New Technique Efficiently Extracts Fertilizer Nutrients from Livestock Manure

The innovative method uses a nickel-based electrode to recover ammonia and potassium, potentially reducing environmental pollution and operational costs for farmers.

• An interdisciplinary team led by Wisconsin-Madison scientists has developed a new technique to extract useful nutrients such as ammonia and potassium from livestock manure to efficiently make fertilizer and other useful chemical products.
• 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 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.
• Trial runs with small amounts of manure recovered more than half the ammonia in the first pass, with a recovery of about 85% after two cycles.
• A preliminary technical economic analysis shows that a model dairy farm using the system could expect resulting revenues to be higher than operating costs, so long as electricity prices aren't exorbitant.

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