University of Arkansas
Ralph E. Martin Department of Chemical Engineering
3202 Bell Engineering Center
Fayetteville, AR 72701-1201
Phone: (479) 575-4951
Fax: (479) 575-7926
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.