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ARS Home » Southeast Area » Florence, South Carolina » Coastal Plain Soil, Water and Plant Conservation Research » Research » Publications at this Location » Publication #303549
Title: Recovery of ammonia from swine manure using gas-permeable membranes: Effect of waste strength and pH

Author
item GARCIA GONZALEZ, MARIA CRUZ - Institute Of Castilla - Spain
item Vanotti, Matias

Submitted to: Journal of Waste Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/17/2015
Publication Date: 2/2/2015
Publication URL: http://dx.doi.org/10.1016/j.wasman.2015.01.021.
Citation: Garcia Gonzalez, M., Vanotti, M.B. 2015. Recovery of ammonia from swine manure using gas-permeable membranes: Effect of waste strength and pH. Journal of Waste Management. 38:455-461. doi.org/10.1016/j.wasman.2015.01.021.

Interpretive Summary: 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. Bench experiments were conducted using raw liquid swine manure collected from pits in nursery, finishing and sow barns. This provided manures of various strengths (low, medium and high) with ammonia concentrations ranging from 1065 to 2285 milligrams per Liter. As ammonia content increased in manure, more N was captured by the process. The process was optimized by controllling the pH. It recovered more than 80% of the ammonia contained in the raw manure. These results suggested that the new technology is useful for recovering and concentrating the ammonia contained in raw swine manure, reducing environmental pollution potential while converting ammonia into a valuable plant fertilizer.

Technical Abstract: Nitrogen recovery of swine manure was investigated using gas-permeable membranes. The process involved a continuous recirculation of an acidic solution through a tubular gas-permeable membrane submerged in a manure filled vessel. Ammonia contained in manure was concentrated in the acidic solution increasing its pH, while ammonia removal caused a pH decrease in manure. Two batch experiments were performed at lab scale. In the first one, nitrogen recovery efficiency was evaluated with no pH adjustment of manure; whereas in the second experiment, manure with three different ammonia concentrations (ranging from 1065 to 2285 milligrams per Liter.) was used adjusting their pH to 9 when necessary. With no pH adjustment, ammonia recovery from manure was 54.8%, while ammonia recovery averaged 81.9% when pH of manure was adjusted. Moreover, the present work showed that as available ammonia content increased in manure, more N was captured by the membrane process. These results suggested that the gas-permeable membranes are a useful technology for ammonia recovery from manure, reducing environmental pollution whilst converting ammonia into a valuable ammonium salt fertlizer.