A sustainable approach to the treatment of textile reverse osmosis concentrate using the photo-Fenton process

Textile industry wastewater consists of colored wastewater containing high concentrations of organic matter, complex components, reactive dyes, and chemical residues. While reverse osmosis (RO) membrane systems are frequently used to sustainably manage high-volume wastewater streams, they also produce a concentrated, resistant, and nonbiodegradable effluent. In this study, the photo-Fenton process was applied and optimized using Box-Behnken Design (BBD) to treat RO concentrate containing high concentrations of toxic and pollutant species. H₂O₂/COD, Fe²⁺/H₂O₂, and reaction time were selected as operating parameters, while COD, color index (CI), ultraviolet absorbance at 254 nm (UV₂₅₄), and ultraviolet absorbance at 280 nm (UV₂₈₀) removal efficiencies were selected as model responses. Statistically, the model's fits were evaluated using variance analysis. Numerical analysis determined the optimum process conditions as H₂O₂/COD 2.0, Fe²⁺/H₂O₂ 0.25, and reaction time 68.4 min at pH 3.0. Under optimum conditions, the validation experiments demonstrated that the photo-Fenton process achieved removal efficiencies of 78.5% for COD, 96.6% for CI, 82.5% for total suspended solids, 92.8% for UV₂₅₄, and 85.0% for UV₂₈₀. The calculated operating cost of the process was 14.3 €/m³. The obtained results showed that the applied photo-Fenton process effectively removed pollutants from RO concentrate, and that the BBD could be used to optimize its operating conditions.