水泥和活性炭对多环芳烃污染土壤固化稳定化效果的影响

Effect of cement and activated carbon on solidification/stabilization of PAHs contaminated soil

固化稳定化技术由于处理费用低、操作简单易行,是污染场地修复常用的技术。评估了水泥和活性炭固化稳定化多环芳烃(PAHs)污染土壤的浸出行为和无侧限抗压强度(UCS)。PAHs污染土壤采用非酸性降水、酸性降水和卫生填埋场共处置3种方法分别浸出时,浸出液中PAHs的浓度分别为2.53、2.74和3.88μg/L;当水泥添加量为土壤质量的20%时,3种方法浸出液中PAHs的浓度分别为8.99、10.12和10.99μg/L;水泥固化稳定化会增加污染土壤中PAHs的浸出浓度,不同情景下PAHs的浸出浓度表现为卫生填埋场共处置>酸性降水>非酸性降水。当水泥添加量为土壤质量的20%,活性炭添加量为土壤质量的1%时,PAHs的浸出浓度为0.99μg/L,活性炭的加入可有效降低浸出液中PAHs的浓度。当水泥添加量分别为土壤质量的10%、20%和30%时,固化稳定化产物28 d的UCS分别为1.82、5.95和12.06 MPa,UCS随着水泥添加量的增多而增大;水泥添加量为土壤质量的20%,活性炭添加量不大于土壤质量的2%时,其UCS与不加活性炭时相当。

As a low cost and easy to operate technology, the solidification/stabilization is widely used for remediating contaminated sites. PAHs leachability and unconfined compressive strength（ UCS） of cement-based solidified/stabilized materials with or without activated carbon were evaluated. When the contaminated soil was leached under three scenarios of neutral precipitation, acid precipitation, and co-disposal, the leaching concentrations of PAHs were 2. 53,2. 74 and 3. 88 μg/L,respectively. After treated by cement of 20% soil weight,the leaching concentrations of PAHs were 8. 99,10. 12 and 10. 99 μg/L,respectively under the three scenarios. The leachability of PAHs increased when contaminated soil was solidified/stabilized by cement. PAHs concentrations in leachates were in the order of co-disposal scenario〉 acid-precipitation scenario 〉neutralprecipitation scenario. When the contaminated soil was treated by 20% cement and 1% activated carbon of soil weight,the leaching concentrations of PAHs was 0. 99 μg/L; the addition of activated carbon can significantly lower PAHs concentrations in leachates. 28 d UCS of solidified/stabilized materials was 1. 82,5. 95 and 12. 06 MPa when the contaminated soil was treated by cement of 10%,20% and 30% of soil weight,respectively. UCS of solidified/stabilized materials increased with the adding amounts of cement. When the contaminated soil was treated by 20% cement,UCS of solidified/stabilized materials was not affected by the amount of activated carbon when adding no more than 2% of soil weight.