水质参数复合变动下基于氧化还原电位的管网铁释放风险研究

At present the problems of secondary pollution, iron release and red water in water distribution networks become more and more serious. The research is carried out to solve the problems. It is from the perspective of composite changes of water chemical conditions and takes oxidation reduction potential as the starting point. It covers the law of iron release, risk prediction and assessment and control methods. The main contents are including composite changing models of water quality parameters and iron release conditions of the corresponding model, the influences on oxidation reduction potential and iron release and the relativity between the two, the prediction model of iron release based on oxidation reduction potential, the comprehensive assessment system of iron release risk and reasonable control methods for risk reduction. Therefore, the research can provide direct and scientific basis for secondary pollution control and water quality improvement. And it may help lay a foundation for the running of water distribution networks with higher efficiency, better quality and more safety.

针对目前我国给水管网二次污染严重、铁含量超标及“黄水”现象频发等问题，从水化学条件复合变化的角度出发，以管网水的氧化还原电位为切入点，开展铁释放规律、风险预测与评价、控制措施等方面的研究工作。主要包括：建立管网水质参数的复合变动模型，研究相应模式下的铁释放发生条件；分析复合变化的水质对氧化还原电位与铁释放过程所造成的影响及其相关性；建立基于氧化还原电位的铁释放预测模型；构建管道的铁释放风险综合评价体系；以削减管道铁释放风险为目标，提出合理的控制方法与措施。该研究能够为管网的二次污染控制、供水水质改善提供直接、科学的理论依据，并为管网系统高效、高质、安全运行的实现奠定基础。

供水管网系统是城市供水系统的重要组成部分，但是目前二次污染、铁含量超标等问题日益突出。本项目针对上述问题，以混合供水区域为切入点开展研究。利用不动点迭代法实现了管网的水力模拟模型的快速、稳定的求解，并在此基础上，结合水质检测，确定了供水分界线及其漂移带的位置；利用饱和指数LSI、稳定指数RSI和拉森比率LR，建立了水质化学稳定性评价体系；通过扫描电镜、X射线衍射分析等，发现铸铁管和钢管的管垢物理化学特性具有明显差异；利用动态及静态模拟实验系统，分析了DO、pH、碱度、Cl-、SO42-等单一因素变化及复合变化条件下的铁释放过程，DO和碱度的升高会抑制铁释放，Cl-和SO42-的升高会促进铁的释放，而pH=7.0时铁释放量最小，升高或降低pH均会促进管道内的铁释放；混合供水区砷的平均浓度为0.98 μg/L，但致癌风险值在10-6到10-5之间，表明混合水中的砷对公众健康有潜在风险；结合X市饮用水检测结果，锶的含量在0.06~1.69 mg/L范围内，平均浓度为0.34 mg/L，锶暴露引发的健康风险指数的平均值和95%分位数值均小于1，即风险在可接受水平范围内；TCM、BDCM、DBCM、TBM和砷的平均浓度分别为12.67 μg/L、1.42 μg/L、0.60 μg/L、0.13 μg/L和1.00 μg/L，砷引发的健康风险占总风险的72.07%，而三卤甲烷的风险占27.93%，由此确定砷是X市饮用水中应优先控制的有毒物。