不同淋洗剂和淋洗条件下重金属污染土壤淋洗修复研究进展

Advance in washing technology for remediation of heavy metal contaminated soils: effects of eluants and washing conditions

土壤淋洗修复技术作为一种快速有效的污染土壤治理技术越来越受到重视,其适用于受高浓度重金属污染的土壤。着重阐述了近年来不同淋洗剂以及淋洗条件对重金属污染土壤的修复效果,并综述了不同淋洗剂对不同形态重金属淋洗效果,讨论了淋出液的处理及淋洗剂的回收,同时介绍了国内外重金属污染土壤淋洗修复工程实践。指出在众多淋洗剂中以天然有机酸因低生态毒性和高降解性而最具有研究前景。应综合考虑各影响因素,选择最优条件达到最好的修复效果,而在选择淋洗剂时,也应考虑其本身的生物降解性和生态毒性。无论哪种淋洗剂,均以可交换态和碳酸盐结合态形式存在的重金属容易被淋出,而相对稳定的残渣态较难去除。本文最后提出了研究中存在的问题,并展望了今后淋洗技术的研究方向,旨在为研究重金属污染土壤修复技术提供理论依据。

As an effective technology for rapid remediation of soils highly contaminated with heavy metals, soil washing has increasingly received attention in recent years. This paper provides an overview on recent advances in research on the efficacy of various eluants and washing conditions associated with the washing technology for remediation of soils contaminated with heavy metals. Effect of eluants on washing efficiency of various fractions of heavy metals in soils, and the treatment and reuse of the spent washing solutions were discussed. How to treat and recycle waste washing solutions after soil being washed was discussed as well. Among the eluants ap- plied in the global remediation practices, natural organic acids have been recognized as the most promising chemicals for soil washing, because of their low ecotoxicity and high biodegradability which have been consid- ered as important criteria for eluants selection. Regardless of the eluant type, heavy metals in exchangeable and carbonate fraction are most likely to be removed, whereas those in residual fraction are relatively stable and difficult to be removed with soil washing. Directions for further research were also proposed to advance soil washing technology.