Process for treating co-products from the production of synthetic fuels and production unit for its implementation

Abstract

Process for treating co-products from the production of synthetic fuels and production unit for its implementation. The invention relates to a process for treating co-products from the production of synthetic fuels, comprising the combination of at least three treatments, including an anaerobic biological treatment, an aerobic biological treatment to produce an aerobic mixed liquor, and an ozonation treatment of the aerobic mixed liquor. This process enables the production of biogas which can be converted into dihydrogen to supply a biofuel refinery. The invention also provides a production unit for implementing this process. Figure for the abstract: Fig. 1.

Description

Title of the invention: Process for treating co-products from the production of synthetic fuels and production unit for its implementation technical field

[0001] The present invention relates to the field of treatment of co-products generated by the production of synthetic fuels, whether upstream – at the stage of pretreatment of raw materials – or during the synthesis itself. The invention specifically aims at the treatment of co-products resulting from the pretreatment of raw materials intended for the biofuel industry.

[0002] The invention proposes a process for treating co-products as well as an installation for implementing this process, which make it possible to optimize the valorization of co-products and reduce the carbon footprint. Previous technique

[0003] The production of synthetic fuels relies on chemical reactions generating multiple co-products, essentially organic, throughout the production line.

[0004] These co-products include, in particular, wastewater—resulting from the washing of intermediate products and the cleaning of equipment—which contains a high concentration of solids and hydrophobic substances, as well as solid residues from the purification of reagents (i.e., raw materials) and reaction by-products. The purification of reagents and the pretreatment of raw materials are essential for this industry, which uses numerous reaction catalysts that are sensitive to impurities.

[0005] In the second- and third-generation biofuel industry, the raw materials used are solid, liquid, or semi-solid fats and oils at room temperature (known as FOGs, for Fat, Oil, and Grease) that contain undesirable compounds which must be removed by pretreatment processes. These pretreatments of crude lipid materials consist of processing unrefined vegetable or animal oils (natural or recycled) to isolate a fraction containing refined lipids of interest intended for conversion into biofuel, for example, fatty acid triglycerides and fatty acids in the case of renewable diesel. Crude vegetable and animal oils and fats are generally subjected to several chemical pretreatment steps to remove undesirable compounds that could reduce biofuel production yield.The choice of pretreatment reagents, the number of steps and the order of the . Processing steps vary depending on the nature of the raw material. Furthermore, by-products are sometimes generated in large quantities and are extremely varied in nature – mineral, organic, solid, liquid, or pasty. In addition, the organic matter content of these by-products can be very high, making their management complex and costly for potential transformation into valuable products.

[0006] This is why, for example, only wastewater from the pretreatment of raw materials is currently treated in biorefineries. The wastewater is simply subjected to physical separation treatments such as flotation or activated carbon fixation, which lead to pollution transfer. The solid co-products are generally treated by incineration, which is very energy-intensive and increases the carbon footprint of the biofuel.

[0007] The need therefore remains to treat the co-products generated by the synthetic fuels industry, particularly co-products from the refining of raw organic materials, using a process with a limited or even zero carbon footprint. Regardless of this aspect, it would be desirable to optimize the energy efficiency of a processing unit for these co-products.

[0008] Such a treatment process would make it possible to reduce the overall carbon footprint of producing a synthetic fuel.

[0009] It would be particularly advantageous to treat concentrated, or even highly concentrated, co-products without consuming excessive energy. Optimizing the valorization of co-products by increasing the proportion of biogas produced, while simultaneously reducing the quantities of biological sludge, is also a goal.

[0010] The need to improve the management of co-products generated by the pretreatment of raw materials, in particular lipid raw materials used for the production of biodiesel and renewable diesel, also remains.

[0011] The invention aims in particular to remedy one or more of the drawbacks related to the refining of raw materials for the biofuel industry of the prior art mentioned above. Description of the invention

[0012] This objective is achieved by proposing a process for treating co-products from the production of synthetic fuels, comprising the combination of at least three treatments, including an anaerobic biological treatment, an aerobic biological treatment to produce an aerobic mixed liquor, and an ozonation treatment of the aerobic mixed liquor.

[0013] The invention also provides an installation enabling the implementation of this process, for example a co-product treatment unit and a biorefinery.

[0014] In a first embodiment, the concentrated residues and wastewater feed an anaerobic digester which produces, in addition to biogas, an effluent whose liquid part feeds an aerobic digester and undergoes ozonation.

[0015] In a second embodiment, a fatty fraction is extracted from the wastewater, so that the anaerobic treatment is carried out on the fatty fraction of the wastewater and not on the wastewater itself. In this version, the concentrated residues undergo aerobic treatment and ozonation independently of the wastewater.

[0016] The proposed method and installation of the invention for the treatment of co-products advantageously makes it possible to reduce the carbon footprint of a synthetic fuel production unit, in particular by one of the following five means or by a combination of several of them.

[0017] First, the reduction of the carbon footprint can be achieved through an energy-autonomous process.

[0018] The invention also has the advantage of producing exclusively biogenic carbon dioxide.

[0019] In a particular embodiment, the process includes a treatment for transforming biogenic methane into dihydrogen, preferably accompanied by a treatment for converting biomethane into green dihydrogen to power a renewable diesel production unit. This valorization of biogas thus reduces the proportion of blue dihydrogen used for the hydrotreating of the processed raw materials. The process of the invention makes it possible to supply green energy up to a value of 4.3 MWh per ton of chemical oxygen demand (COD). A co-product treatment plant according to the invention, fed with 10 t / day of lipid raw materials (quantified by their COD), can produce 16 GWh / year of green energy, while a co-product treatment plant according to the invention, fed with 50 t / day of lipid raw materials (quantified by their COD), can produce 80 GWh / year of green energy.

[0020] The invention also makes it possible to reduce the quantity of biological sludge resulting from the treatment of co-products, which is of particular interest for co-products with a high carbon content.

[0021] Finally, the invention limits, or even eliminates, the pollution transfers associated with the use of activated carbon or an ion exchanger as practiced in the prior art. Brief description of the drawings

[0022] Figure 1 is a diagram representing a first embodiment of the invention. The anaerobic digestion of all the liquid and solid co-products is followed by aerobic treatment of the digested effluent.

[0023] Fig. 2 represents a second embodiment of the invention, in which the solid co-products and wastewater are treated separately, allowing external treatment of the solid co-products in an anaerobic digestion plant combined with an aerobic digestion plant such as an MBBR reactor.

[0024] Fig. 3 is a diagram of a synthetic fuel production unit according to the invention comprising a co-product treatment subunit, a dihydrogen production subunit from biogas and a hydrotreatment section. Description of the implementation methods

[0025] A first object of the invention relates to a process for treating co-products from the production of a synthetic fuel, the co-products comprising concentrated residues and / or wastewater, said process comprising: - a biological treatment in an anaerobic reactor to produce biogas, - a biological treatment in an aerobic reactor of a treated liquid to produce a mixed liquor and treated waters, - the treatment of the mixed liquor by ozonation.

[0026] A synthetic fuel, within the meaning of the invention, is a paraffinic fuel whose production process includes at least one step of chemical transformation of the raw material used, as opposed to fossil fuels which are derived from petroleum by refining.

[0027] The invention relates particularly to a synthetic fuel chosen from biofuels and synthetic fuels.

[0028] The term "biofuel" refers to a fuel produced from biomass, a carbon source: this is the case for biodiesel and renewable diesel produced from natural organic oils and fats. "Synthetic fuels," such as synthetic naphtha or synthetic diesel, include the category of electrofuels produced from renewable or decarbonized electricity.

[0029] The synthetic fuel referred to in the present invention is for example chosen from hydrotreated vegetable oils such as biodiesel, biopropane, bionaphtha, biokerosene, renewable diesel including fatty acid methyl esters, synthetic diesel and synthetic naphtha.

[0030] The invention relates to the management of co-products formed in the synthetic fuels industry, and a "co-product" for the purposes of the invention is understood to be a chemical compound or a mixture of chemical compounds resulting from one of the production stages of a synthetic fuel, which can be recovered. These stages include the purification (also called pretreatment) of raw materials, and the transformation of raw materials into biofuel (including the synthesis and purification of the finished product).

[0031] The physical state of the co-product can be liquid, pasty, or solid, regardless of the stage at which it is formed in the fuel synthesis chain. In one particular embodiment, the co-product comprises a mineral or organic fat.

[0032] For example, the process of the invention relates to a co-product resulting from the pretreatment of raw materials, these raw materials being essentially lipid-based in the case of biofuels manufactured from vegetable oils or animal fats. The present invention therefore relates in particular to co-products formed during the implementation of a pretreatment process for the raw material(s) necessary for the manufacture of a biofuel.

[0033] In a particular embodiment of the invention, the co-products are obtained from the pretreatment of raw materials intended for the production of a synthetic fuel chosen from among biofuels.

[0034] The co-products may include wastewater, concentrated residue, or a mixture thereof. In one embodiment, the co-products include concentrated residue and wastewater, which feed the anaerobic reactor at the inlet.

[0035] The term "wastewater" means wastewater discharged during a synthetic fuel production process, in particular water discharged during the pretreatment of a raw material comprising lipid compounds (including oils, fats and / or waxes) or during a synthetic fuel synthesis process from a raw material.

[0036] The term “concentrated residues” means solid or pasty, organic or inorganic co-products.

[0037] The process of the invention offers improved management of concentrated solid inorganic residues (such as mineral waxes or colouring earths) and solid organic residues such as gums.

[0038] In a particular embodiment, the process is applied to the treatment of co-products formed during the pretreatment of raw materials used for the production of a biofuel.

[0039] Both biodiesel and renewable diesel synthesis processes use catalysts, which have the disadvantage of being deactivated upon contact with secondary compounds present in the raw lipid feedstock. Furthermore, the raw materials contain compounds that are not converted into biofuel. Therefore, it is necessary to pretreat the fats to limit impurity levels and ensure a good biofuel production yield.

[0040] Pretreatment depends on the nature of the raw material used and employs various physical and chemical techniques, including neutralization with caustic soda, degumming under acidic conditions to remove phospholipids, bleaching with colored earths to remove phospholipids and oxidized compounds, absorption, neutralizing steam distillation (also called deacidification) to remove free fatty acids and volatile compounds, drying, washing, and filtration to remove solids, including waxes. Some pretreatment steps aim to limit or eliminate the levels of undesirable products present in the raw material. Some pretreatment steps themselves generate contaminants that add to the impurities in the raw material and that must be removed in further steps.

[0041] For example, raw materials intended for a renewable diesel manufacturing unit can successively undergo degumming (by action of citric acid or phosphoric acid), neutralization (with a base), washing with water, then decolorization by acid treatment and adsorption on bleaching earths and activated carbon.

[0042] Co-products generated during the production of synthetic fuels, such as co-products generated during the pretreatment of raw materials intended for the manufacture of biofuels, have highly varied chemical compositions and physical states, which makes their management all the more difficult to implement. In the case of a renewable diesel feedstock, the waste produced by the pretreatment of the raw materials consists of wash water (liquid), acid gums (organic and pasty), or used bleaching earth (SBE), which is solid.

[0043] The process of the invention can also be applied to the treatment of co-products formed during the synthesis of a biofuel or a synthetic fuel.

[0044] According to a first embodiment of the process of the invention, co-products comprising concentrated residues (pasty or solid) and wastewater undergo sequential anaerobic and aerobic treatment. The concentrated residues and wastewater are initially placed in the same anaerobic reactor to produce a first effluent, which is then subjected to anaerobic biological treatment. This treatment generates, in addition to biogas, a second effluent. Treatment of the second effluent by separation produces an anaerobic treatment sludge and a treated liquid, the latter being intended for aerobic and ozonation treatment. The anaerobic treatment sludge is then disposed of.

[0045] Thus, the first embodiment of the invention provides for a biological treatment in the anaerobic reactor which produces, in addition to biogas, a first effluent, and the process includes a treatment by separation of the first effluent, producing biological sludge and the treated liquid.

[0046] In a second embodiment, the co-products comprise wastewater and solid residues that are treated separately. The wastewater is degreased and degreased, for example in a separation tank, to separate the water from the oils and produce a grease fraction and a treated liquid. Anaerobic treatment is applied only to the grease fraction of the wastewater. Anaerobic treatment and ozonation treatment are carried out on concentrated residues.

[0047] In the second embodiment of the invention, the co-products comprise wastewater, which undergoes a degreasing treatment to produce a grease fraction and the treated liquid. The grease fraction of the wastewater can advantageously undergo biological treatment in an anaerobic reactor. Finally, when the co-products comprise, in addition to wastewater, concentrated residues, the latter also undergo biological treatment in an anaerobic reactor.

[0048] According to a particularly advantageous embodiment of the invention, the co-products are characterized by a high, or even very high, total chemical oxygen demand (COD). Thus, the total COD of the co-products of the invention preferably includes a high biodegradable COD (correlated with a high BOD5), possibly accompanied by a hard (or refractory) COD.

[0049] The process of the invention makes it possible, in particular, to treat co-products with a chemical oxygen demand (COD) between 10 g / L and 600 g / L, and also to treat both solid residues and wastewater. The COD will be measured according to ISO 6060:1989, in accordance with the practice of those skilled in the art.

[0050] Wastewater, for example, has a chemical oxygen demand (COD) of between 10 g / L and 50 g / L, and concentrated, pasty residues can have a COD of between 100 g / L and 200 g / L: this is particularly the case for acid gums resulting from the pretreatment of raw materials used for the production of HVO (Hydrotreated Vegetable Oil) biofuels. The COD of concentrated solid residues that can be efficiently managed by the process of the invention can reach a value of between 300 and 500 g / L. Such solid residues are, for example, used bleaching earths resulting from the purification of raw materials for HVO biofuels.

[0051] Measurements of chemical oxygen demand can be carried out using sensors at any point in the installation, mainly at the inlet on the co-products, or in the material flows within the installation, in order to optimize the efficiency of the process and to adapt the parameters of the different devices, in particular the load of the digesters and the intensity of the ozonation.

[0052] The process of the invention makes it possible to generate treated water with a chemical oxygen demand of less than 0.1 g / L. The quantity of biological sludge is advantageously minimized compared to prior art processes.

[0053] Ozonation treatment of the mixed liquor can be carried out using devices known to those skilled in the art. In this description, the term "mixed liquor" refers to a mixture of an aqueous liquid to be purified and aerobic microorganisms suspended in the liquid that purify it. Ozonation, combined with aerobic biological treatment, is particularly useful for treating concentrated, or even highly concentrated, by-products, as it increases the biodegradation of refractory materials.

[0054] The process of the invention is therefore advantageous for the management of co-products with a chemical oxygen demand greater than 10 g / L, preferably greater than 20 g / L. In a particular embodiment, the process of the invention is especially suited to the management of co-products with a chemical oxygen demand greater than 150 g / L, or even greater than 170 g / L.

[0055] According to a particular embodiment, ozone is injected into a circuit carrying the mixed liquor. The ozone can be injected using an injector or a static mixer. For example, ozonation is carried out on the mixed liquor extracted from the bioreactor, notably in a recirculation loop. The device used for ozonation includes an ozonation tower through which the mixed liquor circulates. Alternatively, the ozone produced by an ozonator is injected directly into a circuit carrying the mixed liquor.

[0056] A person skilled in the art will know how to adjust the amount of ozone required to the composition of the mixed liquor. The recycling of the mixed liquor is preferably configured so as to optimize the consumption of co-products by biomass.

[0057] Aerobic treatment can be carried out in an activated sludge reactor, a fixed-bed reactor, or a moving-bed reactor. A moving-bed biological film reactor (MBBR) is preferred, as it has a smaller relative volume or a higher relative treatment capacity due to the suspension of microorganisms and their higher biomass concentration.

[0058] Anaerobic treatment can be carried out in an anaerobic reactor comprising a three-phase separator. The three-phase separator includes a degassing tank to release the gas, a separation chamber to separate the liquid from the sludge, and a solids recovery tank. This separator advantageously optimizes the operation of the fixed-bed digester, particularly for the treatment of streams with a chemical oxygen demand exceeding 300 g / L.

[0059] The process of the invention may include a treatment for separating the mixed liquor and biogas generated by the anaerobic treatment. The temperature value will be chosen by a person skilled in the art to optimize biogas production. For example, the treatment may include a mesophilic digestion stage, at around 35°C, a thermophilic digestion stage between 50°C and 60°C, or a combination of the two stages.

[0060] The biogas produced by the anaerobic treatment comprises biomethane and carbon dioxide, so the process may also include biogas treatment to separate biogenic methane and biogenic carbon dioxide. The resulting biomethane can be used in several ways, for example by compression (to supply the city gas network), by conversion to dihydrogen, or by combustion (to heat the aerobic and anaerobic reactors or to heat a thermal dryer for drying the biological sludge if necessary). The biomethane can also be used to drive alternators that generate electricity, which powers various treatment equipment. In a particular embodiment of the invention, the process includes a treatment to transform biomethane (also called biogenic methane) into dihydrogen.

[0061] As stated above, the co-products treated according to the invention are generated during the production of a synthetic fuel. In a particular embodiment, the synthetic fuel is a biofuel, the term "biofuel" referring to a fuel produced from biomass.

[0062] Biofuels are classified into three generations based on the origin of the biomass used and the associated transformation processes. A first-generation biofuel is an agrofuel produced from crops traditionally used for food. These biofuels are derived from plant matter, such as sugar beets or cereals for bioethanol production, or rapeseed and sunflowers for biodiesel production. In second-generation biofuels, the plant biomass is non-food, making it possible to produce renewable diesel. This includes wood, straw, agricultural and forestry residues, or dedicated crops (lignocellulosic biomass), notably allowing for the production of renewable diesel. Finally, third-generation biomass is of marine origin and uses algae that produce lipids.

[0063] Diesel biofuels include various products, manufactured from oils derived from oil-bearing plants, animal fats or used oils.

[0064] Fatty acid methyl esters (FAME) are obtained by a transesterification reaction of triglyceride molecules, which constitute the majority of vegetable oils extracted from plant seeds, with methanol. One of these fatty acid methyl esters, biodiesel (blended with fossil diesel and supplied at service stations as B7 or B10 diesel), is produced from vegetable oils extracted from oilseed plants such as rapeseed, corn, sunflower, palm and soy.

[0065] Another biofuel diesel, renewable diesel (supplied at the pump under the name XTL diesel) is produced by hydrotreating and hydrocracking vegetable oils or animal fats, generally from animal fat residues such as tallow, used cooking vegetable oils, industrial waste such as effluents discharged from mills where palm fruits are crushed to obtain oil (Palm Oil Mill Effluent or POME), and black liquor from the manufacture of kraft paper (PPO paper).

[0066] Other biofuels such as biopropane, bionaphtha and sustainable aviation fuels (SAFs) such as bio-kerosene are produced using the same process.

[0067] Biofuels obtained by hydrotreating used vegetable oils are designated as hydrotreated vegetable oils or HVO biofuels (Hydrotreated Vegetable Oil). Hydrotreating consists of removing the oxygen atoms contained in the starting biomass to obtain alkanes (also called paraffins). This treatment, carried out at very high temperatures in the presence of a catalyst, consumes gaseous dihydrogen and releases carbon dioxide and water. Hydrotreating is followed by hydrocracking, by which the alkanes undergo a change in the configuration of their carbon and hydrogen atoms (isomerization).

[0068] The process of the invention also relates to the treatment of co-products generated during the production of synthetic fuels by Fisher-Tropsch synthesis (FTS). These fuels are obtained by converting a mixture of carbon monoxide and dihydrogen (called syngas or synthetic gas) in the presence of a catalyst, to obtain a product of interest (short-chain-length liquid hydrocarbons corresponding to diesel and gasoline fractions) and co-products (solid hydrocarbons). This category of synthetic fuels includes electrofuels (e-fuels) produced from renewable electricity (from solar or wind power, for example) or decarbonized electricity. E-diesel, e-gasoline, and e-kerosene are examples.

[0069] In [Fig. 1], wastewater co-products and solid residues—in particular, co-products from the pretreatment of raw materials during the production of HVO biofuels or fatty acid methyl esters (FAME)—undergo biological treatment in an anaerobic reactor (1). At least 90% of the organic matter (corresponding to 90% of the chemical oxygen demand) entering the anaerobic digester is converted into biogas, a mixture of biogenic CH4 and CO2. The treated effluent leaving the anaerobic digester undergoes a separation treatment (3) to separate the biological sludge from the separated water. The separation can be carried out in a decanter, in a flotation tank or through membranes.

[0070] A separate sludge, still too heavily laden with biomass to be discharged directly into the environment, can undergo further treatment steps. The separated biological sludge is then removed from the site for disposal.

[0071] The biogas produced by the digester comprises approximately 50% to 80% by volume of biomethane, the remainder being mostly carbon dioxide. The biogas preferably undergoes a separation treatment (2) to separate the biomethane and the carbon dioxide.

[0072] The separated water from the anaerobic digester undergoes biological treatment in an aerobic reactor (4) to degrade residual organic matter (biodegradable COD) and refractory organic matter (refractory COD or Hard COD). The biodegradability of the refractory organic matter is increased by ozonation treatment (5) of the mixed liquor extracted from the aerobic bioreactor, the ozonation being carried out, for example, in a mixed liquor recirculation loop. The solids contained in the treated water exiting the aerobic bioreactor are separated from the main stream by flotation, clarification, filtration, or membranes. The sludge produced during the separation stage can be recycled with the sludge from the anaerobic digester to be simultaneously dewatered and then disposed of off-site.The treated water from the biological treatment in the aerobic reactor can be discharged either to existing facilities or directly into the environment, depending on the discharge permit.

[0073] In the diagram of [Fig. 2], the concentrated residues are treated separately from the wastewater. The concentrated residues can be transported to an off-site anaerobic digestion plant for biological treatment in an anaerobic reactor (1) for degradation and conversion into biogas. The biogas undergoes a separation treatment (2) of biogenic methane and carbon dioxide.

[0074] Untreated wastewater can contain up to 10% fats, greases, and oils (FOG). The FOG is degraded by biological treatment in an on-site aerobic reactor (4). However, since the wastewater is incompatible with the downstream biological treatment step, the stream passes through a flotation unit to undergo grease removal treatment (6) and remove the FOG from the main stream. The separated concentrated FOG can then be sent to an off-site digestion facility for biological treatment in an anaerobic reactor (1), resulting in the production of biogenic CO2 and CH4.

[0075] The biodegradability of refractory organic materials can be increased by ozonation treatment (5) of the mixed liquor extracted from the aerobic bioreactor. The solids contained in the water treated by the aerobic reactor are separated from the main stream by flotation, clarification, filtration, or membrane filtration. The sludge The wastewater produced by the separation treatment (3) is dewatered and removed from the site. The treated water from the aerobic treatment can be discharged either to existing facilities or directly into the environment, depending on discharge standards or regulations.

[0076] The invention offers a particularly advantageous solution for reducing the carbon footprint of biofuel production units, including HVO and FAME biofuels, which generate both liquid and solid co-products of varying concentrations. The invention makes it possible to manage all co-products simultaneously or separately, thereby limiting the amount of sludge and producing biomethane, which can be directly used in several industries, including the HVO biofuel sector. The process of the invention offers essentially two implementation methods. The first solution is based on the anaerobic digestion of all co-products generated by the refining of lipid raw materials, followed by aerobic treatment of the digested effluents.When solid residues cannot be treated on site at the pretreatment unit, the invention proposes an alternative solution consisting of an external treatment of these residues by anaerobic treatment, with the aqueous co-products undergoing separate aerobic treatment.

[0077] The process of the invention can be implemented in a co-product treatment plant, said plant being located at the biofuel production site or at another site. The plant comprises an anaerobic reactor, an aerobic reactor, and an ozonation means for bringing ozone into contact with the mixed liquor produced by the aerobic treatment.

[0078] A second object of the invention relates to a synthetic fuel production unit having a co-product treatment subunit comprising an aerobic reactor, an ozone production means, an anaerobic reactor producing biogas, and a biogas treatment means to extract biogenic methane.

[0079] The production unit may include a subunit for transforming biogenic methane into green dihydrogen, intended to supply a section for hydrotreating and hydroisomerizing raw materials.

[0080] In a particular embodiment, the production unit is a biorefinery in which the biomethane produced by the anaerobic treatment is converted into dihydrogen in a steam reforming unit, which dihydrogen is used to transform the raw materials into alkanes (hydrotreating), and to transform these alkanes into biofuels (hydroisomerization).

[0081] The production unit of the invention is configured to implement the process described above in the first design of the invention. Consequently, the features described above in relation to the first object of the invention, as well as any combination thereof, may be repeated to describe the production unit which is the subject of the second object of the invention, so that they are not repeated in this part.

[0082] The production unit illustrated in [Fig.3] includes a co-product treatment subunit (8) equipped with an aerobic reactor, an ozone production means, an anaerobic reactor producing biogas, and a biogas treatment means for extracting biogenic methane.

[0083] This subunit can advantageously be installed at the site of a biorefinery producing HVO biofuels from lipid feedstocks such as FOGs. The site includes a feedstock hydrotreating and hydroisomerization section (9) for processing the FOGs, and a processing subunit (10) producing dihydrogen from methane, also called the reforming section. In this installation, the biogenic methane produced by the co-product processing subunit (8) can advantageously replace, totally or partially, fossil methane to feed the reforming section, and thus produce green dihydrogen, dihydrogen being essential for the operation of the biorefinery to carry out the hydrotreating and hydroisomerization of the FOGs.In a particular embodiment, the biorefinery may also include a raw material pretreatment unit to generate refined raw materials and raw material co-products on site. The co-products are advantageously treated in the co-product treatment subunit (8) while the refined raw materials are used to feed the raw material hydrotreating and hydroisomerization section (9).

[0084] The term "includes / comprising" does not exclude the presence of other elements or steps. Furthermore, although listed individually, a plurality of means, elements, or process steps may be implemented in a single unit or device.

[0085] . Reference symbols in the claims are provided simply as examples and should in no way be interpreted as limiting the scope of the claims.

[0086] Although the present invention has been described above with reference to specific embodiments, it is not intended to be limited to the specific form shown here. Furthermore, although features are presented individually, they can advantageously be combined.

Claims

Claims

1. A method for treating co-products from the production of a synthetic fuel, the co-products being chosen from concentrated residues, waste water and their mixtures, said method comprising: - a biological treatment in an anaerobic reactor (1) to produce a biogas, - a biological treatment in an aerobic reactor (4) of a treated liquid to produce a mixed liquor and treated water, and - treatment by ozonation (5) of the mixed liquor.

2. Method according to claim 1, characterized in that the co-products comprise concentrated residues and waste water, which feed the anaerobic reactor as input.

3. Method according to claim 2, characterized in that the biological treatment in the anaerobic reactor (1) produces, in addition to the biogas, a first effluent, and in that the method comprises a separation treatment (3) of the first effluent, producing biological sludge and the treated liquid.

4. A method according to claim 1, characterized in that the co-products comprise waste water, which undergoes a degreasing treatment (6) to produce a fatty fraction and the treated liquid.

5. Method according to claim 4, characterized in that the fatty fraction of the waste water undergoes biological treatment in the anaerobic reactor (1).

6. Method according to claim 4 or 5, characterized in that the co-products comprise, in addition to waste water, concentrated residues which undergo biological treatment in the anaerobic reactor (1).

7. Method according to one of the preceding claims, characterized in that it comprises a treatment of the biogas (2) to separate the biogenic methane and the biogenic carbon dioxide.

8. Method according to one of the preceding claims, characterized in that the co-products resulting from the production of a synthetic fuel are derived from the pretreatment of the raw materials used for the production of the synthetic fuel, which is chosen from biofuels.

9. Method according to one of the preceding claims, characterized in that the anaerobic reactor comprises a three-phase separator.

10. Method according to claim 7, characterized in that the method comprises a treatment for transforming biogenic methane into di-hydrogen.

11. Method according to one of the preceding claims, characterized in that the synthetic fuel is chosen from hydrotreated vegetable oils such as biodiesel, biopropane, bionaphtha, biokerosene, renewable diesel, synthetic diesel and synthetic naphtha.

12. A synthetic fuel production unit (7) having a co-product processing sub-unit (8) comprising an aerobic reactor, an ozone production means, an anaerobic reactor producing biogas, and a biogas processing means for extracting biogenic methane.

13. Production unit according to claim 12, characterized in that it comprises a sub-unit for transforming biogenic methane into green dihydrogen (10), which feeds the raw material hydrotreatment and hydroisomerization section (9).

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