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.

Download full-text


Available from: C.P. Chin-pao Huang, Jan 27, 2015
  • Source
    • "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]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of the present study was to identify the influence of process parameters and their interactions on the electro-ultrafiltration performance during the filtration of alumina suspensions at low cross-flow rates. Overall, a weak flux-pressure dependence was observed in the absence of an electric field, indicating mass transfer limitation. A clear enhancement of flux was achieved by superimposing an electric field on the transmembrane pressure. As the feed pH increased from the acidic range to the vicinity of the isoelectric point of the particles, the beneficial effect of the electric field on permeate flux decreased significantly. Statistical analyses showed that in addition to the experimental parameters, some of their interactions were quite influential for determining the performance of the electro-ultrafiltration (EUF) process. Thus, the electric field induced flux enhancement became less pronounced as the initial ionic strength of the feed solution increased. In addition, the three studied response factors were noticed to be interrelated, whereby inevitable pH and conductivity changes associated with the electrode reactions during the electrofiltration process were also important in determining the permeate flux and quality. Overall, the results indicated that a clear understanding of the EUF performance is only possible when considering different effects (such as flux improvement and pH shift) simultaneously.
    Full-text · Article · Mar 2012 · Journal of Membrane Science
    • "The system consists of a medium of suitable mineral constitution, culture containing native microflora, geophagus worm Pheretima elongata and bio-indicator plants [17]. Catalytic processes for oxidation or reduction of both organic and inorganic pollutants are widely adopted1819202122232425. Solar-assisted oxidation, photo-assisted oxidation, heterogeneous catalytic ozonation, electro catalysis, electro-Fenton methods, photo-electro-catalysis process and photo-electro-Fenton process applications are a few areas of catalytic applications to water purifi- cation. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Water is a major source for survival on this planet. Its conservation is therefore a priority. With the increase in demand, the supply needs to meet specific standards. Several purification techniques have been adopted to meet the standards. Magnetic separation is one purification technique that has been adapted from ore mining industries to anti-scale treatment of pipe lines to seeding magnetic flocculent. No reviews have come up in recent years on the water purification technique using magnetic assistance. The present article brings out a series of information on this water purification technique and explains different aspects of magnetism and magnetic materials for water purification.
    No preview · Article · Aug 2010 · Journal of hazardous materials
  • Source
    • "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]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The objective of this study was to examine the removal of arsenic from groundwater by a laboratory scale electro-ultrafiltration (EUF) system. Two groundwater samples taken from I-Ian County located in the northeastern part of Taiwan were studied. These well waters were selected based on their As(III) and As(V) contents; the As(III) to As(V) ratios of the well water were 1.8 and 0.4 for Well-#1 and Well-#2, respectively. In the absence of electrical voltage, the total arsenic removal efficiencies were 1% and 14% for Well-#1 and Well-#2 samples, respectively, using 100-kDa membranes. The higher As removal efficiency of Well-#2 than that of Well-#1 sample might be attributed to different charge characteristics of As(V) and As(III). Upon the application of an electrical voltage of 25 V to the ultrafiltration (UF) system, it was able to reduce the total arsenic concentrations in both groundwater samples by over 79%. The result suggested the possible association between As(III) species and dissolved organic matter which enhanced the As removal.
    Full-text · Article · Dec 2008 · Desalination
Show more