The Effect of Feeding Patterns on the Performance of Activated Sludge Systems

Author: Suazo Francisco J.   Novak John T.   Higgins Matthew J.  

Publisher: Water Environment Federation

ISSN: 1938-6478

Source: Proceedings of the Water Environment Federation, Vol.2009, Iss.10, 2009-01, pp. : 5690-5708

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Abstract

Excessive amounts of monovalent cations are known to cause deterioration in settling and dewatering properties of activated sludge (Higgins and Novak, 1997a). 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 on 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 total suspended solids (TSS), effluent chemical oxygen demand (COD), sludge volume index (SVI), and capillary suction time (CST), accompanied by an increase in effluent biopolymer (proteins and polysaccharides). This study shows that the way in which feed is provided will have a large influence on effluent quality and settling and dewatering properties of activated sludge. Specifically, when a high substrate pressure is provided, better flocculation occurs, even in the presence of a high monovalent cation concentration, resulting in improved system performance.