Weng Yu-Hsiang, Li Kung-Cheh, Chaung-Hsieh Lin Han, Huang C P
Graduate Institute of Environmental Engineering, National Taiwan University, Taipei 106, Taiwan, ROC.
Water Res. 2006 May;40(9):1783-94. doi: 10.1016/j.watres.2006.02.028. Epub 2006 Apr 17.
Humic substances (HS) represent the common agents contributing to flux decline during membrane filtration of natural water. In order to minimize the fouling during microfiltration (MF) of HS, modifying the operation of MF presents a promising alternative. A laboratory-scale electro-microfiltration (EMF) module was used to separate Aldrich HS from water by applying a voltage across the membrane. The presence of an electric field significantly reduced the flux decline. A flux comparable to that of ion-free water was attained when the voltage was near the critical electric field strength (Ecritical), i.e., the electrical field gradient that balances the advective and electrophoretic velocities of solute. At an applied voltage of 100 V (approximately 110 V/cm), it was able to reduce UV absorbance at 254 nm (UV254), total organic carbon (TOC) and trihalomethane formation potential (THMFP) by over 50% in the permeate. Results from 1H nuclear magnetic resonance (1H NMR) analysis suggest that the aromatic and functionalized aliphatic fractions decreased significantly in the permeate. The charged HS have large molecule weight compared with those passing through membrane. Results clearly indicate that a combination of electric force with MF can increase HS rejection and decrease flux decline. Electrophoretic attraction was the major mechanism for the improvement of flux and rejection over time.
腐殖质（HS）是导致天然水膜过滤过程中通量下降的常见因素。为了尽量减少HS微滤（MF）过程中的污染，改进MF操作是一种很有前景的选择。使用实验室规模的电微滤（EMF）模块，通过在膜上施加电压来从水中分离Aldrich腐殖质。电场的存在显著降低了通量下降。当电压接近临界电场强度（E临界）时，即平衡溶质平流速度和电泳速度的电场梯度时，可获得与无离子水相当的通量。在施加100 V（约110 V/cm）的电压时，它能够使透过液中254 nm处的紫外线吸光度（UV254）、总有机碳（TOC）和三卤甲烷生成潜力（THMFP）降低超过50%。1H核磁共振（1H NMR）分析结果表明，透过液中芳香族和官能化脂肪族部分显著减少。与透过膜的腐殖质相比，带电的腐殖质分子量较大。结果清楚地表明，电力与微滤相结合可以提高腐殖质截留率并减少通量下降。随着时间的推移，电泳吸引是通量和截留率提高的主要机制。
