Method for treating food waste

Abstract

The invention relates to the field of waste treatment, and in particular to the field of organic waste treatment, more particularly food waste. The present invention relates to a method for treating food waste, and to a device for implementing the method according to the invention.

Description

FOOD WASTE TREATMENT PROCESS

[0001] technical field

[0002] The invention belongs to the field of waste treatment, and in particular to the field of organic waste treatment, more specifically food waste.

[0003] The present invention relates to a method for treating food waste and to a device for implementing the method according to the invention.

[0004] State of the art

[0005] Food waste production continues to grow. Combating food waste is a priority for producers, food processing companies, distributors, and consumers alike. Otherwise, regulations are increasing their requirements for treatment and recovery. Since 1 erSince January 2012, individuals who produce or hold significant quantities of biowaste have been required to sort it, and once sorted, this waste must be processed through selective collection or local facilities. Since January 1, 2016, this requirement has extended to professionals producing more than 10 metric tons of biowaste per year. The nationwide implementation of source separation is planned for all biowaste producers in France by 2025. Regarding food waste, this includes the agri-food industry (2.6 million metric tons excluding effluents and sludge, INSEE, 2019), as well as the distribution sector (supermarkets, 0.45 million metric tons and markets, 0.4 million metric tons), the restaurant industry (0.8 million metric tons), and households (estimated at 18 million metric tons).While the fermentability of this waste is a constant factor requiring limited storage (odors, pests, pathogens), production contexts differ in terms of the size of the deposit, its quality, and the location of the production site (urban versus rural), thus constraining sorting and recovery to varying degrees. For small deposits, the collection frequency of once or twice a week and the necessary disinfection of containers and collection vehicles translate into prohibitive costs for local authorities and producers (households, restaurants, retail outlets, etc.) who are keen to develop local management solutions. However, the in-situ solutions under development, such as composting, methanization, or drying, encounter limitations inherent in their reduced scale: waste is produced. The challenges associated with methanization and drying include the visual and handling of waste, nuisances such as odors, flies, and significant manual labor, poor ergonomics, energy consumption, and the costs of managing explosive and fire hazards. For larger deposits, the lack of utilization of composting and methanization processes becomes a major drawback. Composting results in the production of a soil amendment with limited value. Methanization produces biogas and digestate, the management of which is complex (gaseous energy carrier, post-treatment of digestate through composting, etc.). However, composting can be implemented simply, with lower investment and operating costs than methanization. Mass losses in composting are also higher than in methanization, and the resulting compost can be applied directly to the soil.Composting, however, is not without its drawbacks. While known for its aerobic properties, the aggregates and compaction of the material, even when mixed with a structuring material (increasing the porosity of the medium), hinder even homogeneous aeration and lead to the development of anoxic and anaerobic zones. These zones promote the production and subsequent release of malodorous metabolites into the atmosphere. The composition of food waste, along with its high biodegradability, further exacerbates the development of these anoxic and anaerobic zones, and consequently, the odors.

[0006] Unlike drying and methanization, aerobic processes have the following advantages: i) they avoid the need for heat input, as the aerobic transformation of matter itself generates heat, and ii) they do not require fire and / or explosion risk prevention devices. When implemented on solid or pasty waste, their limitations include a lack of control of aerobic conditions, resulting in the development of anoxic and anaerobic zones that promote the production and emission of malodorous metabolites.

[0007] Increased control over the oxygenation of the material could be achieved by grinding the waste and introducing the ground material into an aqueous solution, then dispersing the solution onto a packing material. Such a solution would also have the advantage of limiting handling as well as the nuisances associated with this handling (carrying loads, odors, flies, health risks, etc.).

[0008] However, the above solution is not without its drawbacks. The localized accumulation of dry matter, inherent to the filtering properties of the packing, can obstruct the passage of water and air through the material. This slows down the biodegradation of the dry matter and can lead to clogging of the packing. Clogging can be further accelerated by the high biodegradability of food waste, whose aerobic biodegradation generates significant amounts of heat, resulting in a substantial increase in the packing temperature and, consequently, in the amount of water evaporated. Processes and devices exist, such as those described in application FR3096282, which partially address the problems encountered in known processes.

[0009] However, preventing clogging is challenging, and the risk increases over time. Resolving clogging once it has occurred is equally complex. This can be achieved, for example, mechanically by fluidizing the packing material, or chemically by introducing an acid, a base, or an oxidant. Such interventions are relatively expensive, require interrupting waste loading, and are not always effective.

[0010] Therefore, there is a need to address the shortcomings and drawbacks of previous art.

[0011] Detailed description of the invention

[0012] The invention thus relates to a process for treating organic waste, preferably food waste, comprising the steps of: 1) feeding and dispersion onto a packing material within a packing tank, of an aqueous suspension comprising crushed and / or dissolved waste including organic matter, 2) extraction of inert matter and / or sludge from the liquid effluent exiting the packing, preferably by filtration, decantation or flocculation, 3) mixing of the filling, preferably at a frequency ranging from one rotation of the tank every 6 to 72 hours, preferably every 12 to 48 hours, and even more preferably every 18 to 30 hours, and 4) redispersion on the packing of at least part of the liquid effluent exiting the packing, said liquid effluent being optionally enriched with crushed and / or dissolved waste, in which the waste undergoes aerobic biodegradation within the packing at a temperature ranging from 30 to 70°C.

[0013] For the purposes of this invention, "waste treatment" means the aerobic biodegradation, possibly supplemented by anaerobic biodegradation or fermentation, of ground waste suspended and / or dissolved in water. The waste includes biodegradable organic matter. Preferably, the waste is food waste.

[0014] Biodegradation refers to the consumption of organic matter by microorganisms such as bacteria, fungi, or algae for metabolic purposes.

[0015] Advantageously, the aqueous suspension comprises ground and / or dissolved waste. The waste includes organic matter and is preferably food waste. The concentration of waste in the suspension can vary. It generally does not exceed 100 g DM / L (grams of dry matter per liter, g DM / L) to avoid compromising its pumpability and homogeneous distribution on the surface of the packing, and leading to rapid clogging of the packing surface. The suspension essentially comprises water, organic matter, and possibly microorganisms.

[0016] The term "feeding" refers to the introduction of the aqueous suspension, comprising ground and / or dissolved waste, or its formation within a reactor or any suitable container from which it can then be dispersed onto the packing. Preferably, the feeding is homogeneous over time, meaning that the dry matter (DM) is ideally distributed evenly throughout the solution; otherwise, sudden DM additions to the packing could lead to surface clogging. Homogeneity over time can be further facilitated by the implementation of agitation of the solution in the suitable container (i.e. a receiving tank) to avoid decantation of the MS while the element ensuring dispersion / redispersion (i.e. a pump) is running (stopping the agitation could cause the cessation of dispersion / redispersion of the suspension on the packing).

[0017] Advantageously, the process according to the invention may further include a step of stirring the aqueous suspension comprising crushed and / or dissolved waste.

[0018] Advantageously, feeding can be accomplished by filling a receiving tank with an aqueous suspension containing ground and / or dissolved waste. The aqueous suspension can also be formed directly inside the tank. In this embodiment, feeding consists of filling the tank with a certain quantity of water, then introducing ground or unground food waste, which is then ground directly in the tank. Preferably, when the waste is introduced unground into the receiving tank, the dispersion of the suspension onto the packing must be stopped until the waste is ground to avoid clogging the pipes (suspended waste particles), blocking the pump (suspended waste particles), and clogging the packing surface by distributing a non-homogeneous dry matter solution. Preferably, the waste is ground upstream of the feeding process.Preferably, the waste feed is semi-continuous.

[0019] The term "dispersion" refers to a homogeneous distribution of the aqueous suspension comprising the crushed and / or dissolved waste over the packing in such a way as to ensure maximum efficiency of the aerobic biodegradation occurring within the packing.

[0020] Advantageously, the dispersion can be carried out by a fixed network of pipes or a motorized and / or mobile distributor pouring the solution homogeneously over the entire packing surface.

[0021] In the context of the invention, "liquid effluent" means the aqueous suspension exiting the packing having undergone partial or total aerobic biodegradation.

[0022] Advantageously, inert matter and / or sludge from the liquid effluent exiting the packing can be extracted before the liquid effluent exiting the packing is redispersed onto the packing. Preferably, the dry matter concentration in the aqueous suspension is measured regularly during the implementation of the process, and when it ceases to decrease over time, step 2) of the extraction process according to the invention is carried out. The extraction can be performed using any compatible extraction method and can be adapted according to the type of waste, inert matter, and / or sludge. For example, the inert matter and / or sludge can be filtered, removed by settling, possibly preceded by coagulation-flocculation. The extraction step of the inert matter and / or sludge can be carried out directly in the receiving tank via a settling tank or any other external component.Preferably, extraction is carried out by sampling the suspension in the receiving tank (before refilling the tank with waste), but it can also be carried out by filtration, decantation or coagulation-flocculation.

[0023] For the purposes of this invention, "inert material" means any non-biodegradable material that cannot be broken down by microorganisms, or whose biodegradation rate is so slow that, given the 20- to 30-day residence time of the material in the reactor, it cannot be broken down. For example, food waste is generally composed of biodegradable organic matter but may include a certain amount of material that will not be broken down by microorganisms. This may include minerals and trace elements (salts), mineral matter (such as bone or shell fragments), organic matter that is not biodegradable during the treatment process, such as lignin (such as seeds), as well as any packaging residues or other materials that may have passed through prior sorting.

[0024] In the context of the invention, "sludge" means the mixture of inert matter, stabilized organic matter and microorganisms formed during the treatment.

[0025] Advantageously, the process according to the invention is implemented in a closed loop. A closed loop is understood to mean that the process does not include any additional water supply step, apart from the one initially included in the aqueous suspension containing waste or in the receiving tank and in any waste added during the implementation of the process. In a closed circuit, almost all of the liquid effluent leaving the packing is completely redispersed over the packing. For example, the liquid effluent from the packing is collected in the receiving tank and then redispersed over the packing. In normal operation, there may be losses because some of the liquid effluent may be retained in the inert material and / or the extracted sludge. It is also possible to redisperse only part of the liquid effluent if the liquid volume becomes too large. There may be water losses, primarily in the form of vapor. Advantageously, step 4) of the process according to the invention can be implemented via a circulation loop that allows the aqueous effluent flowing into the receiving tank to be reintroduced into the dispersion / redispersion means."At least a part of the aqueous effluent" means 50 to 100% (volume) of the aqueous effluent.

[0026] Advantageously, the mixing in step 3) of the process according to the invention can be carried out by rotating the packing tank through an angle of 180°*x, where x is an integer, preferably an odd integer (around an axis XX'). x is not equal to 0, as this is equivalent to no rotation. Rotating the packing tank mixes the bulk packing material within it. Depending on the quantity and type of waste to be treated, the rotations can be more or less frequent and more or less rapid. For example, for an organic waste load of 25 kg / week (5 kg / day over 5 days) with a packing volume of 170 L in a 200 L tank, a rotation of 1.5 turns (x = 3) is applied upstream of each feed of the aqueous suspension of organic waste.

[0027] Advantageously, the process according to the invention is implemented in continuous operation. By "continuous operation" it is understood that ground waste is added regularly (generally once or several times a day) to the aqueous suspension, during the implementation of the process, as aerobic biodegradation removes waste.

[0028] Advantageously, the process according to the invention may further include a step 5) of natural or forced ventilation of the filling, preferably Forced air circulation within the packing is used to promote aerobic biodegradation when natural ventilation is insufficient. This forced air circulation can also help control the temperature within the packing, as the circulating air can be used, for example, to lower the temperature. Forced air circulation is preferably achieved using a compressor or fan. Ideally, the forced air circulation should be in the opposite direction to the flow of the aqueous suspension within the packing, meaning the air should preferably flow from the bottom to the top of the packing chamber. The injected air is generally at ambient temperature, typically between 10 and 20 °C.Depending on the season and the environment in which the process is carried out, this temperature may be lower or higher. Preferably, the air temperature is within a range of 15 to 25°C.

[0029] Advantageously, the process according to the invention may further include a step 6) of condensing the water vapor contained in the gaseous effluent resulting from the natural or forced aeration of the packing, said gaseous effluent being a mixture of air and gases produced during aerobic biodegradation within the packing. This condensation step may be carried out by controlling the dilution of the resulting gaseous effluent, in particular by installing a blocking device such as a removable perforated cover. During the implementation of step 6), the condensed water vapor then runs off the packing, thus preventing any drying. The water condensed during step 6) may also not run off the packing. It can thus be extracted from the system.

[0030] Condensation refers to the limitation or prevention of evaporation by the return to a liquid state of a fraction of the water vapor contained in the gaseous effluent. When the gaseous effluent exiting the material is diluted in the outside air, this dilution lowers the saturated vapor pressure of the water contained in the gaseous phase above the packing, a process that promotes the evaporation of the water contained in the effluent. Conversely, when the gaseous effluent exiting the material is not diluted (and the water vapor condenses on the walls of the obscuring device such as a lid) (perforated removable), the gaseous phase above the filling remains saturated with water vapor, which limits the evaporation of the water contained in the filling. A preferred embodiment of the method of the invention is that in which step 6) is carried out.

[0031] Thus, the process according to the invention may further include a step 7) of diluting the gaseous effluent. When water losses in the form of vapor must be reduced, the dilution of the gaseous effluent must be minimal. Conversely, when water losses in the form of vapor need to be increased, the dilution of the gaseous effluent must be high. Step 7) can therefore be implemented simultaneously or as an alternative to step 6) by removing the obscuring device, such as the removable perforated cover. For example, when a regime limiting evaporation is desired, zero dilution will be achieved and step 7) is not implemented. Conversely, when a regime promoting evaporation is desired, the gaseous effluent will be diluted in the surrounding air by implementing step 7), and the dilution rate will depend on atmospheric conditions. A person skilled in the art can determine the duration of step 7) based on the quantity of water to be removed.

[0032] Generally, waste or aqueous suspensions containing ground and / or dissolved waste contain sufficient aerobic microorganisms for aerobic biodegradation to occur. In some cases, when the composition of food waste or the aqueous suspension containing ground and / or dissolved waste is insufficient to ensure adequate aerobic or anaerobic biodegradation, it is possible to enrich the medium (aqueous suspension or device component) with microorganisms beneficial for waste biodegradation.

[0033] For the purposes of this invention, an "aerobic microorganism" is defined as a microorganism that can only live in the presence of strict oxygen or whose growth is possible in the presence of oxygen, in which case it is called a facultative aerobe. Examples include bacteria, archaea, fungi, algae, yeasts, and other common aerobic microorganisms.

[0034] Advantageously, according to the invention, the microorganisms involved in aerobic biodegradation are essentially bacteria (i.e. phyla: Firmicutes, Actinobacteria, Proteobacteria, Bacteroidetes, Deinococcus- Thermus) and fungi (i.e. phyla: Ascomycota, Basidiomycota, Zygomycota, Oomycota, Deuteromycota, Chytridiomycota).

[0035] Advantageously, the aqueous suspension comprising ground and / or dissolved waste can be obtained by grinding the waste to a greater or lesser degree, followed by dissolving it. The resulting suspension can then be dispersed onto the packing material, in accordance with step 1) of the process according to the invention. For example, prior to step 1), the process according to the invention may further comprise the following steps: a) grinding of waste, said grinding preferably being carried out within a fraction of the liquid effluent optionally enriched with ground and / or dissolved waste; b) dissolving the ground material obtained in step a); c) optionally, extraction, preferably by filtration or decantation, of the insufficiently ground solid particles from the aqueous suspension obtained in b), and obtaining an aqueous suspension comprising ground and / or dissolved waste.The extracted, insufficiently ground solid particles can then be ground again and dissolved. The particle size of the ground material can easily be adjusted by a person skilled in the art according to the type of packing, particularly its porosity. Preferably, the particle size of the ground material is less than 3 mm. The dissolution of the ground material from step b) can be carried out in the liquid effluent.

[0036] Advantageously, any type of bulk packing can be used in implementing the process according to the invention. For the purposes of the invention, "packing" or "packing material" refers to an assembly, whether bulk or structured, for example in a tank or column, that increases the contact surface area between the liquid and gas phases, thereby improving phase exchange for a given column volume. The porosity of the packing can be a function of the flow rate and the dry matter concentration of the suspension. The mixture of different Structuring materials (with different porosity and exchange surface area) make it easier to adjust the porosity and exchange surface area of ​​the lining.

[0037] In the context of the invention, the filling is a loose filling of natural and / or synthetic origin. It is preferably a filling of natural origin or a mixture of natural and synthetic fillings. The filling is preferably selected from the group comprising natural materials, preferably organic, and synthetic materials, or a mixture thereof. The synthetic filling is preferably made of plastic. The synthetic filling may be selected from Pali rings, Lessing rings, Rashig rings, Berl saddles, Intalox saddles, and swages. The natural filling may be selected from fine wood shavings and plant fibers.Plant fibers can be chosen from wood, coconut, hemp, and loofah fibers. Natural filling materials are preferably chosen from fine wood chips and coconut fibers. When using a mixture of natural and synthetic filling materials, a natural / synthetic volume ratio is defined. This ratio can range from 2:3 to 3:2, preferably 1:1. A replenishment of natural filling materials can be carried out to compensate for their slow biodegradation. Thus, natural filling materials can be added periodically to the filling tank. The quantity added and the frequency of addition could, for example, be 1 / 3 of the initial volume of natural filling materials added every 3 months.

[0038] Advantageously, the process according to the invention may further include an anaerobic biodegradation or fermentation step (8). In one embodiment of the invention, at least a portion of the liquid effluent exiting the packing may undergo an anaerobic biodegradation or fermentation step before being redispersed at the top of the packing. The anaerobic biodegradation or fermentation step (8) may be carried out in a tank isolated from the packing, and in particular from any natural or forced airflow. This tank may be identical to, or different from, the receiving tank used for feeding and the recovery of the liquid effluent exiting the packing. The process may further include an inoculation step (i.e. of the tank isolated from the packing or another element) by microorganisms promoting anaerobic biodegradation or fermentation.

[0039] Advantageously, the process according to the invention may further include a step 9) of cooling the liquid and / or gaseous effluent exiting the packing. This step 9) may be carried out by conduction and / or condensation and may be performed in addition to step 6). Of course, those skilled in the art will know how to adapt the cooling of the liquid and / or gaseous effluent so as to maintain an optimal temperature for biodegradation within the packing.

[0040] Advantageously, cooling the liquid and / or gaseous effluents exiting the packing allows for the extraction of heat. This extracted heat is then transferred, preferably to a heat transfer fluid, for further use. For example, the extracted heat can be used to heat a room near the process location, produce domestic hot water, or dry materials. In winter, it can also be used to warm the airflow circulating within the packing, the packing itself, or the receiving tank. The process of the invention allows for the recovery of at least 20% of the theoretically recoverable heat, and preferably more than 40%.

[0041] Advantageously, the process according to the invention may further include a step 10) of purging a fraction of the liquid effluent. This step can be implemented as material to be treated is added. When the liquid effluent circulates in the recirculation loop and through the packing, it becomes enriched in mineral elements such as nitrogen, phosphorus, potassium, or sulfur; and this accumulation (increase in the concentration of these elements in the liquid effluent) can, beyond certain thresholds, inhibit biodegradation activity or, more generally, the biological activity of microorganisms. Step 10) can therefore be implemented, on an ad hoc basis, on a fraction of the liquid effluent. This fraction could, for example, be on the order of 1 L / 25 kg of waste added, or 3% of the volume of the liquid effluent. A person skilled in the art will know how to implement this step. by means of a simple bypass circuit or a withdrawal from the tank. Step 10) can be implemented simultaneously with step 2).

[0042] Another object of the invention relates to a packing tank 1, preferably cylindrical, extending radially around an axis XX', said tank comprising: -a first outer shell 100; -a second inner envelope 200 contained within the outer envelope 100, being movable in rotation around the axis XX' within the outer envelope 100; and -a filling 300 filling at least 65% of the light of the inner envelope 200; and the inner envelope 200 has at least two perforated areas 210, and the outer envelope has at least two windows 110 capable of being positioned at least partially opposite the perforated area of ​​the inner envelope 200 in a rotation configuration of the inner envelope 200 within the outer envelope 100.

[0043] Within the framework of the present invention, and in particular within the framework of the implementation of the process according to the invention, "rotation of the packing tank 1" means the rotation of the second inner shell 200 contained in the outer shell 100 of the tank 1 according to the invention.

[0044] Advantageously, the first outer shell 100 can be cylindrical. The internal diameter of the cylinder can range from 23 to 260 cm, preferably from 33 to 240 cm. The length of the cylinder can range from 13 to 1550 cm, preferably from 23 to 1250 cm. The outer shell comprises at least two windows 110, preferably two. The two windows 110 of the outer shell 100, considered independently of the rest of the tank, can be positioned opposite each other and each comprises a parallelepiped-shaped cavity opening onto the exterior of the tank.In an alternative embodiment, the outer casing 100 consists of at least two fixed parallelepiped windows 110 placed opposite each other, preferably four windows, opposite each other, in pairs, capable of being positioned at least partially opposite the perforated areas 210 of the inner casing 200 in a rotational configuration of the inner casing 200, and of a support structure 120, said support structure being able to be cylindrical. The support structure may be made of in addition to including a system 140 for rotating the inner casing 200, such as motorized wheels 140. The outer casing 100 may further include holes 130. The holes 130 may be obstructed or not so as to modulate the dilution of the gaseous effluent.

[0045] Advantageously, the second inner shell 200 can be cylindrical. The internal diameter of the cylinder can range from 20 to 240 cm, preferably from 30 to 200 cm. The internal length of the cylinder can range from 10 to 1500 cm, preferably from 20 to 1200 cm. A length-to-diameter (L / D) ratio is defined. Preferably, the L / D ratio is within a range of 0.1 to 10, preferably from 0.2 to 9. For an inner cylinder of fixed volume, the loads applied per unit area of ​​the upper lining within the cylinder and per unit area of ​​the internal cylinder in contact with the lining increase with the cylinder volume and decrease as L / D increases. In fact, increasing the cylinder volume will lead to cylinders with increasing L / D ratios. For cylinder volumes between 0.08 and 25 m³ 3An indicative value for L / D can be obtained using the equation below: L / D = 1.3181 x ln(V) + 3.6239, where V represents the required cylinder volume in m³ 3 . For volumes less than 0.08 m 3 , L / D will preferably be between 0.1 and 0.29. Advantageously, the inner envelope 200 may have perforations with an internal diameter ranging from 10 mm to 30 mm, preferably from 15 mm to 25 mm, and cover at least 20 to 50% of the surface of the inner envelope 200, preferably from 30 to 40%.

[0046] Advantageously, the length of each perforated zone of the inner shell 200 can represent 70 to 100% of the length of the inner shell 200, preferably 80%. The width of each perforated zone of the inner shell 200 can represent 10 to 25% of the perimeter of the inner shell 200, preferably 15 to 20% of the perimeter, or approximately 1 / 6 of the perimeter. Advantageously, each perforated zone 210 can be a stainless steel grid.

[0047] Advantageously, the dimensions of the windows 110 of the external envelope 100 are adjusted to match (i.e. less than or equal to) the dimensions of the perforated areas 210 of the internal envelope 200.

[0048] Advantageously, the points of contact between the inner envelope 200 containing the filling 300 and the outer envelope 100 can be seals 310 with a height greater than the spacing between the inner envelope 200 and the outer envelope 100, said seals being fixed to the inner envelope 200, so as to surround each perforated window 110. The compression of said seals 310, resulting from their height greater than the spacing between the two envelopes 100, 200, ensures the seal between the two envelopes 100, 200.

[0049] Advantageously, the internal diameter of the outer shell preferably has the dimension of the diameter of the inner shell plus the two thicknesses of the seals and the two thicknesses of the walls of the inner shell; the adjustment of the diameters of the two shells can be carried out by a person skilled in the art so as to obtain the tank of the desired dimension.

[0050] Advantageously, the material constituting the inner envelope 200 and / or the outer envelope 100 has low thermal conductivity, or the envelopes themselves include insulation and can thus be thermally insulated from the external environment. For example, the envelopes may be made of plastic (minimum conductivity of around 0.15 W / m / °K) and / or metal (minimum conductivity of around 14 W / m / °K for stainless steel) and may include polyurethane insulation (minimum conductivity of around 0.026 W / m / °K).

[0051] Advantageously, the 300 padding can fill at least 65% of the light in the inner envelope 200, preferably from 65 to 85%.

[0052] Advantageously, the packing tank 1 according to the invention may further include a means for regulating the dilution of the outgoing gases 400. Preferably, the means for regulating the dilution of the outgoing gases 400 may be a removable perforated cover. A removable perforated cover may be equipped with collection channels, said channels allowing the collection of condensate formed on the walls of the cover. The channels may be connected to a drain channel connected to the outside. The channel may be equipped with a valve, In the closed position, this allows condensate to accumulate in the troughs before being discharged onto the packing. The removable perforated cover has holes. In one embodiment, the holes can be blocked to modulate the dilution of the gaseous effluent. The holes allow ambient air to enter the space at the top of the tank, between the packing and the cover. These holes are preferably positioned as close as possible to the perforated areas 210, and therefore they can also be located near the windows 110.

[0053] The means for regulating the dilution of the outgoing gases 400 allows for two operating modes: the first, with the perforated lid in place, to limit evaporation; the second, without the lid, to promote evaporation. This is controlled by varying the volume of liquid effluent exiting the packing, which a person skilled in the art can adjust according to their needs. For example, a drastic reduction in the volume of liquid effluent exiting, indicating a water deficiency in the packing (which limits biodegradation), justifies the use of the regulation means 400 to limit evaporation. Conversely, a drastic increase in this volume, indicating a water-saturated packing, justifies removing the packing to promote evaporation. The regulation means enables the implementation of steps 6 and 7 of the process according to the invention.The accumulation of solution in the receiving tank 4 and as soon as the volume Vs of the solution in the receiving tank 4 is greater than 100%, preferably 50 to 75%, of the initial volume VE introduced into the receiving tank 4 (step a)), then the lid 400 must be removed, and as soon as Vs solution in the receiving tank 4 returns to an initial VE then the lid 400 is replaced.

[0054] The invention further relates to a processing unit 1000, comprising: - a packing tank 1 according to the invention, - a means of supplying 7 with the aqueous suspension, - a means of dispersing 3 of the aqueous suspension, - a means for redispersing 10 of the liquid effluent from the packing, preferably identical to the dispersion means 3, - a means of extracting 5 inert matter and / or sludge from the liquid effluent emerging from the upholstery, and - a recirculation loop 2 allowing the redispersion over the packing of at least part of the liquid effluent exiting the packing, said loop comprising a receiving tank 4, and possibly a buffer tank 8.

[0055] The term "connected" means a direct or indirect connection between two elements of the packing tank 1, 2000 or of the processing unit 1000 according to the invention.

[0056] Advantageously, the feeding means 7 represents any element enabling the introduction of waste, whether ground or not, in aqueous suspension or not, into the treatment unit 1000 according to the invention for the purpose of its treatment. The feeding means 7 may be located at the receiving tank 4 or be the receiving tank 4 itself, at the head 11 of the packing tank, or upstream of the grinding means 6. The feeding means 7 may be a feeding hopper 7.

[0057] Advantageously, in the process according to the invention, the supply of aqueous suspension can be done via the receiving tank 4. This can be a tank whose contents are agitated (axial agitation) and of sufficient useful volume to allow an increase in its volume following an increase in dry matter of the solution or a deficit in evaporation. The aqueous suspension is thus dispersed onto the packing 300 from the receiving tank 4 via the recirculation loop 2. The liquid effluent from the packing 300 can be stored in the receiving tank 4 (or in the buffer tank 8) and redispersed at the inlet 11 of the packing tank 1 via the recirculation loop 2. The feed can be made directly at the inlet 11 of the packing tank 1, via a separate element of the recirculation loop 2. The receiving tank 4 can be connected to the packing tank 1 via the recirculation loop 2 and the dispersion or redispersion means 3 or 10.

[0058] Advantageously, the receiving tank 4 is connected to the head 11 of the packing tank 1 via the recirculation loop 2 and / or the dispersion means 3 or redispersion means 10. The receiving tank 4 thus allows the aqueous suspension to be stored before its dispersion onto the packing 300 and the liquid effluent exiting the packing 300 to be recovered before the latter is redispersed over the packing 300. The receiving tank 4 may include an agitation means 41, preferably a mechanical agitator.

[0059] Advantageously, the base 12 of the filling tank 1 is connected to the receiving tank 4.

[0060] Advantageously, the dispersion means 3 represents any element enabling the homogeneous distribution of the aqueous suspension over the packing 300. This can be a fixed network of pipes or a motorized and / or mobile distributor (a distributor moving in translation or rotation if the packing tank is parallelepiped or cylindrical), the movement enabling the distribution points to be moved homogeneously over the entire surface of the packing 300. It can also be a fixed network of pipes. The dispersion means 3 is preferably located under the base of the gas dilution control means 400. The dispersion means 3 allows, if necessary, the equitable redistribution of the aqueous suspension flow via a network of pipes.

[0061] Advantageously, the means of dispersion 3 and redispersion 10 are identical or different, preferably identical.

[0062] Advantageously, during implementation of the process in the treatment unit according to the invention, the packing 300 is generally traversed, for example from bottom to top, by a gaseous flow, for example air, containing oxygen used by microorganisms for aerobic biodegradation. During biodegradation, the biodegradable organic matter is oxidized in the predominant forms of CO2 and H2O. Carbon dioxide and water are removed via the exiting gas flow at the top of the packing to the gas dilution control means (when present), where the water vapor condenses and then flows back into the packing, limiting the risk of clogging and, in some cases, the drying out of the biofilter. The biodegradation activity results in the production of heat, which warms the packing and the solution. At the base 12 of the packing tank 1, the liquid effluent flows into the receiving tank 4.

[0063] Advantageously, the ventilation means 9 represents any element enabling air circulation within the packing tank 1 (particularly within the inner casing). This could be a fan, a compressor, or a simple opening allowing air to circulate in the packing 300 (inside the packing tank 1).

[0064] Advantageously, the ventilation means 9 is connected to the base 12 of the packing tank 1.

[0065] Advantageously, the treatment unit may include a gas inlet E, connected to the venting means 9 or to the base 12 of the packing tank 1. The treatment unit may include a gas outlet S, connected to the outlet gas dilution control means 400 or to the head 11 of the packing tank 1.

[0066] Advantageously, the recirculation loop 2 connects the receiving tank 4 to the head 11 of the packing tank 1. The recirculation loop 2 may include a pumping means 21. The pumping means 21 may be any element such as a centrifugal or peristaltic pump enabling the aqueous suspension to be circulated from the tank to the dispersion means 3 and / or redispersion means 10.

[0067] Advantageously, the recirculation loop 2, possibly including a pumping means 21, connects the receiving tank 4 and the head 11 of the packing tank 1, allowing at least part of the liquid effluent from the packing to be reinjected into the head 11 of the packing tank 1.

[0068] Advantageously, the dispersion means 3 / redispersion 10 is connected to the pump 21 and to the head 11 of the packing tank 1, allowing the aqueous suspension to be dispersed homogeneously on the packing 300.

[0069] Advantageously, the extraction means 5 can be a simple settling tank or a filter. Settling will be promoted by intermittently stopping the agitation and the feeding of the packing when the dry matter concentration of the aqueous suspension no longer allows the input of the quantity of waste for which the treatment unit 1000 according to the invention was designed. Settling can optionally be promoted by adding flocculating agents to the receiving tank, these agents enabling the formation of flocs (whose settling rate is higher than that of non-flocculated materials).

[0070] Advantageously, the extraction means 5 can be connected or integrated into the receptacle tank 4.

[0071] Advantageously, the processing unit 1000 may include a cooling means 14, which can be any type of heat exchanger. The cooling means 14 at the top 11 of the packing tank 1 can be a liquid / gas heat exchanger, preferably operating by condensation. For example, it could be a tube or plate heat exchanger. The cooling means 14 at the bottom 12 of the packing tank 1 can be a liquid / liquid heat exchanger, preferably operating by conduction. For example, it could be a tube or plate heat exchanger. The heat exchanger can be positioned upstream (head 11 of the packing tank 1) and / or downstream (base 12 of the packing tank 1 or in the receiving tank 4) of the packing 300. When a heat exchanger is positioned upstream of the packing 300, it allows the gaseous effluent from the packing to be cooled.Cooling the gaseous effluent allows the water vapor contained within it to condense. This condensation prevents water loss and thus limits the increase in dry matter content of the solution, which would otherwise lead to clogging of the packing 300. When a heat exchanger is positioned downstream of the packing 300, it cools the liquid effluent from the packing before it is redispersed. Lowering the temperature of the liquid effluent can also reduce evaporation losses by lowering the temperature of the upper part of the packing (particularly during redispersion). The heat extracted during the cooling of the liquid and / or gaseous effluents from the packing can be transferred to a heat transfer fluid or other storage element. Generally, the gaseous effluent from biodegradation comprises a mixture of oxygen, nitrogen, carbon dioxide, water vapor, and other biodegradation gases. It typically contains less oxygen and more carbon dioxide than the incoming air, water vapor, and other biodegradation gases. The gaseous effluent escapes from the packing head and flows into the cooling unit, where the water vapor is recondensed before trickling back into the packing, or directly into the receiving tank via a pipe connected to the packing tank.

[0072] Advantageously, at least one cooling means 14 is connected to the head 11, to the inner casing 200 and / or to the base 12 of the packing tank 1.

[0073] Advantageously, the processing unit 1000 according to the invention may further comprise a grinding means 6. The grinding means 6 may, for example, be a grinder capable of grinding bones, fibrous materials, and pastes. It may be a garbage disposal. The type and / or size of the grinder can be adapted to the dimensions of the installation.

[0074] Advantageously, the grinding means 6 can be connected or integrated into the receiving tank 4. The waste can thus be ground before being suspended in the receiving tank 4 or ground within the receiving tank 4, preferably before being suspended in the receiving tank 4.

[0075] Advantageously, the treatment unit 1000 according to the invention may further comprise a fermenter reactor 16.

[0076] The invention also relates to the use of the packing tank 1 or the unit 1000 according to the invention for treating waste, preferably food waste, comprising organic matter and capable of undergoing aerobic biodegradation, at least partial.

[0077] The advantages associated with the invention include, but are not limited to: - a reduction in waste handling, due to the dissolution of the waste and subsequent handling carried out solely by a pump, - the absence of contact (visual, manual, olfactory, etc.) with the waste once it has been introduced into the treatment unit, guaranteeing better acceptance of the process and reducing both health risks and olfactory nuisances, - better control of waste transformations by aerobic biodegradation via better control of oxygen-matter exchanges in the filling (greater homogeneity of exchanges) as well as greater homogeneity of heat transfers between the material and the external environment (unlike composting processes), - the production of a treatment residue representing a very small fraction mass of the treated waste deposit, - a sanitized treatment residue due to the residence times and high temperatures in the filling, - a significant reduction in environmentally impactful gaseous emissions (CH4, N2O, NH3, H2S, VOCs, odors) linked to better control of the oxygenation of matter and its biodegradation, - applicable to deposits ranging from that produced at the hearth scale (80 kg / year / individual) compared to that produced by a large producer, i.e., 50 tonnes / year and above. - low treatment costs, - a turnkey, on / off type solution, - a process with low energy and material efficiency (reduced wood consumption and low installed electrical power due to low pressure losses in the lining due to the gaseous aeration flow), - obtaining products of interest: concentrated solution of minerals (N, P, K, S, Na, Ca etc... ). - an on-site implementation to treat waste from collective catering (cafeterias, schools, university restaurants, nursing homes, etc.), large and medium-sized food retailers, or even household food waste (domestic scale), in local treatment stations in urban (markets, city centers, neighborhoods, vertical housing) or rural areas, or on a centralized treatment platform, or even iv) in the agri-food industry, - an implementation for the production, from food waste, of molecules of interest such as ethanol, volatile fatty acids or even methane (This production can be obtained via the control of the level of aeration of the packing (micro-aeration) or within the fermenter of the solution exiting the packing, agitated and airtight container, via the control of the redox of the solution collected in this container and the residence time in the fermenter), - implementation within the framework of fermentations whose substrates are initially solid, substrates of specific biochemical composition by means of an input of specific microorganisms.

[0078] Brief description of the figures

[0079] [Fig. 1] Figure 1 shows an example of a cylindrical packing tank 1, extending radially around an axis XX', said tank comprising: -a first outer envelope 100; -a second inner envelope 200 contained within the outer envelope 100, being movable in rotation around the axis XX' within the outer envelope 100; and -a filling 300 filling at least 65% of the light of the inner envelope 200; and the inner envelope 200 has two perforated areas 210, and the outer envelope 100 has two windows 110 capable of being positioned at least partially opposite the perforated area of ​​the inner envelope 200 in a rotation configuration of the inner envelope 200 within the outer envelope 100.

[0080] [Fig. 2] Figure 2 shows a cross-sectional view of an example of a cylindrical packing tank 1 extending radially around an axis XX', said tank comprising: - a first outer envelope 100; - a second inner envelope 200 contained within the outer envelope, being rotationally mobile around the axis XX' within the outer envelope; and -a 300 filling that fills at least 65% of the light in the inner envelope 200; - a removable perforated lid 400; - a set of seals 310; and the inner envelope 200 has two perforated areas 210, and the outer envelope 100 has two windows 110 capable of being positioned at least partly opposite the perforated area of ​​the inner envelope 200 in a rotation configuration of the inner envelope 200 in the outer envelope 100.

[0081] [Fig. 3] Figure 3 represents A) a top view of the packing tank 1 and B) a side view of the packing tank 1, when the perforated areas 210 and the windows 110 are aligned.

[0082] [Fig. 4] Figure 4 represents a cylindrical packing tank 2000 extending radially around an axis XX', said tank comprising: - a first external envelope consisting of a 120 support structure and of a set of 140 motorized wheels; - a set of 310 seals; - a second inner envelope 200 contained within the outer envelope, being rotationally mobile around the axis XX' within the outer envelope; and -a 300 filling that fills at least 65% of the light in the inner envelope 200; - a removable perforated cover 400; and the inner envelope 200 has four perforated areas 210, and the outer envelope has four windows 110 capable of being positioned at least partially opposite the perforated area of ​​the inner envelope in a rotation configuration of the inner envelope in the outer envelope.

[0083] [Fig. 5] Figure 5 represents a treatment unit 1000 according to the invention comprising a waste feed tank 7, a gas outlet S, a packing tank 1 comprising a packing head 11 and a packing base 12, a recirculation loop 2 comprising a pump 21, a distributor 10 of the aqueous suspension at the head 11 of the packing tank, a receiving tank 4 comprising an agitator 41 and a filter 5, a purge outlet P, a grinder 6, an air inlet E, a compressor 9 (air inlet, natural ventilation) and a set of valves 13. The direction of air flow is symbolized by the set of arrows F1. The direction of liquid flow is symbolized by the set of arrows F2.

[0084] The following example illustrates the invention, in a non-limiting manner.

[0085] An experiment was conducted in treatment unit 1000, illustrated in Figure 5, which includes a packing tank 1, shown in Figures 1, 2, and 3. The receiving tank 4 was a cylindrical HDPE tank with a volume of 60 L. A volume of 30 L of water was introduced into the receiving tank prior to the first addition of shredded waste. The packing tank 1 has the following dimensions: - external envelope 100: D = 64 cm, L = 111 cm, windows (2): L = 84 cm, W = 30 cm, - inner envelope 200: D= 50 cm, L = 100 cm, perforated areas (2): 80 cm, perforated circular linear: (20*2=40 cm) i.e. total perforated area covering 25% of the inner envelope (2*12.5%), diameter of holes: 15 mm. The packing material 300 had a total volume of 170 L. It consisted of a mixture made up of 48% by volume of fine, dry wood chips and 52% by volume of Pali rings (15 mm x 15 mm). A gas outlet S was provided at the top of the packing tank 1, which was connected to a removable perforated cover 400.

[0086] The treated biowaste was collected from a self-service institutional restaurant. It consisted mainly of raw and cooked food uneaten by diners (leftover trays and raw and cooked food not selected by diners). Its dry matter (DM) content was 256 g DM / kg. The waste was shredded in shredder 6 before being transferred to the collection tank 4.

[0087] A 25 kg / week (5 kg / day over 5 days) load of food waste was applied for 4 weeks. 5 kg of waste was added 5 days a week to the feed bin 7, which also contained the solution collected in the receiving tank 4. The water-waste suspension, whether ground or dissolved, returned to the receiving tank 4. Air produced by a compressor 9 was injected at the base 12 of the packing tank. The aeration flow rate applied to the packing 300 was between 4 and 12.5 L / min. The aqueous suspension containing the waste was dispersed and recirculated over the packing 300 via the recirculation loop 2, using a sump pump 21. The homogeneous dispersion of the suspension in the packing tank 1 was implemented via the distribution of the suspension flow in a network of tubes 10 whose outlets were uniformly distributed at the head 11 of the packing tank.

[0088] The mixing of the packing was carried out by a rotation around the axis XX' of the inner shell 100 of the packing tank 1, at a frequency of 1.5 (x = 3) turns every 24h, rotation applied before the feeding-dispersion of the suspension on the packing i.e. approximately 24h after the last addition of suspension on the packing 300.

[0089] The perforated lid 400 was put in place for 16 days (condensation) and removed until the 28th day (dilution).

[0090] The masses of the reactor and the container collecting the solution exiting the packing were measured daily. The temperature of the reaction medium and the O2 and CO2 concentrations of the exiting gases were continuously monitored.

[0091] Each addition of ground waste resulted in: i) an increase in the oxygen consumption kinetics (rC) and temperature in the packing, indicating the growth of the biological activity of aerobic biodegradation of the biodegradable material, ii) the attainment of maximum values ​​for rC2 and temperature in the packing, then iii) the decrease of rC and T, iii) rCO2 max (mol C / h) and Tmatière max reached were respectively 2.25 mol C-CO2 / h produced and 58.4°C.

[0092] Measurements showed that the accumulation of matter (H2O and dry solids) in the system (packing tank 1 and receiving tank 4) began to decrease after 18 days of treatment, and that from then on, the weekly mass loss was equal to or even greater than the mass of waste added during the week. The treatment performance is estimated at 5 to 6 tonnes / m³. 3 / year.

Claims

Demands

1. A process for treating organic waste, preferably food waste, comprising the steps of: 1) feeding and dispersion onto a packing material within a packing tank, of an aqueous suspension comprising crushed and / or dissolved waste including organic matter, 2) extraction of inert matter and / or sludge from the liquid effluent exiting the packing, preferably by filtration, decantation or flocculation, 3) mixing of the filling, preferably at a frequency ranging from one rotation of the tank every 6 to 72 hours, preferably every 12 to 48 hours, and even more preferably every 18 to 30 hours, and 4) redispersion on the packing of at least part of the liquid effluent exiting the packing, said liquid effluent being optionally enriched with crushed and / or dissolved waste, in which the waste undergoes aerobic biodegradation within the packing at a temperature ranging from 30 to 70°C.

2. The method according to claim 1, said method being implemented in a closed circuit.

3. A method according to claim 1 or 2, wherein the mixing of step 3) is carried out by rotating the packing tank by an angle of 180°*x, where x is a relative integer, not 0, preferably x is an odd relative integer.

4. A process according to any one of the preceding claims, said process being fed with waste in a semi-continuous manner.

5. A method according to any one of the preceding claims, further comprising a step 5) of natural or forced ventilation of the filling, preferably by forced circulation of an airflow in the filling.

6. A method according to the preceding claim, further comprising a step 6) of condensing the water vapor included in the gaseous effluent from the natural or forced ventilation of the packing.

7. A method according to any one of the preceding claims, further comprising a step 7) of diluting the gaseous effluent, said gaseous effluent being a mixture of air and gases produced during aerobic biodegradation within the packing.

8. A method according to any one of the preceding claims, wherein the filling is a bulk filling of natural and / or synthetic origin, preferably of natural origin, or a mixture of natural and synthetic filling in a natural / synthetic volume ratio of 2:3 to 3:2, and even more preferably a ratio of 1:

1.

9. A method according to the preceding claim, wherein the synthetic filling, preferably made of plastic, is selected from Pali rings, Lessing rings, Rashig rings, Berl saddles, Intalox saddles, and tellerettes, and wherein the natural filling is selected from fine wood chips and vegetable fibers selected from wood, coconut, hemp and luffa fibers.

10. A packing tank (1) for implementing the process according to any one of the preceding claims, preferably cylindrical, extending radially about an axis XX', said tank comprising: -a first outer envelope (100); -a second inner envelope (200) contained within the outer envelope (100), being rotationally mobile around the axis XX' within the outer envelope (100); and -a filling material (300) filling at least 65% of the light in the inner envelope (200); - optionally a gas dilution control means (400), and the inner envelope (200) has at least two perforated areas (210), and the outer envelope has at least two windows (110) capable of being positioned at least partially opposite the perforated area (210) of the inner envelope (200) in a rotation configuration of the inner envelope (200) in the outer envelope (100).

11. Tank according to claim 10, wherein the two windows (110) of the outer casing (100), considered independently of the rest of the tank (1), are placed opposite each other and each comprise a parallelepiped cavity opening onto the outside of the tank (1).

12. Tank according to any one of claims 10 or 11 in which the inner shell (200) has perforations of internal diameter from 10 mm to 30 mm, preferably from 15 mm to 25 mm and cover at least 20 to 50% of the surface of the inner shell (200), preferably from 30 to 40%.

13. Processing unit (1000) comprising: - a packing tank (1) according to any one of claims 10 to 12, - a means of supplying (7) the aqueous suspension, - a means of dispersing (3) the aqueous suspension, - a means for redispersing (10) the liquid effluent from the packing, preferably identical to the dispersion means (3), - a means of extracting (5) inert matter and / or sludge from the liquid effluent exiting the packing, and - a recirculation loop (2) allowing the redispersion over the packing of at least a portion of the liquid effluent exiting the packing, said loop (2) comprising a receiving tank (4), and possibly a buffer tank (8).

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