School of Environmental Science and Engineering, Tianjin University, 135 Yaguan Road, Tianjin, 300350, Jinnan District, China.
Tianjin Renai College, Tianjin, 301636, China.
Environ Sci Pollut Res Int. 2023 Feb;30(6):15217-15229. doi: 10.1007/s11356-022-23151-0. Epub 2022 Sep 27.
Metal contaminants in corrosion products of drinking water distribution systems (DWDS) can be released into potable water under specific conditions, thereby polluting drinking water and posing a health risk. Under stagnation conditions, the release characteristics, occurring forms, and environmental risks of ten metals were determined in loose and tubercle scale solids of an unlined cast iron pipe with a long service history, before and after immersion. Most Al, As, Cr, Fe, and V in corrosion scales existed in the residual fraction, with the released concentration and pollution risk being low. Since more than 59% of Ca in pipe scales existed in the exchangeable fraction, Ca release was high. Although the Pb and Cd content of corrosion solids was low, a high proportion of Pb and Cd was present in non-residual fractions with high mobility. Sudden severe Pb or Cd pollution events in DWDS could result in high pollution and environmental risk levels. The total content and released amount of Mn and Zn in corrosion scales were both high. Therefore, while special attention should be paid to Mn and Zn, Pb and Cd also present a high risk in pipe scales, despite their low concentrations. During stagnation immersion, metal release from powdered pipe scales occurred via the processes of mass release, re-adsorption into scales, and slow release until equilibrium was reached. The levels of metal re-adsorption into scales were much higher than the concentrations dissolved into bulk water. However, the amount of metal re-adsorption into tubercle scale blocks was less. Importantly, these findings highlight that during DWDS operation, the sudden release of metal pollutants caused by pipe scale breakage should be avoided.
金属污染物在饮用水分配系统（DWDS）的腐蚀产物中，在特定条件下可能会释放到饮用水中，从而污染饮用水并带来健康风险。在停滞条件下，确定了经过长期服役的无衬里铸铁管松散和结核状固体中十种金属在浸泡前后的释放特性、存在形式和环境风险。在腐蚀层中，大多数 Al、As、Cr、Fe 和 V 以残余态存在，释放浓度和污染风险较低。由于管垢中超过 59%的 Ca 以可交换态存在，因此 Ca 释放量较高。尽管腐蚀固体中的 Pb 和 Cd 含量较低，但 Pb 和 Cd 的很大一部分存在于具有高迁移性的非残余态。DWDS 中突然发生的 Pb 或 Cd 严重污染事件可能导致高污染和高环境风险水平。腐蚀层中 Mn 和 Zn 的总量和释放量都很高。因此，虽然需要特别注意 Mn 和 Zn，但尽管浓度较低，Pb 和 Cd 在管垢中也存在高风险。在停滞浸泡过程中，粉末状管垢中的金属释放通过大量释放、重新吸附到垢层和缓慢释放直至达到平衡的过程发生。金属重新吸附到垢层中的水平远高于溶解到总水中的浓度。然而，重新吸附到结核状垢块中的金属量较少。重要的是，这些发现强调了在 DWDS 运行期间，应避免因管垢破裂而突然释放金属污染物。
