USDA patents manure emissions process
WASHINGTON – Researchers with the US Department of Agriculture’s Agricultural Research Service (ARS) have invented a device that captures and recycles ammonia from livestock waste. ARS believes the device could help streamline on-farm nitrogen management by reducing potentially harmful ammonia emissions and concentrating nitrogen in a liquid product that can be sold as fertilizer.
The system uses gas-permeable membranes, according to the agency. ARS scientists recorded an average removal rate from 45 to 153 milligrams of ammonia per liter per day when manure ammonia concentrations ranged from 138 to 302 milligrams of ammonia per liter. ARS said that when manure acidity decreased, ammonia recovery increased.
In a follow-up study ARS scientists immersed the device into liquid manure that had 1,290 milligrams of ammonia per liter. After nine days, the total ammonia concentration decreased approximately 50 percent to 663 milligrams per liter and acidity increased from pH 8.1 to 7.0.
The work was conducted by ARS scientists Matias Vanotti and Ariel Szogi at the agency's Coastal Plains Soil, Water and Plant Research Center in Florence, SC.