Working and recycling process of plants of the picea family or other varieties, and products obtained therefrom

Abstract

The invention relates to a process for processing twigs, foliage and similar plant parts for the extraction of essential oils (OE), in which a comminuted mass is subjected to a steam stream that is subsequently condensed for the extraction of an essential oil (EO) and a hydrolate (ID). The biomass (BM) is then subjected to a biodigestion phase for the production of methane and biogas; lignin and biographite are then extracted from the resulting biodigestate. The process of the invention allows a high degree of raw material reuse, reducing waste and achieving a high yield in biogas and lignin production.

Description

[0001] Patent description for an industrial invention with the title

[0002] "Working and recycling process of plants of the Picea family or other varieties, and products obtained therefrom "

[0003] Owner: Calanca Swiss Herbs (Svizzera)

[0004] Filed on No.

[0005] Designated Inventors:

[0006] DESCRIPTION

[0007] The invention relates, in a general sense, to the recycling of tree-cutting residues in woods and forests.

[0008] The cutting of trees considered above is commonly carried out for the maintenance of wood and forest regions, or for the procurement of timber for industrial production, such as furniture, construction products (e.g. planks, beams, laths, etc.), but also products for the chemical, pharmaceutical or other applications.

[0009] After tree cutting operations in woods and forests, the trunks of the trees are separated from the branches, foliage and other parts of the plant other than the stem; these are reused in different ways, depending on their variety and intended uses, also depending on the vegetal variety of the cut plant.

[0010] Without overburdening this description with explanations of the many possible uses of branches and waste from tree cutting (e.g. pellets, firewood, charcoal, etc.), herein the focus will be put on their use for the production of essential oils or other extracted compounds, which can be used in cosmetics, pharmaceuticals, chemicals or other industrial fields. For this reason, the present invention relates in particular to the processing and recycling of cut residues of plants of the Picea species (i.e. Picea or Pinaceae), or in any case of varieties from which essential oils can be extracted as will be shown below.

[0011] In this context, the most relevant current state of the art can be well represented by what is described in the international patent application, published as WO2016 / 029332 (under the name Borea Inc. Quebec). This document discloses a process to produce essential oils from a biomass of Picea mariana plants, i.e. a variety of spruce or pine tree that is native and widespread mainly in North America, from the United States to Canada.

[0012] Biomass is made up of plant parts such as twigs, foliage, branches, trunks and bark, whilst some methods are known to extract essential oils, whose active ingredients are most concentrated in the needle-like leaves; a method called Clevenger is used to extract them in the laboratory but it is not suitable for large quantities.

[0013] Steam distillation or supercritical CO2 extraction methods are used for this purpose.

[0014] The essences and active substances are not only present in the needle-like foliage of the plants, but also in the branches and bark, so that these parts of the plants also undergo the known extraction processes. This generates some critical issues in the production cycle from a logistical point of view, because if the time between the cutting of the plants and the extraction of the substances is long, the volatile substances tend to disperse and there can be losses in the yield of the process of up to 50 %.

[0015] This situation is exacerbated in the case of higher temperatures during the summer months; it can pose problems with regard to the selling prices of the final product, which are subject to seasonal variations, as well as having time-varying features, including product quality.

[0016] The need is therefore felt for a new extraction and production process of essential oils from high quantities of biomass deriving from the cutting of black spruce. Similarly, there is a need to obtain high grade essential oils and hydrolates, as well as suitable apparatus and processes for their production According to the disclosure of WO2016 / 029332, the process of extracting a conifer essential oil from tree branch biomass involves: a) a phase of separating the branches from trunks of coniferous trees, carried out in situ; b) a crushing phase ("chipping") of the material to obtain a coarse coniferous wood chip, by loading it onto a self-propelled machine; c) a phase to extract the essential conifer oil by subjecting the branches and other raw material to steam, with sufficient pressure and temperature for the time needed to extract the essential oil.

[0017] The crushing phase may concern not only the leaves but also the branches and bark of coniferous plants. There exist also several options and variants with regard to the type and size of the chipped material, as well as of the processing temperatures and pressures of the steam.

[0018] Extraction can be done in an extractor apparatus where a generator provides the necessary steam, while a controller regulates the steam pressure and temperature; the apparatus also includes a self-propelled equipment and condenser to condense the steam and a separator to decant the essential oil from the hydrosol.

[0019] The process can generate a large amount of waste that has to be disposed of.

[0020] To this end, as an alternative to the dump disposal of dry waste normally carried out in urban or forest areas, document WO2016 / 029332 points to the transformation of the steam-moistened material into biomass or pellet form, which can be used in a separate power generation apparatus to produce steam for use in the process.

[0021] The other residues of the process described in WO2016 / 029332, such as hydrosols and waste substances from the separation of essential oils, are disposed of in a known manner (i.e. sent to the dump) without being reused, although studies are reportedly underway for applications in agriculture as fungicides, pesticides, antimicrobials or others. To the applicants’ knowledge, the state of the art outlined in application WO2016 / 029332 can be considered as the best that can be found on an industrial level in the processes of extracting essential oils from pine trees or other plant varieties (e.g. laurel, eucalyptus, cedar, bergamot, lavender, etc.).

[0022] However, although WO2016 / 029332 shows that it is known to reuse some of the waste from the processing of pine trees, it does not appear that this is done effectively in the process and in the results. In the case of branches and other residues steamed for the extraction of essential oils, the resulting biomass is subsequently burnt to provide heat that is used to generate the cycle steam.

[0023] It is easy to understand that ashes are formed from the combustion of biomass and it is not clear what is done with them, but it seems safe to assume that they are disposed of as waste with the contraindications that may follow.

[0024] The same applies to hydrolates or hydrosols, i.e. colloidal fluids obtained as a result of the separation of essential oils by steam treatment of chipped twigs, whose dispersant phase consists of water; in WO2016 / 029332 nothing is explained about the characteristics of this fluid, nor how it is obtained, and its possible subsequent reuse is only theoretical.

[0025] As a conclusion it can be stated that, in general, the processes for producing essential oils from plant biomass known from W02016 / 029332 cannot be considered environmentally sustainable, because the reuse or any recycled materials and by-products remain limited since they only concern a fraction of the process (i.e. the biomass for combustion), and are incomplete as certain by-products generated throughout the process remain unused.

[0026] In the light of the foregoing discussion, there exists an urgent need to overcome the limitations highlighted by the current state of the art, relating to processes for the production of essential oils from plant biomasses, such as branches or residues from the cutting of pine trees and the like.

[0027] On the basis of this assumption, it can therefore be stated that the technical problem underlying the Present invention is to develop a method for processing branches or parts of plants from which essential oils are extracted which enables other products and / or by-products such as hydrolates and others to be obtained in addition to the latter, so as to achieve an almost total or at least very high reuse of the original biomass.

[0028] The idea of solving this problem lies in identifying new processing stages of the process, such as separation, transformation, conservation and others, to which the biomass is subjected during the work cycle, in order to obtain new products and / or by-products that improve the performance of the process as a whole.

[0029] For example, in the context of the process according to the invention, the hydrolate obtained by separating the essential oils from the condensed fluid at the end of the extraction step has a surprisingly high concentration of certain compounds belonging to the terpene family, such as 1-8 Cineol and Borneol.

[0030] Thanks to extensive studies and research by the applicants, it has emerged that these molecules are surprisingly effective in the field of insect or pest control in agriculture, and being natural, they pose no risks to humans or the environment.

[0031] Further, in the process of the invention, the biomass obtained after extraction of the essential oils were found to have a surprising methanogenic potential.

[0032] In fact, the applicants discovered that steam coming into contact with biomass is able to defiber the hardest part of the wood and the hardest parts of the biomass, weakening it and thus, making it attackable by bacteria in an operational biodigestion step of the invention's process.

[0033] In accordance with a preferred form, the resulting biodigestate is then further processed to obtain lignin. The latter can be advantageously used in industry for the production of chemicals, construction, paper, biofuels and other products.

[0034] As a result, at the end of the various operational steps of the process according to the invention, various products and by-products are obtained which allow a high reuse of the initial biomass, minimizing the waste material to be disposed of at the end. The features of the invention are more specifically set out in the claims appended to this description.

[0035] These features and the invention as a whole, with its effects and advantages, will better result from the explanation set forth below of a preferred and non-exclusive example of its realization, shown with reference to the accompanying drawings and diagrams in which:

[0036] Fig. 1 is a block diagram illustrating the process according to an embodiment of the invention;

[0037] Fig. 2 is a block diagram illustrating an apparatus for implementing the process according to the invention;

[0038] Fig. 3 shows some parts of the apparatus of the previous figure in more detail;

[0039] Fig. 4 and 5 show graphs of a chromatographic analysis of a laurel (Laurus Nobilis) essential oil and hydrolate respectively, obtained through the process according to the invention;

[0040] Fig. 6 and 7 show graphs of the chromatographic analysis of a fir (Picea Abies) essential oil and hydrolate, respectively, obtained through the process according to the invention;

[0041] Fig. 8 shows two graphs showing the time pattern of cumulative production and of methane production rate from a biomass obtained by the process according to the invention;

[0042] Fig. 9 shows the graph of the time pattern of the degradability of a biomass obtained by the process according to the invention.

[0043] With reference to the above-mentioned figures, therein the literal reference I indicates as a whole an industrial apparatus for carrying out the process according to the invention.

[0044] Although such an apparatus is shown schematically in Figure 2 as an apparatus physically arranged in a single location, in reality its components may also be separated from each other and arranged in different locations to implement some of the process steps, as will become clear later. Therefore, in the following, for the sake of convenience, reference will be made to the schematic configuration of figure 2, which shows the various components in close proximity, but this should not be understood in a limiting way; the system and the various process steps can therefore also be implemented separately in time and space, i.e. at different times and places, depending on the chosen method of implementation.

[0045] Further, in this connection it should be pointed out that within this description, the reference to "a form of implementation", "a form of realization", "a variant of implementation" and other similar expressions, indicates that a particular configuration, structure, action, operational phase or other feature, is included in at least one example of the invention.

[0046] Thus, such expressions found in different parts within this description indicate elements that are not necessarily all referable to the same embodiment or realization form of the invention.

[0047] Moreover, persons skilled in the art know that particular configurations, structures or features considered herein, can be combined in a number of appropriate ways to achieve the explained results of the invention.

[0048] Finally, in accordance with established practice in the patent field, numerical or literal references used in drawings serve only for clarity and do not limit the scope of protection or the gist of the invention.

[0049] Having regard to this foreword, apparatus I comprises a first part or section 1 for the extraction of essential oils, a second part or section 2 for the production of methane, and a third part or section 3 for the extraction of lignin.

[0050] Beginning with the first part or section 1, the latter comprises an extraction chamber or vessel 10 which is essentially a container, preferably metal although it could be of other appropriate material, into which the Biomass BM to be treated is introduced.

[0051] The latter is preferably prepared in shredded form (so-called 'wood chips'), although the type or size of the components, i.e. twigs, leaves, fruits (i.e. pine cones, berries or the like) etc., may depend on various factors such as the plant variety being processed, the quantity of biomass to be processed and others.

[0052] The chamber 10 comprises a main body 11 that is cylindrical and sealed by a lid 12; to this end, the lid 12 is provided with appropriate means of closure 13, such as lever closures like those schematically shown in Fig. 3, although other solutions are possible, depending on the shape and / or size of the chamber 10.

[0053] Thus, for example, it will be possible to have hatches or manholes in place of a lid 12 that closes the entire mouth of body 11, as well as handwheels, bolts or other equivalent means to secure the closure of a lid 12. The latter may also be removable or hinged to the body 11, depending on the requirements or design choices made by those skilled in the art.

[0054] Regardless of the configuration of the body 11, lid 12 or closing means 13 adopted, in a preferred form of the invention the extraction chamber 10 can be maintained in the sealed condition, for periods of time even in the order of weeks or months, for the reasons that will be better understood below.

[0055] Further, according to another preferred embodiment, the extraction chamber 10 may be replaced with a similar one, to be removed and placed in a storehouse, warehouse or similar facility, to be stored for the periods of time mentioned above.

[0056] The extraction chamber 10 is equipped with valves 14, 15 respectively for steam inlet and outlet inside it, for the treatment of Biomass BM; valves 14, 15 shown schematically in Fig. 3 are manually operated valves that allow the steam flow to be intercepted, blocking it or leaving it open.

[0057] Valves 14, 15 may be of any appropriate type, even different from each other, depending on the design choices and the apparatus I in which they are to operate.

[0058] Thus, there can be simple valves or valves with two or more ways, non-return or ball valves, diaphragm or piston valves, solenoid valves or pneumatic valves, servo-operated or manual, and other types.

[0059] However, although for simplicity's sake only two valves 14, 15 are shown in the diagram in Fig. 3, there may be others in the extraction chamber 10, not necessarily traversed by steam, but they could be safety valves or something else.

[0060] The first section 1 of apparatus I also includes a steam generator 16, which can be in fluid communication with chamber 10 via a conduit 17 connected to valve 14; the steam fed into chamber 10 meets biomass BM and exits chamber 10 from the second valve 15, to flow along an outlet conduit 18 to a condenser 19 downstream.

[0061] The condensed process fluid then flows by gravity into a mass separator 20 that separates the essential oils OE from the hydrolate ID; the separated products are finally sent to the respective storage tanks (not shown in the drawings).

[0062] In this circumstance, it should be noted that according to one of the applicants' solutions, the flow rate of cooling water to the condenser 19 varies depending on its temperature at the condenser inlet, ranging between 200 litres / hour and 1000 litres / hour per 1 cubic metre of treated BM matter.

[0063] As the cubic metres increase, the cooling water flow rate will increase proportionally.

[0064] In such a case, the process can provide for two additional thermal energy recovery phases:

[0065] - The outgoing water is re-routed within an exchanger to pre-heat the water destined for steam generator 16, in order to reduce consumption (this situation is depicted with dotted lines in figure 3).

[0066] - The cooling water is conveyed into an exchanger placed under vacuum conditions (i.e. pressure below atmospheric) to minimize pressure losses.

[0067] Here, water flow is reduced to a minimum, and thanks to the low pressure in the heat exchanger, the cooling water comes back to boil between 80°C and 98°C.

[0068] It is then mixed with a small amount of steam produced by the boiler and fed back into the feed system of Extractor 1. This approach allows for reduced waste and considerable energy recovery once the system is started up. The second part or section 2 of Apparatus I is intended for the biodigestion of Biomass BM from which essential oils OE are extracted.

[0069] Stewed biomass, i.e. obtained at the end of the extraction phase of the essential oils with steam, can be subjected to biodigestion just after cooling, or after a longer period of time (weeks or months) as mentioned above.

[0070] In accordance with a preferred form of the invention, biodigestion is carried out in the same extraction chamber 10 where the first steam treatment step was performed: this means that the Biomass BM does not have to be moved from the chamber, thus eliminating possible process downtime.

[0071] Additionally, if the biodigestion is carried out after a long time since oil extraction, an inert gas such as nitrogen, argon, helium, neon or mixtures thereof is fed into chamber 10 to protect the Biomass BM from oxidation or other biochemical reactions that may impair or otherwise reduce its methanogenic potential. Storage under inert conditions in chamber 10 is ensured by sealing body 11 with lid 12 (or other elements as explained above); in this context also the valves 14, 15 must ensure the necessary tightness to maintain the sealed storage conditions for the Biomass BM in chamber 10.

[0072] For biogas production, an inoculation of micro-organisms is carried out, as will be discussed in more detail below; this inoculation preferably occurs after the evacuation of any inert gas present in chamber 10 has been carried out.

[0073] At this stage of the process, chamber 10 operates as a reactor in which biodigestion takes place; it should be noted, however, that the tightness ensured by chamber 10 allows the conditions necessary for biodigestion to take place and to be maintained within it, while the biogas generated can still be evacuated by valves 14, 15 or possibly by other valves, which are in any case not connected to ducts 17, 18.

[0074] More generally, for biodigestion and biogas production, chamber 10 is operationally connected with a biogas storage gasometer 23 and for this purpose is preferably placed in a different part of apparatus I with respect to that for the extraction phase of essential oils. In particular, biogas production can take place at a different location than oil production; for example, another area of the same industrial apparatus, or another location where chambers 10 with Biomass BM them can be transported for biogas production.

[0075] Similar considerations apply to the third section or part 3 of apparatus I, where the anaerobic digestate originating from the previous phase can be used for the production of of lignin or other industrial products.

[0076] The biodigestate is therefore removed from chamber 10 and sent for further processing, which occurs differently depending on the final product.

[0077] From an operational point of view, the process steps according to the invention are schematically illustrated in Figure 1 and explained below.

[0078] Sub-process I: Extraction of essential oils

[0079] This first part of the processing cycle can be broken down into a series of steps:

[0080] 1. Preparation of the raw material: The first process step is the so-called chipping (i.e. crushing) of the waste from the cutting of trees, branches, etc. The forest cutting residues of the plant families indicated above are cut (chipped) into small pieces and placed in chamber 10, which preferably consists of a stainless-steel container.

[0081] 2. Steam generation: the chamber or vessel 10 is connected to a steam boiler that injects steam at a specific pressure.

[0082] In particular, chamber 10 works with an extraction temperature between 85 °C and 110 °C, while the operating pressure varies from 0.5 to 5 bar during extraction.

[0083] Advantageously, the system recovers percolated water from the mineral-rich organic matter, thanks to the concave or cylindrical bottom of the chamber 10. The steam is conveyed into the condenser 19, where the cooling temperature increases from 4 °C to 26 °C after heat exchange with steam. For condenser 19, any exchanger suitable for the purpose can be used; however, for this application, the choice fell advantageously on a specific twisted tube bundle exchanger configuration, in order to optimize space and performance.

[0084] 3. Essential oil extraction: steam coming into contact with the raw material (the biomass BM) causes the essential oil to evaporate. The steam and essential oil are directed through a duct 18 (preferably stainless) and passed through the condenser 19. The condenser cools the steam, which condenses into water and essential oil. The essential oil floats on the surface of the water and is collected in a separate container.

[0085] 4. Separation of oil and water: Once the essential oil has been collected, it is purified by separating it from the residual water. This is done using a special mass difference separator, which allows the essential oil to be separated from the water. This operation not only allows a high-quality essential oil to be obtained, but also makes it possible to retrieve a significant amount of the active ingredients presents in the essential oil, such as 1-8 Cineol and Borneol.

[0086] Indeed, through laboratory analyses carried out, the applicants found surprisingly high percentages of these molecules in the hydrolate; in particular in the order of 46 %, corresponding to a quantity by weight of 200-350 mg / L of 1-8 Cineol in the essential oil extracted from the hydrolate obtained from the laurel variety (Laurus Nobilis).

[0087] In other words, the applicants realized in an original way that the by-product of the main extraction process of essential oils, i.e. hydrolate ID, is itself an unexpected rich fluid of essential substances that can be advantageously extracted in the form of an additional oil, separable by density from the rest of the hydrolate.

[0088] In the case of the above-mentioned laurel, from the tests carried out, the applicants were able to note that this secondary oil derived from the hydrolate ID, in addition to 1-8 Cineol in a high quantity (200-350 mg / L) also contains Borneol (approx. 10 to 15 mg / L), which was instead absent in the main essential oil

[0089] OE, Le. that obtained by steam extraction from the biomass BM. In this connection, the applicants therefore realized in a new and original way, that by controlling during the essential oil extraction process the time pattern of the steam temperature in the condensation phase, it is possible to ensure that certain compounds or molecules extracted from the Biomass BM remain dissolved in the essential oil OE or hydrolate ID obtained at the end of the process, or to vary their respective amounts inside them.

[0090] This is the case, for example, with Borneol, which has been found in the Hydrolate ID obtained from laurel but is absent in the essential oil OE.

[0091] By varying the cooling curve of the steam of the vapor during its condensation, a different proportion of 1-8 Cineol and Borneol could be obtained.

[0092] It should be noted that this result is important as it allows compounds or molecules to be obtained without having to add catalysts, solvents or other additives to the vapor that could contaminate the essential oil OE and hydrolate ID.

[0093] Similar conclusions can be extended to fir (Picea Abies), for which interesting results were obtained with the process of the present invention.

[0094] Indeed, a derivative oil containing 17.83 % 1-8 Cineol (equivalent to 43.68 mg / L) and 14.35 % Borneol (35.25 mg / L) was separated from the fir hydrolate ID.

[0095] In the main essential oil OE, on the other hand, percentages of 7.84 % 18 Cineol and 1.1 %

[0096] Borneol were found. Here too, the values of the compounds and molecules and their distribution within essential oil OE and hydrolate ID can be adjusted by acting on the temperature drop curve of the condensing vapor, during the separation process I.

[0097] These experimental results are illustrated by the graphs in Figures 4 to 7, which show the values detected by spectroscopic analysis of laboratory samples obtained using the process described. In this context, it should be noted that the gas chromatographic analyses to detect the compositions of essential oils and hydrolates were carried out in a third-party laboratory, on the basis of established international practice and standards.

[0098] The method involved a double gas chromatographic (GC) analysis comprising injection of essential oil extract OE plus direct injection of hydrolate ID; the sample preparation for injection of extracted essential oil OE included extraction by hexane after decanting and then concentration, whereas no preparation was performed for the direct injection of the hydrolate.

[0099] The acquisition method (in a polar VF-Wax column) used for the injection of extracted essential oil OE was 2SHYD N, while for the hydrolate ID it was 20S R; for the injection of essential oil OE, the investigating criterion of the 80 major compounds has been followed, while for the hydrolate there were used ethanol, methanol, acetone and the 5 other major compounds.

[0100] Referring to the parameters LOD (Limit Of Detection) and LOQ (Limit Of Quantification) normally used to indicate the significance of the presence of an element, where LOD is defined as the minimum concentration of an analyte that can be distinguished from a background signal with a certain degree of statistical certainty, while LOQ is the minimum concentration at which the analyte can be quantified with acceptable precision, from the analyses performed it can be stated that in the hydrolate ID obtained from the process according to invention, the concentrations of Borneol and 1-8 Cineol are relevant.

[0101] Further tests on anonymized samples from the same batch of hydrolate confirmed the results, with the presence of Borneol at 57.59 mg / L and 1,8-Cineol at 44.65 mg / L.

[0102] As is well known, LOD and LOQ levels for gas chromatography (GC) depend on the specific methodology and matrix analyzed, but are typically in the order of a few pg / L or ng / L, much lower than the values observed for Borneol and 1,8-Cineol of the present invention.

[0103] In fact, based on the commonly recognized definitions in the prior art (see among many documents the European Union Joint Research Council's 'Guidance Document on the estimation of LOD and LOQ for measurements in the field of contaminants in feed and food' or David A. Ambruster, Terry Pry 'Limit of Blank, Limit of Detection and Limit of Quantification’, Clinical Biochemist Review 29 / 08 / 2008), a substance is considered to be present in 'trace' form if its concentration is close to the LOD.

[0104] Since, in the extraction process according to the invention, the concentrations of Borneol and 1,8- Cineol in the hydro late were found to be in the order of several tens of mg / L (ranging from about 10-20 mg / L to 44.65 mg / L and up to 300-350 mg / L) depending on the plant varieties concerned (fir, spruce, laurel, etc.), they far exceed the typical LOD and LOQ levels, so that these compounds cannot be considered mere 'traces'.

[0105] 5. Storage of the extracts: The resulting products, i.e. essential oil OE and hydrolate ID, are preferably stored in containers that protect the contents from light and heat, which are then sealed and stored in a cool, dry place.

[0106] Sub-process II: Biodigestion

[0107] Once the extraction of essential oils with sub-process I is complete, the Biomass BM consisting of the steam- treated material (i.e. stewed) can be advantageously used for biogas production.

[0108] In this context, the applicants observed how the extraction of mineral oils following steam treatment of Biomass BM removes undigestible substances and weakens the harder wood fibres, making the biomass more easily attacked by microorganisms (bacteria and the like) used for biodigestion.

[0109] As explained above, this processing can take place downstream of the previous extraction of essential oils, after a necessary cooling of the biomass, or separately after a long time (days, weeks or months) in which the Biomass BM can be stored in the separation chamber 10 vessel, preferably in an inert or otherwise controlled atmosphere (pressure, temperature, humidity, etc.).

[0110] For this purpose, a gas such as nitrogen, argon or other noble gases or their mixtures are preferably injected into the reaction chamber 10 where the stewed Biomass BM is contained, suitable for creating an inert atmosphere that prevents oxidation of the organic material until biodigestion is to be started. Regardless of this, the Biomass BM is advantageously kept in chamber 10, which in this part of the process thus serves as a reactor for the biodigestion reaction; sub-process II can thus be schematically summarized with the following steps.

[0111] 1. Storage: Since the container (i.e. chamber 10) for anaerobic digestion is the same as for the steam separation process, the processed mass is advantageously in a sterile condition.

[0112] Therefore, by inserting an inert or similar gas that creates a neutral atmosphere in chamber 10, there is prevented or at least stopped the activation of fermentation or other biological activities in the organic matter. This allows to store the container or chamber 10 with its content inside, for any desired time interval.

[0113] 2. Reactor preparation: Before starting the process, any inert gas present in chamber 10 is extracted, which makes the environment neutral. As mentioned above, at this stage of the process, chamber 10 operates as a reactor within which the biodigestion reaction takes place under controlled anaerobic conditions.

[0114] 3. Addition of inocula: inocula are the bacteria that enable anaerobic digestion.

[0115] Commercial inocula can be used or the bacteria can be taken from a reactor already in operation. In the example herein, inocula of the agro-zootechnical digestate type were used.

[0116] The inocula are added by "spraying" them from above once the lid 12 of the reactor 10 has been lifted. The inocula percolate through the organic matter BM and arrive to a grid 22 (made of stainless steel, plastic or another material that does not damage or contaminate the reaction) preferably located at the bottom of the reactor 10.

[0117] 4. pH adjustment: the acidity or pH of the biodigestion reaction must be adjusted to ensure a favorable environment for bacterial growth. In general, the optimal pH for anaerobic digestion is preferably between 6.5 and 7.5. There can be used different products to optimize the reaction environment, such as for example acetic acid, livestock slurry, glycerin, etc. while increasing at the same time the methanogenic yield.

[0118] 5. Process monitoring: during anaerobic digestion, it is important to monitor pH, temperature and biogas production. If there are variations, the necessary corrections can be made.

[0119] 6. Biogas or biomethane collection: the biogas produced during anaerobic digestion can be collected and used as an energy source. For collection, a system of pipes and valves is used to convey the biogas to a storage gasometer, which can be used to regularly feed thermogenic processes (steam boiler), cogeneration (district heating, electricity, etc.) or 'gas-upgrading’, Le. gas refining for feeding into the grid or compression into cylinders. For this purpose, pipes, valves, tanks, condensers, activated carbon filters and other elements of a methane circuit are used, mostly different from those for steam.

[0120] 7. Digestate extraction: at the end of the anaerobic digestion process, an organic material called digestate is obtained. The digestate can be advantageously reused for various applications, e.g. as fertilizer for agricultural crops.

[0121] Digestate obtained from processing plants of the Picea family contains a high level of lignin, with all its possible applications, which will be discussed below.

[0122] 8. Reactor cleaning: once anaerobic digestion is complete, the reactor or chamber 10 is cleaned and disinfected to prepare it for a new cycle of digestion or essential oil extraction with steam, as already explained.

[0123] Figures 8 and 9 show the development over time of some parameters concerning the production of biomethane and biogas with the process of the invention.

[0124] As can be seen, the methane daily production rate has a highest point after about a week, while cumulative production over time grows fairly regular following the trend of biomass degradability.

[0125] Laboratory tests were carried out on a sample of organic matter (fir wood chips) that had previously undergone steam treatment to extract the essential oils. The following table shows the data of a laboratory test from which the diagrams were derived from

[0126] Figures 8 and 9

[0127] Reference method: UNI EN ISO 11734:2004 and UNUTS 11703:2018

[0128] Sub-process III: retrieval of lignin and other compounds The applicants observed that the biodigestate obtained from the previous treatment is still surprisingly rich in compounds and substances that can be advantageously reused: this is the case, for example, of lignin, which is present in the biodigestate of Picea plants and which can be obtained with the following steps.

[0129] 1. Pre-treatment of digestate: Anaerobic digestate is pre-treated to remove any impurities that might hinder the lignin extraction process. This may include the removal of solid particles through filtration or centrifugation.

[0130] 2. Alkaline extraction: After pre-treatment, the digestate is then subjected to an alkaline extraction process to separate the lignin from the other digestate components. In this process, the digestate is treated with a sodium hydroxide (NaOH) solution at high temperature and pressure. The NaOH solution splits the lignin from the other components of the digestate and transforms it into a soluble form.

[0131] 3. Acidification of the extraction solution: The lignin extraction solution is then acidified to cause lignin precipitation. In this process, an acid solution is added to the alkaline extraction solution. The acidification of the solution causes the lignin to separate from other compounds and precipitate as a solid.

[0132] 4. Separation and purification: The precipitated lignin is then separated from the other compounds of the solution by centrifugation or filtration. After separation, the lignin can be purified by repeated washing with water or other solvents. The end product will be pure lignin in solid form.

[0133] 5. Drying: The pure lignin is finally dried to residual moisture and obtain a dry and stable product. Drying can be carried out in a dryer at low temperature to preserve the properties of the lignin.

[0134] As is well known, lignin can have various industrial uses in the chemical sector to produce polymers for various uses (films, paints, etc.), or as a fuel to produce energy.

[0135] However, pre-treatment is often required in prior art to reduce the Sulphur content and volatiles in the wood in order to improve the properties of lignin so that it can then be used as a reinforcing filler in composites and plasticizers.

[0136] The process of the invention, in which the biomass derived from tree cutting is subjected to steam extraction of essential oils and then biodigestion to produce biogas, makes it possible to obtain lignin with an advantageous high yield since the starting biodigestate is free of unnecessary compounds and substances. From what has been stated herein before, it is possible to understand how the process according to invention solves the underlying technical problem outlined at the beginning.

[0137] Indeed, the percentage of reuse of biomass from tree cutting is high due to the fact that it is not only used for the extraction of essential oils, but also (and above all) for the production of biogas; preferably, lignin obtained from biodigestate should be added to the products obtained.

[0138] It should be noted that the overall yield of the cycle is increased by the synergistic effect resulting from the concatenation of sub-processes I, II and III, since the products obtained at the end of each of them promote their subsequent use.

[0139] Thus, as far as essential oils are concerned, they can be used in various applications from cosmetics to food, perfumes or others (depending also on the type of plant variety) while hydrolate, containing a significant amount of 1-8 Cineol and Borneol, can be advantageously used as a pesticide, fungicide or pesticide in agriculture.

[0140] The proportion between these molecules can vary from 1 :1 to 1 :10 or 10: 1.

[0141] What must be emphasized, however, is the fact that with the process according to the invention, these (or other) molecules are made available in an aqueous solution made from hydrolate ID: they can therefore be used in a simple manner without having to be modified or prepared with chemical solvents and the like, and are thus environmentally advantageous.

[0142] It should be noted that this advantageous effect does not only apply to 1-8 Cineol or Borneol considered here, but also to other molecules or compounds present in Hydrolate ID, such as terpenes, methyl eugenol, linalool, etc., which may be different from those considered in the examples referred to above; this is also a function of the different plant varieties used in the process of the invention.

[0143] As mentioned, the process of the invention teaches how to regulate the presence of certain substances in the main essential oil OE and in the hydrolate ID, by operating on the vapor temperature abatement curve in the condensation phase; this principle can be applied for different substances or compounds, so as to broaden the application of the invention.

[0144] Additionally, Biomass BM that has been steam-treated exhibits characteristics that make it more easily attacked by biodigestion microorganisms, because the wooden fibres or at least the more resistant ones, are weakened by the steam.

[0145] As a result, the biochemical methanogenic potential of the biomass is improved over that of currently known biodigestion processes, as confirmed by the laboratory results carried out.

[0146] Finally, the biodigestate obtained at the end of the second sub-process also turns out to be an advantageous intermediate product from which lignin can be obtained, as volatile substances and others (e.g. sulphurised substances) that may be present in the initial organic matter, i.e. branches, foliage and other woody parts, are eliminated during steam treatment and subsequent biodigestion phases.

[0147] It should also be noted that in the prior art, lignin is extracted from waste processing of cellulose production: it therefore contains added chemicals that do not facilitate the extraction of lignin.

[0148] In contrast, in the present invention, the biodigestate obtained at the end of sub-process II is a product with significant added value, as it is improved by the upstream removal of several substances.

[0149] All these features and advantages are encompassed by the scope of the following claims.

Claims

CLAIMS1. Working process of twigs, leaves, branches and similar plant parts for the extraction of essential oils (OE), in which a mass (BM) of twigs, leaves, branches and similar crushed parts is subjected to a steam flow which is subsequently condensed for the extraction of an essential oil (OE), characterized in that it includes a step of separating the essential oil (OE) from a hydrolate (ID) and in that the time pattern of the steam temperature during condensation is controlled, so as to control the presence in the hydrolate (ID) of selected molecules and / or compounds.2 Process according to claim 1, wherein the steam temperature is between 85 °C and 110 °C while the working pressure varies between 0.5 and 5 bar.3 Process according to claim 1 or 2, wherein the hydrolate (ID) comprises 1-8 Cineol and / or Borneol.4 Process according to any one of claims 1 to 3, wherein the hydrolate (ID) comprises 1-8 Cineol and / or Borneol in an amount by weight from about 10 to 350 mg / L.5 Process according to claim 4, wherein the hydrolate (ID) comprises 1-8 Cineol and / or Borneol in an amount by weight of 35 to 350 mg / L.6 Process according to any of the previous claims, comprising a biodigestion step of steam- treated biomass (BM) from which essential oils (EO) have been extracted, for the production of biogas and / or biomethane.

7. Process according to claim 6, wherein the biodigestion is carried out in the same reaction chamber (10) where steam treatment of the biomass for the extraction of essential oils (OE) previously took place.8 Process according to claim 6 or 7, wherein prior to biodigestion the biomass (BM) is maintained in an inert atmosphere in the reaction chamber (10) to inhibit biodigestion and / or oxidation of the biomass (BM) for a predetermined time interval.9 Process according to claim 8, comprising a step of feeding an inert gas such as nitrogen, argon, helium, neon and the like, or mixtures thereof, into the reaction chamber (10) to obtain the inert atmosphere.10 Process according to any one of claims 6 to 9, comprising a step of extracting lignin from the biodigestate obtained at the end of the biodigestion step.11 Process according to claim 10, wherein the digestate is treated with a sodium hydroxide (NaOH) solution at high temperature and pressure.12 Process according to claims 10 or 11, wherein the lignin extraction solution is then acidified to cause lignin precipitation.13 Process according to any of the preceding claims, wherein the plants from which twigs, leaves, branches and other parts to be treated are obtained, include one or more of the following varieties:Pinaceae, laurel, eucalyptus, cedar, bergamot, lavender.

14. Apparatus for implementing the process according to the preceding claims, comprising an extraction chamber (10), a steam source (16) in fluid communication with the extraction chamber (10), a condenser (19) in fluid communication with the extraction chamber (10), characterized in that the extraction chamber (10) is removable in relation to the vapor source (16) and to the condenser (19) for being taken away.

15. Apparatus according to claim 14, wherein the separation chamber (10) can be removed while maintaining it in a sealed condition with respect to the external environment.

16. Apparatus according to claims 14 or 15, comprising means for feeding an inert gas into the separation chamber (10).

17. Hydrolate (ID), biodigestate or lignin obtained by the process according to any of claims 1 to 13.

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