Experimental Study on Treatment of Low Turbidity Water in Subsidence Area by Coagulation Technology

To solve the problem of poor coagulation effect of low turbidity water in a subsidence area of coal mine, the flocculation agents such as polymetric ferric chloride(PFC), polyaluminium sulfate(PAS), polyaluminium chloride(PAC) dosed alone and combined with the coagulant aids such as polyacrylamide(PAM) and activated silicic acid were conducted by the experiment. Results showed that the treatment effect of low turbidity water in a subsidence area of coal mine by dosing a flocculation agent alone was limited, when the dosage of PAC was 20 mg/L, the removal rate of turbidity was only 64.6%,while the dosage of PAS was 35 mg/L to reach the same effect. When the combined dosage was PAC of 20 mg/L and PAM of 0.20 mg/L, the effluent turbidity was less than l NTU and the removal rate could reach 89.3%, while the dosage of activated silicic acid instead of PAM was 25 mg/L to achieve the same result.