混凝防止膜污染的研究

Study of coagulation on preventing membrane fouling

试验主要研究混凝改善膜通量和防止膜污染的效果。试验的每个工况均为0.1MPa过滤压力,连续膜过滤8h,观察膜通量的变化情况。结果表明:在直接过滤原水的情况下,反冲洗后的膜通量恢复率仅为初始通量的40%;而投加了混凝剂4mg/L和10mg/L(以Al计)后,反冲洗后的膜通量得到了完全的恢复。混凝防止膜污染取决于过滤过程在膜表面形成的滤饼层的性能。在过滤混凝液的情况下,膜表面会形成滤饼层,从而有效地防止膜污染,而在过滤上清液的情况下,无法被混凝去除的中性亲水性的有机物沉积在膜表面,造成膜污染。

In this experiment, the effects on improvement of membrane flux and prevention of membrane fouling by coagulation were studied. The results demonstrated： after backwashing, the membrane flux was completely recovered with the addition of coagulant 4 mg/L and 10 mg/L（as AI）, while the membrane flux was only 40% of initial flux without coagulation pretreatment. And it was also found that whether or not the membrane fouling would be prevented by coagulation depended on the possibility of cake layer formation on the membrane surface. If the coagulation fluid was filtered, the coagulation would form a cake layer on the membrane surface and effectively prevent membrane fouling, while if only the clear supernatant fluid was filtered the membrane fouling would appear due to the sedimentation of small, neutral, hydrophilic compounds on the membrane surface.