Start-up and long-term performance of anammox moving bed biofilm reactor seeded with granular biomass

Abstract

Availability of granular anammox sludge is much higher than biofilm seed carriers and the sludge is easier to transport. This paper describes and investigates a formation of mature anammox biofilm originated from granular sludge and proves that an anammox moving bed biofilm reactors (MBBR) can be easily and quickly started-up by seeding with granular sludge. The reactor was fed with synthetic wastewater containing ammonium and nitrite. Successful start-up was completed in as little as 50 days when TN removal increased to more than 80%. Surface nitrogen loading rate during start-up was equal to 0.75 g m^-2 d and was stepwise increased up to 5.3 g m^-2 d. Biofilm thickness reached 1269 ± 444 μm at the end of the study with specific anammox activity of 22.0 ± 2.1 mg N g^-1 VSS h. This study shows that granular biomass can be transitioned to a biofilm relatively easily which opens a new window of opportunity for starting-up anammox MBBRs.

Keywords: Anammox; Biofilm; Granules; MBBR; Start-up.