重金属污染土壤稳定/固化修复技术研究进展

Recent advance in solidification/stabilization technology for the remediation of heavy metals-contaminated soil.

修复重金属污染土壤一直是国际上的难点和热点研究课题.目前常用的污染场地修复技术主要包括挖掘、稳定/固化(solidification/stabilization,S/S)、化学淋洗、气提、热处理、生物修复等.本文在参考美国环境保护署(EPA)、英国环境署的S/S技术规范、国内外发明专利基础上,对S/S的概念、国内外发展现状及今后的发展方向进行了系统论述.固定化技术通过把污染物囊封入惰性基材中,或在污染物外面加上低渗透性的材料,来减少污染物暴露的淋滤面积以达到限制污染物迁移的目的.稳定化技术是从改变污染物的有效性出发,将污染物转化为不易溶解、迁移能力或毒性更小的形式.S/S技术包括:水泥固化、石灰火山灰固化、塑性材料包容固化、玻璃化技术、药剂稳定化.在稳定化技术中,加入药剂的目的是改变土壤的物理、化学性质,通过pH控制技术、氧化还原电势技术、沉淀技术、吸附技术、离子交换技术等改变重金属在土壤中的存在状态,从而降低其生物有效性和迁移性.本文还论述了S/S修复效果评价方法,并指出需加强S/S技术中的分子键合技术、土聚合物以及我国的S/S技术导则制定等工作.

Remediation of heavy metals-contaminated soil is still a difficulty and a hotspot of international research projects.At present,the technologies commonly adopted for the remediation of contaminated sites mainly include excavation,solidification/stabilization（S/S）,soil washing,soil vapor extraction（SVE）,thermal treatment,and bioremediation.Based on the S/S technical guidelines of Unite State Environmental Protection Agency（EPA） and United Kingdom Environment Agency（EA） and the domestic and foreign patents,this paper introduced the concepts of S/S and its development status at home and abroad,and discussed its future development directions.Solidification refers to a process that binds contaminated media with a reagent,changing the media＇s physical properties via increasing its compressive strength,decreasing its permeability,and encapsulating the contaminants to form a solid material.Stabilization refers to the process that involves a chemical reaction which reduces the leachability of a waste,chemically immobilizes the waste and reduces its solubility,making the waste become less harmful or less mobile.S/S technology includes cement solidification,lime pozzolanic solidification,plastic materials stabilization,vitrification,and regent-based stabilization.Stabilization（or immobilization） treatment processes convert contaminants to less mobile forms through chemical or thermal interactions.In stabilization technology,the aim of adding agents is to change the soil physical and chemical properties through pH control technology,redox potential technology,precipitation techniques,adsorption technology,and ion-exchange technology that change the existing forms of heavy metals in soil,and thus,reduce the heavy metals bioavailability and mobility.This review also discussed the S/S evaluation methods,highlighted the need to enhance S/S technology in the molecular bonding,soil polymers,and formulation of China＇s S/S technical guidelines.