Integrated apparatus and process for thermochemical and mechanical pretreatment for increasing biogas production

Abstract

Disclosed, in the present disclosure, is a pretreatment technology capable of increasing the amount of biogas produced in a downstream biogas production process, and improving process efficiency compared to a conventional pretreatment method, by pretreating an organic raw material, such as biomass or organic waste, by means of integration of thermochemical treatment and mechanical grinding.

Description

Integrated apparatus and process for thermochemical and mechanical pretreatment to increase biogas production

[0001] The present disclosure relates to an integrated apparatus and process for thermochemical and mechanical pretreatment to increase biogas production. More specifically, the present disclosure relates to a pretreatment technology that can increase the amount of biogas produced in a subsequent biogas production process and improve process efficiency compared to existing pretreatment methods by pretreating organic raw materials, such as biomass and organic waste, through a method that integrates thermochemical treatment and mechanical grinding.

[0002] Korea relies on imported resources for more than 95% of its energy needs, and since the production of petroleum-based chemicals accounts for a significant portion of the national economy, it is necessary to make the most of available renewable resources to secure stable energy sources in the future and to meet the increasingly stringent global demand for carbon reduction. In response to these national policy requirements, research is actively underway to recycle various organic waste resources that are currently discarded and to manufacture high-value-added materials from them.

[0003] A representative example of the aforementioned research is a technology for producing biogas by anaerobic digestion of low-cost organic materials such as biomass waste like sawdust, food waste, sewage sludge, animal and plant residues, and slaughterhouse waste.

[0004] Biogas is generally a gas produced using organic matter (or organic waste resources), consisting mainly of methane and carbon dioxide, and may contain small amounts of hydrogen, hydrogen sulfide, ammonia, and other gases. In particular, biogas can be produced by applying an anaerobic digestion method that decomposes organic matter under oxygen-free conditions.

[0005] Although biogas production efficiency has increased to some extent through research on the reaction mechanism and optimal reaction conditions of anaerobic digestion, it is still difficult to produce a sufficient amount of biogas, and various methods to increase biogas production are being studied. Lignocellulose-based biomass (or woody biomass), which is attracting attention as a raw material for biogas production along with organic waste discharged from various industrial and living environments, contains cellulose, hemicellulose, and / or lignin in its structure and is discharged from various agricultural and food sectors, and has diverse characteristics depending on the source.

[0006] Currently commercialized biogasification facilities primarily focus on specific organic wastes, such as food waste and sewage sludge, while the treatment of other organic wastes, particularly unused biomass, is inadequate. Unused biomass causes environmental pollution when landfilled or incinerated and contains tissues that hinder microbial digestion, leading to reduced treatment efficiency during anaerobic digestion. In particular, existing processes have been criticized for high energy consumption and a lack of flexibility in handling complex wastes. Considering these factors, there is a need for measures that can increase biogas production even when using a variety of organic materials or wastes.

[0007] As an alternative to this, various pretreatment techniques have been developed, such as hydrolysis, grinding, acid treatment, steam explosion, and supercritical ammonia treatment. Conventional pretreatment techniques involve performing one of the aforementioned pretreatments alone or combining multiple pretreatments. When combining multiple pretreatments, a typical method involves performing grinding treatment first followed by hydrolysis (or thermal hydrolysis) (e.g., Korean Patent Publication No. 2022-0074816, Japanese Patent No. 4765073, etc.). However, conventional pretreatment processes are disadvantageous in terms of reaction continuity, cause equipment complexity, or increase the number of treatment steps. Furthermore, they have low efficiency relative to the energy input, and despite involving multiple pretreatment processes, there are limitations in increasing the production volume of biogas.

[0008] In one embodiment of the present disclosure, the aim is to provide a pretreatment process and a biogas production process that can increase biogas production yield for various organic raw materials while overcoming the technical limitations pointed out in conventional pretreatment processes.

[0009] In another embodiment of the present disclosure, a pretreatment device for organic raw materials capable of increasing the production of biogas is provided.

[0010] According to the first aspect of the present disclosure,

[0011] a) a step of introducing an organic raw material containing solids into a pretreatment device integrated so that grinding by a ball mill and thermal hydrolysis are performed in a single treatment zone; and

[0012] b) a step of simultaneously performing grinding and thermal hydrolysis by processing the organic raw material under controlled conditions within the above-mentioned pretreatment device;

[0013] A pretreatment process for organic raw materials including is provided.

[0014] According to an exemplary embodiment, the content of solids in the organic raw material processed in the pretreatment device can be controlled in the range of 50 to 95 weight%.

[0015] According to an exemplary embodiment, the organic raw material may be at least one of lignocellulose-based biomass and organic waste.

[0016] According to an exemplary embodiment, step b) can be performed under conditions of a temperature controlled in the range of 100 to 240 ℃ and a rotational speed in the range of 80 to 250 rpm.

[0017] According to an exemplary embodiment, the organic raw material that has undergone step b) may have an average particle size (mean size) in the range of 20 to 36 μm, a D50 in the range of 12 to 26 μm, and a D90 in the range of 40 to 85 μm.

[0018] According to an exemplary embodiment, the volume ratio of the ball to the solid of the organic raw material within the single processing zone can be controlled in the range of 0.5 to 5:1.

[0019] According to an exemplary embodiment, in step b), the liquid-to-solid ratio (L / S, weight basis) can be controlled in the range of 0.05 to 0.3 based on the solid content of the organic raw material.

[0020] According to an exemplary embodiment, step b) is performed in a stepwise control manner including a first step, a second step, and a third step, and

[0021] At this time, the first step is performed at a rotational speed controlled within the range of 80 to 120 rpm until a processing temperature corresponding to the second step is reached, and

[0022] The above second step is performed at a rotational speed controlled within the range of 140 to 250 rpm at a temperature within a single processing zone set at a set temperature, and

[0023] The above third step can be performed at a rotational speed controlled in the range of 50 to 120 rpm while cooling to a temperature controlled in the range of 40 to 85 ℃.

[0024] According to an exemplary embodiment, the second step may be performed for a time adjusted within the range of 5 to 60 minutes.

[0025] According to the second aspect of the present disclosure,

[0026] (A) a step of introducing an organic raw material containing solids into a pretreatment device integrated so that grinding by a ball mill and thermal hydrolysis are performed in a single treatment zone; and

[0027] (B) a step of pretreating an organic raw material by treating the organic raw material under controlled conditions within the pretreatment device to simultaneously perform grinding and thermal hydrolysis; and

[0028] (C) A step of generating biogas from the pretreated organic raw material by anaerobic digestion;

[0029] A process for producing biogas from organic raw materials including is provided.

[0030] According to the third aspect of the present disclosure,

[0031] As a pretreatment device for organic raw materials containing solids,

[0032] An inner chamber partitioned to form a single processing zone accommodating both organic raw materials and multiple balls;

[0033] A cross-bar shaped rotatable impeller disposed within the inner chamber above;

[0034] A heat source that provides heat necessary for the thermal hydrolysis of organic raw materials to the inner chamber; and

[0035] A rotary drive unit connected to the above impeller and providing the driving force required for the rotation of the impeller;

[0036] Includes,

[0037] A pretreatment device is provided configured such that an organic raw material undergoes thermal hydrolysis while being crushed as a plurality of balls come into contact with and / or collide with each other according to the rotation of the cross-bar type rotatable impeller.

[0038] According to an exemplary embodiment, the pretreatment device may further include a cover positioned above the inner chamber to seal the inner chamber and, as it is separated from the inner chamber, functions as an inlet for introducing organic raw materials and a plurality of balls of a predetermined size into the inner chamber.

[0039] According to an exemplary embodiment, the cross-bar type rotatable impeller is,

[0040] A rotating shaft installed within the inner chamber; and

[0041] A plurality of cross-bars formed at predetermined intervals vertically or horizontally along the above rotation axis;

[0042] Includes,

[0043] At this time, the plurality of cross-bars rotate according to the rotation of the rotation axis, and

[0044] A plurality of balls housed in an inner chamber may be configured to come into contact with or collide with each other by means of the above-mentioned rotating crossbar.

[0045] According to an exemplary embodiment, a plurality of cross-bars formed on the rotation axis may include a first cross-bar extending in a first direction and a second cross-bar extending in a second direction.

[0046] According to an exemplary embodiment, the first cross-bar and the second cross-bar are formed alternately, and the first direction and the second direction may be mutually perpendicular directions.

[0047] According to an exemplary embodiment, the material of each of the inner chamber, the plurality of cross-bar shaped rotatable impellers, and the balls may be at least one selected from the group consisting of steel, stainless steel, ceramic, tungsten carbide, and zirconia.

[0048] According to an exemplary embodiment, the inner chamber has a cylindrical shape, and the ratio of the diameter of the ball to the diameter of the inner chamber may be in the range of 0.05 to 0.15.

[0049] According to a specific embodiment of the present disclosure, by pretreating organic raw materials using a single device in which thermochemical treatment (specifically, thermal hydrolysis) and mechanical grinding (specifically, ball milling) are performed as a single integrated process, the particle size of the organic raw materials is reduced by the ball mill while thermal hydrolysis is performed. As a result, the efficiency of thermal hydrolysis is increased, thereby increasing the production volume of biogas in a subsequent biogas production process. Furthermore, by performing multiple pretreatments in an integrated manner, pretreatment time can be reduced and process efficiency can be improved.

[0050] FIG. 1 is a flowchart of a pretreatment process according to an exemplary embodiment of the present disclosure;

[0051] FIGS. 2a and FIGS. 2b are a perspective view and a plan view, respectively, illustrating the schematic appearance of an integrated preprocessing device according to an exemplary embodiment;

[0052] FIGS. 3a and FIGS. 3b are, respectively, a cross-sectional view schematically illustrating the internal structure and operating mechanism of an integrated preprocessing device according to an exemplary embodiment, and a perspective view of a main operating unit;

[0053] FIGS. 4a to 4d are photographs respectively showing the appearance of (a, b) a cross-bar shaped impeller separated from and coupled to the inner chamber, (c) the inner chamber, and (d) a ball used for ball mill processing in an integrated pretreatment device used in an example;

[0054] FIGS. 5a to 5c are graphs showing the measurement results of (a) average particle size, (b) D50, and (c) D90 for each pretreatment process (single process, individual process, and integrated process), respectively;

[0055] FIGS. 6a and FIGS. 6b are graphs showing (a) the biogas production amount and (b) the accumulated methane production amount, respectively, in a reaction for producing biogas from a biomass sample pretreated in a single process;

[0056] FIGS. 7a and FIGS. 7b are graphs showing (a) the biogas production amount and (b) the accumulated methane production amount in a reaction for producing biogas from a biomass sample pretreated by an individual process;

[0057] FIGS. 8a and FIGS. 8b are graphs showing (a) biogas production and (b) accumulated methane production, respectively, in a reaction for producing biogas from a biomass sample pretreated by an integrated process; and

[0058] Figures 9a and 9b are graphs showing (a) the biogas production amount and (b) the accumulated methane production amount when the processing time is changed in a reaction to produce biogas using biomass processed by an integrated process, respectively.

[0059] The present invention can be fully achieved by the following description. The following description should be understood as describing preferred embodiments of the present invention, but the present invention is not necessarily limited thereto. Furthermore, the attached drawings are for illustrative purposes only and do not limit the present invention; details regarding individual components can be appropriately understood in accordance with the specific intent of the relevant descriptions provided below.

[0060] Terms used in this specification may be defined as follows.

[0061] "Biomass" can be broadly understood to mean any organic material derived from living organisms, such as plants, animals, and microorganisms.

[0062] "Lignocellulose-based biomass" may refer to plant-based biomass composed of cellulose, hemicellulose, and lignin as structural components, and may include, for example, various agricultural crops and agricultural and forestry by-products.

[0063] In a narrow sense, "organic waste" refers to waste derived from plants, animals, or other natural sources that can be decomposed into various natural chemicals, compounds, etc., through bioprocesses, and typically includes food waste and agricultural waste such as sewage sludge, human waste, livestock manure, food waste, and animal and plant residues. In a broad sense, it may include organic matter (specifically, organic matter containing solids) discharged or discarded from various living environments, commercial and / or manufacturing processes, etc.

[0064] "Thermal hydrolysis process (THP)" can broadly refer to a hydrolysis reaction performed using water or moisture under specific temperature conditions (specifically, elevated temperature conditions), and can decompose the complex structural bonds (i.e., cellulose, hemicellulose, lignin, etc.) of organic materials, particularly lignocellulose-based biomass, by applying heat.

[0065] "Ball milling" may refer to a mechanical process applied to grind, mix, and disperse solid materials into fine particles or powder form. A chamber is filled with balls, which serve as a grinding medium, and the material to be processed. As the chamber rotates, the balls mix with and collide with the filled material, allowing the material to be ground into smaller particles through impact, abrasion, and / or shear forces. By grinding organic raw materials into fine particles through this ball milling process, the surface area can be increased, which can improve the accessibility of microorganisms during the subsequent anaerobic digestion process.

[0066] "Biogas" may refer to a mixture of methane and carbon dioxide produced from biomass through anaerobic digestion (the decomposition of organic matter by microorganisms in an oxygen-deficient environment).

[0067] "Biochemical methane potential (BMP) test" may refer to a test that measures the maximum amount of methane that can be produced from organic raw materials.

[0068] "Anaerobic digestion" can refer to the process of digesting organic matter by blocking contact with oxygen and through the action of enzymes secreted by anaerobic bacteria.

[0069] Where a numeric range is specified in this specification as a lower limit and / or an upper limit, it may be understood that any sub-combination within said numeric range is also disclosed. For example, where "1 to 5" is written, it may include 1, 2, 3, 4 and 5, as well as any sub-combination between them.

[0070] When a component is said to "include," it means that, unless otherwise noted, it may include additional components.

[0071] In the case of the term "contact," in a narrow sense it means direct contact between two objects, but in a broad sense it can be understood as allowing any additional component to be involved.

[0072] The expressions "on" and "above" are used to refer to concepts of relative position, where not only are other components or layers directly present on the mentioned layer, but other layers (intermediate layers) or components may be interposed or present between them. Similarly, the expressions "below," "in the lower part," and "below," as well as the expression "between," can also be understood as concepts relative to position.

[0073]

[0074] Pretreatment process of organic raw materials

[0075] According to one embodiment of the present disclosure, for organic raw materials, specifically organic raw materials containing solids, thermochemical treatment (e.g., thermal hydrolysis) and mechanical grinding (e.g., ball milling) are performed simultaneously within a single treatment zone, thereby increasing the biogas production during the subsequent biogas production process by microorganisms. In this regard, a flowchart of a pretreatment process according to an exemplary embodiment is shown in FIG. 1.

[0076] Referring to the drawings above, organic raw materials containing solids are first introduced into a pretreatment device. At this time, the pretreatment device is equipped with a single processing zone capable of simultaneously performing ball milling and thermal hydrolysis. Balls used for grinding, specifically multiple balls, can be introduced into the pretreatment device (specifically the single processing zone) simultaneously (together) or sequentially with the organic raw materials. However, as shown in the illustrated embodiment, introducing the organic raw materials and balls together into the pretreatment device may be advantageous in terms of efficient processing and uniform grinding effects. Additionally, the single processing zone may provide a sealed space.

[0077] According to an exemplary embodiment, the organic raw material may be at least one selected from lignocellulosic biomass, organic waste, etc. Examples of such lignocellulosic biomass include hardwood, softwood, sugarcane bagasse, sugarcane straw, corn stalks, corn fiber, etc. In addition, various lignocellulosic biomass known in the art, such as rice straw, wheat straw, bamboo, sawdust, chips, rice husks, hay, tree bark, driftwood, etc., may be applied. Furthermore, one or more of the types exemplified above may be used in combination. Meanwhile, the organic waste may be, for example, sludge, livestock manure, agricultural waste, municipal waste, etc., and may contain lignocellulosic components (i.e., cellulose, hemicellulose, and / or lignin) on its own, or may contain lignocellulosic components when combined with the aforementioned lignocellulosic biomass.

[0078] According to an exemplary embodiment, in the case of an organic raw material (i.e., a material to be processed within a single processing zone) processed within a pretreatment device, the content of solids (solids) may be controlled so as to be appropriately maintained to enable efficient thermal hydrolysis and ball mill grinding processes. For example, the solid content in the raw material may be in the range of, for example, about 50 to 95 weight%, specifically about 60 to 93 weight%, more specifically about 70 to 92 weight%, and particularly specifically about 80 to 91 weight%.

[0079] In addition, ball mills for grinding organic raw materials to a predetermined level can be selected from techniques known in the industry, such as electric ball mills, vibrating ball mills, planetary ball mills, etc.

[0080] According to one embodiment, the ball mill may be operated in such a manner that a plurality of balls introduced into a single processing zone within a pretreatment device come into contact with and / or collide with each other by rotation, thereby crushing organic raw materials introduced together. In this case, the material of the plurality of balls introduced into the pretreatment device is not particularly limited as long as it can crush the organic raw materials to a desired degree. However, the material of the balls may be at least one selected from, for example, steel, stainless steel, ceramic, tungsten carbide, zirconia, etc., and in a specific embodiment, stainless steel, more specifically SUS 316L, may be used.

[0081] In exemplary embodiments, the plurality of balls used for ball mill grinding may have different sizes (or diameters), but balls of the same diameter may be used for uniform grinding. In this regard, the diameter of each of the plurality of balls may be determined, for example, in a range of about 10 to 50 mm, specifically about 12 to 40 mm, more specifically about 15 to 35 mm, and particularly specifically about 18 to 25 mm, but may vary depending on the scale of the pretreatment device, as described below.

[0082] Referring again to FIG. 1, stirring conditions are formed inside the pretreatment device by a rotating means, and at this time, a plurality of balls come into contact or collide with each other to crush organic raw materials, and thermal hydrolysis is performed simultaneously. If necessary, an appropriate amount of water may be supplied separately, or / or an appropriate amount of water may be introduced into the pretreatment device together with the introduction of organic raw materials. In addition, the pretreatment device induces thermal hydrolysis to occur along with the crushing of organic raw materials by a ball mill by heating the inside of the treatment zone. As an example, the type of heat source (i.e., internal heat source) may be an electric heater (e.g., electric band heater, electric coil type heater, etc.), steam injection (e.g., multi-point steam injection), microwave irradiation, etc., and may also be a direct heating or indirect heating method.

[0083] According to exemplary embodiments, the temperature within the treatment zone (i.e., the pretreatment temperature) can alter the properties of the organic raw material to be treated, thereby affecting productivity during the subsequent process of biogas production following the pretreatment step. In this regard, if the pretreatment temperature is excessively high or low, the organic material being treated may be converted into a non-degradable substance, or a decrease in microbial activity may occur during the subsequent biogas production process. Taking this into consideration, the pretreatment temperature may be controlled within a range of, for example, about 100 to 240°C, specifically about 100 to 220°C, more specifically about 100 to 180°C, and particularly specifically about 100 to 140°C. According to specific embodiments, the pretreatment temperature may be controlled within a range of, for example, about 100 to 130°C, specifically about 100 to 120°C. However, the pretreatment temperature is not limited to the aforementioned range and may vary depending on the type, composition, and properties of the organic raw material, as well as the properties of the organic raw material suitable for the subsequent biogas production stage.

[0084] In addition, the pretreatment can be performed under atmospheric pressure or boosted pressure conditions to improve the solubilization of organic matter and reaction efficiency, for example, in a range of about 1 to 9.5 atmospheres, specifically about 1.5 to 8.5 atmospheres, and more specifically about 2 to 7.5 atmospheres.

[0085] Meanwhile, ball mill grinding involves the rotation of a stirring means, and the rotation speed can be adjusted considering the desired particle size and the degree of homogenization of the organic material. As an example, the rotation speed of the ball mill grinding process can be performed under conditions of a rotation speed in the range of, for example, about 80 to 250 rpm, specifically about 90 to 230 rpm, more specifically about 95 to 210 rpm, and particularly specifically about 100 to 200 rpm.

[0086] According to exemplary embodiments, it may be advantageous to process an appropriate amount of organic raw material when thermal hydrolysis and ball mill grinding are performed simultaneously. As an example, the volume ratio of the total balls to the solids of the organic raw material within the processing zone of the pretreatment device can be adjusted to ensure uniform grinding and optimal energy efficiency, for example, in a range of about 0.5 to 5:1, specifically about 0.6 to 4:1, more specifically about 0.7 to 3:1, particularly specifically about 0.8 to 2:1, and in a specific embodiment, in a range of about 0.9 to 1.1:1, specifically about 1:1.

[0087] According to an exemplary embodiment, as thermal hydrolysis is performed along with ball mill grinding, it is necessary to have an appropriate amount of moisture in the organic raw material introduced into the treatment zone. In this regard, the amount of moisture can be controlled within a range of liquid-to-saturation ratios (L / S, based on weight) based on the solid content of the organic raw material during pretreatment, for example, about 0.05 to 0.3, specifically about 0.07 to 0.2, more specifically about 0.08 to 0.15, and particularly specifically about 0.09 to 0.12. In this regard, since the treatment effect may be negligible or process efficiency may be reduced due to an increase in the volume of the treated material if the amount of moisture is excessively low or high, it may be advantageous to control it within the aforementioned liquid-to-saturation ratio range, but it is not limited thereto as it can be changed depending on the characteristics of the organic raw material, etc.

[0088] According to an exemplary embodiment, preprocessing can be performed using a stepwise control method of rotational speed. In this case, the stepwise control may largely include a first stage, which is an initial (start) stage; a second stage, which is a steady state; and a third stage, which is a termination stage.

[0089] In this regard, the first step may refer to a period until a temperature corresponding to the subsequent second step (i.e., the pretreatment temperature of the organic raw material) is reached, at which time the rotational speed may be controlled, for example, in the range of about 80 to 120 rpm, specifically about 85 to 115 rpm, more specifically about 90 to 110 rpm, and particularly specifically about 95 to 105 rpm. The reason for setting the rotational speed range to a relatively low range is that if excessive mechanical energy is introduced initially under conditions where thermal hydrolysis is not sufficiently carried out, it may be difficult to achieve a desirable integrated pretreatment effect. Furthermore, in an exemplary embodiment, the first step may be performed over a range of, for example, about 30 to 90 minutes, specifically about 40 to 80 minutes, more specifically about 50 to 70 minutes, and particularly specifically about 60 to 75 minutes, but this should be understood as being for illustrative purposes.

[0090] In the second stage, as the temperature inside the treatment zone reaches the aforementioned pretreatment temperature, the rotational speed for ball mill grinding may be increased. The reason for increasing the rotational speed in this way is to ensure more effective homogeneous grinding at the treatment temperature, thereby reducing particle size and improving the solubility of organic matter. As an example, the rotational speed of the second stage may be controlled in a range of, for example, about 140 to 250 rpm, specifically about 150 to 230 rpm, more specifically about 170 to 220 rpm, and particularly specifically about 190 to 210 rpm. Additionally, since processing for an excessive amount of time in the second stage may have a detrimental effect on biogas production, it may be advantageous to set an appropriate time range. As an example, the treatment step of the second stage may be performed over a range of, for example, about 5 to 60 minutes, specifically about 8 to 30 minutes, more specifically about 10 to 25 minutes, and particularly specifically about 12 to 20 minutes. However, as the processing time may vary depending on the particle size, moisture content, organic composition, processing temperature, reaction pressure, etc. of the organic raw material, the aforementioned range may be understood as illustrative.

[0091] Meanwhile, in the third step, after the pretreatment performed during the second step is completed, the rotation speed is reduced to prevent excessive reaction. In this regard, the third step may be cooled to a temperature controlled in the range of, for example, about 40 to 85°C, specifically about 50 to 80°C, more specifically about 60 to 75°C. At this time, the rotation speed may be controlled in the range of, for example, about 50 to 120 rpm, specifically about 85 to 115 rpm, more specifically about 90 to 110 rpm, and particularly specifically about 95 to 100 rpm. Additionally, the third step may be performed over a range of, for example, about 10 to 80 minutes, specifically about 20 to 75 minutes, more specifically about 30 to 70 minutes, and particularly specifically about 35 to 65 minutes, but this should be understood as illustrative.

[0092] Referring again to FIG. 1, after the pretreatment is completed, gaseous components such as steam generated during the integrated (simultaneous) performance of thermal hydrolysis and ball mill grinding, and components volatilized by heating, are discharged from the pretreatment device. According to the illustrated embodiment, after the gas discharge, only the pretreated organic raw material may be discharged outside the device while the balls remain in the pretreatment device; however, alternatively, considering the difficulty of separation, both the pretreated organic raw material and the balls may be discharged outside the pretreatment device. In this case, the balls used for grinding may be separated from the organic raw material outside the device and then reintroduced into the pretreatment device as described above.

[0093] As described above, organic raw materials that have undergone integrated pretreatment are in a state suitable for the biogas production reaction (e.g., anaerobic digestion by microorganisms), which is a post-pretreatment process. Specifically, by grinding the organic raw materials into fine sizes, the surface area is increased, thereby enhancing the accessibility of microorganisms during the post-pretreatment biogas production reaction. Furthermore, by breaking down the complex structural bonds of the biomass through thermal hydrolysis and simplifying the structure of the biomass, decomposition during the biogas production reaction can be facilitated, and digestion efficiency can be improved. In particular, as thermal hydrolysis proceeds simultaneously with ball mill grinding, the organic raw materials acquire a reduced particle size, resulting in an increased cross-sectional area. Additionally, the thermal hydrolysis effect can be maximized through smooth heat mass transfer. It is important to note that this differs from conventional single thermal hydrolysis processes or sequential individual treatment methods of grinding followed by thermal hydrolysis, which generate difficult-to-decompose substances and thus limit the increase in biogas production.

[0094] According to an exemplary embodiment, the mean size of the pretreated organic raw material may be controlled in the range of, for example, about 20 to 36 μm, specifically about 22 to 33 μm, more specifically about 23 to 32 μm, and particularly specifically about 24 to 31 μm. In addition, the D50 of the pretreated organic raw material may be controlled in the range of, for example, about 12 to 26 μm, specifically about 13 to 25 μm, more specifically about 14 to 24 μm, and particularly specifically about 15 to 23 μm. Furthermore, the D90 of the pretreated organic raw material may be controlled in the range of, for example, about 40 to 85 μm, specifically about 42 to 82 μm, more specifically about 43 to 80 μm, and particularly specifically about 44 to 79 μm. As a result of undergoing integrated pretreatment in this way, the particles of the organic raw material can be dispersed into a finer and more homogeneous size, making it easier for microorganisms to access them.

[0095] According to exemplary embodiments, total chemical oxygen demand (the amount of oxygen required for the chemical oxidation of all organic and inorganic substances present in the material; T-COD) and soluble chemical oxygen demand (the amount of oxygen required for the chemical oxidation of organic and inorganic substances present in a dissolved state in the material; S-COD) can be cited as quantitative indicators of non-degradable components in pretreated organic raw materials.

[0096] In this regard, since T-COD and S-COD, respectively, can affect the ease of decomposition (or decomposition rate) by microorganisms and the production volume of biogas during the subsequent biogas production reaction, it may be advantageous for the pretreated organic raw material to have T-COD and S-COD within an appropriate range. As an example, the T-COD of the pretreated organic raw material may be in the range of, for example, about 204,000 to 280,000 ppm (specifically about 206,000 to 278,000, more specifically about 207,000 to 230,000 ppm, particularly specifically about 208,000 to 220,000 ppm).

[0097] According to an exemplary embodiment, the S-COD of the treated organic raw material may be in the range of, for example, about 85,000 to 125,000 ppm (specifically about 88,000 to 121,000 ppm, more specifically about 88,000 to 115,000 ppm, particularly specifically about 89,000 to 110,000 ppm).

[0098] It may be suitable for increasing the methane production efficiency by increasing substrate solubility in the anaerobic digestion process of organic feedstocks within the respective ranges of the aforementioned T-COD and S-COD.

[0099] According to an exemplary embodiment, the ratio of volatile solids (VS) to total solids (TS) of the pretreated organic raw material may be an indicator indicating the ratio of organic matter convertible into biogas in a subsequent biogas production reaction (anaerobic digestion reaction), and may be controlled, for example, in the range of about 87 to 90, specifically about 87.5 to 89.8, more specifically about 88 to 89.5, and particularly specifically about 88.5 to 89.4.

[0100] According to an exemplary embodiment, the C / N ratio in the raw material during the biogas production reaction can affect the anaerobic digestion efficiency, microbial growth, and methane production during the subsequent biogas production process. Therefore, the total C / N ratio of the pretreated organic raw material may be controlled in the range of, for example, about 18 to 32, specifically about 20 to 31, more specifically about 22 to 30, and particularly specifically about 25 to 29, which can contribute to enabling methane-producing bacteria to function stably in anaerobic digestion.

[0101] According to exemplary embodiments, total nitrogen (TN) in the biogas production reaction affects the growth and proliferation of biogas-producing microorganisms, so it is desirable for it to be at an appropriate level. Accordingly, the total nitrogen (TN) of the organic raw material pretreated by the integrated process may be in the range of, for example, about 4,500 to 4,900 mg / L, specifically about 4,550 to 4,850 mg / L, more specifically about 4,600 to 4,800 mg / L, and particularly specifically about 4,650 to 4,750 mg / L.

[0102] The characteristics of the aforementioned pretreated organic raw material are provided for exemplary purposes and may vary depending on the type and characteristics of the raw material.

[0103] Meanwhile, according to another embodiment of the present disclosure, a pretreatment device capable of simultaneously performing the aforementioned thermal hydrolysis and ball mill grinding is provided. The schematic appearance of an integrated pretreatment device (100) according to an exemplary embodiment is as shown in FIG. 2.

[0104] Referring to the drawings above, the integrated pretreatment device (100) largely comprises an inner chamber (101), a cover (102), and a rotary connecting part (103) provided on the cover (102). In the illustrated embodiment, the inner chamber (101) is partitioned to accommodate organic raw materials and balls used in a ball mill together, thereby providing a single processing zone. Additionally, the inner chamber (101) may be cylindrical in shape as illustrated, but is not limited to a specific shape as long as thermal hydrolysis and ball mill grinding can be performed simultaneously.

[0105] In the illustrated embodiment, the cover (102) has a shape and dimensions capable of covering an upper open area of ​​the inner chamber (101) and can be attached to the inner chamber (101) in a detachable manner. Additionally, while the cover (102) seals the interior of the chamber (101) when attached, it can function as an inlet for introducing organic raw materials and a plurality of balls into the space within the chamber (101) when detached.

[0106] According to an exemplary embodiment, the cover (102) may be provided with an inlet and / or outlet for the introduction and discharge of gas, through which a specific gas from the outside may be introduced into the inner chamber (101) and gaseous components generated during the pretreatment process may be discharged outside the inner chamber (101). According to an exemplary embodiment, the cover (102) may additionally be provided with a water or moisture supply port (not shown), so that if the organic raw material does not contain enough moisture to sufficiently induce thermal hydrolysis, water or moisture may be replenished through the operation of a pump or the like.

[0107] Referring again to FIGS. 2a and 2b, a rotary drive unit (104) is positioned outside the inner chamber (101) (in the illustrated embodiment, the lateral space of the inner chamber (101)), and the rotary drive unit (104) is driven by a motor. At this time, the rotary drive unit (104) and the rotary connecting unit (103) are configured to be mechanically connected or interlocked by a belt (105). To this end, in the illustrated embodiment, a continuous groove corresponding to the thickness and width of the belt is formed so that the belt (105) can be stably seated and rotated on each of the rotary connecting unit (103) and the rotary drive unit (104). Accordingly, as the motor of the rotary drive unit (104) rotates, the belt provides driving force to the rotary connecting unit (103), and a stirring means (a cross-bar type impeller as described later) mechanically connected to the rotary connecting unit (103) within the inner chamber (101) rotates or stirs. In addition, the temperature inside the internal chamber (101), the rotational speed of the motor, etc., can be controlled by a control unit equipped with a display and an input unit.

[0108] Meanwhile, the internal structure and operating mechanism of the integrated preprocessing device according to the specific embodiment shown in FIGS. 2a and 2b are as shown in FIGS. 3a and 3b.

[0109] Referring to the drawing above, a stirrer, which is a rotating means, is attached to the lower side of a rotating connection part (103) provided on a cover (102), and is configured to rotate at a speed adjusted according to the rotation of the rotating connection part (101).

[0110] According to the illustrated embodiment, a cross-bar type rotatable impeller may be used as a stirrer. In this regard, the rotation axis (111) of the impeller is provided in the inner chamber (101). In the illustrated embodiment, the cover (102) is coupled to the upper end of the inner chamber (101), and the rotation axis (111) may be extended from the central area of ​​the inner chamber (101) across the upper end and the lower end of the inner chamber so that the rotation axis (111) can rotate without disengaging when the rotational connection (103) rotates.

[0111] Additionally, a first cross-bar (112, 112', 112", 112"') in a first direction and a second cross-bar (113, 113', 113") in a second direction are formed along the rotation axis (111) at a predetermined upper and lower interval. At this time, the first cross-bar (112, 112', 112", 112"') and the second cross-bar (113, 113', 113") may be formed alternately to provide effective mutual contact and / or collision action between balls and balls and between balls and organic raw materials contained within the inner chamber (101), but the arrangement pattern may be changed depending on the case (for example, one second cross-bar may be formed next to two first cross-bars formed adjacently, and vice versa). Alternatively, a cross-bar other than the first cross-bar and the second cross-bar (i.e., in the first direction A cross-bar forming a predetermined angle with the second direction may also be additionally provided. Additionally, in the illustrated embodiment, the rotation axis (111) is arranged in the vertical direction, but in an alternative embodiment, the rotation axis (111) may be arranged in the horizontal direction and configured to rotate.

[0112] In an exemplary embodiment, the first direction and the second direction may be formed in mutually perpendicular directions, for example, about 30 to 150°, specifically about 45 to 135°, more specifically about 60 to 120°, particularly specifically.

[0113] In addition, in the illustrated embodiment, four first crossbars and three second crossbars are formed alternately, but this is not limited thereto, and the dimensions and the number of crossbars can be changed depending on the scale of the preprocessing device, etc.

[0114] As described above, as the rotating shaft (111) and the cross-bar rotate, the organic raw material contained in the inner chamber (101) can be crushed by mechanically contacting and / or colliding with a plurality of balls contained in the inner chamber (101).

[0115] Meanwhile, according to the illustrated embodiment, using a ball of appropriate size within the inner chamber (101) may be advantageous in terms of grinding efficiency. In this regard, when the inner chamber (101) is cylindrical in shape, the ratio of the diameter of the ball to the diameter of the cross-section (circular cross-section) of the inner chamber can be adjusted, for example, in the range of about 0.05 to 0.15, specifically about 0.07 to 0.12, more specifically about 0.08 to 0.1.

[0116] According to an exemplary embodiment, in the illustrated embodiment, each of the inner chamber and the cross-bar type rotatable impeller can be made of the same material as the ball material described above.

[0117] A thermocouple may be installed at the lower center (not shown) of the inner chamber (101) of the illustrated pretreatment device (100) to measure and monitor the internal temperature in real time, and based on this, the control unit may be configured to precisely adjust pretreatment conditions such as the temperature inside the chamber (101) and the rotation speed of the stirring means. In this embodiment, since the pretreatment device is operated under high temperature conditions, accurately measuring the temperature inside the chamber (101) may be advantageous for efficient pretreatment. In this regard, conventional devices that perform thermal hydrolysis-only pretreatment adopt a method of measuring the internal temperature by connecting a temperature sensor to the upper side of the chamber, but it is difficult to apply this directly to an integrated pretreatment device that performs ball mill grinding and thermal hydrolysis simultaneously, as in this embodiment. Considering this, in the exemplary embodiment, it may be advantageous to measure the internal temperature of the chamber (101) in real time by installing a thermocouple (not shown) in the central area of ​​the lower end of the inner chamber (101). In this case, the thermocouple is installed inside the chamber and additionally provides a function to fix the rotating shaft (111) constituting the impeller, thereby minimizing vibrations caused by multiple balls and the impeller colliding randomly, so stable operation is possible.

[0118]

[0119] Biogas production process

[0120] According to another embodiment of the present disclosure, biogas can be produced using a pretreated organic raw material according to methods known in the art. In this regard, the reaction for the production of biogas is typically based on anaerobic digestion, specifically by decomposing organic matter in the pretreated raw material through the action of microorganisms to produce biogas mainly containing methane and carbon dioxide. At this time, any type of microorganism capable of converting organic matter into methane under anaerobic conditions may be used, specifically examples include methane-producing bacteria and hydrogen-producing bacteria. Representative species of applicable microorganisms may include Methanobacterium, Methanosaeta, and Methanosarcina.

[0121] The conditions for anaerobic digestion for biogas production are not specifically limited and can be appropriately adjusted by considering the type of microorganism used.

[0122] As an example, the anaerobic digestion temperature can be set in the range of, for example, about 25 to 55°C, specifically about 30 to 50°C, more specifically about 32 to 45°C, and particularly specifically about 35 to 40°C. In addition, the pH can be set in the range of, for example, about 6 to 8.5, specifically about 6.5 to 8.2, and more specifically about 7 to 8.

[0123] According to an exemplary embodiment, the Solids Retention Time (SRT) refers to the average time that microorganisms (solids) remain in the digester (or digestion reactor), and can be controlled in the range of, for example, about 10 to 40 days, specifically about 15 to 35 days, and more specifically about 20 to 30 days. In addition, the Hydraulic Retention Time (HRT) refers to the average time that fluid remains in the digester, and can be controlled in the range of, for example, about 10 to 20 days, specifically about 12 to 18 days, and more specifically about 14 to 16 days.

[0124] In addition, it may be advantageous to process an appropriate amount of pre-treated organic raw material during anaerobic digestion. For example, the organic loading rate can be expressed as the amount of organic raw material fed into a digester of a unit volume per unit time (the unit can be expressed as kg COD / m³ / day), and the organic loading rate can be determined by considering the type of digester, operating temperature, and the characteristics of the pre-treated organic raw material. For example, the organic loading rate can be controlled within the range of, for instance, about 1 to 10 kg COD / m³ / day, specifically about 1.5 to 8 kg COD / m³ / day, and more specifically about 2 to 6 kg COD / m³ / day. In this regard, if the organic loading rate is excessively low, the organic material required by microorganisms inside the digester is not sufficiently supplied, which may lead to a decrease in microbial activity; on the other hand, if it is excessively high, an acid fermentation stagnation phenomenon may occur, which paralyzes the function of the digester. Therefore, it may be advantageous to control it appropriately within the aforementioned range.

[0125] In addition, the generated biogas contains methane and carbon dioxide, as well as trace amounts of other gases (e.g., hydrogen sulfide, ammonia, hydrogen, water, etc.), and may undergo separation and purification processes depending on the downstream process. For example, carbon dioxide can be separated using known carbon dioxide sequestration techniques such as absorption, adsorption, or membrane separation, and hydrogen sulfide can be separated through conventional desulfurization treatments such as wet desulfurization, dry desulfurization, or biological desulfurization. Thus, the methane purified through the separation process can be used as fuel or chemical raw material required for electricity, gas, heat supply, etc.

[0126] The present invention can be more clearly understood by the following examples, which are merely for illustrative purposes and are not intended to limit the scope of the invention.

[0127]

[0128] Examples

[0129]

[0130] In the example, a pretreatment device was manufactured in-house based on the design shown in FIGS. 2 and 3. In the manufactured pretreatment device, (a) a cross-bar type impeller as a stirrer, (b) a cover driven by a belt and a rotating connection part provided therein, (c) an internal chamber space, and (d) a plurality of balls introduced into the internal chamber are respectively shown in FIGS. 4a to 4d.

[0131] In each of the examples and comparative examples, the pretreatment effect was evaluated by measuring the production of biogas by performing a BMP test on the organic sample. For the BMP test, 1 g of a sample mixed with 70% (w / w) of food waste obtained from ... and 30% (w / w) of biomass pretreated according to the procedure described below was placed in a BMP test bottle along with 40 mL of activated sludge (containing 5 g / L glucose) and 160 mL of basal medium (total working volume: 200 mL), and the biogas generated was measured once a day.

[0132] The BMP test was performed according to the conditions and analysis methods shown in Table 1 below.

[0133]

[0134] Test Conditions Total Working Volume: 200 mL Inoculum Volume: 40 mL Substrate Amount: 1.0 g VS Temperature: 37 ℃ Stirring Speed: 100 rpm pH: 7-7.5 Analytical Method: GC-TCD Gas Composition Measurement pH Measurement at 24 and 48 Hours

[0135]

[0136] Example 1 and Comparative Examples 1 and 2

[0137] Biomass (obtained from...) was used as the organic raw material to be pretreated, and the pretreatment was performed in three ways: a single process (thermal hydrolysis; Comparative Example 1), an individual process (ball mill → thermal hydrolysis; Comparative Example 2), and an integrated process (ball mill + thermal hydrolysis; Example 1). When ball milling was involved, the volume ratio of raw material (biomass) to total balls was set to 1:1.

[0138] The pretreatment time was fixed at 15 minutes, and the treatment temperature was set in a total of 5 ranges at intervals of 20 ℃ within the range of 100 to 180 ℃ (Control: no pretreatment; 100 ℃, 120 ℃, 140 ℃, 160 ℃, and 180 ℃). In addition, for the integrated process, the impeller stirring speed was set to 150 rpm, and the liquid-to-saturation ratio (L / S ratio; g / g) was set to 0.1.

[0139] - The average particle size, D50, and D90 of the pretreated biomass samples were measured according to the single process, individual process, and integrated process, respectively, and the results are shown in Figures 5a to 5c.

[0140] Referring to the above drawings, it can be seen that the biomass samples processed in single and individual processes exhibit a pronounced phenomenon of particles clumping or forming lumps when processed at specific temperatures. In particular, in the individual process (ball mill → thermal hydrolysis), a phenomenon was observed where the biomass samples clumped into lumps as the thermal hydrolysis reaction proceeded after the particles of the biomass sample underwent fine grinding (Control: 61.7 μm; Individual process: 54.8 to 165.61 μm). On the other hand, in the integrated process, the particle size of the biomass was maintained at the smallest level under all temperature conditions, which means that the substrate is uniformly dispersed during the biogas production process and fluidity is improved.

[0141] Furthermore, as particle size decreases, the total surface area of ​​the substrate increases, which acts as a factor facilitating microbial accessibility and treatment efficiency. An increase in the surface area of ​​organic raw materials accelerates the decomposition rate and can induce faster and more effective decomposition of organic matter. Specifically, in the anaerobic digestion process, the reduction in particle size leads to more uniform mixing of the substrate and reduces sedimentation and suspension problems within the digester, thereby improving biogas production efficiency. Additionally, increased microbial accessibility accelerates the decomposition of organic matter, ultimately resulting in an increase in methane production.

[0142]

[0143] - The characteristics of the biomass samples pretreated according to the single process, individual process, and integrated process were compared with the characteristics of the biomass samples before pretreatment and the biomass samples that underwent pretreatment by ball milling alone, respectively, and the results are shown in Table 2 and Table 3 below.

[0144]

[0145] Carbon Hydrogen Nitrogen Sulfur Oxygen[%] Before Pretreatment (Raw) 46.6 57.3 65.9 70.6 328.63 Ball Mill (Ball mill) Single 47.5 77.3 95.5 50.5 928.37 Single Process (Thermal Hydrolysis Single) 100 ℃ 51.5 58.0 35.1 10.5 823.3 4120 ℃ 51.2 37.7 85.3 50.5 924.2 7140 ℃ 48.0 57.2 96.0 60.6 326.3 5160 ℃ 48.3 67.4 06.5 70.6 924.6 7180 ℃ 49.2 27.2 96.3 90.6 826.89 Individual Process (Ball Mill → Thermal Hydrolysis) 100 ℃52.487.444.840.5423.83120 ℃50.397.026.940.7324.80140 ℃52.077.187.390.7025.83160 ℃46.446.987.930.6825.73180 ℃55.857.017.700.7322.45 Integrated Process (Ball Mill + Thermal Hydrolysis) 100 ℃49.317.444.840.5427.28120 ℃43.857.026.940.7329.36140 ℃43.927.187.390.7029.74160 ℃44.556.987.930.6825.33180 ℃46.607.017.700.7325.68

[0146]

[0147] C / N ratio Total C / N ratio TSVSVS / TST-CODS-CODT-N Before Pretreatment (Raw) 7.8 129.3 5 18.8 16.9 8 9.6 20 2,300 8 3,400 3,600 Ball Mill (Single) 8.5 7 29.5 8 18.7 16.6 8 8.8 23 2,000 19,800 4,900 Single Process (Thermal Hydrolysis Single) 100 ℃ 10.0 9 30.0 4 19.5 17.6 9 0.3 20 3,200 8 4,000 3,500 120 ℃ 9.5 8 29.8 8 19.8 17.6 8 8.9 23 8,400 8 6,800 4,200 140 ℃7.9329.3919.017.190.0242,400100,0003,500160 ℃7.3629.2218.516.689.7251,800106,4003,000180 ℃7.7129.3218.616.890.3267,600127,4004,300 Individual Process (Ball Mill → Thermal Hydrolysis) 100 ℃10.8330.2619.617.488.8254,80088,8005,000120 ℃7.2629.1920.017.889.0271,00081,2004,500140 ℃7.0429.1219.417.389.2217,40084,6005,000160 ℃5.8628.7718.716.688.8207,40098,6004,700180 ℃7.2529.1817.515.689.1193,200113,2004,600Integrated Process(Ball Mill + Thermal Hydrolysis)100 ℃10.1830.0618.216.087.9222,80088,6004,700120 ℃6.3228.9118.516.589.2210,00089,7004,700140 ℃5.9428.7917.315.388.4225,00096,2004,600160 ℃5.6228.6917.215.288.4249,000104,2004,800180 ℃6.0528.8217.215.187.8278,800121,5004,800

[0148]

[0149] Referring to the table above, the COD measurement includes both biodegradable substances and oxidizing substances, which are non-degradable substances, within the sample. Since the amount of oxygen consumed during the oxidation reaction originates not only from organic compounds but also from inorganic substances that can be oxidized, the COD measurement can be used as an indicator of non-degradable organic substances contained in the sample. According to the table above, the S-COD concentration showed a tendency to increase as the thermal hydrolysis temperature increased under the same treatment method, which implies the possibility that some non-degradable substances within the organic matter may be formed during the thermal hydrolysis process.

[0150] In the integrated process, the carbon content was maintained at a relatively low level, which implies that more soluble organic matter was released compared to single and individual processes. Furthermore, in anaerobic digestion, it is desirable to maintain the C / N ratio within a specific range (approximately 20 to 30) to ensure the stable operation of methane-producing bacteria; the integrated process maintained an appropriate C / N ratio both before and after pretreatment, providing conditions suitable for anaerobic digestion. Additionally, while the decrease in TS and VS after pretreatment indicates that some organic matter was dissolved, the fact that the VS / TS ratio remained constant suggests that although thermal hydrolysis induced physical deformation, it did not significantly affect the total organic matter content.

[0151]

[0152] - In a reaction (BMP test) for producing biogas from a biomass sample pretreated by a single process (thermal hydrolysis single process) according to Comparative Example 1, the biogas production volume and accumulated methane production volume were measured, and the results are shown in Figures 6a and 6b, respectively.

[0153] Referring to the figure above, for biomass treated by a single process, the largest amount of biogas was produced at the lowest treatment temperature of 100°C. Specifically, the total biogas output was highest at 100°C at 504.26 ml / g VS, which represents an increase of approximately 19% compared to the untreated experimental group (Control). Conversely, the total biogas output was lowest at 180°C at 108.94 mL / g VS, suggesting that the thermal hydrolysis effect may become inefficient as the pretreatment temperature increases. Furthermore, the proportion of hydrogen was relatively high, and methanation hardly proceeded, resulting in an extremely low distribution. This can be interpreted as being due to the fact that under high-temperature conditions, organic matter was excessively decomposed, with some of it converted into recalcitrant substances that microorganisms could not effectively utilize.

[0154] Furthermore, in a single process where only thermal hydrolysis treatment was performed, a long initial lag phase (the delay period from the input of the substrate until the microorganisms become activated and begin biogas production) was formed. This is likely because the activation of microorganisms was delayed due to insufficient solubilization of organic matter within the treated biomass. In other words, while the solubilization of the substrate by thermal hydrolysis was effective at low temperatures, leading to higher biogas productivity, the prolonged lag phase required a significant amount of processing time to convert it into methane, which could potentially reduce the overall efficiency of the process.

[0155]

[0156] - In the reaction (BMP test) for producing biogas from a biomass sample pretreated by an individual process (ball mill → thermal hydrolysis) according to Comparative Example 2, the biogas production volume and accumulated methane production volume were measured, and the results are shown in Figures 7a and 7b, respectively.

[0157] Referring to the figure above, in the case of the individual process, contrary to expectations, a smaller amount of biogas was produced throughout the entire thermal hydrolysis stage compared to the untreated biomass sample. Specifically, the biogas production was found to be at a level similar to or without significant difference from the Control (482.23 mL / g VS, 466.0 mL / g VS, 160 ℃). This phenomenon suggests that the particle size relatively increased when ball milling and thermal hydrolysis were applied individually, which does not contribute to an increase in biogas production. In particular, considering that the highest biogas production was observed when treated at 160 ℃, this suggests that biomass pretreatment through individual processes requires a large amount of energy and high costs.

[0158] In addition, a phenomenon was observed in which the amount of hydrogen produced increased rapidly under conditions of 180 ℃, suggesting that methanation did not proceed smoothly. This phenomenon can be explained by the fact that the methane production process of microorganisms was inhibited as organic matter in the biomass sample treated at high temperatures was converted into recalcitrant substances.

[0159] Meanwhile, in the case of the individual process, compared to the single process, methane began to be generated at an earlier stage, and the relatively short processing time for conversion to methane suggests that it may be advantageous in terms of process efficiency. This is attributed to the increased availability of organic matter after ball milling, which promoted the activation of initial microorganisms. However, despite the early onset of methane generation, the total amount of methane produced actually showed a decreasing trend. This can be explained by the fact that while organic matter was rapidly consumed during the initial stages of the individual process, the subsequent lack of a smooth and continuous supply acted unfavorably for long-term methane production.

[0160]

[0161] - Biogas production and accumulated methane production were measured in a reaction (BMP test) to produce biogas from a biomass sample pretreated by an integrated process (ball mill + thermal hydrolysis) according to Example 1, and the results are shown in Figures 8a and 8b, respectively.

[0162] Referring to Figure 8a, the BMP test results for the pretreated biomass samples showed that, compared to the single process, the highest biogas production occurred at a temperature increased by 20°C (120°C). Specifically, for the integrated process, the biogas was approximately 752 mL / g VS and the methane was 486.81 mL / g VS at pretreatment at 120°C. This represents an increase of approximately 8% and 26%, respectively, compared to the results of the control (696.31 mL / g VS and 386.5 mL / g VS). However, when pretreatment was performed at temperatures exceeding 120°C, a pattern of decreasing biogas production efficiency was observed, which corresponds to a pattern similar to that of the aforementioned single and individual processes.

[0163] Referring to Fig. 8b, the cumulative methane generation exceeded 300 mL / g VS within 100 hours and reached approximately 450 mL / g VS around 200 hours. In contrast, the Control group reached 300 mL / g VS after about 300 hours, suggesting that approximately twice the processing time is required compared to the example. Furthermore, the integrated process exhibited a short lag phase, which implies improved productivity (i.e., reduced operating time).

[0164] Based on the results described above, it can be concluded that the integrated process was able to decompose a large amount of biomass sample into methane in a relatively short processing time, and that biomass can be processed more efficiently through the integrated process.

[0165]

[0166] - In the previously performed Comparative Example 1 (single process; thermal hydrolysis alone) and Comparative Example 2 (individual process; ball mill → thermal hydrolysis), and Example 1 (integrated process; ball mill + thermal hydrolysis), the increase in biogas, total methane energy, power consumption, and energy production per hour were measured while changing the pretreatment conditions, and the results are shown in Table 4 below.

[0167] In addition, when the pretreatment time in the integrated process is increased from 15 minutes to 30 minutes, the biogas production and accumulated methane production are shown in Figures 9a and 9b, respectively.

[0168]

[0169] Biogas (CH4) Increase (mL) Total Methane Energy (kWh) Electricity Consumption (kWh) Energy Production Per Hour (Wh / hr) Single Process THP (100 / 15 min) 6 1.4 1.3 1 0.3 0 1 1.46 Single Process THP (120 / 15 min) - 10.0 1.7 2 0.4 8 8.72 Separate Process Ball / THP (100 / 15 min) - 16.8 1.5 9 0.3 4 12.85 Separate Process Ball / THP (120 / 15 min) - 0.9 1.5 4 0.5 2 13.92 Integrated Process Ball+THP (100 / 15 min) 5.4 2.1 0 0.3 1 2 9.86 Integrated Process Ball+THP (120 / 15 min) 8 2.1 2.5 7 0.4 8 3 6.72 Integrated Process Ball+THP(100 / 30min)-117.11.240.397.28 Integrated Process Ball+THP(120 / 30min)6.11.180.576.93

[0170]

[0171] According to the table above, the integrated process showed relatively superior results in terms of total methane energy production and energy production per hour compared to the single and individual processes, and the best results were obtained, especially under conditions of 120°C and 15 minutes.

[0172] In addition, referring to Figures 9a and 9b, when the pretreatment time in the integrated process was doubled, the biogas production decreased sharply. Specifically, compared to the biogas production during 15 minutes of pretreatment, the production of biogas and methane during 30 minutes of pretreatment decreased by approximately 59% and 54%, respectively. This is attributed to the fact that excessive pretreatment caused the organic matter to decompose excessively, forming recalcitrant substances, or that the amount of soluble organic matter available for microorganisms to utilize during the biogas production process decreased.

[0173] All simple variations or modifications of the present invention fall within the scope of the present invention, and the specific scope of protection of the present invention will be clarified by the appended claims.

Claims

1. a) a step of introducing an organic raw material containing solids into a pretreatment device integrated so that grinding by a ball mill and thermal hydrolysis are performed in a single treatment zone; and b) a step of simultaneously performing grinding and thermal hydrolysis by processing the organic raw material under controlled conditions within the above-mentioned pretreatment device; A pretreatment process for organic raw materials including 2. A pretreatment process according to claim 1, characterized in that the content of solids in the organic raw material processed in the pretreatment device is controlled within the range of 50 to 95 weight%.

3. A process according to paragraph 2, characterized in that the organic raw material is at least one of lignocellulose-based biomass and organic waste.

4. A process according to paragraph 3, wherein step b) is performed under conditions of a temperature controlled in the range of 100 to 240 ℃ and a rotational speed in the range of 80 to 250 rpm.

5. A process according to claim 4, wherein step b) is performed under pressure conditions controlled within a range of 1 to 9.5 atmospheres.

6. A process according to claim 5, wherein the organic raw material obtained in step b) has an average particle size (mean size) in the range of 20 to 36 μm, a D50 in the range of 12 to 26 μm, and a D90 in the range of 40 to 85 μm.

7. A process according to paragraph 2, characterized in that the volume ratio of the ball to the solid content of the organic raw material within the single processing zone is controlled within the range of 0.5 to 5:

1.

8. A process according to claim 4, characterized in that, in step b) above, the liquid-to-solid ratio (L / S, weight basis) is controlled within the range of 0.05 to 0.3 based on the solid content of the organic raw material.

9. In paragraph 4, the above step b) is performed in a stepwise control manner including a first step, a second step, and a third step, and At this time, the first step is performed at a rotational speed controlled within the range of 80 to 120 rpm until a processing temperature corresponding to the second step is reached, and The above second step is performed at a rotational speed controlled within the range of 140 to 250 rpm at a temperature within a single processing zone set at a set temperature, and The above third step is characterized by being performed at a rotational speed controlled within the range of 50 to 120 rpm while cooling to a temperature controlled within the range of 40 to 85 ℃.

10. A process according to claim 9, wherein the second step is performed for a time controlled within the range of 5 to 60 minutes.

11. A process according to claim 10, characterized in that the first step is performed for 30 to 90 minutes and the third step is performed for 10 to 80 minutes.

12. A process according to any one of claims 1 to 11, characterized in that the total chemical oxygen demand (T-COD) of the pretreated organic raw material is controlled in the range of 204,000 to 280,000 ppm, and the soluble chemical oxygen demand (S-COD) is controlled in the range of 85,000 to 125,000 ppm.

13. In Clause 12, the ratio of volatile solids (VS) to total solids (TS) of the pretreated organic raw material is set within the range of 87 to 90; The total C / N ratio of the above-mentioned pretreated organic raw material is determined within the range of 20 to 31; and A process characterized in that the total nitrogen (TN) of the above-mentioned pretreated organic raw material is set in the range of 4,500 to 4,900 mg / L.

14. (A) A step of introducing an organic raw material containing solids into a pretreatment device integrated so that grinding by a ball mill and thermal hydrolysis are performed in a single treatment zone; and (B) a step of pretreating an organic raw material by treating the organic raw material under controlled conditions within the pretreatment device to simultaneously perform grinding and thermal hydrolysis; and (C) A step of generating biogas from the pretreated organic raw material by anaerobic digestion; A process for producing biogas from organic raw materials including 15. A pretreatment device for organic raw materials containing solids, An inner chamber partitioned to form a single processing zone accommodating both organic raw materials and multiple balls; A cross-bar shaped rotatable impeller disposed within the inner chamber above; A heat source that provides heat necessary for the thermal hydrolysis of organic raw materials to the inner chamber; and A rotary drive unit connected to the above impeller and providing the driving force required for the rotation of the impeller; Includes, A pretreatment device configured to allow organic raw materials to undergo thermal hydrolysis while being crushed as a plurality of balls come into contact with and / or collide with each other according to the rotation of the above-mentioned cross-bar type rotatable impeller.

16. In paragraph 15, the cross-bar type rotatable impeller is, A rotating shaft installed within the inner chamber; and A plurality of cross-bars formed at predetermined intervals vertically or horizontally along the above rotation axis; Includes, At this time, the plurality of cross-bars rotate according to the rotation of the rotation axis, and A pretreatment device characterized by being configured such that a plurality of balls housed in an inner chamber are in contact with or collide with each other by the above-mentioned rotating crossbar.

17. A pretreatment device according to claim 16, characterized in that a plurality of cross-bars formed on the rotation axis include a first cross-bar extending in a first direction and a second cross-bar extending in a second direction.

18. A pretreatment device according to claim 17, characterized in that the first cross-bar and the second cross-bar are formed alternately, and the first direction and the second direction are mutually perpendicular directions.

19. A pretreatment apparatus according to claim 15 or 16, characterized in that the material of each of the inner chamber, the plurality of cross-bar shaped rotatable impellers, and the balls is at least one selected from the group consisting of steel, stainless steel, ceramic, tungsten carbide, and zirconia.

20. A pretreatment device according to claim 15 or 16, wherein the inner chamber has a cylindrical shape, and the ratio of the diameter of the ball to the diameter of the inner chamber is controlled within the range of 0.05 to 0.15.

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