Organic compounds removal from wastewater by extraction

Abstract

A problem arises when purifying a triglyceridic and / or free fatty acid feedstock for renewable hydrocarbon production, where such feedstock comprises C2-C6 aliphatic oxygenates, as they are transferred to the aqueous wastewater during the course of the purification, and which contributes to the degree of pollution of the aqueous wastewater measured as the chemical oxygen demand. The aqueous wastewater is extracted with the purified feedstock for renewable hydrocarbon production, which reduces the chemical oxygen demand of the aqueous wastewater by extracting the C2-C6 aliphatic oxygenates therefrom, while maintaining the purified feedstock for renewable hydrocarbon production in a quality that can be directly processed in a hydrotreating step, where the extracted C2-C6 aliphatic oxygenates are also converted to valuable hydrocarbons.

Description

[0001] P-23039 / P466618PC00

[0002] 1 / 44

[0003] Organic Compounds Removal from Wastewater by Extraction

[0004] Technical Field

[0005] The present invention relates to processes for purifying a feedstock for renewable hydrocarbon production.

[0006] Background Art

[0007] Palm oil mill effluent (POME) is a byproduct generated during the processing of palm oil. It contains a mixture of organic compounds, including short-chain carboxylic acids, which contribute to high chemical oxygen demand (COD) in wastewaters generated in processing / purifying POME. The chemical oxygen demand is a measure of the amount of oxygen required to oxidize the organic and oxidizable inorganic matter in wastewater.

[0008] In the context of utilizing POME as a feedstock for renewable energy under the Renewable Energy Directive II (RED II) annex IX A, the high COD content in the wastewaters from processing POME poses a challenge. The presence of short-chain carboxylic acids in POME can lead to increased COD levels in wastewaters, indicating a higher demand for oxygen during the wastewater treatment process.

[0009] To comply with RED II annex IX A, which outlines sustainability criteria for bioenergy feedstocks, it's crucial to address the environmental impact of POME utilization. High COD levels in wastewaters from POME processing imply that effective wastewater treatment is necessary to minimize the environmental footprint of POME conversion processes.

[0010] Efficient treatment methods, such as anaerobic digestion or other advanced biological treatment processes, can be employed to reduce the COD in the wastewaters from POME processing / purification. These methods help break down P-23039 / P466618PC00

[0011] 2 / 44 organic compounds, including short-chain acids, and generate biogas as a byproduct. However, they also take up much space.

[0012] Accordingly, while POME and other renewable materials such as oils and fats are potential feedstocks for renewable energy, the high COD content in the wastewaters coming from purifying the feedstock originating particularly from short-chain carboxylic acids, requires careful consideration and effective wastewater treatment to meet the sustainability criteria outlined in RED II annex IX A. Implementation of efficient treatment processes is essential to minimize the environmental impact and make POME utilization a sustainable and compliant option for renewable energy production.

[0013] Consequently, there is a need for processes that can convert renewable material, in particular waste-based renewable material including residues and by-products to hydrocarbon fuels, and at the same time efficiently treat wastewater. Examples of such renewable materials include palm oil mill effluent (POME), soapstock acid oil (SAO), brown grease (BG), animal fat (AF), used cooking oil (UCO), tall oil, as well as algae oil (AO), oils from regenerative agriculture, and their mixtures.

[0014] Summary of the Invention

[0015] The present invention was made in view of the prior art described above, and the object of the present invention is to provide processes that integrate, in particular, waste-based biofuel production comprising feedstock purification and hydrotreatment and at the same time reduce the COD in the wastewater produced from such processes. In other words, to reduce the COD in the challenging wastewaters to a level that can be treated further by e.g. biological processes which further reduce the COD.

[0016] To solve the problem, the present invention provides a process for purifying a feedstock for renewable hydrocarbon production comprising the following steps:

[0017] (a) providing a feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, and including impurities in the form of metal P-23039 / P466618PC00

[0018] 3 / 44 impurities and phosphorus impurities, as well as up to 4 wt% water, and optionally solid matter, where the feedstock includes at least 0.01 wt% C2-C6 aliphatic oxygenates;

[0019] (b) purifying the feedstock for renewable hydrocarbon production in one or more purification steps whereby metal impurities and phosphorus impurities are reduced, and where an aqueous wastewater phase comprising C2-C6 aliphatic oxygenates is separated, thereby forming a purified feedstock for renewable hydrocarbon production having less metal impurities measured in w-ppm and phosphorus impurities measured in w-ppm than the feedstock for renewable hydrocarbon production, preferably where the one or more purification steps are selected so as to reduce the total amount of aqueous wastewater phase recovered to at least 0.5 wt% and at most 5 wt%, where wt% of the total amount of aqueous wastewater phase recovered is calculated based on the feedstock for renewable hydrocarbon production;

[0020] (c) optionally providing an extraction agent by mixing at least part of or all of the purified feedstock for renewable hydrocarbon production from step (b) with a further feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, having less than 10 w-ppm metals, less than 10 w-ppm phosphorus, and in some cases having less than 0.3 wt% water, where the w-ppm and wt% is calculated based on the further feedstock for renewable hydrocarbon production;

[0021] (d) extracting part of the C2-C6 aliphatic oxygenates from the aqueous wastewater phase with a feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, having less than 10 w-ppm metals, less than 10 w-ppm phosphorus, where the w-ppm is calculated based on the further feedstock for renewable hydrocarbon production; and / or with the extraction agent provided in step (c), thereby providing an aqueous wastewater phase depleted of C2-C6 aliphatic oxygenates, and a feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates;

[0022] (e) optionally mixing at least part of or all of the feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates with part of or the remaining part of the purified feedstock for renewable hydrocarbon production;

[0023] (f) providing the feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates obtained in step (d) or the feedstock obtained in step (e) P-23039 / P466618PC00

[0024] 4 / 44 to one or more catalytic hydrotreating steps, whereby at least deoxygenation is effected in the presence of hydrogen at elevated temperatures, such as 200-450°C and at elevated pressures, such as 10-150 bar to form hydrocarbons; where the metal and phosphorus impurities are measured as elemental metal and phosphorus impurities.

[0025] That is, the inventors of the present invention in a first aspect of the invention found that certain (waste-based) feedstocks for hydrocarbon production can be purified using the process of the invention leaving a lower COD wastewater and at the same time providing a higher hydrocarbon yield given the recovery of aliphatic oxygenates from produced wastewater.

[0026] Taking palm oil mill effluent (POME) as an example of the feedstock in step (a) of claim 1. The POME may be purified by usual methods in the art leaving a purified POME low in water as well as metal and phosphorus impurities, and ready to be fed to a hydrotreating process. This leaves a POME wastewater high in organic impurities that consume oxygen during the decomposition of organic matter in the POME wastewater, i.e. have observable chemical oxygen demand (COD). Herein these organic impurities are referred to as COD impurities and include C2-C6 aliphatic oxygenates such as short-chain carboxylic acids.

[0027] The inventors have surprisingly found that the COD of the wastewater can be reduced by extraction of the wastewater with a (purified) feedstock for renewable hydrocarbon production that comprises free fatty acids and / or triglycerides, having less than 10 w-ppm metals, and less than 10 w-ppm phosphorus, including the purified POME, and at the same time, metal and phosphorus impurities and water are not transferred to any significant degree to the purified feedstock for renewable hydrocarbon production, such as the purified POME, which remain in a purified state that can be used directly in a hydrotreating process without further purification.

[0028] The removal of COD impurities from the wastewater including C2-C6 aliphatic oxygenates such as short-chain carboxylic acids work in synergy with the subsequent hydrotreatment(s) in step (f), where the extracted aliphatic oxygenates P-23039 / P466618PC00

[0029] 5 / 44 are converted to hydrocarbons together with the purified feedstock for renewable hydrocarbon production, such as the POME thereby increasing the hydrocarbon yield of the process together with providing a wastewater that has a lower amount of organic impurities measured as the COD.

[0030] The feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides referred to in step (a) may have one or more of:

[0031] - an oxygen content in the range of 3.0-20 wt%;

[0032] - a water content of less than 4 wt%;

[0033] - a total acid number in the range of 5-200 mg KOH / g;

[0034] - less than 70 wt% of an oil fraction with a boiling point of less than 350 °C;

[0035] - the sum of C2-C6 carboxylic acids in the range of 100-20000 mg / kg;

[0036] - a free fatty acid content of 10-90 wt%.

[0037] The feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides referred to in step (a) may be selected from one or more from the list consisting of: palm oil mill effluent (POME), used cooking oil, animal fat, yellow grease, brown grease, soapstock acid oil or tall oil, algae oil (AO), and oils from regenerative agriculture. Preferably the feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides referred to in step (a) comprises palm oil mill effluent (POME).

[0038] The one or more purification steps may be selected from one or more of:

[0039] - drying, for example at elevated temperature and / or at reduced pressure;

[0040] - filter-aid filtration, for example filtering in the presence of 0.1-1 wt% filter aid;

[0041] - settling, for example in a settling tank;

[0042] - water washing, for example in a tank or in a counter current column;

[0043] - heat treatment, for example heating to at least 150 °C , such as 150-400 °C, preferably of at least 200 °C, such as 200-350 °C, more preferably of at least 220 °C, such as 220-350 °C, more preferably 220-280°C for a sufficient period of time, such as 0.5-300 min, preferably 30-60 min;

[0044] - degumming, for example adding 1000-5000 w-ppm phosphoric, citric or sulfuric acid, water until a total of 1-5 wt%, heating to 60-90°C, and separating the gums; P-23039 / P466618PC00

[0045] 6 / 44

[0046] - alkali refining, for example treating the oil with alkali to remove free fatty acids as soap, followed by addition of adsorbent and filtration;

[0047] - bleaching, for example adding 100-5000 w-ppm citric acid, optionally adding 0.1 -1 wt% water, adding 0.2-2 wt% adsorbent, mixing, drying and filtering;

[0048] - deodorisation, for example at 220-260 °C under 1 -200 mbar; such as filter-aid filtration followed by heat treatment followed by bleaching.

[0049] The extraction may be performed as a liquid-liquid extraction above the melting point of the feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, having less than 10 w-ppm metals, less than 10 w-ppm phosphorus or the extraction agent of step (c), and below the boiling point of water.

[0050] The extraction may be performed as a counter-current liquid-liquid extraction.

[0051] The extraction may be performed as a liquid-liquid extraction where the oil-to-water ratio is from 0.2:1 .0 to 20.0:1 .0, such as from 0.4:1 .0 to 10.0:1 .0, such as 0.4:1 .0 to 4.0:1.0.

[0052] The extraction may be performed in one or more mixer-settler type extractor(s) and / or as a counter-current liquid-liquid extraction in one or more column extractors, such as one or more reciprocating plate column extractor(s).

[0053] The extraction may be performed as a counter-current liquid-liquid extraction, where the number of extraction stages is at least 2, such as at least 4, 6, 8 or 10.

[0054] The extraction may be performed as a liquid-liquid extraction, and whereby in step (c) the extraction agent fulfils one or more of the following:

[0055] - the combined feed in step (c) having a free fatty acid amount at least 10% higher than the purified feedstock for renewable hydrocarbon before mixing;

[0056] - the combined feed in step (c) having a free fatty acid content of 10-90 wt%.

[0057] For example, in step (c) the further feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, having less than 10 w-ppm metals, P-23039 / P466618PC00

[0058] 7 / 44 less than 10 w-ppm phosphorus may contain more than 50 wt% of free fatty acids, such as C and / or Cw free fatty acids, and / or in step (c) the further feedstock for renewable hydrocarbon production comprises C and / or Cw fatty acids and is selected from one or more of: palm oil mill effluent (POME), used cooking oil, animal fat, yellow grease, brown grease, soapstock acid oil, or tall oil, algae oil (AO), and oils from regenerative agriculture.

[0059] The aqueous wastewater phase comprising C2-C6 aliphatic oxygenates referred to in step (b) may have one or more of:

[0060] - a COD value of 1000 mg O / l or more, such as 20000 mg O / l or more;

[0061] - the sum of C2-C6 carboxylic acids in the range of 1000-20000 mg / kg.

[0062] The extraction in step (d) may be performed as a liquid-liquid extraction at a temperature range of 20-280°C.

[0063] The extraction in step (d) may be performed as a liquid-liquid extraction at a temperature range of 50-95 °C, such as 55-85 °C.

[0064] Brief Description of the Drawings

[0065] Figure 1 provides an example of the present process for purifying a feedstock for renewable hydrocarbon productions comprising providing a feedstock for renewable hydrocarbon production as defined herein.

[0066] Figure 2 shows simulations carried out with an Aspen Plus steady-state process simulation model. P-23039 / P466618PC00

[0067] 8 / 44

[0068] Detailed Description of the Invention

[0069] In describing the embodiments of the invention specific terminology will be resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.

[0070] The present invention relates to a process for purifying a feedstock for renewable hydrocarbon production comprising the following steps:

[0071] (a) providing a feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, and including impurities in the form of metal impurities and phosphorus impurities, as well as up to 4 wt% water, and optionally solid matter, where the feedstock includes at least 0.01 wt% C2-C6 aliphatic oxygenates;

[0072] (b) purifying the feedstock for renewable hydrocarbon production in one or more purification steps whereby metal impurities and phosphorus impurities are reduced, and where an aqueous wastewater phase comprising C2-C6 aliphatic oxygenates is separated, thereby forming a purified feedstock for renewable hydrocarbon production, and having less metal impurities measured in w-ppm and phosphorus impurities measured in w-ppm than the feedstock for renewable hydrocarbon production. For example, the one or more purification steps may be selected so as to reduce the total amount of aqueous wastewater phase recovered to at least 0.5 wt% and at most 5 wt%, where wt% of the total amount of aqueous wastewater phase recovered is calculated based on the feedstock for renewable hydrocarbon production;

[0073] (c) optionally providing an extraction agent by mixing at least part of or all of the purified feedstock for renewable hydrocarbon production from step (b) with a further feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, having less than 10 w-ppm metals, less than 10 w-ppm phosphorus;

[0074] (d) extracting part of the C2-C6 aliphatic oxygenates from the aqueous wastewater phase with a feedstock for renewable hydrocarbon production comprising free fatty P-23039 / P466618PC00

[0075] 9 / 44 acids and / or triglycerides, having less than 10 w-ppm metals, less than 10 w-ppm phosphorus, where the w-ppm is calculated based on the feedstock for renewable hydrocarbon production or with the extraction agent provided in step (c), thereby providing an aqueous wastewater phase depleted of C2-C6 aliphatic oxygenates, and a feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates.

[0076] (e) optionally mixing at least part of or all of the feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates with part of or the remaining part of the purified feedstock for renewable hydrocarbon production;

[0077] (f) providing the feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates obtained in step (d) or the feedstock obtained in step (e) to one or more catalytic hydrotreating steps, whereby at least deoxygenation is effected in the presence of hydrogen at elevated temperatures, such as 200-450°C and at elevated pressures, such as 10-150 bar to form hydrocarbons.

[0078] The inventors of the present invention in a first aspect of the invention found that the wastewater generated in the purification of certain (waste-based) feedstocks for hydrocarbon production can be purified using the process of the invention leaving a lower COD wastewater and at the same time providing a higher hydrocarbon yield in the overall process.

[0079] Exemplified using palm oil mill effluent (POME) as the feedstock in step (a) of claim 1. The POME may be purified by usual methods in the art leaving a purified POME low in water as well as metal and phosphorus impurities, and ready to be fed to a hydrotreating step. This leaves a POME wastewater high in organic impurities resulting in a high wastewater COD. These organic impurities include C2-C6 aliphatic oxygenates such as short-chain carboxylic acids.

[0080] The inventors have surprisingly found that the COD of the wastewater can be reduced by extraction of the wastewater with an extraction agent comprising triglycerides, free fatty acids and mixtures thereof. For example the purified POME may be used for this purpose. At the same time, metal and phosphorus impurities and water are not transferred to any significant degree to the extraction agent, such P-23039 / P466618PC00

[0081] 10 / 44 as e.g. purified POME, which remain in a purified state that can be used directly in a hydrotreating process without further purification. The COD of the wastewater can also be reduced by extraction of the wastewater with triglycerides, free fatty acids and mixtures thereof, including mixtures with the purified POME.

[0082] The removal of COD impurities including C2-C6 aliphatic oxygenates such as short-chain carboxylic acids work in synergy with the subsequent hydrotreatment(s) in step (f), where the extracted aliphatic oxygenates are converted to hydrocarbons together with the POME thereby increasing the hydrocarbon yield of the process together with providing a wastewater that has a lower amount of impurities measured as the COD using ISO 15705M-2002 M.

[0083] Step (a) - The feedstock for renewable hydrocarbon production

[0084] The present invention relates to a process for purifying a feedstock for renewable hydrocarbon production comprising the following steps:

[0085] In step (a) a feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides is provided.

[0086] Triglycerides and fatty acids are present in large amounts in plant oils and animal fats. The majority of these plant oils and animal fats are composed of 25 wt%, 40 wt%, 60 wt%, or 80 w% or more of fatty acids (for example 80-95 wt%), either as free fatty acids or as esters of fatty acids. Examples of esters of fatty acids are fatty acid glyceride esters (mono-, di- and / or tri-glyceridic) or for example the fatty acid methyl esters (FAME) or fatty acid ethyl esters (FAEE). Accordingly, the feedstock for renewable hydrocarbon production may contain 60 wt% or more of free fatty acids and / or fatty acid esters. For example, many of the suitable plant oils and / or animal fats comprise 70 wt% or more of free fatty acids and esters of fatty acids, such as triglycerides and typically even as high as around 90-95 wt%). The feedstock may also be a blend of two or more types of plant oils and / or animal fats. P-23039 / P466618PC00

[0087] 11 / 44

[0088] Examples of plant oils and animal fats include: rapeseed oil, canola oil, colza oil, babassu oil, carinata oil, coconut butter, muscat butter oil, sesame oil, maize oil, poppy seed oil, cottonseed oil, soy oil, laurel seed oil, jatropha oil, pongamia oil, safflower oil, palm kernel oil, camelina oil, makauba oil, makauba kernel oil, tall oil, fraction of tall oil, crude tall oil, tall oil pitch, sunflower oil, com oil, techn ical / disti Ilers com oil, soybean oil, hemp seed oil, olive oil, linseed oil, cottonseed oil, mustard oil, mustard seed oil, peanut oil, castor oil, coconut oil, palm oil, crude palm oil, palm seed oil, palm fatty acid distillate, a sludge originating from plant oil production, palm oil mill effluent, arachis oil, castor oil, coconut oil, archaeal oil, bacterial oil, fungal oil, protozoal oil, algal oil, seaweed oil, oils from halophiles, poultry fat, dry rendered poultry fat, brown grease, used cooking oil, suet, lard, tallow, blubber, recycled alimentary fats, acid oil, train oil, spent bleaching earth oil, microbial oil, or any combinations or mixtures thereof.

[0089] Plant oils and / or animal fats encompass both the virgin oils, as well as waste oils. One of the differences between virgin oils, such as rapeseed oil, and waste oils such as used cooking oil is the free fatty acid (FFA) content. FFA is created from oil degradation during storage and usage, e.g. by oxidation and hydrolysis.

[0090] Waste oils include a variety of low-value materials, such as used cooking oils, animal fats (such as beef tallow, poultry fat, waste lard, fish oil), tall oil, yellow grease, brown grease, as well as sludge oil or soap oils from the vegetable oil-refining process.

[0091] One example of a sludge oil is palm oil mill effluent (POME), which is also called sludge palm oil. The production of palm oil generates an aqueous palm oil mill effluent, which contains residual oil from the milling process, which residual oil can be recovered, and is called POME herein. It has a relatively high FFA level of above 15 wt% FFA, such as from 15-85 wt% FFA, and also includes impurities in the form of metal impurities, for example from 10-4000 w-ppm, and phosphorus impurities, for example from 5-150 w-ppm (w-ppm metals and phosphorus is measured as the elemental metals and phosphorus), as well as water, e.g. up to 4 wt% water, and may also contain at least 0.01 wt% solid matter, e.g. from 0.1 -2.0 wt% solid matter. Additionally, POME contains at least 0.01 wt% C2-C6 aliphatic oxygenates, from e.g. P-23039 / P466618PC00

[0092] 12 / 44 fermentation and anaerobic degradation, for example at least 0.05 wt%. 0.01 wt% C2-C6 aliphatic oxygenates corresponds to 100 w-ppm. This amount will usually be concentrated in the wastewaters from the purification to a much higher amount. The feedstock will usually not contain more than 4 wt% C2-C6 aliphatic oxygenates. Accordingly, the feedstock will therefore usually contain C2-C6 aliphatic oxygenates in the range of 0.01 to 4.0 wt%, for example 0.05-4.0 wt% C2-C6 aliphatic oxygenates.

[0093] Soapstock oil is produced in amounts of about 5 wt%, when crude virgin vegetable oils such as crude palm oil is refined to remove i.a. free fatty acids. Accordingly, soapstock oil has a relatively high FFA level.

[0094] Waste oils are usually characterized by relatively high free fatty acid (FFA) content due to deterioration of the triglycerides during e.g. cooking. Waste oils also typically have a water content that is usually desirable to reduce before feeding the oil to a hydrotreating reactor. Waste oils also often include impurities in the form of metal impurities and phosphorus impurities and potentially contain a variety of solid materials, which entered the oil as foreign material during usage or storage. For example, waste oils may include impurities in the form of 10-4000 w-ppm metal impurities and 5-1200 w-ppm, such as 5-150 w-ppm phosphorus impurities (both measured as elemental metals and phosphorus) and may contain more than 0.01 wt% solid materials, e.g. from 0.1 -2.0 wt%, which entered the oil as foreign material during usage or storage. Solid materials should also preferably be removed, typically by filtration prior to further processing.

[0095] Waste cooking oil may, for example, be drained into the sewer system in e.g. domestic households, where it can be recovered as yellow and brown grease.

[0096] Yellow grease has lower free fatty acids levels compared to the more decomposed brown grease. As a rule of thumb, yellow grease is said to have FFA levels between 5-15 wt%, whereas brown grease has FFA levels above 15 wt%. Some times brown grease will also be considered to have FFA levels of 35 wt% or higher. Trap greases are usually considered as a brown grease. It is collected from grease traps from P-23039 / P466618PC00

[0097] 13 / 44 restaurants, food processing plants or even wastewater treatment plants. It usually has high FFA levels of 40 wt% and higher caused by, among other things, hydrolysis by water and oxidation.

[0098] The process of the invention can advantageously be used to process lower quality oils containing free fatty acids, and therefore the feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides may comprise at least 10 wt% free fatty acids.

[0099] For example, the feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides referred to in step (a) may be selected from one or more from the list consisting of: palm oil mill effluent (POME), used cooking oil, animal fat, yellow grease, brown grease, soapstock acid oil, tall oil, algae oil (AO), and oils from regenerative agriculture.

[0100] The feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides may also include impurities in the form of metal impurities and phosphorus impurities, as well as up to 4 wt% water, and optionally solid matter.

[0101] Typical metal impurities include Si, Na, K, Ca and Mg. The metal impurities are usually measured in w-ppm (corresponding to mg / kg) of the metal measured as the elemental metal, which can be done using a variety of techniques, including ICP-MS. Too high metal and phosphorus impurity levels are not desirable during hydrotreatment, and the level is sought to be reduced to avoid catalyst bed plugging and catalyst deactivation. It is not uncommon that the feedstock for renewable hydrocarbon production contains more than 300 w-ppm (mg / kg) metal impurities measured as the sum of the elemental Si, Na, K, Ca and Mg for example from 300- 4000 w-ppm. Phosphorus impurities include the phospholipids that are present in vegetable oil and not uncommonly in the range of 100-1200 w-ppm P measured as elemental phosphorus. Accordingly, the metal and phosphorus impurities are measured as elemental metal and phosphorus impurities. P-23039 / P466618PC00

[0102] 14 / 44

[0103] The feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides may also include C2-C6 aliphatic oxygenates. These aliphatic oxygenates may be present as impurities in many waste oils, from e.g. fermentation, anaerobic degradation and other degradation processes. C2-C6 aliphatic oxygenates include short-chain carboxylic acids, such as C2-C6 carboxylic acids. For example acetic acid (C2), propionic acid (C3), butanoic acid (C4), pentanoic acid (C5) and hexanoic acid (Ce) as well as their isomers. Other aliphatic oxygenates include phenols, alcohols and esters, for example C2-C6 aliphatic oxygenates include glycerol and C2-C6 alcohols. During purification these oxygenates usually end up in an aqueous wastewater phase, and contribute to the pollution thereof, as measured using the chemical oxygen demand (COD).

[0104] The feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides referred to in step (a) may have one or more of:

[0105] - an oxygen content in the range of 3.0-20 wt%;

[0106] - a water content of less than 4 wt%;

[0107] - a total acid number in the range of 5-200 mg KOH / g;

[0108] - less than 70 wt% of an oil fraction with a boiling point of less than 350 °C;

[0109] - the sum of C2-C6 carboxylic acids in the range of 100-20000 mg / kg;

[0110] - a free fatty acid content of 10-90 wt%, such as 10-60 wt% for example 10-30 wt%; the wt% calculated based on the feedstock for renewable hydrocarbon production.

[0111] For example, the feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides referred to in step (a) may have less than 70 wt% of an oil fraction with a boiling point of less than 350 °C and a free fatty acid content of 10-30 wt%, the wt% calculated based on the feedstock for renewable hydrocarbon production.

[0112] When the feedstock for renewable hydrocarbon production in addition to free fatty acids and / or triglycerides also contain metal impurities and phosphorus impurities, as well as significant amounts of water, optionally solid matter and C2-C6 aliphatic oxygenates, then it is necessary to purify the feedstock for renewable hydrocarbon P-23039 / P466618PC00

[0113] 15 / 44 production to avoid problems downstream, in particular in the hydrotreating reactor, where the catalyst lifetime is influenced by the presence of too high impurity levels.

[0114] Step (b) - Purification

[0115] Accordingly, the process according to the present invention also includes a step (b) of purifying the feedstock for renewable hydrocarbon production in one or more purification steps whereby metal impurities and phosphorus impurities are reduced, and where an aqueous wastewater phase comprising C2-C6 aliphatic oxygenates is separated, thereby forming a purified feedstock for renewable hydrocarbon production having less metal impurities measured in w-ppm (for example less than 10 wppm metal impurities) and phosphorus impurities (for example less than 10 wppm phosphorus impurities) measured in w-ppm than the feedstock for renewable hydrocarbon production.

[0116] The purification of the feedstock for renewable hydrocarbon production takes place in one or more purification steps.

[0117] There are a number of purification processes known in the art for purifying the feedstock for renewable hydrocarbon production, and they include prepurifying processes such as drying, filter-aid filtration, settling, and water washing as well as pretreatment processes such as heat treatment, degumming, alkali refining, bleaching and deodorization. Accordingly, one or more purification steps include one or more of heat treatment, degumming, alkali refining, bleaching, and deodorization.

[0118] The objective of water washing is to decrease COD by pre-washing major part of organic compounds from the feedstock for renewable hydrocarbon production with water. This may be accomplished at refining site or elsewhere, such as at terminals, aggregation centres, or at separate preprocessing hubs. Water washing reduces i.a. the COD load, the phosphorous amount and the metal amount of the feedstock for renewable hydrocarbon production, which can then be optionally further pretreated as discussed herein. P-23039 / P466618PC00

[0119] 16 / 44

[0120] The objective of degumming is to remove the phospholipids and other impurities from the feedstock for renewable hydrocarbon production. This is usually performed by heating the oil with water, which hydrates the phospholipids and allowing them to be separated from the oil by e.g. centrifugation or other mechanical separation methods. This reduces i.a. the phosphorus amount of the feedstock for renewable hydrocarbon production. Degumming may also be performed in the presence of an acid, such as phosphoric acid or citric acid.

[0121] The objective of heat treatment is to convert soluble phosphorus and metal impurities into an insoluble form that can be then more easily removed from the feedstock for renewable hydrocarbon production. Heat treatment may be done by heating the feedstock to at least 150 °C, such as 150-400 °C, preferably to at least 200 °C, such as 200-350 °C, more preferably to at least 220 °C, such as 220-350 °C, more preferably 220-280°C for a sufficient period of time, such as 0.5-300 min, preferably 30-60 min. Heat treatment is often followed by a solids removal step to remove the impurities such as filtration or bleaching.

[0122] The objective of alkali refining is to remove free fatty acids (FFA) from the feedstock for renewable hydrocarbon production. It is usually not desired to remove the FFAs because the presence of FFAs have certain advantages in the process of the present invention, i.a. FFAs are useful in the hydrotreating process, where they are converted to hydrocarbons. Alkali refining is usually performed by mixing the oil with an alkali solution (usually sodium hydroxide or sodium carbonate). This reaction forms soap, which is then separated from the oil. This purification step removes free fatty acids and other acidic impurities from the oil.

[0123] The objective of bleaching is to remove pigments, residual phospholipids and metal impurities, as well as other impurities from the feedstock for renewable hydrocarbon production. This is usually performed by treating the oil with bleaching earth, such as activated clay, and then heating this mixture. The bleaching earth adsorbs the impurities, and the mixture is then dried and filtered to remove the impurities P-23039 / P466618PC00

[0124] 17 / 44 together with the bleaching earth. Bleaching may also be performed in the presence of added water and acid, e.g. citric acid.

[0125] The objective of deodorization is to remove any volatile compounds, including free fatty acids, from the feedstock for renewable hydrocarbon production. It is usually not desired to remove these volatile compounds because they can typically be converted in the hydrotreating process to hydrocarbons, thereby increasing the yield of the hydrotreating process. This is usually performed by heating the oil under vacuum to remove volatile components, and steam can also be added.

[0126] When solid matter is present, the one or more purification steps may include a filtration step, for example in the presence of filter aid, to remove any solid matter. This may then be followed by a degumming step, or a heat treatment step, followed by a bleaching step. In addition to filtration, solid matter may also be removed by settling, decanting and / or centrifugation, or methods including any of these four processes.

[0127] If any solid matter has already been removed, then the one or more purification steps may include a degumming step, or a heat treatment step, followed by a bleaching step. Additionally, the one or more purification steps may include drying / evaporation or be preceded or followed by a drying step. This can be done at any suitable conditions that evaporate water.

[0128] The one or more purification steps may be selected from one or more of:

[0129] - drying, for example at elevated temperature and / or at reduced pressure;

[0130] - filter-aid filtration, for example filtering in the presence of 0.1-1 wt% filter aid;

[0131] - settling, for example in a settling tank;

[0132] - water washing, for example in a tank or in a counter current column;

[0133] - heat treatment, for example heating to at least 150 °C, such as 150-400 °C, preferably at least 200 °C, such as 200-350 °C, more preferably at least 220 °C, such as 220-350 °C, more preferably 220-280°C for a sufficient period of time, such as 0.5-300 min, preferably 30-60 min with mixing; P-23039 / P466618PC00

[0134] 18 / 44

[0135] - degumming, for example adding 1000-5000 w-ppm phosphoric, citric or sulfuric acid, water until a total of 1-5 wt%, heating to 60-90°C, and separating the gums;

[0136] - Alkali refining, for example treating the oil with alkali to remove free fatty acids as soap, followed by addition of adsorbent and filtration;

[0137] - bleaching, for example adding 100-5000 w-ppm citric acid, optionally adding 0.1 -1 wt% water, adding 0.2-2 wt% adsorbent, mixing, drying and filtering;

[0138] - deodorisation, for example at 220-260 °C, 1 -200 mbar; such as filter-aid filtration followed by heat treatment followed by bleaching.

[0139] The purification reduces the metal impurities and phosphorus impurities, and forms a purified feedstock for renewable hydrocarbon production having less metal impurities measured in w-ppm and phosphorus impurities measured in w-ppm than the feedstock for renewable hydrocarbon production. The one or more purification steps may be combined with drying and / or evaporation or be preceded or followed by a drying step. This can be done at any suitable conditions that evaporate water.

[0140] As mentioned herein, metal impurities and phosphorus impurities can cause problems downstream, in particular in the hydrotreating reactor, where the catalyst lifetime is influenced by the presence of too high impurity levels.

[0141] The purified feedstock for renewable hydrocarbon production may contain no free water phase, e.g. may contain less than 0.3 wt% water. It is not uncommon that the purified feedstock for renewable hydrocarbon production contains less than 0.4 wt%, e.g. less than 0.1 wt% water, for example around 0.05 wt% water.

[0142] An aqueous wastewater phase comprising C2-C6 aliphatic oxygenates is separated during the purification step. The aqueous wastewater phase may also comprise metal impurities and phosphorus impurities, although the majority of these types of impurities have been separated during the purification steps, e.g. adsorbed on bleaching earths. Separating the aqueous wastewater phase during the purification step(s) may include phase separation (e.g. settling, centrifugation) or separation by drying / evaporation. P-23039 / P466618PC00

[0143] 19 / 44

[0144] As mentioned herein the feedstock for renewable hydrocarbon production may contain C2-C6 aliphatic oxygenates which are present in many waste oils, from e.g. fermentation, anaerobic degradation and other degradation processes. C2-C6 aliphatic oxygenates include short-chain carboxylic acids, such as C2-C6 carboxylic acids. For example, acetic acid (C2), propionic acid (C3), butanoic acid (C4), pentanoic acid (C5) and hexanoic acid (Ce) as well as their isomers. Other aliphatic oxygenates include phenols, alcohols and esters, for example C2-C6 aliphatic oxygenates include glycerol and C2-C6 alcohols. During purification these oxygenates usually end up in the aqueous wastewater phase, and contribute to the pollution thereof, as measured using the chemical oxygen demand (COD). Accordingly, the aqueous wastewater phase may comprise these C2-C6 aliphatic oxygenates. For example, the aqueous wastewater phase may comprise C2-C6 carboxylic acids, such as 1000 mg / kg C2-C6 carboxylic acids or more, such as 5000 mg / kg C2-C6 carboxylic acids or more, or even 9000 mg / kg C2-C6 carboxylic acids or more. These C2-C6 aliphatic oxygenates, including the C2-C6 carboxylic acids contribute to the pollution of the aqueous wastewater phase. The higher the amount of these C2-C6 aliphatic oxygenates, the higher the COD value, i.e. the amount of oxygen required to oxidize / clean the organic wastewater. A high COD level implies that more extensive wastewater treatment is necessary to minimize the environmental effect caused by the wastewater. It is therefore desirable that the COD level is as low as possible in the wastewater.

[0145] The aqueous wastewater phase comprising C2-C6 aliphatic oxygenates referred to in step (b) may have a COD value of 1000 mg O / l or more, such as 10000 mg O / l or more, or even having a COD value of 20000 mg O / l or more.

[0146] For example, the aqueous wastewater phase comprising C2-C6 aliphatic oxygenates referred to in step (b) may have a sum of C2-C6 carboxylic acids in the range of 1000-20000 mg / kg. P-23039 / P466618PC00

[0147] 20 / 44

[0148] Step (d) - Extraction of aqueous wastewater

[0149] The process according to the present invention also includes a step (d) of extracting part of the C2-C6 aliphatic oxygenates from the aqueous wastewater phase with a feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, having less than 10 w-ppm metals, less than 10 w-ppm phosphorus, where the w-ppm is calculated based on the further feedstock for renewable hydrocarbon production.

[0150] During extraction the aqueous wastewater phase is mixed with a feedstock for renewable hydrocarbon production, which may be or include part of the purified feedstock for renewable hydrocarbon production. The feedstock for renewable hydrocarbon production used for extraction is an oil phase, which is not miscible with the aqueous wastewater phase. Mixing the aqueous and oil phase causes components in these phases to partition in the two phases. In particular, it was found that a significant part of the C2-C6 aliphatic oxygenates from the aqueous wastewater phase could be extracted to the oil phase, forming a feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates and an aqueous wastewater phase depleted of C2-C6 aliphatic oxygenates. Not only that, but the metal impurities and phosphorus impurities did not migrate back to the oil phase, and did not increase the water content of the oil phase to an extent where it was detrimental to the downstream hydrotreating step, as the feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates can be used either directly, or used directly after being mixed with a dryer feedstock for renewable hydrocarbon production obtained in step (b) of the process.

[0151] It is advantageous that the feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates can be used directly in the hydrotreatment step without any further purification, as it makes the process more efficient in addition to increasing the amount of feedstock that can be hydrotreated to form hydrocarbons. P-23039 / P466618PC00

[0152] 21 / 44

[0153] At the same time it reduces the COD of the aqueous wastewater phase depleted of C2-C6 aliphatic oxygenates, which in turns saves space for further processing of the wastewater to bring it to even lower levels of COD.

[0154] The extraction causes the COD levels to lower in the aqueous wastewater phase depleted of C2-C6 aliphatic oxygenates, because i.a. the levels of C2-C6 aliphatic oxygenates are reduced, and they contribute to the COD level of the aqueous wastewater. In some instances, the aqueous wastewater phase depleted of C2-C6 aliphatic oxygenates, will have a COD level that is reduced by 20% or more compared to the aqueous wastewater phase comprising C2-C6 aliphatic oxygenates before the extraction step, for example the COD level may be reduced by 30% or more compared to the aqueous wastewater phase comprising C2-C6 aliphatic oxygenates before the extraction step.

[0155] The extraction may be performed as a liquid-liquid extraction. A liquid-liquid extraction may be performed above the melting point of the oil used for extraction, and below the boiling point of the aqueous phase that is to be extracted. For example, a liquid-liquid extraction may be performed above the melting point of the feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, having less than 10 w-ppm metals, less than 10 w-ppm phosphorus, which may be the purified feedstock for renewable hydrocarbon production from step (b) or the extraction agent of step (c) and below the boiling point of water.

[0156] The liquid-liquid extraction may be performed just above the melting point of the oil used for extraction at the pressure used during extraction. At ambient pressure (1 atm) this may be around 40 °C or higher. As shown in the examples, increasing the temperature improves the removal of organic compounds, i.e. the COD impurities and thus lowers the COD. Accordingly, the liquid-liquid extraction may be performed at temperatures higher than the melting point of the oil used for extraction (e.g. part of the purified feedstock for renewable hydrocarbon production), for example around 50 °C or higher, or 60 °C or higher. Liquid-liquid extraction finds its natural upper temperature limit at the boiling point of the aqueous phase that is to be extracted at the pressure used during extraction. At ambient pressure (1 atm), the aqueous P-23039 / P466618PC00

[0157] 22 / 44 phase will often have a boiling point above 100 °C due to boiling point elevation caused when a compound is added to water to form an aqueous phase. The liquidliquid extraction may therefore be performed at temperatures lower than the boiling point of the aqueous wastewater phase comprising C2-C6 aliphatic oxygenates that is to be extracted, for example around 100 °C or lower, such as around 90 °C or lower, or around 80 °C or lower. Accordingly, the liquid-liquid extraction may be performed at temperatures between 40-100°C, such as between 40-95°C, both ranges covering the range where both the oil and aqueous phase are expected to be liquid at ambient pressure (1 atm). The liquid-liquid extraction may also advantageously be performed at elevated temperature ranges of between 50-95 °C, such as between 55-85 °C, which are temperatures that may remove a significant amount of COD impurities from the aqueous phase, e.g. the COD level is lowered by at least about 20-50%. The liquid-liquid extraction may also advantageously be performed at even more elevated temperature ranges of between 70-90 °C, where even higher amounts of COD impurities can be removed compared to temperatures below that range.

[0158] For example, the extraction in step (d) may be performed as a liquid-liquid extraction at a temperature range of 50-95 °C, such as 55-85 °C.

[0159] The extraction in step (d) may be performed as a liquid-liquid extraction at an elevated pressure of 2-70 bar pressure, and at a temperature range where the extraction remains a liquid-liquid extraction at the given extraction pressure. For example, at 50 bar(g) the boiling point of water is about 265 °C. The extraction step (d) may for example be performed as a liquid-liquid extraction at an elevated pressure of 2-70 bar pressure, and at a temperature range of 20 °C to 280 °C. At extraction temperatures higher than 280 °C undesirable thermal degradation may occur.

[0160] A liquid-liquid extraction may be performed at an oil-to-water ratio. The ratio may be varied depending on the aim. Significant amounts of COD impurities can be removed from the aqueous phase to be extracted even if only a small amount of oil is used for extraction compared to the aqueous phase that is to be extracted, e.g. P-23039 / P466618PC00

[0161] 23 / 44

[0162] 0.5 part oil to 1.0 part water (oil-to-water ratio of 0.5: 1.0). For example an oil-to- water ratio of 0.2: 1.0 would be useful in removing some of the COD. This would also minimise the volume of oil used for extraction. Accordingly, the liquid-liquid extraction may be performed at an oil-to-water ratio of 0.2:1 .0 or higher, for example 0.5:1.0 or higher, or 0.9:1.0 or higher.

[0163] The amount of COD impurities that can be removed from the aqueous phase to be extracted increases with increasing oil-to-water ratio, and as much as up to 80% of the COD could be removed at a high oil-to-water ratio of up to 20.0:1 .0, for example at an oil-to-water ratio of up to 10.0: 1 .0.

[0164] Accordingly, the liquid-liquid extraction may be performed at oil-to-water ratios between 0.2:1 .0 to 20.0:1 .0, for example between 0.4:1 .0 to 10.0:1 .0. If one of the aims of the liquid-liquid extraction in addition to reduction in wastewater COD also lies in reducing the amount of oil used for the extraction, then the liquid-liquid extraction may be performed at oil-to-water ratios of 0.4: 1.0 to 4.0:1.0 to maximise the COD extracted using as little oil as possible.

[0165] The extraction temperatures / pressures and oil-to-water ratios may also be freely combined. For example, the liquid-liquid extraction may be performed at oil-to-water ratios between 0.2: 1.0 to 20.0:1.0 and at temperatures between 40-100°C, such as at oil-to-water ratios between 0.4: 1.0 to 10.0:1.0 and at temperatures between 50- 95°C, or at the other oil-to-water ratios and / or temperature / pressures noted herein.

[0166] Various liquid-liquid extraction methods are known by skilled persons in the art. In the context of the present invention, it may be advantageous that the extraction is performed as a counter-current liquid-liquid extraction. The counter-current liquidliquid extraction may increase the efficiency of the extraction.

[0167] The extraction should ensure effective mixing and mass transfer between the phases. This may be achieved with various mixing elements and internals as well as mixers placed within the extraction equipment. For example, The extraction may be performed as a liquid-liquid extraction in one or more mixer-settlers in series, e.g. P-23039 / P466618PC00

[0168] 24 / 44 where the phases are mixed in a container and allowed to settle before separating the phases. For example, the extraction may be performed in one or more mixersettler extractor. Using more than one mixer-settler extractor may improve the extraction. When more than one mixer-settler extractor is used, they may be connected in series. The extraction may be performed as a liquid-liquid extraction in one or more mixer-settlers, where the extraction is repeated one or more times, e.g. 3-15 times.

[0169] The extraction may be performed as a counter-current liquid-liquid extraction in an extraction column, where the oil phase, which has a lower density (light phase) than the water phase to be extracted (heavy phase), is introduced to the bottom of the column and flows upward due to density difference to the water phase. The water (heavy) phase is introduced to the top of the column from where it settles towards the bottom of the column. Various internals such as feed distributors, nozzles, baffles, random packing, structured packing, rotating mixers, or static mixers may be employed to improve dispersion and turbulence of the oil phase among the water phase. It is relevant to maintain effective dispersion and mixing to ensure effective mass transfer between the two phases over the length of the column.

[0170] For example, the extraction may be performed as a counter-current liquid-liquid extraction in a reciprocating plate column, also known as a Karr reciprocating plate column. A reciprocating plate column comprises a series of perforated plates with large diameter holes and high free cross-sectional area mounted on a reciprocated central shaft, i.e. a shaft that can move back-and-forth in an oscillating motion. The shaft with the perforated plates is enclosed in the column and connected to a variable speed motor to adjust the reciprocating motion, also called strokes. The strokes per minute (SPM) can be varied, and may for example be between 20-360 SPM, for example between 40-240 SPM, such as between 120-240 SPM.

[0171] The efficiency of an extraction may be measured by the number of theoretical extraction stages also called ideal stages. Shaking a mixture of oil and aqueous phase in a separation funnel is normally considered to constitute a single extraction stage. The efficiency of an extraction process is then measured theoretically in P-23039 / P466618PC00

[0172] 25 / 44 relation to the efficiency of a single extraction stage, e.g. using a separation funnel. The Kremser equation is the classical method for determining the number of stages in counter-current mass exchange units. A higher number of theoretical extraction stages usually results in a higher separation, which means that in the case of extracting part of the C2-C6 aliphatic oxygenates from the aqueous wastewater phase with a feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, having less than 10 w-ppm metals, less than 10 w-ppm phosphorus, which may e.g. include part of the purified feedstock for renewable hydrocarbon production, more of the C2-C6 aliphatic oxygenates can be extracted from the aqueous phase to the oil phase, thereby reducing the COD value in the aqueous wastewater phase.

[0173] For example, the extraction may be performed as a liquid-liquid extraction where the number of extraction stages is at least 2. For example it is not uncommon to have liquid-liquid extraction methods, e.g. counter-current extraction using an extraction column, such as a reciprocating plate column. Such columns may have at least 4 theoretical stages, such as at least 8 or at least 12 theoretical stages. For example, the number of extraction stages may be between 10 and 20 theoretical stages.

[0174] The number of extraction stages can be adjusted in an extraction column, such as a reciprocating column i.a. by manipulating the SPM, flow rate of both the oil phase and the aqueous phase, and / or by adjusting the rotational speed of mixers within the column. The number of theoretical extraction stages also depends on the dimensions and design of the extraction column, such as a reciprocating plate column, and can be determined by the skilled person for any given extraction column, such as a reciprocating plate column.

[0175] Step (c) - Optionally providing an extraction agent by mixing

[0176] As mentioned herein, the process according to the present invention also includes a step (d) of extracting part of the C2-C6 aliphatic oxygenates from the aqueous P-23039 / P466618PC00

[0177] 26 / 44 wastewater phase with the extraction agent provided in step (c), which includes part of the purified feedstock for renewable hydrocarbon production.

[0178] In step (c) the purified feedstock for renewable hydrocarbon production from step (b) may be mixed with a further feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides. The further feedstock for renewable hydrocarbon production should have less than 10 w-ppm metal impurities, less than 10 w-ppm phosphorus impurities, and optionally less than 0.3 wt% water, where the w-ppm and wt% is calculated based on the further feedstock for renewable hydrocarbon production, thereby being suitable to be fed to a hydrotreating step without further purification, as the case is also for the purified feedstock for renewable hydrocarbon production from step (b).

[0179] Accordingly, the process according to the present invention includes an optional step (c) of providing an extraction agent by mixing part of the purified feedstock for renewable hydrocarbon production from step (b) with a further feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, having less than 10 w-ppm metals, less than 10 w-ppm phosphorus, and optionally less than 0.3 wt% water, where the w-ppm and wt% is calculated based on the further feedstock for renewable hydrocarbon production.

[0180] The feedstock (extracting agent) obtained in step (c) may then be used for the extraction described in step (d).

[0181] In the extraction step (d) the composition of the oil phase used for extraction is relevant for the efficiency of the extraction step, whether it is part of the purified feedstock for renewable hydrocarbon production or the feedstock (extraction agent) obtained in step (c). When it comes to extracting part of the C2-C6 aliphatic oxygenates from the aqueous wastewater phase with the feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, having less than 10 w-ppm metals, less than 10 w-ppm phosphorus or the feedstock obtained in step (c), it is advantageous that the oil phase contains free fatty acids, as it is seen that a higher proportion of free fatty acids in the oil phase improves the P-23039 / P466618PC00

[0182] 27 / 44 extraction of the C2-C6 aliphatic oxygenates from the aqueous wastewater phase, thereby reducing the COD levels in the aqueous wastewater phase.

[0183] It is therefore advantageous that in step (c) the feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, having less than 10 w-ppm metals, less than 10 w-ppm phosphorus has a higher amount of free fatty acids than the purified feedstock for renewable hydrocarbon production obtained in step (b). For example, the extraction agent in step (c) may have a free fatty acid amount at least 10% higher than the purified feedstock for renewable hydrocarbon before mixing, and / or the extraction agentin step (c) may have a free fatty acid content of 10-90 wt%.

[0184] For example, in step (c) the feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, having less than 10 w-ppm metals, less than 10 w-ppm phosphorus may contain more than 50 wt% of C and C18 free fatty acids, and / or in step (c) the further feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, having less than 10 w- ppm metals, less than 10 w-ppm phosphorus may be selected from one or more of: palm oil mill effluent (POME), used cooking oil, animal fat, yellow grease, brown grease, soapstock acid oil, or tall oil, algae oil (AO), and oils from regenerative agriculture.

[0185] Step (e) - Optionally mixing with more of the purified feedstock

[0186] The feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates obtained from the extraction step (d) may be used directly in a hydrotreating process, or may optionally in a step (e) undergo mixing where at least part of or all of the feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates is mixed with part of or the remaining part of the purified feedstock for renewable hydrocarbon production.

[0187] Should it be desired, the feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates may be mixed with part of or the remaining part of P-23039 / P466618PC00

[0188] 28 / 44 the purified feedstock for renewable hydrocarbon production. This is because moisture may potentially also be absorbed to the feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates during the extraction step. Mixing with part of or the remaining part of the purified feedstock for renewable hydrocarbon production obtained from step (b) reduces the water content of the combined feedstock, which will be closer to the water content of the purified feedstock for renewable hydrocarbon production obtained from step (b).

[0189] Step (f) - Hydrotreatment

[0190] In step (f) the feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates obtained in step (d) or the feedstock obtained in step (e) may be provided to one or more catalytic hydrotreating steps, whereby at least deoxygenation is effected in the presence of hydrogen at elevated temperatures, such as 200-450°C and at elevated pressures, such as 10-150 bar to form hydrocarbons.

[0191] The C2-C6 aliphatic oxygenates will also be hydrogenated to form hydrocarbons. The hydrocarbons include C2-C6 hydrocarbons, but seeing that a number of the C2-C6 aliphatic oxygenates also include C2-C6 carboxylic acids, they may react during the hydrodeoxygenation conditions to form dimers with other carboxylic acids, fatty acids or unsaturated fatty acids in the feedstock. For example, ketonisation reactions may occur between e.g. acetic acid and a C fatty acid resulting in a dimer that is hydrodeoxygenated to a hydrocarbon in the diesel pool hydrocarbon range.

[0192] The one or more catalytic hydrotreatment step(s) may be performed in a hydrotreatment reactor, which is a vessel that can house at least one catalytic zone. In the present invention a trickle-bed reactor is well-suited. A trickle bed reactor involves the downward movement of the feedstock while it is contacted with hydrogen in a co-current or counter-current manner. An example of a trickle bed reactor is an adiabatic trickle-bed reactor. P-23039 / P466618PC00

[0193] 29 / 44

[0194] The catalytic zone may in its simplest form be a fixed bed of catalyst particles. It may also be multiple fixed beds having the same or different catalyst particles, or it may be a number of layers of catalyst particles of different activity and / or composition.

[0195] For example, the hydrotreatment reactor may comprise at least three catalytic zones or up to three catalytic zones, for example one, two or three catalytic zones.

[0196] The feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates obtained in step (d) or the feedstock obtained in step (e) may be introduced together with a hydrogen-rich gas to a first hydrotreatment reactor comprising at least one catalytic zone.

[0197] The feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates obtained in step (d) or the feedstock obtained in step (e) is introduced together with a hydrogen-rich gas into the catalytic zone at an inlet temperature and a pressure causing hydrodeoxygenation of the oxygen-containing components thereby converting them essentially completely to hydrocarbons.

[0198] There are many different combinations of inlet temperatures and pressures, which would cause hydrodeoxygenation essentially completely to hydrocarbons. For example the inlet temperature and pressure of hydrotreatment reactor may be 200-400 °C and 10-150 bar, for example 250-380 °C and 20-120 bar, such as 280-360 °C and 30-100 bar.

[0199] It is a matter of routine work for the skilled persons to select various combinations of temperatures and pressures causing hydrodeoxygenation of the oxygencontaining components thereby converting them essentially completely to hydrocarbons, e.g. to at least 98% hydrocarbons, such as at least 99% hydrocarbons.

[0200] In the same manner that the skilled persons can select various combinations of temperatures and pressures, they would also be able to select one or more P-23039 / P466618PC00

[0201] 30 / 44 suitable catalysts for the one or more catalytic zones of the first hydrotreatment reactor.

[0202] For example, the catalytic zone(s) of the hydrotreatment reactor(s) may comprise one or more catalyst(s) selected from hydrogenation metal on a support, such as for example a catalyst selected from a group consisting of Pd, Pt, Ni, Co, Mo, Ru, Rh, W or any combination of these. For example, the catalytic zone(s) may comprise one or more catalyst(s) selected from CoMo, NiMo, NiW, CoNiMo on a support, for example an alumina support. When the catalyst is selected from the group consisting of Ni, Co, Mo, Ru, Rh, W or any combination of these, then typically the catalyst is sulfided, and a source of sulfur is either added or present in the feedstock and / or in the hydrogen-rich gas.

[0203] The hydrotreatment reactor may be operated at a WHSV in the range from 0.5-3 IT1, such as 0.5-1 .5 IT1and a H2flow of 350-2100 NI H2 / l feed, such as 500-1500 NI H2 / l feed.

[0204] More general reaction conditions for the hydrotreatment step may involve a tricklebed reactor as the hydrotreating reactor, comprising a catalyst zone, the catalyst zone comprising a supported hydrogenation catalyst comprising molybdenum, where the hydrotreatment is conducted in the presence of hydrogen at a temperature of 200-400 °C and at a pressure between 10-150 bar, where the WHSV is in the range from 0.5-3 IT1, and at a H2flow of 300-2100 NI H2 / l feed.

[0205] With reference to figure 1 , in an embodiment the present process for purifying a feedstock for renewable hydrocarbon productions comprises providing a feedstock for renewable hydrocarbon production as defined herein, such as a feedstock comprising palm oil mill effluent (POME) and purifying the feedstock in one or more purification steps as defined herein and where an aqueous wastewater phase comprising C2-Ce aliphatic oxygenates (1) as defined herein is separated and thereby forming a purified feedstock (2) for renewable hydrocarbon production as defined herein. Optionally at least part of or all the purified feedstock (2) is mixed (not shown) with a further feedstock for renewable hydrocarbon production as P-23039 / P466618PC00

[0206] 31 / 44 defined herein to provide an extraction agent. The aqueous wastewater phase (1) is then introduced into a counter current extraction column (10) for extracting part of the C2-C6 aliphatic oxygenates from the aqueous wastewater phase thereby providing an aqueous wastewater phase depleted of C2-C6 aliphatic oxygenates and a feedstock for renewable hydrocarbon production enriched with C2-C6 oxygenates. The countercurrent extraction column (10) may comprise 2-10 ideal separation phases for separating at least a light phase (3) comprising feedstock for renewable production enriched with C2-C6 aliphatic oxygenates and a heavy phase (4) comprising wastewater depleted of aliphatic oxygenates. Optionally, the light phase (3) is flown from the top of counter current extraction column (10) via pipe to a light phase decanter (12), where first decanted wastewater depleted of aliphatic oxygenates (5) and a feedstock for renewable production enriched with C2-C6 aliphatic oxygenates (6) are separated. First decanted wastewater depleted of aliphatic oxygenates may then be combined with the heavy phase (4) comprising wastewater depleted of aliphatic oxygenates. The feedstock for renewable production enriched with C2-C6 aliphatic oxygenates (6) may then be sent to hydrotreatment and / or recirculated to the extraction step. The wastewater depleted of aliphatic oxygenates (7) may then be sent to biological wastewater treatment. Also depicted is the heavy phase hold-up drum (13).

[0207] The renewable character of carbon-containing compositions, such as feedstocks and products, can be determined by comparing the14C-isotope content of the feedstock to the14C-isotope content in the air in 1950. The14C-isotope content can be used as evidence of the renewable origin of the feedstock or product.

[0208] Carbon atoms of renewable material comprise a higher number of unstable radiocarbon (14C) atoms compared to carbon atoms of fossil origin. Therefore, it is possible to distinguish between carbon compounds derived from biological sources, and carbon compounds derived from fossil sources by analysing the ratio of12C and14C isotopes. Thus, a particular ratio of said isotopes can be used to identify renewable carbon compounds and differentiate those from non-renewable i.e. fossil carbon compounds. The isotope ratio does not change in the course of chemical reactions. Examples of a suitable method for analysing the content of carbon from biological sources is ASTM D6866 (2020). An example of how to apply ASTM D6866 P-23039 / P466618PC00

[0209] 32 / 44 to determine the renewable content in fuels is provided given in the article of Dijs et al., Radiocarbon, 48(3), 2006, pp 315-323. For the purpose of the present invention, a carbon-containing material, such as a feedstock or product is considered to be of renewable origin if it contains 90% or more modem carbon, such as 100% modern carbon, as measured using ASTM D6866.

[0210] When describing the embodiments of the present invention, the combinations and permutations of all possible embodiments have not been explicitly described. Nevertheless, the mere fact that certain measures are recited in mutually different dependent claims or described in different embodiments does not indicate that a combination of these measures cannot be used to advantage. The present invention envisages all possible combinations and permutations of the described embodiments. The terms “comprising”, “comprise” and “comprises” herein are intended by the inventors to be optionally substitutable with the terms “consisting of”, “consist of’ and “consists of”, respectively, in every instance.

[0211] P-23039 / P466618PC00

[0212] 33 / 44

[0213] Examples

[0214] Analysis methods used

[0215] Elemental phosphorus and metals: The concentration of phosphorus and metals was analysed from all samples by first digesting the sample with acids in a microwave oven to obtain a clear water / acid matrix (assessed visually), then diluting it to a known amount and analysing it against the acid based calibration using ICP- MS / MS (tandem Inductively Coupled Plasma Mass Spectrometry). Elements detected by the method include Li, B, Na, Mg, Al, P, Si, K, Ca, Ti, V, Ch, Mn, Fe, Co, Ni, Cu, Zn, As, Mb, Cd, Sn, and Ba.

[0216] Triglycerides, diglycerides, monoglycerides, free fatty acids: Mono-, di- and triglycerides, fatty acids and paraffins are separated by molecular size using size exclusion technique. High resolution GPC column set, HPLC system with refractive index detector are set-up for this separation technique.

[0217] Water: Water content of all the samples was determined according to ASTM D6304-20, procedure C. The method is based on a coulometric Karl Fischer titration.

[0218] Volatile components: LC-MS method for short chain carboxylic acids, which is used to determine quantitatively or semi-quantitatively Ci-Ce monocarboxylic acids and select oxo-, hydroxy- and dicarboxylic acids from aqueous and (bio)oil-based samples employing mass spectrometry detection. For oil-based samples a liquidliquid extraction is performed. At the start of the sample preparation, stable isotopelabelled internal standard solutions (7 different standards) are added into the samples. Carboxylic acids are analysed using ion exclusion chromatography (IEC) and mass spectrometric (MS) detection. Carboxylic acids are ionised using electrospray ionisation (negative mode, ESI-) before being fed to the mass spectrometer. For other VOCs standard method A.O.C.S. Ca 3b-87 is used (ISO 9832) (Headspace VOC analysis with GC-MS).

[0219] COD: Chemical oxygen demand was determined according to IS015705-2002M. P-23039 / P466618PC00

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[0221] Feedstocks

[0222] Table A - Bulk composition and impurities in the samples used in example 1: Triglyceride model oil (RBDPO), FFA model oil (linoleic acid), Bleached POME resulting in wastewater

[0223] Table B - Bulk composition and impurities in the samples used in example 2: Purified feedstock oil, Crude POME, Bleached POME, and wastewater from bleaching. P-23039 / P466618PC00

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[0225] Example 1 - Batch extraction of wastewater

[0226] A Palm Oil Mill Effluent (POME) sample was purified by bleaching (addition of citric acid 2000 w-ppm, water 1.25 wt% and bleaching earth 1 wt% at 85 °C, mixing for 20 min, drying at 105 °C (80 mbara) for 35 min, filtration with a leaf filter) to obtain bleached POME and an aqueous wastewater phase containing among other things aliphatic oxygenates including acetic acid, butanoic acid and hexanoic acid, which contribute to the high chemical oxygen demand (COD) of the wastewater.

[0227] The aqueous wastewater having an initial chemical oxygen demand (COD) of 30000 mg O / l was extracted with a triglyceride rich oil (Triglyceride model oil: RBDPO, i.e. refined, bleached and deodorised palm oil) and with a FFA rich oil (FFA model oil: linoleic acid) at varying temperature and ratio of oil : water (see conditions below in Table 1 ). The Triglyceride model oil or FFA model oil were mixed with the aqueous wastewater in a separation funnel, and brought to a temperature of 60 or 80 °C in a heating cabinet. The separation funnel was shaken for 3 minutes and returned to the heating cabinet. An aqueous phase and an oil phase were separated, and the chemical oxygen demand (COD) measured from the aqueous phase, and reported in table 1 below:

[0228] Table 1 - Batch extraction of wastewater to reduce COD P-23039 / P466618PC00

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[0230] The observed COD reduction in the wastewater was 26-46%. It can be seen that increasing the oil : water ratio from 0.5:1 to 1 :1 to 3:1 increases the reduction of COD in the wastewater with 26%, 31 %, and 46%, respectively.

[0231] The use of a more polar solvent such as FFA rich oil (FFA model oil, linoleic acid, 99% free fatty acids) compared to the triglyceride rich oil (triglyceride model oil, RBDPO (93% triglycerides and 0.4% free fatty acids) improved the reduction in COD by approximately 10 percentage points.

[0232] Increasing the extraction temperature by 20 °C from 60 °C to 80 °C improved the reduction in wastewater COD by approximately 10 percentage points at the same oil : water ratio.

[0233] The solvents used (Triglyceride model oil and FFA model oil) and aqueous wastewater had a small amount of metal and phosphorus impurities (see table 2 below). As evident from table 2 below there was no significant transfer of phosphorus or metal impurities from the wastewater to the solvent product phase, as the sum of P, Si, Na, K, Ca, Mg for the Triglyceride model oil (RBDPO) and FFA model oil (linoleic acid) products remained below 5 mg / kg in this experiment.

[0234] Table 2 - Phosphorus and metal impurities measured as elemental phosphorus and metal in the extraction experiments compared to the Triglyceride model oil (RBDPO), FFA model oil (linoleic acid) and aqueous waste water. P-23039 / P466618PC00

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[0236] Example 2 - Continuous extraction of wastewater

[0237] Similar to example 1 , the same Palm Oil Mill Effluent (POME) sample was purified by bleaching with slightly more water and an aqueous wastewater phase (wastewater 2) containing among other things aliphatic oxygenates including acetic acid, butanoic acid and hexanoic acid, which contribute to the high chemical oxygen demand (COD) of the wastewater was obtained.

[0238] The aqueous wastewater having an initial chemical oxygen demand (COD) of 22200 mg O / l was extracted with a purified feedstock blend containing 31 .7 wt% of bleached POME (lipid mixture with 74% triglycerides and 17% FFA, see Table B). This liquid-liquid extraction was performed in a Karr counter-current extraction column, where the wastewater was a continuous phase and the purified feedstock was the dispersed phase.

[0239] The temperature was 80 °C, and the ratio of oil : water was 1 :1.5 (0.67:1 ). This oikwater ratio was achieved with adjusting oil and water flow rates to the column. The flow rate of oil was 14 ml / min and the flow rate of water was 20 ml / min. 180 strokes per minute (SPM) agitation was used. In total these conditions (flow and agitation) resulted in an estimated 16 ideal stages. The wastewater product from the extraction (raffinate) had a reduced COD of 14200 mg O / l corresponding to 36% COD reduction. The short chain carboxylic acids were the main source of COD in the wastewater. The reduction of various aliphatic oxygenates from the wastewater was quantified, and tabulated below in tables 3 and 4. The majority of the aliphatic oxygenates included hexanoic, butanoic and acetic acid. P-23039 / P466618PC00

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[0241] Table 3 - Amounts of glycerol and short chain carboxylic acids removed by continuous extraction. Table 4 - Amounts of phenols, alcohols, esters and other VOCs removed by continuous extraction.

[0242] The product contained no free water. The short chain carboxylic acid representing an unwanted COD in the wastewater is removed therefrom and transferred to the product oil (extract). The product oil (extract) can be fed directly to a HDO step P-23039 / P466618PC00

[0243] 39 / 44 without further purification where it is converted to hydrocarbons in the hydrodeoxygenation step that follows thereby increasing the overall hydrocarbon yield from the POME and reducing the COD of the wastewater.

[0244] Example 3 - Simulation of Example 2 and extrapolation to Higher Qi I: Water Ratios

[0245] Simulations were carried out with an Aspen Plus steady-state process simulation model, the results shown in figure 2 (simulation data in small circles). The results were compared to Example 2 KARR counter-current extraction column results (figure 2, large circle). The simulation results matched the observed experimental results in terms of COD reduction. The model was slightly pessimistic in COD removal estimates compared to the experimental result. Simulated water phase COD reduction was 34.5 %-units whereas the experimental result was 38 %-units. When extrapolating column performance to other conditions, the simulation model predicts significantly improved COD reduction when oikwater ratios are increased (> 80%-units COD reduction at 9:1 oikwater ratio).

Claims

P-23039 / P466618PC0040 / 44Claims1. A process for purifying a feedstock for renewable hydrocarbon production comprising the following steps:(a) providing a feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, and including impurities in the form of metal impurities and phosphorus impurities, as well as up to 4 wt% water, and optionally solid matter, where the feedstock includes at least 0.01 wt% C2-C6 aliphatic oxygenates;(b) purifying the feedstock for renewable hydrocarbon production in one or more purification steps whereby metal impurities and phosphorus impurities are reduced, and where an aqueous wastewater phase comprising C2-C6 aliphatic oxygenates is separated, thereby forming a purified feedstock for renewable hydrocarbon production having less metal impurities measured in w-ppm and phosphorus impurities measured in w-ppm than the feedstock for renewable hydrocarbon production;(c) optionally providing an extraction agent by mixing at least part of or all the purified feedstock for renewable hydrocarbon production from step (b) with a further feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, having less than 10 w-ppm metals, less than 10 w- ppm phosphorus, where the w-ppm is calculated based on the further feedstock for renewable hydrocarbon production;(d) extracting part of the C2-C6 aliphatic oxygenates from the aqueous wastewater phase with a feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, having less than 10 w-ppm metals, less than 10 w-ppm phosphorus, where the w-ppm is calculated based on the feedstock for renewable hydrocarbon production; and / or with the extraction agent provided in step (c), thereby providing an aqueous wastewater phase depleted of C2-C6 aliphatic oxygenates, and a feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates.(e) optionally mixing at least part of or all of the feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates with part of or the remaining part of the purified feedstock for renewable hydrocarbonP-23039 / P466618PC0041 / 44 production;(f) providing the feedstock for renewable hydrocarbon production enriched with C2-C6 aliphatic oxygenates obtained in step (d) or the feedstock obtained in step (e) to one or more catalytic hydrotreating steps, whereby at least deoxygenation is effected in the presence of hydrogen at elevated temperatures, such as 200-450°C and at elevated pressures, such as 10-150 bar to form hydrocarbons; where the metal and phosphorus impurities are measured as elemental metal and phosphorus impurities.

2. Process according to claim 1 , where the feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides referred to in step (a) has one or more of:- an oxygen content in the range of 3.0-20 wt%;- a water content of less than 4 wt%;- a total acid number in the range of 5-200 mg KOH / g;- less than 70 wt% of an oil fraction with a boiling point of less than 350 °C;- the sum of C2-C6 carboxylic acids in the range of 100-20000 mg / kg;- a free fatty acid content of 10-90 wt%;3. Process according to claims 1 or 2, where the feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides referred to in step (a) is selected from one or more from the list consisting of: palm oil mill effluent (POME), used cooking oil, animal fat, yellow grease, brown grease, soapstock acid oil, tall oil, algae oil (AO), and oils from regenerative agriculture.

4. Process according to any one of claims 1 -3, where the one or more purification steps are selected from one or more of:- drying, for example at elevated temperature and / or at reduced pressure;- filter-aid filtration, for example filtering in the presence of 0.1-1 wt% filter aid;- settling, for example in a settling tank;- water washing, for example in a tank or in a counter current column;- heat treatment, for example heating to at least 150 °C , such as 150-400 °C,P-23039 / P466618PC0042 / 44 preferably of to at least 200 °C, such as 200-350 °C, more preferably to at least 220 °C, such as 220-350 °C, more preferably 220-280°C for a sufficient period of time, such as 0.5-300 min, preferably 30-60 min;- degumming, for example adding 1000-5000 w-ppm phosphoric, citric or sulfuric acid, water until a total of 1-5 wt%, heating to 60-90°C, and separating the gums;- Alkali refining, for example treating the oil with alkali to remove free fatty acids as soap, followed by addition of adsorbent and filtration;- bleaching, for example adding 100-5000 w-ppm citric acid, optionally adding 0.1 -1 wt% water, adding 0.2-2 wt% adsorbent, mixing, drying and filtering;- deodorisation, for example at 220-260 °C, under 1-200 mbar; such as filter-aid filtration followed by heat treatment followed by bleaching.

5. Process according to any one of claims 1 -4, where the extraction is performed as a liquid-liquid extraction above the melting point of the feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, having less than 10 w-ppm metals, less than 10 w-ppm phosphorus or the extraction agent of step (c), and below the boiling point of water.

6. Process according to any one of claims 1 -5, where the extraction is performed as a counter-current liquid-liquid extraction.

7. Process according to any one of claims 1 -6, where the extraction is performed as a liquid-liquid extraction where the oil-to-water ratio is from 0.2: 1.0 to 20.0:1.0, such as from 0.4:1.0 to 10.0:1.0, such as 0.4:1.0 to 4.0:1.0.

8. Process according to any one of claims 1 -7, where the extraction is performed in one or more mixer-settler type extractor(s) and / or as a counter-current liquid-liquid extraction in one or more column extractor(s).P-23039 / P466618PC0043 / 449. Process according to any one of claims 1 -8, where the extraction is performed as a liquid-liquid extraction and where the number of extraction stages is at least 2, such as at least 4, 6, 8 or 10.

10. Process according to any one of claims 1 -9, where the extraction is performed as a liquid-liquid extraction, and whereby in step (c) the extraction agent fulfils one or more of the following:- the combined feed in step (c) having a free fatty acid amount at least 10% higher than the purified feedstock for renewable hydrocarbon before mixing;- the combined feed in step (c) having a free fatty acid content of 10-70 wt%.

11. Process according to any one of claims 1-10, where in step (c) the further feedstock for renewable hydrocarbon production contains more than 50 wt% of free fatty acids, such as more than 50 wt% of C and / or Cis free fatty acids.

12. Process according to any one of claims 1-11 , where in step (c) the extraction agent comprising free fatty acids and / or triglycerides, having less than 10 w- ppm metals, less than 10 w-ppm phosphorus comprises C and / or Cis fatty acids and is selected from one or more of: palm oil mill effluent (POME), used cooking oil, animal fat, yellow grease, brown grease, soapstock acid oil, or tall oil, algae oil (AO), and oils from regenerative agriculture.

13. Process according to any one of claims 1-12, where the aqueous wastewater phase comprising C2-C6 aliphatic oxygenates referred to in step (b) has one or more of:- a COD value of 1000 mg O / l or more, such as 20000 mg O / l or more;- the sum of C2-C6 carboxylic acids in the range of 1000-20000 mg / kg.

14. Process according to any one of claims 1 -13, where the extraction in step (d) is performed as a liquid-liquid extraction at a temperature range of 20-280 °C.P-23039 / P466618PC0044 / 4415. Process according to any one of claims 1 -14, where the extraction in step (d) is performed as a liquid-liquid extraction at a temperature range of 50-95 °C, such as 55-85 °C.

16. Process according to any one of claims 1 -15, where in step d) the feedstock for renewable hydrocarbon production comprising free fatty acids and / or triglycerides, having less than 10 w-ppm metals, less than 10 w-ppm phosphorus, where the w-ppm is calculated based on the further feedstock for renewable hydrocarbon production, may be or comprise at least part of the purified feedstock formed in step b).

17. Process according to any one of claims 1 -16, where at least 70% of the feedstock for renewable hydrocarbon production referred to in step (a) is free fatty acids and / or triglycerides.

18. Process according to any one of claims 1-17, where at least 50% of the free fatty acids in the feedstock for renewable hydrocarbon production referred to in step (a) is fatty acids having a carbon number of C12-C24.

19. Process according to any one of claims 1 -18, where the feedstock for renewable hydrocarbon production referred to in step (a) is free of solid cellulosic biomass.

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