Collaborative Research: Impact of Wastewater Derived Organic Nitrogen on Eutrophication

许多城市污水处理设施正面临越来越严格的污水氮限值，接近或超过目前的技术极限。如果允许的N水平低于常规N去除技术的极限，则必须去除溶解有机氮（DON）。研究和安装先进的处理技术以进一步去除残留的DON所需的资本成本是可观的。目前的法规使用总氮来设定限制，而没有考虑到DON和无机氮对浮游植物的生物利用度可能不同，因此它们对接收水生系统的潜在有害影响。考虑到废水中DON （wwDON）的生物利用度的不确定性，进一步减少DON是否会带来可观的环境效益？目前，关于水体中浮游植物对wwDON生物利用度的信息很少，也没有公认的定量评价wwDON生物利用度的方法。本研究旨在解决这一问题，填补理解废水衍生有机氮对接收水生生态系统影响的知识空白。本研究旨在探讨城市污水处理设施中污水don的特性，评估污水don对浮游植物的生物有效性及其对富营养化的影响。虽然N通常限制在咸水中，但咸水和淡水都受到关注，因为大多数城市排放到淡水中，最近的研究表明，上游淡水系统中N的命运和不稳定性最终会影响下游对N敏感的河口和海岸系统中N的运输和营养状况。具体目标是：1。评估wwDON对两种已知在富营养化中起作用的浮游植物的生物有效性。2 .研究海水和淡水浮游植物对污水don的生物利用度，以及细菌在污水don对藻类的稳定作用。检查wwDON的组成与其生物利用度之间的关系，并确定wwDON的生物利用度和顽固性的部分。利用原位生产的15n标记wwDON进一步评估wwDON对自然生物群（包括藻类和细菌）的命运和生物利用度。该项目将展示跨学科和综合方法解决环境挑战的好处。多学科研究涵盖至少三个学科的专业知识，这些专业知识将对淡水水生系统中污水don的生物利用度进行独特、全面和最先进的评估。拟议的研究解决了一个紧迫的问题，具有重大的社会和经济影响，以前没有调查过。研究结果将为开发标准的氮素生物利用度评估方法提供必要的信息和框架，这是公用事业和监管机构迫切需要的，以便有针对性地进行处理设计和投资，以消除对接收水生生态系统真正有害的氮素成分，从而最大化环境效益。该项目将加强两所大学现有的和新的教育推广项目。在西北大学，最近由顾创办的生物技术环境、展示和培训中心（BEST）；NSF资助的两个教育项目CONNECTIONS和RET；以及北大著名的体验式学习项目CO-OP。在北卡罗来纳大学，有美国国家科学基金会支持的（生态系统，EID和海洋科学项目）在北卡罗来纳大学ims的夏季实习和美国国家科学基金会支持的夏季研究生研究体验项目（SPGRE）。所有这些项目都旨在吸引和参与来自不同背景的学生。PI启动了ITRI（工业转化研究计划），并将与WEF/WERF（水环境联合会）合作，通过网络工具和数据库向专业人员和从业者传播信息。

0932665/0932632Gu/PaerlMany municipal wastewater treatment facilities are facing increasingly stringent effluent N limits that are near or beyond the current limits of technology. Removal of dissolved organic nitrogen (DON) becomes necessary if the permitted N level is below the limit of conventional N removal technology. The capital cost required to research and install advanced treatment technologies for further removal of the residual DON is substantial. Current regulations use total nitrogen for setting limits without consideration of the possibility that DON and inorganic N may differ in their bioavailability to phytoplankton and therefore their potential harmful impact on receiving aquatic systems. The question arises on whether further reduction of DON will bring substantial environmental benefits relative to the significant cost incurred, given the uncertainty over the bioavailability of wastewater derived DON (wwDON). Currently, there is little information on the wwDON bioavailability to phytoplankton in receiving waters and there is no accepted method for quantitatively assessing the wwDON bioavailability. This study proposes to addresses this issue and fill in the knowledge gap for understanding the impact of wastewater derived organic nitrogen on receiving aquatic ecosystems.The proposed research aims at investigating the characteristics of wwDON from municipal treatment facilities and assessing the bioavailability of wwDON to phytoplankton and its impact on eutrophication. Although N is usually limiting for saline waters, both saline waters and freshwaters are of concern here because most municipalities discharge to freshwaters, and recent studies indicated that the fate and lability (labile) of N in upstream freshwater systems will eventually affect the transport of N and nutrient condition in down-stream N-sensitive estuary and coastal systems. The specific objectives are:1. Assess the bioavailability of wwDON to two phytoplankton species known to play roles in eutrophication.2. Investigate the bioavailability of wwDON to both saline and freshwater phytoplankton and the role of bacteria in labilization of wwDON to algae.3. Examine the relationship between the composition of wwDON and its bioavailability, and identify the fractions of wwDON that are bioavailable versus recalcitrant.4. Further evaluate the fate and bioavailability of wwDON to natural biota (including both algae and bacteria) using 15N-labeled wwDON produced in situ.The project will demonstrate the benefits of interdisciplinary and integrated approach for solving environmental challenges. The multidisciplinary research covers expertise in at least three disciplines that will apply unique, comprehensive, and state-of-the-art assessment of the bioavailability of wwDON to freshwater aquatic systems.The proposed research addresses a pressing issue with significant social and economical impacts that have not previously been investigated. The results will provide essential information and framework for developing a standard wwDON bioavailability assessment method that are urgently needed by utilities and regulators in order to target their treatment design and investments at eliminating the N components that are truly harmful to receiving aquatic ecosystems and therefore maximizing the environmental benefits. The project will enhance both existing and new education outreach programs at the two institutions. At NU, there is BEST (Biotechnology for the Environment, Showcase and Training), a center recently initiated by Gu; CONNECTIONS and RET, two NSF funded education programs; and CO-OP, a distinguished experiential learning program for NU. At UNC, there are NSF-supported (Ecosystems, EID and Ocean Sciences Programs) summer internships at UNC-IMS and NSF-supported Summer Pre-graduate Research Experience Program (SPGRE). All these programs intend to attract and involve students from diverse backgrounds. The PI started ITRI (Industrial Translational Research Initiative) and will work with WEF/WERF (Water Environment Federation) for information dissemination to professionals and practitioners via web-based tools and databases.