Method for preparing carbon source from kitchen waste

Abstract

The application discloses a kind of methods for preparing carbon source from kitchen waste, belongs to the technical field of organic waste treatment;Including: preparation of Fe loaded carbon nanomaterial;Preparation of Fe loaded carbon aerogel material;Fe loaded carbon nanomaterial and Fe loaded carbon aerogel material are weighed according to preset proportion, to obtain mixed powder;Adopt resin to stick mixed powder, then carry out compression molding, calcination, to obtain conical filler;The conical filler and kitchen waste are added to the pulping container of carbon source preparation machine, and the required flora for hydrolysis and acidification of kitchen waste is added;Start stirring, to prepare carbon source.The application realizes kitchen waste resource by Fe loaded carbon-based material and microorganism, with the advantages of green environmental protection, low cost, high efficiency, reusability and the like.

Description

Technical Field

[0001] This invention relates to the field of organic waste treatment technology, specifically to a method for preparing a carbon source from kitchen waste. Background Technology

[0002] In my country's urban wastewater treatment plants, most suffer from insufficient influent carbon sources, requiring the addition of additional carbon sources to improve denitrification efficiency and meet discharge standards. Therefore, improving wastewater denitrification efficiency has become a significant technical challenge for wastewater treatment plants.

[0003] With the improvement of my country's economic level, the output of food waste is also increasing. The main components of food waste are carbohydrates, proteins, and oils, with a very high organic matter content. It is an ideal raw material for producing carbon sources through anaerobic fermentation. If not properly treated, it can easily lead to secondary pollution and resource waste. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing carbon sources from kitchen waste.

[0005] This invention discloses a method for preparing a carbon source from food waste, comprising:

[0006] Preparation of Fe-supported carbon nanomaterials;

[0007] Preparation of Fe-supported carbon aerogel materials;

[0008] Fe-supported carbon nanomaterials and Fe-supported carbon aerogel materials were weighed according to a preset ratio to obtain a mixed powder.

[0009] The mixed powder is bonded with resin, then pressed and calcined to obtain a cone-shaped filler.

[0010] The conical packing material and kitchen waste are added to the pulping container of the carbon source preparation machine, along with the microbial community required for the hydrolysis and acidification of the kitchen waste; stirring is then started to obtain the carbon source.

[0011] As a further improvement of the present invention, the particle size of the kitchen waste is 3~10mm and the moisture content is less than 80%; the COD of the carbon source product is higher than 150000mg / L.

[0012] As a further improvement of the present invention, the preparation of Fe-supported carbon nanomaterials includes:

[0013] The carbon-based material was immersed in an excess of ferric salt solution to ensure sufficient Fe loading. The pH of the mixture was adjusted to alkaline, and after stirring, the precipitate was collected and thoroughly washed with deionized water and ethanol. After drying, it was pyrolyzed at high temperature to ensure that the Fe was fully oxidized and attached to the surface of the carbon-based material in the form of ferric iron, thus obtaining a material with a density of 1.8~2.2 g / cm³.3 Fe-supported carbon nanomaterials.

[0014] As a further improvement of the present invention, the preparation of Fe-supported carbon nanomaterials includes:

[0015] Gelatin and silica powder were dissolved in deionized water, and after magnetic stirring, the gelatin was completely dissolved in a water bath. Repeated freeze-thaw treatment was performed to obtain a stable hydrogel. The hydrogel was then freeze-dried under vacuum and pyrolyzed. After natural cooling, the SiO2 nanoparticles were removed with hydrofluoric acid solution, and then thoroughly washed with deionized water and ethanol. After drying, a carbon aerogel carrier was obtained.

[0016] The carbon aerogel support was impregnated in an excess of ferric salt solution to ensure sufficient Fe loading. The pH of the mixture was adjusted to alkaline, and after stirring, the precipitate was collected and thoroughly washed with deionized water and ethanol. After drying, it was pyrolyzed at high temperature to ensure that the Fe was fully oxidized and attached to the surface of the carbon aerogel support in the form of ferric iron, thus obtaining a density of 0.12~0.18 g / cm³. 3 Fe-supported carbon aerogel materials.

[0017] As a further improvement of the present invention

[0018] The carbon-based materials are petroleum coke and pitch coke, with a weight ratio of petroleum coke to pitch coke of (2~4):1, preferably 3:1.

[0019] The ferric salt solution is a ferric nitrate solution;

[0020] The pH of the mixture is adjusted to 9-11, preferably 10, by adding sodium hydroxide;

[0021] The mixture is stirred at 70~90℃ for 0.5~1.5h and the precipitate is collected, preferably stirred at 80℃ for 1h;

[0022] After the precipitate is dried in an oven at 70~90℃, it is calcined in a tube furnace at 500~600℃ for 3~5 hours to allow Fe to be fully oxidized and attached to the surface of the carbon-based material or carbon aerogel carrier in the form of ferric iron; preferably, after the precipitate is dried in an oven at 80℃, it is calcined in a tube furnace at 550℃ for 4 hours.

[0023] After vacuum freeze-drying the hydrogel for 10-15 hours, the temperature is raised to 700-900°C at a heating rate of 3-6°C / min, and then pyrolyzed in a tube furnace for 3-5 hours; preferably, after vacuum freeze-drying for 12 hours, the temperature is raised to 800°C at a heating rate of 5°C / min, and then pyrolyzed in a tube furnace for 4 hours.

[0024] As a further improvement of the present invention, the required addition ratio of Fe-loaded carbon nanomaterials and Fe-loaded carbon aerogel materials is as follows: to ensure that the prepared conical packing material can be uniformly distributed and suspended in the kitchen waste in the pulping container, so as to ensure that the upper, middle and lower parts of the kitchen waste can be better treated; that is, by adding low-density Fe-loaded carbon aerogel materials, the density of the prepared conical packing material is adjusted so that the density of the conical packing material is similar to that of the kitchen waste solution, so that the conical packing material can cooperate with the microorganisms in the upper, middle and lower layers of the solution during use; preferably, the weight ratio of Fe-loaded carbon nanomaterials to Fe-loaded carbon aerogel materials in the upper part of the conical packing material is 1:0, the weight ratio of Fe-loaded carbon nanomaterials to Fe-loaded carbon aerogel materials in the middle part of the conical packing material is 4:5, and the weight ratio of Fe-loaded carbon nanomaterials to Fe-loaded carbon aerogel materials in the lower part of the conical packing material is 1:0; the specific height of the upper, middle and lower parts can be selected to each account for 1 / 3 of the overall height.

[0025] As a further improvement of the present invention, the method of using resin to bind the mixed powder, followed by pressing and calcination, yields a cone-shaped filler; comprising:

[0026] Phenolic resin is used to bind the mixed powder; wherein the weight ratio of the mixed powder to the phenolic resin is (1.5~2.5):1, preferably 2:1;

[0027] The bonded mixed powder is pressed into shape under a molding pressure of 100~150MPa, and then calcined at 800~1200℃ to obtain a cone-shaped filler.

[0028] As a further improvement of the present invention, the conical packing added to the pulping container is 30% to 40% of the volume of the pulping container and is lower than the center line of the container; the lower dimensions of the conical packing include Φ80mm, Φ60mm, Φ50mm and Φ40mm, and the corresponding upper dimensions are Φ70mm, Φ50mm, Φ40mm and Φ30mm, respectively. The height dimension of each packing is 70mm, and the volume ratio of each dimension is Φ80mm:Φ60mm:Φ50mm:Φ40mm=20:35:25:20.

[0029] As a further improvement of the present invention, the microbial community added to the pulping container includes Chlorophyta phylum among hydrolytic bacteria and Firmicutes and Actinobacteria phylum among acid-producing bacteria. The total amount of microbial community added is microbial community: organic matter = 1:400, and the amount of Chlorophyta phylum, Firmicutes and Actinobacteria added is 1:1:1.

[0030] As a further improvement of the present invention, the carbon source preparation machine includes a pulping container and legs supporting the pulping container;

[0031] The pulping container is equipped with a stirrer. The top of the pulping container is equipped with a feeding port for adding conical packing material, kitchen waste and microorganisms. The bottom of the pulping container is equipped with a discharge port and a packing material outlet. A filter screen is installed on the discharge port.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] This invention utilizes Fe-loaded carbon-based materials in conjunction with microorganisms to recycle food waste, offering advantages such as being environmentally friendly, low-cost, highly efficient, and reusable. It also produces carbon source additives from food waste for wastewater treatment plants, supplementing the carbon source for microorganisms. This approach achieves both the harmless and resource-based treatment of food waste and solves the technical challenges faced by wastewater treatment plants. Attached Figure Description

[0034] Figure 1 This is a flowchart of the method for preparing carbon sources from food waste disclosed in this invention;

[0035] Figure 2 This is a schematic diagram of the carbon source preparation machine;

[0036] Figure 3 This is a schematic diagram of a cone-shaped packing.

[0037] In the picture:

[0038] 1. Pulping container; 2. Support legs; 3. Agitator; 4. Feed port; 5. Discharge port; 6. Packing outlet; 7. Filter screen. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] The present invention will now be described in further detail with reference to the accompanying drawings:

[0041] like Figure 1 As shown, the present invention provides a method for preparing a carbon source from food waste, comprising:

[0042] Step 1: Preparation of Fe-supported carbon nanomaterials:

[0043] Carbon-based materials (petroleum coke: pitch coke = 3:1) were impregnated in an excess of ferric nitrate solution to ensure sufficient Fe loading. The pH of the mixture was adjusted to 10 by adding sodium hydroxide, and then stirred at 80°C for 1 hour. The precipitate was collected and thoroughly washed with deionized water and ethanol. Finally, the washed precipitate was dried in an oven at 80°C and then calcined in a tube furnace at 550°C for 4 hours to ensure that Fe was fully oxidized and attached to the surface of the carbon-based material in the form of ferric iron, resulting in a product with a density of approximately 2 g / cm³. 3 Fe-supported carbon nanomaterials.

[0044] Step 2: Preparation of Fe-supported carbon aerogel material:

[0045] Gelatin and silica powder were dissolved in deionized water. The mixture was first magnetically stirred for 30 min, then completely dissolved in a 70°C water bath. This process was repeated three times with a cold-thaw cycle to form a stable hydrogel. The hydrogel was then freeze-dried under vacuum for 12 h, and then heated to 800°C at a rate of 5°C / min, followed by pyrolysis in a tube furnace for 4 h. After natural cooling to room temperature, the SiO2 nanoparticles were removed with hydrofluoric acid solution, followed by thorough washing with deionized water and ethanol. Finally, the hydrogel was dried in an oven at 80°C to obtain the carbon aerogel support.

[0046] The carbon aerogel support was impregnated in an excess of ferric nitrate solution to ensure sufficient Fe loading. The pH of the mixture was adjusted to 10 by adding sodium hydroxide, and then stirred at 80°C for 1 hour. The precipitate was collected and thoroughly washed with deionized water and ethanol. Finally, the washed precipitate was dried in an oven at 80°C and then calcined in a tube furnace at 550°C for 4 hours to ensure that the Fe was fully oxidized and attached to the surface of the carbon aerogel support in the form of ferric iron, resulting in a density of approximately 0.15 g / cm³. 3 Fe-supported carbon aerogel materials.

[0047] Step 3: Weigh the Fe-supported carbon nanomaterials and Fe-supported carbon aerogel materials according to a preset ratio to obtain a mixed powder; wherein,

[0048] The required ratio of Fe-supported carbon nanomaterials and Fe-supported carbon aerogels is as follows: The prepared conical packing material should be uniformly distributed and suspended in the food waste within the slurry container to ensure better treatment of the upper, middle, and lower parts of the food waste. Specifically, by adding low-density Fe-supported carbon aerogels, the density of the prepared conical packing material is adjusted to be similar to the density of the food waste solution, allowing the conical packing material to synergize with microorganisms in the upper, middle, and lower layers of the solution during use. Preferably, the weight ratio of Fe-supported carbon nanomaterials to Fe-supported carbon aerogels in the upper part of the conical packing material is 1:0; in the middle part, it is 4:5; and in the lower part, it is 1:0. The specific height of each part can be selected to be 1 / 3 of the overall height.

[0049] Step 4: Use phenolic resin to bond the mixed powder to ensure that the flexural strength and compressive strength of the material can reach about 41 MPa and 55 MPa respectively; wherein the weight ratio of mixed powder to phenolic resin is 2:1.

[0050] Step 5: Press the bonded mixed powder under a molding pressure of 120 MPa to obtain a conical filler blank; wherein, the above molding pressure can ensure the porosity of the filler, thereby giving the filler good electrical conductivity.

[0051] Step 6: Calcination at 1000℃ yields conical packing material. During high-temperature calcination, the phenolic resin forms a planar network structure with abundant large π bonds within the layers, facilitating the free movement of electrons and thus enabling the packing material to better collaborate with microorganisms in degrading food waste. The conical packing material disrupts the flow field during use, causing the slurry to flow in a turbulent state, thereby reducing the settling velocity and promoting the crushing and degradation of food waste.

[0052] Step 7: Add the conical packing material and kitchen waste into the slurry container of the carbon source preparation machine, and add the bacterial flora required for the hydrolysis and acidification of the kitchen waste; start stirring to obtain the carbon source; wherein,

[0053] Conical packing such as Figure 3As shown, the height of each packing material is 70mm. Adding too much conical packing will cause them to overlap, hindering their crushing capacity and increasing energy consumption; adding too little conical packing will limit their crushing capacity. Therefore, the conical packing added to the pulping container is selected to be 30%~40% of the container's volume, and below the container's centerline. The dimensions of the conical packing include Φ80mm, Φ60mm, Φ50mm, and Φ40mm, all of which are the lower diameters of the packing. The corresponding upper dimensions are Φ70mm, Φ50mm, Φ40mm, and Φ30mm, with a volume ratio of Φ80mm:Φ60mm:Φ50mm:Φ40mm = 20:35:25:20.

[0054] The microbial community added to the pulping container includes Chloroflexi (a type of hydrolytic bacteria) and Firmicutes and Actinobacteriota (a type of acid-producing bacteria). These microorganisms work synergistically with the conical packing material to degrade food waste and prepare carbon sources. The total ratio of microorganisms to organic matter is 1:400, and the ratio of Chloroflexi, Firmicutes, and Actinobacteriota is 1:1:1 to ensure synergistic degradation and optimal synergistic effect between the packing material and the microorganisms.

[0055] like Figure 2 As shown, the carbon source preparation machine includes a slurry container 1 and support legs 2 supporting the slurry container; the slurry container 1 is equipped with a stirrer 3, the top of the slurry container 1 is equipped with a feeding port 4 for adding conical packing material, kitchen waste and microorganisms, the bottom of the slurry container is equipped with a discharge port 5 and a packing material outlet 6, and the discharge port 5 is equipped with a 100-mesh filter screen 7; it processes materials in batches, after the material enters from the feeding port 4, the stirrer 3 is turned on and stirred continuously for 4 to 6 hours, and then the material is discharged from the discharge port 5. When the internal packing material is severely worn, it can be discharged from the packing material outlet 6 and replenished from the feeding port 4.

[0056] test:

[0057] In the experiment determining the shape of the nanofiller, spherical and conical fillers were selected based on the principle of ball milling to crush and degrade food waste with microbial communities. Experimental results showed that the COD content of the carbon source during the degradation process with spherical nanofillers and microorganisms was 140,520 ml / L. Conical nanofillers, on the other hand, could disrupt the flow field during degradation, causing the slurry to flow in a turbulent state, thereby reducing the settling velocity and facilitating the crushing and degradation of food waste. After degradation, the COD content of the carbon source reached 180,056 ml / L. Therefore, conical nanofillers were selected for degradation in subsequent experiments.

[0058] During the experiment, four different experimental parameters were set up to compare the effects of microbial communities and nanofillers on the COD of degraded kitchen waste. To ensure the rigor of the experiment, a parallel experiment was set up to calculate the average value. The four experimental parameters were (1) kitchen waste; (2) kitchen waste + microbial community; (3) kitchen waste + nanofiller; and (4) kitchen waste + microbial community + nanofiller. After the hydrolysis and acidification simulation test, the COD of the carbon source after the degradation of kitchen waste in the four experimental groups were 70200 mg / L, 100800 mg / L, 120040 mg / L, and 180056 mg / L, respectively.

[0059] Experimental results show that incomplete hydrolysis and acidification of kitchen waste leads to a large amount of organic matter entering the solid residue and being lost. However, the degradation effect of adding only biological microorganisms and nanofillers on kitchen waste is limited. After the addition of biological microorganisms and nanofillers for synergistic degradation, the carbon source COD can reach 180056 mg / L, which is far greater than the theoretical COD content. Therefore, it indicates that biological microorganisms and nanofillers have a synergistic effect. The synergistic mechanism mainly consists of two parts: 1. The large π bonds contained in phenolic resin during the bonding and calcination process are conducive to the free movement of electrons during microbial metabolism. 2. The Fe active particles loaded in the nanofillers can not only change the membrane potential of microorganisms and increase the permeability of the extracellular membrane, but also act as important signal transduction mediators, accelerate microbial electron transfer, promote enzymatic reactions, and reconstruct the microbial metabolic reaction environment.

[0060] The advantages of this invention are:

[0061] This invention utilizes Fe-loaded carbon-based materials in conjunction with microorganisms to recycle food waste, offering advantages such as being environmentally friendly, low-cost, highly efficient, and reusable. It also produces carbon source additives from food waste for wastewater treatment plants, supplementing the carbon source for microorganisms. This approach achieves both the harmless and resource-based treatment of food waste and solves the technical challenges faced by wastewater treatment plants.

[0062] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a carbon source from kitchen waste, characterized in that, include: Preparation of Fe-supported carbon nanomaterials; Preparation of Fe-supported carbon aerogel materials; Fe-supported carbon nanomaterials and Fe-supported carbon aerogel materials were weighed according to a preset ratio to obtain a mixed powder. The mixed powder is bonded with resin, then pressed and calcined to obtain a cone-shaped filler. The conical packing material and kitchen waste are added to the pulping container of the carbon source preparation machine, along with the microbial community required for the hydrolysis and acidification of the kitchen waste; stirring is then started to obtain the carbon source.

2. The method for preparing a carbon source from kitchen waste as described in claim 1, characterized in that, The food waste has a particle size of 3-10mm and a moisture content of less than 80%; the COD of the carbon source product is higher than 150,000mg / L.

3. The method for preparing a carbon source from kitchen waste as described in claim 1, characterized in that, The preparation of Fe-supported carbon nanomaterials includes: The carbon-based material is immersed in an excess of ferric salt solution, the pH of the mixture is adjusted to alkaline, the precipitate is collected after stirring and thoroughly washed with deionized water and ethanol, dried and then pyrolyzed at high temperature to ensure that Fe is fully oxidized and attached to the surface of the carbon-based material in the form of ferric iron, thus obtaining Fe-loaded carbon nanomaterials.

4. The method for preparing a carbon source from kitchen waste as described in claim 3, characterized in that, The preparation of Fe-supported carbon aerogel material includes: Gelatin and silica powder were dissolved in deionized water, and after magnetic stirring, the gelatin was completely dissolved in a water bath. Repeated freeze-thaw treatment was performed to obtain a stable hydrogel. The hydrogel was then freeze-dried under vacuum and pyrolyzed. After natural cooling, the SiO2 nanoparticles were removed with hydrofluoric acid solution, and then thoroughly washed with deionized water and ethanol. After drying, a carbon aerogel carrier was obtained. The carbon aerogel support was immersed in an excess of ferric salt solution. The pH of the mixture was adjusted to alkaline. After stirring, the precipitate was collected and thoroughly washed with deionized water and ethanol. After drying, it was pyrolyzed at high temperature to ensure that Fe was fully oxidized and attached to the surface of the carbon aerogel support in the form of ferric iron, thus obtaining the Fe-loaded carbon aerogel material.

5. The method for preparing a carbon source from kitchen waste as described in claim 4, characterized in that, The carbon-based materials are petroleum coke and pitch coke, with a weight ratio of (2~4):

1. The ferric salt solution is a ferric nitrate solution; The pH of the mixture was adjusted to 9-11 by adding sodium hydroxide. The mixture was stirred at 70-90℃ for 0.5-1.5 hours, and the precipitate was collected. After the precipitate is dried in an oven at 70~90℃, it is calcined in a tube furnace at 500~600℃ for 3~5 hours to fully oxidize Fe and attach it to the surface of carbon-based materials or carbon aerogel carrier in the form of ferric iron. After the hydrogel is freeze-dried under vacuum for 10-15 hours, it is heated to 700-900℃ at a heating rate of 3-6℃ / min and then pyrolyzed in a tube furnace for 3-5 hours.

6. The method for preparing a carbon source from kitchen waste as described in claim 1, characterized in that, The required addition ratio of Fe-supported carbon nanomaterials and Fe-supported carbon aerogels is to ensure that the prepared conical filler can be uniformly distributed and suspended in the kitchen waste in the pulping container, so as to ensure that the upper, middle and lower parts of the kitchen waste can be better processed.

7. The method for preparing a carbon source from kitchen waste as described in claim 1, characterized in that, The process involves bonding mixed powders with resin, followed by pressing, molding, and calcination to obtain a cone-shaped filler; comprising: Phenolic resin is used to bind the mixed powder; wherein the weight ratio of the mixed powder to the phenolic resin is (1.5~2.5):

1. The bonded mixed powder is pressed into shape under a molding pressure of 100~150MPa, and then calcined at 800~1200℃ to obtain a cone-shaped filler.

8. The method for preparing a carbon source from kitchen waste as described in claim 1, characterized in that, The conical packing added to the pulping container accounts for 30% to 40% of the container's volume and is below the container's centerline. The lower dimensions of the conical packing include Φ80mm, Φ60mm, Φ50mm, and Φ40mm, with corresponding upper dimensions of Φ70mm, Φ50mm, Φ40mm, and Φ30mm. The height of the conical packing is 70mm, and the volume ratio of each dimension is Φ80mm:Φ60mm:Φ50mm:Φ40mm = 20:35:25:

20.

9. The method for preparing a carbon source from kitchen waste as described in claim 1, characterized in that, The microbial community added to the pulping container includes the phylum Chlorophytum of hydrolytic bacteria and the phylum Firmicutes and Actinobacteria of acid-producing bacteria.

10. The method for preparing a carbon source from food waste as described in claim 1, characterized in that, The carbon source preparation machine includes a pulping container and support legs that support the pulping container; The pulping container is equipped with a stirrer. The top of the pulping container is equipped with a feeding port for adding conical packing material, kitchen waste and microorganisms. The bottom of the pulping container is equipped with a discharge port and a packing material outlet. A filter screen is installed on the discharge port.

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