Laterite Integrated Persulfate Based Advanced Oxidation and Biological Treatment for Textile Industrial Effluent...

This study investigated a combined approach of a persulfate-based advanced oxidation process (AOP) followed by biological treatment of a textile industrial effluent. The effluent from the textile industry is primarily composed of various dyes in varying concentrations, resulting in high chemical oxygen demand (COD) and biological oxygen demand (BOD). The model pollutant rhodamine B (RhB) was used in the optimization studies. During the persulfate oxidation process (PSO), persulfate activation is required to generate sulfate radicals (SO₄ ^•-). Raw laterite soil was used as a catalyst for the treatment of RhB in batch studies, and it was able to reduce the dye concentration by about 20% in 60 min of operation, with initial RhB concentrations of 150 mg L^-1 and persulfate concentrations of 200 mg L^-1. Furthermore, alkali-treated laterite soil (ATLS) was used as a catalyst, achieving 57%-60% removal in 60 min at pH 3 and complete removal after 72 h of biological treatment. Furthermore, the optimized conditions were tested on real field waters to determine efficiency, and it was observed that the PSO removed approximately 45% of COD, with further biological treatment for 72 h increasing the removal efficiency to 64%. All other parameters of water quality were reduced by more than 60%.