燃气热脱附技术土壤修复效果及影响因素

Soil remediation effect and influencing factors of gas thermal desorption technology

以某退役煤气厂土壤中苯、萘和TPH为目标污染物,基于燃气热脱附技术开展了工程化的修复。当加热井间距为2.5 m,加热56 d,土壤可升至目标温度150℃,土壤中苯、萘和TPH的去除率分别为100%、92%和95%,均达到目标修复值。研究发现,沸点越低,污染物去除率峰值出现越早;沸点越高,污染物去除率峰值出现越晚。停止加热后,测温点距离加热井越近,温度升至峰值的时间越早;测温点距离加热井越远,温度升至峰值的时间越晚,温度呈现出明显的滞后现象。通过能耗分析,每处理1.0 m^(3)污染土壤约消耗天然气82.6 m^(3),电量40.5 kW·h。本研究结果可为利用燃气热脱附技术进行土壤修复工程提供参考。

Taking benzene,naphthalene and TPH in the soil of a de-commissioned gas plant as the target pollutants,the engineering remediation was carried out based on gas thermal desorption technology in this study.The temperature of the studied soil reached 150℃ after 56 days of heating with the heating wells placed 2.5 m from each other.Accordingly,the removal percentages of benzene,naphthalene and TPH reached 100%,92%and 95%,respectively,which all met the remediation targets.During the heating process,the time required to reach peak removal percentages for different pollutants was inversely correlated to the boiling points of the pollutants.In terms of the temporal-spatial variation of the temperatures,after the heating was stopped,it has been observed that the time required to reach peak temperature was inversely correlated to the distance from the heating well,and there was an apparent hysteresis effect on temperature profile.A cost-effectiveness study revealed that 82.6 m^(3) of natural gas and 40.5 kW·h of electricity was needed to treat each cubic meter of polluted soil.This study can provide reference for soil remediation by gas thermal desorption technology.