Effect of Permeate Flux and Water Temperature on Membrane Fouling in Membrane Bioreactor

Both permeate flux and water temperature are critical factors that influence aerobic membrane bioreactors (MBR), affecting treatment rates and microbial composition. This experiment assessed the membrane fouling characteristics of aerobic MBRs with varying water temperatures (10-25℃) and permeate fluxes (10-80 L/m².h). In the membrane filtration process, a dead-end stirred cell with a working volume of 400 mL was used as MBR. The mixed liquid used in this experiment was obtained from an anoxic-selector-aerobic MBR system with a hydraulic retention time of 6 h. As a result, the organic removal efficiency exceeded 80% at permeate fluxes of < 10 L/m2h and exceeded 85% at water temperatures of >15℃. The efficiencies of NH₄-N and NO₃-N removal exceeded 65% and 45%, respectively, at permeate fluxes of < 10 L/m2h and water temperatures of >15℃. Regardless of the water temperature, organic and nitrogen reductions at 10 L/m2h were 30% higher than those at 50 L/m².h. For membrane fouling, the transmembrane pressure (TMP) at permeate fluxes of <10 L/m².h and water temperatures of < 10℃ was approximately 30% lower than that at permeate fluxes of >20 L/m².h and water temperatures of >15℃. Specifically, TMP at a permeate flux of 10 L/m².h was two times lower than that at a permeate flux of 30 L/m².h, indicating that TMP development was affected by permeate flux compared to water temperature.