WO2008037872A2

WO2008037872A2 - Basin for treating waste water using macrophyte beds

Info

Publication number: WO2008037872A2
Application number: PCT/FR2007/001523
Authority: WO
Inventors: Daniel Bonnotte
Original assignee: Aquariolis Sarl
Priority date: 2006-09-27
Filing date: 2007-09-19
Publication date: 2008-04-03
Also published as: FR2906239A1; WO2008037872A3; FR2906239B1

Abstract

The invention relates to a basin for treating waste water that comprises a plurality of macrophyte-bed purification tanks. Each tank comprises a first set of waste water distribution pipes (22, 24) arranged above the tank for distributing the waste water above the tank and a first set of purified water draining pipes (26, 28, 30) provided at the bottom of the tank for recovering the purified water, as well as a second set of waste water distribution pipes (32) located under the surface of the macrophyte bed and upstream relative to the tank for distributing the waste water into the tank and a second set of purified water draining pipes (34) provided at the bottom of the tank and downstream thereof for recovering the purified water. Valves (36, 38, 40, 42, 44, 52, 56) are provided for either connecting the inlet of the waste water to the first set of distribution pipes and for connecting the outlet of the purified water to the first set of draining pipes when the tank is used as a vertical filter, or for connecting the inlet of the waste water to the second set of distribution pipes and for connecting the outlet of the purified water to the second set of draining pipes when the tank is used as a horizontal filter.

Description

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Treatment basin: waste water by macrophytes

TECHNICAL FIELD The present invention relates to the treatment of wastewater in sewage lagoons and relates in particular to a sewage treatment pond by macrophyte beds.

State of the art

Today, urban wastewater treatment has become a problem of utmost importance as the volume of wastewater continues to grow. Apart from individual septic tanks for places not having any sewer, this purification is done in sewage treatment plants by processes using microorganisms in the majority of cases.

Bacteria beds are generally used after decantation of suspended solids. The bacterial beds can be on disks supporting the bacteria to activate the degradation of the effluents while ensuring oxygenation of the support. Unfortunately, there is the problem of eliminating sludge which generally accumulates upstream before treatment with bacteria.

There is currently a system to solve the above problem, it is the use of macrophyte beds where the purification is done by the combined action of plants and micro-organisms in a filter bed.

Microorganisms that are aerobic bacteria and / or anaerobic bacteria have the main function of degrading pollutants. It is these bacteria that ensure the oxidation-reduction processes and generate, thanks to the degradation of the pollutants, the energy necessary for biosynthesis. In addition, the bacteria mineralize the nitrogen and phosphorus compounds and make them assimilable by the plants, and ensure the nitrification / denitrification reactions. The plants in the macrophyte bed serve to support the development of bacteria and also promote their development through the shading and hygrometry they maintain. But above all, they assimilate the molecules resulting from the "shearing" of the molecules of pollutants by the bacteria. In addition, plants have other functions. Thus, they prevent clogging of the upper part of the filter and allow a good migration of water. Their roots can secrete antibiotics contributing to the elimination of pathogenic microorganisms. Finally, they are also used to integrate facilities into the landscape and eliminate odors.

There are two types of macrophyte beds, vertical filters and horizontal filters. The vertical filters, which mainly contain aerobic bacteria, have a high oxygenation which, in addition to the elimination of dissolved organic matter, allows good nitrification. On the other hand, if this type of filter makes it possible to treat raw water (that is to say without a settling tank), periods of rest must be provided in order to allow the wetting and mineralization of the organic deposits and thus allow the degradation of organic matter. accumulated during feeding periods. Horizontal filters promote the development of anaerobic bacteria, even if near the roots an aerobic metabolism develops. Powered at very low surface and / or volume loads they allow a good elimination of suspended solids and dissolved organic matter. In contrast, poorly oxygenated, they are not very effective for oxidizing oxidizing degrading materials such as ammonium.

Unfortunately, treatment plants, whether conventional or macrophyte beds, are effective for the treatment of domestic wastewater containing mainly organic matter but remain ineffective for the treatment of effluents with specific pollutants. such as drug residues or inorganic molecules.

Presentation of the invention

Therefore, a first object of the invention is to provide a wastewater treatment tank by macrophyte beds that can be used both as a vertical filter and as a horizontal filter

Another object of the invention is to provide a sewage treatment pond composed of a plurality of macrophyte bed treatment tanks for treating water containing specific pollutants such as drug residues, or certain industrial pollutants.

Yet another object of the invention is to provide a research pool for combining treatment tanks macrophyte beds to achieve an effective purification of wastewater containing one or more medical or industrial pollutants.

The object of the present invention is therefore a wastewater treatment tank per macrophyte bed comprising a wastewater inlet located upstream of the tank, an outflow of purified water located downstream of the tank and a macrophyte bed between the tank. entry and exit comprising macrophyte plants and aerobic or anaerobic bacteria, these bacteria having the function of transforming the molecules of pollutants contained in the wastewater into molecules that can be assimilated by macrophyte plants and macrophyte plants whose function is to promote development of bacteria and assimilate assimilable molecules. The bin comprises, firstly, a first set of distribution pipes located above the tank and for distributing the wastewater vertically above the macrophyte bed and a first set of drainage pipes located at the bottom of the macrophyte bed responsible for recovering the purified water by the macrophyte bed, on the other hand, a second set of distribution pipes located under the surface of the macrophyte bed upstream of the tank and for distributing the wastewater in the tank and a second set drainage pipes located at the bottom of the macrophyte bed downstream of it and responsible for recovering the purified water by the macrophyte bed. The tray includes a plurality of valves operable to connect the wastewater inlet to the first set of distribution pipes and connect the outlet of the treated water to the first set of drainage pipes so that the tank operates by filtering. vertical with mainly aerobic bacteria, either connecting the wastewater inlet to the second set of distribution pipes and connecting the outlet of the treated water to the second set of drainage pipes so that the tank operates by horizontal filtration with mainly anaerobic bacteria.

Brief description of the drawings

The objects, objects and features of the invention will become more apparent on reading the following description with reference to the accompanying drawings, in which: FIGS. 1A and 1B show respectively the top view and the section of a purification tank. wastewater according to a preferred embodiment of the invention; Figure 2 is a schematic representation of a wastewater treatment pond at two levels of treatment tanks according to the invention, and; FIG. 3 schematically represents a double basket used for seeding into plants or bacteria in a wastewater treatment tank according to the invention.

DETAILED DESCRIPTION OF THE INVENTION As will be seen later, the pond according to the invention consists of a plurality of identical treatment tanks. A purification tank 10 illustrated in FIGS. 1A and 1B is an aboveground tank with a length of between 2m and 2.5m, with a width of between 0.5m and 0.8m and a height of about 0.5m.

The purification tank 10 contains a layer of rollers 12 at the bottom, then gravel 14 in one or more layers starting with coarse gravel and finishing with fine gravel. Macrophyte plants 16 responsible for assimilating the molecules resulting from the degradation of the pollutants by the bacteria are rooted in the gravel.

Each treatment tank has an effluent inlet pipe 18 and a treated water outlet pipe 20. At the inlet pipe 18, a stitching waiting allows the possibility of connecting a device to inject a product, for example a solution loaded with bacteria, directly into the effluent. According to the preferred embodiment, the wastewater is distributed in the tank used as a vertical filter by means of a set of distribution pipes 22, 24 located above the tank. The treated water is recovered by means of a set of drainage pipes (pipes with holes) placed longitudinally at the bottom of the tank, a pipe 26 or 28 located on each edge of the tank and the third pipe 30 located in the middle of the tank. It should be noted that a different configuration could be used for both wastewater distribution pipes and treated water drainage pipes.

The purification tank 10 can also be used as a horizontal filter. Still according to the preferred embodiment, it comprises a distribution pipe waste water 32 transverse to the purification tank and located upstream thereof, a little below the surface of the gravel, the pipe 32 being identical to a drainage pipe, that is to say with holes . It also comprises a drain pipe 34 downstream of the tank, transverse thereto and located at the bottom of the tank. Note that a different configuration could be used, both for the distribution of wastewater and for the recovery of treated water, provided that the distribution pipes are upstream of the tank and that the drainage pipes are downstream of the tray so that filtering (by anaerobic bacteria) can be done all along the tray. Thus, the distribution of wastewater could be done by a set of several pipes rather than one and the same for the drainage of treated water.

When the purification tank 10 is used as a vertical filter, a valve 36 is opened connecting the inlet of the wastewater 18 to the distribution pipes 22, 24. Likewise, valves 38, 40 and 42 respectively connecting the drainage pipes 26, 28 and 30 to the drainage pipe 34 are in the open position.

When the purification tank 10 is used as a horizontal filter, the valves 36, 38, 40 and 42 are in the closed position. A valve 44 connecting the wastewater inlet 18 to the distribution pipe 32 is in the open position. Note that the valve 44 is in the closed position when the tray is used as a vertical filter.

When the purification tank 10 is used as a horizontal filter, the outlet of the treated water 20 opens into a chamber 46 and is connected to a floor trap 48 so that the treated water comes out of the top of the trap 48 and is The siphon 48 is connected by a rotating sleeve to the outlet pipe 20. In this way, the level of the macrophyte bed can be adjusted in the tray. Indeed, it suffices to rotate the siphon 48 for lowering the outlet height of the treated water and consequently lowering the height of the liquid in the tank 10. A valve 52 which connects the drainage pipe 34 to the outlet pipe of the purified water 20 is in the open position 5 when the tank is used as a horizontal filter.

By cons, if the tray 10 is used as a vertical filter, the siphon 48 is not essential. It is therefore necessary in this case to be able to dismantle the siphon to evacuate the treated water through the discharge outlet 50.

10 the siphon is not removable, which is preferable to avoid manipulation, it is advisable to provide a bypass 54 which recovers the purified water from the drain pipe 34 and sends them directly into the eye 46. A valve 56 connecting the drain pipe 34 to the bypass 54 is

15 then in open position. Note that, in the presence of the bypass 54, the valve 52 is obviously in the closed position. In the absence of bypass, the valve 56 does not exist and the valve 52 is in the open position, whether the tank is used as a horizontal filter or that it is used as a filter

20 vertical.

As mentioned above, one of the aims of the invention is to provide a treatment pond capable of treating wastewater containing specific pollutants such as medicinal residues or

25 industrialists. For a specific pollutant, it is possible that aerobic bacteria are necessary but not sufficient, and that anaerobic bacteria are also necessary but insufficient for the degradation of the pollutant. This is why a basin according to the invention

30 comprises at least one tray configured as a vertical filter followed by a tray configured as a horizontal filter or vice versa.

While a horizontal filter can operate continuously without interruption, it is not the same for a

^'35 vertical filter wherein the work of the bacteria and its regeneration can be effectively assured that if the filter is at rest a part of the time, for example half or 2/3 of the time. It is therefore wise that the wastewater of a vertical pond is made by covering for a day followed by one or two days of rest for example.

According to a preferred embodiment of the invention, a sewage treatment basin consists of several levels following each other each comprising at least two purification tanks so as to be able to configure two tanks respectively as a horizontal filter. followed by a vertical filter or vice versa. A treatment pond according to the invention is illustrated in FIG.

The basin has two levels. A first level consists of 4 parallel bins 60, 62, 64 and 66 and a second level following the first level consists of 3 bins in parallel 68, 70 and 72. Each of the bins is followed by a look represented by a circle, namely the look 46 of Figures IA and IB, this view can receive treated water directly from the tank outlet or via a bypass (shown in dashed lines) as explained above. The 3 trays 60, 62 and 64 of the first level are configured as vertical filters while the tray 66 is configured as a horizontal filter. As has been said previously, only one tray configured as a vertical filter is active, for example the tray 60, while the trays 62 and 64 are at rest. The quiescence is easily achieved by closing the inlet valves of the tray, that is to say the valves 36 and 44 of Figure IA. It should be noted that the wastewater supply is via a sewage injection inlet 74.

Two of the second level bins, namely the bins 68 and 70 are configured as vertical filters, and the third bin 72 is configured as a horizontal filter. Since the second level receives partially cleaned wastewater, it is not necessary that these tanks are at rest 2/3 of the time, but only half the time. It can therefore be considered that the tray 68 is active while the tray 70 is at rest and vice versa.

The two-level basin illustrated in Figure 2 allows all possible combinations of a tray configured as a vertical filter followed by another tray configured as a vertical filter or horizontal filter, or a tray configured as a horizontal filter followed by a bin configured as a horizontal filter or as a vertical filter. Thus, it is possible to make the following bins active, provided that the other bins are inactive or at rest:

1. bin 60 (vertical filter) and bin 68 (vertical filter),

2. Tray 60 (vertical filter) and Tray 72 (horizontal filter), 3. Tray 66 (horizontal filter) and Tray 72 (horizontal filter),

4. Tray 66 (horizontal filter) and Tray 68 (vertical filter).

For certain specific pollutants, it may be necessary to have several bins configured as vertical filters and / or horizontal filters placed one after the other. So we can have a third level after the second level and even a fourth level, and so on. In addition to the treatment of effluents requiring the combination of several tanks in series configured as different filters, a multi-level treatment basin also makes it possible to respond to pollutions that vary over time. One can imagine that some days, there is production of effluents loaded with given medicinal or industrial residues whereas the following day, it is the residue of another drug or another industrial product which is mainly in the effluents.

As seen previously, each purification tank has a discharge outlet 50 (see Figures IA and IB). In order to supply water to treat the tanks of the second level, the evacuation outlets of the tanks of the first level must be at the height of the inlet pipes of the tanks of the second level, and likewise for the exits of evacuation of the tanks of the second level with respect to the pipes of entry bins of a possible third level, and so on. Therefore, it is necessary for the bins of each level to be elevated relative to the bins of the next level. If this is not the case, a pump system must be provided to raise the water supplied to the outlets of the bins at the level of the inlet pipes of the bins of the next level.

The treatment basin which has just been described can also be used as a research basin, that is to say a basin which makes it possible to search the filtration (horizontal filter or vertical filter) best adapted to a specific pollutant, control the effect of this pollutant on bacteria and plants, search and sow the medium by bacteria and plants adapted to the pollutant and finally analyze the effectiveness of a specific bacterium or plant.

It should be noted that the treatment pond described above may be a pond made definitively in full size and in the soil. In this case, the basin can have an area of several tens of m2. Such a basin may be for example a pilot plant for treating polluted effluents, on site (after the primary research phase), or for the treatment of pollutions that vary over time.

In order to seed a purification tank with bacteria (aerobic or anaerobic) and / or plants whose efficiency is to be analyzed, it is advisable to use double baskets shown in FIG. 3. The outer basket 80 is made mesh having mesh size smaller than the size of the gravel in the tray to prevent them from entering the interior of the double basket while allowing water to enter. Cart interior 82 in which the plant 84 has been placed or the bacteria whose efficacy is to be analyzed has an inverse role and must retain the aggregates which have been placed therein, namely the support of the plant or of the bacteria, while letting the water and the root system of the plant pass. The mesh of the inner basket 82 must have a mesh whose diameter is smaller than the size of said granules. Note that this technique can be used to collect the medium or a plant for analysis without destroying at least partially the contents of the tray and disrupt its operation

Claims

1. Wastewater treatment tank (1O) per macrophyte bed comprising a wastewater inlet (18) situated upstream of the tank, an outflow of treated water (20) located downstream of the tank and a macrophyte bed between said inlet and said outlet comprising macrophyte plants and aerobic or anaerobic bacteria in gravel, said bacteria having the function of transforming the molecules of pollutants contained in the wastewater into assimilable molecules by macrophyte plants and macrophyte plants whose function is to promote the development of bacteria and to assimilate said assimilable molecules; said tank being characterized in that it comprises on the one hand, a first set of wastewater distribution pipes (22, 24) located above the tank and for distributing the wastewater vertically above said macrophyte bed and a first set of purified water drainage pipes (26, 28, 30) located at the bottom of said macrophyte bed and responsible for recovering the purified water from said macrophyte bed, and secondly a second set of water distribution pipes; waste water (32) located below the surface of said macrophyte bed upstream of the tank and for distributing the wastewater in the tank and a second set of purified water drain pipes (34) located at the bottom of said downstream macrophyte bed of the latter and responsible for recovering the purified water by said macrophyte bed, and in that it comprises a plurality of valves (36, 38, 40, 42, 44, 52, 56) whose function is - to connect said sewage inlet to said p providing a first set of distribution pipes and connecting said outlet of the treated water to said first set of drainage pipes so that the tank functions by vertical filtering with mainly aerobic bacteria, - either to connect said input water sewage ^• said second set of distribution pipes and connecting said output of treated water to said second set of drainage pipes so that the trough runs through horizontal filter with mainly anaerobic bacteria.

The container of claim 1, wherein said first set of purified water drainage pipes is comprised of longitudinal upstream pipes in val of the trough comprising a pipe located on each of the edges of the trough (26, 30) and a pipe located in the middle of the tank (28), and a transverse pipe (34) and located downstream of said tank.

A container according to claim 1, wherein each of said longitudinal drainage pipes of purified water (26, 28 and 30) is connected to said transverse pipe (34) by a valve (38, 40 and 42) and said cross pipe is connected at said outlet of the purified water (20) by a valve (52).

A tank according to claim 2 or 3, wherein said second set of wastewater distribution pipes consists of a single drain pipe-type pipe (32) located below the surface of said macrophyte bed upstream of the tank and transverse to said tray, and said second set of draining pipes purified water consists of a single drain pipe (34) located at the bottom of said macrophyte bed downstream of the tray and transverse said tray.

5. Tank according to one of claims 1 to 4, further comprising a look (46) into which said outlet purified water (20), said outlet being connected by a rotary sleeve to a floor drain (48) of in order to be able to adjust the level of the macrophyte bed when said tray is configured as a horizontal filter.

A bin according to claim 5, further comprising a bypass (54) connected to a valve (56) at the drainage pipe (34) which recovers the treated water from said drain pipe and feeds directly into said drain pipe look (46) when said tray is configured as a vertical filter.

7. Sewage treatment basin comprising a plurality of purification tanks according to one of claims 1 to 6, consisting of several levels following each other each comprising at least two purification tanks so as to be able to configure two trays respectively in horizontal filter followed by a vertical filter or vice versa.

8. Treatment basin according to claim 7, comprising two levels, the first level comprising in parallel three purification tanks configured as vertical filters (60, 62, 64) and a tray configured as a horizontal filter (66), two of said bins. configured as vertical filters being at rest and the third being active, the second level comprising in parallel two cleaning tanks configured as vertical filters (68, 70) and a tray configured as a horizontal filter (72), one of said bins configured as filters. verticals being at rest and the other being active.

9. Treatment basin according to claim 8 used as a research pool to search for the configuration of horizontal filter bins or vertical filters best suited to a specific pollutant, control the effect of this pollutant on bacteria and plants , to search and sow the medium by bacteria and plants adapted to the pollutant and finally to analyze the effectiveness of a specific bacterium or plant.

10. Processing pond according to claim 9, in which seeding is carried out by means of double baskets, each consisting of an outer basket (80) mesh with meshes of a diameter smaller than the size of the gravel lying in the macrophyte bed to prevent the latter from entering the interior of the double basket while allowing the water to enter, and an inner basket (82) in which the plant (84) or the meshed bacteria has been placed. whose meshes have a diameter smaller than the size of the aggregates serving to support said plant or said bacteria.