Abstract:Microcystis aeruginosa was selected to explore the removal performance of coagulation by combining PAC with diatomite. The effects of PAC dosage, diatomite dosage, initial solution pH, concentration of humic acid on the removal of algae and turbidity were investigated. The zeta potential of the reaction system in coagulation processes was determined. Results showed that diatomite could effectively improve floc settle ability and algae removal. The Chl-a removal reached 96% and the residual turbidity was less than 0.9 NTU with 6mg/L PAC and 30mg/L diatomite when initial solution pH ranged from 7 ~ 8. The presence of humic acid in water obviously inhibited the coagulation removal of Microcystis aeruginosa. When the concentration of humic acid was higher than 1.0mg/L, the algae removal declined sharply and the residual turbidity increased; the addition of diatomite would mitigate the negative effect to some extent.