Submitted to: Recycling of Agricultural Municipal and Industrial Residues
Publication Type: Proceedings
Publication Acceptance Date: 4/15/2008
Publication Date: 6/11/2008
Citation: Hunt, P.G., Matheny, T.A., Ro, K.S., Vanotti, M.B., Reddy, G.B. 2008. Denitrification enzyme activity in swine wastewater lagoons. p. 433-436. In: Proceedings of Recycling of Agricultural Municipal and Industrial Residues (RAMIRAN) 13th International Conference, June 2008, Albena, Bulgaria.
Technical Abstract: Anaerobic lagoons are typically used for treatment of swine wastewater. Although these anaerobic lagoons were once thought to be relatively simple in their physical, chemical, and biological processes, they are actually very sophisticated. Recent reports of high levels of di-nitrogen emissions and high levels of potential surficial oxygen transfer indicated that large amounts of nitrogen may be removed via denitrification in these anaerobic lagoons. While specific lagoon characteristics vary with design, geographic location, time of year, and loading rates, conditions are generally thought to be favorable for some type and level of denitrification. If classical denitrification is occurring in these lagoons, the denitrification enzyme levels should be correspondingly high. Our objective was to quantify denitrification enzyme activity (DEA) in several lagoons. The DEA was measured by the acetylene inhibition method on eight commercial swine wastewater lagoons. Wastewater samples were taken at four quadrants of each lagoon from the surface, midway to the bottom, and just above the bottom of the lagoon. Although lagoons have significant surficial oxygen transfer to potentially produce precursors for denitrification, there was very little DEA measured in these eight commercial lagoons. The oxygen in these commercial lagoons may have been used to oxidize BOD. Also, the oxygen might have been used to form precursors that supported alternate nitrogen removal processes such as ANAMMOX. Further research needs to be conducted on DEA, enzyme activation, and microbial communities from lagoons in order to better understand the nitrogen cycling process of swine wastewater lagoons.