Anaerobic treatment of split flow wastewater and concentrates from the textile processing industry

Under anaerobic conditions an almost complete decolorization of many dyes, an efficient GOD-removal and a digestion of substances that are refractory under aerobic conditions can be obtained. Therefore anaerobic processes can be used to treat highly loaded split flows and concentrates from the textile processing industry (TPI). Using a large number of biodegradability tests on a bench scale, different types of commercial textile auxiliaries, dyes, real split flow effluents from desizing and dyeing processes and real residual printing pastes were tested in regard to their anaerobic biodegradability. Investigations with anaerobic fixed bed reactors (AFBR) showed that it is possible to treat effluents containing a high organic load from desizing processes and highly coloured effluents from exhaust dyeing processes together resulting in high GOD-removal and nearly complete decolorization. With respect to the further aerobic removal of the remaining organic load of the AFBR's effluents it could be seen that the decrease of COD-elimination in AFBR resulting from high portions of effluents from exhaust dyeing processes and short hydraulic retention times is compensated by an increase in aerobic BOD-elimination. (C) 1999 IAWQ Published by Elsevier Science Ltd. All rights reserved.