超声联合反冲在线控制PVDF中空纤维超滤膜的污染

Control of PVDF hollow fiber ultrafiltration membrane by ultrasound with backwashing

采用聚偏氟乙烯(PVDF)中空纤维超滤膜处理饱和氯化钙溶液,研究超声处理和在线反冲洗对膜通量的影响.无反冲时,低频率和较高声强抑垢效果好,在超声频率为40 kHz、声强为2 700 W/m2,曝气量为45 L/h时,超滤90 min,抑垢率为81.3%.进行了不同反冲周期的过滤实验,反冲周期小于20 min,延缓污染效果好.反冲周期为15 min,无曝气条件下,有无超声时各超滤90 min,抑垢率分别为92.4%和83.3%.开启超声,同时曝气,在相同反冲周期下超滤相同时间,抑垢率达94.2%.明显好于单独反冲时的效果.超声抑垢联合反冲洗是一种有效控制膜污染的方法.

Polyvinylidene-fluoride （PVDF） hollow fiber ultrafiltration membrane was applied to treat saturated calcium chloride solution, and ultrasound and online backwashing were employed to study PVDF hollow fiber membrane flux. Under the conditions of no backwashing, the lower the ultrasonic frequency and the higher the intensity of ultrasound, the better rate was 45 L/h and the ultrasonic frequency and the restraint of scale formation was. When the aeration intensity were 40 kHz and 2 700 W/m^2 respectively, the rate of restraining scale formation reached 81.3% after utrafiltration 90 min. Membrane fouling during periodic ultrafiltration and backwashing were investigated experimentally. The results show that the backwashing cycle less than 20 min is superior to that of the longer. Without aeration, the rate of restraining scale formation is 92.4% or 83.3% with or without 90 min ultrasound treatment respectively. However, the rate is 94. 2% at the same cycle and ultrafiltration time with 45 L/h aeration. So ultrasound irradiation with backwashing is an effective method to control membrane fouling.