Submitted to: Recycling of Agricultural Municipal and Industrial Residues
Publication Type: Proceedings
Publication Acceptance Date: May 27, 1998
Publication Date: N/A
Technical Abstract: Environmental pollution from animal waste is a major concern in the U.S.A. due to the rapid growth of confined animal production. Liquid swine manure is mostly treated and stored in anaerobic lagoons before land application. For storage periods of 180 days typical of the Southeast, more than 50% of the nitrogen (N) entering the lagoon is lost by ammonia volatilization. Its subsequent deposition across the landscape may be the largest form of N non-point source pollution in the region. A possible solution is to remove ammonia using nitrification-denitrification systems. In order to overcome low nitrification rates in swine wastewater, we evaluated a new technology that uses immobilized nitrifying bacteria. The technology has been successfully applied to municipal wastewater treatment providing higher nitrification rates, shorter hydraulic residence times (HRT), and smaller reactors. Acclimated nitrifying cells were immobilized in 3- to 5-mm polyvinyl alcohol polymer pellets. Swine wastewater was treated in aerated, fluidized bioreactors with a 15% (w/v) pellet concentration using batch and continuous flow treatment. In batch treatment, 14 h were needed for total nitrification of ammonia-N (approx. 250 mg N/L). In contrast, it took 10 d for a control (no-pellets) aerated reactor to start nitrification, and 69% of ammonia-N was lost by air stripping. In continuous flow treatment, ammonia removal efficiencies of more than 90% were obtained with ammonia loading rates of 418 mg N/L/d and HRT of 12 h. The rate of nitrification obtained with HRT of 4 h was 604 mg N/L/d. The high nitrification rates obtained in this work indicate that the immobilized nitrifiers technology has potential application for reducing ammonia loss from confined animal production.