FR2878169A1 - MONOBLOC INSTALLATION FOR WATER TREATMENT ASSOCIATING A DECANTATION UNIT AND A FILTRATION SYSTEM - Google Patents

Abstract

Monoblock installation for water treatment comprising a settling unit through which the raw water to be treated circulates from bottom to top, the decantation unit being positioned above a filtering device through which passes through gravity water decanted, characterized in that the settling unit is hermetically separated from the filter device by means of a partition and in that it is provided with a pipe connecting the top of the decanter at the top of the system of filtration in which circulates the decanted water.

Description

MONOBLOC INSTALLATION FOR WATER TREATMENT

  ASSOCIATING A DECANTATION UNIT AND A FILTRATION SYSTEM

  The invention relates to a new monobloc installation for the treatment of water comprising a decanting unit of the raw water to be treated and a filtration system.

  The installation of the invention is more particularly adapted for the treatment of water supplying small settlements, up to about 16 000 inhabitants where there is no specific treatment plant, At present, the water supplied in some villages is spring water which, initially drinkable, can quickly be the subject of bacteriological pollution or physicochemical pollution. In this case, one of the widely used treatments consists of a bleach treatment. Nevertheless, this type of solution is not satisfactory since it is often poorly controlled. In addition, it gives the water an unpleasant taste. At the same time, the regulation of drinking water quality is setting an example by being the European turbidity standard which is currently less than 0.5 nfu. This therefore means that there is a significant need for effective pollution control systems that can be implemented easily, at low cost, and does not have the above disadvantages.

  A system of this type is disclosed, for example, in document FR-A-2 374 068. More specifically, this reference describes an installation combining in the same chamber, settling and filtration. However, the described device has a number of disadvantages. The first is that the settling system is mounted directly in the submergence chamber of the filter, which means that an anomaly of one or the other of the two elements, requires the immobilization of the entire installation. Furthermore, it is intended to wash against the current simultaneously or separately, the filter and the settling system. In the case of separate washing, it is specified that the washing of the settling tank must necessarily be carried out following the washing of the filtering layer. In fact, the water used for the backwashing comes from the supply valve positioned at the bottom of the installation, and necessarily passes through the filter before going to the decanter, which implies that in case of separate washing , the water recovered above the filter must be clean. In any case, whether the cleaning of the clarifier and the filtration system is separate or simultaneous, all the sludge present on the surface of the separators is recovered at the bottom of the decanter, then eliminated by means of a pipe of evacuation. However, the skilled person knows that to obtain effective settling, it is necessary to leave under the separators, a mud web allowing a predecantation of the raw water. Another disadvantage relates to the hopper or wedge shape of the partition separating the decanting device from the submergence chamber leading to obtain a variable circulation velocity of the liquid and therefore a non-homogeneous treatment of the fluid. Finally, the specific form of the separators composed of multiple thin vertical and parallel sheets, between which are disposed other sheets constituting spacers does not allow optimal settling.

  The installation developed by the Applicant aims to solve all of these disadvantages.

  The invention relates to a one-piece installation for water treatment comprising a settling unit through which flows from bottom to top, the raw water to be treated, the settling unit being positioned above a device filtration through which passes, by gravity, water decanted.

  This installation is characterized in that the settling unit is hermetically separated from the filtering device by means of a partition and in that it is provided with a pipe connecting the top of the decanter to the top of the filtration system, in which circulates the decanted water.

  In other words, the invention consists in separating the clarifier from the filtration system so that the said settling tank is not in the submersion chamber of the filter, which has at least three advantages respectively: decantation or the filtration system is autonomous, which means that in case of failure of a module, simply replace said module, - the passage of the decanted water to the filtration system is carried out at constant speed and controlled and therefore allows effective treatment the backwash of the filter does not result in the washing of the settler, which means that the decanter separators permanently have a mud web to ensure a pre-settling step .

  In practice, the decantation unit has: in its upper part, separators for separating the raw water from the sludge it contains and a chute for recovering decanted water overcoming the separators, said chute opening into the pipe connecting the top of the filtration system, - in its lower part, a raw water supply pipe to be treated and a sludge extraction system.

  Moreover, to allow a more efficient decantation than that obtained with the systems of the prior art and in particular that described in the document FR-A-2,374,068, the Applicant has developed new separators in the form of identical corrugated plates having a front face and a reverse face, the corrugations defining oblique channels parallel to each other. In addition, the plates are contiguous to each other so that the front face of the plate n is in contact with the front face of the plate n + 1, and the back side of the plate nH-2 is in contact with the back side of the plate n + 1, and so on.

  According to another characteristic, the oblique channels are oriented at an angle of 60 relative to the vertical.

  Moreover, to further optimize the settling phenomenon by increasing the contact area, each oblique channel has parallel corrugations or indentations formed in the direction of progression of the liquid to be treated.

  To the knowledge of the Applicant, such separators have never been described, including in the field of water treatment, especially for decantation.

  Therefore, the invention also relates to the separators described above, as well as the use of these separators in a fluid decantation unit. It also relates to a decanter with said separators.

  According to another characteristic, the settling unit of the plant of the invention is provided with a sludge extraction system in the form of a collector arranged at the periphery, the separators, and the bottom of which is positioned a pipe with holes, the pipe being connected to a suction system. In other words, and unlike the system proposed in the prior art, the sludge extraction means of the invention makes it possible to extract the portion of the sludge recovered by gravity at the bottom of the collector, and this in the absence any washing of the separators. As a result, there is a permanent mud wall in suspension under the separators.

  As regards the filtration system, it is conventionally composed of a nozzle plate on which at least one filter layer rests, an evacuation chamber being arranged under said plate. Of course, the filter layers and their composition will vary depending on the chemical composition of the liquid to be treated.

  To allow a homogeneous distribution of the decanted liquid from the top of the decanter, the pipe connecting the decanter leads to the top of the filtration system in a water distribution trough.

  Finally, the installation of the invention is advantageously equipped with a chemical pre-treatment unit for raw water. In practice, this pre-treatment unit is located upstream of the settling tank and contains means for storing, mixing and agitating the chemicals necessary for treating the water. This unit also features pumps and control valves to manage the flow rates of each of the chemicals.

  The invention and the advantages resulting therefrom will emerge more clearly from the following exemplary embodiments in support of the appended figures.

  Figure 1 is a schematic perspective view of the installation of the invention.

  Figure 2 is a sectional view of the separators contained in the decanting unit.

  In Figure 1, there is shown schematically the installation of the invention. This installation comprises three separate modules, respectively a settling unit (1) connected to a chemical pretreatment device (2), the decantation module being positioned above a filtration system (3). In this exemplary embodiment, the vessel in which the settling and filtration elements are integrated is made of stainless steel and is circular in shape.

  According to a first characteristic of the invention, the settling unit (1) is hermetically separated from the filtration system (3) by means of a partition (4). Therefore, the passage of the decanted water to the filter is performed by means of a pipe (5) connecting the top of the decanter at the top of the filtration system.

  The settling unit will now be described in more detail.

  From bottom to top, this unit is equipped in its bottom, a sludge collector (6) at the bottom of which is positioned a pipe (7) sludge evacuation, itself connected to a suction pipe (8). ). In practice, the sludge evacuation pipe (7) is provided throughout its length with perforations allowing the passage of sludge by suction.

  Then, located substantially above the settler, the inlet pipe (9) of the raw water to be treated. Advantageously, the pipe is preceded, as already said, by a chemical pre-treatment unit (2), which incorporates the means necessary for storing, mixing and dosing the chemicals. Of course, the choice of chemicals will be made according to the physicochemical nature and type of pollution of the raw water to be treated. The raw water thus arriving near the bottom of the settling unit, then goes up into the tank to pass through the decantation system itself, consisting of separators. This zone is shown schematically in FIG. 1 by the reference (10).

  These separators are shown in section in FIG.

  They are constituted by the association of corrugated plates (11) contiguous to each other. More specifically, the corrugations of each plate form oblique channels (12) parallel to each other, making an angle of 60 with the vertical. If we define a front face and a reverse face for each of the plates (11), the plates are contiguous in the following manner.

  The front face of the plate n is contiguous to the front face of the plate n + 1, while the reverse side of the plate n + 2 is contiguous with the reverse side of the face n + 1, the front face of the plate n + 3 then being contiguous to the front face of the plate n + 2. Such a conformation makes it possible to optimize the flow of water, and thus the settling by increasing the contact surface. In terms of process, a single mold is sufficient to manufacture each of the plates, since their association is obtained by turning one plate over the other. To further optimize the path of the water to be treated, and therefore the effectiveness of the settling, each channel has corrugations arranged in the direction of the flow of water. These undulations (13) appear clearly in FIG.

  Above the separators, the decanted water is recovered by means of a circular chute (14), also provided with not shown perforations.

  This chute is connected to the pipe (5) so as to allow the passage of the decanted water in the filtration unit (3). The water therefore arrives in this filtration unit through the pipe (15). This pipe is open so as to allow the water supply of the filter overflow. Under this pipe, is represented the actual filter element (16) composed of one or more layers of granular material chosen, again, depending on the nature of the liquid to be treated.

  The filter layer or layers are supported by a plate (17) through which nozzles (18) pass through which the water passes into the manifold (19). The clean water 20 is then discharged through the pipe (20).

  As already stated, the installation of the invention is more particularly used for the supply of drinking water to low population areas, up to 16,000 inhabitants. In practice, the filtration rate will be between 5 and 100 m3 / h as needed. To do this, the dimensions of the installation can vary advantageously, exclusively in terms of diameter, so as not to generate systems at too great height. In addition, the characteristics of the separators are such that they make it possible to improve the efficiency of the decantation compared to the known systems for similar dimensions, thus making it possible to reduce the size of the installation.

  The operation of the installation is very simple. In practice, the water to be treated first goes into the chemical pre-treatment unit to change the physicochemical characteristics of the liquid for decantation and filtration. In particular, the water may be premixed with a flocculant so as to promote settling. When the water reaches the bottom of the decanter, the level of it rises to cross then the convolutions created by the separators. Depending on the amount of sludge deposited in the separators, part of them falls by gravity into the bottom of the collector and is then sucked in cycles. In other words, a veil of sludge subsist under the separators to ensure a first decantation step. Once the raw water passed through the separators, it is recovered by the chute located at the top of the settling unit, the decanted water is then transmitted to the top of the filtration system. The decanted water then travels the filtering layers from top to bottom, to be transmitted into the clean water collector through the nozzles arranged in the tray, support filter layers.

  According to an essential characteristic, the cleaning of the settling unit is obtained solely by the combination of the sludge collector and the suction pipe. So there is never against washing separators, which allows to obtain a permanent slime web under said separators. On the other hand, the backwashing of the filtration system is possible by sucking clean water through the pipe (20), then discharging the dirty water through the pipes (15) and (5).

  The invention is the advantages that ensue from the above description. In particular, the hermetic separation of the settling and filtration systems is noted, which makes it possible to maintain a sludge web on the surface of the separators, and thus to ensure a pre-settling step. In addition, the module system makes it possible to change one of the modules in case of failure, without immobilizing the installation.

Claims (10)

  1 / Monoblock installation for water treatment comprising a settling unit through which the raw water to be treated circulates from bottom to top, the settling unit being positioned above a filtration device through which gravity-settling water, characterized in that the settling unit is hermetically separated from the filtration device by means of a partition and in that it is provided with a pipe connecting the top of the settling tank to the top of the filtration system in which circulates decanted water.   2 / Apparatus according to claim 1, characterized in that the decantation unit has: - in its upper part, separators for separating the raw water sludge it contains, is a water recovery trough decantée overcoming the separators, the chute opening in the pipe communicating with the top of the filtration system, in its lower part, a raw water supply pipe and a sludge extraction system.   3 / Apparatus according to claim 2, characterized in that the separators are in the form of identical corrugated plates having a front face and a back side, each corrugation defining oblique channels parallel to each other, the plates being contiguous with each other. so that the front face of the plate n is in contact with the front face of the plate n + 1, and the back side of the plate n + 2 is in contact with the reverse side of the plate n + 1.   4 / Apparatus according to claim 3, characterizing that the oblique channels are oriented at an angle of 60. lo   5 / Apparatus according to one of claims 3 or 4, characterized in that each oblique channel has parallel corrugations arranged in the direction of progression of the liquid to be treated.   6 / Apparatus according to claim 2, characterized in that the sludge extraction system is in the form of a collector arranged at the periphery of the separators at the bottom of which is positioned a pipe with holes, the pipe being connected to a suction system.   7 / Apparatus according to claim 1, characterized in that the filtration system is composed of a nozzle plate on which rests at least one filter layer, an evacuation chamber being arranged under said plate.   8 / Apparatus according to claim 7, characterized in that the pipe 15 from the top of the settler opens into a water distribution trough on the surface of the filtration system.   9 / Apparatus according to one of the preceding claims, characterized in that it further comprises a chemical pre-treatment unit raw water positioned 20 upstream of the decanter.   10 / installation claim 9, characterized in that the pre-treatment unit contains means for storing, mixing and stirring chemicals.