Integrated evaluation of Fenton and Photo-Fenton processes for the treatment of chemical industry wastewater: Pollutant removal and ecological risk potential of the treated effluent

The treatment of real chemical industry wastewater is challenging due to its complex composition and high levels of resistant organic pollutants. This study assessed the effectiveness of Fenton and photo-Fenton processes for degrading chromophoric compounds in such wastewater. Four reagent doses were tested in the Fenton process, with the optimal condition (0.1 g/L Fe2+ and 4 g/L H2O2) selected for photo-Fenton experiments. The impact of UV fluence (250, 500, and 750 mJ/cm2) on pollutant removal was evaluated. Photo-Fenton treatment at 750 mJ/cm2 achieved the highest efficiencies: 72% COD, 95% color removal, outperforming classical Fenton oxidation. Acute toxicity tests with Daphnia magna showed reduced toxicity in all treated samples; however, only the 750 mJ/cm2 photo-Fenton effluent-maintained immobilization below 10%, indicating negligible toxicity. These results demonstrate that UV-assisted processes enhance pollutant degradation and ecological safety. The study underscores the value of combining chemical and biological assessments to ensure environmentally safe wastewater discharge.