Techno-economic assessment of integrated photochemical AOPs for sustainable treatment of textile and dyeing wastewater

Textile and dyeing industries generate large quantities of wastewater rich in colourants, dyes, chemicals, surfactants, etc. Notably, textile effluents are highly coloured, toxic, odorous, and with high chemical oxygen demand (COD) and low biochemical oxygen demand (BOD). These colour-causing complex organic compounds in wastewater streams are not completely degraded or removed using conventional physicochemical and biological treatment processes. Although as per regulatory norms, COD, colour, and BOD need to be eliminated if the treated water is to be reused. A batch-scale study of photochemical Advanced Oxidation Processes (AOP) to treat textile wastewater from a common effluent treatment plant is aimed to improve biodegradability and downstream performance. The assessment compared the techno-economic feasibility of integrating four photochemical AOPs with existing biological treatment plant in terms of their efficiency, energy requirement, and overall cost of treatment. Photochemical AOPs considered in this study were UV photolysis, UV/H2O2, UV photo Fenton, and UV/TiO2 photocatalysis. Although every treatment improved the quality of treated water, UV/TiO2 photocatalysis was the most promising for removing COD and BOD and required the least electrical energy per order (10.79 kWh/m(3)/order-COD removal and 5.16 kWh/m(3)/order-colour removal) whereas UV/TiO2 was the most economic (0.77 US dollar or INR 59.75/m(3)).