A method for treating kitchen waste by wet heat catalytic hydrolysis

Abstract

The present invention belongs to the field of waste treatment, and particularly relates to a method for treating kitchen waste by wet heat catalytic hydrolysis. A method of combining supercritical steam wet heat catalytic hydrolysis, flotation adsorption and anaerobic fermentation is used to treat kitchen waste in a multi-level and all-round manner, and organic matter in kitchen waste is converted into small molecule organic acids to the greatest extent. The present invention adsorbs grease with montmorillonite loaded with beta-cyclodextrin having quaternary ammonium salt cations to obtain a microsphere suspension in which grease is evenly dispersed; the problem of high grease inhibiting degradation efficiency or anaerobic fermentation speed is solved, and grease is made into energy for biocatalysis links, which is preferentially consumed and degraded, and composite strains are selected to be loaded on active carriers, so that the strains remain active in a high-salt environment, and the fermentation speed and degradation speed are improved, providing a new method for high value-added kitchen waste treatment.

Description

Technical Field

[0001] The invention belongs to the technical field of organic waste treatment, and in particular relates to a method for treating kitchen waste by wet heat catalytic hydrolysis. Background Art

[0002] The grease in kitchen waste exists in five forms: floating oil, dispersed oil, emulsified oil, dissolved oil, and grease inside the solid phase. Among them, the floating oil has a larger particle size and can float up quickly after standing still, floating on the water surface in the form of a continuous oil film; the dispersed oil is suspended in the liquid phase in the form of small oil droplets. After standing for a period of time, this type of oil will gather into larger oil droplets and float to the water surface; the emulsified oil is milky in the liquid phase, which is more difficult to separate than the above two types of oil; the dissolved oil is dispersed in the water phase in a molecular or chemical state to form neutral oil droplets, with a particle size of less than a few nanometers. The oil and water form a very stable homogeneous system, which is difficult to remove by general physical methods; the grease inside the solid phase is mostly in a solid form and is tightly combined with the solid phase particles of the food waste, making it difficult to separate directly. In addition, since the solid content in the kitchen waste slurry reaches 10% to 15%, the grease that is easier to remove, such as floating oil and dispersed oil, will be adsorbed and mixed in the solid matter, reducing the separation performance of these greases. Therefore, it is very difficult to separate the grease in kitchen waste.

[0003] At present, there are mainly wet heat treatment methods for solid phase oils and fats, and micro-flotation and coarse granulation methods for floating oils and dispersed oils. However, the wet heat treatment method requires heating the kitchen waste to a high temperature of about 150°C, and the process energy consumption is relatively high; the coarse granulation method not only requires coarse granulation fillers, which increases equipment costs, but also requires strict control of process conditions to ensure the efficiency of oil recovery; although the micro-flotation method has a good effect, due to the large amount of solid phase substances in the kitchen waste slurry, it is easy to cause blockage of the microbubble generator. Therefore, if the oil is not separated when treating the garbage, but isolated by a substance, and participates in the degradation and fermentation process of organic matter in the later stage, and finally is hydrolyzed into small molecular organic matter simultaneously, it is a difficulty in current research.

[0004] The Chinese patent with publication number CN113877942B discloses a method for harmless treatment of kitchen waste, in which a combination of gravity separation and condensation is used to separate oil and water from kitchen waste, and the separated oil is processed into biodiesel or sent to a soap factory. This method also separates and treats oil separately, which is complex, energy-consuming and time-consuming.

[0005] The Chinese patent with the publication number CN102671918B discloses a biochemical treatment system for kitchen waste, wherein after the kitchen waste is pre-treated, a pulping fine particle treatment mode is adopted. During anaerobic treatment, the digestion rate of the anaerobic fermentation system can be effectively improved, the amount of biogas produced can be greatly reduced, and the amount of biogas can be increased; the garbage can be effectively converted into clean energy by anaerobic fermentation. However, the patent does not involve the treatment of grease, nor does it solve the problem that the fatty acids generated after the degradation of kitchen waste oil adhere to the surface of microorganisms, hindering the material transfer of the bacteria, and the undegraded grease wraps the bacteria, making the bacteria inactive. It also does not solve the problem that high salinity will cause the external osmotic pressure to increase, the activity of metabolic enzymes to decrease, and the growth of fine spores to be inhibited, thereby affecting the fermentation efficiency, and ultimately affecting the conversion efficiency of small molecular organic matter. Therefore, if the negative impact of high-fat and high-salt components in kitchen waste is solved, and the conversion rate of organic components in kitchen waste to small molecular organic matter is improved, it is a problem that needs to be solved urgently. Summary of the invention

[0006] In order to solve the above problems, the purpose of the present invention is to provide a method for wet heat catalysis of kitchen waste to solve one or more technical problems existing in the prior art and at least provide a beneficial choice or create conditions.

[0007] After the kitchen waste is treated with high temperature and high pressure thermal hydrolysis, the biological tissues and fine spore structures of the biological organisms in the waste are pulped, some organic macromolecular long-chain substances are decomposed, and some hydrophilic organic colloid substances are hydrolyzed. Soft substances such as plastics shrink or become fragments during the thermal hydrolysis process. The entire thermal hydrolysis process can complete the digestion and degradation of easily degradable organic matter in the kitchen waste, sterilization, dehydration, deodorization, and volume reduction. The wet heat catalytic method has the advantages of small footprint and short processing time, and is particularly suitable for kitchen waste with low calorific value, high water content, and unsorted. However, this method cannot reduce problems caused by oil feedback inhibition and organic acid metabolic stress during the treatment process.

[0008] Furthermore, the present invention proposes a method for treating kitchen waste by wet heat catalytic hydrolysis. The method combines supercritical steam wet heat catalytic hydrolysis, flotation adsorption technology and anaerobic fermentation technology to perform multi-level and all-round fine treatment of kitchen waste. The device includes a feeding and conveying bin, a high-pressure heating and stirring tank, a high-pressure heating reaction tank, a pipeline, a water pump, a critical steam generating device, a steam wet heat hydrolysis tank, a filter, a biocatalytic tank, a heating and stirring tank, and a packaging machine.

[0009] Among them, the method is provided with a conveyor belt behind the feeding and conveying bin, which is connected to a high-pressure heating and stirring tank after passing through a funnel. The inner layer of the high-pressure heating and stirring tank has a polytetrafluoroethylene coating. The high-pressure heating and stirring tank connecting pipeline is used to separate the solid and liquid substances in the system. The bottom pipeline is connected to the high-pressure wet heat catalytic hydrolysis tank, and the upper pipeline is connected to the high-pressure heating reaction tank through a filter screen. The high-pressure heating reaction tank is connected to the biocatalytic tank through a pipeline. The high-pressure wet heat catalytic hydrolysis tank is connected to a water pump and a supercritical steam generating device through a pipeline, and is connected to the biocatalytic tank, and is connected to the heating and stirring tank through a pipeline. The heating and stirring tank is connected to a packaging machine. For specific connections, see Figure 1 .

[0010] The hydrolysis tank is a low-temperature pressurized hydrolysis tank with Chinese patent publication number CN106269798B. The supercritical steam device is a low-temperature pressurized hydrolysis tank with Chinese patent publication number CN108249393B. The biocatalytic tank is a bio-enzyme catalytic chemical reaction tank device with Chinese patent publication number CN117903936B.

[0011] In order to treat kitchen waste in a multi-level and all-round manner, the method for treating kitchen waste by wet heat catalytic hydrolysis includes the following steps:

[0012] The first stage: pre-treatment of kitchen waste to obtain: an upper water layer containing grease, a middle slurry rich in organic matter, and a lower sediment;

[0013] The second step: After the oil in the upper water layer is treated by flotation adsorption technology, the oil is adsorbed by montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations to obtain a microsphere suspension with uniform oil dispersion;

[0014] The third step: the organic matter layer of the obtained middle slurry is subjected to wet heat treatment by supercritical steam wet heat catalytic hydrolysis to obtain the initially degraded organic matter;

[0015] The fourth step: all organic matter obtained after treatment is subjected to biocatalytic treatment to obtain small molecule organic acids;

[0016] The fifth step: harmless treatment of sediment.

[0017] First, the kitchen waste is pretreated to obtain: an upper water layer containing grease, a middle slurry rich in organic matter, and a lower sediment. The specific steps are:

[0018] S001, put the kitchen waste containing impurities (such as plastic, ceramic slag, glass slag, sand and gravel, etc.) into the waste treatment device through the feeding and conveying bin, and the kitchen waste is conveyed to the high-pressure heating mixing tank through the conveyor belt and the funnel.

[0019] S002, adding water to the kitchen waste in the high-pressure heating stirring tank, boiling it under high pressure for 3 to 5 hours for rapid disinfection, removing bacteria, viruses and other microorganisms contained in the kitchen waste, and quickly softening the organic matter contained in the kitchen waste for easy subsequent treatment. At the same time, rapid stirring is performed to initially crush the organic matter, and the food residues are crushed into kitchen waste slurry, so that light materials such as plastics and grease contained in the kitchen waste float up to obtain an upper water layer; the slurry suspended in the middle layer is obtained to obtain a middle layer slurry rich in organic matter; and the heavier materials such as glass slag, sand and gravel, ceramic slag, bones, shells and other organic-free materials are precipitated to obtain a lower sediment.

[0020] S003, the upper water layer containing grease and plastic is transported to a high-pressure heating stirring tank through a pipeline, a filter screen is set at the pipeline outlet, and during the transportation process, impurities such as plastic are intercepted by the filter screen at the pipeline outlet to obtain a water layer containing grease, and the water layer containing grease enters a high-pressure heating reaction tank, and the middle layer slurry rich in organic matter is transported to a high-pressure wet-heat hydrolysis tank through a pipeline.

[0021] When the temperature drops, the grease will partially solidify or become sticky. Because of its strong adhesion, it is easy to adhere to the pipe, or to the surface of biological enzymes or microorganisms during the fermentation catalysis process, which hinders the material transfer of the bacteria. Undegraded grease is also easy to wrap the bacteria, making them inactive. Therefore, the grease needs to be specially treated before entering the biocatalytic tank. The grease is adsorbed by montmorillonite loaded with β-cyclodextrin with quaternary ammonium salt cations, and the microsphere suspension that adsorbs the grease is evenly dispersed; specifically:

[0022] S101, dissolving β-cyclodextrin in deionized water to obtain a β-cyclodextrin solution, adding sodium hydroxide and stirring evenly to adjust the pH to 11.0-11.5, adding octadecyltrimethylammonium chloride, heating to 60° C., stirring fully, reacting for 1-2 hours, and obtaining a β-cyclodextrin solution having a quaternary ammonium salt cation,

[0023] S102, adding montmorillonite with a diameter of 80 to 100 nm to the β-cyclodextrin solution containing quaternary ammonium salt cations, so that the montmorillonite is fully dispersed in the solution, fully stirred, and reacted for 1 to 2 hours to obtain montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations, taking out the suspension, centrifuging at a speed of 3500 rpm, washing with deionized water 2 to 3 times to remove sodium hydroxide, centrifuging again, taking out the solid mixture at the bottom, drying and grinding at 60° C., and obtaining montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations;

[0024] The mass ratio of octadecyltrimethylammonium chloride to nano-montmorillonite is 1:1-2.

[0025] This is because octadecyltrimethylammonium chloride reacts with the hydroxyl group of β-cyclodextrin, causing β-cyclodextrin to contain a large amount of quaternary ammonium cations, and the cations in montmorillonite undergo ion exchange with the quaternary ammonium cations in β-cyclodextrin, resulting in montmorillonite loaded with β-cyclodextrin having quaternary ammonium cations. The modified montmorillonite can adsorb oil in water.

[0026] S103, adding montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations into a high-pressure heating reaction tank, at a high temperature of 80 to 90°C, the mesopores on the montmorillonite and cyclodextrin are opened, and the oil in the water layer is absorbed into the mesopores, stirred for 1 to 2 hours, and after sufficient adsorption, allowed to stand for 1 to 2 hours to obtain a microsphere suspension with uniform oil dispersion, which is then transferred to a biocatalytic tank through a pipeline.

[0027] Further, the organic matter layer of the middle slurry obtained in S002 is subjected to wet heat treatment, and all the obtained organic matter is subjected to biocatalytic treatment, the specific steps are:

[0028] S201, the middle layer pulp rich in organic matter should be transported to a high-pressure wet heat hydrolysis tank through a pipeline, and the wet heat catalytic hydrolysis tank is heated to a pressure of 1.2-2MPa and a temperature of 140-160°C to evaporate the water in the middle layer pulp to obtain dry organic matter, and a critical steam generating device is used to generate 140-160°C critical steam, which is transported to the high-pressure wet heat catalytic hydrolysis tank through a pipeline. At the same time, the system is stirred, and the organic matter in the system is sprayed multiple times in a short time to break its complex chemical bonds. The evaporation-steam spraying-uniform mixing process is repeated multiple times to decompose the cellulose in the system into small molecular cellulose, the starch into short-chain starch, and the protein into short-chain polypeptides, thereby obtaining initially degraded organic matter.

[0029] S202, the montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cation is dispersed in deionized water, sodium carbonate and citric acid are added to adjust the pH to 6.3-6.5, tryptophan and phenylalanine are added, and the reaction is carried out for 1-2 hours to make the surface of the montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cation load negative charge, and after completion, it is filtered, dried, ground and filtered with a 60-mesh filter cloth to obtain an active carrier with negative charge,

[0030] Wherein: the mass ratio of phenylalanine, tryptophan and montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cation is 2-5:4-8:15-20;

[0031] S203, under sterile conditions, oligosaccharide, negatively charged active carrier, and deionized water are prepared into a suspension, and then the composite bacteria are added, and the suspension is cultured at a constant temperature of 35 to 37°C and a shaking speed of 120 to 150 rpm / min for 3 to 6 hours; finally, a composite bacterial liquid is obtained; wherein the number of viable bacteria of Parabacillus is ≥10 10 CFU / g; the number of viable bacteria of commercial yeast powder is ≥10 9 CFU / g, the number of viable Bifidobacterium adolescentis ≥10 9 CFU / g;

[0032] The composite bacteria specifically include: yeast, Bifidobacterium adolescentis and Parabacillus, and the mass ratio thereof is 1-2:2-4:2-4;

[0033] According to the mass fraction, the oligosaccharide is 5 to 8 parts, the negatively charged active carrier is 30 to 35 parts, the deionized water is 40 to 50 parts, and the composite bacteria is 8 to 12 parts;

[0034] S204, at 35-37°C, the composite bacterial liquid is added to the biocatalytic tank, and protease, cellulase and lipase are added, and after stirring evenly, the montmorillonite suspension adsorbed with oil obtained in S103 is cooled to 35°C and added to the biocatalytic tank through a pipeline to react for 1-2 hours, and then water is added to the preliminarily degraded organic matter in S201 and mixed evenly, and then cooled to 35°C, and then added to the biocatalytic tank through a pipeline for further fermentation and degradation. After reacting for 24-30 hours, the liquid containing small molecule organic acids in the biocatalytic tank can be filtered through a filter through a pipeline and then transported to a heating stirring tank for further concentration and sterilization to obtain a high-concentration small molecule organic acid liquid.

[0035] Among them, the enzyme activity of amylase preparation is 40U / mg, the enzyme activity of protease preparation is 10U / mg, the enzyme activity of lipase preparation is 30U / mg, and the enzyme activity of cellulase preparation is 20U / mg. And the addition amount of protease, cellulase and lipase is 0.005-0.008 of the mass of kitchen waste;

[0036] S205, the difficult-to-treat lower layer sediment obtained in the high-pressure heating stirring tank is cleaned regularly, dried by a blast drying device, incinerated, and then ground to render it harmless.

[0037] The organic residue obtained by filtration in step S204 is dried by a blast drying device, incinerated, and then ground to render it harmless.

[0038] Kitchen waste has several significant advantages in producing small molecule organic acids. Kitchen waste is mainly composed of starch, protein, fat, cellulose and inorganic salts. Among these substances, starch and protein account for the largest proportion, about 60%, and oil accounts for about 15-30%.

[0039] Therefore, large amounts of sugars and starches can be easily utilized by the composite culture fluid, whereas cellulosic biomass must be pretreated under conditions that require large amounts of energy consumption. Furthermore, food waste also contains a large amount of functionalized molecules, namely proteins, fatty acids, and minerals, which can serve as nutrients to support the growth of microorganisms.

[0040] When grease floats in the kitchen waste slurry, due to its adhesiveness and non-degradability, it adheres to the surface of microorganisms, affecting the activity of microorganisms, thereby reducing the fermentation efficiency and affecting the fermentation products. When we adsorb grease with montmorillonite loaded with β-cyclodextrin with quaternary ammonium salt cations, when the ambient temperature drops, the grease is fixed on the montmorillonite. Because a large amount of quaternary ammonium salt cations are loaded on the montmorillonite, when the liquid environment becomes weakly acidic, part of the grease is slowly hydrolyzed into fatty acids. When the active carrier loaded with the composite bacteria is added to the environment, because the pH is 6.5 in the weakly acidic environment, the amino acids on the active carrier are amphoteric, making the surface of the active carrier present a negative charge. At this time, the montmorillonite loaded with β-cyclodextrin with quaternary ammonium salt cations that adsorbs a large amount of grease presents a positive charge, and the two will react first, so that the fatty acids are preferentially consumed as the energy source of the composite bacteria, and the other part of the fatty acids will also be preferentially degraded into small molecular organic acids by the composite bacteria. Tryptophan and phenylalanine contained in the active carrier can enhance the conversion and utilization of oil and fatty acids by the composite bacteria through synergistic effect, resulting in the generation of small molecular organic acids. At the same time, it can also promote the conversion of large molecular organic matter in the middle layer slurry into small molecular organic acids.

[0041] Furthermore, the addition of enzyme preparations can speed up the decomposition of the middle layer slurry from macromolecules to small molecules, which is beneficial to the utilization of small molecules by microorganisms, promotes the growth of strains, and thus is beneficial to the degradation of garbage. Therefore, the combined action of enzyme preparations and composite bacterial liquid can significantly increase the fermentation speed and degradation rate. It was found that: in the case of continuous addition of garbage, without adding enzyme preparations, the microbial agent directly degraded the kitchen waste, and the 24-hour degradation rate was 86.1%, while the combined action of enzyme preparations and composite bacterial liquid, the 24-hour degradation rate was 95.8%.

[0042] The effects of reaction temperature and residence time on the hydrothermal process were studied. At the same time, due to the understanding of the role of hydrogen ions in hydrothermal chemical reactions during the mechanism analysis, the weak acid as an additive promoted the formation of small molecular organic matter in the hydrothermal reaction process. In addition, the use of high-temperature steam to directly heat the kitchen waste can greatly shorten the heating time of traditional electric heating or other heating methods, achieve rapid heating, and avoid changes in organic matter in kitchen waste during the long heating process.

[0043] In the biocatalytic tank, because oil is used as energy to supply microorganisms, its decomposition speed is greatly accelerated. At the same time, due to the protective effect of the active carrier on the bacteria, the penetration of salt is greatly weakened even in a high-salt environment, so that the bacteria are protected by the surrounding oils and amino acids, which promotes the growth and reproduction of microorganisms.

[0044] pH is also one of the important factors affecting anaerobic fermentation. Different microorganisms have different optimal growth pH ranges. The optimal pH value of composite bacteria is between 6.0 and 6.5. Changes in pH can easily cause changes in the fermentation process. If the pH is reduced significantly, it will cause changes in the composition of the acidified end products and seriously reduce the activity of the composite bacteria, resulting in "acidosis". The control of pH at each stage of the anaerobic fermentation process directly affects the activity of the anaerobic microbial flora, so it is very important to maintain the acid-base balance of the system. The active carrier and montmorillonite loaded with β-cyclodextrin having quaternary ammonium cations can provide OH groups, so that the pH value of the environment is maintained between 6.0 and 6.5, thereby avoiding acidosis.

[0045] Oil or fat is a degradable substance. Generally speaking, its hydrolysis rate is very slow, lagging behind sugars and proteins. Oil is a complex substance composed of glycerol and higher fatty acids. At room temperature, the liquid is called oil, and the solid is called fat. It is relatively stable in nature, and the speed of microorganisms absorbing and utilizing it is also relatively slow. After the above-mentioned pretreatment, under the action of positive and negative charges, the composite bacteria and the montmorillonite adsorbed with a large amount of oil react preferentially. Under the action of microbial exospore enzymes, the oil is first hydrolyzed into fatty acids and glycerol. Glycerol is also called glycerol. In the body of the microorganism, in addition to the substances absorbed and utilized by the microorganism to be converted into fine spores, it is mainly decomposed into pyruvate. Under anaerobic conditions, pyruvate is further decomposed into short-chain organic substances such as propionic acid, butyric acid, succinic acid, and ethanol. Fatty acids are oxidized in the microbial fine spores, causing carbon atoms to continuously break off from the fatty acid chain in pairs to form acetyl coenzyme. Under anaerobic conditions, acetyl coenzyme is then converted into low molecular weight organic acids such as acetic acid. Ultimately, oily substances are also rapidly decomposed and degraded into small molecular organic acids.

[0046] Under hydrothermal conditions, the use of thermochemical treatment methods with the addition of liquid acid, alkaline catalyst or organic acid can further improve the depolymerization efficiency of macromolecular organic matter and significantly shorten the hydrothermal reaction cycle. In addition, in the acid production stage of biocatalysis, the residual alkali solution in the hydrolyzate can also prevent the rapid decrease of pH value to ensure the biochemical reaction environment required for normal metabolism of microorganisms. In general, oils and fats are passively transported by microorganisms and transferred across the membrane to the microspores, becoming organic matter that is preferentially degraded by microbial biochemical transformation, providing sufficient energy supply for microbial growth in the initial stage of fermentation. The increase in soluble fatty acids also ensures sufficient carbon sources for microbial metabolism, so that in the entire biocatalytic system, oils and fatty acids, as well as macromolecular organic matter in garbage slurry can be quickly degraded by composite bacteria, and finally more small molecular organic acids are obtained, thereby improving the utilization rate of kitchen waste.

[0047] β-cyclodextrin has a cavity structure that is hydrophobic inside and hydrophilic outside. The cavity structure of β-cyclodextrin can be used as the catalytic active area, and the polyhydroxy structure outside the cavity can interact with the substrate montmorillonite. As an adsorbent, the lipophilic microspheres with OH group binding sites and quaternary ammonium salt catalytic sites can have a strong adsorption effect on long-chain oils and fats. When used as an active carrier, it has an OH group binding site and an amino acid COO group, double active points, which enhances the activity of the composite strains. Improve its ability to interact with oils and fats. And further promote the degradation of proteins and sugars in organic matter. At the same time, montmorillonite and β-cyclodextrin have micro-mesoporous structures. The fatty acids produced by hydrolysis can enter the mesopores and contact the active sites, which strengthens the hydrolysis rate and thus increases the degradation rate. At the same time, the diffusion path length of reactants and products is reduced, thereby inhibiting secondary reactions, solving the problem of oil adhesion and microbial inactivation. More importantly, alkali treatment and amino acid activation make it easier for macromolecular oils to enter the pore structure of montmorillonite, promote the uniform dispersion of oils, and fully contact with the composite bacteria to be quickly degraded and consumed. This further improves the utilization rate and degradation rate of oils.

[0048] The high content of organic matter in kitchen waste can easily cause a rapid drop in pH, so controlling pH during the reaction is a very important task. The active carrier, due to its special amphoteric structure, can release OH groups when pH drops rapidly, thus playing a short-term regulatory role and avoiding acidosis.

[0049] Kitchen waste contains high salt content, which inhibits the reproduction of microorganisms. Bacteria that are not protected by active carriers are prone to decreased activity in high-salt environments. When composite bacteria are protected by active carriers, the impact of salt on microbial activity can be effectively avoided.

[0050] This method proposes a technology for treating kitchen waste by using critical steam wet heat catalytic hydrolysis as the main method. Compared with the prior art, the invention has the following beneficial effects:

[0051] 1) The present invention proposes a method for treating kitchen waste by supercritical steam catalytic hydrolysis, which combines supercritical steam catalytic hydrolysis, flotation adsorption technology and anaerobic fermentation technology to perform multi-level and all-round fine treatment on kitchen waste. The kitchen waste is pretreated to obtain: an upper water layer containing grease, a middle slurry rich in organic matter and a lower sediment. The grease in the upper water layer is adsorbed by montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations to obtain a microsphere suspension with uniform grease dispersion; the problem that high grease in kitchen waste inhibits the degradation efficiency of kitchen waste or the speed of anaerobic fermentation is solved, and the grease is made into energy in the biocatalytic link, which is preferentially consumed and degraded, creatively solving the problem that grease is not easy to degrade and is easily attached to microorganisms and inactivated. The organic matter in the kitchen waste is converted into small-particle, small-molecule organic acids to the greatest extent, making it easy to reuse. 2) Three salt-tolerant bacteria, namely yeast, oceanic bacillus and parabacillus, are selected as composite bacteria, and the composite bacteria are loaded on an active carrier. Through the synergistic effect of amino acids, the composite bacteria are loaded in the micro-mesoporous structure of montmorillonite and β-cyclodextrin, which further protects the activity of the composite bacteria and prevents its activity from being weakened in a high-salt environment. And through the negatively charged active carrier and the positively charged oil microspheres, through the action of positive and negative charges, the negatively charged active carrier and the positively charged oil microspheres are more fully in contact with the oil, which is more conducive to the consumption and degradation of the oil and increases the degradation rate.

[0052] 3) The kitchen waste treatment method designed by the present invention does not produce any toxic or harmful substances during the production process, effectively avoiding the problems of producing unpleasant odors, complex treatment processes, the spread of germs caused by the fermentation of kitchen waste, waste of manpower and material resources in storage and logistics, and damage to the treatment device in the current kitchen waste treatment process. The problem of kitchen waste contaminating and clogging the waste treatment device in the existing kitchen waste treatment method is solved, and the problems of high energy consumption, low waste treatment efficiency, and low organic matter reuse rate in the current kitchen waste treatment process are solved. The method is low-cost, can maximize the utilization of resources, and effectively reduce energy consumption.

[0053] 4) The kitchen waste treatment technology proposed in the present invention can catalyze most of the organic matter in the kitchen waste into small molecule organic acids in an environmentally friendly way, and has products with high economic value, so that the parts of the kitchen waste that are difficult to handle and reuse are fully utilized, and its resource utilization rate is high, and it has certain economic and environmental benefits. The catalytic process described in the present invention is relatively simple, has low energy consumption, the required equipment structure is simple, and the equipment investment cost is low, which is very suitable for large-scale batch production. In the production process described in the present invention, a new supercritical steam catalytic process is used. This process can make organic matter preliminarily decompose in a short time by only using steam, has high catalytic efficiency and is relatively environmentally friendly, and does not require additional large amounts of catalysts, which can effectively reduce costs. In addition, the strains in the present invention can be screened by subculture from a biological fermentation tank, and the strains can be reused, effectively reducing the cost of kitchen waste treatment. The method is easy to promote, easy to realize assembly line operation and large-scale industrial production, and has various ways to treat kitchen waste. According to different needs, the kitchen waste can be catalytically hydrolyzed into a variety of substances rich in organic matter, such as biodiesel, small molecule alcohol substances, and small molecule organic acids. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 :Process flow chart of treating kitchen waste by wet heat catalytic hydrolysis;

[0055] Figure 2 : Electron microscopic image of the composite bacterial liquid degrading oil microspheres; DETAILED DESCRIPTION

[0056] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content described in the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0057] Example 1

[0058] 200 portions of kitchen waste are taken and pre-treated, and the specific steps are as follows: the kitchen waste is fed into a waste treatment device through a feeding and conveying bin, and the kitchen waste is conveyed to a high-pressure heating stirring tank through a conveyor belt and a funnel; water is added to the kitchen waste in the high-pressure heating stirring tank, and the mixture is boiled for 3 hours for rapid disinfection, and the organic matter contained in the kitchen waste is rapidly softened, and at the same time, rapid stirring is performed to initially crush the organic matter, and the food residues are crushed into kitchen waste slurry, so that the plastic and grease contained in the kitchen waste float to obtain an upper water layer; the upper water layer containing grease and plastic is conveyed to the high-pressure heating stirring tank through a pipeline, and a filter is arranged at the outlet of the pipeline, and during the conveying process, plastic impurities are intercepted by the filter at the outlet of the pipeline to obtain a water layer containing grease, and the water layer containing grease enters the high-pressure heating stirring tank.

[0059] Further, the oil in the upper water layer is treated, and the oil is adsorbed by montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations to obtain a microsphere suspension in which the oil is evenly dispersed; specifically:

[0060] Dissolve 5 parts of β-cyclodextrin in 95 parts of deionized water to obtain a 5% β-cyclodextrin solution, add sodium hydroxide and stir evenly to adjust the pH to 11.2, add 5 parts of octadecyltrimethylammonium chloride, raise the temperature to 60° C., stir well, and react for 2 hours to obtain a β-cyclodextrin solution with quaternary ammonium salt cations;

[0061] Into the β-cyclodextrin solution containing quaternary ammonium salt cation, 10 parts of montmorillonite with a diameter of 80-100 nm are added to fully disperse the montmorillonite in the solution, fully stirred, and reacted for 2 hours to obtain montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cation, the suspension is taken out and centrifuged at a speed of 3500 rpm, washed with deionized water for 3 times to remove sodium hydroxide, and then centrifuged again, the solid mixture at the bottom is taken out, and dried and ground at 60° C. to obtain montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cation;

[0062] 10 parts of montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations were added to a high-pressure heating reaction tank. At a high temperature of 90°C, the mesopores on the montmorillonite and cyclodextrin opened, and the oil in the water layer was absorbed into the mesopores. The mixture was stirred for 2 hours. After sufficient adsorption, it was allowed to stand for 2 hours to obtain a uniformly dispersed microsphere suspension adsorbing oil.

[0063] The middle slurry layer rich in organic matter is subjected to wet heat treatment, and all organic matter obtained in the second and third stages is subjected to biocatalytic treatment. The specific steps are as follows:

[0064] The middle layer pulp rich in organic matter is transported to a high-pressure wet heat catalytic hydrolysis tank through a pipeline, and the high-pressure wet heat catalytic hydrolysis tank is heated to a pressure of 1.2 MPa and a temperature of 140°C to evaporate the water in the middle layer pulp to obtain dry organic matter, and a critical steam generating device is used to generate 160°C critical steam, which is transported to the high-pressure wet heat hydrolysis tank through a pipeline, and the system is stirred at the same time, and the organic matter in the system is sprayed multiple times in a short time to break its complex chemical bonds, and the evaporation-steam spraying-uniform mixing process is repeated multiple times to decompose the cellulose in the system into small molecular cellulose, the starch into short-chain starch, and the protein into short-chain polypeptides, thereby obtaining initially degraded organic matter;

[0065] 15 parts of montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations are dispersed in deionized water, sodium carbonate and citric acid are added to adjust the pH to 6.3, 8 parts of tryptophan and 2 parts of phenylalanine are added, and the reaction is carried out for 2 hours, so that the surface of the montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations is negatively charged, and after completion, it is filtered, dried, ground, and filtered with a 60-mesh filter cloth to obtain a negatively charged active carrier;

[0066] Take 1 part of yeast, 3 parts of oceanic bacillus and 4 parts of parabacillus to obtain a composite strain;

[0067] Under sterile conditions, 8 parts of oligosaccharide, 35 parts of negatively charged active carrier, and 40 parts of deionized water were prepared into a suspension, and then 8 parts of composite bacteria were added, and constant temperature anaerobic shaking culture was carried out for 4 hours, the culture temperature was 35°C, and the shaking culture speed was 150rpm / min; the composite bacteria liquid was prepared;

[0068] At 35°C, 20 parts of the composite bacterial liquid are added to a biocatalytic tank, and 1 part of protease, 1.6 parts of cellulase and 1 part of lipase are added, and after stirring evenly, the obtained microsphere suspension with evenly dispersed oil is cooled to 35°C and added to the biocatalytic tank through a pipeline to react for 2 hours, and then the preliminarily degraded organic matter is added with water and mixed evenly, and then cooled to 35°C, and then added to the biocatalytic tank through a pipeline for further fermentation and degradation. After reacting for 24 hours, the liquid containing small molecular organic acids in the biocatalytic tank is filtered through a filter screen through a pipeline and transported to a heating stirring tank for further concentration and sterilization to obtain a high-concentration small molecular organic acid liquid, which enters a packaging tank;

[0069] Finally, the lower sediment and the filtered organic residue are dried with an air drying device, incinerated, and then ground to render them harmless.

[0070] Example 2

[0071] 200 portions of kitchen waste are taken and pre-treated, and the specific steps are as follows: the kitchen waste is fed into a waste treatment device through a feeding and conveying bin, and the kitchen waste is conveyed to a high-pressure heating stirring tank through a conveyor belt and a funnel; water is added to the kitchen waste in the high-pressure heating stirring tank, and the mixture is boiled for 4 hours for rapid disinfection, and the organic matter contained in the kitchen waste is rapidly softened, and at the same time, rapid stirring is performed to initially crush the organic matter, and the food residues are crushed into kitchen waste slurry, so that the plastic and grease contained in the kitchen waste float to obtain an upper water layer; the upper water layer containing grease and plastic is conveyed to the high-pressure heating stirring tank through a pipeline, and a filter is arranged at the outlet of the pipeline, and during the conveying process, plastic impurities are intercepted by the filter at the outlet of the pipeline to obtain a water layer containing grease, and the water layer containing grease enters the high-pressure heating stirring tank.

[0072] Further, the oil in the upper water layer is treated, and the oil is adsorbed by montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations to obtain a microsphere suspension in which the oil is evenly dispersed; specifically:

[0073] 8 parts of β-cyclodextrin are dissolved in 92 parts of deionized water to obtain an 8% β-cyclodextrin solution, sodium hydroxide is added and stirred to adjust the pH to 11.5, 16 parts of octadecyltrimethylammonium chloride are added, the temperature is raised to 60° C., the mixture is stirred sufficiently, and the reaction is performed for 2 hours to obtain a β-cyclodextrin solution having a quaternary ammonium salt cation;

[0074] 32 parts of montmorillonite with a diameter of 80 to 100 nm are added to a β-cyclodextrin solution containing a quaternary ammonium salt cation, the montmorillonite is fully dispersed in the solution, the mixture is fully stirred, and the mixture is reacted for 2 hours to obtain montmorillonite loaded with β-cyclodextrin having a quaternary ammonium salt cation, the suspension is taken out and centrifuged at a speed of 3500 rpm, the suspension is washed with deionized water for 3 times to remove the sodium hydroxide, the suspension is centrifuged again, the solid mixture at the bottom is taken out, and the mixture is dried and ground at 60° C. to obtain montmorillonite loaded with β-cyclodextrin having a quaternary ammonium salt cation;

[0075] 20 parts of montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations were added to a high-pressure heating reaction tank. At a high temperature of 85°C, the mesopores on the montmorillonite and cyclodextrin opened, and the oil in the water layer was absorbed into the mesopores. The mixture was stirred for 2 hours. After sufficient adsorption, it was allowed to stand for 2 hours to obtain a uniformly dispersed microsphere suspension adsorbing oil.

[0076] The middle slurry layer rich in organic matter is subjected to wet heat treatment, and all organic matter obtained in the second and third stages is subjected to biocatalytic treatment. The specific steps are as follows:

[0077] The middle layer pulp rich in organic matter is transported to a high-pressure wet heat catalytic hydrolysis tank through a pipeline, and the high-pressure wet heat catalytic hydrolysis tank is heated to a pressure of 1.5 MPa and a temperature of 140°C to evaporate the water in the middle layer pulp to obtain dry organic matter, and a critical steam generating device is used to generate 160°C critical steam, which is transported to the high-pressure wet heat hydrolysis tank through a pipeline, and the system is stirred at the same time, and the organic matter in the system is sprayed multiple times in a short time to break its complex chemical bonds, and the evaporation-steam spraying-uniform mixing process is repeated multiple times to decompose the cellulose in the system into small molecular cellulose, the starch into short-chain starch, and the protein into short-chain polypeptides, thereby obtaining initially degraded organic matter;

[0078] 20 parts of montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations are dispersed in deionized water, sodium carbonate and citric acid are added to adjust the pH to 6.5, 4 parts of tryptophan and 5 parts of phenylalanine are added, and the reaction is carried out for 2 hours, so that the surface of the montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations is negatively charged, and after completion, it is filtered, dried, ground, and filtered with a 60-mesh filter cloth to obtain a negatively charged active carrier;

[0079] Take 4 parts of yeast, 8 parts of oceanic bacillus and 8 parts of parabacillus to obtain a composite strain;

[0080] Under sterile conditions, 8 parts of oligosaccharide, 30 parts of negatively charged active carrier, and 50 parts of deionized water were prepared into a suspension, and then 12 parts of the composite bacteria were added, and the mixture was cultured at a constant temperature for 4 hours under anaerobic shaking, at a culture temperature of 35°C and a shaking culture speed of 150 rpm / min; a composite bacteria liquid was obtained;

[0081] At 35°C, 10 parts of the composite bacterial liquid are added to a biocatalytic tank, and 1.6 parts of protease, 1.6 parts of cellulase and 1 part of lipase are added, and after stirring evenly, the obtained microsphere suspension with evenly dispersed oil is cooled to 35°C and added to the biocatalytic tank through a pipeline to react for 2 hours, and then the preliminarily degraded organic matter is added with water and mixed evenly, and then cooled to 35°C, and then added to the biocatalytic tank through a pipeline for further fermentation and degradation. After reacting for 30 hours, the liquid containing small molecular organic acids in the biocatalytic tank is filtered through a filter screen through a pipeline and transported to a heating stirring tank for further concentration and sterilization to obtain a high-concentration small molecular organic acid liquid, which enters a packaging tank;

[0082] Finally, the lower sediment and the filtered organic residue are dried with an air drying device, incinerated, and then ground to render them harmless.

[0083] Example 3

[0084] 200 portions of kitchen waste are taken and pre-treated, and the specific steps are as follows: the kitchen waste is fed into a waste treatment device through a feeding and conveying bin, and the kitchen waste is conveyed to a high-pressure heating stirring tank through a conveyor belt and a funnel; water is added to the kitchen waste in the high-pressure heating stirring tank, and the mixture is boiled for 5 hours for rapid disinfection, and the organic matter contained in the kitchen waste is rapidly softened, and at the same time, rapid stirring is performed to initially crush the organic matter, and the food residues are crushed into kitchen waste slurry, so that the plastic and grease contained in the kitchen waste float to obtain an upper water layer; the upper water layer containing grease and plastic is conveyed to the high-pressure heating stirring tank through a pipeline, and a filter is arranged at the outlet of the pipeline, and during the conveying process, plastic impurities are intercepted by the filter at the outlet of the pipeline to obtain a water layer containing grease, and the water layer containing grease enters the high-pressure heating stirring tank.

[0085] Further, the oil in the upper water layer is treated, and the oil is adsorbed by montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations to obtain a microsphere suspension in which the oil is evenly dispersed; specifically:

[0086] Dissolve 6 parts of β-cyclodextrin in 94 parts of deionized water to obtain a 6% β-cyclodextrin solution, add sodium hydroxide and stir evenly to adjust the pH to 11.0, add 10 parts of octadecyltrimethylammonium chloride, raise the temperature to 60° C., stir well, and react for 2 hours to obtain a β-cyclodextrin solution with quaternary ammonium salt cations;

[0087] 18 parts of montmorillonite with a diameter of 80 to 100 nm are added to a β-cyclodextrin solution containing a quaternary ammonium salt cation, the montmorillonite is fully dispersed in the solution, the mixture is fully stirred, and the mixture is reacted for 2 hours to obtain montmorillonite loaded with β-cyclodextrin having a quaternary ammonium salt cation, the suspension is taken out and centrifuged at a speed of 3500 rpm, the suspension is washed with deionized water for 3 times to remove the sodium hydroxide, the suspension is centrifuged again, the solid mixture at the bottom is taken out, and the mixture is dried and ground at 60° C. to obtain montmorillonite loaded with β-cyclodextrin having a quaternary ammonium salt cation;

[0088] 15 parts of montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations were added to a high-pressure heating reaction tank. At a high temperature of 80°C, the mesopores on the montmorillonite and cyclodextrin opened, and the oil in the water layer was absorbed into the mesopores. The mixture was stirred for 2 hours. After sufficient adsorption, it was allowed to stand for 2 hours to obtain a uniformly dispersed microsphere suspension adsorbing oil.

[0089] The middle slurry layer rich in organic matter is subjected to wet heat treatment, and all organic matter obtained in the second and third stages is subjected to biocatalytic treatment. The specific steps are as follows:

[0090] The middle layer slurry rich in organic matter is transported to a high-pressure wet heat catalytic hydrolysis tank through a pipeline, and the high-pressure wet heat catalytic hydrolysis tank is heated to a pressure of 2.0 MPa and a temperature of 140°C to evaporate the water in the middle layer slurry to obtain dry organic matter, and a critical steam generating device is used to generate 160°C critical steam, which is transported to the high-pressure wet heat hydrolysis tank through a pipeline, and the system is stirred at the same time, and the organic matter in the system is sprayed multiple times in a short time to break its complex chemical bonds, and the evaporation-steam spraying-uniform mixing process is repeated multiple times to decompose the cellulose in the system into small molecular cellulose, the starch into short-chain starch, and the protein into short-chain polypeptides, thereby obtaining initially degraded organic matter;

[0091] 18 parts of montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations are dispersed in deionized water, sodium carbonate and citric acid are added to adjust the pH to 6.5, 6 parts of tryptophan and 3 parts of phenylalanine are added, and the reaction is carried out for 2 hours, so that the surface of the montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations is negatively charged, and after completion, it is filtered, dried, ground, and filtered with a 60-mesh filter cloth to obtain a negatively charged active carrier;

[0092] Take 2 parts of yeast, 4 parts of oceanic bacillus and 4 parts of parabacillus to obtain a composite strain;

[0093] Under sterile conditions, 6 parts of oligosaccharide, 32 parts of negatively charged active carrier, and 45 parts of deionized water were prepared into a suspension, and then 10 parts of the composite bacteria were added, and the mixture was cultured at a constant temperature for 4 hours under anaerobic shaking, at a culture temperature of 35°C and a shaking culture speed of 150 rpm / min; a composite bacteria liquid was obtained;

[0094] At 35°C, 15 parts of the composite bacterial liquid are added to a biocatalytic tank, and 1.0 part of protease, 1.6 parts of cellulase and 1.6 parts of lipase are added, and after stirring evenly, the obtained microsphere suspension with evenly dispersed oil is cooled to 35°C and added to the biocatalytic tank through a pipeline to react for 2 hours, and then the preliminarily degraded organic matter is added with water and mixed evenly, and then cooled to 35°C, and then added to the biocatalytic tank through a pipeline for further fermentation and degradation. After reacting for 30 hours, the liquid containing small molecular organic acids in the biocatalytic tank is filtered through a filter screen through a pipeline and transported to a heating stirring tank for further concentration and sterilization to obtain a high-concentration small molecular organic acid liquid, which enters a packaging tank;

[0095] Finally, the lower sediment and the filtered organic residue are dried with an air drying device, incinerated, and then ground to render them harmless.

[0096] Comparative Example 1, the upper layer of fat in the high pressure heating reaction tank is directly added to the biocatalytic tank without treatment, and the rest is the same as Example 1;

[0097] Comparative Example 2: The composite bacteria were directly added into the biochemical catalytic tank according to the proportion, and the active carrier was not modified to form a composite bacteria liquid. Others were the same as in Example 1.

[0098] In comparative example 3, the upper layer of oil in the high-pressure heating reaction tank is saponified with sodium bicarbonate, acetic acid is added to generate fatty acids, and then added to the biocatalytic tank. The composite bacteria are directly added to the biochemical catalytic tank according to proportion, and the active carrier is not modified to form a composite bacteria liquid. The rest is the same as in example 1.

[0099] Experimental effect comparison data

[0100] 1. Survival rate of composite bacterial culture solution in high salt environment

[0101] For the composite bacterial liquid prepared in Example 1-3,

[0102] 8 parts of oligosaccharide and 50 parts of deionized water were prepared into a suspension, and then 12 parts of the composite bacteria were added, and the mixture was cultured at a constant temperature for 4 hours under anaerobic shaking, at a temperature of 35° C. and a shaking speed of 150 rpm / min; a composite bacteria liquid A was obtained, without adding an active carrier, and the rest was the same as in Example 1;

[0103] 10 portions of the above composite bacterial liquid were inoculated into a 20% NaCl aqueous solution and placed for 5 hours and 24 hours. The survival rate of the live bacteria was measured, as shown in Table 1:

[0104] It can be seen that without the protection of negatively charged active carriers, the number of active bacteria in a high-salt environment will decrease by more than 50% after 5 hours, and there will be almost no active bacteria after 24 hours. Under the protection of negatively charged active carriers, at least 80% of the active bacteria in the composite bacterial liquid exist because of the presence of certain nutrients and the synergistic effect of amino acids. Without the protection of active carriers, even if the three selected bacterial strains are salt-tolerant, most of the active bacterial strains will slowly lose their activity in salt water as high as 20%, and it will be difficult for them to survive for a long time.

[0105] Table 1 Record of viable bacteria count in each sample (CFU / g)

[0106] project Number of live bacteria after 5 hours of storage Live bacteria count after 24 hours Example 1 <![CDATA[6.42×10 9 ]]> <![CDATA[6.25×10 8 ]]> Example 2 <![CDATA[9.62×10 9 ]]> <![CDATA[7.82×10 8 ]]> Example 3 <![CDATA[4.19×10 9 ]]> <![CDATA[5.97×10 8 ]]> Composite bacterial liquid A <![CDATA[1.73×10 5 ]]> <![CDATA[5.97×10 2 ]]>

[0107] 2. Monitoring records of oil content in kitchen waste

[0108] The GC-MS test was performed on the oil content in the upper water layer in Example 1-3 and Comparative Example 1-3 using a gas chromatograph-mass spectrometer from Shimadzu Corporation, Japan. The oil content in the bottom liquid of the suspension after oil treatment and before entering the biocatalytic tank in Example 1-3 and Comparative Example 1-3 was also tested. The records are shown in Table 2;

[0109] GC conditions: Rtx-5MS capillary column (30m×0.25mm×0.25μm); temperature program: initial temperature 50℃, maintained for 2min, increased to 200℃ at 3℃ / min; then increased to 250℃ at 20℃ / min, maintained for 5min; continued to increase to 280℃ at 15℃ / min, maintained for 10min. Carrier gas was helium, flow rate was 1mL / min, split injection, split ratio was 40:1, injection port temperature was 280℃.

[0110] MS conditions: EI ion source, electron energy 70 eV; interface temperature 280 °C, ion source temperature 250 °C, solvent-free cutting time.

[0111] Table 2 Monitoring records of oil content in kitchen waste

[0112]

[0113] As can be seen from Table 2, because Examples 1-3 use flotation adsorption technology and use montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations, at a high temperature of 80°C, the mesopores on the montmorillonite and cyclodextrin open, absorbing the oil in the water layer into the mesopores, and then cooling to 35°C, only a trace amount of oil exists in the bottom liquid of the suspension. The amount of oil is very small and will not inhibit the degradation efficiency of kitchen waste, nor will it affect the anaerobic fermentation rate by adhesion and wrapping of microorganisms. From the electron microscope image of the fermented microparticles taken out of the biocatalytic tank, see Figure 2 It can also be seen that the interaction between the active carrier and the evenly dispersed microspheres adsorbed with oil makes the bacterial microorganisms multiply in large numbers between the microspheres, promoting the entire fermentation and degradation process. However, in Comparative Examples 1 and 3 where the oil was not treated, when the temperature dropped to 35°C, a large amount of oil solid matter was free in the suspension, which would cover the bacteria, seriously affecting the fermentation speed and inhibiting the degradation efficiency of kitchen waste.

[0114] 3. Degradation performance of kitchen waste by wet heat catalytic hydrolysis

[0115] High performance liquid chromatography was used, chromatographic column: Agilent ZORBAXSB-C18 column (5μm×4.6mm×250mm), mobile phase was methanol: KH2PO4 buffer solution (20mmol / L, pH2.6) = 5:95, detection wavelength was 197nm, column temperature was 25°C, injection volume was 20μL, flow rate was 0.8mL / min, high concentration small molecule organic acid liquid obtained in the heated stirring tank in Examples 1-3 and Comparative Examples 1-3 was qualitatively and quantitatively analyzed, and the test results are shown in Table 3. The acid production is the output of the organic small molecule acid obtained after the treatment of kitchen waste, mainly formic acid and butyric acid, to the corresponding kitchen waste mass, that is, how many grams of organic small molecule acid can be produced per kilogram of kitchen waste. See Table 3;

[0116] Table 3 Degradation performance of kitchen waste by wet heat catalytic hydrolysis

[0117]

[0118] As can be seen from Table 3, in Examples 1-3, because the active carrier interacts with the evenly dispersed microspheres adsorbing grease, the microbial strains can also reproduce rapidly in a high-salt environment, accelerating the speed of anaerobic fermentation, and also making the grease preferentially degraded by microorganisms, increasing the acid production, and significantly promoting the degradation efficiency of the entire system. In Comparative Example 1, because the grease is not pre-treated, the grease cannot be degraded in the entire system, the acid production decreases, and the fermentation speed is affected, so that the degradation rate is also reduced by half. In Comparative Example 2, because the active carrier is not used, the strain is quickly inactivated in a high-salt environment, and the fermentation speed is slowed down, thereby affecting the degradation rate of the entire system. In Comparative Example 3, because the pretreatment of grease cannot completely make the grease preferentially degraded, and it will also appear in the case of low temperature, the grease wraps the microorganisms, inhibiting the degradation efficiency of the entire system, and the active strains of this system are inactivated in large quantities without the protection of the active carrier in the superimposed composite strains, which makes the fermentation speed of the entire system slower and the degradation rate lower. Therefore, the present invention adopts a method for treating kitchen waste by wet heat catalytic hydrolysis, combining supercritical steam wet heat catalytic hydrolysis, flotation adsorption technology and anaerobic fermentation technology, which can perform multi-level and all-round fine treatment of kitchen waste, and can significantly improve the acid production and degradation efficiency, providing an advanced and effective method for treating kitchen waste.

[0119] The above description is only used to illustrate the technical solution of the present invention rather than to limit it. Any equal modifications and changes made to the technical solution of the present invention by ordinary persons in the art, as long as they do not deviate from the overall concept of the present invention, are still within the scope of the present invention.

Claims

1. A method for treating kitchen waste by wet heat catalytic hydrolysis, characterized in that: The method for treating kitchen waste by wet heat catalytic hydrolysis is to use supercritical steam wet heat catalytic hydrolysis, flotation adsorption technology and anaerobic fermentation technology to treat kitchen waste by wet heat catalytic hydrolysis; The method for treating kitchen waste by wet heat catalytic hydrolysis comprises the following steps: The first stage: pre-treatment of kitchen waste to obtain: an upper water layer containing grease, a middle slurry containing organic matter and a lower sediment; The second step: After the oil in the upper water layer is treated by flotation adsorption technology, the oil is adsorbed by montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations to obtain a microsphere suspension with uniform oil dispersion; The third step: the organic matter layer of the obtained middle slurry is subjected to wet heat treatment by supercritical steam wet heat catalytic hydrolysis to obtain the initially degraded organic matter; The fourth step: all organic matter obtained after treatment is subjected to biocatalytic treatment to obtain small molecule organic acids; The fifth step: harmless treatment of sediment.

2. The method for treating kitchen waste by wet heat catalytic hydrolysis according to claim 1, characterized in that: in, The device for processing kitchen waste includes a feeding and conveying bin, a high-pressure heating and stirring tank, a high-pressure heating and reaction tank, a pipeline, a water pump, a critical steam generating device, a steam wet heat hydrolysis tank, a filter screen, a biocatalytic tank, a heating and stirring tank, and a packaging machine; Specifically: a conveyor belt is provided behind the feeding and conveying bin, which is connected to a high-pressure heating and stirring tank after passing through a funnel. The inner layer of the high-pressure heating and stirring tank has a polytetrafluoroethylene coating. A pipeline is connected behind the high-pressure heating and stirring tank to separate the solid and liquid substances in the system. The bottom pipeline is connected to the high-pressure wet heat catalytic hydrolysis tank, and the upper pipeline is connected to the high-pressure heating reaction tank through a filter. The high-pressure heating reaction tank is connected to the biocatalytic tank and the high-pressure wet heat catalytic hydrolysis tank through a pipeline. The water pump is connected to the supercritical steam generating device through a pipeline, and is connected to the biocatalytic tank, and is connected to the heating stirring tank through a pipeline. The heating stirring tank is connected to the packaging machine.

3. The method for treating kitchen waste by wet heat catalytic hydrolysis according to claim 1, characterized in that: The pretreatment of kitchen waste obtains: an upper water layer containing grease, a middle slurry containing organic matter, and a lower sediment. The specific steps are: S001, feeding the kitchen waste containing impurities into the waste treatment device through the feeding and conveying bin, and the kitchen waste is conveyed to the high-pressure heating and stirring tank through the conveyor belt and the funnel; S002, adding water to the kitchen waste in the high-pressure heating stirring tank, boiling for 3 to 5 hours, quickly disinfecting, and quickly softening the organic matter contained in the kitchen waste, and at the same time, quickly stirring to initially crush the organic matter, crushing the food residue into kitchen waste slurry, making the plastic and grease contained in the kitchen waste float to obtain an upper water layer; suspending the slurry in the middle layer to obtain a middle layer slurry rich in organic matter; and precipitating glass slag, sand and gravel, ceramic slag, bones, shells and other heavy substances without organic matter to obtain a lower sediment; S003, the upper water layer containing grease and plastic is transported to a high-pressure heating stirring tank through a pipeline, a filter screen is set at the pipeline outlet, and during the transportation process, plastic impurities are intercepted by the filter screen at the pipeline outlet to obtain a water layer containing grease, and the water layer containing grease enters a high-pressure heating reaction tank; the middle layer slurry rich in organic matter is transported to a high-pressure wet heat catalytic hydrolysis tank through a pipeline.

4. The method for treating kitchen waste by wet heat catalytic hydrolysis according to claim 1, characterized in that: The oil in the upper water layer is treated, and the oil is adsorbed by montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations to obtain a microsphere suspension in which the oil is evenly dispersed; specifically: S101, dissolving β-cyclodextrin in deionized water to obtain a β-cyclodextrin solution, adding sodium hydroxide and stirring evenly to adjust the pH to 11.0-11.5, adding octadecyltrimethylammonium chloride, heating to 60° C., stirring fully, reacting for 1-2 hours, and obtaining a β-cyclodextrin solution having a quaternary ammonium salt cation; S102, adding montmorillonite with a diameter of 80 to 100 nm to the β-cyclodextrin solution containing quaternary ammonium salt cations, so that the montmorillonite is fully dispersed in the solution, fully stirred, and reacted for 1 to 2 hours to obtain montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations, taking out the suspension, centrifuging at a speed of 3500 rpm, washing with deionized water 2 to 3 times to remove sodium hydroxide, centrifuging again, taking out the solid mixture at the bottom, drying and grinding at 60° C., and obtaining montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations; S103, adding montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations into a high-pressure heating reaction tank, at a high temperature of 80 to 90°C, the mesopores on the montmorillonite and cyclodextrin are opened, and the oil in the water layer is absorbed into the mesopores, stirred for 1 to 2 hours, and after sufficient adsorption, allowed to stand for 1 to 2 hours to obtain a uniformly dispersed microsphere suspension adsorbing the oil, which is then transferred to a biocatalytic tank through a pipeline.

5. The method for treating kitchen waste by wet heat catalytic hydrolysis according to claim 1, characterized in that: The middle slurry layer rich in organic matter is subjected to wet heat treatment, and all organic matter obtained in the second and third stages is subjected to biocatalytic treatment. The specific steps are as follows: S201, the middle layer slurry rich in organic matter is transported to a high-pressure wet heat catalytic hydrolysis tank through a pipeline, and the high-pressure wet heat catalytic hydrolysis tank is heated to a pressure of 1.2-2 MPa and a temperature of 140-160° C., so that the water in the middle layer slurry is evaporated to obtain dry organic matter, and a critical steam generating device is used to generate critical steam at 140-160° C. and transport it to the high-pressure wet heat hydrolysis tank through a pipeline, and the system is stirred at the same time, and the organic matter in the system is sprayed multiple times in a short time to break its complex chemical bonds, and the evaporation-steam spraying-uniform mixing process is repeated multiple times to decompose the cellulose in the system into small molecular cellulose, the starch into short-chain starch, and the protein into short-chain polypeptides, so as to obtain initially degraded organic matter; S202, the montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cation is dispersed in deionized water, sodium carbonate and citric acid are added to adjust the pH to 6.3-6.5, tryptophan and phenylalanine are added, and the reaction is carried out for 1-2 hours, so that the surface of the montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cation is negatively charged, and after completion, it is filtered, dried, ground, and filtered with a 60-mesh filter cloth to obtain an active carrier with a negative charge; Wherein: the mass ratio of phenylalanine, tryptophan and montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cation is 2-5:4-8:15-20; S203, under sterile conditions, preparing a suspension of isomaltooligosaccharide, a negatively charged active carrier, and deionized water, then adding the composite bacteria, and culturing the suspension at a constant temperature of 35 to 37° C. and a shaking speed of 120 to 150 rpm / min for 3 to 6 hours; finally obtaining a composite bacterial liquid; wherein, according to mass fraction, the suspension comprises 5 to 8 parts of isomaltooligosaccharide, 30 to 35 parts of a negatively charged active carrier, 40 to 50 parts of deionized water, and 8 to 12 parts of the composite bacteria; S204, at 35-37°C, the composite bacterial liquid is added to the biocatalytic tank, and protease, cellulase and lipase are added, and after stirring evenly, the obtained microsphere suspension with evenly dispersed oil is cooled to 35°C and then added to the biocatalytic tank through a pipeline to react for 1-2 hours, and then water is added to the preliminarily degraded organic matter in S201 and mixed evenly, and then cooled to 35°C, and then added to the biocatalytic tank through a pipeline for further fermentation and degradation. After reacting for 24-30 hours, the liquid containing small molecule organic acid in the biocatalytic tank is filtered through a filter screen through a pipeline and then transported to a heating stirring tank for further concentration and sterilization to obtain a high-concentration small molecule organic acid liquid; S205, the lower layer of sediment obtained in the high-pressure heating stirring tank is cleaned regularly, dried by a blast drying device, incinerated, and then ground to be harmless.

6. The method for treating kitchen waste by wet heat catalytic hydrolysis according to claim 2, characterized in that: The high-pressure wet heat catalytic hydrolysis tank has a pressure of 1.2-2MPa and a temperature of 140-200°C; the high-pressure heating stirring tank has a pressure of 1.2-2MPa and a temperature of 30-100°C; the biocatalytic tank has a temperature of 30-40°C.

7. The method for treating kitchen waste by wet heat catalytic hydrolysis according to claim 4, characterized in that: in, The mass ratio of octadecyltrimethylammonium chloride to β-cyclodextrin is 1:1-2; the mass percentage concentration of the β-cyclodextrin solution is 5-8%; the mass ratio of β-cyclodextrin to montmorillonite is 1:2-4; the mass ratio of montmorillonite loaded with β-cyclodextrin having quaternary ammonium salt cations to kitchen waste is 1:10-20.

8. The method for treating kitchen waste by wet heat catalytic hydrolysis according to claim 5, characterized in that: in, The enzymatic activity of the amylase preparation is 40U / mg, the enzymatic activity of the protease preparation is 10U / mg, the enzymatic activity of the lipase preparation is 30U / mg, and the enzymatic activity of the cellulase preparation is 20U / mg; and the added amounts of the protease, cellulase and lipase are 0.005 to 0.008 of the mass of the kitchen waste, respectively; The composite bacteria specifically include: yeast, oceanic bacillus and parabacillus, the mass ratio of which is 1-2:2-4:2-4; wherein the number of live bacteria of parabacillus is ≥10 10 CFU / g; the number of viable bacteria of commercial yeast powder is ≥10 9 CFU / g, viable count of Oceanic Bacillus ≥10 9 CFU / g, the mass ratio of composite bacterial liquid to kitchen waste is 1:10~20.

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