Fouling characteristics of a novel rotating tubular membrane bioreactor

Abstract

Shear-enhanced membrane filtration is an effective way to mitigate membrane fouling in membrane bioreactor (MBR) technology. In this study, a novel rotating tubular membrane bioreactor (RTMBR) was employed to achieve shear-enhanced membrane filtration and fouling characteristics of the bioreactor were investigated. Through particle image velocimetry (PIV) analysis, it was found that the turbulence in the reactor intensified as the rotary speed increased. Two partial least squares (PLS) models predicting membrane fouling rate in the bioreactor were established employing rotary speed (RS), aeration rate (AR), mixed liquor suspended solids (MLSS), bound extracellular polymeric substances (bEPS) and mean particle size (MPS) as predictor variables. The models owned good robustness and predictive power. The results indicated that membrane fouling rate decreased as RS increased. The factors in order of decreasing influences on membrane fouling rate were MLSS, bEPS, RS, MPS and AR according to the model results, indicating a more significant impact of RS on membrane fouling rate than that of MPS and AR. Furthermore, 5 additional tests clearly verified the relationship between rotary speed and membrane fouling. Lastly, analysis of energy consumption suggested that increasing rotary speed to mitigate membrane fouling was much more energy saving and efficient than increasing aeration rate.