Treatment of Car-washing Wastewater by Electrocoagulation-Ultrasound Technique for Reuse

To reduce the water consumption and pollution in car-washing, a combined technique, i.e., electrocoagulation coupled with ultrasound, was proposed to treat the car-washing water for reuse. The effects of parameters (such as current intensity (I), initial pH, electrode distance (d), treatment time (t), and so on) on the removal efficiency of COD and turbidity in the wastewater were studied. The results indicate that the removal efficiency of COD and turbidity is maximum (68.77% and 96.27%, respectively) when I=1.2 A, pH=6.0, d=1.5 cm, and t=20 min. The quality of treated wastewater could meet the COD and turbidity requirements in Water Quality Standard for Urban Water Consumption. Meanwhile, the character of the reaction cell was studied, and it shows that the cell voltage is a linear function of the electrode distance when the current is constant. Compared with the removal rate of pollutants from car-washing wastewater by the single electrocoagulation method, a higher rate could be achieved by this combined technique.