Showing papers on "Ultrafiltration published in 1985"

Use of Micellar-Enhanced Ultrafiltration to Remove Dissolved Organics from Aqueous Streams

Abstract: Traditional ultrafiltration is ineffective at removing dissolved low molecular weight organics from water. In micellar-enhanced ultrafiltration (MEUF), surfactant is added to the water at concentrations well above the critical micelle concentration. Almost all of the organic originally dissolved (the solute) solubilizes in the micelles formed by the surfactant. The solution then passes through an ultrafiltration membrane with pores small enough to block micelle passage. The permeate contains (at most) only the unsolubilized solute and the surfactant monomer, both at very low concentrations. In this work, the criteria for selecting a surfactant are considered and MEUF is tested on an aqueous stream containing 4-tert-butyl-phenol with hexadecylpyridinium chloride as the surfactant. At high surfactant concentrations (0.25 M) in the retentate, rejections decrease, probably owing to the formation of n-mers (e.g., dimers, trimers, etc.) which are able to pass through the pores along with some solubiliz...

Process and system for producing sterile water and sterile aqueous solutions

Abstract: Water substantially free of pyrogens and microorganisms that meets the requirements of United States Pharmacopoeia Standard USP XX Water for Injection is produced by processing drinking quality water through a filtration step adapted to remove organic contaminants and impurities that degrade downstream seperation membranes, a reverse osmosis step to remove dissolved solids, pyrogens, microorganisms and chemical contamination, a deionization step to further remove dissolved solids, and an ultrafiltration step to remove pyrogens. A sterile filter to remove microorganisms increases the water quality to USP XX Sterile Water for Injection. Means are provided to periodically remove accumulated chemical contaminants, pyrogens and microorganisms from the reverse osmosis apparatus, the deionization apparatus and the ultrafiltration apparatus. The sterile water can be admixed with a sterile concentrate composition to produce a sterile dilute solution that can be packaged under sterile conditions.

Composition, Physicochemical and Functional Properties of Reference Whey Protein Concentrates

Abstract: Four reference whey protein concentrates (WPCs) were prepared from pasteurized and nonpasteurized acid casein whey and Cheddar cheese whey using ultrafiltration/diafiltration and spray drying processes. The WPCs exhibited comparable composition, protein solubility and PAGE and reverse phase HPLC properties. Major differences were observed in the viscosity and foaming properties of the reference WPCs as a function of pH. The WPCs generally produced higher foam expansion but lower viscosity and stability values than for liquid egg white protein. The findings were discussed in terms of the need for additional, fundamental knowledge of the physicochemical structure and reactivity of whey proteins to understand the reasons for their poor functional performance.

High flux membrane.

Abstract: A high flux ultrafiltration membrane comprises a porous substrate (for example, a polypropylene biofilter) having an ultrafiltration microskin permanently deposited thereon. The microskin is formed of a reticulated so-called Fractal membrane produced by dehydrating a calcium apatite gel or calcium aconitate gel by changing the pH. The membrane shows improved flux properties and high chemical resistance. It may be used inter alia to desalt molasses or skim milk.

Autotransfusion system and method

Abstract: An autotransfusion system for salvaging, washing, and concentrating blood and returning the blood to a patient during surgery. The system comprises both a filtration unit and an ultrafiltration unit. The ultrafiltration unit is configured so as to communicate with the filtration unit, and both the filtration unit and the ultrafiltration unit are provided with a suitable conduit for conveying blood back to a patient. The ultrafiltration unit is divided into two chambers by a semipermeable membrane, the membrane being selected so as to permit fluid to pass therethrough, while preventing the passage of blood cells and other formed elements. A mixture of healthy blood cells, fluid, and particulate debris is salvaged from an operative field of a patient. The blood mixture is filtered in the filtration unit and can then be immediately returned to the patient, if needed. Alternatively, the filtered mixture is conveyed to the ultrafiltration unit where a portion of the fluid is removed from the mixture and wherein the healthy blood cells may be washed by the addition of a washing solution. The washed and concentrated blood cells are then returned to the patient through a suitable return line.

A dynamic model for low‐pressure, hollow‐fiber ultrafiltration

Abstract: Developpement et essai d'une solution numerique des equations qui tiennent compte de la variation axiale de la pression hydraulique et de la pression osmotique

Ultrafiltration studies in vitro of serum aluminum in dialysis patients after deferoxamine chelation therapy.

Abstract: Using gel filtration chromatography, we evaluated aluminum bound to albumin, transferrin, and other plasma proteins in the serum of patients on maintenance hemodialysis. The proportion of dialyzable aluminum, as determined by selective membrane ultrafiltration and flameless atomic absorption spectrometry, increased by more than fourfold on treatment with the metal chelator, deferoxamine. This ultrafiltration technique may prove useful for monitoring the proportion of aluminum mobilized during such therapy.

The Performance of a Rotating Module in Oily Emulsions Ultrafiltration

Abstract: The rotating ultrafiltration module has been applied to concentrated oily emulsions with the aim of checking its practical features. The ultrafiltration yield has been measured as a function of pressure, tangential speed, temperature, oil concentration, and hydrodynamic conditions. An energy consumption evaluation has been performed and a comparison with tubular modules tried. The importance of turbulence promoters and the influence of the radial geometry of the module has been outlined by means of simulation tests with a transparent model system.

Stable allergenic extracts and methods

Abstract: A storage-stable, high potency allergenic extract is prepared by ultrafiltration, retaining fractions having molecular weights of from 1000 to 100,000, and treating the solution with gel polymer and/or carbon absorbents. The extract is dried to a moisture content of less than one weight percent water. The purified solution and aqueous reconstituted solutions of the dried extract provide a transparent, colorless solution which has greatly increased stability, remaining transparent and colorless for extended periods.

Improvements in ethanol concentration and fermentor ethanol productivity in yeast fermentations using whole soy flour in batch, and continuous recycle systems

Abstract: Ethanol concentrations and fermentor productivities were increased 20.2 and 15.5% at 90 and 95% recycle, respectively, when whole soy flour was added to the feed (2 g/l at 90% recycle, and 1 g/l at 95% recycle) of a continuous yeast fermentation system with recycle of cells and soy flour (soy flour concentrations were 2% at steady state in the fermentor) by UF membranes as compared to controls. The improvements were primarily due to increases in cell concentrations. Similar results were obtained for batch cultures.

Performance, kinetics, and substrate utilization in a continuous yeast fermentation with cell recycle by ultrafiltration membranes

Abstract: A continuous single stage yeast fermentation with cell recycle by ultrafiltration membranes was operated at various recycle ratios. Cell concentration was increased 10.6 times, and ethanol concentration and fermentor productivity both 5.3 times with 97% recycle as compared to no recycle. Both specific growth rate and specific ethanol productivity followed the exponential ethanol inhibition form (specific productivity was constant up to 37.5 g/l of ethanol before decreasing), similar to that obtained without recycle, but with greater inhibition constants most likely due to toxins retained in the system at hight recycle ratios.

Studies on coagulation of milk ultrafiltration retentates. I. Coagulation kinetics

Abstract: Parametres de la cinetique de coagulation de concentres issus de la diafiltration et de l'ultrafiltration du lait entier pasteurise : concentration en proteines, en presure, pH et technique de filtration

Rinsing Behavior of Deposited Layers Formed on Membranes in Ultrafiltration

Abstract: Skim milk and aqueous milk protein suspensions were ultrafiltered in a tubular module under controlled conditions (temperature, pressure, flow rate) and were subsequently rinsed with water also under controlled conditions. The effect of rinsing on the deposited layer was followed by observing the flux with time. Ultrafiltration and rinsing should be carried out at high flow rates and at low pressures. Increasing the pressure led to an undesirable increase in the compactness of the deposit. Theoretical considerations of the mechanism of transport in and at the deposited layer made it possible to obtain data on the thickness of the deposits, on mass transfer coefficients and velocity profiles within deposits. The experimental rinsing curves could be well explained by the calculated results. The results should help to optimize the performance and cleaning of UF modules.

The effects of dissolved organic matter on the aqueous partitioning of polynuclear aromatic hydrocarbons

Abstract: The partitioning of six polynuclear aromatic hydrocarbons into aqueous solutions containing dissolved organic matter from various coastal environments was investigated by liquid chromatography. Specific hydrocarbon-organic matter interactions were observed. The greatest interactions occurred with the very low solubility hydrocarbons and with organic matter of terrestrial origin. Ultrafiltration experiments suggested that it was the relatively high (greater than approximately 500) molecular weight organic matter that was interacting with the hydrocarbons.

Studies on coagulation of milk ultrafiltration retentates. II. Kinetics of whey syneresis

Abstract: Etablissement des equations decrivant la cinetique de la synerese du lactoserum a partir de caille de lait ultrafiltre ou diafiltre et effet des parametres de traitement du lait sur cette cinetique

Process for the production of polybenzimidazole ultrafiltration membranes

Abstract: This invention relates to the preparation of ultrafiltration polybenzimidazole membranes in a coagulation bath comprised of a solvent and a non-solvent for the polybenzimidazole.

Process for the production of cheese

Abstract: A process and apparatus for the production of cheese. Milk is initially concentrated by ultrafiltration and diafiltration to obtain the desired buffer capacity to lactose ratio in the retentate. Following concentration, an acid, an acid precursor, or a lactic acid producing starter culture is added to the retentate and the retentate is fermented to obtain a final pH of about 4.9 to 5.6 and preferably 5.1 to 5.2. After complete fermentation, a coagulant, such as rennet, is added to the fermented retentate to produce curds. The curds are subsequently treated to remove moisture and obtain the final solids content and texture. The curds can then be drained, salted and pressed. By reaching to a final pH before coagulation, better pH control is obtained over the final product.

Ultrafiltration processes for the characterization and separation of landfill leachates

Abstract: Ultrafiltration is demonstrated to be an effective method for characterizing industrial landfill leachates by molecular weight (MW) distribution. The majority of the organic matter (as TOC and COD) for the hazardous wastes examined was found to be below 500 MW. The applicability of ultrafiltration as an effective process for removal of low MW organic matter from industrial wastes is limited. Ultrafiltration, however, is useful as a pretreatment process for removal of large MW compounds that interfere with subsequent treatment processes. Ultrafiltration of raw landfill leachates is hindered by concentration polarization and severe fouling. Physiochemical lime treatment of the highly turbid raw leachate was found to aid in the stabilization of product flux.

Physicochemical Speciation of Trace Elements in River Water by Means of Ultrafiltration

Abstract: Ultrafiltration and Millipore filtration techniques have been used in the speciation of trace elements in Tama River water. The size distribution was clarified for 32 elements by means of neutron-activation analysis in order to discuss their chemical or physical forms. Alkali and alkaline-earth elements were primarily found in the dissolved-size fraction ( 0.45 μm) in the upper reaches of the river, but in the lower reaches they were chiefly fractionated as the dissolved species, with the exception of Sc and Fe. The dissolved V and Mn were distributed in the smallest-molecular-weight fraction, while the Co, Ni, and Zn were divided between two smaller-molecular-weight fract...

Steady-State Modeling of Electroultrafiltration at Constant Concentration

Abstract: A simple mathematical model was developed to predict the steady-state electroultrafiltration (a combination of ultrafiltration and electrophoresis) flux for processing bovine serum albumin (BSA) solutions at constant concentration. The assumption that the wall concentration is an exponential function of the electric field strength gave a linear dependence of flux on electric field strength. This dependence was experimentally confirmed for electroultrafiltration of 1–4 wt% BSA solutions at pH 7.4, using Amicon XM-50 membranes with a transmembrane pressure drop of 5 psig. The mathematical model uses the values of the solution and solvent fluxes for normal ultrafiltration plus the electrophoretic mobility of the solute to predict the electroultrafiltration flux. The difference between the model predictions and the measured performance was 7.5%.

Effect of antifoam agents and efficiency of cleaning procedures on the cross-flow filtration of microbial suspensions

Abstract: The influence of several biocompatible antifoam agents on the performance of ultrafiltration membranes for yeast cell concentration is described. Flux rates of water solutions and cell suspensions decreased in the presence of the antifoam agents. The anti-foam fouling effect was cumulative. Water was ineffective as a cleaning substance, while 0.1 NaOH and ethanol were used successfully for membrane washing.