Efficient Removal Performance of COD in Real Laundry Wastewater via Conventional and Photo-Fenton Degradation Systems: A Comparative Study on Oxidants and Operating Time by H2O2/Fe2+.

The present study was performed to compare the chemical oxygen demand (COD) removal performances of conventional Fenton (c-Fenton) and photo-Fenton (p-Fenton) processes from real laundry wastewater in batch reactors. The effects of pH, Fe²⁺ dose, H₂O₂ dose, and H₂O₂/Fe²⁺ ratio on both Fenton processes were investigated. The maximum removal was found at pH 3 for both Fenton processes. The optimum H₂O₂/Fe²⁺ ratio was determined to be 900/400 for the c-Fenton process and 600/400 for the p-Fenton process. The COD removal efficiencies in the optimum H₂O₂/Fe²⁺ ratios were achieved as 90 and 99% for c-Fenton and p-Fenton processes, respectively. Kinetic models were tested to understand the oxidation mechanism using Behnajady–Modirshahla–Ghanbery (BMG), zero-order, first-order, and second-order reactions kinetics. The results indicated that the experimental data were described well by BMG model (R² = 0.988) for c-Fenton, and the zero-order kinetic model (R² = 0.976) for p-Fenton process. The results supported the use of p-Fenton due to achieved faster oxidation with fewer reagents to remove COD from the wastewater. [ABSTRACT FROM AUTHOR]