EFRI DCheM: Re-Engineering the Nitrogen Cycle: Distributed Electrochemical Nitrogen Refineries for Ammonia Synthesis and Water Purification

氮污染是美国国家科学院确定的一项重大挑战。化肥生产已经超过了废水中氮的去除，导致持续的损失，威胁到水生生态系统和人类健康。该项目旨在通过将水中的氮污染物回收到高纯度氨中来应对这一挑战。PIs方法的独特之处在于，它能够减少氮排放及其负面级联效应；降低传统化肥生产和废水处理的能源和成本；以及解决可能在墨西哥湾等沿海生态系统中持续数十年的遗留污染问题。EFRI分布式化学制造研究项目的总体目标是了解、设计和控制多功能电化学过程，以最大限度地减少对环境的影响，实现现场化肥制造和水净化。该项目结合了在新材料和工艺方面的根本性突破，将废水污染物转化为产品。该项目包括将基本发现与各种废水的成本优化和性能相结合，以及为回收设施确定采用地点和价值主张的优先顺序。因为重新设计氮循环是一项艰巨的挑战，它需要整个美国人才库的最佳方法。因此，项目团队计划通过在斯坦福大学试点规模的水处理厂举办年度研讨会和演示日来扩大参与范围，并邀请代表人数不足的K-12学生、当地社区成员、本科生研究人员以及代表化肥生产、农业和水处理的项目产业顾问委员会。该团队还将为未被充分代表的本科生开设研讨会，在课堂上开展动手实验活动，为K-12学生开发以氮为重点的模块，并为高中和本科EFRI奖学金学生提供指导研究经验。目前，重新平衡氮循环的工程努力主要集中在改进Haber-Bosch工艺以生产氨或扩大从废水中去除氮。该项目提出了一个变革性的愿景：在分布式氮炼厂回收活性氮(例如氨、硝酸盐)，将废水中的逃逸排放转化为高纯度的氨。这项研究的总体目标是了解、设计和控制多功能电化学单元工艺，使分布式氨生产和水净化对环境的影响降至最低。该项目将利用电渗析和硝酸盐还原作为平台，对氨选择催化剂以及适用于两种普遍存在的废水：城市废水和化肥径流的处理工艺进行基准测试和表征。该项目的目标是：(1)通过选择性电化学反应分离了解和控制电催化微环境；(2)为能效、成本效益和适应性工艺建立量化的材料和工艺创新目标；以及(3)利用经济和环境评估来优先考虑废水衍生氨制造的当地背景和产品。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。

Nitrogen pollution is a Grand Challenge identified by the National Academies. Fertilizer production has outpaced removal of nitrogen from wastewater, leading to continuous losses that threaten aquatic ecosystems and human health. This project aims to meet this challenge by recycling waterborne nitrogen pollutants into high-purity ammonia. The PIs’ approach is unique in its ability to reduce nitrogen emissions and their negative cascade effects; reduce the energy and costs of conventional fertilizer production and wastewater treatment; and address legacy pollution that can persist for decades in coastal ecosystems like the Gulf of Mexico. The overall goal of this EFRI Distributed Chemical Manufacturing research project is to understand, design, and control multifunctional electrochemical processes that enable on-site fertilizer manufacturing and water purification with minimal environmental impacts. The project combines fundamental breakthroughs in novel materials and processes to convert wastewater pollutants into products. The project includes integration of the fundamental discoveries with cost optimization and performance in various wastewaters, as well as prioritizing adoption locations and value propositions for recovery facilities. Because re-engineering the nitrogen cycle is a demanding challenge, it requires the best approaches from the entire U.S. talent pool. Thus, the project team plans to broaden participation by hosting an annual workshop and demonstration day at a Stanford pilot-scale water treatment plant and invite underrepresented K-12 students; local community members; undergraduate researchers; and the project’s industrial advisory board representing fertilizer production, agriculture, and water treatment. The team will also develop workshops for incoming underrepresented undergraduate students, hands-on lab activities in classes, nitrogen-focused modules with K-12 students, and mentored research experiences for high school and undergraduate EFRI Scholars.Current engineering efforts to rebalance the nitrogen cycle have largely concentrated on the improvement of the Haber-Bosch process to produce ammonia or expansion of nitrogen removal from wastewater. This project puts forward a transformative vision: recycling reactive nitrogen (e.g., ammonia, nitrate) in distributed nitrogen refineries that convert fugitive emissions in waste waters into high-purity ammonia. The overall goal of the research is to understand, design, and control multifunctional electrochemical unit processes that enable distributed ammonia manufacturing and water purification with minimal environmental impacts. The project will utilize electrodialysis and nitrate reduction as a platform to benchmark and characterize ammonia-selective catalysts, as well as a treatment process applicable to two ubiquitous wastewaters: municipal wastewater and fertilizer runoff. The project’s objectives are to: (1) understand and control electrocatalytic microenvironments via selective electrochemical reactive separations; (2) establish quantitative material and process innovation targets for energy-efficient, cost-effective, and adaptive processes; and (3) leverage economic and environmental assessments to prioritize local contexts and products for wastewater-derived ammonia manufacturing.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.