The effect of chemical settling on the kinetics and design of activated sludge for tannery wastewaters

The effect of chemical settling of tannery wastewaters on the kinetic behav iour and performance of activated sludge process is investigated on the bas is of experimentally supported model evaluations. Experiments involved besi dese conventional characterization, detailed COD fractionation and assessme nt of major kinetic and stoichiometric coefficients by means of respirometr ic measurements. A multi-component model based on the endogenous decay conc ept was used for the kinetic interpretation and design of activated sludge. Results indicated that chemical settling as a pretreatment step induced a totally different kinetic pattern, significantly improving the biological t reatability of tannery wastewaters. Design implications were evaluated in t erms of major parameters of practical importance, such as effluent quality, activated sludge composition, aeration volume, oxygen demand and sludge ge neration. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.