Study On The Remediation And Resource Utilization Of Lead Arsenic Composite Heavy Metal Contaminated Soil

This article mainly summarizes the situation of heavy metal contaminated soil at home and abroad and the research progress of solidification and stabilization,analyzes the characteristics of contaminated soil,explores the optimal material combination and material ratio for solidification and stabilization treatment of lead arsenic composite heavy metal contaminated soil,and on this basis,recycles the contaminated soil to produce polluted soil block building materials,And according to national regulations and standards,the best sample preparation ratio for strength and environmental evaluation is selected to achieve the goal of resource utilization of heavy metal contaminated soil.We plan to select 7 single remediation materials for stabilizing and repairing lead arsenic contaminated soil,compare the results,and select materials with good remediation effects for binary composite material remediation experiments.A comprehensive comparative study was conducted on the differences in stabilization effects and changes in soil heavy metal forms of different remediation materials,and a stabilization remediation material suitable for lead arsenic heavy metal contaminated soil was selected.After stabilization,lead and arsenic contaminated soil is treated as a resource,using contaminated soil as the main filling material,cement as the cementitious material,and river sand as the aggregate to prepare ordinary concrete small blocks.Exploring the effects of factors such as cement type,contaminated soil content,and curing age on the performance of masonry blocks,and selecting the optimal ratio through experimental research.Conduct freeze-thaw cycle tests on the blocks to investigate the impact of freeze-thaw cycle times on the compressive strength and toxic leaching concentration of the blocks,and evaluate the frost resistance and long-term durability of the blocks.The seven selected stabilizing remediation materials have good remediation effects for arsenic pollution(quicklime)and lead pollution(potassium dihydrogen phosphate),while potassium dihydrogen phosphate can aggravate the release of arsenic ions during soil cultivation.Through testing the changes in heavy metal forms of polluted soil before and after remediation,it was found that the exchangeable form of arsenic in the soil was relatively large,and the carbonate binding form of lead was relatively large,which couldpotentially affect the ecological environment and groundwater safety of the park.Based on the test results,quicklime and ferrous sulfate were selected as co stabilizing materials(1:1,total feed ratio of 5%).After 7 days of stabilization and remediation,soil arsenic The lead leaching concentrations are 0.039 and 0.034 mg/L,both of which can meet the Class IV standard for groundwater in the national standard.After repair,the contaminated soil blocks can meet the requirements of GB/T8239-2014 "Ordinary Concrete Small Blocks" for sample preparation raw materials and processes,and have good mechanical properties.The compressive strength can meet the requirements of MU5,MU7.5,MU10,and MU15 standards.The toxicity of Pb and As ions in the water environment and acidic environment is lower than the concentration limit of heavy metals in the leaching solution specified in the Identification Standard for Hazardous Wastes-Identification of Leaching Toxicity(GB 5085.3-2007),and the toxic leaching of Portland cement blocks is generally less than that of sulphoaluminate cement blocks,and both strength and toxicity leaching can withstand the effect of freeze-thaw cycles.On the basis of domestic and international practice and research,this article takes the industrial land soil polluted by heavy metals such as lead and arsenic in Yaojiagang Chemical Park,Yichang City,Hubei Province as the research object.Stable remediation materials and composite ratio materials are selected to conduct stabilization tests on lead and arsenic heavy metal contaminated soil.The differences in stabilization effects and changes in soil heavy metal forms of different remediation materials are studied,and stabilization materials suitable for the remediation of lead and arsenic contaminated soil are selected,Utilize the stabilized contaminated soil resources and test the various performance indicators of the material to explore its practical applicability.It can play a certain guiding role in the treatment and utilization of actual lead and arsenic contaminated soil.