Colour removal from fermentation industry effluents

Large amounts of effluents from the fermentation industry are characterized by high COD and colour. Although significant reduction in COD is achieved through biological treatment processes, a substantial amount of colour rema ins. Coagulation and flocculation with alum acid iron salts are not effecti ve for colour removal. This is due to the nature of colour causing compound s which are almost totally dissolved and resistant to biodegradation. Hence , fermentation industries face difficulties in discharging their coloured e ffluents into either sewers or surface waters. In this study, colour remova l from biological treatment plant effluents of a fermentation industry with lime and ozone was investigated experimentally. Optimum lime dose for redu cing the colour to values around 1000 Pt-Co was found as 10.0 g/l, while 0. 9 g/l ozone was necessary to obtain the same residual colour. Economic eval uation has indicated that cost of lime treatment was 1.3 to 1.4 USD/m(3) wh ile it was 2.5 USD/m(3) for ozone treatment. Annual total costs for lime an d ozone treatment were also estimated as 2 million USD and 3.65 million USD , respectively. (C) 1999 IAWQ Published by Elsevier Science Ltd. All rights reserved.