Synergy of Free Radicals in Microcystis aeruginosa Inactivation within an Electrolysis/Persulfate/Chlorine System

In this study, an electrochemical system combined with peroxymonosulfate (PMS) and chlorine was developed to enhance the removal efficiency of Microcystis aeruginosa. The almost complete inactivation of algal cells can be achieved in 30 min at a chlorine concentration of 30.0 μM, PMS concentration of 0.75 mM, and current density of 15 mA/cm2. Quenching experiments indicate the involvement of •OH, SO4•–, Cl•, •O2–, and 1O2 in the inactivation of M. aeruginosa, and SO4•– plays a crucial role. Besides the inherent contribution of SO4•– in fortifying the electrolysis/PMS/chlorine system, the ability of the system to control algal proliferation is also bolstered by the SO4•– indirect activation of chlorine species. The alterations in superoxide dismutase, CAT, and malondialdehyde activities substantiate the induction of apoptosis in algal cells. The production of free radicals precipitates a cascade of oxidative impairment within algal cells, which is characterized by marked transformations in cell morphology and structural integrity. Further, microcystin-LR in actual water body also could be effectively removed in the electrolysis/PMS/chlorine system. The findings of this study convincingly establish the electrolysis/PMS/chlorine system as an efficient and environmentally friendly electrochemical application in alga wastewater treatment.