Abstract:Five typical bloom algae species (Chlorella, Chlamydomonas, Cyclotella, Synedra, Glenodinium) in the source water of villages and towns in the Three Gorges Reservoir area were selected as materials. The effect of different doses of PAC (poly aluminum chloride) on the removal of these algae cells (chlorophylla and turbidity), as well as the differences in the structure and morphology of the flocs after coagulation and sedimentation, were compared, and the appropriate PAC dosage for removal the coagulation of typical algae species was screened. The results showed that: (1) the morphological structure of the selected algae species in the experiment are obviously different, Synedra has a long linear structure, Cyclotella has a short cylindrical structure, and Chlorella, Chlamydomonas and Glenodinium are spherical or elliptical. Cells of Synedra and Glenodinium are relatively the largest. (2) The PAC removal efficiency of Synedra and Glenodinium was the best, followed by Chlorella and Chlamydomonas, while the good PAC removal efficiency of Cyclotella was relatively difficult to achieve. The removal efficiency of PAC is related to the morphological characteristics of algae. (3) Synedra and Glenodinium were prone to form large and dense flocs. Chlorella and Chlamydomonas formed relatively small flocs, and Cyclotella has the weakest ability to form flocs. (4) The appropriate dosage of PAC was 15-80 mg/L for Synedra and Glenodinium, 15-50 mg/L for Chlorella, 15-65 mg/L for Chlamydomonas and 50-80 mg/L for Cyclotella. Within the appropriate PAC dosing range, the removal rates of Chla and turbidity of each algae reached 81%-97% and 76%-97%, respectively. It can be seen that the PAC coagulation sedimentation method can be used to remove 5 typical blooms and algae species in the water source water of villages and towns in the Three Gorges Reservoir area, but the appropriate dosage of each algae species is different. Appropriate amount of PAC can effectively reduce the Chla and turbidity in each algae liquid.