Bioreactor

About: Bioreactor is a research topic. Over the lifetime, 9980 publications have been published within this topic receiving 192690 citations. The topic is also known as: bioreactors.

Quantitative analysis of a high-rate hydrogen-producing microbial community in anaerobic agitated granular sludge bed bioreactors using glucose as substrate

Abstract: Fermentative H(2) production microbial structure in an agitated granular sludge bed bioreactor was analyzed using fluorescence in situ hybridization (FISH) and polymerase chain reaction-denatured gradient gel electrophoresis (PCR-DGGE). This hydrogen-producing system was operated at four different hydraulic retention times (HRTs) of 4, 2, 1, and 0.5 h and with an influent glucose concentration of 20 g chemical oxygen demand/l. According to the PCR-DGGE analysis, bacterial community structures were mainly composed of Clostridium sp. (possibly Clostridium pasteurianum), Klebsiella oxytoca, and Streptococcus sp. Significant increase of Clostridium/total cell ratio (68%) was observed when the reactor was operated under higher influent flow rate. The existence of Streptococcus sp. in the reactor became more important when operated under a short HRT as indicated by the ratio of Streptococcus probe-positive cells to Clostridium probe-positive cells changing from 21% (HRT 4 h) to 38% (HRT 0.5 h). FISH images suggested that Streptococcus cells probably acted as seeds for self-flocculated granule formation. Furthermore, combining the inspections with hydrogen production under different HRTs and their corresponding FISH analysis indicated that K. oxytoca did not directly contribute to H(2) production but possibly played a role in consuming O(2) to create an anaerobic environment for the hydrogen-producing Clostridium.

Bioaugmenting bioreactors for the continuous removal of 3-chloroaniline by a slow release approach.

Abstract: The survival and activity of microbial degradative inoculants in bioreactors is critical to obtain successful biodegradation of non- or slowly degradable pollutants. Achieving this in industrial wastewater reactors is technically challenging. We evaluated a strategy to obtain complete and stable bioaugmentation of activated sludge, which is used to treat a 3-chloroaniline (3-CA) contaminated wastewater in a lab-scale semi-continuous activated sludge system. A 3-CA metabolizing bacterium, Comamonas testosteroni strain I2, was mixed with molten agar and encapsulated in 4 mm diameter open-ended silicone tubes of 3 cm long. The tubes containing the immobilized bacteria represented about 1% of the volume of the mixed liquor. The bioaugmentation activity of a reactor containing the immobilized cells was compared with a reactor with suspended I2gfp cells. From day 25-30 after inoculation, the reactor with only suspended cells failed to completely degrade 3-CA because of a decrease in metabolic activity. In the reactors with immobilized cells, however, 3-CA continued to be removed. A mass balance indicated that ca. 10% of the degradation activity was due to the immobilized cells. Slow release of the growing embedded cells from the agar into the activated sludge medium, resulting in a higher number of active 3-CA-degrading I2 cells, was responsible for ca. 90% of the degradation. Our results demonstrate that this simple immobilization procedure was effective to maintain a 3-CA-degrading population within the activated sludge community.

Design of bioreactors for coal synthesis gas fermentations.

Abstract: Anaerobic bacteria may be utilized in the conversion of CO, CO 2 and H 2 in synthesis gas to products such as methane, acetate, ethanol and butanol. Bioreactors for these fermentations are mass transfer limited due to very low gas solubilities. Several reactor designs have been examined for these conversions including batch, continuous stirred tank and bubble column reactors. This paper presents laboratory results for these reactor systems using the strict anaerobe Peptostreptococcus productus as a model organism. Results comparing the performance of these reactors and showing the effects of increased mass transfer and total pressure on system performance are presented are discussed.