Method for sanitizing an animal by-product

Abstract

A process for sanitizing an animal by-product by heat treatment, characterized in that the heat treatment is carried out in a heat conditioner and comprises a heating step by direct contact of the by-product with a solid conductive surface of a heating element of the conditioner. The heat-treated animal by-product is then cooled using a cooling device. Figure for the abstract: Figure 1

Description

Title of the invention: Method for sanitizing an animal by-product Field of invention

[0001] The invention relates to an industrial process for the sanitization of an animal by-product, which allows the recovery of said product, in particular as a fertilizer, while limiting environmental disturbances (odors, etc.). Description of the prior art

[0002] Livestock effluents can contain pathogenic microorganisms and their destruction is essential to limit the health risks associated with the spreading of these effluents on agricultural land. For example, poultry droppings are preferred vectors for salmonella or other pathogenic bacteria.

[0003] The European Union health regulations on animal by-products and derived products provide that some of these by-products can be used to produce organic fertilizers or amendments. For these materials presenting a health risk, a processing step (defined in this application by the term hygienization) is necessary prior to their use, more particularly their use in a mixture. Thus, for the manufacture of fertilizers or organic amendments prepared (for example in the form of granules), livestock products must have a processed (hygienized) status to be used (Regulations (EU) 1069 / 2009 and (EC) 142 / 2011). At the regulatory level, this processed status is obtained by heat treatment (heating) of the material to a minimum core temperature of 70°C and for a minimum duration of 60 minutes.

[0004] The composting technique is often authorized by derogation but does not guarantee the total destruction of all pathogenic germs (Socrate A., 2000). Furthermore, this process of biological transformation of organic matter by fermentation consisting of putting the effluents in a windrow and carrying out several turnings which will allow good oxygenation and a rise in temperature is not easy to control. The product to be composted must also contain sufficient water to allow fermentation; however, this level of humidity is not always compatible with the subsequent use of the product, for example for its granulation.

[0005] There are thus different processes for reducing pathogenic microbial populations in these materials. Studies have focused on chemical treatments (acids, urea, chlorine, lime, etc.) which may prove interesting, but the products obtained cannot generally be used in organic farming. The most effective methods appear to be those based on thermal treatments (e.g., pasteurization). rization, sterilization).

[0006] Current processes for drying droppings by contact between droppings and hot air carried out in livestock farming are not sufficient on their own to guarantee effective hygiene of products (Derel and Aubert, 2008). In addition, these processes using hot air generate large volumes of air which must then be treated to eliminate unpleasant odors.

[0007] Kim et al., 2012, studied the inactivation by heating in an oven of salmonella contained in poultry droppings at different temperatures, different humidity levels and according to the composition of the droppings. This process by convection and thermal radiation is however not industrializable.

[0008] US2019 / 0117804 (Detzel) describes the use of a "cooling" tower, a tower which is modified to become a heating tower and is used for the hygienization of animal by-product pellets. The animal by-products are poured at the top of the column and fall continuously in the tower to a discharge screw. They come into contact with heated coils. This device does not describe any means of agitation or mixing allowing the by-products to be mixed. This device has several disadvantages: a caking or crusting effect can occur due to the silo flow (in a funnel) where part of the by-product remains fixed on the heating coils, making them ineffective. In addition, it is possible that some by-product does not touch the coils and is therefore not hygienized. At a minimum, this device requires superheating to reach the desired hygienization temperature and therefore a large energy loss.

[0009] WO02 / 24585 (SEGHERS BETTER TECHNOLOGY GROUP) describes a method of pelletization by drying sludge and not a sanitation process. In particular, the starting product to be treated is a liquid or semi-liquid and not a solid product.

[0010] WO2012115589A1 (TELGE NÀT AB) describes the use of reactors for hy- to process a liquid animal by-product using a mixing bioreactor. This device does not use a thermal conditioner and also deals with the processing of liquid animal or human by-products.

[0011] There is therefore a need to propose a process for the hygienization of animal by-products which can be industrialized and which meets several criteria:

[0012] - process meeting health regulations: the process must easily allow the temperature of the material to be treated to be controlled (minimum 70°C at the heart of the product according to the regulations in force on the date of filing of the present invention) and the duration (minimum 60 minutes according to the regulations in force on the date of filing of the present invention);

[0013] - taking into account the properties of certain materials to be sanitized such as livestock effluents (especially poultry droppings): risk of crusting (cementation) of the material, risk of corrosion and abrasiveness;

[0014] - the agronomic value of the product obtained by the process: nitrogen content (N), moisture content, etc. For example, in order to pelletize poultry droppings, the moisture content of the resulting product is an important criterion, as the droppings must not be too wet;

[0015] - hygienized animal by-products with good preservation during their storage at room temperature. Description of the invention

[0016] Surprisingly, it has emerged that the use of a thermal conditioner (or cooker) allows effective hygienization at the industrial level of animal by-products, and in particular of solid animal by-products. The addition of a cooling step following the heat treatment step allows good preservation at room temperature of the hygienized animal by-products.

[0017] This process also has several advantages:

[0018] - Safety and environmental risks (dust levels, fog, odor and fouling) are limited. For comparison, the Applicant tested a process in which a reactor comprising a conveyor screw was implemented in which poultry droppings were thermally treated by injecting steam or hot air into the reactor. This sanitation process with significant air flows is not very suitable due to the release of unpleasant odors from the treated droppings as well as the high energy consumption.

[0019] - Adaptation of the process to industrial constraints in the factory: size, flow rate, satisfactory automation. The Applicant also observed the absence of crusting and caking of the treated material on the walls of the conditioner. For comparison, the reactor comprising a conveyor screw tested by the Applicant as described above was not conclusive insofar as the control of flow rates (reactor filling rate) and material residence times were not satisfactory.

[0020] - Economic aspect of the process: limited investment and operating costs, in particular due to the heating of the material to be treated by direct contact with the heating element of the conditioner and the fact that the heat transfer fluid of the conditioner circulates in a closed circuit, compared to processes using steam or hot air in direct contact with the material to be treated as tested by the Applicant.

[0021] Thus one aspect of the invention is a method for sanitizing an animal by-product, and in particular a solid by-product, by heat treatment, characterized in that the heat treatment is carried out in a heat conditioner, said heat conditioner comprising an enclosure, at least one solid heating element (4) having, inside the enclosure,

[0022] - a direct contact surface (solid conductive surface) with a solid material to heating which allows the conduction of heat,

[0023] - means for maintaining said heating surface at a temperature of desired heating, and

[0024] - guide means (6) for stirring, mixing and / or kneading said material solid to be heated on said contact surface,

[0025] said method comprises a step of heating by direct contact of the by-product with said conductive surface of said solid heating element of said conditioner and where the animal by-product to be sanitized has a dry matter content of at least 45% by mass,

[0026] and wherein the heat-treated animal by-product has a temperature of at least 70°C and is then cooled using a cooling device.

[0027] Cooling means active cooling as opposed to natural cooling of the animal by-product that has been heat-treated. Natural, or passive, cooling consists of leaving the product exposed to the ambient atmosphere without promoting heat exchange by the application of means primarily intended to promote or accelerate the lowering of the temperature of the product and / or the thermal equilibrium of the product with its environment.

[0028] Advantageously, the animal by-product which has been heat-treated is cooled to a temperature below 50°C, preferably below 45°C, more preferably below 40°C, in less than 48 hours and in ascending order of preference in less than 24h, 12h, 6h, 1h, 30 minutes, 15 min, 10 min, 5 min, 3 min.

[0029] Preferably, the animal by-product which has been heat-treated and has a temperature between 70°C and 90°C, in particular between 70°C and 80°C, is cooled to a temperature below 45°C, in particular between 30°C and 45°C, in less than 5 min.

[0030] This cooling step makes it possible to safely store the animal by-product that has been heat-treated at room temperature (e.g., preventing a risk of fire of the by-product, avoiding operators handling a hot product) while preserving its quality (e.g., avoiding caking, microbial contamination and / or fermentation of the by-product).

[0031] Thermal conditioners (also called heaters or cookers) are conduction heating devices that are conventionally used for the pretreatment of oilseeds in order to facilitate the extraction of oil from these seeds during crushing processes. The purpose of this heating is to finely control the moisture content of the oilseeds and prepare them for crushing to extract oil. These devices are well known in the field of vegetable oil extraction: Laisney et al., 1984: chap. II.5 vertical cookers pll6 - 120 and horizontal cookers pl20- 121; Unger EH, 2011 pages 169-170 and Debryune I, 2001.

[0032] A conditioner consists of an enclosure, most often a horizontal or vertical cylindrical body. A typical conditioner comprises one, and generally several, solid heating elements having, inside the enclosure, a contact surface with the solid material to be heated which allows the conduction of heat. The material to be heated comes into direct contact with the heating element while being stirred and / or mixed on the surface thereof. The conditioner therefore also comprises guide means for stirring, mixing and / or kneading the material to be heated on said contact surface, or "heating surface". These means make it possible in particular to homogenize and optimize the heating.

[0033] The heating surface of a conditioner is maintained at the desired heating temperature by various known means. For example, the heat source of the heating surface may be an electrical heating resistor or a heated fluid, preferably a heat transfer fluid, such as a liquid (for example water) or a gas (for example steam). The heat transfer fluid circulates in a closed circuit between a heat source and the heating surface of the conditioner. The heat transfer fluid therefore does not come into contact with the material to be heated. Thus, the heat transfer fluid does not require filtration or washing treatment; the heating of the heating surface is carried out exclusively by conduction in a closed circuit. Advantageously, the heating surface comprises, or consists essentially of, a metal alloy.

[0034] The means for guiding the material on said heating surface may comprise blades, paddles or scrapers, which may move in rotation or translation.

[0035] There are two types of conditioners: vertical conditioners and horizontal conditioners. The size of the conditioners depends on the volumes of material to be processed and the desired throughput of processed material. Advantageously, the throughput is between 1 and 10 tonnes / hour, preferably between 4 and 6 tonnes / hour.

[0036] In horizontal conditioners, where the longest dimension of the enclosure is its length, the heating surface may comprise an internal surface of the enclosure. In this case, the materials to be heated are moved by an internal mixer, such as a moving helical ribbon. In the case where the enclosure comprises a drum rotating about a horizontal axis, the materials to be heated are moved due to the combined effects of gravity and the rotation of the drum.

[0037] In vertical conditioners, where the largest dimension of the enclosure is its height, the heating surface may comprise a series (i.e. at least two) of heating elements, such as plates (also called heating trays), superimposed one above the other and constituting stages. These stages are gener- similarly structured rattling. The number of stages generally varies from 1 to 15. A number of stages from 5 to 9, in particular from 6 to 8, for example 7, is particularly suitable for the method according to the invention.

[0038] In vertical stage conditioners, the circulation of the material is usually ensured by a system of rotating mixers fixed on a vertical shaft passing through the stages. The mixers most often have stirring vanes, for example of the paddle type, which allow the mixing of the material to be treated on the heating surface of each stage. At each stage, an opening, preferably removable, allows the material to be treated to be moved from one stage to another. These openings can be controlled by doors.

[0039] As is known, a conditioner also comprises an inlet opening for the materials to be treated, for example a feed screw, and an outlet opening for the treated materials, for example an extraction screw, making it possible to recover the treated material.

[0040] Many specialist companies offer these types of conditioners, including OLEXA, BUHLER, DESMET BALLESTRA, etc.

[0041] An example of a conditioner that can be used for implementing the invention is shown in [Fig.l]. A vertical cylindrical enclosure comprises heating elements such as horizontal heating plates (4). These heating plates (4) comprise a double enclosure in which steam (3) circulates. Blades (6) mounted on a rotating axis (9) and driven by a motor (2) are used to guide the treated materials. The raw animal by-product (1) is introduced at the top of the enclosure through a valve (12), for example a butterfly valve, and comes into contact with the heating plate (4) constituting stage 1. When the filling reaches a certain high level (NH), it is stopped. A rotating blade (6) drives and moves the raw material onto the surface of the heating plate (4) of stage 1.Advantageously, each stage is equipped with a thermal probe (11) for measuring the core temperature of the treated material and an access hatch (10). A removable door (5) allows the treated material to be tipped by gravity from one stage of the conditioner to the lower stage. The opening of this door can be triggered when a certain filling level (e.g. NH) is reached. An outlet valve (7) allows the heat-treated animal by-product (8) to be collected once the treatment has been carried out.

[0042] Unexpectedly, the use of such conditioners makes it possible to sanitize animal by-products without requiring substantial modifications, for example compared to their use for conditioning seeds. Any conditioner of the prior art can be used and in particular those described above. Vertical conditioners, and in particular those whose heating elements are metal alloy plates are particularly preferred.

[0043] Also, the method according to the invention advantageously comprises a step of introducing an animal by-product into a thermal conditioner, a step of heat treatment by conduction comprising a step of direct contact of the by-product with a solid conductive surface of a heating element of the conditioner and a step of cooling the thermally treated by-product. This contact step is carried out for a duration allowing the sanitization of the product and in particular its core heating to a target temperature. In particular, a minimum target temperature of the by-product of 70°C must advantageously be reached. It is also advantageous for the minimum core heating temperature of the product to be reached for a period of time, in particular for a minimum duration of 60 minutes.This minimum temperature of 70°C and this minimum duration of 60 minutes meets the health regulations concerning the sanitization of an animal by-product, in force on the filing date of the present invention. This minimum temperature / minimum duration pair can be modulated according to the evolution of these regulations.

[0044] Once the treatment step has been carried out and sanitation has been achieved, the animal by-product is advantageously extracted from the conditioner enclosure by appropriate means such as, for example, an extraction screw, or simply by gravity. The heat-treated animal by-product is then cooled using a cooling device (cooler).

[0045] Thus, the method according to the invention can make it possible to sanitize animal by-products in an energy-efficient and industrial manner without causing fouling phenomena and while making it possible to limit emissions of volatile compounds, and thus the associated pollution, particularly odorous pollution, for the environment. The odors emitted during the treatment of this animal waste are in fact a significant environmental problem.

[0046] Unlike other industrial hygienization processes, and as described above, the heating of animal by-products is carried out predominantly by conduction.

[0047] The transfer of energy by heat is generally achieved by a combination of several transfer modes: conduction, due to the progressive diffusion of thermal agitation in the matter; convection, thermal transfer which accompanies the macroscopic movements of the matter; radiation, which corresponds to the propagation of photons.

[0048] Unlike existing hygienization processes, the animal by-product is not heated by direct contact with hot air or a flow of hot air and in particular by a flow of hot air coming from outside the device (i.e. passing through the conditioner). Alternatively or additionally the conditioner is not heated by hot air whose temperature is substantially higher than the target temperature (e.g. higher than 80°C). Preferably, according to the method according to the invention, the animal by-product is not heated by convection or thermal radiation.

[0049] According to a particular aspect of the invention, the heat treatment is carried out without adding water to the animal by-product.

[0050] According to a particular aspect of the invention, the heat treatment is carried out at atmospheric pressure.

[0051] According to a preferred aspect of the method according to the invention, the heat treatment heats the animal by-product to a core temperature greater than or equal to 70°C, preferably between 70°C and 90°C.

[0052] According to a preferred aspect of the method according to the invention, the heat treatment is carried out for at least 60 minutes, in order to correspond to the regulatory minima of treatment time and temperature.

[0053] According to a preferred aspect of the method according to the invention, the heat treatment is carried out in an atmosphere of normal composition and advantageously does not require the establishment of an inert atmosphere, or one more inert than the normal atmosphere. Thus, it may advantageously be required not to inject water vapor during the implementation of the method.

[0054] It is obvious that when implementing the method according to the invention, there will always necessarily be additional phenomena of convection and thermal radiation. However, these phenomena are not the predominant transfer modes in a conditioner, which is recognized in the field as a conduction heating device. At the industrial level, the person skilled in the art knows how to recognize which energy transfer is the predominant energy transfer by determining the quantity of heat Q associated with each type of transfer. Also, a heating method excluding the use of convection or irradiation excludes this means as a principal or predominant method and not as a secondary or subsidiary method.

[0055] Advantageously, the animal by-product is transferred from the conditioner to the cooling device by suitable means such as, for example, a screw or a connecting hopper.

[0056] There are various cooling methods that allow the heat-treated animal by-product not to be denatured. These are mainly methods in which the heat-treated by-product is cooled by direct contact (preferably air) or by indirect contact with a cooling fluid (refrigerant heat transfer fluid).

[0057] Among the methods of cooling by direct contact with air (re- convection cooling), we distinguish:

[0058] - counter-air cooling: there are cooling devices vertical counter-airflow or horizontal belt and cross-flow. Examples include devices sold by manufacturers STOLZ, GEELEN, CPM;

[0059] - fluidized bed cooling which allows cooling of a product which is conveyed by a sloping vibrating system. The air used for cooling can be ambient air or pre-cooled air. Examples include devices sold by the manufacturers COMESSA, SABE, SCHULE, JOEST;

[0060] - batch cooling, where it involves cells containing a product to be cooled and whose floor is perforated allowing a current of air to circulate in the product arriving from the bottom and leaving towards the top. We can cite for example devices sold by the manufacturer GICOM.

[0061] Among the methods of cooling by indirect contact (i.e., by contact on a cold wall), we distinguish:

[0062] - heat exchangers which allow a transfer of energy between a product to solid state and at least one fluid at different temperatures. The solid to be cooled and the fluid are separated by a transfer surface, generally metallic. In these indirect systems, the refrigerant exchange relies on a refrigerated fluid that circulates in a closed circuit in the exchangers. In the majority of cases, the fluids are in the liquid or gaseous state (e.g., water, air). Tubular heat exchangers are particularly suitable for this cooling method. Examples include devices sold by the manufacturers SERMIA and THERMOFIN.

[0063] According to a preferred aspect of the method of the invention, the cooling device is a double-jacketed tubular heat exchanger (internal and external) comprising a rotor and a stator, where the external jacket contains a refrigerated fluid (e.g., glycolated water, hydrofluorocarbons) at a temperature generally between -10°C and +10°C. The product to be cooled, driven by a rotor (e.g., an Archimedes screw system), passes through the stator of the exchanger and exchanges its calories by indirect contact with the refrigerated fluid contained in the external jacket. The product thus emerges having been cooled. This device is particularly advantageous insofar as, with the product to be cooled circulating inside the tube, the release of unpleasant odors is limited, in particular for operators and the neighborhood. A deodorization installation can also be provided but is not essential.The product is not denatured because there is no direct contact with the refrigerated fluid. The risk of re-contamination by microorganisms is also limited due to the closed circuit operation and a short residence time.

[0064] At the industrial level, the person skilled in the art knows how to implement a device for cooling a solid material. Preferably, this device is a heat exchanger. Double-jacketed tubular heat exchanger comprising a rotor and a stator, where the outer jacket contains a refrigerated fluid, such as a refrigerated liquid.

[0065] An animal by-product is understood to mean a product of animal origin, in particular from a farm animal, which is not intended for human consumption. The by-product is advantageously a category 2 material in accordance with Regulation (EC) No 1069 / 2009 of the European Parliament and the Council of 21 October 2009.

[0066] Advantageously, the animal by-product to be sanitized is slurry or the contents of the digestive system of an animal, such as a pig, sheep, bovine, insect and / or poultry. It may be a livestock effluent which may be chosen from the group consisting of poultry droppings (for example chicken), poultry manure (for example chicken), poultry compost (for example chicken), cattle manure compost, insect frass (insect manure), cattle manure, pig manure and mixtures thereof. Preferably, the animal by-product is poultry droppings, poultry manure and / or insect frass. Particularly preferably, the animal by-product is poultry droppings or poultry manure, very preferably poultry droppings, in particular dehydrated (dried).

[0067] The method of the invention makes it possible to sanitize and cool different types of animal by-products having a varied humidity level. Preferably, this is at most 55% by mass, which corresponds to a dry matter (DM) level of at least 45% by mass. More preferably, this is at most 40% by mass, which corresponds to a dry matter (DM) level of at least 60% by mass. Also, the method according to the invention is particularly suitable for sanitizing droppings from laying hens from cage-type farms, free-range farms or aviaries.

[0068] Manure, particularly from laying hens, can be pre-dried in breeding by different systems, notably those using hot air from breeding buildings (drying by tunnel or duct, Derel and Aubert, 2008).

[0069] The animal by-product to be sanitized may contain straw, wood shavings or sawdust (e.g. manure).

[0070] The animal by-product to be sanitized is advantageously in the form of particles, ground materials, aggregates or powders, in particular irregular or homogeneous, but whose particle size is preferably less than or equal to 12 mm, and advantageously less than or equal to 8 mm, and even more advantageously less than or equal to 5 mm.

[0071] According to a preferred variant of the method according to the invention, the animal by-product to be sanitized has a low and / or controlled humidity level. It is advantageously dried or dehydrated.

[0072] According to a preferred variant of the process according to the invention, the animal by-product to be sanitized has a dry matter content of at least 45% by mass, preferably of at least 65%, even more preferably of at least 75%.

[0073] According to a variant of the method according to the invention, the animal by-product to be sanitized has, for example, a dry matter content of less than 95% by mass, or less than 90%, or less than 85%.

[0074] According to a variant of the process according to the invention, the animal by-product to be sanitized has a dry matter content of between 45% and 85% by mass.

[0075] According to a preferred variant of the process according to the invention, the animal by-product to be sanitized can therefore be used raw or dried, depending on the nature of the starting by-product.

[0076] According to an advantageous aspect of the method, it may comprise a preliminary step of drying (dehydration) of the animal by-product to be sanitized. This drying (dehydration) step may be carried out by evaporation or by solid-liquid separation, in particular mechanical (decanter, filter or sieve, screw press or centrifuge, etc.). A method commonly used in poultry farming is the drying of animal by-products by direct contact with the hot air obtained from the livestock buildings.

[0077] The animal by-product, once heat-treated and cooled according to the method according to the invention, is a hygienized animal by-product, that is to say that it no longer presents major risks for the environment and / or users. In particular, it has a substantially reduced load of pathogenic organisms and in particular of Escherichia coli, enterococci, salmonella and / or helminth eggs, preferably of Escherichia coli and enterococci. This load may be less than 1000 CFU / g, preferably less than 600 CFU / g and advantageously less than 300 CFU / g (for example less than 100 CFU / g).Also, one aspect of the invention relates to a hygienized animal by-product characterized in that it is advantageously obtained by the process according to the invention, and that it can have a load of Escherichia coli or enterococci of less than 500 CFU / g, preferably the absence of salmonella, and a dry matter content advantageously between 80% and 95% by weight.

[0078] Preferably, said animal by-product comprises hygienized poultry droppings (e.g. from laying hens) or insect droppings.

[0079] Preferably, the hygienized animal by-product obtained is in the form of powder or free or detached particles and advantageously is not in the form of compressed or compacted granules (pellet).

[0080] Another aspect of the invention relates to the use of a conditioner, in particular a conditioner as described above, for the hygienization of an animal by-product, in particular a by-product as mentioned above.

[0081] Another aspect of the invention relates to a hygienized animal by-product characterized in that it is obtained by the method according to the invention. Advantageously, the by- sanitized product is as described above.

[0082] Yet another aspect of the invention relates to the use of a hygienized animal by-product, as described above, as a fertilizer and / or for providing organic matter to the soil and crops.

[0083] Another aspect of the invention relates to an animal by-product hygienization system characterized in that it comprises a conditioner, a cooling device and an animal by-product as described above. Preferably, said cooling device is a double-jacketed (internal and external) tubular heat exchanger comprising a rotor and a stator, where the external jacket contains a refrigerated fluid at a temperature generally between -10°C and +10°C, as described above.

[0084] According to another preferred aspect of the invention, the hygienization system is preferably devoid of means for making the internal atmosphere of said system more inert. According to a particularly preferred aspect, said system is devoid of a steam generator and / or a steam distribution circuit inside the device. Description of figures

[0085] [Fig. 1] is a diagram of a typical vertical conditioner or cooker that can be used in the method according to the invention;

[0086] [Fig.2] is a graph tracking the core temperature of ther-treated products mically from example 1 for 60 min in the conditioner. Example 1: • Materials and methods

[0087] Different category 2 animal by-products (intermediate health risk, EC Regulation No. 1069 / 2009) were tested: three sources of dehydrated poultry droppings (cage rearing, free-range rearing, aviary rearing) and insect frass. The products were in ground form, with a particle size of less than 5 mm.

[0088] The reference methods for the different measurements are as follows:

[0089] For agronomic measurements, dry matter contents (NF EN method 13040), organic matter (method NF EN 13039), nitrogen (Dumas method NF EN 13654-2), phosphorus, potassium, calcium and magnesium (method adapted from NF EN 13650, dosage according to NF EN ISO11885) were carried out. The NF methods are those available on the date of filing the application.

[0090] For bacteriological measurements, 5 (T0 to T4) samples (products treated “T”) of 25g per material were taken in the conditioner. The contents of Escherichia coli (method NF ISO 16649-2), enterococci (analyses on SLANETZ medium (conf on Bile-Esculin-Azide (BEA) agar), method at 37°C for 48 hours), salmonella (method NF EN ISO 6579-1) were measured.

[0091] In addition, humidity analyses were carried out using a humidity meter (KERN Desiccator) just before and after treatment to assess the impact on the drying of the product.

[0092] Table 1: Typical agronomic characteristics of products before hygienization, average contents and standard deviation.

[0093] [Tables 1] Data in g / kg raw product Caged laying hen droppings (Levasseur et al. 2019) Aviary laying hen droppings (Ponchant et al. 2018) Free-range laying hen droppings (Ponchant et al. 2018) Frass - Insect manure Dry matter 848 462(101) 574(118) 719 Organic matter 628 368 (91) 316(88) 684 Total nitrogen 39.5 20.2 (4.0) 22.0 (9.6) 31.5 p2o5 37.8 13.6 (4.4) 28.8 (8.6) 32.8 k2o 25.7 12.3 (4.4) 20.8 (4.8) 27.4 CaO 79.6 33.1 (10.9) 79.3 (23.9) 4.0 MgO 8.7 5.5 (1.4) 9.2 (1.9) 9.9

[0094] Table 2: Bacteriological characteristics of the products tested before hygienization (2 samples per material)

[0095] [Tables2] Laying hen droppings Cage CFU / g Laying hen droppings Aviary CFU / g Laying hen droppings Free range CFU / g E. coli 123,000 680,000 50,500 Enterococci <10,000 <10,000 130,000

[0096] The horizontal conditioner (or cooker) (Olexa, Arras, France) used in the examples is composed of two nested horizontal cylinders. The lower part of each cylinder is heated by several resistors; the heat being transported by a circulation of thermal fluid in the casing of the conditioner. Inside the conditioner, the materials are mixed by a moving helical ribbon.

[0097] Approximately 50kg of materials were used for each type of by-product. The condi- The donor was preheated to 100°C to allow the target temperature of 70°C to be reached at the core of the product. The product was then introduced into the conditioner and kept there for one hour.

[0098] Regular sampling by thermometric probe made it possible to monitor the temperature within the conditioner. The data is shown in the graph in [Fig.2]. Temperature monitoring is simple to carry out and compliance with the time / temperature pair (70°C / Ihr) is well respected.

[0099] Monitoring core temperatures during the product temperature rise phase revealed a fairly low thermal inertia of poultry droppings: rapid temperature rise and cooling.

[0100] Humidity measurements were carried out on the starting materials and at the output of the device. The values ​​obtained are compiled in Table 3:

[0101] Table 3: Evolution of dry matter (DM) in mass after keeping the products at 70°C for 1 hour

[0102] [Tables3] Batch Slurry typology Origin Initial DM% Final DM % Difference % 1 Dried (dehydrated) poultry droppings Cage rearing 81.0 90.0 9.0 2 Dried (dehydrated) poultry droppings Free-range rearing 76.5 81.8 5.3 3 Insect manure Frass Hermetia illucens rearing 79.5 82.5 3.0 4 Dried (dehydrated) poultry droppings Aviary rearing 81.7 89.4 7.7

[0103] The products, which initially had rather high dry matter levels, between 76.5 and 81.7% by mass of dry matter (DM), lost between 3 and 9 moisture points which is satisfactory for an industrial application (Table 3). The target in this example is to have products at approximately 85% by mass of DM.

[0104] All agronomic values ​​were measured and the values ​​obtained are compiled in Table 4:

[0105] Table 4: Agronomic results after keeping the products at 70°C for 1 hour

[0106] [Tables4] Data in g / kg raw product Caged laying hen droppings Aviary laying hen droppings Free-range laying hen droppings Frass - Insect manure Dry matter 885 893 811 852 Organic matter 635 638 604 719 Total nitrogen 39.1 46.2 31.6 27.6 p2o5 27.2 33.2 25.9 35.7 k2o 29.8 36.6 23.6 34.0 CaO 88.6 98.1 73.5 0.8 MgO 10.1 12.5 9.1 7.9

[0107] The results obtained are consistent and only reflect the slight concentration of the products linked to the loss of humidity (Table 4). The results do not highlight other phenomena (chemical reaction, volatilization of ammonia, etc.).

[0108] Agronomic and bacteriological measurements were carried out on outgoing products (heat-treated products).

[0109] The bacteriological results of the 5 samples (T0-T4) are all compliant (Table 5) and respect the thresholds expected by the transformation process. The E. coli and enterococcus load thresholds at the process outlet to be respected are as follows: load less than 1000 CFU / g, on 5 samples.

[0110] Table 5: Summary of bacteriological results (average of the 5 analyses per product) [YES] [Tables5] Products Caddy droppings CFU / g Droppings - Outdoor CFU / g Frass CFU / g Flying droppings CFU / g Regulations - processed product (1069 / 2009) CFU / g E. coli T0 <100 <100 <100 <100 <1000 E. coli Tl <100 <100 <100 <100 <1000 E. coli T2 <100 <100 <100 <100 <1000 E. coli T3 <100 <100 <100 <100 <1000 E. coli T4 <100 <100 <100 <100 <1000 Enterococcus T0 <100 <100 <100 <100 <1000 Enterococcus Tl <100 <100 <100 <100 <1000 Enterococcus T2 <100 <100 <100 <100 <1000 Enterococcus T3 <100 <100 <100 <100 <1000 Enterococcus T4 <100 <100 <100 <100 <1000

[0112] The method makes it possible to reduce the load of E. coli and enterococcus in a substantial and acceptable manner for regulatory purposes.

[0113] Finally, the observations made during the tests, in terms of dust, odor, fog, and fouling did not reveal any particular problems for an application in industrial conditions.

[0114] The absence of crusting (cementation) of the treated material on the walls of the conditioner was also observed.

[0115] In terms of odor, the initial products already have a slight odor that was present during the tests. However, the vicinity of the cooker, which does not include a deodorization device, did not present any exacerbation of the odors for the operators. Example 2:

[0116] Poultry droppings, insect frass and poultry compost were treated according to the method of Example 1. The products were in the ground form, either small particles (droppings and frass < 5mm (sieve)), or, in the case of poultry compost, in the form of coarser particles. In all cases the starting material showed a certain heterogeneity, particularly in the case of agricultural compost.

[0117] It has appeared that the process according to the invention, by the use of a conditioner, refines the granulometry and the homogeneity of the heat-treated product. The elements of the conditioner "work" the material. In addition, natural sieving takes place when the product is very heterogeneous (heat-treated manure, poultry compost) with fine particles coming out first and coarse particles (clods, straw, etc.) coming out last when the process is carried out in "batch" mode. Frass offers a very nice product presentation with a fine and homogeneous particle size and without dust. • Conclusion

[0118] The method according to the invention is versatile and can be adapted to sanitize any type of animal by-product as described above. Surprisingly, no fouling problems were observed when implementing the invention. Example 3:

[0119] Poultry droppings were treated according to the method of Example 2. The flow rate was 5 tonnes / hour. The heat-treated droppings having a temperature of 70°C were then cooled to a temperature of 40°C in 3 min at a flow rate also of 5 tonnes / hour, using a double-jacketed tubular heat exchanger equipped with a motor-driven Archimedes screw (rotor). The outer jacket contained glycolated water at a temperature of 2°C. The heat-treated and cooled poultry droppings were stored at room temperature before use. No unpleasant odour or condensation on the pile was observed. List of cited documents

[0120] - Debruyne L, 2001. Soya: processing and industrial aspects; Techniques of the Engineer RefF6030 vl., 18p.

[0121] - Derel R. and Aubert C., 2008. Evolution of the microbiological quality of droppings of laying hens after drying and during storage, TeMA, vol. 7, 4-11.

[0122] - Laisney J., 1984. The modern oil mill. Paris, CFDT (French Company for the development development of textile fibers), 318p.

[0123] - Métras R., 2003. Uses and microbiological health hazards linked to Livestock effluents, Single doctoral thesis in veterinary medicine, Claude Bernard University, France, 150p.

[0124] - Ponchant P. et al., 2018. Characterization of poultry effluents, TeMA, vol 47, 35-41.

[0125] - Socrate A., 2000. What treatments for effluents from industrial livestock farms? poultry? ENGREF bibliographic summary.

[0126] - Unger EH, 2011. Processing. In: Canola-Chemistry, Production, Processing and Utilization, edited by Daun JK, Eskin NAM and Hickling. D. AOCS Press, Urbana, Chapter 6, pp. 163-188.

[0127] - Kim et al., 2012, Validating Thermal Inactivation of Salmonella spp. in Fresh and Aged Chicken Litter, Applied and Environmental Microbiology p. 1302-1307.

[0128] - Levasseur P. et al., 2019. Agronomic recovery of livestock effluents from pigs, cattle, sheep, goats, poultry and rabbits. RMT Livestock and Environment, Paris, 83 pages.

Claims

Claims

1. Method for sanitizing a solid animal by-product by heat treatment, characterized in that the heat treatment is carried out in a heat conditioner, said heat conditioner comprising an enclosure, at least one solid heating element (4) having, inside the enclosure, - a surface for direct contact with a solid material to be heated which allows the conduction of heat, - means for maintaining said heating surface at a desired heating temperature, and - guide means (6) for stirring, mixing and / or kneading said solid material to be heated on said contact surface, said method comprises a step of heating by direct contact of the by-product with said conductive surface of said solid heating element of said conditioner and where the animal by-product to be sanitized has a dry matter content of at least 45% by mass,and in that the heat-treated animal by-product has a core temperature of at least 70°C and is then cooled using a cooling device.,

2. The method of claim 1, wherein the by-product is not heated by direct contact with hot air, particularly with hot air from outside the conditioner.

3. The method according to claim 1 or 2, wherein the animal by-product to be sanitized is a livestock effluent, preferably selected from the group consisting of poultry droppings, poultry manure, poultry compost, cattle manure compost, insect frass, cattle slurry, pig slurry and mixtures thereof, more preferably poultry droppings.

4. The method of any one of claims 1 to 3, wherein said heat treatment heats the animal by-product to a core temperature between 70°C and 90°C.

5. The method of any one of claims 1 to 4, wherein said heat treatment is carried out for at least 60 minutes.

6. The method according to any one of claims 1 to 5, wherein said animal by-product to be sanitized is in the form of particles, granules or powders, the particle size of which is preferably less than or equal to 12 mm, and advantageously less than or equal to 8 mm, and even more advantageously less than or equal to 5 mm.

7. The method according to any one of claims 1 to 6, wherein the animal by-product to be sanitized has a dry matter content of at least 65% and more preferably at least 75%.

8. The method according to any one of claims 1 to 7, wherein the heat treatment is carried out under normal atmosphere and / or without injection of water vapor.

9. The method of any one of claims 1 to 7, wherein the heat-treated animal by-product is cooled to a temperature below 50°C in less than 48 hours.

10. Hygienized animal by-product characterized in that it is obtained by the process according to any one of claims 1 to 8, and in that the animal by-product is chosen from the group consisting of poultry droppings, poultry manure, poultry compost and insect frass, and has a load of Escherichia coli or enterococci of less than 500 CFU / g, the absence of salmonella, and a dry matter content of between 80% and 95% by weight.

11. A hygienized animal by-product according to claim 10, wherein said hygienized animal by-product is in the form of powder or free or detached particles.

12. Animal by-product sanitization system characterized in that it comprises a thermal conditioner, a cooling device and a solid animal by-product to be sanitized (1), said thermal conditioner comprising: - an enclosure, - at least one solid heating element (4) having, inside the enclosure, a surface of direct contact with a solid material to be heated which allows the conduction of heat, - means for maintaining said heating surface at a desired heating temperature, and - guide means (6) for stirring, mixing and / or kneading said solid material to be heated on said contact surface.

13. Hygienization system according to claim 12, wherein the animal by-product to be hygienized (1) has a dry matter content of at least 45% by mass.

14. A sanitizing system according to claim 12 or claim 13, wherein the system comprises an internal atmosphere and is devoid of means for rendering said atmosphere more inert.

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