Hollow Fiber Filter Research Articles

Characterization of colloidal and particulate matter transported by the magela creek system, Northern Australia

AbstractThe composition and amount of colloidal and suspended participate matter transported during a small flood event in Magela Creek in tropical northern Australia was investigated. The flood studied constituted approximately 3 % of the total annual flow, most (90%) of which occurred between mid‐January and mid‐February of the study year. Three fractions were separated from water samples using a sequential method involving a continuous flow centrifuge to separate suspended particulate matter (SPM; nominally > 1 μm) followed by hollow fibre filtration, first using a 0.1 μm filter to separate course colloidal matter (CCM; nominal size 1–0.1 μm) and then a 0–015 μm filter to separate fine colloidal matter (FCM; nominal size 0.1–0.015 μm). The SPM was predominantly inorganic (organic matter 21 %), whereas the colloidal fractions were dominantly organic matter (CCM 60%; FCM 83%). Analysis of individual particles using electron microprobe and automated image analysis indicated that the mineral fractions in both the SPM and CCM were dominated by iron‐enriched aluminosilicates (including kaolinite) (72–82%) and quartz (9–10%), indicative of a highly weathered and extensively laterized catchment. Surprisingly there was very little difference in the composition of the SPM or CCM fractions during the flood event studied, which may indicate either that sediment availability was restricted following the major run‐off events in January and February, or that all the sediment sources within the catchment are geochemically similar.Approximately the same amounts of particulate (20 tonne), colloidal (21 tonne) and dissolved material (17 tonne) were transported during the 25 hour period of the main flood peak; over 90% of the colloidal matter was 0.1–1.0 μm in size. These data suggest that previous estimates of the amounts of particulate (and colloidal) matter transported by Magela Creek, which were based on suspended solids measurements, may have underestimated the particulate matter load by as much as 50%. It is possible that the relatively high proportion of colloidal matter is unique to Magela Creek because coagulation and aggregation of colloidal matter to particulate matter is slow due to the very low concentations of calcium and magnesium in these waters. However, if the result is more widespread, there are important implications for the global estimates of fluvially transported particulate and dissolved materials as many of the previous studies may have underestimated the particulate load and overestimated the dissolved load.

特集 精密ろ過膜 諸工業における精密ろ過法の利用の現状 水処理

The continuous microfiltration in the paper is a 0.2 micrometer hollow fiber filter that automatically backwashes with air at either preset time interval or pressure drop.The CMF is operated in direct flow mode or cross blow mode at a low pressure producing a high flux. Surface river water, secondary sewage water and another process water can be treated in higher quality by the CMF, compared with concentional water treatment process.

Long-term experience with extracorporeal low-density lipoprotein cholesterol removal by dextran sulfate cellulose adsorption.

Patients with familial hypercholesterolemia have a high incidence of coronary heart disease due to diet- and drug-resistant, elevated low-density lipoprotein cholesterol (LDL-C). Five patients with familial hypercholesterolemia and diet- and drug-resistant LDL-C greater than 230 mg/dl were treated by LDL apheresis using dextran sulfate cellulose adsorption (Liposorber System LA-15, Kaneka). Plasma separation was by 0.5-m2 polysulfone hollow fiber filter. Two columns containing 150 ml of dextran sulfate cellulose alternately adsorbed LDL and were regenerated by 4.1% saline. The five patients received a total of 360 treatments at 7-day intervals. The treated plasma volume per session was 4.1 +/- 0.4 l. Postapheresis values compared with preapheresis were: total cholesterol, 40%; LDL-C, 28%; VLDL-C, 65%; HDL-C, 95%; triglycerides, 70%; white blood cells, 116%; platelets, 87%; C3 complement, 79%; fibrinogen, 64%; albumin, 94%. The decrease in HDL-C per treatment was not significant. The safety parameters showed only slight changes. The initial LDL of 436 +/- 172 mg/dl decreased to mean pre-apheresis levels of between 150 and 100 mg/dl. The anti-atherogenic HDL increased in three and remained unchanged in two patients. Adverse events like hypotension, angina pectoris, and technical problems occurred in 11 of the 360 treatments. Long-term treatment of patients with diet- and drug-resistant familial hypercholesterolemia by extracorporeal dextran sulfate cellulose adsorption is effective and safe.

Application of an automated plasma filtration device and a blood monitoring system for LDL apheresis.

This study describes the adaptation of a filtration separation device (AK 10 from Gambro, München, FRG) and a blood monitor system (BTS 100 from Diamed, Köln, FRG) to the automated adsorption/desorption device for LDL apheresis. Plasma separation by filtration was performed by a hollow-fiber filter (OP5, Asahi Corp., Japan). In order to evaluate the quality of the plasma obtained by filtration, the platelet contamination, the activity of factors V and VIII and the concentration of the immunoglobulins IgG and IgM were determined. The following results were found: Platelet contamination of the plasma was 2,740/microliters. As compared to the patient's pretreatment values, activity of factor V was 94%, activity of factor VIII was 104%, concentration of IgG was 96%, concentration of IgM was 94%. Ten LDL aphereses were evaluated: red cell counts, platelet counts, hemoglobin concentration and hematocrit were not changed significantly. Thus, this new combination system represents an improved alternative to previously performed centrifugation methods.

Microparticle Removability of the Regenerated Cellulose Hollow Fiber (BMM): An Electron Microscopic Evaluation

In this study we ewamined the structure and microparticle removability of 2 types of regenerated cellulose hollow fiber filters (BMMR and its modified type, BMMU) by electron microscopy using colloidal gold solutions and viruses (HIV and JEV). The following results were obtained: 1) The meshwork structure of the BMMU wall was more suitable for filtration of microparticles than that of the BMMR

Dynamic Filtration of Blood: A New Concept for Enhancing Plasma Filtration

We have shown previously that blood flow pulsations created by intermittent squeezing of the inlet blood line significantly increased the plasma filtration rate in membrane plasmapheresis. However, in order to avoid hemolysis, the filtration increase had to be limited to about 50%. We have now devised a more efficient pulsation generator. By properly matching the tubing compliance and the pulsation amplitude, it is possible to extract 50 ml/min of plasma from 90 ml/min of blood at 36% hematocrit with a 1000 cm2 polypropylene hollow fiber filter without hemolysis. Simultaneous recording of the time course of plasma filtration rate measured by an electromagnetic flow meter and transmembrane showed that the increase in mean plasma flow rate was due to a dynamic filtration process which prevents the establishment of concentration polarization. The transmembrane pressure (Ptm) increases over a 0.5-second interval when the tube is squeezed. The membrane responds with an increase in filtration since the concentration polarization layer takes a few seconds to build up. The Ptm then drops when the tube is released before the polarization layer has time to build up appreciably and a sudden acceleration of the blood flow (velocity spike) helps clean the membrane, reducing the polarization. Tests with bovine show that the system is very efficient in reducing membrane plugging with small area filters.

Plasma profiles and removal rates of inorganic sulphate, and their influence on serum ionized calcium, in patients on maintenance haemodialysis

1. Regular dialysis treatment is reported to remove inorganic sulphate, but not to restore its level to normal. To evaluate the adequacy of modern dialysis techniques in maintaining the sulphate balance, intra- and interdialysis plasma profiles and removal rates of sulphate were studied in 20 stable patients on maintenance haemodialysis. The influence of sulphate levels on the distribution of calcium-complex species was also investigated. 2. Sulphate was determined by ion-exchange chromatography of both serum ultrafiltrates, taken at the start of, during, at the end of, and at 24 h and 48 h after a dialysis session, and whole diffusate collections. Dialyser clearances of sulphate were assessed by two independent procedures and compared with those of urea and creatinine, on two different methods of dialysis, i.e. traditional haemodialysis with Cuprophan hollow fibre filters, and haemodiafiltration with high-flux Polysulphone or polyacrylonitrile dialysers. Concentrations of the main serum ions were determined before and after dialysis and used to solve a multiple mass balance equation system by which concentrations of the calcium-complex species were calculated. 3. Before dialysis, sulphate levels were eight times those determined in 17 control subjects and remained higher than normal at the end of dialysis. These changes were independent of the dialysis procedure. There was a close correlation between serum levels of sulphate and creatinine. Dialyser clearances of sulphate were comparable with those of creatinine, but lower than those of urea. Clearances of all solutes were higher on haemodiafiltration.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma fractionation by dead-end membrane filtration: Effects of membrane properties and plasma flux1

Plasma fractionation by membrane filtration permits the reinfusion of the patient with his own albumin. In this study, the influence of membrane nature and plasma flux on plasma fractionation in dead-end mode is investigated with acetate hollow fiber filters. It is found that transmembrane pressure TMP rises exponentially with time, the rate of increase being proportional to plasma flux. The faster TMP rises, the faster the drop in sieving coefficient SC. It is also found that albumin SC is a function of TMP and not of plasma flux. Theoretical analysis of the dead-end filtration was performed. This theoretical model indicates that the observed variation of TMP with time is consistent with the assumptions that pore volume decreases proportionally to the filtrate plasma volume.

A low-cost automated device incorporating a hollow fiber filtration cartridge for large-scale production of ghosts from human erythrocytes

Readily available elements were used to build an automatic apparatus dedicated to the preparation of erythrocyte ghosts. The apparatus id designed around a low-cost re-usable hollow-fiber filtration cartridge (marketed for therapeutic plasmapheresis). The apparatus is controlled by a simple programmer (based on a diode matric and low cost timers and liquid level sensors): once the apparatus is loaded with whole red blood cells, washing of cells, as well as hemolysis and washing of ghosts, is performed by the machine in about 4,5 h without any operator inetrvention. Automatic filter cleaning takes a further 110 min.

Effects of complete cell recycling on product formation byLactobacillus casei ssp.rhamnosus in continuous cultures

The lactic acid bacteriumLactobacillus casei ssprhamnosus was cultivated in a system with complete cell recycling in order to obtain information on how this cultivation technique affected the microorganisms. Cultivations at two different glucose concentrations (25 g/L and 50 g/L) were performed. Hollow fiber filters were used for separating the cells from the spent broth. The cell recycling was carried out for 128–135 h. Samples were taken three to four times daily for analysis ofd- andl-lactate, glucose concentration, and cell mass. Protein patterns were studied with two-dimensional electrophoresis. A change in the protein pattern was observed. Dry weight of cell mass of 86 g/L was obtained when cultivated on 50 g glucose/L, which was approximately 15 times more than in the batch culture. The percentage ofd-lactate of the total lactate increased with time; when cultivated on 25 g glucose/L, it increased from 3% to 13%. No racemase was detected by the methods used. The data collected from these two recycling experiments show that this is an efficient way to obtain high cell densities, but that the method can affect the product formation pattern of the microorganism.

Hemodynamic changes in the peripheral circulation after repeat low density lipoprotein apheresis in familial hypercholesterolemia.

Repeat low density lipoprotein (LDL) apheresis and blood flow determinations in the forearm and leg were performed in 10 patients (age range, 13-49 years; four male, six female) with familial hypercholesterolemia (eight homozygous, two heterozygous). To perform LDL apheresis, plasma was first separated by a polysulphone hollow fiber filter; then, LDL was selectively removed from plasma by dextran sulphate cellulose beads packed in columns. Blood flows in the forearm and leg were determined at rest and during a reactive hyperemia test (peak flow). This test was performed noninvasively by a strain-gauge plethysmograph with semicontinuous registration of arterial blood flow variables before the first apheresis and 3 weeks after the last of six procedures for apheresis. Resting arterial blood flows in the forearm and leg were slightly increased after repeat LDL apheresis (p less than 0.05). Peak blood flow in the leg significantly increased (+34%, p less than 0.01). No change in peak blood flow in the forearm was observed. Systolic blood pressures were slightly but significantly reduced (p less than 0.05); forearm peripheral resistances were also reduced (p less than 0.05). Flow response was not related to LDL receptor status. Blood and plasma viscosities were determined before and 7 days after the last apheresis. Blood viscosity was significantly reduced after LDL apheresis at shear rates of 11.25-450 sec-1. Plasma viscosity did not change.

Recovery of β-galactosidase from a poly (ethylene glycol) solution by diafiltration

Cross-flow diafiltration was used for the recovery of β-galactosidase from a poly (ethylene glycol) (PEG) 4000 top phase, which was obtained during extraction of Escherichia coli cell disintegrate in a PEG 4000/potassium phosphate aqueous two-phase system. Two different filtration systems were used, an Amicon system containing a hollow fiber filter (nominal cut off 100,000, membrane area 2.65 · 10 −2 m 2) and a Millipore system containing a plate and frame filter (nominal cutoff 100,000, membrane area 0.5 m 2). To enhance filtration, the top phases were diluted 2.5×, 5×, and 10× with water prior to the filtration. By reducing the concentration of top phase before the filtration, the retention of β-galactosidase and PEG 4000 decreased and the flux increased in both systems. While the retention of β-galactosidase was high in both systems, the retention of PEG 4000 was much lower in the Amicon system. However, the system capacities, expressed as the volume of nondiluted top phase treated per membrane area and time, were not influenced by the extent of dilution of the top phase prior to the filtration. The system capacities were approximately 3.0 and 1.5 l m −2 h −1 for the Millipore and Amicon systems, respectively. The recoveries of β-galactosidase in the retentates were ≥ 95%.

A novel approach to anticoagulation control.

Heparin used in extracorporeal therapy often leads to bleeding complications. Protamine used for heparin reversal can cause adverse hemodynamic responses. To control both types of complications, a cellulosic hollow-fiber filter device containing immobilized protamine (defined as a protamine filter) was developed. In vivo experiments with dogs showed that the filter not only removed more than 80% of the anticoagulant activity of heparin, but also caused no clinically significant hemodynamic response. In addition, the protamine filter also significantly attenuated both the thrombocytopenic and granulocytopenic responses associated with the use of protamine. Moreover, the use of immobilized protamine considerably reduced activation of the blood complement system by free protamine.

Acetic acid production using a fermentor equipped with a hollow fiber filter module

The continuous production of acetic acid by Acetobacter aceti M23 was carried out using a fermentor equipped with a hollow fiber filter module. The culture continued for 830 h with various dilution rates, which were changed stepwisely from low to high. The final cell concentration was 21.9 g dry cell/L and the maximum productivity of acetic acid was 12.7 g/L.h for the exit acetic acid concentration of about 50 g/L. The productivity was higher than any literature's values surveyed so far. The cell concentration was 62.8 times and the productivity was 4.6 times as high as those of the fermentor without the filter module. The productivity increased with the increase of dilution rate up to 0.3 h(-1). It is interesting to note that the viable cell concentration was kept almost constant about 1.1 x 10(9) cells/ml in spite of the increase of dilution rate. Use of oxygen-rich air was indispensable to establish the high productivity of acetic acid.

Modelling of Plasma-Separation through Microporous Membranes

Available mathematical models of ultrafiltration have been used to predict changes in maximum plasma filtration rate with wall shear rate for given filters and blood properties. We have done many plasmapheresis experiments in vitro, using hollow-fiber filters (500-1000 cm2) and fresh bovine blood collected on ACD or heparin. The comparison between predicted and experimentally obtained filtration rates was good for models based on the concentration polarization theory and lift velocity theory. In other experiments with pulsatile inlet flow we found that plasma filtration rate increased by 20 to 50% compared to non-pulsatile conditions. These results are in good agreement with the modified model of ultrafiltration incorporating pulsating flow. This paper presents relationships between plasma filtration velocity (steady and pulsating flow) and hemolysis limit as a function of wall shear rate and filter size.

Enhancement of acetic acid production in a high cell-density culture of Acetobacter aceti

The rate of production of acetic acid was greatly enhanced by a high cell-density culture of Acetobacter aceti. Acetobacter aceti cells were recycled through a hollow fiber filter module, and the high acetic acid production rate of 120 mg/ l/h (at an exit acetic acid concentration of 40 g/ l) at the dilution rate of 4.0 h −1 was obtained. High viable cell concentrations were maintained by using medium rich in yeast extract and controlling the DO concentration at an optimum level. Viable cell concentrations increased with increasing added amounts of yeast extract in the medium as long as the acetic acid concentration was not higher than 40 g/ l. When DO and yeast extract were not depleted from the culture, the correlation between the acetic acid production rate ( PD) and the dilution rate ( D) was given as, PD = 7.1 + 34.5 D (0.3 ≤ D ≤ 3)

Treatment of hypercholesterolemia by chemical adsorption of lipoproteins

Dextran sulfate (Mr 5,000) was covalently linked to porous cellulose beads, and the dissociation constant (Kd) and the maximum binding level (S) of the beads were calculated for the human plasma lipoproteins VLDL, LDL, and HDL. The S values for VLDL and LDL were 2 and 7 g cholesterol/liter of the wet beads and that for HDL was almost negligible, although the apparent Kd were all in the same order. In fact, LDL and VLDL were exclusively adsorbed by the beads from human plasma in vitro. Bound LDL was desorbed with 0.35 M NaCl. The beads were packed in a column (25-ml) and used with polysulfone hollow fibers in experimental LDL-apheresis for WHHL rabbits; LDL cholesterol was reduced from 500 to 200 mg/dl, while HDL, total plasma protein, and major blood cell counts did not change. For LDL apheresis of familial hypercholesterolemia, the sorbent column, 400-ml, was used with the polysulfone hollow fiber filter. The maximum removal of LDL + VLDL cholesterol was 6 to 8 g with a single column resulting in its reduction by 250 to 300 mg/dl after 3.5 liters plasma treatment. Adsorption was negligible with albumin, HDL, IgA, G, M, apoA-I, A-II, C-II, enzymes, and electrolytes. Activated complement fragments, C3a and C5a, were completely adsorbed. By periodic removal of LDL, an increase of HDL cholesterol was observed in some cases. In order to increase LDL removal in a single treatment and to reduce the extracorporeal circulation volume, two small columns (150 ml each) were used alternatively.(ABSTRACT TRUNCATED AT 250 WORDS)

High-flux haemodialysis with 1.5 m2 modified cuprammonium rayon membrane: technical and clinical evaluation.

The feasibility and reliability of a short dialysis technique performed with standard dialysis equipment and a modified cuprammonium rayon hollow-fibre filter has been studied. The hydraulic response of the filter and membrane to high blood flows and transmembrane pressures were tested in vitro and the maximal clearances of different solutes achievable during high-flux bicarbonate dialysis were studied in vivo. Clinical studies were undertaken to evaluate the long-term effects of the short, highly efficient dialysis therapy. Six patients were treated for more than a year with single-pass bicarbonate dialysis with a blood flow of 500 ml/min, dialysate flow of 700 ml/min, and average duration of 150 min/session three times weekly. The treatment showed an adequate efficiency with an average KT/V greater than 1. All patients obtained an average blood urea nitrogen during the study of less than 80 mg/dl and an average protein catabolic rate of 0.9 g/kg per 24 h. The treatment was well tolerated by all patients and, on echocardiography, no significant changes in myocardial function were detected after one year of therapy. The treatment is efficient, well tolerated, simple to monitor and does not require the use of synthetic membranes or machines with advanced technology. Thus the reduction of dialysis treatment time is feasible in all centres at a relatively low cost.

Starting a plasmapheresis program with hollow-fiber filtration.

In a routine donor center, a program of hollow-fiber filtration can be instituted. With the Organon Teknika PLASMAPUR system the collection of 600 ml plasma was completed within 50 min in 76% of the procedures. Changing the tubing set took 12-15 min. From the plasma a frozen cryoprecipitate is made with a recovery of 59%. After pooling, lyophilization and heat treatment, the recovery is 42%.

Starting a Plasmapheresis Program with Hollow-Fiber Filtration

In a routine donor center, a program of hollow-fiber filtration can be instituted. With the Organon Teknika PLASMAPUR system the collection of 600 ml plasma was completed within 50 min in 76% of the procedures. Changing the tubing set took 12-15 min. From the plasma a frozen cryoprecipitate is made with a recovery of 59%. After pooling, lyophilization and heat treatment, the recovery is 42%.