Herein, we reported a method to prepare magnetic sodalite sphere by using the mud from backwash wastewater after polyaluminum chloride (PAC) coagulation. The results showed that approximately 100% of Fe in the wastewater was precipitated as flocculent iron mud (FM) by adding PAC. FM was converted to spherical magnetic sodalite (FMP) with a diameter of 3 μm via a facile alkali hydrothermal method without adding Al/Si resources or reductant. The product FMP had the saturated magnetization of 10.9 emu g−1 and high Zn2+ adsorption capacity of 50.6 mg g−1. Without coagulation with PAC, the removal rate of Fe from the wastewater was only 92.7%, and the precipitated mud (RM) was converted to irregular particles (RMP), which had weak magnetic response and low capacity of Zn2+ adsorption comparing with FMP. With the method, the Fe in backwash wastewater was effectively recycled, and the generated sludge was converted to well-formed sodalite sphere without generating any secondary waste.
KW - Backwash wastewater; coagulation; magnetic sodalite; Mössbauer; adsorption DO - 10.32604/jrm.2021.015189