Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/31/2015
Publication Date: 3/31/2015
Citation: Vanotti, M.B., Garcia-Gonzalez, M.C., Dube, P.J., Szogi, A.A. 2015. Improved recovery of ammonia from swine manure using gas-permeable membrane technology and aeration. In: Proceedings of Waste to Worth: Advancing Sustainability in Animal Agriculture. Livestock and Poultry Environmental Learning Center, March 30-April 3, 2015, Seattle, Washington. http://articles.extension.org/pages/72883/improved-recovery-of-ammonia-from-swine-manure-using-gas-permeable-membrane-technology-and-aeration.
Technical Abstract: Significant efforts are required to abate ammonia emissions from livestock operations. In addition, the costs of fertilizers have rapidly increased in recent years, especially nitrogen fertilizer such as anhydrous ammonia which is made from natural gas. Thus, new technologies for abatement of ammonia emissions in livestock operations are being focussed on nitrogen (N) recovery. Nitrogen recovery from swine manure was investigated using a new technology that uses gas-permeable membranes at low pressure. Membrane manifolds are submerged in the manure and the ammonia is removed from the liquid before it escapes into the air. The process involves manure pH control to increase ammonium recovery rate that is normally carried out using an alkali chemical. In this study a new strategy was tested to avoid the use of alkali chemicals. Instead of the chemical, we applied low-rate aeration and nitrification inhibitor to raise the pH and promote ammonia capture by the membrane system. Two studies were conducted to recover N from liquid swine manures containing high ammonia concentrations using a USDA patented gas-permeable membrane system. One study used raw liquid manure from the pit under slatted floor of a farrowing sow’s barn in Segovia, Spain. The second study used liquid swine manure effluent from a covered lagoon digester in North Carolina, United States of America. The new strategy worked quite well in both situations. In the first study using raw manure, ammonium concentration was almost depleted: it declined from 2270 to 20 milligrams N per litre. The ammonia that was removed was recovered efficiently in the concentrator tank (99 percent recovery efficiency). The results obtained were consistent in the second study that used digested swine effluent. The ammonium concentration in the digester effluent decreased rapidly, from 3130 to 96 milligrams N per litre, in 5 days. The recovery efficiency was 98 percent. With the aeration protocol the rate of nutrient recovery was 5 times faster compared to a control that used the same membrane reactor and conditions but operated without the aeration protocol. Overall results obtained in this research indicate the low-rate aeration is an economical alternative to chemical addition to increase ammonia availability and the capture of ammonia by gas-permeable membrane systems. This conclusion is supported by the very high removal and recovery efficiencies obtained resulting in an overall recovery of 95 to 98% of the initial ammonia in the manure.