Landfill Leachate Treatment Using a Combination of Heterotrophic Denitrification and Partial Nitritation in a Single Sequencing Batch Reactor

The combination of heterotrophic denitrification and partial nitritation for the treatment of landfill leachate was investigated in a single sequencing batch reactor with the objective of achieving simultaneous elimination of nitrogen and organic matter and providing a suitable effluent for the subsequent anaerobic ammonium oxidation (Anammox) treatment. Partial nitritation was established by finely adjusting the airflow rate (AFR) and the influent loading rate (ILR) to an oxygen-limiting condition. The long-term operation of the batch reactor showed that more than 55% removal of the chemical oxygen demand (COD) and 60% elimination of total nitrogen (TN) were obtained. Cycle analysis showed that heterotrophic denitrification contributed to approximately 28% reduction of nitrogen and 24% reduction of COD in the bulk liquid. This study showed that the treatment capacity increased with the increasing total air flux (TAF), and that nitrate formation could be inhibited by controlling the ratio of TAF to ILR below 240 (m(3) air m(-3)/kg COD). It was also determined that the effluent pH was an indicator of the partial nitritation performance. This study provides important insights into the process control on partial nitritation of landfill leachate with fluctuated influent conditions.