Ammonium Nitrogen Wastewater Treatment by Aerobic Granular Sludge Membrane Bioreactor

Aerobic granular sludge was cultured successively and stably existed in the membrane bioreactors, inoculated by floccular activated sludge and fed with glucose as organic substrate by means of special alternating anaerobic-aerobic operation mode. Microscopic observation of the granular showed that the morphology of granules was nearly spherical or elliptical with dense structure and its mean diameter was 1000 mum. Nitrogen and carbon components in ammonium nitrogen wastewater were efficiently removed by using an aerobic granular sludge membrane bioreactor where biofilm was fixed on a hollow-fiber membrane. The experimental results showed that the effluent ammonia nitrogen could be constant at less than 10 mg/L and COD was averaged at 46.2 mg/L under the conditions of HRT 8 h, the volume load of COD 600 mg/L, and the concentration of ammonia nitrogen 40 mg/L. The removal rates of nitrate nitrogen and nitrite nitrogen were approximately 90%. In addition, the introduction of aerobic granules into the MBR system was beneficial to controlling membrane fouling.