Effect of Alcaligenes faecalis on Nitrous Oxide Emission and Nitrogen Removal in Three Phase Fluidized Bed Process

Abstract

Nitrous oxide (N₂O), one of the greenhouse effect gases, has not been known that how much N₂O is produced from municipal wastewater treatment and what its management should be. In this study, for controlling nitrous oxide emission and removing nitrogen from municipal wastewater, we experimented the three phase fluidized bed process equipped with draft tube along with immobilized Alcaligenes faecalis, a typical heterotrophic nitrifer and a predominant genus. Also we evaluated the optimum treatment condition of the three phase fluidized bed process for emitting nitrous oxide. The results of this study showed that the three phase fluidized bed process was more effective than the activated sludge process for controlling nitrous oxide emission and removing nitrogen. Increasing amount of A. faecalis in reactor should be encouraged for controlling nitrous oxide emission and removing nitrogen. In addition, the activated sludge process using immobilized A. faecalis as a carrier had more nitrogen removal efficiency than conventional activated sludge process. The accumulation of NO₂-N, NO₃-N resulted in high N₂O emission. Therefore, we suggested that it is necessary to reduce NO₂-N and NO₃-N for both reducing N₂O emission and improving nitrogen removal.

Keywords:

• Alcaligenes faecalis
• Activated carbon
• Three phase fluidized bed process
• Nitrous oxide