Insights into remediation of acid cracked intensive real olive mill wastewater by electro-Fenton process in the presence of per-sulphate

Abstract

ABSTRACT Olive mill wastewaters (OMW) have complicated pollutants that are hard to treat as it contains high concentrations of refractory and toxic compounds, which is looking for practicable and economical treatment options. In this work, the remediation of OMW was conducted using the electro-Fenton process (EFP) with iron electrodes in the presence of per-sulphate (PS) to chemical oxygen demand (COD) and total phenol (TP) reduction after acid cracking step. The system performance were COD, Colour, and TP per cent removal while initial pH, voltage, reaction time, H2O2 dosage, electrical conductivity (EC) and dosage of PS were independent variables. Acid cracking of wastewater in pH 2.5 was used to reduce disturbing parameters to provide suitable condition for reaction. Acid cracking leads to mean removal of turbidity, COD, TP, colour up to 80%, 18%, 17% and 30%, respectively. It was found that parameters such as H2O2, pH, reaction time, voltage and EC in an optimum value increase the process efficiency. The optimum condition by EFP was obtained at a pH 2, H2O2 0.2 M, voltage 10 V and conductivity of 11,000 µS/cm for removing over 70% of COD and TP at 60 min. However, after adding low concentration of PS there was not any enhance in the efficiency of COD and TP due to plenty presence of scavengers in OMW. It could be concluded that the remediation of pretreated OMW with acid cracking using EFP may be considered as reliable pretreatment method with further modifications.