Removal of humic substances (HS) from water by electro-microfiltration (EMF).
ABSTRACT 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.
- European Journal of Pain Supplements 01/2011; 5(1):35-35.
- [Show abstract] [Hide abstract]
ABSTRACT: Modifications of bacterial activities are observed when continuous electric current is applied in soil for soil remediation purposes (electrokinetic). In this study we found a significant increase of 330% of the total heterotrophic culturable bacteria 2d after soil samples had been submitted to pulsed electric field (PEF) treatment (E∼4KV/cm, τ∼5ms, 3 pulses) resulting from pulsed electric current injections. We hypothesized that this result was caused by qualitative and/or quantitative modifications of the dissolved organic matter and tested this using a γ-sterilized model soil. The incidence of electrical parameters (electric field intensity and pulse duration) on the water-extractable organic matter was analysed using two types of experimental set-ups for current injection. These experimental set-ups exhibited different volume, physical state (liquid, solid) of the soil samples and different electrical conditions. Total organic carbon content and fluorescence signature (excitation-emission matrix, EEM) were monitored for all samples. A 67% decrease in the ratio between higher and lower molecular weight fluorescent compounds was observed, indicating a new distribution of the fluorescent compounds into the dissolved organic matter following PEF treatment.European Journal of Soil Biology - EUR J SOIL BIOL. 01/2008; 44(1):10-17.
- [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.Journal of Membrane Science 03/2012; 403– 404 (2012):227– 235. · 4.09 Impact Factor