High NH₄⁺-N concentration wastewater treatment by shortcut nitrification–denitrification using a system of A/O inner loop fluidized bed biofilm reactors

In this experiment, a rapid mass-transfer inner loop fluidized bed biofilm reactor (ILFBBR) was employed to treat synthetic high ammonia nitrogen-containing (NH₄⁺-N) wastewater by shortcut nitrification–denitrification. The reactor operation was stable after a short start-up period. Ammonia oxidizing bacteria (AOB) were predominant and 65% nitrite (NO₂⁻-N/NO_x⁻-N) levels were achieved. During the nitrification–denitrification period, the removal rates of NH₄⁺-N and total nitrogen (TN) reached 94 and 82%, respectively. From the material balance, it was indicated that 87% of NH₄⁺-N was removed by shortcut nitrification. The features of ILFBBR and the benefits of shortcut nitrification were combined in this experiment, and showed an excellent removal of NH₄⁺-N from high-concentration NH₄⁺-N wastewater.