LAUSR

Abstract An anaerobic/oxic/anoxic sequencing batch biofilm reactor (A/O/A SBBR) was tested to treat carbon-limited wastewater without external carbon addition. Simultaneous nitritation–denitritation in the oxic period and poly-hydroxybutyrate (PHB)-driven denitritation in the anoxic period were implemented in the A/O/A SBBR. A high total nitrogen (TN) removal efficiency of 95.97 ± 2.85% was achieved, in which 57.62 ± 4.43% was removed during the aerobic period and 39.00 ± 4.07% was removed during the anoxic period. Simultaneously, 15.47 ± 2.65% of the removed TN was emitted as nitrous oxide (N2O), and 72.25 ± 4.86% of total N2O was produced during the anoxic period. As a result, PHB-driven denitritation improved TN removal efficiency while stimulating high amounts of N2O emission. High-throughput pyrosequencing analysis revealed an abundance of the genera Thauera and Denitratisoma as potential denitrifiers that improved TN removal efficiency. N2O was primarily produced by betaproteobacterial microorganism...