FR2907022A1 - Effluent treatment unit, especially for treating rainwater from overflow tank, comprises tank formed by assembling annular modules and having decantation and filtration compartments - Google Patents

Abstract

An effluent treatment unit, with a decantation compartment upstream of a filtration compartment, comprises a tank formed by assembling annular modules (1a - 1f); end closure elements (3, 4) having respective inlet and outlet openings (31, 41); and at least one intermediate separating wall (51) forming the decantation compartment (C1) and filtration compartment (C'2, C''2).

Description

The present invention relates to a unit for the treatment of effluents,

  especially for the treatment of rainwater from watersheds. The units for the treatment of effluents charged with sludge, suspended solids, hydrocarbons and / or heavy metals conventionally comprise different zones or compartments for carrying out successive treatments on the effluents, in particular a settling compartment, possibly preceded by a settling compartment and / or a buffer compartment, and a filtration compartment. These different compartments may be formed of different independent structures connected to each other, possibly by pumps. For example, it is known in particular from the international application WO2004 / 080559 a unit for treating effluents from technical areas, in particular runoff water and washing water from fairing areas, said unit of treatment comprising a buried buffer tank for recovering the effluents to be treated, effluent transfer means of the buffer tank to an external settling tank, the latter being provided with withdrawal means for recovering the sludge, and a filter tank buried to which are fed the effluents from the settling tank. Each compartment must be sized according to the volume of effluent to be treated, the nature of the pollutants and the amount of pollutants. Specific structures must therefore be designed for each treatment unit to be produced. Current treatment units are effective in treating effluents, but their design and placement is time consuming and expensive. The object of the present invention is to overcome the aforementioned drawbacks by proposing a simple processing unit of design, which is easy to install and inexpensive. For this purpose, the subject of the present invention is a unit for the treatment of effluents, in particular of rainwater originating from catchment basins, comprising from upstream to downstream a settling compartment and a filtration compartment, characterized in that it comprises a tank formed of a set of annular modules assembled to one another in a sealed manner via assembly means, such as assembly flanges, said assembly being closed at the end by a first and a second element closing members assembled on the annular end modules and respectively provided with an inlet opening and an outlet opening for the introduction of the effluents to be treated and their evacuation, at least one intermediate partition wall being arranged inside the set of annular modules to form the settling compartment and the filter compartment adapted to receive a substrate.

The present invention provides an effluent treatment unit comprising modular annular members joined to each other and end closure members to form a single elongate vessel, to be buried substantially horizontally, capable of decantation. sludge, separation of hydrocarbon pollutants, and substrate filtration. The use of such annular modules 3 makes it easy to adapt the volume of each compartment of the tank to the quantity and type of effluent to be treated. According to one feature, the partition wall 5 has a substantially horizontal upper edge, the transfer of effluents from the settling compartment to the filtration compartment being effected by pouring, over said upper edge, the effluents passing through the treatment unit by gravity, 10 without pumping system. According to one embodiment, the partition wall is disposed substantially at the assembly interface of two annular modules. According to another feature, the filtration compartment is equipped with a siphoid intermediate wall defining an upstream subcompartment and a downstream subcompartment communicating from below, the effluents flowing into the upper part of the upstream subcompartment, the discharge opening opening into the sub-compartment downstream, at least one of the two sub-compartments being adapted to receive a substrate. Advantageously, the filtration compartment is formed of at least two annular modules, the siphoid intermediate wall is disposed substantially at the assembly interface of two annular modules. According to another feature, the annular modules have support means for supporting a lamellar settling and / or coalescing system in the settling compartment, above a sludge storage zone, so that the flow of effluent arriving in the tank passes through said lamellar system.

According to one embodiment, the lamellar system comprises one or more modular lamellar blocks each comprising a parallelepipedal frame on which are mounted a plurality of lamellae parallel to each other, in one or more rows, said lamellar blocks being arranged in a column and or longitudinally one after the other, so that their slats are disposed substantially parallel to the longitudinal axis of the tank, and preferably inclined relative to the vertical, intermediate walls of upstream and downstream shutter being disposed upstream and downstream of the lamellar system to direct the flow of effluents through said lamellar system.

Advantageously, the lamellar blocks are slidably mounted on longitudinal guide rails arranged for example on inner shoulders of the annular wall of the annular modules. The settling compartment advantageously comprises at least one empty module, without lamellar system, to allow the displacement of the filtration modules during a cleaning operation. Advantageously, the annular modules have assembly flanges at the end and / or the annular modules of the settling compartment are equipped with ducts extending along the annular wall, preferably corrugated and / or ribbed, of the bottom of the module. to an upper manhole, to facilitate extraction of the sludge from the storage area by suction. According to one embodiment, the processing unit is formed from annular modules, obtained for example by roto-molding, provided with vertical end walls, in one piece with the annular wall of the modules, said vertical walls being removed or partially cut to form an intermediate wall of the vessel, in particular the partition wall, or a siphoid wall, a closure wall, or a substrate support wall for example. According to one embodiment, the filtration compartment is at least partly filled with a substrate comprising pumice aggregates, such as those marketed by the companies Stem Stone and Zeochem Diffusion, such aggregates proving particularly effective for adsorption removal of hydrocarbons and improve turbidity. The invention will be better understood, and other objects, details, features, and advantages will become more clearly apparent from the following detailed explanatory description of a particular presently preferred embodiment of the invention, with reference to the drawing. schematic annexed in which: - Figure 1 is a block diagram of a treatment tank according to one embodiment of the invention; Figure 2 is a perspective view of a process tank according to the embodiment of the invention of Figure 1; FIG. 3 is a perspective view of the three successive upstream modules of the settling compartment 30 of the treatment tank of FIG. 2; FIG. 4 is another perspective view of the three successive modules of FIG. 3, not equipped with lamellar blocks; FIG. 5 is a half-perspective view of the three modules of FIG. 4, in a vertical longitudinal section plane; - Figure 6 is a perspective view of the closure wall at the tank inlet; FIGS. 7 and 8 are respectively side and perspective views of a lamellar block for the settling compartment; FIG. 9 is a perspective view of the three successive downstream modules of the treatment tank of FIG. 2, namely the empty module of the settling compartment and the two modules of the filtration compartment; and - Figures 10, 11 and 12 show perspective views of the empty module, the first module and the second module of the filtration compartment, respectively. Figure 1 schematically illustrates the principle of an effluent treatment tank according to the invention intended more particularly for the treatment of rainwater of a watershed. The tank is formed of a succession of six annular modular elements, called annular modules, and referenced from 1a to 1f, assembled to each other in a sealed manner. This set of six modules is closed at the input by a first vertical wall 3, said input, assembled to the first module of the assembly, and at the output by a second vertical wall 4, called output, assembled at the last module 1f of the set.

The inlet wall 3 and the outlet wall 4 each comprise in the upper part an opening 31, 41 respectively defining the inlet orifice of the tank, intended to be connected to a rainwater collection network. and the evacuation orifice of the tank, intended to be connected for example to a wastewater network for discharging the effluents out of the tank. The inner volume of the vessel is longitudinally divided into a settling chamber C1 and a substrate filtration compartment C2 by a vertical partition wall 51 extending upwardly from the bottom of the vessel, and having an upper edge 51a. horizontal disposed below the inlet and outlet ports 15. In the present embodiment, the partition wall is disposed substantially at the assembly interface of two annular modules, the settling chamber C1 being formed of four annular modules la-ld, and the filter compartment C2. of two annular modules le-lf. The vessel also comprises a trap wall 52 for hydrocarbon retention, this upper wall is mounted at the same level as the partition wall 51 and extends from the top of the tank downwards with a lower edge 52a. disposed below the inlet and outlet ports, remote from the upper edge 51a of the partition wall to maintain a passage between the two compartments.

The settling compartment C1 is equipped with a lamellar settling system formed of modular lamellar blocks 6, resting on shoulders 2907022 8 modules as described below, with in the lower part a sludge storage area B. In In the present embodiment, only three modules of the settling compartment are equipped with lamellar blocks, so as to maintain an empty module ld just upstream of the filtration compartment, which will be used to move the lamellar blocks as described below. . The lamellar blocks are disposed between an upstream vertical closure wall 53 and a vertical downstream closure wall 54, so as to force the flow of effluent through said blocks. This lamellar block system makes it possible to increase the active decantation surface and thus to trap the smallest suspended matter. The lamellar blocks also make it possible to treat the fine droplets of hydrocarbons, such as gas oil, gasoline, and / or oil, by gathering them into larger droplets that will rise to the surface between the two closure walls.

The filter compartment C2 is intended to receive a substrate, in the form of porous granules, for example based on zeolites and / or pumice stones, ensuring by adsorption and ion exchange the elimination of dissolved particles, for example 5 microns, hydrocarbons, ammonium ions, and / or heavy metals. The porous structure of the substrate provides, by molecular sieve effect, a high adsorption capacity of organic and inorganic elements.

The filtration compartment is equipped with a siphoid intermediate wall 55 which separates the filtration compartment into an upstream subcompartment 290 C 2 and a downstream subcompartment C 2 communicating through the lower passage defined between the bottom the tank and the lower edge 55a of said intermediate wall, the discharge orifice is situated in the upper part of the downstream subcompartment, this system of siphoid wall and discharge orifice in the upper part makes it possible to increase the time of travel of the effluent through the substrate The substrate of the downstream subcompartment is preferably supported by a support wall 56 disposed substantially at the assembly interface between the last module 1f and the outlet wall 4 The upstream subcompartment C '2 is, for example, filled with a substrate S' formed of zeolite aggregates, substantially up to the upper edge 51a of the partition wall, and the downstream subcompartment C '2 is filled a substrate S "formed of granules of pumice type, of smaller particle size than that of zeolite type aggregates. In a variant, the filtration compartment does not comprise any siphoid wall and the discharge orifice is provided at the lower part of the tank, the upper edge of the partition wall then being disposed above said discharge orifice. In the embodiment illustrated in FIGS. 2 to 12, the vessel is formed of an assembly of identical annular modules having an annular wall 10 of generally oblong cross section. With reference in particular to FIGS. 4, 10 and 12, this annular wall has two parallel vertical side panels 11 connected by a curved lower pan 12 and a curved upper pan 13 provided with the manhole 14. For the purpose of stiffening, the annular wall is corrugated, with corrugations of generally rectangular cross-section. Each module has at the end a collar 15 for its assembly to another annular module or to an end wall 3, 4. The lower panel has a recess 16 defining 5 externally a base. This recess is formed while maintaining longitudinal and transverse reinforcements 17a, 17b to ensure the rigidity of the module. The lower pan further has two inner longitudinal shoulders 18 disposed on either side of the vertical longitudinal plane of symmetry of the module for the positioning of lamellar blocks, when the module is used to form the settling compartment. In the present embodiment, at the lower pan, the waves of the corrugations of the annular wall extend inwardly forming horizontal edges 19 extending downwardly by vertical edges 20, which horizontal edges constitute said shoulders for supporting the lamellar blocks.

The modules are for example made of a plastic material, such as PVC, or a composite material based on resin and fibers, such as a glass fiber-reinforced polyester type material, preferably by rotational molding. .

The annular modules, or at least a part of them, are preferably manufactured with end vertical walls at the flanges, molded in one piece with the annular wall of the module, these vertical walls are then cut to be removed, or partially cut to form one of the aforementioned internal intermediate walls 51-53 and 55-56 of the vessel.

Figures 3 to 5 show the three modules 1a, 1b and 1c of the settling compartment which are equipped with lamellar blocks. Two columns of three lamellar blocks 6a, 6b, 6c superimposed are placed in each of these modules, each column resting by its lower block 6c on the shoulders of the module. A rectangular cut 54a is then formed in a vertical wall of the first module 1a to form the upstream shut-off wall 53. This rectangular cut-out 54a has dimensions smaller than the cross-sectional area of a column of three lamellar blocks, in order to seal the passages around the blocks and thus direct the entire flow of effluent between the block plates. The other vertical wall of this first module 1a and the two vertical walls of the second and third modules 1b are completely removed. In order to facilitate the sliding of the lamellar blocks in the modules and thus facilitate their setting up and their displacement during cleaning operations, the columns rest on rails 21 mounted on said shoulders 18. Each rail, for example made of stainless steel , is formed of a plate whose length corresponds substantially to that of a module, coming horizontally flat against a shoulder, and provided with a vertical guide 21a directed upwards for guiding blocks and a vertical return 21b wedging downwardly against the aforementioned vertical edges 20 to wedge the rail. The rails 30 will preferably be attached to the shoulders via appropriate fastening means.

With reference to FIGS. 7 and 8, each lamellar unit 6 comprises a parallelepipedal support frame 61 open on each of its faces, formed of an assembly of tubular or bar frames, made of stainless steel for example, and on which plates or slats 62 are mounted parallel to each other in two parallel rows. The plates are arranged perpendicular to the open entrance 63 and outlet 64 faces of the frame, and inclined relative to the vertical. The block is mounted in an annular module so that its plates are arranged parallel to the longitudinal axis of the tank. The flow of effluents arriving through the inlet face passes between the plates of the first row, then those of the second row 15 before emerging through the exit face. The plates will for example be slid by the input and output faces between upper and lower rails of the frame, the plates bearing on one of their main face a pin 62a to ensure a gap between the plates. The plates are then held in the frame by stop bars 65 riveted to the frame. The chassis advantageously comprises upper centering pins 66 for centering the blocks when they are stacked in a column.

In order to facilitate the removal of the sludge present in the storage areas defined under the shoulders, each of the three modules is equipped with a suction pipe 22 extending into the inner hollow of a corrugation of the annular wall, with a lower end 22a disposed in the recess and an upper end at the manhole. The upper ends of the pipes of the outer modules 1a and 1c are preferably connected to upper horizontal pipes 23 extending to the manhole of the central module 1b to allow the sludge of the three modules to be sucked from there. latest. With reference to FIG. 6, the inlet wall has an annular flange 31 provided with longitudinal reinforcement and a flange 32 of generally oblong shape, identical to that of the flanges of the annular modules 10 to allow its assembly on the first module. . The vertical wall is slightly curved towards the outside and has in the upper part an outwardly extending tubular protrusion 33 consisting of a plurality of successive cylindrical portions 15 of different diameters, which decrease outwards, arranged tangentially so that the outgrowth has a continuous bottom, without steps. The aforementioned opening of the inlet wall, intended to constitute the inlet of the tank will be obtained by cutting one of the portions of this tubular excrescence to adapt the diameter of the opening to that of the pipe to which the tank will be connected. The inlet wall is equipped with a deflector or siphonic partition 34 disposed vis-à-vis the inlet orifice 25 to break the flow of effluents entering the settling chamber, and thus reduce turbulence and limit the phenomenon of rising sludge. The outlet wall 4 is identical to that of the inlet wall of FIG. 6, but without a siphoid wall. A downstream closure wall 54 of the settling compartment having an external periphery corresponding to the section of a module and a rectangular central opening identical to that of the upstream shut-off wall is assembled directly on the last column of the cooling system. lamellar. This wall 5 downstream shutter can be moved in the tank to the empty module to allow cleaning operations. Referring to FIGS. 9 to 12, a vertical end wall of the empty module 1d is omitted and the other is cut to form the top wall 52 of hydrocarbon retention. The vertical walls of the first module of the filtration compartment are cut to form the partition wall 51 and the siphoid intermediate wall 55. A vertical end wall of the last module 1f is removed and the other is cut to form the wall. 56. The establishment and operation of the tank described above, comprising six annular modules, will now be performed. Of course, the number of modules constituting each compartment, as well as the number of lamellar blocks can be adapted to the volume of effluents to be treated and the nature of the pollutants contained in the effluents to be treated. The annular modules can be easily transported by road to the treatment site where they will be assembled to each other. The set of three modules 1a, 1b and 1c with their suction pipe 22, 23 may optionally be pre-assembled before delivery on site. After placing the lamellar blocks 6 and the downstream closure wall 54, the inlet and outlet walls 4 are assembled and the tank is installed in its final location, in particular in a hole to be there. buried. The substrate will be loaded into the filtration compartment through the manholes of the modules 1a and 1f. The protuberances of the inlet and outlet wall are cut to the desired diameter to connect the tank to the effluent recovery network to be treated and to the evacuation network. The manholes are closed by removable covers 24. The recovered rainwater enters the settling compartment through the inlet port. The macro-waste may be filtered by a screen system disposed upstream of the treatment tank, possibly equipped with an overflow system to regulate the flow of effluent towards the treatment tank in case of incidents. As shown schematically by arrows in FIG. 1, the effluent stream enters the settling chamber through the inlet, passes through the lamellar system, flows into the filtration compartment, passing over from the upper edge of the partition wall and out of the tank via the discharge port. The level of effluent in the tank is represented diagrammatically by the discontinuous line referenced N. In the settling compartment, the fine particles decant and accumulate under the lamellar blocks, in the bottom of the tank, between the two intermediate walls. shutter. Because of their low density, some of the hydrocarbons rise to the surface. Droplets of oil and oil formed by coalescence accumulate on the surface in the settling compartment. The hydrocarbon-type floating layers will advantageously be adsorbed by means of floating and hydrophobic pumice stones placed between the closure walls and replaced periodically, such as those sold under the trade name Ecopomex. Alternatively, these floating layers can be adsorbed by means of adsorbent pads, placed in the settling compartment by manholes and periodically replaced, and / or degraded and digested by bacteria. The substrate may be regularly inspected and replaced via the manholes of the modules 1a and 1f of the filtration compartment. The sludge storage area will be regularly emptied, for example once a year, by suction of the sludge by means of a mobile pump connected to the pipes. An operator may descend into the settling module 15 in order to regularly clean the annular modules and their lamellar blocks, for example by means of a high-pressure cleaner. The empty module is used to longitudinally offset the filter block columns to allow the cleaning of each column 20 and to release successively each annular module. The columns can be moved on the rails by means of cables connected to a winch through the manholes. For example, each module defines an interior volume of 10m3. The tanks will preferably comprise at least three annular modules, two of which for the decantation compartment, tanks of several tens of annular modules, for example 50 or more modules, may be produced according to the quantity and nature of the effluents to be treated. According to an alternative embodiment, the downstream closure wall is formed in the same way as the upstream shutter wall, by cutting in a vertical wall of a module. The tank does not have an empty module, and the settling chamber will be cleaned only by the suction lines.

According to another variant embodiment, the modules are manufactured without vertical end walls, the various vertical walls mentioned above of the tank then consist of separate elements, assembled to the modules, preferably substantially to the assembly interface. two modules. The walls are for example held locked in position during the assembly of two modules, each wall comprising for example a peripheral portion which is interposed between the two collars. The upstream closure wall 53 is then mounted at the assembly interface of the inlet wall 3 and the first module 1a, the partition wall 51 and the high wall 52 of hydrocarbon retention are mounted on the 1d and the first module of the filtration compartment assembly interface, the siphoid intermediate wall 55 is mounted at the assembly interface of the first and second modules 1a, 1f of the filtration compartment and the wall support is mounted at the assembly interface of the second module 1f and the outlet wall 4.

Alternatively, the settling and filtering compartments are separated by a sealed partition wall extending over the entire height of the vessel, and transfer means are provided in the settling compartment, in particular in the empty module for transferring the effluents from said settling compartment to the substrate filtration compartment. These transfer means comprise, for example, a submerged pump provided with a suction inlet, and a delivery duct passing through the sealed partition wall and whose discharge end opens into the upper part of the compartment filtration. The start of the pump is controlled by a level detection system, placed in the settling compartment, comprising for example a float type level sensor. Although the invention has been described in connection with a particular embodiment, it is obvious that it is in no way limited thereto and that it comprises all the technical equivalents of the means described, as well as their combinations if those are within the scope of the invention. In addition, it can be applied to other fields of application than rainwater.

Claims (10)

  1. Unit for the treatment of effluents, in particular of rainwater originating from catchment basins, comprising from upstream to downstream a settling compartment and a filtration compartment, characterized in that it comprises a tank formed of a set annular modules (la-lf) sealingly joined to each other, said assembly being closed at the end by a first and a second closing element (3, 44), assembled on the annular end modules, and respectively provided with an inlet opening (31) and an outlet opening (41), at least one intermediate partition wall (51) being arranged inside the annular module assembly to form the compartment of decantation (Cl) and the filtration compartment (C2).   2. Treatment unit according to claim 1, characterized in that the partition wall (51) has a substantially horizontal upper edge (51a), the transfer of effluents from the settling compartment (Cl) to the filtration compartment (C2). by spilling, above said upper edge.   3. Treatment unit according to claim 1 or 2, characterized in that the partition wall (51) is disposed substantially at the assembly interface of two annular modules.   4. Treatment unit according to one of claims 1 to 3, characterized in that the filtration compartment (C2) is equipped with a siphoid intermediate wall (55) defining an upstream subcompartment (C'2) and a downstream subcompartment 2907022 (C "2) communicating from below, the effluent discharging into the upper part of the upstream subcompartment, the discharge opening (41) opening into the subcompartment downstream, at least the one of the two sub-compartments being adapted to receive a substrate.   5. Treatment unit according to claim 4, characterized in that the filtration compartment (C2) is formed of at least two annular modules (1a, 1f), the siphoid intermediate wall (55) is arranged substantially at the assembly interface of two annular modules.   6. Processing unit according to one of claims 1 to 5, characterized in that the annular modules (la-lf) have support means (18) 15 for supporting a lamellar system (6) in the compartment of settling, above a sludge storage area, so that the stream of effluents arriving in the tank passes through said lamellar system.   7. Treatment unit according to one of claims 1 to 6, characterized in that the lamellar system (6) comprises one or more modular lamellar blocks (6a, 6b, 6c) each comprising a frame (61) parallelepiped on which are mounted a plurality of lamellae (62) parallel to each other, said lamellar blocks being arranged in column and / or longitudinally one after the other, so that their lamellae are arranged substantially parallel to the longitudinal axis of the tank intermediate closure walls (53, 54) being disposed upstream and downstream of the lamellar system to direct the flow of effluents through said lamellar system. 2907022 21   8. Processing unit according to claim 7, characterized in that the lamellar blocks (6) are slidably mounted on longitudinal guide rails (21) arranged on inner shoulders (18) of the annular wall (10) of the modules. annular (la, lb, 1c).   9. Processing unit according to one of claims 3 to 8, characterized in that it is formed from annular modules provided with vertical end walls integral with the annular wall of the modules, said walls. vertical members being removed or partially cut to form an intermediate wall of the vessel.   10. Processing unit according to one of claims 1 to 9, characterized in that the filter compartment (C2) is at least partially filled with a substrate (S ") comprising granules of pumice.