Effect of Filtration using Sand Filter or MBR on Ozone Requirement for Color Removal in Textile Wastewater

The effect of filtration on ozone requirement for color removal in biologically treated textile wastewater effluent was investigated using two separate filtration methods. Filtered effluents were obtained from an ultrafiltration membrane and a sand filtration system. Ozonation was carried out in bubble column reactor tests to compare the efficiency of ozone tertiary color removal for the base case of conventional activated sludge (CAS) gravity clarified effluent, to sand filtered CAS effluent and immersed membrane bioreactor (iMBR) effluent. The ozone requirement to achieve the 200 mg/L platinum-cobalt color units (CU) target for the iMBR system was 26% that of the CAS system. The requirement for the sand filtered effluent was 42% of the CAS effluent. When reuse of the ozone treated water within the facility was not considered, no technology provided a clear cost advantage relative to the base case. Given that the membrane treated effluent is the only one capable of being used for any grade of water reuse, the inclusion of water recovery and reuse makes the membrane filtered system a compelling alternative.