WASTEWATER TREATMENT DEVICE AND METHOD

Abstract

TITLE OF THE INVENTION: WASTEWATER TREATMENT DEVICE AND METHOD The wastewater treatment device (100) comprises: - an anaerobic vacuum digester (105) including: - in its lower part (110), a wastewater inlet (115), - in its upper part (120): - a treated water overflow (125) including a water outlet (130) positioned at a first height (131) from the lower part and - a biogas outlet (135) positioned at a second height (136) higher than the first height, - a riser column (140) for biogas by suction from the lower part to the upper part, - a downpipe (141) for untreated wastewater from the upper part to the lower part and - a vacuum pump (145) connected to the biogas outlet configured to, when said pump is actuated, cause The flow of water from the lower part to the upper part. Figure for the abbreviation: Figure 1

Description

Title of the invention: WASTEWATER TREATMENT DEVICE AND METHOD Technical field of the invention

[0001] The present invention relates to a wastewater treatment device and a wastewater treatment process. It is applicable, for example, to the field of urban wastewater treatment. State of the art

[0002] Water scarcity and climate change necessitate appropriate and careful management of available water resources. In particular, Mediterranean regions are facing an imminent water shortage and require environmental protection technologies: - incorporating resource conservation, - focused on the minimal use of energy and chemicals and - promoting the maximum reuse of treated urban wastewater (known as "ERU") and residues produced from the pollutants present therein.

[0003] Solutions of the UASB (Upflow Anaerobic Sludge Blanket) type, designed for wastewater treatment in the 1970s, are known. This reactor is fed by an upward flow without packing media and is equipped in its upper part with a three-phase separation system: gas, liquid, and solid. This system allows for the release of biogas and limits the release of suspended solids (SS) from the effluent. Its hydraulic behavior is of the perfectly mixed type except at the three-phase separator, which exhibits the hydraulic characteristics of a plug flow reactor. The agitation of the medium is primarily due to biogas production.Good wastewater distribution is necessary, particularly for wastewater with low COD (for "chemical oxygen demand") concentrations that generates little gas, in order to avoid the formation of preferential pathways.

[0004] The retention of biomass in sludge bed reactors is based on the ability of anaerobic microorganisms to flocculate into granules that can reach up to 5 mm in diameter and exhibit good sedimentation characteristics (volume index < 20 mL.gMVS; maximum sedimentation velocity > 5 mh⁻¹), and good mechanical strength. This prevents their leaching from the reactor, in which the liquid's upward velocity is generally maintained between 1 and 1.5 mh⁻¹.

[0005] The main problem with these systems lies in the formation and maintenance of Granules. Granulation is a slow process that results in a long start-up period (approximately 6 months) if unsuitable digester sludge is used as inoculum. The formation of granular sludge is practically impossible with certain types of effluent, and degranulation can be observed when the reactor treating these effluents is seeded with already granular sludge. Sludge bed processes are also sensitive to the suspended solids concentration in the effluent. Indeed, a low upward velocity does not allow for the leaching of particulate matter, which can cause its accumulation at the expense of granule formation, thus leading to a decrease in biological activity. Solving these problems requires a better understanding of the underlying mechanisms of granulation and the factors that govern it. The granules are composed exclusively of microorganisms.It is generally accepted that their formation results from the selection of flocculating bacteria in an upflow system where free-floating cells in suspension are necessarily leached. Furthermore, the granules exhibit a highly complex bacterial organization. Fermentative, syntrophic, and methanogenic microorganisms are closely associated with one another, reducing the distance between them. This makes interspecies hydrogen transfer and metabolite diffusion along the food chain more efficient. The integration of UASB technology as a pretreatment process for ERU presents the following disadvantages: - poor elimination of pathogens and nutrients, - long inoculation and maturation time, - need for post-treatment and - potential olfactory nuisances if the reactor is poorly managed.

[0006] Mixing within the UASB reactor is a key parameter. One of the greatest technological advances in high-load anaerobic processes is the ability to separate the hydraulic residence time (HRT) from the sludge residence time (SRT). Unlike aerobic systems, in anaerobic or anoxic processes, the maximum permissible load depends on the maximum amount of reactant that can be supplied (e.g., oxygen during aerobic reactions), but in UASB digesters, performance is governed by the quantity of viable anaerobic biocatalysts, i.e., anaerobic bacterial biomass, having maximum contact with the wastewater constituents. Numerous improvements have been made to the UASB since its invention. For example, some researchers have replaced the gas-solid separator at the top of the reactor with an ascending fixed bed (UASB-FA).Other teams have adapted the fluidization conditions of a fluidized bed (liquid and gas velocities) to sludge beds to achieve granule expansion and treat various high-load chemical, biochemical, and biotechnological wastes. This reactor, . The EGSB (Expanded Granular Sludge Bed) process handles larger pollution loads because dead zones are limited, thus promoting sludge / effluent contact. The EGSB combines effluent recirculation at upwelling velocities exceeding 4 m / h with taller reactor geometries (high height-to-diameter ratio).

[0007] Compartmentalizing the reactor space led to the internal circulation reactor (IC for "Internal Circulation"), which consists of two superimposed UASB reactors. The lower reactor operates at high load, and the biogas produced is recovered for fluidization of the second reactor, located above and fed at low load, by gas-lift effect.

[0008] Although ERUs are considered dilute effluents (COD < 1000 mg / L*), they exhibit the characteristics of a complex effluent, with a low temperature (ranging between 15 and 25 °C) and a high TSS ratio of approximately 50–65%, i.e., a low ratio of soluble COD to total COD. Consequently, the total COD conversion is limited by the hydrolysis phase of solid compounds. The management and yields of this biogas technology are highly temperature-dependent. Like all chemical and biochemical transformations, the reaction rates in biogas production increase with temperature. However, these systems are very dependent on their operating temperature.

[0009] Thus, there is no satisfactory system that optimizes mixing in the reactor while also facilitating the extraction of biogas from the reactor. Description of the invention

[0010] The present invention aims to remedy all or part of these drawbacks.

[0011] To this end, according to a first aspect, the present invention relates to a wastewater treatment device, which comprises: - an anaerobic vacuum digester comprising: - in the lower part, an inlet for wastewater, - in the upper part: - a treated water overflow with a water outlet positioned at a first height from the lower part and - a biogas outlet positioned at a second height higher than the first height - a water lift column using biogas suction from the lower section to the upper section, - a column of untreated wastewater downpipes from the upper part to the lower part and - a vacuum pump connected to the biogas outlet configured to, when said pump is activated, cause water to flow from the lower part to the upper part.

[0012] Thanks to these provisions, it is possible to create a first stage of energy recovery in an urban wastewater treatment (ERU) sector.

[0013] This clarifies the ERU and transforms the pollution into methane. These provisions offer three main advantages: - hydraulic transport, through the suction effect of the riser column, with low energy cost aimed at optimizing mixing in the digester (promoting contact between sludge, anaerobic catalysts, and the reaction medium), - easy biogas extraction because the saturation pressure is preferentially below atmospheric pressure (the dissolution constant of a gas is proportional to the pressure in the container) and - sludge control and removal that is close to optimal.

[0014] The more biogas is extracted, the better the mixing inside the reactor. If the mixing is optimal, the better the reactor's performance in terms of converting pollution into methane.

[0015] In embodiments, the device of the present invention comprises: - an inlet for recirculated biogas in the lower part of the digester and - a biogas recirculation line from the biogas outlet to the biogas inlet.

[0016] These embodiments make it possible to promote the mixing of the sludge in the lower part of the digester.

[0017] In embodiments, the device of the present invention comprises: - a recirculation line activation valve and - a water extraction valve from the weir.

[0018] These embodiments allow the device to exhibit distinct modes of operation depending on the opening and closing of these valves.

[0019] In embodiments, the device of the present invention includes a water presence sensor in the weir, at least the extraction valve being activated according to the presence of captured water.

[0020] These embodiments allow a transition from a configuration in which the digester pressure increases towards a nominal pressure to a configuration in which the device is operating nominally. These embodiments allow the valve to remain in the closed position until water is drawn in at that point to prevent air from entering the reactor.

[0021] In embodiments, the device of the present invention has an operating mode in which the recirculating line activation valve The control valve and the water extraction valve are closed.

[0022] These embodiments allow a pressure reduction of the reactor suitable for the nominal operating condition of the device allowing optimal extraction of biogas and water.

[0023] In embodiments, the device of the present invention comprises: - a pressure sensor, configured to detect an operating pressure in the upper part of the digester and - a PID controller, configured to regulate the operation of the vacuum pump according to the pressure captured at the top of the digester.

[0024] These embodiments allow the device to optimally achieve an operating pressure.

[0025] In embodiments, the water upwelling column by water biogas aspiration comprises, in the upper part of the digester, an outlet for upwelled biogas, said outlet being positioned at a third height lower than the first height.

[0026] These embodiments allow the sludge, water and biogas obtained in the digester to be sorted.

[0027] In some embodiments, the device of the present invention comprises a buffer column configured to receive wastewater, said buffer column comprising: - a wastewater inlet, - an atmospheric air intake and - the digester wastewater inlet being connected to the buffer column and configured to supply wastewater by vacuum.

[0028] These embodiments allow for optimization of the digester's operation.

[0029] In some embodiments, the device that is the subject of the present invention comprises: - a sensor for the wastewater fill level of the buffer column and - a wastewater supply pump for the buffer column activated according to the captured fill level.

[0030] These embodiments allow for the automatic regulation of the quantity of wastewater in the buffer column. In such embodiments, a "PID" type control can be implemented, in which the pump operating frequency is controlled by the liquid level in the buffer column.

[0031] In some embodiments, the device that is the subject of the present invention comprises, downstream of the vacuum pump: - a biogas dehumidifier, - an adsorption method to purify biogas and / or - biogas storage.

[0032] These embodiments allow biogas to be treated in order to conform to specific valorization requirements.

[0033] In some embodiments, the digester comprises: - a thermal chamber configured to receive a flow of hot water, comprising a water inlet and a water outlet, - a hot water circuit comprising: - a water pump connected to the water outlet of the enclosure and - a heat exchanger configured to heat or cool hot water, the water at the outlet of the heat exchanger being supplied to the water inlet of the enclosure.

[0034] These embodiments allow the operating temperature of the digester to be regulated automatically.

[0035] According to a second aspect, the present invention relates to a wastewater treatment process, which comprises: - an anaerobic digestion stage under vacuum, in a digester, comprising: - a wastewater inlet stage in the lower part of the digester, - a pumping stage, in a water pumping column, by drawing biogas from the lower part to an upper part of the digester. - a discharge stage, via a weir in the upper part of the digester, of the treated water comprising a water outlet stage into a water inlet of the weir positioned at a first height, - an outlet stage for biogas, via a biogas outlet positioned at a second height greater than the first height, - a descent stage, in a wastewater downpipe, from the upper part to the lower part of the digester and - a vacuum pumping stage connected to the biogas outlet configured to, when said pump is operated, cause water to flow from the lower part to the upper part.

[0036] The advantages of the process correspond, mutatis mutandis, to the advantages of the device which is the subject of the present invention. Brief description of the figures

[0037] Other advantages, purposes and particular features of the invention will become apparent from the following non-limiting description of at least one particular embodiment of the device and method of the present invention, with reference to the accompanying drawings, in which: [Fig. 1] schematically represents a particular embodiment of the device that is the subject of the present invention and [Fig.2] represents, schematically and in the form of a flowchart, a succession of a particular step in the process which is the subject of the present invention. Description of the implementation methods

[0038] The present description is given by way of non-limiting grammar, each feature of an embodiment being able to be advantageously combined with any other feature of any other embodiment.

[0039] Hereinafter, the term "valve" refers to any type of valve known and suitable for the use indicated in the context. Such a valve is, for example, a motorized valve.

[0040] It should be noted from the outset that the figures are not to scale.

[0041] Figure [1], which is not to scale, shows a schematic view of a mode of the implementation of device 100, which is the subject of the present invention. This wastewater treatment device 100 comprises: - a 105 anaerobic vacuum digester comprising: - in the lower part 110, an inlet 115 for wastewater, - in the upper part 120: - a weir 125 for treated water having an outlet 130 for water positioned at a first height 131 from the lower part and - a 135 outlet for biogas positioned at a second height 136 higher than the first height and - a 140 mm water lift column using biogas suction from the lower section to the upper section, - a column 141 of untreated wastewater downpipes from the upper part to the lower part and - a 145 vacuum pump connected to the biogas outlet configured to, when said pump is activated, cause the flow of water from the lower part to the upper part.

[0042] The anaerobic digester 105 refers to a tank used in the methanation process that produces biogas through an anaerobic digestion process of organic matter from various sources. Here, preferably, the organic matter comes from urban wastewater.

[0043] The digester 105 is said to be "under vacuum", that is to say that its preferred operating conditions are at a pressure generally lower than atmospheric pressure.

[0044] The digester 105 is formally divided into two parts: a lower part 110 and an upper part 120, the relative proportions of which may vary. The part of the digester 105 that is generally close to the base, i.e., the ground, when the digester 105 is in operation, is generally called the "lower part 110". The lower part 110 thus designates the point of reception of the gravity flows occurring within the digester 105.

[0045] This digester 105 can implement various internal devices capable of interacting with the flow of biogas, water, and / or organic waste. For example, the digester 105 can implement, as shown in [Fig. 1], a grooved or finned flow device configured to distribute the flow homogeneously in the lower part 110. Such devices prevent the accumulation of sludge in a particular area of ​​the digester 105, which could disable it or at least reduce its efficiency.

[0046] In its lower section 110, the digester 105 has a wastewater inlet 115. This inlet 115 corresponds to an opening, preferably connected to a pipe, and optionally associated with a control means for a valve that governs the opening and / or closing of the inlet. This valve can be operated manually or automatically, using a programmable logic controller (PLC), according to preferred operating values ​​of the digester 105.

[0047] The lower part 110 of the digester also includes a bed of microorganisms, such as bacteria, selected for their ability to digest the waste-to-energy and produce biogas. Such microorganisms can be supported by granules arranged at the bottom of the tank (i.e., in the lower part 110) of the digester 105.

[0048] The wastewater thus exhibits an upward flow in the transverse surface of the reactor, except in column 141 where the water descends.

[0049] The lower part 110 and the upper part 120 of the digester 105 are connected by a water riser column 140 by suction of biogas from the lower part 110 to the upper part 120.

[0050] The lower part 110 and the upper part 120 of the digester 105 are also connected by a downpipe 141 carrying untreated wastewater from the upper part to the lower part.

[0051] The columns 140 for raising water by biogas aspiration and 141 for lowering water are, for example, coaxial.

[0052] In variants, the digester 105 includes a means for collecting wastewater brought up by the suction action of biogas through the riser column 140. This wastewater is then directed to the wastewater downpipe column 141 towards the lower part of the digester 105.

[0053] During the operation of the vacuum pump 145, the water in the lower part 110 is drawn up to the upper part of the digester 105. The riser columns 140 and the descent columns 141 amplify the mixing within the reactor by channeling the biogas towards the center.

[0054] In its upper part 120, the digester 105 mainly comprises outlets for the different species of interest generated. Firstly, an outlet 130 for water fed by a weir 125 whose function is to allow the water to exit exceeding a predetermined height, called first height 131, a function of the depression level, which is fixed according to the total height of the reactor, chosen to correspond to the height reached by the water once treated by the microorganisms.

[0055] Here, the "outlet" of the weir 125 is called, for example, a liquid retention wall whose crossing constitutes the outlet 130, in a manner analogous to the operation of a hydraulic weir.

[0056] The term "height" refers to a value of a physical quantity representing the distance between the base and a given point of the digester 105 along a vertical gravity axis. Alternatively, the height can also be measured from the highest point of the tank or any other reference point located at a higher altitude than the point of interest whose height is measured when the digester 105 is in operating condition.

[0057] In preferred variants, the weir 125 is connected to a pipe for vertical flow of the treated water towards the lower part 110, by gravity or by means of a pump, so as to counterbalance the effect of the negative pressure in the upper part 120 of the digester 105 when the water exits the digester 105.

[0058] Secondly, the digester 105 includes a biogas outlet 135, comprising, for example, a biogas extraction pipe with an opening positioned at the second height. The outlet 135 is configured to draw in biogas located above the purified water and the water drawn in by the downpipe 141.

[0059] The movement of water in the digester 105 is caused by the action of the vacuum pump 145 configured to generate a pressure, at the outlet 135 for biogas, lower than the inlet pressure of the ERU into the digester 105.

[0060] In embodiments such as that shown in [Fig. 1], the device 100 comprises: - a 150 inlet for recirculated biogas in the lower part 110 of the digester and - a 155 biogas recirculation line from the 135 biogas outlet to the 150 biogas inlet.

[0061] Inlet 150 is, for example, structurally similar to inlet 115 for wastewater in the various variants presented.

[0062] The recirculation line 155 is, for example, a pipe configured to connect the downstream of the vacuum pump 145 and the inlet 150 for biogas in the lower part 110 of the digester 105.

[0063] This recirculation line 155 can be associated with a set of valves whose selective actuation allows all or part of the biogas flow to be forced towards said recirculation line 155. In a minimalist embodiment, the vacuum pump 145 is connected to a biogas discharge line and the recirculation line 155 is a branch off this discharge line, the branch and the discharge line being each associated with a separate valve whose opposite activation causes the biogas to pass either into the discharge pipe or into the recirculation pipe 155.

[0064] In variants, the recirculation line 155 is associated with a gas pump and / or a check valve upstream of the inlet 155.

[0065] In embodiments such as that shown in [Fig. 1], the device 100 comprises: - a valve 160 for activating the recirculation line 155 and - a 165 valve for extracting water from the 125 spillway.

[0066] An example of an embodiment of the activation valve 160 is shown above, while the valve 165, functionally, allows the extraction of water from the weir 125, that is to say that as long as the extraction valve 165 is closed, the water captured by the weir 125 remains in the same pressure environment as the rest of the digester 105. The water leaving the weir can be used in multiple ways.

[0067] In embodiments such as that shown in [Fig.1], the device 100 includes a water presence sensor 170 in the weir 125, at least the extraction valve 165 being activated according to the presence of captured water.

[0068] The sensor 170 is, for example, a capacitive sensor activated by the presence of water in the weir 125. The detection of water can correspond to a change in the operating mode of the device 100, from a power-up phase to a nominal operating phase. These changes in operating modes are described below.

[0069] In embodiments such as that shown in [Fig.1], the device 100 has an operating mode in which the valve 160 for activating the recirculation line 155 and the water extraction valve 165 are closed.

[0070] Such an operating mode corresponds to a power-up or initialization phase of the device 100, during which a vacuum is created in the digester 105. For a vacuum to be created, the inlets and outlets of the digester 105 must be closed. As the vacuum is created, the water rises along the digester, from the lower part 110 to the upper part 120, until treated water enters the overflow 125. When water enters the overflow 125, a valve 165 is opened, allowing the treated water to exit. Other operating modes are described below.

[0071] In embodiments such as that shown in [Fig. 1], the device 100 comprises: - a 175 pressure sensor, configured to capture an operating pressure in the upper part 120 of the digester and - a PID 180 controller, configured to regulate the operation of the 145 vacuum pump according to the pressure captured in the upper part of the digester.

[0072] The pressure sensor 175 can be of any type known to a person skilled in the art who corresponds to the operating conditions of device 100, particularly in terms of temperature, pressure or humidity.

[0073] The PID controller 180, for "proportional, integral, derivative," is a control system that improves the performance of a closed-loop system or process. Here, the vacuum pump 145 is controlled by the pressure detected by the sensor 175.

[0074] In some embodiments, the biogas suction water return column 140 has, in the upper part 120 of the digester, an outlet 185 for biogas return, said outlet being positioned at a third height 186 lower than the first height 131. This height difference is due to the gas retention rate in the zone above the biogas suction water return column 140.

[0075] This allows for a double imbalance to be maintained: - Outlet 135 for biogas is located at a higher altitude than outlet 130 for water from overflow 125, - Outlet 185 for water from column 140 is located at a lower altitude than outlet 130 for water from the overflow and at a lower altitude than outlet 135 for biogas. The liquid level in this area is higher due to the "gaslift" effect, i.e., the rising biogas carrying wastewater. This liquid level is represented by a second line, 187, with a line through it.

[0076] In embodiments such as that shown in [Fig. 1], the device 100 comprises a buffer column 190 configured to receive wastewater, said buffer column comprising: - a 195 inlet for wastewater, - a 200 atmospheric air intake and - the inlet 115 for wastewater from digester 105 being connected to the buffer column 190 and configured to supply wastewater by vacuum.

[0077] The buffer column 190 has the main function of serving as a reservoir from which, by suction, water to be treated is drawn towards the digester 105.

[0078] The inlet 195 is, for example, analogous to the inlet 115 of the digester 105. The atmospheric air intake 200 is, for example, an opening to the environment outside the device 100, optionally able to be closed or not by means of a flap or valve.

[0079] When buffer column 190 is present, the wastewater inlet 115 can be reduced to a pipe that is not closed or can be closed between digester 105 and buffer column 190.

[0080] In embodiments such as that shown in [Fig. 1], the device 100 comprises: - a sensor 205 for the wastewater filling level of the buffer column 190 And - a 210 pump supplying the 190 buffer column with wastewater activated according to the captured fill level.

[0081] Sensor 205 is, for example, an ultrasonic sensor.

[0082] When the captured fill level is below a predetermined limit value, or a dynamic value calculated based on the flow rate of the pump 145 when empty or the pressure detected inside the digester 105, the pump 210 is, for example, configured to inject wastewater into the buffer column 190. Conversely, when the captured fill level is above a predetermined limit value, or a dynamic value calculated based on the flow rate of the pump 145 when empty or the pressure detected inside the digester 105, the pump 210 is, for example, configured to discontinue the injection of wastewater.

[0083] In embodiments such as that shown in [Fig. 1], the device 100 comprises, downstream of the vacuum pump 145: - a 215 biogas dehumidifier, - a 220 adsorption medium for purifying biogas and / or - a 225 biogas storage.

[0084] The dehumidifier 215 is, for example, a condenser of residual water vapors present in biogas.

[0085] The adsorption medium 220 is, for example, an activated carbon adsorption column or another porous adsorption medium such as silica or zeolites. In variants, the adsorption medium 220 can also be more complex if a higher quality of biogas is required at the outlet, for example of the "PSA" type (for "Pressure Swing Adsorption").

[0086] The storage 225 can correspond to a transport pipe or a tank, for example.

[0087] Preferably, device 100 comprises: - a 215 biogas dehumidifier, - a 220 adsorption medium for purifying dehumidified biogas and - a 225 storage of purified biogas.

[0088] In some embodiments, the digester 205 comprises: - a thermal enclosure 230 configured to receive a flow of hot water, comprising a water inlet 235 and a hydraulic guard for the protection of the gasometer 225, - a 245 hot water circuit comprising: - a 250 water pump connected to the 240 outlet for water from the 230 enclosure and - a heat exchanger 255 configured to heat or cool hot water, the water outlet of the heat exchanger 255 being supplied to the inlet 235 for water from the 230 speaker.

[0089] Two operating regimes are presented below. In both examples, the start-up condition is reached when the liquid level is one meter high in the buffer column and in the digester 105.

[0090] In the first operating mode, known as "regulated operation", the steps of the following process are carried out: - initially, a valve 165 at the outlet of the treated water from the digester 105 is closed to prevent atmospheric air from being drawn into the digester 105, making it impossible to prime the device 100, - opening of a priming valve 101 and closing of a biogas extraction valve 102 and a biogas recirculation valve 160, - starting up the pump 145 in vacuum until a set pressure is reached, depending on the height of the digester 105 chosen - in this example, the digester 105 is six meters high, i.e. a pressure of 500 mbarA (-0.5 barG), - maintenance of the set pressure by PID regulation between a differential frequency inverter of the vacuum pump 145 and a pressure sensor 175 installed in the upper part 120 of the digester (the speed of the vacuum pump is controlled by the pressure), - regulation of the liquid level inside the buffer column 190 by PID between the ERU feed pump speed and the liquid level measured by an ultrasonic sensor 205, - introduction of pre-treated wastewater into the buffer column 190 (after screening at the head of the wastewater treatment plant, for example), filling the digester 105 by vacuum, - Opening of the water outlet valve 165 when the water presence sensor 170 detects and is activated by the presence of water, - closing of the priming valve 101 and opening of the extraction valve 102, - The treated water is pumped back because the water flow is in a positive pressure zone; the liquid level in the buffer column 190 and the outlet equalize according to the water flow rate at the inlet 115. - The system operates stably; the treated water exits digester 105 through a dedicated outlet 130, and a circulation loop within digester 105 is created by the lifting effect of the biogas amplified by the vacuum; the gas retention rate increases with the level of vacuum. - The biogas produced is extracted by the 145 vacuum pump and goes through a stage of removing pollutants that can be absorbed in the vacuum network (foams and skimmate) via a condensate tray, - The biogas then undergoes a dehumidification stage; the condensate is removed by gravity. - the biogas then passes through an adsorption medium using extruded activated carbon or other adsorbent material to remove the H2S species, - The biogas is stored in a double-membrane gasometer (30 mbarsG) until the time of its use; a hydraulic guard of 50 mbarsG is associated with this device. - The evacuation of granular sludge takes place when the excess sludge compartment is full; at this stage, a 260 probe, for example capacitive, triggers the timed emptying procedure towards a solar dewatering zone (sludge mineralization), - The compartment height is sufficient to ensure that the stored granular sludge has a solids retention time (SRT) of 30 days (psychrophilic conditions 12-25°C); this is to ensure its proper sanitization by anaerobic digestion and - Thermal regulation of digester 105 is possible by the circulation of hot water in circuit 245 and thermal insulation.

[0091] All or part of this example can be implemented in an advantageous embodiment benefiting, occasionally or synergistically, from the unitary advantages provided by these parts.

[0092] A schematic representation, in the form of a flowchart, of the process 300 of the present invention is shown in [Fig. 2]. This wastewater treatment process 300 comprises: - a 305 stage of anaerobic digestion under vacuum, in a digester, comprising: - a wastewater inlet stage 310 in the lower part of the digester, - a step 315 of the ascent, in the digester water ascent column from the lower part to an upper part of the digester, - a discharge step 320, via a weir in the upper part of the digester, of the treated water comprising a water outlet step 325 into a water outlet of the water weir positioned according to a first height, - a 330 exit stage for biogas, via a biogas outlet positioned at a second height higher than the first height, - a descent stage 331, in a wastewater downpipe, from the upper part to the lower part of the digester and - a vacuum pumping stage 335 connected to the biogas outlet configured to, when said pump is operated, cause water to flow from the lower part to the upper part.

[0093] These steps have been described, mutatis mutandis, with reference to [Fig. 1].

Claims

Demands

1. A wastewater treatment device (100), characterized in that it comprises: - a vacuum anaerobic digester (105) comprising: - in its lower part (110), a wastewater inlet (115), the lower part being configured to receive a bed of microorganisms such as bacteria, - in its upper part (120): - a treated water overflow (125) comprising a water outlet (130) positioned at a first height (131) from the lower part and - a biogas outlet (135) positioned at a second height (136) higher than the first height, - a riser column (140) for biogas suction from the lower part to the upper part, - a downpipe (141) for untreated wastewater from the upper part to the lower part, and - a vacuum pump (145) connected to the biogas outlet configured to, when said pump is When activated, it causes water to flow from the lower part to the upper part.and - a buffer column (190) configured to receive wastewater, said buffer column comprising: - a wastewater inlet (195), - an atmospheric air intake (200) and - the digester wastewater inlet (115) being connected to the buffer column and configured to supply wastewater by suction.

2. Device (100) according to claim 1, comprising: - an inlet (150) for biogas recirculated in the lower part (110) of the digester and - a pipe (155) for recirculating biogas from the outlet (135) for biogas to the inlet (150) for biogas.

3. Device (100) according to claim 2, which comprises: - a valve (160) for activating the recirculation line (155) and - a valve (165) for extracting water from the weir.

4. Device (100) according to claim 3, which includes a sensor (170) for the presence of water in the weir (125), at least the extraction valve (165) being activated according to the presence of captured water.

5. Device (100) according to any one of claims 3 or 4, which has an operating mode in which the recirculation line (155) activation valve (160) and the water extraction valve (165) are closed.

6. Device (100) according to any one of claims 1 to 5, comprising: - a pressure sensor (175), configured to capture an operating pressure in the upper part (120) of the digester and - a PID controller (180), configured to regulate the operation of the vacuum pump (145) as a function of the pressure captured in the upper part of the digester.

7. Device (100) according to any one of claims 1 to 6, wherein the biogas riser column (140) comprises, in the upper part (120) of the digester, an outlet (185) for raised biogas, said outlet being positioned at a third height (186) lower than the first (131) height.

8. Device (100) according to claim 7, which includes: - a sensor (205) of a wastewater filling level of the buffer column (190) and - a pump (210) for supplying wastewater to the buffer column activated according to the captured filling level.

9. Device (100) according to any one of claims 1 to 8, which comprises, downstream of the vacuum pump (145): - a biogas dehumidifier (215), - an adsorption means (220) for purifying the biogas and / or - a biogas storage (225).

10. Device (100) according to any one of claims 1 to 9, wherein the digester (205) comprises: - a thermal enclosure (230) configured to receive a flow of hot water, having a water inlet (235) and a water outlet (240), - a hot water circuit (245) comprising: - a water pump (250) connected to the water outlet of the enclosure and - a heat exchanger (255) configured to heat or cool the hot water, the water at the outlet of the heat exchanger being supplied to the water inlet of the enclosure.

11. A wastewater treatment process (300), characterized in that it comprises: - a step (305) of anaerobic digestion under vacuum, in a digester, including: - a wastewater inlet stage (310) in the lower part of the digester, - a stage for generating a bed of microorganisms such as bacteria in the lower part of the digester, - a step (315) of upward movement, in the water riser column by suction of biogas from the lower part to an upper part of the digester, - a discharge stage (320) of treated water via a weir in the upper part of the digester, comprising a water outlet stage (325) of water into a water outlet of the water weir positioned at a first height, - a biogas outlet stage (330), by means of a biogas outlet positioned at a second height greater than the first height, - a descent stage (331), in a wastewater descent column, from the upper part to the lower part of the digester and - a vacuum pumping stage (335) connected to the biogas outlet configured to, when said pump is activated, cause the flow of water from the lower part to the upper part, - a wastewater inlet stage into a buffer column, - an atmospheric air intake stage in the buffer column and - a supply stage, by vacuum, of the wastewater present in the buffer column to the digester, the digester being connected to the buffer column.

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