Showing papers on "Bioreactor published in 1996"

Biological production of acetic acid from waste gases

Abstract: A method and apparatus for converting waste gases from industrial processes such as oil refining, carbon black, coke, ammonia, andmethanol production, into useful products is disclosed. The method includes introducing the waste gases into a bioreactor where they are fermented to various products, such as organic acids, alcohols H2, SCP, and salts of organic acids by anaerobic bacteria within the bioreactor. These valuable end products are then recovered, separated and purified.

Long-Term Continuous Cultivation of Clostridium beijerinckii in a Two-Stage Chemostat with On-Line Solvent Removal.

Abstract: A two-stage continuous cultivation experiment with Clostridium beijerinckii NRRL B592 is described. This strain maintained its ability to produce neutral solvents (acetone, n-butanol, and ethanol) at an overall dilution rate of 0.13 h(sup-1) and achieved an average overall solvent concentration of 9.27 g/liter and an overall solvent productivity of 1.24 g/liter/h for more than 100 overall retention times. The experiment was performed without pH control on a semisynthetic medium containing yeast extract, and product inhibition was the limiting factor. Solid carrier material was present in both stages, and the solvent productivity in both stages was similar. A membrane evaporation module integrated into the recirculation loop of a second-stage bioreactor after 2,166 h increased solvent productivity and improved the yield of solvents by about 40%. The membrane reduced the concentration of solvents, which would otherwise inhibit the fermentation. Additionally, the integrated membrane evaporation dampened metabolic oscillations, which are characteristic of continuous cultivation of clostridia. It was also demonstrated that a moderate concentration buildup (approximately 30% of bioreactor inflow) caused by water flux through the membrane caused no detrimental effects to the bacterial cells. However, much higher water fluxes through the membrane, associated with a much more dramatic increase in the concentration of salts in the medium, did appear to favor cell degeneration.

Anaerobic bioprocessing of organic wastes.

Abstract: Anaerobic digestion of dissolved, suspended and solid organics has rapidly evolved in the last decades but nevertheless still faces several scientific unknowns. In this review, some fundamentals of bacterial conversions and adhesion are addressed initially. It is argued in the light of ΔG-values of reactions, and in view of the minimum energy quantum per mol, that anaerobic syntrophs must have special survival strategies in order to support their existence: redistributing the available energy between the partners, reduced end-product fermentation reactions and special cell-to-cell physiological interactions. In terms of kinetics, it appears that both reaction rates and residual substrate thresholds are strongly related to minimum ΔG-values. These new fundamental insights open perspectives for efficient design and operation of anaerobic bioprocesses. Subsequently, an overview is given of the current anaerobic biotechnology. For treating wastewaters, a novel and high performance new system has been introduced during the last decade; the upflow anaerobic sludge blanket system (UASB). This reactor concept requires anaerobic consortia to grow in a dense and eco-physiologically well-organized way. The microbial principles of such granular sludge growth are presented. Using a thermodynamic approach, the formation of different types of aggregates is explained. The application of this bioprocess in worldwide wastewater treatment is indicated. Due to the long retention times of the active biomass, the UASB is also suitable for the development of bacterial consortia capable of degrading xenobiotics. Operating granular sludge reactors at high upflow velocities (5–6 m/h) in expanded granular sludge bed (EGSB) systems enlarges the application field to very low strength wastewaters (chemical oxygen demand < 1 g/l) and psychrophilic temperatures (10°C). For the treatment of organic suspensions, there is currently a tendency to evolve from the conventional mesophilic continuously stirred tank system to the thermophilic configuration, as the latter permits higher conversion rates and easier sanitation. Integration of ultrafiltration in anaerobic slurry digestion facilitates operation at higher volumetric loading rates and at shorter residence times. With respect to organic solids, the recent trend in society towards source separated collection of biowaste has opened a broad range of new application areas for solid state anaerobic fermentation.

Geosmin and Related Volatiles in Bioreactor-Cultured Streptomyces citreus CBS 109.60.

Abstract: Streptomyces citreus CBS 109.60 produced geosmin and a complex pattern of other volatile compounds during cultivation in a 2.5-liter laboratory bioreactor. Volatiles were isolated from disrupted cells, from the culture medium, and from the waste air of the bioreactor by adsorption on Lewatit OC 1064MD. Quantitative and qualitative analyses were carried out using capillary gas chromatography and coupled gas chromatography-mass spectroscopy. S. citreus produced 56 volatile compounds, which were mainly terpenoids but also included aliphatic ketones, alcohols, esters, pyrazines, furan(on)es, and aromatic types during the growth phase. The major components were geosmin and a germacradienol. A biosynthetic pathway for geosmin including eudesmanolides is proposed.

Membrane bioreactor: a new treatment tool

Abstract: 4 new process that combines membrane bioreactor (MBR) technology and powdered activated carbon (PAC) has been developed at industrial scale. This process denitrifies, removes natural organic matter (NOM) and pesticides, and disinfects. Denitrification is carried out by heterotrophic bacteria using ethanol as a carbon source. PAC added to the bioreactor adsorbs pesticides and a fraction of NOM. The membrane keeps the solids and high-molecular-weight compounds in the bioreactor by separating them from the treated water. Ultrafiltration removes protozoa, bacteria, and viruses, thus achieving disinfection. Chlorine is added to the ultrafiltered water to maintain quality in the distribution system.

Laccase variation during dye decolourisation in a 200 L packed-bed bioreactor

Abstract: The white-rot fungus, Pycnoporus cinnabarinus, was grown in a 200 L packed-bed bioreactor. The dye, Remazol Brilliant Blue R, was added to the reactor and was rapidly decolourised. The phenoloxidase, laccase, catalysed this process. Laccases isolated from different days in the bioreactor cycle indicated variations in charge to size characteristics. Purified laccase from different days was isoelectrically focused and showed variations in intensities and numbers of bands whilst catalytic activity was retained.

Operation strategies for psychrophilic anaerobic digestion of swine manure slurry in sequencing batch reactors

Abstract: The objective of this study was to evaluate the performance of psychrophilic anaerobic digestion in sequencing batch reactors (SBRs) under operating strategies that would optimize process performance and stability while minimizing the interference of the bioreactor operation with regular farm activities. Process performance was evaluated on (i) reduction in pollution potential; (ii) energy recovery; and (iii) odour reduction. Experiments were carried out in twelve 40-L SBRs. Experimental results indicated that psychrophilic anaerobic digestion of swine manure slurry at 20 °C in an intermittently fed SBR (i) reduced the pollution potential of swine manure slurry by removing 84 – 93% of the soluble chemical oxygen demand and 41 – 83% of total chemical oxygen demand; (ii) produced biogas at rates exceeding 0.48 L of CH4 per gram of volatile solids fed; and (iii) successfully reduced odours. Other findings were that (i) for all experimental runs, psychrophilic anaerobic digestion of swine manure slurry in SBR...

Influence of physiologically relevant parameters on biomass formation in a trickle-bed bioreactor used for waste gas cleaning

Abstract: Limitation of biomass formation in a mixed culture immobilised in a trickle-bed bioreactor without substantially affecting the biological degradation of organic compounds in waste gas streams was investigated. As carbon source, the industrially relevant volatile organic compounds ethyl acetate and toluene were used. The temporal biofilm composition was investigated by means of transmission electron microscopy of ultrathin sections cut along the film height. Physiologically relevant parameters were varied. In this context the effect of (a) the type of nitrogen source, (b) the concentration of inert salt and (c) limiting the availability of essential nutrients by intermittent trickling was studied. The effect of these parameters on both biomass formation and degradation was expressed in terms of the ratio R which was defined as the fractional inhibition of biomass formation related to the fractional decrease of degradation. Using nitrate as nitrogen source instead of ammonium, R was 0.71, which means that the fractional inhibition of biomass formation was less than the fractional inhibition of degradation. When the concentration of NaCl as inert salt was adjusted to 0.4 M, the R became 1.32, showing that the fractional inhibition of biomass formation was stronger than the fractional inhibition of degradation. Limiting the availability of nutrients by intermittent trickling, the pressure drop fell by 50% whereas the degradation efficiency decreased by 30%. In summary, intermittent trickling and addition of an inert salt were observed to be advantageous unlike the impact of the type of nitrogen source.

Apparatus and method for waste water treatment utilizing granular sludge

Abstract: A wastewater treating apparatus has first, second and third bioreactors. Each bioreactor has, in an upper position, a reaction/sprinkling portion for exhaust gas treatment. The first bioreactor has, in a lower position, a submerged portion including an aerobic upper portion and an anaerobic lower portion. The aerobic upper portion includes a membrane filter. A membrane concentrated liquid produced by the membrane filter is introduced into a mixing tank. A mixture of an alcohol, fine powdered material and membrane concentrated liquid from the mixing tank is introduced, together with a developer-containing wastewater, into the anaerobic lower portion, so that a granular sludge is formed therein. The granular sludge contains anaerobic microorganisms in a high concentration level and is therefore capable of treating the wastewater without necessity of wastewater dilution or use of chemicals.

Waste treatment and minimization system

Abstract: A method and a system for the treatment of organic hazardous wastes from plant waste and associated wastewater treatment processes, whereby the waste is either introduced directly, or continuously separated from wastewater, and routed to a bioreactor, and whereby no organic solids are generated for further offsite disposal. The system disclosed includes a bioreactor (6) containing selected bacteria, untreated sludges, and recirculated biomass, and a liquid/solid separator (8) allowing water to be utilized elsewhere in the system and returning solids to the bioreactor. The biodegradation process, initiated continuously, converts hazardous organic constituents in waste stream and wastewater sludges from plant operations to inert materials, for extensive periods of operation, without the need for solids removal, external solids treatment or disposal.

Toxic effect of coloured olive compounds on the anaerobic digestion of olive oil mill effluent in UASB-like reactors

Abstract: Anaerobic sludge digestion of olive oil mill effluent (OOME) in Upflow Anaerobic Sludge Blanket (UASB) reactors was shown to be unstable as a result of both chemical and biological parameters. The study was complicated by the fact that Chemical Oxygen Demand (COD) was removed by growth and maintenance of active biomass and by adsorption in and on the sludge. Coloured compounds caused an inhibition effect on the anaerobic digestion of the wastewater. This inhibition, shown at low COD concentrations of diluted OOME, was due to accumulation of recalcitrant coloured compounds in the sludge, inducing irreversible inhibition of bacterial growth. Partial decolourization of OOME through resin (Duolite XAD 761) treatment reduced the toxic effect.

Anaerobic dechlorination and mineralization of pentachlorophenol and 2,4,6-trichlorophenol by methanogenic pentachlorophenol-degrading granules

Abstract: Anaerobic granules developed for the treatment of pentachlorophenol (PCP) completely minearilized14C-labeled PCP to14CH4 and14CO2. Release of chloride ions from PCP was performed by live cells in the granules under anaerobic conditions. No chloride ions were released under aerobic conditions or by autoclaved cells. Addition of sulfate enhanced the initial chloride release rate and accelerated the process of mineralization of14C-labeled PCP. Addition of molybdate (10 mM) inhibited the chloride release rate and severely inhibited PCP mineralization. This suggests involvement of sulfate-reducing bacteria in PCP dechlorination and mineralization. Addition of 2-bromoethane sulfonate slightly decreased the chloride release rate and completely stopped production of14CH4 and14CO2 from [14C]PCP. 2,4,6-trichlorophenol was observed as an intermediate during PCP dechlorination. On the basis of experimental results, dechlorination of 2,4,6-trichlorophanol by the granules was conducted through 2,4-dichlorophenol, 4-chlorophenol or 2-chlorophenol to phenol at pH 7.0–7.2.

Production of alkaline protease by a new Bacillus subtilis isolate for use as a bating enzyme in leather treatment.

Abstract: Bacillus subtilis, isolated from tannery waste, produced an alkaline protease at optimal activity when grown in a casein/gelatine medium in a stirred tank fermenter at 37°C with the dissolved oxygen tension at 40% air saturation. Optimum protease activity (223 U ml-1) was at pH 8.5 and was stable for 1 h up to 45°C but at 60°C lost 80% activity. Use of the crude protease as a bating agent for producing high quality leather is indicated. Tensile strength, bursting strength, tear strength and elongation at break of prepared leather were increased with increasing amounts of protease used for bating.

A miniature bioreactor for sensing toxicity using recombinant bioluminescent Escherichia coli cells.

Abstract: A miniature bioreactor was fabricated as a contactor between biosensing cells and toxic materials. This miniature bioreactor (58 mL working volume) showed performance similar to that of a conventional bioreactor, as well as the advantages of easy installation, facile operation, and small medium requirements during long-term continuous operation. A performance evaluation measured the response to ethanol in continuous operation by using a recombinant bioluminescent Escherichia coli strain. Continuous cultures were repeatedly induced by the ethanol challenge. Steady-state cell concentrations (OD) were found to be decreased, the induced specific bioluminescence (SBL) peak value was found to be increased, and the peak response time, which is the time constant of this continuous monitoring system, was found to be decreased with increasing dilution rate. Finally, on- and off-line bioluminescence monitoring was shown to be reliable, suggesting that this system is suitable for applications such as monitoring the influent and effluent streams of waste water biotreatment plants.

Horizontal-flow anaerobic immobilized sludge (HAIS) reactor for paper industry wastewater treatment

Abstract: Immobilized cell reactors are known to permit the continuous operation without biomass washout and also for increasing the time available for cells` catalytic function in a reaction or in a series of reactions. Several cell immobilization supports have been used in different reactors for anaerobic wastewater treatment, such as: agar gel, acrylamide, porous ceramic, and polyurethane foam besides the self-immobilized biomass from UASB reactors. However, the results are not conclusive as to the advantages of these different reactors with different supports as compared to other anaerobic reactor configurations. This paper describes a new anaerobic attached growth reactor configuration, herein referred as horizontal-flow anaerobic immobilized sludge (HAIS) reactor and presents the results of its performance test treating kraft paper industry wastewater. The reactor configuration was conceived aiming to increase the ratio useful volume/total volume by lowering the volume for gas separation. The HAIS reactor conception would permit also to incorporate the reactor hydrodynamic characteristics in its design criteria if the flow pattern could be approximated as plug-flow.

Biodegradation of Organic Wastes Containing Surfactants in a Biomass Recycle Reactor

Abstract: The microbial biodegradation of simulated graywater, containing 21.5 mg of linear alkylbenzene sulfonate liter-1, was investigated with a continuous-flow bioreactor with 100% biomass recycle. Low concentrations of organic matter in the ultrafiltration eluate were achieved by hydraulic residence times as short as 1.6 h and for periods of up to 74 days at a hydraulic residence time of 6 h. Upon a shift from the chemostat to the biomass recycle mode, the increase in biomass with time approximated a linear rather than an exponential function. Biomass densities as high as 6.8 g of cell protein liter-1 were reached; this was 50-fold higher than the steady-state biomass level in chemostats fed the same medium. We assessed physiological changes in the microbial community after a switch from the chemostat to the biomass recycle mode. Over 150 h, there was a two- to fourfold decrease in the respiratory potential of the microbes. After this decrease, respiratory potentials were relatively constant up to 74 days of operation. A decline in reactivity was also indicated by increasing lag periods before growth in response to organic nutrient inputs and by a decrease in the proportion of cells able to reduce tetrazolium dye. However, the bioreactor system was still capable of rapidly metabolizing inputs of organic matter, because of the very high biomass concentrations. It appears that < 10% of the organic carbon inputs accumulate as biomass.

Recycling crop residues for use in recirculating hydroponic crop production.

Abstract: As part of bioregenerative life support feasibility testing by NASA, crop residues are being used to resupply elemental nutrients to recirculating hydroponic crop production systems. Methods for recovering nutrients from crop residues have evolved from water soaking (leaching) to rapid aerobic bioreactor processing. Leaching residues recovered the majority of elements but it also recovered significant amounts of soluble organics. The high organic content of leachates was detrimental to plant growth. Aerobic bioreactor processing reduced the organic content ten-fold, which reduced or eliminated phytotoxic effects. Wheat and potato production studies were successful using effluents from reactors having with 8- to 1-day retention times. Aerobic bioreactor effluents supplied at least half of the crops elemental mass needs in these studies. Descriptions of leachate and effluent mineral content, biomass productivity, microbial activity, and nutrient budgets for potato and wheat are presented.