Effect of MLSS on sludge characteristics and membrane flux in A/O-MBR
A/O-MBR中MLSS浓度对污泥性能及膜通量的影响

An experimental study on A/O-MBR for the treatment of domestic sewage was carried out by using homemade membrane modules of curtain polypropylene hollow fiber.The relationship between the concentration of mixed liquer suspended solid(MLSS) and change of the membrane flux in the membrane bioreactor was investigated.The results showed that extracellular polymeric substance(EPS) increased from 43 mg/g VSS to 81 mg/g VSS and the ratio of polysaccharide to protein improved from 0.87 to 1.08 with the increase of MLSS from 3 805 mg/L to 6 912 mg/L.Meanwhile,the reduction of relative hydrophobicity(RH) and the increase of Zeta potential also promoted the increase of membrane fouling rate.Under the experimental conditions,the cleaning cycle of membrane modules shortened from 22 days to 11 days when MLSS in reactor reached to 6 200 mg/L after 60 days.Change of the characteristics of mixing liquor as a result of the change of MLSS concentration in reactor is one of the most important factors for membrane flux in A/O-MBR process.