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Showing papers on "Bioreactor published in 1995"


Journal ArticleDOI
TL;DR: It can be shown that there does not exist any need for ‘phase separation’ when treating non- or slightly acidified wastewaters and it looks necessary to reconsider theories for mass transfer in immobilized anaerobic biomass.
Abstract: Upflow Anaerobic Sludge Bed (UASB) wastewater (pre-)treatment systems represent a proven sustainable technology for a wide range of very different industrial effluents, including those containing toxic/inhibitory compounds. The process is also feasible for treatment of domestic wastewater with temperatures as low as 14-16 degrees C and likely even lower. Compared to conventional aerobic treatment systems the anaerobic treatment process merely offers advantages. This especially is true for the rate of start-up. The available insight in anaerobic sludge immobilization (i.e. granulation) and growth of granular anaerobic sludge in many respects suffices for practice. In anaerobic treatment the immobilization of balanced microbial communities is essential, because the concentration of intermediates then can be kept sufficiently low. So far ignored factors like the death and decay rate of organisms are of eminent importance for the quality of immobilized anaerobic sludge. Taking these factors into account, it can be shown that there does not exist any need for 'phase separation' when treating non- or slightly acidified wastewaters. Phase separation even is detrimental in case the acidogenic organisms are not removed from the effluent of the acidogenic reactor, because they deteriorate the settleability of granular sludge and also negatively affect the formation and growth of granular sludge. The growing insight in the role of factors like nutrients and trace elements, the effect of metabolic intermediates and end products opens excellent prospects for process control, e.g. for the anaerobic treatment of wastewaters containing mainly methanol. Anaerobic wastewater treatment can also profitably be applied in the thermophilic and psychrophilic temperature range. Moreover, thermophilic anaerobic sludge can be used under mesophilic conditions. The Expanded Granular Sludge Bed (EGSB) system particularly offers big practical potentials, e.g. for very low strength wastewaters (COD << 1 g/l) and at temperatures as low as 10 degrees C. In EGSB-systems virtually all the retained sludge is employed, while compared to UASB-systems also a substantially bigger fraction of the immobilized organisms (inside the granules) participates in the process, because an extraordinary high substrate affinity prevails in these systems. It looks necessary to reconsider theories for mass transfer in immobilized anaerobic biomass. Instead of phasing the digestion process, staging of the anaerobic reactors should be applied. In this way mixing up of the sludge can be significantly reduced and a plug flow is promoted. A staged process will provide a higher treatment efficiency and a higher process stability. This especially applies for thermophilic systems.

820 citations


Journal ArticleDOI
TL;DR: A simple fed-batch process for high cell density cultivation of Escherichia coli TG1 was developed to maintain carbon-limited growth using a defined medium and cell concentrations of 128 and 148 g per 1 dry cell weight were obtained using glucose or glycerol as carbon source.

463 citations


Journal ArticleDOI
TL;DR: Aside from mineralization, polyhydroxylated and chlorinated phenols as well as nitroaromatics and aromatic amines are susceptible to polymerization in aerobic environments and an alternative approach for bioremediation systems can be directed towards incorporating these aromatic pollutants into detoxified humic-like substances.
Abstract: Toxic aromatic pollutants, concentrated in industrial wastes and contaminated sites, can potentially be eliminated by low cost bioremediation systems. Most commonly, the goal of these treatment systems is directed at providing optimum environmental conditions for the mineralization of the pollutants by naturally occurring microflora. Electrophilic aromatic pollutants with multiple chloro, nitro and azo groups have proven to be persistent to biodegradation by aerobic bacteria. These compounds are readily reduced by anaerobic consortia to lower chlorinated aromatics or aromatic amines but are not mineralized further. The reduction increases the susceptibility of the aromatic molecule for oxygenolytic attack. Sequencing anaerobic and aerobic biotreatment steps provide enhanced mineralization of many electrophilic aromatic pollutants. The combined activity of anaerobic and aerobic bacteria can also be obtained in a single treatment step if the bacteria are immobilized in particulate matrices (e.g. biofilm, soil aggregate, etc.). Due to the rapid uptake of oxygen by aerobes and facultative bacteria compared to the slow diffusion of oxygen, oxygen penetration into active biofilms seldom exceeds several hundred micrometers. The anaerobic microniches established inside the biofilms can be applied to the reduction of electron withdrawing functional groups in order to prepare recalcitrant aromatic compounds for further mineralization in the aerobic outer layer of the biofilm. Aside from mineralization, polyhydroxylated and chlorinated phenols as well as nitroaromatics and aromatic amines are susceptible to polymerization in aerobic environments. Consequently, an alternative approach for bioremediation systems can be directed towards incorporating these aromatic pollutants into detoxified humic-like substances. The activation of aromatic pollutants for polymerization can potentially be encouraged by an anaerobic pretreatment step prior to oxidation. Anaerobic bacteria can modify aromatic pollutants by demethylating methoxy groups and reducing nitro groups. The resulting phenols and aromatic amines are readily polymerized in a subsequent aerobic step.

340 citations


Journal ArticleDOI
TL;DR: A structured metabolic model is developed that describes the stoichiometry and kinetics of the biological P removal process and satisfactorily describes the dynamic behavior of all components during the anaerobic and aerobic phases.
Abstract: A structured metabolic model is developed that describes the stoichiometry and kinetics of the biological P removal process. In this approach all relevant metabolic reactions underlying the metabolism, considering also components like adenosine triphosphate (ATP) and nic-otinamide-adenine dinucleotide (NADH(2)) are describedbased on biochemical pathways. As a consequence of the relations between the stoichiometry of the metabolic reactions and the reaction rates of components, the required number of kinetic relations to describe the process is reduced. The model describes the dynamics of the storage compounds which are considered separately from the active biomass. The model was validated in experiments at a constant sludge retention time of 8 days, over the anaerobic and aerobic phases in which the external oncentrations as well as the internal fractions of the relevant components involved in the P-removal process were monitored. These measurements include dissolved acetate, phosphate, and ammonium; oxygen consumption; poly-beta-hydroxybutyrate (PHB); glycogen; and active biomass. The model satisfactorily describes the dynamic behavior of all components during the anaerobicand aerobic phases.(c) 1995 John Wiley & Sons, Inc.

205 citations


Journal ArticleDOI
TL;DR: The kLa measurements and correlation with power density calculations for yeast re-suspension show that the kLa data in the pulsed baffled bioreactor are on average 75% higher than those obtained in the stirred tank (ST) fermenter.

132 citations


Journal ArticleDOI
TL;DR: Plug-flow biofilm reactors were colonized by microorganisms indigenous to streamwater and used to measure concentrations of biodegradable dissolved organic carbon in streamwater to determine the influence of physical, chemical, and biological factors on the operation of the bioreactors.

116 citations


Journal ArticleDOI
TL;DR: In this paper, a selection of aerobic biofilm reactors and activated sludge plants were investigated for the presence of methane producing bacteria (MPB) and sulfate reducing bacteria (SRB).

110 citations


Journal ArticleDOI
TL;DR: The similarity of kinetics in the three bioreactor configurations suggests that taxol production by T. baccata cell suspensions is amenable to scateup.
Abstract: The kinetics of biomass accumulation, nutrient uptake and taxol production of Taxus baccata cell suspensions were examined in three bioreactor configurations, viz. 250-mL Erienmeyerflasks, 1-L working volume pneumatically mixed (PMB), and stirred tank (STB) bioreactors. Qualitatively similar kinetics were observed in all three bioreactor types. Biomass accumulation and specific nutrient uptake rates exhibited biphasic characteristics. Carbohydrate uptake and biomass accumulation substantially ceased when phosphate was depleted from the medium. Phosphate was identified as a possible growth-limiting nutrient. Taxol accumulated exclusively in the second phase of growth. A maximum taxol concentration of 1.5 mg/L was obtained in the PMB which was fivefold greater than that obtained in the Erienmeyer flasks and the STB, but the relative kinetics of taxol production was the same in all three reactor types. Biomass yields were calculated from the kinetic data and a stoichiometry for biomass formation was evaluated. The similarity of kinetics in the three bioreactor configurations suggests that taxol production by T. baccata cell suspensions is amenable to scateup. (c) 1995 John Wiley & Sons, Inc.

106 citations


Journal ArticleDOI
TL;DR: In this article, the influence of high biomass concentration on the operating conditions of a newly developed high-performance bioreactor, the impinging-stream loop reactor, combined with membrane filtration is discussed.

103 citations


Journal ArticleDOI
TL;DR: Reactor performance was stable for continuous, long-term operation for both sterile and nonsterile unsupplemented acid whey feeds for the 6-month period studied.

96 citations


Journal ArticleDOI
TL;DR: A metabolic model of the biological phosphorus removal process was developed and verified over a wide range of growth rates, and one set of kinetic parameters was capable of describing the measured conversions of all components observed in the reactor as a function of the sludge retention time.
Abstract: The biological phosphorus removal process is a process which depends basically on three internal storage compounds. Poly-beta-hydroxybutyrate (PHB) produced during the anaerobic phase is used as substrate for biomass, polyphosphate, and glycogen formation. The reaction rates of the aerobic processes are primarily determined by the PHB content of the cells. This PHB content is highly dynamic due to the conversions during the anaerobic and aerobic phase of the cycle and the ratio between substrate addition and biomass present in the reactor. The amount of biomass present in the reactor is determined by the sludge retention time and growth rate. A metabolic model of the biological phosphorus removal process was developed and verified over a wide range of growth rates. The effect of different growth rates on the internal fractions of stored components was determined and described mathematically. One set of kinetic parameters was capable of describing the measured conversions of all components observed in the reactor as a function of the sludge retention time.

Journal ArticleDOI
TL;DR: The findings indicate that oxygen limitation acts in an analogous manner to substrate limitation imposed by dissolved nutrients, stimulating secondary metabolite production in some cases and inhibiting it in others.
Abstract: Summary: A miniature electrode was used to measure, for the first time, the time-dependent change in dissolved oxygen concentration of small-scale cultures of two actinomycete species at various aeration efficiencies in both complex and defined media Erythromycin was produced in both oxygen-limited and oxygen-sufficient conditions in shaken flask and inclined tube cultures of Saccharopolyspora erythraea and a further, novel, secondary metabolite was produced only under oxygen limitation In contrast, vancomycin was only produced in oxygen-sufficient cultures of Amycolatopsis orientalis Similar results were obtained in batch bioreactor cultures These findings indicate that oxygen limitation acts in an analogous manner to substrate limitation imposed by dissolved nutrients, stimulating secondary metabolite production in some cases and inhibiting it in others The implications of these findings in screening programmes for novel secondary metabolites are discussed

Journal ArticleDOI
TL;DR: The results concerning the possibility of using a continuous system able to operate at controlled water activity in a heterogeneous medium are reported and lipolytic enzyme in such a system appears to be a new process for the biotransformation of volatile esters.
Abstract: Fusarium solani cutinase and Candida cylindracea lipase were used to catalyze a transesterification reaction in a continuous gas/solid bioreactor. In this system, a solid phase composed of a packed enzymatic preparation was continuously percolated with carrier gas which fed substrate and removed reaction products simultaneously. Different conditions of immobilization were used and compared to the results obtained with a nonsupported enzyme. The enzymatic activity was found to be highly dependent of a key parameter: water activity (a(w)). Biocatalyst stability was greatly influenced by water activity and the choice of immobilization technique for the enzymatic material. For free and adsorbed enzymes, water requirements exhibited optima which corresponded to the complete hydration coverage of the protein. These optima presented a good correlation with the isotherm sorption curves obtained for the different preparations. In this work are reported the results concerning the possibility of using a continuous system able to operate at controlled water activity in a heterogeneous medium. Lipolytic enzyme in such a system appears to be a new process for the biotransformation of volatile esters.

Journal ArticleDOI
TL;DR: In this article, three lab-scale rotating drum biofilm reactors (RDBRs) were used to culture the biofilms, and microelectrodes and a microslicing technique have been used to elucidate changes in the structure of bio-films with depth and to determine the influence of these changes on mass transport and transformation processes.

Journal ArticleDOI
TL;DR: The potential of this type of bioreactor is emphasized from the point of view of the different number of possible modifications in the design both of the bioreactors and the biocatalytic particles, in order to enhance its operation.
Abstract: Fluidized-bed reactors present a number of advantages that make them an attractive alternative in processes involving biocatalysts. However, fluidized-bed bioreactors are also realtively complex, basically for two reasons. First, their use requires the biocatalyst, commonly cells or enzymes, to be immobilized into or onto a solid support. Second, the hydrodynamic characterization is difficult, especially in those systems where three phases (gas—liquid—solid) are involved. The mathematical model of a fluidized-bed bioreactor needs to take into account those hydrodynamic aspects that will determine the flux model in the reactor. Moreover, the description of other aspects is also required: the mechanisms of transport between the different phases, the kinetic equations for the phenomena taking place in the biocatalytic particles, such as cell growth, product formation, substrate consumption, enzyme deactivation, and the mass balance equations in the reactor. In addition to these aspects, the application of fluidized-bed bioreactors to different kind of processes is also discussed. The potential of this type of bioreactor is also emphasized from the point of view of the different number of possible modifications in the design both of the bioreactor and the biocatalyst particles, in order to enhance its operation.

Journal ArticleDOI
TL;DR: Compared with conventional batch fermentation, the recycle batch fermentation with the immobilized cell bioreactor allows faster fermentation, produces a higher concentration of product, and can be run continually without significant downtime.
Abstract: Recycle batch fermentations using immobilized cells of Propionibacterium acidipropionici were studied for propionate production from whey permeate, de-lactose whey permeate, and acid whey. Cells were immobilized in a spirally wound fibrous sheet packed in a 0.5-L column reactor, which was connected to a 5-L stirred tank batch fermentor with recirculation. The immobilized cells bioreactor served as a breeder for these recycle batch fermentations. High fermentation rates and conversions were obtained with these whey media without nutrient supplementation. It took approximately 55 h to ferment whey permeate containing approximately 45 g/L lactose to approximately 20 g/L propionic acid. Higher propionate concentrations can be produced with various concentrated whey media containing more lactose. The highest propionic acid concentration obtained with the recycle batch reactor was 65 g/L, which is much higher than the normal maximum concentration of 35 to 45 g/L reported in the literature. The volumetric productivity ranged from 0.22 g/L x h to 0.47 g/L x h, depending on the propionate concentration and whey medium used. The corresponding specific cell productivity was 0.033 to 0.07 g/L x g cell. The productivity increased to 0.68 g/L x h when whey permeate was supplemented with 1% (w/v) yeast extract. Compared with conventional batch fermentation, the recycle batch fermentation with the immobilized cell bioreactor allows faster fermentation, produces a higher concentration of product, and can be run continually without significant downtime. The process also produced similar fermentation results with nonsterile whey media.

Journal ArticleDOI
TL;DR: Scenedesmus obliquus cells adsorbed in hydrophilic, commercially available polymeric foams are of potential value for biologic N depollution of drinking waters contaminated with nitrogenous fertilizers.

Journal ArticleDOI
TL;DR: The results of the mathematical analysis confirmed that the biofilm has two major effects on system performance: (a) it prevents direct contact between DCE and the aerating gas, thus avoiding air stripping; and (b) it limits the flux of DCE across the membrane with consequent accumulation of D CE at the membrane-biofilm interface, which reduces the mass transfer driving force for DCE extraction from the wastewater.

Journal ArticleDOI
TL;DR: A modified integrated form of the Michaelis-Menten equation is proposed to describe the removal of metal ion by a columnar bioreactor, where the efficiency of metal removal is semi-quantitatively related to the input flow rate, the total enzyme loading and theBioreactor activity.
Abstract: Biofilm-immobilised Citrobacter sp removed uranyl ion from flows supplemented with glycerol 2-phosphate The metal uptake mechanism was mediated by the activity of a cell-surface bound phosphatase that precipitated liberated inorganic phosphate with uranyl ion as HUO 2 PO 4 4H 2 O at the bacterial surface A modified integrated form of the Michaelis-Menten equation is proposed to describe the removal of metal ion by a columnar bioreactor, where the efficiency of metal removal is semi-quantitatively related to the input flow rate, the total enzyme loading (E 0 ) and the bioreactor activity With biofilm immobilised bacteria, E 0 was further divisible (split) into subparameters of phosphatase titre per bacterium and total biomass surface area Varying the split E 0 and the reaction temperature modified the bioreactor performance The immobilised bacteria retained high metal loads without loss in steady-state activity Accumulated metal was recovered as a concentrated solution

Journal ArticleDOI
TL;DR: Among the three different baffle geometries investigated, the orifice baffles gave the highest and sharpest increase in the oxygen transfer rate, and the trends in the kLa measurements are consistent with the fluid mechanics observed within both the systems and previous work.
Abstract: We report experimental data of mass transfer of oxygen into yeast resuspension in a pulsed baffled bioreactor. The bioreactor consists of a 50-mm-diameter column with the presence of a series of either wall (orifice) or central (disc) baffles or a mixture of both where fluid oscillation can also be supermposed during the experiments. Air bubbles are sparged into the bottom of the pulsed baffled bioreactor, and the kinetics of liquid oxygen concentration in the yeast solution is followed using a dissolved oxygen probe with a fast response time of 3 s together with the dynamic gassing-out technique. Among the three different baffle geometries investigated, the orifice baffles gave the highest and sharpest increase in the oxygen transfer rate, and the trends in the kLa measurements are consistent with the fluid mechanics observed within both the systems and previous work. In addition, we have also compared the kLa values with those obtained in a stirred tank; an 11% increase in the KLa is reported. © 1995 John Wiley & Sons, Inc.

Journal ArticleDOI
TL;DR: In this paper, continuous flow anaerobic fluidized-bed granular activated carbon bioreactors were used to treat 2,4-dinitrotoluene (2-4-DNT), a compound used in primary propellant production.
Abstract: Continuous-flow anaerobic fluidized-bed granular activated carbon bioreactors were used to treat 2,4-dinitrotoluene (2,4-DNT), a compound used in primary propellant production. A synthetic wastewater solution containing 2,4-DNT, ethanol, mineral ether, and a carbonate buffer and another solution containing growth nutrients and vitamins were fed to each of the two bioreactors. The influent ethanol concentrations were varied to determine the effect of ethanol concentration on the extent of 2,4-DNT degradation. The anaerobic bioreactors, when operated under methanogenic conditions with a primary substrate, were able to transform the 2.4-DNT into 2-amino-4-nitrotoluene (2-A-4-NT). 4-amino-2-nitrotoluene (4-A-2-NT), 2,4-diaminotoluene (2,4-DAT), and trace amounts of toluene. During stable operation, for the range of non-zero influent ethanol concentrations evaluated in this study, the majority of the products were identified as 2,4-DAT. Batch activated sludge reactors were used to examine the fate of 2,4-DAT under aerobic conditions. 2,4-DAT (16 mg/L) were mineralized within 9 hours, indicating that a two-stage system may be an effective 2,4-DNT treatment strategy.

Journal ArticleDOI
TL;DR: Propene transfer from air to a suspension of propene‐utilizing Xanthobacter Py2 cells in the membrane bioreactor proved to be controlled by mass transfer in the liquid phase by simulating propene transfer rates agreed well with the experimental data.
Abstract: A novel type of bioreactor for waste gas treatment has been designed. The reactor contains a microporous hydrophobic membrane to create a large interface between the waste gas and the aqueous phase. To test the new reactor, propene was chosen because of its high air/water partition coefficient, which causes a low water concentration and hampers its removal from air. Propene transfer from air to a suspension of propene-utilizing Xanthobacter Py2 cells in the membrane bioreactor proved to be controlled by mass transfer in the liquid phase. The resistance of the membrane was negligible. Simulated propene transfer rates agreed well with the experimental data. A stable biofilm of Xanthobacter Py2 developed on the membrane during prolonged operation. The propene flux into the biofilm was 1 x 10(-6) mol m(-2) s(-1) at a propene concentration of 9.3 x 10(-2) mol m(-3) in the gas phase. (c) 1995 John Wiley & Sons, Inc.

Journal ArticleDOI
TL;DR: In this article, the influence of operating conditions such as medium composition, light intensity, carbon dioxide concentration in the flushing gas, culture temperature, and gas flow rate, on photosynthesis of Dunaliella tertiolecta were studied using a chemometrics approach.
Abstract: Two kinds of bioreactors, a bubble-column and an air-lift bioreactor, have been designed. The influence of operating conditions such as medium composition, light intensity, carbon dioxide concentration in the flushing gas, culture temperature, and gas flow rate, on photosynthesis of Dunaliella tertiolecta were studied using a chemometrics approach. The bubble-column bioreactor system was shown to be advantageous over the air-life because of a weaker intensity of hydrodynamic stress derived from gas bubble dispersion and culture broth mixing. Optimal conditions for carbon dioxide fixation or maximal growth rate were determined. The effect of hydrodynamic shear forces on the algal wall produced by gas bubbling was identified as one of the most significant factors for algal growth.

Journal ArticleDOI
TL;DR: Among the different chemicals employed to counteract the pH drop in the fermentation broth, CaCO3 gave the best results and was used as neutralizing agent for Penicillium variabile P16.


Patent
27 Mar 1995
TL;DR: A combination of an MP MBR with an ATA MBR is highly effective when the MPB produces high BOD concentration mixed liquor for destruction by the ATAB.
Abstract: A wastewater feed containing an ultimate BOD/COD ratio >0.6 is well-suited for especially acclimated thermophilic and/or caldo-active living micro-organisms ("hot cells") which thrive in an autothermal aerobic (ATA) reaction zone having an ATA bioreactor ("ATAB") operating at substantially ambient atmospheric pressure in combination with a MF or UF membrane filtration device from which a solids-free permeate may be withdrawn. This combination, of ATAB and membrane device is a "membrane bioreactor" (ATA MBR), which operates autothermally with a feed containing biodegradable organic materials having a BOD of at least 5,000 mg/L, preferably at least 10,000 mg/L (10 g/L) with a minor portion of "municipal" wastewater or domestic sewage. Operation of the ATAB, preferably in the thermophilic range from 45° C.-75° C., with constant HRT from 1 to 12 days, is contingent upon maintaining a stable population of live hot cells. Such cells enhance the biokinetics of degradation and allow operation of the ATAB at higher COD loading and a lower concentration of TSS, than would be possible at a lower temperature. A surprisingly high membrane productivity allows production of much less sludge to be disposed of outside the system, than would have to be disposed of with a conventional mesophilic reactor in normal operation with a HRT of less than 24 hr. A combination of an MP MBR with an ATA MBR is highly effective when the MPB produces high BOD concentration mixed liquor for destruction by the ATAB.

Journal ArticleDOI
TL;DR: The anaerobic processing of pretreated OMW seemingly involved no inhibition phenomena as the biotoxicity and the total phenolic compound content were reduced by 71.2% and 77.9% respectively as a result of the pretreatment.
Abstract: A kinetic study was carried out on the anaerobic digestion of olive-mill wastewater (OMW) and OMW that was previously fermented with Aspergillus terreus. The bioreactors used were batch fed and contained saponite as support for the mediating bacteria. The anaerobic digestion process followed first-order kinetics, from which the kinetic constant A was calculated using a non-linear regression. This kinetic parameter was influenced by the pretreatment carried out, and was 3.7 times higher for pretreated OMW than for untreated OMW. The anaerobic processing of pretreated OMW seemingly involved no inhibition phenomena as the biotoxicity and the total phenolic compound content (analysed by HPLC) were reduced by 71.2% and 77.9% respectively as a result of the pretreatment. Finally, the yield coefficient of methane production was 0.345 litres of methane (at standard temperature and pressure)/g of chemical oxygen demand, that is, 23% higher than that provided by untreated wastewater.

Journal ArticleDOI
TL;DR: A model was developed to describe the consumption of glucose within beads based on Michaelis–Menten kinetics and the diffusion of glucose into beads and confirmed that the observed reduction in ethanol yield compared with free yeast cells was caused by the lower substrate concentration towards the centre of the bead.
Abstract: Yeast, immobilised in alginate beads of known standard size and mechanical strength, has been utilised in a novel design of fluidised bed bioreactor which avoids problems of particle flotation and gas logging. Circulating substrate simultaneously entered the top and bottom of the bed. The bioreactor operated reliably for periods of up to 20 days. Increasing alginate concentration in the range 1–5% (w/w) had little effect on the performance of the immobilised yeast in converting ethanol to glucose but reduced the tendency of beads to split. Increasing bead diameter in the range 1–5 mm increased the tendency to split and reduced overall conversion of glucose. A model was developed to describe the consumption of glucose within beads based on Michaelis–Menten kinetics and the diffusion of glucose into beads. Application of the model to experimental results showed maximum reaction velocity to be independent of bead diameter and alginate concentration. The model confirmed that the observed reduction in ethanol yield compared with free yeast cells was caused by the lower substrate concentration towards the centre of the bead as opposed to any change in the metabolic rate of the immobilised cells.

Journal ArticleDOI
TL;DR: An anaerobic bioreactor system was operated in a batch recycle mode to establish the microbial biodegradation of Aroclor 1248-spiked sediment, utilizing sanitary landfill leachate as a novel carbon, nutrient, and or microbial source.
Abstract: An anaerobic bioreactor system was operated in a batch recycle mode to establish the microbial biodegradation of Aroclor 1248-spiked sediment, utilizing sanitary landfill leachate as a novel carbon, nutrient, and/or microbial source. Experiments conducted on two bioreactors confirmed that significant dechlorination of Aroclor 1248-spiked sediments occurred. After 13 weeks of operation, the average total chlorine/biphenyl of the original Aroclor was reduced by 11% and 23%, with the majority of dechlorination occurring within 7 weeks. No dechlorination was observed in the sterilized control reactor. The overall significance is the first reported occurrence of anaerobic dechlorination of a PCB-contaminated sediment in a low-cost laboratory-scale bioreactor system. The environmental significance is the reduction in chlorine content of the original Aroclor, an important component in any environmental bioremediation program. Innovative approaches to laboratory-scale bioreactor monitoring and bioreactor design principles applicable to hazardous waste containment areas are also discussed.

Patent
31 Mar 1995
TL;DR: In this paper, an arrangement for conducting air filtration by biofilter operation is provided, which generally includes at least one bioreactor bed, through which air to be purified is passed.
Abstract: An arrangement for conducting air filtration by biofilter operation is provided. The arrangement generally includes at least one bioreactor bed, through which air to be purified is passed. Preferably the arrangement is configured so that air flow through each tank is from the top downwardly. In general, the biofiltration operation is conducted under pressures of less than ambient, to advantage.