Ultra Filtration Research Papers - Academia.edu (original) (raw)

Para evaluar la eficiencia de concentración de las proteínas del suero con una planta móvil compuesta por un módulo de ultrafiltración y otro de nanofiltración, se determinó la composición en sólidos totales, proteína, ceniza y lactosa del suero inicial, del concentrado proteico y de los permeados de ultra y nano filtración. El contenido en cenizas se determinó por el método oficial de la AOAC, sólidos totales por Mojonier, lactosa por colorimetría con ácido pícrico y proteína por Microkjeldahl. Los porcentajes de remoción de los compuestos en los permeados se calcularon en base a los balances de materia seca obtenidos cuando el 95% del volumen del suero original había sido removido como permeado. Se encontró que los permeados de la ultrafiltración y la nanofiltración contenían 7,31% y 5,47% de sólidos totales, de los cuales el 71,13% y el 70,46% respectivamente, fue lactosa. La eficiencia de concentración de la proteína del suero con la planta móvil de ultra y nanofiltración tangencial se hizo evidente al obtenerse un concentrado proteico que alcanzó un contenido en sólidos totales de 20,29%, de los cuales 29,17 era lactosa y 51,84% era proteína.

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- Ultra Filtration, Dry Mass, Whey protein concentrate

Aim. To verify the rationale of a pelvic stop-flow technique for the perfusion of high-doses of mitomycin C and anthacyclines in patients with inoperable, recurrent pelvic cancer.Methods. The stop-flow technique was realized by using percutaneous double-balloon arterial–venous catheters that selectively isolate the pelvic vascular section and a perfusion provided by an extracorporeal pump for 20 min. Ten patients (pts) with unresectable pelvic recurrence from colon-rectal cancer were treated with a combination of Mitomycin C (MMC, 20 mg/sqm) plus doxorubicin (DOXO, 75 mg/sqm; 8 pts) or epirubicin (EPI, 75 mg/sqm; 2 pts) infused into the isolated pelvic compartment. Blood samples were collected from the extracorporeal vascular flow and from peripheral plasma, and analysed for drug quantitation.Results. During the procedure, there were no technical or hemodynamic complications, and no deaths occurred during surgery or in the postoperative period. MMC and DOXO peak levels measured in the extracorporeal system which irrotates the tumor area, were on average 21.6 (range: 4.3–44.3, MMC) and 17.2 (range: 1.8–48.4, DOXO) times higher than those observed in the peripheral blood. Similarly; the area under concentration (AUC) versus time curves measured in the pelvic compartment during stop-flow perfusion were 19.9 (range: 3.8–45.0, MMC) and 13.4 (range: 1.2–26.6, DOXO) times higher than the corresponding value in peripheral circulation. The drug percentage eliminated in the ultra filtrate was only 7.7% (MMC) and 0.9% (DOXO), and the plasmatic AUC0–24 were similar to those observed with iv bolus of equivalent drug doses. Minimal systemic and local toxicities were observed. One complete pathological and 2 partial responses were observed; pain remission in 8/10 patients. Median survival was 12 months (8–31).Conclusion. The endo-arterial administration into the local vasculature produces high pelvic-systemic concentration gradients during the stop-flow perfusion with limited local and systemic toxicity. The encouraging clinical results suggest further evaluation.

- by Elena Strocchi
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- Treatment Outcome, Adolescent, Blood sampling, Aged

Aflatoxin M 1 (AFM 1) is an important mycotoxin frequently found in milk and in dairy products. It is a minor metabolic product of Aspergillus flavus and A parasiticus. However, it occurs in dairy products as a metabolite formed in cows from aflatoxin B 1 contained in animal feeds. In cheese production, AFM 1 distributes between curd and whey, being present in products derived from cheese whey processing. In this study, cheese whey from dairy processing was artificially contaminated with the mycotoxin at about 0.1 µg l −1. Ultra-filtration experiments of whey were carried out in order to determinate AFM 1 distribution between retentate (protein-rich fraction) and permeate (lactose-rich fraction). Recoveries of AFM 1 in retentate were 72.6-86.4% while, in permeate, recoveries were in the range 2.4-14.7%. Partition coefficients of AFM 1 , lactose and protein were calculated to determine whether there was an interaction between AFM 1 and protein. In all experiments, AFM 1 partition coefficient was lower than 1, whilst for lactose coefficients close to 1 were determined, showing an affinity of aflatoxin M 1 to the protein-rich fraction (retentate).

- by Carla Mendonça
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- Engineering, Chemistry, Food Safety, Partition Coefficient

Ultra-filtration (UF) provides a new way of generating narrow bands of sample in the fractionation of coal and petroleum-derived liquids. It allows larger quantities of high-mass fractions to be recovered, making more detailed investigations possible, through the use of techniques requiring larger amounts of sample. In this work, UF-separated fractions have been used to study molecular mass distributions of a coal tar pitch, used as laboratory standard. The pitch was fractionated by solvent solubility into three fractions. These were further fractionated by ultra-filtration, using membranes specific to protein molecular sizes classed as ''1 kDa", ''5 kDa", ''10 kDa" and ''100 kDa". Planar chromatography was used as a tertiary fractionation method, to subdivide the UF-fractions. The various fractions were examined by size exclusion chromatography (SEC), UV-fluorescence spectroscopy and laser desorption-mass spectrometry (LD-MS). There was good agreement between mass estimates based on SEC and LD-MS of the smaller UF-fractions, with evidence for the presence of material with molecular masses ranging between 800 and 10,000 u. Examining the largest UF fractions of the pitch-pyridine-insoluble sample also gave clear evidence for material with molecular masses above 10,000 u. Taken together, however, the LD-MS data showed progressively diminishing differences, as the sizes of the UF membranes, and the likely molecular masses of the sample fractions, increased. One likely explanation is incomplete sampling during the laser desorption procedure. The evidence suggests that the upper mass limit detectable for these and similar samples by LD-MS has been reached. Despite these reservations, LD-MS appears as the best method to date, for investigating the mass ranges of samples derived from coal tar pitch and heavy petroleum fractions.

Membrane bioreactor biofouling is usually described as an extracellular matrix in which biopolymers, inorganic salts and active microbes co-exist. For that reason, biomineralization (BM) models can be useful to describe the spatial organization and environmental constraints within the referred scenario. BM arguments were utilized as background in order to (1) evaluate CaCO 3 influence on flux decline; pore blocking and cake layer properties (resistance, permeability and compressibility) in a wide range of Chitosan/ Bovine serum albumin (BSA) mixtures during step-pressure runs and, (2) perform membrane autopsies in order to explore the genesis of mineralized extracellular building blocks (MEBB) during cake layer build up. Using low molecular weight chitosan (LC) and BSA, 2 L of 5 LC/BSA mixtures (0.25-1.85 ratio) were pumped to an external ultra filtration (UF) membrane (23.5 cm 2 , hydrophobic, piezoelectric, 100 kDa as molecular weight cut-off). Eight different pressure steps (40 ± 7 to 540 ± 21 kPa) were applied. Each pressure step was held for 900 s. CaCO 3 was added to LC/BSA mixtures at 0.5, 1.5 and 3 mM in order to create MEBB during the filtration tests. Membrane autopsies were performed after the filtration tests using thermo gravimetric, scanning microscopy and specific membrane mass (mg cm À2 ) analyses. Biopolymer-CaCO 3 step-pressure filtration created compressible cake layers (with inner voids). The formation of an internal skeleton of MEBB may contribute to irreversible fouling consolidation. A hypothesis for MEBB genesis and development was set forth.

- by Adalberto Noyola
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- Chitosan, Filtration, Multidisciplinary, Extracellular Matrix

Water is critical to paper production and increasing competition from other users has reduced water availability to paper mills in recent years. The study was conducted at a large-scale integrated pulp and paper industry. The study conducted at laboratory for recycling of effluents was aimed at reducing water foot print of the paper mill. Paper machine section effluent was identified for treatment and reuse based on the flow and characteristics. Chemical aided clarification and simple membrane filtration systems were used for water recovery. Closing the water loop through suitable treatment for reuse of wastewater in the paper mills provides an assured and continuous source of water. Pollutant reductions at the rate of 87.5%, 75% and 89% were obtained on SS, COD and turbidity, respectively. Operational and capital costs were delineated for selection of treatment option and enhanced water recovery. Feasibility of micro/ultra filtration combination was assessed to reduce costs for water recovery. This combination removed up to 93% and 91.7% of SS and COD from the effluents. The treatment options assessed for water recovery reduced freshwater consumption by about 40% and the excess treated water was stored in ponds for process use during the lean season.

- by Rita Dhodapkar
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- Engineering, Water Availability, Desalination, Seasonality

For the production of highly concentrated monoclonal antibody intermediate solutions in the course of downstream processing, ultra filtration is the industry standard in manufacturing scale. Key challenges are to achieve high end concentrations and to reduce both process time and aggregate formation, particularly for therapeutic proteins, intended for subcutaneous administration. Therefore, in this study the effects of operational parameters on permeate flux and aggregation in the concentrated solutions were investigated. An optimized ultrafiltration concentration method was developed based on systematic screening of cross-flow rate and transmembrane pressure at different protein concentrations in the retentate. In this method flow and pressure values are adjusted depending on the prevailing retentate concentration. The resulting three stage protocol reduces process time and assures a low aggregate burden compared to concentration processes operated at constant flow and pressure conditions. Flow and pressure profiles were set and recorded in lab scale using an automated tangential flow filtration system which has been shown to adequately reflect process conditions at manufacturing scale. The formation of IgG aggregates was monitored by turbidity measurement, SE-HPLC, light obscuration, dynamic light scattering and a microscopic method. These techniques allow characterization of a wide range of aggregate sizes of soluble and insoluble aggregates that can occur during processing. In addition, FT-IR spectroscopy was performed to investigate secondary structure of the aggregates, revealing different quantities of structurally perturbed protein depending on applied flow and pressure conditions. Finally, the concentrated material derived from the optimized method showed improved processability at sterile filtration which is an important manufacturing step prior to storage.

- by Eva Rosenberg and +2
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- Engineering, Membrane Science, Ultrafiltration, Dynamic Light Scattering

Advances in dairy foods and dairy foods processing since 1981 have influenced consumers and processors of dairy products. Consumer benefits include dairy products with enhanced nutrition and product functionality for specific applications. Processors convert raw milk to finished product with improved efficiencies and have developed processing technologies to improve traditional products and to introduce new products for expanding the dairy foods market. Membrane processing evolved from a laboratory technique to a major industrial process for milk and whey processing. Ultra-filtration and reverse osmosis have been used extensively in fractionation of milk and whey components. Advances in cheese manufacturing methods have included mechanization of the making process. Membrane processing has allowed uniform composition of the cheese milk and starter cultures have become more predictable. Cheese vats have become larger and enclosed as well as computer controlled. Researchers have learne...

- by Rajiv Dave
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- Dairy Science, Animal Production, Food Processing, Food Technology

Grey water is an alternative source of water which can potentially save a significant quantity of precious drinking water. The present study emphasizes primarily on the treatment of greywater to make it fit for serving various purposes. This paper provides an insight into the design of laboratory scale grey water treatment system, comprises of oxidative mineralization, disinfection, and filtration of grey water. Laboratory scale treatability trails were performed by the means of synthetic grey water and real grey water. Grey water treatment system demonstrated satisfactory removal of contaminants which was evident from the COD removal efficiency of 85% and 90%, TSS removal efficiency of 98% and 86%, and faecal coliform with removal efficiencies of 99% and 96% respectively. It could be inferred from the study finding that the treated water possed low turbidity value (< 1 NTU) and was free of suspended solids. Thus this study explored the capability of the grey water treatment system to carry electrochemical oxidation of grey water contaminants and making treated water fits for reuse. This implies that this treatment technology possesses the potential to be considered as a viable alternative to conventional grey water treatment systems.

Membrane separation technology was used to remove free glycerol from biodiesel in order to meet the ASTM D6751 and EN 14214 standards. Fatty acid methyl esters (FAME) produced from canola oil and methanol were purified using ultra-filtration. The effect of different materials present in the transesterification reaction, such as water, soap, and methanol, on the final free glycerol separation was studied. A modified polyacrylonitrile (PAN) membrane, with 100 kD molecular weight cut-off was used in all runs. Tests were performed at 25°C and 552 kPa operating pressure. The free glycerol content in the feed, retentate and permeate of the membrane system was analyzed using gas chromatography according to ASTM D6584. Results showed low concentrations of water had a considerable effect in removing glycerol from the FAME even at approx. 0.08 mass%. This is four orders of magnitude less than the amount of water required in a conventional biodiesel purification process using water washing. It is suggested that the mechanism of separation of free glycerol from FAME was due to the removal of an ultrafine dispersed glycerol-rich phase present in the untreated FAME. This was confirmed by the presence of particulates in the untreated FAME. The size of the particles and the free glycerol separation both increased with increasing water content of the FAME. The trends of separation and particle size vs. water content in the FAME phase were very similar and exhibited a sudden increase at 0.08 mass% water in the untreated FAME. This supports the conclusion that water increased the size of the distributed glycerol phase in the untreated FAME leading to its separation by the ultra-filtration membrane. The technology for the removal of free glycerol from biodiesel was found to use 2.0 g of water per L of treated FAME (0.225 mass% water) vs. the current 10 L of water per L of treated FAME.

- by jehad saleh
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- Mechanical Engineering, Chemical Engineering, Biodiesel, Filtration

Thuringiensin is a heat stable β-exotoxin from Bacillus thuringiensis with a great potential for replacing the traditional chemical pesticides. A process using micellar-enhanced ultrafitration method to recover thuringiensin was significantly improved by the use of a spiral-wound membrane, which could be operated at a low transmembrane pressure drop. This method was performed by adding a surfactant cetylpyridinium chloride (CPC) into the fermentation broth. After the surfactant-thuringiensin conjugates were formed, the broth then passed through the ultrafiltration membrane and the retentate was collected. The results indicated the optimal concentration of CPC for producing a maximal recovery up to 99.3% is 4%. For purification, the centrifuged broth was further filtered by a membrane filter. The filtered solution then was mixed with 50% of activated carbon. The supernatant then was injected into a preparative HPLC. The eluate was collected during thuringiensin peak formation. This eluate was then concentrated by vacuum evaporation and dialysis using an electrodialyzer to remove the excess salts. The dialyzed solution was then crystallized by lyophilization. The purity of the thuringiensin crystal was identified by HPLC, capillary electrophoresis, and mass spectrometry.

- by Yew-Min Tzeng
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- Mass Spectrometry, Capillary electrophoresis, Activated Carbon, Bioseparation

The specific purpose of this study was to compare three different collagen extraction methods commonly used in isotope laboratories conducting dietary studies. We evaluated their resultant differences in d 13 C and d 15 N, collagen quality and collagen yield. Our study was based on well-preserved skeletal material from the medieval period in Denmark. Our study shows that there is a systematic significant difference in the yield and the d 13 C values between the three methods. Using the method of DeNiro and Epstein [DeNiro, M.J., Epstein, S., 1981. Influence of diet on the distribution of nitrogen isotopes in animals. Geochimica et Cosmochimica Acta 45, 341e351] with NaOH as cleaning agent, will, according to our study, give d 13 C values that are on average AE0.32& more positive than using the ultra-filtration method [Brown, T.A., Nelson, D.E., Vogel, J.S., Southon, J.R., 1988. Improved collagen extraction by modified Longin method. Radiocarbon 30 (2), 171e177, modified in Richards, M.P., Hedges R.E.M., 1999. Stable isotope evidence for similarities in the types of marine foods used by late Mesolithic humans at sites along the Atlantic coast of Europe. Journal of Archaeological Science 26, 717e722]. The third method, which is a modified version of the second method, excluded the ultra-filtration step. This method seems to give d 13 C values that lie in between the other methods. Our study did not show any significant difference in d 15 N values. Although the differences between the methods are very small, we conclude that the use of stable isotope analysis in food determination studies requires adherence to routine methods for preparing and measuring samples.

- by Niels Lynnerup and +1
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- Archaeology, Geochemistry, Stable Isotope Analysis, Archaeological Science

Polyamidehomopolymer and block copolymernanocomposites were prepared by melt processing using a co-rotating Leistritz twin screw extruder. The polymers used werepolyamide 11 (PA11) and poly (ether-block-amide), Pebax 7233. Commercially available nanoclay, Cloisite 30B was chosen as the nanofiller in this study. Particular emphasis was placed on better defining the morphological and performance characteristics of the nanocomposites prepared.Analytical techniques such as X-ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and short-term mechanical tests were employed to characterise the nanocomposite materials.XRD analysis confirmed an exfoliated structure for PA11 nanocomposite at low loading whereas for Pebax 7233, an increase in d 001 spacing suggests an intercalated structure exists. There was no significant change in melting temperature for PA11 and Pebax 7233 due to nanoclay addition; however, the crystallinity was found to decrease as measured by DSC.The performance characteristics of both nanocomposites systems were established using short-term tensile and DMA techniques.A significant increase in storage modulus was observed for both nanocomposite systems investigated.

Milk concentrates are used in the production of cast cheese. The effects of pH (5.19-6.21) and NaCl concentration (0, 1.75% and 3.50%, w/w) on the rheological and microstructural properties of rennet-induced casein gels made from ultra filtered skim milk (19.8%, w/w casein) were investigated. Low pH and high NaCl concentration reduced the development rate of the gel elasticity after coagulation of the ultra filtrated skim milk. Strain at fracture and stress at fracture from uniaxial compression of casein gels 48 h after coagulation showed maximum and minimum values at pH $5.8 and 5.29, respectively. Young's modulus from uniaxial compression of the same gels was almost constant between pH 5.52 and 6.21 but much lower at pH 5.28. Addition of NaCl resulted in increased Young's modulus in the interval pH 6.21-5.52. As pH decreased, the level of colloidal calcium phosphate decreased concomitantly, giving less cross-links in the casein network and partly explaining the changes in the rheological properties. Increased ionic strength by adjusting pH and addition of NaCl also influenced rheological results. The microstructure examined with confocal laser-scanning microscopy was unaffected by the changes in pH and concentrations of NaCl in the range studied as revealed by image analysis and calculations of two-and threedimensional data from micrographs.

- by Richard Ipsen and +1
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- Image Analysis, Dairy, Clinical Sciences, Rheological properties

High strength milk permeate derived from ultra-filtration based cheese making process was treated in an anaerobic moving bed biofilm reactor (AMBBR) under mesophilic (35°C) condition. Total chemical oxygen demand (TCOD) removal efficiencies of 86.3-73.2% were achieved at organic loading rates (OLR) of 2.0-20.0 g TCOD L À1 d À1 . A mass balance model gave values of methane yield coefficient (Y G/S ) and cell maintenance coefficient (k m ) of 0.341 L CH 4 g À1 TCOD removed and 0.1808 g TCOD removed g À1 VSS d À1 , respectively. The maximum substrate utilization rate U max was determined as 89.3 g TCOD L À1 d À1 by a modified Stover-Kincannon model. Volumetric methane production rates (VMPR) were shown to correlate with the biodegradable TCOD concentration through a Michaelis-Menten type equation. Moreover, based on VMPR and OLR removed from the reactor, the sludge production yield was determined as 0.0794 g VSS g À1 TCOD removed .

- by R. Qiu
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- Algorithms, Biofilms, Kinetics, Water Purification
- by Maurizio Petruccioli and +1
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- Humic acid, Detoxification, Laccase, Process biochemistry

Water management plays a vital role in steel industry. The present work is carried out in cold rolling mill aiming to recovery maximum water. In CRM process the acid waste, alkaline waste and oil and grease wastewater generated. This wastewater is treated in effluent treatment plant and then it is desalinized to avoid the salt concentration in water circulation system by implementing ultra-filtration and RO system. It is found there is membrane fouling in RO3 system due to increase in hardness at the inlet it is reduced by adding lime and soda ash. Results shows that most salts are removed by UF and RO treatment and high quality of water is obtained. It is found that reusing the desalinated wastewater found more economical then discharging.

- by GRD JOURNALS and +1
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- Desalination, Reverse osmosis, Ultra Filtration, membrane fouling

Extracellular laccase from Panus tigrinus CBS 577.79 was produced in a bubblecolumn reactor using glucose-containing medium supplemented with 2,5-xylidine under conditions of nitrogen sufficiency. The main laccase isoenzyme was purified to apparent homogeneity by ultra-filtration, anion-exchange chromatography and gel filtration that led to a purified enzyme with a specific activity of 317 IU (mg protein) -1 and a final yield of 66%. Laccase was found to be a monomeric protein with a molecular mass of 69.1 kDa, pI of 3.15 and 6.9% N-glycosylation of the high mannose type. Temperature and pH optima were 55°C and 3.75 (2,6-dimethoxyphenol as substrate). At 50 and 60°C, the enzyme halflives were 281 and 25 min, respectively. The P. tigrinus laccase oxidized a wide range of both naturally occurring and synthetic aromatic compounds: the highest catalytic efficiencies were for 2,2¢-azinobis-(3-ethylbenzthiazoline-6-sulfonic) acid and 2,6-dimethoxyphenol (5.99 · 10 6 and 3.07 · 10 6 M -1 s -1 , respectively). Catalytic rate constants for typical N-OH redox mediators, such as 1-hydroxybenzotriazole (2.6 s -1 ), violuric acid (8.4 s -1 ) and 2,2,6,6-tetramethylpiperidin-N-oxide radical (7.8 s -1 ), were found to be higher than those reported for other high redox potential fungal laccases.

- by Ahmad Adnan
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- Engineering, Microbiology, Physical Chemistry, Chromatography

BACKGROUND: Ternary nanocomposites containing an organomodified layered silicate polyimide additive within a polyamide matrix have been investigated to gain greater insight into structure–property relationships and potential high-temperature automotive applications.RESULTS: Polyamide nanocomposite blends, containing 3 wt% of organoclay, were prepared and compared with organoclay-reinforced polyamide and neat polyamide. Nanoclay addition significantly increased heat distortion temperature, as well as both the tensile and flexural moduli and strength. The addition of polyimide demonstrated further increases in heat distortion temperature, glass transition temperature and the flexural and tensile moduli by about 17, 21 and 40%, respectively. The tensile and flexural strengths were either unaffected or decreased modestly, although the strain-to-failure decreased substantially. Morphological studies using transmission electron microscopy (TEM) and X-ray diffraction showed that the nanoclay was dispersed within the ternary blends forming highly intercalated nanocomposites, regardless of the presence and level of polyimide. However, TEM revealed clay agglomeration at the polyamide–polyimide interface which degraded the mechanical properties.CONCLUSIONS: A range of improvements in mechanical properties have been achieved through the addition of a polyimide additive to a polyamide nanocomposite. The decrease in ductility, arising from the poor polyamide–polyimide interface and nanoclay clustering, clearly requires improving for this deficiency to be overcome. Copyright © 2008 Society of Chemical Industry

Background. The clinical determinants of baseline peritoneal membrane (PM) transport characteristics, as evaluated by a hypertonic peritoneal equilibration test (PET), remain ill-defined. Likewise, the longi- tudinal evolution of PM transport properties in peritoneal dialysis (PD) patients given automated PD (APD) and icodextrin still needs to be determined precisely. The aims of the present study were (1) to determine the clinical

- by Pierre Wallemacq and +1
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- Ultrafiltration, Transport Properties, Follow-up studies, Solute transport

DNA appears to decay by random chain scission resulting in a predictable range of fragment lengths. Collagen decay has also been modelled in this same way, although it has become increasingly evident that collagen decay does not follow this same pattern. Radiocarbon and stable isotope analysis now use ultra-filtration to isolate large fragments (>30% of original polymer length) even in Pleistocene bone. How then does collagen decay? This study contrasts experimentally degraded samples with collagen extracted from forensic, archaeological and fossil bone. In experimentally degraded bone, values for amino acid and elemental (C:N) composition, bulk δ 13 C, δ 15 N, and aspartic acid racemisation (AAR) changed very little until 99% of the collagen was lost, suggesting that the collagen triple helix and polypeptide chains remained remarkably intact. This suggestion was demonstrated directly by examining the integrity of individual polypeptide chains using cyanogen bromide (CNBr) cleavage followed by SDS-PAGE electrophoresis. In ancient samples, AAR values remain remarkably stable and the pattern of CNBr-cleavage was only replaced with a smear of smaller polypeptides in the oldest (Pleistocene) bones investigated. Smearing may reflect both modification of the methionine resides (the sites of CNBrcleavage) and/or partial hydrolysis of the collagen molecule. The findings reveal why it is not usually necessary to worry about collagen diagenesis; it is mostly intact. However, evidence of partial deterioration of the oldest bone samples suggests that alternative purification strategies may increase yields in some samples.

- by Kirsty Penkman
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- Archaeology, Geology, Stable Isotope Analysis, Triple Helix

The aim of this work was to evaluate the loss of sugars (glucose, fructose and sucrose) in pineapple juice (Ananas comosus, L. Merril), Pérola cv., hydrolyzed with commercial pectinase (Ultrazym 100G) alone and combined with a cellulase (Celluclast) as a pre-treatment, and after clarification by cross flow micro-and ultra-filtration, using two different module geometries (plate/frame and tubular systems) to select the membrane process that would best preserve these nutrients. Membranes of polysulfone (PS), polyethersulfone (PES) and polyvinylidene fluoride (PVdF) to micro-and ultra-filtration were used. The membrane pore diameters and cutoffs were: 0.1, 0.45 lm, and 50, 100 KDa (PS), and 0.3 lm and 30-80 KDa (PES and PVdF). All processes were operated at different trans-membrane pressures (TMP), at room temperature (25°C ± 2). The sugar contents of the clarified pineapple juices determined by HPLC revealed significant differences at a 5% level. These results showed that the membrane pore diameters or cutoffs as well as the module geometry influenced the clarified juice sugar contents. It was observed that the sugar content was more reduced when the 30-80 KDa tubular membrane at 1.5 bar was used for pineapple juice clarification. Although the best total sugar recoveries have been observed in juices clarified with polysulfone membranes (50 KDa-7.5 bar), the use of 0.3 lm PES, due to its tubular configuration and module geometry, is more attractive and appropriate.

- by Izabela Castro
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- Food Engineering, Food, Filtration, High Performance Liquid Chromatography

Apple scab (black spot) is caused by the fungus, Venturia inaequalis. Race 1 isolates of this fungus are avirulent on Malus hosts carrying the resistance gene V m : Detached leaves from a V m host (resistant, differential host 5) and 'Royal Gala' (susceptible, host 1) were inoculated with a conidial suspension of V. inaequalis. In the resistant reaction, a hypersensitive response (HR), characterised by necrosis and the accumulation of autofluorescent materials in epidermal and mesophyll cells, was observed at the site of fungal penetration. No HR was observed in the susceptible host. V. inaequalis grown in vitro produced an elicitor that induced necrosis, similar to the HR, when infiltrated into leaves of the resistant V m host. No response, however, was observed in the susceptible host. The elicitor was proteinaceous and a fraction with elicitor activity was isolated using ultra-filtration, acetone precipitation and ion-exchange chromatography. The elicitor activity was resistant to boiling but it was abolished by digestion with proteinase K. The protein fraction contained three major proteins all with low isoelectric points (pI 3·0-4·5). The fraction also elicited necrosis in the differential host 4, but not in any of the other resistant hosts tested, including differential hosts 2, 3, and 6. Therefore, the fraction may contain elicitors with more than one host specificity. q

- by Win Kim
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- Biochemistry, Genetics, Microbiology, Mycology

Interactions between soluble enzymes and interfaces of organic solvent drops or gas bubbles have a very negative effect on the operational stability of the soluble enzymes. In this study, the formation of a hydrophilic shell around the enzyme has been attempted using dextran-aldehyde which would prevent the interaction between enzyme and hydrophobic interfaces with minimal modification of the enzyme surface. After optimizing the size of the dextran (that was found to play a critical role), three different enzymes (glucose oxidase, d-amino acid oxidase, and trypsin) have been conjugated with dextran-aldehyde and their stability towards organic-aqueous and air-liquid interfaces has been evaluated. The treatment itself proved to be very low-cost in terms of activity and was highly stabilizing for the three enzymes assayed. The conjugated preparation of the three assayed enzymes remained fully active in the presence of air-liquid interfaces for at least 10 h. However, the unmodified enzymes lost more than 50% of activity within the first hour of the experiments except for trypsin which kept 38% activity after 12 h while the trypsin dextran-aldehyde conjugate maintained 100% enzyme activity. Similar results were achieved in the presence of stirred organic solvent-aqueous buffer biphasic system, although in this case some activity was lost by the action of the soluble portion of the organic solvent. In fact, this treatment seems to be also effective to improve the resistance to the action of organic solvent.

- by José Guisán
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- Engineering, Chemistry, Technology, Biotechnology
- by Pablo Vélez
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- DNA repair, Solvent Extraction, Polymerase Chain Reaction, Ultra Filtration

An ultra-performance liquid chromatographytandem mass spectrometry method was developed, optimised and validated for the quantification of synthetic folic acid (FA), also called pteroyl-L-glutamic acid or vitamin B9 and naturally occurring 5-methyltetrahydrofolate (5-MTHF) found in folate-fortified breads. Optimised sample preparation prior to analysis involved addition of 13 C 5 labelled internal standards, treatments with α-amylase and rat serum, solid-phase extraction using aromatic-selective cartridges and ultra-filtration. Analytes were separated on a Waters ACQUITY HSS T3 column during a 6-min run and analysed by positive ion electrospray selected reaction monitoring MS/MS. Standard calibration curves for the two analytes were linear over the range of 0.018-14 μg FA/g of fresh bread (r 2 =0.997) and 9.3-900 ng 5-MTHF/g of fresh bread (r 2 =0.999). The absolute recoveries were 90% and 76% for FA and 5-MTHF, respectively. Intra-day coefficients of variation were 3% for FA and 18% for 5-MTHF.

- by Martin Bucknall and +2
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- Engineering, Australia, Folic acid, Sample Preparation
- by Atheesha Singh
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- Virology, Canonical Correlation, Centrifugation, Ultra Filtration

The separation of stillage was tested by means of the pilot plantARNO600-BIO using three-channel ceramic membranes with the pore diameter range from microfiltration to ultrafiltration (1.4 µm–5 kDa). The permeate from the last membrane step was able to be recycled as technological water. The best results were achieved in the arrangement of series using 0.2 µm membrane as the first step supplemented by ultra-filtration membranes (50 kDa and 15 kDa), predominantly, where the reduction of the chemical oxygen demand (COD) extended 80%. With this process, we try to get some advantages over the conventional process in terms of eliminating both land and energy costs for the wastewater treatment process and improving the quality of the discharge water. The main goal in this study is to analyse different separation steps and conditions to find both the best separation options for the decrease of the final volume of distillery stillage, and the way how to make the bio e...

- by Mojmír Rychtera
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- Chemistry, Waste water treatment, Profitability, Ethanol Production

Investigations were carried out in order to solidify in cement a low-level radioactive waste of complex chemistry obtained by mixing two process streams, a slurry produced by ultra-filtration and an evaporator concentrate with a salinity of 600 gxL − 1. Direct cementation with Portland cement (OPC) was not possible due to a very long setting time of cement resulting from borates and phosphates contained in the waste. According to a classical approach, this difficulty could be solved by pre-treating the waste to reduce adverse cement-waste interactions. A two-stage process was defined, including precipitation of phosphates and sulfates at 60°C by adding calcium and barium hydroxide to the waste stream, and encapsulation with a blend of OPC and calcium aluminate cement (CAC) to convert borates into calcium quadriboroaluminate. The material obtained with a 30% waste loading complied with specifications. However, the pre-treatment step made the process complex and costly. A new alternative was then developed: the direct encapsulation of the waste with a blend of OPC and calcium sulfoaluminate cement (CSĀ) at room temperature. Setting inhibition was suppressed, which probably resulted from the fact that, when hydrating, CSĀ cement formed significant amounts of ettringite and calcium monosulfoaluminate hydrate which incorporated borates into their structure. As a consequence, the waste loading could be increased to 56% while keeping acceptable properties at the laboratory scale.

- by C. Cau-dit-coumes
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- Civil Engineering, Leaching, Scanning Electron Microscopy, Waste Management

Third International Conference on Engineering for Waste and Biomass Valorization, May 2010, Beijing, China. The metals such as vanadium, nickel and iron are identified in the typical crude oils extracted from oil bearing rocks. The produced water contains salts, heavy metals, emulsified oil and other organics after the hot water extraction process (HWEP) of bitumen from oil sands. This is a serious environmental problem waiting for technically and economically feasible solutions. Membrane technologies such as ultra filtration, nanofiltration, and reverse osmosis are widely used in water purification and they are also applied for produced-water (wastewater stream in oil and gas production) purification. This study focuses on the transport of Vanadium (V) and Nickel (II) through activated composite membranes (ACMs) based on carrier Aliquat 336, in cyclohexane and dodecane. Reagents and materials, without further purification, and double distilled water were used. The UV-visible spectrophotometer and Atomic Absorption Spectrometer (FAAS) were utilised for measuring the concentrations of metal ions from aqueous solutions. Optimum conditions for both feed (pH \ 7) and permeate (pH [ 8) solutions, the influence of hydrodynamic conditions, the concentration of carrier on membrane (0.2, 0.5 and 0.7 M), the influence of aqueous feed acidity (4 \ pH \ 7), the influence of permeate reagents (NH 3 , HNO 3, and Na 2 CO 3 ) and the efficiency of separation process were established. The experiments were carried out

- by Larisa Melita
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- Environmental Engineering, Chemical Engineering, Water Purification, Oil and gas

- by Oliver Craig and +3
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- Archaeology, Geology, Stable Isotope Analysis, Triple Helix

Hydrologic runo is one of the main processes in which radionuclides deposited in the surface environment migrate widely in both particulate and dissolved forms. This paper focuses on the transfer capability of long lived Chernobyl radionuclides from surface soil to river water in dissolved forms. First, concentration and speciation of radioactive Cs, Sr and transuranic isotopes, such as Pu and Am, were examined in undisturbed surface soil along the river in the exclusion zone (30 km zone) near the Chernobyl Nuclear Power Plant (NPP) in order to validate the radioactive contamination characteristics. Almost all radioactivities exist in the very top surface in the undisturbed soil layer. Sr-90 in the soil was estimated to be highest in the water soluble and exchangeable fractions, which were easily accessible to river water as a dissolved fraction. Pu isotopes and Am-241 are major radionuclides in free humic and free fulvic acid fractions. Secondly, surface soil near the Sahan River was extracted with distilled water, as an analogue of rain water, to estimate the dissolved fraction in runo components from surface soil to river water. After a ®ltration procedure, extracted water was treated with ultra ®ltration techniques separating the molecular weight fractions of beyond and below 10,000 Da. Each fraction was measured for the radioactivity and the characteristics of organic materials including humic substances. Most Pu and Am exist in the molecular weight fractions beyond 10,000 Da, in spite of the fact that most of the dissolved organic fractions exist below 10,000 Da. This means that transuranic elements such as Pu and Am are associated with mobile high molecular weight materials like fulvic acids in water leachates.

- by Hikaru Amano
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- Earth Sciences, Speciation, Organic Geochemistry, Ultrafiltration

Ceramic membranes coated with ZrO 2 were used for the continuous separation of a well-defined low molecular weight lignin from softwood and hardwood kraft black liquors on a pilot scale. The membranes used had M w cutoffs of 1000, 5000, and 15,000 Da, respectively. The flux (permeate flow) through the different membranes measured as L/(m 2 •h) was studied by varying the inlet pressure and temperature. The black liquor lignins in the permeate from the filters were isolated and studied with GPC and UV spectroscopy. The low molecular weight lignin fraction was highly phenolic and could be polymerised by one-electron oxidation.

- by Monica Ek
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- Industrial Crops, Ceramic Membrane, Ultra Filtration, Low molecular weight

In this work, the effect of Trametes pubescens laccase (TpL) used in combination with a low-molecularweight ultra-filtered lignin (UFL) to improve mechanical properties of kraft liner pulp and chemi-thermo-mechanical pulp was studied. UFL was isolated by ultra-filtration from the kraft cooking black liquor obtained from softwood pulping. This by-product from the pulp industry contains an oligomeric lignin with almost twice the amount of free phenolic moieties than residual kraft pulp lignin. The reactivity of TpL on UFL and kraft pulp was studied by nuclear magnetic resonance spectroscopy and size exclusion chromatography. Laccase was shown to polymerise UFL and residual kraft pulp lignin in the fibres, seen by the increase in their average molecular weight and in the case of UFL as a decrease in the amount of phenolic hydroxyls. The laccase initiated cross-linking of lignin, mediated by UFL, which gives rise to more than a twofold increase in wet strength of kraft liner pulp handsheets without loosing other critical mechanical properties. Hence, this could be an interesting path to decrease mechano-sorptive creep that has been reported to lessen in extent as wet strength is given to papers. The laccase/2,2′azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) mediator system showed a greater increase in wet tensile strength of the resulting pulp sheets than the laccase/UFL system. However, other mechanical properties such as dry tensile strength, compression strength and Scott Bond internal strength were negatively affected by the laccase/ABTS system.

- by Luca Zoia
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- Filtration, Multidisciplinary, Cellulose, Negative Affect

Naturally occurring modulators of carcinogenesis, including dietary compounds, can either stimulate or inhibit cancer development. Mechanisms responsible for these effects are unknown. Garlics used in this study were freshly prepared, and their effectiveness in augmenting natural killer (NK) activity was evaluated. Administration of 20 mg/kg produced an optimum augmentation of NK activity. A glycoprotein with MW of about 14 kDa was isolated from garlic extract and its activity was assessed. It could induce NK augmentation against K562 tumor cell line. In vivo studies also confirmed that Fraction Residue 10 (R10) of garlic extract partially purified by ultra filtration and further purified by chromatography could induce a resistance to the growth of spontaneous mammary carcinoma in Balb/c mice. NK cytotoxic activities were evaluated by flowcytometry. D

- by Roya Yaraee
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- Flow Cytometry, Breast Cancer, Immunopharmacology, Natural Killer cells

Background. Prostacyclin is an easy-to-use and safe antihaemostatic drug for continuous renal replacement therapies (RRTs). No study has been performed so far about its use in critically ill patients with acute renal failure (ARF) treated with sustained low-efficiency dialysis (SLED), a hybrid modality between conventional intermittent and continuous RRTs. Methods. We studied 35 consecutive ICU patients with ARF, in whom

- by Enrico Fiaccadori
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- Acute kidney injury, Treatment Outcome, Acute renal failure, Follow-up studies

This study compares the rheological properties of acid-induced gels prepared of industrial spray-dried egg white proteins (EWP) with the acid-induced gels prepared of ovalbumin (OA) and whey protein isolate (WPI). Also we aimed to form transparent gels of EWP by means of the cold-gelation process. We showed that it was not possible to prepare cold-set gels because ovotransferrin (OT), present in EWP, was found to interfere with fibril formation. Therefore, we developed a new purification method in which first OT was selectively denatured by a heating step, subsequently precipitated by acidification and removed by centrifugation. Finally, the supernatant was desalted by ultra filtration. This resulted in a preheated EWP preparation, which mainly contains OA (O80%). By removing OT using this new preheat procedure transparent gels were obtained after acid-induced gelation. Fracture properties of various EWP preparations were determined and compared with those of acid-induced gels of OA and WPI. Gels formed from different EWP preparations were weak (fracture stress 1-15 kPa, fracture strain 0.3-0.7), and the networks consisted of thin strands with hardly any additional disulphide bonds formed during the gelation step. In conclusion, the microstructure of the aggregates formed in the first step of the cold-gelation process and the amount of additional disulphide bonds formed during the second step appeared to be the determining factors contributing to the hardness and deformability of acid-induced gels of egg white proteins. q

- by Fred van de Velde
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- Protein Purification, Rheological properties, Microstructures, Food Sciences

Dissolved organic matter (DOM) influences many aspects of drinking water treatment, including the formation of harmful disinfection by-products (DBPs) when disinfectants are applied. DOM was isolated and fractionated using membrane ultra-filtration (UF) and reverse osmosis (RO) to eight individual fractions based on molecular weight cut-offs from a conventional surface water treatment plant (WTP) in Guangzhou of PR China. Molecular weights of these eight fractions were further calibrated using high performance size exclusion chromatography (HPSEC) and they ranged from 0.36 to 182.6 kDa. Fractions with molecular weight <0.80 kDa obtained by YC-05 UF membrane and RO were the major ones in all four stages of the water treatment processes; both ZM-500 and YM-100 membranes showed the highest removal efficiency when coupling with conventional coagulation and sedimentation processes. The elemental analysis showed that YC-05 fraction had greater polarity and aromaticity than any of the others. Furthermore, disinfection characteristics and trihalomethane formation potential (THMFP) were determined for all DOM fractions obtained in this study. YC-05 fraction was the major precursor for trihalomethane (THMs) formation among the samples tested and could be removed effectively by particulate activated carbon (PAC) adsorption. RO fraction could not be removed by PAC adsorption and, as a result, consumed more chlorine in the disinfection process. The results suggested that advanced drinking water treatment should focus on the removal of low molecular weight DOM in the source water.

- by Ji-Dong Gu
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- Engineering, Water Purification, Water Treatment, China

Schwertmannite (ideal formula: Fe 8 O 8 (OH) 6 SO 4) is typically found as a secondary iron mineral in pyrite oxidizing environments. In this study, geochemical constraints upon its formation are established and its role in the geochemical cycling of iron between reducing and oxidizing conditions are discussed. The composition of surface waters was analyzed and sediments characterized by X-ray diffraction, FTIR spectroscopy and determination of the Fe:S ratio in the oxalate extractable fraction from 18 acidic mining lakes. The lakes are exposed to a permanent supply of pyritegenous ferrous iron from adjacent ground water. In 3 of the lakes the suspended matter was fractionated using ultra filtration and analyzed with respect to their mineral composition. In addition, stability experiments with synthetic schwertmannite were performed. The examined lake surface waters were O 2-saturated and have sulfate concentrations (10.3 Ϯ 5.5 mM) and pH values (3.0 Ϯ 0.6) that are characteristic for the stability window of schwertmannite. Geochemical modeling implied that i) the waters were saturated with respect to schwertmannite, which controlled the activity of Fe 3ϩ and sulfate, and ii) a redox equilibrium exists between Fe 2ϩ and schwertmannite. In the uppermost sediment layers (1 to 5 cm depth), schwertmannite was detectable in 16 lakes-in 5 of them by all three methods. FTIR spectroscopy also proved its occurrence in the colloidal fraction (1-10 kDa) in all of the 3 investigated lake surface waters. The stability of synthetic schwertmannite was examined as a function of pH (2-7) by a 1-yr experiment. The transformation rate into goethite increased with increasing pH. Our study suggests that schwertmannite is the first mineral formed after oxidation and hydrolysis of a slightly acidic (pH 5-6), Fe(II)-SO 4 solution, a process that directly affects the pH of the receiving water. Its occurrence is transient and restricted to environments, such as acidic mining lakes, where the coordination chemistry of Fe 3ϩ is controlled by the competition between sulfate and hydroxy ions (i.e. mildly acidic).

- by Stefan Peiffer
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- Geology, Geochemistry, Chemistry, FTIR spectroscopy

The increasing use of alternative crops has meant the introduction of new technologies to process their products. In this work, an alternative method is presented for the extraction of natural indigo from woad (Isatis tinctoria) based on a technique used to extract indigo from Indigofera spp. This method does not rely on the old fermentation procedure used throughout Northern Europe and is cheap, clean and efficient. Evolved from laboratory-based tests, it involves steeping the leaves at low pH in warm water and extracting the indigo at a higher pH, followed by ultra-filtration of the product, which is then left to air-dry. Problems encountered during the development of the technique and how they were overcome are discussed. 1998 Silsoe Research Institute

- by Kerry Gilbert
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- Agricultural Engineering, Biomedical Engineering, New Technology, Ultra Filtration

A hydrophiLic Surface Modifying Macromolecule (LSMM) was synthesized, characterized, and blended into the casting solution of polyethersulfone (PES) membranes. Ultra-filtration membranes were prepared by the phase inversion technique. The membranes were then characterized by contact angle measurements and a solute transport study using poly(ethylene glycol) (PEG) and poly(ethylene oxide) (PEO) solutes of different molecular weights. Pore size and pore size distribution of the membranes were determined by using PEG and PEO separation data. The Ottawa River water was treated by the membranes. The LSMM blended PES membranes showed higher fouling resistance and long-term stability than the PES membrane without LSMM.

- by Roberto Narbaitz
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- Engineering, Membrane Science, River water, Pore Size

Hydroxyl-terminated polybutadiene (HTPB) was blended into a poly(ether sulfone) (PES) casting solution used to prepare ultra-filtration (UF) membranes via the phase inversion technique. The membranes were then characterized by contact angle (CA) measurements and UF experiments. The CA was increased with the addition of HTPB in the PES membrane and also by lowering the gelation bath temperature. It was observed that the CA was lower for membranes prepared with N-methyl-2-pyrrolidinone (NMP) as the solvent than those using N,N-dimethylacetamide (DMAc) as solvent. The flux values were higher for membranes made using a 4°C gelation bath when compared with the ambient temperature ((25 Ϯ 1)°C) irrespective of the cast solvents, NMP or DMAc. The flux values were much higher and the solute separations were lower for the HTPB-based PES membranes than for the pure PES membrane, when the membranes were cast with DMAc as a solvent. On the other hand, both flux and separation values were much lower for the HTPB-based PES membranes than for the pure PES membrane, when the membranes were cast using NMP. Atomic force microscopy and scanning electron microscopy were used for morphological characterization and the correlation of topography/photography with the performance data was also examined.

- by Roberto Narbaitz
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- Engineering, Manufacturing, Scanning Electron Microscopy, Morphology

Methods. An automatic system (ABPS, automatic blood pressure stabilization) for BP control by fluid removal feedback regulation is implemented on a dialysis machine (Dialog Advanced, Braun). A fuzzy logic (FL) control runs in the system,... more

- by FULVIO FIORINI
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- Fuzzy Logic, Fuzzy Logic Control, Fuzzy Control, Prospective studies

The natural course of longitudinal changes in peritoneal permeability and membrane area has been studied mostly by performing single-dwell studies in selected patients during treatment with peritoneal dialysis. To evaluate the permeability characteristics of the peritoneal membrane by measuring drained ultrafiltration volume relative to initial glucose concentration in dialysis fluid from the start to the end of continuous ambulatory peritoneal dialysis (CAPD) treatment in a selected cohort of patients with and without peritonitis. A retrospective analysis of a group of patients whose peritoneal function was prospectively followed by recording drained ultrafiltration volume and glucose concentration in dialysis fluid for each dwell time, every day, during the time in CAPD treatment. Mean values from a 1-month period starting after the first 3 weeks of CAPD treatment were compared with the mean values from the last month of treatment. Approximately 11 500 exchanges were analyzed. Eva...

- by Knut Aasarød
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- Water, Ultrafiltration, Glucose, Permeability

Cheddar cheese mixed starter cultures containing exopolysaccharide (EPS)-producing strains of Lactococcus lactis subsp. cremoris (Lac. cremoris) were characterized and used for the production of reduced-fat Cheddar cheese (15% fat). The effects of ropy and capsular strains and their combination on cheese production and physical characteristics as well as composition of the resultant whey samples were investigated and compared with the impact of adding 0.2% (w/v) of lecithin, as a thickening agent, to cheese milk. Control cheese was made using EPS-non-producing Lac. cremoris. Cheeses made with capsular or ropy strains or their combination retained 3.6-4.8% more moisture and resulted in 0.29-1.19 kg/100 kg higher yield than control cheese. Lecithin also increased the moisture retention and cheese yield by 1.4% and 0.37%, respectively, over the control cheese. Lecithin addition also substantially increased viscosity, total solid content and concentrating time by ultra-filtration (UF) of the whey produced. Compared with lecithin addition, the application of EPS-producing strains increased the viscosity of the resultant whey slightly, while decreasing whey total solids, and prolonging the time required to concentrate whey samples by UF. The amount of EPS expelled in whey ranged from 31 to 53 mg L À1 . Retention of EPS-producing strains in cheese curd was remarkably higher than that of non-producing strains. These results indicate the capacity of EPS-producing Lac. cremoris for enhanced moisture retention in reduced-fat Cheddar cheese; these strains would be a promising alternative to commercial stabilizers. r

- by G. LaPointe
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- Production, Bacteria, Dairy, Clinical Sciences

Engyodontium album isolated from marine sediment produced protease, which was active at pH 11. Process parameters influencing the production of alkaline protease by marine E. album was optimized. Particle size of <425 μm, 60% initial moisture content and incubation at 25 °C for 120 h were optimal for protease production under solid state fermentation (SSF) using wheat bran. The organism has two optimal pH (5 and 10) for maximal enzyme production. Sucrose as carbon source, ammonium hydrogen carbonate as additional inorganic nitrogen source and amino acid leucine enhanced enzyme production during SSF. The protease was purified and partially characterized. A 16-fold purified enzyme was obtained after ammonium sulphate precipitation and ion-exchange chromatography. Molecular weight of the purified enzyme protein was recorded approximately 38 kDa by SDS-PAGE. The enzyme showed maximum activity at pH 11 and 60 °C. Activity at high temperature and high alkaline pH suggests suitability of the enzyme for its application in detergent industry.

- by Chandrasekaran Muthusamy
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- Engineering, Microbiology, Physical Chemistry, Chromatography

On-site size fractionation of about 40 major and trace elements (TE) was performed on waters from boreal small rivers and their estuaries in the Karelia region of North-West Russia around the "Vetreny Belt" mountain range and in Paanajärvi National Park (Northern Karelia). Samples were filtered in the field using a progressively decreasing pore size (5 lm, 2.5 (3) lm, 0.22 (0.45) lm, 100 kDa, 10 and 1 kDa) by means of frontal filtration and ultrafiltration (UF) techniques and employing in-situ dialysis with 10 and 1 kDa membranes followed by ICP-MS analysis. For most samples, dialysis yields a systematically higher (factor of 2-3) proportion of colloidal forms compared to UF. Nevertheless, dialysis is able to provide a fast and artefact-free in-situ separation of colloidal and dissolved components.

- by Jérôme Viers
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- Geology, Geochemistry, Silica, Pore Size

- by Daniela Correa-Llantén
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- Engineering, Microbiology, Physical Chemistry, Chromatography