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PubMed2004

[Printing and dyeing wastewater treatment using combined process of anaerobic bioreactor and MBR].

This paper describes a labor-scale experiment for printing and dyeing wastewater treatment of woolen mill using a combined process of an anaerobic reactor and a membrane bioreactor (MBR). The experimental results showed that when the concentration of COD, BOD5 and color in the influent were 128-321 mg/L, 36-95 mg/L and 40-70 dilution times (DT), the average concentrations of COD, BOD5, color and turbidity in the effluent were 36.9 mg/L, 3.7 mg/L, 21 DT and 0.24 NTU, respectively, and the corresponding removal rates were 80.3%, 95%, 59% and 99.3%, respectively. A new integrated membrane bioreactor by gravity drain of liquid level in the bioreactor was developed in this study. It not only lessens suction pump for effluent and controlling unit comparing to the traditional integrated membrane bioreactor, but also has the characters of high and continuous flux, concise configuration and simple operation and maintenance. According to the experimental results, the air flow rate through the membrane module is a significant factor to affect the flux rate and cake layer deposited on the membrane. With application of optimal air flow rate, it is effective to reduce membrane fouling and maintain high flux rate.

Bacteria, Aerobic↗

PubMedDate not supplied

Aquatic ecosystem as a bioreactor: water purification and some other functions.

A fundamental concept is proposed of aquatic ecosystem as a bioreactor that carries out the function of water purification in natural water bodies and streams. The ecosystem as a bioreactor has the following characteristic attributes: (1) it is a large-scale (large-volume) bioreactor; (2) it is a diversified (in terms of the number of taxa and the scope of functional activities) bioreactor; (3) it possesses a broad range of biocatalytic (chemical-transforming and degrading) capabilities. New experimental data on xenobiotics-induced inhibition of the functioning of the molluscs Unio tu- midus, U. pictorum, M. galloprovincialis and Limnaea stagnalis emphasize the potential ecological hazard from sublethal concentrations of pollutants (including those exemplified by synthetic surfactants and detergents).

Animals↗

PubMed2004

Development of nitrogen-removal bioreactor using poly(lactic acid) as an energy source.

To control nitrogen such as ammonia in a rearing water of aquatic animals, we developed new bioreactor capable of both nitrification and denitrification. It was consisted of gel-plate immobilized microorganisms and a biodegradable plastic plate composed of three kind of poly(lactic acid) as an energy source of denitrification. When batch treatment experiment by the bioreactor was continuously carried out with an artificial rearing water containing ammonia, nitrogen-removal rate of the bioreactor was approximately 3 g-N/d/m2-gel surface and the activity was maintained for over 3 month without additional energy source. Therefore, the bioreactor would be effective to control nitrogen concentration in rearing water of a closed water circulating system for aquatic animals.

Ammonia↗

PubMed2005

Enhancement of oxygen transfer and nitrogen removal in a membrane separation bioreactor for domestic wastewater treatment.

Biological nitrogen removal in a membrane separation bioreactor developed for on-site domestic wastewater treatment was investigated. The bioreactor employed hollow fiber membrane modules for solid-liquid separation so that the biomass could be completely retained within the system. Intermittent aeration was supplied with 90 minutes on and off cycle to achieve nitrification and denitrification reaction for nitrogen removal. High COD and nitrogen removal of more than 90% were achieved under a moderate temperature of 25 degrees C. As the temperature was stepwise decreased from 25 to 5 degrees C, COD removal in the system could be constantly maintained while nitrogen removal was deteriorated. Nevertheless, increasing aeration supply could enhance nitrification at low temperature with benefit from complete retention of nitrifying bacteria within the system by membrane separation. At low operating temperature range of 5 degrees C, nitrogen removal could be recovered to more than 85%. A mathematical model considering diffusion resistance of limiting substrate into the bio-particle is applied to describe nitrogen removal in a membrane separation bioreactor. The simulation suggested that limitation of the oxygen supply was the major cause of inhibition of nitrification during temperature decrease. Nevertheless, increasing aeration could promote oxygen diffusion into the bio-particle. Sufficient oxygen was supplied to the nitrifying bacteria and the nitrification could proceed. In the membrane separation bioreactor, biomass concentration under low temperature operation was allowed to increase by 2-3 times of that of moderate temperature to compensate for the loss of bacterial activities so that the temperature effect was masked.

Biomass↗

PubMed2005

[Study on energy dissipation in modified airlift bioreactor].

The effects of operational variables and reactor configurations (e.g. diameter of draft tube and the number of static mixers) on energy loss in modified airlift bioreactor were investigated at the first time. The results showed that improving the structure of draft tube could reduce energy loss in the bioreactor. When the diameter of draft tube and the number of static mixers were 4.0cm and 39, respectively, the total energy loss in the modified bioreactor was the least among all the configurations and 23.6% less than that of the conventional counterpart at the same air flowrate. The energy consumption for aeration was the smallest (43.9% less than that of the conventional counterpart) when the diameter of draft tube and the number of static mixers were 5.5cm and 13, respectively. The highest energy dissipation (70% - 80%) occurred in the riser, the bottom zone (about 20%) took the second place and the separator (less than 10%) took the third place. The energy dissipation in the downcomer was neglectable under the conditions in the research. When the energy loss per unit volume was considered, bottom zone stood the first place. It was implied that the riser was the most important zone to cut down the energy loss of the bioreactor and some attention should also be paid to the bottom zone.

Bioreactors↗

PubMed2006

[Acceleration the stabilization of waste in bioreactor landfill by sequential anaerobic and semi-aerobic operation].

Based on the comparison between anaerobic, aerobic and semi-aerobic bioreactor landfill, the method to acceleration the stabilization process of waste in bioreactor landfill by sequential anaerobic and semi-aerobic operation mode was brought forward and put into practice in simulated experiment. When the operation mode was changed from anaerobic mode to semi-aerobic mode in the 710th day, the COD concentration of simulated bioreactor landfill column D1 (leachate recirculation once everyday) and D4 (leachate recirculation twice every week) was dropped from 705mg/L, 669mg/L to 135mg/L, 178 mg/L and the ammonia-N concentration was dropped from 650 mg/L, 877mg/L to undetectable level after 360 days. At the same time, the COD concentration of control column D2 and D3 was dropped from 435mg/L, 852mg/L to 295mg/L, 596mg/L and the ammonia-N concentration was dropped from 654 mg/L, 1107 mg/L to 469mg/L, 783mg/L. The rate of COD and ammonia-N concentration drop in leachate was enhanced largely after the operation mode of simulated bioreactor landfill column was changed from anaerobic mode to semi-aerobic mode. It was also shown that higher leachate recirculation frequency is more favorable for this process.

Bacteria, Aerobic↗

PubMed2006

Numerical simulation of microcarrier motion in a rotating wall vessel bioreactor.

OBJECTIVE: To analyze the forces of rotational wall vessel (RWV) bioreactor on small tissue pieces or microcarrier particles and to determine the tracks of microcarrier particles in RWV bioreactor. METHODS: The motion of the microcarrier in the rotating wall vessel (RWV) bioreactor with both the inner and outer cylinders rotating was modeled by numerical simulation. RESULTS: The continuous trajectory of microcarrier particles, including the possible collision with the wall was obtained. An expression between the minimum rotational speed difference of the inner and outer cylinders and the microcarrier particle or aggregate radius could avoid collisions with either wall. The range of microcarrier radius or tissue size, which could be safely cultured in the RWV bioreactor, in terms of shear stress level, was determined. CONCLUSION: The model works well in describing the trajectory of a heavier microcarrier particle in rotating wall vessel.

Bioreactors↗

PubMed1993

Use of microgravity bioreactors for development of an in vitro rat salivary gland cell culture model.

During development, salivary gland (SG) cells both secrete factors which modulate cellular behavior and express specific hormone receptors. Whether SG cell growth is modulated by an autocrine epidermal growth factor (EGF) receptor-mediated signal transduction pathway is not clearly understood. SG tissue is the synthesis site for functionally distinct products including growth factors, digestive enzymes, and homeostasis maintaining factors. Historically, SG cells have proven difficult to grow and may be only maintained as limited three-dimensional ductal-type structures in collagen gels or on reconstituted basement membrane gels. A novel approach to establishing primary rat SG cultures is use of microgravity bioreactors originally designed by NASA as low-shear culture systems for predicting cell growth and differentiation in the microgravity environment of space. These completely fluid-filled bioreactors, which are oriented horizontally and rotate, have proven advantageous for Earth-based culture of three-dimensional cell assemblies, tissue-like aggregates, and glandular structures. Use of microgravity bioreactors for establishing in vitro models to investigate steroid-mediated secretion of EGF by normal SG cells may also prove useful for the investigation of cancer and other salivary gland disorders. These microgravity bioreactors promise challenging opportunities for future applications in basic and applied cell research.

Animals↗

PubMed1994

Use of hepatocyte cultures for liver support bioreactors.

Hybrid artificial liver systems are being developed as extracorporeal temporary liver support therapy. Here, an overview is given with emphasis on hepatocyte culture models for bioreactors, in vitro studies, animal studies and the clinical application of hybrid liver support systems. In vitro studies show long term external metabolic functions of primary isolated hepatocytes in bioreactors. These systems are capable of supporting essential liver functions. Animal experiments show the possibility of upscaling the bioreactors for clinical treatment. Since there is no reliable animal model for investigations on the treatment of acute liver failure, the promising results of these studies have limited relevance. The small number of clinical studies are not sufficient to give statements about a clinical improvement of therapy of acute liver failure. Although important progress has been made in the development of the systems, multiple different hepatocyte culture models and bioreactor constructions are discussed in the literature, indicating competition in this field of medical research.

Animals↗

PubMed1993

Agitation, aeration and perfusion modules for cell culture bioreactors.

For an optimized bioreactor design which is adapted to the cultivation of sensitive animal cells different modular bioreactor components for gentle agitation, sufficient aeration and long-term perfusion were developed and investigated with respect to their suitability from laboratory to production scale. Aeration systems have been designed for both shear sensitive cells and cells which tolerate bubbles. The systems are based on either membranes for bubble-free aeration or stainless steel sparger systems. They were characterized by determination of their oxygen transfer capacity and optimized in cultivation processes of different cell lines under process conditions such as batch and perfusion mode. Different impellers for suspension cells and cells grown on carriers were investigated for their suitability to ensure homogeneous gentle mixing. A large pitch blade impeller as well as a novel 3-blade segment impeller are appropriate for homogeneous mixing at low shear rates. Especially with the 3-blade segment impeller fluid mechanical stress can be reduced at a given stirrer speed which is advantageous for the cultivation of cells attached to microcarriers or extremely shear sensitive suspension cells. However, our results indicate that shear sensitivity of animal cells has been generally overestimated. Continuous perfusion of both suspension cell cultures and cells cultivated on microcarriers could be successfully performed over extended periods of time using stainless steel spinfilters with appropriate pore sizes and systems based on microporous hydrophilic membranes. Spinfilters are suitable cell retention systems for technical scale bioreactors allowing continuous perfusion cultures of suspension cells (pore size 10 to 20 microns) as well as anchorage dependent cells grown on microcarriers (pore size 75 microns) over six weeks to 3 months. Applying the developed modules for agitation, aeration and perfusion process adapted bioreactor set-ups can be realized which ensure optimum growth and product formation conditions in order to maximize cell and product yields.

Air↗

PubMed1997

Hollow-fire bioreactors compared to batch and chemostat culture for the production of a recombinant toxoid by a marine Iibrio.

Bioreactor selection is important for maximising the productivity of recombinant organisms. In this paper a comparison is made between growth and recombinant protein synthesis in three types of bioreactor containing a marine Vibrio capable of heterologous expression and secretion of the non-toxic B-subunit pentamer of Escherichia coli heat-labile enterotoxin, EtxB. The heterologous gene was located on the plasmid pMMB68. Resistance to carbenicillin was used to select for plasmid-containing cells. In batch and continuous culture. Volumetric productivities were highest when cells were grown in the presence of carbenicillin. Without antibiotic selection, the highest volumetric productivity (9.4 mg EtxB-1 h-1) was observed in hollow-fibre bioreactors, and the production phase could be maintained for over 50 h. The highest specific productivity under these conditions was found in batch culture, but the maximal production phase was only of 5 h duration. In hollow-fibre reactors the type of fibre used significantly affected productivity, both with regards to the maintenance of reactor integrity and by allowing passage of the recombinant toxoid through the selectively permeable membrane. Where contamination of the product with carbenicillin is to be avoided, these bioreactors are superior to batch or continuous culture.

Bacterial Toxins↗

PubMed1990

Culture of human tumor infiltrating lymphocytes in hollow fiber bioreactors.

Human tumor infiltrating lymphocytes (TIL) from metastatic melanoma of six patients were grown using a new hollow fiber bioreactor system. After inoculating 0.35-10 X 10(8) TIL into the extra-fiber space (EFS), each Cellmax bioreactor was perfused with AIM-V medium, supplemented with rIL-2. The cells subsequently expanded 124-1170-fold to yield 1.5-5.4 X 10(10) TIL over a 14-32 day period. TIL were flushed from the EFS using 200 ml medium and possessed an average viability = 91%. The phenotype and the autologous tumor cell lytic capacity of these TIL were similar to those of TIL grown in the currently used gas-permeable culture bags. Tissue culture media use averaged 4.3 liters/10(10) TIL harvested. The TIL of one patient were re-expanded twice from cells remaining within the same bioreactor after harvest suggesting that one bioreactor cartridge could be used for repetitive, periodic studies. An estimated 80% decrease in technical time expended and in incubator space requirements were realized using this methodology. Cell culture on hollow fibers appears to be a useful method for producing large quantities of primary human lymphocytes for experimental, and perhaps, therapeutic needs.

Cells, Cultured↗

PubMed1992

Hepatocyte function in a hollow fiber bioreactor: a potential bioartificial liver.

We have developed a novel hepatocyte loaded hollow fiber bioreactor as a potential bioartificial liver. Freshly harvested rat hepatocytes were entrapped in a three-dimensional gel matrix within hollow fibers in a perfused bioreactor. Gel entrapment allowed cells to be cultured at high density while maintaining tissue-specific function. Hepatocyte function was evaluated in 10 bioreactors, each containing approximately 5 x 10(7) cells. Oxygen consumption averaged 0.32 pmole/cell/hr, albumin appearance averaged 0.60 pg/cell/hr, and lidocaine clearance (a measure of the P-450 activity) averaged 0.74 pg/cell/hr. Function persisted for the 7 days of the study. Electron microscopy at 7 days showed the distinctive ultrastructure of viable, differentiated hepatocytes: bile canaliculi, intercellular junctions, peroxisomes, abundant mitochondria, and glycogen granules. Maintenance of tissue specific function and ultrastructure suggests that this bioreactor configuration has potential as a device to support patients in liver failure, as well as to study hepatocytes in vitro.

Amino Acids↗

PubMed1997

Innovative bioreactors.

Recent papers have described new bioreactor designs. Most innovations addressed either oxygen transfer, shear induced by stirring, control of water activity in organic phase systems or waste biotreatment. Innovations made during the past year were reported in mainly three areas: bioreactor designs for increases in oxygen transfer and decreases in shear stress; bioreactors for two-phase reactions with water activity control; and environmental bioreactors.

Journal Article↗

PubMed2000

High-rate aerobic treatment of winery wastewater using bioreactors with free and immobilized activated sludge.

COD (chemical oxygen demand) removal rate and efficiency of winery wastewater (WW) aerobic treatments were evaluated in an air-bubble column bioreactor using self-adapted microbial populations either free or immobilized on polyurethane particles and in a packed-bed bioreactor immobilized on Raschig rings. The bioreactors were fed continuously for up to 12 months using WW of different origins and with different pollution loads (COD range, 0.8-11.0 kg.m(-3)): the maximum loading rate was approx. 8.8 kg-COD m(-3).d(-1). The highest COD removal rate (6.6 kg.m(-3).d(-1)) was obtained with free activated sludge in the bubble column bioreactor; treatment efficiency and hydraulic retention time were >90% and approx. 0.8 d, respectively. The microbial populations in the three reactors were characterized.

Journal Article↗

PubMed2003

Optimization and scale-up of L-lactic acid fermentation by mutant strain Rhizopus sp. MK-96-1196 in airlift bioreactors.

We determined the optimum culture conditions such as inoculum size, initial starch concentration, pH during the fermentation and aeration rate for L-lactic acid production by Rhizopus sp. MK-96-1196 in a 3-l airlift bioreactor. More than 90 g/l of L-lactic acid was produced from only partially enzymatically hydrolyzed corn starch with a production rate of 2.6 g/l/h and a product yield of 87% based on the starch consumed under the optimum conditions in the 3-l airlift bioreactor. Scale-up from the 3-l to a 100-l airlift bioreactor for L-lactic acid fermentation was carried out using V(s)(cm/s) as a scale-up criterion. The production rates and yields of L-lactic acid in both bioreactors appeared to be fairly well correlated with k(L)a (1/h).

Journal Article↗

PubMedDate not supplied

Enhancing oxygen transfer in surface-aerated bioreactors by stable foams.

To enhance oxygen transfer in surface-aeration bioreactors, stabilized foams were generated to increase the gas-liquid interfacial area by slowly introducing coarse bubbles into media containing fetal bovine serum. The bubble sparging rates were so low (i.e., 20 and 50 mL/h) that the contribution to oxygen transfer from these bubbles was due to foaming instead of bubbling. Furthermore, no physical cell damage caused by bubble sparging was observed. Oxygen transfer coefficients, kLa, in the bioreactors were measured in cell-free media. Without the foam-stabilizing agent (i.e., serum), no appreciable change in kLa was observed due to the bubble sparging. On the other hand, with serum, kLa increased with increasing serum content and bubble sparging rate and corresponded well with the degree of foaming. With 10% fetal bovine serum and a bubble sparging rate of 50 mL/h, kLa increased approximately 90% compared with no foaming. The enhancing effect of foam on oxygen transfer in surface aeration bioreactors has been further demonstrated with hybridoma cultures simultaneously grown in three identical bioreactors with and without stabilized foams.

Aerobiosis↗

PubMedDate not supplied

Production of human alkaline phosphatase, a secreted, glycosylated protein, from a baculovirus expression system and the attachment-dependent cell line Trichoplusia ni BTI-Tn 5B1-4 using a split-flow, air-lift bioreactor.

A split-flow, air-lift bioreactor for the cultivation of insect cells to produce recombinant protein is described. It can be used advantageously with attached cell systems. This bioreactor incorporates two sections: a rise and a downcomer. Trichoplusia ni BTI-Tn 5B1-4 cells are grown on a support material of glass beads or microcarriers placed in the downcomer. This cell line is more productive than other commonly used insect cell lines, but it has the disadvantage of being difficult to use at large volumes since it is not easily adaptable to suspension culture. Adequate oxygen demand is supplied by sparging without direct exposure of cells to air bubbles. Nutrients are supplied convectively to the attached cells on support material as the fluid flows through the downcomer. The split-flow, air-lift bioreactor appears to be suitable for insect cell culture and is potentially scalable. It can provide a high surface-to-volume ratio and can be operated in batch or continuous mode. A lab-scale prototype bioreactor has been constructed and tested for the production of a secreted, glycosylated recombinant protein (human alkaline phosphatase) or seAP using an Autographa californica multiple nuclear polyhedrosis virus (AcMNPV) vector. With a ratio of riser cross-sectional area to downcomer cross-sectional area of 1, an aspect ratio of 4.4, an air-flow rate of 54 mL/min in the riser, and a bed of 2400 3-min nonporous glass beads, 10.7 micrograms/mL of seAP was produced using an MOI (multiplicity of infection or the ratio of plaque-forming units to cells) of 10.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗