气液两相流对气升式管式MBR膜污染的影响

Impact of Gas-liquid Two-phase Flow on Membrane Fouling in Air-lift Tubular MBR

采用计算流体力学(CFD)与实体模型相结合的方法,对气升式管式MBR运行中气液两相流的水力学参数进行计算和验证。CFD模拟结果显示,当单管曝气量>43 L/h时,可得到10.1 Pa以上的膜面剪切力,继续增大曝气量对提高膜面剪切力影响不明显。采用与CFD模型同尺寸的实体模型验证CFD模拟结果,两种方法所得膜面剪切力误差为10%～20%。分析膜面剪切力对气升式管式MBR中膜污染的影响可知,当单膜管曝气量为57 L/h、膜面剪切力为8.7 Pa时,能够得到3.2 kPa/d的膜污染速率,继续增大曝气量反而会加速膜污染速率。

The hydraulics parameters of the gas-liquid two-phase flow in air-lift tubular MBR was simulated and verified using CFD and physical models. The results of CFD simulation showed that when the aeration rate of a single tube was greater than 43 L/h, a shear stress of more than 10.1 Pa could be obtained on the membrane surface. Continuous increase in the aeration rate had no significant effect on improving the shear stress on the membrane surface. The verification resuhs of a physical model with the same size to CFD model indicated that there was a 10% to 20% error in the shear stress. The impact of shear stress on the membrane surface on membrane fouling in air-lift tubular MBR was analyzed. When the aeration rate of a single tube was 57 L/h, and the shear stress on membrane surface was 8.7 Pa, the membrane fouling rate was 3.2 kPa/d. However, when the aeration rate was increased continuously, membrane fouling rate was accelerated.