抽出-处理技术抽出污染地下水——抽出效率及抽出终点

针对抽出-处理技术修复污染地下水过程中抽水井抽出效率随时间逐渐降低、抽出-处理技术运行终点（以下简称"抽出终点"）难以确定的问题，提出通过评估抽水井抽出效率，以分段、多次优化抽水方案提高抽出效率、降低修复成本、减少修复时间为工作思路，利用层次分析法和专家打分法实现方案优化时间节点选择。以青海某铬盐厂为例，通过建立抽水方案优化时间节点评价指标体系，可定量分析方案优化时间节点，合理确定抽出终点。结果显示：第1次优化结果为抽水井抽出效率在20%~40%时应重新布设抽水方案（P₃），即采用原抽水方案抽水100 d后需重新布设抽水井；第2次优化结果为抽水井抽出效率在20%~40%时应与其他修复技术联用（P₇），即采用一次优化后抽水方案继续抽水300 d后需联合其他修复技术开展治理。经评估，2次优化可有效提高抽水井抽出效率，使修复时间缩短600 d，相同时间内含水层中六价铬去除率增加8.31%。

Pumping Treatment Technology to Pump out Contaminated Groundwater: Extraction Efficiency and Extraction Endpoint

In the process of recovery of polluted groundwater by pumping treatment technology,the extraction efficiency of pump decreases gradually over time,and it is difficult to determine the end point of pumping treatment. In order to improve the efficiency of extraction, reduce repair costs, repair time of the treatment, multiple optimization of pumping scheme is proposed. By using the analytic hierarchy process and expert scoring method, the index weight, quantitative characterization of the optimal time node, and the extraction endpoint are realized. Taking a chromium salt plant in Hebei as an example, the above method was applied to optimize the pumping scheme. The results showed that when the pumping efficiency was 20%-40%, the proportion of the pumping scheme (P₃) was the largest. In the first time optimization, P₃ should be re-arranged after 100 d pumping. The second optimization plan is to combine with other rehabilitation technologies after the first optimization, that is to continue pumping for 300 d after the first optimized pumping scheme was used; and then, to treat the remaining contaminated groundwater of the site with other rehabilitation technologies. After evaluation, the second optimization can effectively improve the pumping efficiency of the pumping well, shorten the repair time by 600 d, and increase the removal rate of hexavalent chromium in the aquifer by 8.31% in the same time.