Experimental Study on Removal Efficiencies of Water Turbidity by Ultrafiltration Membranes and Coagulation

[Objective] The study aimed to discuss the removal effect on the low turbidity by 2 methods of ultrafiltration membranes and coagulation.[Method] The experimental raw water was made by oneself to simulate the low turbidity in the micro-pollution source water turbidity range.The raw water with 3 turbidity of 5,10,15 NTU was set up and 2 methods of ultrafiltration membranes and poly-aluminum chloride(PAC)coagulation were selected to conduct the test of the treating effects on 3 low turbidity resp.[Result] No matter how much water turbidity was,the effluent turbidity by the ultrafiltration membrane was below 1 NTU and was stable.When PAC was used to remove the kaolin turbidity,the best pH value was around 8,that is PAC coagulation could get best effect under the neutral and weak alkali conditions.When the turbidity of raw water was 5 NTU,the optimal dosage of PAC was 7.5 mg/L;when the turbidity of raw water was10 and 15 NTU,the optimal dosage was 10 and 15 mg/L,with the removal rate of 74.2% and over 80%,resp.[Conclusion] It was suggested to use the coagulation-ultrafiltration combination process,which ether could avoid the pollution of high turbidity on the membrane components and reduce the pollution membrane pollution rate,but also could guarantee the outlet water quality.