Remediation Of Cadmium Contaminated Soils In Sichuan Province

With the rapid development of modern industry,agriculture and the acceleration of urban process?the heavy metal soil pollution has become a worldwide environmental problem,the pollution of cadmium in our country is the most prominent,which has aroused widespread concern.In this paper,the present situation,harm,characteristics and common repair techniques of Cd-contaminated soil were reviewed.Based on the extensive access to information and on-site research,the process condition of chemical leaching and phytoremediation on Cd-contaminated soil in a certain area of Sichuan were studied.The related process of ectopic chemical repair was put forward,and the process design was carried out.Mainly formed the following results.1.Study on the process conditions of chemical repair:The effects of low molecular weight organic acids(acetic acid,citric acid,oxalic acid and tartaric acid)on the removal of cadmium in the tested soil were studied by using the experimental method of oscillating and washing soil.The types of chemical eluents used were determined according to the experimental results.The single experiment was used to explore the specific experimental conditions and the effects of oscillation time,solid-liquid ratio and organic acid concentration on the Cd-removal rate were investigated by orthogonal experiment.The variance analysis of orthogonal experiment was carried out by using SPSS software to obtain the best Cd-removal experimental conditions.Using soil column elution experiment with hydrochloric acid,EDTA,citric acid,tartaric acid and its formula to repair the tested soil obtained a 72-hour leaching curve,which can help to study the effect of cadmium removal under the action of acid and artificial chelating agent.2.Study on the process conditions of phytoremediation:Use heavy Cd-contaminated soil as research object.solanum as experimental plants,and add a dose of citric acid and EDTA to compare the effect of activator on Cd uptake by plants.and the same time to research the effects on the PH value and cadmium content in root soil.3.Based on the previous research results,the related technological processes of ectopic chemical repair were put forward according to the principle of scientificity,feasibility,safety and local conditions.The remediation treatment of Cd-contaminated soil was carried out by excavation and stacking,wet sieving,extraction reaction,sludge concentration and pressure filtration,net soil filtration,waste collection and treatment,and put forward the specific process of producing sewage and sludge in the reaction process as well.