Comparison of nitrite accumulation performance and microbial community structure in endogenous partial denitrification process with acetate and glucose served as carbon source

• EPD A possessed higher COD intra efficiency with abundant Candidatus_Competibacter . • Preferred r NO2 and NTR were obtained in EPD A but less stable nitrite accumulation. • A shift from Candidatus_Competibacter to Defluviicoccus appeared in EPD A and EPD G . • The combination of EPD and Anammox might be practicable for wastewater treatment. Although the combination of endogenous partial denitrification (EPD) and Anammox (EPD-AMX) were developed for deep-level nitrogen removal, the effects of different carbon source were not clear. In this study, the EPD performance was investigated comparatively with acetate (EPD A) and glucose (EPD G ). Results revealed that through regulating chemical oxygen demand to phosphate ratio, Candidatus_Competibacter was highly enriched in EPD A (54.2%) and EPD G (51.3%), resulting high intracellular carbon storage efficiencies (90.2% and 85.3%, respectively). More stable nitrite accumulation was observed in EPD G than EPD A . But, higher specific nitrite generated rate ( r NO2, 8.25 > 7.04 mgN·gVSS −1 ·h −1 ) and nitrate-to-nitrite transformation rate (NTR, 87.9% > 85.2%) were achieved in EPD A than those in EPD G . The functional bacterium was also shifted to Defluviicoccus in both EPD A (30.6%) and EPD G (25.8%). Moreover, with whether acetate or glucose, the EPD-AMX processes could achieve the same level of total nitrogen removal efficiencies (88.7% and 91.3%, respectively) via anammox mainly (87.8% and 89.4%, respectively).