Screening Of A Microbial Flocculant Producing Bacteria And The Research Of Its Synthesis Condition

Microbial Flocculant is a biological macromolecules that has flocculation activity and secreted by microorganism, with the adventage of efficient, non-toxic, no secondary pollution, etc., Microbial Flocculant is an extensive range of applications of environmentally friendly water treatment agent. Microbial Flocculant has great application value in water treatment, sewage water treatment, post-processing, food fermentation. The chemical composition of microbial flocculant mainly includes proteins, polysaccharides, DNA and other macromolecules. High osmotic pressure, high concentrations of heavy metals, extreme pH, high or low temperatures and other environmental factors may effect its flocculation activity by altering the conformation of bioflocculant. In order to improve the rate of microbial flocculation in these environmental conditions, Studies have reported to improve flocculation activity by increasing use of the amount invested, and adding metal ions. In addition, multi-strain mixed microbial fermentation method for preparing a composite flocculant. It has theoretical and practical significance to protect bioflocculant in extreme environments stable and maintain its activity.This paper identified that the flocculating activity of synthetic strain H09 is high in Kaolin system. It was proved that H09 is the Ectoine secretory strain by Liquid Chromatographic Analysis. Compared with identification based on 16S rDNA and Blast, H09 is confirmed as Moderately Halophilic which named Halomonas sp. H09. The composition identify of Halomonas sp. H09 by Infrared Spectrophotometry proved that the main Extraction of the bioflocculant is polysaccharide. Based on the results of flocculation activity distribution, this microbial flocculant was identified as extracellular polysaccharide flocculant. The experimental results indicate that:The optimum C and N source, Glucose and (NH4)2SO4 are benefit to the Syntheses of Polysaccharide. The optimition of Glucose Concentration is 60 g/L and the concentration of (NH4)2SO4 is 15 g/L, the optimum concentration of NaCl is 30 g/L,and the optimum fermentation conditions of polysaccharide is pH 7.0; Under the optimized conditions, Halomonas sp. H09 resultant of polysaccharide was 3709.4 mg/L. The experiment discusses the best flocculating system for the Polysaccharide and examined affecting factors on bioflocculation. In the system of Kaolin clay suspension of sea water, The optimum level of polysaccharide is 0.015%, and the optimum temperature is 30℃.The maximum value is 79.3% in 5 mins. Using Halomonas sp. H09 in the treatment of Desulfurization Wastewater and the flocculation rate can reach 90.5%.