Method for preparing high-carbon-nitrogen-ratio organic carbon source and high-protein feed from kitchen waste solid residues

Abstract

The invention discloses a method for preparing a high-carbon-nitrogen-ratio organic carbon source and a high-protein feed from kitchen waste solid residues. According to the method, kitchen waste solid residues are sequentially subjected to anaerobic fermentation and drying treatment to obtain dry powder and water vapor, the dry powder serves as feed, the water vapor is subjected to condensation treatment to obtain condensed water, the condensed water is subjected to membrane concentration treatment to obtain a concentrated solution, and the concentrated solution serves as an organic carbon source; strains adopted in the anaerobic fermentation process comprise at least one of saccharomycetes, lactic acid bacteria, bacillus aceticus and clostridium. According to the method, the kitchen waste solid residues can be converted into high-quality feed raw materials and organic carbon sources, high-quality utilization of the kitchen waste is achieved, the economic value of the waste is improved, meanwhile, the kitchen waste treatment process is optimized, and environmental pollution is reduced.

Description

Technical Field

[0001] The invention relates to a method for treating kitchen waste, in particular to a method for preparing an organic carbon source with a high carbon-nitrogen ratio and a high-protein feed by utilizing solid residues from kitchen waste, and belongs to the technical field of waste treatment. Background Art

[0002] Kitchen solids contain a lot of nutritious substances such as protein, carbohydrates, minerals, etc., and have a high recycling value. Currently, there are relevant patents for the resource utilization of kitchen solids and the production of carbon sources from kitchen waste, but there are no patents for the full utilization of kitchen solids, that is, the resource utilization of the liquid phase while the solids are being recycled. The current mainstream method only utilizes the solid phase in the kitchen solids, and does not utilize the high-concentration organic liquid phase with a content of 75-80%, but instead discharges it as wastewater, which not only causes environmental pollution, but is also a waste of resources.

[0003] Therefore, it is necessary to develop a method for treating kitchen solid residues that can improve resource utilization while reducing environmental pollution. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing a high carbon-nitrogen ratio organic carbon source and a high-protein feed using solid residues of kitchen waste. The method can convert solid residues of kitchen waste into high-quality feed raw materials and organic carbon sources, realize high-quality utilization of kitchen waste, improve the economic value of waste, optimize the kitchen waste treatment process, and reduce environmental pollution.

[0005] In order to achieve the above technical objectives, the present invention provides a method for preparing a high carbon-nitrogen ratio organic carbon source and a high-protein feed using solid residues of kitchen waste. The method comprises the following steps: subjecting the solid residues of kitchen waste to anaerobic fermentation and drying in sequence to obtain dry powder and water vapor, wherein the dry powder is used as feed, the water vapor is condensed to obtain condensed water, the condensed water is concentrated by membrane to obtain a concentrated solution, and the concentrated solution is used as an organic carbon source; the bacterial species used in the anaerobic fermentation process include at least one of yeast, lactic acid bacteria, acetic acid bacteria, and clostridium.

[0006] On the one hand, the present invention strengthens anaerobic fermentation by introducing specific microbial strains during the anaerobic fermentation process. The specific microbial strains can quickly decompose complex organic matter in the food waste solid residue into volatile organic acids, while improving the fermentation efficiency and product stability. On the other hand, the present invention skillfully combines anaerobic fermentation with a drying process to fully recycle the nutrients in the food waste solid residue. The dry powder contains rich nutrients such as protein, carbohydrates, minerals, etc., and can be directly used as animal feed. The condensed water has an extremely high carbon-nitrogen ratio and can be used as an excellent organic carbon source.

[0007] As a preferred solution, the amount of the bacteria added is 0.1-5 wt % of the solid residue of the kitchen waste. The fermentation efficiency can be improved by controlling the amount of bacteria within a suitable range.

[0008] As a preferred solution, the conditions for anaerobic fermentation are: air isolation, pH 3.5-5, temperature 35-45° C., and time 2-6 hours. The fermentation efficiency can be improved by controlling the anaerobic fermentation conditions within a suitable range.

[0009] As a preferred solution, organic matter with large porosity is added during the anaerobic fermentation process, such as straw, bran, etc. Adding organic matter with large porosity can increase the air permeability of the material and improve the fermentation effect.

[0010] As a preferred solution, the drying conditions are: temperature of 120-180° C. and time of 2-3 hours.

[0011] As a preferred solution, the moisture content of the dry powder is less than 12wt%. The low moisture content dry powder can be prepared into high-quality feed raw materials through crushing, screening and impurity removal processes. The dry powder can be further processed into granules or other forms for easy storage and transportation.

[0012] As a preferred solution, the condensation process is a multi-stage dust removal condensation process.

[0013] As a preferred solution, the COD concentration of the condensed water is 13000-2000 mg / L, more preferably 15000-20000 mg / L, and the ammonia nitrogen content (NH4 + -N) is lower than 8mg / L.

[0014] As a preferred solution, the membrane concentration treatment includes ultrafiltration and / or microfiltration.

[0015] As a preferred solution, the COD concentration of the concentrated liquid is 25000 mg / L to 35000 mg / L.

[0016] As a preferred solution, the kitchen waste solid residue is the residual solid matter obtained after the kitchen waste is screened, cooked at high temperature and separated into three phases. The solid matter contains nutrient-rich components such as protein, carbohydrates and minerals.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) By introducing specific microbial strains for enhanced anaerobic fermentation, the fermentation efficiency and product quality can be significantly improved;

[0019] (2) By combining the drying process, the moisture content of the solid residue can be effectively reduced, the quality, stability and storage of the converted products can be improved, and energy consumption and production costs can be reduced;

[0020] (3) Comprehensively utilize water vapor and condensed water to reduce wastewater discharge. Combined with membrane concentration technology, the reuse of condensed water is more efficient, providing a better quality organic carbon source for biochemical treatment, which is in line with the concepts of sustainable development and circular economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0022] Figure 1 The present invention provides a simplified process flow diagram for preparing a high carbon-nitrogen ratio organic carbon source and a high-protein feed from solid residues of kitchen waste. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Solid food residue: First, the food waste undergoes a preliminary screening process (using spiral sorting, the spiral diameter is 500, the sieve holes are waist-shaped holes, 35*60, and the sieve plate thickness is 8mm) to remove large impurities and non-degradable substances such as plastics and metals. Then, the screened food waste enters the 70°C high-temperature cooking stage, where it is cooked under high temperature to destroy the structure of organic matter and kill harmful microorganisms. The cooked food waste will enter the oil, water, and residue three-phase separation device for separation. In this process, grease, water, and solid residues are collected and processed separately. Finally, the solid residue obtained after the three-phase separation is the solid food waste residue.

[0025] Example 1

[0026] (1) Enhanced anaerobic fermentation

[0027] 100g of solid residue after three-phase separation of kitchen waste was taken, and the water content was measured to be 77.5%. The solid residue was placed in a 0.15L sealed plastic bottle, and yeast strains were added at a ratio of 2wt% relative to the solid residue, and anaerobic fermentation conditions were maintained. The temperature was kept at 37.5°C by heating, and the placement time was 4 hours. The pH value of the material was detected to be 4.2. At this time, the solid residue provided a relatively ideal environment for microorganisms.

[0028] (2) Drying

[0029] After fermentation is completed, the solid residue is transferred to a high-temperature dryer, the drying temperature is set to 160°C, and the drying time is 1.8 hours.

[0030] The moisture content of the obtained dry powder is reduced to 11.5%, and it is cooled at room temperature to be used as a high-quality feed raw material.

[0031] (3) Carbon source production from condensed wastewater

[0032] The wet water vapor generated during the drying process is treated by an improved three-stage dust removal and condensation system to improve the recovery rate of water vapor. The collected condensate is tested and the pH value is 3.05, COD is 18500mg / L, NH4 + -N is 3.62 mg / L.

[0033] (4) Inorganic ceramic membrane concentration process

[0034] a. Collect the condensed wastewater generated during the drying process to ensure that large suspended solids in the wastewater are initially filtered out to prevent clogging of the membrane during subsequent treatment.

[0035] b. Introduce the pre-treated condensed wastewater into the inorganic ceramic membrane concentration system. Operating conditions are set: the filtration pressure is controlled at 0.2-0.4MPa, and the temperature is maintained between room temperature and 60℃.

[0036] c. Through the filtration of inorganic ceramic membrane (pore size of 50nm), the wastewater is separated into clear liquid and concentrated liquid. The clear liquid is sent to the subsequent biological aerobic system for treatment; the concentrated liquid contains high concentration of organic matter and is used as an organic carbon source, with a COD concentration of 28000mg / L.

[0037] Example 2

[0038] (1) Enhanced anaerobic fermentation

[0039] 1kg of solid residue after three-phase separation of kitchen waste was taken, and the water content was determined to be 77.5%. The solid residue was placed in a 1.2L sealed plastic bucket, and yeast strains were added at a ratio of 1.5wt% and acetic acid bacteria were added at a ratio of 1wt% relative to the solid residue. Anaerobic fermentation conditions were maintained, and the temperature was maintained at 30°C by heating. The placement time was 3 hours, and the pH value of the material was detected to be 4.3. At this time, the solid residue provided a relatively ideal environment for microorganisms.

[0040] (2) Drying

[0041] After fermentation is completed, the solid residue is transferred to a high-temperature dryer, the drying temperature is set to 150°C, and the drying is performed for 2 hours.

[0042] The moisture content of the obtained dry powder is reduced to 10%, and it is cooled at room temperature to be used as a high-quality feed raw material.

[0043] (3) Carbon source production from condensed wastewater

[0044] The wet water vapor generated during the drying process is treated by an improved three-stage dust removal and condensation system to improve the recovery rate of water vapor. The collected condensate was tested and the pH value was 3.12, COD was 16500mg / L, NH4 + -N is 4.25mg / L.

[0045] (4) Inorganic ceramic membrane concentration process

[0046] a. Collect the condensed wastewater generated during the drying process to ensure that large suspended solids in the wastewater are initially filtered out to prevent clogging of the membrane during subsequent treatment.

[0047] b. Introduce the pre-treated condensed wastewater into the inorganic ceramic membrane concentration system. Operating conditions are set: the filtration pressure is controlled at 0.2-0.4MPa, and the temperature is maintained between room temperature and 60℃.

[0048] c. Through the filtration of inorganic ceramic membrane (pore size of 50nm), the wastewater is separated into clear liquid and concentrated liquid. The clear liquid is sent to the subsequent biological aerobic system for treatment; the concentrated liquid contains high concentration of organic matter and is used as an organic carbon source, with a COD concentration of 26000mg / L.

[0049] Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing high carbon-nitrogen ratio organic carbon source and high-protein feed using solid residue from kitchen waste, Features: The solid residue of kitchen waste is subjected to anaerobic fermentation and drying treatment in sequence to obtain dry powder and water vapor, the dry powder is used as feed, the water vapor is condensed to obtain condensed water, the condensed water is subjected to membrane concentration treatment to obtain concentrated liquid, and the concentrated liquid is used as an organic carbon source; the bacterial species used in the anaerobic fermentation process include at least one of yeast, lactic acid bacteria, acetic acid bacteria, and clostridium.

2. A method for preparing a high carbon-nitrogen ratio organic carbon source and a high-protein feed using solid residues from kitchen waste according to claim 1, Features: The added amount of the bacteria is 0.1-5wt% of the solid residue of the kitchen waste.

3. A method for preparing a high carbon-nitrogen ratio organic carbon source and a high-protein feed using solid residues from kitchen waste according to claim 1 or 2, Features: The conditions of the anaerobic fermentation are: isolation from air, pH of 3.5-5, temperature of 35-45° C., and time of 2-6 hours.

4. A method for preparing a high carbon-nitrogen ratio organic carbon source and a high-protein feed using solid residues from kitchen waste according to claim 1 or 2, Features: The drying conditions are as follows: temperature of 120-180° C. and time of 2-3 hours.

5. The method for preparing high carbon-nitrogen ratio organic carbon source and high-protein feed by using solid residue from kitchen waste according to claim 1, Features: The moisture content of the dry powder is lower than 12 wt %.

6. The method for preparing high carbon-nitrogen ratio organic carbon source and high-protein feed by using solid residue from kitchen waste according to claim 1, Features: The condensation process is a multi-stage dust removal condensation process.

7. A method for preparing a high carbon-nitrogen ratio organic carbon source and high-protein feed using solid residue from kitchen waste according to claim 1 or 5, Features: The COD concentration of the condensed water is 13000-2000 mg / L, and the ammonia nitrogen content is lower than 8 mg / L.

8. The method for preparing high carbon-nitrogen ratio organic carbon source and high-protein feed by using solid residue from kitchen waste according to claim 1, Features: The membrane concentration process includes ultrafiltration and / or microfiltration.

9. A method for preparing a high carbon-nitrogen ratio organic carbon source and a high-protein feed using solid residues from kitchen waste according to claim 1 or 7, Features: The COD concentration of the concentrated liquid is 25000-35000 mg / L.

10. The method for preparing high carbon-nitrogen ratio organic carbon source and high-protein feed by using solid residue from kitchen waste according to claim 1, Features: The kitchen waste solid residue is the residual solid matter obtained after the kitchen waste is screened, cooked at high temperature and separated into three phases.

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