Optimization of the photo-Fenton-like process for real and synthetic azo dye production wastewater treatment using response surface methodology

Treatability of synthetic Acid Blue 193 and Reactive Black 39 production wastewaters and real Reactive Black 39 production effluent via photo-Fenton-like process was investigated. The Central Composite Design technique was used to study the effect of some critical process parameters of the photo-Fenton process (e.g. reaction time, initial COD and Fe³⁺H₂O₂ molar ratio) on synthetic Acid Blue 193 production wastewater treatment efficiency in terms of color, chemical oxygen demand (COD) and total organic carbon (TOC) removals. Selected process parameters were optimized to obtain maximum color, COD and TOC removal efficiencies. Optimum working conditions were established as 45 min reaction time and a Fe³⁺H₂O ₂ molar ratio of 0.073 for wastewater having an initial COD (COD _o) of 200 mg L^-1. Under these conditions, 99% color, 83% COD and 58% TOC abatements were experimentally obtained. In case of real Reactive Black 39 production effluent, photo-Fenton-like treatment efficiency was found to be considerably lower than that of the synthetic acid and reactive dye production wastewaters, which was attributable to the relatively high chloride (i.e. a well known *OH radical scavenger) content of the real effluent.