Application Of Ultrafiltration Research Articles

Postoperative Prophylactic Peritoneal Dialysis in Neonates and Infants After Complex Congenital Cardiac Surgery

Peritoneal dialysis after complex congenital cardiac surgery was introduced to a group of neonates and infants (n = 756; age, 0 to 1 year) between May 1993 and December 2005. Indications of peritoneal dialysis were determined as well as methods, prolonged dialysis, and its outcomes. Demographic characteristics, preoperative risk factors, intraoperative variables, and postoperative complications were compared in 756 cases with ages below 1 year. All cases underwent ultrafiltration during the perioperative stage. One hundred eighty-six cases (24.6% of total) required peritoneal dialysis. The cardiac pathology was transposition of great arteries in 133 cases, tetralogy of Fallot in 37, aorticopulmonary window associated with interrupted aortic arch in 4 and total anomalous pulmonary venous return in 5, and other complex pathology in 7 cases. Prolonged peritoneal dialysis was usually required in infants with low weight, with episodes of pulmonary hypertensive crisis (p < 0.05), and with preoperative renal dysfunction. No major complication was observed related to the peritoneal dialysis catheter. Of 186 patients, 23 (12.3%) had acute renal failure, and 4 of them died (2.15% of all patients underwent operation, 17.3% of those with acute renal failure). It has been demonstrated that the combination of peritoneal dialysis with perioperative ultrafiltration application was effective in providing the required postoperative negative fluid balance in especially complex congenital heart cases and affected survival positively.

Fentanyl Plasma Levels After Modified Ultrafiltration in Infant Heart Surgery

Modified ultrafiltration (MUF) is a novel application of ultrafiltration to remove excess water after cardiopulmonary bypass in pediatric patients that was first reported in 1991. It has gained widespread use as an important adjunct to fluid management in neonates, infants, and pediatric cardiac surgery patients. Now more than two decades after its original description, the exact mechanism of action and effects of this therapy are still a matter of discussion. The aim of this study was to determine the effects of MUF on plasma fentanyl levels using a two-phase in vitro and in vivo study. We designed an in vitro experimental model to simulate MUF that allowed measurement of plasma fentanyl levels while eliminating biologic variables. Plasma fentanyl levels were measured during five consecutive operations on neonates and infants undergoing repair of congenital heart defects. Increases in plasma fentanyl levels were found in vitro as well as in vivo. Fentanyl plasma levels more than doubled after MUF (increased by a factor of 2.22, from 12.4 to 27.5 ng/ml in vivo). The increase in plasma fentanyl levels needs to be taken into account when delivering anesthetic care and when analyzing the effect of MUF on outcome variables.

Ultrafiltration Versus Usual Care for Hospitalized Patients With Heart Failure: The Relief for Acutely Fluid-Overloaded Patients With Decompensated Congestive Heart Failure (RAPID-CHF) Trial

The purpose of this research was to assess the safety and efficacy of ultrafiltration (UF) in patients admitted with decompensated congestive heart failure (CHF). Ultrafiltration for CHF is usually reserved for patients with renal failure or those unresponsive to pharmacologic management. We performed a randomized trial of UF versus usual medical care using a simple UF device that does not require special monitoring or central intravenous access. Patients admitted for CHF with evidence of volume overload were randomized to a single, 8 h UF session in addition to usual care or usual care alone. The primary end point was weight loss 24 h after the time of enrollment. Forty patients were enrolled (20 UF, 20 usual care). Ultrafiltration was successful in 18 of the 20 patients in the UF group. Fluid removal after 24 h was 4,650 ml and 2,838 ml in the UF and usual care groups, respectively (p = 0.001). Weight loss after 24 h, the primary end point, was 2.5 kg and 1.86 kg in the UF and usual care groups, respectively (p = 0.240). Patients tolerated UF well. The early application of UF for patients with CHF was feasible, well-tolerated, and resulted in significant weight loss and fluid removal. A larger trial is underway to determine the relative efficacy of UF versus standard care in acute decompensated heart failure.

Peptides analysis in blood plasma using on-line system of supported liquid membrane and high-performance liquid chromatography

The potential of using supported liquid membrane (SLM) technique, combined with reversed-phase high-performance liquid chromatography (RP-HPLC) has been investigated for the determination of peptides in human blood plasma. The peptides studied were DLLeu DLPhe, MetLeuPhe, GlyLeuTyr and ValGluProIleProTyr. The carrier (Aliquat 336) was incorporated in membrane phase in order to facilitate the transport of investigated peptides. After extraction, the analyte-enriched acceptor phase was directly injected into an HPLC system for analysis. With SLM, high selectivity and efficiency were achieved for extraction of peptides in aqueous solutions. Lower extraction efficiency was obtained in plasma sample. The limiting factors were the presence of salts and proteins in blood plasma. The necessary of ultrafiltration application before the SLM was required in order to improve its stability. The minimum quantifiable concentration was 90–130 ng/ml of the investigated peptides based on 0.5 ml plasma. The standard curve was linear over the concentration range of 0.05–10 μg/ml.

Application of a combined UF/RO system for the reuse of filter backwash water from treated swimming pool water

Results from the full-scale application of a combined ultrafiltration (UF) and reverse osmosis (RO) treatment process for the reuse of spent filter backwash water (SFBW) from treated swimming pool water are presented. Ultrafiltration treatment showed a significant reduction of particulate matter. Turbidity decreased from values between 5 and 25 FNU in the feed (SFBW) to values below 0.02 FNU. At the plant investigated in this study, filtration periods up to 90 min were achieved. With this configuration, efficiencies of more than 97% for the UF plant were obtained. In order to avoid an increasing concentration of salts and dissolved compounds, up to one-third of the UF filtrate was directed to the RO plant. As a result, no deterioration of the swimming pool water quality was observed, and especially the concentration of disinfection by-products did not increase. A cost comparison showed annual savings depending on the expected useful life of the membranes. If the expected useful life of the membranes exceeded 7 years, annual savings of more than 4,300 would be possible. With regard to threshold values for the direct discharge of the concentrate, the concentration of suspended solids, adsorbable organic halides as well as the chemical oxygen demand are of special interest.

Application of cross-flow ultrafiltration on inorganic membranes in purification of food materials

This paper brings data on ultrafiltration on inorganic membranes (MEMBRALOX, France, mean pore size 20 and 100&amp;nbsp;nm, 0.8 m long, filtration area 0.2 m&lt;sup&gt;2&lt;/sup&gt;), which were used for the purification of different liquid materials from the food industry; in particular egg blend, amaranth starch suspension, and caramel (i.e. natural colorant). The ultrafiltration was carried out on a pilot plant filtration unit TIA (Bollene, France), cross-flow permeate fluxes being measured at first. Using the experimental data, mathematical models describing membrane fouling were suggested. The obtained permeate steady-state fluxes (40 l/h/m&lt;sup&gt;2&lt;/sup&gt; for amaranth starch solution, 20 l/h/m&lt;sup&gt;2&lt;/sup&gt; for egg blend and 5&amp;ndash;30&amp;nbsp;l/h/m&lt;sup&gt;2&lt;/sup&gt; for caramel) depended partially on the filtration temperature (15&amp;ndash;17&amp;deg;C for egg blend, 40&amp;deg;C for amaranth, and 50&amp;ndash;70&amp;deg;C for caramel) but mostly on the character of the medium filtered. &amp;nbsp;

A study of ultrafiltration membrane fouling by humic acids and flux recovery by backwashing: Experiments and modeling

One of the critical issues for the successful application of ultrafiltration in water treatment is membrane fouling due to dissolved organic matter, which negatively affects productivity, product quality, and process costs. The aim of the present study is to contribute to the understanding of fouling phenomena by organic matter and the efficiency of the backwashing technique, which is applied in practice to restore membrane flux. Fouling experiments are carried out, in a single fiber apparatus, using humic acid solutions as model substances representative of naturally occurring organic matter; they are aimed at identifying the significance of distinct fouling mechanisms and their degree of reversibility. A new model is presented which takes into account the simultaneous action of all fouling mechanisms and describes the experimental results successfully. An important parameter considered in the study is the concentration of calcium ions, which promote humic acid aggregation and influence the rate of flux decline, the reversibility of fouling and rejection. A relatively rapid irreversible fouling takes place due to internal pore adsorption, which persists for a long time. In parallel, with time, pore blocking becomes important and a fouling cake develops on the membranes. The effects of the latter are partly reversed by backwashing, but their combined influence persists over a long time giving rise to a prolonged flux decline.

Application of Blood Purification to Non-Renal Organ Failure

The application of artificial organs to the task of blood purification in the setting of non-renal organ failure simultaneously presents important challenges and opportunities. Failures of cardiovascular, hepatic, coagulation and immune systems are all characterized by dysregulation leading to multi-organ failure. When sustained, these conditions result in multiple organ system dysfunction and death and are far too common in modern intensive care units (ICUs). While the pathogenesis of each of these organ failures is complex and variable, brought about by a variety of underlying conditions, the potential to improve patient outcomes by simultaneously targeting multiple pathways can perhaps best be realized by blood purification. Unlike drug strategies, which are usually limited to one component of these complex networks, blood purification is, by its very nature, broad spectrum and self regulating. For example, as the concentration of mediators or toxins increases, so does removal. Furthermore, given the many failed trials of specific therapy, the recent focus of immunomodulatory therapy in sepsis has shifted to non-specific methods of influencing the entire inflammatory response without suppressing it. In this issue of the journal, members of the Acute Dialysis Quality Initiative (ADQI) present systematic reviews on the application of hemofiltration, ultrafiltration, plasma therapies and liver-assist therapy for the treatment of non-renal organ failure. The focus of these reviews is on clinical evidence as well as recommendations for future research.

Application of ultrafiltration integrated with coagulation for improved NOM removal

Alum coagulation followed by ultrafiltration was studied in order to improve water quality for surface water treatment. The influence of pH (from 5 to 10) and coagulant dose (25, 40 and 50 g alum/m 3 equal to 1.795, 2.872 and 3.59 g Al/m 3) on the investigated process performance was analyzed. Two ultrafiltration membranes (cut-off 30 kD) made of regenerated cellulose and polyethersulphone were used. The experiments showed that even the lowest dose of alum significantly increased the quality of permeate. The maximum NOM separation was observed at pH 6 and a further increase of solution reaction resulted in a worsening of the permeate quality.

Simulation of structural and permeation properties of multi-layer ceramic membranes

In the present work we describe and use a reconstruction technique for the pore structure characterization of ceramic membranes, aiming to give a deeper view on the relation between structural and permeation properties of these materials. For this purpose, we have considered multi-layer asymmetric α-Al 2O 3 membranes that are commercially used in micro- and ultrafiltration applications. Subsequently, we employ stochastic techniques to generate three-dimensional reconstructions, for each membrane layer, that share the basic structural properties of the original materials determined directly from SEM studies. The viscous flow permeability of each layer is estimated by solving numerically the momentum equation in the void space of the reconstructed media. In addition, the Knudsen permeability is predicted through a Monte Carlo random walk simulation technique. The very good agreement between predicted and experimentally measured permeability values, without the need to resort to any fitting parameter, renders the proposed reconstruction methodology quite promising for reliable characterization and representation of the pore structure of this type of membrane.

Investigation of ultra- and nanofiltration for utilization of whey protein and lactose

Ultrafiltration is one of the most fascinating technologies, which has been introduced for application in the dairy industry. Ultrafiltration makes it possible to improve the quality of traditional dairy products, to create new food staffs, to utilize dairy by-products (such as whey) to a much greater extent for human nutrition and to prepare milk ingredients to be used in the entire food industry. In this study the application of ultrafiltration for milk and whey protein concentration, and research on nanofiltration for lactose concentration of the ultrafiltration permeate are detailed. The performance of ultra- and nanofiltration membranes can be characterized in terms of permeate flux, membrane retention and yield, which parameters are determined by pressure, recycle flow rate and temperature. The influence of these parameters on milk- and whey protein and lactose concentration was measured. The experiments were carried out using laboratory scale ultra- and nanofiltration units. The permeate flux, protein and lactose content in the permeate and in the concentrate fractions were measured during the experimental runs. Comparing the separation behavior of the membranes it was found that the investigated membranes are suitable for concentration of the milk- and whey proteins and lactose with high flux and retention. The filtration characteristics were obviously influenced by the process parameters. A new combination of membrane based cheese production procedure is proposed, which makes possible a significant increase in the cheese yield by incorporating the whey proteins.

Synthesis, characterization and thermal studies on cellulose acetate membranes with additive

Cellulose acetate (CA) membranes are used in ultrafiltration applications, although they show low chemical, mechanical and thermal resistance. In order to prepare membranes with improved properties, modification of cellulose acetate with polyethelene glycol (PEG 600) has been attempted. In this study, CA has been mixed with PEG 600 as an additive in a polar solvent. The effects of CA composition and additive concentration given by a mixture design of experiments on membrane compaction, pure water flux, water content and membrane hydraulic resistance have been studied and discussed. The efficiency of protein separation by the developed CA membranes have been quantified using model proteins such as pepsin, egg albumin (EA) and bovine serum albumin (BSA). The thermal stability of the developed membranes prepared with PEG 600 additive has also been investigated using thermogravimetric analysis and differential scanning calorimetry.

Application of ultrafiltration to improve the extraction of antibiotics

The production of antibiotics typically consists of fermentation, removal of biomass, solvent extraction, and crystallization. Vacuum rotary filtration or other conventional filtration systems and microfiltration are used to remove the biomass, but the biomass removal step fails to remove macromolecules including polysaccharides and proteins which may act as emulsifiers causing emulsion in the subsequent solvent extraction process, and reducing the process efficiency and product quality. In this work, an attempt was made to remove these “emulsifiers” before solvent extraction using ultrafiltration (UF). Bench and pilot scale spiral wound membrane modules with the MWCO of 5, 20 and 50 kDa were tested to treat benzylpenicillin (Pen G) broth following microbe removal. The UF permeates were subsequently fed to solvent extraction (acidic extraction at pH 2.0). The experimental results showed that UF could significantly improve the extraction operation in terms of phase separation, elimination of the need for any de-emulsifier or wet agent, and increase extraction recovery and product quality. Similar improvements from UF were observed in the extractions of erythromycin and medmycin (alkaline extraction at pH 10.0 and 8.7, respectively). The experimental results show that UF is an alternative to the use of de-emulsifier or other wet agent to obtain good phase separation even by gravity without centrifugal extractor in solvent extractions of Pen G, erythromycin and medmycin. The mechanisms of the improvement of extraction were discussed based on the experimental results on characterizing the feed and permeate solutions of UF. And it was concluded that there existed bioemulsifiers in antibiotic fermentation broth and UF could successfully remove them and hence could improve the extraction operation.

Mineral membrane filtration in refinement of starch hydrolysates

The paper is focused on application of cross-flow ultrafiltration on ceramic membranes for refinement of starch hydrolysates. The use of membrane separation processes as a possibility for improvement of conventional filtration technologies is discussed as well. Samples of commercial hydrolysates from wheat starch obtained by acid and enzymatic hydrolysis were filtered on two different filtration units (T.I.A., Bollene, France and MUF, Mikropur, Czech Republic) equipped with various inorganic membranes (Membralox, TAMI). The mean pore size of used membranes was 20–100 nm. Properties of feed and permeate (i.e. viscosity, content of proteins, colour substances and sugar profile) were evaluated in dependence on membrane used. The results proved that ultrafiltration can fulfil some requirements especially for acid starch hydrolysate refinement, due to the removing of macromolecular substances, namely proteins and colour compounds, while the sugar composition and concentration is not affected. Achieved permeate fluxes (12–86 dm 3 h −1 m −2) depend on the quality of syrup, i.e. on the technology, and on the tangential velocities which are different for both filtration units.

Product Recovery and Reduction of Wastewater Disposal Costs in a Detergent Production Facility

In an applied research project in cooperation with industrial partners investigations have been made on the application of ultrafiltration and nanofiltration membrane processes for the separation of surfactants from cleaning‐in‐place rinsing waters in a liquid detergent production plant. A membrane screening as well as pilot plant experiments have been performed. Chemical oxygen demand reductions in the wastewater of up to 96 % have been achieved resulting in less environmental impact and lower wastewater disposal costs.

Application of ultrafiltration and stable isotopic amendments to field studies of mercury partitioning to filterable carbon in lake water and overland runoff

Results from pilot studies on colloidal phase transport of newly deposited mercury in lake water and overland runoff demonstrate that the combination of ultrafiltration, and stable isotope amendment techniques is a viable tool for the study of mercury partitioning to filterable carbon. Ultrafiltration mass balance calculations were generally excellent, averaging 97.3, 96.1 and 99.8% for dissolved organic carbon (DOC), total mercury (Hg T), and methylmercury (MeHg), respectively. Sub nanogram per liter quantities of isotope were measurable, and the observed phase distribution from replicate ultrafiltration separations on lake water agreed within 20%. We believe the data presented here are the first published colloidal phase mercury data on lake water and overland runoff from uncontaminated sites. Initial results from pilot-scale lake amendment experiments indicate that the choice of matrix used to dissolve the isotope did not affect the initial phase distribution of the added mercury in the lake. In addition there was anecdotal evidence that native MeHg was either recently produced in the system, or at a minimum, that this ‘old’ MeHg partitions to the same subset of DOC that binds the amended mercury. Initial results from pilot-scale overland runoff experiments indicate that less than 20% of newly deposited mercury was transported in the filterable fraction (<0.7 μm). There is some indication of colloidal phase enrichment of mercury in runoff compared to the phase distribution of organic carbon, but the mechanism of this enrichment is unclear. The phase distribution of newly deposited mercury can differ from that of organic carbon and native mercury, suggesting that the quality of the carbon (available ligands), not the quantity of carbon, regulates partitioning. Further characterization of DOC is needed to clarify the underlying mechanisms.

Polymeric Ultrafiltration Membranes and Surfactants

Surfactants have been extensively used in ultrafiltration processes such as membrane cleaning,removal of surfactants or other organic toxic compounds and metal ions from solutions and estimation of interactions at surfactant and membrane interface. The aim of this review is to present the possibilities that arise from the data reported in the literature on the field of ultrafiltration (UF) membranes and surfactants. This data is classified into five groups and a brief description of each article is given. Pretreatment of membranes with surfactant solutions can lead to performance increase of UF process. By Micellar‐Enhanced Ultrafiltration the separation of low molecular weight toxic substances and heavy metals is possible, extending the applications of conventional UF (e.g. separation of proteins). Through estimation of the type of interactions on membrane surface with surfactants the prediction of retention and removal of small size substances, the prevention of fouling, the modification of surfactant‐membrane system, the design of new surfactant‐membrane system could be achieved. Finally economical aspects of UF‐surfactant processes are given.

Micellar Enhanced Ultrafiltration to Remove Traces of Petroleum Oil from Oil Field Brine: Use of Pluronic Triblock Copolymer Micelles

The ultrafiltration characteristics of surfactant (Triton X‐100)‐oil field brine with a cellulosic membrane were analyzed. Triton X‐100 permeate concentration was found to be invariant with ultrafiltration time and remained below or close to the surfactant critical micelle concentration (cmc), suggesting a permeate free of micelles. With an increase of the surfactant feed concentration, the permeate surfactant composition also remained unchanged (∼1.7 × 10−4 M) at a surfactant feed concentration of 5× cmc and 10× cmc and was slightly above the cmc (2.4 × 10−4 M) at a feed concentration 50 times the cmc. This indicates that micelles are completely rejected, which is desirable in micellar enhanced ultrafiltration (MEUF) applications. The removal of traces of petroleum oil from oil field brine by MEUF was examined. Excellent oil rejection (∼99.5%) were achieved in the seldom‐explored surfactant concentration regime around the cmc. Unexpected oil rejection (99.6%) was observed at surfactant concentrations moderately below the cmc (0.7× cmc). This was attributed to concentration polarization that results in a build‐up of surfactant molecules at the solution–membrane interface where micelles are present. These high oil rejections were achieved with an extremely low surfactant feed concentration (∼0.34 mg/L), making the MEUF process economically and environmentally viable.

Preparation of alumina membranes for micro- and ultrafiltration applications

A very thin disc type ceramic rnembrane (0(.)3-0(.)8 nun thickness, 25-30 mm diameter) made of pure alumina and suitable for microfiltration applications has been prepared by a tape casting process. A sol coating was applied to the disc to form an ultrafiltration membrane. The pore size of the membrane could be varied in the range 0(.)1-0(.)7 mum and porosity in the range 25-55% by optimising the experimental parameters. The most important factor for determining the pore size of the membrane was found to be the initial particle size distribution of the ceramic powder. Firing temperature and soaking time are other crucial parameters affecting volumetric porosity. Water permeability through the membrane under suction and under positive pressure is comparable with that of ceramic membranes prepared by conventional methods. In addition, a typical membrane shows a very narrow pore size distribution in the range 0(.)1-0(.)4 mum, with a median pore size of 0(.)28 mum. A very sharp drop in the pore size distribution pattern around 0(.)4 mum indicates that no pores larger than this exist. This implies that all particles with radius > 0(.)4 mum are trapped in the membrane, providing excellent separation efficiency. Results of microbial separation tests confirmed the possibility of micro-organism separation through these membranes. (C) 2002 IoM Communications Ltd. Published by Maney for the Institute of Materials, Minerals and Mining.

Membrane processes used for potable water quality improvement

The tap water is often used as water source for different industries, however, the water repurification is required to meet the specification of technology. The effect of application of ultrafiltration (UF), nanofiltration (NF), reverse osmosis (RO) and membrane distillation (MD) processes on the quality of treated water was investigated. The removal of suspended solids and colloids obtained by UF process allowed the reduction of SDI 15 from 8 to 2. The NF process permitted to achieve the complete removal of dissolved organic carbon and the rejection of hardness between 60% and 87%. The rejection of TDS obtained in the RO system was at a level of 99.7%. The highest quality water (0.8 μS/cm, 0.6 ppm TDS) was produced in the MD installation.