Integrated Fenton-like and ozonation based advanced oxidation processes for treatment of real-time textile effluent...

The treatment of real-time textile effluent, collected from the Common Effluent Treatment Plant (CETP) of Kerala Industrial Infrastructure Development Corporation (KINFRA) at Kannur (District), Kerala (State), India, have been studied by utilizing the Fenton-like and ozone (O₃) based advanced oxidation processes (AOPs). The Fenton-like AOP has been conducted as the pre-treatment of textile effluent involving the activation of persulfate (PS) and hydrogen peroxide (H₂O₂) as a single and the mixed oxidants by using the Flyash (FA)-Pd composite particles as the activator. The maximum chemical oxygen demand (COD) removal of 84% has been observed for a stand-alone O₃ based treatment at an O₃ flow rate of 5-6 g h^-1. By conducting the pre-treatment of textile effluent with the PS, H₂O₂, and mixed oxidants (PS and H₂O₂) based Fenton-like AOPs, the COD removal after an O₃ based post-treatment has been observed to be 83, 87, and 93% respectively at an O₃ flow rate of 2, 3, and 5 g h^-1. Hence, the Fenton-like pre-treatment involving the activation of mixed oxidants has been determined to be the best method for the highest COD removal of real-time textile effluent. The optimum values of initial oxidant-ratio (initial [H₂O₂]:initial [PS]), initial oxidant-dosage, and ozonation time, for the mixed oxidants based Fenton-like pre-treatment, have been determined to be 3 wt% mM^-1, 6:2 wt% mM^-1, and 60 min respectively. Under the most optimum conditions, the COD removal has been attributed to the combination of O₂^•- (for the pre-treatment) and ^•OOH (for the post-treatment) which possess relatively lower oxidation potential values.