A review of the textile wastewater treatment technologies with special focus on advanced oxidation processes (AOPs), membrane separation and integrated AOP-membrane processes

The current work presents a review of some recent studies focussing on the treatment of textile wastewater using advanced oxidation processes (AOPs), membrane separation and the integrated AOP-membrane process. The textile industry is the most water-intensive industry and discharges a wide variety of pollutants with widely varying values into its effluents, which among other factors, depend on the wet processes undertaken at certain textile industry, the geographical location of the industry, the substrates involved, and the processing conditions used. The application of homogeneous and heterogeneous AOPs for treating textile wastewater has been reviewed. Unlike homogeneous AOPs, heterogeneous AOPs use transition metal-based catalysts, produce higher kinetics in shorter treatment times, and generate a lesser amount of sludge. However, the techno-economic optimization of these catalysts in both the homogeneous and heterogeneous AOPs is a key direction for further research work. On the other hand, membranes have shown better performances than the conventional treatment processes, produce lesser byproducts, and have been found to be a suitable integration option to have a more robust treatment process employing both the AOPs and membrane separations. However, more work is needed to enhance the throughput, anti-fouling properties and large-scale module design of these membranes. Based upon a handful of studies focussing on the use of integrated AOP-membrane separation processes to treat wastewater, various process configurations were proposed for future engineering design. Key challenges hindering the development of such integrated process concepts have been presented, which could work as a reference for future research and development.