State Key Laboratory Hydroscience and Engineering, Tsinghua University, Beijing, 100084, China.
College of Environmental Science and Engineering, Donghua University, Shanghai, 201620, China.
Water Res. 2020 May 15;175:115675. doi: 10.1016/j.watres.2020.115675. Epub 2020 Mar 3.
The release of potentially toxic metal ions from corrosion scales formed on pipe surfaces is of great concern for water quality in drinking water distribution systems (DWDS). This study examined the effects of alkalinity, chloride, and sulfate on metal release from corrosion scales sampled from a corroded iron pipe. Jar tests and recirculation pipe systems were used to investigate the metal-release potential during stagnant and active flow conditions. The experimental data show that both the ambient water chemistry and hydraulic conditions exerted complex influences on metal release from the exposed corrosion scales. Fe, Mn, and Ni were more labile to be released during a 132-h period of stagnation, while the release of Al, Zn, and Cu was an order of magnitude higher under flow conditions compared to stagnant conditions. Increasing concentrations of chloride (from 5 mg/L to 60 mg/L) and sulfate (from 20 mg/L to 100 mg/L) resulted in the increased release of Fe, Al, and Zn, especially under active flow conditions. This effect could be effectively mitigated by increasing alkalinity from 50 mg/L to 200 mg/L as CaCO. While increasing alkalinity suppressed the release of Fe and stimulated the release of Al and Cu under stagnant conditions, this contradictory effect was not observed under active flow conditions.
从管道表面腐蚀层中释放出潜在有毒的金属离子，这对饮用水分配系统 (DWDS) 的水质非常重要。本研究考察了碱度、氯离子和硫酸根离子对从腐蚀铁管采集的腐蚀层中金属释放的影响。使用瓶试法和循环管道系统研究了在静止和流动条件下金属释放的潜在能力。实验数据表明，环境水化学和水力条件都对暴露的腐蚀层中金属的释放产生了复杂的影响。在 132 小时的静止期内，Fe、Mn 和 Ni 更容易释放，而在流动条件下，Al、Zn 和 Cu 的释放量比静止条件下高一个数量级。增加氯离子（从 5mg/L 增加到 60mg/L）和硫酸根离子（从 20mg/L 增加到 100mg/L）浓度会导致 Fe、Al 和 Zn 的释放增加，特别是在流动条件下。通过将碱度从 50mg/L 增加到 200mg/L（以 CaCO3 计）可以有效缓解这种效应。虽然增加碱度会抑制 Fe 的释放并刺激 Al 和 Cu 的释放，但在流动条件下没有观察到这种矛盾的效果。
