A process for the complete resource utilization of kitchen waste

Abstract

This invention discloses a process for the complete resource utilization of kitchen waste. It includes the following steps: adding kitchen waste to a mixing tank, removing sand and stirring evenly to complete enzymatic hydrolysis, obtaining a complete slurry and kitchen wastewater; after sand removal and enzymatic hydrolysis, the complete slurry and kitchen wastewater are cooked and heated, then separated by a centrifuge to obtain mixed grease, slurry, and wet residue; a pyrolysis reaction is carried out, and the kitchen waste after the pyrolysis reaction is used to make poultry feed; the water containing high organic matter is subjected to anaerobic fermentation, and the fermentation liquid is treated by electrodialysis to concentrate the organic matter in the fermentation liquid, obtaining a high-concentration carbon source solution. The advantages are: the water, grease, and wet residue in the kitchen waste are treated and converted separately, achieving complete resource utilization, avoiding resource waste, improving resource recycling rate, reducing environmental pollution, and the entire process has no wastewater, waste gas, or waste residue emissions, meeting environmental protection requirements.

Description

Technical Field

[0001] This invention relates to a method for the resource utilization of kitchen waste, specifically a process for the full resource utilization of kitchen waste, belonging to the field of kitchen waste treatment technology. Background Technology

[0002] Food waste is an important component of urban household waste, characterized by high moisture content and rich organic matter. Traditional food waste treatment methods, such as landfill, incineration, and anaerobic fermentation, not only occupy a large amount of land resources but may also generate secondary pollution problems such as foul odors, leachate, biogas residue, and biogas slurry.

[0003] In recent years, with the increasing awareness of environmental protection and the development of resource recycling technologies, the demand for the resource-based treatment of food waste has become increasingly urgent. However, most current food waste treatment technologies can only partially recover and utilize the resources, such as extracting oil for biodiesel production, while the treatment of remaining components such as wet residue is inadequate, resulting in a low resource utilization rate. Therefore, developing a treatment method that can achieve full resource recovery of food waste is of significant practical importance. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a process method for the full resource utilization of food waste, which can convert all kinds of components in food waste through different process flows.

[0005] To solve the above-mentioned technical problems, the present invention provides a process for the complete resource utilization of food waste, comprising the following steps:

[0006] A. Slurry extraction:

[0007] Kitchen waste is added to a mixing tank, sand is removed and the mixture is stirred evenly to complete enzymatic hydrolysis and obtain a full amount of slurry;

[0008] B. Hot oil extraction from kitchen wastewater and wet residue:

[0009] After sand removal and enzymatic hydrolysis, the entire slurry is cooked and heated, and then separated by a centrifuge to obtain mixed oil, slurry and wet residue.

[0010] C. Preparation of poultry feed from pyrolysis residue:

[0011] The wet slag obtained above is sent to a pyrolysis reactor for drying. The pyrolysis reaction is carried out under anaerobic or low-oxygen conditions. A compound enzyme preparation is added to adjust the pH value and activity of the slurry. The kitchen waste produced after the pyrolysis reaction is dried and crushed to make poultry feed.

[0012] D. Anaerobic fermentation and electrodialysis for carbon source production:

[0013] The water containing high organic matter obtained during the above oil extraction process is subjected to anaerobic fermentation. The fermentation broth is then subjected to electrodialysis to concentrate the organic matter in the fermentation broth, resulting in a high-concentration carbon source solution.

[0014] Furthermore, prior to step A, the kitchen waste is pre-treated. During pre-treatment, the collected kitchen waste is completely crushed, put into a medium-temperature precipitator for cooking and precipitating, and then preliminarily sorted to remove various impurities.

[0015] Furthermore, the mixed oils extracted in step B are directly used as raw materials for downstream biodiesel production.

[0016] Furthermore, in step C, the compound enzyme preparation includes antioxidant enzymes and reductases, with a mass ratio of 1:2000.

[0017] Furthermore, in step C, the pyrolysis temperature is 118-120℃, and the reaction time is 4.5-6 hours.

[0018] Furthermore, in step D, the temperature inside the fermenter is maintained at 85-100℃, the pressure is 1.5 MPa, and the fermentation time is 4 hours.

[0019] Furthermore, in step D, the biogas produced during the anaerobic fermentation process serves as the project's steam supply source.

[0020] Furthermore, in step D, anion and cation exchange membranes are used in the electrodialysis treatment, and the current density is controlled at 1-3 A / dm³. 2 The processing time is 2-4 hours.

[0021] Furthermore, the carbon source solution obtained in step D is used as an external carbon source in the wastewater treatment plant for processes such as denitrification.

[0022] The advantages of this invention are:

[0023] (1) By treating and transforming the water, oil, wet residue and other components in kitchen waste separately, the full utilization of resources is realized, which avoids resource waste, improves the resource recycling rate, and reduces environmental pollution. At the same time, the entire treatment process has no wastewater, waste gas and waste residue emissions, which meets environmental protection requirements.

[0024] (2) The biogas produced during fermentation can be used as an energy source for the steam generator and for heating the pyrolysis reaction, thus achieving energy self-sufficiency and reducing processing costs.

[0025] (3) The extracted slurry can be directly used as a raw material for preparing feed from kitchen waste, which has high economic value and application prospects. The pyrolysis oil can be used as biodiesel or chemical raw material, and as an oil additive in poultry feed. The carbon source solution obtained by fermentation and electrodialysis can be used for sewage treatment, which has high economic value and application prospects. Detailed Implementation

[0026] The following detailed description of the process for the complete resource utilization of kitchen waste according to the present invention, in conjunction with specific embodiments, provides a further detailed explanation.

[0027] The process for the complete resource recovery of food waste of the present invention includes the following steps:

[0028] (1) Pre-treatment of kitchen waste:

[0029] During pretreatment, the collected kitchen waste is completely crushed and put into a medium-temperature precipitator at a temperature of 82-85℃ and stirred for more than 40 minutes for cooking and precipitating. Then, it is preliminarily sorted to remove various impurities such as plastic, glass, and metal.

[0030] (2) Slurry extraction:

[0031] The crushed, processed, and sorted kitchen waste is added to a mixing tank to remove sand and mix evenly to complete enzymatic hydrolysis. The mixing time is 30-60 minutes, preferably 40 minutes, to obtain a full slurry (including kitchen wastewater and wet residue).

[0032] (3) Full-volume hot oil extraction from kitchen wastewater and wet residue:

[0033] After sand removal and enzymatic hydrolysis, the entire slurry is cooked again and heated to 90-120℃, and then separated by centrifugation to obtain mixed oil, slurry and wet residue; among them, the mixed oil is extracted and directly used as a raw material for downstream biodiesel production;

[0034] (4) Preparation of poultry feed from pyrolysis residue:

[0035] The wet slag obtained from the above separation is sent to a pyrolysis reactor for drying. The pyrolysis reaction is carried out under anaerobic or low-oxygen conditions. A compound enzyme preparation is added, which includes antioxidant enzymes and reductases in a mass ratio of 1:2000, to adjust the pH value and activity of the slurry. The pyrolysis temperature is 118-120℃ and the reaction time is 4.5-6 hours. The kitchen waste powder made from the pyrolysis reaction is dried and pulverized to make poultry feed. The poultry feed prepared from this powder is nutritious, palatable, and can effectively improve the growth performance of poultry.

[0036] (5) Anaerobic fermentation and electrodialysis for carbon source production:

[0037] The water containing high levels of organic matter (liquid components separated during the treatment of kitchen waste, containing dissolved or suspended large amounts of organic matter) obtained during the oil extraction process is subjected to anaerobic fermentation in a fermenter. The temperature inside the fermenter is maintained at 85-100℃, the pressure at 1-3 MPa (preferably 1.5 MPa), and the fermentation time is 3-5 hours (preferably 4 hours). The biogas produced during anaerobic fermentation serves as the project's steam supply source, effectively reducing external purchase costs and minimizing environmental pollution. The fermentation liquid contains abundant organic acids, alcohols, and other organic matter. The fermentation liquid is then subjected to electrodialysis treatment using anion and cation exchange membranes, with the current density controlled at 1-3 A / dm³. 2 The processing time is 2-4 hours. The organic matter in the fermentation broth is concentrated by electrodialysis to obtain a high-concentration carbon source solution, which can be used as an external carbon source in sewage treatment plants for processes such as denitrification and nitrogen removal, thereby improving sewage treatment efficiency.

[0038] The following examples demonstrate its effectiveness:

[0039] First, the collected 5 tons of kitchen waste was crushed to reduce the particle size to less than 6 mm. The crushed kitchen waste was then added to a medium-temperature precipitator, heated at 85°C and stirred for 45 minutes. It was then pumped to a mixing tank for further mixing, causing large particles and heavy objects to settle to the bottom. The slurry continuously entered a desander to remove sand, effectively reducing the wear of shells and bone fragments on subsequent high-speed rotating machinery. Next, the slurry, after crushing, precipitating, cooking, and sand removal, was sent to a high-speed, high-precision three-phase centrifuge to extract the mixed grease, wet residue, and water phases from the kitchen waste. The wet residue (slurry) after three-phase centrifugation had a particle size of less than 2 mm and was added to a pyrolysis reactor via a screw conveyor. Simultaneously, antioxidant enzymes and reductases were added at a ratio of 1:2000 (approximately 0.5% of the wet residue weight per ton, 0.5 kg added) to adjust the pH and organic matter activity of the slurry. The pyrolysis temperature was 120°C, and the reaction time was 5 hours. The kitchen waste produced from the pyrolysis reaction is dried, crushed, automatically sorted, coded and packaged to make poultry feed.

[0040] The water containing high levels of organic matter obtained during the oil extraction process is then subjected to anaerobic fermentation. The fermentation tank is maintained at a temperature of 90℃ and a pressure of 1.5 MPa for 4 hours. The biogas produced during anaerobic fermentation can be used as a steam supply for the project. Finally, the fermentation liquid is filtered through quartz sand and a large-particle membrane, followed by electrodialysis using an anion and cation exchange membrane, with the current density controlled at 2 A / dm³. 2 The processing time is 3 hours. Electrodialysis can concentrate the organic matter in the fermentation broth to obtain a high-concentration carbon source solution.

[0041] The parameters obtained from the process methods in the above specific application examples are analyzed as follows:

[0042] The core experimental data for each process step are as follows:

[0043] 1. Pretreatment stage (impurity removal)

[0044]

[0045] 2. Full-volume hot oil extraction process (three-phase centrifugal separation)

[0046] 3. Pyrolysis process for producing poultry feed

[0047] 4. Anaerobic fermentation and electrodialysis carbon source production process

[0048] 5. Environmental protection indicator experimental data (verifying "environmentally friendly")

[0049]

[0050] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A process for full resource utilization of kitchen waste, characterized in that, The method comprises the following steps: A. Slurry extraction: Kitchen waste is added to a stirring tank, sand is removed, and enzyme hydrolysis is completed to obtain full-volume slurry; B. Full-volume hot-state oil extraction of kitchen waste water and wet residue: After sand removal and enzyme hydrolysis, the full-volume slurry is subjected to cooking and heating, and then mixed oil, slurry and wet residue are obtained by centrifugation; C. Preparation of poultry feed from pyrolysis residue: The wet residue obtained in the above step is sent to a pyrolysis reactor for drying treatment, and pyrolysis reaction is carried out under anaerobic or low-oxygen conditions. A composite enzyme preparation is added to adjust the pH value and activity of the slurry. The kitchen powder prepared from the kitchen waste after pyrolysis reaction is dried, crushed and made into poultry feed; D. Carbon source preparation by anaerobic fermentation and electrodialysis: The water containing high organic matter separated in the above oil extraction process is subjected to anaerobic fermentation treatment, and the fermentation liquid is subjected to electrodialysis treatment. The organic matter in the fermentation liquid is concentrated by electrodialysis to obtain a high-concentration carbon source solution.

2. The kitchen waste full resource utilization process method according to claim 1, characterized in that: Before the step A, the kitchen waste is pretreated. During the pretreatment, the collected kitchen waste is fully crushed, subjected to cooking and quality conversion in a medium-temperature quality converter, and then subjected to preliminary sorting to remove various impurities.

3. The kitchen waste full resource utilization process method according to claim 1 or 2, characterized in that: The mixed oil extracted in the step B is directly used as a raw material for downstream production of biodiesel.

4. The kitchen waste full resource utilization process method according to claim 3, characterized in that: In the step C, the composite enzyme preparation comprises antioxidant enzymes and reductase, and the mass ratio of the two is 1:2000.

5. The kitchen waste full resource utilization process method according to claim 1, 2 or 4, characterized in that: In the step C, the pyrolysis temperature is 118-120℃, and the reaction time is 4.5-6 hours.

6. The kitchen waste full resource utilization process method according to claim 5, characterized in that: In the step D, the temperature in the fermentation tank is maintained at 85-100℃, the pressure is 1.5Mpa, and the fermentation time is 4h.

7. The kitchen waste total resource utilization process method according to claim 1, 2, 4 or 6, characterized in that: In the step D, the biogas produced during the anaerobic fermentation process is used as a steam supply source for the project.

8. The kitchen waste full resource utilization process method according to claim 7, characterized in that: In the step D, cation and anion exchange membranes are used in the electrodialysis treatment, the current density is controlled at 1-3A / dm², and the treatment time is 2-4 hours.

9. The kitchen waste full resource utilization process method according to claim 1, characterized in that: The carbon source solution obtained in the step D is used as an external carbon source for a sewage treatment plant.

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