IMPROVED EFFICIENCY SLUDGE TREATMENT SYSTEM

Abstract

The present invention relates to a sludge treatment system employing a flocculating agent, comprising a sludge circulation zone, means for injecting a liquid flocculant solution into said zone, wherein the injection means comprise a reservoir for storing a flocculating agent in liquid form, a water supply, and a premixing device (SP) for the flocculating agent and water, the flocculating agent reservoir and the water supply being connected to the inlet of the premixing device, the premixing device comprising a circuit including at least two straight sections (D1, D2, D3) connected by a coil (S1, S2). [Fig. 2]

Description

Title of the invention: SLUDGE TREATMENT SYSTEM WITH IMPROVED EFFICIENCY TECHNICAL FIELD AND PRIOR ART

[0001] The present invention relates to a system for treating sludge with improved efficiency, particularly sludge resulting from the extraction of materials from pipes and wells by water injection and pumping.

[0002] When you want to unblock a blocked pipe, pressurized water is injected into it, which dissolves the materials, thus forming sludge, which is then sucked up and collected in a tank.

[0003] This type of device is generally installed on a sanitation vehicle which has a water tank and a sludge collection tank. Generally, the sludge is filtered to separate the larger solid particles from the water. The water is then returned to the water tank for reuse.

[0004] In order to improve water recycling, it is known to inject a flocculating agent into the sludge to agglomerate the remaining solid particles and facilitate their separation. The separation of the agglomerated solid particles and the water is then obtained by means of a filtration system.

[0005] The flocculation agent is previously diluted in water, then injected into the sludge tank directly or into a sludge circulation circuit prior to the cyclone separator. The preparation of the flocculation agent and water mixture is long and slows down the sludge treatment cycle, especially since this mixture has a lifetime of approximately 30 min, so it can hardly be prepared in advance, which imposes an additional constraint. Statement of the invention

[0006] It is therefore an object of the present application to provide a sludge treatment system having improved efficiency.

[0007] In the present application, "sludge" means the mixture of solid materials and water.

[0008] The aim stated above is achieved by a sludge treatment system comprising a circuit for circulating the sludge to be treated, a reservoir of at least one flocculation agent, a water supply and means for injecting said agent into the circuit, the system also comprising means for ensuring the continuous generation and delivery of the flocculation agent-water mixture, designated "flocculation solution" so as to be able to continuously inject the flocculation agent into the sludge circulation circuit.

[0009] Thanks to the invention, the duration of the sludge treatment cycle is reduced because there is no longer any waiting time for the flocculation solution to be available. In addition, the flocculation solution does not risk being out of date since it is manufactured on demand.

[0010] The inventors thought of setting up a unique device allowing, continuously, to generate the flocculation solution and to supply the circuit with it.

[0011] In a particularly advantageous example, the device for preparing and supplying the flocculation solution comprises a flocculation agent reservoir, a water supply both connected to the inlet of a circuit ensuring mixing, the outlet of the circuit being connected to the treatment circuit. The mixing circuit comprises straight zones, connected by serpentine-shaped zones and at least one variation of the passage section.

[0012] The mixing circuit may comprise one or more coils and / or one or more elbows and / or one or more narrowings of the flow section of the flocculation agent and water mixture.

[0013] The inventors discovered that such a circuit could quickly and over a relatively short path generate a flocculation solution injectable into the treatment circuit.

[0014] The serpentine-shaped zones cause a mixing or amalgamation phenomenon which, associated with straight zones and possibly one or more changes in section, quickly ensures that a mixture is obtained between the flocculation agent and the water injectable into the sludge.

[0015] The device offers the advantage of having a relatively small footprint and is entirely passive, that is to say it does not require a mixer set in motion by external energy. Only pumps are used to supply the device with flocculation agent and water.

[0016] The water is, preferably, at least in part the water resulting from the treatment of the sludge.

[0017] The system according to the invention can be integrated into a sanitation vehicle.

[0018] The present invention then relates to a sludge treatment system using a flocculation agent, comprising a zone for circulating the sludge to be treated, means for injecting a liquid flocculant solution into said zone, in which the injection means comprise a reservoir intended to store a flocculation agent in liquid form, a water supply and a device for premixing the flocculation agent and the water, the flocculation agent reservoir and the water supply being connected to the inlet of the premixing device, the premixing device comprising a circuit comprising at least two straight portions connected by a coil.

[0019] Preferably, the sludge treatment system comprises three straight portions connected two by two by a serpentine.

[0020] In an advantageous example, the circuit of the premixing device comprises at least one variation of the passage section.

[0021] The circuit of the premixing device may also comprise at least one bent portion, advantageously at 90°.

[0022] According to an additional feature, the connection of the water and flocculation agent supply to the circuit is such that the flocculation agent is injected into the water flow.

[0023] The injection of the flocculating agent preferably takes place between two bent zones.

[0024] In one example, the sludge treatment system comprises an injection pump flocculating agent and a water supply pump.

[0025] Preferably, the sludge treatment system comprises a water tank containing water obtained after treatment of the sludge, said tank forming the water supply.

[0026] In a particularly interesting exemplary embodiment, the sludge treatment system comprises a circuit comprising at least a first static mixer so as to generate turbulence in the flow of a sludge stream, an agglomeration device downstream of the first static mixer in the flow direction of the sludge stream, and the means for injecting the liquid flocculant solution are configured to inject the flocculant into the circuit at the level of the first static mixer.

[0027] The sludge treatment system may comprise a sludge collection tank before treatment, in which the injection means are capable of injecting the flocculation solution into the sludge tank.

[0028] The sludge treatment system advantageously comprises means for injecting a coagulant.

[0029] The present invention also relates to a sanitation vehicle comprising a treatment system according to the invention, means for injecting water into an area to be cleaned so as to form sludge, and means for sucking up the sludge. Brief description of the drawings

[0030] The present application will be better understood with the aid of the description which follows and the attached drawings in which: - [Fig.l] is a schematic representation of an exemplary embodiment of a sludge treatment installation implementing an example of a treatment system according to the invention, - [Fig.2] is a schematic representation of an example of a device of premixture of the treatment system according to the invention, - [Fig.3] is a front view of an example of a diaphragm that can be implemented in the treatment system according to the invention, - [Fig.3] is a side view of an example of a static mixer that can be implemented in the treatment system according to the invention, - [Fig.5] is a schematically represented longitudinal sectional view of an example of an agglomeration device that can be implemented in the treatment system according to the invention. DETAILED DESCRIPTION OF EMBODIMENTS

[0031] In [Fig.l], a sludge collection installation can be seen implementing an example of a treatment system according to the invention.

[0032] The installation is intended to collect solid materials, for example contained in pipes, wells or the like. In general, these solid materials at least partially block the pipe or well. In order to facilitate the suction of these solid materials, water is injected into the area to be cleared and the water and the solid materials forming sludge are sucked up.

[0033] The aim of the invention is to treat the sludge thus sucked up in order to recycle the water contained therein.

[0034] The installation comprises a sludge tank 1, a water tank 2, a water injection system 6 in the area to be cleaned, for example a CA pipeline, in order to facilitate the suction of the sludge and suction means 4 for the mixture of water and sludge contained in the pipeline.

[0035] The water injection system 6 comprises a high pressure pump 7.

[0036] The water tank has an outlet 2.1 for using water for the treatment system and an outlet 2.2 for discharging water and supplying the high-pressure pump which will be described later. The outlet 2.1 is equipped with a valve 3.

[0037] The valves are preferably pneumatic valves controlled either from a control panel by the user or automatically by a control unit which manages the different cycles autonomously. Alternatively, solenoid valves can be implemented.

[0038] In the example shown, the installation comprises a single tank whose internal volume is separated in two by a wall 8, thus forming the sludge tank 1 and the water tank 2.

[0039] The wall 8 can be movable, allowing the volume of the two reservoirs to be adjusted according to the volume of their contents.

[0040] The installation includes a sludge treatment system for separating the water from the solid matter and thus recycling the water so that it can be reused, for example to continue unblocking the pipe without having to refill the water tank.

[0041] The installation includes a circuit Cl intended to treat the sludge.

[0042] The circuit C1 is connected at the input to a discharge outlet 9 of the sludge tank 1 and at the output to at least one separator 14.

[0043] The circuit comprises a pump 12 intended to circulate the sludge in the circuit, the cyclone-type separator 14 intended to separate the water from the solid matter. The circuit C1, at the outlet of the cyclone separator 14, comprises a branch connected to the sludge tank to return the solid matter thereto and a branch connected to the water tank to return the water thereto. The circuit C1 comprises a first portion C1.1 between the inlet of the circuit and the pump 12, a second portion C1.2 between the pump and the cyclone separator, a third portion C1.3 between the cyclone separator and the sludge tank and a fourth portion C1.4 between the cyclone separator and the water tank.

[0044] Preferably, a filtration system 20, for example of the filter drum type, is provided at the discharge outlet 9 of the sludge tank 1 to ensure a first filtration of the sludge so as to retain the largest particles in the sludge tank.

[0045] The treatment system according to the invention S is configured to improve the separation of solid matter from water. For this, it comprises means for injecting a flocculation agent into the sludge in order to cause the agglomeration of the solid particles with each other and facilitate their separation. The use of flocculation agents for the treatment of sludge is well known and will not be described in detail.

[0046] In this example, the system is mounted between the inlet of circuit C1 and pump 12, as a bypass of portion C1.1 of circuit 10.

[0047] According to the invention, the treatment system comprises a circuit C2 connected at the inlet to the circuit C1 by a three-way valve 22 making it possible to direct the sludge towards the portion C1.1 or towards the circuit C2, and at the outlet to the circuit C1 upstream of the pump 12 by a three-way valve 24. The control of the valves 3, 22 and 24 makes it possible either to isolate the circuit C2 and to circulate the sludge in the portion C1.1, or to circulate the sludge in the circuit C2, or to circulate water in the circuit C2 or in the circuit C1 for rinsing them.

[0048] This example is in no way limiting and a processing system without the possibility of short-circuiting the circuit C2 does not depart from the scope of the present invention.

[0049] Circuit C2 comprises means for mixing the flocculant and the sludge to optimize the effectiveness of the flocculation agent.

[0050] The circuit C2 comprises means 25 for injecting a flocculation agent.

[0051] The injection means 25 according to the invention comprise a flocculation agent reservoir 27 and a device SP for continuously generating and distributing a flocculation solution.

[0052] The term “flocculation solution” means a mixture of one or more flocculation agents and water.

[0053] The device SP comprises a supply inlet E1 connected to the flocculation agent reservoir 27 and to a water supply. A pump 29 ensures the controlled supply of flocculation agent to the inlet E1. A pump 30 ensures the controlled supply of water to the inlet E1. Preferably, the water comes from the water reservoir 2. Alternatively, a system using a water reservoir separate from the water reservoir 2 does not depart from the scope of the present invention.

[0054] In [Fig. 2], a schematic representation of a preferred embodiment of the SP premixing device can be seen. The step implemented by the SP device is referred to as “premixing” because it takes place before mixing the flocculating agent with the sludge. The mixture obtained at the outlet of the premixing system is a liquid flocculant solution and will be referred to as the “flocculation solution”.

[0055] In the example shown and advantageously, the flocculating agent is injected into the water stream that comes from the water source, and the flocculating agent and the water are then injected together into the feed inlet of the device.

[0056] Advantageously, the inlet of the device comprises one or more bends and one or more changes in section, in particular downstream of the injection of water and flocculation agent, further improving the premixing.

[0057] For example, between the pump 30 and the injection of the flocculant an elbow-shaped connection 31.1 is provided. Also preferably, an elbow-shaped connection 31.2 is provided just after the injection of the flocculating agent at the inlet of the device. The elbows are advantageously 90° elbows. These elbows also promote mixing. In a particularly preferred manner, at least one change in passage section is present at the elbows or downstream of them as shown in [Fig.2] and designated by A.

[0058] One or more changes in passage section may be provided throughout the device.

[0059] The premixing device comprises an alternation of straight portions D1, D2, D3 and coils SI, S2, and one or more changes of section. In this example, the premixing device comprises three straight portions D1, D2 and D3 connected by two coils SI and S2. The coils generate a mixing phenomenon. The inventors have found that this alternation of straight portions and coils significantly improves the mixing of the flocculating agent in the water.

[0060] The number of straight portions and coils is in no way limiting and is chosen, for example, as a function of the desired premix efficiency, the space available and the quantity of flocculation agent to be premixed.

[0061] The device comprises an output 33 connected to the sludge treatment circuit.

[0062] The operation of the device is as follows.

[0063] Water is injected into the device by means of pump 30, it passes through elbow 31.1, and undergoes a change of direction. The flocculation agent is injected into the water just after elbow 31.1. The mixture passes through elbow 31.2 and undergoes a further change of direction. The passage section is then reduced, which has the effect of accelerating the flow rate.

[0064] The mixture then moves into the straight portion D1, then into the coil S1 in which it undergoes mixing, the straight portion D2, the coil S2 in which the mixture undergoes further mixing and finally the mixture circulates in a straight portion D3 until it is injected into the sludge.

[0065] In an exemplary embodiment, the straight portions are made from metal tubes and the coils from flexible plastic tubes wound on themselves. It will be understood that any other embodiment can be envisaged, for example the coils can be made from metal tubes wound on themselves.

[0066] The premixing device according to the invention has the advantage of continuously supplying a flocculation solution in a reduced footprint. In addition, the mixing is done passively, which contributes to the simplicity, robustness and reduction of the footprint of the device. No pump and / or stirring are required to ensure that a homogeneous flocculation solution is obtained.

[0067] The locations of elbows, section changes, coils and straight portions are not limiting and any other arrangement is not outside the scope of the present application.

[0068] The premixing device allows a flocculation solution to be generated continuously and on demand. This prevents the production of a flocculation solution that would not be used and would then expire. Such a device therefore reduces waste. Furthermore, the dosage of flocculation agent can very easily be changed instantly. The device thus offers a high degree of adaptability. For example, the quantity of flocculation solution and / or its composition can be controlled from values ​​measured at the system outlet and / or in the water tank, making it possible to adapt the quantity of flocculation agent injected as precisely as possible.

[0069] The injection device also has the advantage of ensuring continuous premixing of the flocculation agent with the water, and continuous injection into the circuit C2, which makes the sludge treatment faster. Such a system avoids having to stop the installation in order to fill a tank containing the water and flocculation agent mixture, as is done in existing installations.

[0070] In the example shown, the flocculation mixture produced by the premixing device is injected into a sludge circulation circuit at the outlet of the tank. sludge.

[0071] Alternatively, the flocculation solution is injected directly into the sludge tank in addition to or instead of injection into the sludge circulation circuit.

[0072] In the example of the system of [Fig.l], the mixing system advantageously comprises at least one first static mixer and advantageously two first static mixers in series.

[0073] The first static mixers can be chosen from the plate static mixer and the helical static mixer.

[0074] In a preferred example, the injection means inject the flocculant at the static mixer plate 26, hereinafter referred to as the “diaphragm” for simplicity. “At the diaphragm” is understood to mean in or just after the diaphragm. Preferably, the injection means are integrated into the diaphragm, more particularly the injector(s) 26.1 are integrated into the diaphragm plate as shown diagrammatically in [Fig.3].

[0075] In [Fig.3], we can see a front view of an example of diaphragm 26 which can be implemented in the present invention. It generates strong turbulence downstream, which causes an initial dilution of the flocculant in the sludge.

[0076] An example of a helical static mixer 28 is shown in [Fig.4]. The helical static mixer receives the flocculant and sludge mixture. It is configured to ensure separation of the flow and its regrouping, as well as rotation of the flow around the axis of the pipe. The arrows F symbolize the flows in the static mixer. The static mixer 28 comprises fins 28.1 arranged in the flow duct and shaped so as to ensure separation of the flow, its rotation and its regrouping.

[0077] The action of the diaphragm 26 and the static mixer 28 significantly improves the homogeneity of the mixture. Now the action of the flocculant, which is to ensure agglomeration of the particles between them, is particularly effective when the mixture is homogeneous. This therefore results in obtaining a homogeneous mixture quickly between the sludge and the flocculant, and an improved action of the latter.

[0078] The number of elements allowing the separation of the flow, its rotation and its grouping is chosen according to the installation, in particular according to the volume to be treated, in order to achieve a homogeneous mixture. This agglomerate of particles is called "floc".

[0079] Preferably, the treatment system comprises, downstream of the first diaphragm 26, a device 32, designated an agglomeration device, further promoting the formation of large flocs which are even more easily separable from the water. In [Fig. 5], a representation of the agglomeration device 32 can be seen.

[0080] The agglomeration device 32 comprises an enclosure 34 with a longitudinal axis X, having a first cylindrical part 36 with a circular section and a second conical part 38. The device comprises a supply inlet 41 of the enclosure oriented so as to ensure injection of the flow into the first cylindrical part 36, advantageously blades (not shown) making it possible to facilitate the generation of a vortex around the axis X, and an evacuation outlet 39 located in the lower part of the device in the representation of [Fig.5], more particularly at the free end of the second conical part 38 in the axis of the enclosure.

[0081] The operation of the agglomeration device 32 is as follows.

[0082] The flow of fluid leaving the static mixer 28 is injected tangentially to the wall of the first cylindrical part 36, which generates a swirling flow in the enclosure around the axis X. The flocs are then pushed radially outwards and then are brought closer to each other due to the flow in the direction of the discharge outlet 39. The flocs P being brought closer to each other, this results in an agglomeration of flocs between them and therefore the formation of flocs P' of larger dimensions, which are more easily separable from the water for example by a cyclonic separator.

[0083] Alternatively, the system comprises two first static plate mixers in series, two first helical static mixers in series. Alternatively, the first helical static mixer is upstream of the first static plate mixer and the injection of the flocculant takes place between them.

[0084] In a particularly advantageous manner, the treatment system also comprises means 40 for injecting a coagulating agent into the circuit upstream of the injection of the flocculant.

[0085] The injection means 40 comprise a coagulant reservoir 42, an injection pump 44 and an injection tube 43 which connects the reservoir to the circuit C2 upstream of the diaphragm 26. Very advantageously, the circuit C2 also comprises at least a second static mixer at which the coagulant is injected. The second static mixer preferably comprises a diaphragm 46. Preferably, the coagulant is injected into the diaphragm 46, in a similar manner to the diaphragm 26, improving the dilution of the coagulant in the sludge. Alternatively, the coagulant is injected just downstream of the diaphragm 46.

[0086] Also advantageously, a helical static mixer 48 is provided in front of the diaphragm 46, further improving the homogeneous mixing between the sludge and the coagulant.

[0087] The coagulant comprises, for example, metal salts, generally iron or aluminum salts, for example A1C13, making it possible to eliminate or at least reduce the colloidal repulsions between the particles, which facilitates the formation of flocs under the action of the flocculant.

[0088] The diaphragm 46 may be similar to the diaphragm 26.

[0089] The helical static mixer 48 may be similar to the helical static mixer 28.

[0090] Alternatively, the system comprises two second static plate mixers in series, two second helical static mixers in series. Alternatively, the second helical static mixer is upstream of the second static plate mixer and the injection of the flocculant takes place between them.

[0091] Also advantageously, the installation comprises means for monitoring and treating the recycled water 49 comprising for example a turbidimeter 53 which measures the turbidity of the water.

[0092] The water tank comprises a discharge outlet 2.2, a valve 51 for closing the outlet 2.2, a filter 52 and the turbidimeter 53.

[0093] For example, the filter 52 is such that it retains particles larger than 5 μm. The filter 52 is preferably a backwash filter.

[0094] Advantageously, the means 49 comprise a water treatment device, for example an ultraviolet disinfection lamp 54. The ultraviolet treatment makes it possible to make the water contained in the water tank comply with the requirements for being discharged into a drainage system.

[0095] In the example shown, a circuit C3 for short-circuiting the turbidimeter 53 and the water treatment device is provided between the valve 51 and an additional valve 58 which is provided between the water treatment device 52 and the ultraviolet lamp 54.

[0096] A turbidimeter 56 is advantageously arranged on the portion C 1.4 at the outlet of the cyclone separator. Very advantageously, it may be provided to check the turbidity of the recycled water to adjust the quantity of flocculant and / or coagulant to be injected into the circuit C2. Preferably, an electronic control unit automatically ensures the adjustment of the injection of the flocculant and possibly the coagulant according to the turbidity measurement. The quantities injected are for example managed by the control of the pumps, which makes it possible to limit the quantity of flocculant and possibly the coagulant to the necessary quantities.

[0097] An example of operation of the installation will now be described.

[0098] Water taken from the water tank 2 is injected into a pipe to be evacuated CA, the sludge thus formed is sucked up and collected in the sludge tank 1.

[0099] The valve 22 is controlled so as to connect the sludge tank 1 with the circuit C2, the pump 12 is activated so as to circulate the sludge in the circuit C2. Simultaneously, the pumps 29 and 30 are activated to inject the flocculant and the water into the SP premixing system, the solution thus produced is injected into the diaphragm 26. The pump 44 is also activated to inject the coagulant into the diaphragm 46.

[0100] The sludge is mixed first with the coagulant, then secondly with the flocculant, which causes the formation of flocs. The sludge containing the flocs is then injected into the agglomeration device, which has the effect of agglomerating the flocs together.

[0101] The sludge is then conveyed to the cyclonic separator 14 which ensures separation of the water, which is returned to the water tank 2, and the solid particles P', which are discharged into the sludge tank 1.

[0102] By controlling valves 3, 22 and 24, it is possible to ensure rinsing of circuit C2 by circulating water from the water tank to the cyclone separator 14.

[0103] It is also possible to back-rinse the filter 20 by controlling the valves so that the water circulates from the water tank directly out of the mud tank.

[0104] Alternatively, the entire treatment system may be arranged between the pump 12 and the cyclone separator 14. According to another alternative, the treatment system is arranged between the cyclone separator 14 and the water tank.

[0105] Alternatively, the flocculant injection means 25 can inject the flocculant directly into the sludge tank and / or directly into the water tank.

[0106] It will be understood that the sludge treatment system is a system in its own right which can be integrated during manufacture into a treatment plant or manufactured independently and connected to a plant as required.

[0107] The sludge treatment installation comprising a treatment system according to the invention may be fixed or mobile, for example mounted on a sanitation vehicle.

Claims

Claims

1. Sludge treatment system using a flocculation agent, comprising a zone for circulating the sludge to be treated, means (25) for injecting a liquid flocculant solution into said zone (C2), in which the injection means comprise a reservoir (29) intended to store a flocculation agent in liquid form, a water supply and a premixing device (SP) for the flocculation agent and the water, the flocculation agent reservoir (29) and the water supply being connected to the inlet (El) of the premixing device (SP), the premixing device (SP) comprising a circuit comprising at least two straight portions (Dl, D2, D3) connected by a coil (S1, S2).

2. Sludge treatment system according to claim 1, comprising three straight portions (D1, D2, D3) connected two by two by a coil (S1, S2).

3. Sludge treatment system according to claim 1 or 2, in the circuit of the premixing device comprises at least one variation (A) of the passage section.

4. Sludge treatment system according to one of claims 1 to 3, in which the circuit of the premixing device comprises at least one bent portion (31.1, 31.2), advantageously at 90°.

5. A sludge treatment system according to any one of claims 1 to 4, wherein the connection of the water and flocculating agent supply to the circuit is such that the flocculating agent is injected into the water stream.

6. Sludge treatment system according to claims 4 and 5, wherein the injection of the flocculating agent takes place between two bent zones (31.1, 31.2).

7. Sludge treatment system according to one of claims 1 to 6, comprising a flocculation agent injection pump and a water supply pump.

8. A sludge treatment system according to one of claims 1 to 7, comprising a water tank containing water obtained after treatment of the sludge, said tank forming the water supply.

9. Sludge treatment system according to one of claims 1 to 8, comprising a circuit (C2) comprising at least one first static mixer so as to generate turbulence in the flow of a stream

10.

11.

12. of sludge, an agglomeration device (32) downstream of the first static mixer (26, 28) in the direction of flow of the sludge flow, and in which the means for injecting the liquid flocculant solution (25) are configured to inject the flocculant into the circuit (C2) at the level of the first static mixer (26). Sludge treatment system according to one of claims 1 to 9, comprising a sludge collection tank before treatment, in which the injection means are capable of injecting the flocculation solution into the sludge tank.

11. Sludge treatment system according to one of claims 1 to 10, comprising means for injecting a coagulant.

12. Sanitation vehicle comprising a treatment system according to one of the preceding claims, means for injecting water into an area to be cleaned so as to form sludge, and means for sucking up the sludge.

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