An integrated technology for efficient selenium remediation

硒是一种金属，被用于制造各种工业产品，包括玻璃、颜料、光伏电池和半导体器件。近年来，硒对地表水系统和地下水含水层的污染已成为美国乃至世界范围内的一个重要问题。在自然水体中，硒主要以硒酸盐（SeO42-）和亚硒酸盐（SeO42-）两种氧阴离子形式存在，它们具有高溶性和毒性。虽然硒（Se）由于其抗氧化特性是人类健康必需的微量营养素，但长期暴露于过量的硒会对生态系统健康产生不利影响，导致鱼类和水生无脊椎动物的突变和生殖障碍，因为有毒的硒氧离子会在水生食物链中生物积累。本项目的总体目标是探索一种新的综合处理系统的设计、评估和优化，该系统可以从污染水中提取有毒的硒酸盐/亚硒酸盐氧离子，并将其还原为无毒且不溶的元素硒（Se0）。为了推进这一目标，首席研究员（pi）提议将流动电极电容性去离子（FCDI）离子分离过程与生物电化学系统（BES）集成到一个紧凑的反应器中，利用电力作为动力和电源，从污染的废水流中去除、还原和解毒硒酸盐/亚硒酸盐氧离子。该项目的成功完成将通过产生新的基础知识和数据来促进设计和部署更有效和更具成本效益的技术，从而使社会受益，这些技术可以在工业和受污染的废水排放到接收水体之前从其中去除硒。通过学生教育和培训，包括在阿拉巴马大学指导一名博士后研究员、一名研究生和一名本科生，将为社会带来额外的好处。传统和商业上可用的水处理技术（如混凝/沉淀、离子交换和反渗透）不能同时从污染水中去除有毒的硒酸盐/亚硒酸盐氧离子，并将其转化为无毒且不溶性的零价硒（Se0）。在这个项目中，首席研究员（pi）提议测试一个假设，即将流动电极电容性去离子（FCDI）离子分离过程与生物电化学系统（BES）集成到一个紧凑的反应器中，可以同时去除、还原和将污染废水中的有毒硒酸盐/亚硒酸盐氧离子转化为无毒的Se0，使用电力作为动力和能源。本研究的具体目标是：1)利用合成硒污染废水和实际硒污染废水，在相关工况下对fdi - bes一体化反应器的性能进行表征、评价和优化；2)利用宏基因组测序技术探测并揭示硒酸盐/亚硒酸盐氧阴离子生物电化学还原的分子机制；3)进行生命周期分析（LCA）和全局敏感性分析，以指导所提出的新型集成FCDI-BES处理列车的性能优化。为实现本项目的教育和培养目标，pi计划招募和指导本科生从事本项目的研究活动。此外，pi还提议利用阿拉巴马大学现有的项目，设计并提供两项年度教育活动，包括为30-50名高中学生和教师提供沉浸式的实验室演示，这些学生和教师是从阿拉巴马州黑带的120多所学校中挑选出来的。阿拉巴马州黑带是阿拉巴马州的一个地区，面临着持续的经济和社会挑战，包括高贫困和高失业率。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Selenium is a metalloid that is utilized in the manufacturing of various industrial products including glasses, pigments, photovoltaic cells, and semiconductor devices. In recent years, the contamination of surface water systems and groundwater aquifers by selenium (Se) has become a critical problem in the United States and worldwide. In natural waters, Se predominantly exists as selenate (SeO42-) and selenite (SeO42-) oxyanion species which are both highly soluble and toxic. Although selenium (Se) is an essential micronutrient for human health due to its antioxidant properties, chronic exposure to excess Se can adversely impact ecosystem health causing mutations and reproductive impairments in fish and aquatic invertebrates as toxic Se oxyanions bioaccumulate in aquatic food chains. The overarching goal of this project is to explore the design, evaluation, and optimization of a new integrated treatment train that can extract toxic selenate/selenite oxyanions from contaminated water and reduce them to elemental selenium (Se0) which is non-toxic and non-soluble. To advance this goal, the Principal Investigators (PIs) propose to test the integration of a flow-electrode capacitive deionization (FCDI) ion separation process with a bioelectrochemical system (BES) into a compact reactor to remove, reduce, and detoxify selenate/selenite oxyanions from contaminated wastewater streams using electricity as driving force and power source. The successful completion of this project will benefit society through the generation of new fundamental knowledge and data to advance the design and deployment of more efficient and cost-effective technologies that could remove Se from industrial and contaminated wastewater streams prior to their discharge into receiving water bodies. Additional benefits to society will be achieved through student education and training including the mentoring of a post-doctoral research fellow, one graduate student, and one undergraduate student at the University of Alabama. Conventional and commercially available water treatment technologies (e.g., coagulation/precipitation, ion exchange, and reverse osmosis) cannot simultaneously remove toxic selenate/selenite oxyanions from contaminated water and convert them to non-toxic and insoluble zero valent selenium (Se0). In this project, the Principal Investigators (PIs) propose to test the hypothesis that the integration of a flow-electrode capacitive deionization (FCDI) ion separation process with a bioelectrochemical system (BES) into a compact reactor could enable the simultaneous removal, reduction, and conversion of toxic selenate/selenite oxyanions from contaminated wastewater to non-toxic Se0 using electricity as driving force and energy source. The specific objectives of the research are to 1) characterize, evaluate, and optimize the performance of the integrated FCDI-BES reactor under relevant operating conditions using synthetic and real-world selenium contaminated wastewater; 2) probe and unravel the molecular mechanisms of the bioelectrochemical reduction of selenate/selenite oxyanions using metagenomic sequencing; and 3) conduct a life cycle analysis (LCA) and a global sensitivity analysis to guide the optimization of the performance of the proposed new and integrated FCDI-BES treatment train. To implement the education and training goals of this project, the PIs plan to recruit and mentor undergraduate students to work on the project research activities. In addition, the PIs propose to leverage existing programs at the University of Alabama to design and deliver two annual educational activities consisting of immersive lab demonstrations for 30-50 high school students and teachers selected from over 120 schools located in the Alabama Black Belt, a region in the State of Alabama with persistent economic and social challenges including high poverty and high unemployment.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.