Over 5000 public drinking water systems in the US are out of compliance with the Lead and Copper Rule. Lead leaching from lead pipes is limited by the solubility of a naturally occurring scale. Changes in water quality may cause this scale to become more soluble, releasing lead into the drinking water. We propose a novel electrochemical method to prevent lead leaching from lead pipes. In this method, an aluminum wire and an alkaline phosphate electrolyte are inserted into the pipes. The pipes are then anodized for 2 h by using an external power supply, resulting in the electrodeposition of an insoluble aluminum oxide layer on top of the preexisting scale. This technology was tested on lead pipes from the EBMUD water distribution systems located in Berkeley, CA, using recirculating synthetic and actual tap water for 120 days. The untreated pipes leached an average of 23 ppb and 38 ppb of lead respectively, when using free chlorine and monochloramine as disinfection residuals. In contrast, the treated pipes leached 3 ppb and 5 ppb respectively. These results suggest that the proposed treatment has the potential to prevent lead leaching regardless of the disinfection residual and thus should be further explored in a field trial.

美国超过 5000 个公共饮用水系统不符合铅和铜规则。从铅管中浸出的铅受到天然水垢溶解度的限制。水质的变化可能会导致这种水垢变得更易溶解，从而将铅释放到饮用水中。我们提出了一种新的电化学方法来防止铅从铅管中浸出。在这种方法中，将铝线和碱性磷酸盐电解质插入管道中。然后使用外部电源对管道进行 2 小时的阳极氧化，从而在预先存在的水垢上电沉积不溶性氧化铝层。这项技术在位于加利福尼亚州伯克利的 EBMUD 配水系统的铅管上进行了测试，使用再循环合成和实际自来水进行了 120 天。当使用游离氯和一氯胺作为消毒残留物时，未经处理的管道平均分别浸出 23 ppb 和 38 ppb 的铅。相比之下，处理过的管道分别浸出 3 ppb 和 5 ppb。这些结果表明，无论消毒残留如何，所提出的处理方法都有可能防止铅浸出，因此应在现场试验中进一步探索。