消毒剂和溶解氧对管网铁释放影响的中试研究

针对南水北调中线水源地丹江口水库水调入受水区城市后,可能引起管网铁腐蚀产物释放的问题,从北方某受水区城市的实际管网中挖取了原通地下水的3个地点的铸铁管道,在丹江口搭建了中试模拟系统,开展水源切换以及消毒剂和溶解氧对管网铁释放影响的中试研究。结果表明,实验管道管垢较薄且稳定性较差,在水源切换初期有"黄水"现象发生;增加进水硫酸根浓度,管网系统出水总铁浓度和浊度均有所增加;在0.3~3.6 mg/L的范围内改变进水自由氯浓度对实验系统铁释放的影响没有明显的规律;但进水氯胺浓度从1.3 mg/L增加到2.0 mg/L时,YS系统的铁释放有所升高;进水溶解氧浓度从8 mg/L增加到15 mg/L时,实验系统的铁释放都有明显的降低,但再增加到20 mg/L时,铁释放反而有所升高。

Pilot study on effects of disinfectant and dissolved oxygen on iron release in distribution system

Water source switch to Danjiangkou reservoir (the middle route source area of the South-to-North Water Diversion Project in China) water might cause increased iron release in distribution systems of water receiving areas.Cast iron pipes transporting groundwater were harvested from three sites of existing distribution system of a northern city,and pipe-loop distribution systems were established in Danjiangkou.Pilot study was conducted to observe the outcomes of source water switch,and the effects of different disinfectants and dissolved oxygen concentration on iron release behaviors were investigated.Results show that the corrosion scales on the test pipes are relatively thin and less stable; at the early stage of water source switch,apparent "red water" occurs.The effluent iron concentration and turbidity increase accordingly with the increase of sulfate concentration.The change of iron release with free chlorine concentration change in the range of 0.3~3.6 mg/L has no clear trend.While iron release of YS system increases significantly as chloramine concentration is raised from 1.3 to 2.0 mg/L. When dissolved oxygen increases from 8 mg/L to 15 mg/L,iron release decreases significantly,but further increase of dissolved oxygen to 20 mg/L results in iron release increase.