Pilot-Scale Integrated Anaerobic–Aerobic Bioreactor for COD and NH 3 -N Removal: Start-up, Key Processes, and Performance

The start-up of an integrated anaerobic–aerobic bioreactor (IAAB) was conducted by gradually increasing the organic loading rate (OLR) of the artificial wastewater. In this case, glucose was taken as the sole carbon resource. It reached stabilization after it was continuously run for 96 days. Chemical oxygen demand (COD), ammonium nitrogen (NH 3 -N), and volatile fatty acid (VFA) were the running indicators. Biomass concentration, particle size distribution, dehydrogenase activity (DHA), the contents of coenzyme F 420 , extracellular polymeric substances (EPS), the shapes, and micro-compositions of granular sludge were the stable indicators. The results indicated that the system had good COD removal ability and NH 3 -N removal effect. The formation of sludge granules in the anaerobic compartment was the key factor of the start-up and stability of the IAAB. Each section of anaerobic process had an obvious separating function.