FR2906803A1 - EFFLUENT PURIFICATION SYSTEM FOR SUCCESSIVE PHASES - Google Patents

Abstract

Installation comprising a tank (100) for separating suspended matter in the form of sludge.The cylindrical tank (100) provided with a bottom (102) forms from bottom to top, a sludge deposition zone (Z1) surmounted by a flocculation zone (Z2) itself surmounted by an effluent outlet zone (Z3, Z4). The bottom (102) has a passage (103) for the sludge. An effluent inlet (550) feeds the vessel (100) through its wall (101) into the flocculation zone (Z2). The effluent entrainment device (400) in the vessel (100) comprises movable bulkheads (410), rising, delimiting with the wall (101) and the bottom (102) of the tank (100), effluent compartments (CE) open at the top and bottom. The bulkheads (410) leave the upper portion (Z4) of the tank (100) free to form the outlet area (104) of the cleaned effluent (SN). A drive unit (420) moves the partitions (410) to slow speed relative to the wall (101) and the bottom (102) of the tank (100).

Description

Field of the Invention The present invention relates to an installation

  for purifying successive phases of effluents, comprising a tank receiving the effluents to enable them to separate from suspended solids in the form of sludge deposited at the bottom of the tank and passing through a sludge collection chamber provided with an outlet sludge, the cleaned effluents coming out of the top of the tank. It is known to treat the effluents, generally by adding flocculation additives and introducing the effluent / flocculant mixture into a tank to allow the sludge to be deposited at the bottom of the tank, the effluents cleaned sludge being evacuated from above the tank while the sludge collected at the bottom of the tank is evacuated on their side. But this general solution, known sludge purification, is a relatively slow process requiring large volumes of tanks therefore poses problems of installation, transport of effluents to clean and does not allow to simply purge selective sludge. OBJECT OF THE INVENTION The object of the present invention is to develop an effluent purification plant for separating sludge, which is effective for treating and eliminating heavy or light sludge, or simple to manufacture and maintain, permitting a selective separation and has a small footprint. DISCLOSURE AND ADVANTAGES OF THE INVENTION For this purpose, the invention relates to an effluent purification plant, characterized in that - the cylindrical vessel provided with a bottom forms from bottom to top, a sludge deposition zone surmounted by a flocculation zone itself on-30 mounted effluent outlet zone, * the bottom having a passage for the sludge, separating the tank from the sludge collection chamber, * an effluent inlet to supply the tank through its wall in the flocculation zone, an effluent entrainment device in the tank comprising movable, rising partitions delimiting with the wall and the bottom of the tank, open effluent compartments 2906803 2 * the bulkheads leaving the upper part of the tank free to form the exit zone of the cleaned effluents, - a drive unit moving the partitions at a slow speed with respect to the walls and the bottom of the tank. tank. The installation of effluents according to the invention makes it possible to involve or print the volumes of effluents contained in the compartments delimited by the moving partitions, a cycloidal movement or rolling movement of the water column, along of the fixed wall of the tank. This rolling movement, similar to a cycloidal movement of the liquid, promotes the separation of the sludge flakes and their gradual agglutination to grow and settle under the effect of their weight at the bottom of the tank from where the deposited flakes are removed by a squeegee effect exerted by the lower part of the partitions against the bottom of the tank to be directed towards the passage of the bottom and arrive in the sludge collection chamber. The uncleaned effluent is preferably introduced at a location in the tank wall, located in the upper part of the flocculation zone, so that the flakes that develop progressively descend into the water volume and the separated effluents. flakes progressively rise in the volume of water of the effluent chamber to pass into the outlet area of the cleaned effluent, which area is not swept by the partitions and constitutes an area in which the movement of the liquid is calmed. The movement of the partitions is a slow movement not to agitate the volumes of effluents but only to involve them a rolling movement in the effluent compartments. This movement and the rotational drive (cycloid movement) of the effluent volumes in the compartment creates a cyclone effect applied to the liquid, particles and flakes in suspension, pushing the particles out of the water column into each room, favoring their grouping into flakes. An elementary volume of effluent travels downwardly in a spiral path also depending on the effluent flow rate, that is to say the amount of effluent added to the chamber as it passes in front of the inlet. effluents.

  When the chamber is no longer in communication with the arrival of effluents, the moving liquid is no longer disturbed; this cycloidal movement is maintained by the slow movement of the partitions and the momentum imparted by the addition of effluents to the passage 2906803 3 before the arrival of effluents. The presentation of the invention has been made above generally but in the case of sludge with a density greater than the average density of the effluents, heavy sludge which separates down into the volume of effluents from the tank.

However, the installation and the general means thereof also apply to the purification of light or floating sludge, that is to say the density of which is lower than the average density of the effluents; such sludge back into the liquid of the tank to be evacuated by what, in the case of heavy sludge, is the output of cleaned effluent while the effluents cleaned of such sludge, go down into the so-called sludge collection room for to be evacuated by it. An elementary volume can thus describe a descending or ascending cycloidal movement corresponding to several rotations of the partitions. Since the chambers are closed, the volume of liquid they contain in principle changes only upon the arrival of a quantity of uncleaned effluents resulting in the release of a quantity of cleaned effluents. According to a particularly advantageous characteristic, the installation comprises an effluent feed with at least one mixer to add reagents to the effluents before their introduction into the tank. The addition of a reagent to the effluents promotes coagulation and flocculation of the particles in the form of sludge. This addition is preferably selectively to selectively remove a certain type of sludge because the effectiveness of reagent addition separation depends on the adequacy of the reagents and the sludge. According to another characteristic, the vessel is cylindrical of circular section and the movable partitions are radial panels carried by an axis concentric with the vessel forming a rotor driven in rotation by the drive unit.

This cylindrical tank-shaped installation structure with partitions arranged radially on the drive shaft constitutes a particularly simple solution to achieve because of its circular symmetry. According to an advantageous characteristic, the partitions are provided with oblong holes located above the flocculation zone or above the effluent inlet. These holes make it possible to break the cycloidal movement of the water by a horizontal circular movement of the purified water thanks to the water blade thus formed. This allows one hand, to return any flakes in the cycloidal movement and secondly, to calm more quickly the water when it passes over the partitions or blades. The interest of these oblong holes and this water slide is responsible for heavy sludge. In the case of light sludge that floats, the partitions do not have such oblong holes. According to another advantageous characteristic, the movable partitions are slightly inclined relative to the vertical direction, at an angle of the order of a few degrees. This inclination of the movable partitions communicates to the effluent volumes a downward velocity component for a suitable direction of rotation of the rotor. This component is interesting for heavy sludge, to favor the descendant of flakes following a downward spiral path. In the opposite case of floating light sludge, such as oils or greases, it is sufficient, for the same inclination of the partitions, to move and in particular to rotate the latter in the opposite direction so as to apply an ascending component to the particles of sludge suspended in the effluents. According to another feature, the passage of the bottom communicating with the sludge collection chamber is an elongate opening, substantially parallel to the orientation of the edge of the partition sweeping the bottom of the tank, when the partition is at level of the passage. This elongated opening makes it possible to evacuate very regularly the sludge layer scraped by the lower part of a partition and pushed by it in front of it. In the case of radial partitions carried by an axis in a cylindrical vessel of circular section, this elongated opening is preferably directed radially with respect to the axis and this passage of the bottom is in particular located at a place remote from the effluent inlet .

For greater efficiency, it is interesting that the arrival of the raw effluents is practically at the entrance of the flow path of the partitions while the outlet of the cleaned effluents is at the end of this circulation path. This allows, as indicated above, to disturb the volume of liquid contained in a chamber only in a reduced manner. According to an advantageous characteristic, the drive of the rotor is a motor, in particular a geared motor installed above the tank, in particular directly on the top of the tank being fastened to the wall of the tank. According to an advantageous characteristic, the sludge collection chamber is a hopper-shaped volume whose lower end is connected to a sludge pump, allowing the sludge flakes to be grouped progressively at the bottom of the hopper for pumping. , while the liquid which separates again at this level of the flakes, can go up in the tank as and when the flakes arrive. In the case of floating sludge, the sludge is discharged from above and the hopper under the bottom of the tank is used to evacuate the cleaned effluent. According to another advantageous characteristic, several purification plants as described above are combined in series, to selectively eliminate in each installation, a certain type of sludge. In this series installation, the first plant is preferably used to separate the floating sludge and the following facilities, the heavy sludge, which descend into the effluent. For each type of sludge, separately used coagulation and flocculation reagents will be used before entering each tank. The amount of injected reagent 20 is adapted to the amount of sludge of this nature, to be treated at this time in the tank. This allows a better efficiency of the reagents. Sludge can also be collected and processed separately depending on their nature. Drawings The present invention will be described below in more detail with the aid of an embodiment of a purification plant according to the invention shown in the accompanying drawings, in which: - Figure 1 is a view FIG. 2 is a horizontal sectional view along II-II of FIG. 1; FIG. 3 is a sectional view on III-III of FIG. 1; FIG. 4 is a sectional view similar to that of FIG. 1 showing the application of the plant to the separation of light sludge; FIG. 5 shows the combination of three installations according to FIGS. 4. DESCRIPTION OF AN EMBODIMENT According to FIG. 1, the invention relates to an effluent purification installation. This plant consists of an effluent tank 100 to allow the particles in suspension in the effluents to pool and flocculate to form sludges deposited at the bottom of the tank and collect them; the cleaned effluents exit through the top of the tank.

The effluents arrive in AE (arrival of effluents) to receive reagents and enter the tank through the effluent inlet EF. The cleaned effluents leave the tank 100 through the cleaned effluent outlet SN and the sludge through the sludge outlet SB. In this example, the tank 100 has a cylindrical shape of circular section delimited by a wall 101 and a bottom plate 102. Under the bottom plate is a collection chamber 200 collecting the sludge; it is in the form of an inverted hopper or cone communicating with the tank 100 through a passage described later. The collection chamber 200 is connected by a pipe 201 to a pump 202 for discharging the sludge thus collected. The tank 100 is subdivided schematically into four zones starting from the bottom: firstly, a sludge deposition zone Z1 on top of a flocculation zone Z2 itself surmounted by an intermediate zone Z3 and finally an exit zone. cleaned effluents Z4.

The tank is equipped with an effluent entrainment device 400. This device is a rotor formed of mobile partitions 410, mounted integral with an axis 411 driven in rotation by a drive means 420 constituted by a motor or a motor. gearmotor. The free end 412 of the shaft is engaged in a bearing of the bottom plate 102 of the vessel. In the upper part, the axis is integral with the output of the geared motor 420 itself installed by means not shown straddling the top of the tank 100. The rotor is rotated slowly around the axis of rotation ZZ in the direction A. The partitions 410 are slightly inclined in the same direction relative to the vertical direction, by an angle of the order of a few degrees. The movable partitions 410 are provided near their upper part with oblong holes 430, horizontally positioned identically so that by rotation they describe tori with respect to the axis of rotation ZZ. The sides of the partitions are lined with lip seals 440 bearing against the peripheral wall 101 of the tank. The lower side of the partitions 410 is provided with a scraper segment 450 bearing against the bottom plate 102.

The partitions 410 function as blades and leave free the upper part (Z4) of the tank 100 forming the outlet volume 104 of the cleaned effluents. This volume 104 in which the liquid movement of the tank is quieter is connected to an outlet pipe 105 in which the cleaned effluent passes by gravitation (SN output). Upstream of the tank the effluents are supplied by a pump 500 which introduces them into a mixer 520 preceded by a point of injection 510 of coagulant. This static mixer 520 has a reduced section and therefore a rapid rate of passage to promote coagulation.

The fast mixer 520 is followed by a slow mixer 540 preceded by an injection point 530 of a flocculant; its section is larger to promote flocculation. At the outlet, this mixer 540 opens into the tank 100 through a flared conical mouth 550 whose large base is oriented tangentially downwards in the tank.

The outlet 105 of effluents freed of a large part of their charge, is made by a pipe. This is advantageously disposed at the periphery of the tank 100 in an angular position with respect to the inlet 550, slightly greater than the arc covered by a compartment CE between two walls 410 of the rotor so that the effluents 20 arrive. in a compartment without immediately depressing the liquid volume of this compartment directly to the output 105. This arc is preferably 110 for a rotor with four walls 410 equiangular (90). FIG. 2 shows the rotor 100 consisting of four cross-shaped compartments 410 delimiting between them and the fixed wall 101 of the tank 100, each time an effluent compartment CE. The rotation of the rotor, for example in the direction of the arrow A, causes the volume of water of each compartment CE according to a rolling movement MR along the inner surface of the fixed wall 101 of the tank; this movement is comparable to a cycloidal movement resulting in an overall rotation MR of the liquid volume around a vertical axis in the compartment CE. The seals 440 bordering the partitions 410 on the sides prevent the formation of a film of liquid which would reduce the cycloidal rolling movement and possibly disturb it. With these seals 440, all the liquid contained in each effluent compartment CE is necessarily set in motion. The rotational drive of the moving partitions 410 by the drive unit 420 is a slow rotational movement, the clusters not having the function of agitating the effluent volumes CE but only to rotate them. around themselves by rolling along the wall. The slight inclination of the partitions 410 combined with their direction of rotation A generates a downward velocity component, favoring the deposition of the flakes at the bottom of the tank, in the case of materials of higher density than the average of the effluents. . The rotational movement promotes the expulsion of the particles and the grouping of flakes in large flakes F down into the tank 100 under the effect of gravity. The deposited flakes FD are taken up by the scraper segments 450 which pass them into the collection chamber 200 through the passage of the bottom plate 102. The horizontal oblong holes 430 made in the vicinity of the upper part of the partitions 410 make it possible to forming the transient zone Z3 between the flocculation zone Z2 which extends below, from the level of the inlet 550 of the effluents in the tank 100 and the outlet volume Z4, 104. This transient zone Z3 weakens the rotational movement the volume of water in each EC compartment without this movement of the volume of water being completely removed. The partitions 410 flowing in a slow motion leave the water rings in the upper part above the zone occupied by the bulkheads 410 of the rotor in the tank 100. The immobile crowns promote the damping of the movement. rotating each volume of water in its compartment EC so that finally, when the cleaned effluents leave the top of each compartment, weaken the circulation movement. Nevertheless, there remains a certain movement of the volume of water movement in the upper part of each compartment, a movement that favors the evacuation of the residual particles towards the sides of the compartment CE, that is to say the partitions 410 and the wall 101 of the tank so that they 30 go down along the walls in a more or less helical movement. FIG. 2 also shows the angular arrangement of the inlet 550 of the effluents and of the outlet 105. Since this angular distance is 110, the inlet 550 does not open into a compartment CE 35 while it is at the level of the outlet 105. Figure 3 shows a top view of the shape of pas-sage 103 made in the bottom 102 of the tank and opening into the sludge collection chamber. This passage is an oblong hole radially directed with respect to the rotor or to the tank 100, that is to say generally, it is directed parallel to a partition (in this case these partitions are also radial) . For reasons of presentation, the mixers 520, 540 are shown in positions diametrically opposite to FIG. 1, whereas in reality they are preferably juxtaposed as shown in FIGS. 2 and 3. According to an embodiment not shown, the installation may also have a structure different from that of a tank (circular cylinder) equipped with a rotor. It is sufficient, for the implementation of the invention, that the partitions delimit with the wall of the tank compartments and that the partitions move at a slow speed to generate the rolling movement or cycloidal movement of the volume of effluents in each compartment delimited by two partitions.

In the embodiment of the installation of FIG. 1, the cleaning of the effluents consists in separating products of higher density than that of the cleaned effluents, for example water. The cleaning is done by collecting the separate elements (sludge) at the base of the installation. However, the invention is also applicable to the cleaning of effluents containing materials of lower density than that of the effluents, for example fats or oils. Figure 4 shows an installation according to the invention for the separation of light or floating products such as oils or greases loading effluents.

The structure of the plant is almost identical to that described above except that the separated products of the effluent are removed by rising flakes in the liquid to collect in the upper part of the tank, above the bulkheads. rotor while the cleaned effluent of these oils or fats, descends to be evacuated by the collection chamber, previously used to collect heavy materials such as sludge. The elements of this installation identical to those of Figure 1, have the same references although the operation can be reversed.

The modifications of this second embodiment with respect to the first embodiment consist in promoting the rise of floating materials such as oils and greases by accentuating their natural gravitational lift movement and their flocking together. the rolling movement of the effluent volumes in the EC compartments and involving in this movement a component directed upwards and not downwards. For this and without modifying the inclination of the partitions 410, it suffices to rotate the rotor in the direction R opposite the direction of rotation A preceding. In addition, the introduction of the effluents to be cleaned is preferably by an inlet 550A in the lower part of the tank 100 and not towards the middle or at the top as in the previous embodiment, so that the effluents have a sufficient course height 10 to promote the grouping of small flakes into large flakes F, under the combined effect of the upward movement, the rolling movement of the liquid volumes in the EC compartments with centrifugal effect directing the flakes outwards volumes of effluents in rotation and finally of the ascensional component imparted to the liquid by the movement R and the orientation of the partitions 410. In the upper volume 104, in which the liquid is tranquilized, the flakes to be removed collect to pass by the exit 105 which then becomes a SB sludge outlet. The effluent inlet EF is at the base of the tank 100 and the outlet SN of the cleaned effluents is under the tank 100 by the collection chamber 200, the pump 560 then operating as an effluent discharge pump. cleaned and no longer as a sludge pump; the arrival AE of the effluents is upstream of the pump 500. After the pump 500, the effluents pass into the mixers 520, 540 with each time a reagent injection point 510, 530 to inject coagulant and flocculant. The connection between the mixers is the same as above except, as indicated, the output of the mixer 540. The upward or downward vertical circulation in the mixers is chosen according to the nature of the liquids to be mixed.

As indicated above, the mixers 520, 540 are preferably juxtaposed although presented in two diametrically opposite positions in FIG. 4. The installations described in both FIG. 1 and FIG. selective effluent cleaning and also step-by-step cleaning more accurate than overall cleaning. This makes it possible to adapt a coagulant agent and a particular flocculating agent to each type of product to separate effluents.

FIG. 5 shows a diagram of an installation made of the combination of three installations I1, I2, I3 such as that of FIG. 1 and FIG. 4. In order not to complicate the drawing, the different components of each installation are not represented. Only the 5 inputs and the outputs and the direction of rotation of the rotor are indicated. It should be noted that for obvious reasons it is preferable to first separate the products of lower density than the average density of the effluents such as oils and greases and then to separate the elements of higher density in one or more times. at the average density of the effluents and which collect in the collection chamber under the tank The series connection of the three installations according to FIG. 5 shows the arrival of effluents AE1 which pass through a first and a second static mixer to be introduced. at the base of the vessel through the effluent inlet EF1. The flakes of products to be separated go up, as already indicated, to be evacuated by the sludge outlet SB1 which is at the top. The cleaned effluent of these first types of products is taken at the base of the hopper under the tank by the outlet of cleaned effluents SM 1.

In this installation, the direction of rotation is the direction R adopted by convention as it was specified in connection with the installation of FIG. 4. Next, the effluents having undergone this first cleaning arrive at the effluent inlet AE2. of the second plant to also receive a coagulant and a flocculant and be introduced now through the effluent inlet EF2 in the upper part of the vessel. The flakes of elements to be eliminated develop as has been described and the sludge is collected in the collection chamber. This sludge is extracted by the pump and SB2 sludge outlet. The cleaned effluents are extracted in the upper part of the tank by the outlet of cleaned effluents SN2. These effluents, after this second cleaning, must undergo a third cleaning and arrive at the third effluent inlet AE3 to cross if necessary two static mixers to receive a coagulating agent and a flocculant specific to the types of elements to be eliminated 35. during this third stage. The operation is similar to that described above with regard to FIG. 1 and the second installation I2. The sludge is extracted from the sludge collection chamber by the outlet SB3 2906803 12 and the cleaned effluents are taken in the upper part of the tank by the outlet of cleaned effluents SN3. 5

Claims (5)

  1) Installation for purification by successive phases of effluents, comprising a tank receiving the effluents to enable them to separate suspended matter in the form of sludge deposited at the bottom of the tank and passing through a sludge collection chamber equipped with a sludge outlet, the cleaned effluent leaving the top of the tank, characterized in that - the cylindrical tank (100) provided with a bottom (102) forming from bottom to top, a sludge deposition zone (Z 1 ) surmounted by a flocculation zone (Z2) itself surmounted by an effluent outlet zone (Z3, Z4), the bottom (102) having a passage (103) for the sludge, separating the tank (100) of the sludge collection chamber (200), * an effluent inlet (550) for supplying the vessel (100) through its wall (101) in the flocculation zone (Z2), entrainment of the effluents (400) in the tank (100) comprising movable walls (410), rising, delimiting with the wall (101) and the bottom (102) of the tank (100), the effluent compartments (CE) open at the top and bottom, * the partitions (410) leaving free the upper part (Z4) of the tank (100) to form the zone of outlet (104) of the cleaned effluent (SN), - a drive unit (420) moving the partitions (410) at a slow speed relative to the wall (101) and the bottom (102) of the tank (100). 2) Installation according to claim 1, characterized by an effluent feed (AE) with at least one mixer (520, 540) for adding reagents to the effluents. 3) Installation according to claim 1, characterized in that the vessel (100) is cylindrical with a circular section and the movable partitions (410) are radial panels carried by an axis (411) concentric with the vessel forming a rotor rotated by the training group (420). 4) Plant according to claim 1, characterized in that the partitions (410) are provided with oblong holes (430) located above the flocculation zone (Z3) or above the effluent inlet (550). . 5 5) Installation according to claim 1, characterized in that the movable partitions (410) are slightly inclined relative to the vertical direction (ZZ), at an angle of the order of a few degrees. 6) Installation according to claim 1, characterized in that the passage (103) of the bottom (102) communicating with the sludge collection chamber (200) is an elongate opening, substantially parallel to the orientation of the scraper member (450) of the partition (410) sweeping the bottom (102) of the tank, when the partition (410) is at the pas-sage (103). 7) Installation according to claim 1, characterized in that the passage (103) of the bottom (102) is located at a location remote from the inlet (550) effluents. 8) Apparatus according to claim 3, characterized in that the drive (420) of the rotor is a motor, including a geared motor installed above the tank. 9) Apparatus according to claim 1, characterized in that the sludge collection chamber (200) is a hopper-shaped volume whose lower end is connected to a sludge pump (560). 35