Studies On The Biological Characteristics And Flocculating Effects Of Bioflocculant-Producing Microorganism In Qinghai Province

Bioflocculants are the metabolic products of the microorganism, which are safe, non-toxic, easily cultivated, and can be biodegraded. Its main components are amylose, glycoprotein, nucleic acid, protein etc.This research screened 17 strains of bioflocculant-producing microorganisms from activated sludge and sewage by conventional methods, which collected from wastewater treatment pond of Qinghai Jingzhu Tibetan Medicine Ltd., Qinghai Glutin Ltd., Lanzhou Huanghe Brewage Ltd and so on. 3 strains of them with high flocculating activity were obtained afer rescreening. They were named JN-1, JN-2 and JN-15.By studying the biological characteristics of bioflocculant-producing microorganisms, it was shown that they were all G⁺ and belong to bacillus sp. The colonial morphology of JN-1 and JN-2 was white,small,opacity,and erose on the edge.JN-1 and JN-2 didn't produce sulfureted hydrogen and indole, didn't hydrolyze starch, could liquefy gelatin and utilize citric acid salt;the result of V-P experiment was positive ,but methyl red experiment was negative. Both strains could produce acid by utilizing sucrose, glucose,xylose,fructose and manna sugar. They were identified as (Bacillus pumilus Meyer & Gottheil in Gottheil 1901,681.). The colonial of JN-15 was big, smooth, transparence, viscous, and regular on the edge. It didn't produce sulfureted hydrogen and indole, could hydrolyze starch and liquefy gelatin, couldn't utilize citric acid salt;the result of V-P experiment was positive ,but methyl red experiment was negative.JN-15 could produce acid by utilizing sucrose, glucose, starch ,xylose,fructose,maltose and manna sugar. They were identified as [Bacillus polymyxa (Prazmowski)Mace 1889,588.].Optimized experiments of farmentation condition showed that the JN-1 optimum conditions were glucose 40g/l,yeast extract + carbamide + ammonia sulfate (5/5/2) 2 g/l, CaCl₂ 6 g/l,initial pH value as 7.0, culture temperature as 37℃, culture time as 48h; the JN-2 optimum conditions were sucrose 10g/l,yeast extract + carbamide + ammonia sulfate (5:5:2) 3 g/l, CuSO₄ 6g/l,initial pH value as 8.0, culture temperature as 33℃, culture time as 48h; the JN-15 optimum conditions were sucrose 20g/l,beef extract + carbamide + ammonia sulfate (5/5/2) 3 g/l, CaCl₂ 8 g/l,initial pH value as 7.0, culture temperature as 29℃, culture time as 48h.The results of the experiment on the flocculating characteristic of the bioflocculant produced showed that the effects were best for three strains when FeCl₃ be used of coagulant aid. The flocculating rate were highest, when flocculant addition was 2%. The flocculating activity was balanced ,when dosage was 1%～3%,but other were all under this dosage. The flocculanting activity of their liguor which is a kind of matter by depositing from grain alcohol, were highest. Their flocculating rate raised with the increment of flocculanting time.JN-1 and JN-2 had flocculanting activity ,when the pH value greater or less than 6.0.Furthermore, the flocculanting activity on the alkalescence side greater than on the acidity side. But JN-15 only had flocculanting activity on the alkalescence side. The experiment of mised bacillus fermentation proved that flocculanting products were not enhancing after fermentation with mised bacillus,but restraining effect of flocculant.By studying the extraction and application of bioflocculant, it was shown that we only extract bioflocculant from fermented liquors of JN-15 with grain alcohol. The fermented liquors of JN-15 had good effects on sewage treatment and decolor.