Control of residual aluminum during coagulation in treatment of reservoir source water with high alkalinity
高碱度水库水混凝过程中残留铝控制

To minimize the residual aluminum (Al) levels in the effluent of a drinking water treatment plant (DWTP) with reservoirs source water of high alkalinity,the coagulation performances and the residual Al concentrations using three flocculants,with different basicity (B) and Alb content,were investigated under varibale Al doses and pH. The results indicate that the basicity and Alb content significantly affect coagulation behaviors.The removal efficiency of DOC and turbidity increases with elevated doses of AlCl3 (B=0), PACl-1 (B = 1.2), and PACl-2 (B = 2.2). The concentrations of total Al and dissolved Al are the lowest at Al doses of 1.5~2.0 mg/L for three flocculants.As for the PACl-2, which is prepared by this DWTP, both strategies of decreasing the basicity of flocculant and adjusting the solution pH to 7~7.5 are useful to enhance the coagulation performances and to decrease the residual Al levels. Moreover, the adjustment of flocculant preparation is preferred in the future application.