Start-up of the Anammox process from the conventional activated sludge in a membrane bioreactor

A lab-scale membrane bioreactor (MBR) was used to start-up the anaerobic ammonium oxidation (Anammox) process from the conventional activated sludge for 2 months. Results indicated the MBR could be a novel and suitable system for start-up of the Anammox process. The Anammox activity appeared after 16 days operation, and the average removal efficiencies of ammonia and nitrite were both over 90% in the end. A final specific Anammox activity of 0.35 g NH4+–N+NO2-–N (gVSS ∗ d)−1 was obtained. Fluorescence in situ hybridization (FISH) analysis confirmed the existence of Anammox bacteria and aerobic ammonia oxidizing bacteria. On the basis of results on MBR performance and FISH analysis, it was proposed that the start-up process was essentially a microbial community succession under man-made disturbance, and a climax community with Anammox bacteria as the dominant population was finally established.