Application of magnetic coagulation for the advanced treatment of ethylene glycol wastewater

Abstract

Due to technological innovation, the influent for advanced treatment has increased, while the capacity of mechanical clarifiers is limited, which has led to a decrease in the effective removal of pollutants, so this paper explores the feasibility of using magnetic coagulation instead of conventional coagulation. The effect of each factor on coagulation is studied, and then the parameters are optimized by an orthogonal test. The optimum conditions are as follows: the doses of poly aluminium chloride and polyacrylamide are 40 and 1 mg L−1, respectively, the initial pH is 7.0, and the dose of magnetic powder (200 mesh) is 80 mg L−1. The average recovery of magnetic powder is 96.99%, and the properties of the recovered magnetic powder remain stable. Compared with values obtained in conventional coagulation, the removal rates of the chemical oxygen demand, turbidity and SiO2 increase by 7.0%, 6.6% and 5.1%, respectively, and reagent cost decreases by 26.6%. The sedimentation time of conventional coagulation is approximately 30 min, while that of magnetic coagulation is approximately 2 min. The average sedimentation rate of magnetic coagulation is 14 times faster than that of conventional coagulation. Therefore, it is feasible to use magnetic coagulation.