Increasingly, large-scale animal production occurs in confinement where large 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 volatilization of free ammonia (NH{sub}3) governs nitrogen removal in these systems. The objective of this research was to quantify the NH{sub}3 volatilization from constructed wetlands that treat swine wastewater In May and July of 2000, a specially designed enclosure was used to measure NH{sub}3 volatilization from constructed wetlands receiving swine wastewater Laboratory and field calibration tests indicated that the enclosure was effective at measuring NH{sub}3 volatilization. Wetland tests indicated that NH{sub}3 volatilization was occurring. From average hourly rates, it was estimated that 7 to 16 of the nitrogen load to the wetlands was removed through NH{sub}3 volatilization. Although NH{sub}3 losses should not be ignored, results indicated that NH{sub}3 volatilization was not responsible for removing the majority of nitrogen from the swine wastewater.
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