在线反冲下电絮凝对可逆及不可逆膜污染的影响

为研究在线反冲膜分离工艺中电絮凝对膜污染控制的影响,采用电絮凝(EC)技术和平板微滤(MF)膜组合,形成EC-MF集成工艺去除水中腐殖酸,并和单独MF膜分离对比结果表明,间歇操作工艺中,电流密度越高,减缓膜污染作用越明显,电流密度分别为30、40 m A/cm^2时,UV₂₅₄及DOC的去除率分别可达95%及80%以上。连续操作工艺中,电絮凝可明显降低可逆及不可逆膜污染,并有效延长反冲运行周期,当两工艺最终膜污染程度基本相当时,EC-MF运行了555 min,而MF只能运行270 min。EC-MF中污染膜表面滤饼疏松,而MF中污染膜表面凝胶态污染物结构致密。采用先纯水冲洗、再NaOH溶液浸泡、最后HCl溶液浸泡工艺时,EC-MF膜通量恢复率可达到95.6%,较单独的MF工艺显著提高。

Effects of Electrocoagulation on Reversible and Irreversible Membrane Fouling Control in Process of Online Back-flushing

In order to investigate the effects of electrocoagulation(EC) on membrane fouling control in process of online back-flushing, the EC and flat sheet microfiltration membrane(MF) were combined to form EC/MF process for removal of humic acid(HA) in water, and compared with those of alone MF membrane separation. The results show that, in batch process, the higher the current density, the better the anti-fouling ability of the membrane, and under the current density of 30 and 40 mA/cm^2, the removal rates of UV254 and DOC could reach 95% and 80%, respectively. In continuous operation process, EC significantly reduced the reversible and irreversible membrane fouling and effectively prolonged the back-washing cycle. As the membrane fouling for EC/MF and MF were basically the same, the EC/MF ran for 555 min, and while MF only ran for 270 min. The EC/MF showed a loose cake on the fouling membrane surface, while MF had obvious colloids on the fouling membrane surface leading to much denser structure. The flux recovery rate of EC/MF membrane reached 95.6% which was significant higher than MF process as the fouling membranes were first rinsed by pure water, then by Na OH solution soaking and last by HCl solution soaking.