Effect of acid flow rate, membrane surface area, and capture solution on the effectiveness of suspended GPM systems to recover ammonia

Authors: SOTO-HERRANZ, MARIA - UNIVERSITY OF VALLADOLID; SANCHEZ-BASCONES, MERCEDES - UNIVERSITY OF VALLADOLID; ANTOLIN-RODRIGUEZ, JUAN - UNIVERSITY OF VALLADOLID; Vanotti, Matias; MARTIN-RAMOS, PABLO - UNIVERSITY OF ZARAGOZA

Submitted to: Membranes
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2021
Publication Date: 7/16/2021
Citation: Soto-Herranz, M., Sanchez-Bascones, M., Antolin-Rodriguez, J., Vanotti, M.B., Martin-Ramos, P. 2021. Effect of acid flow rate, membrane surface area, and capture solution on the effectiveness of suspended GPM systems to recover ammonia. Membranes [MDPI]. ll(7):538. https://doi.org/10.3390/membranes11070538.
DOI: https://doi.org/10.3390/membranes11070538

Interpretive Summary: Animal production is one of the largest contributors to gaseous ammonia (NH3) emissions. Ammonia emissions contribute to ecosystem degradation when it is deposited on land or water with corresponding soil acidification and eutrophication of surface water bodies. A European Union LIFE project Ammonia Trapping (AT) was designed to recover gaseous ammonia from animal barns in Spain farms. The main objective of the AT project was to reduce NH3 emissions from the atmosphere of swine and poultry farms by using gas-permeable membrane (GPM) technology. The NH3 present in the air passes through the wall of the GPM and is captured by an acid solution that circulates on the other side to form a fertilizing salt (ammonium sulfate). Targets in the AT project were a reduction in the NH3 concentration of 70 percent of or higher, and rates of ammonia trapping of 1.3 g N per square meter of membrane per day. The lack of studies about the efficiency of GPM materials with different surface areas and acid flow rates to capture of NH3 from the air prompted this laboratory study. The process responded to increased membrane surface area and also to increased acid recirculation rates. Therefore, to optimize the effectiveness of a GPM system to capture gaseous ammonia, the membrane surface area and the velocity of the circulating acidic solution should be important design considerations.

Technical Abstract: The loss of ammonia through volatilization on farms creates problems for ecosystems and human and animal health. The application of ammonia capture systems using gas-permeable membranes on farms can reduce the levels of ammonia pollution in the atmosphere. In this study, two laboratory experiments were carried out to evaluate the effect of acid flux, nitrogen (N) concentration at the emission source, and gas permeable membrane surface on ammonia recovery from the gas phase. In the first experiment, the effect of two surfaces (81.7 and 163.4 square centimeters) was evaluated when using different concentrations of synthetic N emitting solution (3000, 6000 and 12000 mg ammonia N per liter) and the same flow of acidic solution, 0.8 liters per hour. In the second experiment, the capture of ammonia was studied using different acid flow rates (0.8, 1.3, 1.6, 2.1 liters per hour) and a synthetic N emitting solution with a concentration of 6000 mg ammonia N per liter and a surface area of 122.5 square centimeters. Ammonia was released from a synthetic solution, and an acidic solution was used as ammonia capture solution. The increase in the surface area of the membrane increased the capture of ammonia, but the process was limited at the highest N emitting solution concentration. however, higher acid flow rates in the second experiment resulted in a higher ammonia capture.