Electrochemical Treatment of Olive Processing Wastewater Using a Boron‐Doped Diamond Anode

Abstract

Electrochemical oxidation (EO) of olive processing wastewater (OPW) samples was carried out using a boron‐doped diamond anode. The treatment was performed in a batch system with recirculation, using an up‐flow single‐compartment electrochemical cell. The influence of the wastewater dilution, the applied current density (j) and the recirculation flow rate (RFR) on the EO performance was investigated. Although OPW is a complex mixture of organic compounds, its chemical oxygen demand (COD) decay with time followed the theoretical models developed for single organic compound solutions, in particular when EO is diffusion controlled. The average mass transfer coefficients determined at this regime were found to increase with RFR, being independent of j. Regarding the mineralization index of the final samples, after 7 h a decrease was observed with the increase in j or RFR. Specific energy consumption was also evaluated and it increased with dilution and j, being lower for higher RFR. The lowest specific energy consumption observed, obtained with the raw sample at j = 20 mA cm−2, was 24 Wh gCOD−1.