Application of magnetic fields to wastewater treatment and its mechanisms: A review

Magnetic field (MF) has been applied widely and successfully as an efficient, low-cost and easy-to-use technique to enhance wastewater treatment (WWT) performance. Although the effects of MF on WWT were revealed and summarized by some works, they are still mysterious and complex. This review summarizes the application of MF in magnetic adsorption-separation of heavy metals and dyes, treatment of domestic wastewater and photo-magnetic coupling technology. Furthermore, the mechanisms of MF-enhanced WWT are critically elaborated from the perspective of magnetic physicochemical and biological effects, such as magnetoresistance, Lorentz force, and intracellular radical pair mechanism. At last, the challenges and opportunities for MF application in WWT are discussed. For overcoming the limitations and taking advantages of MFs in WWT, fundamental research of the mechanisms of the application of MFs should be carried out in the future. [Display omitted] •Application of magnetic fields effectively improves wastewater treatment efficiency.•Magnetic physicochemical effects are explained in detail.•A radical pair mechanism involving intracellular basal metabolism is summarized.•Theories and applications of magnetic fields in WWT should be improved.