基于化学氧化和堆式热脱附技术修复污染土壤的环境足迹分析

Environmental footprint analysis of remediation of contaminated soil based on chemical oxidation and ex-situ thermal pile desorption technology

在“双碳”背景下,我国土壤修复工程使用技术类型不断向低碳、低能耗和绿色可持续修复技术转变,修复活动本身所产生的环境足迹受到了广泛关注和重视。采用环境足迹评估工具SiteWise^(TM)对重庆市某钢铁厂汞和多环芳烃污染场地化学氧化和堆式热脱附修复全过程的环境足迹进行了定量评价。结果表明:修复3483 m^(3)污染土壤,共排放温室气体(GHG)990.52 t,消耗能源1.57×10^(7) MJ,排放空气污染物4.94×10^(3) kg;GHG排放量、能源消耗量、空气污染物排放量占整个工程的比例在施工准备阶段为6.0%~9.1%,化学氧化阶段为43.6%~48.1%,化学氧化+堆式热脱附阶段为45.9%~47.5%;化学氧化+堆式热脱附技术相比化学氧化技术的环境影响更大,修复单方量污染土壤的GHG排放量、能源消耗量、空气污染物排放量为化学氧化技术的5.28~5.97倍。案例研究结果显示,材料消耗是对环境足迹贡献度最高的环节,其次为设备使用、运输、废物处理。

Under the background of"Peak Carbon Dioxide Emissions"and"Carbon Neutrality",the technology type of China's soil remediation projects is continuously shifting towards low-carbon,low-energy,green and sustainable remediation technologies.The environmental footprint of remediation activities has been widely noticed and evaluated.SiteWise^(TM),an environmental footprint assessment tool,was used to quantitatively assess the environmental footprint of the whole remediation process of a mercury and PAHs contaminated site in a steel plant in Chongqing.The results showed that the remediation of 3483 m^(3) of contaminated soil emitted a total of 990.52 t of greenhouse gases(GHGs),consumed 1.57×10^(7) MJ of energy and emitted 4.94×10^(3) kg of air pollutants.GHG emissions,energy consumption and air pollutant emissions at the construction preparation stage accounted for 6.0%-9.1%of the project,while those at the chemical oxidation stage accounted for 43.6%-48.1%.The GHG emissions,energy consumption and air pollutant emissions at the chemical oxidation+ex-situ thermal pile desorption stage accounted for 45.9%-47.5%.The chemical oxidation+ex-situ thermal pile desorption technology had a greater environmental impact compared to the chemical oxidation technology,and the environmental footprint for remediation of a single cubic volume of contaminated soil was about 5.28-5.97 times that of the chemical oxidation technology.The case study results showed that material consumption was the largest contributor to the environmental footprint,followed by equipment use,transport and residual handling.