Aerobic and anaerobic biodegradability of a flocculant polymer

Flocculant polymers are used to improve the efficiency of separation proces ses used in wastewater treatment. The subsequent fate and effects of these additives are uncertain, however, with some previous reports indicating the m to be biodegradable while others indicate complete recalcitrance. The bio degradability of a common flocculant polymer was therefore evaluated, using both aerobic and anaerobic batch assays. Knowledge of the polymer's chemic al composition also allowed degradation stoichiometries to be calculated fo r complete biodegradation and also for incomplete degradation to several hy pothesized end products. Results showed conclusively that the polymer was s ubject to partial degradation by both aerobic and anaerobic cultures. Measu red oxygen consumption under aerobic conditions, and gas production under a naerobic conditions, both indicate that the partial destruction of pendant cationic moieties occurs, but that the polymer's CH2 backbone remains essen tially intact. These results allow seemingly contradictory previous reports to be explained. The findings are relevant to the environmental fate of th ese polymers as well as certain treatment process effects.