浓缩液浓度对浸没式超滤系统运行特性影响研究

Influence of bulk solution concentration on the operation of submerged ultrafiltration system

为研究浓缩液浓度对浸没式超滤系统运行特性的影响,并优化超滤工艺的回收率,利用3 m3/h的浸没式中空纤维膜中试装置,考察浓缩液浓度不断增加时超滤系统的净水效能和膜污染情况。试验结果表明,随着过滤的进行,浓缩液的浑浊度随着时间近似线性增加,但溶解性有机物的浓度并未显著变化。浓缩液浓度对超滤出水的浑浊度和CODMn无显著影响。当浓缩液浓度较低时(回收率<92%),膜污染较轻;当浓缩液浓度较高时(92%<回收率<97%),由于污染物浓度增加,膜污染显著增加;当浓缩液进一步增加的时候(回收率>97%),由于过滤初期快速形成滤饼层,可以起到二次过滤的作用,且浓缩液中存在的絮体也可以吸附污染物,在二者的共同作用下,尽管可逆污染较大,但是不可逆污染较轻。长期运行中,超滤系统在97.5%回收率下的膜污染甚至比95.0%回收率下更低。因此,控制超滤工艺在高回收率下运行可以控制膜污染。

To study the effect of solution concentration on the operating characteristics of immersion ultrafiltration systems and optimize the recovery rate,this study utilized a 3 m~3/h pilot-scale submerged hollow fiber membrane system to investigate the decontaminate efficiency and membrane fouling during the continuous increase in bulk solution concentration.The experimental results showed that as filtration progressed,the turbidity of the bulk solution increased approximately linearly over time,but the concentration of soluble organic matter did not change significantly.The bulk solution concentration had no significant impact on the turbidity and COD_(Mn)of the ultrafiltrate permeate.When the bulk solution concentration was low(recovery<92%),membrane fouling was relatively low.When the bulk solution concentration was high(92%<recovery rate<97%),membrane fouling increased significantly due to the increase in foulants concentration.When the bulk solution concentration was further increased(recovery>97%),a cake layer rapidly formed at the beginning of filtration,which acted as a secondary membrane.Moreover,the flocs present can also adsorb pollutants.Under the combined action of the two,although reversible pollution is greater,irreversible pollution is lighter.During long-term operation,ultrafiltration exhibited lower membrane fouling at a 97.5%recovery compared to a 95.0%recovery.Therefore,controlling ultrafiltration processes to operate at a high recovery may help control membrane fouling.