Fenton Oxidation Pre-Treatment of Olive Mill Wastewater for Enhanced Subsequent Biological Degradation

Abstract

Olive mill wastewater is characterized by high organic load, dark coloration, and the presence of refractory phenolic compounds that hinder conventional biological treatment processes. This study investigates the application of Fenton oxidation as a pre-treatment method for improving the biodegradability of olive mill wastewater prior to subsequent biological degradation. The research focuses on evaluating the influence of hydrogen peroxide dosage, ferrous ion concentration, reaction time, pH, and temperature on oxidation efficiency and pollutant removal performance. Experimental analyses demonstrated that the Fenton process effectively degraded phenolic compounds, reduced chemical oxygen demand, and improved the biodegradability index of the wastewater through the generation of highly reactive hydroxyl radicals. Optimized operating conditions significantly enhanced the breakdown of complex organic pollutants and reduced toxicity, thereby facilitating improved microbial activity during the biological treatment stage. Kinetic evaluation revealed that oxidation efficiency is strongly dependent on reagent concentration and acidic reaction conditions, which govern hydroxyl radical formation and pollutant mineralization. The pre-treated wastewater exhibited increased susceptibility to biological degradation, resulting in enhanced overall treatment efficiency and reduced treatment time in downstream biological processes. Comparative assessment with untreated wastewater confirmed that Fenton oxidation substantially improves process stability and pollutant removal effectiveness in integrated treatment systems. Furthermore, the combined physicochemical and biological approach offers advantages such as reduced sludge generation, lower environmental impact, and improved compliance with wastewater discharge standards.