气液两相流对中空纤维膜错流过滤过程的影响

Influence of Gas-Liquid Two-Phase Flow on Cross-Flow Filtration Process of Hollow Fiber Membrane

采用聚偏氟乙烯(PVDF)中空纤维膜进行错流过滤试验,以中空纤维膜组件的膜通量、浑浊度以及高锰酸盐指数(COD_(Mn))的截留率为考察指标,通过在过滤时添加曝气形成气液两相流,研究在气液两相流条件下曝气量、进水流量、跨膜压差等参数对中空纤维膜错流过滤过程的影响。试验结果表明:在一定范围内,膜通量随着曝气量增大而增大,曝气量为120 L/h时对浑浊度的去除效果最好,为96.5%,COD_(Mn)的截留率为68.6%,达到动态平衡状态后膜通量最高,继续提升曝气量,膜通量随曝气量增加而减小,出水浑浊度也略有升高;跨膜压差越大,膜通量越高,中空纤维膜组件达到动态平衡状态的时间越早;增大进水流量利于提高膜通量。气液两相流能有效减缓浓差极化和膜污染,提高稳定通量,有利于提高膜过滤效率。

In this paper, PVDF hollow fiber membrane was used for cross-flow filtration experiment. Membrane flux, turbidity and COD_(Mn)retention rate of hollow fiber membrane module were taken as inspection indices, gas-liquid two-phase flow was formed by adding aeration during filtration. The effects of aeration quantity, influent flow rate and transmembrane pressure difference on cross-flow filtration process of hollow fiber membrane were studied. Results showed that within a certain range, membrane flux increased with the increasing of aeration rate, with aeration rate of 120 L/h, best turbidity removal efficiency was 96.5%, and the retention rate of COD_(Mn)was 68.6%. After reaching dynamic equilibrium state, the membrane flux was highest, and the membrane flux decreased with the continious increased of aeration rate, and the effluent turbidity also increased slightly. The larger the transmembrane pressure difference, the higher the membrane flux, and the earlier the hollow fiber membrane module reached the dynamic equilibrium state. Increasing influent flow rate was beneficial to increase membrane flux. Gas-liquid two-phase flow could effectively slow down concentration polarization and membrane fouling, improve stable flux and membrane filtration efficiency.