[Characteristics of membrane fouling and its control in membrane sequencing batch reactor process].

Characteristics of membrane fouling and its control were investigated using synthetic wastewater as feed in an anaerobic/aerobic membrane sequencing batch reactor (MSBR) for 300 days operational period. The experimental results showed that the sludge was in flocculent form, and the range of SVI was 64.6-110.6 mL x g(-1) during the initial 75 days operation. Membrane fouling occurred in a quick exponential growth, and the average growth rate of TMP was 0.309 kPa x d(-1). Membrane resistance was in the range of 0.393 x 10(11) - 1.298 x 10(11) m(-1) x d(-1) and specific membrane flux decreased from 4.4 L x (m2 x h x kPa) (-1) to 0.52 L x (m2 x h x kPa)(-1). The critical membrane flux was 20 L x (m2 x h)(-1) at 75th day. In 75-120 d operation, MSBR condition was regulated, and aerobic granular sludge in reactor appeared. SVI decreased steadily, and finally maintained approximately 40 mL x g(-1) from 170th day on. The sludge particle grew much gradually, and size distribution was mainly in diameter 500-1000 microm at 220th day. Membrane fouling developed very slowly. The average accumulating rate of TMP was only 0.062 kPa x d(-1) membrane resistance varied from 0.291 x 10(11) m(-1) x d(-1) to 0.404 x 10(11) m(-1) x d(-1), specific membrane flux decreased from 4.4 L x (m2 x h x kPa)(-1) to 1.4 L x (m2 x h x kPa) (-1) and critical membrane flux was 40 L x (m2 x h)(-1) at 220th day. These data clearly demonstrated that the formation of aerobic granular sludge was beneficial to cease the growth rate of membrane fouling. Specific membrane flux was the biggest at aeration strength of 100 m3 x (m2 x h)(-1) while membrane fouling rate was the lowest at aeration strength of 69 m3 x (m2 x h)(-1).