SEPTIC TANK

Abstract

TITLE OF THE INVENTION: SEPTIC TANK The septic tank (300) comprises: - a reservoir (305) for the retention and digestion of organic matter contained in effluents, - a longitudinal distribution point (309) for effluents, and - a lateral collection point (316) for effluents. Figure for the abstract: Figure 5

Description

Title of the invention: SEPTIC TANK Technical field of the invention

[0001] The present invention relates to a septic tank. It is applicable, in particular, to the field of domestic wastewater treatment. State of the art

[0002] The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section constitutes prior art simply because of its inclusion in this section.

[0003] Septic tanks have the dual function of retaining solid matter contained in domestic effluents, by settling and flotation, and of liquefying this matter by anaerobic digestion.

[0004] A septic tank comprises a closed reservoir, an inlet, and an outlet. Typically, the outlet for liquid effluent is positioned opposite the inlet for effluent, and this is for several reasons: - The performance of settling in a septic tank is linked to the settling surface area - this surface area must be as large as possible in order to decrease the upward velocity of the materials and therefore retain as much material as possible; thus, by maximizing the distance between the inlet and outlet, the largest possible settling surface area is obtained. - Hydraulic short circuits, which reduce effluent retention time, are minimized a priori when the inlet is as far from the outlet as possible, and - Sludge theoretically accumulates more towards the inlet of the septic tank and the risk of sludge leaving the outlet is a priori minimized when the outlet is as far away from the inlet as possible.

[0005] Such a configuration A is represented in [Fig. 1], in which the following are shown: - an inlet 101 for effluents, - a 102 tank and - an outlet 103 for effluents positioned at the opposite end of the tank 102 relative to the inlet 101.

[0006] For various reasons, certain septic tank configurations require that the outlet outside the septic tank be positioned somewhere other than at the point furthest from the effluent inlet. In such configurations, although the outlet is relocated, the point of collection of liquid effluent inside the tank remains the furthest point from the effluent inlet and a set of internal tubing is implemented to transport the effluent from the capture point to the outlet.

[0007] Such a configuration B is represented in [Fig. 1], in which are shown: - an inlet 101 for effluents, - a reservoir 102, - a collection point 104 for effluents positioned at the opposite end of the tank 102 from the inlet 101, and - an outlet 103 for effluents connected to the collection point 104 by a pipe 105.

[0008] Such configurations are therefore limited to adding an internal hydraulic circuit to benefit from the advantages mentioned above while benefiting from the flexibility of positioning the outlet.

[0009] However, adding internal tubing to the pit presents a double disadvantage: it complicates the assembly, and above all, there is an increased risk of accumulation of materials and biomass in the tubing and therefore an increased risk of clogging of this tubing.

[0010] Existing systems sometimes have a complex configuration with the addition of extra parts, which does not allow for flexibility in installation. These systems have a standard performance that is not optimized, contrary to what the widely accepted theory of optimizing the treatment operation of a septic tank might suggest. Summary of the invention

[0011] The present invention aims to remedy all or part of these drawbacks.

[0012] The inventors have discovered, surprisingly, that contrary to widely held beliefs in the field of septic tank design, positioning a collection point for liquid effluent laterally to the general flow of effluent in the tank improves the performance of the septic tank. In other words, this discovery is counterintuitive with regard to the creation of a hydraulic short circuit and the apparent minimization of the settling surface area.

[0013] To this end, according to one aspect, the present invention relates to a septic tank, which comprises: - a reservoir for the retention and digestion of organic matter contained in effluents, - a longitudinal distribution point for effluents in the reservoir and - a lateral collection point for liquid effluents positioned laterally in the tank.

[0014] As can be understood, the distribution point is associated with an effluent inlet positioned at the interface between the inside and outside of the tank. The inlet and the distribution point may be the same or close together, or the distribution point may be located away from the inlet.

[0015] As can be understood, the collection point is associated with an effluent outlet positioned at the interface between the inside and outside of the tank. The outlet and the collection point may be the same or close together, or the collection point may be located away from the outlet.

[0016] Thanks to these provisions, the septic tank that is the subject of the present invention allows for many operating configurations due to the more flexible positioning of an outlet connected to the collection point compared to a strict longitudinal inlet-outlet configuration as known in the prior art.

[0017] Beyond this flexibility in positioning, the septic tank that is the subject of the present invention exhibits better treatment performance than septic tanks with longitudinal inlet-outlet connections. Such performance improvements are illustrated in [Fig. 2]. In particular, the hydraulic retention time is increased.

[0018] In particular embodiments, the retention tank has an elongated shape, the longitudinal distribution point being positioned near a short part of the tank and the lateral collection point being positioned near a long part of the tank.

[0019] In particular embodiments, the retention tank has a parallelepiped shape, the longitudinal distribution point being positioned near a small face of the tank and the lateral collection point being positioned near a large face of the tank.

[0020] In particular embodiments, the retention tank has a rectangular parallelepiped shape.

[0021] In particular embodiments, the lateral collection point is positioned at a distance from the longitudinal distribution point corresponding to at most 90% of the total length of the tank, at most 70% of the total length of the tank, at most 50% of the total length of the tank, at most 30% of the total length of the tank or at most 10% of the total length of the tank.

[0022] In particular embodiments, the lateral collection point is positioned at a distance from the longitudinal distribution point corresponding to between 45% and 55% of the total length of the tank.

[0023] In particular embodiments, the septic tank which is the subject of the present invention comprises an inlet, connected to the distribution point, positioned in the upper part of the tank.

[0024] In particular embodiments, the septic tank of the present invention comprises an outlet, connected to the lateral collection point, positioned in the upper part of the tank at a height lower than the height of the inlet.

[0025] In particular embodiments, the septic tank of the present invention comprises an effluent treatment element positioned immediately downstream of the lateral collection point.

[0026] These embodiments prevent hydraulic backflow towards dwellings when the septic tank is being filled. These embodiments also limit the release of solid matter from the tank. Brief description of the figures

[0027] Other advantages, purposes and particular features of the invention will become apparent from the following non-limiting description of at least one particular embodiment of the septic tank that is the subject of the present invention, with reference to the accompanying drawings, in which:

[0028] [Fig-1] schematically represents two particular embodiments of pits septic tanks as provided for in the prior art,

[0029] [Fig.2] schematically represents three diagrams illustrating the performance of the septic tank, the subject of the present invention

[0030] [Fig.3] schematically represents a first view of an embodiment particular septic tank, which is the subject of the present invention,

[0031] [Fig.4] schematically represents a second view of an embodiment particular septic tank, which is the subject of the present invention, and

[0032] [Fig.5] schematically represents a third view of an embodiment particulars of the septic tank which is the subject of the present invention. Description of the implementation methods

[0033] The present description is given by way of non-limiting grammar, each feature of an embodiment being able to be advantageously combined with any other feature of any other embodiment.

[0034] It should be noted from the outset that the figures are not to scale.

[0035] As can be understood from reading the present description, various concepts The inventive features can be implemented by one or more methods or devices described below, several examples of which are provided herein. The actions or steps performed in implementing the method or device can be ordered in any appropriate manner. Consequently, it is possible to construct embodiments in which the actions or steps are performed in a different order than illustrated, which may include the performance of certain acts simultaneously, even if they are presented as sequential acts in the illustrated modes of realization.

[0036] The expression "and / or", as used in this document, shall be understood as meaning "either or both" of the elements thus joined, that is, elements that are present conjunctively in some cases and disjunctively in others. Multiple elements listed with "and / or" shall be interpreted in the same way, that is, "one or more" of the elements thus joined. Other elements may also be present, other than those specifically identified by the "and / or" clause, whether or not they are related to those specifically identified elements.Thus, by way of non-limiting example, a reference to "A and / or B", when used in conjunction with an open language such as "including", may refer, in one embodiment, to A only (possibly including elements other than B); in another embodiment, to B only (possibly including elements other than A); in yet another embodiment, to A and B (possibly including other elements).

[0037] As used herein in the description, "or" should be understood inclusively.

[0038] As used in this description, the expression "at least one," with reference to a list of one or more elements, should be understood as meaning at least one element chosen from one or more elements in the list of elements, but not necessarily including at least one of each element specifically enumerated in the list of elements and not excluding any combination of elements in the list of elements. This definition also allows for the optional presence of elements other than the elements specifically identified in the list of elements to which the expression "at least one" refers, whether or not they are related to those specifically identified elements.Thus, by way of non-limiting example, "at least one of A and B" (or, equivalently, "at least one of A or B", or, equivalently, "at least one of A and / or B") may refer, in one embodiment, to at least one, possibly including more than one, A, without B present (and possibly including elements other than B); in another embodiment, to at least one, possibly including more than one, B, without A present (and possibly including elements other than A); in yet another embodiment, to at least one, possibly including more than one, A, and at least one, possibly including more than one, B (and possibly including other elements).

[0039] In the description below, all transitive expressions such as "comprising", "including", "carrying", "having", "containing", "implying", "holding", "composed of", and others, are to be understood as open-ended, that is, as meaning including but not limited to. Only the transitive expressions "consisting in" and "consisting essentially in" should be understood as closed or semi-closed transitive expressions, respectively.

[0040] Figures 3, 4 and 5 show a schematic view of one embodiment of the septic tank 300 which is the subject of the present invention. In particular: - Figure 3 shows, side by side, a front and side view of a particular embodiment of the septic tank 300 which is the subject of the present invention, illustrating two cross-sectional planes, corresponding to a vertical cross-sectional plane 301 and a horizontal cross-sectional plane 302. - Figure 4 represents a cross-sectional view, along the vertical cutting plane 301, of the septic tank 300 which is the subject of the present invention, and - Fig. 5 represents a cross-sectional view, along the horizontal cutting plane 302, of the septic tank 300 which is the subject of the present invention.

[0041] This septic tank 300 comprises: - a 305 tank for the retention of solid matter and the digestion of organic matter contained in effluents, - a longitudinal distribution point 310 for effluents in the tank and - a lateral collection point 315 for effluents positioned laterally in the tank.

[0042] The tank 305 corresponds to any closed receptacle suitable for the retention of domestic wastewater. This tank 305 can have any shape. To maximize the efficiency of settling, it is common to use an elongated tank 305. Such a tank 305, for example, has a parallelepiped shape. In a variant such as that shown in [Fig. 1], the tank 102 has an oblong internal horizontal cross-section.

[0043] The configuration of the particular shape of the tank 305 depends on the use case for which the tank 305 is configured, and this configuration is therefore not limiting.

[0044] The longitudinal distribution point 310 corresponds, for example, inside the reservoir 305, to the outlet of a pipe whose inlet is located outside the reservoir 305. In very simple variants, the longitudinal distribution point 310 corresponds to an opening in a wall of the reservoir 305.

[0045] Such a distribution point 310 can be adjacent to or remote from an effluent inlet in the tank, positioned at the interface between the inside and outside of the tank 305.

[0046] The distribution point 310 is said to be longitudinal because this distribution point fixes a longitudinal axis of general movement of the effluents in the reservoir 305. This longitudinal axis is represented by the reference 106 of [Fig.1].

[0047] This longitudinal axis of effluent movement is preferably aligned with an axis of symmetry of the tank 305, which corresponds to a centering of the distribution point 310. When the tank 305 is longer than it is wide, this longitudinal axis of effluent movement is preferably oriented in the general direction of the length of the tank 305, which corresponds for example to a positioning of the distribution point 310 on a short side of the tank 305.

[0048] The lateral collection point 315 corresponds to a liquid effluent collection site located inside the tank 305. This collection site corresponds, for example, to the inlet of a pipe whose outlet is located outside the tank 305. In very simple variants, the lateral collection point 315 corresponds to an opening in a wall of the tank 305.

[0049] The collection point 315 is said to be lateral because this collection point 315 is positioned transversely with respect to the general direction of flow of the effluents in the reservoir 305 at the distribution point 310 in particular.

[0050] In other words, the collection point 315 is positioned to the side with respect to the general direction of flow of the effluents in the reservoir 305 at the distribution point 310 in particular.

[0051] In other words, the collection point 315 is said to be lateral because it is positioned elsewhere than on the longitudinal axis of effluent flow in the previously defined tank 305. The collection point 315 is preferably offset from the axis of symmetry of the tank 305 in order to be closer to the lateral wall of the tank 305. When the tank 305 is longer than it is wide, the collection point 315 is preferably in the general direction of the width of the tank 305, which corresponds, for example, to positioning the collection point 315 on one of the longer sides of the tank 305.

[0052] In other words, the collection point 315 is said to be “intermediate” because it is located at an intermediate distance between the distribution point 310 and one end of the reservoir 305.

[0053] Thus, as can be understood, in particular embodiments, the retention tank 305 has an elongated shape, the longitudinal distribution point 310 being positioned on a short part of the tank and the lateral collection point 315 being positioned on a long part of the tank.

[0054] Such a collection point 315 may be adjacent to or remote from an effluent outlet in the tank, positioned at the interface between the inside and outside of the tank 305.

[0055] In particular embodiments, the retention reservoir 305 has a parallelepiped shape, the longitudinal distribution point 310 being positioned on a small face of the tank and the lateral collection point 315 being positioned on a large face of the tank.

[0056] In particular embodiments, the retention tank 305 has a rectangular parallelepiped shape.

[0057] In particular embodiments, the lateral collection point 315 is positioned at a distance from the longitudinal distribution point 310 corresponding to at most 90% of the total length of the reservoir 305.

[0058] In particular embodiments, the lateral collection point 315 is positioned at a distance from the longitudinal distribution point 310 corresponding to at most 70% of the total length of the reservoir 305.

[0059] In particular embodiments, the lateral collection point 315 is positioned at a distance from the longitudinal distribution point 310 corresponding to at most 50% of the total length of the reservoir 305.

[0060] In particular embodiments, the lateral collection point 315 is positioned at a distance from the longitudinal distribution point 310 corresponding to at most 30% of the total length of the reservoir 305.

[0061] In particular embodiments, the lateral collection point 315 is positioned at a distance from the longitudinal distribution point 310 corresponding to at most 10% of the total length of the reservoir 305.

[0062] In particular embodiments, the lateral collection point 315 is positioned at a distance from the longitudinal distribution point 310 corresponding to between 45% and 55% of the total length of the reservoir 305.

[0063] This distance 303 is represented in [Fig.3] and extends from the projection of the position of the distribution point 310 on the side of the reservoir 305 on which the collection point 315 is positioned to the center of gravity of the collection point 315.

[0064] In particular embodiments, the septic tank 300 of the present invention includes an inlet 309, connected to the distribution point 310, positioned in the upper part of the tank 305.

[0065] In particular embodiments, the septic tank 300 of the present invention includes an outlet 316, connected to the lateral collection point 315, positioned in the upper part of the tank 305 at a height lower than the height of the inlet 309.

[0066] In particular embodiments, the septic tank 300 of the present invention comprises an effluent treatment element 320 positioned in the tank 305 and downstream of the lateral collection point 315.

[0067] This element 320 is associated with the performance of an effluent filtration function. The type of element 320 depends on the use case implemented for the septic tank 300. Note that the element 320 can be a pre-filter or an effluent filter or any other type of device positioned immediately downstream of the collection point 315.

[0068] The performance of the 300 septic tank as represented in figures 3, 4 and 5 is illustrated in [Fig.2].

[0069] Fig. 2 represents three diagrams, referenced A, B and C, representing the comparison of different performance indicators between the 300 septic tank of the present invention and other known septic tanks.

[0070] Diagram A shows a curve graph of the values ​​of the quantity of suspended solids and the yield on suspended solids for the septic tank that is the subject of the present invention: - curve 201 of the suspended solids yield calculated between the inlet and outlet of the pit, - curve 202 of the concentration of suspended solids measured in the inlet effluent of the pit, and - curve 203 of the concentration of suspended matter measured in the effluent from the pit.

[0071] It is observed that the average yield 213 is 73%, with a value reaching as high as 90%. It is also observed that the outlet concentrations 212 average 77 mg / L, with a maximum of 120 mg / L and a minimum of 35 mg / L. These values ​​are at least similar to, or even better than, those observed in the case of a typical pit.

[0072] Such values ​​can be measured during a test carried out on a 3 cubic meter usable volume septic tank, supplied with domestic wastewater from a housing development of 14 single-family homes. The daily wastewater supply regime is that of standard EN 12566-3. The results correspond to 160 days of testing.

[0073] Diagram B represents, on the x-axis, a volume of recovered liquid effluents, in litres, and on the y-axis the time required to reach this volume.

[0074] This diagram is obtained from tests carried out in clear water on four pit configurations, two of which, 204 and 206, are the subject of the present invention (with and without a flow restrictor), and two, 205 and 207, are typical pits (also with and without a flow restrictor). A volume of 200 L was discharged into the inlet over a period of three minutes, corresponding to draining a bathtub. The cumulative volume of water exiting the pits was determined by regularly measuring the volume collected at the outlet over time.

[0075] It is observed that it takes slightly longer to recover the water from the pits of the present invention, with or without an outlet flow restrictor, suggesting an increased residence time within the pit. An increased residence time corresponds to improved performance for solids retention.

[0076] This value is measured: - for the septic tank 204, which is the subject of the present invention, when a flow restrictor is implemented, - for a septic tank 205 with longitudinal alignment of distribution and collection points, when a flow restrictor is implemented, and - for the septic tank 206 which is the subject of the present invention, without a flow limiter, - for a septic tank 207 with longitudinal alignment of the distribution and collection points, without a flow limiter.

[0077] Compared to a typical pit, a lateral collection point allows the recovery time of the entire injected volume to be extended by 15% and 30% respectively with and without a flow limiter.

[0078] Diagram C represents, on the x-axis, time, and on the y-axis, the height of sludge, in centimeters, in the septic tank that is the subject of the present invention. This value is measured: - for a measurement point 208 located opposite the distribution point of the septic tank, - for a measurement point 209 located laterally to the flow through the tank and at the level of the lateral collection point, and - for a measurement point 211 located at the longitudinal distribution point.

[0079] Curve 210 of diagram C shows the average of the measurements of curve points 208, 209 and 211.

[0080] This diagram shows that the sludge heights in the pit that is the subject of the present invention evolve as in a standard pit.

[0081] Diagrams A, B and C illustrate a performance superior or equal to that of the pit which is the subject of the present invention in comparison with existing septic tanks.

Claims

Demands

1. Septic tank (300), characterized in that it comprises: - a reservoir (305) for the retention and digestion of organic matter contained in effluents, - a longitudinal distribution point (310) for effluents in the reservoir and - a lateral collection point (315) for effluents positioned laterally in the reservoir.

2. Septic tank (300) according to claim 1, wherein the retention tank (305) has an elongated shape, the longitudinal distribution point (310) being positioned near a short part of the tank and the lateral collection point (315) being positioned near a long part of the tank.

3. Septic tank (300) according to any one of claims 1 or 2, wherein the retention tank (305) has a parallelepiped shape, the longitudinal distribution point (310) being positioned near a small face of the tank and the lateral collection point (315) being positioned near a large face of the tank.

4. Septic tank (300) according to claim 3, wherein the retention tank (305) has a rectangular parallelepiped shape.

5. Septic tank (300) according to any one of claims 1 to 4, wherein the lateral collection point (315) is positioned at a distance from the longitudinal distribution point (310) corresponding to at most 90% of the total length of the tank, at most 70% of the total length of the tank, at most 50% of the total length of the tank, at most 30% of the total length of the tank or at most 10% of the total length of the tank (305).

6. Septic tank (300) according to claim 4, wherein the lateral collection point (315) is positioned at a distance from the longitudinal distribution point (310) corresponding to between 45% and 55% of the total length of the tank (305).

7. Septic tank (300) according to any one of claims 1 to 6, the septic tank which is the subject of the present invention comprises an inlet (309), connected to the distribution point (310), positioned in the upper part of the tank (305).

8. 12 Septic tank (300) according to any one of claims 1 to 7, the septic tank (300) of the present invention comprises an outlet (316), connected to the lateral collection point (315), positioned in the upper part of the tank (305) at a height lower than the height of the inlet (309).

9. Septic tank (300) according to any one of claims 1 to 8, comprising an effluent treatment element (320) positioned immediately downstream of the lateral collection point (315).

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