Removal of Microcystis aeruginosa by natural pyrite-activated persulfate: Performance and the significance of iron species

In this study, the feasibility of removing Microcystis aeruginosa by heterogeneous persulfate activation using ubiquitous natural pyrite was investigated. The results indicated the significant degradation efficiency of chlorophyll-a (over 90%) was obtained in pyrite/persulfate (PS) system, which was influenced by various experimental parameters, including pyrite loading, PS dosage, the initial pH and coexisting common anions. The EPR, SEM, TEM, XPS and zeta potential analysis indicated that the reactive oxygen species (center dot SO4, center dot OH, center dot O-2 and O-1(2)) generated during PS activation using pyrite played an essential role in facilitate the destabilization of algae cells to further destroyed them, while the continuous formation of oxidation layer consisting of FeOOH and Fe2O3 on pyrite surface and dissolved Fe(III) could favor coagulation of algae. Furthermore, pyrite/PS system was not only effective in destructing the cellular morphology and reducing the viability of algae, but also able to control algal organic matter, which could avoid yielding serious secondary pollution. This study highlighted the dual role of iron species as both catalyst and coagulant for M. aeruginosa removal and demonstrated that it is highly advantageous to employ pyrite/persulfate system with high-efficiency and cost-effectiveness to eliminate algae.