Recovery of ammonia from poultry litter using gas-permeable membranes

Authors: Rothrock, Michael; Szogi, Ariel; Vanotti, Matias

Submitted to: American Society of Agricultural and Biological Engineers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2010
Publication Date: 9/20/2010
Citation: Rothrock Jr, M.J., Szogi, A.A., Vanotti, M.B. 2010. Recovery of ammonia from poultry litter using gas-permeable membranes. Transactions of the American Society of Agricultural and Biological Engineers. 53(4):1267-1275.

Interpretive Summary: Gaseous ammonia released from poultry production into the air is of environmental concern both for human and bird health. Continued exposure to ammonia in poultry houses leads to declining bird health and production. To alleviate these problems, we developed a new process that uses gas-permeable membranes to remove ammonia from the air inside the poultry house. In this process, gaseous ammonia passes through a membrane and is captured on the other side by a diluted acid solution. In a bench-scale prototype test, 96% of the ammonia released by poultry litter was captured. Because membranes can be configured in either tubular or flat modules, they can be placed close to the litter surface, reducing the exposure of birds to ammonia. Given that the ammonia is captured inside the houses, the process could reduce both ventilation needed to maintain air quality and associated ventilator-energy requirements. This study demonstrates that gas-permeable membrane technology can effectively recover ammonia from poultry litter and possibly other livestock operations. The benefits of this recovery are both cleaner air and captured concentrated liquid nitrogen that can be re-used as fertilizer.

Technical Abstract: The removal and recovery of gaseous ammonia from poultry litter can benefit bird health/productivity and reduce environmental concerns of emissions from poultry production. We investigated the potential use of gas-permeable membranes as components of a new process to capture and recover ammonia in poultry houses. This process includes the passage of gaseous ammonia through a microporous hydrophobic membrane and capture with a circulating diluted acid on the other side of the membrane and production of a concentrated ammonium salt. The membranes can be assembled in modules or manifolds and can be tubular or flat. In bench-scale prototype testing using tubular expanded polytetrafluoroethylene (ePTFE) membranes and a 1N acidic solution, the technology captured and recovered 96% of the ammonia lost from poultry litter. The recovery of ammonia could mimic the slow release during flock production or could be accelerated to a few days using hydrated lime amendments. The membrane manifolds can be placed close to the litter surface (above or below), reducing the exposure of the birds to ammonia. Considering the ammonia is captured inside the houses, this technology could help reduce ventilation and energy needs to lower ammonia levels in poultry houses. The results obtained in this study show that the use of gas-permeable membrane technology could be an effective approach to recover ammonia from poultry litter and other livestock operations. The final products are (1) cleaner air inside the poultry houses with benefits to bird health and reduced environmental emissions, and (2) a concentrated liquid nitrogen that can be re-used in agriculture as a valued fertilizer.