膜生物反应器中PVDF中空纤维膜亲水性变化特征

为研究膜生物反应器(MBR)中PVDF中空纤维膜的亲水性变化特征,提出以接触角变化速率的绝对值(λ)表征亲水性的方法 ,按轴向长度将膜纤维划分为4个位置,考察过滤和清洗对膜亲水性的影响。结果表明:在MBR运行过程中,膜污染的加剧与膜的亲水性变化有关,膜纤维通量越高的位置,膜的亲水性越差。采用物理反洗和短时间的化学浸泡清洗,膜的亲水性能得到一定恢复,但效果有限。延长化学浸泡清洗时间发现,浸泡3 h膜纤维的亲水性最好。

Characteristics of PVDF hollow fiber membrane hydrophilicity variation in the membrane bioreactor

In order t o investigate the variation characteristics of hydrophilicity of PVDF hollow fiber membranes in the membrane bioreactor(MBR),it is proposed that using the absolute value(λ) of variation rate of contact angle by time for characterizing the membrane hydrophilicity ,the membrane fiber can be divided into four positions according to the length of axial direction. The influences of filtration and cleaning on membrane hydrophilicity are investigated. The results show that in the process of MBR operation,the aggravation of membrane pollution is related to membrane hydrophilicity variation. The higher the fiber membrane flux ,the worse the membrane hydrophilicity. The membrane hydrophilicity can be recovered to a certain degree ,by physical back flushing and short-time chemical immersion and cleaning,but the effect is limited. It is found that the best hydrophilicity of membrane fiber can be obtained by extending the time for three hours.