The anammox process was applied to treat urban landfill leachate coming from a previous partial nitritation process. In presence of organic matter, the anammox process could coexist with heterotrophic denitrification. The goal of this study was to asses the stability of the anammox process with simultaneous heterotrophic denitrification treating urban landfill leachate. The results achieved demonstrated that the anammox process was not inactivated by heterotrophic denitrification. Moreover, part of the nitrate produced by anammox bacteria and part of the influent nitrite were removed by heterotrophic denitrifiers with associated biodegradable organic matter consumption. In this sense, the contribution on nitrogen removal of each process was calculated using a nitrogen mass balance methodology. An 85.1+/-5.6% of the nitrogen consumption was achieved via anammox process while the average heterotrophic denitrifiers contribution was 14.9+/-5.6%. Heterotrophic denitrification was limited by the available easily biodegradable organic matter.
IWA Publishing 2008.