Anammox bacteria enrichment in fixed biofilm successfully enhanced nitrogen removal of domestic wastewater in a sequencing biofilm batch reactor (SBBR)

Abstract

The feasibility of enhancing anammox enrichment in sewage treatment through fixed biofilm was investigated in this study. Two reactors were used to treat real domestic sewage and operated in an identical mode: one is a sequencing biofilm batch reactor (SBBR) with blank carriers and the other is a sequencing batch reactor (SBR) without carriers. After anammox sludge inoculation and 160 days' operation, the abundance of the anammox bacteria increased to 2.58 × 109 gene copies/g dry sludge in the biofilm of SBBR, but decreased to 8.18 × 107 gene copies/g dry sludge in the activated sludge of SBR. The nitrogen removal efficiency (NRE) of SBBR and SBR was 79.3% and 57.9%, respectively. Further analysis suggests that the partial nitrification was stabilized in SBBR due to the addition of carriers and the dominating nitrogen removal pathway was the anammox reaction. In general, the fixed biofilm effectively maintained and enriched the anammox bacteria, which benefitted the start-up and steady operation of the sewage partial nitrification anammox (PNA) process.