Intermittently aerated reactors have been successfully used for nitrogen removal from digested swine manure by achieving complete nitrification during aerated periods, followed by denitrification during nonaerated periods (9, 30). Digested swine manure usually contains high ammonia concentrations and a low carbon/nitrogen ratio. These characteristics impose challenges for the traditional nitrification/denitrification approach due to (i) the high oxygen demand for complete nitrification of ammonia to nitrate and (ii) the relatively low organic substrate content available for complete denitrification. Intermittently aerated reactors can potentially be optimized if used to perform partial nitrification followed by denitrification via nitrite, resulting in reduced oxygen demand for ammonia removal and reduced organic substrate for denitrification. We hypothesized that aeration cycles with sufficiently short aerated periods or sufficiently long nonaerated periods can provide appropriate conditions for partial nitrification and denitrification via nitrite. In the present study, we assessed the effects of different aeration cycles on nitrogen removal performance and the community compositions of AOB
and NOB by using amoA DGGE and quantitative slot blot hybridizations based on 16S rRNA.