Runoff from crops can lead to excess nitrogen and phosphorous nutrients in wastewater systems. Lynn Betts, USDA
Runoff from crops can lead to excess nitrogen and phosphorous nutrients in wastewater systems.

Project to create commercial fertilizer out of wastewater nutrients

Goal of project is to make energy-efficient fertilizer that competes with conventional, commercially available fertilizers.

A $2.4 million award from the National Science Foundation will enable a multidisciplinary team of researchers at the University of Arkansas and their colleagues at two other institutions to develop a chemical process that converts nitrogen and phosphorous from wastewater into commercial fertilizer.

The goal of the project is to make an energy-efficient fertilizer that competes with conventional, commercially available fertilizers.

“Excess nitrogen and phosphorous in wastewater, due primarily to human impact, cause serious environmental problems,” said Lauren Greenlee, assistant professor of chemical engineering and the lead principal investigator for the project. “We’re engineering a technology that takes these nutrients from the environment and recycles them, turning them into a commercial product that is energy efficient and environmentally less harmful to produce.”

The technology is based on the same general concept that has been used to develop commercialized fuel cells and electrolyzers, wherein two electrodes are separated by a membrane, which allows for controlling the reactions taking place and the flow of electricity in and out. The researchers will design electrodes to precipitate fertilizer “struvite,” a crystallized mineral composed of magnesium, ammonium and phosphate. The researchers will then collect the struvite in particulate form.

The electrochemical-engineering team consists of principal investigators Greenlee, Andrew Herring at the Colorado School of Mines and Julie Renner at Case Western Reserve University. They will focus on electrode design, water chemistry, electrochemical operations, struvite precipitation and the engineering of a bench-scale reactor design.

The three other principal investigators are all from the University of Arkansas: Greg Thoma, professor of chemical engineering; Jennie Popp, professor of agricultural economics and agricultural business, and Kristofor Brye, professor of applied soil physics and pedology. Thoma will develop a life-cycle assessment of the proposed technology; Popp will examine the economics of implementing the technology, and Brye will study the composition, chemistry and viability of the fertilizer struvite created by the engineering team, comparing it to commercial fertilizers.

Greenlee said the project seeks to engage the local and regional community on issues related to nutrient recycling. Each year of the project, the researchers will host a workshop at the University of Arkansas and will invite regional stakeholders from across the food supply chain to discuss challenges and form partnerships among stakeholders.

“We want to develop an understanding of the needs and opportunities regarding food production, water conservation and nutrient recycling,” Greenlee said.

The project will support the education and training of six full-time graduate students, one post-doctoral researcher and multiple undergraduate researchers.

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