FR2768141A1 - Small scale domestic effluent treatment for up to 600 inhabitants - Google Patents

Abstract

The treatment vessel is divided into two equal parts. Effluent for treatment is supplied to each vessel for periods of 24 hours, during which the vessel is aerated (29) from its base (3) with fine bubbles, and the effluent degraded by micro-organisms supported on vertical sheets (23) submerged in the liquid. During the next 24 hour period clarified effluent (40) and excess sludge are removed. The vertical sheets holding the micro-organisms are positioned 25 to 30 cm apart from each other and are submerged by at least 20 cm. Aeration is carried out intermittently during both filling and emptying periods. During emptying aeration is followed by settling, then skimming liquid from near the surface.

Description

AEROBIC PURIFICATION MICRO-STATION WITH UNDERWATER FIXED BED
AND A COMBINED BASIN
TECHNICAL FIELD OF THE INVENTION
The present invention relates to micro-wastewater treatment plants intended to treat aerobic waste daily discharges of a few tens to a few hundred equivalent inhabitants.

STATE OF TECHNOLOGY
The main difficulty encountered in the treatment of effluents from small communities is the variation in hydraulic and pollution flows.

Indeed, very small agglomerations generally only have unitary networks for the collection of effluents.

Wastewater treatment plants intended to treat effluents from motorway areas, campsites, etc., encounter the same difficulties with very significant peaks in terms of hydraulic flows and pollution flows.

The existing micro-stations are mainly of three types
activated sludge micro-stations: they are designed as reduced models of
larger stations. These micro-stations have a major defect, they are easily
leached during hydraulic shocks, which makes their operation very chaotic.
micro-stations with an emerging bacterial bed: they also resist jolts very poorly
hydraulic and polluting loads.
immersed fixed bed micro-stations: these resist hydraulic shocks well,
but most of the time they have limited oxygenation capacities which makes
that they do not withstand badly from polluting charges.

PRESENTATION OF THE TECHNIQUE
The present invention aims to remedy the drawbacks of the prior techniques.

The effluents are treated in a tank comprising two longitudinal walls 1 (FIG. 1 and FIG. 2) inclined at approximately 600, two transverse walls 2 (FIG. 2) vertical and a slab 3 (FIG. 3) horizontal. Sealing is ensured by a flexible film 4 (FIG. 3) which seals, it rests on cleanliness concrete 5 (FIG. 3) which protects it at the base.

Vertical protection plates 6 (Figure 4 and Figure 5) and inclined protection plates 7 (Figure 3) also provide protection for the sealing film. An upper lateral belt 8 (FIG. 3) allows the fixing of the main functional assemblies and in particular of the sealing film via the elements 9 for fixing the film (FIG. 3).

A central separation 10 (FIG. 3) separates the basin into two symmetrical half-basins, each half-basin has the same equipment except the sludge evacuation equipment which is common to the two half-basins. The upper face 1 1 (FIG. 3) of the central separation is situated above the highest level 30 (FIG. 3 and FIG. 4) of the effluents so as to avoid the direct passage of the effluents in the upper part of a half-basin. towards the other. The lower face 12 (FIG. 3) of the central partition leaves sufficient passage over the entire length to allow the levels to be balanced between the two half-basins. The suspended elements, the possible cover are fixed to a frame whose elements 13 (FIG. 1) bear on the one hand on the lateral belt 8 (FIG. 3) and on the other hand on support pillars 14 (FIG. 3 and figure 5). The support pillars 14 are supported on a load distributing pad 15 (FIG. 3).

The microorganisms attached are fixed on sheets of fabric 16 (Figure 2 and Figure 4) stretched vertically, the upper edge 18 (Figure 3) is located at an altitude such that it is always immersed at least 20 cm. The lower edge 19 (FIG. 3) of these same sheets of fabric is situated at an altitude such that the outlet of the tubes 24 (FIG. 2), carrying the fine bubble diffusers 29 (FIG. 2, FIG. 3 and FIG. 4) is possible without dismantling of the cloths supporting micro-organisms.

The aeration of the basin is carried out by the fine bubble diffusers 29 (Figure 2, Figure 3 and Figure 4) fixed on support tubes 24 (Figure 2), these tubes are fixed by fasteners 25 (Figure 4), they are supplied in air by supply tubes 26 (FIG. 2), the condensates are evacuated by tubes 27 (FIG. 4) fitted at their ends with valves 28 (FIG. 4), all these lines of diffuser support tubes and their annexes are independent of each other
Each gap 17 (FIG. 2) between two layers of fabric supporting micro-organisms is aerated by fine bubble diffusers 29 (FIG. 2, FIG. 3 and FIG. 4). The lifting of the diffusers for maintenance is done line by line. For this, an upward movement is successively followed by a horizontal shift towards the transverse wall opposite to the feed, then a horizontal shift towards the center and finally an ascent in the central zone, near the central separation 10 (FIG. 3).

The action of the fine bubble diffusers creates above them an upward movement of the effluents and a downward movement of these same effluents along the inclined walls. The whole forms vortex movements between the layers, these vortex movements are favorable for the mixing of the effluents and for the contact of these same effluents with the microorganisms fixed on the layers of fabric.

The effluent to be treated is supplied to the basin by two supply lines which are completely independent of each other, each line supplying a half-basin. Each line includes a feed pump, a distribution chute and its annexes. The effluents can be introduced up to a maximum level 30 (Figure 3 and Figure 4), through a chute 31 (Figure 1 and Figure 3) which has the function of distributing them regularly.

This distribution is made by a crenellated edge 32 (Figure 1, Figure 3 and Figure 4). An anti-drip deflector 33 (Figure 3 and Figure 4) prevents runoff along the wall. A lower vertical deflector 34 (FIG. 3 and FIG. 4) plunges into the liquid to a level situated very slightly below the minimum level 38 (FIG. 3 and FIG. 4) of the effluents being treated. The chute is covered by a deflector cover 35 (Figure 3 and Figure 4).

This deflector cover has a horizontal face which covers the chute thus avoiding the development of photophilic organisms and a vertical face whose lower edge plunges into the liquid slightly below the minimum level 38 (FIG. 3 and FIG. 4).

The feeding of the chute is carried out by a distribution pipe 36 (FIG. 1 and FIG. 3) equipped with outlet outlets 37 (FIG. 1) which ensure the regular distribution of the effluent by zone over the entire length of the chute.

After a period of rest, the free flocs decant which allows the extraction of clarified effluents. This is done periodically on one side or the other of the basin up to a minimum level 38 (Figure 3 and Figure 4). Zone 39 (Figure 3) where the recovery of clarified effluents takes place is located above each inclined wall. This recovery is done by chutes 40 (Figure 2 and Figure 3) movable in alternating discontinuous rotation about an axis. The effluent is then taken up by flexible tubes 41 (FIG. 3), these flexible tubes open out for each half-basin into an evacuation pipe 42 (FIG. 3) which flows itself into the counting channel 43 (FIG. 2 and Figure 4).

Each chute is rotatable around an axis 44 (FIG. 6 and FIG. 7), the connection between the chute and the axis of rotation is effected by a connecting arm 45 (FIG. 6 and FIG. 7), each chute can be brought back into position. high by return springs 46 (Figure 6 and Figure 7). Each chute for collecting clarified effluents is protected against the arrival of floats by a movable deflector in rotation 49 (FIG. 6 and FIG. 7). The alternating rotation movement which is of small amplitude is exerted around an axis 47 (FIG. 7), the connection is made between the deflector and the axis by a connecting arm 48 (FIG. 6 and FIG. 7), the lifting movement of the deflector is obtained by floats 50 (Figure 6 and Figure 7). On each side of the basin, the descent movements of the mobile chutes are controlled by a geared motor 56 (Figure 1 and Figure 2) each housed in the technical gallery 55 (Figure 5 and Figure 1). On each side the movement is transmitted by a shaft line 57 (Figure 2, Figure 6 and Figure 7) provided with control pins 58 (Figure 2, Figure 6 and Figure 7). The mechanical connection between the control pins 58 (Figure 2, Figure 6 and Figure 7) and each chute is provided by a ratchet 52 (Figure 6 and Figure 7). The connection between the control lug 58 (Figure 2, Figure 6 and Figure 7) and the ratchet itself is provided by a contact roller 53 (Figure 6 and Figure 7). The connection between the ratchet 52 (Figure 6 and Figure 7) and each connecting arm 45 (Figure 6 and Figure 7) is provided by a connecting member 54 (Figure 6 and Figure 7).

In each half-basin, the descent movements of all the troughs are obtained by starting the corresponding geared motor 56 (Figure 1 and Figure 2) in the direction of descent. The control lug 58 (Figure 2, Figure 6 and Figure 7) comes into contact with the ratchet 52 (Figure 6 and Figure 7), the chute sinks into the effluent, the clear liquid passes over the edge and is collected in the chute finally the lug 58 escapes and releases the chute which immediately engages in an upward movement. Each chute is returned upwards by the springs 46 (FIG. 6 and FIG. 7) and the skimming of the clarified effluents is interrupted. Then reverse the direction of rotation of the control shaft until the pins 58 (Figure 2, Figure 6 and Figure 7) pass over the ratchets 52 (Figure 6 and Figure 7).

The extraction of excess sludge is done in the central part 59 (Figure 3) located in the area where communication is established between the two half-basins. The sludge is taken up from closable return mouths 61 (FIG. 1, FIG. 3 and FIG. 5) at a given instant only one mouth is functional (that is to say not closed). The return vents are connected to a horizontal pipe 60 (Figure 1 and Figure 5) which opens into a recovery tank 62 (Figure 1 and Figure 5). The sludge is extracted by a submerged pump 63 (Figure 1 and Figure 5). All of the devices for closing the sludge return openings are controlled by a geared motor 64 (Figure 1), it drives a shaft line 65 (Figure 2) equipped with control lugs 66 (Figure 2 and Figure 3 ). Periodically during the rotation of the shaft line 65 (Figure 2) one of the control pins 66 (Figure 2 and Figure 3) comes into contact with one of the ends of the upper oscillating link arm 68 (Figure 3). This rotates around the axis of rotation 67 (Figure 3) when the contact between the control pin 66 (Figure 2 and Figure 3) and the end of the swing arm 68 (Figure 3) is no longer established , each return spring 69 (Figure 3) returns the swing arm to its original position. The mechanical connection between the upper oscillating link arm 68 (Figure 3) and the lower swing link arm 71 (Figure 3) is provided by a link rod 70 (Figure 3). The lower link arm 71 (Figure 3) oscillates around an axis 72 (Figure 3), it controls a closing valve 73 (Figure 3) mounted on a ball joint.

OPERATION
Operation takes place in 24 hour cycles. During 24 hours, the effluent to be treated is introduced into one of the two half-basins. During the following 24 hours the effluent to be treated is introduced into the other half-basin and so on. 24-hour cycles are broken down into 30-minute cycles. Each cycle breaks down as follows
In the half-basin where the fresh effluent intake takes place, there is a first phase which lasts a few minutes, with introduction of the effluent and simultaneous aeration, then a second phase with continued aeration. Meanwhile on the other side, in the other half-basin, where no fresh effluents are introduced for 24 hours, there is an initial aeration phase of approximately 15 minutes followed by a phase of rest of approximately 5 minutes, itself followed by a final phase of approximately 10 minutes during which extraction of the clarified effluents is carried out up to minimum level 38 (FIG. 3 and FIG. 4).

The same cycles are repeated on each side for 24 hours. Then, as previously stated, the roles played by each half-pool are reversed for 24 hours and so on.

STATEMENT OF FIGURES
Figure 1 shows a partial half-view of the basin showing mainly the distribution of the effluent and the extraction of sludge.

FIG. 2 represents a partial half-view mainly showing the supports of microorganisms the aeration and the recovery of the treated effluents.

Figure 3 shows a partial vertical half-section.

FIG. 4 represents a partial vertical longitudinal section passing through the measurement channel and through a distribution chute.

Figure 5 shows a partial vertical longitudinal axial section.

FIG. 6 represents a diagram in cross section of a module for recovering clarified effluents.

FIG. 7 represents a schematic top view of a module for recovering clarified effluents.

EMBODIMENT
The effluent is housed in a hexahedron-shaped tank with two longitudinal walls] (Figure 1 and Figure 2) inclined at approximately 60, two transverse walls 2 (Figure 2) vertical and a raft 3 (Figure 3) horizontal . A vertical section perpendicular to the longitudinal axis of the tank is an isosceles trapezium, the small base of which is at the bottom, a vertical section passing through the longitudinal axis is a square or a rectangle. The tightness of the tank is ensured by a flexible film 4 (figure 3) which rests at the base on a concrete of cleanliness 5 (figure 3), this same film rests on vertical protection plates 6 (figure 4 and figure 5) and protection plates inclined at about 60 7 (figure 3). An upper lateral belt 8 (FIG. 3) circles the pelvis. The height of the basin is such that the maximum height of the effluents being treated is between 2 m and 2.20 m approximately. This type of micro-station is intended for the treatment of effluents of approximately 100 to 600 population equivalents. The necessary treatment volumes are obtained from micro-stations with 2 or 3 standard widths. It is the variations in the length of the tanks that allow the necessary volume of treatment to be obtained. The central separation 10 (FIG. 3) separates the basin into two symmetrical half-basins, it is situated in a vertical plane passing substantially through the longitudinal axis of the basin. The upper face 11 (FIG. 3) of this central separation is located approximately 10 cm at the level of the maximum level 30 (FIG. 3) of the effluents, its lower face 12 (FIG. 3) leaves a free passage of approximately 10 cm in height over the entire length of the pelvis.

The suspended elements, the possible cover are fixed to a frame whose elements 13 (figure 1) bear on the one hand on the belt 8 (figure 3) and on the other hand on support pillars 14 (figure 3 and figure 5) which are located in a vertical plane passing through the longitudinal axis of the basin. The layers 16 (FIG. 2 and FIG. 4) of tissue supporting microorganisms are located in vertical parallel planes perpendicular to the longitudinal axis of the basin. The intervals 17 (FIG. 2) are equal and between approximately 25 and 30 cm. The upper edge 18 (FIG. 3) of the cloths supporting micro-organisms is situated at an altitude such that it is always immersed at least 20 cm. The lower edge 19 (FIG. 3) of these same layers of fabric supporting micro-organisms is situated at an altitude such that it allows the exit of the tubes 24 (FIG. 2) supporting the fine bubble diffusers without dismantling the layers of supporting fabric. microorganisms. The cloths supporting micro-organisms are stretched between an upper support 20 (Figure 3 and Figure 4) and a lower support 21 (Figure 3 and Figure 4). The intervals are maintained between the strips of tissue supporting microorganisms by horizontal connecting elements 22 (FIG. 4).

All of the fabric layers supporting microorganisms and their supports are held in place by vertical supports 23 (FIG. 3). Each assembly consisting of a tube 24 (FIG. 2) supporting fine bubble diffusers, fixed at each of its ends by a fixing 25 (FIG. 4), supplied with air by a tube 26 (FIG. 2), the condensates being evacuated by a tube 27 (FIG. 4), the tube itself closed by a tap 28 (FIG. 4) constitutes an assembly which is completely mechanically and functionally independent of other assemblies of the same type which perform the same ventilation function.

Each interval between two layers of tissue supporting microorganisms is aerated by fine bubble diffusers 29 (Figure 2, Figure 3 and Figure 4) located immediately above the raft, each of them is centered with respect to the two layers of tissue supporting nearest microorganisms. The effluents are distributed on each side of the basin by a chute 31 (FIG. 1 and FIG. 3) of rectangular section. The edge 32 (FIG. 1, FIG. 3 and FIG. 4) of these chutes faces inward and has a crenellated edge. Each chute is equipped with an anti-drip deflector 33 (Figure 3 and Figure 4). A vertical lower deflector 34 (Figure 3 and Figure 4) vertically extends the crenellated wall just a little below the minimum level 38 (Figure 3 and Figure 4) of the effluents being treated. Each chute is equipped with a deflector cover 35 (FIG. 3 and FIG. 4) which has a horizontal face which covers the chute and a vertical face whose lower edge plunges into the effluents slightly below the minimum level 38 (FIG. 3 and FIG. 4).

Each chute is supplied by a distribution pipe 36 (Figure 1 and Figure 3) located at the bottom of the chute opposite the crenellated edge. Outlets 37 (Figure 1) are evenly distributed over the entire length of the distribution pipe 36 (Figure 1 and Figure 3).

On each side of the basin the clarified effluents can be collected by troughs 40 (Figure 2 and Figure 3) movable in alternating rotation around an axis. Each movable chute is connected by a flexible tile 41 (Figure 3) to a discharge pipe 42 (Figure 3) which itself is connected to the counting channel 43 (Figure 1 and Figure 4).

Each chute is movable in rotation about an axis 44 (Figure 6 and Figure 7). The trunking - axis of rotation link is made by a link arm 45 (FIG. 6 and FIG. 7). Each chute can be returned to the high position by return springs 46 (FIG. 6 and FIG. 7). The mobile anti-floating deflector 49 (Figure 6 and Figure 7) is rotatable around an axis of rotation 47 (Figure 7). The connection is made by a link arm 48 (Figure 6 and Figure 7), the deflector is integral with floats 50 (Figure 6 and Figure 7). In each half-basin the downward movement of the troughs is controlled by a geared motor 56 (Figure 1 and Figure 2) housed in a technical gallery 55 (Figure 1 and Figure 5). Each gearmotor is integral with a shaft line 57 (Figure 2, Figure 6 and Figure 7) equipped with control pins 58 (Figure 2, Figure 6 and Figure 7) all located in the same plane.

The mechanical connection between the control pins 58 (Figure 2, Figure 6 and Figure 7) and each actual chute is provided by a ratchet 52 (Figure 6 and Figure 7) which oscillates around an axis of rotation 51 (Figure 7 ). The connection between each control pin 58 (Figure 2, Figure 6 and Figure 7) and each ratchet is provided by a contact roller 53 (Figure 6, Figure 7). The connection between the rock 52 (Figure 6 and Figure 7) and the connecting arms 45 (Figure 6 and Figure 7) is provided by connecting elements 54 (Figure 6 and Figure 7).

The sludge is taken up from closable return mouths 61 (FIG. 1, FIG. 3 and FIG. 5) distributed regularly on a horizontal pipe 60 (FIG. 1 and FIG. 5)
connected to a recovery tank 62 (Figure 1 and Figure 5) from where the sludge can be extracted
by a submerged pump 63 (Figure 1 and Figure 5). All of the devices for closing the sludge recovery openings are controlled by a geared motor 64 (Figure 1) which drives a shaft line 65 (Figure 2) on which are fixed control pins 66 (Figure 2 and Figure 3), the control pins are arranged in different planes so that they
only mechanically control the opening of one return opening at a time.

The upper part of the device for controlling the opening and closing of the
sludge recovery includes an upper oscillating link arm 68 (Figure 3) which rotates
about an axis of rotation 67 (Figure 3) and which is connected to a return spring 69 (Figure 3).

The mechanical connection between the upper part and the lower part is ensured by an arm
link 70 (Figure 3). The lower part of the device for controlling the opening or closing of the sludge recovery openings is composed of a lower oscillating link arm 71 (FIG. 3) which oscillates around an axis of rotation 72 (FIG. 3) and which controls a closing valve mounted on ball joint 73 (Figure 3).

INDUSTRIAL APPLICATION
The present invention is intended for aerobic treatment of effluents from small communities mainly between 100 and 600 population equivalents. It can also treat small pollutant loads of wine, food or industrial origin.

These micro-stations are particularly suitable for withstanding large load variations and large variations in hydraulic flows at the inlet.

They therefore meet a real need because the networks of small communities are most often unitary with very large hydraulic fluctuations.

Claims (7)

 (figure 2) vertical and to strike off 3 (figure 3) horizontal.  longitudinal 1 (Figure 1 and Figure 2) inclined to about 60, with transverse walls 2  CLAIMS 1) Aerobic micro-station with fixed immersed bed and characterized combined basin. In that the effluents being treated are housed in a walled basin  In that the basin is separated into two equal parts by a central separation 10 (figure  levels between the 2 half-basins.  3) whose lower edge 12 (FIG. 3) leaves a free space which allows the balancing of  bodies 16 (Figure 2, Figure 4) stretched vertically.  . In that each half-basin is equipped with layers of micro-support fabrics  (Figure 2) independent of each other.  In that the basin is aerated by fine bubble diffusers fixed on support tubes 24  supply and a distribution chute and its annexes.  complete line independent of each other, each including a pump  In that the distribution of the effluent to be treated is ensured in each half-basin by a  chutes movable in discontinuous alternating rotation 40 (Figure 2, Figure 3).  In that on each side of the basin the clarified effluents can be collected by  1, Figure 3 and Figure 5) of which only one at a given time is functional.  In that the excess sludge is taken up by closable return mouths 61 (FIG. 2) Micro-station according to claim 1 characterized: In that an upper lateral belt 8 (Figure 3) goes around the basin.  between the two half-basins.  about the height of the entire length of the pool to allow the levels to be balanced  lower 12 (figure 3) of this same central separation leaves a free passage of 10 cm  direct passage of effluents in the upper part of a half-basin towards the other, and that the face  above the maximum level of the effluents being treated so as to avoid  that the upper face 1 1 (FIG. 3) of this central separation is located approximately 10 cm  central is located in a vertical plane passing substantially through the longitudinal axis of the basin,  evacuation of the sludge which are common to the two half-basins, that this separation  symmetrical, that each half-basin has the same equipment except the equipment  . In that a central separation 10 (Figure 3) separates the basin into two half-basins  passing through the longitudinal axis of the pelvis.  share on support pillars 14 (Figure 3 and Figure 5) which are located in a vertical plane  the elements 13 (Figure 1) bear on the one hand on the belt 8 (Figure 3) and on the other  In that the suspended elements and the possible cover are fixed to a frame of which 3) Micro-station according to claim 1 characterized. In that the sheets of fabrics 16 (FIG. 2 and FIG. 4) are located in planes  vertical parallels perpendicular to the longitudinal axis of the pelvis, and that the intervals 17  (Figure 2) between two successive layers are equal and between 25 and 30 cm approximately.  organisms is located at an altitude such that it is always immersed at least 20 cm.  . In that the upper edge 18 (FIG. 3) of the cloths of microphone support fabric  organizations.  fine bubbles is possible without disassembly of the microphone support cloths  is located at an altitude such that the outlet of the tubes 24 (Figure 2) fitted with their aerators  In that the lower edge 19 (FIG. 3) of the cloths supporting micro-organisms 4) Micro-station according to claim 1 comprising a basin aeration device characterized: In that each assembly consisting of a tube 24 (Figure 2) support for fine diffusers  bubbles 29 (figure 2, figure 3 and figure 4), fixed by the elements 25 (figure 4), supplied with air  by a tube 26 (figure 2), the condensates being evacuated by a tube 27 (figure 4) constitutes  a whole totally mechanically and functionally independent of the others  sets of the same type which perform the same ventilation function. In that each interval between two layers of tissue supporting microorganisms is aerated by fine bubble diffusers 29 (FIG. 1) located immediately above the raft and that each of these fine bubble diffusers is centered with respect to the two layers of nearest tissues of microorganisms. 5) Micro-station according to claim 1 comprising a distribution assembly for the characterized effluent. In that each half-basin has a complete effluent distribution line  independent of the other, and that each includes a supply pump and a  distribution chute 31 (Figure 1 and Figure 3) and its annexes.  being processed.  crenellated wall a little below the minimum level 38 (Figure 3 and Figure 4) of the effluents  In that a vertical lower deflector 34 (Figure 3 and Figure 4) vertically extends the  minimum 38 (Figure 3 and Figure 4) of the effluents being treated.  lower plunges into the effluents being treated slightly below the level  comprising a horizontal face which covers the chute and a vertical face whose edge  In that each chute is equipped with a deflector cover 35 (Figure 3 and Figure 4)  evenly distributed over their entire length.  and that these distribution pipes are fitted with outlet openings 37 (FIG. 1)  36 (FIG. 1 and FIG. 3) located at the bottom of each chute opposite the crenellated edge,  In that the feeding of each chute is ensured by a distribution pipe 6) Micro-station according to claim 1 comprising a device for extracting clarified effluents characterized:. In that after a period of rest the extraction of the cleared effluents takes place  periodically on either side of the basin to a minimum level 38 (Figure 3 and  figure 4).  (figure 3).  chute is connected by a flexible tube 41 (Figure 3) to a discharge pipe 42  Figure 3) mobile in alternating discontinuous rotation around an axis, and that each  In that the recovery of the clarified effluents is carried out by chutes 40 (FIG. 2 and  (Figure 6 and Figure 7), that the connection is made with link arms 45 (Figure 6 and Figure  In that each chute is movable in alternating discontinuous rotation around axes 44  (Figure 6 and Figure 7).  7) and that each chute can be brought up by return springs 46  figure 7).  link arm 48 (Figure 6 and Figure 7) and that it is integral with floats 50 (Figure 6 and  alternative of low amplitude around axes 47 (figure 7), that the connection is made with  mobile in rotation 49 (FIG. 6 and FIG. 7), that this deflector is mobile in rotation  . In that each chute is protected against the arrival of floats by a deflector  figure 7).  that the mechanical connection with each chute is ensured by a ratchet 52 (Figure 6 and  control pins 58 (Figure 2, Figure 6 and Figure 7) all located in the same plane and  gear motor is integral with a shaft line 57 (Figure 2, Figure 6 and Figure 7) equipped  are controlled by a geared motor 56 (Figure 1 and Figure 2), that each  . In that in each half-basin the movements of descent of the mobile chutes 7) Micro-station according to claim 1 comprising a sludge extraction device characterized in that the sludge is taken up from return mouths 61 (FIG. 1, FIG. 3 and  figure 5) of which only one at a given time is functional, that these mouths are  regularly distributed over a horizontal pipe 60 (FIG. 1 and FIG. 5) connected to a  recovery tank 62 (Figure 1 and Figure 5) from where the sludge is extracted by a pump  submerged 63 (FIG. 1 and FIG. 5) In that all of the devices for closing the return vents are controlled by  a geared motor 64 (Figure 2) which drives a shaft line 65 (Figure 2) equipped with control pins 66 (Figure 2 and Figure 3), that these control pins are arranged in different planes, than the upper part of the control device comprises an upper oscillating link arm 68 (Figure 3) which oscillates around an axis of rotation 67 (Figure 3) that it is connected to a return spring 69 (Figure 3), that the mechanical connection between the upper oscillating part and the lower oscillating part is provided by a link arm 70 (FIG. 3), that the lower oscillating link arm 71 (FIG. 3) oscillates around an axis of rotation 72 (FIG. 3) and that 'it controls a closing valve 73 (figure 3) mounted on a ball joint.