A test for predicting propensity of activated sludge to acute filamentous bulking

Filamentous bulking is a solid-liquid separation problem well known to acti vated-sludge plant operators. The use of curative additives is a rather del icate solution and the tools developed to anticipate it seem limited. To co mplement existing sludge sedimentation monitoring tools, a new test to asse ss the propensity of activated sludge for filamentous bulking was developed . It consists of challenging the sludges by feeding them under conditions f avoring filamentous bacteria for 24 hours. The effects of such an acute tre atment on sludge settleability is subsequently assessed through a simple sl udge volume (SV30) measurement with reference to a control. The sludge can then be evaluated as prone to bulking (unstable sludge) or not (stable slud ge). Such a test can be used to predict the occurrence of filamentous bulki ng in activated-sludge treatment plants. This so-called acute bulking rest requires simple equipment and can be done by any wastewater treatment plant operator.