Screening And Identifying Of A Kind Of Flocculant-producing Bacillus And Studying On Its Flocculation Properties

Microbial flocculant (MBF) is a kind of metabolites produced by microbes or theirsecretions, which is the efficient, nontoxic and no secondary pollution water treatment agent,got through bacteria, fungi and other microbes for fermentation, extraction, refining usingmicrobial technology. Due to microbial flocculant can overcome inorganic polymer andsynthetic organic polymer flocculant’s inherent defects, and finally realize no pollutionemission, so microbial flocculants research is becoming a important topic in today’s world.This article through to collect the sludge samples, using the microbial technology such asseparation and purification, isolate five single colony strain from samples; and screen abacterial strain, which is smooth, moist,sticky, filamentous when lifting and have efficientflocculation activity.Through analysis of phenotypic characteristics, physiological and biochemicalcharacteristics, molecular biology, system development and clustering, and the clusteringanalysis, this bacteria is in same branch with Bacillus mucilaginous C4585in thephylogenetic tree, which sequence similarity is as high as99%. With the above experimentalresults, the finally confirm that this bacteria is one strain of Bacteria, classificated asB.mucilaginous.Considering to get high productive flocculant, we optimize the fermentation culturemedium with single factor and response surface methods, in order to improve the GM1flocculating rate. Based on the quadratic multinomial linear regression equation and theresponse surface analysis, it shows that the best fermentation culture medium formula is:sucrose0.57%, ammonium sulfate0.022%, pH value7.42. Under this condition, theflocculating rate increased by6.0%than before, and it has important theoretical guidancesignificance in industrial waste water and domestic water treatment.Through the flocculating substance extracting and its composition analyzing, it is foundthat the flocculating substance are mainly distributed in the fermented liquid. Using alcoholsinking method, we can get white fibrous solid after lyophilization. The material is easilyabsorb moisture in the air, soluble in water, insoluble in ethanol and acetone and any other organic solvents. Through physical, chemical and other methods to analyze that the substancemainly is polysaccharide.Comprehensing the flocculating material analysis in the physical and chemical and flocculatingkaolin particles before and after electron microscopy images, the flocculation mechanism ofthe flocculating agent summed up as: When the distance between the molecules with kaolinparticles near each other, van der Waals force is main force; When add CaCl2solution, it canneutralize the negative charge, so that the electrostatic repulsion decreased; With distanceshrinking, hydrogen bond is the main adsorption force, and some particles with differentflocculant molecular intertwine and fall down, that to get the best effective result.Using4g/L of kaolin suspension imitate the actual wastewater, it shows that thisflocculant is more easy to soluble in high temperature water; The optimum pH of the besteffective flocculation is2, peralkaline can inhibit flocculation effect; The optimum addingamount offlocculant was3.0mg/L; The optimal adding amount of coagulant aid CaCl2is0.4g/L. So this flocculant can be applied to the high temperature industrial wastewater treatmentand acid industrial wastewater treatment and so on.