Separating pathogens from drinking water and food using magnetic nanomaterials: opportunities and challenges

Bacteria contamination causes detrimental health impacts worldwide, but current methods to separate bacteria from drinking water, food, and beverages are costly and insufficient. Thus, magnetic separation provides an important, novel method to remove pathogens from aqueous mediums. Surface-functionalized superparamagnetic nanoparticles can adhere to bacteria and provide strong magnetic properties that allow nanoparticle-bacteria complexes to separate rapidly from solutions when an external magnetic field is introduced. This review summarizes key studies that employ magnetic nanoparticles for pathogen separation in drinking water and food systems. A combination of metrics including log removal efficiency, incubation time, adsorption capacity, and pH dependence, is used to enable effective comparisons among magnetic separation studies. We also examine the reusability of magnetic nanoparticles, which remains a major barrier to large-scale implementation. Finally, we outline the remaining technical challenges and discuss future research directions needed to advance magnetic separation toward practical, large-scale treatment applications.