| With the rapid development of industry,the unreasonable industrial structure, extensive production methods and rise in agrochemical use that have made the pollution of sources water in our country become more and more serious,heavy metals pollution has already be a very outstanding problem in water pollution. The events of heavy metal pollution occur frequently and have brought serious influence and harm to people’ life,and at the same time,more and more pollution occur in the form of compound. Most of heavy metals in water body can not remove by the conventional treatment process in water plant, and treated water is difficult to meet drinking water standards. So find an emergency treatment of sudden heavy metals compound pollution in water source has important significance for us.In this thesis,taking the sudden compound pollution of heavy metals hexavalent Chromium + Cadmium(II) in drinking water source as the researching object. The main conelusions and result were listed as follows:Conventional treatment process, enhanced coagulation:(1)The removal efficiency of Cr6+ is the best by conventional coagulation process with FECL as coagulant. With pH of raw water from 6.5 to 7.5,the dosage of FECL from 16 to 26mg/L,under these conditions, the raw water with 0.17 mgL Cr6+ could be treated up to the national drinking water standard, with the residual concentration of Cr6+ was lower than 0.05 mg/L. And the removal efficiency was the best with the pH at 7 and the dosage at 22mg/L.(2)The removal efficiency of Cd is closely linked to pH value, with pH of water from 8.5 to 10 and the dosage of PAFC was 2.00mg/L, the raw water with 0.03 mgL Cd could be treated up to the national drinking water standard, with the residual concentration of Cd was lower than 0.005 mg/L.(3)To research the removal efficiency of hexavalent Chromium + Cadmium by segmentation process, The results showed that: Segmentation process could enhance the removal rate of hexavalent Chromium and Cadmium effectively;When the first paragraph of PFCL investment plus the amount was 22.0 mg/L, pH value was neutral;the second paragraph of PAFC dosage is 2. 0 mg/L and pH value was 8.5,the residual antimony hexavalent Chromium in the sedimentation effluent was 0.012mg/L and residual Cadmium concentration in the sedimentation effluent was 2.1ug/L and less than the standards for drinking water quality.Adsorption study of modified activated carbon:(1)The removal rate of hexavalent chromium was increasing with increase of dosage and adsorption time and with the loss of pH value. And also the pH and the dosage were more important.When the adsorption time was 120 min and pH at 5 and the dosage of modified activated carbon was 0.2g/L, removal rate of hexavalent chromium reached 88% for the raw water containing hexavalent chromium of 0.3mg/L. Under the same condition, removal rate of hexavalent chromium even could be as high as 97.33% when the pH was at 4.(2)The residual concentration was 4.1ug/L for the water containing Cadmium of 30ug/L with the dosage of modified activated carbon 0.1g/L and the adsorption time 10 min and the pH as the original.(3)For the Hexavalent Chromium + Cadmium Combined Pollution,simulated water treatment processes which was used in the waterworks with water-intake up,adding modified activated carbom in the raw water pump station. The modified activated carbom was mixed and adsorbed Cr(VI)with the hydraulic characteristic of supply pipe and time of flow. Adding the modified activated carbom another time when water was sent waterworks and initial water containing 30 ug/L(5 times) cadmium(Cd) and 0.3mg/L(5 times) hexavalent chromium(Cr) can be treated to satisfy the Chinese drinking water quality standard. |
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