Animal carcass treatment method

Abstract

The invention relates to the technical field of waste resource treatment, in particular to an animal carcass treatment method which comprises the following steps: after animal carcasses are cooked, collecting first solid residues, first slurry and waste gas; performing three-phase centrifugal treatment on the first slurry, and collecting a liquid phase and a solid phase; the solid phase and the first solid slag are mixed and then subjected to harmless treatment; performing condensation treatment on the waste gas to obtain waste liquid, mixing the waste liquid with the liquid phase to obtain second slurry, and performing anaerobic digestion treatment on the second slurry to generate biogas. Steaming treatment is firstly carried out, so that sterilization and disinfection can be realized, and separation of parts such as bones, meat and fur is facilitated. The first slurry is subjected to three-phase centrifugal treatment, a liquid phase, a solid phase and an oil phase are separated out, the main component of the oil phase is grease and can be used for multiple purposes such as biological fuel oil processing, the solid phase and the first solid residues can be jointly subjected to harmless treatment, and the liquid phase and waste liquid formed by waste gas can be jointly subjected to anaerobic digestion treatment to generate biogas; and resource utilization and energy utilization are realized.

Description

Technical Field

[0001] The present application relates to the technical field of waste treatment, and in particular to a method for treating animal carcasses. Background Art

[0002] If animal carcasses are not handled properly, they can cause the spread and proliferation of pathogenic microorganisms, and can also contaminate the soil, grasslands, surface water and air, causing environmental pollution accidents.

[0003] The existing technology for handling animal carcasses is generally to build a separate sanitary plant, which usually separates the animal carcasses into solid residues and waste liquid through dry treatment. The solid residue is then harmlessly treated in accordance with the "Technical Specifications for the Harmless Treatment of Dead and Diseased Animals" of the Ministry of Agriculture, such as incineration, chemical treatment, anaerobic digestion, deep burial, etc. The waste liquid is treated by a sewage treatment plant.

[0004] The above treatment method greatly reduces the possible harm of animal carcasses, reduces the harm of pathogenic microorganisms and the harm to the environment, and meets the requirements of epidemic prevention and environmental protection. However, the existing treatment method cannot realize the resource utilization of animal carcasses, has high costs and heavy burdens, and the products can only be discarded. Summary of the invention

[0005] The purpose of the present application is to provide a method for processing animal carcasses, aiming to solve the problem that the methods for processing animal carcasses in the prior art cannot be used as resources.

[0006] In order to achieve the above application purpose, the technical solution adopted in this application is as follows:

[0007] The present application provides a method for processing animal carcasses, comprising the following steps:

[0008] After the animal carcasses are steamed, a first solid residue, a first slurry and waste gas are collected;

[0009] The first slurry is subjected to three-phase centrifugation to collect a liquid phase and a solid phase;

[0010] mixing the solid phase with the first solid slag and then performing harmless treatment;

[0011] The waste gas is condensed to obtain waste liquid, the waste liquid is mixed with the liquid phase to obtain a second slurry, and the second slurry is anaerobic digested to generate biogas.

[0012] The method for treating animal carcasses of the present application changes the existing dry treatment into a wet treatment, and first performs a boiling treatment, which can not only sterilize and disinfect, but also facilitate the separation of parts such as bones, meat, fur, and the like, and form a first solid residue, a first slurry, and waste gas. Since the first slurry also contains components such as grease residue, the first slurry can be further subjected to a three-phase centrifugal treatment to separate a liquid phase, a solid phase, and an oil phase. The main component of the oil phase is grease, which can be used for a variety of purposes such as processing biofuels. The solid phase can be harmlessly treated together with the first solid residue, and the liquid phase can be anaerobically digested together with the waste liquid formed by the waste gas to generate biogas. Therefore, the method for treating animal carcasses of the present application not only effectively kills pathogens and meets the requirements of disease control and environmental protection, but can also be converted into high value-added products, realize resource and energy utilization, improve economic value, reduce the "NIMBY effect" caused by the construction of new specialized facilities, achieve coordinated treatment of multiple waste resources, and improve utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0014] Figure 1 It is a schematic diagram of the breeding results of feeding black soldier flies with meat and bone residue and kitchen waste separately and together in step S4 of Example 1 of the present application;

[0015] Figure 2 This is a schematic diagram of the nutritional composition of black soldier flies obtained by feeding the meat and bone residue and kitchen waste separately and together in step S4 of Example 1 of the present application;

[0016] Figure 3 It is a graph of the total methane production of the second slurry and the three-phase centrifuge liquid of the kitchen waste in step S5 of Example 1 of the present application and the blank group and the positive group;

[0017] Figure 4 is a graph showing the total methane production of the second slurry and the kitchen waste three-phase centrifuge liquid at different mixing ratios in step S5 of Example 1 of the present application and a blank group;

[0018] Figure 5 It is a production rate diagram of methane production of different mixing ratios of the second slurry and the kitchen waste three-phase centrifuge liquid in step S5 of Example 1 of the present application and each as a raw material and a positive group;

[0019] Figure 6 It is a daily production rate diagram of different mixing ratios of the second slurry and the kitchen waste three-phase centrifuge liquid in step S5 of Example 1 of the present application. DETAILED DESCRIPTION

[0020] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0021] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0022] In this application, "at least one" means one or more, "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items.

[0023] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0024] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass in the embodiment description of the present application can be μg, mg, g, kg and other mass units known in the chemical industry.

[0025] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0026] Explanation of terms in this application:

[0027] Animal carcasses: should be understood in a broad sense, such as dead poultry and livestock, unqualified frozen meat products, slaughterhouse waste, bone and meat products discarded from restaurant kitchens, etc.

[0028] Three-phase centrifuge liquid (liquid phase): In the prior art, waste materials such as kitchen waste are generally separated into three phases by a three-phase centrifuge to obtain a solid phase, an oil phase, and a liquid phase. The liquid phase here is a common term in the industry, and is a parallel term with the oil phase, excluding the oil phase. However, after the three-phase separation of kitchen waste, it is inevitable that the liquid phase still contains organic matter, rather than an inorganic solution mixture. This is a consensus in the industry. Therefore, the liquid phase and the oil phase are terms within the industry, rather than the liquid phase and the oil phase distinguished from the perspective of chemistry.

[0029] The present application provides a method for processing animal carcasses, comprising the following steps:

[0030] S10: After the animal carcass is steamed, a first solid residue, a first slurry and waste gas are collected;

[0031] S20: subjecting the first slurry to three-phase centrifugation to collect a liquid phase and a solid phase;

[0032] S30: mixing the solid phase with the first solid slag and then performing harmless treatment;

[0033] S40: condensing the waste gas to obtain waste liquid, mixing the waste liquid with the liquid phase to obtain a second slurry, and performing anaerobically digesting treatment on the second slurry to generate biogas.

[0034] The method for treating animal carcasses in the embodiment of the present application changes the existing dry treatment into a wet treatment, and first performs the steaming treatment in step S10, which can not only sterilize and disinfect, but also facilitate the separation of parts such as bones, meat, fur, and the like, and form a first solid residue, a first slurry, and waste gas. Since the first slurry also contains components such as grease residue, the first slurry can be further subjected to a three-phase centrifugal treatment in step S20 to separate a liquid phase, a solid phase, and an oil phase. The main component of the oil phase is grease, which can be used for a variety of purposes such as processing biofuels. The solid phase can be harmlessly treated together with the first solid residue in step S30, and the liquid phase can be anaerobically digested together with the waste liquid formed by the waste gas in step S40 to generate biogas. Therefore, the method for treating animal carcasses in the embodiment of the present application not only effectively kills pathogens and meets the requirements of disease control and environmental protection, but can also be converted into high value-added products, realize resource and energy utilization, and improve economic value.

[0035] [Step S10]

[0036] After the animal carcasses are steamed, a first solid residue, a first slurry and waste gas are collected;

[0037] This step is a step of performing a cooking treatment. The collected animal carcasses can be sorted first, and then chopped or crushed to reduce the particle size and increase the surface area, which is beneficial to the cooking effect. The cooking treatment can be carried out in a high-pressure sterilization reactor, and can be boiled in hot water or steam. The temperature of the steam can be 135-145°C, the cooking time can be 30-45 minutes, the cooking pressure can be 0.3-0.4MPa, and the mass ratio of the animal carcass to the steam can be (8-10):1. These process parameters are conducive to killing pathogens and separating the fur, meat, etc. of the animal carcass from the bones.

[0038] After the cooking process, the first solid residue, the first slurry and the waste gas are collected, and these components are processed and utilized in steps S20, S30 and S40, respectively. Therefore, the above steps S20, S30 and S40 are in a parallel relationship, representing the destination and processing method of the three products obtained by the cooking process, but not representing the order of the steps. The main components of the first solid residue are bone ash, meat, etc., the first slurry contains oil, protein, water, fine residue, etc., and the waste gas contains water vapor and volatile components, and has a bad smell.

[0039] [Step S20]

[0040] The first slurry is subjected to three-phase centrifugation to collect a liquid phase and a solid phase;

[0041] The first slurry contains a variety of complex components that are difficult to use directly, so it can be separated first. This step is a step of performing three-phase centrifugal treatment on the first slurry to obtain a solid phase, a liquid phase and an oil phase. The oil phase is rich in components such as oil and fat, which can be used to process biofuels, industrial oils, soaps, and biodiesel, which is beneficial to improve economic value. The solid phase and the liquid phase are further processed in steps S30 and S40 respectively.

[0042] [Step S30]

[0043] S30: mixing the solid phase with the first solid slag and then performing harmless treatment;

[0044] This step is a step of harmlessly treating the first solid residue of step S10 and the solid phase of step S20. The main components of the first solid residue and the solid phase are organic solids such as meat and bone residue. The harmless treatment may include at least one of incineration, chemical treatment, anaerobic digestion, landfilling, and feeding insect larvae. Among them, incineration, chemical treatment, anaerobic digestion, and landfilling are all methods recorded in the relevant standard documents of the Ministry of Agriculture of the People's Republic of China. These methods have different advantages and disadvantages. Different regions can choose appropriate treatment methods according to their own conditions. Feeding insect larvae is a resource utilization method created by the treatment method of this application. The high organic matter solids after the solid phase is mixed with the first solid residue are rich in high protein and moderate in moisture content. They can be used to feed saprophytic insect larvae, such as mealworms or black soldier flies. The adults obtained by feeding can be used as animal feed, which can replace fish meal or soybean meal in aquatic feed. Compared with mealworms, black soldier flies have higher oil content and lower protein content, faster growth rate, and stronger feeding habits and adaptability than mealworms. The ideal feed for raising black soldier flies needs to be nutritionally balanced, with protein generally ranging from 16% to 23%, crude fat ranging from 3% to 11%, and carbohydrates ranging from 41% to 53%. Compared with this standard, the mixture of the solid phase and the first solid residue can be used as a potential high-quality feed for raising black soldier flies. However, the mixture of the solid phase and the first solid residue has problems such as a single nutritional structure, poor air permeability, and high crude fat content. Therefore, it is possible to consider balancing nutrition by adjusting the moisture content or adding substances rich in starch and cellulose so that the black soldier fly larvae can grow better on the mixture of the solid phase and the first solid residue. In the demonstration example, it can be appropriately mixed with fruit and vegetable waste, which is conducive to increasing the growth rate of larvae, increasing the weight of adults, and improving Liao Cong's conversion rate.

[0045] In some embodiments, after collecting the first solid slag, the following steps are further included:

[0046] Extruding the first solid slag to obtain a second solid slag and a third slurry;

[0047] The third slurry is mixed with the first slurry and then subjected to three-phase centrifugal treatment in step S20;

[0048] The second solid slag is mixed with the solid phase and then subjected to harmless treatment.

[0049] These steps are mainly to further process the first solid slag. Since a large amount of liquid organic matter and other components often remain in the first solid slag, the components in the first solid slag can be further separated by extrusion treatment, and the liquid components therein can be squeezed out to obtain the third slurry, and the remaining extruded solid slag is collected as the second solid slag.

[0050] Since steps S20, S30, and S40 are described above as parallel steps rather than sequential steps, the prepared third slurry can be mixed with the first slurry in step S20 and then subjected to the three-phase centrifugal treatment of step S20. The specific method of the three-phase centrifugal treatment and the subsequent product processing can refer to the description of the above step S20.

[0051] Similarly, the prepared second solid slag can be mixed with the solid phase in step S30 (or further including other first solid slags) and then subjected to the harmless treatment of the above step S30. The specific method of the harmless treatment and the subsequent product processing can refer to the description of the above step S30.

[0052] [Step S40]

[0053] The waste gas is condensed to obtain waste liquid, the waste liquid is mixed with the liquid phase to obtain a second slurry, and the second slurry is anaerobic digested to generate biogas.

[0054] This step is a step of resource utilization of the waste gas and the liquid phase of the three-phase centrifugation in step S20. Both the waste gas and the liquid phase contain a large amount of organic matter with complex components and a certain nitrogen content. Therefore, the waste gas can be condensed to obtain waste liquid, which can be mixed with the liquid phase and then subjected to anaerobic fermentation to produce biogas, thereby realizing resource utilization.

[0055] In some embodiments, the waste liquid and the liquid phase are mixed in a mass ratio of (0.1-0.3):1 to obtain the second slurry, which may include but is not limited to any ratio of 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1 or any range between any two ratios. The waste liquid and the liquid phase in these mass ratios are beneficial to adjust the parameters such as heavy volatile fatty acids (VFA), ammonia nitrogen, total alkalinity, carbon-nitrogen ratio in the second slurry to the best, thereby improving the effect of anaerobic digestion treatment to produce biogas.

[0056] In some embodiments, the raw materials for anaerobic digestion treatment also include three-phase centrifuge liquid of kitchen waste. After research, the applicant found that if the second slurry obtained by the above-mentioned animal carcass treatment method is used for anaerobic fermentation treatment alone, the biogas production rate is slow, and it takes more days to reach a high daily output. At the same time, the biogas production ratio is not high compared to the second slurry. However, after the three-phase centrifuge liquid of kitchen waste and the second slurry are mixed (the mixed liquid is hereinafter referred to as the fourth slurry), anaerobic fermentation treatment can not only greatly accelerate the biogas production rate, but also improve the production ratio, which has a higher economic value. At the same time, the kitchen waste is also utilized as a resource, which has more environmental value.

[0057] In some embodiments, the mass ratio of the three-phase centrifuge liquid to the second slurry is (0.25-4):1. In the exemplary embodiment, it may include but is not limited to any ratio of 0.25:1, 0.5:1, 1:1, 2:1, 4:1 or any range between any two ratios. The fourth slurry obtained by mixing the three-phase centrifuge liquid with these mass ratios with the second slurry has a fast biogas production rate through anaerobic digestion and a high production ratio.

[0058] In some embodiments, the anaerobic digestion treatment includes adding at least one of inoculated activated sludge, anaerobic digestion sludge, and anaerobic bacteria; the inoculated activated sludge may include solid residues obtained by three-phase centrifugation of kitchen waste for culturing and domestication treatment, which is beneficial to improving the effect of anaerobic digestion and methanogenesis. The anaerobic bacteria may be fermentative bacteria, hydrogen-producing acetogenic bacteria, hydrogen-consuming acetogenic bacteria, hydrogen-consuming methanogenic bacteria, acetogenic methanogenic bacteria, and may be powder or aqueous solution.

[0059] In some embodiments, the temperature of the anaerobic digestion treatment may be 35-37° C., and the duration of the anaerobic digestion treatment may be 21-45 days to ensure the progress of the anaerobic digestion treatment and the methane yield and output.

[0060] In some embodiments, the carbon-nitrogen ratio of the raw material (the second slurry or further the fourth slurry) for anaerobic digestion treatment is (15-25):1, which may include but is not limited to any ratio of 15:1, 20:1, 25:1 or a range between any two ratios. By controlling the carbon-nitrogen ratio of the raw material, it is beneficial to increase the biogas production rate and yield of anaerobic digestion treatment.

[0061] In some embodiments, the anaerobic digestion treatment includes the steps of hydrolysis treatment, acidification treatment, hydrogen and acetogenesis, and methanogenesis treatment in sequence;

[0062] Among them, the temperature of the hydrolysis treatment is ≥90°C, and the hydrolysis treatment is carried out by wet heat; various hydrolases can be added to convert the complex organic components in the raw materials into simple soluble monomers or dimers. Since subsequent microorganisms cannot directly metabolize biological macromolecules such as carbohydrates, proteins and fats, they need to be degraded into soluble polymers or monomer compounds before they can be used by acidified bacteria. Starch is hydrolyzed into maltose, glucose and dextrin under the action of amylase. Cellulose is hydrolyzed into sugar under the synergistic action of multiple cellulases. The peptide bonds of proteins are broken by proteases to generate dipeptides and polypeptides, and then various amino acids are generated.

[0063] Acidification treatment includes lactic acid fermentation treatment, which can be carried out in an acidification tank with kitchen waste centrifuge for 3 to 5 days. The acidogenic fermentation process refers to the conversion of organic matter in the form of soluble monomers or dimers into end products mainly composed of short-chain fatty acids or alcohols. These hydrolyzed monomers will be further degraded by microorganisms into lactic acid, etc.

[0064] Hydrogen and acetic acid production are intermediate products in the acidification process. This stage mainly converts organic acids or alcohols with more than two carbon atoms produced in the hydrolysis and acidification stage into small molecules such as acetic acid that can be directly used by methanogens.

[0065] Methanation treatment is the process in which the slurry after hydrolysis and acidification is put into the anaerobic tank for anaerobic digestion. This step is the process in which strictly anaerobic methanogenic bacteria convert acetic acid, one carbon compound, H2, CO2, etc. into CH4 and CO2.

[0066] In some embodiments, the yield of biogas generated is 320-360 mL / g COD.

[0067] The following describes the invention in conjunction with specific embodiments.

[0068] Example 1

[0069] This embodiment provides a method for processing animal carcasses, comprising the following steps:

[0070] S1: The collected 20 tons of dead poultry and livestock carcasses are first washed with 2 tons of disinfectant water, and then steamed with 2 tons of steam, and the first solid residue, the first slurry and the waste gas are collected;

[0071] S2: extruding the first solid slag to obtain a second solid slag and a third slurry;

[0072] S3: The first slurry and the third slurry are mixed and then subjected to three-phase centrifugal treatment to collect the liquid phase, solid phase and oil phase. The oil phase is 2 tons in total, mainly grease, which is shipped and sold and can be used for processing biofuels and other purposes;

[0073] S4: The solid phase and the second solid residue are mixed to obtain 1.7 tons of meat and bone residue for feeding black soldier fly larvae;

[0074] S5: The waste gas is condensed to obtain waste liquid, and the waste liquid and liquid phase are mixed to obtain a second slurry totaling 20.3 tons. The three-phase centrifugal liquid of the kitchen waste and the second slurry are mixed at a weight ratio of 4:1 to obtain a fourth slurry, and the fourth slurry is subjected to anaerobically digested treatment to generate biogas.

[0075] Example 2

[0076] This embodiment provides a method for treating animal carcasses, which is different from Embodiment 1 only in that the weight ratio of the three-phase centrifuge liquid of kitchen waste to the second slurry in step S5 is changed from 4:1 to 3:2, and the rest is the same.

[0077] Example 3

[0078] This embodiment provides a method for treating animal carcasses, which is different from Embodiment 1 only in that the weight ratio of the three-phase centrifuge liquid of kitchen waste to the second slurry in step S5 is changed from 4:1 to 2:3, and the rest is the same.

[0079] Example 4

[0080] This embodiment provides a method for treating animal carcasses, which is different from Embodiment 1 only in that the weight ratio of the three-phase centrifuge liquid of kitchen waste to the second slurry in step S5 is changed from 4:1 to 1:4, and the rest is the same.

[0081] Example 5

[0082] This embodiment provides a method for treating animal carcasses, which is different from Embodiment 1 only in that the three-phase centrifuge liquid of kitchen waste is not added in step S5, but the second slurry is directly used for anaerobic digestion treatment, and the rest is the same.

[0083] Example 6

[0084] This embodiment provides a method for processing animal carcasses, which differs from Embodiment 1 only in that there is no step S2 for further extrusion of the first solid residue, and the first solid residue obtained in step S1 is directly used for feeding black soldier fly larvae in step S4, and the first slurry obtained in step S1 is directly used for three-phase centrifugal treatment in step S3, and the rest are the same.

[0085] Related performance tests and results

[0086] 1. Meat and bone residue

[0087] 1.1 Raw material testing

[0088] A third-party testing agency was commissioned to test the meat and bone residue in step S4 of Example 1. The elemental analysis results are shown in Table 1.1.

[0089] Table 1.1

[0090] C(％) H(％) O(％) N(％) S(％) 44.48±1.65 6.92±0.21 23.18±0.74 9.38±0.64 1.98±0.04

[0091] After drying to constant weight, the nutritional indicators are shown in Table 1.2.

[0092] Table 1.2

[0093] Crude Protein Crude fat Crude Fiber Coarse ash Moisture 55.87％ 14.7％ ≤1.0％ 22.50％ 0.05％

[0094] The contents of 18 common amino acids in meat and bone residue are shown in Table 1.3.

[0095] Table 1.3

[0096]

[0097]

[0098] The sanitary indicators of meat and bone residue are shown in Table 1.4. All sanitary indicators of meat and bone residue meet the feed hygiene standards. No conventional 112 types of veterinary drug residues were detected. In general, meat and bone residue is a material with high nutritional value, meets various safety standards, and has great potential for resource utilization.

[0099] Table 1.4

[0100]

[0101]

[0102] In general, the moisture content of meat and bone residue is 67%, and the carbon-nitrogen ratio (mass ratio of carbon to nitrogen) is 4.75±0.14, which is relatively low compared to the C / N (15-25) of good substrates for anaerobic digestion. Meat and bone residue has high crude protein content, high crude fat content, low crude fiber content, and also contains ash from bones. If meat and bone residue is used alone to feed mealworm larvae, the moisture content of the meat and bone residue will be high; if black soldier flies are raised, the protein and crude fat content will be higher than the ideal range. Therefore, some starch- and cellulose-rich substances can be added to the meat and bone residue to balance the nutrition so that the insect larvae can grow better. Meat and bone residue is rich in amino acids and has good nutrition.

[0103] 1.2 Specific feeding method

[0104] The room temperature was maintained at 26°C, the humidity was about 60%, each set of boxes was not covered, and an 80-mesh gauze was used to prevent insects from entering and exiting; the collected meat and bone residues were frozen and stored in a refrigerator at -20°C for standby use; the fruit and vegetable waste used in this paper used 1300g of lettuce roots and 144g of rotten leaves of small green vegetables discarded from the Heyuan Canteen of Tsinghua University Shenzhen International Graduate School; 1310g of fruit peels discarded from fresh fruit cuttings from Baiguoyuan, including dragon fruit peels (800g), pineapple peels (210g), watermelon peels (200g), and mango peels (100g). It was crushed into a slurry with a particle size of less than 0.5cm by a wall-breaking machine and frozen and stored in a refrigerator at -20°C for standby use.

[0105] Then, according to different mass ratios, they were divided into five groups: PF (pure fruits and vegetables), FM31 (fruits and vegetables: meat and bone residue = 3:1), FM11 (fruits and vegetables: meat and bone residue = 1:1), FM13 (fruits and vegetables: meat and bone residue = 1:3), and PM (meat and bone residue), with three replicates in each group, and each replicate was inoculated with about 1,000 4-day-old larvae.

[0106] 1.3 Test Results

[0107] The results of the experiment on feeding black soldier flies with meat and bone residue are as follows Figure 1 As shown, Figure 1The weight of black soldier flies obtained by breeding under different ratios of mixed matrix conditions (PF, fruit and vegetable waste; PM, meat and bone residue; FM represents a mixture of fruit and vegetable waste and meat and bone residue, and the two numbers behind it represent the ratio).

[0108] Furthermore, the black soldier fly larvae produced by the fruit and vegetable feeding, mixed feeding (FM13) and meat and bone residue feeding groups were sent for inspection and analyzed for nutritional indicators. The results are as follows: Figure 2 shown. Figure 2 The nutritional indexes of the black soldier fly pre-pupae in three groups: pure fruit and vegetable, optimal mixture, and meat and bone residue. The amino acid content was tested, and the results are shown in Table 1.5. EAA in Table 5 is essential amino acid, and TAA is the total amount of amino acids.

[0109] Table 1.5

[0110]

[0111]

[0112] from Figure 1 From the results of the black soldier fly larvae rearing, several materials can be used for larval growth, but fruit and vegetable waste has the worst effect, and the weight gain of the insects is not obvious, indicating that the feasibility of pure fruit and vegetable waste rearing is low. Meat and bone residue has a better effect as feed, but when it is properly mixed with fruit and vegetable waste (3:1), the larvae grow fastest, the insect weight is the largest after two weeks, and the weight is close to 100 mg / piece at harvest, and the feed-worm conversion rate is 22.0%. Therefore, adding 1 / 3 of fruit and vegetable waste to meat and bone residue is beneficial to the rearing of black soldier fly larvae.

[0113] In terms of larval nutritional content, combined Figure 2 It can be seen from Table 1.5 that the crude protein content of feed is positively correlated with the crude protein content in the insect body. The crude protein content of the fruit and vegetable garbage group, mixed group, and meat and bone residue group were 36.23%, 40.64%, and 42.58%, respectively. Among them, the crude protein content of the fruit and vegetable garbage group was the lowest, and the protein content of the meat and bone residue group was the highest. Generally, the protein content of black soldier fly larvae is between 32% and 58%, and the results of this study are also in this range. The crude fat and ash content of the mixed group and the meat and bone residue group were similar, ranging from 30.63% to 30.70% and 14.24% to 14.50%, respectively, which were significantly higher than the crude fat and ash content of the fruit and vegetable garbage group. At the same time, the crude fiber content of the mixed group and the meat and bone residue was also close, about 7.40%, while the crude fiber content of the fruit and vegetable garbage group reached 8.28%.

[0114] Recombinase-mediated isothermal nucleic acid amplification technology (RAA) can be used to determine limiting amino acids. The smaller the RAA value, the more insufficient the content of this type of amino acid. The RAA values ​​of insect leucine in the fruit and vegetable garbage group, meat and bone residue group, and mixed group were very low, at 0.02, 0.01, and 0.02, respectively, indicating that the first limiting amino acid was leucine; the second limiting amino acid in the fruit and vegetable garbage group and the meat and bone residue group was glycine, while the second limiting amino acid in the mixed group was lysine. This shows that different feeds will lead to different amino acid compositions in black soldier fly larvae. Therefore, when using a mixture to feed black soldier flies, the supplementation of leucine and lysine can be appropriately increased.

[0115] This experiment used the nutritional requirement of 50-75kg pigs (NRC2012) as the reference protein and the essential amino acid index (EAAI) as the evaluation standard to evaluate the protein of black soldier fly larvae fed on three different matrices. The EAAI of the fruit and vegetable waste group, the meat and bone residue group, and the mixed group were 1.97, 0.64, and 0.88, respectively. Among them, the EAAI of the mixed group was higher, which was a good protein feed; the EAAI of the fruit and vegetable waste group was the highest, but the weight of a single worm was extremely low, which was not suitable for practical application; the EAAI of the meat and bone residue group was lower, and it was not suitable as a protein feed, indicating that only feeding with meat and bone residue led to an imbalance in the nutritional composition of the worm.

[0116] In summary, the meat and bone residue obtained by mixing the solid phase and the second solid residue as a substrate for feeding black soldier flies has a better effect, and the quality of black soldier fly larvae as protein feed can be improved by mixing fruit and vegetable waste in an appropriate proportion. When the meat and bone residue is mixed with fruit and vegetable waste in a ratio of 3:1, the larvae grow at the fastest rate and can be harvested within two weeks, and the feed-worm conversion rate reaches 22.0%. According to this ratio, each ton of dead poultry and livestock feed can produce 0.02t of fresh insects and 1.55kg of insect feces that can be used for composting, with a total benefit of 40.78 yuan. According to the estimated annual processing capacity of 4,600t of the sanitary treatment plant, it can benefit 188,000 yuan per year. Compared with traditional methods such as incineration and landfill, it realizes resource utilization while protecting the environment and improves economic benefits.

[0117] 2. Anaerobic digestion to produce methane

[0118] 2.1 Raw material testing

[0119] A third-party testing agency was commissioned to test the second slurry and kitchen waste centrifuge liquid of step S5 of Example 1. The test results are shown in Table 2.1. Compared with domestic sewage, the sanitary treatment waste liquid of dead poultry and livestock and the three-phase centrifuge liquid of kitchen waste have the characteristics of high COD, high ammonia nitrogen and organic matter content.

[0120] Table 2.1

[0121]

[0122]

[0123] 2.2 Specific anaerobic fermentation method

[0124] The biochemical methanogenic potential (BMP) tester was used for analysis. The constant temperature water bath was set at 37℃, the total substance in the reactor was set to 400mL, the total VS was set to 20g / L, and the inoculum mud: mixture VS ratio (ISR) was set to 4:1. In principle, the total VS of each group of kitchen waste centrifuge liquid and the second slurry was the same to prevent the different VS of the mixture from affecting the anaerobic digestion efficiency. On this basis, the total mass of the mixture was adjusted to explore the ideal ratio of adding to promote anaerobic fermentation. Each treatment was repeated three times. The inoculum mud used kitchen waste anaerobic digestion slurry, and the fine residue of kitchen waste three-phase centrifugation was used for cultivation and domestication. Before the experiment, the system was tested for heavy volatile fatty acids (VFA), ammonia nitrogen, total alkalinity, etc. The results showed that the inoculum basically met the requirements of the biochemical methanogenic potential (BMP) experiment, and only the ammonia nitrogen was 3.8g / L, slightly higher than the standard requirement of 2.5g / L. The experiment was divided into blank (inoculated mud), positive control (inoculated mud + cellulose), kitchen waste slurry, livestock wastewater and different mixing ratios, as shown in Tables 2.2 and 2.3, with three parallels in each group.

[0125] Table 2.2

[0126] deal with Inoculation mud (g) Centrifuge liquid (g) Livestock wastewater (g) Deionized water (g) blank 348 0 0 0 Positive Control 278.3 0 0 1.6 Food waste 278.3 32 0 0 Livestock wastewater 278.3 0 16 0

[0127] Table 2.3

[0128] deal with Inoculation mud (g) Centrifuge liquid (g) Livestock wastewater (g) Deionized water (g) blank 269.4 0 0 0 Centrifuge liquid: wastewater 4:1 215.5 25.4 6.4 0 Centrifuge liquid: wastewater 3:2 215.5 16.7 11.1 0 Centrifuge liquid: wastewater 2:3 215.5 10 15 0 Centrifuge liquid: wastewater 1:4 215.5 4.5 18 0

[0129] 2.3 Test Results

[0130] Among them, the total methane production (in mL) of the single substrate experiment is as follows Figure 3 The total methane production (in mL) of the mixed substrate experiment is shown in Figure 4 The methane yields (in mL / gCOD) of single and mixed substrate experiments are shown in Figure 5 The daily rate of methane production in the mixed substrate experiment (in mL / gCOD) is shown in Figure 6 shown.

[0131] Figure 5 It can be seen that the gas production of the cellulose group (positive control group) is normal, which is 392mL / g VS, indicating that the performance of the inoculum is good. The three-phase centrifuge liquid of kitchen waste and the waste liquid from dead poultry and livestock treatment have certain methane production potential and can produce biogas through anaerobic digestion. Figure 5It can be seen that the methane production capacity of the three-phase centrifuge liquid of kitchen waste is about 180mL / g COD, and the wastewater from dead poultry and livestock treatment is about 210mL / g COD. When the two are mixed, not only does it not affect the anaerobic digestion performance of the kitchen waste itself, but the methane production capacity is significantly improved. Among them, when the ratio of kitchen waste centrifuge liquid to dead poultry and livestock treatment wastewater is 2:3, the methane production potential is the largest, reaching 332mL / g COD, which is significantly higher than the anaerobic digestion performance of the two single substrates, and the methane production is increased by 66%.

[0132] The duration of the two batches of experiments was about 20 days. Figure 4 and Figure 6 It can be seen that when dead livestock and diseased animals are used to treat wastewater, gas production is nearly complete after about 15 days, while when kitchen waste three-phase centrifugal liquid or mixed substrates of different proportions are used, gas production is nearly complete after 7 days; at the same time, the maximum daily methane production rate of the mixed substrate experiment occurs around the 1st and 6th days. Therefore, the use of mixed substrates will not extend the treatment cycle of the original kitchen waste anaerobic digestion system, nor will it reduce the treatment capacity of the anaerobic digestion system.

[0133] According to the experimental results, when the three-phase centrifuge liquid of kitchen waste and the filtrate of dead livestock treatment were mixed in a ratio of 2:3, the methane production was the highest, reaching 1068mL / 25g substrate (10g+15g). Assuming that the methane production contribution of the two wastewaters is roughly the same, the amount of biogas produced by dead livestock entering the existing anaerobic digestion system is 71.17m3 / t dead livestock wastewater. According to the calculation that 20.3t of wastewater is generated when 20t of feed is processed, the emergency treatment line can produce 72.24m3 per ton of feed. 3 Biogas has extremely high economic value.

[0134] 3. Test method description

[0135] The equipment or test methods for the above parameters are as follows:

[0136] The pH value was measured using a Mettler Toledo Inlab Expert Go-ISM pH meter.

[0137] Volatile fatty acids were determined after pretreatment. The pretreatment method was as follows: the sample was centrifuged at 10,000 rpm for 10 min, and the supernatant after centrifugation was filtered with a filter membrane with a pore size of 0.45 μm to further remove impurities. The filtrate finally obtained can be used for the determination of soluble parameters. After the sample was pretreated by dilution, membrane filtration, etc., 1 mL of the filtrate was taken into a chromatographic bottle, 30 μL of formic acid was added, and then the chromatographic instrument (GC-2014, Shimadzu, Japan) was used for determination. The chromatograph was equipped with a capillary column (Inertcap wax 30m×0.25mm×0.25μm) and a flame ionization detector.

[0138] The soluble chemical oxygen demand (SCOD) was determined by the potassium dichromate method. After the sample was diluted to an appropriate concentration, 2 mL of the sample was taken from the reaction bottle of the kit and shaken well. The sample was placed in a digester for digestion and then tested (HACH, DRB200, USA).

[0139] Other test indicators are shown in Table 3.1 below.

[0140] Table 3.1

[0141]

[0142] The amino acid ratio (RAA) is a method used to evaluate the nutritional value of protein in feed / food. The calculation formula is as follows:

[0143] RAAi=Ai / A0

[0144] Essential Amino Acid Index (EAAI):

[0145]

[0146] n: the number of essential amino acids for comparison. When n is 6-12, EAAI ≥ 0.90 is a high-quality protein source; 0.80 ≤ EAAI < 0.90 is a good protein source; 0.70 ≤ EAAI < 0.80 is a usable protein source; EAAI < 0.70 is an unusable protein source.

[0147] Data processing software: SPSS (ANOVA), excel, origin.

[0148] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for processing animal carcasses, characterized in that: The steps include: After the animal carcasses are steamed, a first solid residue, a first slurry and waste gas are collected; Subjecting the first slurry to three-phase centrifugation to collect a liquid phase and a solid phase; mixing the solid phase with the first solid slag and then performing harmless treatment; The waste gas is condensed to obtain waste liquid, the waste liquid is mixed with the liquid phase to obtain a second slurry, and the second slurry is anaerobic digested to generate biogas.

2. The method for processing animal carcasses according to claim 1, characterized in that: The raw materials for the anaerobic digestion treatment also include a three-phase centrifuge liquid of kitchen waste, and the mass ratio of the three-phase centrifuge liquid to the second slurry is (0.25-4):

1.

3. The method for processing animal carcasses according to claim 1 or 2, characterized in that: The temperature of the anaerobic digestion treatment is 35-37°C; And / or, the anaerobic digestion treatment includes adding at least one of inoculated activated sludge, anaerobic digestion slurry, and anaerobic bacteria; And / or, the anaerobic digestion treatment time is 21 to 45 days; And / or, the carbon-nitrogen ratio of the raw material subjected to the anaerobic digestion treatment is (15-25):

1.

4. The method for processing animal carcasses according to claim 3, characterized in that: The inoculated activated sludge is cultured and domesticated by solid residues from three-phase centrifugation of kitchen waste.

5. The method for processing animal carcasses according to any one of claims 1, 2 or 4, characterized in that: The anaerobic digestion treatment includes the steps of hydrolysis treatment, acidification treatment, hydrogen and acetic acid production and methanation treatment in sequence; Wherein, the temperature of the hydrolysis treatment is ≥90°C; The acidification treatment includes lactic acid fermentation treatment, and the duration of the lactic acid fermentation treatment is 3 to 5 days.

6. The method for processing animal carcasses according to any one of claims 1, 2 or 4, characterized in that: The yield of the generated biogas is 320-360 mL / g COD.

7. The method for processing animal carcasses according to any one of claims 1, 2 or 4, characterized in that: The waste liquid and the liquid phase are mixed in a mass ratio of (0.1-0.3):1 to obtain the second slurry.

8. The method for processing animal carcasses according to claim 1, 2 or 4, characterized in that: After collecting the first solid slag, the method further comprises the following steps: Extruding the first solid slag to obtain a second solid slag and a third slurry; The third slurry is mixed with the first slurry and then subjected to the three-phase centrifugal treatment; The harmless treatment is then performed after the second solid slag is mixed with the solid phase.

9. The method for processing animal carcasses according to any one of claims 1, 2 or 4, characterized in that: The harmless treatment includes at least one of incineration, chemical treatment, anaerobic digestion, landfilling, and feeding insect larvae.

10. The method for processing animal carcasses according to any one of claims 1, 2 or 4, characterized in that: The steaming treatment comprises steaming the cooking treatment, the temperature of the steam is 135-145° C., and the time of the steaming treatment is 30-45 minutes.

Images