A comprehensive laboratory investigation was conducted to test the feasibility of employing biological and physicochemical treatment processes for complex wastewaters discharged by several chemical industries. Results obtained during this study indicated that the wastes contain a fraction of toxic and nonbiodegradable organic matter, which limits the implementation of a conventional biological treatment process for the combined wastewater stream. Toxicity, as measured by a bioluminescence assay (Microtox), served as a valuable tool to assess biological treatability of various waste sources, with the aim to select an economically feasible and environmentally acceptable treatment/management program for an industrial park. Toxicity values served as quantitative indices for the establishment of baseline data of removability potential, defined either by biodegradation or carbon adsorption. This removability data enabled identification of problematic waste sources, which are only partially biodegradable and/or possess considerable toxicity. Further investigation of the problematic waste streams focused on the evaluation of activated carbon adsorption characteristics, using toxicity balances instead of traditional chemical determinations. This method could be successfully employed to yield simultaneously both adsorption characteristics and an assessment of the impact of the treated effluent on biota in receiving waters. © 1994 by John Wiley & Sons, Inc..