再生水回灌地下水过程中极性卤代消毒副产物在土壤中迁移转化机制研究

During groundwater recharge with reclaimed water, halogenated disinfection byproducts (X-DBPs) of high carcinogenicity and mutagenicity are generated threating groundwater security. Current research is focus on regulated volatile or semi-volatile X-DBPs based on gas chromatography analytical method. However, research on emerging polar halogenated DBPs (PX-DBPs) which are 3-4 magnitude more toxic than regulated X-DBPs is rare. This study aims to characterize the PX-DBPs in reclaimed water with advanced treatment. Those typical PX-DBPs of relatively high toxicity containing typical functional groups (i.e. benzoquinone, phenolic and pyrrole, etc.) are selected as model compounds to 1) investigate the sorption and desorption of PX-DBPs on soil and its mechanism underlying through kinetics and thermodynamics study, and setup QSAR model to establish the relationship between sorption coefficient with PX-DBPs and soil physicochemical properties and environmental factors; 2) investigate the biodegradation of PX-DBPs and its mechanism by soil microorganism and the impact of soil microorganism, redox condition and the structures of PX-DBPs on its biodegradation through PX-DBPs degradation kinetics study; 3) adopt artificial neural network algorithm in computer science to analyze the coupled mechanism of adsorption and biodegradation and to predict its environmental behavior in soil. The results of this research will provide the safety of reclaimed water reuse as well as risk assessment, control and management of micropollutants in groundwater with solid support theoretically.

再生水回灌地下水过程中，氯消毒产生的强致癌和致畸性卤代消毒副产物（X-DBPs）可对地下水安全造成威胁。目前，相关研究专注于基于GC分析的挥发和半挥发性常规X-DBPs，而对毒性可达常规物质3-4个数量级的新兴极性X-DBPs（PX-DBPs）却鲜有关注。本研究拟采用UPLC-MS/MS方法，表征深度处理再生水中PX-DBPs赋存状态，选取典型强毒性PX-DBPs（含苯醌、苯酚和吡咯等基团）为模型物质：1）研究其在土壤中吸附解吸动力学和热力学，明确吸附影响因素，建立吸附与物质和土壤理化性质及环境因素之间关系的QSAR模型；2）研究其在土壤中降解动力学，明确微生物、氧化还原条件和物质结构对降解的影响及降解规律，探讨降解机制；3）引入计算机人工神经网络算法，解析吸附和降解耦合作用机制，并实现其在土壤中环境行为预测。本研究成果将为再生水安全利用及地下水中微污染物的风险评估和管控提供理论支持。

再生水回灌地下水过程中，氯消毒产生的强致癌和致畸性卤代消毒副产物（X-DBPs）可对地下水安全造成威胁。目前，相关研究专注于基于GC分析的挥发和半挥发性常规X-DBPs，而对毒性可达常规物质3-4个数量级的新兴极性X-DBPs（PX-DBPs）却鲜有关注。本研究调研了北京市内十大再生水厂再生水处理工艺，选取了四个典型再生水处理工艺水厂的出水作为研究对象，采用超高效液相色谱-串联质谱方法，分析和鉴别了再生水出水中生成的PX-DBPs。采集了北京、哈尔滨、安阳和杭州河道包气带土壤，选取了典型PX-DBPs（包括2,4-二氯苯酚（2,4-DCP）、2,4-二溴苯酚（2,4-DBP）和2,4,6-三溴苯酚（TBP））作为研究对象，研究了其在不同土壤中的吸附解吸动力学、热力学及影响因素，探究了土壤理化性质（包括土壤有机质含量、CEC、颗粒组成等）、环境因素（包括温度、pH 和离子强度等）和PX-DPBs 理化性质对其吸附解吸的影响，建立了吸附系数与土壤性质和环境因素之间回归方程。典型PX-DBPs在不同土壤中的生物降解规律研究表明，PX-DBPs降解动力学符合一级反应，不同土壤对TBP的降解速率与土壤中的有机质含量相关。北京土壤中不同PX-DBPs的生物降解研究发现，PX-DBPs降解速率可能与其结构和毒性相关。此外，本研究搭建了土柱系统，模拟PX-DBPs在再生水回灌过程中在土水系统中的迁移转化，研究了TBP在不同时间、不同深度土壤中的迁移和降解，建立了土柱中TBP衰减浓度与迁移深度之间的关系。本研究成果将为再生水安全利用及地下水中微污染物的风险评估和管控提供理论支持。