EP0433387A1 - Filtration apparatus and method - Google Patents
Filtration apparatus and methodInfo
- Publication number
- EP0433387A1 EP0433387A1 EP19890910890 EP89910890A EP0433387A1 EP 0433387 A1 EP0433387 A1 EP 0433387A1 EP 19890910890 EP19890910890 EP 19890910890 EP 89910890 A EP89910890 A EP 89910890A EP 0433387 A1 EP0433387 A1 EP 0433387A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- filter
- particles
- fibre
- deep
- deep filter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000001914 filtration Methods 0.000 title claims abstract description 25
- 238000000034 method Methods 0.000 title claims abstract description 24
- 239000002245 particle Substances 0.000 claims abstract description 71
- 239000012530 fluid Substances 0.000 claims abstract description 29
- 230000005684 electric field Effects 0.000 claims abstract description 25
- 239000000835 fiber Substances 0.000 claims description 73
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 14
- 239000000463 material Substances 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 11
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 9
- 238000011118 depth filtration Methods 0.000 claims description 8
- 238000005342 ion exchange Methods 0.000 claims description 7
- 125000000129 anionic group Chemical group 0.000 claims description 5
- 239000011148 porous material Substances 0.000 claims description 5
- 125000002091 cationic group Chemical group 0.000 claims description 4
- 230000000063 preceeding effect Effects 0.000 claims 1
- 239000010416 ion conductor Substances 0.000 abstract 1
- 239000002609 medium Substances 0.000 description 21
- 238000005259 measurement Methods 0.000 description 11
- 230000000694 effects Effects 0.000 description 8
- 230000009471 action Effects 0.000 description 6
- 238000004062 sedimentation Methods 0.000 description 6
- 239000000725 suspension Substances 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 239000004793 Polystyrene Substances 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 238000000151 deposition Methods 0.000 description 5
- 230000008021 deposition Effects 0.000 description 5
- 239000000084 colloidal system Substances 0.000 description 4
- 239000000706 filtrate Substances 0.000 description 4
- 230000037230 mobility Effects 0.000 description 4
- 238000012856 packing Methods 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 3
- 239000000443 aerosol Substances 0.000 description 3
- 238000013459 approach Methods 0.000 description 3
- 239000007853 buffer solution Substances 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 230000005484 gravity Effects 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 239000004816 latex Substances 0.000 description 3
- 229920000126 latex Polymers 0.000 description 3
- 230000035699 permeability Effects 0.000 description 3
- 229920000867 polyelectrolyte Polymers 0.000 description 3
- 229920002223 polystyrene Polymers 0.000 description 3
- 239000004094 surface-active agent Substances 0.000 description 3
- 101710150402 Mastin Proteins 0.000 description 2
- 239000004952 Polyamide Substances 0.000 description 2
- 239000012736 aqueous medium Substances 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 239000012212 insulator Substances 0.000 description 2
- 239000003456 ion exchange resin Substances 0.000 description 2
- 229920003303 ion-exchange polymer Polymers 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 229920002647 polyamide Polymers 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 1
- KRKNYBCHXYNGOX-UHFFFAOYSA-K Citrate Chemical compound [O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O KRKNYBCHXYNGOX-UHFFFAOYSA-K 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 241000463291 Elga Species 0.000 description 1
- 229920005439 Perspex® Polymers 0.000 description 1
- 239000004159 Potassium persulphate Substances 0.000 description 1
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 description 1
- 239000004141 Sodium laurylsulphate Substances 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- SWLVFNYSXGMGBS-UHFFFAOYSA-N ammonium bromide Chemical compound [NH4+].[Br-] SWLVFNYSXGMGBS-UHFFFAOYSA-N 0.000 description 1
- 239000007900 aqueous suspension Substances 0.000 description 1
- 239000000872 buffer Substances 0.000 description 1
- 239000013590 bulk material Substances 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000003651 drinking water Substances 0.000 description 1
- 235000020188 drinking water Nutrition 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000001493 electron microscopy Methods 0.000 description 1
- 238000001962 electrophoresis Methods 0.000 description 1
- 238000001652 electrophoretic deposition Methods 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000011066 ex-situ storage Methods 0.000 description 1
- 238000005194 fractionation Methods 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 239000003999 initiator Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000002574 poison Substances 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 239000004926 polymethyl methacrylate Substances 0.000 description 1
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 description 1
- 235000019394 potassium persulphate Nutrition 0.000 description 1
- 125000001453 quaternary ammonium group Chemical group 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000009738 saturating Methods 0.000 description 1
- 235000019333 sodium laurylsulphate Nutrition 0.000 description 1
- 238000007619 statistical method Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 230000036962 time dependent Effects 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
- LENZDBCJOHFCAS-UHFFFAOYSA-N tris Chemical compound OCC(N)(CO)CO LENZDBCJOHFCAS-UHFFFAOYSA-N 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D35/00—Filtering devices having features not specifically covered by groups B01D24/00 - B01D33/00, or for applications not specifically covered by groups B01D24/00 - B01D33/00; Auxiliary devices for filtration; Filter housing constructions
- B01D35/06—Filters making use of electricity or magnetism
Definitions
- This invention relates to filtration and more particularly to the enhancing of filtration by electrical action.
- the design of a filter to remove particles from a fluid must be a compromise between the obstruction the filter produces in the desired flow of the fluid and the efficiency of removal of particles from the fluid. It is known that in certain circumstances the action of a filter can be enhanced by the application of an electric field. An enhanced filter might for example offer less obstruction for a given removal of particles than the unenhanced version. Clearly the choice of parameter enhanced in any given filter, subject to design constraints, can be a matter of choice.
- the deep-bed filter in which the spaces are large compared with the size of the particles to be filtered and the filter medium is relatively loosely packed.
- the pore volume can be 20 to 30% or even more.
- a significant use of deep-bed filters is depth filtration for drinking water supplies.
- a relatively deep layer or bed of filter medium such as sand, is used to adsorb particles on the surface of the medium with minimal pressure loss in the passage of the water through the relatively open filter. While such a filter is effective in removing many of the particles small particles tend to follow the hydraulic streamlines and pass through the filter medium.
- a method of depth filtration of particle from a fluid carrying particles including providing in a deep filter a quantity of filter medium elements, at least some of the elements being ionically conductive, applying an electric field to said deep filter to cooperate with individual said elements,
- the filter medium elements may have an electrical conductivity varying from one part to another part of the element.
- the one and another part may be regions of a fibre and there may be several said parts in each fibre.
- the fibres are manufactured fibres having within them one or more conductive parts of discontinuous longitudinal regions.
- One preferred fibre is the proprietary fibre ACTILEX B701 (RTM) a polyacrylic material, as recently available from Courtaulds Ltd.
- the filter medium elements may be permitted or caused to have a specific state of charge, not the same as that of the particles to be filtered. Specifically the elements may be chemically treated, e.g. with NaOH, to have a charge opposite to that of the particles. The elements may be permitted or caused to imbibe water.
- the deep filter type is well-known in the art and is characterised by a filter medium of a bed or layer of significant depth but open structure to have a high porosity.
- the porosity may be such that in the absence of the electric field particles could move through without encountering the filter medium.
- a method of depth filtration including providing in quantity a filter medium of elements having an electrical conductivity varying from one part to another of said elements, forming a quantity of said elements into a deep filter, applying an electric field to cooperate with individual said elements in the deep filter, permitting or causing fluid with particles for filtration therefrom to flow into the deep filter, influencing the movement of particles in the deep filter by the cooperation of sai d appl i ed el ectri c fi el d and sai d i ndi vi dual el ements to enhance the filtration of said particles from the fluid.
- a deep filter including filter medium arranged in filter layer, means to apply an electric field to the layer and means to move through the layer a liquid with particles for filtration, the filter medium being ion conductive.
- the filter medium is composed of fibres loosely packed to provide a high porosity ranging to in excess of 96% and up to 96.75% pore volume.
- the ion conductivity of an individual fibre may not be uniform from part to part of the fibre. Non-uniform conductivity can be provided by the fibres not being all of one type.
- the fibres When the filter medium is of loosely packed fibres the fibres may be mainly in two of the three conventional orthogonal directions. It may then be advantageous for the means to movethe liquid to direct the liquid generally in the third of said three directions.
- the filter medium may be polyacrylic fibres chemically modified to be set with elcctropositive groups.
- FIG. 1 is a schematic diagram, partly in cross-section, of a filter structure embodying the invention
- FIGS 2 and 4 are graphs useful in understanding the behaviour of the filter.
- Figure 4 is a graph useful in comparing the behaviour of a filter embodying the invention with other filters.
- Table 1 is a table of parameter ranges for the filter
- Tables 2 and 3 are tables useful in understanding the behaviour of the filter.
- Table 4 is a table useful in comparing the behaviour of a filter embodying the invention with other filters.
- FIG. 1 shows in schematic form an experimental form of a filter embodying the invention.
- a deep-bed filter indicated generally at 1 is formed in tube
- the filter medium 20 is of fibres and is described in more detail below.
- the filter medium 20 is held in the tube 10 by two similar retainers formed of plastic meshes 11 (conveniently of NETLON, R.T.M.) attached to 0-rings 12 and supports 13.
- the tube 10 is closed by similar closures 14 at each end.
- Each closure has a liquid flow tube 15 extending through it.
- Each closure also supports a disc electrode 30 and an insulated electrical connection 31 for the electrode.
- the electrodes are of platinised titanium and the connection is of an insulated copper wire extending through the electrode.
- An adjustable source of electricity 32, with voltmeter 33 and ammeter 34, is connected to the connections 31.
- the source is of continuous, i.e. d.c, current, In this way an electrical field of desired strength can be applied in the filter.
- the tube 10 was about 35 millimetres in diameter and a filter length of about 10 to 25 and typically 15 millimetres was used.
- the fibres and filter medium will now be described in more detail.
- the fibres were supplied by Courtaulds, under the trade name
- the fibre was pre-treated by stirring a 0.4% slurry in 10 -2 M NaOH for 5 hours before use to rid it of residual hydrochloric acid from the manufacturing process, and also to convert the ion-exchanging surface to the hydroxide form.
- the fibre zeta( ⁇ )-potentia1 was calculated from streaming potential measurements of fibre plugs using apparatus similar to that of Joy et al (1965). Measurements were corrected for surface conduction by the method of Fairbrother and Mastin (1924). The axial conductivity of the fibre was measured by the alternating current impedance method on continuous filaments of the material.
- the filter medium was formed in place in the tube 10.
- the filter pad was formed on the lower retainer by sedimentation of the pre-treated fibres from a 4% slurry in the buffer solution. Fibre settlement was assisted by mechanical agitation using a modified Griffin and George mechanical shaker, which also helped remove trapped air bubbles, such that the fibres usually settled within 30 minutes. The supernatant was drained and the upper retainer placed in the cell to compress the fibre pad to the required filter length. Prior to filtration the fibre pad was equilibrated by passage of 250ml buffer solution through the cell. The electrical supply was connected and the field set at the required strength and the test material suspension flowed upwards through the cell (as shown in the drawing) at the desired flow rate from a constant head device.
- the performance of the filter was measured using a test material of an aqueous suspension of homodispersed polystyrene latex particles.
- the polystyrene latex particles were prepared by emulsion polymerisation according to the method of Kotera et al (1970).
- the initiator used was potassium persulphate and, in the case of the sub-micron particles, sodium lauryl sulphate was used as a surfactant.
- particles of mean diameter 0.432, 1.13 and 2.09 micrometres respectively were obtained. These were then purified using nuclear grade ion-exchange resins (Rohm and Haas) according to the method of Van den Hull and Vanderhoff (1972).
- Particle diameters were determined using a model "T” Coulter counter (Coulter, Luton) or, in the case of the smallest particles, electron microscopy.
- the particle electrophoretic mobilities were determined using a Rank Mk II microelectrophoresis apparatus (Rank Bros., Bottisham, Cambridge) fitted with a flat cell.
- the filtrate particle concentration was monitored nephelometrically using a Camlab Ratio Turbi dimeter (Camlab, Cambridge) fitted with a flow-through cell. The meter was pre-calibrated to give direct proportionality between the turbidity reading and the particle concentration. Filter efficiency is designated ⁇ , with suffix D,E,I,G respectively for diffusional, electrophoretic, interceptional, gravitational capture. The range of experimental parameters used in the study is given in Table 1.
- Figure 2 shows the permeability values obtained for a fibre bed compressed to five different porosities, with comparison predicted values.
- the experimental data are in good agreement with those predicted by Happel, whose model yields a flow parameter:
- U K ⁇ P/ ⁇ L (02) where U is the approach velocity of the fluid, K is the permeability, ⁇ P is the pressure drop across the filter and ⁇ is the fluid viscosity.
- the permeability is related to the packing density, according to the respective models, by:
- K Happel a F 2 ( - ln ⁇ - 1 + ⁇ 2 /(1 + ⁇ 2 ))/8 ⁇ (03)
- K Kuwabara a F 2 ( - ln ⁇ + 2 - ⁇ 2 /2 - 1.5)/8 ⁇ (04)
- ⁇ K -1/2 a F and K zero and K 1 are Bessel functions of the zero and first order respectively, a F is the fibre radius.
- the zeta( ⁇ )-potential values calculated from the particle mobility and fibre bed streaming potential data are given in Table 2. The standard deviations for mobility measurements were less than 8% for the smallest particles and less than 5% for thetwo larger particles.
- Non-electrophoretic filtration performance is considered first. Under the conditions employed (see Table 1) the ⁇ D / ⁇ I ratios were approximately 2:1, 1:1 and 1:2 for the particle radii of 0.216, 0.565 and 1.05 micrometres respectively. Equations from Natanson (1957a), Langmuir (1942) and Stechina et al (1969) respectively for diffusion (D), interception (I) and gravitation (G) were used in calculating the theoretical collector efficiency.
- the classical value for interception (Langmuir 1942) was modified to include the effects of van der Waal's attraction and hydrodynamic retardation according to the predictions of Natanson (1957b) or, where appropriate, the computations of Spielman and Fitzpatrick (1973). According to Natanson, the modified collector efficiency for capture by interception is given by
- ⁇ E mN E (07)
- ⁇ E mN E /(l+N E ) (08)
- ⁇ E mN E /(l-mN E ) (09)
- m is the electrophoretic capture coefficient
- ⁇ E ⁇ exp - ⁇ DIG ; i.e. non-electrophoretic capture is assumed to be given by the calculated theoretical collector efficiency, ignoring the effect of the double layer attractive force.
- the experimentally measured electrophoretic capture efficiency values were generally large in comparison to those obtained in the absence of an electric field, the error induced by this assumption is small.
- the fibre has a fractional pore volume of 0.05.
- Optical microscopic studies showed that the fibre has a large degree of surface roughness, and therefore only approximates to a perfect cylindrical collector.
- its conductivity, although significantly higher than that of the suspension electrolyte, is at least two orders of magnitude lower than would be expected of a homogeneous ion-exchange resin of equivalent ion-exchange capacity. This suggests that the fibre is chemically heterogeneous with an uneven distribution of quaternary ammonium functional groups throughout the fibre material. The effect of such a material on the applied field cannot be predicted.
- the above describes particle capture by a fibrous filter in the presence and absence of an external electric field.
- the field was applied parallel to the the fluid flow in both the co-flow (positive field) and counter-flow (negative field) directions.
- the fibres of the filter by way of example polyacrylic, are preferably chemically modified to be set with electropositive groups.
- ACTILEX fibres are believed to be those described in European Published Patent Application 0 194766 Al.
- ⁇ E minimises at low negative field strengths and then follows the same relationship as positive fields but with a reduced proportionality factor m.
- No extensive empirical study of particle capture by negative sedimentation has been carried out in the past, but the results for negative fields are in qualitative agreement with the observations of Fitzpatrick and Spielman (1973).
- the relation of field and flow direction may be important. Even better filtration may occur when the field is across the flow.
- the values given for factor m include the effect of ohmic resistance at the filter supports but this affects all measurements similarly. An estimate of this effect is a multiplier of 2-3 for m.
- the electrophoretic fibre efficiency was found to be independent of filter history under the conditions employed in the study and dependent to a small extent on the size and/or surface charge of the particle.
- the fibres were Courtelie (RTM) (a polyacrylic fibre of zero bulk conductivity), 12k High Modulus carbon fibre of very high electrical conductivity, and a cationic ion-exchange fibre of comparatively high ionic conductivity, Actilex A801.
- RTM Courtelie
- Well characterised negatively charged polystyrene latex particles were used throughout.
- the surface charge of the carbon fibre can therefore not be determined by this method. However, it seems probable that a fibre of substantial bulk conductivity will not undergo charge reversal on saturating with any surfactant because of its large density of charge carrying groups. This is demonstrated by the cationic Actilex A801 fibre, which remains weakly negative on saturation with the polyamide. In the case of Courtelie such charge carrying groups are probably less highly charged and more thinly distributed.
- the filtration data is summarised in Table 4, and the electrophoretic capture data shown graphically in Figure 4.
- Table 4 The electrophoretic capture data shown graphically in Figure 4.
- both the modified Courtelie fibre and the anionic ion-exchange fibre Actilex B701 approximate to a perfect sink. This may have been predicted from the streaming potential data, indicating positively charged surfaces for the respective fibres. All other fibres are negatively charged and this is reflected in their low measured capture efficiencies, both with and without an applied electric field.
- the transient response of an electrophoretic depth filter composed of the ion-exchange materials differs noticably to that of Courtelie (figure 5).
- the filtrate concentration remains almost unchanged over a period of 30 minutes for both the ion-exchangers. A gradual increase in the filtrate concentration with time occurs with Courtelie under the same conditions.
- the anionic fibre Actilex B701 from the slopes in Figure 4, clearly has a collector efficiency significantly greater than the other fibres although Courtelie and Actilex A801 when surface modified show behaviour which might be useful.
- Actilex B701 fibre makes it very suitable for use in electrophoretic depth filters. It is possible that the Actilex A801 fibre may have some usefullness for such filters.
- the enhanced performance over fibres of similar surface charge characteristics, and therefore similar field-absent filter properties, is evidenced by a doubling of the electrophoretic collector efficiency and a less time-dependent filtrate concentration. It is possible that the higher efficiency of the Actilex fibres is a consequence of either their ionic conductivity or their permittivity. Although the ionic conductivity of these fibres is by no means large, they at least will not actively obstruct the passage of ions through the filter bed, in the way that an insulator must.
- N Dl dimensionless double layer number according to Adamczyk and van der Ven, 4 ⁇ O ⁇ P ⁇ F a p /kT
Abstract
Procédé permettant de filtrer en profondeur un fluide pour le débarrasser des particules qui s'y trouvent qui consiste à disposer dans un filtre à lit profond une certaine quantité d'éléments filtrants, dont certains au moins sont des conducteurs ioniques, à placer ledit filtre à lit profond dans un champ électrique qui agit individuellement sur lesdits éléments filtrants, à laisser ou faire couler ledit fluide chargé de particules dans le filtre à lit profond, et à influencer ensuite le mouvement des particules dans le filtre à lit profond au moyen du champ électrique pour en accroître la filtration.Method for depth filtering of a fluid to rid it of particles therein which consists in placing in a deep bed filter a certain quantity of filter elements, at least some of which are ionic conductors, in placing said filter deep bed in an electric field which acts individually on said filter elements, to let or run said particle-laden fluid in the deep bed filter, and then to influence the movement of particles in the deep bed filter by means of the electric field to increase filtration.
Description
Claims
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8821271 | 1988-09-12 | ||
GB888821270A GB8821270D0 (en) | 1988-09-12 | 1988-09-12 | Filtration |
GB888821271A GB8821271D0 (en) | 1988-09-12 | 1988-09-12 | Filtration |
GB8821270 | 1988-09-12 |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0433387A1 true EP0433387A1 (en) | 1991-06-26 |
Family
ID=26294378
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19890910890 Withdrawn EP0433387A1 (en) | 1988-09-12 | 1989-09-12 | Filtration apparatus and method |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0433387A1 (en) |
JP (1) | JPH04500627A (en) |
GB (1) | GB2224958B (en) |
WO (1) | WO1990002595A1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4513069B2 (en) * | 2006-03-30 | 2010-07-28 | いすゞ自動車株式会社 | Solar-absorbing glass structure |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2573967A (en) * | 1947-05-01 | 1951-11-06 | Us Hoffman Machinery Corp | Electrical precipitation method |
US3324026A (en) * | 1964-01-10 | 1967-06-06 | Petrolite Corp | Electric filter |
US3933643A (en) * | 1971-09-10 | 1976-01-20 | The Carborundum Company | Electrically conducting filter media for fluids |
DE2315615C3 (en) * | 1973-03-29 | 1979-09-06 | Karl Dr.Rer.Nat. 4150 Krefeld Dietzel | Device for the mechanical-biological purification of waste water |
WO1982002003A1 (en) * | 1980-12-09 | 1982-06-24 | Dennis E Johnson | Electro-chemical system for liquid filtration |
US4350590A (en) * | 1981-02-25 | 1982-09-21 | Robinson Norman R | Filtration system |
US4594138A (en) * | 1984-05-17 | 1986-06-10 | Thompson Donald E | Fluid filter |
GB8506361D0 (en) * | 1985-03-12 | 1985-04-11 | Courtaulds Plc | Cationic fibre |
GB2198365A (en) * | 1986-08-04 | 1988-06-15 | Howden James & Co Ltd | Filter |
-
1989
- 1989-09-12 GB GB8920648A patent/GB2224958B/en not_active Expired - Lifetime
- 1989-09-12 WO PCT/GB1989/001071 patent/WO1990002595A1/en not_active Application Discontinuation
- 1989-09-12 EP EP19890910890 patent/EP0433387A1/en not_active Withdrawn
- 1989-09-12 JP JP51023189A patent/JPH04500627A/en active Pending
Non-Patent Citations (1)
Title |
---|
See references of WO9002595A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO1990002595A1 (en) | 1990-03-22 |
GB8920648D0 (en) | 1989-10-25 |
GB2224958B (en) | 1992-08-12 |
JPH04500627A (en) | 1992-02-06 |
GB2224958A (en) | 1990-05-23 |
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