The Application of an Electrocoagulation Process to the Sustainable Treatment of Initial Rainwater and the Simulation of a Flow Pattern in an Experimental Device

The pollutant content in initial rainwater is very high, so the treatment and research of initial rainwater has become an engagement issue in controlling non-point source pollution and realizing sustainable development in Chinese cities. This study explores the best flow pattern suitable for treating initial rainwater by electrocoagulation (EC), and a pilot-scale experiment is conducted to analyze the effect of the EC process on the treatment of initial rainwater. The findings indicate that the latter enhances the turbulent flow effect and the EC process treatment effect better under the two flow modes of parallel perforation flow and dislocation perforation flow. For the dislocation perforated flow pattern, the removal rates of suspended matter (SS), chemical oxygen demand (COD), and phosphorus (TP) are 94.00%, 81.95%, and 98.97%, respectively, which reach the expected treatment targets. Using the electrocoagulation–filtration (ECF) process to treat initial rainwater, the final effluent exhibits high quality and could be used as urban circulating cooling water. Specifically, SS, COD, and TP concentrations are 15.00 mg/L, 21.06 mg/L, and 0.11 mg/L, respectively. The hydraulic retention time of the process is short, only 30 min, and the energy consumption is low, 0.57 kWh. This study provides a reference for the sustainable treatment of early urban rainwater and the design of the flow pattern of the EC process.