Screening of a Microbial Flocculant Producing Silicate Bacteria MT5-2 and its Flocculating Activity

Abstract

A microbial flocculant (MBF) producing silicate bacteria MT5-2 was isolated from different sources of samples by silicate selected medium. Its chemical composition, optimal flocculation conditions，flocculation characteristics and primary application were studied in this paper. The results showed that the flocculant was an extracellular polysaccharide, and its flocculation activity was mainly distributed in the fermentation broth. The optimal flocculation conditions were as follows: for the 100 mL kaolin suspension, flocculant dosage was 4mL, metal cation dosage was 1% of ZnCl2 3mL, pH 7.5. The flocculation activity can reach 95% under this condition. Application results showed that flocculant MT5-2 had better flocculation activity in several common suspensions, such as kieselguhr, bentonite, soil, active carbon and starch, compared with polyacrylamide and inorganic salt.