Studies On Removal Of Heavy Metals As(Ⅲ),Hg(Ⅱ) From Micro-polluted Waters By Enhanced Coagulation

People pay more and more attention on drinking water's security problem. Especially aims in the micro pollution source of drinking water of micro heavy metal elimination, already became one of hot spots the people pay attention on. The study imitated water purification plants to carry on enhanced coagulation treatments on micro-polluted raw water,analyzing water quality parameters and full-scale experiment study including PFS,PAC,PFSS inorder to select the fittest coagulation for micro-polluted raw water.The removal of heavy metal arsenic from micro-polluted waters by enhanced coagulation was studied using polyferric sulfate (PFS), poly aluminum chloride (PAC) and poly ferric metasilicate (PFSS) as the coagulant. The effects of the pH, the dosage of PFS, the concentration of arsenic ion and the turbidity of raw water on the arsenic removal were investigated. The experimental results shown that, the removal rate of arsenic treated with PFSS was higher than that of with PFS and PAC, under the condition of pH6-8 and dosage of PFSS 0.065mmol/L, the residual concentration of arsenic in post-treated water was lower than 0.01 mg/L for raw water with initial concentration of arsenic 0.1 mg/L.When the concentration of arsenic was higher than 0.01 mg/L in water, arsenic can also be removed under the condition of increasing the dosage of PFSS. PFS may also remove As (III) in the source water effectively, but the elimination rate is lower than PFSS, elimination rate of PAC is the lowest.The removal of heavy metal Mercury from micro-polluted waters by enhanced coagulation was studied using PAC as the coagulant.The effects the adsorption time, pH, the adsorbent dosages, the dosage of sulfur,PAC, the concentration of Mercury ion on the Mercury removal were investigated.The experimental results shown that, under the condition of pH 8.5,the residual concentration of Mercury was lower than lug/L when the Mercury concentration 5-7ug/L in raw water. The results meet the water quality standards for drinking water sources.The experiment indicated that, enhanced coagulation is a way to enhance the output water.On the based routine treatment aechnique, enhanced coagulation is efficient way to treat the micro-polluted raw water.