Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N1/00—Sampling; Preparing specimens for investigation
  • G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
  • G01N1/40—Concentrating samples
  • G01N1/4077—Concentrating samples by other techniques involving separation of suspended solids
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/01—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with flat filtering elements
  • B01D29/05—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with flat filtering elements supported
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/50—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with multiple filtering elements, characterised by their mutual disposition
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/62—Regenerating the filter material in the filter
  • B01D29/66—Regenerating the filter material in the filter by flushing, e.g. counter-current air-bumps
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/62—Regenerating the filter material in the filter
  • B01D29/70—Regenerating the filter material in the filter by forces created by movement of the filter element
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/88—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices
  • B01D29/94—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor having feed or discharge devices for discharging the filter cake, e.g. chutes
• • 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
  • B01D35/14—Safety devices specially adapted for filtration; Devices for indicating clogging
  • B01D35/143—Filter condition indicators
• • 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
  • B01D35/14—Safety devices specially adapted for filtration; Devices for indicating clogging
  • B01D35/153—Anti-leakage or anti-return valves
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
  • B01D61/14—Ultrafiltration; Microfiltration
  • B01D61/18—Apparatus therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
  • B01D61/14—Ultrafiltration; Microfiltration
  • B01D61/20—Accessories; Auxiliary operations
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D63/00—Apparatus in general for separation processes using semi-permeable membranes
  • B01D63/08—Flat membrane modules
  • B01D63/082—Flat membrane modules comprising a stack of flat membranes

Definitions

• the present invention relates to a process for filtering fluid, liquid or gaseous samples, laden with particles to be analyzed, in particular of biological origin, such as cells or microorganisms, in particular constituted by bac ⁇ series, yeasts, filamentous fungi etc. as well as by particles of inorganic origin, asbestos in the air for example, or molecules of biological origin, such as proteins.
• biological origin such as cells or microorganisms, in particular constituted by bac ⁇ series, yeasts, filamentous fungi etc.
• particles of inorganic origin such as cells or microorganisms, in particular constituted by bac ⁇ series, yeasts, filamentous fungi etc.
• particles of inorganic origin such as cells or microorganisms, in particular constituted by bac ⁇ series, yeasts, filamentous fungi etc.
• particles of inorganic origin such as cells or microorganisms, in particular constituted by bac ⁇ series, yeasts, filamentous fungi etc.
• the invention also relates to a filtration
• beer production sometimes faces the problem of contamination by bacteria.
• the liquid contains particles which constitute yeast debris, cereals used in the manufacture, protein aggregates, colloids, etc.
• the particles sought in this case are of small size and require the use of very low porosity filters which tend to clog very quickly, thus reducing the total filterable volume.
• the aim of the present invention is to increase the filtration yield, therefore the volume of samples which can be analyzed and, consequently, the sensitivity of the detection methods which will be used.
• the subject of the present invention is a method of filtering fluid, liquid or gaseous samples, laden with particles to be detected, comprising a step of isolating these particles using a filter, the method which is characterized in what it further comprises a step of detaching the particles retained by the isolation filter with respect thereto, followed by a step of concentrating the particles thus detached from the isolation filter.
• the removal of the particles filtered by the isolation filter is obtained by washing this isolation filter using a fluid, free of all particles and under pressure, which is directed on the isolation filter in a direction opposite to the direction of filtration of the aforementioned sample.
• fluid free from all particles means a fluid which has been suitably filtered beforehand.
• the concentration of the particles detached from the isolation filter is obtained using a second filter having a filtration surface area substantially smaller than the filtration surface of the isolation filter and being separated from the latter by a suitable distance.
• the fluid for washing the isolation filter is constituted by a solution having characteristics which reduce the surface tensions between the particles retained by the isolation filter and the latter.
• the present invention also relates to a filtration device comprising a lower block and an upper block as well as a filter, this filter being intended, on the one hand, to be tightly sealed between these two, blocks and, on the other hand, when isolating particles contained in a fluid, liquid or gaseous sample, which device is characterized in that it comprises means for detaching the particles with which the isolation filter is charged relative to it ci and a means for concentrating the particles thus detached.
• the means for detaching the particles with which the isolation filter is charged consists of a washing fluid, free of all particles and under pressure, which is directed on the isolation filter in a direction opposite to the direction of filtration by the latter, and the concentration means is constituted by a second filter disposed at a certain distance from the isolation filter and having a filtration area substantially smaller by relative to the filtration area of the isolation filter.
• the concentration filter is arranged in an axial housing formed in one of the two aforementioned clamping blocks and is fixed to an appropriate support means.
• FIG. 1 is an exploded view of the filtration device according to the invention.
• FIG. 2 is a bottom view of the upper block of the filtration device illustrated in Figure 1;
• FIGS. 1 and 4 are a top view of the lower block of the filtration device illustrated in Figure 1;
• - Figure 4 is an axial sectional view of the filtration device according to the invention, the component blocks being assembled relative to one another, with however an axial spacing to show the arrangement between them of the filter d 'isolation.
• the filtration device 100 in accordance with the present invention comprises a lower transparent block 1 and a transparent upper block 2, between which is intended to be tightened, in a sealed manner, a filter ( or a filter membrane) for isolation 3.
• the lower block 1 is produced in the form of a bowl intended to receive the upper block 2, which is in the form of a substantially full cylinder, while the block 1 is a hollow cylinder.
• the tightness of the tightening of the insulation filter 3 is obtained using two flat seals 4a and 4b, which are fixed, in particular by gluing, on an annular shoulder 5 of the internal surface of the bottom 10 of the lower block. 1 and around 6 of the lower base of the clamping block 2, respectively.
• the isolation filter 3 is clamped between the two blocks 1 and 2 by means of two supports 7a and 7b (see also Figure 4), which are constituted by two grids ('each housed in the space delimited by each flat seals 4a and 4b, respectively, and made for example in PVC) and which come to bear against the abovementioned shoulders 5 and 6 of the two clamping blocks 1 and 2, when the clamping operation takes place.
• the first grid 7a is removably disposed inside the seal 4a, while the second is fixed, in particular by gluing, to the seal 4b.
• a flow grid of a type known to technicians in the field, can be placed in particular between each face of the isolation filter 3 and each of the support grids 7a and 7b, and this in order to spread a liquid sample to analyze over a larger surface of the filter and therefore increase the filtration efficiency: the two flow grids thus dis ⁇ posed are shown only in FIG. 4, where they are indicated by the reference numerals 30a and 30b.
• a nozzle 8a formed at the lower part of the clamping block 1, makes it possible to introduce the fluid sample loaded with particles which must be filtered - and therefore isolated - by the filter 3.
• Another nozzle, 8b, provided the upper part of the clamping block 2 makes it possible to evacuate the fluid sample after the first filtration tion by the aforementioned filter 3.
• a ball valve 11a (comprising a ball 12a and a spring 13a) prevents a return of the fluid sample inside the filtration device 100.
• a third nozzle 9 also equipped with an anti ball valve -return 11b (comprising a ball 12b and a spring 13b), makes it possible to inject a washing or rinsing solution under pressure directed onto the isolation filter 3 in a direction opposite to the direction of the first filtration.
• a washing or rinsing solution under pressure directed onto the isolation filter 3 in a direction opposite to the direction of the first filtration.
• it is a solution having the capacity to unhook the particles which are responsible for the isolation filter 3, so as to detach these particles from the latter together with the action of the pressure of the fluid. rinse.
• the particles that the rinsing fluid - necessarily removed from all particles - detaches from the isolation filter 3 are conveyed to the bottom 10 of the clamping block 1 (see FIG. 4).
• a recess 15 which is intended to accommodate a second filter membrane 20, also carried by a special support constituted by a ring 16, metallic (for example brass) or plastic.
• the filter 20 (which is normally flexible, like the filter 3) is supported by a grid 17 (see Figure 4).
• This filter 20 and its support 17 are lo ⁇ ges in the ring 16 and held in place by a split collar 19, making a spring, force-fitted inside the ring 16.
• This ring 16 may advantageously include a handle 21 allowing easy extraction from its housing 15.
• injection of the fluid sample to be filtered this can take place using different means.
• a peristaltic pump allowing, firstly, the injection of the sample and, secondly, by simply reversing the direction of rotation of the pump, the suction of the solution of washing.
• other means of injection can be used, in particular a simple syringe.
• the porosity of the two filters 3 and 20 can range from 0.2 .mu.m to 50 .mu.m and essentially depends on the particle diameter 'to focus as well as the filterability of the sample.
• Another potential application of the device is the separation of proteins in solution, in which case membranes having a breaking capacity varying from 2,000 to 10 ⁇ daltons are used.
• the ratio between the filtering surface of the isolation filter 3 and that of the concentration filter 20 is a very important parameter for assessing the efficiency of the method and of the filtration device according to the present invention.
• double filtration - including an isolation step followed by a concentration step
• the distance between the isolation and concentration filters is equal to 19 mm in the example shown in the figures.
• the analysis is done by conventional means known to technicians in the field, in particular by microscopy, image analysis. immunoenzymatic techniques and, advantageously, by the apparatus which is the subject of the Patent Application in the name of the Applicant N * FR-88 02 936.
• This ratio can be increased to 50 and even more, the value of the upper limit of the range of variation of this ratio being at least equal to 250.
• composition of the washing solution this may for example have the following characteristics:
• the filtration method according to the invention has the additional advantage in particular of gradually removing the particles present on the isolation filter and thus of reducing the risks of clogging of the concentration filter. Compared to a As a traditional filtration device, the Applicant's method also allows the same sample volume to pass more quickly.
• the applications of the method and of the filtration device according to the invention are numerous, in particular in the biomedical, pharmaceutical and food fields, as well as in fermentation and the detection of the degree of pollution of liquids or of the atmosphere.
• bacteria contaminating beer these are in particular the bacteria Lactojacillu-1 and Pediococcus. Brewers want to detect at least one bacteria in 100 ml of beer.
• the device which is the subject of the present invention makes it possible to filter 1000 ml of beer and to retain on an isolation filter having a porosity of 0.45 ⁇ m the bacterium (or bacteria) present in it. sample.
• a pressurized washing solution makes it possible to unhook the retained bacteria (s) from the isolation filter and to concentrate the microorganisms thus detached on the concentration filter, having a porosity of 0.2 ⁇ m for example, although it is preferable to use the same porosity for the concentration filter and the isolation filter, ie 0.45 ⁇ m.
• the presence of the bacterium (s) on the concentration filter is detected by techniques known per se, as already mentioned above.
• the Applicant has filtered, by way of nonlimiting example, 300 ml of phosphate buffer containing 500 yeasts. The yeasts present on the concentration filter were counted, which gave 475 cells. The yield during this experiment was 95%.
• Other application examples are based on the same principle and aim to detect: - Clostridium tyrobutyricum spores in milk

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Water Supply & Treatment (AREA)
• Engineering & Computer Science (AREA)
• Biochemistry (AREA)
• Analytical Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Health & Medical Sciences (AREA)
• Physics & Mathematics (AREA)
• Sampling And Sample Adjustment (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=9379003

Family Applications (1)

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Cited By (4)

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Citations (3)

Family Cites Families (1)

• 1989
  • 1989-02-22 FR FR8902272A patent/FR2643285B1/fr not_active Expired - Lifetime
• 1990
  • 1990-02-22 WO PCT/FR1990/000127 patent/WO1990010211A1/fr unknown

Patent Citations (3)

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