加热对有机-重金属复合污染土壤影响研究

Effect of Heating on Organic Pollutants and Heavy Metals Polluted Soil

该文考察了加热温度和加热时间对废旧电器拆解场地的有机-重金属复合污染土壤有机污染物浓度、重金属浸出浓度、重金属弱酸提取态含量和土壤理化性质的影响。加热温度试验结果表明,300℃以上加热6 h后,土壤有机污染物含量均达到建设用地第一类用地要求,但镉和镍的浸出浓度均超过了地下水Ⅳ类水质标准。400℃以上加热6 h后,土壤重金属浸出浓度均达到地下水Ⅳ类水质标准,但土壤理化性质变化较大,综合考虑加热温度对土壤污染物含量和理化性质的影响,300℃是最佳的加热温度。300℃下加热时间试验结果表明,随着加热时间的增加,镉和镍的浸出浓度逐渐下降,但加热至18 h后,镉的浸出浓度依然超标,而土壤理化性质变化较大,综合考虑加热时间对土壤理化性质影响,300℃下的加热时间需要控制在12 h以内。后续根据需要再结合固化/稳定化技术处理可使土壤满足使用要求。

The effects of heating temperature and heating time on the concentration of organic pollutants,the leaching concentration of heavy metals,the content of weak acid extraction state of heavy metals and the physical and chemical properties of soil from the waste electrical appliances dismantling site were investigated.The heating temperature test results showed that after heating above 300℃for 6 hours,the content of soil organic pollutants met the requirements of class I land for construction land,but the leaching concentration of nickel and cadmium exceeded the classⅣwater quality of groundwater.After heating above 400℃for 6 hours,the soil heavy metal leaching concentration met the classⅣwater quality standard of groundwater,but it had a great impact on the physical and chemical properties of soil.Considering the impact of heating temperature on the content of soil pollutants and physicochemical properties,300℃was the best heating temperature.The results of heating time test under 300℃showed that with the increasing of heating time,the leaching concentration of nickel and cadmium decreased,however,even heated for 18 h,the leaching concentration of cadmium still exceeded the standard,while the properties of soil changed a lot.Considering the impact of heating time on soil physical and chemical properties,the heating time of heating at 300℃needed to be controlled within 12 hours.The subsequent solidification/stabilization treatment may make the soil meet the use requirements.