蓝藻胞外聚合物在供水过程中的行为特征及对水质安全的影响研究

Extracellular polymeric substances (EPS) formed and secreted on the surface of cyanobacteria is a kind of high organic pollutant, which will seriously contaminated the drinking water sources and water quality. Investigating the release mechanism and contamination characteristics of cyanobacterial EPS in water sources, ascertaining the migration and transformation of cyanobacterial EPS during drinking water treatment processes and evaluating the influence of EPS on the water quality are necessary for keeping the water safety. In this project, cyanobacterial EPS is selected as the target of water safety analysis. The contamination characteristics of cyanobacterial EPS in water sources are explored by the investigation of the release mechanism and composition distribution of free EPS; the migration and transformation of cyanobacterial EPS during drinking water treatment processes and their water risks are studied by the investigation of their isolation, migration, adsorption, retention and transformation in water treatment units; the biological stability risks of cyanobacterial EPS to the water supply network are evaluated by the investigation of their changes during water supply. As a result, the influence mechanism of cyanobacterial EPS on drinking water safety is clarified and the water safety evaluation method based on cyanobacterial EPS is established to provide a theoretical basis for the protection of drinking water quality. This project has important theoretical significance and application value for the safe supply of drinking water.

蓝藻细胞表面形成和分泌的胞外聚合物（EPS）是一种高有机污染源，严重污染饮用水水源及处理水质。探究蓝藻EPS在水源水中的释放机制及污染特性，探明蓝藻EPS在饮用水处理过程中的迁移转化规律，评估残留蓝藻EPS对供水水质的影响，是保障饮用水安全的必要基础。本项目拟以蓝藻EPS作为水质安全分析的切入点，研究蓝藻向水源水中释放游离态EPS的机制及其组分结构特征，探讨蓝藻EPS对水源水的污染特性；考察蓝藻EPS在水处理单元中的游离、迁移、吸附、截留、转化等作用，探究蓝藻EPS在饮用水处理过程中的迁移转化规律和水质风险；考察残留蓝藻EPS在供水管网输运中的变化规律，评估蓝藻EPS对供水管网生物稳定性的风险。从而全面解析蓝藻EPS对饮用水水质安全的影响机制，建立基于蓝藻EPS的饮用水安全评价方法，为保障饮水水质安全提供技术理论基础。研究工作对于饮用水的安全供给具有重要的理论意义和应用价值。

本研究以蓝藻细胞表面形成和分泌的胞外聚合物（EPS）作为水质安全分析的切入点，探究了蓝藻EPS在水源水中的释放机制及污染特性，探明了蓝藻EPS在饮用水处理过程中的迁移转化规律，评估了残留蓝藻EPS对供水水质的影响风险。研究结果表明水源水质pH、温度、光照、涡流搅拌等各项自然因素均为蓝藻EPS分泌释放的外界环境刺激，自然环境刺激下蓝藻EPS的释放污染不容小觑。常规水处理工艺对蓝藻EPS的去除主要靠预氧化、消毒等化学反应过程，混凝效果次之，过滤截留效果并不明显，但由于蓝藻EPS中含有大量的腐殖酸、富里酸等大分子有机物质，氯化消毒工艺极易导致消毒副产物的生成，非氯化消毒工艺用于处理蓝藻EPS相对较安全。蓝藻细胞EPS的有效分离去除可以减少细胞间静电斥力，增加颗粒间碰撞概率，同时增大细胞颗粒疏水度，使藻细胞更容易从水溶液中分离去除，改善蓝藻混凝效果。供水管网中残留蓝藻EPS存在会显著影响管网生物稳定性，促使细菌快速增长繁殖，总活菌数72h内升高18-20倍，加快余氯衰减速度，并易导致管网水质浊度在12-24h后即超出生活饮用水卫生标准上限。因此应尽可能在水处理出水进入管网之前阻绝蓝藻EPS的残留问题。该研究工作对于饮用水的安全供给具有重要的理论意义和应用价值。