Anaerobic Ammonia Oxidation in Start-Up of Bench Scale ASBR

A set of bench scale ASBR reactors with 0.5 L effective volume were carried out to culture anaerobic ammonia oxidizing bacteria, while the anaerobic granular sludge was inoculated into these reactors as well as the operating temperature is 30±1°C, HRT is 72h and pH is approximate 7.8 in this experiment. After 60 days running, these reactors appeared anaerobic ammonia oxidation phenomenon. When the influent NH4+-N and NO2--N concentrations were approximately 50 mg/L and 70 mg/L, the NH4+-N, NO2--N and TN removal were 80%, 90% and 70%, respectively, the ratio of the NH4+-N and NO2--N removal and NO3--N production is approximately 1:1.5:0.25, close to the theoretical valve of 1:1.32:0.26 and that mainly accord with the chemical equilibrium of anaerobic ammonia oxidation mode. Furthermore, when the phenomenon of anaerobic ammonia oxidation appeared, effluent pH value was slightly higher than influent and the sludge become red.