Pergamon Wat. Sci. r .. rh. Vol. 33, No.3, pp. 1-8, 1996. Copyright C 1996 lAWQ. Pubhshed by Elsevier Science Ltd Printed in G"'.l BnllUn. All right. reserved. 0273--1223/96 $15-00 + oro PI!: S0273-1223(96)00295-l! DETOXIFICATION OF INDUSTRIAL WASTEWATERS IN AN EXTRACTIVE MEMBRANE BIOREACTOR A. G. Livingston, L. M. Freitas dos Santos, P. Pavasant, E. N. Pistikopoulos and L. F. Strachan Department 01 Chemical Engineering and Chemical Technology, Imperial College of Science, Technology and Medicine, London SW7 28Y, UK ABSTRACT Point source treatment of aqueous wastes produced in the chemical industry and containing toxic organic compounds in an Extractive Membrane Bioreactor (EMB) is reported. The EMB is shown to be effective in removing a range of toxic organic compounds, achieving over 99% removal at wastewater-reactor contact times of less than 30 minutes. A model which predicts the removal efficiency is discussed, and anew, advanced EMB system is described which overcomes the mass transfer limitations in the original plug flow configuration. Finally, data showing the effect of the membrane attached biofilms on membrane mass transfer is used to illustrate one of the key problems that must be solved during technology transfer if the EMB process is to prove successful at industrial scale. Copyright © 19961AWQ. Published by Elsevier Science Ltd. KEYWORDS Biodegradation; Extractive Membrane Bioreactor; Membrane Attached Biofilms; Membrane Mass Transfer: Toxic Organic Compounds. BACKGROUND Many toxic organic compounds which enter industrial wastewaters pass through conventional wastewater treatment plants unaltered. They may be present in detectable levels in the fmal plant discharge and may create problems in the operation of standard biological treatment plant (Leisinger and Brunner, 1986); for instance anilines are known to inhibit nitrification activity by more than 50% when present even at concentrations below I mg L-! (Eckenfelder, 1989). Many toxic organics are volatile (for instance 1,2 dichloroethane), and are stripped out of conventional plants by aeration (Parker et al., 1993). Furthermore, legislation aimed at controlling the permissible levels of specific toxic organic compounds (priority pollutants) is in force in many industrialised nations (e.g. EEe, 1982), and is creating a niche for new technologies aimed at dealing with these discharges. Many of these priority pollutants are in fact biodegradable under controlled laboratory conditions following acclimatisation of a suitable microbial inoculum. However, generally it is difficult to apply specifically acclimatised microorganisms to wastewaters in a conventional treatment plant, since there will typically be many substrates present in an overall site effluent flow which make it difficult to maintain selective pressure for the priority pollutant Treatment of aqueous wastes emitted from chemical industry processes at their point of emission, where the waste contains typically only a few organic compounds, has been advanced as an