A bioflocculant-producing silicate bacteria screening and its flocculating activity

A flocculant-producing silicate strain,B12,was isolated from soil.Its flocculant producing conditions and flocculation characteristics were studied.The results show that,adding 8 g/L glucose and 0.15 g/L(NH4)2SO4 as the source of carbon and nitrogen,adjusting the initial pH value at 6.9,culturing 72 h at 31 ℃ and the shaking speed of 150 r/min,the highest flocculating rate reaches 93.6%.Providing oxygen can enhance the bacterium growth rate,but will be disadvantageous to product flocculant.B12 is cultured in sections,which is benefit for promoting the flocculating rate.The extracellular metabolites of B12 strain mainly takes the flocculant,and could apply in pH range of 0.5～12 with highly stability,and the flocculant rate is above 90%.Compared with other inorganic flocculants,the bioflocculant is high effective,non-toxic and with no secondary pollution,and it will have a good prospect of application in the solid-liquid separation and mineral pulp wastewater treatment.