ABSTRACT
Upsets of activated sludge processes at Publicly Owned Treatment Works (POTWs) can be caused by toxic waste streams discharged by industrial users. A mild case of toxicity can manifest itself in depression of nitrification rates or in killing the protozoan population with a resulting increase in the effluent turbidity. In order to reduce the chances of a toxic upset, some POTWs with the voluntary cooperation of major industrial users, have implemented a program of screening industrial wastestreams for potential toxicity to the activated sludge. Experimental methods of assessing toxicity to biological treatment can be divided into three categories: respirometric methods, methods based on measurement of specific bacterial cell constituents and methods measuring inhibition of substrate removal. The fed batch reactor (FBR) procedure is one of the methods employing measurement of substrate removal. The FBR test was found to be a simple and inexpensive test for rapid screening of wastestreams for acute inhibition/toxicity to activated sludge.
