Rapid and Stable Accumulation of Nitrite Under High Ph During Partial Denitrification Process: Characterization and Mechanism

Abstract

Abstracts pH plays a decisive role in selection of microbial communities. In this study, the effect of influent pH on nitrite accumulation and its mechanism were discussed during partial denitrification (PD) process. The results indicated that the maximum nitrite transformation ratio (NTR) and accumulation velocity at pH of 11.0 reached 82.53% and 15.26 mg/L·h in 21 cycles (1 hour per cycle), which were 1.6 times and double higher than pH 7.0. Moreover, NTR quickly achieved 68% in 10 cycles and was not affected even pH changed from 11.0 to 7.0. In addition, the relative abundance of Thauera could increase from 0.32% to 30% and the electron chain transfer rate was accelerated in high pH condition. Furthermore, the relative abundance of narH and the activity of enzymes involved in the TCA cycle increased too. It provides an effective regulatory method for rapid and stable accumulation of nitrite in the PD process.

Keywords: Partial denitrification, high influent pH, NO2--N accumulation, Thauera, Metagenomic sequencing