REGENERABLE SYSTEM AND METHOD FOR FILTRATION OF A DRAINAGE LIQUID WITH MICROFIBERS

Abstract

The invention relates to a method and a regenerable system for filtering microfibers from a liquid effluent from a textile treatment device, the system comprising at least one removable enclosure formed by upper (20) and lower (30) casings, a filter cartridge (10) comprising a granular medium (1) and a free volume (40), means for supplying (21, 22) and means for evacuating (31, 32) the liquid effluent, means for connecting (21, 22) to means for regeneration by gas aspiration, the means for supplying (21, 22) the liquid effluent and the means for connecting (31, 32) to the means for regeneration by gas aspiration comprising at least one common opening (21, 22) provided in the upper casing (20) and being configured to allow alternatively a connection to a drain line of the textile treatment device and a connection to the means for regeneration by gas aspiration. Figure 2a to be published.

Description

Title of the invention: REGENERABLE SYSTEM AND METHOD FOR FILTERING MICROFIBERS FROM A DRAIN LIQUID Technical field

[0001] The present invention relates to the field of removing microfibers contained in a drain liquid from a textile treatment device, such as a washing machine.

[0002] Recent studies indicate that between 20 and 35% of microplastics found in the marine environment are microfibers from synthetic clothing. These microplastics are mainly released during the washing of synthetic textiles in the form of microfibers, due to the abrasion of the fabrics during the wash cycle. More than 700,000 microscopic fibers can thus be released into wastewater during each use of a domestic washing machine, with many likely to pass through wastewater treatment and therefore end up in the environment.

[0003] More precisely, according to certain studies, the quantity of fibers released during the washing of textiles would correspond to a quantity varying from 0.005 to 0.02% of the weight of the washed textiles depending on the nature of the textile. Other studies consider that the release of fibers during the washing of textiles would even correspond to a quantity varying from 0.02 to 0.1% of the weight of the washed textiles depending on the nature of the textile.

[0004] It is therefore also a major public health problem since this microplastic is found in the water and food we consume. According to the latest estimates, a human being ingests an average of 5 grams of plastic each week, the equivalent of the weight of a credit card.

[0005] Furthermore, on January 30, 2020, France passed a law relating to the fight against waste and the circular economy in which Article 10 bis AAB stipulates that new washing machines must be equipped with a plastic microfiber filter from January 1, 2025. France is the first country in the world to take such a measure. Prior art

[0006] Document US 4906367 is known, which describes a flexible woven filter positioned at the level of the drain pipe of a washing machine. The main impurities such as hair balls are retained by this filter, which must be physically removed for cleaning as soon as it becomes clogged. The filter described in this document was initially designed to protect wastewater pipes and not to retain objects as small as microfibers. The pores of this filter are in fact not large enough fine to allow their retention effectively. Using smaller pores for this type of filter would lead to rapid clogging and a too short filter life.

[0007] We also know application WO 2017 / 173215, which describes a spherical plastic object that is introduced into the drum of a washing machine with the clothes to be cleaned and that allows the released fibers to be captured in situ thanks to numerous protuberances. The geometry of these protuberances is however not currently designed to capture small objects such as microfibers, the retention efficiency of microfibers whose length is greater than 100 pm being only 26%.

[0008] We also know application WO 2017 / 121862 which describes a woven filtering plastic bag into which the clothes to be washed are placed and capable of retaining some of the textile microfibers. The bag has perforations with a diameter of between 5 and 200 μm, preferably 50 μm. If the problem of microfibers is addressed here, one may wonder whether putting clothes in a bag will not harm the washing thereof. In particular, dirt particles larger than the microfibers will not be able to be evacuated properly. The mechanical action of the drum may also be less effective if the clothes are in a bag. The document does not detail how certain microfibers will not escape again when the clothes are removed from the bag.

[0009] Patent application WO 2019 / 017848 describes a system for retaining microfibers, comprising a filter cartridge in a removable enclosure, to be positioned at the outlet of a washing machine, based on microfiltration membranes made of polyethylene nanofibers. The membrane has a preferred pore diameter of around 50 μm and is optionally doped with aluminum oxide nanoparticles to improve the adsorption of microfibers. The filter membrane described in this document has a certain mobility, which allows it to have an anti-clogging function. However, despite this anti-clogging function, the filter cartridge containing the micro-filtration membrane marketed to date has a lifespan of 20 washing cycles. The use of such a filter therefore requires a significant quantity of consumables, and therefore a significant consumption of plastic materials to manufacture them.In addition, the plastic nanofibers constituting the membrane can present a risk of deterioration during use, and therefore of release into wastewater. Finally, when the filter is clogged, the percolation flow rate decreases sharply and ultimately leads to clogging of the system, preventing the evacuation of the liquid which then gradually accumulates upstream of the membrane, with no possibility of evacuating the liquid other than by dismantling the filter.

[0010] In patent application FR 20 / 03351, a system and method for filtering the microfibers (plastic or other) at the outlet of textile treatment devices are proposed. This system allows the collection of at least part of the microfibers at the outlet of a textile treatment device thanks to depth filtration on a granular bed, for possible subsequent recovery, thanks to the implementation of fluidization of the granular medium. However, this system has several openings each with their own function, which could make its use complex for a user (opening and closing of valves to move from a filtration phase to a regeneration phase). In addition, the system must be completely replaced if the fouling of the granular filter is too significant to be eliminated by a simple regeneration. Summary of the invention

[0011] The present invention aims at a modular and simplified alternative to the microfiber filtration systems and methods according to the prior art. In particular, the system for filtering microfibers according to the invention comprises a filter cartridge comprising a granular medium, insertable into a removable enclosure. In addition, the system according to the invention is provided with only two openings and does not require valves. Indeed, the opening connected to a drain pipe of a washing machine for the supply of liquid effluent can be temporarily disconnected for regeneration by gas suction of the granular medium from the filter cartridge. The modular and removable design of the system according to the invention makes it possible to easily replace the filter cartridge, for example if the fouling is too significant to be eliminated by simple regeneration, without having to change the entire filtration system.The filtration system according to the invention is designed to be cleaned simply, using a commercial device such as a vacuum cleaner, to recover the microfibers deposited in the granular filter.

[0012] The invention relates to a regenerable system for filtering microfibers contained in a liquid effluent from a textile treatment device, comprising at least: an enclosure formed by, in the operating position, at least one upper casing and one lower casing, a filtration cartridge arranged inside said enclosure, means for supplying said liquid effluent into the enclosure comprising at least one opening arranged in said upper casing of said enclosure and above said filtration cartridge, means for discharging said liquid effluent comprising at least one opening arranged in said lower casing of said enclosure and below said filtration cartridge, means for assembling together in a removable manner at least said upper and lower casings.

[0013] Furthermore, the system according to the invention is such that:

[0014] - said filtration cartridge comprises a granular medium occupying a portion of the volume of said filtration cartridge, said granular medium being surmounted by a free volume;

[0015] - said enclosure comprises means of connection to regeneration means by gaseous suction of said granular medium, comprising at least said opening arranged in said upper casing of said enclosure;

[0016] - said means for supplying said liquid effluent and said connection means to means for regenerating said granular medium by gas suction are configured to alternately allow a connection to a drain pipe of said textile treatment device and a connection to said means for regenerating said granular medium by gas suction.

[0017] According to one implementation of the invention, said filtration cartridge may comprise a pipe arranged to short-circuit said granular medium in the event of an accumulation of said liquid effluent above said granular medium, said pipe of said filtration cartridge preferably being provided with a deflector in its upper part and / or a non-return valve in its lower part.

[0018] According to one implementation of the invention, said pipe of said filtration cartridge may further comprise a liquid detector, preferably connected to an alarm.

[0019] According to one implementation of the invention, said free volume above said granular medium may represent at least 20% of the volume of said granular medium, preferably between 30 and 50% of the volume of said granular medium, and is preferably 40% of the volume of said granular medium.

[0020] According to one implementation of the invention, said granular medium may comprise sand particles, crushed glass beads or raw glass beads, particles formed from natural or synthetic zeolite, from alumina, or from resins or plastic.

[0021] According to one implementation of the invention, said granular medium may comprise particles of size between 0.1 mm and 2 cm for at least 80% by weight of said particles, preferably between 0.3 and 2.5 mm for at least 90% by weight of said particles.

[0022] According to one implementation of the invention, a liquid distributor may be arranged between said filtration cartridge and said opening provided in said upper casing of said enclosure and / or a gas distributor may be arranged between said filtration cartridge and said opening of said means for discharging said liquid effluent.

[0023] According to one implementation of the invention, at least said opening arranged in said upper casing of said enclosure of said means for supplying said effluent liquid and said means of connection to means of regeneration by gas suction of said granular medium may have an internal diameter of at least 30 mm, preferably between 30 mm and 35 mm.

[0024] According to one implementation of the invention, said means for supplying said liquid effluent and said means for connecting to means for regenerating said granular medium by gas suction may comprise connectors.

[0025] The invention further relates to a method for filtering microfibers contained in a liquid effluent from a textile treatment device, said method being implemented by means of a regenerable system for filtering microfibers as described above. Said method comprises at least the following steps:

[0026] A) said means for supplying said liquid effluent are connected to a drain pipe of said textile treatment device;

[0027] B) at least one filtration phase of said microfibers is carried out, comprising at least the passage of said liquid effluent through said granular medium by means of at least said means for supplying said liquid effluent, and said filtered liquid effluent is evacuated from said microfibers by means of said means for evacuating said liquid effluent;

[0028] C) said means for supplying said liquid effluent are disconnected from said drain pipe of said textile treatment device, and said connection means are connected to means for regenerating the granular medium by gas suction to means for regenerating the said granular medium by gas suction

[0029] D) a regeneration phase is carried out by gas suction of said granular medium.

[0030] According to one implementation of the invention, step B) can be repeated between 50 and 150 times, preferably approximately 100 times, before carrying out steps C) and D).

[0031] According to one implementation of the invention, the method may comprise, prior to step B), a step of pre-treatment of said liquid effluent, said step of pre-treatment of said liquid effluent comprising at least one injection of at least one flocculating agent into said liquid effluent and / or at least one decantation of said liquid effluent and / or at least one cyclonic separation of said liquid effluent.

[0032] According to one implementation of the invention, the method may comprise, prior to step C), a phase of draining said granular medium, carried out by connecting said gas suction means at least to the opening of said means for discharging said liquid effluent, and / or a phase of drying said granular medium, carried out by means of means for heating said granular medium.

[0033] The invention further relates to a filtration cartridge comprising a granular medium occupying a portion of the volume of said filtration cartridge and being surmounted by a free volume, said filtration cartridge being configured to be inserted and fixed in a removable manner to the regenerable system for the filtration of microfibers contained in a liquid effluent as described above.

[0034] The invention further relates to a textile treatment device, comprising at least one regenerable system for the filtration of microfibers contained in a liquid effluent as described above. List of figures

[0035] Other characteristics and advantages of the system according to the invention will appear on reading the following description of non-limiting examples of embodiments, with reference to the figures appended and described below. [Fig la ]

[0036] [Fig. 1a] illustrates a first embodiment of the filtration cartridge of the filtration system according to the invention. [Fig 1b]

[0037] [Fig. 1b] illustrates a variant of the first embodiment of the filtration cartridge of the filtration system according to the invention presented in [Fig. 1a]. [Fig 2a]

[0038] [fig.2a] illustrates a first embodiment of the filtration system according to the invention. [Fig 2b]

[0039] [fig.2b] illustrates a variant of the first embodiment of the filtration system according to the invention presented in [fig.2a]. [Fig 3a] [Fig 3b]

[0040] Figures 3a and 3b show enlargements of the upper part of the upper casing of the system according to the invention. [Fig 4]

[0041] [Fig.4] shows a possible configuration of the system according to the invention for carrying out a regeneration phase by gas suction. Description of the embodiments

[0042] The invention relates to a regenerable system and method for the filtration of microfibers contained in a liquid effluent from a textile treatment device.

[0043] By "microfibers" is meant particles from woven or knitted materials, composed of natural (cotton, wool, etc.) or synthetic (polyester, polyamide, acrylic, etc.) fibers such as clothing or fabrics used in clothing or for any other application (for example, sheets, curtains, etc.) in private homes or in industry. Microfibers, normally carried in waste water from a washing machine, are generally elongated in shape, with diameters generally between 0.1 and 50 microns. The length of the fibers can range from a few fiber diameters up to several mm depending on the nature and condition of the materials that are washed upstream.

[0044] By "textile treatment device" is meant in particular a textile washing device, for example an individual washing machine (or a washing machine), for domestic or commercial use, a set of washing machines (for example in laundries), an industrial laundries (for example a laundry), etc. But a textile treatment device according to the invention generally comprises any device bringing a textile into contact with a liquid, the liquid then being separated from the textile, such as a device for dyeing a textile, or a device for waterproofing a textile.

[0045] By "liquid effluent from at least one textile treatment device" is meant the liquid from the emptying of the textile treatment device, for example the liquid after washing and / or rinsing and / or spinning in the case of a washing machine. This is subsequently referred to equivalently as "drain liquid". Conventionally, the microfiber load of liquid effluents leaving textile treatment devices is generally limited, with contents between 0.1 and 1000 ppm by weight, generally between 1 and 100 ppm by weight.

[0046] The system according to the invention is intended to be connected to a pipe for emptying a textile treatment device, for example at the end of the pipe for emptying the textile treatment device. According to the invention, the connection of the system to a pipe for emptying a textile treatment device is carried out in such a way as to allow, in the operating position, an essentially vertical flow of liquid effluent through the filtration system. Indeed, as will be described in more detail below, the general principle of the filtration system according to the invention consists of the filtration of the microfibers contained in a liquid effluent from a textile treatment device, by percolation of this liquid effluent through a granular medium contained in a filtration cartridge. An essentially vertical flow, from top to bottom, through the granular medium, is therefore advantageous.

[0047] The system according to the invention is also intended to be connected to means for regenerating the granular medium by gas suction, for example to a conduit of a commercial or industrial vacuum cleaner. In this sense, the filtration system according to the invention is regenerable. According to the invention, the connection of the system to means for regeneration by gas suction is carried out in such a way as to allow a flow of gas from the bottom to the top (relative to the filtration service position) through the filtration system.

[0048] The system according to the invention is preferably installed outside the washing machine, for example at the end of the pipe for emptying the textile treatment device. An external positioning allows easy access to intervene on the filtration system, for example to extract the filtration cartridge, or to connect the system to means of regeneration by gas suction of the granular medium as will be described below.

[0049] The system according to the invention comprises at least:

[0050] - an enclosure formed by, in the operating position (i.e. in the position suitable for filtration), at least one upper casing and one lower casing;

[0051] - a filtration cartridge arranged inside the enclosure, and comprising a medium granular occupying a portion of the volume of the filtration cartridge, and a free volume above the granular medium: thus the filtration cartridge comprises the filter medium consisting of a granular medium to capture the microfibers in the granular stack, using the principle of depth filtration;

[0052] - means for bringing the liquid effluent into the enclosure, comprising at at least one opening provided in the upper casing of the enclosure, above the filter cartridge. Thus, in the operating position (i.e. at least during the filtration phase), this opening allows the liquid effluent to pass through the granular medium contained in the filter cartridge from top to bottom, or in other words, this opening allows the percolation of the liquid effluent through the granular medium;

[0053] - means for discharging the liquid effluent comprising at least one opening arranged in the lower casing of the enclosure, below the filter cartridge: and located below the filter cartridge. Thus, in the operating position (i.e. at least during the filtration phase), this opening of the liquid effluent discharge means allows the liquid effluent filtered by the granular medium to exit;

[0054] - means for assembling together in a removable manner at least the casings upper and lower: these removable assembly means allow in particular access to the filtration cartridge placed inside the enclosure formed by the assembly of the upper and lower casings;

[0055] - means of connection to means of regeneration of said granular medium by gas suction, comprising at least the opening provided in said upper casing of the enclosure: in other words, the opening of the means for bringing the liquid effluent into the enclosure is the same opening as that of the means for regenerating said granular medium by gas suction;

[0056] Furthermore, according to the invention, the means for supplying the liquid and the means for connection to means for regeneration by gas suction of the granular medium are configured to alternately allow connection to a drain line of the textile treatment device and connection to means for regeneration by gas suction of the granular medium.

[0057] Thus, the general principle of the filtration system according to the invention consists of the filtration of the microfibers contained in a liquid effluent from a textile treatment device, by percolation of this liquid effluent through a granular medium. According to the invention, the system according to the invention comprises an enclosure, formed by the removable assembly of an upper casing and a lower casing, and inside which is arranged a filtration cartridge comprising the granular medium. The system according to the invention is further configured to be connected to means for regeneration by gas suction of the granular medium, so as to eliminate in particular the microfibers having deposited in the granular medium.The fact that the granular medium is contained in a filter cartridge allows the replacement of the filter cartridge, when the latter is defective or if, due to use in abnormal conditions such as water loaded with microparticles other than textile microfibers, the granular medium of the filter cartridge is too dirty to be regenerated. Under normal conditions of use, that is to say for a liquid effluent essentially loaded with textile microfibers, the process can be implemented with the same filter cartridge which is regenerable.

[0058] In addition, this prevents the user from having to handle the granular medium and being exposed to direct contact with the particles of the granular medium.

[0059] Furthermore, according to the invention, the means for supplying the liquid and the means for connection to means for regeneration by gas suction of the granular medium are configured to allow alternately a connection to a drain pipe and a connection to means for regeneration by gas suction of the granular medium, which allows simplified operation of the system according to the invention.

[0060] According to the invention, a portion of the volume of the filtration cartridge is occupied by the granular medium and the granular medium is surmounted by a free volume in the filtration cartridge. The free volume above the granular medium makes it possible, on the one hand, to avoid the risk of backflow of the liquid effluent in the event of accumulation above the granular medium (which can occur in the event of clogging of the granular medium), and on the other hand to allow the expansion of the particles during regeneration by gas suction of the granular medium as will be described below. According to one implementation of the invention, the free volume above the granular medium represents at least 20% of the volume of the granular medium, preferably between 30 and 50% of the granular medium, and is preferably 40%. Such free volumes are born necessary to allow the expansion of the particles during the regeneration phase by gas suction of the granular medium. In particular, a free volume between 30 and 50% allows optimal efficiency of the regeneration phase while limiting the dimensions of the filtration cartridge, and thus the size of the system according to the invention.

[0061] The granular medium according to the invention comprises at least one bed of particles as will be described below.

[0062] The method according to the invention generally comprises at least one step of filtering the microfibers contained in a liquid effluent from a textile treatment device, by percolation of this liquid effluent through a granular medium, followed by a step of regeneration by gas suction of the granular medium. Indeed, as the washing sequence progresses, the filter cartridge gradually becomes loaded with microfibers and microparticles contained in the liquid effluent. According to the invention, the system according to the invention can then be disconnected from the drain pipe of the textile treatment device to be connected to gas suction means. Preferably, the regeneration phase is carried out by means of an upward flow of a gas corresponding to air.

[0063] Different embodiments of the invention are described below.

[0064] According to one implementation of the invention, the enclosure, resulting from the assembly of the upper and lower casings, may be cylindrical or parallelepipedal in shape, and may preferably be elongated along the axis of the flow of the liquid effluent passing through the enclosure (i.e. along a vertical axis).

[0065] Advantageously, the enclosure and the filter cartridge have corresponding shapes, so as to allow the insertion of the filter cartridge into the enclosure. Advantageously, the sections of the enclosure and the cartridge are dimensioned so as to allow the filter cartridge to be inserted with a small clearance inside the enclosure. Thus, for example, if the filter cartridge has a substantially cylindrical shape, the upper and lower casings forming the enclosure also have a substantially cylindrical shape, and the internal diameter of the casing has substantially the same dimension as the external diameter of the filter cartridge, with the clearance determined according to the mechanical tolerance allowing the filter cartridge to be assembled inside the casings.Advantageously, the filter cartridge is removably attached to the enclosure, for example by bolting, screwing by clipping (snap-fastening), or a bayonet assembly. This makes it possible to maintain the filter cartridge in the operating position in the enclosure. Advantageously, the filter cartridge is dimensioned and arranged in the enclosure so that a free volume in the enclosure is formed at least above the filter cartridge, and preferably also en- . below the filter cartridge. This or these free volumes above and below the filter cartridge prevent the risk of liquid effluent backflow in the event of accumulation, due for example to clogging of the granular medium of the filter cartridge. Clogging of the granular medium can occur due to the deposition of microfibers in the granular medium, but generally by any type of solid matter, including limescale deposits.

[0066] Implicitly, the filtration cartridge comprises upper and lower walls at least permeable to the liquid effluent, so as to allow the flow of this effluent through the filtration cartridge. The upper and lower walls are therefore in fact permeable to gases in general (i.e. to all gases), in particular to the gas which can be used for the regeneration by gas suction of the granular medium as will be described below. Advantageously, the granular medium rests on the lower wall of the filtration cartridge. The filtration cartridge may be cylindrical or parallelepipedal in shape, and is preferably elongated along the axis of the flow of the liquid effluent passing through the enclosure (i.e. along a vertical axis).Advantageously, the upper and lower walls of the cartridge can be fixed integrally to the side walls of the filter cartridge by removable fixing means (for example by screwing, clipping, etc.), in order to allow their maintenance.

[0067] Advantageously, the opening of the means for supplying the liquid effluent can be arranged in the upper wall of the upper casing according to the invention, preferably in a central part of this upper wall (for example located in an area centered on the barycenter of the upper wall, and the radius of which can correspond to 30% of the smallest dimension of the upper wall). An opening arranged in a central part of the upper wall of the enclosure allows a more homogeneous laterally distribution of the liquid effluent compared to an eccentric opening.

[0068] Advantageously, the opening of the liquid effluent evacuation means can be arranged in the lower wall of the lower casing according to the invention, to avoid an accumulation of the filtered liquid effluent in the bottom of the enclosure. According to one implementation of the invention, this opening can be connected to a wastewater evacuation system, such as a siphon upstream of a sewer system. Depending on the geometric configuration, a lifting pump can be implemented in order to ensure the evacuation of the filtered effluent.

[0069] The system according to the invention also comprises means for connection to means for regeneration by gaseous suction of the granular medium, thanks to a gaseous suction operated through the opening located in the upper part of the enclosure, above the filtration cartridge. Under the effect of the suction flow, a An upward convection gas movement is generated in the particle bed. The particles in the filtration bed are set in motion and fluidized, without being entrained with the gas flow. Fibers smaller than the particles constituting the filtration bed are entrained with the upward flow. The means for regenerating the granular medium by gas suction aim to prevent clogging of the granular medium which can result from the accumulation, in particular, of filtered microfibers in the granular medium. The means for regenerating the granular medium by gas suction make it possible to extend the service life of the system according to the invention. According to one implementation of the invention, the means for regenerating the granular medium may be a vacuum cleaner for domestic or industrial use. Advantageously, the gas in the gas suction means is air, which avoids the need for means for storing the gas or gas admission means other than a vent line.In fact, in this case, the air can be sucked either through the opening of the liquid effluent discharge means arranged in the lower casing if the enclosure has not been disassembled, or through the base of the filter cartridge if the enclosure has been disassembled to remove the lower casing.

[0070] According to the invention, the opening of the means for regenerating the granular medium by gas suction therefore corresponds to the opening of the means for supplying the liquid effluent into the enclosure. In other words, the opening provided in the upper casing of the enclosure can be used both for supplying the liquid effluent and for regenerating the granular medium by gas suction. This allows for simplified manufacture and use of the upper casing of the enclosure by a user (single connection point, no valves to handle).This may further allow that both the opening for the supply of the liquid effluent and the opening for the gas suction regeneration of the granular medium are arranged centrally in the upper wall of the upper housing, which contributes to a homogeneous distribution of both the liquid effluent on the granular medium of the filter cartridge and the gas during the gas suction regeneration.

[0071] Advantageously, the means for regenerating the granular medium by gas suction can be configured to remove the microfibers from the granular medium when the accumulated volume of microfibers represents 0.1 to 10% of the porosity of the granular medium, preferably 0.5 to 5% of the porosity of the granular medium. In this way, it is possible to carry out around a hundred filtration phases before regenerating the granular medium of the system according to the invention.

[0072] According to the invention, the means for bringing the liquid effluent into the enclosure and the means for connection to the gas suction regeneration means are configured so as to alternately allow connection to a drain pipe of a textile treatment device and to regeneration means by as gaseous suction. In other words, the means for bringing the liquid effluent into the enclosure and the means of connection to the gaseous suction regeneration means are configured to meet the operating constraints of both the textile treatment devices and the gaseous suction regeneration means. For example, the pipe for draining a washing machine generally consists of a hose with an internal diameter less than or equal to 25 mm, which ensures the evacuation of the wash water without generating a significant pressure drop. Furthermore, the pipes of the gaseous suction means, and at least the pipes of commercial vacuum cleaners, generally have an internal diameter greater than 30 mm. Indeed, the speed of the gas is greater than the speed of the liquid effluent and these dimensions are necessary to minimize the pressure drop of the flow.According to one implementation of the invention, the common opening of the means for supplying the liquid effluent into the enclosure and of the means for connecting to gas suction regeneration means may have an internal diameter at least equal to the internal diameter of the gas suction regeneration means. Preferably, the common opening of the means for supplying the liquid effluent and of the gas suction regeneration means has an internal diameter of at least 30 mm, preferably between 30 and 35 mm. Such diameters make it possible to avoid a limitation of the flow during the regeneration phase with gas suction regeneration means at least of the commercial vacuum cleaner type.Advantageously, if the external diameter of the washing machine drain pipe is less than or equal to the internal diameter of the common opening of the means for supplying the liquid effluent and the means for regeneration by gas suction, the washing machine drain pipe can be inserted into the common opening of the means for supplying the liquid effluent and the means for connection to means for regenerating said granular medium.According to one implementation of the invention, the means for connecting the gas suction regeneration means and / or the means for supplying the liquid effluent may comprise a connector (such as a ring, for example), in particular to compensate for the differences in diameter between the common opening of the means for connecting to the gas suction regeneration means and the means for supplying the liquid effluent and the drain pipes and / or the gas suction means, but also to guarantee the sealing of the connection between these different elements.

[0073] Advantageously, the upper wall and / or the lower wall of the filtration cartridge permeable to the liquid effluent may consist of a grid, or a porous support open to the passage of fluids, the size of the openings of the grid or of the porous support being however smaller than the size of the particles of the granular medium. This grid or porous support open to the passage of fluids makes it possible to retain inside the filtration cartridge the particles of the granular medium, during handling of the cartridge and during regeneration by gas suction. In the case of the upper wall of the filtration cartridge, such a porous grid or support open to the passage of fluids can also allow a more homogeneous distribution of the liquid effluent on the granular medium, thus improving the filtration quality of the system according to the invention. In addition, this porous grid or support open to the passage of fluids can serve as a pre-filter and retain objects of a size comparable to the size of the particles of the granular bed or larger outside the filtration cartridge. In the case of the lower wall of the filtration cartridge, such a porous grid or support open to the passage of fluids can also allow a more homogeneous distribution of the fluids during the regeneration phase of the granular medium.

[0074] According to one implementation of the invention, the upper wall and / or the lower wall of the filtration cartridge may consist, for example, of two superimposed perforated plates between which a sieve grid will have been arranged, the holes of the plates having a size greater than the average size of the particles while the sieve grid has a mesh size smaller than the average size of the particles constituting the granular medium. Alternatively, the upper wall and / or the lower wall of the filtration cartridge may consist of a rigid or supported simple sieve grid, the mesh size of which has a mesh size smaller than the average size of the particles constituting the granular medium. Alternatively, the upper wall and / or the lower wall of the filtration cartridge may consist of a plate made of sintered material allowing the passage of fluids inside the sintered material.Preferably, to properly distribute the air sucked into the granular medium during regeneration, the porosity of the upper wall can be sized according to a pressure drop in the gas flow of between 10 and 2000 Pa for a gas flow of 1 m / s at atmospheric pressure and at 25°C, and preferably between 5 and 1000 Pa. Preferably, to properly distribute the air sucked into the granular medium during regeneration, the lower wall of the filtration cartridge can be sized so as to offer a certain resistance to the flow of the gas during regeneration, while offering low resistance to the passage of the liquid during filtration.Advantageously, the porosity of the lower wall can be sized according to a pressure drop of between 100 and 10000 Pa for a gas flow of 1 m / s at atmospheric pressure and at 25°C, preferably between 500 and 5000 Pa and very preferably between 1000 and 3000 Pa.

[0075] Advantageously, a jet breaker may also be arranged in the enclosure, above the upper wall of the filter cartridge, and under the opening for the supply of the liquid effluent, allowing the introduction of the liquid effluent from the washing machine located in the upper casing so as to disperse it and thus prevent an excessively powerful jet of liquid effluent from impacting the permeable medium of the upper wall of the filtration cartridge or the granular medium. The jet breaker may, for example, have the shape of a solid or hollow cone, a double cone or a disc, or any other shape allowing a fluid to be dispersed. Advantageously, a liquid distributor may also be arranged in the enclosure, above the upper wall of the filtration cartridge, and under the opening for supplying the liquid effluent. Generally speaking, a liquid distributor allows a homogeneous distribution of a liquid. According to one implementation of the invention, the liquid distributor may be a perforated liquid-retaining plate. Such a distributor makes it possible to distribute the liquid uniformly over the section of the granular medium.

[0076] Advantageously, a gas distributor may be arranged between the filtration cartridge and the opening allowing the admission of gas from the gas suction means, i.e. at least the opening of the means for discharging the liquid effluent. A gas distributor allows homogeneous distribution of a gas. According to one implementation of the invention, the gas distributor may be a perforated plate. Advantageously, the orifices of the perforated plate are sized so that the pressure drop generated during the passage of the gas through the orifices leads to a uniform distribution of the gas at the outlet of the distributor.

[0077] According to one implementation, the means for assembling together in a removable manner at least the upper and lower casings of the enclosure may be screwing means, clipping (snap-fastening), bolting means, a bayonet assembly, or any other known means for assembling and disassembling the lower and upper casings. According to one implementation of the invention, the means for assembling together in a removable manner at least the upper and lower casings may comprise flat flanges assembled together by means of bolted connections. Very preferably, these means for assembling together in a removable manner at least the upper and lower casings also make it possible to ensure sealing against the liquid effluent of the assembly, and preferably also against the gas of the gas suction regeneration means. In this way, the fluids flow entirely into the enclosure.In the case of flat flanges, the seal can, for example, be ensured by grooves dug into the housing flanges, allowing an O-ring to be fitted which will then be crushed when the flanges are tightened.

[0078] Very preferably, the means for assembling together in a removable manner at least the upper and lower casings can make it possible to assemble in a removable manner the filter cartridge, the lower casing and the upper casing. In this way, the filter cartridge is fixed integrally to the enclosure, which makes it possible to guarantee that the filter cartridge is kept in the operating position in the enclosure. According to one implementation, the means for dismountably assembling the upper and lower casings and the filter cartridge together may comprise flat flanges or collars assembled together by means of bolted connections. Alternatively, the means for dismountably assembling the filter cartridge, the lower casing and the upper casing together may consist of screwing means, for example for screwing the filter cartridge inside the upper casing and inside the upper casing. Very preferably, the means for dismountably assembling the filter cartridge, the upper casing and the lower casing together may comprise means for ensuring the sealing of the assembly, at least to the liquid effluent and preferably also to the gas from the gas suction regeneration means.In this way, the fluids flow completely into the enclosure. These means may consist, for example, of flanges located at the base of the two housings and resting on a flange of the filter cartridge. In the case of flat flanges, the seal may, for example, be ensured by grooves hollowed out in the flanges of the housings allowing an O-ring to be placed which will then be crushed when the three flanges are tightened. Advantageously, when the filter cartridge and the housings are of substantially cylindrical shape, a thread on the external wall of the filter cartridge and the internal wall of the upper housing may allow the cartridge to be assembled in the upper housing by screwing, until a stop corresponding to the flange of the filter cartridge is reached.

[0079] Advantageously, the side walls of the filter cartridge can be formed from a transparent material, which is a property possible with materials such as PVC, polycarbonates, or even PMMA (poly methyl methacrylate acrylic). The transparency allows the user, when the lower casing is dismantled or when the filter cartridge is separated from the enclosure, to check the state of the granular medium and in particular its clogging, as well as to check the proper progress of the regeneration phase of the granular medium.

[0080] Advantageously, the filtration cartridge may comprise a granular medium short-circuit conduit, arranged so as to allow the evacuation of an accumulation of liquid effluent in the free volume of the filtration cartridge above the granular medium. In other words, according to this design, a portion of the liquid effluent which may have accumulated above the granular medium (in the event of an excessively high liquid effluent flow rate compared to the filtration flow rate of the granular medium and / or in the event of clogging of the granular medium) enters through an opening in this conduit located above the granular medium and is evacuated through an opening in this conduit located below the granular medium. This conduit, which acts as a short-circuit, makes it possible to avoid a backflow of the liquid effluent through the upper face of the filtration cartridge which could lead to clogging of the filtration system. emptying of the textile treatment device. Preferably, the pipe according to this design can preferably be equipped with a deflector in its upper part, to prevent the liquid effluent entering through the upper part of the filtration cartridge from penetrating directly into this pipe. Advantageously, this internal short-circuit pipe can also be equipped with a non-return valve, making it possible to prevent gas from rising in the short circuit in the upward vertical direction during a phase of regeneration of the granular medium by gas suction.

[0081] According to a variant of this implementation, the internal short circuit of the filtration cartridge may comprise a liquid detector, preferably connected to an alarm. Such a detector makes it possible to detect the presence of water circulating in the short circuit, which may be an indicator that it is recommended to carry out a regeneration phase of the granular medium since at least part of the liquid effluent is no longer filtered by the system according to the invention. This liquid detector may for example consist of two metal branches separated by a few millimeters, positioned inside the conduit of the short circuit, and supplied with electricity (for example by means of a battery, a cell or a connection to an electrical network). When the water passes between the two branches, the electric current is established and may trigger an alarm, for example a light and / or sound alarm.The light signal can advantageously be maintained over time, i.e. even after water has passed through the short-circuit pipe, in order to alert the user if he was not present when the alarm was triggered.

[0082] [Fig. 1a] illustrates, in a schematic and non-limiting manner, a first embodiment of the filtration cartridge of the system according to the invention. According to this design, the filtration cartridge 10 is delimited by side walls 11, and lower 13 and upper 14 walls. The lower 13 and upper 14 walls are in the form of a grid whose mesh size allows the passage of the liquid effluent while retaining the particles of the granular medium 1 inside the filtration cartridge 10. The granular medium is surmounted by a free volume 40. The filtration cartridge 10 is provided with a collar 12 allowing its integral assembly with the upper casing (not shown) of the enclosure.Preferably, in the case where the wall 11 is transparent to see inside the filtration cartridge, the position of the collar is located above the granular bed which then makes it possible to observe the state of the granular medium by simply dismantling the lower casing.

[0083] [Fig. 1b] presents a variant of the embodiment of [Fig.1a], in every respect identical to this first embodiment (thus, the common elements will not be described again), and in which the filtration cartridge 10 is provided with a short-circuit system formed by a pipe 15 and a deflector 16. The pipe 15 comprises an opening located above the granular medium 1 and an opening located below the granular medium, allowing the excess liquid accumulated above the granular medium 1 to be evacuated. The deflector 16 arranged above the upper opening of the pipe 15 makes it possible to prevent the liquid effluent entering through the upper part of the filtration cartridge 10 from penetrating directly into the pipe 15. The internal short circuit is further provided with a non-return valve 57 preventing gas from rising in the pipe 140 in the upward vertical direction during a regeneration phase of the granular medium.

[0084] [fig.2a] illustrates, in a schematic and non-limiting manner, a first embodiment of the filtration system according to the invention, comprising an enclosure formed by the assembly of an upper casing 20 and a lower casing 30, and a filtration cartridge 10 assembled integrally with the upper 20 and lower 30 casings. The lower casing 30 and the upper 20 casing have sections which allow the insertion, with a small clearance, of the filtration cartridge 10 inside the casings 20, 30. The upper 20 and lower 30 casings are provided with means allowing them to be fixed together integrally and in a removable manner to the filtration cartridge 10. These means consist of two flat flanges 25, 35 resting on the flat flange 12 of the filtration cartridge.The sealing of the assembly is ensured by an O-ring 26 arranged in grooves hollowed out in the flat flanges 25, 35 of the upper 20 and lower 30 casings, which is crushed when the flat flanges 12, 25, 35 are tightened. In order to position the filter cartridge 10 in the upper casing 20 and to ensure sealing to prevent any passage of fluid between the lateral external wall 11 of the filter cartridge 10 and the lateral internal wall of the upper casing 20 (respectively of the lower casing 30), a stop 24 (respectively a stop 34) is arranged on the lateral internal wall of the upper casing 20 (respectively of the lower casing 30), over the entire periphery of the upper casing 20 (respectively of the lower casing 30).The upper face of the upper casing 20 comprises an opening 21, 22, formed by an orifice at the end of a tube 22 secured to the upper casing 20, this opening 21, 22 being intended to be connected alternately either to the liquid effluent discharge pipe of a textile treatment device (not shown), or to means for regenerating the granular medium 1 by gas suction (not shown). This opening 21, 22 is positioned in the center of the upper face of the casing 20 which allows axial introduction of the liquid effluent from the washing machine and axial withdrawal of the sucked gas, and thus better distribution of the fluids in the filtration cartridge 10.The lower face of the lower casing 30 comprises an opening 31, 32, formed by an orifice at the end of a tube 32 secured to the lower casing 30, and allowing a connection to a wastewater evacuation system, such as a siphon upstream of a sewerage device (not shown). The opening. 31, 32 is positioned in the center of the lower face of the lower casing 30, which facilitates the collection and evacuation of the filtered liquid effluent under the filtration cartridge 10 and an axial admission of the sucked gas. Thus, this configuration of the openings 21, 22, 31, 32 of the upper 20 and lower 30 casings allows a better distribution of the fluids in the granular medium 1.

[0085] [fig.2b] shows a variant of the embodiment of [fig.2a], identical in every way to this first embodiment (thus, the common elements will not be described again), and in which a jet breaker 27 is arranged between the opening 21, 22 for the supply of the liquid effluent and the filtration cartridge 10. In addition, this jet breaker is arranged in the axis of the opening 21, 22 for the supply of the liquid effluent, which makes it possible to disperse the liquid effluent homogeneously over the section of the granular medium 1. In this design, the jet breaker 27 is fixed to the upper casing 20 by rigid rods 28, and has the shape of a cone.

[0086] Figures 3a and 3b show enlargements of the upper part of the upper casing of the system according to the invention, so as to detail the means for connecting the opening of the upper casing of the system of the invention to a drain pipe of a textile washing machine and to a commercial vacuum cleaner. In this example, the upper face of the upper casing 20 comprises an opening 21, 22 (formed by an orifice at the end of a tube 22 secured to the upper casing 20) with an internal diameter of 30 mm. In the design of [fig. 3a], the outer diameter of the drain pipe 21 of the washing machine is 32 mm, and is therefore larger than the inner diameter of the opening 21, 22. To enable connection to the drain pipe, a ring 40 adjusted to the inner diameter of the drain pipe 41 is inserted into the opening 21, 22 and the drain pipe 41 is inserted onto this ring. In the design of [fig.3b], the internal diameter of the commercial vacuum cleaner duct 43 is greater than the internal diameter of the opening 21, 22 but is less than the external diameter of the opening 21, 22. In this case, the connection between the commercial vacuum cleaner duct 43 and the opening 21, 22 is provided by the ring 42.

[0087] The granular medium according to the invention comprises at least one bed of particles, hereinafter referred to equivalently as a "filter bed" or "filtration bed". According to one implementation of the invention, the granular medium may comprise a plurality of staged particle beds, each held by a support which is not impermeable at least to the liquid effluent. The support is therefore also in fact not impermeable to gases in general, and in particular to the gas used for the regeneration of the granular medium by gaseous fluidization. According to one implementation of the invention, the support of the granular medium for each staged bed (possibly with the exception of the last bed which may rest directly on the lower face of the filtration cartridge) may be a grid, the meshes of which are sized to retain the granular medium while allowing the passage of at least the liquid effluent. Thus, in the system according to this implementation of the invention, the liquid effluent can flow by percolation through each of the staged beds, from top to bottom.

[0088] The material constituting the particles of a bed can be defined by its composition, but also by its particle size and its density. Different types of particles are possible to constitute a bed of particles, as described below.

[0089] According to one implementation of the invention, the particles of a bed may be sand particles, or crushed glass beads or raw glass beads, particles formed from natural or synthetic zeolite, from alumina, or from resins or plastic. The materials mentioned above have the advantages of being easily accessible commercially and have properties (in particular density as will be discussed below) adapted to the intended application.According to an alternative, the particles of a bed can be made of a material whose surface properties have been modified to promote the retention of the microfibers, by phenomena of physicochemical affinity with the textile microfibers (by modifying the electrostatic properties of the particles in particular), or to limit the affinity of these particles with water (via a hydrophobic treatment, for example by covering the particles such as glass beads with a Teflon film), which makes it possible to facilitate the drying of the bed before regeneration. According to another implementation of the invention, it is possible to use a mixture of particles from materials of different nature for the same bed, or to use particles from materials of different nature from one bed to another in the case where the granular medium is formed by a plurality of staged beds.

[0090] Generally, the particle size distribution influences the filtration and regeneration capacity of the granular medium with respect to the microfibers, by acting on the resistance to fluid flow. According to an advantageous implementation of the invention, the particle size may be, for at least 80% by weight of the particles, between 0.1 mm and 2 cm, preferably, for at least 90% by weight of the particles, between 0.3 and 2.5 mm. Alternatively or in combination, the average equivalent diameter of the particles of the granular medium (defined with respect to the weight size distribution of the particles) of the particles may be between 0.3 and 1.5 mm, and preferably between 0.4 and 1.2 mm. Advantageously, the quantity of particles having a size less than 0.1 mm may be less than 5% by weight.Advantageously, particles having different particle sizes may be used for the same bed, or particles having different particle sizes may be used from one bed to another in the case where the granular medium is formed by a plurality of staged beds. Advantageously, in the case where the granular medium is formed by a plurality of staged beds, the beds may consist of particles having . decreasing particle sizes along the direction of the liquid effluent flow (i.e. from top to bottom), so as to allow filtration first of the largest fibers, then of increasingly finer fibers.

[0091] Generally, the density of the particles constituting a particle bed affects the fluidization of the particles during regeneration (minimum velocity allowing the bed to be fluidized and pressure drop across the bed). The materials described above for constituting particles (e.g. sand, glass, zeolite) generally have grain densities of between 1100 and 2800 kg / m2 suitable for regeneration, for example, by gas suction, even when the suction flow rate is moderate (e.g. with a domestic vacuum cleaner). Advantageously, hollow materials such as hollow glass or plastic beads may be used, the grain density of which may be lower, which then makes it possible to regenerate the bed with lower fluid flow rates.

[0092] Generally speaking, the speed of passage of the liquid effluent in a bed of particles influences on the one hand the quality with which the retention of the fibers is achieved and on the other hand the pressure drop of the liquid effluent through the bed of particles. Advantageously, the system according to the invention can be sized so that the filtration speed (surface speed of the liquid effluent in the bed of particles) is between 1 and 100 m / h, preferably between 5 and 50 m / h. Preferably, the system according to the invention can be sized so that the pressure drop offered by the clean bed of particles (i.e. before any filtration or after regeneration) is between 500 and 100,000 Pa, preferably between 1,000 and 10,000 Pa.It is possible to calculate the flow pressure drop during the passage of the liquid effluent through the particle bed (during first use or after regeneration) using correlations described for example in the document (S. Rhode, “Multiphase operation in process engineering”, Ellipses Edition, 2019).

[0093] According to an implementation of the invention, it is possible to determine an appropriate liquid effluent filtration speed and pressure drop by means of a dimensioning well known to the specialist, carried out at least as a function of the quantity of liquid effluent to be filtered during a given time, the pressure at the discharge of the textile treatment device and the positioning of the system according to the invention on the portion of the pipe for the discharge of the textile treatment device (in particular the positioning of the filtration system according to the invention relative to the discharge of the textile treatment device and relative to the wastewater evacuation system to which the filtration system according to the invention is connected when it is in service).

[0094] Generally speaking, the flow rate of the liquid effluent to be filtered depends on the capacity of the washing machine. For a domestic washing machine, capable of washing between 5 and 10 kg of linen, the system according to the invention can be sized so as to have filtration rates between 1 and 25 1 / min, preferably between 3 and 15 1 / min. The filtration rate is a function of the filtration surface and the filtration speed described above.

[0095] According to an implementation of the invention according to which a single bed of particles is arranged in the filtration cartridge and for a washing machine washing between 5 and 10 kg of laundry, the diameter of the filtration cartridge can vary between 5 and 50 cm of internal diameter, preferably between 10 and 30 cm of internal diameter to have optimal filtration speeds as defined above. Advantageously, the height of a bed of particles can be between 0.5 and 5 times the equivalent diameter of the passage section of the bed of particles, preferably between 0.7 and 2 times the equivalent diameter of the passage section of the bed of particles, which allows time for the microfibers to settle in the porosity of the bed.

[0096] Advantageously, the gas suction means may be supplemented by a particle separation system, arranged downstream of the gas suction means, such as a cyclone chamber or a membrane filter, to collect the microfiber particles. Note that vacuum cleaners for domestic use generally include such particle separation systems. The free volume above the granular medium in the filter cartridge, which serves as an accumulation zone during the filtration phase, makes it possible, during a bed regeneration phase, to contain the expansion of the bed associated with the fluidization of the bed. At the end of the bed regeneration phase, the suction flow is stopped and the particles sediment to once again reform a filter bed free of the fibers deposited during the prior filtration phases.Advantageously, the fibers collected during a regeneration phase can either be used as recycling material or disposed of as non-hazardous waste in appropriate collection systems.

[0097] Generally speaking, the velocity of the rising gas during the regeneration of the particle bed determines the agitation of the granular medium. It is well known to those skilled in the art that to set a particle bed in motion, the gas must rise through the granular bed with a flow velocity greater than a velocity called "minimum fluidization velocity", which can be calculated using correlations well known to those skilled in the art (for example, as described in the document (Wen CH & Yu YH, Chem. Eng. Prog. Symp. Sériés, 82, 100-111 (1966)) and the value of which depends on the properties of the granular medium (particle size, density).Preferably, during regeneration, the bed of particles can be fluidized by an upward movement of air, at a speed passing through the bed preferably corresponding to a speed of between 2 and 20 times the value of the minimum fluidization speed, in order to promote agitation of the particles. of the bed, and thus cause the collected microfibers to fly out of the bed. Very preferably, the speed of the ascending air through the bed can be between 3 and 10 times the minimum fluidization speed. In the case of a domestic washing machine washing between 5 and 10 kg of laundry, this range of ascending gas speeds allows fluidization to be ensured, without requiring specific suction means. In other words, this range of ascending gas speeds is generally compatible with the characteristics of the majority of commercial vacuum cleaners available for domestic use.

[0098] Generally speaking, the suction flow rate through the filter medium depends on the washing capacity of the washing machine. For a simple domestic washing machine with a washing capacity of 5 to 10 kg of laundry, the system can be sized so as to have suction flow rates of around 10 to 100 l / s, preferably between 20 and 40 l / s, making it possible to generate a suction vacuum of between 5 and 50 kPa, preferably between 20 and 40 kPa. These characteristics are compatible with the characteristics of the majority of commercial vacuum cleaners available for domestic use. In the case where the system according to the invention is installed downstream of industrial laundries or downstream of a set of washing machines, a specific suction system, characterized by higher flow rates and suction speed, may be preferred.

[0099] The invention further relates to a method for the filtration of microfibers contained in a liquid effluent, which can be advantageously implemented by means of the regenerable system for the filtration of microfibers contained in a liquid effluent according to any one of the embodiments or any one of the combinations of the embodiments described above.

[0100] The method according to the invention comprises at least the following steps:

[0101] A) the means for supplying the liquid effluent described above are connected to a operation of a textile processing device;

[0102] B) at least one filtration phase is carried out comprising at least the passage of the liquid effluent through the granular medium by means of at least the means for supplying the liquid effluent described above, and the liquid effluent thus filtered is evacuated by means of the means for evacuating the liquid effluent described above;

[0103] C) the means for supplying the liquid effluent from the conduit of the textile treatment device are disconnected, and the means for connecting to means for regeneration by gas suction of the granular medium described above are connected to means for regeneration by gas suction of the granular medium;

[0104] D) a regeneration phase is carried out by gas suction of the granular medium.

[0105] Advantageously, step B) is repeated between 20 and 150 times, preferably approximately 100. times before carrying out steps C) and D). Indeed, it is important to proceed regularly linked to the regeneration of the filter medium in order to avoid clogging, but it may not be necessary to carry out a regeneration phase systematically after each filtration phase, depending on the microfiber load of the liquid effluent. For example, it is possible to estimate a frequency of triggering the regeneration phase, by estimating a clogging speed of the porosity of the filter bed by accumulation of microfibers, from the concentration of microfibers in the liquid effluent at each wash. This embodiment, by avoiding systematic regeneration phases, allows in particular energy savings.

[0106] Preferably, a regeneration phase is carried out by gas suction of the granular medium, after a plurality of filtration phases, when it is detected that the percolation flow rate of the liquid effluent slows down. According to one implementation, a regeneration phase of the granular medium can be triggered in the following manner: for each filtration phase, the variation in the level of the liquid effluent in the free volume above the granular medium is measured as a function of time; this measurement is compared to a reference value of the percolation flow rate, obtained for example by measurement when the granular medium is free of microfibers; when the measurement is at least 100% lower than the reference value, or preferably at least 50% lower than the reference value, a regeneration phase is carried out by gas suction of the granular medium at the end of the current filtration phase.

[0107] Preferably, the regeneration phase by gas suction of the granular medium may only be triggered after a predetermined duration, taken from the end of the last filtration phase, allowing at least the drainage of the liquid effluent and preferably also the drying of the granular medium, in order to evacuate all the moisture contained in the granular medium. This predetermined duration may be between 3 and 7 hours, preferably 5 hours. According to one implementation of the invention, to promote drying, it is also possible to establish natural or forced convection of gas through the granular medium, by keeping open the openings of the means for discharging the liquid effluent and the means for connecting to the means for regeneration by gas suction of the granular medium. The predetermined duration will advantageously be limited when hydrophobic particles are used and / or the filter is constructed with a hydrophobic material.

[0108] [fig.4] shows a possible configuration of the system according to the invention for carrying out the regeneration phase, a configuration which is identical in every respect to that of [fig.2a] (thus, the common elements will not be described again), with the exception of the fact that the lower casing (not shown) has been disassembled from the upper casing 20 and the filtration cartridge 10. In this configuration, the means for regeneration by gas suction of the granular medium can be connected to the opening 21, 22 which is a common opening serving both for connection to the means for regeneration generation by gas suction (not shown) and to a drain pipe of a textile treatment device (not shown). In this configuration, the air intake is carried out at the level of the grid 13 constituting the lower face of the filtration cartridge 10. This particular configuration allows the user, when the walls of the filtration cartridge are transparent (according to an embodiment described above), to check the proper progress of the regeneration phase. It is obviously also possible to regenerate the filtration cartridge without dismantling the lower casing, as shown in [fig.2a]. Under these conditions, the system is connected to gas suction regeneration means by the opening 21,21 and the gas intake is carried out at the opening 31,32.

[0109] Advantageously, the method according to the invention may comprise, prior to step C), a phase of draining the granular medium, carried out by means of gas suction means connected to the system according to the invention so as to generate a downward flow of gas through the granular medium. In other words, the gas suction means are connected this time at least to the opening of the liquid effluent discharge means. The suction of gas through an opening located in the lower casing allows forced convection of gas through the granular medium from top to bottom. This forced convection of gas entrains a large part of the residual liquid present in the interstices of the granular medium, thus facilitating its gravitational flow and making it possible to reduce the residual humidity of the bed.Under these conditions, with the help of the circulation of the gas, it is thus possible to reduce the volume fraction of the liquid in the bed to a content of less than 10%, or even to completely dry the bed if the time of this step is sufficiently long. Thus, this circulation of a gas makes it possible to facilitate the gravitational flow of the liquid effluent trapped in the granular medium, before proceeding with the regeneration of the granular medium. Advantageously, the system according to the invention can comprise means for collecting (such as water traps) the drained liquid effluent, located upstream of the opening connected to the gas suction means, to avoid excessive entrainment of liquid towards the gas suction means, these liquid entrainments being able to be detrimental to the proper functioning of the gas suction means.

[0110] Advantageously, the method according to the invention may comprise, after step B) and preferably after a drainage phase as described above, a phase of drying the granular medium, carried out by means of means for heating the granular medium. This drying phase allows accelerated drying compared to a drainage phase as described above which would be carried out over a sufficiently long time to result in the drying of the granular medium. According to one implementation of the invention, this phase of drying the granular medium can be carried out by placing the filter cartridge, which will have been previously removed from the enclosure of the system according to the invention, in a heating enclosure, such as for example a microwave oven or a conventional oven. According to another implementation of the invention, this phase of drying the granular medium can be carried out by connecting gas insufflation means to the system according to the invention so as to generate an ascending or descending flow of gas through the granular medium, and by preheating the gas before it enters the enclosure. The gas can for example be heated by means of a heat source (for example a heating resistor, a heat exchanger) located between the gas insufflation means and the opening to which the gas insufflation means are connected.According to this implementation, the gas insufflation means can be connected to the system according to the invention at the opening of the means for regeneration by gas suction of the granular medium located above the granular medium, or at the opening of the means for evacuating the liquid effluent. Preferably, the gas used is a gas with a low water vapor content. According to one design of this implementation of the invention, the gas insufflation means can consist of a hair dryer. According to another embodiment of the invention, this phase of drying the granular medium can be carried out by percolating a hot liquid through the granular medium, or by heating the walls of the granular medium. The heating of the wall of the granular medium can be carried out, for example, by placing a heating resistor in contact with the wall of the filtration cartridge, or in the wall of the filtration cartridge itself.Advantageously, the granular medium is heated to temperatures between 30 and 90°C, preferably at least between 50 and 70°C. Such temperatures are capable of allowing the removal of more than 95% of the residual moisture present in the granular medium at the start of drying, within a period of less than 30 minutes, or even less than 10 minutes.

[0111] Advantageously, the method according to the invention can comprise at least one step of pretreatment of the liquid effluent, before its arrival on the granular medium (and therefore before step B).

[0112] According to one implementation of the invention, this preliminary step of pretreatment of the liquid effluent may comprise a sub-step of injecting at least one flocculating agent into the liquid effluent, for example by means of the means for injecting a flocculating agent as described above. A flocculating agent makes it possible to promote the agglomeration of the smallest fibers or other particles contained in the draining liquid, which facilitates their separation from the liquid effluent as they pass through the granular medium. For example, a flocculating agent may be used in the form of mineral salts with polyvalent cations such as alumina sulfate or ferric chloride, activated silica, or natural organic polyelectrolytes (starches, alginate) or synthesis (high molecular weight polymers such as polycrylamides or polyvinylamines). The injection of a flocculating agent will preferably be carried out at a low content, generally between 1 and 20 ppm of the drain liquid, and a device will preferably be used to promote the mixing of said flocculating agent in the liquid effluent. Flocculation is particularly interesting in the case where the microfibers or particles present have dimensions of the order of a micron or less than a micron. The flocculating agent can also be injected at the same time as the detergent intended for washing textiles, and possibly be combined with the detergent.

[0113] Alternatively or cumulatively, the preliminary step of pretreatment of the liquid effluent may comprise a sub-step of settling the liquid effluent, carried out for example by means of a settling chamber arranged upstream of the enclosure of the system according to the invention as described above. A settling chamber allows the sedimentation by gravity of the largest fibers. Such a preliminary settling sub-step may make it possible to capture the largest fibers and to limit the excessively rapid clogging of the granular medium, which will then be able to capture more effectively the majority of the smallest fibers.

[0114] Alternatively or cumulatively, the preliminary step of pretreatment of the liquid effluent may comprise a sub-step of passing the liquid effluent into a cyclonic separation chamber (such as a hydrocyclone) arranged upstream of the enclosure of the system according to the invention as described above. A cyclonic separation chamber (such as a hydrocyclone) makes it possible to separate the largest fibers by inducing vorticity and a centrifugal force field promoting separation. Such a preliminary sub-step may make it possible to capture the largest fibers and limit the excessively rapid clogging of the granular medium, which will then be able to capture the majority of the smallest fibers more effectively.

[0115] Advantageously, the preliminary step of pretreatment of the liquid effluent may comprise a sub-step of injecting at least one flocculating agent into the liquid effluent, followed by a sub-step of settling the liquid effluent and / or a sub-step of cyclonic separation. The flocculating agent makes it possible to promote the agglomeration of the smallest fibers, which will increase the efficiency of the sub-step of settling and / or cyclonic separation, before the passage of the liquid effluent, already discharged of the largest fibers and / or fiber agglomerates, into the granular medium.

[0116] Advantageously, the method according to the invention may further comprise at least one step subsequent to the regeneration step, consisting of the collection of the microfibers resulting from the regeneration phase, for example by means of a cyclonic chamber or a filter (for example a membrane) placed downstream of the means for regeneration by gas suction of said granular medium described above.

[0117] Thus, the system and method according to the invention make it possible to filter the microfibers from a liquid effluent, resulting from the washing, rinsing and / or spinning phases of a textile treatment device, with a capture efficiency of microfibers greater than 50 microns greater than at least 80%. The system and method according to the invention can be used over a long period, thanks to the possibility of regenerating the granular medium in which the microfibers can accumulate over time. In addition, the filter cartridge is easily regenerable thanks to connection means that are simple to manage for the user. Regeneration also makes it possible to recover the microfibers for later use.The modular and removable aspect of the system according to the invention makes it possible to change the filtration cartridge in the event of deterioration, for example when regeneration becomes ineffective (scaled granular medium for example), without having to change the entire filtration system.

[0118] The invention also relates to a filtration cartridge comprising a granular medium occupying a portion of the volume of the filtration cartridge as described according to any one of the embodiments above; the filtration cartridge being configured to be inserted and removably fixed to the regenerable system for the filtration of microfibers contained in a liquid effluent according to any one of the embodiments described above.

[0119] The invention also relates to a textile treatment device, such as a washing machine, comprising at least one regenerable system for the filtration of microfibers contained in a liquid effluent according to any one of the embodiments described above.

[0120] It goes without saying that the invention is not limited to the embodiments of the system and the method described and illustrated above as examples; on the contrary, it encompasses all the variant embodiments, as well as all the combinations of these embodiments, so as to combine their effects. Examples

[0121] The application example described below concerns an application of the microfiber filtration system and method according to the invention to an individual washing machine and to a commercial vacuum cleaner.

[0122] More precisely, the washing machine in this example has a washing capacity of 5 kg of laundry, and uses a maximum total quantity of water of 50 l for each wash. The wash water evacuation cycles during the different phases of the program vary depending on the user's choices, but the washing machine is characterized by the fact that the largest quantity that can be evacuated during a phase during washing is 15 l, with the liquid evacuated in 3 minutes. Between two washing machine drain cycles, the time is approximately 15 min minimum. The average fiber content in the drain water is around 0.02 g / l, corresponding to an average fiber release rate of 0.02% relative to the weight of washed laundry, and an average quantity of fibers to be collected by the filter at each wash of 1g on average for 5 kg of washed laundry.

[0123] The washing machine discharges the drain liquids through a drain point located at the base of the washing machine 5 cm from the ground. A connection point to the sewer system is available at a height of 15 cm above the washing machine drain point (i.e. 20 cm from the ground on which the washing machine rests).

[0124] For this application example, the filtration system according to the design described in [fig.2a] is connected to a washing machine drain pipe. The references cited below therefore correspond to those of [fig.2a]. For this application example, the enclosure is cylindrical, with an internal diameter of 25 cm and a height of 70 cm, and into which is inserted a filtration cartridge which is also cylindrical, with an external diameter of 25 cm and a height of 60 cm. The granular medium 1 is arranged over a height of 25 cm in the filtration cartridge 10. It is surmounted by a free volume with a height of 30 cm, the volume of which allows the accumulation of 15 l of liquid effluent. The lower face of the filtration cartridge is a grid with a mesh size of 0.15 mm. Between this grid and the base of the lower casing, a 50 mm empty space allows the liquid to be collected under the filtration cartridge.Granular medium 1 consists of sand with an average diameter of 0.5 mm, and such that 90% of the sand particles have a size between 0.3 and 0.7 mm. The average density of the sand grains is estimated at 2550 kg / m3. The porosity (interstitial space) of granular medium 1 is estimated at 41% of the granular volume after regeneration.

[0125] The system according to this application example is connected to the washing machine drain pipe at the opening 21, 22, located at a height of approximately 90 cm from the ground. The opening 31, 32 of the lower casing is therefore still located above the outlet of the washing machine drain, which makes it possible to connect this assembly to the usual wastewater drainage system, with a siphon and to discharge the filtered rinse liquid by gravity.

[0126] When the granular medium 1 is clean, just after regeneration, the characteristics of the bed allow filtration with a flow rate of 61 / min by creating a pressure drop of less than 2000 Pa, corresponding to a hydrostatic height of 20 cm less than the height of the free volume above the granular medium. As a result, filtration by percolation of the bed can be carried out in less than 4 min. When the granular medium 1 is clogged after accumulation of approximately 100 g of microfibers, the pressure drop has doubled and corresponds to approximately 4000 Pa, i.e. a hydrostatic height of 40 cm always lower than the height of the free volume 30. These characteristics ensure effective filtration of the drain liquid for around a hundred washes.

[0127] For this application example, the inner diameter of the opening 21, 22 is 30 mm, the inner diameter of the line of the commercial vacuum cleaner used is 31 mm, and the outer diameter of the drain line is 32 mm. In order to compensate for the differences in diameter, the connection of the opening 21, 22 to the drain line of the washing machine alternatively to the line of the commercial vacuum cleaner is configured as described respectively in Figures 3a and 3b.

[0128] After about a hundred washes, the washing machine drain pipe is disconnected from the opening 21, 22 and this opening 21, 22 is connected to a commercial vacuum cleaner (equipped with a disposable filter bag), making it possible to create a convective flow of ascending air through the granular medium 1, the air entering through the opening 31, 32. The vacuum cleaner can suck 30 l / s with a suction of 40 kPa. The fluidization speed of the particles is 19.5 cm / s. A minimum flow rate of 10 l / s is therefore required to fluidize the bed. The use of the vacuum cleaner which sucks 30 l / s therefore makes it possible to fluidize the bed at a speed corresponding to 3 times the minimum fluidization speed. The suction required to compensate for the pressure drop of the granular medium in the fluidized state is approximately 4000 Pa, which is much lower than the suction capacity of the vacuum cleaner. The bed is therefore well fluidized, which allows the microfibers to be evacuated towards the filter bag.At the end of regeneration, the suction is stopped and the sand particles sediment to reform the filter medium.

[0129] The system and method for filtering microfibers according to this design made it possible to eliminate between 80 and 90% of fibers with a length greater than about 50 microns.

[0130] The dimensions of the filtration system described in the application example could be reduced by optimizing the operating conditions of the washing machine, for example by considering more frequent emptying but of a smaller volume.

Claims

Claims

1. Regenerable system for filtering microfibers contained in a liquid effluent from a textile treatment device, comprising at least: an enclosure formed by, in the operating position, at least one upper casing (20) and one lower casing (30), a filtration cartridge (10) arranged inside said enclosure, means for supplying (21, 22) said liquid effluent into the enclosure comprising at least one opening (21, 22) arranged in said upper casing (20) of said enclosure and above said filtration cartridge (10), means for discharging (31, 32) said liquid effluent comprising at least one opening (31, 32) arranged in said lower casing (30) of said enclosure and below said filtration cartridge (10), means for assembling (25, 26, 35, 36) together in a removable manner at least said upper casings (20) and lower (30),characterized in that: - said filtration cartridge (10) comprises a granular medium (1) occupying a portion of the volume of said filtration cartridge, said granular medium being surmounted by a free volume (40); - said enclosure comprises means of connection (21, 22) to means of regeneration by gas suction of said granular medium (1), comprising at least said opening (21, 22) arranged in said upper casing (20) of said enclosure; - said means for supplying (21, 22) said liquid effluent and said means of connection (21, 22) to means of regeneration of said granular medium (1) by gas suction are configured to allow alternately a connection to a drain pipe of said textile treatment device and a connection to said means of regeneration by gas suction of said granular medium.,

2. System according to claim 1, wherein said filtration cartridge (10) comprises a conduit (15) arranged to short-circuit said granular medium (1) in the event of an accumulation of said liquid effluent above said granular medium, said conduit (15) of said filtration cartridge (10) being preferably provided with a deflector (16) in its upper part and / or a non-return valve (57) in its lower part.

3. The system of claim 2, wherein said conduit (15) of said filtration cartridge (10) further comprises a detector of liquid, preferably connected to an alarm.

4. System according to one of the preceding claims, wherein said free volume (40) above said granular medium represents at least 20% of the volume of said granular medium, preferably between 30 and 50% of the volume of said granular medium, and preferably is 40% of the volume of said granular medium.

5. System according to one of the preceding claims, in which said granular medium (1) comprises sand particles, crushed glass beads or raw glass beads, particles formed from natural or synthetic zeolite, from alumina, or from resins or plastic.

6. System according to one of the preceding claims, said granular medium (1) comprises particles of size between 0.1 mm and 2 cm for at least 80% by weight of said particles, preferably between 0.3 and 2.5 mm for at least 90% by weight of said particles.

7. System according to one of the preceding claims, in which a liquid distributor is arranged between said filtration cartridge (10) and said opening (21, 22) arranged in said upper casing (20) of said enclosure and / or a gas distributor is arranged between said filtration cartridge (10) and said opening (31, 32) of said means for discharging said liquid effluent.

8. System according to one of the preceding claims, in which at least said opening (21, 22) arranged in said upper casing (20) of said enclosure of said means for supplying said liquid effluent and of said means for connection to means for regenerating by gas suction said granular medium (1) has an internal diameter of at least 30 mm, preferably between 30 mm and 35 mm.

9. System according to one of the preceding claims, in which said means for supplying said liquid effluent and said means for connecting to means for regenerating by gas suction said granular medium comprise connectors.

10. Method for the filtration of microfibers contained in a liquid effluent from a textile treatment device, said method being implemented by means of a regenerable system for the filtration of microfibers according to any one of the preceding claims, characterized in that said method comprises at least the following steps A) said means for supplying said liquid effluent are connected to a drain pipe of said textile treatment device; B) at least one phase of filtration of said microfibers is carried out comprising at least the passage of said liquid effluent through said granular medium by means of at least said means for supplying said liquid effluent, and said filtered liquid effluent is evacuated from said microfibers by means of said means for evacuating said liquid effluent. C) said means for supplying said liquid effluent are disconnected from said drain pipe of said textile treatment device, and said connection means are connected to means for regenerating the granular medium by gas suction to means for regenerating the granular medium by gas suction; D) a phase of regeneration by gas suction of said granular medium is carried out.

11. A method according to claim 10, wherein step B) is repeated between 50 and 150 times, preferably about 100 times, before carrying out steps C) and D).

12. Method according to one of claims 10 to 11, comprising, prior to step B), a step of pretreatment of said liquid effluent, said step of pretreatment of said liquid effluent comprising at least one injection of at least one flocculating agent into said liquid effluent and / or at least one decantation of said liquid effluent and / or at least one cyclonic separation of said liquid effluent.

13. Method according to one of claims 10 to 12, comprising, prior to step C), a phase of draining said granular medium, carried out by connecting said gas suction means at least to the opening of said means for discharging said liquid effluent, and / or a phase of drying said granular medium, carried out by means of means for heating said granular medium.

14. A filtration cartridge comprising a granular medium (1) occupying a portion of the volume of said filtration cartridge (10) and being surmounted by a free volume (40), said filtration cartridge being configured to be inserted and removably fixed to the regenerable system for the filtration of microfibers contained in a liquid effluent according to any one of claims 1 to 9.

15. Textile treatment device, comprising at least one regenerable system for the filtration of microfibers contained in an effluent liquid according to any one of claims 1 to 9.

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