幂函数式进料对PVC超滤膜污染控制研究

Study on the control of PVC ultrafiltration membrane fouling by power function feeding

为了研究函数式间歇流体对外压式超滤膜处理模拟污水过程中膜污染的影响。采用PVC中空纤维超滤膜实验处理腐殖酸模拟污水,在膜组件料液进口处放置幂函数式流体控制器,通过改变料液在膜组件中的流动状态,考察幂函数式进料对PVC超滤膜污染的控制情况;采用计算流体力学(CFD)模拟膜表面剪切力的变化,探究影响膜污染的内在原因。结果表明,当间歇周期内运行和停止时间为10 s时,膜比通量最大可达0.8。扫描电镜结果显示,与新膜相比,经幂函数式进料处理后的膜表面沾有少量颗粒,而经过稳定流处理后的膜表面则形成了致密滤饼层。利用流体力学计算(CFD)模拟结果表明采用间歇流进料时的剪切力为37×10^(5)N,约为稳定流进料的5倍且沿着流体流动方向剪切力的降低率为45.7%及40.5%。

To study the effect of intermittent fluid frequency on membrane fouling in external pressure ultrafiltration process,the PVC hollow fiber ultrafiltration membrane was selected to treat humic acid solution.A power functional control unit was placed before membrane module to produce intermitted fluid.Results showed that when opening and closing time were both 10 s in single-factor experiment,the membrane specific flux was highest and it can reach up to 0.8.The membrane fouling was analyzed by SEM.The fibrous structure with abundant pores can be observed clearly on the surface of pristine membrane.The membrane surface was covered with some small praticles with power functional flow treatment,while the cake layer was formed on the membrane surface and the fouling was more serious with steady flow feeding.The results of fluid dynamics calculation(CFD)show that the shear force of power functional is 37×10^(5) N which was nearly 5 times that of steady flow feeding.The reduction rate of the shear force was 45.7%and 40.5%when adopted the power functional feeding.