Comparison research on membrane fouling of two-stage sequencing batch MBR and one-stage aerobic MBR

Aiming at resolving membrane fouling problem of MBR technology applying in water recycle, two-stage sequencing batch membrane bioreactor (TSBMBR) was presented. Comparing with the one-stage aerobic membrane bioreactor, the mechanism of how sequencing batch operating mode reducing membrane fouling was shown. The results showed that external pollution resistance (R_ef+R_p) of one-stage aerobic membrane bioreactor, taking up 75.39% of total resistance, was much higher than that of TSBMBR. The most obvious factor was external deposition resistance R_ef, which of TSBMBR was just 6.5% of that of one-stage aerobic membrane bioreactor. And then was the gel polarization resistance R_p, which of TSBMBR was about 33.12% of that of one-stage aerobic membrane bioreactor. Gel polarization resistance R_p of the two systems occupied the major proportion, values of SMP of the two system accumulated with time, and SMP value of TSBMBR is lower than that of one-stage aerobic membrane bioreactor. SMP value of the former was more stable and increased slowly, while that of the latter increased rapidly in late experiment period. Reduction rate of SBMBR2 specific membrane flux was much lower than that of one-stage aerobic membrane bioreactor. Comparing with initial operation, specific membrane flux fell by 42% and 75% respectively. This showed that sequencing batch mode membrane suction and idle aeration operation mode could help improving degradability of hard-biodegradable organics, mitigating polarization, and effectively reducing sediment and gel layer pollution on membrane surface. Comparing with one-stage membrane bioreactor, TSBMBR could enable the system to keep high trans-membrane flux, low membrane fouling rate and high system stability.