Rapid and high purification of olive mill wastewater (OMV) with the combination electrocoagulation-catalytic sonoproxone processes

Background and purpose: Olive Mill Wastewater (OMW) is one of the most problematic wastewater in the food industry. Thus, its ineffective treatment causes severe pollution in the environment. In this study, the treatment of OMW by combining electrocoagulation (EC) and catalytic sonoperoxone processes was investigated. Materials and methods: The efficiency of turbidity removal and mineralization of OMW using EC was investigated by applying the following operation variables: type of electrode (iron and aluminum), reaction time (0- 60min) and current density (0.08-0.77 A/dm(2)). Then, a single ozonation process (SOP), a catalytic ozonation process (COP), an ultrasonic process (US), H2O2, COP/US, a peroxone process (H2O2/O-3) and a catalytic sonoperoxone process (H2O2/COP/US) were performed. Finally, the biodegradability of OMW was measured by using BOD5/TOC index. Results: Maximum removal efficiency of the turbidity, Total Organic Carbon (TOC) and consumed electrode in the EC were 82%, 75% and 634 mg of iron electrode/L. of OMWW, respectively. The TOC removal efficiency of the pretreated OMW by using the following oxidation processes of US, H2O2, SOP, O-3/H2O2, COP, COP/US and H2O2/COP/US was 8%, 15%. 20%, 25%, 61%, 68% and 75%, respectively. In addition, the biodegradability index (BOD5/TOC) in the catalytic sonoperoxone process increased by as much as 32% compared to raw OMWW. Conclusion: The EC process caused an effective per-treatment of OMW and combined by sonoperoxone process improved its biological biodegradability. So, this process can be used for the efficient treatment of OMWW and the wastewater produced by similar industries. (C) 2019 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.