Existence of Critical Recovery and Impacts of Operational Mode on Potable Water Microfiltration

Results from a potable water microfiltration (MF) pilot study employing untreated surface water are reported. The effects of filtrate flux and recovery on direct flow, outside-inside, hollow fiber MF fouling rates, and backwash effectiveness are presented. Constant flux experiments suggested the existence of a critical recovery below which MF fouling rates were low and effectiveness of backwashes was high and relatively independent of the recovery. However, in the range of experimental conditions investigated, fouling rates increased dramatically and backwash effectiveness decreased steeply when this critical recovery was exceeded regardless of the flux. In general, for a fixed recovery, specific flux profiles analyzed on the basis of volume filtered per unit membrane area were insensitive to filtrate flux. Fouling was accelerated by operating membranes at constant flux rather than at constant pressure, in part, because of membrane compaction and cake compression. Changing the mode of filtration between constant flux and constant pressure is shown to have no effect on MF filtrate water quality. For any given capacity, membrane area requirements are decreased, and power requirements are increased when membranes are operated at constant flux rather than at constant pressure.     

Temperature effects on the morphology of porous thin film composite nanofiltration membranes

Even though polymeric nanofiltration (NF) and reverse osmosis (RO) membranes often operate on surface waters and surficial groundwaters whose temperature varies over time and with season, very little detailed mechanistic information on temperature effects on membrane selectivity is available to date. Hence, a study was undertaken to investigate the effects of operating temperature (5-41 degrees C) on the morphology and structure of two commercially available thin film composite NF membranes. Application of hydrodynamic models to experimental rejection of dilute solutions of hydrophilic neutral alcohols, sugars, and poly(ethylene glycol)s revealed changes in both the sieving coefficient and permeability of solutes below the membrane glass transition temperature. The vast majority of pores were smaller than 2 nm for both membranes (network pores) even though evidence for a small fraction of larger aggregate pores (approximately 30 nm) was also obtained for one membrane. Increasing temperature appears to cause structural changes in network pores by increasing its pore size while simultaneously decreasing pore density. These increases in pore sizes partially explain reported reductions in contaminant (e.g. arsenic, salts, natural organic matter, hardness, etc.) removal by NF and RO membranes with increasing temperature.     

An enterprise integration methodology

As more and more organizations pursue the benefits of e-business, they are looking to a process called enterprise integration, or EI, as a key technical enabler in transforming their business processes. A typical form of EI is Webification; in this scenario, a company wants to offer its existing products and services over the Internet, so it builds Web front-end systems and integrates them to its backend legacy systems. (In this article, we use "legacy system" to mean any IT system already in operation.) A more complex El scenario involves enterprise application integration. By this process, the organization links up previously separate and isolated systems to give them greater leverage. For example, an organization might integrate a customer-relationship-management system, a call center system, and legacy customer account systems to give the organization a consolidated view of its customers. An emerging EI scenario is business-to-business (B2B) integration (also called extended enterprise models), which occurs when an organization integrates its own business processes with those of its business partners to improve efficiency within a collaborative value chain.     

Tracking petroleum refinery emission events using lanthanum and lanthanides as elemental markers for PM2.5

Fine particulate matter levels at four air sampling stations in the Houston, TX area are apportioned to quantify the impact of emissions from a local refinery during a reported emission event. Through quantification of lanthanum and lanthanides using a recently developed analytical technique, the impacts of emissions from fluidized-bed catalytic cracking (FCC) units are quantitatively tracked across the Houston region. The results show a significant (33-106-fold) increase in contributions of FCC emissions to PM2.5 compared with background levels associated with routine operation. This impact from industrial emissions to ambient air quality occurs simultaneously with a larger, regional haze episode that lead to elevated PM2.5 concentrations throughout the entire region. By focusing on detailed chemical analysis of unique maker metals (lanthanum and lanthanides), the impact of emissions from the FCC unit was tracked from the local refinery that reported the emission event to a site approximately 50 km downwind, illustrating the strength of the analytical method to isolate an important source during a regional haze episode not related to the emission event. While this source apportionment technique could separate contributions from FCC emissions, improved time-resolved sampling is proposed to more precisely quantify the impacts of transient emission events on ambient PM2.5.     

Influence of MMT nanoclay on impedance spectroscopy analysis of naturally woven coconut sheath/polyester hybrid composite

In this work, the impedance spectroscopy study has been carried out for the naturally woven coconut sheath fiber reinforced composite with the effect of adding different weight percentages of montmorillonite nanoclay and chemical activation of fiber. The dispersion mechanism of nanoclay with polyester, and the modification of the fiber surface have been studied by using X–ray diffractogram, transmission electron microscope and scanning electron microscope respectively. Infra‐red spectra have also been taken to study the reactive compounds of treated fibers. The impedance spectrum shows significant improvement in A.C. conductivity, dielectric constant and loss tangent values by the fiber modification, using alkali and silane treatments, due to the structural topography changes at the fiber surface. The highest dielectric strength was found in alkali‐treated coconut sheath/polyester composite due to increase in orientation polarization by the absorption of moisture content at fiber surface. The addition of different weight percentages of nanoclay with coconut sheath in all the treated conditions shows significant changes in the dielectric properties. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Disinfection byproduct relationships and speciation in chlorinated nanofiltered waters

The formation and speciation of disinfection byproducts (DBPs) resulting from chlorination of nanofilter permeates obtained from various source water locations and membrane types are examined. Specific ultraviolet absorbance and bromide utilization are shown to decrease following nanofiltration. Both dissolved organic carbon (DOC) concentration and ultraviolet absorbance at 254 nm were found to correlate strongly with trihalomethane (THM), haloacetic acid (HAA), and total organic halide (TOX) concentrations in chlorinated nanofilter permeates, suggesting that they can be employed as surrogates for DBPs in nanofiltered waters. Because smooth curves were obtained for individual THM and HAA species as well as bromine and chlorine incorporation into THMs and HAAs as a function of Br-/DOC molar ratio, it is likely that mole fractions of these DBPs are more strongly influenced by chlorination conditions, Br-, and DOC concentrations than NOM source and membrane type. Mole fractions of mono-, di-, and trihalogenated HAAs were found to be independent of Br-/DOC. Even at a very low Br-/DOC of 2.9microM/mM, the mixed bromochloro- and tribromoacetic acids constituted 20% of total HAAs on a molar basis. This increased to approximately 50% as Br-/DOC increased to approximately 25microM/mM or more, proving that a large fraction of HAAs may not be covered under existing federal regulations. Total THM and HAA9 concentrations decreased in permeate waters with increasing Br-/DOC suggesting that nanofilter permeates are limited with respect to DBP precursors.     

Bacteriophage inactivation by UV-A illuminated fullerenes: role of nanoparticle-virus association and biological targets

Inactivation rates of the MS2 bacteriophage and (1)O(2) generation rates by four different photosensitized aqueous fullerene suspensions were in the same order: aqu-nC(60) < C(60)(OH)(6) ≈ C(60)(OH)(24) < C(60)(NH(2))(6). Alterations to capsid protein secondary structures and protein oxidation were inferred by detecting changes in infrared vibrational frequencies and carbonyl groups respectively. MS2 inactivation appears to be the result of loss of capsid structural integrity (localized deformation) and the reduced ability to eject genomic RNA into its bacterial host. Evidence is also presented for possible capsid rupture in MS2 exposed to UV-A illuminated C(60)(NH(2))(6) through TEM imagery and detection of RNA infrared fingerprints in ATR-FTIR spectra. Fullerene-virus mixtures were also directly visualized in the aqueous phase using a novel enhanced darkfield transmission optical microscope fitted with a hyperspectral imaging (HSI) spectrometer. Perturbations in intermolecular extended chains, HSI, and electrostatic interactions suggest that inactivation is a function of the relative proximity between nanoparticles and viruses and (1)O(2) generation rate. MS2 log survival ratios were linearly related to CT (product of (1)O(2) concentration C and exposure time T) demonstrating the applicability of classical Chick-Watson kinetics for all fullerenes employed in this study. Results suggest that antiviral properties of fullerenes can be increased by adjusting the type of surface functionalization and extent of cage derivatization thereby increasing the (1)O(2) generation rate and facilitating closer association with biological targets.     

Inactivation of bacteriophages via photosensitization of fullerol nanoparticles

The production of two reactive oxygen species through UV photosensitization of polyhydroxylated fullerene (fullerol) is shown to enhance viral inactivation rates. The production of both singlet oxygen and superoxide by fullerol in the presence of UV light is confirmed via two unique methods: electron paramagnetic resonance and reduction of nitro blue tetrazolium. These findings build on previous results both in the area of fullerene photosensitization and in the area of fullerene impact on microfauna. Results showed thatthe first-order MS2 bacteriophage inactivation rate nearly doubled due to the presence of singlet oxygen and increased by 125% due to singlet oxygen and superoxide as compared to UVA illumination alone. When fullerol and NADH are present in solution, dark inactivation of viruses occurs at nearly the same rate as that produced by UVA illumination without nanoparticles. These results suggest a potential for fullerenes to impact virus populations in both natural and engineered systems ranging from surface waters to disinfection technologies for water and wastewater treatment.     

Molecular characterization and tissue distribution of ferritin M in kelp grouper, Epinephelus bruneus

This study, reports the identification and analysis of ferritin M chain, from kelp grouper, Epinephelus bruneus (EbFerM); it comprises 1004 base pair (bp), including 528 bp open reading frame (ORF) which encodes 176 amino acid (aa) residues; the calculated molecular weight is 20 kDa. The 5′-untranslated region (UTR) possesses 476 bp proceeded by a putative Iron Regulatory Element (IRE). Pair wise alignments showed that EbFerM shared 94% identity with that of Larimichthys crocea and Sciaenops. It is expressed in abundance in liver, spleen, and kidney when challenged with Vibrio anguillarum, lipopolysaccharide (LPS), or poly I:C.     

Slip at a uniformly porous boundary: effect on fluid flow and mass transfer

An approximate solution to the 2-D Navier-Stokes equations for steady, isothermal, incompressible, laminar flow in a channel bounded by one porous wall subject to uniform suction is derived. The solution is valid for small values of the Reynolds number based on the suction velocity and channel height. Solute transport is considered numerically by decoupling the equations representing momentum and mass transfer. The effect of fluid slip at the porous boundary on the axial and transverse components of fluid velocity, axial pressure drop and mass transfer is investigated.