Research on Influence Factors of Membrane Fouling in A/O-MBR System

[Objective] The aim was to study the influence factors of membrane fouling in A/O-MBR system,so as to control membrane fouling better,prolong the service life of membrane,further reduce the cost of water treatment and promote the popularization of membrane bioreactor(MBR) effectively.[Method] Based on small A/O-MBR device,an orthogonal test with three factors(including aeration intensity,pump-stop ratio and mixed liquor suspended solid) and three levels was designed to optimize three parameters,and the effects of factors on membrane fouling and their mechanisms were studied through single-factor analysis.[Result] The order of operation parameters affecting membrane fouling in A/O-MBR was aeration intensity>pump-stop ratio>mixed liquor suspended solid(MLSS),and the optimum operating parameters were composed of 1.6 m3/h of aeration intensity,4 500 mg/L of MLSS and 9:2 of pump-stop ratio.With the increase of running time,soluble microbial product(SMP) and extracellular polymeric substance(EPS) accumulated gradually in the reactor,and EPS accumulated more rapidly than SMP;meanwhile,membrane fouling was accelerated.Therefore,EPS was the priority factor for membrane fouling compared with SMP.In addition,membrane fouling was accelerated gradually with the increase of protein content in EPS,while the variation of polysaccharides content in EPS had no obvious effect on membrane fouling,so protein content in EPS was the main factor for membrane fouling.[Conclusion] The study could provide theoretical references for the choice of parameters,operation and running in practical engineering.