BIOAUGMENTATION OF AN ACTIVATED-SLUDGE RECEIVING PH SHOCK LOADINGS

The microbial population in an activated-sludge reactor can grow and f unction within a pH range around neutrality. Upset of the activated-sl udge system can occur when the reactor pH falls outside this narrow ra nge. An alkaline-tolerating culture was used in this study for augment ation of a laboratory-scale activated-sludge system that suffered abno rmal pH. During pulse shocks of pH 12 in the influent, treatment effic iencies of both an augmented reactor and an unaugmented control were f ound to decline when the pH value of the reactor went above 9. During a prolonged period of elevated influent pH, the augmented reactor had some chance of performing slightly better than the unaugmented control . Both reactors failed because the activated sludge was washed out aft er about one mean cell residence time. (C) 1997 Elsevier Science Ltd.