Subsurface arsenic (As) removal has been proposed for in situ immobilizing As in aquifers at a low cost and without post-disposal of As-containing wastes. However, the results reported for field tests are very limited, particularly when high As, phosphate (P) and iron (Fe) coexist in the groundwater. Herein the performance of single- and multiple-well operations was evaluated for in situ removing groundwater As in Jianghan Plain, central China. To enhance groundwater oxygenation, in-well electrolysis was employed in both operation modes. The groundwater in confined aquifer in Jianghan Plain contains elevated concentrations of As (272–606 μg/L), Fe²⁺ (4.7–14.3 mg/L) and P (0.90–1.58 mg/L). In the single-well operation with cycles of injection and abstraction, groundwater Fe²⁺ was completely removed but As cannot be reduced to below the World Health Organization guideline (10 μg/L) due to the high concentration and the competition of coexisting P. In-well electrolysis is cost-effective for boosting dissolved oxygen (DO) and Fe²⁺ removal in single-well operations. In the multiple-well operation with one abstraction well surrounded by 6 in-well electrolysis wells, removals of groundwater As, Fe, P and Mn were not sufficient because of clogging of treatment wells and incomplete capture of groundwater flowing to the abstraction well. In comparison, single-well operation is more simple and efficient for in situ treatment of groundwater As and Fe than multiple-well operation. This study provides a field example of in situ removing high As in groundwater by both single- and multiple-well operations, and underscores the difficulty in treating the groundwater with coexistence of elevated As and P.

已经提出了去除地下砷（As）的方法，以低成本将其原位固定在含水层中，并且无需后处理含As的废物。但是，现场测试报告的结果非常有限，特别是当地下水中同时存在高砷，磷酸盐（P）和铁（Fe）时。在这里，对单井和多井作业的性能进行了评估，以原位去除华中江汉平原地区的地下水。为了提高地下水的氧合作用，两种操作模式均采用井内电解。江汉平原承压含水层中的地下水中As（272–606μg/ L），Fe ²⁺（4.7–14.3 mg / L）和P（0.90–1.58 mg / L）。在注入和提取循环的单井操作中，地下水中的Fe ²⁺被完全去除，但由于P的高浓度和共存竞争，As不能降低到世界卫生组织的指导标准（10μg/ L）以下。井内电解在单井操作中提高溶解氧（DO）和去除Fe ^2+的成本效益。在多井作业中，一口采油井被6口井内电解池包围，由于处理井的堵塞和流向采油井的地下水的不完全捕集，地下水As，Fe，P和Mn的去除还不够。相比之下，单井操作在现场更简单，更高效地下水砷和铁的处理要比多井作业的多。这项研究提供了通过单井和多井作业原位去除地下水中高砷的现场实例，并着重说明了在高砷和高磷共存的情况下处理地下水的难度。