ARS | Publication request: AMMONIA VOLATILIZATION FROM CONSTRUCTED WETLANDS THAT TREAT SWINE WASTEWATER

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 3, 2002
Publication Date: June 1, 2002
Citation: POACH, M.E., HUNT, P.G., SADLER, E.J., MATHENY, T.A., JOHNSON, M.H., STONE, K.C., HUMENIK, F.J., RICE, J.M. AMMONIA VOLATILIZATION FROM CONSTRUCTED WETLANDS THAT TREAT SWINE WASTEWATER. TRANSACTIONS OF THE AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS. 2002. V. 45. P. 619-627.

Interpretive Summary: Animal production is a major component of agriculture in the USA. It is vital to both food stability and economic health. Increasingly, large-scale animal production occurs in confinement where enormous per-unit-area quantities of waste are generated. With the increased scale of production, new technologies are needed to deal with the waste. Constructed wetlands are considered an alternative treatment because they are operationally simple and because treatment is achieved through natural processes. However, one natural process that may occur is ammonia volatilization because animal waste is high in ammonia. Ammonia volatilized to the atmosphere can cause acid rain and, with redeposition, the overfertilization of natural systems. A study on constructed wetlands that treat swine wastewater found that a relatively small amount of ammonia volatilization was occurring. Therefore, ammonia volatilization was not the dominant nitrogen loss mechanism in these wetlands. The major treatment mechanism seems to be the process of nitrification-denitrification where nitrogen is returned to the atmosphere as harmless dinitrogen. Constructed wetlands as a component of a total wastewater treatment system offer an acceptable treatment alternative to animal waste lagoons.

Technical Abstract: Increasingly, large-scale animal production occurs in confinement where enormous per-unit-area quantities of waste are generated. With the increased scale of production, new environment-friendly technologies are needed to deal with the waste. Constructed wetlands are considered an alternative treatment, but it is not known if ammonia volatilization governs nitrogen removal in these systems. The objective of this research was to quantify the ammonia volatilization from constructed wetlands treating swine wastewater. In May and July of 2000, a specially designed enclosure was used to measure ammonia volatilization from constructed wetlands receiving swine wastewater. Laboratory and field calibration tests indicated that the enclosure was effective at measuring ammonia volatilization. In wetland tests, 7 to 16% of the nitrogen load (16 to 53 kg N/ha/day) was removed through volatilization, and volatilization accounted for 12 to 33% of nitrogen removed by the wetlands. Although ammonia losses should not be ignored, results indicated that ammonia volatilization was not a dominant mechanism for nitrogen loss from these wetlands.