| The types of soil pollution in China are complex and diverse,mainly including heavy metal pollution sites,persistent organic pollution sites,organic pollution sites and electronic waste pollution sites.With the continuous development of modern industry in China,the problem of site pollution is becoming more and more serious.At present,there are as many as one million sites polluted by heavy metals in China.In this paper,the performance of different materials and site remediation were studied to solve the problem of arsenic and lead compound pollution in a chemical plant of Shaoguan.The main research contents are as follows:?1?The soil polluted by arsenic and lead in a chemical plant of Shaoguan was sampled.The results showed that the content of arsenic and lead in the plant soil exceeded the standard seriously,and the distribution was uneven.The toxic leaching content of arsenic in topsoil is as high as 0.19 mg/L,and that of lead is as high as 0.14mg/L.The soil is acidic and arsenic and lead pollution is mainly concentrated in the topsoil?0-50 cm?.?2?The effects of different materials on the repair of arsenic and lead were compared in the laboratory.The results showed that after 24 hours treatment with 3%Mg?OH?2-FeS or 3%n ZVI,the content of lead reached the standard,but the content of arsenic was not up to the standard.2%Fe-Mn nanoparticles+0.9%Cao treated arsenic and lead soil for 24 hours,the toxic leaching content of arsenic and lead reached the standard.?3?Furthermore,the effects of composite materials,which were made of iron oxide,manganese dioxide and magnesium hydroxide,on the treatment of arsenic and lead were studied.The results show that the material[Fe-Mn-Mg?OH?2]prepared by mixing Fe2O3:16.7%;Mn O2:50%;Mg?OH?2:33.3%]has a good curing effect on arsenic and lead.The optimal dosage of the material is 3%,and the toxic leaching concentration of arsenic and lead are 0.009 mg·L-1and 0.008 mg·L-1,respectively.The curing rates of arsenic and lead are 95.6%and 92.6%respectively.Through the characterization of XPS,FTIR and XRD,it was found that FeOOH was the key component in the treatment of arsenic and lead.As?III?in the soil is oxidized by Mn O2to As?V?,and As?V?is coordinated with FeOOH to form refractory compounds,while lead in the soil reacts with magnesium hydroxide to form lead hydroxide precipitation.?4?We applied Fe-Mn-Mg?OH?2to the site restoration project.The results of field remediation test showed that the in-situ remediation was carried out according to the ratio of Fe-Mn-Mg?OH?2material to soil mass of 3%.After remediation,the soil samples were tested and found that the toxic leaching content of arsenic and lead in all soil samples were up to the standard,and the long-term monitoring of arsenic and lead concentration and pH showed that the arsenic and lead content were up to the standard for a long time,and the pH did not change much.In this paper,the basic laboratory experiments and site remediation experiments are fully studied,and the mechanism of removing arsenic and lead from soil by the best remediation materials is explored,which provides a reference for the resource-based treatment of arsenic and lead in arsenic and lead pollution treatment industry in the future. |
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