|Nakaoka, M. - INDUS. TECH. CEN., JAPAN|
|Odamura, S. - KUMAMOTO UNIV., JAPAN|
Submitted to: ASAE Annual International Meeting
Publication Type: Proceedings
Publication Acceptance Date: July 19, 1999
Publication Date: N/A
Technical Abstract: Nitrification of ammonia is a critical component for improved systems of animal wastewater treatment. One of the most effective nitrification processes uses nitrifying microorganisms encapsulated in polymer resins. We adapted this technology for high-ammonia wastewaters by using acclimated microorganisms. High-ammonia nitrifying bacteria (HANB) were successfully immobilized in 3- to 5-mm polyvinyl alcohol (PVA) polymer pellets. Swine wastewater containing 350 to 2600 mg N/L was treated in aerated, suspended bioreactors using batch and continuous flow treatment. In batch treatment, ammonia removal rates of 38 to 41 mg-N/L-reactor/h (915 to 990 mg-N/L-reactor/day) were obtained with 97 to 100% nitrification efficiency. In continuous flow, efficiencies >80% were obtained with ammonia loading rates <1000 mg N/L-reactor/d and HRT of 24 to 48 h. All of the ammonia-N removed was entirely recovered in oxidized N forms. Comparison between a single reactor vs. two or three reactors in series showed that there is no advantage to using the plug-flow regime. Our results indicated that the process pH is important for optimization of nitrification in high-ammonia wastewaters and that improper selection may result in 50% decrease in performance. Optimum nitrification performance was obtained when the pH was controlled at 8.5. Our results also indicated that immobilized HANB pellets were not inhibited by high-ammonia concentration in the range of 350 to 2600 mg N/L and that both ammonia and NO2**- oxidizers entrapped in these pellets operated simultaneously providing fast and complete nitrification. The results of this study indicate the HANB pellets are a useful technology for fast and efficient nitrification treatment of high-ammonia animal wastewaters.