RO filtration of biologically treated textile and dyeing effluents using ozonation as a pre-treatment

Bench-scale experiments were conducted to investigate the application of zonation pre-treatment for biologically treated textile and dyeing wastewater to improve performance of the RO process Based on zonation experiments, four specific ozone consumptions (SOC), 0, 0 3, 0 6, 4 0 mg O(3)/mg DOC(0) were chosen for study of the effects of zonation on the reverse osmosis (RO) process Membrane flux was recorded Also, the permeate water quality parameters such as TOC, conductivity were analyzed In addition, fouled membrane cleaning was studied The study further examined the nature and mechanisms of membrane fouling using scanning electron microscopy (SEM) and the energy dispersive X-ray spectrometer (EDS) The effect of zonation on RO filtration was found to depend on SOC The study revealed that significant improvement can be achieved in the efficiency of RO filtration by employing zonation with 0 6 mg O(3)/mg DOC(0) SOC Although the product water purity slightly decreased, the zonation pre-treatment showed advantages at 0 6 mg O(3)/mg DOC(0) SOC for the following (i) mitigation of flux decline due to membrane fouling, (ii) improvement in foulants cleanability In addition, hypotheses were put forward to explain the reasons from the aspect of organic matter characteristics changed by zonation, such as changing on functional groups and molecular weight of organic matter