Removal of some organic compounds and color from olive mill wastewater by electrocoagulation

Abstract

The effective performance of electrocoagulation (EC) technique in the treatment of olive mill wastewater (OMW) was investigated using Al and Fe electrodes. Current densities (CD), electrode materials (Al and Fe), electrolyte amounts, time and initial pH value were selected as parameters. In these parameters, the removal percentage of chemical oxygen demand (COD), color, phenol and lignin from OMW were experimentally investigated. OMW was used directly without pH adjustment and pretreatment. The experiment results show that the removal efficiency depends on time, types of electrodes, applied current and electrolyte amounts and pH value. Optimum working pH was found to be in the range from 3 to 7. It was found that an increase in the current and electrolysis time enhanced the speed of the treatment significantly. In addition, when a Fe electrode was used, it was found that the obtained results of phenol, lignin, color and COD removal were more effective than with an Al electrode. When the experiments were carried out at 20 V and at a current intensity of 1,75A., it was found that the percentages of lignin, phenol, COD and color removal were 55%, 80%, 65% and 80% respectively by using a Fe electrode for 60-min electrolysis time, while they were 49 %, 70%, 35% and 90% respectively for the Al electrode. In addition, the effect of electrolyte was examined and an increase was observed in the removal percentage by increasing the electrolyte amount. Energy consumption and rate constant for both electrode were calculated. The results show that electrocoagulation could be considered as an effective alternative solution for the treatment of OMW or may be combined with another conventional treatment process to achieve high quality effluent water.