PRETREATMENT OF AZO DYES USING OZONE

Wastewaters produced in textile industrial processes contain organic d yes which are not easily amenable to biological treatment. Pretreatmen t with ozone is a promising method for oxidation of those dyes to more degradable compounds. The aim of this work is to assess the oxidation kinetics of a specific azo dye used in the textile industry, Orange I I. Batch experiments were conducted in order to elucidate the oxidatio n route of the dye. Oxalate, formate and benzenesulfonate are found to be the oxidation intermediate compounds. A mathematical model which d escribes the dye elimination, the COD and BOD5 variation, the amount o f ozone reacted and the time evolution of the intermediate compounds h as been developed. (C) 1997 IAWQ. Published by Elsevier Science Ltd.