土壤原位修复技术研究与应用进展

A review on the Study on Practice of Soil Remediation in situ

土壤原位修复技术是指不经挖掘,直接在污染场地就地修复污染土壤的土壤修复技术,具有投资低,对周边环境影响小的特点,是土壤修复的研究热点。土壤原位修复技术主要有淋洗,气相抽提(SVE),多相抽提(MPVE),气相喷射(IAS),生物降解,原位化学氧化(ISCO),原位化学还原,污染物固定,植物修复等。淋洗法主要用于治理高渗透性土壤中的重金属和难挥发降解的有机物。土壤气相抽提和喷射技术适用于处理土壤中的易挥发污染物,并有常与加热技术,生物处理技术等联用,可以起到促进污染物挥发,增氧促分解的作用。多相抽提法主要用于治理存在大量非水相流体的污染场地,可将土壤中有机相污染物直接抽出。生物降解有生物好氧降解、生物厌氧降解、生物还原降解多种,降解方式由污染物种类和地质条件决定。化学方法可将污染物氧化或还原为低毒无毒物质,周期一般较短。固定污染物可以直接加入药剂反应生成沉淀,也可制造合适条件使微生物生成可沉淀重金属的离子。植物修复主要用于富集重金属,成本低廉,但富集了重金属的植物体的有效利用尚待进一步研究。土壤原位修复需要因地制宜,灵活结合工期、污染情况、地质条件、地面设施等,得出最经济实用的修复方法,并在辅助提高技术上展开更多研究,使原位修复技术更经济有效。

Soil remediation in situ treats the contaminated soil without excavation. It has the advantages of low investment and has small impact on the surrounding. It is a hot point in soil remediation. In site soil remediation technology mainly includes flushing, soil vapor extraction （SVE）, multiphase vacuum extraction（MPVE）, air sparging （IAS）, biological degradation, in situ chemical oxidation（ISCO） and in situ chemical reduction, immobilization and phytoremediation etc.. Flushing is mainly used for organic compounds with low solubility and heavy metals in soil of high permeability. Soil vapor extraction and air sparging is suitable for the treatment of volatile pollutants in soil, and are often associated with heating and biological treatment, promoting volatilization and increasing the content of oxygen to promote decomposition. Multiphase vacuum extraction is mainly used for sites with mass of NAPL, can extract organic phase pollutants directly. Biodegradation includes aerobic degradation, anaerobic degradation and reduction degradation, the contaminants and geological conditions decides which one can be used. Chemical treatment can make pollutant oxidated or reduced to low toxic or non-toxic substances, with a shorter duration. Immobilization can add treatments directly and generate precipitation. Microorganisms can generate ions in certain conditions that can precipitate heavy metals ions also. Phytoremediation is mainly used for the accumulation of heavy metals with less cost. But further studied is needed on the effective utilization of plants that accumulated with heavy metals. For in situ soil remediation, in order to be more economical and practical, the most appropriate technology should be selected according to the schedule, contaminant, geological condition, ground facilities. And more research is needed on the related technology to make in situ remediation more economical and effective.