Research On Effects Of Microbial Flocculant On The Growth Of Chlorella Pyrenoidosa

Flocculation as an effective pretreatment method has been widely used in water treatment. The traditional organic and inorganic flocculants have a highly-efficient flocculation effect and the low costs and other excellent features, but for their strong nerve toxicity and carcinogenicity, and other shortcomings on the environment and human health, and the negative effects becoming more and more obvious, the application are restricted more andmore. To solve the environmental problems, a new generation of highly efficient microbial flocculant (Microbial Flocculant, MBF) come into the people's attention. Although the bioflocculant biodegradable, non-toxic harmless and no secondary pollution, and other properties have been affirmed in theory, but there is no experimental data related to the theoretical support, so actual research on the water ecological safety and environment-friendly of bioflocculant is of great significance.This paper deals with the studies on environmental toxicological characteristics of MBFA9,MBFBS-5 and MBFC3 three highly efficient microbial flocculant by Chlorella pyrenoidosa with the indicator of the biomass, chlorophyll content (Chl-a, Chl-b), soluble protein content and antioxidant enzyme specific activity (SOD specific activity, POD specific activity). The results showed that:low concentrations of all the three highly efficient microbial flocculant can inhibit the growth of Chlorella pyrenoidosa at the very start, but the inhibiting effects weaken with time and disappear eventually; high concentrations of microbial flocculant can minor promote the growth of Chlorella pyrenoidosa eventually. Meanwhile, the activities of superoxide dismutase (SOD) and peroxidase (POD) keep stable. The antioxidase system and the nonenzyme-resistance system are not started, and the algal cells are not injured.Referencing ISO10707-1994 Water quality-Evaluation in an aqueous medium of the "ultimate" aerobic biodegradability of organic compounds-Method by analysis of biochemical oxygen demand (closed bottle test), design a solution for sludge removal CODcr indicators for the evaluation of the bioflocculant biodegradablity. The results show that:the degradation rate of MBFA9, MBFBS-5 and MBFC3 three bioflocculant can reach more than 95 percent in three days, and there has been no degradation process lag, and the first-period degradation start at the first day, and the degradation rates are very rapidly and completely degradated within 10 days.So the biodegradability of MBFA9,MBFBS-5 and MBFC3 three highly efficient microbial flocculant is good.Through the effects of MBFA9,MBFBS-5 and MBFC3 three highly efficient microbial flocculant on the growth of green algae Chlorella pyrenoidosa and the bioflocculant biodegradablity evaluating experiments, it is primarily testified that MBFA9,MBFBS-5 and MBFC3 three highly efficient microbial flocculant are safe, non-toxic, eco-friendly microbial fermentation products.