Screening Of Complex Flocculant-producing Strain And Its Cultural Conditions

For a long time, the flocculants used in water and wastewater treatment mainly include iron salt , aluminum salt and polyacrylamide flocculant. The related research suggests that taking superfluous aluminum ion from drinking water would increase the proportion of suffering from senile dementia. The iron salt would corrode the mental and color the water. High concentration of iron would lead to negative impact on human and the zoology. Synthetic high-polymer flocculant has a little toxicity. For example, the monomer of the polyacrylamide has nerval toxicity and lead to macrocephaly, cancer and mutation, thus limit their application. In contrast, microbial flocculants that have flocculanting activity are generally biodegraded readily and are harmless to the environment and humans. Thus, biof locculants are attracting wide interest and urgently called for. But the domestic research works focus in conventional screening of flocculating kaolin suspension. Many questions must be more studied on mechanisms of flocculation, culture conditions of bio-flocculants production, gene control on producing of flocculant producing strains, characterization and application of bio-flocculants. Because of high cost of culture medium, it is hard to realize industrialization of microbial flocculants production. Therefore, a research has been conducted on complex microbial flocculants in order to decrease microbialflocculants cost and increase the ability of strains to adapt easily.The study of screening and mixing of flocculant-producing strains and optimization of its cultural conditions have been done. The mixed strains were cultured in starch wastewater, and transformation of reducing sugar by them in the process and the influence of wastewater quantity on the flocculant activity were investigated. Meanwhile, influence factors of the medium initial pH> agitation rate> relatively inoculums adscititious carbon sources on synthesize bio-flocculant were investigated. The study of disposed efficiency on wine distillery wastewater, paper making wastewater, starch wastewater, activated sludge was done.Strains which was isolated from activated sludge were mixed with each other, and the mixed strains of 9+2K J1+J4 were screened. By means of orthogonal test, the optimum culture conditions were found. The results showed that the optimum culture conditions of complex flocculant producing strains were the medium initial pH 5. 0, agitation rate lOOr/min, relatively inoculum 2. 5%, adscititious carbon sources 4% and the medium initial pH 5.0, agitation rate lOOr/min, relatively inoculum 10%, adscititious carbon sources 2%, the fractional flocculational were 77. 9% and 78. 3%, relatively. The biof locculant produced by mixing strains using starch wastewater showed reduce values of turbidity and COD to starch wastewater, paper making wastewater, wine distillery wastewater, and activated sludge.The data indicated that starch wastewater can be used to culture flocculant producing strains, and reduce the production cost. The study results are very weightily basic data for producing bio-flocculant in organic wasterwater, and build a foundation for application and further study of this method.