纳米铁原位注入技术对六价铬污染地下水的修复

纳米零价铁原位注入是六价铬污染地下水的有效修复技术之一。为验证其场地修复效果,在北京某电镀厂搬迁后的遗留六价铬污染场地,现场制备纳米铁并通过原位注入对场地内六价铬污染地下水进行原位修复现场中试研究。选取6 m×6 m实验场地,在地下水中六价铬污染浓度最高为2 mg·L-1的中心点设置注射井并在四周设置4口监测井。实验结果表明,原位注入纳米铁药剂具有良好修复效果,修复后该实验场地范围内地下水中六价铬浓度均低于地下水质量Ⅳ类标准0.1 mg·L-1,注射井中六价铬还原率达到99%。通过对注射井及监测井地下水中pH、溶解氧、氧化还原电位等检测指标进行跟踪监测和相关性分析,发现氧化还原电位与污染物浓度变化相关性最强,可以作为污染物变化的表征因子。该中试研究结果对于六价铬污染地下水的原位修复具有重要的参考价值。

Remediation of chromium (VI) contaminated groundwater by in-situ injection of nanoscale zero valent iron

In-situ injection of nanoscale zero valent iron (nZVI) is an effective technology for the remediation of chromium (VI) (Cr(Ⅵ)) contaminated groundwater. A field pilot test was carried out in a Cr(Ⅵ) contaminated site where the electroplate factory located in Beijing. One injection well surrounded with four monitoring wells was installed in the central of the test site (6 m×6 m). Before test, the highest Cr(Ⅵ) concentration of the groundwater in the injection well is up to 2 mg·L-1. The monitoring data showed that Cr(Ⅵ) could be effectively removed by injection of nZVI prepared in the field. After 5 days, the concentrations of Cr(Ⅵ) in the test site decreased to below 0.1 mg·L-1,and the removal efficiency of Cr(Ⅵ) was up to 99%. Compared with pH and DO, a better linear relationship between ORP and Cr(Ⅵ) concentration was found. The pilot scale test proved that the technology of in-situ injection of nZVI was of great value in the remediation of Cr(Ⅵ) contaminated groundwater.