Effect of feeding patterns on the performance of activated sludge systems.

Excessive amounts of monovalent cations are known to cause deterioration in settling and dewatering properties of activated sludge. In this study, variations in the feeding pattern to a sequencing batch reactor (SBR) were evaluated to determine if the feed pattern could influence effluent quality and sludge characteristics under high monovalent cation concentrations. Data showed that deflocculation caused by high concentrations of sodium could be mitigated by using a feed cycle where the influent to the SBR was provided over a period of 1 minute. In contrast, when the feed was provided over 4 hours, deterioration in settling and effluent water quality was observed, as reflected by an increase in effluent suspended solids, effluent chemical oxygen demand, and capillary suction time.