Method for preparing carbon source from kitchen waste

Abstract

The invention discloses a method for preparing a carbon source from kitchen waste, and belongs to the technical field of organic waste treatment. Comprising the following steps: preparing a Fe-loaded carbon nanomaterial; preparing a Fe-loaded carbon aerogel material; weighing the Fe-loaded carbon nanomaterial and the Fe-loaded carbon aerogel material according to a preset proportion to obtain mixed powder; the mixed powder is bonded through resin, then compression molding and roasting are conducted, and the conical filler is obtained; adding the conical filler and the kitchen waste into a pulping container of a carbon source preparation machine, and adding flora required for hydrolytic acidification of the kitchen waste; starting stirring to prepare the carbon source. According to the method, the kitchen waste is recycled through cooperation of the Fe-loaded carbon-based material and microorganisms, and the method has the advantages of being environmentally friendly, low in cost, high in efficiency, capable of being repeatedly used and the like.

Description

Technical Field

[0001] The invention relates to the technical field of organic waste treatment, and in particular to a method for preparing a carbon source from kitchen waste. Background Art

[0002] In most of my country's urban sewage treatment plants, there is a problem of insufficient carbon source in the influent, and additional carbon source needs to be added to improve the denitrification effect in order to meet the discharge standards. Therefore, how to improve the denitrification efficiency of wastewater has become a technical problem currently faced by sewage treatment plants.

[0003] With the improvement of my country's economic level, the output of restaurant kitchen waste has also been growing; the main components of restaurant kitchen waste are carbohydrates, proteins and fats, among which the organic matter content is very high, which is an ideal raw material for producing carbon sources through anaerobic fermentation and acid production. If it is not properly handled, it is easy to cause secondary pollution and waste of resources. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a method for preparing a carbon source from kitchen waste.

[0005] The present invention discloses a method for preparing a carbon source from kitchen waste, comprising: Preparation of Fe-loaded carbon nanomaterials; Preparation of Fe-loaded carbon aerogel material; Weigh Fe-loaded carbon nanomaterials and Fe-loaded carbon aerogel materials according to a preset ratio to obtain a mixed powder; The mixed powder is bonded with resin, and then pressed and calcined to obtain a conical filler; The conical filler and the food waste are added into the pulping container of the carbon source preparation machine, and the bacteria required for hydrolyzing and acidifying the food waste are added; stirring is started to prepare the carbon source.

[0006] As a further improvement of the present invention, the particle size of the kitchen waste is 3-10 mm, and the moisture content is lower than 80%; the COD of the finished carbon source product is higher than 150000 mg / L.

[0007] As a further improvement of the present invention, the preparation of Fe-loaded carbon nanomaterials comprises: The carbon-based material is immersed in an excess of trivalent iron salt solution to ensure sufficient Fe loading, the pH of the mixed solution is adjusted to alkaline, the precipitate is collected after stirring and fully washed with deionized water and ethanol, and then dried and 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 trivalent iron, so as to obtain a density of 1.8~2.2g / cm 3 Fe-loaded carbon nanomaterials.

[0008] As a further improvement of the present invention, the preparation of Fe-loaded carbon nanomaterials comprises: Gelatin and silica powder are dissolved in deionized water, and then magnetically stirred and placed in a water bath to completely dissolve the gelatin, and then subjected to repeated freeze-thaw treatment to obtain a stable hydrogel; the hydrogel is vacuum freeze-dried and then pyrolyzed, and after natural cooling, SiO2 nanoparticles are removed with a hydrofluoric acid solution, and then fully washed with deionized water and ethanol, and dried to obtain a carbon aerogel carrier; The carbon aerogel carrier was immersed in an excess of trivalent iron salt solution to ensure sufficient Fe loading, the pH of the mixed solution was adjusted to alkaline, the precipitate was collected after stirring and washed thoroughly with deionized water and ethanol, and then dried and pyrolyzed at high temperature to ensure that Fe was fully oxidized and attached to the surface of the carbon aerogel carrier in the form of trivalent iron, thus obtaining a density of 0.12~0.18g / cm 3 Fe-loaded carbon aerogel materials.

[0009] As a further improvement of the present invention, The carbon-based material is petroleum coke and asphalt coke, the weight ratio of petroleum coke to asphalt coke is (2-4):1, and the preferred weight ratio of petroleum coke to asphalt coke is 3:1; The ferric salt solution is ferric nitrate solution; The pH of the mixture is adjusted to 9-11, preferably 10, by adding sodium hydroxide; The mixed solution is stirred at 70-90°C for 0.5-1.5h and the precipitate is collected, preferably at 80°C for 1h; After the precipitate is dried in an oven at 70-90°C, it is fired in a tube furnace at 500-600°C for 3-5 hours, so that Fe is fully oxidized and attached to the surface of the carbon-based material or carbon aerogel carrier in the form of trivalent iron; preferably, after the precipitate is dried in an oven at 80°C, it is fired in a tube furnace at 550°C for 4 hours; After the hydrogel is freeze-dried in vacuum for 10 to 15 hours, the temperature is increased to 700 to 900°C at a heating rate of 3 to 6°C / min, and pyrolyzed in a tubular furnace for 3 to 5 hours; preferably, after the hydrogel is freeze-dried in vacuum for 12 hours, the temperature is increased to 800°C at a heating rate of 5°C / min, and pyrolyzed in a tubular furnace for 4 hours.

[0010] As a further improvement of the present invention, the requirement for the addition ratio of the Fe-loaded carbon nanomaterial and the Fe-loaded carbon aerogel material is as follows: to ensure that the prepared conical filler can be evenly distributed and suspended in the food waste in the pulping container, so as to ensure that the upper, middle and lower parts of the food waste can be better processed; that is, by adding a low-density Fe-loaded carbon aerogel material to adjust the density of the prepared conical filler, the density of the conical filler is similar to that of the solution of the food waste, so that the conical filler can cooperate with the microorganisms in the upper, middle and bottom layers of the solution during use; preferably, the weight ratio of the upper part of the conical filler: the Fe-loaded carbon nanomaterial to the Fe-loaded carbon aerogel material is 1:0, the weight ratio of the middle part of the conical filler: the Fe-loaded carbon nanomaterial to the Fe-loaded carbon aerogel material is 4:5, and the weight ratio of the lower part of the conical filler: the Fe-loaded carbon nanomaterial to the Fe-loaded carbon aerogel material is 1:0; the specific heights of the upper, middle and lower parts can be selected to each account for 1 / 3 of the overall height.

[0011] As a further improvement of the present invention, the mixed powder is bonded with resin, and then pressed and calcined to obtain a conical filler; comprising: The mixed powder is bonded with phenolic resin; wherein the weight ratio of the mixed powder to the phenolic resin is (1.5-2.5):1, preferably 2:1; The mixed powder after bonding is pressed and molded at a molding pressure of 100-150 MPa, and then calcined at 800-1200° C. to obtain a conical filler.

[0012] As a further improvement of the present invention, the conical filler 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 filler include Φ80mm, Φ60mm, Φ50mm and Φ40mm, and the corresponding upper dimensions are Φ70mm, Φ50mm, Φ40mm and Φ30mm, and the height dimensions of each filler are 70mm. The volume ratio of each dimension is Φ80mm:Φ60mm:Φ50mm:Φ40mm=20:35:25:20.

[0013] As a further improvement of the present invention, the bacterial community added to the pulping container includes Chloroflexi among hydrolytic bacteria and Firmicutes and Actinobacteria among acid-producing bacteria. The total amount of the bacterial community added is bacterial community: organic matter = 1:400, and the added amounts of Chloroflexi, Firmicutes and Actinobacteria are 1:1:1.

[0014] As a further improvement of the present invention, the carbon source preparation machine includes a pulping container and legs supporting the pulping container; The pulping container is provided with a stirrer, the top of the pulping container is provided with a feeding port for adding conical fillers, kitchen waste and bacterial flora, the bottom of the pulping container is provided with a discharge port and a filler outlet, and the discharge port is provided with a filter.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention utilizes Fe-loaded carbon-based materials to coordinate microorganisms to recycle kitchen waste, which has the advantages of being green, environmentally friendly, low cost, high efficiency, and reusable. The kitchen waste is made into a carbon source additive required by a sewage treatment plant to supplement the microbial carbon source. This can not only achieve harmless resource processing of kitchen waste, but also solve the technical problems of sewage treatment plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A flow chart of the method for preparing carbon sources from food waste disclosed in the present invention; Figure 2 It is a structural schematic diagram of a carbon source preparation machine; Figure 3 Schematic diagram of conical packing.

[0017] In the figure: 1. Pulping container; 2. Support legs; 3. Agitator; 4. Feeding port; 5. Discharging port; 6. Filling outlet; 7. Filter screen. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0019] The present invention is further described in detail below in conjunction with the accompanying drawings: like Figure 1 As shown, the present invention provides a method for preparing a carbon source from kitchen waste, comprising: Step 1: Preparation of Fe-loaded carbon nanomaterials: The carbon-based material (petroleum coke: asphalt coke = 3:1) was immersed in an excess of ferric nitrate solution to ensure sufficient loading of Fe; 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 washed thoroughly with deionized water and ethanol, and finally the washed precipitate was dried in an oven at 80°C and calcined at 550°C in a tube furnace for 4 hours to ensure that Fe was fully oxidized and attached to the surface of the carbon-based material in the form of trivalent iron, that is, a density of about 2 g / cm3 Fe-loaded carbon nanomaterials.

[0020] Step 2: Preparation of Fe-loaded carbon aerogel material: Gelatin and silica powder were dissolved in deionized water, stirred magnetically for 30 min, and then completely dissolved in a 70°C water bath. Cold thawing treatment was performed three times in succession to form a stable hydrogel, which was then freeze-dried in a vacuum for 12 h, heated to 800°C at a heating rate of 5°C / min, and pyrolyzed in a tube furnace for 4 h. After cooling naturally to room temperature, SiO2 nanoparticles were removed with a hydrofluoric acid solution, and then fully washed with deionized water and ethanol, and dried in an oven at 80°C to obtain a carbon aerogel carrier.

[0021] The carbon aerogel carrier was immersed in an excess of ferric nitrate solution to ensure sufficient loading of Fe; 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 washed with deionized water and ethanol, and finally the washed precipitate was dried in an oven at 80°C and calcined at 550°C in a tube furnace for 4 hours to ensure that Fe was fully oxidized and attached to the surface of the carbon aerogel carrier in the form of trivalent iron, that is, a density of about 0.15 g / cm 3 Fe-loaded carbon aerogel materials.

[0022] Step 3: weigh Fe-loaded carbon nanomaterials and Fe-loaded carbon aerogel materials according to a preset ratio to obtain a mixed powder; wherein: The requirement for the addition ratio of Fe-loaded carbon nanomaterial and Fe-loaded carbon aerogel material is: to ensure that the prepared conical filler can be evenly distributed and suspended in the food waste in the pulping container, so as to ensure that the upper, middle and lower parts of the food waste can be better processed; that is, by adding low-density Fe-loaded carbon aerogel material to adjust the density of the prepared conical filler, the density of the conical filler and the solution of food waste are similar, so that the conical filler can cooperate with the microorganisms in the upper, middle and bottom layers of the solution during use; preferably, the weight ratio of the upper part of the conical filler: Fe-loaded carbon nanomaterial to Fe-loaded carbon aerogel material is 1:0, the middle part of the conical filler: Fe-loaded carbon nanomaterial to Fe-loaded carbon aerogel material is 4:5, and the lower part of the conical filler: Fe-loaded carbon nanomaterial to Fe-loaded carbon aerogel material is 1:0; the specific heights of the upper, middle and lower parts can be selected to each account for 1 / 3 of the overall height.

[0023] Step 4: Use phenolic resin to bond the mixed powder to ensure that the bending strength and compressive strength of the material can reach about 41 MPa and about 55 MPa respectively; wherein the weight ratio of the mixed powder to the phenolic resin is 2:1.

[0024] Step 5: Pressing and molding the bonded mixed powder at 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 allowing the filler to have good electrical conductivity.

[0025] Step 6, calcining at 1000°C to obtain a conical filler; wherein the phenolic resin forms a planar network structure during the high temperature calcination process, and the layer contains abundant large π bonds, which is conducive to the free movement of electrons, so that the filler can better cooperate with microorganisms to degrade food waste. The conical filler will disrupt the flow field during use, causing the slurry to flow in a turbulent state, thereby reducing the sedimentation rate, which is conducive to the crushing and degradation of food waste.

[0026] Step 7: Add the conical filler and the food waste into the pulping container of the carbon source preparation machine, and add the bacteria required for hydrolyzing and acidifying the food waste; start stirring to prepare the carbon source; wherein, Conical packing Figure 3 As shown in the figure, the height size of each filler is 70mm. If too much conical filler is added, they will overlap each other and cannot fully exert the crushing capacity. At the same time, the kinetic energy consumption is increased. If too little conical filler is added, the crushing capacity is relatively limited. For this reason, the conical filler added to the pulping container is selected to be 30%~40% of the volume of the pulping container and is lower than the center line of the container. The sizes of the conical filler include Φ80mm, Φ60mm, Φ50mm and Φ40mm, and the above sizes are all the lower diameters of the filler. The corresponding upper sizes are Φ70mm, Φ50mm, Φ40mm and Φ30mm, respectively, and the volume ratio of each size is Φ80mm:Φ60mm:Φ50mm:Φ40mm=20:35:25:20.

[0027] The bacterial flora added to the pulping container includes Chloroflexi among hydrolytic bacteria and Firmicutes and Actinobacteriota among acid-producing bacteria, which synergize with the conical filler to degrade food waste to prepare a carbon source; the total amount of the bacterial flora added is bacterial flora: organic matter = 1:400, and the addition amounts of Chloroflexi, Firmicutes and Actinobacteria are 1:1:1, so as to carry out synergistic degradation and ensure that the filler and the microorganisms exert the best synergistic effect.

[0028] like Figure 2As shown, the carbon source preparation machine includes a pulping container 1 and a leg 2 for supporting the pulping container; a stirrer 3 is arranged in the pulping container 1, a feeding port 4 for adding conical fillers, food waste and bacterial flora is arranged on the top of the pulping container 1, a discharge port 5 and a filler outlet 6 are arranged at the bottom of the pulping container, and a 100-mesh filter screen 7 is arranged on the discharge port 5; the material is processed in a batch manner, 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, and after the internal filler is severely worn, it can be discharged from the filler outlet 6 and replenished from the feeding port 4.

[0029] test: In the experiment to determine the shape of nanofillers, spherical and conical fillers were selected according to the principle of ball mill and biological flora to crush and degrade food waste. The experimental results showed that the COD content of carbon source was 140520ml / L during the degradation process of spherical nanofillers and microorganisms. The conical nanofillers and microorganisms can disturb the flow field and make the slurry flow in a turbulent state, thereby reducing the sedimentation rate, which is conducive to the crushing and degradation of food waste. The COD content of carbon source after degradation reached 180056ml / L. Therefore, conical nanofillers were selected for degradation in subsequent experiments.

[0030] During the experiment, a total of 4 groups of different experimental parameters were set up to compare the effects of biological flora and nanofillers on the COD after the degradation of food waste. At the same time, in order to ensure the rigor of the experiment, a group of parallel experiments were set up to calculate the average value. The 4 groups of experimental parameters were (1) food waste; (2) food waste + biological flora; (3) food waste + nanofillers; (4) food waste + biological flora + nanofillers. After the hydrolysis and acidification simulation test, the COD of the carbon source after the degradation of the food waste in the 4 groups of experiments was 70200mg / L, 100800mg / L, 120040mg / L, and 180056mg / L, respectively.

[0031] The experimental results show that the incomplete hydrolysis and acidification process of food waste causes a large amount of organic matter to enter the solid residue and be lost. However, the degradation effect of only adding biological flora and nanofillers on food waste is limited. After adding biological flora and nanofillers for synergistic degradation, the carbon source COD can reach 180056 mg / L, which is much larger than the theoretical carbon source COD content. Therefore, it shows that the biological colony and nanofillers have a synergistic effect. The synergistic mechanism is mainly divided into two parts: 1. The large π bond contained in phenolic resin during the bonding and roasting process is conducive to the free movement of electrons in the microbial metabolism process. 2. The Fe active particles loaded in the nanofiller can not only change the membrane potential of microorganisms and improve the permeability of the extracellular membrane, but also act as an important signal transduction transmitter, accelerate microbial electron transfer, promote the occurrence of enzymatic reactions, and reconstruct the microbial metabolic reaction environment.

[0032] The advantages of the present invention are: The present invention utilizes Fe-loaded carbon-based materials to coordinate microorganisms to recycle kitchen waste, which has the advantages of being green, environmentally friendly, low cost, high efficiency, and reusable. The kitchen waste is made into a carbon source additive required by a sewage treatment plant to supplement the microbial carbon source. This can not only achieve harmless resource processing of kitchen waste, but also solve the technical problems of sewage treatment plants.

[0033] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a carbon source from kitchen waste, characterized in that: include: Preparation of Fe-loaded carbon nanomaterials; Preparation of Fe-loaded carbon aerogel material; Weigh Fe-loaded carbon nanomaterials and Fe-loaded carbon aerogel materials according to a preset ratio to obtain a mixed powder; The mixed powder is bonded with resin, and then pressed and calcined to obtain a conical filler; The conical filler and the food waste are added into the pulping container of the carbon source preparation machine, and the bacteria required for hydrolyzing and acidifying the food waste are added; stirring is started to prepare the carbon source.

2. The method for preparing carbon source from food waste according to claim 1, characterized in that: The particle size of the kitchen waste is 3-10 mm, and the moisture content is lower than 80%; the COD of the finished carbon source product is higher than 150000 mg / L.

3. The method for preparing carbon source from food waste according to claim 1, characterized in that: The method for preparing Fe-loaded carbon nanomaterials comprises: The carbon-based material is immersed in an excess of trivalent iron salt solution, the pH of the mixed solution is adjusted to alkaline, the precipitate is collected after stirring and washed thoroughly with deionized water and ethanol, and then dried and 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 trivalent iron, thereby obtaining Fe-loaded carbon nanomaterials.

4. The method for preparing carbon source from food waste according to claim 3, characterized in that: The method for preparing Fe-loaded carbon nanomaterials comprises: Gelatin and silica powder are dissolved in deionized water, and then magnetically stirred and placed in a water bath to completely dissolve the gelatin, and then subjected to repeated freeze-thaw treatment to obtain a stable hydrogel; the hydrogel is vacuum freeze-dried and then pyrolyzed, and after natural cooling, SiO2 nanoparticles are removed with a hydrofluoric acid solution, and then fully washed with deionized water and ethanol, and dried to obtain a carbon aerogel carrier; The carbon aerogel carrier is immersed in an excess of trivalent iron salt solution, the pH of the mixed solution is adjusted to alkaline, the precipitate is collected after stirring and washed thoroughly with deionized water and ethanol, and then dried and pyrolyzed at high temperature to ensure that Fe is fully oxidized and attached to the surface of the carbon aerogel carrier in the form of trivalent iron, thereby obtaining Fe-loaded carbon aerogel material.

5. The method for preparing carbon source from food waste according to claim 4, characterized in that: The carbon-based materials are petroleum coke and asphalt coke, and the weight ratio of petroleum coke to asphalt coke is (2-4):1; The ferric salt solution is ferric nitrate solution; The pH of the mixture was adjusted to 9-11 by adding sodium hydroxide; The mixed solution is stirred at 70-90°C for 0.5-1.5h and the precipitate is collected, preferably at 80°C for 1h; After the precipitate is dried in an oven at 70-90°C, it is fired in a tube furnace at 500-600°C for 3-5h to fully oxidize Fe and attach it to the surface of the carbon-based material or carbon aerogel carrier in the form of trivalent iron; After the hydrogel was freeze-dried in vacuum for 10-15 h, the temperature was raised to 700-900 °C at a heating rate of 3-6 °C / min and pyrolyzed in a tubular furnace for 3-5 h.

6. The method for preparing carbon source from food waste according to claim 1, characterized in that: The requirement for the addition ratio of the Fe-loaded carbon nanomaterial and the Fe-loaded carbon aerogel material is to ensure that the prepared conical filler can be evenly distributed and suspended in the food waste in the pulping container, so as to ensure that the upper, middle and lower parts of the food waste can be better processed.

7. The method for preparing carbon source from food waste according to claim 1, characterized in that: The mixed powder is bonded with resin, and then pressed and calcined to obtain a conical filler; comprising: The mixed powder is bonded with phenolic resin; wherein the weight ratio of the mixed powder to the phenolic resin is (1.5-2.5):1, preferably 2:1; The mixed powder after bonding is pressed and molded at a molding pressure of 100-150 MPa, and then calcined at 800-1200° C. to obtain a conical filler.

8. The method for preparing carbon source from food waste according to claim 1, characterized in that: The conical filler added to the pulping container is 30%~40% of the volume of the pulping container and is lower than the center line of the container; the lower dimensions of the conical filler include Φ80mm, Φ60mm, Φ50mm and Φ40mm, and the corresponding upper dimensions are Φ70mm, Φ50mm, Φ40mm and Φ30mm. The height of the conical filler is 70mm, and the volume ratio of each dimension is Φ80mm:Φ60mm:Φ50mm:Φ40mm=20:35:25:

20.

9. The method for preparing carbon source from food waste according to claim 1, characterized in that: The bacterial flora added to the pulping container includes Chloroflexi among hydrolytic bacteria and Firmicutes and Actinobacteria among acid-producing bacteria. The total amount of bacterial flora added is bacterial flora: organic matter = 1:400, and the amount of Chloroflexi, Firmicutes and Actinobacteria added is 1:1:

1.

10. The method for preparing carbon source from food waste according to claim 1, characterized in that: The carbon source preparation machine includes a pulping container and legs supporting the pulping container; The pulping container is provided with a stirrer, the top of the pulping container is provided with a feeding port for adding conical fillers, kitchen waste and bacterial flora, the bottom of the pulping container is provided with a discharge port and a filler outlet, and the discharge port is provided with a filter.

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