Insights Into A Shift Of Microbial Communities During The Start-Up Of Anammox Reactor Under Mainstream And Sidestream Conditions

Although anaerobic ammonium oxidation (anammox) owns energy-neutral advantages, the start-up of anammox faced the challenges of a long time and complex environmental factors. This study investigates the shift of microbial communities during the start-up of the anammox reactor under mainstream and sidestream conditions. Two microbial morphologies (biofilm and gel bead) were compared. Different from Candidatus Brocadia, only Candidatus Kuenenia was retained under sidestream conditions, whose relative abundance arrived at 15.40% and 2.17% in biofilm and gel bead, respectively. However, anammox bacteria were strongly against temperature (20 degrees C +/- 0.5 degrees C) and pH (6.7-7.3) under mainstream conditions, instead of competition with other nitrogen removal microorganisms. Although gel beads could start up the bioreactor in a short time of 14 d, the abundance of anammox bacteria, Nitrosomonas and denitrifiers in gel beads was lower than those in the biofilm. Finally, the anammox bacteria were proved to own significant positive relations with temperature and pH. Overall, our findings give information to facilitate the start-up of an anammox-based bioreactor.