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Researchers use electricity to separate nutrients, chemicals from manure

Photo: Lab showing separation of nutrients from manure by Rui Wang/University of Wisconsin

New research at the University of Wisconsin shows farmers might someday be able to extract several valuable products from manure.

Chemistry researcher Song Jin tells Brownfield that by energizing a special electrode, ammonia and potassium can be separated from manure and then reused for fertilizer while preventing nitrates and other nutrients from contaminating ground and surface water.  Jin says this could potentially save farmers money and generate additional revenue. “In the most optimal condition right now, our estimate, which is very preliminary, says that for a 1,000 cow farm, you can make up to about $200,000 a year out of this process.”

Also, Jin says it’s possible farmers could benefit from the other elements extracted from manure using the same process. “But on top of that, we also take that electrode, we combine that with another reaction to generate some other useful chemicals. This can be fuels like hydrogen, or it can be disinfectant like hydrogen peroxide which you can use to treat wastewater.”

The process uses a nickel-based electrode that is placed directly into the manure wastewater. As organic matter in the manure gets oxidized by the electrode, the ammonium and potassium ions are selectively driven into and captured by the electrode. Then, the nutrient-loaded electrode is 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.

Jin says much more research will be needed to determine if the process can be feasible on a large scale on a farm, but he’s hoping to get the funding to find out.