A compound bioflocculant CBF with high flocculating activity,produced by mixed culture of Rhizobium radiobacter F2 and Bacillus sphaeicus F6 from soil,was investigated with regard to its production and application in low temperature and low turbidity drinking water treatment.The most preferred carbon source,nitrogen source and C/N ratio(w/w)for strains F2 and F6 to produce CBF were found to be glucose,Urea and 20,respectively.