Evaluation of the effectiveness of electro-coagulation-flotation process for removal toxicity of olive oil mill wastewater

The olive oil mill wastewater is one of the contaminating food industrial wastewaters. Olive oil extraction process imports wastewater with high phenolic chemicals into the environment. In this study the toxicity of raw olive oil mill wastewater and the effluent of electro-coagulation have been investigated. Germination test was used for evaluating the toxicity of wastewater and effluent process. Electro-coagulation-flotation examinations performed in a plexiglas electrochemical reactor with 1750 ml practical volume. 4 blades of aluminum and titanium as anode and cathode electrodes with a gap of 2 cm were connected to DC power supply in monopolar parallel mode. Based on the information from this study, the pollution load of phenolic compounds in olive oil mill wastewater is 1000 times more than municipal wastewater. Also, the evaluation toxicity of effluent obtained from the process in natural pH of wastewater (pH=5.2), 117 mA/m2 current density and 30 minutes time process, suggests that the effluent causes plant species growth, even without dilution. The results obtained from this research can warn us to the risks of releasing these wastewaters without treatment and toxic effects on the different species of plants. Results demonstrated although using of electro-coagulation-flotation process removes high percent of pollutants of olive oil mill wastewater, but, it can’t attain the discharge limitations, then it should be more treated with some other methods.