Settling assembly for decanting an effluent

Abstract

Settling assembly (1) for decanting an effluent, comprising a settling tank (2) and a supply device (9) for supplying said settling tank (2) with effluent, said settling assembly (1) being characterized in that it comprises a flow distribution and energy dissipation compartment (4) capable of receiving the effluent directly from the supply device (9), said compartment (4) being installed in the settling tank (2) and delimited by at least a portion (23) of the external wall (22) of the settling tank (2), by at least one other liquid-tight lateral wall (6), and by a bottom wall (7) perforated with a plurality of orifices (8), forming an intermediate volume; said plurality of orifices (8) establishing fluidic communication between the intermediate volume and the settling volume.

Description

Effluent settling unit

[0001] The present invention relates to the field of water treatment and, in particular, to an assembly for settling an effluent.

[0002] More particularly, the invention relates to the supply of the effluent into a circular lamellar decanter.

[0003] Lamellar settlers are commonly used in effluent treatment to separate suspended particles in water.

[0004] However, it is relatively important to ensure uniform distribution of the incoming water flow and good dissipation of its energy to ensure optimal operation of the lamella clarifier.

[0005] Existing effluent supply devices on circular structures therefore require costly adaptations, particularly in civil engineering, to allow the effluent flow to be supplied in the central part, so as to obtain a uniform flow distribution. In addition, such an effluent supply does not allow for optimized control of the flow energy as it enters the settling basin, causing undesirable turbulence.

[0006] Also, there is a need for a solution that allows an effluent stream to be brought into a circular settling basin, allows for energy dissipation of the supplied effluent stream, improved flow distribution, and has a relatively simple and inexpensive design to achieve.

[0007] In this regard, an effluent settling unit is proposed comprising a settling basin and a device for supplying said settling basin with effluent,

[0008] said settling basin comprises a bottom and an external wall in the general shape of a right circular cylinder delimiting a settling volume,

[0009] said settling assembly being characterized in that it comprises a flow distribution and energy dissipation compartment capable of directly receiving the effluent from the feed device, said compartment being installed in the settling basin and delimited by at least a portion of the external wall of the settling basin, by at least one other liquid-tight side wall, and by a bottom wall perforated with a plurality of orifices, forming an intermediate volume; said plurality of orifices putting the intermediate volume into fluid communication with the settling volume.

[0010] Thus, due to the position at the edge of the basin of the flow distribution and energy dissipation compartment, it is relatively simple to bring the effluent, and to introduce it into the basin by dissipating its energy and ensuring a relatively optimal distribution of the flow. This therefore allows an optimized dissipation of the energy of penetration of the effluent in the circular decanter, while simplifying its supply.

[0011] Advantageously, the assembly further comprises lamellar modules installed in said settling volume of said settling basin and chutes for recovering the settled water on the surface of said settling basin. Thus, the flow via the perforated floor takes place by balancing the levels between the compartment and the settling basin.

[0012] Advantageously, said bottom wall of said flow distribution and energy dissipation compartment is mounted at a height from the bottom of the settling tank lower than the height of the recovery chutes. Thus, better mixing can be obtained in the effluent present in the tank.

[0013] Advantageously, said bottom wall is mounted at a height from the bottom, greater than or equal to two thirds of the total height of the pool.

[0014] Advantageously, the orifices are uniformly distributed on the bottom wall. This allows for improved flow distribution.

[0015] In particular, each orifice has a diameter between 3 cm and 40 cm.

[0016] In particular, the holes are spaced 5 cm to 60 cm apart from each other.

[0017] In particular, said portion of the external wall extends so that between its ends it forms an angle with respect to the center of the basin of between 20° and 160°.

[0018] Other features and advantages of the invention will emerge from reading the description given below of an embodiment of the invention, given for informational purposes but not as a limitation, with reference to the appended drawings in which:

[0019] is a schematic side view of a decanting assembly according to the main embodiment of the invention;

[0020] is a schematic perspective view of the decanting assembly according to the main embodiment of the invention;

[0021] is a top view of the flow distribution and energy dissipation compartment of the settling assembly according to the main embodiment of the invention;

[0022] is a perspective view of the flow distribution and energy dissipation compartment, the external wall of the settling basin not being shown;

[0023] is a top view of the settling assembly according to the main embodiment of the invention.

[0024] In a first embodiment of the invention, a settling assembly 1 for an effluent comprises a settling basin 2 and a device 9 for supplying said basin with effluent.

[0025] The settling basin 2 generally comprises at least one bottom 21 and an external wall 22 in the general shape of a right circular cylinder, defining a settling volume.

[0026] For example, such a pool can have a diameter ranging from 5m to 30m, and a depth, also called total height, between 2m and 10m.

[0027] In this embodiment, as explained below, the basin further comprises a recovery pit 20 for the settled particles.

[0028] The settling assembly 1 comprises lamellar modules 10 installed in said settling basin 2, and recovery chutes 11 for the settled water.

[0029] The lamellar modules 10 are known to be formed of lamellae, frequently in a "honeycomb" cross-section, which can be inclined at an angle of between 45 and 60 degrees relative to the horizontal so as to promote the separation and fall of the solid particles.

[0030] Thus, the effluent settles in basin 2 according to two mechanisms:

[0031] On the one hand, the heaviest particles suspended in the effluent fall by gravity to the bottom of the basin. A scraper bridge, not shown, then scrapes these particles and causes them to fall into the recovery pit 20, comprising a suction nozzle allowing the particles to be collected. This settling is made possible by the low turbulence of the effluent in basin 2, which explains in particular the desire to dissipate the energy of the effluent flow brought into basin 2.

[0032] The lightest particles suspended in the effluent are separated during the passage of the effluent through the lamellar modules, the operation of which is known to those skilled in the art, the clear water then being collected in the upper part of the lamellar modules by overflowing into recovery chutes 11.

[0033] These chutes 11, the edges of which extend above the level of the effluent from the basin 2, have partly submerged openings, so that the water leaving the lamellar modules flows into the recovery chutes 11 through these openings.

[0034] In order to dissipate the energy of the effluent flow, while improving the distribution of the flow entering the basin 2, the assembly 1 comprises a flow distribution and energy dissipation compartment 4, intended to receive the effluent arriving from the feed device 9, before it enters the settling basin 2.

[0035] The supply device 9 for said effluent may comprise distribution pipes, pumps or channels for conveying the effluent to the flow distribution and energy dissipation compartment 4.

[0036] The flow distribution and energy dissipation compartment 4 is made in basin 2.

[0037] In other words, said compartment 4 is contained in the volume defined by the external wall 22 in the general shape of a right circular cylinder.

[0038] This flow distribution and energy dissipation compartment 4 is formed by at least a portion 23 of the external wall 22 of the settling basin 2, and by a liquid-tight side wall 6 formed in said settling basin 2, forming an intermediate volume.

[0039] Seen from above the basin 2, the side wall 6 thus takes the form of a chord to the circle formed by the external wall 22.

[0040] The portion 23 of the external wall 22 extends here, in top view, over an arc forming an angle with the center of the basin of between 20° and 160°.

[0041] The side wall 6 is positioned so that the surface area occupied by the compartment 4 is between 5% and 40% of the general surface area of ​​the pool.

[0042] In other words, the side wall 6 extends on either side to the external wall 22.

[0043] However, the invention is not limited to a single side wall 6. The compartment 4 is delimited by the portion 23 of the external wall 22 and by one or more side walls.

[0044] Furthermore, the side wall(s) 6 do not necessarily extend in a flat manner, but may have curved, concave or convex shapes, or any other shape suitable for the decanter.

[0045] The lamellar modules 10 are mounted in the basin outside the compartment 4, and preferably in an arrangement allowing maximum distance between these lamellar modules 10 and the compartment 4, so as to limit the interactions of the fluids penetrating into the basin 2 and the fluids rising towards the lamellar modules 10.

[0046] Accordingly, in this embodiment, the lamellar modules extend into the basin from an edge diametrically opposite the portion 23 of the external wall 22 of the compartment 4.

[0047] According to a cross-sectional representation of the basin, seen from above, the side wall 6 forms a chord of the circle delimiting the periphery of the basin 2, so that the outline of the compartment 4 is formed by the chord and by the arc of the circle delimited by the chord.

[0048] This flow distribution and energy dissipation compartment 4 comprises a bottom wall 7 perforated with a plurality of orifices 8 opening into the settling volume of the settling basin 2.

[0049] Thus, although the intermediate volume is contained in the settling volume, these two volumes are only in fluid communication via the orifices 8 of the bottom wall 7.

[0050] In this embodiment, the bottom wall 7 extends substantially parallel to the bottom 21 of the settling basin 2, which ensures an advantageous distribution of the effluent in the compartment 4.

[0051] However, the bottom wall 7 could also present a total or partial variation, compared to the bottom 21.

[0052] The feed device 9 discharges an effluent into said compartment 4. This feed device 9 is installed and opens from the portion of the cylindrical surface 22 forming the flow distribution and energy dissipation compartment 4.

[0053] In other words, the effluent supply device 9 emerges from the periphery of the settling basin 2, which in particular allows for simplified technical implementation, particularly in civil engineering, of the effluent supply, unlike supplies in the center of the settling basin.

[0054] In this embodiment, the bottom wall 7, also called floor 7, closes the entire compartment 4 in its lower part, in other words opposite the bottom of the settling basin 2.

[0055] This bottom wall 7 is here made of concrete, but can be made of any other suitable material, whether plastic, polymer materials, metals, composites, adapted in particular to the type of effluent to be treated.

[0056] In the main embodiment of the invention, the bottom wall has a thickness depending on the material used.

[0057] The invention is not limited to a particular thickness, but may range, for example, from 1 mm to 50 cm, depending on the material used.

[0058] The bottom wall 7 of the compartment 4 is formed so that its level, or height, relative to the bottom of the settling basin 21, is lower than a minimum level of effluent present in the settling basin under operational conditions.

[0059] Preferably, the bottom wall 7 is mounted at a height, starting from the bottom 21, greater than or equal to two-thirds of the total height of the basin 2 and less than the total height of the basin 2.

[0060] In other words, under operational conditions, the effluent level 12 in the settling basin is higher than the level of the bottom wall 7 of compartment 4.

[0061] Thus, the effluent in flow distribution and energy dissipation compartment 4 enters the basin by balancing the effluent levels between compartment 4 and settling basin 2.

[0062] In particular, the water is extracted as shown by overflow into the recovery chutes 11, which allows penetration of the effluent contained in the compartment 4 into the basin 2.

[0063] Also, relative to the bottom 21 of the basin 2, the level of the bottom wall 7 has a height lower than the height of the recovery chutes 11.

[0064] This allows the energy of the effluent to be dissipated efficiently for its introduction into the settling basin and reduces hydrodynamic turbulence in the basin.

[0065] The bottom wall 7 comprises a plurality of orifices 8, distributed substantially uniformly over its entire surface.

[0066] These orifices 8 are sized to allow free passage of the effluent, while ensuring dissipation of its energy.

[0067] The orifices 8 are in the main embodiment of the invention uniformly distributed on the bottom wall 7.

[0068] In a particular example, the orifices 8 may have a diameter of between 3 and 40 cm and may be spaced 5 to 60 cm apart, depending on the surface area of ​​the bottom wall 7 and the properties of the effluent.

[0069] The invention is however not limited to a uniform distribution of the orifices on the bottom wall 7.

[0070] The bottom wall 7 may in particular comprise an arrangement of orifices according to a predefined non-regular pattern.

[0071] However, care is taken to ensure that the orifices are arranged in a pattern and with suitable dimensions to ensure an optimized distribution of the effluent flow in the settling basin at a desired flow rate.

Claims

Settling assembly (1) for an effluent comprising a settling basin (2) and a device (9) for supplying said settling basin (2) with effluent, said settling basin (2) comprises a bottom (21) and an external wall (22) in the general shape of a right circular cylinder delimiting a settling volume, said settling assembly (1) being characterized in that it comprises a flow distribution and energy dissipation compartment (4) capable of directly receiving the effluent from the supply device (9), said compartment (4) being installed in the settling basin (2) and delimited by at least one portion (23) of the external wall (22) of the settling basin (2), by at least one other liquid-tight side wall (6), and by a bottom wall (7) perforated with a plurality of orifices (8), forming an intermediate volume;said plurality of orifices (8) providing fluid communication between the intermediate volume and the settling volume.; Assembly according to claim 1, characterized in that it further comprises lamellar modules (10) installed in the settling volume of said settling basin (2) and recovery chutes (11) for the decanted water on the surface of said settling basin (2). Settling assembly according to claim 2, characterized in that said bottom wall (7) of said flow distribution and energy dissipation compartment (4) is mounted at a height from the bottom (21) of the settling basin (2) lower than the height of the recovery chutes (11). Decanting assembly according to claim 3, characterized in that said bottom wall (7) is mounted at a height from the bottom (21), greater than or equal to two thirds of the total height of the basin (2). Assembly according to any one of claims 1 to 4, characterized in that the orifices (8) are uniformly distributed on the bottom wall. Assembly according to any one of claims 1 to 5, characterized in that each orifice (8) has a diameter of between 3 cm and 40 cm. Assembly according to any one of claims 1 to 6, characterized in that the orifices (8) are spaced 5 cm to 60 cm from each other. Assembly according to any one of claims 1 to 7, characterized in that said portion (23) of the external wall (22) extends so that between its ends it forms an angle relative to the center of the basin (2) of between 20° and 160°.

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