Collaborative research: impact of wastewater derived organic nitrogen on eutrophication

0932665/0932632 Gu/PARL许多城市污水处理设施面临着越来越严格的出水氮限制，接近或超过了当前的技术限制。如果允许的氮水平低于常规脱氮技术的极限，则需要去除溶解的有机氮(DON)。研究和安装进一步去除残留DON的先进处理技术所需的资本成本是巨大的。目前的法规使用总氮来设定限制，没有考虑到DON和无机氮对浮游植物的生物有效性可能不同，因此它们对接收水生系统的潜在有害影响。考虑到废水DON(WwDON)生物可利用性的不确定性，进一步减少DON是否会带来相对于所产生的巨大成本的实质性环境效益的问题出现了。目前，关于WWDON对接收水中浮游植物的生物有效性的信息很少，也没有公认的定量评估WWDON生物有效性的方法。这项研究建议解决这一问题，填补在了解废水衍生有机氮对接受水生态系统的影响方面的知识空白。这项研究旨在调查市政处理设施中WWDON的特征，评估WWDON对浮游植物的生物有效性及其对富营养化的影响。尽管氮在咸水中通常是有限的，但咸水和淡水在这里都受到关注，因为大多数市政当局向淡水排放氮，而且最近的研究表明，上游淡水系统中氮的去向和不稳定最终将影响下游对氮敏感的河口和海岸系统中氮的运输和营养状况。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利用度。2.研究了WWDON对盐生浮游植物和淡水浮游植物的生物有效性，以及细菌在WWDON对藻类稳定作用中的作用。3.研究WWDON的组成与生物利用度之间的关系，确定WWDON的生物利用度与顽固性之间的关系。4.利用原位合成的15N标记的wwDON，进一步评价wwDON在自然生物群(包括藻类和细菌)中的去向和生物有效性。该项目将展示跨学科和综合方法在解决环境挑战方面的好处。这项多学科研究涵盖了至少三个学科的专业知识，这些学科将对淡水水生系统中WWDON的生物有效性进行独特、全面和最先进的评估。拟议的研究解决了一个具有重大社会和经济影响的紧迫问题，这一问题以前从未被调查过。研究结果将为开发公用事业和监管机构迫切需要的标准WWDON生物利用度评估方法提供必要的信息和框架，以便将他们的处理设计和投资集中于消除对水生生态系统真正有害的N组分，从而实现环境效益的最大化。该项目将加强这两个机构现有的和新的教育推广计划。在NU，有BEST(环境生物技术，展示和培训)，这是Gu最近发起的一个中心；Connections和RET，两个NSF资助的教育项目；以及Co-op，NU的一个杰出的体验式学习项目。在北卡罗来纳大学，有NSF支持的(生态系统、EID和海洋科学计划)在UNC-IMS的暑期实习和NSF支持的暑期研究生前研究体验计划(SPGRE)。所有这些项目都旨在吸引和参与来自不同背景的学生。该协会启动了ITRI(工业转化研究计划)，并将与WEF/WERF(水环境联合会)合作，通过基于网络的工具和数据库向专业人员和从业者传播信息

0932665/0932632 Gu/Paerl Many 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