| 1. |
- Jonsson, C, et al.
(författare)
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The influence of degreasing agents used at car washes on the performance of ultrafiltration membranes
- 1995
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Ingår i: Desalination. - : Elsevier BV. - 1873-4464 .- 0011-9164. ; 100:1-3, s. 115-123
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Tidskriftsartikel (refereegranskat)abstract
- The influence of washing chemicals used at car washes on the flux and retention of three ultrafiltration (UF) membranes has been studied. Eleven commercial degreasing agents, two shampoo agents and a wax were included in the investigation. The membrane performance when treating waste water collected at a car wash at different times of the year was also studied. The retention of the different chemicals varied greatly, but there was no significant difference in COD retention among the three UF membranes. The highest flux was observed when treating the alkaline degreasing agents and the shampoo solutions. The flux and COD retention when treating the waste water from the car wash were 30-50 l/m(2) h and 60%, respectively. One of the low-retention degreasing agents was treated by nanofiltration (NF). The retention was significantly higher when using NF, but the COD concentration in the permeate was still too high to allow the permeate to be discharged without further treatment.
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| 2. |
- Jönsson, Ann-Sofi, et al.
(författare)
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Membrane distillation - A theoretical study of evaporation through microporous membranes
- 1985
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Ingår i: Desalination. - : Elsevier BV. - 1873-4464 .- 0011-9164. ; 56, s. 237-249
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Tidskriftsartikel (refereegranskat)abstract
- Membrane distillation is a process in which, for example, water in a heated salt solution, evaporates through a porous membrane. The vapour condenses on a coolant surface on the other side of the membrane. The two liquid streams, the salt solution and the condensate, are separated by a highly porous hydrophobic membrane. Surface tension forces withhold liquids from the pores and prevent contact between the two liquids. The temperature difference, causing a corresponding vapour pressure difference across the membrane, provides the driving force of the membrane distillation process. Evaporation will occur at the solution surface if the vapour pressure on the solution side is greater than the vapour pressure at the condensate surface. Vapours then diffuse through the pores to the cooler surface, where they condense. The dependence of mass and heat transport upon different process and membrane parameters involved in membrane distillation has been investigated theoretically.
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| 3. |
- Jönsson, Ann-Sofi, et al.
(författare)
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The application of membrane technology in the pulp and paper industry
- 1985
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Ingår i: Desalination. - : Elsevier BV. - 1873-4464 .- 0011-9164. ; 53:1-3, s. 181-196
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Tidskriftsartikel (refereegranskat)abstract
- A state of the art review on industrial applications of membrane technology in the pulp and paper industry is presented. Applications have been arranged under three headlines, effluent treatment, concentration and fractionation. Among new and promising applications are treatment of waste paper white water, effluent after deresination and concentration of spent liquor from chemi-mechanical pulping.
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| 4. |
- Jönsson, Ann-Sofi, et al.
(författare)
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Treatment of paper coating colour effluents by membrane filtration
- 1996
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Ingår i: Desalination. - : Elsevier BV. - 1873-4464 .- 0011-9164. ; 105:3, s. 263-276
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Tidskriftsartikel (refereegranskat)abstract
- Dilute coating colour effluents are created during the coating of paper and board. After treating the colour effluents with ultrafiltration, the retentate can be reused as coating colour and the permeate can replace fresh water. At the same time, the load on the external treatment plant is reduced. In this investigation, pilot-plant experiments were performed at a paper mill. A high and steady flux, 120 l/m(2) h, was achieved at a colour concentration of 10-15%. The flux at 40% was lower but steady, 50 l/m(2) h. The membrane performance when treating five coating colours with varying composition was studied in laboratory experiments. The composition of the colour had a significant influence on the membrane performance. A colour containing starch exhibited the lowest flux and the lowest COD retention of the colours included in the study, while a colour in which the clay had been replaced by CaCO3 exhibited the highest final concentration of 60%.
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| 5. |
- Jönsson, Ann-Sofi, et al.
(författare)
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Ultrafiltration applications
- 1990
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Ingår i: Desalination. - : Elsevier BV. - 1873-4464 .- 0011-9164. ; 77:1-3, s. 135-179
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Forskningsöversikt (refereegranskat)
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| 6. |
- Linde, K, et al.
(författare)
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Nanofiltration of salt solutions and landfill leachate
- 1995
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Ingår i: Desalination. - : Elsevier BV. - 1873-4464 .- 0011-9164. ; 103:3, s. 223-232
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Tidskriftsartikel (refereegranskat)abstract
- Nanofiltration (NF) has attracted increasing attention during recent years due to the development of new applications. The advantage of NF compared with reverse osmosis (RO) and ultrafiltration (UF) is that it is possible to separate organic substances from some types of salts. It is, furthermore, also possible to separate different kinds of salts due to the negatively charged groups on the membrane. The retention of sulphate salts by the membranes used in this investigation was 88-96%, while the retention of chloride salts was only 12-47% at low salt concentrations. This difference in retention is due to the charge density of the anion. The retention of NaCl was found to be strongly related to the concentration. The retention decreased from 45% to 7% when the concentration was increased from 0.05 M to 1 M. Although the repulsion of the anion mainly determines the retention of salt solutions, it was observed that the cation can affect the retention, especially in salt solutions with a high concentration of monovalent anions. It was found that the retention of divalent cations was three times higher than that of monovalent cations in this type of salt solution. In chloride solutions with mixed cations, it was shown that a monovalent cation passed through the membrane preferentially to the divalent cations, to such an extent that the retention became negative. NF was utilized to treat a landfill leachate with an extremely high salt content from a waste cell containing mainly ash because of the good separation of cations. Most of the heavy metals, which are multivalent cations, are rejected while the monovalent cations, which are rather harmless substances, pass through the membrane. The retention of, for example, cadmium, zinc, lead and chromium was found to be higher than 70%, while the retention of potassium and sodium was less than 10%. Since the transmembrane osmotic pressure was low, due to the low retention of the monovalent ions, the flux was several times higher than for RO membranes. The flux of the leachate, with a conductivity of 6800 mS/m, was above 50 l/m(2)h at 3 MPa and 25 degrees C.
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| 7. |
- Sivik, B, et al.
(författare)
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A Rehological Screening Method for Membrane Modifying Polymers
- 1990
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Ingår i: Desalination. - : Elsevier BV. - 1873-4464 .- 0011-9164. ; 77, s. 181-194
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Tidskriftsartikel (refereegranskat)abstract
- A rheological method for screening water soluble polymers intended for fouling prevention of membranes is investigated.Viscosity is measured of mixtures between polymers (neutral Dextran T500 positively charged DEAE-dextran and negatively charged dextran sulphate) and proteins (BSA, ovalbumin, pepsin and lysozyme).The method is sensitive enough to detect interactions between the polymers and the proteins also at low concentrations.Different types of interactions are discussed and one application with modified membranes is described (BSA and above mentioned polymers).
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| 8. |
- Zhang, W, et al.
(författare)
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Membrane characterization by the contact angle technique: II. Characterization of UF-membranes and comparison between the captive bubble and sessile drop as methods to obtain water contact angles
- 1989
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Ingår i: Desalination. - : Elsevier BV. - 0011-9164. ; 72:3, s. 263-273
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Tidskriftsartikel (refereegranskat)abstract
- Several commercial UF-membranes are characterized by water contact angles. Two different methods of contact angle measurements, the sessile drop and the captive bubble methods, are compared. Differences in results between the two methods occur for the DDS GR 61 membrane; otherwise the methods give rather consistent results. The advancing and the receding contact angles are measured for the UF-membranes. All membranes show considerable contact angle hysteresis. The cellulose acetate and the polyacrylonitrile membranes show less hysteresis than the polysulfone and the polyolefine membranes. The order of hydrophobicity according to advancing contact angle is polyolefine > polysulfone > cellulose acetate > polyacrylonitrile. The contact angle data are compared with Hansen's solubility data. Some correlation between θr and δtotal can be seen. θa correlates to the hydrogen and the polar part of the solubility parameter.
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| 9. |
- Platt, Samantha, et al.
(författare)
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Retention of pegs in cross-flow ultrafiltration through membranes
- 2002
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Ingår i: Desalination. - 0011-9164 .- 1873-4464. ; 149:1-3, s. 417-422
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Tidskriftsartikel (refereegranskat)abstract
- This work investigated the difference between membrane cut-offs measured with the CHARMME methods and the values quoted from the manufacturers. Four different membranes were characterised. The two regenerated cellulose membranes that according to the manufacturers had cut-offs of 5 and 10 kD had, in fact, the same cut-off of 2.5 kD. It was also found that the polyethersulfone membrane had a lower cut-off (3 kD) than that stated by the membrane manufacturers (5 kD). A cross-flow velocity of 2 m/s and a flux of 40 1/h/m2 was found to keep the mass transfer coefficient within a tolerable range for all PEGs used.
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| 10. |
- Westin, K. J., et al.
(författare)
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Precipitation of calcium carbonate in the presence of citrate and EDTA
- 2003
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Ingår i: Desalination. - 0011-9164 .- 1873-4464. ; 159:2, s. 107-118
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Tidskriftsartikel (refereegranskat)abstract
- The influence of process conditions such as feed rate, calcium/carbonate ratio, pH, complexing agents [ethylenediaminetetraacetic acid (EDTA), citrate (CIT)] and their concentration on the average particle size and shape of precipitated calcium carbonate was studied. The precipitation was performed in a semi-batch operated agitated vessel at constant pH by adding sodium hydrogen carbonate to a solution containing calcium chloride. In the absence of a complexing agent, agglomerates of needle-shaped crystals, probably aragonite, are obtained. Increasing feed time and the calcium/carbonate ratio increases the average particle size, whereas the opposite effect is observed for increasing pH. The observations can be related to the level of supersaturation. In the presence of complexing agents and at a concentration ratio of calcium vs. a complexing agent of 6, differently shaped and smaller particles were obtained. Furthermore, the effect of the other parameters on particle size becomes much weaker in the presence of complexing agents. In the presence of EDTA mostly spherical particles were obtained, and in the presence of citrate mainly rhombic particles corresponding to calcite were obtained. The effect on particle shape and size is attributed to interactions of the complexing agents with the faces of the crystalline calcium carbonate.
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