Excellence in Research: Delineating the characteristics, transformation and water quality impacts of landfill leachate induced dissolved organic nitrogen

在美国，过量的氮排放到地表水水体(如湖泊、河流和河口)，正在造成普遍和令人头疼的环境问题，从有害的藻华(HAB)到完全的富营养化，对全国的水质产生了负面影响。目前对氮(N)水污染的研究主要集中在无机氮(如硝酸盐)。溶解有机氮(DON)虽然往往是废水厂废水中的一大部分氮，但在历史上一直被忽视。该项目的首席调查人员和其他研究人员最近的研究表明，垃圾渗滤液是DON的重要来源，其N质量流量与废水和农业径流相当。本研究的目的是对垃圾渗滤液中的DON进行表征，评价其富营养化潜力，并利用生物脱氮工艺去除污水处理厂中的DON。该项目的成功完成将使社会受益，因为发展了新的基础知识，可用于指导废水处理过程中的氮去除，以及对减轻赤潮感兴趣的水质管理人员。将通过利益相关者/公众宣传和学生教育/培训进一步造福社会，包括指导一名在HBCU(北卡罗来纳农工州立大学)注册的博士生和一名非研究生。目前关于地表水体氮(N)污染的研究主要集中在无机氮，即来自农业径流和废水处理厂废水的硝酸盐。然而，越来越多的证据表明，垃圾渗滤液中的溶解有机氮(DON)是氮污染的一个重要来源。垃圾渗滤液中的DON主要由两大类化合物组成：1)蛋白性DON；2)来源于DON的腐殖质(HS)。这两个组分具有不同的分子组成，在生物脱氮(BNR)工艺促进藻类生长和污水处理厂脱氮过程中表现出明显不同的行为。本研究的总体目标是全面调查垃圾渗滤液中DON的存在、特征、在不同BNR工艺场景/配置下的降解和转化规律，以及它对有害藻华的影响。为推进这一目标，本项目的首席研究人员建议开展一项围绕三个具体目标的综合实验计划：1)将DON的发生和组成与垃圾填埋场的特性(例如，年龄和稳定阶段)相关联；2)阐明传统和短路BNR工艺中垃圾渗滤液诱导的DON的降解、转化和去除；以及(3)评估垃圾渗滤液诱导的DON对有害藻华动态的影响。这些具体目标将通过将最先进的DON表征研究与实验室规模的BRN实验和实地DON渗滤液收集结合起来，然后进行藻类生长和刺激的生物测试来实现。这项拟议研究的成功完成可以提供新的数据和基础知识来指导DON缓解水污染和赤潮。该奖项由NSF/ENG/CBET部门的环境工程和环境可持续发展计划和NSF/ENG/EEC部门的广泛参与工程计划共同资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

In the United States, the discharge of excess nitrogen into surface water bodies (e.g., lakes, rivers, and estuaries) is causing pervasive and vexing environmental problems ranging from harmful algal blooms (HABs) to complete eutrophication that negatively impact water quality nationwide. Current research on nitrogen (N) water pollution has primarily focused on inorganic nitrogen (e.g. nitrate). Dissolved organic nitrogen (DON), while often a large fraction of the nitrogen from wastewater plant effluents, has been historically overlooked. Recent studies by the Principal Investigators of this project and others suggest that landfill leachates are significant sources of DON with comparable N mass flows as wastewater effluents and agricultural runoffs. The goals of this research are to characterize DON from landfill leachates, evaluate its eutrophication potential, and its removal efficiency in wastewater treatment plants using biological nutrient removal processes. The successful completion of this project will benefit society through the development of new fundamental knowledge that could be used to inform nitrogen removal during wastewater treatment as well as water quality managers interested in mitigating HABs. Further benefits to society will be achieved through stakeholder/public outreach and student education/training including the mentoring of one doctoral student and an ungraduate student enrolled at an HBCU (North Carolina A&T State University).Current research on nitrogen (N) pollution in surface water bodies has focused primarily on inorganic nitrogen, i.e., nitrate from agricultural runoff and wasterwater plant effluents. However, there is growing evidence that dissolved organic nitrogen (DON) from landfill leachates is a significant source of N pollution. DON from landfill leachates has been shown to consist of two broad classes of compounds 1) proteinaceous DON and 2) humic substances (HS) derived DON. These two fractions have different molecular compositions with distinctly different behaviors during algal growth stimulation and N removal in wastewater treatment plants using biological nutrient removal (BNR) processes. The overarching goal of this research is to comprehensively investigate the occurrence, characteristics of DON from landfill leachates, its degradation and transformation patterns in various BNR process scenarios/configurations, and its impacts on harmful algal blooms. To advance this goal, the Principal Investigators of this project propose to carry out an integrated experimental program structured around three specific objectives: 1) Correlate occurrence and composition of DON with landfill characteristics (e.g., age and stabilization stage), 2) Elucidate the degradation, transformation, and removal of landfill leachate induced DON in conventional and short-cut BNR processes, and (3) Evaluate the impacts of landfill leachate induced DON on harmful algal bloom dynamics. These specific objectives will be accomplished by coupling state-of-the-art DON characterization studies with laboratory scale BRN experiments and field DON leachate collections followed by bioassays of algal growth and stimulation. The successful completion of the proposed research could provide new data and fundamental knowledge to guide the mitigation of water pollution and HABs by DON.This award is jointly funded by the Environmental Engineering and Evironmental Sustainability programs of the NSF/ENG/CBET Division and the Broadening Participation in Engineering program of the NSF/ENG/EEC Division.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.