Simultaneous endogenous partial denitrification/anammox process for low-strength wastewater treatment: Process optimization, nitrogen removal and microbial dynamics

The endogenous partial denitrification process (EPD) led by glycogen-accumulating organisms (GAOs) has become an alternative to NO2− supply in mainstream anaerobic-ammonia oxidation (anammox). However, low autotrophic nitrogen removal contribution is an urgent problem that needs to be solved in simultaneous endogenous partial denitrification/anammox (EPDA) system. This study used anaerobic duration optimization to enhance the autotrophic nitrogen removal capacity of EPDA system. The results showed that the EPDA activity increased from 0.67 to 1.09 mg N/g VSS·h after anaerobic time was extended to 120 min. This significantly improved the contribution of anammox to TIN removal, increasing from 23.5 % to 61.6 %. During the phase Ⅲ, Eff.TIN of 4.5±1.8 mg/L and NRE of 92.2 %±3.0 %. The enrichment of AnAOB (Candidatus Brocadia) and GAOs (Defluviicoccus) was responsible for maintaining the stability of the EPDA process. This study provides a feasible optimization strategy for improving the contribution of autotrophic nitrogen removal in the EPDA system. © 2024 Elsevier B.V.