A/O-MBR中MLSS浓度对污泥性能及膜通量的影响

Effect of MLSS on sludge characteristics and membrane flux in A/O-MBR

采用国产聚丙烯中空纤维帘式膜组件,进行了A/O-MBR系统处理生活污水的实验研究,主要探讨了系统中污泥浓度(MLSS)与膜通量变化过程的关系。实验结果表明,MLSS由3 805 mg/L升高到6 912 mg/L时,污泥混合液胞外聚合物(EPS)由43 mg/g VSS增加到81 mg/g VSS,EPS中多糖与蛋白质的比例从0.87增加到1.08。同时,污泥相对疏水性(RH)的降低与Zeta电位的升高也在一定程度上共同促进了膜污染速率的上升。实验条件下,当运行时间为60 d左右,MLSS升高至6 200 mg/L时,跨膜压差上升迅速,膜组件清洗周期由初始的22 d缩短为11 d。A/O-MBR中由于MLSS浓度变化而导致的活性污泥混合液特性的变化,是影响膜通量变化的重要原因。

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.