Removal of humic substances (HS) from water by electro-microfiltration (EMF)

Department of Civil and Environmental Engineering, University of Delaware, Ньюарк, Delaware, United States
Water Research (Impact Factor: 5.53). 06/2006; 40(9):1783-94. DOI: 10.1016/j.watres.2006.02.028
Source: PubMed


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.

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Available from: C.P. Chin-pao Huang, Jan 27, 2015
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    • "Due to these reactions, unwanted gas formation may occur at the electrode surfaces which may seriously affect the flux enhancement [15]. However, in wastewater purification, gas formation might be useful, since under suitable circumstances oxygen gas evolved on the anode helps in oxidizing impurities from the wastewater [10] [16]. In addition, the electrochemical reactions might give rise to electrolysis of water and might thus increase or decrease the pH of the concentrate and/or permeate during EUF [17]. "
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    • "This is the electrofiltration process. Much has been reported that electrofiltration can reduce fouling, increase rejection and at the same time purify water [10] [12]. In a previous study, we have shown that the removal of As(V) in the presence of humic substances from synthetic water could be achieved by electro-ultrafiltration (EUF) with a 100-kDa membrane at neural pH [10]. "
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    • "While efficiency of electrofiltration is primarily based on AEM of species in solution, it was expected that fouling could be controlled during electroultrafiltration (EUF). Although much has been reported to eliminate fouling and increase removal of HSs by electrofiltration [12] [13] [14] [15], there are still gaps in the literature about the effect of HSs MW fractions on the performance of EUF. In this study, gel fractionation chromatography (GFC) was used to separate HSs into different MW groups. "
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