Treatment of vegetable oil refinery wastewater by sequential electrocoagulation-electrooxidation process

In the present study a sequential process composed of electrocoagulation (EC) followed by electrooxidation (EO) was utilized at the laboratory scale to remove the chemical oxygen demand (COD) from wastewater generated in Iraqi vegetable oil refinery plant.in the EC, impacts of operating variables such as current density (10-30 mA cm2) and pH (4-10),and EC time (30-90 min) on the COD removal (RE%) were investigated using response surface methodology (RSM) based on Box- Behnken design(BBD). a mathematical correlation that relates the operating factors with RE% was developed and its regression coefficient was 99.02% confirming the significant of the model. Response surface plots showed that RE% increased with increasing current density and time while it decreased with increasing pH. The optimum removal with a lower cost for EC process were achieved at current density of 30mA/cm2, pH of 4, and electrolysis time of 90 min in which RE% of 69.19% was obtained with requirement of 0.513kWh/kg COD as specific energy consumption (SEC). The effluent exit from EC was treated by EO for a period of 240min at a current density of 30mA/cm2 and an initial pH value of 4 to obtain RE% of 96% at SEC of 1.554 kWh/kg COD. Combining EC with EO resulted in a total RE% of 98.72% and a total SEC of 2.067 kWh/kg COD. Based on the results of present study, the applicability of a sequential electrocoagulationelectrooxidation process for treatment vegetable oil wastewaters is feasible.

Automated summary

In this study, a sequential process of electrocoagulation (EC) followed by electrooxidation (EO) was used to remove the chemical oxygen demand (COD) from wastewater generated in an Iraqi vegetable oil refinery. The effects of operating variables on COD removal in EC were investigated, and a mathematical correlation was developed. The optimum removal efficiency of COD by EC was 69.19% and by EO was 96%. When EC and EO were combined, the total COD removal efficiency was 98.72%.