Treatment of automotive paint wastewater in continuous-flow electroflotation reactor

With painting operations as a major origin of environmental concerns in automotive industry, novel and effective technologies are required for treatment of automotive paint wastewater. In this experimental study, a continuous-flow electroflotation reactor with effective volume of 38.4 L and stainless-steel electrodes were designed and implemented for treatment of this industrial wastewater. The system performance, namely the total suspended solids removal, was investigated with operational parameters including the hydraulic retention time, current density and influent total solids concentration. The removal rate ranged between 57 ± 1% and 95 ± 7% under initial total solids concentration 3000 mg/L, current density 50 A/m2, retention time 4 min, and initial total solids concentration 500 mg/L, current density 100 A/m2, retention time 8 min conditions, respectively. It was found that the removal rate decreases with the increase of influent total solids concentration. The results revealed that the suspended solids removal rate is directly related to the applied current density and hydraulic retention time. The electroflotation system showed to be energy-efficient compared to the commercial systems. Further, an empirical equation for the total suspended solids removal rate was established with the R2 value of 92.74%. The independent variables were the retention time, influent suspended solids concentration and applied current density.