根系分泌物介导下生物电化学强化人工湿地去除低污染水中PPCPs的研究

The occurrence of pharmaceuticals and personal care products (PPCPs) in slightly contaminated water in relation to sewage treatment plant (STP) discharges and non-point source pollution is an issue of general concern. Constructed wetland (CW) is still needed to be improved with regard to the PPCPs removal although it is suitable for treatment of slightly contaminated water. Considering that CW and microbial fuel cell (MFC) could be integrated smoothly in the structure, we firstly develop a MFC type wetland (MFCW) in this proposal. In addition, the bio-film electrode reactor (BER) will be used to consume the electrical energy produced by MFCW and simultaneously be used as pre-treatment of MFCW. The biodegradability of PPCPs could be improved by BER section, thus the removal efficiency of PPCPs in MFCW could be promoted. To deal with the problem of lacking of easily degradable organics in slightly contaminated water, root exudates (REX) will be especially adopted as co-substrate to improve energy yield of MFCW and simultaneously as co-metabolism primary substrate to stimulate the degradation of PPCPs and their metabolites. Consequently, a new integrated biological-electrochemically enhanced wetland system could be developed. First, we aim to explore the role of MFC process on the enhancement of CW with regard to the degradation of PPCPs. Second, we attempt to elucidate the effects of the configuration and operating conditions on the improvement of biodegradability of PPCPs parent compounds in BER section. Third, we aim to illuminate the stimulating mechanisms of various constituents as well as mixture liquid of root exudates for the electric energy production and the co-metabolism biodegradation of PPCPs, respectively. Lastly, we will explore the regulating strategy for matching the balance of matter and energy as well as the removal mechanisms of PPCPs in the new biological-electrochemically enhanced wetland system. This study will have great significance for the control of PPCPs pollution, the mitigation of ecological and healthy risks caused by PPCPs as well as the interdisciplinary studies between ecological engineering and biological-electrochemistry.

污水处理厂尾水、面源污染水等低污染水中医药与个人护理品(PPCPs)对水生态及人类健康有潜在严重危害。人工湿地(CW)是处理低污染水的首选，但其去除PPCPs的效能亟需加强。本课题首先利用CW和微生物燃料电池(MFC)在构造上易融合的优势，构建MFCW；并利用生物膜电极(BER)作为MFCW的外部用电器和预处理单元；尤其针对低污染水中易降解有机物不足对产电的制约，引入根系分泌物作为共基质，同步促进MFCW产电及PPCPs共代谢降解，构成根系分泌物介导的生物电化学增强型人工湿地耦合系统。研究：MFC电化学过程强化CW降解PPCPs的机理；BER对PPCPs的预转化机制；根系分泌物单一及混合组分对促进MFCW产电及促进PPCPs共代谢降解的机理；揭示新型湿地耦合系统中的物质能量匹配条件及PPCPs去除途径。成果对控制PPCPs污染、保障人类健康、促进生态工程学与生物电化学交叉融合具有重要意义。

本研究以强化去除低污染水中的药物和个人护理品（PPCPs）类污染物为目的，构建了全新的生物膜电极反应器（BER）-人工湿地微生物燃料电池(CW-MFC) 的耦合系统，并探索了相关抗生素抗性基因（ARGs）在耦合系统中各个单元的时空变化规律。本课题首先研究了CW-MFC去除PPCPs的特性，结果表明进水PPCPs浓度、共基质浓度、水力停留时间 (HRT) 都应控制在一定范围内，才能使系统在产电电压、功率密度和库仑效率方面达到优化平衡。研究发现闭路运行模式能提高电极对PPCPs的吸附能力并刺激了微生物代谢活性，因此具有更好的去除效果。. 为强化CW-MFC的电产生和COD去除能力，创新性地构建了上向流锰矿石基质CW-MFC。锰矿石CW-MFC强化了产电菌和相关功能基因的富集，抑制了产甲烷菌及相应的功能基因，增强了系统对COD的去除能力。方差分解分析表明，基质类型、抗生素聚集和细菌群落演化是影响ARGs的主要因素。Network神经网络分析结果揭示了潜在的抗生素抗性基因宿主，同时揭示了抗性基因和整合子基因以及宿主细菌的共出现模式。. 为了强化CW-MFC对PPCPs的去除效率，在CW-MFC前端构建了低电流运行的BER反应器。结果表明低电流不会对磺胺类抗生素的降解产物及降解途径产生影响，但是可以提高其去除速率。进一步构建了3D-BER反应器，3D-BER显著增强了对磺胺类和四环素类抗生素的去除效果。微生物的生物量、脱氢酶活性及相对丰度在低电流的刺激下呈现出增加趋势。而且，与其他普通厌氧生物方法相比，3D-BER能够显著减少ARGs扩散的风险。揭示了在弱电流刺激条件下，耦合系统中分离纯化出的纯培养耐药菌和耐药基因对电流的响应规律。. 在上述研究基础上，进一步构建了BER-CW-MFC耦合系统。研究了系统对抗生素去除及ARGs在系统内部的动态变化规律。结果表明BER中磺胺类抗生素的去除效率和ARGs丰度受进水抗生素浓度和HRT的影响。随着HRT的延长，BER和CW-MFC中sul基因相对丰度在减少。研究发现，生物电有效减少BER系统微生物群落多样性，并减少出水的ARGs丰度。. 研究成果对于控制PPCPs污染、保障人类健康、促进生态工程学与生物电化学交叉融合具有重要意义。