Olive oil wastewater treatment with the use of an electrolysis system

Olive oil wastewater (OOW), a toxic liquid associated with the production of olive oil, was treated by an electrochemical method using Ti/Pt as anode and Stainless Steel 304 as cathode. In this technique, sodium chloride 4% (w/v) as an electrolyte was added to the wastewater and the mixture was passed through an electrolytic cell. Due to the strong oxidizing potential Of the chemicals produced (chlorine oxygen, hydroxyl radicals and other oxidants) the organic pollutants were wet oxidized to carbon dioxide and water A number of experiments were run in a batch, laboratory-scale, pilot-plant, and the results are reported here. After 1 and 10 h of electrolysis at 0.26 A/cm(2), total COD was reduced by 41 and 93%, respectively, total TOC was reduced by 20 and 80.4%, VSS were reduced by 1 and 98.7%, and total phenolic compounds were reduced by 50 and 99.4%, while the mean anode efficiency was 1960 gh(-1) A(-1) sq.m(-1) and 340 g h(-1) A(-1) sq.m(-1). Also, the mean energy consumption was 1.273 kwh per kg of COD removed and 12.3 kwh per kg of COD removed for 1 and 10 h, respectively. These results strongly indicate that this electrolytic method of total oxidation of OOW is not feasible. However it could be used as an oxidation pretreatment stage for detoxification of the wastewater. (C) 1997 Elsevier Science Ltd.