Studies On Removal Of Heavy Metals(Cd(â…¡), Pb(â…¡) And Cr(â…¥)) From Micro-polluted Waters By Enhanced Coagulation

Our dinking water are mainly rivers,lakes and reservoirs.By means of monitoring and analysis,we know that these water have been polluted by some heavy metals.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 Cadmium from micro-polluted waters by enhanced coagulation was studied using polyferric sulfate(PFS) as the coagulant.The effects of the pH, the dosage of PFS,the concentration of Cadmium ion and the turbidity of raw water on the Cadmium removal were investigated.The experimental results shown that,under the condition of the pH≥9,the residual concentration of Cadmium was lower than 0.005mg/L when the dosage of PFS is 3.75mg/L and the Cadmium concentration 0.1mg/L in water.When the concentration of Cadmium was higher than 0.1mg/L in water,Cadmium can also be removed under the condition of increasing the dosage of PFS.The removal of heavy metal Lead from micro-polluted waters by enhanced coagulation was studied using polyferric sulfate(PFS) as the coagulant.The effects of the pH,the dosage of PFS, the concentration of Lead ion and the turbidity of raw water on the Lead removal were investigated.The experimental results shown that,under the condition of pH＞6,the residual concentration of Lead was lower than 0.01mg/L when the dosage of PFS is 3.00mg/L and the Lead concentration 0.1mg/L in raw water.When the concentration of Lead was higher than 0.1mg/L in raw water,Lead can also be removed under the condition of increasing the dosage of PFS.The removal of heavy metal Chromium from micro-polluted waters by enhanced coagulation was studied using Polyferric Silicate Sulfate(PFSS) as the coagulant.The effects of the dosage of reductant and PFSS,the pH and the concentration of Chromium ion of raw water on the Chromium removal were investigated.The experimental results shown that,under the condition of the pH=7 and the dosage of reductant being theoretical value,the residual concentration of Chromium was lower than 0.05mg/L when the dosage of PFSS is 0.75mg/L and the Chromium concentration 0.865mg/L in water.When the concentration of Chromium was higher then 0.865mg/L in water,Chromium can also be removed under the condition of increasing the dosage of PFSS.By comparing the tests of the coagulants of PAC,PFS and PFSS,we can see that in the same dosage,PFSS can make the residual concentration of heavy metal before filtration less than the other two agents.Therefore,the coagulation properties of PFSS is better than the other two.The effect of complex pollution on removal of heavy metal is little,but we should determine the dosage of coagulant according to water qualityThe 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.