Opportunities of aluminum sludge dredging with soft magnetic conditioner for dewaterability enrichment

Aluminum (Al) salts are commonly used in conventional water facilities as primary coagulants. However, the coagulation process generates massive amounts of aluminum-based waste material, known as alum sludge or "Al-Sludge", which requires proper treatment before disposal. This study introduces an innovative ferrite conditioner composed of a blend of zinc-silver (Zn-Ag) ferrite (Zn_0.5Ag_0.5Fe₂O₄), prepared through a simple co-precipitation method with a viable yield. The prepared Zn-Ag ferrite conditioner (ZSF-Conditioner) was applied as a modified Fenton conditioner and characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). In addition, the thermal behavior of the material was analyzed using thermogravimetry (TG) and thermogravimetric analysis (TGA). The ZSF-Conditioner utilizes oxidative radicals to dismantle extracellular Al-Sludge and improves sludge dewaterability. The capillary suction time (CST) of the Al-Sludge before and after treatment revealed the effectiveness of the Fenton process. For accurate optimization of the system variables, response surface methodology (RSM) was applied based on a Box-Behnken experimental design. The optimal values for ZSF-Conditioner, hydrogen peroxide (H₂O₂), and pH were determined to be 43 mg L^{- 1}, 430 mg L^{- 1}, and 3.5, respectively, achieving a CST reduction efficacy of 74 ± 3%, which was consistent with the predicted efficiency from the polynomial model. Thus, the experimental data confirmed the effectiveness of the system for Al-Sludge conditioning, highlighting its notable implementation and safe technology.