由于出厂水中残余颗粒沉降、溶解物质析出以及管材腐蚀等原因使给水管网内壁普遍附着有疏松沉淀物和腐蚀产物形成的硬质管垢，且这些管壁附着物通常含有多种有毒有害无机污染物。在管网水力或水质条件发生变化时，无机污染物可大量释放进入水中，危害公众健康。本项目以典型城市给水管网中无机污染物的调查为出发点，通过多种仪器手段综合表征管网内无机污染物的分布特征及其赋存形态，并结合水源、处理工艺、出厂水以及管材状况等因素解析无机污染物的主要来源。通过管网模拟实验、模型计算等多种手段研究出厂水中微量无机污染物在管网中析出及其在管壁上的吸附累积等过程，探讨沉淀物和管垢内不同结合形态的无机污染物重新释放的主要影响因素，揭示无机污染物在管网水相、沉淀物和腐蚀管垢中的迁移转化过程机制。本项目研究可为供水行业合理制定管网水质维持方案提供技术支持，同时还可为制定基于用户端水质安全的饮用水标准提供依据。

Loosely attached deposits and relatively hard corrosion scales are commonly existed on the pipe inner-walls of drinking water distribution systems (DWDS). Toxic and harmful inorganic contaminants are widely detected in the solids attached to distribution pipes. Inorganic contaminants accumulated in the pipe solids could be released back into bulk water and put consumers' health at risk under the condition of hydraulic or water quality changes in DWDS. This project will conduct a preliminary investigation of inorganic contaminants in typical DWDSs in China, and the distribution and speciation of inorganic contaminants in pipe solids will be characterized by using state-of-the-art instrumental techniques, then the origin of inorganic contaminants will be analyzed according to the source water and finished quality, water treatment processes and pipe condition assessment. Different experimental methods including pipe loop simulation and process modelling will be adopted to elucidate the precipitation, sedimentation and adsorption behaviors of residual inorganic contaminants in finished water. Meanwhile, the factors influencing the release processes of inorganic contaminants with different speciation and combination status will be investigated. The overall aim of this project is to illustrate the transportation mechanisms of inorganic contaminants between bulk water and different pipe wall solids. The results obtained could provide technical support for the water industry to establish effective DWDS water quality maintenance measures. In addition, this research could also help to improve the current drinking water quality standards based on the water safety at the consumers' taps.