Recovery of textile industry wastewater by membrane-assisted advanced oxidation processes

The aim of this study is to investigate effective and low-cost recovery processes for textile industry wastewater, evaluate alternatives to reduce membrane fouling, and determine wastewater recovery processes that maximize water reuse and minimize waste generation in the textile industry. In this study, a laboratory-scale system incorporating membrane-supported advanced oxidation processes has been designed for the recovery of textile wastewater. The study integrated Fenton, Photo-Fenton, activated carbon/H2O2, and activated carbon/PMS oxidation processes with a membrane system that includes microfiltration (MF) and reverse osmosis (RO) processes. Fenton and Photo-Fenton processes were continuously operated at different hydraulic retention times, with doses of 2, 3, and 4 mM Fe2+ and 5, 10, and 15 mM H2O2, to determine the optimum conditions. The highest removal efficiency was achieved with a pH of 3.0, 10 mM H2O2, and 3 mM Fe2+. Continuous Fenton oxidation operated at different hydraulic retention times resulted in chemical oxygen demand (COD) removal efficiency of around 70% and total organic carbon (TOC) removal efficiency of around 76%. Prior to the membrane system, low-cost carbon obtained from agricultural waste was used as a catalyst in H2O2 and PMS oxidation to increase COD and TOC removal efficiency. Using commercial activated carbon, magnetic activated carbon, and pine nut activated carbon as catalysts, COD removal efficiencies of 79%, 81%, and 83%, respectively, were achieved in oxidations. Textile wastewater was passed through MF and RO membranes at pressures of 2, 4, 6, and 8 bars after oxidation, and the COD removal efficiencies and recovery rates of the product and concentrate were calculated. The most efficient removal performance was observed with pine nut activated carbon as the catalyst in H2O2 oxidation, resulting in a product COD value of <10 mg/L, conductivity of 25 µs/cm, and complete color removal. This combined process proposed for textile industry wastewater treatment is considered an efficient process in terms of conductivity, COD, and color parameters for wastewater recovery.