Research On The Production And Application Of Microbial Flocculants By Mixed Bacteria

Microbial flocculant is a kind of flocculant secreted by microorganism. These kinds of microbial polymers are expected to be useful in flocculating wastewater due to their bio-degradaility and the harmlessness of the products of their degradation toward the human and environment. Researchers are focused on the flocculant of single microbe and the cost of the microbial flocculant is too high to be used in the industry .In this paper the microbial flocculant YF-3 of high flocculating activity was manufactured by three bacteria of high flocculation activity. The culture conditions and activity of the flocculant YF-3 were studied, the ratio of flocculation was high when beer producing wastewater was used as the medium, only the nitrogen resource was added .It has been succeeded in the laboratory and given a way to use in the industry. YF-3 can be used to treat the various wastewater well.In this study, Xanthomonas WB-2, Xanthomonas WA-2 and Acinetobacter M-3 as high-yied strains were screened out . The best medium of nitrogen and carbon for Xanthomonas WB-2 grouth were beef grease, glucose and sucrose separately. The optimum pH of medium was 7~8. The optimum growing and flocculation-producing temperature was 28-32.The time of best performance was after cultivating 60~72h. The optimum pH of the environment was 4~6.The experiment showed that the best medium of nitrogen and carbonfor flocculant YF-3 were peptone, glucose and sucrose separately. The suitable pH value for flocculant YF-3 was wide, and the optimum was pH 4~6.The experiment indicated that beer producing wastewater could be used as the medium . The best diluted concentration of wastewater was 30-70 %. The high ratio of flocculation was 94.2% when 50% of diluted concentration of the wastewater was used. The high cation can enhance the flocculating activity of YF-3 specially Ca2+ .Analytical experiment approved that the major constitute of YF-3 was polysaccharide. There were -COOH and -OH in the molecules. It had larger molecular weight, and its structure was liner. The mechanism of flocculating was mainly absorbing and bridging.The wastewater purification experiment demonstrated that the YF-3 had good purifying effect in the treatment of wastewater, especially in beer producing wastewater. Inorganic flocculant or CaC should be used together in treatment of beer producing wastewater .