Submitted to: Animal Production Systems and the Environment
Publication Type: Proceedings
Publication Acceptance Date: 5/25/1998
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Nitrification is a necessary but often limiting process in animal waste treatment for removal of nitrogen as N2 through biological nitrification/denitrification systems. We evaluated three technologies for enhancing nitrification of swine lagoon wastewater: overland flow, media filter, and a bioreactor using nitrifying pellets. In overland flow, nitrification occurs when a thin film of water is in close contact with a nitrifying population at the soil surface. The system consisted of a 4-x20-m plot with 2% slope receiving a total N loading rate of 64 to 99 kg N/ha/d. Total N removal efficiency ranged from 35 to 42%, and 7% of the total N application was recovered in the effluent as nitrate. A recirculating media filter unit consisted of a 1-m**3 tank filled with marl gravel media which supported a nitrifying biofilm. Lagoon wastewater was applied as a fine spray on the surface using total N loading rates of 249 g m**-3/d. The media filter treatment transformed up to 57% of the inflow total N into nitrate. The new nitrifying pellets technology uses acclimated nitrifying cells immobilized in 3- to 5-mm polymer pellets. Swine wastewater was treated in an aerated fluidized reactor unit with a 15% (w/v) pellet concentration. Nitrification efficiencies of more than 90% and quantitative ammonia removal were obtained in continuous flow treatment using total N loading rates of 438 g N m**-3/d and hydraulic residence time of 12 h. Two conclusions are suggested from this work: (1) that nitrification of lagoon swine wastewater can be attained using aerobic treatments with enriched nitrifying populations; and (2) that large mass removal of N from swine wastewater may be possible by sequencing nitrification and denitrification unit processes.