in the permeate was consistently lower than 0.7,mg/L for all experiments. [source] Analysis of the Activated Sludge Process in an MBR under Starvation ConditionsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 3 2006M. Vukovic Abstract An aerobic membrane bioreactor (MBR) at complete biomass retention was studied over a period of time under starvation conditions. Kinetic parameters were determined in a no-feed batch test. The decay rate of activated sludge, kd = 0.05,d,1, was determined by tracking the decrease of MLSS. The ratio of MLVSS/MLSS was in the range 0.76,0.85. The pH values were between 7.02 and 8.23. As a function of different initial concentrations of MLSS, specific nitrification rates qN, decreased from 4.23 to 0.02,mg-N/(g,MLVSS,d) and specific biodegradation rates qb increased from 0.23 to 1.90,mg-COD/(g,MLVSS,d). From experimental data the kinetic constants for respiration, which followed Monod kinetics, were determined as qO2max = 9.8,mg-O2/(g,MLVSS,h), Kx = 2.9,g/dm3. Additionally, a linear correlation between MLSS and mean floc size was found to exist during the biodegradation process. [source] Bioprocesses for air pollution controlJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2009Christian Kennes Abstract Bioprocesses have been developed as relatively recent alternatives to conventional, non-biological technologies, for waste gas treatment and air pollution control in general. This paper reviews major biodegradation processes relevant in this field as well as both accepted and major innovative bioreactor configurations studied or used nowadays for the treatment of polluted air, i.e. biofilters, one- and two-liquid phase biotrickling filters, bioscrubbers, membrane bioreactors, rotating biodiscs and biodrums, one- and two-liquid phase suspended growth bioreactors, as well as hybrid reactor configurations. Some of these bioreactors are being used at full-scale for solving air pollution problems, while others are still at the research and development stage at laboratory- or pilot-scale. Copyright © 2009 Society of Chemical Industry [source] Definition and validation of operating equations for poly(vinyl alcohol)-poly(lactide-co-glycolide) microfiltration membrane-scaffold bioreactorsBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2010R.J. Shipley Abstract The aim of this work is to provide operating data for biodegradable hollow fiber membrane bioreactors. The physicochemical cell culture environment can be controlled with the permeate flowrate, so this aim necessitates the provision of operating equations that enable end-users to set the pressures and feed flowrates to obtain their desired culture environment. In this paper, theoretical expressions for the pure water retentate and permeate flowrates, derived using lubrication theory, are compared against experimental data for a single fiber poly(vinyl alcohol),poly(lactide-co-glycolide) crossflow module to give values for the membrane permeability and slip. Analysis of the width of the boundary layer region where slip effects are important, together with the sensitivity of the retentate and permeate equations to the slip parameter, show that slip is insignificant for these membranes, which have a mean pore diameter of 1.1,µm. The experimental data is used to determine a membrane permeability, of k,=,1.86,×,10,16,m2, and to validate the model. It was concluded that the operating equation that relates the permeate to feed ratio, c, lumen inlet flowrate, Ql,in, lumen outlet pressure, P1, and ECS outlet pressure, P0, is (1) where A and B are constants that depend on the membrane permeability and geometry (and are given explicitly). Finally, two worked examples are presented to demonstrate how a tissue engineer can use Equation (1) to specify operating conditions for their bioreactor. Biotechnol. Bioeng. 2010;107: 382,392. © 2010 Wiley Periodicals, Inc. [source] | ||||||||||