Control of the bacterial content of water with synthetic polymeric flocculants

The removal of low concentrations of Escherichia coli from water by coagulation with synthetic polymers was studied by observation of filtration rate, electrophoretic mobility, and light transmission and scattering. Cationic polyethyleneimines with molecular weights from 300 to 112, 000 were effective at polymer concentrations from 0. 1 to 80 mg per litre, but the quantity of polymer needed to initiate coagulation was independent of molecular weight, and above about 10 mg per litre the high-molecular-weight polymers caused redispersal of the bacterium. Over a wide range of molecular weights, non-ionic and anionic polyacrylamides at polymer concentrations from 0.1 to 50 mg per litre were not effective in the coagulation of the bacterium. A bibliography of 33 references is appended.