Algae-removal Treatment of A-F/PDM Composite Coagulants to Summer Taihu Lake Algae-rich Water under Prechlorination Process

摘要

The series of stable A-F/PDM composite coagulants prepared by combining polydiallyldimethylammonium chloride (PDM) with the composite (A-F) of aluminum sulfate (AS) and ferric chloride (FeCl_3) were used to research the algae-removal efficiencies to summer Taihu Lake algae-rich water under prechlorination process. The composite coagulants were tested by jar tests for the effects of mass percents (5%~20%) and intrinsic viscosity values (0.55~3.99 dL/g) of PDM on algae-removal efficiencies. For water with algae content of 6.14×10~4 cells/mL, the algae-removal rates of 90.9% and 94.0%~96.3% could be realized by using A-F and A-F/PDM (0.55/5%~3.99/20%) with dosages of 5.60 mg/L and 4.81~3.01 mg/L, respectively, when 2 NTU residual turbidity of effluent water after sedimentation was required. Therefore, using A-F/PDM composite coagulants could enhance evidently the algae-removal efficiency of A-F to summer Taihu Lake algae-rich water. Compared with using A-F solely, the dosages of A-F in composite coagulants were saved when the residual turbidities were required in same level.