Effects of hydrodynamic conditions on the start-up of anaerobic ammonium oxidation (ANAMMOX) process in EGSB reactors

2 liters anaerobic granular sludge and 1.5 liters aerobic sludge were seeded to four similar plexiglass EGSB reactors, which used to start-up anaerobic ammonium oxidation process . The EGSB reactors were operated on peristaltic pumps with different recycled-water upflow velocities (1.5m·h-1(1#), 2.0m·h-1(2#), 2.5m·h-1(3#), 3.0m·h-1(4#)) in order to expose the biomass to different shear conditions and to study their effects on both efficiency and biophysical properties of the Anammox granular biomass. The results showed that: Greater hydraulic loading, the higher the efficiency of the reactor started When the increased flow velocity is 2.5m / h, the reactor has the most significant anaerobic ammonium oxidation effect and the best impact resistance. During the four reactors startup, NH₄⁺-N and NO₂^--N removal ratio was lower than the theoretical value (1:1.32) in most of the time , and NO₃^--N did not accumulate. The reasons may be NO₃^--N what the anaerobic ammonium oxidation process generated reduce to NH₄⁺-N because of the presence of nitrate-reducing bacteria.