淡化海水进入市政供水管网的铁稳定性

Iron stability in desalinated seawater in municipal drinking water distribution systems

该文针对常规地表水源切换为淡化海水对既有供水管网水质铁稳定性的影响开展研究。选取中国市政管网系统中常用的灰口铸铁管和球墨铸铁管,利用实验室制作的管段模拟反应器,分析不同氯离子质量浓度的淡化海水对两种管材管段铁释放的影响。结果表明:供水管网铁释放量与淡化海水中氯离子质量浓度具有显著相关性,氯离子质量浓度从50mg/L增加至240mg/L,8h滞留水的总铁释放量最大增加灰口铸铁管约8.00mg/L,球墨铸铁管约0.40mg/L。供水管网内部腐蚀产物特性与管材密切相关,因而不同管材应对水质变化的耐受性有明显差异。淡化海水由于其水质不稳定,具有强侵蚀性,进入灰口铸铁管的供水管网前,需与常规水源水勾兑使用,严格控制淡化海水的氯离子质量浓度,以免引发严重的管网"黄水"问题。

This study investigated the effect of desalinated seawater in drinking water distribution systems on the iron stability in the pipes.The iron release rates of two kinds of pipes,an unlined cast iron pipe and a ductile cast iron pipe,were measured for various chloride concentrations in desalinated seawater with pipe section reactors.The results show that the iron release in the iron pipes correlates well with chloride concentration for chloride concentrations from 50 mg/L to 240 mg/L with the total iron concentration for the unlined cast iron pipe increasing by 8.00mg/L and that for the ductile cast iron pipe increasing by 0.40mg/L after8 hin stagnate water.The characteristics of the interior corrosion are closely related to the pipe materials.Desalinated seawater,which is strongly corrosive,should be mixed with traditional source water with control of the chloride concentration to avoid the serious＂red water＂problem in unlined cast iron pipes.