煤制气遗留场地修复后再开发安全利用评估

随着社会经济发展和城镇建设加快，原有土地使用性质发生改变，其中工业遗留场地的污染物可能对土壤和地下水造成污染。但由于修复技术的局限性以及水文地质的复杂性，修复后场地仍然可能存在不利于安全利用的物质残留或异味等风险隐患。为了进一步完善污染地块修复后再利用评价方法，对可能存在的污染风险进行识别，现选取了一块经原位化学氧化和原位热脱附修复后的煤制气遗留场地，从感官可接受度、工程安全性和环境质量3个方面系统全面地评估场地修复后再开发安全利用的适宜性。评估结果表明，在感官可接受度方面，硫化氢的质量浓度是其嗅阈值的1.6～4.8倍，氨、甲苯和三氯甲烷质量浓度均低于其嗅阈值，臭气浓度低于检出限，感官可接受程度高；在工程安全性方面，地块经原位热脱附和原位化学氧化修复后，基本土性参数、压缩系数和渗透系数未发生明显改变，但是原位化学氧化区MH2点位浅层土壤硫酸盐残留浓度达到中腐蚀等级；在环境质量方面，修复后场地土壤中和地下水中污染物的质量浓度均低于相应评价标准限值。在场地后期开发建设中，应进一步对土壤中硫化氢气体和土壤硫酸盐腐蚀性进行监测，确保地块安全开发利用。研究结果可为其他污染地块修复后的再利用提供有效、科学的指导。

Safety Assessment on Reutilization of Brownfield Sites Left by Coal-based Synthetic Natural Gas After Remediation

With the development of society and economy and the acceleration of urban construction，the using property of the original land has changed. The pollutants in the sites left by industries may cause the pollution of soil and groundwater. However，due to the limitations of remediation technology and the complexity of hydrogeology，it may still have hidden risks such as residual substances or odors that are not conducive to safe use of the restored site. In order to further improve the reuse evaluation method of contaminated sites after remediation and identify possible pollution risks，a brownfield site left by coal based synthetic natural gas and remediated by in situ chemical oxidation and in situ thermal desorption was selected. The suitability of the site for safety utilization after remediation was systematically and comprehensively evaluated from three aspects of sensory acceptability，engineering safety and environmental quality. The evaluation results showed that in terms of sensory acceptability，the mass concentration of hydrogen sulfide was 1.6~4.8 times higher than the odor threshold，and the mass concentrations of ammonia，toluene and trichloromethane were all lower than the odor threshold. Additionally，the odor concentration was lower than the detection limit. The sensory acceptability was high. In terms of engineering safety，the basic soil property parameters，compression coefficient and permeability coefficient did not change significantly after in situ thermal desorption and in situ chemical oxidation remediation. However，the residual sulfate concentration in the shallow soil of MH2 in the in-situ chemical oxidation zone reached medium corrosion level. In terms of environmental quality，the mass concentrations of pollutants in the soil and groundwater of the restored site were lower than the corresponding evaluation standard. In the later development and construction of the site，hydrogen sulfide gas and corrosiveness in the soil should be further monitored to ensure the safe development and utilization of the site. The research results can provide an effective and scientific guidance for the reuse of other contaminated sites after remediation.