Evaluation of parameters influencing oxygen transfer efficiency in a membrane bioreactor

Abstract

Design of fine-bubble aeration systems for membrane bioreactors (MBRs) is challenging due to high mixed liquor suspended solids (MLSS) concentrations that cause changes in alpha value, which is the ratio of mass transfer rate under process conditions to that under clean water conditions. This study describes the results of pilot-scale fine-pore aeration testing to determine a-values and influencing factors for MBRs. Clean water and process water aeration tests were performed at the Honouliuli WWTP during the period of December 2005 and October 2006. Three different 9-inch diameter fine-pore diffusers were tested. Comprehensive analyses of the sludge properties were conducted. Through this study, correlations were found to exist between a-value and oxygen uptake rate (OUR), particle size distribution (PSD), MLSS and viscosity of activated sludge, thereby providing better understanding and design guidance for MBR aeration systems.