NSF Project Summary

This project is supported by the Innovations at the Nexus of Food, Energy, and Water (INFEWS) Program. It addresses the lack of nutrient recycling from wastewater streams and the resulting strain on water resources, energy use, and sustainable food supply. Two key nutrients, nitrogen (N) and phosphorus (P), are critical for all life on Earth, including humans, animals, and plants. Worldwide, phosphorus supply comes from limited stores of phosphate rock. Nitrogen comes from the energy- and capital-intensive industrial Haber-Bosch process that makes ammonia. Phosphorus and nitrogen are transported from fertilizers and human and animal waste to wastewaters via agricultural run-off. There is an important opportunity for nutrient recovery and reuse rather than treatment and disposal. This project develops innovative engineering technology to recycle nitrogen and phosphorus nutrients as a high-value fertilizer, struvite, while also enabling energy-efficient wastewater treatment. The technology is developed within the context of an economic life cycle analysis. In terms of broadening participation, a stakeholder-driven workshop takes place yearly. In addition to lower energy use and increased nitrogen and phosphorus recycling, the benefits are cleaner water, healthier watersheds, and sustainable agricultural activities. Numerous undergraduate and graduate students receive training in an interdisciplinary context.

Over-fertilization and excess ammonia production in addition to a lack of nutrient recycling contribute to an imbalanced N/P cycle. This situation leads to water contamination issues, decreased agricultural viability in nutrient-saturated watersheds, and excessive energy use. This research project addresses the problem with an electrochemical reactor that recovers N and P as struvite, a slow-release fertilizer. An electrochemical reactor is designed to study kinetics and flow dynamics of struvite precipitation. This reactor is designed to be energy-efficient with high potential for on-site power generation. Key electrochemical components, including the magnesium alloy anode and a functional peptide scaffold for accelerated struvite precipitation are developed. The peptide-functionalized mesh is designed to enhance struvite precipitation kinetics and purity. The energy requirements for this process are evaluated and the economic costs and benefits of the new technology are determined. The project also addresses the impact of struvite composition and morphology on soil composition and crop fertility, studies the efficacy of struvite as a fertilizer, and develops a life cycle assessment of the technology including a system energy balance. For application to municipal wastewater treatment facilities, the technology integration is evaluated in terms of scalability, water quality/liquid composition, and cost-effectiveness.