给水管网腐蚀层中稳态水对管网水质影响机制及调控方法

On the basis of the results of previous studies，the research concerned the secondary pollution problems of water supply distribution system.further analysis of quality characteristics of steady water in pipe corrosion layer was made. ATR-FTIR was used to analyze the corrosion of the pipe online in the steady water environment Corrosion mechanism under steady water environment and construct the kinetic equation was studied. High concentrations of chemicals of steady water accumulation and microbial growth mechanism and influencing factors were analyzed. Also the way and influencing factors of the release of pollutants in steady water to flowing water was studied. Analysis of high concentrations of chemicals of steady-state water accumulation and microbial growth mechanism and influencing factors, analytical steady-state water pollutant release to the flow of water within the pipe, channels, and influencing factors, reveal the accumulation and release of chemicals and microorganisms of steady-state water mechanism. Based on the results of mechanism studies, screening factors affect the steady-state water pollutant release, using the method of orthogonal experiment and effective way to control the steady-state release of pollutants in water. The corrosion mechanism of the findings on in-depth understanding of the pipe network, better control of secondary pollution of water pipe network, safeguard the safety of drinking water distribution has a very important significance.

本课题针对给水管网输配过程中水质二次污染问题，在前人研究成果的基础上，从微观上进一步分析管网腐蚀层内稳态水水质特征及其界面环境。利用衰减全反射红外光谱在线分析稳态水环境下管壁界面的腐蚀过程，阐明稳态水环境下的管壁腐蚀机理，并构建其反应动力学方程。分析稳态水中高浓度化学物质累积和微生物生长的机制及影响因素，解析稳态水中污染物向管道内流动水释放的过程、途径和影响因素，揭示稳态水中化学物质与微生物的累积与释放机制。基于机理研究的结果，筛选影响稳态水污染物释放的因素，利用正交实验的方法，研究控制稳态水中污染物释放的有效方式。研究结果对深入认识管网腐蚀机理，更有效地控制管网水质二次污染，保障饮用水安全输配都都具有非常重要的意义。

本项目围绕给水管网输配过程中水质二次污染及供水管道的腐蚀问题，对铸铁给水管道中稳态水所在的管垢层进行了研究，分析了管垢层内物理结构及化学组成成分。自行设计并搭建闭塞水研究实验装置，从微观层面较全面地对比分析了管壁腐蚀层内、外的水质特征；另外通过模拟给水管网局部腐蚀的闭塞电池装置，研究了闭塞水中化学物质累积与迁移机制以及铸铁在闭塞水中的腐蚀行为，以期达到通过调节水厂出水水质进而控制或减缓管网腐蚀进程的目的。围绕以上研究方向和目的，开展了大量深入的研究工作，并取得了一系列新颖的研究成果，代表性成果主要有：1.通过对管道内水体水质特征的深入对比分析，将给水管道内的水分成三类：主体水，稳态水和闭塞水，其水质存在巨大差异。相对于流动水，闭塞水呈酸性，含有更多的溶解性铁及铁的悬浮颗粒物，并富集氯离子、硫酸根、硝酸根和锰离子等。且闭塞水中铸铁的腐蚀速率远远大于其在流动水中的腐蚀速率；2.通过模拟给水管网局部腐蚀的闭塞电池装置，发现Cl-、SO42-、NO3-能够从流动水向闭塞水中迁移并富集，这些阴离子之间既有竞争关系，又存在协同关系。流动水水质参数的改变会影响阴离子的迁移速率，可以通过改变流动水水质来影响闭塞区铸铁的腐蚀行为。调节流动水pH 值在8.5左右，降低Cl-浓度，提高NO3-浓度，适当调节SO42-浓度可以降低闭塞区铸铁的腐蚀速度；3.提出了新的铸铁给水管道局部腐蚀机理。铸铁局部腐蚀的阳极主要为闭塞区内铸铁的溶解反应，阴极主要是在管垢外部发生的氧还原反应。闭塞区逐渐变为贫氧区，pH值不断降低，阴离子不断富集，形成自催化效应，加速铸铁腐蚀。