Experimental Research On Critical Flux Of PES Flat MBR

At present, membrane bioreactor technology has been widely used in water treatment processes. Compared with the conventional activated sludge, MBR technology has the small footprint, high sludge concentration, good effect, less sludge, etc., but also has its drawbacks, the biggest drawback is the membrane fouling problems. In view of membrane fouling, many researchers made an important concept-critical flux.Sulfur atom of PES formula is in the highest oxidation state,so PES has strong antioxidant properties and good chemical resistance. Therefore, PES is recognized as one of the best membrane materials. Based on the laboratory-made PES flat membrane, relevant factors affecting the determination of critical flux were studied. Besides, membrane fouling behavior in the long-running process and running characteristics of MBR under different operation flux were also studied in this paper.Factors affecting the critical flux are intervals, aeration intensity, flow step, the sludge concentration and so on. Results show that:the time interval of 10-15min, aeration intensity 50 ml/min, flow step 3-5L·m-2h-1, the temperature 25℃is most appropriate for deciding the critical flux.Membrane fouling is inevitable for MBR operation during the run. Factors that affected the membrane fouling included liquid character, nature of the membrane itself, operating conditions, sludge properties and so on. The test proved that membrane fouling developed through three stages:the rapid development stage, the slow development stage and the steady stage. Speed of membrane fouling is different under different operating flux. To select the appropriate operating flux is of great significance for MBR operation. Tests showed that the maintenance of run in the sub-critical flux was an effective way to prevent membrane fouling for MBR operation.