Efficiency and Mechanism of Low-Cost Coal Fly Ash Magnetic Beads Enhanced Coagulation for Treating Relatively High-Turbidity and Low-Organic Wastewater

The resource utilization of coal fly ash solid waste has become a research hotspot. In this work, magnetic beads were separated from industrial waste fly ash by wet magnetic separation and used as magnetic seeds (MS-CFA) in magnetic coagulation (MC). The superiority of MC was evaluated by comparison with traditional coagulation (TC). Meanwhile, The potential and feasibility of MS-CFA were evaluated by also employing Fe3O4 in the MC process. MS-CFA was characterized by SEM, XRD, VSM, and XPS. The results showed that MS-CFA was a composite microsphere crystal with a saturation magnetization of 33.71 emu/g. The addition of MS-CFA reduced the residual turbidity from 10.87 NTU to 3.27 NTU and increased the chemical oxygen demand (COD) removal rate from 42.92% to 64.24%. MS-CFA achieved water treatment performance comparable to or even better than Fe3O4, especially in organic matter removal. As a waste-derived material, MS-CFA not only reduces costs but also provides stronger adsorption for organic pollutants. This study provides a reference route for developing low-cost and high-efficiency magnetic coagulation technology.