Pre-filter and filtering method

Abstract

The invention relates to a pre-filter comprising a filtering part comprising a treated water outlet means, a pre-filter body arranged to house the filtering part, a base arranged to receive the pre-filter body, and comprising a supply opening for water to be treated, a closure system present on the pre-filter body, suitable for being housed in the base and for closing the supply opening for water to be treated, the pre-filter also comprising mutual connection means arranged to assemble the pre-filter, and a control means controlling the filtering part and the connection means so as to be able to assemble or disassemble the pre-filter while closing or opening the water supply opening.

Description

[0001] PRE-FILTER AND FILTRATION METHOD

[0002] technical field

[0003] The present invention relates to a pre-filter for treating wastewater. The present invention also relates to a wastewater settling tank comprising a pre-filter for treating wastewater according to the present invention.

[0004] The present invention also relates to a method for treating wastewater by implementing the pre-filter according to the present invention.

[0005] The present invention also relates to a method for settling wastewater in a settling tank by implementing the pre-filter according to the present invention.

[0006] Previous art

[0007] Prefilters for treating wastewater have been known since prior art. A prefilter is particularly well-suited for all non-collective sanitation systems with septic tanks or all-water tanks. In this case, the prefilter is generally connected to the outlet (internally or externally) of a septic tank or all-water tank and reduces the organic load and / or suspended solids load of the water leaving the tank. In this way, the prefilter prevents the migration of matter to the treatment devices located downstream of the all-water tank, thus preventing the accumulation of matter in these devices that could cause blockages.

[0008] The pre-filter requires regular maintenance to prevent clogging due to the accumulation of organic matter and suspended solids. This maintenance consists of cleaning, which can be tedious depending on the pre-filter, and during which, for example, minimum protective measures must be used to protect the operator: gloves, goggles, etc.

[0009] Although different types of pre-filters exist on the market, there is still a need for a robust and durable pre-filter that is compatible with regular handling, easy to use and maintain, compact, and easy to manufacture industrially.

[0010] Objectives of the invention

[0011] The present invention aims to overcome the drawbacks of the prior art, particularly those described above. Specifically, the present invention proposes to provide a pre-filter that is very easy to install and maintain, while remaining robust over a long period despite handling, such as regular maintenance.

[0012] The present invention also provides a pre-filter that is easy to manufacture industrially.

[0013] The present invention also provides a compact pre-filter so that it can be easily placed in various water treatment devices.

[0014] Summary of the invention

[0015] To achieve the aforementioned objectives, the invention provides a pre-filter for treating wastewater comprising suspended matter in a liquid phase, and producing treated water consisting of said wastewater depleted of at least a portion of the suspended matter, said pre-filter comprising:

[0016] - a filtering part comprising a basal part, a filtering side wall and a head part, said filtering side wall being at least partially formed of a filtering medium and arranged to retain said suspended matter in an external part of said filtering side wall and to allow collection of said treated water in a lumen of said filtering part and comprising a means of outlet of said treated water in fluidic communication with said lumen,

[0017] - a pre-filter body comprising a filtration volume delimited by an external wall, said external wall comprising a treated water outlet orifice, said pre-filter body being arranged to house said filtering part and so that the treated water outlet orifice is capable of being in fluidic communication with said treated water outlet means,

[0018] - a base arranged to receive said pre-filter body, said base being provided with a side wall and a bottom wall, said side wall comprising an orifice for supplying water to be treated arranged to be in fluidic communication with said filtration volume,

[0019] - a sealing system present on the body of the pre-filter, suitable for being housed in said base and for sealing said wastewater inlet orifice, said pre-filter further comprising a first connection means on said filtering part and a second connection means on the pre-filter body or on the base, said first connection means and said second connection means being mutual connection means arranged to assemble said pre-filter, - a control means in operational connection with said filtering part, and with said first and second connection means, said control means being arranged to ensure the connection between said filtering part and said pre-filter body or between said filtering part and said base, and to effect a closing or opening of said wastewater inlet orifice by a relative movement between said pre-filter body and said base,wherein said sealing system is a rotary sealing system arranged to open said water supply orifice to be treated, in at least one open position, while simultaneously assembling said pre-filter by said first and second connection means controlled by said control means, or to close said water supply orifice to be treated, in at least one closed position, while simultaneously disassembling said pre-filter by said first and second connection means controlled by said control means.

[0020] Indeed, a pre-filter according to the present invention, combining a base arranged to receive a pre-filter body, the pre-filter body being arranged to house a filter element and comprising a closure system, provides a compact system comprising few components, thus facilitating its industrialization. Furthermore, the pre-filter includes a first connection means on the filter element and a second mutual connection means to the first on the pre-filter body or on the base, allowing the pre-filter to be assembled or disassembled. A control means, operationally connected to the filter element and to said first and second connection means, allows the wastewater inlet to be opened (open position) or closed (closed position) by rotation.This also allows the filter element to be removed for maintenance while simultaneously sealing the inlet, preventing wastewater from contaminating the pre-filter body. After maintenance, when starting the pre-filter, the filter element can be easily assembled to the base and / or body of the pre-filter by rotating it using the first and second connection points, while still allowing the inlet to be opened. This makes handling the pre-filter very simple during maintenance and / or cleaning, ensuring easy commissioning by minimizing manual intervention. Furthermore, the arrangement of the base, the rotating sealing system, the pre-filter body, and the filter element provides a compact pre-filter that can be easily integrated into various water treatment systems.Other embodiments of the pre-filter according to the present invention are indicated in the attached claims.

[0021] The present invention also relates to a wastewater settling tank comprising:

[0022] - a settling tank designed to decant wastewater,

[0023] - at least one wastewater inlet and at least one settled water outlet, said at least one wastewater inlet and said at least one settled water outlet being in fluidic connection with said settling tank,

[0024] - a pre-filter according to the present invention connected to said at least one outlet of the decanted water so that the decanted water passes through said pre-filter upon exiting said decantation tank,

[0025] - an opening, for example a manhole, arranged to allow access to said at least one wastewater inlet and / or to said at least one settled water outlet.

[0026] Other embodiments of the settling tank comprising a pre-filter according to the present invention are indicated in the attached claims.

[0027] The present invention also relates to a method for treating wastewater by implementing the pre-filter according to the present invention, the method comprising the steps of: positioning, by said control means, said rotary shutter system in an open position so as to open said feed orifice, an inlet of the water to be treated through said feed orifice, a passage of the water to be treated into said filtration volume, a filtration of the water to be treated by a passage of the water to be treated through said filtering side wall of said filtering part so as to collect treated water in said lumen of said filtering part, an outlet of the treated water by said outlet means of said treated water.

[0028] Other embodiments of the method for treating wastewater by implementing the pre-filter according to the present invention are indicated in the attached claims.

[0029] The present invention also relates to a method for settling wastewater in a settling tank comprising the pre-filter according to the present invention: a wastewater inlet into a settling tank by at least one wastewater inlet, settling of the wastewater to give settled water, filtration of the settled water through said pre-filter according to the present invention connected fluidically to at least one filtered water outlet, said filtration being arranged to give filtered water, an outlet of the filtered water through said at least one filtered water outlet.

[0030] Other embodiments of the method for settling wastewater in a settling tank comprising the pre-filter according to the present invention are indicated in the attached claims.

[0031] The present invention also relates to a use of the pre-filter according to the present invention so as to have an optimal reduction of the suspended matter of the water to be treated compared to the treated water, for example a reduction of at least 50% of the suspended matter of the water to be treated compared to the treated water, preferably at least 60%, 70%, 80%, or even 90% (suspended matter contained in the treated water exiting the outlet compared to the water to be treated entering the feed outlet).

[0032] Other embodiments of the use of the pre-filter according to the present invention are indicated in the attached claims.

[0033] The present invention also relates to a purification tank intended for the treatment of wastewater, said purification tank comprising: a wastewater settling tank according to the present invention, a filtration chamber comprising at least one water inlet, in fluidic communication with said settled water outlet of said wastewater settling tank, and at least one filtered water outlet, between which extends a filter bed comprising a filtering material, said filter bed having an upstream section and a downstream face along a fluidic direction of filtration.

[0034] Other embodiments of the wastewater treatment tank according to the present invention are indicated in the attached claims.

[0035] Detailed description of an embodiment of the invention

[0036] Other features and advantages of the present invention will be derived from the following non-limiting description, with reference to the drawings and examples. Figures 1, 2A, and 2B show a schematic representation of a first embodiment of the pre-filter according to the present invention.

[0037] Figure 2C shows a diagram of a second embodiment of the pre-filter according to the present invention

[0038] Figure 3 shows a diagram of another embodiment of the pre-filter according to the present invention.

[0039] Figure 4 shows a diagram (top view) of an embodiment of the rotary pre-filter shuttering system according to the present invention.

[0040] Figure 5 shows a diagram of another embodiment of the pre-filter according to the present invention illustrating an assembly between the filtering part and the pre-filter body.

[0041] In the figures, identical or analogous elements bear the same references.

[0042] In this description and the claims, it is understood that the terms "a," "an," or "the" mean "at least one" and are not to be limited to "only one," unless explicitly stated otherwise. Furthermore, where a range of values ​​is given, the endpoints are included. Finally, all integral and subdomain values ​​within a numerical range are expressly included as if explicitly stated.

[0043] In the context of the present invention, preferably, the term "said first connection means and said second connection means being mutual connection means arranged to assemble said pre-filter" means that the first and second mutual connection means provide a point of support, or allow them to interlock so as to assemble at least the filter element and the base or the filter element and the pre-filter body. Advantageously, the first and second mutual connection means allow them to interlock so as to assemble and reversibly secure, by means of a fastener, at least the filter element and the base or the filter element and the pre-filter body.

[0044] In the context of the present invention, preferably, the term "relative movement between said pre-filter body and said base" means (i) movement of the base relative to the pre-filter body, said pre-filter body remaining substantially in a fixed position, or (ii) movement of the pre-filter body relative to the base, said base remaining substantially in a fixed position. Figures 1 and 2A, and 2B illustrate a first embodiment of the pre-filter 1 according to the present invention. Figure 2A illustrates an exploded schematic representation of the pre-filter according to the present invention.

[0045] The pre-filter 1 for the treatment of wastewater comprising suspended matter in a liquid phase, and forming treated water consisting of said wastewater depleted of at least a part of the suspended matter, the pre-filter comprising: a filtering part 4 including a basal part 4.2, a filtering side wall 4.1 and a head part 4.3, the filtering side wall 4.1 being at least partially formed of a filtering medium and arranged to retain said suspended matter in an external part of the filtering side wall 4.1 and to allow collection of said treated water in a lumen of the filtering part 4.1 and including an outlet means 4.4 of said treated water in fluidic communication with said lumen, a pre-filter body 3 comprising a filtration volume delimited by an external wall, the external wall including an outlet 6 for treated water,said pre-filter body 3 being arranged to house the filter element 4 and such that the treated water outlet 6 is in fluidic communication with said treated water outlet 4.4, a base 2 arranged to receive said pre-filter body 3, said base 2 being provided with a side wall and a bottom wall, said side wall comprising a water inlet 5 for the water to be treated arranged to be in fluidic communication with said filtration volume, a closure system 10 present on the filter body 3, suitable for being housed in said base 2 and for closing said water inlet 5, said pre-filter 1 further comprising a first connection means 8 on the filter element 4 and a second connection means on the pre-filter body or on the base 8', the first connection means 8 and the second connection means 8' being mutual connection means arranged to assemble the pre-filter 1,a control means 7 in operational connection with the filter part 4, and with said first and second connection means 8, 8', the control means 7 being arranged to control the connection between the filter part 4 and the pre-filter body 3 or between the filter part 4 and the base 2, and to achieve a closing or opening of the wastewater inlet 5 by a relative movement between the pre-filter body 3 and the base 2, in which the closing system is a rotary closing system arranged to open the wastewater inlet 5, in at least one open position, while simultaneously assembling the pre-filter 1 by said first and second connection means 8, 8' controlled by the control means 7, or to close the wastewater inlet 5, in at least one closed position, while simultaneously disassembling the pre-filter 1 by said first and second connection means 8,8' controlled by the control means 7.,

[0046] Figure IA illustrates the pre-filter according to the invention in which the rotary sealing system 10 (see exploded view in Figure 2A) comprises at least one open position in which the first and second connection means 8, 8' connect the filtering part 4 to the base 2 and in which the feed orifice 5 is in fluidic connection with the filtration volume of the pre-filter body 3 so as to ensure a passage of the water to be treated through the feed orifice 5 into the pre-filter body 3.

[0047] Figure IB illustrates the pre-filter according to the invention in which the rotary sealing system 10 (see exploded view in Figure 2A) comprises at least one closed position in which the filtering part 4 is disconnected from the base 2 and in which the feed orifice 5 is sealed (closed) by a wall 10 of the rotary sealing system (see Figure 2A) so as to prevent the passage of water to be treated through said feed orifice into the filtration volume of the pre-filter body 3.

[0048] Figure 2B illustrates a schematic representation of the prefilter according to the invention illustrated in Figure 2A in which the filtering part 4 is present in the prefilter body 3.

[0049] Preferably, the base (2) includes a third connection means (9) and the pre-filter body (3) includes a fourth connection means (9'), the third connection means (9) and the fourth connection means (9') being mutual connection means arranged to assemble and fix, preferably fix reversibly, the base (2) to the pre-filter body (3).

[0050] Alternatively, or preferably, Figure 2C illustrates that the basal section 4.2 of the filter section 4 is inclined, such that the basal section 4.2 slopes from the center to the periphery, with the lowest point of the basal section located in a central area and the periphery of the basal section located at a higher level than the central area. This helps to limit the settling and obstruction of suspended matter in the basal section of the filter section. Preferably, the basal section 4.2 of the filter section 4 has one or more openings, such as slots, to prevent sludge accumulation in the lower part (basal section 4.2) of the filter section.

[0051] Preferably, the first connection means on the filter element is located on a distal end of said filter element, preferably on the basal part of the filter element. Preferably, the second connection means is located on the base projecting from an inner face of said bottom wall. Preferably, the first and second connection means are mutually compatible and arranged to assemble said pre-filter so as to connect the filter element to the base.Preferably, the first connection means on the filtering part is located on a distal end of said filtering part, preferably on the basal part of the filtering part, the second connection means is located on the base projecting from an inner face of said bottom wall, and the first connection means and the second connection means being mutual connection means arranged to assemble the pre-filter so as to connect the filtering part to the base.

[0052] Preferably, in at least one open position, the treated water outlet 6 is in fluidic communication with said treated water outlet means 4.4.

[0053] Preferably, the pre-filter includes a first connection means on the filtering part and a second connection means on the pre-filter body and on the base, the first connection means and the second connection means on the pre-filter body and on the base being mutual connection means arranged to assemble the pre-filter.

[0054] Preferably, the first connection means on the filter section comprises a connection means on a distal end of said filter section, preferably on the basal part of the filter section, and a connection means on the head part of the filter section. Preferably, the second connection means on the base comprises a connection means projecting from an inner face of said bottom wall of the base, and the second connection means on the pre-filter body comprises a connection means on an upper part of the pre-filter body such as to be a mutual connection means with the connection means on the head part of the filter section. Preferably, the connection means on a distal end of said filter section, preferably on the basal part of the filter section, is a mutual connection means with the connection means projecting from an inner face of said bottom wall of the base.Preferably, the connection means on the head part of the filter part and said connection means on an upper part of the pre-filter body are mutual and arranged to lock the filter part to the pre-filter body.

[0055] Preferably, said at least one open position is characterized by the fact that said first and second means of connection connect the filtering part to the base or body of the pre-filter so as to assemble the pre-filter, and by the fact that the water-to-treatment supply orifice is open and is in fluidic connection with said filtration volume of the pre-filter body so as to ensure a passage of the water-to-treatment through the water-to-treatment supply orifice into the pre-filter body.

[0056] Preferably, said at least one closed position is characterized by the fact that said first and second means of connection are disconnected so as to disassemble the filter part from the base or body of the pre-filter, and by the fact that the water supply orifice to be treated is closed by a wall of the sealing system so as to prevent a passage of the water to be treated through the water supply orifice to be treated into the body of the pre-filter.

[0057] Preferably, the filtering part has a substantially cylindrical or substantially rectangular shape.

[0058] Preferably, the control means 7 is a manual control means, more preferably a rotary and manual control means, for example a handle, which is located on the filtering part, the control means being arranged to ensure the passage from an open position to a closed position and from a closed position to an open position.

[0059] Preferably, the control means in operational connection with the filter part 4, and with said first and second connection means 8 is arranged to drive, by rotation, said filter part 4 and said base 2 so as to create a rotation between (i) said filter part 4 and said base 2, and (ii) the pre-filter body 3, said rotation being able to position the feed orifice 5 facing the closing system so that the closing system covers the feed orifice 5 allowing this feed orifice 5 to be closed, to position the feed orifice 5 in a position that does not face the closing system so that the closing system does not cover the feed orifice 5, or only partially covers it, allowing this feed orifice 5 to be opened and to have fluidic communication with the filtration volume of the pre-filter body.

[0060] Preferably, the manual control is located on a cover connected to the filter section, with the cover allowing the upper part of the pre-filter to be closed. Indeed, a manual control, such as a handle located on a cover of the pre-filter section, allows for easy manipulation of the pre-filter; a simple rotation of the filter section causes the pre-filter body to rotate relative to the base, or vice versa.

[0061] Figure 3 illustrates another embodiment of the prefilter according to the invention in which the prefilter 1 further comprises an inlet deflector 11 for the water to be treated which is located on the base 2, preferably on the bottom wall of the base 2, said deflector 11 being in fluidic connection with the inlet port 5 for the water to be treated, the deflector 11 being arranged to decrease the velocity of the inlet flow of the water to be treated and to reduce the entrainment of sludge towards the prefilter body 3.

[0062] Preferably, the inlet deflector 1 of the water to be treated is arranged so that the inlet of the water to be treated into the deflector forms an angle with respect to a longitudinal axis (upstream-downstream) of the pre-filter 1 (section axis x3-x4 in Figure 4), preferably an angle between 60° and 120°, preferably an angle of about 90° (longitudinal axis of the feed orifice in the base (section axis xl-x2) with respect to the longitudinal axis of the pre-filter (section axis x3-x4)).

[0063] Preferably, the deflector 11 has a conical shape having a central part raised in a downstream direction relative to a peripheral part of the deflector, the conical deflector being arranged to evacuate suspended matter escaping from said filtering part.

[0064] Preferably, the rotary shutter system (see figure 4) comprises two open positions and two closed positions arranged so that the control means 7 enables the filter part and base to be rotated relative to the pre-filter body or the pre-filter body and filter part relative to the base in order to ensure a relative displacement of the shutter system relative to the base ensuring the passage from an open position to a closed position and from a closed position to an open position, preferably by making one turn of the control means, causing a quarter turn of the rotary shutter system.Indeed, switching from an open to a closed position, and vice versa, with a quarter turn of the shutter system, while simultaneously controlling the connection between the filter element and the base or between the filter element and the pre-filter body using the first and second connection methods, allows for very easy handling of the pre-filter. This greatly facilitates its maintenance and / or installation. Preferably, the rotary shutter system comprises two opposite closed positions and two opposite open positions. Preferably, one closed position is adjacent to one open position. Preferably, the side wall of the pre-filter base comprises two inlets for the water to be treated; more preferably, these two inlets are opposite each other.

[0065] Figure 5 illustrates another embodiment of the prefilter according to the present invention, showing an assembly between the filter element and the prefilter body in which the connection means 12 on the head portion of the filter element and the connection means 13 on an upper portion of the prefilter body are mutually compatible and arranged to lock the filter element to the prefilter body. Figure 5A illustrates an open position in which the filter element is assembled and fixed to the prefilter body; in this open position, the inlet port for the water to be treated is also open and in fluidic communication with the filtration volume.Figure 5B illustrates a closed position in which the filter part is not fixed to the pre-filter body; in this closed position, the water supply orifice to be treated is also closed, sealed, by the sealing system preventing fluidic communication between the supply orifice and the filtration volume.

[0066] Preferably, the filter part 4 is surrounded by a protective cover, the cover being arranged to reduce fouling of the filter part.

[0067] Preferably, the filtering part 4 is in the form of a filter cartridge inserted into the pre-filter body 3.

[0068] Preferably, the filter section 4 is a lamellar filter. More preferably, a lamellar filter cartridge. Preferably, the lamellar filter cartridge has filter slots with a cumulative slot length of between 20 m and 80 m, preferably between 30 m and 60 m, more preferably around 40 m. Preferably, each filter slot has a slot width of between 0.5 and 3 mm.

[0069] Preferably, the treated water outlet 6 is located in a high part of the pre-filter body 3 and the treated water inlet 5 is located in the base (lower part) of the pre-filter, such that on a vertical axis relative to the base, the outlet 6 is located above the inlet 5.

[0070] Preferably, at least the base of the pre-filter, the pre-filter body, and the sealing system are made of synthetic polymer, for example, thermoplastic polymers such as polyvinyl chloride, polypropylene, or acrylonitrile butadiene styrene. Indeed, a synthetic polymer offers: high resistance to wastewater with a pH generally between 5.5 and 9.5; resistance to corrosion from gases released by wastewater, particularly hydrogen sulfide (H2S), carbon dioxide (CO2), methane (CH4), etc.; and non-brittle structural strength over a very long period, even under frequent handling.

[0071] Preferably, in the wastewater settling tank according to the present invention, in operational mode, the water supply orifice to be treated is submerged and the treated water outlet orifice is located above the water level present in the settling tank, the treated water outlet orifice being located above the water supply orifice to be treated along a vertical axis (for example x3-x4 cutting axis) relative to the bottom of the settling tank.

[0072] Preferably, in operational mode, an area of ​​the filtering part of the pre-filter is above the water level to allow air to pass through.

[0073] Preferably, the pre-filter according to the invention is located inside the settling tank and is connected to at least one of the settled water outlets so that the settled water passes through the pre-filter upon exiting the settling tank. Alternatively, the pre-filter according to the invention is located outside the settling tank and is connected to at least one of the settled water outlets so that the settled water passes through the pre-filter upon exiting the settling tank.

[0074] Preferably, the settling tank according to the present invention comprises several pre-filters according to the invention, for example at least 2, at least 3 or at least 4 pre-filters, wherein the pre-filters are arranged

[0075] (i) in parallel, each pre-filter being connected to the settled water outlet so that the settled water passes through one of the pre-filters upon exiting the settling tank, or (ii) in series, in which at least one pre-filter is connected to the settled water outlet, or

[0076] (iii) in parallel and in series, wherein at least one pre-filter is connected to the outlet of the decanted water.

[0077] Preferably, in the settling tank according to the present invention, at least one wastewater inlet is located in a central area of ​​said settling tank. Preferably, the pre-filter according to the invention is located in the central area of ​​the settling tank.

[0078] Preferably, the side wall of the pre-filter base comprises two opposing feed ports. Preferably, in the settling tank according to the present invention, in operational mode, the two opposing feed ports are both arranged to be opposite to the direction of the wastewater flow originating from at least one of the wastewater inlets of the settling tank. This prevents short circuits in the wastewater flow through the settling tank and thus optimizes the flow path, promoting settling within the tank.

[0079] Preferably, in operational mode, the outlet 6 is located above the water level in the settling tank, and the inlet 5 is immersed in the settling tank. More preferably, the outlet is located above the water level in the settling tank, and the inlet is immersed, with the outlet located at a maximum of 60 cm (measured on a vertical axis relative to the maximum sludge level), or more favorably, a maximum of 45 cm above the inlet (measured on a vertical axis relative to the maximum sludge level). Preferably, the wastewater treatment method according to the present invention further comprises a pre-filter maintenance step at regular intervals, the maintenance step comprising: actuation of said control means, preferably by a quarter turn of said control means,in order to close said water supply orifice to be treated, in at least one closed position, while simultaneously disassembling said pre-filter by said first and second connection means, an extraction of said filter part from said pre-filter body, a cleaning and / or maintenance of said filter part, a reinstallation, after cleaning and / or maintenance, of said filter part in said pre-filter body allowing reassembly of said filter part with said base, an actuation of said control means, preferably by a quarter turn in the opposite direction to said quarter turn of said control means, in order to open said water supply orifice to be treated, in at least one open position.

[0080] Preferably, the method for settling wastewater in a settling tank by implementing the pre-filter according to the present invention further comprises, after the entry of wastewater into a settling tank by at least one wastewater inlet, a separation of the incoming wastewater flow into two circulating water flows, said two circulating water flows being directed towards a peripheral area of ​​said settling tank and arranged to ensure settling of the wastewater, and / or an orientation of the incoming wastewater flow towards a peripheral area of ​​said settling tank.

[0081] Preferably, in the wastewater treatment tank according to the present invention, the filter material of the filter bed is a plant-based filter material comprising pieces of wood or plant fibers forming a population of pieces, said population of pieces being thermally transformed at a temperature between 150°C and 300°C forming a population of thermally stabilized pieces, for example a population of roasted pieces.

[0082] It is understood that the present invention is in no way limited to the embodiments described above and that many modifications can be made to it without departing from the scope of the attached claims.

Claims

DEMANDS 1. Prefilter (1) for the treatment of wastewater comprising suspended matter in a liquid phase, and forming treated water consisting of said wastewater depleted of at least part of the suspended matter, said prefilter comprising: - a filtering part (4) comprising a basal part (4.2), a filtering side wall (4.1) and a head part (4.3), said filtering side wall (4.1) being at least partially formed of a filtering medium and arranged to retain said suspended matter in an external part of said filtering side wall (4.1) and to allow collection of said treated water in a lumen of said filtering part and comprising an outlet means (4.4) of said treated water in fluidic communication with said lumen, - a pre-filter body (3) comprising a filtration volume delimited by an external wall, said external wall comprising an outlet orifice (6) for treated water, said pre-filter body (3) being arranged to house said filtering part (4) and so that the outlet orifice (6) for treated water is in fluidic communication with said outlet means (4.4) for said treated water, - a base (2) arranged to receive said pre-filter body (3), said base (2) being provided with a side wall and a bottom wall, said side wall comprising a water supply orifice (5) for the water to be treated arranged to be in fluidic communication with said filtration volume, - a sealing system (10) present on the pre-filter body (3), suitable for being housed in said base (2) and for sealing said water supply orifice (5), said pre-filter (1) further comprising a first connection means (8) on said filtering part (4) and a second connection means on the pre-filter body or on the base (8'), said first connection means (8) and said second connection means (8') being mutual connection means arranged to assemble said pre-filter (1), - a control means (7) in operational connection with said filtering part (4), and with said first and second connection means (8, 8'), said control means (7) being arranged to control the connection between said filtering part (4) and said pre-filter body (3) or between said filtering part (4) and said base (2), and to effect a closing or opening of said wastewater inlet orifice (5) by a relative movement between said pre-filter body (3) and said base (2), wherein said sealing system (10) is a rotary sealing system arranged to (i) open said water supply orifice (5) to be treated, in at least one open position, while simultaneously assembling said pre-filter (1) by said first and second connection means (8, 8') controlled by said control means (7), or (ii) close said water supply orifice (5) to be treated, in at least one closed position, while simultaneously disassembling said pre-filter (1) by said first and second connection means (8, 8') controlled by said control means (7).

2. Prefilter for treating wastewater according to claim 1, wherein said rotary sealing system comprises two open positions and two closed positions arranged so that the control means (7) enables a rotation of the filter part (4) and the base (2) relative to the prefilter body (3) or of the prefilter body (3) and the filter part (4) relative to the base (2) so as to ensure a relative displacement of the sealing system (10) relative to the base (2) ensuring the passage from an open position to a closed position and from a closed position to an open position, preferably by making a quarter turn of the control means (7).

3. Prefilter for treating wastewater according to claim 1 or claim 2, wherein said base (2) comprises a third connection means (9) and said prefilter body (3) comprises a fourth connection means (9'), said third connection means (9) and said fourth connection means (9') being mutual connection means arranged to assemble and fix, preferably fix reversibly, said base (2) to said prefilter body (3).

4. Prefilter for treating wastewater according to any one of the preceding claims, wherein the control means (7) is a manual control means, for example a handle, located on said filtering part (4), said control means (7) being arranged to ensure the passage from said at least one open position to said at least one closed position and from said at least one closed position to said at least one open position.

5. Prefilter for treating wastewater according to any one of the preceding claims, further comprising an inlet deflector (11) for the water to be treated located on said base (2), preferably on the bottom wall of said base, said deflector (11) being in fluidic connection with said inlet orifice (5) for the water to be treated, said deflector (11) being arranged to decrease the velocity of the inlet flow of the water to be treated and to reduce the entrainment of sludge towards said prefilter body (3).

6. Prefilter for treating wastewater according to claim 5, wherein said deflector (1 1 ) has a conical shape having a central part raised in a downstream direction relative to a peripheral part of said deflector (1 1 ), said deflector (1 1 ) in conical form being arranged to evacuate suspended matter escaping from said filtering part (4).

7. Prefilter for treating wastewater according to any one of the preceding claims, wherein said filtering part (4) is surrounded by a protective casing, said casing being arranged to reduce fouling of said filtering part (4).

8. Prefilter for treating wastewater according to any one of the preceding claims, wherein said base (2), said prefilter body (3), and said sealing system (10) are made of synthetic polymer, for example thermoplastic polymers such as polyvinyl chloride, polypropylene, acrylonitrile butadiene styrene.

9. Wastewater settling tank comprising: - a settling tank designed to decant wastewater, - at least one wastewater inlet and at least one settled water outlet, said at least one wastewater inlet and said at least one settled water outlet being in fluidic connection with said settling tank, - a pre-filter (1) according to any one of the preceding claims connected to said at least one outlet of the decanted water so that the decanted water passes through said pre-filter when exiting said settling tank, - an opening, for example a manhole, arranged to allow access to said at least one wastewater inlet and / or to said at least one settled water outlet.

10. Settling tank according to claim 9, wherein, in operational mode, said outlet orifice is located above the water level present in said settling tank and said inlet orifice is immersed in said settling tank, said outlet orifice being located above said inlet orifice along a vertical axis with respect to the bottom of said settling tank.

1. Settling tank according to claim 9 or claim 10, wherein, in operational mode, an area of ​​said filtering part of said pre-filter is above the water level so as to permit the passage of air.

12. Settling tank according to any one of claims 9 to 11, comprising several pre-filters (1) according to any one of claims 1 to 8, for example at least 2, at least 3 or at least 4 pre-filters, wherein said pre-filters are arranged (i) in parallel, each pre-filter (1) being connected to the settled water outlet so that the settled water passes through one of the pre-filters (1) upon exiting the settling tank, or (ii) in series, wherein at least one pre-filter (1) is connected to the outlet of the settled water, or (iii) in parallel and in series, wherein at least one pre-filter (1) is connected to the outlet of the decanted water.

13. Method for treating wastewater by implementing said pre-filter (1) according to any one of claims 1 to 8, said method comprising the steps of: a positioning, by said control means, of said rotary shutter system in an open position so as to open said supply orifice, an inlet of the water to be treated through said supply orifice, a passage of the water to be treated into said filtration volume, a filtration of the water to be treated by a passage of the water to be treated through said filtering side wall of said filtering part so as to collect treated water in said lumen of said filtering part, an outlet of the treated water by said outlet means of said treated water.

14. A method for treating wastewater according to claim 13, further comprising a maintenance step for said pre-filter (1) at regular intervals, said maintenance step comprising: actuation of said control means, preferably by a quarter turn of said control means, so as to close said water supply orifice to be treated, in at least one closed position, while simultaneously disassembling said pre-filter by said first and second connection means, extraction of said filter part from said pre-filter body, cleaning and / or maintenance of said filter part, reinstallation, after cleaning and / or maintenance, of said filter part in said pre-filter body allowing reassembly of said filter part with said base, actuation of said control means, preferably by a quarter turn opposite to said quarter turn of said control means,in order to open said water supply orifice to be treated, in at least one open position.

15. Use of the pre-filter (1) according to any one of claims 1 to 8 so as to have a reduction of at least 50% of the suspended matter of the water to be treated compared to the treated water (suspended matter contained in the treated water exiting the outlet compared to the water to be treated entering the feed outlet).

16. Method for settling wastewater in a settling tank by implementing said pre-filter (1) according to any one of claims 1 to 8, said method comprising: an inlet of wastewater into a settling tank by at least one wastewater inlet, settling of the wastewater to give settled water, filtration of the settled water through said pre-filter, said pre-filter (1) being fluidically connected to at least one filtered water outlet, said filtration being arranged to give filtered water, an outlet of the filtered water by said at least one filtered water outlet.

17. A treatment tank for wastewater treatment, said treatment tank comprising: a wastewater settling tank according to any one of claims 9 to 12, a filtration chamber comprising at least one water inlet, in fluidic communication with said settled water outlet of said wastewater settling tank, and at least one filtered water outlet, between which extends a filter bed comprising a filtering material, said filter bed having an upstream section and a downstream face along a fluidic direction of filtration.

18. A wastewater treatment tank according to claim 17, wherein the filter material of the filter bed is a plant-based filter material comprising pieces of wood or plant fibers forming a population of pieces, said population of pieces being thermally transformed at a temperature between 150°C and 300°C forming a population of thermally stabilized pieces, for example a population of roasted pieces.

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