WO2017202681A1

WO2017202681A1 - Water treatment process and plant

Info

Publication number: WO2017202681A1
Application number: PCT/EP2017/061962
Authority: WO
Inventors: Sylvain DONNAZ; Maurice MARTAUD
Original assignee: Suez Groupe
Priority date: 2016-05-23
Filing date: 2017-05-18
Publication date: 2017-11-30
Also published as: FR3051460B1; FR3051460A1

Abstract

The invention relates to a plant for treating water, in particular wastewater, comprising at least one first biological treatment unit (6), said unit being supplied by an upstream primary water channel, said unit being discharged by a downstream secondary water channel and sludge channel, characterised in that the plant also comprises a second unit (1, 1a, 1b) comprising a vortex-generating mixing device (10, 10a, 10b), said device being in fluid communication with at least one of the primary water, secondary water or sludge channels (14, 14a, 14b), said plant also comprising an additional fluid feed circuit (13, 13a, 13b) in communication with said channel and/or with the first vortex-generating device. The invention likewise relates to a method for implementing the plant.

Description

WATER TREATMENT PROCESS AND INSTALLATION

The invention relates to the field of water treatment and more particularly to water treatment installations and processes, in particular wastewater treatment systems, comprising at least a first biological treatment unit, the feeding of said unit being ensured by a water treatment line. primary water upstream, the discharge of said unit being provided downstream by a secondary water line and a sludge line.

Traditional dies used in the treatment of primary water lines, secondary water and sludge queues involve steps of coagulation and / or flocculation and / or settling.

Recall that coagulation-flocculation is a physicochemical treatment process of water purification, used for the treatment of potabilization or treatment of waste water. Its principle is based on the difficulty of certain particles to decant naturally: colloids. The colloidal particles are characterized by two essential points: on the one hand, they have a very small diameter (from 1 nm to 1 μm), on the other hand, they have the particularity to be electronegatively charged, generating repulsion forces intercolloïdales. These two points give the colloids an extremely low sedimentation rate. Coagulation-flocculation is a process that allows, in two stages, to overcome this absence of sedimentation. This technique makes it possible to tackle the two characteristics mentioned above, making it impossible to eliminate the colloidal particles naturally. At first, coagulation, by adding metal salts (usually iron or aluminum), eliminates intercolloid repulsions: metal cations (Al ³⁺ and Fe ³⁺ ) bind to colloids and neutralize them. . Colloidal particles can now be grouped together. In a second step, the flocculation makes it possible to tackle the problem of the small diameter of the colloids. The critical point is in fact the mass, which does not allow natural and exploitable sedimentation as part of a treatment. The solution exploited by flocculation is to cause, thanks to the addition of flocculant, an agglomeration of the colloidal particles. Subsequently, this agglomerate of colloids called "floc" has a sufficient mass to be able to decant. The added flocculant is generally a polymer, whether organic or natural, which will act as a glue between the colloids.

These steps are generally performed in conventional coagulation or flocculation reactors, dynamic or static mixers, or by online dilution.

In all cases the volumes used must be sized according to the following parameters in order to ensure a good dispersion of the coagulant and the flocculant in the queue to be treated as well as the good formation of the flocs:

- flow rate to be treated (m ³ / h)

- temperature of the water to be treated (° C)

- μ: dynamic viscosity of water depending on the temperature

- contact time or hydraulic residence time (seconds or minutes)

- average speed gradient (G in s ^"1 , G = Root [P / (V, μ)])

- power actually dissipated (P in kW, P = G ² .Vp)

- factor Gt (Gt = G x contact time, with G in s ^"1 , t in seconds) As a reminder, the notion of velocity gradient reflects the evolution of the velocity within the fluid. Spatial variation of the flow velocity This magnitude depends on the applied shear stress and the nature of the fluid.

As a reminder, the factor Gt is a power code per unit volume of the flow of a fluid. It also makes it possible to determine the performance of the dynamic mixers used in the stirring tanks. The factor Gt = G x contact time; with G in s ^"1 , t in seconds).

However, the reactors used although bulky, require significant contact time. The generally accepted contact times are as follows: Flocculation Coagulation Unit

Temperature ° C 0-3 3-7 7-15> 15 <5> 20

Time of min 1-3 1-2 0.5-1 0.08-0.5 30 15 contact

(values

minimum)

Time of s 60-60-120 30-60 5-30 1800 900 contact 180

(values

minimum)

For contact times of between 30 seconds to 30 minutes, the average rate gradient to be applied for the coagulation and flocculation steps is from 300 s ^-1 to values less than 200 s ^-1 . For contact times between 5 and 30 seconds (case of water temperature> 15 ° C), the average speed gradient to be applied for the coagulation and flocculation steps is between 400/500 s-1 and 250 / 300 s-1.

In addition, the coagulation and flocculation processes implement speed gradients G which consume a lot of energy.

Thus, in the case of dynamic mixers, it is generally used a cylindrical vessel provided with a mechanical stirring, (electrical energy consumed as a function of the rotation of an axis on which are fixed variable geometry blades). Thus, dynamic mixers involve mechanical equipment with rotating machines and blades requiring significant energy input (electric motors) and the maintenance of such equipment (OPEX).

In the case of static mixers, there is a major disadvantage consisting in the loss of hydraulic loads (and therefore energy losses). They are also very sensitive to clogging (mineral powders, fibers, micro-fibers, tows, lumps, etc.). These static mixers are intended to promote exchanges between the reactive products and the fluids via baffles, profiles or a packing which cause the increase of the losses of charges within the transported fluid as well as risks of nuisance plugging (as a function of the fluid passing through) which are at the origin of production stoppages and maintenance interventions. These mixers are not compatible and reliable with all types of fluid.

Online dilution systems use a water line perpendicular to the polymer dosing line to dilute the solution before injection. These systems are less sensitive to clogging because the fluid remains filtered water but they consume pumping energy and / or drinking water.

The object of the invention is therefore to eliminate all or some of the disadvantages mentioned above by means of units comprising a device generating a vortex. The object of the invention is to reduce the consumption of reagents (chemical or bio-sourced) by promoting the dispersion of the reagent at the injection point in the reaction volume of the process in question, this volume being able to be coagulation and flocculation tanks ( primary physicochemical settling in urban wastewater with reagents such as iron or aluminum salts and polymer), biological reactors by injection of methanol, sludge thickening and dewatering units (injection of polymers), chlorination chambers drinking water with bleach.

The invention also aims to reduce energy consumption by eliminating in particular rotating blade installations, and also aims to reduce the volume of the reactors.

More particularly, the subject of the invention is a water treatment plant, in particular a wastewater treatment plant, comprising at least a first biological treatment unit, the supply of said unit being provided by an upstream primary water line, evacuation of said unit being provided by a secondary water line and a sludge line downstream, characterized in that the installation further comprises a second unit comprising a vortex generator mixing device, said device being in fluid communication at least one of the primary, secondary or muddy water lines, said installation comprising also an additional fluid supply circuit in communication with said line and / or with the vortex generating device, the vortex generator mixing device being provided with a common outlet for evacuating the intimate mixture between the additional fluid and the water or mud in the line, formed in the mixing device.

Optional features of the invention, complementary or substitution are set forth below.

According to certain features, the average velocity gradient at the outlet of the first vortex-generating mixing device may be greater than 400 sec ^-1 , while the factor Gt is greater than 6000, for a duration t ranging between 10 s and 30 s.

According to other features, the vortex generator mixing device may be a substantially cylindrical drop pit with a feed line forming an alpha angle with the horizontal section of the well.

The drop shaft may be a cylinder with a diameter of between 0.5 m and 6 m, a height of between 0.5 m and 3 m, and a discharge diameter of between 65 mm and 2.6 m, and alpha angle between 0 and 45 degrees, the angle alpha being the angle formed by the arrival of fluid from primary water lines, secondary water or sludge with the tangent to the section of the cylinder.

The angle alpha may advantageously be zero so as to form a tangential admission of the fluid into the drop well.

The vortex generator mixing device may be a drop pit, the evacuation of the intimate mixture formed between the additional fluid and the water or the sludge of the line during the crossing of the drop well, is effected through an outlet as close as possible to the bottom of the well, or even the bottom of the well, to maximize the vortex course. The additional fluid supply circuit may be in communication with said queue and / or with the inlet of the vortex generating device.

The installation may further comprise a dissipator device energy downstream of the vortex generator device, capable of transforming the turbulent regime of the fluid from the vortex generating device, in a laminar regime.

The energy dissipation device can be included in the list defined by the filtration grids and the baffles.

The second unit can form a unit included in the list defined by sludge thickening units, sludge dewatering units, primary and secondary physico-chemical settlers, pre-anoxic reactors, contact tanks, storage tanks, decanters.

The installation may comprise a first mixing device generating a coagulation vortex, a second mixing device generating a vortex flocculation, and a third device included in the list defined by the tranquilizers, decanters, filtration chambers

The subject of the invention is also a process for the treatment of water, in particular waste water, comprising at least a first biological oxidation stage in a biological treatment unit, the supply of said unit being provided by a primary water line. , the evacuation of said unit being provided by a secondary water line and a sludge line, characterized in that the method comprises a second step during which the passage of the primary or secondary water line or the sludge line, additivated with an additional fluid in a vortex generating device, so as to generate an intimate mixture, the additivation with the additional fluid being practiced in the primary or secondary water line or in the sludge line , and / or in the first vortex generating device.

According to certain characteristics, the average speed gradient G and the factor Gt may be respectively greater than 400 s-1 and 6000 for a time t between 10 s and 30 s, at the output of the vortex generating device. According to other characteristics, after passing through the vortex generating device of the primary or secondary water line or the sludge line, added with the additional fluid, it is possible to proceed to a third step of passing the intimate mixture thus obtained in a second energy dissipating device, so as to transform the turbulent regime of the fluid from the first vortex generating device, in a laminar regime.

The second step can also be a step of coagulation or flocculation of the sludge line.

The second step of coagulation or flocculation of the sludge line may be completed by a thickening or dehydration step.

The second step may be a step of coagulation or flocculation of the secondary water line.

The second step of coagulation or flocculation of the secondary water line may be completed by a decantation step or capture on filter.

The second step may be a pre-anoxic step of the primary water line, said line being additivated with methanol.

The second step may be a disinfection step of the secondary water line supplying a contact and storage tank, said line being additive with an oxidant.

Other advantages and particularities of the invention will appear on reading the detailed description of implementations and non-limiting embodiments, and the following appended drawings:

FIGURES 1 and 2 each correspond to a schematic representation of the invention according to distinct embodiments,

FIGURES 3, 4, 5 each correspond to implementations of the invention according to particular applications,

FIGURES 6 and 7 each correspond to test results. For the sake of clarity and brevity, the references in the figures correspond to the same elements.

The embodiments described above being in no way limiting, one may in particular consider variants of the invention comprising only a selection of features described, isolated from the other features described (even if this selection is isolated within a sentence comprising these other characteristics), if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art. This selection comprises at least one characteristic, preferably functional without structural details, or with only a part of the structural details if this part alone is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art .

The principle of the invention as shown in Figures 1 and 2, is based on units equipped with vortex generating devices 10, 10a, 10b, respectively fed with secondary or sludge lines 14, 14a, 14b. A reagent 13, 13a, 13b is generally injected either directly into the queue or directly into the vortex generating device.

These vortex generating devices promote the intimate mixing of at least two fluids and maximize the mixing energy required for coagulation and / or flocculation through the recovery of hydraulic energy.

The invention uses the vortex hydraulic energy that is generated by the geometry of the device and the fluid transported for the dispersion of a reagent and for the efficient mixing between the fluid and the reagent. The vortex generator mixing device homogenizes the fluid and the reagent by reusing the hydraulic energy coming from upstream.

In these vortex-generating mixing devices according to the invention, there are no longer any rotating blades to ensure mixing, since it is the vortex, that is to say the vortex which originates in the fluid. flow in said device, which provides this mixing function.

In these vortex-generating mixing devices according to the invention, the additional fluid supply circuit to be mixed with the main fluid is necessarily in communication with the means for supplying the main fluid to the vortex-generating mixing device and / or with the inlet of the vortex generator mixing device.

Thus, in FIG. 2, the vortex generator mixing device 10a recovers the energy sent by the pump 15. Similarly, the vortex generator mixing device 10b recovers the gravitational energy of the file 14b.

Preferably, the average velocity gradient at the outlet of the first vortex-generating mixing device is greater than 400 s ^-1 , whereas the factor Gt is greater than 6000, for a duration t ranging between 10 s and 30 s.

The notion of velocity gradient reflects the evolution of the velocity within the fluid. The velocity gradient describes the spatial variation of the flow velocity. This magnitude depends on the applied shear stress and the nature of the fluid.

The Gt factor is a power figure per unit volume of fluid flow. It also makes it possible to determine the performance of the dynamic mixers used in the stirring tanks. The factor Gt = G x contact time; with G in s ^"1 , t in seconds).

Thus and as shown in Figures 6 and 7, the speed gradients created are important since for a contact time of 10.6 seconds (or 40 m3 / h), the speed gradients G are 650 to 800.

The speed gradient G is a function of the flow rate involved and the dynamic viscosity (dependent on the temperature of the water or the sludge). For the same volume of reactor-mixer, the speed gradient G involved will evolve as a function of the fluid temperature and the flow rate admitted (see Figure 7).

FIG. 6 shows the evolution of the velocity gradient of a vortex generator as a function of the residence time for different given temperatures. The area defined by the rectangle constitutes the operating domain.

FIG. 7 shows the evolution of the speed gradient of a 118 L vortex generator mixing device as a function of the admitted flow rate for various given temperatures. The area defined by the circle brings together the target operating points.

By way of comparison, the rate gradients used for the conventional coagulation and flocculation mixing tanks are less than or equal to 200 s ^-1 for a coagulation vessel at the contact time of 3 min (Gt factor of about 36,000). and for a flocculation tank with a contact time of 15 min (Gt factor of about 180,000). contact time of 10 to 30 seconds and a range of factor Gt from 6,000 to 14,000, the vortex-generating mixing device creates a velocity gradient G allowing to renew the reaction volume ferry from 3 to 7 times more than the zones of traditional mixing used for coagulation-flocculation.

According to a preferred embodiment, the vortex-generating mixing device is a reactor of substantially cylindrical or frustoconical shape with a supply line 12 forming an angle alpha with the tangent to the horizontal section of the well.

Advantageously, the reactor is a cylinder with a diameter of between 0.5 m and 6 m, a height of between 0.5 m and 3 m, a discharge diameter of between 65 mm and 2.6 m, and an angle of alpha between 0 and 45 degrees, the angle alpha being the angle formed by the arrival of the fluid from the primary water lines, secondary water or sludge with the tangent to the section of the cylinder. In this way, a residence time of between 10 and 30 seconds can be achieved, as well as a velocity gradient greater than 400 s ^-1 .

By way of example, for a minimum flow rate of 40 m ³ / h, a speed gradient G = 685 s ^-1 and a contact time T = 9.2 s are obtained, to obtain a GT = 6296.

For a maximum flow rate of 15,000 m ³ / h, with a height of 2.5 m and a diameter of 4.6 m, a speed gradient G = 1470 s ^"1 and a contact time T = 10.0 s, to obtain a GT = 14663.

For a maximum flow rate of 15,000 m ³ / h, with a height of 3 m and a diameter of 6 m, a speed gradient G = 1127 s ^"1 and a contact time T = 20.4 s are obtained to obtain a GT = 22950.

In a preferred embodiment, the arrivals of the line and the reagent are positioned tangentially to the horizontal section of the vortex generating device. In this way, it promotes the formation of the vortex in the device of the type "sink" on the one hand and above all, it also ensures a dispersion and a distribution of two fluids effective and homogeneous within the device.

According to two variants, the reagent can be injected perpendicularly to the line or directly into the vortex generating device, opposite the arrival of the line. The vortex generator mixing device may be is a hydraulic device consisting of a geometric profile allowing the tangential admission of the line and the reagent and the generation of a hydraulic vortex according to the equation of the P. Ackers drop well. and E. Crump. The evacuation of the intimate mixture formed between the additional fluid and the water or mud of the line during the crossing of the drop well, is effected through an outlet arranged as close as possible to the bottom of the well, even at the bottom of the well, to maximize the path of the hydraulic vortex. In other words, the lengthening of the path of the hydraulic vortex makes it possible to make the mixture between the additional fluid and the water or mud in the line, even more intimate.

For the definition of the fall well, reference may be made to the P. Ackers and E. Crump fall well as defined in the article by Markus H. Kellenberg "Wirbelfallschachte in der Kanalisationstechnik" of issue 98 "Mitteilungen der Versuchsanstalt fur Wasserbau, Hydrology und Glaziologie "(Zurich, 1988).

As an example, for a flow rate of 40 m ³ / h and a 100 L reactor allowing the generation of a vortex according to the drop well of P. Ackers and E. Crump, and for a temperature of 15 ° C, the speed gradient G is equal to 699 s ^-1 for a contact time of 9.0 seconds The factor Gt of this embodiment according to the invention is equal to 6,300.

The following calculations express the results of the sizing parameters of coagulation and flocculation reactors for the traditional field of application:

Example: Unit Coagulation Flocculation Results for 40

m ³ / h

Temperature ° C 3 7 15> 15 <5> 20

Contact time min 3 2 1 0.5 30 15

Volume L 2000 1333 667 333 20000 10000

P absorbed in water kW 0.15 0.14 0.06 0.03 1.5 0.5

Speed gradient s-1 216 272 251 251 223 224

Gt - 38880 32640 15060 7530 401400 201600

The traditional design of the reactors or coagulation and flocculation mixing tanks therefore implies, when the contact times are between 30 seconds and 30 minutes, an average rate gradient to be applied for the coagulation and flocculation steps of between 300 and 30 seconds. ^"1 and values less than 200 s ^{" 1} .

For contact times between 5 and 30 seconds (in the case of a water temperature> 15 ° C), the average speed gradient to be applied for the coagulation and flocculation steps is between 400/500 s ^"1 and 250/300 s ^"1 .

The following calculations express the results of the sizing parameters for a vortex-generating mixing device:

Example: Results Generator Device Unit

for 40 m ³ / h vortex

Temperature ° C 3 7 15 20

Contact time s 10.6 10.6 10.6 10.6

Volume L 118 118 118 118

P absorbed in water kW 0.065 0.065 0.065 0.065

Speed gradient s-1 587 626 699 740

Gt - 6224 6641 7407 7850

Thus, the velocity gradient generated by the vortex devices is maximal, which significantly favors the homogenization of a reactive agent (mineral or organic) in the transferred fluid (secondary water line or sludge line).

According to an improvement of the invention and as represented in FIGS. 1 and 2, the unit further comprises a power dissipating device 11, 11a, 11b downstream of the vortex generator device, capable of transforming the turbulent regime of the fluid from the vortex generating device, laminar regime.

The energy dissipating device enables the recovery and dissipation of the hydraulic energy induced by the vortex generating device. The energy dissipation device may be embodied by filtration grids, baffles, and also tranquilizers. The term "tranquilizer" means a device capable of breaking the turbulent regime acquired during the passage of fluid in the vortex generating device, such as a cylinder for a decanter operating ideally for mirror speeds of less than 90 m / h and which receives the mixture of fluids in its enclosure to dissipate the residual hydraulic energy before entering a downstream filter collection unit or decantation.

Figures 3, 4 and 5 show schematically possible implementations of units comprising a vortex generator mixing device and an energy dissipating device.

More particularly in each FIG. 3, 4, 5, there is shown a biological treatment unit 6, fed by a primary water line in upstream. The evacuation of said unit is ensured by a secondary water line FE and a downstream sludge line FB. Figure 3 relates to the treatment of the secondary water line while Figures 4 and 5 relate to the treatment of the sludge line.

In Figure 3, two units 2 and 3 are arranged successively downstream of the unit 6 and receive the stream FE for treatment. Each of the units comprises a vortex generating device respectively la, lb in fluid communication by means of a pipe 12 with the secondary water line for the first device itself in fluid communication with the second.

Each of the vortex generating devices is fed with a secondary fluid that can flow either directly into the supply lines of the secondary water line, or into the vortex generating devices.

The secondary fluid supply preferably takes place perpendicular to the stream or directly in the vortex generating device, opposite the arrival of the queue.

The first vortex generator mixing device is supplied with secondary fluid of the "coagulation agent" type while the second vortex generator mixing device is supplied with secondary fluid of the "flocculation agent" type. Thus, the units 2 and 3 form for the first a coagulation reactor and for the second a flocculation reactor.

In terms of process, the treatment of water, particularly wastewater, comprises at least a first biological oxidation step in the biological treatment unit 6 fed by a primary water line. This follows a second step during which the passage of the secondary water line, additivated with a coagulation agent in a first vortex generating device, so as to generate an intimate mixture. The additivation with the additional fluid being practiced in the secondary water line or directly in the first vortex generating device. This follows a third step during which the passage of the secondary water line, additivated with a flocculating agent in a second vortex generator device, so as to also generate an intimate mixture. Advantageously, the vortex generating devices are designed and dimensioned so that the average speed gradient G and the factor Gt are respectively greater than 400 s ^-1 and 6000 for t between 10 s and 30 s, at the output of the generating device. vortex.

At the end of the passage of the secondary water line in the vortex generating devices, the water thus treated is conveyed to a decanter or a filtering unit 4.

In the case where the water thus treated is conveyed to a decanter, it is advantageous to add before passage into the settler, a passage in a device for dissipating energy.

In the case where the water thus treated is conveyed to a filter-collecting unit, the passage into an energy-dissipating device is not necessary.

Of course, at the end of each of the passages of the queue in the vortex generating devices, it is advantageous to implement a passage in a device for dissipating energy in order to regain a quasi-laminar flow.

In FIG. 4, a unit 3 is disposed downstream of the unit 6 and receives the sludge line FB for treatment. The unit comprises a vortex generator mixing device 1 in fluid communication by means of a pipe 12 'with the sludge line. The vortex generator mixing device is fed with a secondary fluid of the "flocculation agent" type which can lead directly into the sludge feed lines or into the vortex generating device. Thus, the unit 3 forms a flocculation reactor.

In terms of process, the treatment of water, particularly wastewater, comprises at least a first biological oxidation step in the biological treatment unit 6 fed by a primary water line. This follows a second step during which the passage of the sludge, additivated with a flocculating agent in a vortex generating device, so as to generate an intimate mixture. The additivation with the additional fluid being practiced in the sludge line or in the first vortex generating device.

Advantageously, the vortex generator mixing device is designed and sized so that the average speed gradient G and the Gt factor are respectively greater than 400 s ^"1 and 6000 for t between 10 s and 30 s, output of the vortex generating device.

At the end of the passage of the sludge line in the vortex generating device, the sludge thus treated is conveyed to a dewatering unit 5, provided for example with grid filters or band filters.

Of course, at the end of the passage of the queue in the vortex generating device, it is advantageous to implement a passage in an energy dissipation device to find a quasi-laminar flow.

In FIG. 5, two units 2 and 3 are arranged successively downstream of the unit 6 and receive the sludge line FB for treatment. Each of the units comprises a vortex generating device respectively 1a, 1b in fluid communication by means of a pipe 12 'with the sludge line for the first device itself in fluid communication with the second. Each of the vortex generating devices is fed with a secondary fluid that can flow either directly into the feed lines of the sludge line or into the vortex generating devices. The first vortex generator mixing device is supplied with secondary fluid of the "coagulation agent" type while the second vortex generator mixing device is supplied with secondary fluid of the "flocculation agent" type. Thus, the units 2 and 3 form for the first a coagulation reactor and for the second a flocculation reactor.

In terms of process, the treatment of water, particularly wastewater, comprises at least a first biological oxidation step in the biological treatment unit 6 fed by a primary water line. A second step follows during which the sludge line, additive with a coagulation agent, is passed through a first vortex generating device so as to generate an intimate mixture. The additivation with the additional fluid being practiced in the sludge line or in the first vortex generating device. This follows a third step during which the passage of the sludge line, additivated with a flocculation agent, is carried out in a second vortex generating device, so as to also generate an intimate mixture.

Advantageously, the vortex generating devices are designed and sized so that the average velocity gradient G and the factor Gt are respectively greater than 400 s ^-1 and 6000 for t between 10 s and 30 s, at the output of the vortex generating device.

At the end of the passage of the sludge line in the second vortex generating device, the sludge thus treated is conveyed to a dewatering unit 5, which may be provided with grid filters or band filters.

As previously described, the vortex generating devices find their application for:

Flocculant injection in a sludge thickening unit, - Flocculant injection in a sludge dewatering unit, Injection of coagulant and flocculant in a primary or secondary physicochemical settler,

The injection of flocculant into a decanter or into a decanter-thickener,

However, the vortex generating devices are not limited to the aforementioned applications. It is envisaged that they will also find application for:

The injection of methanol into a pre-anoxic chamber of a biological reactor,

- The injection of an oxidizer such as bleach in a contact or storage tank.

In summary, the installation and the method according to the invention implement a vortex using the transport energy of the fluid to be treated (no additional energy consumption dedicated to the mixture). It comprises a device acting as a robust mixer that is not very sensitive to clogging and acts as a fluid homogenizer / regulator.

There is an improvement in the dispersion of the reagent in the line, which allows a reduction in the consumption of reagents. The reagent dosage is optimized thereby reducing the reaction volume of treatment steps such as coagulation and / or flocculation. In summary, the invention can be applied both to the treatment of wastewater channels, just as it can be applied to treatment of potabilization.

Of course, the invention is not limited to the examples that have just been described and many adjustments can be made to these examples without departing from the scope of the invention. In addition, the various features, shapes, variants and embodiments of the invention may be associated with each other in various combinations to the extent that they are not incompatible or exclusive of each other.

Claims

1. Water treatment plant, particularly wastewater, comprising at least a first biological treatment unit (6), the supply of said unit being provided by a primary water line upstream, the evacuation of said unit being provided by a secondary water line and a sludge line downstream, characterized in that the installation further comprises a second unit (1, la, lb) comprising a vortex generator mixing device (10, 10a, 10b ), said device being in fluid communication with at least one of the primary, secondary water or sludge lines (14, 14a, 14b), said system also comprising an additional fluid supply circuit ( 13, 13a, 13b) in communication with said line and / or with the vortex generating mixing device, the vortex generating mixing device being provided with a common outlet for discharging the intimate mixture between the additional fluid and the water or the mud of the f island, formed in the mixing device.

2. Water treatment plant, particularly wastewater, according to claim 1, characterized in that the mean velocity gradient at the outlet of the first vortex generating device is greater than 400 s ^-1 , while the Gt factor is greater than 6000, for a duration t between 10 s and 30 s.

3. Water treatment plant, particularly wastewater, according to any one of the preceding claims, characterized in that the vortex generator mixing device is a substantially cylindrical drop pit with a supply line ( 12) forming an alpha angle with the horizontal section of the well.

4. Water treatment plant, particularly wastewater, according to claim 3, characterized in that the drop pit is a cylinder with a diameter between 0.5 m and 6 m, height between 0.5 m and 3 m m, with a discharge diameter of between 65 mm and 2.6 m, and with an alpha angle of between 0 and 45 degrees, the angle alpha being the angle formed by the arrival of the fluid coming from the lines of water primary, secondary water or mud with the tangent to the section of the cylinder.

5. Water treatment plant, particularly worn, according to claim 4, characterized in that the angle alpha is zero so as to form a tangential fluid inlet in the drop well.

6. Water treatment plant, particularly wastewater, according to any one of the preceding claims, characterized in that the vortex generator mixing device is a drop pit, the evacuation of the intimate mixture formed between the additional fluid and the water or mud in the line during the crossing of the drop well, is made through an outlet as close as possible to the bottom of the well, or even the bottom of the well, to maximize the route of the vortex.

7. Water treatment plant, particularly wastewater, according to any one of the preceding claims, characterized in that the additional fluid supply circuit is in communication with said queue and / or with the inlet of the mixing device vortex generator.

8. Water treatment plant, particularly wastewater, according to any one of the preceding claims, characterized in that the installation further comprises an energy dissipating device (11, 11a, 11b) downstream of the first device vortex generator, able to transform the turbulent regime of the fluid from the first vortex generating device, in a laminar regime.

9. Water treatment plant, particularly wastewater, according to claim 8, characterized in that the energy dissipation device is included in the list defined by the filter grids and baffles.

10. Water treatment plant, particularly wastewater, according to any one of the preceding claims, characterized in that the second unit (1, la, lb) forms a unit included in the list defined by the thickening units of sludge, sludge dewatering units, primary and secondary physico-chemical settlers, pre-anoxic reactors, contact tanks, storage tanks, decanters.

11. Water treatment plant, particularly wastewater, according to any one of the preceding claims, characterized in that the installation comprises a first mixing device generating coagulation vortex, a second mixing device generating vortex flocculation. , and a third device (40) included in the list defined by the tranquilizers, decanters, filtration chambers.

12. A method for treating water, in particular waste water, comprising at least a first biological oxidation step in a biological treatment unit (6), the feeding of said unit being provided by a primary water line, the evacuation of said unit being provided by a secondary water line and a sludge line, characterized in that the method comprises a second step during which the passage of the primary or secondary water line or the line sludge, additivated with an additional fluid in a first vortex-generating mixing device (10, 10a, 10b), so as to generate an intimate mixture, the additivation with the additional fluid being practiced in the primary water line or secondary or in the sludge line, and / or in the vortex generating device.

13. A method of treating water, in particular wastewater, according to the preceding claim, characterized in that the average speed gradient G and the factor Gt are respectively greater than 400 s ^"1 and 6000 for t between 10 s and 30 s at the output of the vortex generating device.

14. A method of treating water, particularly wastewater, according to claim 12 or 13, characterized in that after passing through the vortex generator mixing device of the primary or secondary water line or the sludge line, additivated with the additional fluid, is carried out a third step of passage of the intimate mixture thus obtained in a device (11, 11a, 11b) dissipating energy, so as to transform the turbulent regime of the fluid from the vortex generating device, in a laminar regime.

15. A method of treating water, in particular wastewater, according to any one of claims 12 to 14, characterized in that the second step is a step of coagulation (2) or flocculation (3) of the sludge line.

16. A method for treating water, particularly wastewater, according to claim 15, characterized in that the second step of coagulation (2) or flocculation (3) of the sludge line is completed by a step of thickening or dewatering. dehydration.

17. A method of treating water, particularly wastewater, according to any one of claims 12 to 14, characterized in that the second step is a step of coagulation (2) or flocculation (3) of the water line secondary.

18. A method of treating water, particularly wastewater, according to claim 17, characterized in that the second step of coagulation (2) or flocculation (3) of the secondary water line is completed by a decantation step or capture on filter.

19. A method of treating water, particularly wastewater, according to any one of claims 12 to 14, characterized in that the second step is a pre-anoxic step of the primary water line, said queue being additivated with methanol.

20. A method of treating water, particularly wastewater, according to any one of claims 12 to 14, characterized in that the second step is a step of disinfecting the secondary water line supplying a contact and storage tank said line being additivated with an oxidizer of the bleach type.