The NH3-N concentration in the final effluent decreased to
below 5 mg/l when HRT was 12 h, with a mean removal rate of 94%.In the UASB process, the NH3-N concentration was found to trend to increase. This may be because nitrate and nitrite in the wastewater were reduced to ammonia by fermentative bacteria under anaerobic conditions [9]. In agreement to our previous study [20],it was found that the I-BAF is a very effective process for NH3-N removal in wastewater. This is mainly because the carriers in the I-BAF reactor can effectively protect microorganisms like ammonia and nitrite oxidizing bacteria.