Coagulation and sedimentation of bacteria using a highly biodegradable polymeric coagulant

Copolymer of acrylamide with N-benzyl-4-vinylpyridinium chloride (PAAM-co-BVP) produced coagulation and sedimentation of Escherichia coli, Bacillus subtillus, Pseudomonas aeruginosa, and Staphylococcus aureus. Addition of more than 50 mg L−1 of PAAM-co-BVP produced bacterial flocks that precipitated at a rate of around 200 cm h−1. Supernatant population reduced in the range 1/30,000–1/25,000,000. Reduction of supernatant population was most effective when about 200 mg L−1 of PAAM-co-BVP was added. PAAM-co-BVP was highly biodegradable and the half-life estimated was 2.4 days when treated with activated sludge. The ratio of biochemical oxygen demand for 5 days (BOD5) to total organic carbon (TOC) was 0.607. Coagulation and sedimentation of bacteria using PAAM-co-BVP is expected to improve the water disinfection processes by saving chlorine and other hazardous chemical fungicides and by reducing the formation of trihalomethanes and other toxic chemical materials. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1618–1623, 2006