Materials
Magnetite (Fe3O4, analytical grade) provided by the Tianjin Institute of Fine Chemical Industry, Tianjin, China, was used as a seeding material in this study. The purity of the Fe3O4 was greater than 98% and its average particle size was 4.55 μm. The target was municipal wastewater, which was simulated using synthetic water prepared by diluting 1 g P l−1 in PO43− to the experimental concentration (0.5 mg/L) in tap water with very low hardness. A P concentration of 0.5 mg/L was selected to simulate the effluent of a municipal wastewater treatment plant that satisfied level 1 A of the discharge standard of pollutants for municipal wastewater treatment plants (GB 18918-2002).
A novel composite inorganic coagulant prepared in our laboratory was used for phosphate removal using superconducting magnetic separation technology. This new composite coagulant was prepared from red mud and a hydrochloric pickle liquor of bauxite. The developed coagulant had better coagulation performance than commercial polyaluminum chloride coagulant (PACl). The characteristics of the new coagulant are listed in Table 1. More information regarding this new coagulant can be found in Zhao et al. [28].