Sulfate radical-based advanced oxidation processes for water disinfection

Sulfate radical (SO4-center dot)-based advanced oxidation processes (AOPs) have emerged as promising technologies for inactivation of pathogenic microorganisms in water and wastewater, due to the high oxidation potential of SO4-center dot towards different microorganisms, such as chlorine-resistant bacteria, fungi and viruses; strong oxidation at wide range of pH adaptation, and the negligible formation of undesired halogenated byproducts, which is suitable to be applied in reclaimed water, underground water or emergency places. This work provides an overview on the kinetic responses of various pathogenic/indicator microorganisms in different SO4-center dot-based AOPs (e.g., metal-assisted, light-assisted, and piezo-catalytic ones) and the mechanisms responsible for the inactivation, mainly including membrane permeability is first destroyed, which leads to enzyme and genome damage, thus effectively inhibiting and inactivating pathogenic microorganisms. The effects of water matrix (e.g.,pH, temperature, and various water matrix) on the disinfection efficacies have also been reviewed and discussed. The formation of undesired byproducts in the SO4-center dot-based AOPs was also reviewed and discussed. Key points from the review are summarized in the conclusive remarks. Knowledge gaps, research needs, and design requirements of engineering applications of these processes in real-world practice are proposed as future perspectives.