Denitrification Enzyme Activity in Swine Wastewater Lagoons.

Anaerobic lagoons are commonly used for treatment of swine wastewater.  Although these lagoons were once thought to be relatively simple; their physical, chemical, and biological processes are actually very sophisticated.  Moreover, there are reports of very high levels of di-nitrogen losses from these lagoons.  The objectives were to:  1) quantify denitrification enzyme activity (DEA) in the water column of several commercial anaerobic swine wastewater lagoons; and 2) Evaluate the influence of lagoon characteristics upon the level of DEA.  The DEA was measured by the acetylene inhibition method.  Measurements were taken on eight commercial swine wastewater lagoons from May 2006 to September, 2007.  The levels of DEA measured in these eight commercial lagoons were not consistent with high rates of denitrification (< 100 mg N₂O m^-3 d^-1).  No particular lagoon characteristic was predictive of DEA levels. Further research is needed in order to correlate microbial community structure with biological processes.  Such insights will allow for a better understanding of the nitrogen cycling process of swine wastewater lagoons.