利用再生水大量有机物特征评价微量PPCPs在土壤渗滤过程中的去除潜能

The fate and removal mechanisms of trace pollutants PPCPs are hot topics in the area of artificial groundwater recharge with reclaimed water. Unlike the traditional research ideas, the influence of bulk effluent organic matters (EfOM) on the removal of trace PPCPs is studied during the process of soil infiltration. This idea is on the basis of the significant influences of EfOM on structure and functional diversity of soil microbes, as well as the soil environment, which play important role in the removal of PPCPs. Therefore, the characteristics of EfOM are supposed to be closely related to the removal of PPCPs. The EfOM are characterized using three-dimmesion excitation-emission spectra (3DEEM) for organic matter compositions and high performance size exclusion chromatography (HPSEC) for molecular weight distribution. The correlations of EfOM characteristics with the removal efficiency of PPCPs are then analyzed using statistical methods. Finally, a set of parameters characterized by fluorescence and molecular distribution will be suggested to assess the removal potential of trace PPCPs during soil infiltration. These results will provide theoretical and technical supports for water safety assessment and engineering practice of groundwater recharge with reclaimed water. Based on this project, it is expected to access innovative results on methods and parameters for assessment of trace PPCPs removal during soil infiltration.

再生水补给地下水过程中，微量污染物PPCPs在土壤中的迁移转化及相关机理是亟待解决的热点问题。不同于传统的研究思路，本项目从再生水中大量有机物的组分特征出发，研究其与微量PPCPs在土壤渗滤中去除特性的相关性，其理论基础是再生水中的大量有机物通过影响土壤微生物群落和土壤环境进而影响PPCPs的迁移转化。研究将采用3DEEM和HPSEC方法联合表征再生水有机物特征，建立其与典型PPCPs去除特性的相关性，形成以再生水分子量分布与荧光特性为综合特征的、评价再生水中PPCPs在土壤渗滤过程中去除潜能的指标参数，为再生水补给地下水的风险评价与工程实践提供理论依据和工具手段。通过研究，拟在土壤渗滤系统对PPCPs去除潜能的评价方法和评价指标方面取得创新性成果。

再生水涵养补给地下水过程中，微量污染物PPCPs在土壤中的迁移转化及相关机理是亟待解决的热点问题。不同于传统的研究思路，本项目将再生水水质特征作为影响因素，考察微量PPCPs在土壤渗滤系统中的去除机理，其理论基础是再生水中的有机物通过影响土壤微生物群落结构进而影响PPCPs的降解。研究表明，有机物含量较少的砂土对磺胺类抗生素（SAs）的吸附较少，去除率仅为10%-20%；但对氧氟沙星的去除率较高达到92%-100%。采用摇瓶实验和土壤柱实验两种方式模拟了土壤渗滤过程中，考察不同进水水质（二级出水和再生水）条件下SAs的降解规律。当土壤渗滤系统的进水水质不同时，系统对有机物及微量SAs的去除规律均有较大差异。一般来讲，小分子的非芳香类有机物较容易被微生物利用，导致土壤柱出水的SUVA值普遍增高。初次投加SAs的土壤渗滤系统中，SAs的降解均出现迟滞期，驯化45 d后，各系统中水样中的SAs均降低到检出限以下；再次投加SAs时，各条件下SAs均可迅速降解，降解曲线满足零级反应动力学。将SAs的降解特性与进水水质参数进行相关性分析，得出与SDZ相关性较高的水质因素包括芳香族蛋白质(I)和富里酸类(III)的物质；与SMX相关性较高的水质因素包括芳香族蛋白质(II)、腐植酸类(V)和SUVA值。三维荧光光谱的数据与难降解微量污染物的降解具有较高的相关度。二级出水为进水的条件下，土壤渗滤系统对SAs表现出较好的去除率。但从出水水质总体考虑，增加预处理有利于出水水质的提高，推荐采用臭氧氧化、臭氧氧化+活性碳吸附作为预处理工艺。