Studies On Microbial Flocculant

Microbial flocculant is one kind of new and safe flocculants.lt has a good practical prospect.In this paper, adopted the method of microorganism pour plate, 28 strains of filiform fungi were isolated from edible fungi waste of our school .Kaolinite suspension was flocculated by the culture broth ,which was regarded as the index to determine flocculating activity and ability to produce flocculant. 10 flocculant-producing strains which had higher flocculating activity were obtained and they were further rescreened. After rescreened,a strain F00 (named temporarily F00, the same to the following),with highest flocculating activity was picked up.Using optimized and orthogonal tests, the optimum culture conditions are: Sugar as source of carbon, Cargamide as source of nitrogen,added P, Mg, K, Zn, Mn mineral elements, initial pH value 6.5, inoculation 4-5 x 104spores/ ml, temperature 30癈 and aerations 80 rpm.The flocculating ability of F0o was affected by sample addition, pH value , temperature, metallic ions, and so on.The F00 producing-flocculant had a wide range of pH value, and its thermostability was very good.Bioflocculant was roughly extracted from culture broth by organic solvent (Acetone),which added 2 times Acetone(V/V) and pH value was adjusted to 11, 21.3g wet products were obtained from 1 L culture broth.Cultivated for 65~72h in flakes, the F00 strain produces a strong-activity flocculant, under optimum flocculating conditions.The flocculant was used for flocculating test on nutrient-rich lake in the lab.The results indicated: Added flocculant's supernatant of centrifuged culture 2%(V/V) and treated for 10min, the removal rate of optical density (OD) was 70% and that of suspended solids (SS) was 62%.