Carrier effects on oxygen mass transfer behavior in a moving-bed biofilm reactor

This study investigates the carrier effects on the oxygen mass transfer behavior of a gas–liquid biofilm surface, and aims to provide evidence for parameter optimization in the practical operation of a moving-bed biofilm reactor (MBBR) during the coking-plant wastewater process. By using the dynamic oxygen dissolution method, the volumetric oxygen mass transfer coefficient KLa was measured by varying the suspended carrier stuffing rate and the intensity of aeration. Within the range of fluidizable flow rate, the efficiency of oxygen mass transfer increased with suspended carrier stuffing rate, and KLa reached its peak value when the stuffing rate was 40%. KLa has an increasing trend with an increase of the aeration intensity, but high aeration intensity was not favorable for reactor operation. Better oxygen mass transfer effect and higher oxygen transfer efficiency could be achieved when the aeration intensity was 0.3 m3 h−1 and the suspended carrier stuffing rate was 30–50%. The possible mechanisms that can account for carrier effects on oxygen mass transfer are the changes in the gas–liquid interfacial area. The ammonia nitrogen removal performance of the coking-plant wastewater in MBBR was satisfied by using the above-suggested conditions. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.