PROCESO PARA DIGESTION ANAEROBICA DE MATERIAL CARBONOSO

Abstract

The invention involves a process for treating carbonaceous material, such as sewage sludge or organic waste, comprising the steps of: (1) performing a thermal treatment of said carbonaceous material, thereby providing heat-treated carbonaceous material, (2) cooling said heat-treated carbonaceous material, thereby providing cooled carbonaceous material, and (3) performing further treatment of said carbonaceous material, wherein the cooling of step 2) is carried out using a vacuum cooling step.

Description

PROCESS FOR ANAEROBIC DIGESTION OF CARBONOSE MATERIAL FIELD OF THE INVENTION The present invention relates to the treatment of carbonaceous materials comprising a thermal pretreatment stage. More specifically, it relates to the treatment of sludge or organic waste that includes at least one biological treatment stage, such as anaerobic digestion. BACKGROUND OF THE INVENTION Anaerobic digestion is a key process for recovering the energy initially present in carbonaceous material, such as wastewater and organic waste, in the form of biogas. Improved digestion efficiency leads to increased energy production, paving the way for energy-independent wastewater treatment plants (WWTPs) and other waste treatment facilities. However, anaerobic digestion exhibits limitations in the initial hydrolytic stage, resulting in slow degradation of organic matter and long retention times in the digester. To enhance the kinetics of anaerobic biodegradation, numerous pretreatment technologies have been developed to accelerate the limiting hydrolysis stage and improve biogas productivity, as well as the characteristics of the digested carbonaceous material (or sludge). An improved state-of-the-art digestion process, with different examples of hydrolysis pretreatment stages implemented upstream of a mesophilic digester, is shown in Figure 1. The hydrolysis pretreatment stage (PT) can be either thermal hydrolysis (TH) or biological hydrolysis (BH), carried out in a tank (H). The pretreatment stage can also include a pre-dewatering stage (carried out in a pre-dewatering unit DU) and storage of the carbonaceous material in a storage unit (SS), where the carbonaceous material is pre-treated before entering the thermal treatment reactor (H). Thermal hydrolysis (THP) is the most widespread pretreatment technology used to enhance the anaerobic digestion (AD) of sludge in wastewater treatment plants (WWTPs). Thermal hydrolysis aims to improve the digestion efficiency and dewatering capacity of biological or mixed sludge by breaking down bacterial cell walls; the cell contents then become readily degradable anaerobically. Another method used to improve the rate-limiting hydrolysis stage is based on biological hydrolysis (BH), also known as Temperature Phased Anaerobic Digestion (TPAD or 2PAD). TPAD typically combines a short thermophilic pretreatment phase (1–3 days) (typically 50–70°C or 75°C) applied before conventional mesophilic anaerobic digestion (typically 35–38°C, 10–20 days). TPAD generally uses carbonaceous feed with a dry solids (DS) content ranging from 3–8% DS. Thermophilic-mesophilic TPAD or 2PAD has been shown to be an effective treatment for increasing methane production and volatile solids (VS) destruction, compared to single-phase mesophilic digestion. Compared to thermal hydrolysis, biological hydrolysis shows lower yields in terms of sludge dewatering capacity and digestion efficiency (biogas production, with the biogas produced being stored in a biogas storage facility). However, biological hydrolysis is an attractive alternative because it requires lower capital expenditures and is particularly relevant in emerging countries. The TPAD allows the production of US EPA class B biosolids, while the 2PAD allows the production of class A biosolids. The beneficial reuse of biosolids through soil application is governed in the United States by the Environmental Protection Agency (EPA), specifically through EPA Rule 40 CFR Part 503 for Biosolids. Within Part 503, the quality of biosolids is defined and uses two commonly identified classifications: Class A biosolids and Class B biosolids. While Part 503 also defines quality standards regarding factors such as heavy metals, the focus of abatement (AD) processes and digestion improvements is on meeting requirements related to reducing the attraction of pathogens and vectors. In a TPAD / 2PAD system, the sludge must be cooled between the biological hydrolysis reactor H (thermophilic) (approximately 55°C) and the mesophilic digester D, generally to 37°C. Currently, in the downstream hydrolysis stage of a TPAD, sludge cooling occurs through heat exchangers (recovery or water / sludge heat exchangers, also designated as HEx) as shown in Figure 2. The water used in HEx is typically process water from the wastewater treatment plant. The size of the heat exchanger can be significantly large, as it depends on the process water temperature. In fact, the HEx sizing depends on the temperature difference across the heat exchanger between the cold side (cooling water) and the hot side (hydrolyzed sludge). The smaller the temperature difference, the larger the HEx. Multiple limitations of current configurations are encountered with current HEx. Viscosity varies significantly depending on the type of sludge and from site to site, which can have a major impact on the size of the heat exchanger (variability of the heat exchange coefficient) and induce a significant energy cost for pumping (significant pressure losses). This can make heat recovery HEx systems uneconomical or even impractical. It also limits the scalability of the process from one site to another. Many emerging countries are located in tropical or warm climates where the process water temperature (used for cooling) can be too high to efficiently cool the sludge (process water temperature is often above 20°C). This significantly increases the size of the HEx (Heavy Extraction Units), where the resulting pressure drop necessitates large pumping capacity and size, consequently making the solution energy-intensive and / or uneconomical. This is incompatible with the requirement to reduce energy consumption in countries where energy costs are high. This is why very few players in the market offer a TPAD / 2PAD in large industrial facilities, where the size problems of the HEx become unmanageable. Finally, deposits that occur in the heat exchanger can also decrease the quality of the exchange since they reduce the heat exchange coefficient. To overcome the aforementioned limitations, heat exchanger designs incorporate numerous safety margins to ensure proper operation. Consequently, cooling heat exchangers can be quite long. The longer the heat exchanger, the greater the pressure drop and, therefore, the higher the electrical consumption of the pumps. Furthermore, the heat exchanger must be maintained and kept free of scale buildup (deposits of grease, solids, and minerals can occur). These deposits continuously reduce the overall heat exchange to a value below the desired level, in addition to increasing the pump's pressure losses. And because the TPAD can be operated in batches, in which case it is called 2PAD, the heat exchanger can be used for only a fraction of the day, with no flow through it. During these batch phases, significant deposits can occur and adhere permanently to the walls of the HEx, further accelerating future deposits. Another difficulty of the current TPAD / 2PAD processes is the sludge preheating stage before being fed to the biological hydrolysis reactor. In a TPAD / 2PAD system, since the first phase (BH) operates under thermophilic conditions, it is necessary to preheat it. To reduce the heat requirements of this first phase, it is possible to use the hot hydrolyzed sludge to heat the cold raw sludge feeding the system. This heat recovery is generally carried out in a double hot sludge / water / cold sludge heat exchanger. Water is the energy transfer medium that carries the energy from the hot sludge to the cold sludge. This necessitates the construction of another heat exchanger to recover the energy. Another possibility is a hot sludge / cold sludge heat exchanger. In this case, the heat exchange coefficient is very limiting, and in terms of total mass, the mass of these sludge / sludge heat exchangers is equivalent to that of sludge / water / sludge heat exchangers, and consequently, their cost is also in the same range. The same deficiencies are found in anaerobic digestion processes that include an upstream pretreatment stage of anaerobic digestion, or when the carbonaceous material has to be pasteurized before being digested. BRIEF DESCRIPTION OF THE INVENTION The present invention almost eliminates the drawbacks of intermediate HEx described above. The disadvantages of preheating stages and additional costs can also be significantly reduced. The present invention relates in particular to a phased anaerobic digestion process MA / t / ZUZZ / UÓUOOD of temperature of wastewater sludge, organic waste, or any kind of carbonaceous material, either continuous (TPAD) or in batches (2PAD), where the cooling of the downstream sludge from the biological hydrolysis stage is carried out using a vacuum cooling stage. In one aspect, the present invention relates to a process for treating carbonaceous material, such as sewage sludge or organic waste, comprising the steps of: (1) performing a heat treatment of said carbonaceous material, thereby providing heat-treated carbonaceous material, (2) cooling said heat-treated carbonaceous material, thereby providing cooled carbonaceous material and recovered steam, and (3) performing a further treatment of said cooled carbonaceous material, wherein the cooling of step 2) is carried out using a vacuum cooling step. As used herein, a “carbonaceous material” is understood to be a mixture of organic and inorganic materials, such as biomass. In the invention, it may also be referred to as “organic matter.” Carbonaceous material is typically moist. Its dry solids content advantageously ranges from 3 to 25%. Examples of carbonaceous material are organic waste and / or sludge, and more particularly sludge from organic waste or drinking water or wastewater treatment plants. Typically, in the present invention, the carbonaceous material is a sludge, such as wastewater treatment sludge. Examples of sludge include municipal sludge, biological sludge, and fresh or raw sludge. As used herein, “vacuum cooling” is understood to mean evaporation under a vacuum, that is, at a pressure lower than atmospheric pressure. Generally, it refers to a rapid cooling technique for evaporating water from any suspension containing organic matter, such as sludge or organic waste, with the evaporation taking place under vacuum. It is sometimes referred to as “flash cooling” or “flash vacuum cooling” because the evaporation is nearly instantaneous. Vacuum cooling is typically operated at absolute pressures ranging from 0.055 to 0.480 bar (i.e., 5,500 to 48,000 Pa), such as from 0.055 to 0.170 bar (i.e., 5,500 to 17,000 Pa), or from 0.15 to 0.48 bar (i.e., 15,000 to 48,000 Pa). In this vacuum cooling stage, some of the water content of the sludge evaporates, producing steam at a temperature determined by the absolute pressure in the vacuum cooling vessel, herein referred to as “recovered steam.” In what follows, it may also be called “flash steam” or simply “steam.” Recovered steam is distinguished from “exhaust gas” or “non-condensable gas,” which is understood herein to be gas produced downstream from the cooling unit, not condensed, for example, in a subsequent heat recovery stage (typically at a temperature between 50°C and 80°C, and at a pressure equal to or close to the pressure in the vacuum cooling unit / stage, i.e., at an absolute pressure ranging from 0.055 to 0.48 bar (i.e., 5,500 to 48,000 Pa)).Exhaust gas generally comprises or consists essentially of N2 (nitrogen), H2S (hydrogen sulfide), CO2 (carbon dioxide), light hydrocarbons (saturated C1-C4 hydrocarbon chains, linear or branched, particularly methane), and / or NH3 (ammonia). ML / t / ZUZZ / UÓUOOD Advantageously, the heat-treated carbonaceous material (particularly sludge) is then cooled (e.g., to a temperature of around 37°C) before being temporarily stored (typically held in an intermediate holding tank) and / or for further treatment. As used herein, the “heat treatment” of step 1) is understood to mean that it comprises heating the carbonaceous material to 50°C or more, typically between 50°C and 90°C. Examples of heat treatment include low-temperature thermal hydrolysis (TH), biological hydrolysis (BH, which corresponds to the first stage of a temperature-phased anaerobic digestion), thermophilic anaerobic digestion, or pasteurization. Pasteurization is a well-known term in the field. It is generally understood as a process in which a liquid product is treated with gentle heat, usually at a temperature below 100°C, advantageously between 70°C and 75°C, to eliminate pathogens. Anaerobic digestion is a process involving microorganisms that break down carbonaceous material in the absence of oxygen. This process produces a digestate and a gaseous fraction comprising methane, and typically consists essentially of methane and CO2, also called biogas. Anaerobic digestion is generally carried out under pH conditions between 7.0 and 7.5, preferably between 7.0 and 7.2. Thermophilic anaerobic digestion is a well-known technique. It is an anaerobic digestion typically carried out at a temperature between 50°C and 60°C. Low-temperature thermal hydrolysis, abbreviated as "HT", is well known in the art. As used herein, it is understood as a process intended to improve digestion yields and dewatering capacity of carbonaceous material (typically biological or mixed sludge) by breaking down bacterial cell walls; the cell contents then become readily degradable anaerobically. A typical prior art TH process is shown in Figure 1. In this process, carbonaceous material, usually sludge, preferably with a dry solids (DS) content ranging from 12 to 22%, is heated to a temperature between 140 and 165°C, typically for 30 minutes. The hydrolyzed sludge is then cooled in a flash tank before being fed into digester D, where anaerobic digestion takes place. After hydrolysis, the sludge is typically diluted to approximately 10% dry matter content before being injected into the digester. Mixing is effective despite this high concentration because thermal hydrolysis decreases the sludge viscosity. The biogas produced is recovered in tank T. The following publications describe additional TH processes: • Barber, WPF “Thermal hydrolysis for sewage treatment: a critical review”. Water Research 104 (2016): 53-71. • Sandino, Julián, et al. “Thermal Hydrolysis and Incineration of Sludge: Evaluating Their Role in Optimizing Energy Profiles at Advanced BNR Facilities”. Proceedings of the Water Environment Federation 2018.18 (2018): 372-386. • González, A., et al. “Pre-treatments to enhance the biodegradability of waste activated ΜΑ / ÓUOOO sludge: elucidating the rate limiting step”. Biotechnology advances 36.5 (2018): 1434-1469. Biological hydrolysis (BH) is well known in the art. As used herein, it is the first stage of Temperature Phased Anaerobic Digestion (TPAD or 2PAD). Typically, BH is a thermophilic digestion stage, advantageously operated at a temperature between 50°C and 75°C (whereas the second stage of a TPAD / 2PAD is generally a mesophilic digestion operated at a temperature between 30-40°C, advantageously between 35°C and 38°C). Prior art TPAD / 2PADs that include a BH stage are described, for example, in ES2430739, DK3008193, and KR100588166B1. Descriptions of the latest generation TPAD / 2PAD processes can also be found in the following publications: • https: / / www.epa.gov / biosolids / examples-equivalent-processes-pfrp-and-psrp (búsqueda 2PAD) • Huyard, A., B. Ferran, and J-M. Audic. “The two phase anaerobic digestión process: sludge stabilization and pathogens reduction”. Water Science and Technology 42.9 (2000): 41-47. • Willis, John, and Perry Schafer. “Advances in thermophilic anaerobic digestión”. Proceedings of the Water Environment Federation 2006.7 (2006): 5378-5392. • Ge, Huoqing, Paul D. Jensen, and Damien J. Batstone. “Temperature phased anaerobic digestión increases apparent hydrolysis rate for waste activated sludge”. Water Research 45.4 (2011): 1597-1606. • Ge, Huoqing, Paul D. Jensen, and Damien J. Batstone. “Increased temperature in the thermophilic stage in temperature phased anaerobic digestión (TPAD) improves degradability of waste activated sludge”. Journal of Hazardous Materials 187.1-3 (2011): 355-361. • Ge, Huoqing, Paul D. Jensen, and Damien J. Batstone. “Pre-treatment mechanisms during thermophilic-mesophilic temperature phased anaerobic digestión of primary sludge”. Water research 44.1 (2010): 123-130. • Watts, S., G. Hamilton, and J. Keller. “Two-stage thermophilic-mesophilic anaerobic digestión of waste activated sludge from a biological nutrient removal plant”. Water science and technology 53.8 (2006): 149-157. • Akgul, D., M. A. Celia, and C. Eskicioglu. “Temperature phased anaerobic digestión of municipal sewage sludge: a Bardenpho treatment plant study”. Water Practice and Technology 11.3 (2016):569-573. As used herein, the “post-treatment” of stage 3) may comprise or be a mechanical and / or biological treatment. An example of “mechanical treatment” is a dewatering stage. As used herein, “biological treatment” is understood to mean thermophilic acidogenesis, aerobic digestion, anaerobic digestion, or fermentation. Fermentation is a well-known process in engineering and can be defined as an anaerobic biological process that extracts energy from carbohydrates in the absence of oxygen to produce small molecules (organic substrates), particularly red blood cells (RBCs), through the action of specific enzymes. CH4 is not produced, or only minimal amounts are. There are five main types of fermentation. MA / t / ZUZZ / UÓUOOO fermentation: • Alcoholic fermentation, producing mainly ethanol, • Lactic acid fermentation, producing lactate, • Propionic acid fermentation, producing propionate, • Butyric acid / butanol fermentation, producing butyrate and butanol, • Mixed acid fermentation, producing VFAs (mainly acetate, but also propionate, lactate, butyrate). The fermentation process can be controlled by the sludge retention time in the anaerobic tank, temperature and pH in the anaerobic tank, as well as by the specific microbial population involved in the fermentation process (i.e., by the choice of microbial strains in the anaerobic tank). In a preferred embodiment, the process further comprises a preheating step of the carbonaceous material with the steam recovered from step 2). In a preferred embodiment, the preheating of the carbonaceous material (such as raw sludge) entering the heat treatment stage 1) is carried out by direct contact of the recovered steam produced in the vacuum cooling stage 2) with the carbonaceous material. Alternatively, it can be carried out by direct injection of the recovered steam produced in the flash cooling stage (2) into the carbonaceous material (such as raw sludge). In another preferred embodiment, the steam recovered from stage 2) is brought into direct contact with the carbonaceous material (raw sludge) flowing upward from the heat treatment stage 1). Consequently, the carbonaceous material (raw sludge) is first directed to a heat recovery vessel where it comes into contact with the recovered steam produced in the vacuum cooling stage. The sludge then enters a reactor in a first unit where it undergoes either thermophilic biological treatment or mechanical treatment. In one particular embodiment, the process according to the invention comprises the steps of (1) Performing a first thermal treatment of sewage sludge or organic matter or any carbonaceous material, at a temperature T1 between 50 and 90°C, preferably between 50°C and 75°C, thereby producing heat-treated carbonaceous material, (2) Cooling said heat-treated carbonaceous material resulting downstream from step (1) to a temperature T2 (T2 lower than T1) of between 34-75°C in a cooling unit (flash chiller) operating under vacuum (typically operating from 0.055 to 0.170 bar (absolute pressure, i.e., 5,500 to 17,000 Pa), thereby producing cooled carbonaceous material, (3) Performing further treatment of said cooled carbonaceous material. The heat treatment of step (1) can be pasteurization, thermophilic biological treatment and / or low temperature thermal hydrolysis. The post-treatment of stage (3) can be any suitable treatment. This post-treatment can be mechanical, such as a dewatering process or temporary storage. It can also be anaerobic, such as fermentation or anaerobic digestion. Such anaerobic digestion can be either two-phase digestion or mesophilic digestion. MA / t / ZUZZ / UÓUOOO In one particular embodiment, the heat treatment of step (1) is pasteurization or low-temperature thermal hydrolysis, preferably pasteurization. In such case, the subsequent treatment advantageously comprises or is an anaerobic treatment, such as fermentation or anaerobic digestion. Such anaerobic digestion may be a two-phase digestion or a mesophilic digestion. Step (2) can be carried out in one stage or in several sub-stages. In other words, the vacuum cooling stage can comprise several cooling phases. In this variant, the invention process typically comprises: (1) Performing a first heat treatment of the carbonaceous material at a temperature Ti of between 50 and 90°C, preferably between 50°C and 75°C, to provide heat-treated carbonaceous material, (2) a) Cooling said resulting heat-treated carbonaceous material downstream from stage (1) to an intermediate temperature Tza (Tza lower than Ti) of between 50°C and 80°C in a cooling unit (flash chiller) operating under vacuum (typically operating from 0.15 to 0.48 bar (absolute pressure, i.e., 15,000 to 48,000 Pa), thereby producing intermediate-cooled carbonaceous material, (2) b) Cooling said intermediate-cooled carbonaceous material downstream from stage 2a) to a final temperature Tb (Tb lower than Tb) of between 34°C and 47°C in a cooling unit (flash chiller) operating under vacuum (typically operating from 0.15 to 0.48 bar (absolute pressure, i.e., 15,000 to 48,000 Pa) from 0.05 to 0.1 bar (absolute pressure), i.e., 5,000 to 10,000 Pa), and preferably 0.055 to 0.17 bar (absolute pressure), i.e. 5,500 to 17,000 Pa), thus producing cooled carbonaceous material, (3) Carry out further treatment of the cooled carbonaceous material. The cooling temperature T2a of stage (2a) is preferably around 50°C when stage (1) is performed at 55-60°C, around 65°C when stage (1) is performed at 70-75°C and around 80°C when stage (1) is performed at 85°C-90°C. In this variant, step (1) is preferably a pasteurization step. In such a case, the subsequent treatment is preferably an anaerobic treatment, such as fermentation or anaerobic digestion. Such anaerobic digestion may be a two-phase digestion or a mesophilic digestion. In one particular embodiment, the process according to the invention comprises the steps of (1) Performing a first thermophilic biological treatment of sewage sludge or organic matter or any carbonaceous material, at a temperature between 50 and 75°C, (2) Cooling the resulting downstream hydrolyzed sludge or organic matter or carbonaceous material from the first stage from 50-75°C to 35-42°C in a flash cooler operating under vacuum (typically operating from 0.05 to 0.1 bar (absolute pressure, i.e., 5,000 to 10,000 Pa), preferably 0.055 to 0.17 bar), thereby producing cooled sludge, (3) Performing further treatment of the cooled sludge. When the further treatment of the resulting cooled hydrolyzed carbonaceous material such as sludge (i.e., carbonaceous material produced in stage (2)) is a mesophilic digestion stage, it is MA / t / ZUZZ / UÓUOOD advantageously carried out in a second reactor at 35-42°C. The recovered steam produced in stage (2), at low pressure and low temperature, can be condensed in other unit operations. In a second aspect, the present invention relates to an installation for implementing said process and an instant cooling unit designed for the implementation of said process. The new facility is designed so that: • The viscosity of the carbonaceous material (especially sludge) does not influence the system design, • Sand sedimentation does not influence the system design, • The temperature of the raw carbonaceous material (especially sludge) does not influence the system design, • The pressure drop generated is negligible compared to a heat exchanger, • Maintenance is significantly reduced. The invention therefore relates to an installation comprising: or at least one heat treatment unit (1) for heat treating carbonaceous material at a temperature between 50-90°C, preferably 50-75°C, or at least one vacuum cooling unit (2) downstream from the heat treatment unit for cooling the carbonaceous material, and at least one after-treatment unit (3), downstream from the vacuum cooling unit (2), for the after-treatment of the cooled carbonaceous material. In one embodiment, an installation according to the invention comprises: • A first unit with one or multiple reactors where a thermal treatment such as thermophilic biological treatment of sludge / organic matter is carried out between 50-90°C, preferably 50-75°C. This unit can be segmented into multiple subunits in series or function as a tank. • A downstream vacuum cooling unit from the first heat treatment units, • A second or multiple units for downstream further treatment from the vacuum cooling unit. Therefore, the installation may include: • a heat treatment unit for heat treating carbonaceous material at a temperature between 50-90°C, preferably 50-75°C, having a first inlet h and a first outlet Oi, said heat treatment unit being configured to be fed at the first inlet h with carbonaceous material, and to produce heat-treated carbonaceous material recovered at the first outlet Oi, • a vacuum cooling unit having a first inlet I2 and a first outlet O2, and optionally a second outlet O2, said first inlet I2 being in fluid connection with the first outlet Oi of the heat treatment unit, said vacuum cooling unit being configured to be fed at the first inlet I2 with said heat-treated carbonaceous material, and to produce cooled carbonaceous material recovered at the first outlet O2, and optionally recovered vapor at the second outlet O2', • a post-treatment unit,which has a first inlet I3 and a first outlet O3, said first inlet h being in fluid connection with the first outlet O2 of the vacuum cooling unit, said post-treatment unit being configured to be fed at the first inlet h with said cooled carbonaceous material, and to produce subsequently treated recovered carbonaceous material at the first outlet O3. As used herein, a “heat treatment unit” means a unit suitable for carrying out heat treatment of carbonaceous material at a temperature between 50 and 90°C, preferably 50–75°C. The heat treatment unit may be a TH unit, a BH unit, a thermophilic anaerobic digester, or a pasteurization unit. As used herein, a “vacuum cooling unit” is understood to be a unit suitable for performing evaporation under vacuum, i.e., at a pressure lower than atmospheric pressure, typically operating at an absolute pressure ranging from 0.055 to 0.480 bar (i.e., 5,500 to 48,000 Pa), such as from 0.055 to 0.170 bar (i.e., 5,500 to 17,000 Pa), or from 0.15 to 0.48 bar (i.e., 15,000 to 48,000 Pa). As used herein, a “down-treatment unit” or “post-treatment unit” means a unit suitable for carrying out further biological or mechanical treatment. In a preferred embodiment, the down-treatment stage comprises further biological treatment, in particular a mesophilic digestion stage. Advantageously, the installation also includes a downstream heat recovery vessel from the vacuum cooling unit. In other words, the installation advantageously further comprises: • a heat recovery vessel, having a first inlet k, a first outlet O4, and a second outlet Ck, said first inlet k being in fluid connection with the second outlet O2' of the vacuum cooling unit, said heat recovery vessel being configured to be fed at the first inlet L with said recovered steam, said recovered steam then being contacted with carbonaceous material (or fresh organic matter) in the vessel, to produce preheated carbonaceous material recovered at the first outlet O4, and additional recovered steam recovered at the second outlet. Advantageously, said outlet O4 of said heat recovery vessel is in fluid connection with the inlet.Alternatively, said heat treatment unit comprises a second Ir inlet, and said O4 outlet of said heat recovery vessel is in fluid connection with the Ir inlet, said heat treatment unit being configured to be fed with said preheated carbonaceous material. Advantageously, the installation also comprises an upstream heat recovery vessel from the heat treatment unit to bring the carbonaceous material into contact with the recovered steam. MA / t / ZUZZ / UÓUOOD Advantageously, the installation further comprises a condenser having a first inlet iHex, a first outlet Oηθχ, and a second outlet Oηθχ' (not shown), said first inlet Ihbx being in fluid connection with the second outlet CU· of the heat recovery vessel, said condenser being configured to be fed at the first inlet Iηθχ with said recovered steam, and to produce recovered exhaust gas at the first outlet Oηθχ, and recovered condensate (generally process water) at the second outlet Onex'. Said condenser is preferably a direct or indirect heat exchanger. In one variant, the installation further comprises a second downstream heat recovery vessel from the first upstream heat recovery vessel of the heat treatment unit. In one particular embodiment, the first unit or heat treatment unit is a reactor suitable for thermophilic digestion. In this variant, the second unit or downstream treatment unit is preferably a reactor suitable for mesophilic digestion. In one particular embodiment, the vacuum cooling unit comprises two vacuum cooling units installed in series. In other words, the vacuum cooling unit is a two-stage vacuum cooling unit. In this embodiment, the carbonaceous material being treated is directed from the heat treatment unit to a first cooling unit. The carbonaceous material cooled from the first cooling unit is then further cooled in a second cooling unit and directed to the subsequent treatment unit. In this modality, the installation therefore includes: • a heat treatment unit for heat treating carbonaceous material at a temperature between 50-90°C, preferably 50-75°C, having a first inlet h and a first outlet Oi, said heat treatment unit being configured to be fed at the first inlet h with carbonaceous material, and to produce heat-treated carbonaceous material recovered at the first outlet Oi, • a first vacuum cooling unit having a first inlet ka and a first outlet Oa, and optionally a second outlet O2a, said first inlet ha being in fluid connection with the first outlet Oi of the heat treatment unit, said first vacuum cooling unit being configured to be fed at the first inlet ka with said heat-treated carbonaceous material, and to produce intermediate cooled carbonaceous material recovered at the first outlet O2a, and optionally recovered steam at the second outlet O2a,• a second vacuum cooling unit having a first inlet kb and a first outlet Ckb, and optionally a second outlet O2b·, said first inlet kb being in fluid connection with the first outlet O2a of the first vacuum cooling unit, said second vacuum cooling unit being configured to be fed at the first inlet kb with said intermediate cooled carbonaceous material and to produce recovered cooled carbonaceous material at the first outlet O2b, and optionally recovered vapor at the second outlet O2b·, and • a post-treatment unit, having a first inlet h and a first outlet O3, said first inlet lPt being in fluid connection with the first outlet O2b of the second vacuum cooling unit, said post-treatment unit being configured to be fed at the first inlet h with said cooled carbonaceous material,and to produce recovered carbonaceous material subsequently treated in the first O3 outlet., In this mode, the recovered steam produced in the first and second cooling units is condensed in one or more condensers. This condenser can be a direct or indirect Hex heat exchanger (more specifically, a Hex water / steam heat exchanger). A “heat exchanger” is known in the art as a system used to transfer heat between two or more fluids (at least one cold fluid and one hot fluid), which can be used in both cooling and heating processes. The fluids can be separated by a solid wall to prevent mixing (indirect heat exchanger) or they can be in direct contact (direct heat exchanger). In the invention, heat exchangers are used to cool recovered steam. The cold fluid is typically process water, while the hot fluid is steam. The steam produced in the second cooling unit can be recovered and directed to a second heat recovery vessel where the steam is in contact with the carbonaceous material (preferably fresh organic matter), thus producing a first preheated carbonaceous material, said first preheated carbonaceous material being then sent to the second heat recovery unit, where the first preheated carbonaceous material is in contact with the steam recovered from the first cooling unit. Advantageously, the steam produced in the first cooling unit is recovered and sent to a heat recovery vessel where the steam is in contact with carbonaceous material (preferably fresh organic matter). In one particular embodiment, an installation according to the invention comprises: • A first unit with one or more sub-units (reactor) where a thermal treatment such as thermophilic biological treatment of sludge / organic matter is carried out between 50-90°C, preferably 50-75°C. This unit can be segmented into multiple sub-units (reactors) in series or operated as a tank (reactor). • A downstream vacuum cooling unit from the first thermal unit, • A second unit in one or multiple sub-units for downstream post-treatment from the vacuum cooling unit. An installation according to the invention may also include: • A storage tank containing (fresh primary, mixed, or biological sludge / organic matter or any carbonaceous matter to be treated) is located upstream of the first reactor. Alternatively, the easily degradable organic matter (carbonaceous material) can be sent directly to the downstream treatment unit while the sludge is processed first in the first reactor. • A heat exchanger in both the first and second units (or only in the first heat treatment unit) to maintain the temperature of the carbonaceous material at the required set point. MA / ÓUOOO BRIEF DESCRIPTION OF THE FIGURES The present invention is illustrated in more detail in the following figures, where: Figure 1 illustrates an upstream hydrolysis pretreatment implemented in a state-of-the-art mesophilic wastewater sludge digester; Figure 2 illustrates the state-of-the-art temperature-stage anaerobic digestion (TPAD) process of wastewater sludge; Figure 3 illustrates an installation for carrying out a temperature-stage anaerobic digestion (TPAD) process of wastewater sludge according to the invention; Figure 4 represents an installation for implementing a wastewater sludge treatment process according to the invention; Figure 5 represents an installation for implementing a wastewater sludge treatment process according to one embodiment of the invention; Figure 6 represents an installation for implementing a wastewater sludge treatment process according to one embodiment of the invention; Figure 7 represents an installation for implementing a wastewater sludge treatment process according to one embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION According to the invention, the process is carried out in an installation comprising a first reactor 1 in which a thermal treatment is carried out to treat municipal sludge, organic matter or any carbonaceous material from a storage tank 1a. The hot organic matter is then cooled in a downstream vacuum cooling unit 2 from the thermal reactor 1 before entering a second reactor 3 in which the cooled organic matter can be treated by further treatment such as anaerobic digestion. In other words, the installation in Figure 3 comprises: or at least one heat treatment unit (1) for heat treating carbonaceous material at a temperature between 50-90°C, preferably 50-75°C, or at least one vacuum cooling unit (2) downstream from the heat treatment unit for cooling the carbonaceous material, and at least one after-treatment unit (3), downstream from the vacuum cooling unit (2), for the after-treatment of the cooled carbonaceous material. More specifically, the installation in Figure 3 comprises: • a heat treatment unit (1) for heat treating carbonaceous material at a temperature between 50-90°C, preferably 50-75°C, having a first inlet h and a first outlet O1, said heat treatment unit being configured to be fed at the first inlet h with carbonaceous material, and to produce a heat-treated carbonaceous material (TL2), recovered at the first outlet O1, • a vacuum cooling unit (2) having a first inlet b and a first outlet O2, and optionally a second outlet O2;said first inlet b being in fluid connection with the first outlet O1 of the heat treatment unit, said vacuum cooling unit (2) being configured to be fed at the first inlet b with said heat-treated carbonaceous material (TL2), and to produce cooled carbonaceous material (TL3) recovered at the first outlet O2, and optionally recovered steam (SL1) at the second outlet O2', • a post-treatment unit (3), having a first inlet I3 and a first outlet O3, said first inlet h being in fluid connection with the first outlet O2 of the vacuum cooling unit (2), said post-treatment unit (3) being configured to be fed at the first inlet h with said cooled carbonaceous material (TL3), and to produce subsequently treated recovered carbonaceous material at the first outlet O3.; In a preferred variant of the first embodiment, the steam produced in the cooling stage is preferably brought into contact via a streamline SL1 with the raw sludge in a reactor 4 located upstream of reactor 1 in the first unit (see Figure 3). This contact can be achieved using a direct-contact countercurrent tower or any other means that minimizes steam pressure drop while maintaining maximum contact between the raw sludge and the steam to maximize condensation. Alternatively, the steam produced from the vacuum cooling stage (2) in unit 2 can be returned (SL2) to reactor 1 for preheating (direct injection into reactor 1). The biogas produced in reactors 1 and 3 of the first and second units can be sent via biogas lines BL3 and BL4, respectively, to a biogas recovery unit 5, typically a CHP (Combined Heat and Power) unit. Heat can be recovered from biogas recovery unit 5 and sent to reactor 1 via heat line HL. As another alternative, a HEx heat exchanger can be used in the steam produced to heat the raw sludge (primary, mixed, or biological) (less preferred). If it is not economical to inject the full steam flow rate into reactor 1 of the first unit, or the collection tank 1a, or the heat exchanger, some of the steam can be condensed in a condenser while the remainder is sent to preheat the incoming sludge (see figure 4). The installation of Figure 4 also includes: • a heat recovery vessel (4), having a first inlet k, a first outlet O4, and a second outlet O4·, said first inlet I4 being in fluid connection with the second outlet O2· of the vacuum cooling unit (2), said heat recovery vessel (4) being configured to be fed at the first inlet k with said recovered steam (SL1), said recovered steam (SL1) then being contacted with carbonaceous material (or fresh organic matter) (TL1) in the vessel (4), to produce preheated carbonaceous material (TL1') recovered at the first outlet O4, and further recovered steam SL3 recovered at the second outlet CU·. Advantageously, said outlet O4 of said heat recovery vessel (4) is in fluid connection with the inlet h.Alternatively, said heat treatment unit (1) comprises a second inlet Ir, and said outlet O4 of said heat recovery vessel (4) is in fluid connection with the inlet Ir, said heat treatment unit (1) being configured to be fed with said preheated carbonaceous material (TL1 j. Advantageously, the installation in Figure 4 also comprises a Hex capacitor that has MA / t / ZUZZ / UÓUOOD a first inlet iHex, a first outlet Οηθχ, and a second outlet Οηθχ· (not shown), said first inlet Ιηθχ being in fluid connection with the second outlet 04' of the heat recovery vessel (4), said condenser Hex being configured to be fed at the first inlet ΙηΘχ with said recovered steam SL3, and to produce recovered exhaust gas at the first outlet Οηθχ, and recovered condensate (generally process water) at the second outlet Οηθχ·. Said condenser is preferably a direct or indirect heat exchanger. This reinjection of recovered steam at low pressure and temperature allows the carbonaceous material (depending on stage 1, it can be primary, mixed or biological sludge) to be heated from a temperature of 10 to 20°C to a temperature of 20 to 45°C (typically between 30°C and 40°C, for example, between 30°C and 35°C), leading to an overall energy saving in the process. The steam recovered from stage (2) is at a pressure between 0.055 and 0.480 bar (absolute pressure), i.e., 5,500 to 48,000 Pa. Thanks to a vacuum pump (i.e., a diaphragm vacuum pump) located downstream of the cooling unit (flash cooler), this recovered flash steam can be brought into contact with the carbonaceous material (which may be primary / mixed / biological sludge). Due to the low solids content of this sludge (between 3 and 25% by mass), specifically between 3 and 8% by mass), this contact is possible without any other intermediate device. As illustrated in Figure 4, in one variant of the modality, the process comprises the following stages: (1a) bringing the sewage sludge or organic matter or any carbonaceous material emitted from storage tank 1a into a heat recovery vessel 4 with the recovered steam SL1 from a downstream cooling stage (2) of reactor 1 of the first unit where thermal treatment is carried out or thermophilic biological treatment of sludge / organic matter / carbonaceous material is carried out between 50 and 90°C, preferably between 50°C and 75°C or mechanical treatment of sludge / organic matter (carbonaceous material); (1) subject the sludge / organic matter / carbonaceous material previously heated in the previous stage to a thermal treatment, for example, a thermophilic biological treatment between 50-90°C in reactor 1 of the first unit; (2) cooling the resulting downstream sludge or organic matter or carbonaceous material from the first unit from 50-90°C to 35-42°C in a vacuum cooling unit 2 operating under vacuum (vacuum pump VP) (typically operating from 0.05 to 0.1 bar (absolute pressure), i.e., 5000 to 10,000 Pa), preferably 0.055 to 0.17 bar, thereby producing cooled carbonaceous material; (3) perform further treatment of the cooled sludge / organic matter / carbonaceous material in reactor 3 of the second unit. The recovered steam (SL1) from the cooling unit 2 is sent to a heat recovery vessel 4. As a result, the recovered steam (SL1) is at least partially condensed in the vessel 4. The exhaust gas (SL2) is sent to a vacuum pump to be evacuated from the installation or treated later. This modality is illustrated in Figures 4 and 5. MA / t / ZUZZ / UÓUOOO If in the heat recovery vessel 4, the contact between the carbonaceous material (more specifically fresh sludge) and the recovered steam is direct, then a foam reduction stage, such as mechanical foam reduction like sludge recirculation in the vessel or chemical foam reduction like antifoam injection, can be performed. In another embodiment (not shown), a first part of the recovered steam SL1 is advantageously sent back to reactor 1 of the heat treatment unit to preheat the latter (direct injection into reactor 1) and a second part (SL2) is sent to the heat recovery vessel 4 to heat the fresh sludge (see figure 4). Figure 5 illustrates a vacuum cooling stage with a minimal number of subunits / elements. This type of installation can therefore have a minimal footprint with a minimal preheating stage. The cooling stage is performed in a single step, so the vapor temperature will be equal to the sludge temperature in the vacuum cooler, which is the lowest temperature achievable with this system. The carbonaceous material is directed in the TL1 treatment line to the heat recovery vessel 4 for contact with steam. The preheated carbonaceous material can then optionally be held in a storage tank 1b. The carbonaceous material is directed to reactor 1 of the first unit via the TL1 treatment line for thermal or mechanical treatment. Non-condensable products can be processed in further treatment stages, such as an odor treatment unit. The hot carbonaceous material is directed from reactor 1 of the first unit through TL2 to the vacuum cooling unit 2. The cooled material is then sent via TL3 to reactor 3 of the second unit, which may be an anaerobic digestion tank 3. The steam recovered from cooling unit 2 is directed via SL1 to the heat recovery unit vessel 4 to perform preheating of the raw carbonaceous material. Excess steam in vessel 4 can be directed via SL3 to a HEx condenser, and non-condensable products can be sent via a non-condensable line to a biogas recovery unit or further treatment stage. The HEx condenser can be a direct or indirect condenser, such as a contactor. In Figure 6, the illustrated installation proposes two-stage vacuum cooling units with maximum heat recovery in the case of limited refrigerant availability (such as process water). Therefore, the installation provides two cooling units, 2a and 2b, installed in series. The organic matter treated in the first reactor 1 is cooled in a first cooling unit 2a and then in a second cooling unit 2b. The steam produced in the second cooling unit 2b is recovered and sent (SL1b) to a heat recovery vessel 4b where the steam comes into contact with the fresh organic matter. The preheated organic matter is then sent via TL1' to a second heat recovery unit 4a where the first preheated organic matter comes into contact with the recovered steam (SL1a) from the ML / t / ZUZZ / UÓUOOD first cooling unit 2a. Therefore, the organic matter is first preheated by the cooler recovered steam and then by the hotter recovered steam. These two stages of preheating the organic matter allow for the improvement of the rheological properties of the organic matter since the organic matter is diluted and preheated before the second preheating stage. This eliminates the need for cooling water to condense the steam produced in the second vacuum cooling sub-stage, as the steam is condensed onto the organic matter. The condenser can be optional since all the steam can be consumed in the preheating stage, thus eliminating the need for both water and a condenser. In this example installation, the recovered steam (SL3a, SL3b) produced by the two vacuum cooling units can be condensed in the HEx condenser. The figures show two HEx condensers, but condensation can be performed in a single condenser. The HEx condenser can be either a direct or indirect condenser, such as a contactor. All non-condensable materials can then be treated in subsequent treatment stages, such as the odor treatment line, or released into the atmosphere or combined with the biogas produced in further treatment. The installation shown in Figure 6 comprises: • a heat treatment unit for heat treating carbonaceous material at a temperature between 50-90°C, preferably 50-75°C, having a first inlet h and a first outlet O1, said heat treatment unit being configured to be fed at the first inlet h with carbonaceous material, and to produce a heat-treated carbonaceous material (TL2), recovered at the first outlet O1, • a first vacuum cooling unit (2a) having a first inlet La and a first outlet O2a, and optionally a second outlet O2a, said first inlet La being in fluid connection with the first outlet Ott of the heat treatment unit, said first vacuum cooling unit (2a) being configured to be fed at the first inlet La with said heat-treated carbonaceous material (TL2), and to produce intermediate cooled carbonaceous material (TL2j) recovered at the first outlet O2a,and optionally recovered steam (SL1 a) at the second outlet O2a·, • a second vacuum cooling unit (2b) having a first inlet bb and a first outlet Ü2b, and optionally a second outlet O2b, said first inlet bb being in fluid connection with the first outlet Cha of the first vacuum cooling unit, said second vacuum cooling unit (2b) being configured to be fed at the first inlet bb with said intermediate cooled carbonaceous material (TL2j, and to produce recovered cooled carbonaceous material (TL3) at the first outlet O2b, and optionally recovered steam (SL3b) at the second outlet O2b·, and • a post-treatment unit (3), having a first inlet b and a first outlet Os, said first inlet b being in fluid connection with the first outlet Oab of the second vacuum cooling unit,said post-treatment unit (3) being configured to be fed at the first inlet b with said cooled carbonaceous material, and to produce subsequently treated recovered carbonaceous material at the first outlet O3., In this mode, the recovered steam produced in the first and second cooling units (SL3a and SL3b) is condensed in one or more condensers. This condenser can be a direct or indirect Hex heat exchanger (more specifically, a Hex water / steam heat exchanger). The steam produced in the second cooling unit (2b) can be recovered and directed to the heat recovery vessel (4b) where the steam is in contact with the carbonaceous material (preferably fresh organic matter), thus producing a first preheated carbonaceous material, said first preheated carbonaceous material being then sent to the second heat recovery unit (4a), where the first preheated carbonaceous material is in contact with the steam recovered (SL1a) from the first cooling unit (2a). Advantageously, the steam produced in the first cooling unit (2a) is recovered and sent to a heat recovery vessel (4) where the steam is in contact with the carbonaceous material (preferably fresh organic matter). The process allows for maximum energy recovery with a highly viscous flow of dry organic matter, highly concentrated in dry matter and / or an installation where the availability of cooling water is limited. In Figure 7, the illustrated installation provides a balance between optimizing heat recovery and minimizing the number of subunits / elements in the installation. This installation can be considered when cooling water is available and the organic matter stream is easy to preheat. Accordingly, the installation also provides two vacuum cooling units 2a, 2b installed in series, but the treated organic matter emitted from reactor 1 is cooled by the first cooling unit 2a and the recovered steam (SL1a) from this unit 2a is used in a heat recovery vessel 4 to preheat the organic matter before reactor 1. The cooled organic matter is then cooled a second time in cooling unit 2b before being directed TL3 to the second reactor 3 for further treatment. The excess steam produced in the first and second cooling units is condensed in SL3a and SL3b in a condenser such as a Hex water / steam heat exchanger, which can be either direct or indirect. The Hex condenser can be a direct or indirect condenser, such as a contactor. This setup provides an optimal balance between cost and energy gain, even if cooling water is required. Advantages of the Invention Cooling using a vacuum cooling system compared to a conventional heat exchanger that operates with process water has many beneficial effects: • Cooling efficiency depends not on the process water temperature but on the vacuum pressure, which is much easier to control. Cooling is almost instantaneous and does not require a significant HRT (Hydraulic Retention Time) as in a HEx. • Variation in mud viscosity is no longer a problem. MA / t / ZUZZ / U ÓUOOD • In the absence of a HEx, there is no need for maintenance on the sludge transfer pumps and pipes. The TPAD / 2PAD processes according to the invention can be implemented in large industrial facilities, where the problems of the size of the HEx would be unmanageable with the processes in the state of the art. When operating in batch configuration (2PAD), flash cooling allows for a significant reduction in the sludge removal sequence from the thermophilic reactor. Consequently, this increases batch time, reducing the size of the thermophilic reactor heated by the HEx and / or the feed pumps (feeding can occur over a longer period). The preheating of raw sludge based on the direct injection of steam from the exhaust gas produced by instantaneous vacuum pressure into the raw sludge has the following advantages over the conventional heat exchanger based on pretreatment in known TPAD / 2PAD. Heat recovery is independent of sludge viscosity. The exhaust gas generated by a vacuum cooling system can be problematic (odor problem due to the presence of H2S and NH3). This problem is generally solved by injecting this gas into the digester once it has condensed. Reusing this exhaust gas without condensing it to preheat the raw sludge allows it to be treated according to standard processes by means of the odor treatment unit in Plant 6. In this application, low-temperature steam reduces the amount of odors and contaminants (vaporized organic material) compared to conventional instantaneous systems. In the absence of a HEx, there is no need for maintenance on the sludge transfer pumps and pipes. In the field of anaerobic sludge digestion, vacuum cooling is generally associated with cooling high-temperature sludge (around 165°C), i.e., sludge treated with a THP or other heat treatments, to a temperature of around 100°C. The pressure following such a system instantaneous (in the sludge treatment field) remains higher than atmospheric pressure (delta P of the instantaneous system > atmospheric pressure). Secondary vacuum cooling can be used to cool sludge from a temperature between 100 and 110°C to a temperature of around 60°C. Such an instantaneous secondary cooling system could operate under vacuum. The final cooling stage, in order to cool the sludge to a temperature of 3738°C suitable for anaerobic digestion (mesophilic stage), is carried out by diluting the sludge with process water or by mixing it with raw primary sludge produced by primary sedimentation tanks. Using vacuum cooling to reduce the temperature of sludge below the 60°C threshold has never been described in the field of municipal sludge treatment. In state-of-the-art processes, the non-condensable gas generated during the flash cooling stages following steam cooling and condensation to 37°C-38°C is fed into the mesophilic reactor.

Claims

1. A process for treating carbonaceous material, such as sewage sludge or organic waste, characterized in that it comprises the steps of: (1) performing a thermal treatment of said carbonaceous material, thereby providing heat-treated carbonaceous material, (2) cooling said heat-treated carbonaceous material, thereby providing cooled carbonaceous material, and (3) performing further treatment of said cooled carbonaceous material, wherein the cooling of step 2) is carried out using a vacuum cooling step.

2. The process according to claim 1, further characterized in that it comprises a preheating step of the carbonaceous material 1a,4 before proceeding to the heat treatment step 1) (TL1), carried out by direct contact of vapor from the recovered vapor (SL1) produced by the vacuum cooling step 2) with the carbonaceous material.

3. The process according to claim 2, further characterized in that the carbonaceous material is first directed to a heat recovery vessel where said carbonaceous material is in contact with the recovered steam produced by the vacuum cooling stage.

4. The process according to any of claims 1 to 3, further characterized in that it comprises the steps of (1) performing a first heat treatment of carbonaceous material, at a temperature T1 between 50 and 90°C, preferably between 50°C and 75°C, thereby producing heat-treated carbonaceous material, (2) cooling said resulting heat-treated carbonaceous material, downstream from step (1) to a temperature T2 lower than T1 of between 34-75°C, in a cooling unit operating under vacuum, thereby producing cooled carbonaceous material, (3) performing a further treatment of said cooled carbonaceous material.

5. The process in accordance with any of claims 1 to 4, further characterized in that step 2) is carried out in one or more sub-steps.

6. The process according to claim 5, further characterized in that step 2 comprises: (2a) cooling the resulting heat-treated carbonaceous material downstream from step (1) to an intermediate temperature T2a lower than T1, between 50°C and 80°C in a cooling unit operating under vacuum (typically from 0.15 to 0.48 bar (absolute pressure, i.e. 15,000 to 48,000 Pa), thereby producing intermediate cooled carbonaceous material, (2b) cooling said intermediate cooled carbonaceous material downstream from step 2a) to a final temperature T2b lower than T2a, between 34°C and 47°C in a cooling unit operating under vacuum (typically from 0.05 to 0.1 bar (absolute pressure, i.e. 5,000 to 10,000 Pa), preferably from 0.055 to 0.17 bar (absolute pressure, i.e. 5,500 to 17,000 Pa), thus producing cooled carbonaceous material.

7. The process in accordance with any of claims 1 to 6, further characterized in that the heat treatment of step 1) is a pasteurization, a thermophilic biological treatment or a low-temperature thermal hydrolysis.

8. The process according to any of claims 1 to 7, further characterized in that the post-treatment step 3) is: - a mechanical treatment step such as a dewatering step, or a temporary storage step, or - an anaerobic treatment step, such as fermentation, anaerobic digestion such as two-phase digestion, or a mesophilic digestion step.

9. The process in accordance with any of claims 1 to 8, further characterized in that the carbonaceous material is organic waste and / or sludge, in particular municipal sludge.

10. An installation for implementing the process as claimed in claims 1 to 9, characterized in that it comprises: at least one heat treatment unit (1) for heat treating carbonaceous material at a temperature of between 50-90°C, preferably 50-75°C, at least one vacuum cooling unit (2) downstream from the heat treatment unit for cooling the carbonaceous material, and at least one post-treatment unit, downstream from the vacuum cooling unit (2), for the post-treatment of the cooled carbonaceous material.

11. The installation according to claim 10, further characterized in that it comprises an upstream heat recovery vessel (4, 4b) from the heat treatment unit to bring the carbonaceous material into contact with the recovered steam.

12. The installation according to claim 11, further characterized in that it comprises a second heat recovery vessel (4a) downstream from the first heat recovery vessel (4b) and upstream from the heat treatment unit.

13. The installation according to claim 11 or 12, further characterized in that the vacuum cooling unit comprises two vacuum cooling units (2a, 2b) installed in series, the carbonaceous material treated from the first unit (1) by a treatment line (TL1) being cooled in a first cooling unit (2a), then the cooled carbonaceous material being cooled a second time in the cooling unit (2b) and directed through a treatment line (TL3) to the second unit (3) for further treatment.

14. The installation according to claim 12, further characterized in that the recovered steam produced in the first and second cooling units (SL3a and SL3b) is condensed in one or more condensers.

15. The installation according to claim 11, further characterized in that the recovered steam produced in the second cooling unit (2b) can be recovered and directed to the heat recovery vessel (4b) where the steam is in contact with carbonaceous material (preferably fresh organic matter), thereby producing a first preheated carbonaceous material, said first preheated carbonaceous material being then sent to the second heat recovery unit (4a), where the first preheated carbonaceous material is in contact with the recovered steam (SL1a) from the first cooling unit (2a).

16. The installation according to claim 12, further characterized in that the recovered steam produced in the first cooling unit (2a) is recovered and sent to a heat recovery vessel (4) where the steam is in contact with carbonaceous material.

Images