FR3055229A1 - LOCAL TREATMENT PLANT FOR ORGANIC WASTES, PROCESSING METHOD THEREFOR, AND METHOD OF MAINTAINING THE INSTALLATION - Google Patents

Abstract

The invention relates to a plant (1) for local treatment of organic waste comprising a transportable container (2) which contains a sanitizing tank (10), first heating means for heating the waste to be treated contained in the tank. sanitizing (10) for hygienic purposes, a digestion vessel (20) in fluid communication with the sanitizing tank (10), containing microorganisms and for receiving the sanitized waste, second heating means for feeding and maintaining in mesophilic condition the contents of the digestion vessel (20), the facility (1) further comprising a waste storage assembly comprising at least one storage tank (30) of the methanized waste in fluid communication with the tank of digestion (20), the storage assembly being configured to have a methanized waste storage capacity at least equal to the volume of the digestion vessel (20).

Description

(54) LOCAL TREATMENT FACILITY FOR ORGANIC WASTE, METHOD FOR TREATING THE SAME AND METHOD FOR MAINTAINING THE FACILITY.

The invention relates to an installation (1) for local treatment of organic waste comprising a transportable container (2) which contains a sanitation tank (10), first heating means for heating the waste to be treated contained in the sanitation tank (10) for hygienic purposes, a digestion tank (20) in fluid communication with the sanitation tank (10), containing microorganisms and intended to receive the hygienized waste, of the second heating means for bring and maintain in mesophilic condition the contents of the digestion tank (20), the installation (1) further comprising a waste storage assembly comprising at least one storage tank (30) of methanized waste in fluid communication with the digestion tank (20), the storage assembly being configured to have a storage capacity for methanized waste at least equal to the volume of the digestion tank (20) .

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INSTALLATION FOR LOCAL TREATMENT OF ORGANIC WASTE, ASSOCIATED PROCESSING METHOD AND

INSTALLATION MAINTENANCE PROCEDURE

TECHNICAL FIELD OF THE INVENTION [001] The invention relates to the field of treatment of organic waste.

The invention relates more particularly to an improved installation and a method for the local treatment of organic waste by anaerobic digestion. The installation and process according to the invention are intended to locally transform organic waste into renewable energy and organic fertilizing material.

STATE OF THE ART We know from application WO2011 / 128781 a microgeneration installation of renewable energy. The installation comprises a portable treatment container which comprises a mixing tank for mixing the waste with a liquid, a maceration pump in fluid communication with the mixing container which is configured to macerate the waste in small pieces, a plurality of small storage tanks in fluid communication with the mixing tank which are configured to perform at least one waste pasteurization operation, a large retention tank in fluid communication with the storage tanks which is configured to perform anaerobic mesophilic digestion of the waste pasteurized and a dehydration unit in fluid communication with the large retention tank which is configured to dry the remainder of the waste after anaerobic mesophilic digestion. The installation also includes a portable gas storage container comprising a biogas storage tank produced during mesophilic anaerobic digestion. The portable treatment container and the portable biogas storage container are configured to be transported to a site and to be placed in fluid communication with each other to allow storage in the storage tank of the biogas produced by operation of mesophilic anaerobic digestion in the treatment tank.

The disadvantage of the installation described in the aforementioned application is the carrying out of maintenance operations thereof, and in particular the maintenance of the digestion tank. The maintenance of the digestion tank requires indeed to stop the installation and to remove the bacterial medium contained in the tank which induces risks of not succeeding in conserving the bacterial medium during the maintenance operation. In addition, due to the removal of the bacterial medium during maintenance, it is necessary to carry out an inoculation operation again and a rise in the load of the bacterial medium during the restarting of the installation, which constitute relatively long steps. and remain relatively complicated, uncertain and expensive.

The invention aims to remedy these problems by proposing an installation and a method for treating and recovering organic waste by methanization allowing simple and easy maintenance while ensuring the conservation of the bacterial medium.

The invention also aims to reduce the frequency of material collection thanks to the capacity of the storage tank.

The invention also aims to provide a transportable installation which can be operational as soon as it is put in place on the site for which it is intended, in order to secure the stages of innoculation and ramping upstream of the setting in place on site.

OBJECT OF THE INVENTION For this purpose, and according to a first aspect, the invention provides a local treatment facility for organic waste comprising a transportable container containing a first treatment tank, called a sanitation tank, intended to receive the waste to be treated in order to be hygienized therein, first heating means for heating the waste to be treated contained in the hygienization tank for the purposes of their hygiene, a second treatment tank, called digestion tank, in fluid communication with the sanitation tank, containing micro-organisms and intended to receive hygienized waste, second heating means to bring and maintain in mesophilic condition the contents of the digestion tank for the purpose of anaerobic digestion of hygienized waste, the installation comprising in addition a waste storage assembly comprising at least one methane waste storage tank és in fluid communication with the digestion tank, the storage assembly being configured to have a storage capacity for methanized waste at least equal to the volume of the digestion tank.

Thus, due to the presence of a storage cure in fluid communication with the digestion tank, maintenance operations are facilitated and the conservation of the bacterial medium in a stable state ensured. In fact, the bacterial medium can be transferred to the storage tank once it has been emptied and stored under conditions making it possible to maintain their stable state. The installation is therefore operational as soon as the maintenance operation is carried out, once the bacterial medium has been transferred to the digestion tank.

By transportable container is meant in the present application a portable container having dimensions optimized to contain at least two tanks, said tanks contained in the container defining a total volume less than or equal to 50 m ^{3 as} well as the network of conduits. associated and the equipment necessary for the operation of the installation and to allow its transport. It is understood, of course, that the dimensions of the container will be adapted to the number and dimensions of the tanks arranged within the latter. However, the number of said tanks and associated equipment is provided to allow the transport of said container with all of the elements contained therein.

Advantageously, the storage tank for methanised waste is located inside the container.

Advantageously, the installation includes a system for mixing the waste and the organic matter contained in the digestion tank.

Advantageously, the installation comprises a circuit returning to the methanization tank, by means of a booster, all or part of the biogas produced during the methanization of the waste in the digestion tank, the biogas forming with the booster the waste mixing system.

Advantageously, the installation includes a stirring system for stirring the waste contained in the sanitation tank.

Advantageously, the sanitation tank has a recirculation line connected to a drive pump to produce, upon actuation of the pump, a recirculation of waste, and thus generate a mixing of the contents of the tank d hygiene.

Advantageously, the installation also includes a storage tank for the biogas produced during the methanisation of the waste in the digestion tank.

Advantageously, the installation comprises a tank for storing a liquid substance configured to allow the introduction of the liquid substance into the sanitation tank.

Advantageously, the installation includes a servo system allowing automated management of the installation.

Advantageously, the installation includes a filtration and electrical and / or thermal recovery system of at least part of the biogas produced during the methanization of the waste in the digestion tank.

The invention also relates to a method for local treatment of organic waste remarkable in that it comprises the following steps consisting in carrying out a hygienization of the organic waste contained in a first treatment tank, called a hygiene tank, transferring the hygienized waste in a second treatment tank containing microorganisms, called digestion tank, the content of said second tank being maintained in mesophilic condition to ensure the methanisation of the hygienized waste, and pour the digestate resulting from the methanisation of the hygienized waste in a storage tank via a conduit connecting the second treatment tank to the storage tank.

Advantageously, it is introduced into the first treatment tank an amount of liquid substance substantially equal to the amount of waste to be treated contained in the first treatment tank.

Advantageously, the waste contained in the first treatment tank is subjected to sequential stirring by recirculation of the contents of the first treatment tank.

Advantageously, the hygienized waste contained in the second treatment tank is subjected to stirring, preferably sequential and / or sectorized, by recirculation of the biogas produced during the methanization of the hygienized waste contained in the second treatment tank.

Advantageously, the second treatment tank is previously inoculated. This has the advantage of speeding up the initial phase of the loading of microorganisms.

The invention also relates to a method of maintaining an installation as described above, the method being remarkable in that it comprises a step of decanting the content of the digestion tank into the storage tank of methanized waste , the storage tank having been drained beforehand, and a step of transferring the contents of the storage tank into the digestion tank once the maintenance of the digestion tank has been carried out.

The invention also relates to a mobile phase separation process composed of a centrifugal decanter disposed on a bucket capable of recovering the dry matter of the digestate after flocculation thereof by adding flocculant, made capable by the tank of storage of digested material. The phase separator also redistributes the purified liquid to the installation thanks to the water storage tank, thus allowing the installation to limit its external water needs.

BRIEF DESCRIPTION OF THE FIGURES Other objects and advantages of the invention will appear during the description which follows, given with reference to the single figure which represents a schematic view of a local treatment plant for organic waste according to the invention. 'invention.

DETAILED DESCRIPTION OF THE FIGURES The installation 1 of local treatment of organic waste DO illustrated in the single figure comprises a transportable container 2 containing a first waste treatment tank, called sanitation tank 10, a second treatment tank waste, called digestion tank 20, containing a bacterial medium (microorganisms), and a third tank 30 for the storage of methanized waste (ie treated) also called DI digestates. The tanks are connected to each other. More particularly, the sanitation tank 10 is in fluid communication with the digestion tank 20 which is in fluid communication with the storage tank 30.

The organic waste DO to be treated is poured into the sanitation tank 10 via a feed hopper 3 having an access hatch 4 opening onto the outside of the container 2. A water supply pipe 5 having an outlet in the feed hopper 3 makes it possible to bring the water necessary for the process which will be described later from a water storage tank 50. In the example illustrated, the water storage tank 50 is placed on the upper wall of the container 2. The feed hopper 3 advantageously comprises, in the lower part, a grinding module 6 for grinding the DO waste before falling into the sanitation tank 10. It can of course be provided to be able to pour waste into the sanitation tank 10 without prior grinding of the latter.

The installation 1 comprises first heating means intended to heat the waste to be treated DO contained in the sanitation tank 10 in order to suppress the pathogens entering and avoid their presence in the installation 1. The waste is thus hygienized at 70 ° C for 60 minutes (hygienization by pasteurization). In the illustrated embodiment, the first heating means comprise a set of heating elements 7 arranged so as to surround the sanitation tank 10 (the wall can then be defined as a double skin wall). Other heating modes can of course be implemented without departing from the scope of the invention, for example by means of an electric immersion heater system or with circulation of hot water in double skin or by a heat exchanger around the recirculation line, a cogeneration system, a UV sanitation system, etc.

In order to maintain a uniform temperature and mixing of the waste material contained in the sanitation tank 10, the latter is equipped with a recirculation circuit 8 arranged to ensure the mixing of the waste. The waste recirculation circuit comprises a conduit 9 connecting, in the example illustrated, as an inlet point the bottom of the sanitation tank 10 and as an outlet point the connection conduit 11 of the sanitation tank 10 to the digestion tank 20 by means of a three-way solenoid valve 12, which conduit 9 is equipped with a recirculation pump 13 allowing the entrainment and the recirculation of the waste within the sanitation tank

10. The pump 13 also has the role of ensuring grinding to a particle size of less than 10 mm, thanks to the regular recirculation of the material during the hygienization time.

The installation 1 comprises second heating means intended to heat the content of the digestion tank 20, namely the waste transferred into the digestion tank 20 containing the microorganisms, after having been hygienized in the tank d hygiene 10. The thermal regulation is carried out so as to bring and maintain the content of the digestion tank 20 in mesophilic condition, ie at a temperature of 37 ° C. and a pH having a value around 7.5 thanks to a basic controlled integration in liquid form. These parameters are monitored by temperature probes and a pH probe provided for this purpose.

In the illustrated embodiment, the second heating means comprise an immersion heater of the electric type 14 located, in this example, at the bottom of the digestion tank 20. Other modes of heating can of course be put implemented without departing from the scope of the invention. In particular, a digestion tank 20 having a double skin wall can be provided.

The digestion tank 20 is connected to the storage tank 30 of the waste treated by a pipe 15, advantageously plunging then inclined, arranged to evacuate the overflow of the digestion tank 20 by effect of communicating mud. The DI digestate leaves the digestion tank 20 by pouring it into the storage tank 30. The DI digestate thus regularly falls into the storage tank 30 which will be emptied via an evacuation pipe 16 to the outside of the container 2 when a level sensor provided for this purpose in the storage tank 30 (not shown) will indicate that the latter is filled. The storage tank 30 is also provided in the upper part with an evacuation pipe 17 for gases from the storage of the DI digestate outside the container 2. The evacuation pipe 17 is advantageously provided with a biofilter 18 to control the rejection of gases, and ventilation (not shown) to accelerate the natural evaporation of water.

In the illustrated embodiment, the installation 1 comprises a single storage tank 30. It is of course obvious that there can be provided a container comprising several storage tanks 30 of the treated waste. Whatever the number of storage tanks 30 provided, the total storage capacity offered must be at least equal to the volume of the digestion tank 20. Furthermore, and as will be seen below, an installation 1 can be provided whose storage tanks 30 are all or in part placed outside the container.

The installation 1 also advantageously comprises a storage tank 40 intended to store the biogas BI produced during the different biological reactions taking place between the hygienized waste and the microorganisms present in the digestion tank 20. The storage tank 40 is preferably in the form of a flexible storage tank or a membrane buffer storage. It is fluidly connected to the digestion tank 20, in the upper part of the latter by a conduit 19. The conduit 19 is equipped with a filter system 21 for filtration of water and hydrogen sulphide from the biogas. Advantageously, but not exclusively, the filter system 21 comprises a water filter consisting of a cartridge filter provided with a mesh of metallic fabric carrying out a demistering. The hydrogen sulfide filter consists of a cartridge filter filled with a purifying consumable such as activated carbon.

Thus filtered from its water and from hydrogen sulphide, biogas BI is recovered within installation 1 according to two ways of use.

One of the ways of using biogas is the mixing of hygienized waste contained in the digestion tank 20 with the microorganisms present in it in order to homogenize the temperature inside said tank but also the material itself (waste and microorganisms) so as to make available in the waste microorganisms which would have deposited in the bottom of the digestion tank 20. To do this, the installation f comprises a conduit for bypass 21 having an entry point in the conduit 19 connecting the digestion tank 20 and the biogas storage tank 40, at the outlet of the filtration system 28, and an exit point in the digestion tank 20. The mixing is produced for example using a booster 22 present in the bypass duct 21 and ejection channels located inside the digestion tank 20 (not shown). In order to ensure homogeneous stirring within the methanization tank, the ejection channels are arranged so as to optimally criss-cross the stirring surface. Thus, it can be carried out sequentially and by sector (an ejection channel defining a sector) so as to obtain maximum homogenization of the material and the temperature.

The other way of use is that linked to the use of biogas as fuel for the operation of the electrical and thermal equipment of the installation 1. To do this, the installation 1 comprises a conduit 23 connecting the tank storage 40 of the biogas to a cogeneration system 24 to which at least one battery 25 is connected. The electrical energy thus produced by the combustion of the biogas in the engine of the cogeneration system 24 is directly used for the electrical equipment of the installation 1 as well as for recharging the battery 25. Although not shown, it can be provided in addition to recover, in addition to the electrical energy, the thermal energy produced by the cogeneration system 24 during the combustion of the biogas to heat the contents of the sanitation tank 10 or else a water tank, or else to heat the digestion tank. In order to avoid any risk linked to the combustion of gases, the cogeneration system 24 is provided with an exhaust chimney 26 towards the outside of the container 2.

According to an alternative embodiment, it can be expected that the installation 1 is equipped with an output connection allowing local use of unused energy surpluses to supply the equipment of the installation 1. Thus, the connection of output could constitute, for example, a socket for charging light electric vehicles, connecting electrical devices, digital screens, heated parasols, lights, heaters, auxiliary air conditioning, etc.

The installation 1 further comprises a control system 27 allowing autonomous operation of the installation 1. The control system 27 is configured to collect all the information necessary to analyze the operation of the installation 1 as well as the technical data related to its proper functioning (temperature, pH or levels at the hours of operation of each element of the installation), to transmit all of the operational information in real time to a remote monitoring system and allow each element to be controlled independently, and thus carry out remote operation and / or remote monitoring.

In order to know the state of the installation 1 and to ensure the safety of the installation 1 in the event of human intervention, the installation 1 is advantageously equipped with safety sensors, such as concentration sensors different gases, connected to the control system 27.

In the illustrated embodiment, all of the elements except the water storage tank 50 is located inside the transportable container 2. The content of container 2 as well as the arrangement of the equipment in container 2 is however not limited to those illustrated in the figure. Installations can also be provided in which the container 2 comprises other equipment (tanks or the like). An installation 1 can also be provided in which the water storage tank 50 is disposed inside the container 2. Likewise, an installation can be provided in which the storage assembly is placed outside from container 2.

The treatment of organic waste in installation 1 is carried out as follows.

The organic waste DO to be treated is poured into the feed hopper 3. The waste then undergoes a first grinding operation via the grinding system before entering the sanitation tank 10. In order to facilitate mixing waste and to obtain the desired percentage of dry matter, a determined quantity of water contained in the water storage tank 50 is poured into the sanitation tank 10 via the feed hopper 3. The waste are mixed through the pump 13 via the opening of the recirculation circuit 8. Jointly, the pump 13 ensures a laceration of the waste. At the same time, the waste contained in the sanitation tank 10 is heated, for example via the heated double-skin wall, to a temperature of 70 ° C. This mixing continues for one hour at this same temperature in order to carry out the sanitation.

The mixture is then sent, via the pump 13, to the digestion tank 20 so that it is treated by microorganisms. Parameters such as temperature and pH are set to ensure the best physiological conditions, i.e. around 37 ° C and a pH between 7 and 8.5. The microorganisms, by digesting the waste, produce BI biogas comprising more or less methane and carbon dioxide. Depending on the rate of these gases in the biogas, it will either be burned by a flaring unit (not shown), or filtered and used to feed the upgrading equipment, namely, in the example illustrated, the cogenerator serving to produce the electrical and thermal energy necessary to supply the control and operating devices, and where appropriate the boiler used to heat the treatment tanks. The digestion tank 20 is regularly stirred in order to allow homogenization of the material to be digested and of the temperature via the biogas recirculation system, the latter being injected via the injection channels with sufficient pressure to create the disturbance necessary for ensuring the mixing of the material to be digested.

When the waste treatment is finished, the latter fall naturally, following the addition of new waste by the pump, according to the principle of "too full" in the storage tank 30.

Once the storage tank 30 is full, a detection system signals it and it is emptied.

The maintenance of the methanization tank is carried out by transferring the contents of the digestion tank 20 into the storage tank 30 which is hermetically closed. The digestion tank 20 is then cleaned. Once the maintenance is completed (tanks cleaned, probes replaced if necessary, base stock and filters changed), the mixture of the storage tank 30 is transferred to the digestion tank 20. Plant 1 is again ready for operation. Thanks to these transfer operations, it is thus possible to carry out maintenance of the digestion tank 20 while safeguarding the population of microorganisms present in it. This thus allows a significant saving of time and to dispense with the stages of inoculation and scaling up of generally difficult microorganisms.

All of these operations are controlled and monitored by the servo system 27 which informs in real time the operating status of the installation

1.

The DI digestate, the phases of which have been separated or not, may in turn be transported to a farmer, a market gardener, a green space, a master composter, a fertilizer manufacturer or a treatment center (composting, incineration, etc.).

The invention is described in the foregoing by way of example. It is understood that a person skilled in the art is able to carry out different variant embodiments of the invention without going beyond the ambit of the invention.

Claims (14)

1. Installation (1) for local treatment of organic waste (DO) comprising: a transportable container (2) containing: - a first treatment tank, called sanitation tank (10), intended to receive the waste to be treated (DO) to be hygienized there - first heating means for heating the waste to be treated (DO) contained in the hygienization tank (10) for the purposes of their hygienization, - a second treatment tank, called a digestion tank (20), in fluid communication with the sanitation tank (10), containing microorganisms and intended to receive the hygienized waste, - second heating means for bringing and maintaining in mesophilic condition the content of the digestion tank (20) for the methanisation of hygienized waste, the installation (1) further comprising a waste storage assembly comprising at least a storage tank (30) for methanised waste in fluid communication with the digestion tank (20), the storage assembly being configured to have a storage capacity for methanized waste at least equal to the volume of the digestion tank (20 ). 2. Installation (1) according to claim 1, characterized in that the storage tank (30) of methanized waste is located inside the container (2). 3. Installation (1) according to any one of the preceding claims, characterized in that the installation (1) comprises a circuit returning to the digestion tank (20), by means of a booster, all or part of the biogas produced during the methanisation of the waste in the digestion tank (20), the biogas forming with the booster a system for mixing the waste. 4. Installation (1) according to any one of the preceding claims, characterized in that the sanitation tank (10) comprises a recirculation line connected to a drive pump to produce, when the pump is actuated , a recirculation of the waste, and thus generate a mixing of the contents of the sanitation tank (10). 5. Installation (1) according to any one of the preceding claims, characterized in that it further comprises a storage tank (40) of the biogas produced during the methanisation of the waste in the digestion tank (20). 6. Installation (1) according to any one of the preceding claims, characterized in that it comprises a storage tank (50) of a liquid substance configured to allow the introduction of the liquid substance into the sanitation tank . 7. Installation (1) according to any one of the preceding claims, characterized in that it comprises a control system allowing automated management of the installation. 8. Installation (1) according to any one of the preceding claims, characterized in that it comprises a filtration and electrical and / or thermal recovery system of at least part of the biogas produced during the methanization of the waste in the digestion tank (20). 9. A method of local treatment of organic waste characterized in that it comprises the following stages consisting in: (a) hygienizing the organic waste contained in a first treatment tank, called the hygiene tank, (b) transferring the hygienized waste into a second treatment tank containing microorganisms, called the digestion tank, the content of said second tank being maintained in mesophilic condition to ensure the methanisation of hygienized waste, and (c) pouring the digestate resulting from the methanisation of hygienized waste into a storage tank via a conduit connecting the second treatment tank to the storage tank. 10. A method of local treatment of organic waste according to claim 9, characterized in that there is introduced into the first treatment tank an amount of liquid substance substantially equal to the amount of waste to be treated contained in the first treatment tank. 11. A method of local treatment of organic waste according to claim 9 or claim 10, characterized in that the waste contained in the first treatment tank is subjected to sequential stirring by recirculation of the 5 contents of the first treatment tank. 12. A method of local treatment of organic waste according to any one of claims 9 to 11, characterized in that the hygienized waste contained in the second treatment tank is subjected to stirring, preferably sequential and / or sectored, by recirculation biogas produced during anaerobic digestion 10 hygienized waste contained in the second treatment tank. 13. A method of local treatment of organic waste according to any one of claims 9 to 12, characterized in that the second treatment tank is previously inoculated (in order to accelerate the first phase of ramping up of the microorganisms). 14. A method of maintaining an installation according to any one of claims 1 to 8, characterized in that it comprises a step of transferring the contents of the digestion tank (20) into the storage tank (30) of methanised waste, the storage tank (30) having been previously emptied, and a step of transferring the content of the storage tank (30) into the digestion tank (20) once the digestion tank has been maintained. 1/1