Sewage settling pit and settling method

Abstract

Wastewater settling pit comprising a settling tank, a wastewater inlet and a settled water outlet, which are fluidically connected to the settling tank, a wastewater deflector, and an opening arranged to allow access to the inlet and / or the outlet, wherein the inlet and the outlet are close to each other so as to both be accessible through the opening.

Description

[0001] WASTEWATER SETTLEMENT TANK AND SETTLEMENT METHOD

[0002] technical field

[0003] The present invention relates to a wastewater settling tank.

[0004] The present invention also relates to a method for settling wastewater by implementing the settling tank according to the present invention.

[0005] The present invention also relates to the use of the wastewater settling tank according to the present invention for treating grey and / or black domestic water from a dwelling.

[0006] The present invention also relates to a means of separation, a deflector, for separating a flow of wastewater.

[0007] Previous art

[0008] The treatment of wastewater, particularly domestic wastewater, before its release into nature has existed for a long time.

[0009] In this context, there are various wastewater treatment processes such as physical processes based on settling and / or filtration processes that allow the removal of macro-waste and the reduction of the amount of suspended solids and / or the reduction of the amount of potentially harmful viruses and / or microorganisms that may be present in wastewater.

[0010] In order to ensure a settling process, there is the all-water septic tank which is a non-collective sanitation device ensuring pre-treatment of wastewater, such as a settling process, and which can be suitable for treating domestic water (grey water and / or black water) coming for example from a single-family home, a hotel complex, a company, or a housing estate.

[0011] The septic tank includes a settling tank designed to remove suspended solids and various pollutants through sedimentation. The settled water can then undergo various secondary treatments to produce water with suitable microbiological and / or physicochemical properties.

[0012] In this context, document W09730770 concerns a wastewater treatment system and process. The system described in this document comprises a septic tank with a rigid enclosure, a wastewater inlet pipe at one end of the tank, and a first inspection chamber (or manhole). The tank also includes a discharge pipe connected to a pre-filter at the other end, with the discharge pipe connected to a second inspection chamber. The septic tank also includes settling means for the heavier solids or sludge to settle at the bottom of the enclosure and for the accumulation of grease and lighter particles on the surface.However, the installation of the septic tank according to this document is impractical, requiring relatively lengthy and regular maintenance to unclog the inlet (wastewater supply pipe) and / or outlet (discharge pipe), which can become blocked by the suspended solids present in the wastewater. Furthermore, the installation of this septic tank is also impractical because it requires significant construction work to access the inspection chambers.

[0013] US2013206661 relates to a hydrodynamic separation unit designed to separate solids from a surface water stream flowing into the separation unit. The separation unit comprises a vertical cylindrical vessel and a vertical cylindrical structure located inside and separated from an inner wall of the cylindrical vessel. The unit, according to this document, is configured such that the stream containing the waste enters the vessel and flows through a peripheral space between the inner wall of the cylindrical vessel and the cylindrical structure within it. The stream then passes through a perforated portion of the cylindrical structure's wall and exits through an effluent pipe located in the lower part of a central space enclosed within the cylindrical structure.Although this document touts the merits of its technology, in practice this separation unit will require regular maintenance to prevent the screen in the central cylindrical structure from clogging. Furthermore, this unit is inflexible, limited to a cylindrical structure to ensure constant rotation of the fluid flow and thus prevent this central cylindrical structure from becoming blocked. Finally, this unit is impractical for maintenance because the effluent pipe is difficult to access, being located in the lower part of a central space enclosed within the cylindrical structure.

[0014] US Patent 701,1743 relates to a water pollution trapping device, specifically oil / gravel separators designed to separate and collect various pollutants from stormwater runoff. The patent describes a separation chamber comprising a wastewater inlet and an outlet, between which one or more separating walls are located. While the patent touts the advantages of its technology, in practice, this device is inflexible because deposits will preferentially accumulate in an upstream portion of the device near the inlet, which can lead to premature blockages.

[0015] Although all-water septic tanks exist on the market, there is still a need for a robust and flexible all-water septic tank (wastewater settling tank) that is practical and quick to implement, easily industrialized at affordable costs, more ecological and ensuring high settling efficiency to remove a maximum of suspended matter.

[0016] Objectives of the invention

[0017] The present invention aims to overcome the drawbacks of the prior art, in particular those described above.

[0018] In particular, the present invention aims to provide a wastewater settling tank (all-water tank) that is both robust and flexible, practical and quick to use, easily industrialized, cost-effective, and offers high settling efficiency. Furthermore, the present invention also aims to provide a settling tank requiring less on-site handling during installation, reducing the necessary equipment and labor while maintaining high wastewater treatment performance.

[0019] Summary of the invention

[0020] To achieve the aforementioned objectives, the invention provides a wastewater settling tank in which said wastewater forms a settling fluid circuit between an upstream wastewater inlet and a downstream settled water outlet, said settling fluid circuit having a wastewater inlet flow before passing through a deflector and a wastewater outlet flow after passing through said deflector, said settling tank comprising: o a settling tank delimited by a bottom wall, a series of side walls and a top wall, said settling tank being arranged to contain a bed of wastewater to be settled, o said wastewater inlet comprising an inlet orifice and said settled water outlet comprising an outlet orifice, in which said inlet orifice and said outlet orifice are arranged to be immersed in said bed of wastewater to be settled,said at least one wastewater inlet and said at least one settled water outlet being in fluidic connection with said settling tank, o an elbow comprising an inlet and an outlet, said elbow inlet being connected to said wastewater inlet, and said elbow outlet being an orifice arranged to guide the wastewater (the wastewater inlet flow) into said deflector, said deflector being arranged to divert said wastewater outlet flow from the settled water outlet and guide it towards one or more side walls of said series of side walls, o an opening, for example a manhole, located in said roof wall, said opening having a cross-section of length L along the roof wall and being arranged to permit access to said at least one wastewater inlet and / or to said at least one settled water outlet,wherein said inlet and said outlet are spaced at a distance of between 0.1 * L and 2 * L so as to be close to each other so that said at least one wastewater inlet and said at least one settled water outlet are both accessible for maintenance through said opening.

[0021] Indeed, a wastewater settling tank combining the aforementioned characteristics centered around a deflector and an elbow comprising an inlet and an outlet, the elbow inlet being connected to the wastewater inlet, and the elbow outlet being an orifice arranged to guide the wastewater outlet into the deflector, the deflector being arranged to divert the wastewater outlet flow from the settled water outlet and guide it towards one or more lateral walls of said series of lateral walls combined with the fact that said inlet orifice and said outlet orifice are spaced at a distance of between 0.1 * L and 2 * L so as to be close to each other so as to be both accessible through the same opening allows for a settling tank whose implementation is practical and quick.Indeed, the maintenance and / or repair of the wastewater inlet and / or the settled water outlet are carried out through the same opening, the same manhole. This greatly accelerates and facilitates the handling and maintenance of the settling tank, while also providing a tank requiring less handling on site during installation and / or maintenance. It reduces the equipment, such as risers, and the labor required, as it only needs one access point, a single manhole (inspection chamber), all while maintaining high water treatment performance. Furthermore, the presence of a single opening providing access to both the wastewater inlet and the settled water outlet simplifies the manufacturing and industrialization of the tank, as only one opening is required.Furthermore, the elbow combined with the deflector optimally reduces the velocity of the wastewater inlet flow into the settling tank, as well as the average flow velocities within the tank, while simultaneously lengthening the settling fluid circuit between the wastewater inlet and the settled water outlet. This ensures optimal removal of suspended solids by settling within the tank, preventing the resuspension of already settled sludge. Additionally, the deflector, designed to divert the wastewater outflow away from the settled water outlet and guide it towards one or more side walls of the settling tank, also ensures optimal wastewater circulation within the tank, preventing short circuits in the water flow between the wastewater inlet and the settled water outlet (between the inlet and outlet ports).This maximizes the residence time of the influx (wastewater entering the settling tank) by utilizing the entire volume of the settling tank. The optimal distribution of water flow within the settling tank increases the hydraulic path length of the water flow, thus reducing the average flow velocities. This also ensures high settling efficiency of the settling tank according to the present invention. Furthermore, the absence of short circuits in the water flow within the settling tank results in a robust, low-maintenance tank by protecting the settled water outlet, and optionally a pre-filter connected to this outlet, from premature clogging that could occur due to suspended solids when short circuits in the water flow are present.The presence of a single opening (a single manhole or inspection chamber), made possible by the proximity of the wastewater inlet (the inlet port) and the settled water outlet (the outlet port), thanks in particular to the arrangement of the elbow and deflector allowing optimal wastewater flow within the settling tank, also makes the settling tank according to the present invention more environmentally friendly because less equipment is needed for its manufacture and installation, such as risers placed between the roof and the ground in which the tank is buried. Furthermore, the presence of a single opening reduces the complexity of manufacturing the settling tank according to the invention, thus decreasing the handling time during its construction.

[0022] Preferably, the deflector includes:

[0023] (i) a main body comprising a bottom wall, side walls, optionally a roof wall, said main body also comprising a baffle inlet directly connected to said elbow outlet and a baffle outlet in fluidic connection with said sewage bed to be settled, a wall integrated into said main body and dividing said baffle outlet into two parts, said baffle outlet being oriented so as to deflect said wastewater outlet flow from the settled water outlet and guide it towards one or more side walls of said series of side walls, or

[0024] (ii) a Y-shaped main body having a base and two lateral branches, said Y-shaped main body comprising a deflector inlet at said base directly connected to said elbow outlet and a deflector outlet formed by said two lateral branches in fluidic connection with said sewage bed to be settled, in which preferably said settled water outlet is located between said two lateral branches, said deflector outlet being oriented so as to deflect said sewage outlet flow from the settled water outlet and guide it towards one or more lateral walls of said series of lateral walls, or

[0025] (iii) a curved partition wall having a concavity facing said elbow outlet and comprising an inclined bottom wall, said partition wall with its inclined bottom wall being oriented so as to deflect the wastewater outlet flow towards said side walls of said series of side walls and / or towards said bottom wall of said settling tank, or

[0026] (iv) at least one side wall of said series of side walls directly facing said elbow outlet so as to deflect said wastewater outlet flow from the settled water outlet and guide it so that said wastewater outlet flow runs along said side wall and / or is directed towards one or more other side wall(s) of said series of side walls.

[0027] Preferably, said wall integrated into the main body of the deflector is positioned so as to form an angle with the longitudinal axis of the main body, this angle being arranged to ensure a separation of the inlet flow of wastewater into at least two outlet flows of wastewater.

[0028] Preferably, the elbow outlet is an opening which is in a plane inclined with respect to a vertical plane and with respect to a horizontal plane at an angle between 30 and 85° and is arranged to guide wastewater into or against said deflector.

[0029] In the context of the present invention, the term "wastewater deflector" preferably refers to a means of diverting wastewater such that the wastewater exiting the deflector, or the wastewater coming into contact with the deflector, forming a wastewater outflow, is guided towards one or more lateral walls of the settling tank, while being diverted, and preferably away from, the settled water outlet. This increases the path, the distance, of the settling fluid circuit between the wastewater inlet and the settled water outlet, thereby ensuring optimal settling while taking advantage of the settling tank's volume to ensure optimal distribution of the sludge within the tank.

[0030] In the context of the present invention, the term "said elbow outlet being an orifice arranged to guide wastewater into said deflector, said deflector being arranged to deflect said wastewater outlet flow from the settled water outlet and guide it towards one or more side walls of said series of side walls" is understood to mean preferably that the elbow outlet is an orifice arranged to guide wastewater into or against said deflector, in which the deflector is arranged to disperse the wastewater outlet flow, deflect it from the settled water outlet, and guide it towards one or more side walls of said series of side walls, in which, preferably, the wastewater outlet flow has at least two flows, each having a mean direction diverging from each other, in which each of the two outlet flows is directed towards one or more side walls of said series of side walls.Preferably, the main body has a flared structure between the deflector inlet and outlet, such that the outlet has a larger cross-section than the inlet. This improves the dispersion of the wastewater flow at the deflector outlet.

[0031] Preferably, the elbow outlet and the deflector (the deflector inlet) of the wastewater are positioned in the settling tank so that at least 50%, 60%, 75%, 80%, 85%, 90%, or even 95%, 96%, 97%, 98%, 99%, or even 100% by volume of said wastewater inlet flow into the settling tank from the elbow outlet enters said deflector and / or comes into contact with said deflector, said deflector being arranged to disperse said wastewater outlet flow while diverting said wastewater outlet flow from the settled water outlet and guiding it towards one or more side walls of said series of side walls.

[0032] Preferably, the wastewater settling tank according to the invention further comprises a pre-filter located outside or inside the settling tank and in fluidic communication with the outlet of the settled water.

[0033] Preferably, the settling tank is a tank with a square or rectangular cross-section.

[0034] Preferably, the settling tank's side wall series comprises at least one side wall. Preferably, the settling tank's side wall series comprises two, three, or four side walls; more preferably, the settling tank's side wall series comprises four side walls.

[0035] Preferably, the settled water outlet includes the outlet orifice in fluidic communication with a settled water outlet channel. Preferably, said wastewater outlet orifice is adjacent to and in fluidic communication with the pre-filter such that the settled water passes through the pre-filter upon exiting the settling tank, the pre-filter being preferably located inside the settling tank. Alternatively, or preferably, said outlet orifice is in fluidic communication with the pre-filter via a settled water outlet channel.

[0036] Preferably, the wastewater inlet comprises a wastewater inlet channel in fluidic communication with the inlet orifice. Preferably, the inlet orifice is located in the settling tank.

[0037] Preferably, said at least one wastewater inlet and said at least one settled water outlet are spaced at a distance of between 0.2 * L and 2 * L, preferably between 0.2 * L and 1.5 * L, advantageously between 0.2 * L and 1 * L. Preferably, said inlet orifice and said outlet orifice are spaced at a distance of between 0.2 * L and 2 * L, preferably between 0.2 * L and 1.5 * L, advantageously between 0.2 * L and 1 * L.

[0038] Preferably, the length L is between 15 cm and 100 cm, preferably between 30 cm and 60 cm.

[0039] Preferably, the settling tank has a total volume preferably defined by a height H, a length Lo, and a width la. Preferably, in operational mode, the settling tank has a usable volume equal to the sum of the volume of settled sewage sludge and the volume of wastewater present in the tank. Preferably, at least one settled water outlet, preferably the settled water outlet, is located in the central zone of the settling tank, the central zone having a central volume V, the central volume V being defined by a height hv, a length lov, and a width lav, hv being between 0.2 * H and 0.8 * H, lov being between 0.2 * Lo and 0.8 * Lo, and lav being between 0.2 * la and 0.8 * la.

[0040] Preferably, at least one settled water outlet and at least one wastewater inlet are located in the central area of ​​the settling tank. Preferably, the wastewater inlet and the settled water outlet are located in the central area of ​​the settling tank. Preferably, the settling tank according to the invention includes a pre-filter located in the central area of ​​the settling tank, said pre-filter being in fluidic communication with the settled water outlet.

[0041] Other embodiments of the wastewater settling tank according to the present invention are indicated in the attached claims.

[0042] The present invention also relates to a method for settling wastewater by implementing the settling tank according to the present invention, the method comprising: o supplying wastewater into said settling tank through said wastewater inlet so as to bring the wastewater towards the inlet of said elbow, o passing the inlet flow of wastewater through said elbow so as to direct the inlet flow of wastewater and guide the wastewater into said deflector so as to divert the outlet flow of wastewater from the outlet of the settled water and guide it towards one or more lateral walls of said series of lateral walls, o settling the wastewater to give settled water, o optionally, filtering the settled water through a pre-filter fluidically connected to said outlet of the settled water, said filtration being arranged to give filtered water, o discharging the settled water.or optionally, a discharge of the filtered water, via at least one outlet for the decanted water.

[0043] Preferably, said wastewater inlet is carried out at a supply flow rate of between 0 and 10 L / s, preferably between 0 and 2 L / s, more preferably between 0 and 1.5 L / s.

[0044] Preferably, the settling tank has a usable volume of between 0% and 80%, and more preferably between 0% and 60%, of the total volume of the settling tank (usable volume relative to the total volume of the settling tank, where the usable volume is the volume occupied by the settled sewage sludge and the wastewater present in the settling tank). Preferably, the sludge filling rate in the settling tank is between 0% and 60% (volume of settled sewage sludge relative to the usable volume of the settling tank).

[0045] Other embodiments of the method for settling wastewater in a settling tank according to the present invention are indicated in the attached claims.

[0046] The present invention also relates to a use of the wastewater settling tank according to the present invention to treat domestic grey and / or black water from a dwelling, for example a single-family dwelling and / or a housing estate and / or a hotel, etc.

[0047] Other embodiments of the use of the wastewater settling tank according to the present invention are indicated in the attached claims.

[0048] The present invention also relates to the use of a wastewater separation means, a wastewater deflector, in a wastewater settling tank, preferably in the settling tank according to the present invention. Other embodiments of the use of a wastewater separation means according to the present invention are indicated in the appended claims.

[0049] The present invention also relates to a wastewater deflector comprising

[0050] (i) a main body comprising a. a bottom wall, one or more side walls and optionally a roof wall, b. a baffle inlet arranged to connect fluidically to a wastewater inlet of a settling tank or to an outlet of a bend, c. a baffle outlet suitable for fluidic connection with a wastewater bed to be settled in a settling tank, and optionally, a transverse wall integrated into the main body and dividing the baffle outlet into two parts.

[0051] Preferably, the transverse wall integrated into the main body is positioned so as to form an angle with the longitudinal axis of the main body, this angle being arranged to optimize the separation of said inlet water flow into said series of wastewater outlet flows and to optimize the direction of said series of wastewater outlet flows.

[0052] Preferably, the main body has a flared structure between said deflector inlet and said deflector outlet such that said deflector outlet has a larger cross-section than the cross-section of said deflector inlet.

[0053] Other embodiments of the wastewater deflector that can be implemented in the wastewater settling tank according to the present invention are indicated in the attached claims.

[0054] Detailed description of the invention

[0055] Other features, details and advantages of the invention will become apparent from the description given below, by way of non-limitation and with reference to the drawings and examples.

[0056] Figure 1 shows a diagram of a first embodiment of the wastewater settling tank according to the present invention.

[0057] Figure 2 shows a numerical simulation illustrating a visualization of the velocity field within the first embodiment of the wastewater settling tank according to the present invention, at the interface between the flow and the deposit according to a predetermined filling configuration (50% of the useful volume of the settling tank) and an incoming wastewater flow rate of 1 L / s.

[0058] Figure 3 shows a numerical simulation illustrating a visualization of the shear stress field within the first embodiment of the wastewater settling tank according to the present invention, at the interface between the flow and the deposit according to a predetermined filling configuration (50% of the useful volume of the settling tank) and an incoming wastewater flow rate of 1 L / s.

[0059] Figure 4 shows a numerical simulation illustrating a visualization of particle deposits with a falling velocity of 1 m / h for an inlet flow rate of 1 L / s and a tank filling rate of 50% within the first embodiment of the wastewater settling tank according to the present invention (top view).

[0060] Figure 5 illustrates a diagram of a second embodiment of the wastewater settling tank according to the present invention.

[0061] Figure 6 shows a numerical simulation illustrating a visualization of the velocity field within the second embodiment of the wastewater settling tank according to the present invention, at the interface between the flow and the deposit according to a predetermined filling configuration (50% of the useful volume of the settling tank) and an incoming wastewater flow rate of 1 L / s.

[0062] Figure 7 shows a numerical simulation illustrating a visualization of particle deposits with a falling velocity of 1 m / h for an inlet flow rate of 1 L / s and a tank filling rate of 50% within the second embodiment of the wastewater settling tank according to the present invention (top view).

[0063] Figures 8 and 9 illustrate a diagram of a third embodiment of the wastewater settling tank according to the present invention.

[0064] Figure 10 shows (A) a numerical simulation illustrating a visualization of the velocity field within the third embodiment of the wastewater settling tank according to the present invention, at the interface between the flow and the deposit according to a predetermined filling configuration (50% of the useful volume of the settling tank) and an incoming wastewater flow rate of 1 L / s, and (B) a numerical simulation illustrating a visualization of the shear stress field within the third embodiment of the wastewater settling tank according to the present invention, at the interface between the flow and the deposit according to a predetermined filling configuration (50% of the useful volume of the settling tank) and an incoming wastewater flow rate of 1 L / s.Figure 11 shows a numerical simulation illustrating a visualization of particle deposits with a falling velocity of 1 m / h for an inlet flow rate of 1 L / s and a tank filling rate of 50% within the third embodiment of the wastewater settling tank according to the present invention (top view).

[0065] Figure 12 illustrates a diagram of a first embodiment of the wastewater deflector according to the present invention.

[0066] Figure 13 illustrates a diagram of a second embodiment of the wastewater deflector according to the present invention.

[0067] Figure 14 shows a diagram of another embodiment of the wastewater settling tank according to the present invention.

[0068] In the figures, identical or analogous elements bear the same references.

[0069] 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.

[0070] In the context of the present invention, the "central zone of the settling tank" is understood to mean, preferably, a zone having a central volume V being defined by a height hv, a length lov and a width lav, the central volume being preferably located in an immersed zone of the settling tank and the central volume being entirely surrounded by a peripheral zone of the settling tank having a peripheral volume, the sum of the central volume and the peripheral volume being preferably equal to the useful volume of the settling tank (volume occupied by the wastewater and the settled sewage sludge).

[0071] In the context of the present invention, the term "useful volume of the settling tank" means the volume occupied by the wastewater and sludge settled in the settling tank.

[0072] In the context of the present invention, "the opening having a section of length L" is understood to mean, preferably, the largest dimension of the section of the opening along the wall of the sky accommodating the opening, for example the diameter for an opening having a circular section.

[0073] In the context of the present invention, preferably, the distance between 0.1 * L and 2 * L between said inlet orifice and said outlet orifice is measured between the wall of the outlet orifice facing the inlet orifice and the wall of the inlet orifice facing the outlet orifice.

[0074] Figure 1 illustrates a first embodiment of the wastewater settling tank 1 according to the present invention. Figure IA is a schematic, side view representation of Figure 1B. The wastewater settling tank 1 according to this embodiment, in which said wastewater forms a settling fluid circuit between an upstream wastewater inlet 3 and a downstream settled water outlet 4, said settling fluid circuit having a wastewater inlet flow before passing through a deflector s, 6 and a wastewater outlet flow after passing through said deflector 5, 6, said settling tank 1 comprises: o a settling tank 2 delimited by a bottom wall 2.1, a series of side walls 2.3 and a top wall 2.2, said settling tank 2 being arranged to contain a bed of wastewater to be settled, o said wastewater inlet 3 comprising an inlet orifice and said settled water outlet 4 comprising an outlet orifice, wherein said inlet orifice and said outlet orifice are arranged to be immersed in said wastewater bed to be settled, said at least one wastewater inlet 3 and said at least one settled water outlet 4 being in fluidic connection with said settling tank 2, o a pre-filter 7 connected to said at least one settled water outlet 4 so that the settled water passes through the pre-filter 7 when exiting said settling tank 2, o an elbow 5.1 comprising an inlet and an outlet, said elbow inlet being connected to said wastewater inlet 3, and said elbow outlet being an orifice arranged to guide the wastewater outlet into said deflector 5, 6, said deflector 5, 6 being arranged to divert said wastewater outlet flow from the settled water outlet 4 and guide it to one or more side walls of said series of side walls 2.3 or an opening 10 (not shown in Figure 1, shown in Figure 8) in the sky wall 2.2 of the settling tank 2, for example a manhole, arranged to permit access to said at least one wastewater inlet 3 and / or to said at least one settled water outlet 4, in which the inlet orifice and the outlet orifice are close to each other so that both are accessible through said opening 10.In this embodiment, the deflector 5, 6 includes a curved separating wall (half-moon plate) having a concavity facing said elbow outlet 5.1 and including a bottom wall inclined so as to deflect the wastewater outlet flow towards said side walls of said series of side walls 2.3 and / or towards said bottom wall 2.1 of said settling tank 2.

[0075] Preferably, the wastewater inlet 3 comprises a wastewater inlet channel 9 fluidically connected to an inlet orifice, said inlet orifice being arranged to be located in the submerged part of the wastewater bed of the settling tank 2.

[0076] Preferably, the settled water outlet 4 comprises a settled water outlet channel 8 fluidically connected to a settled water outlet orifice, said outlet orifice being arranged to be located in the submerged part of the wastewater bed of the settling tank 2.

[0077] According to the present invention, the pit 1 is fed at its inlet by a pipe that dips below the water level of the settling tank 2 in order to slow the flow entering the pit. Furthermore, the outlet includes a pipe equipped with a pre-filter 7 to prevent the passage of suspended solids to the water treatment devices located downstream of the settling pit according to the present invention, such as a filter medium.

[0078] Figures 2, 3, 4, 6, 7, 10, and 11 show the results of a numerical simulation whose methodology is based on a computational fluid dynamics approach and was implemented for the hydrodynamic and sedimentary study of the pit according to the present invention. This approach allows for a qualitative and quantitative study of the performance of the pit according to the present invention, taking into account its geometry and the hydraulic and sedimentary conditions to which it is subjected. This method is divided into three parts, described in the following paragraphs.

[0079] In Figures 2, 3, 6, and 10, Z1 represents a zone of high shear velocity and / or stress; Z2 represents a zone of moderate shear velocity and / or stress; and Z3 represents a zone of low shear velocity and / or stress. In Figure 2, Z4 represents a short-circuit zone between the wastewater inlet and the settled water outlet.

[0080] The first part is based on a hydrodynamic calculation of the flow through the pit according to the present invention. The objective is to visualize the streamlines and velocity field through the pit in order to qualitatively diagnose its operation.

[0081] The second part is based on the results of the first part and consists of calculating the transport of a dissolved pollutant within the septic tank according to the present invention. Analyzing the concentration of this element at the outlet of the septic tank allows for diagnosing the equipment's operation and, in particular, analyzing the hydraulic retention time.

[0082] Finally, the third part also relies on the results of the first and consists of numerically calculating the trajectories of the suspended particles and thus determining their fate in the structure (pit according to the present invention), that is to say whether they settle or are carried into the pre-filter.

[0083] Regarding hydraulic stress, a maximum inlet flow rate of 1 L / s is considered. This roughly corresponds to draining a bathtub. Furthermore, the sludge level in the septic tank is set at 50%, the maximum recommended level. Finally, a minimum settling velocity of 1 m / h for suspended solids will be taken into account.

[0084] In order to facilitate the implementation of the 3D digital model, particularly during the discretization stage into finite volumes, an adaptation of this geometry was carried out by removing components that do not have an influence on the hydro-sedimentary behavior of the structure, such as joints and fittings for example.

[0085] Residence time is the time it takes for a particle to travel the distance between the inlet and outlet of the septic tank. This residence time varies depending on the path taken by each particle, making it non-constant. Indeed, preferential pathways may form between the inlet and outlet, creating bypasses for part of the flow and thus circumventing the treatment process. Furthermore, some particles may enter hydraulically inactive zones, from which they only emerge from the settling tank after an almost indefinite period. In such cases, these occupied dead zones do not contribute effectively to the treatment process either, as they are minimally involved.

[0086] The performance of a settling tank can be quantitatively assessed by numerically modeling the transport of suspended solids within the tank. This model uses the velocity fields obtained during the first phase to calculate the trajectory of each particle. Furthermore, it considers the shear stress generated by the flow at the interface with the deposits, thus determining whether the available energy is sufficient to resuspend a particle once it has settled.

[0087] In the model, suspended solids are injected onto the inlet surface at a rate of 100 particles per second. The sediment supply is maintained for 100 seconds to ensure a sufficient number of particles for a significant and reproducible result.

[0088] All pipes in the model are equipped with a rebound boundary condition, which prevents sedimentation, since the objective is solely to evaluate the performance of the pit. Furthermore, the surface of the deposits within the structure is modeled with a deposition boundary condition, incorporating shear stress-based thresholding, as previously described. Particles that escape through the pre-filter can then exit freely through the outlet surface, where they are also counted.

[0089] A settling velocity of 1 m / h is tested to determine whether the particles most likely to remain suspended can actually escape through the pre-filter, which could lead to premature fouling, or whether they can also be settled in the pit.

[0090] To optimize the retention of suspended solids in the tank, it is advantageous to extend their residence time, thus ensuring sufficient time for them to settle at the bottom of the structure. Once settled, it is beneficial for the flow at the settling bed to have relatively low velocities to avoid the risk of resuspension and transport of the suspended solids to the pre-filter.

[0091] In the first embodiment of the pit according to the present invention, a first deflector configuration is proposed, consisting of an elbow having a predetermined angle fitted onto a plunging tee of the inlet pipe, accompanied by a crescent-shaped plate 5, 6. This is intended to divert the wastewater outflow from the settled water outlet 4 and guide it towards one or more lateral walls of the series of lateral walls 2.3, while preferably separating the wastewater flow entering the deflector into two parts and directing it within the settling tank so as to develop two preferably symmetrical recirculation loops, characterized by reduced velocities. The hydraulic results demonstrate that the upstream flow velocity is reduced by the descending elbow and tee.The half-moon separator 5, 6 then protects the pre-filter 7 by acting as a barrier and diffusing the jet towards the opposite side. Thus, the flow develops throughout the settling tank at lower velocities than those observed in the feed pipe.

[0092] Figure 2 shows that, at the interaction with the sediment bed, this design tends to maximize the surface area directly impacted by the downdraft. However, because the jet is disrupted by the deflector and the separation device, the maximum velocity at the sediment remains reduced. In the impact zone, the majority of the velocity vectors are directed towards the side wall of the pit, while a small portion of this flow is redirected towards the pre-filter.

[0093] Figure 3 shows that the interaction between the flow and the deposition bed generates a shear stress with a small maximum amplitude. However, this stress increases towards the outlet to the pre-filter.

[0094] Figure 4 shows the trajectories of suspended matter within the pit according to the first embodiment, taking into account this velocity field as well as the shear stress developed at the level of the sediment bed. The particles settled after 10,000 seconds of calculation are illustrated.

[0095] Advantageously, in the first embodiment of the pit according to the present invention, the entire useful volume of the pit is used by significantly diffusing the supply jet.

[0096] Figure 5 illustrates a second embodiment of the wastewater settling tank 1 according to the present invention, in which the deflector s, 6 is at least one of the side walls 2.3 of the settling tank 2. The elbow outlet is an orifice facing said at least one of the side walls 2.3 of the settling tank 2 and is situated in a plane inclined with respect to a vertical plane and with respect to a horizontal plane at an angle between 30° and 85°, and is arranged to guide the wastewater outlet so as to come into contact with said at least one of the side walls 2.3 (see Figure 5C). Said at least one of the side walls 2.3 is located on the other side of the elbow outlet with respect to the settled water outlet 4 and the pre-filter 7. Figure 5A illustrates an aerial view (top view) of a schematic representation of the settling tank 2.Figures 5B and 5C illustrate two different views of a longitudinal section of settling tank 2.

[0097] Figure 6 shows that the impact of the inlet jet on the deposit is further from the pre-filter. However, the maximum shear stress developed is three times greater than for the first embodiment of the pit according to the present invention, thus increasing the risk of deposit erosion.

[0098] Figure 7 illustrates that the velocity field developed in this embodiment of the settling tank also allows the particles to be transported over the entire all-water tank, thus utilizing the available storage volume (useful volume).

[0099] Figures 8 and 9 illustrate a third embodiment of the wastewater settling tank according to the present invention. Figures 8A and 9 show a diagram of the third embodiment of the wastewater settling tank according to the present invention, in which the settling tank comprises a deflector 5, 6 comprising a main body including a bottom wall, side walls, and optionally a top wall. The main body also includes a deflector inlet directly connected to the elbow outlet and a deflector outlet in fluidic connection with the wastewater bed to be settled. A wall is integrated into the main body and divides the deflector outlet into two parts. The deflector outlet is oriented so as to divert the wastewater outlet flow from the settled water outlet 4 and guide it towards one or more side walls of the series of side walls 2.3 (and / or towards the bottom wall 2.1). Furthermore, the main body of the deflector has a flared structure between said deflector inlet and said deflector outlet such that said deflector outlet has a larger cross-section than said deflector inlet. Figure 8B shows a diagram of the third embodiment of the wastewater settling tank according to the present invention, in which the settling tank comprises a partition wall 5, 6 located inside the settling tank. Figures 8A and 8B also illustrate the opening 10 in the top wall 2.2 of the settling tank 2, for example, a manhole. The opening 10 is arranged to allow access to said at least one wastewater inlet 3 and to said at least one settled water outlet 4.Figure 8C is a schematic view centered on the opening 10 in the sky wall of the settling tank 2, said opening 10 having a cross-section of length L along the sky wall and being arranged to permit access to said at least one wastewater inlet 3 and to said at least one settled water outlet 4.

[0100] Advantageously, the wastewater deflector 5, 6, arranged to divert the wastewater outlet flow from the settled water outlet 4, guide the wastewater outlet flow towards at least one side wall of the side wall series 2.3, and preferably separate the wastewater inlet flow into at least two wastewater outlet flows, makes it possible to limit the flow velocity at the inlet of the settling tank and direct the water flows towards a peripheral area of ​​the settling tank and away from the settled water outlet, thus protecting the pre-filter 7 which is connected to said settled water outlet 4. Preferably, the inlet velocity is reduced by a deflector whose shape is inspired by that of a plow. This configuration also aims to divide the inlet jet into two branches directed towards the wall opposite the pre-filter 7, while diffusing the velocity over a wider area.On the other hand, the separating wall between the all-water tank and the pre-filter is curved with a concavity facing the wastewater inlet so as to subsequently direct the recirculation loops towards the outside sides (side walls) of the settling tank 2, in order to protect the central area where the pre-filter 7 is located.

[0101] Figure 10 illustrates that the flow velocity when the jet (water flow) reaches the sediment bed is very low. The shear stress induced on the sediment bed is also very low.

[0102] Figure 11 shows that after a simulation of 10,000 seconds of physical time, according to this third embodiment of the invention, the particles are present throughout the entire settling bed. Statistical analysis also showed that a large majority of the particles—94% of the incoming particles—are trapped in the pit (mass of particles trapped in the pit relative to the total mass of particles entering the pit), thus reducing the risk of them being subsequently carried into the pre-filter. This means that once a particle reaches the settling bed, the flow does not have enough energy to resuspend it. Therefore, the proportion of particles escaping to the pre-filter is reduced to 5.9% for this third embodiment.

[0103] The settling tank according to the present invention addresses several constraints: removing the maximum amount of suspended solids to protect the pre-filter from excessively rapid clogging, preventing the resuspension of already settled sludge, and maximizing the retention time of the influx by utilizing the entire usable volume of the tank. Preferably, the deflector is arranged to separate the incoming wastewater flow into two parts, with the deflector positioned to direct these two parts of the flow in a different direction relative to the direction of the settled water outlet. This optimizes the flow circulation within the settling tank, thus ensuring optimal use of the entire volume of the tank.

[0104] Preferably, the wastewater deflector includes a separation wall (partition) located in the settling tank between the wastewater inlet and the settled water outlet, the separation wall being arranged to direct the recirculating water flows towards the peripheral area of ​​the settling tank.

[0105] Preferably, the outlet for the settled water is located in a central area of ​​the settling tank.

[0106] Preferably, in the method for settling wastewater according to the present invention, the wastewater is entered at an inlet flow rate of between 0 and 10 L / s, preferably between 0 and 2 L / s, more preferably between 0 and 1.5 L / s.

[0107] Preferably, the wastewater inlet is at an inlet flow rate and the settled water outlet is at an outlet flow rate, said inlet flow rate and said outlet flow rate being arranged so as to have a useful volume of the settling tank between 0% and 80% of the total volume of the settling tank.

[0108] Preferably, the filling rate of sewage sludge in the settling tank is between 0% and 80%, more preferably between 0% and 60% (volume of sewage sludge relative to the useful volume of the settling tank).

[0109] Preferably, the use of the wastewater settling tank according to the present invention allows for the treatment of grey and / or black domestic wastewater from a dwelling, for example a single-family dwelling and / or a housing estate and / or a hotel, etc.

[0110] Figures 12 and 13 illustrate different embodiments of the deflector according to the present invention comprising a main body 5.5 including a. a bottom wall, one or more side walls and optionally a top wall, b. a deflector inlet 5.6 arranged to connect fluidically to a wastewater inlet of a settling tank or to an outlet of an elbow, c. a deflector outlet 5.7 adapted to be in fluidic connection with a wastewater bed to be settled from a settling tank, and optionally, a transverse wall 5.8 integrated into the main body and separating the deflector outlet into two parts.

[0111] Figure 14 illustrates another embodiment of the settling tank according to the present invention, in which the deflector 5, 6 comprises a Y-shaped main body having a base and two lateral arms. The Y-shaped main body includes a deflector inlet at the base, directly connected to the elbow outlet 5.1, and a deflector outlet formed by the two lateral arms, which are in fluidic connection with the wastewater bed to be settled. The settled water outlet 4 is located between the two lateral arms. The curved arrows in the figure schematically illustrate the direction of the wastewater outlet flow in the settling fluidic circuit from the deflector outlet.

[0112] 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. Wastewater settling tank (1) in which said wastewater forms a settling fluid circuit between an upstream wastewater inlet (3) and a downstream settled water outlet (4), said settling fluid circuit having a wastewater inlet flow before passing through a deflector (5, 6) and a wastewater outlet flow after passing through said deflector (5, 6), said settling tank (1) comprising: o a settling tank (2) delimited by a bottom wall (2.1), a series of side walls (2.3) and a top wall (2.2), said settling tank (2) being arranged to contain a bed of wastewater to be settled, o said wastewater inlet (3) comprising an inlet orifice and said settled water outlet (4) comprising an outlet orifice, wherein said inlet orifice and said outlet orifice are arranged to be immersed in said wastewater bed to be settled, said at least one wastewater inlet (3) and said at least one settled water outlet (4) being in fluidic connection with said settling tank (2), o an elbow (5.1) comprising an inlet and an outlet, said elbow inlet being connected to said wastewater inlet (3), and said elbow outlet being an orifice arranged to guide the wastewater into said deflector (5, 6), said deflector (5, 6) being arranged to divert said wastewater outlet flow from the settled water outlet (4) and guide it towards one or more side walls of said series of side walls (2.3), or an opening (10), for example a manhole, located in said sky wall (2.2), said opening (10) having a cross-section of length L along the sky wall and being arranged to permit access to said at least one wastewater inlet (3) and / or to said at least one settled water outlet (4), wherein said inlet orifice and said outlet orifice are spaced at a distance of between 0.1 * L and 2 * L so as to be close to each other so that said at least one wastewater inlet (3) and said at least one settled water outlet (4) are both accessible for maintenance through said opening (10).

2. Pit according to claim 1, wherein said elbow outlet is an orifice which lies in a plane inclined with respect to a vertical plane and with respect to to a horizontal plane at an angle between 30 and 85° and arranged to guide wastewater into or against said deflector.

3. Pit according to claim 1 or claim 2, wherein said deflector (5, 6) comprises (i) a main body (5.5) comprising a bottom wall, side walls, optionally a roof wall, said main body (5.5) also comprising a baffle inlet (5.6) directly connected to said elbow outlet and a baffle outlet (5.7) in fluidic connection with said wastewater settling bed, a wall integrated (5.8) into said main body (5.5) and dividing said baffle outlet (5.7) into two parts, or (ii) a Y-shaped main body having a base and two lateral branches, said Y-shaped main body comprising a deflector inlet at said base directly connected to said elbow outlet and a deflector outlet formed by said two lateral branches in fluidic connection with said sewage bed to be settled, in which preferably said settled water outlet (4) is located between said two lateral branches, or (iii) a curved partition wall having a concavity facing said elbow outlet and comprising a bottom wall inclined so as to divert the wastewater outlet flow towards said side walls of said series of side walls (2.3) and / or towards said bottom wall (2.1) of said settling tank (2), or (iv) at least one side wall of said series of side walls (2.3) facing said elbow outlet.

4. A pit according to claim 1, wherein said deflector (5, 6) comprises: a main body (5.5) including a bottom wall, side walls, optionally a roof wall, said main body (5.5) also including a deflector inlet (5.6) directly connected to said elbow outlet and a deflector outlet (5.7) in fluidic connection with said wastewater bed to be settled, a wall integrated (5.8) into said main body (5.5) and dividing said deflector outlet (5.7) into two parts, or a Y-shaped main body having a base and two lateral branches, said Y-shaped main body comprising a deflector inlet at said base directly connected to said elbow outlet and a deflector outlet formed by said two lateral branches in fluidic connection with said sewage bed to be settled, in which preferably said outlet (4) of the settled water is located between said two lateral branches, or a curved separation wall having a concavity facing said elbow outlet and comprising a bottom wall inclined so as to deflect the sewage outlet flow towards said lateral walls of said series of lateral walls (2.3) and / or towards said bottom wall (2.1) of said settling tank (2) in which said elbow outlet is an orifice which is in a plane inclined with respect to a vertical plane and with respect to a horizontal plane at an angle between 30 and 85° and being arranged to guide the outlet of wastewater in said deflector in the direction of the outlet of settled water.

5. Pit according to claim 3 or claim 4, wherein said wall integrated into the main body is positioned so as to form an angle with the longitudinal axis of the main body, this angle being arranged to optimize the direction of the wastewater outlet flow.

6. Pit according to any one of claims 3 to 5, wherein said main body has a flared structure between said inlet of said main body and said outlet of said main body such that said outlet of said main body has a larger cross-section than the cross-section of said inlet of said main body.

7. Pit according to any one of the preceding claims, wherein said length L of said opening is between 30 cm and 100 cm, preferably between 30 cm and 60 cm.

8. Pit according to any one of the preceding claims, further comprising a pre-filter (7) connected to said at least one outlet (4) of the decanted water so that the decanted water passes through the pre-filter (7) when exiting said settling tank (2), said pre-filter (7) being located inside or outside said settling tank (2).

9. A pit according to any one of the preceding claims, wherein said settling tank (2) has a height H, a length Lo and a width la, and wherein said tank has at least one outlet (4) for the settled water, 16 preferably said outlet orifice, is located in a central area of ​​said settling tank (2), said central area having a central volume V, said central volume V having dimensions between 0.2 * H and 0.8 * H; 0.2 * Lo and 0.8 * Lo and 0.2 * la and 0.8 * la.

10. Pit according to any one of the preceding claims, wherein said wastewater inlet orifice and said settled water outlet orifice are located in said central area of ​​said settling tank.

1. Method for settling wastewater by implementing said settling tank according to any one of claims 1 to 10, comprising: o supplying wastewater into said settling tank through said wastewater inlet so as to bring the wastewater towards the inlet of said elbow, o passing the inlet flow of wastewater through said elbow so as to direct the inlet flow of wastewater and to guide the wastewater into said deflector so as to divert said outlet flow of wastewater from the outlet (4) of the settled water and guide it towards one or more side walls of said series of side walls (2.3), o a settling of wastewater to give settled water, o optionally, a filtration of the settled water through a pre-filter fluidically connected to said settled water outlet, said filtration being arranged to give filtered water, o a discharge of the settled water, or optionally a discharge of the filtered water, by said at least one (4) settled water outlet.

12. Method for settling wastewater according to claim 1 1 , wherein said wastewater supply is carried out at a supply rate of between 0 and 10 L / s, preferably between 0 and 2 L / s, more preferably between 0 and 1.5 L / s.

13. Method for settling wastewater according to claim 11 or claim 12, wherein the settling tank has a useful volume of between 0% and 80%, preferably between 0% and 60% of the total volume of the settling tank (useful volume in relation to the total volume of the settling tank in which the useful volume is the volume occupied by the settled sewage sludge and by the wastewater present in the settling tank).

14. A method for settling wastewater according to any one of claims 11 to 13, wherein the sludge filling ratio in the settling tank is between 0% and 60% (volume of settled sludge relative to the usable volume of the settling tank).

15. Use of the wastewater settling tank according to any one of claims 1 to 10 for treating grey and / or black domestic wastewater from a dwelling, for example, a single-family home and / or a housing development and / or a hotel, etc.

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