An interdisciplinary team led by University of Wisconsin-Madison scientists has developed a new technique that could help farmers extract useful nutrients such as ammonia and potassium from livestock manure to efficiently make fertilizer and other useful chemical products. While the strategy still needs to be scaled up beyond a proof-of-concept stage, the group's preliminary analyses show it could offer considerable benefits by cutting water and air pollution while simultaneously creating products that farmers could use or sell.
Researchers around the world are hunting for strategies to efficiently recover ammonia from manure, creating more concentrated and valuable fertilizers that are greener and more affordable to transport. Among these strategies are chemical processes driven by electricity, which is becoming increasingly inexpensive in many rural communities thanks to growing solar and wind power generation. However, most electrochemical techniques in development are not yet practical, mainly because they consume a lot of energy and aren't efficient enough at pulling dissolved ammonia (in the form of ammonium ions) out of manure.
This new technique, described in the 8 December 2023 paper published in the journal Nature Sustainability, relies on a specially designed electrode, like those used for batteries, that targets ammonium ions. The technique involves a nickel-based electrode that is placed directly into the manure wastewater. As organic matter in the manure naturally gets oxidized by the electrode, the ammonium, as well as potassium ions, within the wastewater are selectively driven into and captured by the electrode. The strategy does not end with simply removing the nutrients from the wastewater.
In an innovative step that could help make the process even more attractive, the nutrient-loaded electrode is then placed into a device that uses electricity to release the recovered ammonium and potassium ions, which can then be used to make nitrogen and potassium-based fertilizers, and simultaneously produce other useful chemical products.
(Source: Agriculture and Food News, ScienceDaily. www.sciencedaily.com)
