Carwash wastewater treatment by the application of an environmentally friendly hybrid system: an experimental design approach

Treatment of the car wash wastewater (CWW) is crucial important when it is considered as a potential source of environmental health hazard due to the significant concentrations of contaminants such as detergents, oils-greases, phenol, organic materials. In the current study, chemical oxygen demand (COD), methylene blue active substances (MBAS), and turbidity removal efficiencies were conducted from manual CWW using the novel hybrid system including electrocoagulation/flotation (ECF), sedimentation and filtration processes. Experimental design for response surface methodology (RSM), was employed to create two series of 20 experimental runs using monopolar aluminum electrodes. It was optimized using the critical operational parameters such as applied current (1–2 A), electrolysis time (30–90 min) and pH (5–9). The removal efficiencies of COD, turbidity and MBAS were found to be 94.5%, 95% and 95.2% in the optimal condition, respectively. 4.2 kWh/m 3 and 0.23 US$/m 3 were determined for energy consumption and costs, respectively. Overall, this hybrid treatment system is proven as an economic and environmentally friendly technique to remove high contaminants from CWW.