Treatment of real time textile effluent containing azo reactive dyes via ozonation, modified pulsed low frequency ultrasound cavitation, and integrated reactor

Abstract

The common effluent treatment plant (CETP) of Kerala Industrial Infrastructure Development Corporation (KINFRA) at Kannur (District), Kerala (State), India undertakes the treatment of textile effluents containing the azo reactive dyes by using the stage-1 and stage-2 facilities. In this investigation, the stand-alone ozonation (O3) and modified pulsed low frequency ultrasound (US) cavitation as well as their integrated reactor are studied for the possible replacement of stage-1 facility which generates large amount of sludge. The major criteria for the replacement are to achieve minimum 90% of chemical oxygen demand (COD) removal, without the sludge formation, with the final COD level of less than 150 mg L − 1 as per the requirements of KINFRA, India. The stand-alone ozonation and modified pulsed low frequency US cavitation processes provide the COD removal of 90 and 65%; while, their integrated reactor provides 86% COD removal, without the sludge formation, with the final COD level less than 150 mg L − 1. Since all the conditions are satisfied only by the stand-alone O3 process, the latter is highly suitable for the replacement of stage-1 facility. The COD removal is possibly achieved via the generation and attack of ·OOH for the stand-alone O3 process; while, the same is achieved via the generation and attack of O2·- for the modified pulsed low frequency US cavitation process and their integrated reactor.