Optimum Conditions And Ingredient Analysis Of Compound Bioflocculant And Study On The Cyanobacterial Bloom

Microbial flocculants which agglomerate suspended solids, cell debris, colloid particles are the secondary metabolite excreted by microorganisms during growing periods. With the characteristics of biodegradation, nontoxicity, high efficiency and non-secondary pollution, the research and exploration of microbial flocculants has been a hot topic in recent years.First of all, four kinds of flocculating microbes with good flocculating ability, named X-1, X-2, X-3 and X-4, were obtained by repetitious enrichment and reselection from the activated sludge. After four strains of bacteria were combined with each other, it was found that flocculating efficiency of multiple microorganisms with X-1 and X-2 was up to 65.5%. After optimizing culture, it was found that the optimum culture conditions were as follows: the temperature was 35℃, the rotation rate was 160r/min, the intial pH of medium was 8.0, the amount of bacteria was 15ml/L, the amount of seed solution was 10ml/L, the amount of 10% CaCl2 was 40ml/L, the intial pH of Kaolin suspension was 4.5, the time of standing was 12min. Under these optimum culture conditions, the Flocculation rate was up to 92.5%.It was found that the bacteria X-1 was identified as Serratia and the bacteria X-2 was identified as Bacillus by sequencing of 16S rDNA.The flocculant XL1 was purified and the productivity of the purified is 0.9268g per liter fermented liquid.. Thermal stability test showed that the microbial flocculant is heat-resistant well.The components of bio-flocculants were detected through qualitative analysis and quantitive analysis.The results showed that the major components wereProtein,α-amino acids, aromatic amino acids, polysaccharides and hexose.And the rate of polysaccharide was 61.05%,the rate of protein was 2.28%,also there were amino sugar 0.41%and glucuronide 1.36%.Acting composite flocculant XL1 on cyanobacteria water samples which is in logarithmic phase. And the flocculation rate of the flocculant produced by complex bacterium XL1 on cyanobacteria up to 92% after 24h. The results showed that it is possible to use the compound microbial flocculant produced by complex bacterium XL1 to flocculate cyanobacteria, control algal blooms and mitigate the degree of water eutrophication.