AMMONIA VOLATILIZATION FROM CONSTRUCTED WETLANDS THAT TREAT SWINE WASTEWATER

Abstract

Increasingly, largescale animal production occurs in confinement where large perunitarea quantities of wasteare generated. With the increased scale of production, new environmentfriendly technologies are needed to deal with thewaste. Constructed wetlands are considered an alternative treatment, but it is not known if volatilization of free ammonia(NH3) governs nitrogen removal in these systems. The objective of this research was to quantify the NH3 volatilization fromconstructed wetlands that treat swine wastewater. In May and July of 2000, a specially designed enclosure was used tomeasure NH3 volatilization from constructed wetlands receiving swine wastewater. Laboratory and field calibration testsindicated that the enclosure was effective at measuring NH3 volatilization. Wetland tests indicated that NH3 volatilizationwas occurring. From average hourly rates, it was estimated that 7% to 16% of the nitrogen load to the wetlands was removedthrough NH3 volatilization. Although NH3 losses should not be ignored, results indicated that NH3 volatilization was notresponsible for removing the majority of nitrogen from the swine wastewater.