Impact of COD/N on anammox granular sludge with different biological carriers.

ABSTRACT

The purpose of this study is to investigate the effect of COD/N interference on mature anammox granular sludge formed by different biological carriers. Three anammox granular sludge rectors were established with no biological carriers (R1), GAC (R2) and PVA-gel bead (R3), respectively. As the COD/N ratio increased to 12, the activity of anaerobic ammonia oxidizing bacteria in R1 and R2 was significantly inhibited. However, the nitrogen removal effect of R3 did not decrease dramatically, and the nitrogen removal rate in this phase was 1.54 ± 0.05 kg N/m3·d. As the COD/N ratio increased to 11.5, the removal of NH4+-N in all reactors gradually decreased. The order of COD resistance of the three reactors in this study was R3 > R2 > R1. It was found that Candidatus Brocadia might be sensitive to the presence of organic matter. The abundance of heterotrophic denitrifying bacteria increased gradually in each reactor under increased influent COD/N ratios.