Microporous Membrane Bioreactor Research Articles

Experimental observations on the effect of added dispersing agent on phenol biodegradation in a microporous membrane bioreactor

The effect of added dispersing agent tetrasodium pyrophosphate (TSP) on the degradation of phenol by Pseudomonas putida BCRC 14365 in a microporous membrane bioreactor was experimentally studied at 30 °C and pH 7. The hollow fibers were pre-wetted with ethanol to make them more hydrophilic. Phenol solution was passed through the lumen of the module and the cell medium was flowed across the shell. All Experiments were carried out at a fixed initial cell density of 0.023 g/L (0.06 optical density). Phenol could be completely degraded with the help of the biofilm formed on the outer surfaces of the fibers even though its level was high up to 3 g/L. It was also shown that the presence of TSP in cell medium could improve biodegradation. The amount of added TSP was optimized to be 1 g/L under the conditions studied. In this situation, 3 g/L of phenol could be completely removed within 76 h, much shorter than the absence of TSP (within 92 h).

Performance and filtration characteristics of non-woven membranes used in a submerged membrane bioreactor for synthetic wastewater treatment

Experimental studies were conducted to investigate the performance and filtration characteristics of a submerged non-woven membrane bioreactor system. The results showed that an activated sludge system with a submerged tubular non-woven membrane module could be operated until the mixed liquor suspended solid (MLSS) reached about 11,000 mg/L. In studying the filtration characteristics of our submerged non-woven membrane bioreactor system, the factors under investigating included pore size, initial flux, aeration intensity and MLSS effect. It was found that suspended floc particles of activated sludge were the main contributor for membrane fouling. The filtration behaviors of the submerged non-woven membrane bioreactor system were different from those of conventional microporous membrane bioreactor systems, especially operating at high aeration intensity and high MLSS concentration.

Hydrogenotrophic denitrification in a microporous membrane bioreactor

Hydrogenotrophic denitrification of nitrate contaminated groundwater in a bench-scale microporous membrane bioreactor has been investigated. To prevent microbial contamination of the effluent from the reactor the nitrate-laden water treated was separated from the denitrifying culture with a 0.02 μm pore diameter membrane. Equal pressure was maintained across the membrane and nitrate was removed by molecular diffusion through the membrane and into the denitrifying culture. The system was operated with a hydrogenotrophic denitrification culture to circumvent the addition of an organic substrate to the water. Removal efficiencies ranging from 96% to 92% were achieved at influent concentrations ranging from 20 to 40 mg/L NO 3 −-N. The flux values achieved in this study were 2.7–5.3 g NO 3 −-N m −2 d −1. The microporous membrane served as an effective barrier for preventing microbial contamination of the product water as evidenced by the effluent heterotrophic plate count of 9 (±3.5) CFU/mL. The hydrogenotrophic culture was analyzed using available 16S and 23S rRNA-targeted oligonucleotide probes. It was determined that the enrichment process selected for organisms belonging to the beta subclass of Proteobacteria. Further analysis of the hydrogenotrophic culture indicated that the organisms may belong to the β-3 subgroup of Proteobacteria and have yet to be identified as hydrogenotrophic denitrifiers.

Sterile glucose solution prepared by a microporous membrane bioreactor for continuous culture

Glucose solution produced in a new bioreactor with cross-flow filtration by a microporous membrane was used for continuous fermentation using Pseudomonas aeruginosa KYU-1. The membrane filtered out enzyme immobilized on corn stover for recycling. No contaminants were observed in the glucose solution by enrichment culture of the sample solution and no foreign microorganisms were detected throughout the culture.

Some Characteristics of Continuous Glycerolysis of Fat by Lipase with Microporous Membrane Bioreactor

Various characteristics of the continuous glycerolysis of corn oil by pure Pseudomonas fluorescens lipase in a microporous hydrophobic flat membrane bioreactor were studied. By on-line continuous measurement of electric conductivity with a flow cell type electrode, the moisture content of the microaqueous glycerol containing the enzyme was monitored. The effect of moisturec ontent in the microaqueous glycerol on the glycerolysis reactions with the pure enzyme differed slightly from that with a crude enzyme as reported previously. The critical moisture content above which free fatty acids were formed was 3%, this being 1% less than that for the crude enzyme. The microporous hydrophobic flat membrane made of poly (tetrafluoroethylene) (PTFE) gave somewhat better conversions of the outlet product than did the polypropylene membrane at the same flow rates of the oil. Calcium chloride dissolved in the glycerol-water-lipase solution stabilized significantly the enzyme under non-reactive conditions without oil phase but destabilized it slightly during continuous reactions with oil.

Continuous Synthesis of Glycerides by Lipase in a Microporous Membrane Bioreactor

Continuous Synthesis of Glycerides by Lipase in a Microporous Membrane Bioreactor

Continuous synthesis of glycerides by lipase in a microporous membrane bioreactor

AbstractA membrane bioreactor was developed for continuous synthesis of glycerides by lipase to overcome the drawbacks associated with the usual operation in an emulsion system. One unit (total area: 726 cm2) of flat, plate‐type dialyzer was used as the membrane bioreactor at 40 C. The glycerol solution, containing bacterial lipase and water, was supplied continuously to 1 side of a sheet of microporous polypropylene membrane (strongly hydrophobic) and the effluent was recycled, while undiluted liquid fatty acid (oleic or linoleic) was fed continuously to the opposite side of the membrane and came in contact with a glycerol‐water‐lipase solution to cause the reaction. The product, glycerides, was obtained at the outlet, in a pure state, with no other phase. Highest conversion (ca. 90%) was obtained when the water content of the glycerol solution was 3–4%. As the accumulation of water produced by the reaction lowered the conversion, molecular sieves in a column that the glycerol solution passed through were used for optimal water content. The reaction could be continued at least for 1 month, yielding a conversion above 70% when 1% CaCl2 was added in the glycerol solution. The main component of glycerides formed was almost equimolar amounts of mono‐and diglycerides.