Some investigations on bioflocculant producing bacteria

Bacillus sp. As-101 which produces flocculating substances was isolated from activated sludge, using a proteolytic enzyme. Bioflocculant As-101 was partially purified by cold ethanol and cetylpyridinium chloride. The partially purified flocculating substance was an acidic polysaccharide including uronic, pyruvic and acetic acids, respectively, in an approximate ratio of 11.4%, 6.1%, 0.4%. The biopolymer is also a sugar-protein derivative consisting of glucose, mannose and galactose. The protein, the sugar contents ratio is about 83-17%. Bioflocculant As-101 acted under acidic condition and the maximum activity was observed at optimum pH similar to 3.7 and optimum concentration of 30 ppm in kaolin suspension. The flocculating activity was stimulated by the addition of Al3+, Fe3+ and Ca2+ in optimum concentrations of 0.2, 0.25 and 8 mM, respectively. The flocculating activity was linearly decreased on increasing the heating period and was inactivated after 8 min of heating. (C) 2000 Elsevier Science S.A. All rights reserved.