Moderate effect of calcium peroxide enhanced coagulation on algae containing water: cell characteristics and disinfection by-products formation

Preserving cellular integrity while eliminating algae cells constitutes a pivotal aspect in the removal of algae within potable water treatment facilities. The effect of calcium peroxide (CaO2) as a pre-oxidizer on water containing Microcystis aeruginosa and its algal removal performance and reaction mechanism were investigated in this study. CaO2 was found to be highly effective in removing algae, requiring only a small amount to eliminate algal cells while preserving their cellular integrity. At 1.0 mM CaO2, the algal cell damage rate was 19.2% with mild oxidation and slight damage to cellular integrity. Dissolved organic carbon decreased to 75.9% and 13.5% of the original after pre-oxidation and enhanced coagulation at 1.0 mM CaO2, respectively. Higher CaO2 concentrations improved coagulation and reduced disinfection by-products (DBPs) precursors. Notably, CaO2 was more effective in reducing the formation of carbonaceous disinfection by-products compared to nitrogenous disinfection by-products. The formation of most DBPs by chloramination was less than that by chlorination, except for trichloromethane, which was first founded. This study showed that CaO2 had great potential for application in the treatment of algae-laden water.