净水厂滤池反冲洗水回用对常规工艺去除内分泌干扰物的影响机制及对策研究

Spent filter backwash water (SFBW) comprise the majority of the waste streams from conventrational surface water treatment plants (CSWTP), and it can comprise about 3-10% of the plant throughput. Recycling residuals were believed not only improving drinking water production, saving coagultant input, but also help to remove turbidity, microorganism, natural organic matter (NOM) contained in raw water. Thus, the recycling residuals has been accepted by many water treatment plants. However, SFBW may contained endocrine disrupting chemicals (EDCs) which removed by sand filter, and it may cause health risk while it is hard to remove completely through conventrational treatment process. This program will choose representively EDCs in drinking water firstly, then study the changement of EDCs concentration and state during the sand filter backwash, and then study the effect of SFBW recycle on EDCs removal in conventrational water treament. Finally, a model containing the properties of solution, the mode of SFBW recycle and the kinds of EDCs was built to predicting the best recycling ratio, and proposed the best SFBW recycle strategies. The results of this program would show the effect of SFBW recycle on EDCs removal in conventrational water treatment process, and proposed a SFBW recycle stratege under the consideration of EDCs, turbidity, microorganism, NOM removal, which would help to control EDCs concentration in effluent.

在净水厂生产过程中，会产生以滤池反冲洗水（SFBW）为主的生产废水（约占制水规模的3-10%）。回用一定比例的SFBW不仅可以提高产水率、节约混凝剂，而且能够提高浊度、微生物和天然有机物等指标的去除率，该工艺已经被多数水厂采用。然而，SFBW中富集着已被去除的内分泌干扰物（EDCs）等微污染物，鉴于常规净水工艺难以全面有效地将该类物质去除，因此SFBW回用可能会对饮用水安全造成一定风险。本项目选择饮用水中具有代表性的EDCs作为研究对象，考察滤池反冲洗时，SFBW中EDCs的赋存状态及浓度的变化情况；进而结合小试实验研究SFBW回用对常规净水工艺去除EDCs的影响；最终建立基于溶液性质、回用方式、EDCs种类等多因素耦合的回流比预测模型，得到最佳回用方案。本研究将探明SFBW回用对常规工艺去除EDCs的影响机理，并提出优化回用策略，为净水厂控制出水中EDCs浓度奠定理论和技术基础。

滤池反冲洗水（SFBW）回用技术已经被多数净水厂采用，然而SFBW中富集着已被去除的内分泌干扰物（EDCs）等微污染有机物，可能会对饮用水安全造成一定风险。本研究选择饮用水源水中检出频率较高、浓度较大的农药类EDCs作为研究对象，系统地考察了SFBW回用条件下出水中各种农药浓度的变化。本项目取得的研究成果包括：（1）发现向水样中加入一定比例有机溶剂能够有效地消除微滤膜以及检测仪器管路对疏水性EDCs的吸附效应，进而开发出一种预处理简单、灵敏度高的检测方法。（2）常规净水工艺对EDCs的去除率依据这些物质物理化学性质不同而有较大差异，并且已经通过“混凝-沉淀-过滤”工艺去除的EDCs不会随着SFBW直接回用再次释放到水中。（3）随着SFBW回用比例的增加，进水及出水中去除率较低的农药浓度基本保持不变；但对于去除率较高的农药，由于出水中EDCs浓度低于原水中的浓度，会导致出水中EDCs浓度随着SFBW比例的提高而下降。（4）高级氧化技术（AOPs）会大幅升高后续氯化消毒过程中消毒副产物的生成势，因此将AOPs技术应用于饮用水处理时应考虑对氯代消毒副产物的影响。（5）常规工艺预氧化过程会降解部分农药，从而可能会升高出水中农药氧化产物的残留浓度，从而会对人体健康造成一定风险。