A method and system for preparing a carbon source for sewage treatment by anaerobic acidogenic fermentation of kitchen waste

Abstract

The present application belongs to the technical field of sewage treatment, and relates to a method and system for preparing a sewage treatment carbon source through anaerobic acid production fermentation of kitchen waste. The present application discloses a method and system for preparing a sewage treatment carbon source through anaerobic acid production fermentation of kitchen waste. The method first uses kitchen waste as an anaerobic fermentation raw material. After pretreatment steps such as sorting, impurity removal, and three-phase separation, the separated crude oil is sold, and the water phase and the solid phase are homogenized and then fed into an anaerobic reactor for fermentation. The output fermentation slurry is centrifuged and dewatered, and then piped to a sewage treatment plant for use as an additional carbon source. The method is realized through a system comprising a crushing and sorting system, a three-phase separator, a homogenizing tank, an anaerobic fermentation tank, a centrifuge, and a fermentation liquid conveying pipeline. The present application uses kitchen waste anaerobic fermentation liquid to improve the COD of sewage in sewage treatment, thereby reducing costs and achieving efficient removal of pollutants.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology and relates to a method and system for preparing a carbon source for wastewater treatment through anaerobic acid fermentation of kitchen waste. Background Technology

[0002] This invention belongs to the field of wastewater treatment technology and relates to a method and system for preparing a carbon source for wastewater treatment through anaerobic acid fermentation of kitchen waste.

[0003] Most urban wastewater treatment plants in my country have low C / N ratios in their influent, limiting the efficiency of traditional biological methods for removing nitrogen and phosphorus, making it difficult to meet discharge standards. To address this issue, wastewater treatment plants typically add external carbon sources, such as sodium acetate or methanol, during the treatment process. However, the use of traditional chemical carbon sources not only increases the operating costs of wastewater treatment plants but also results in higher CO2 emissions. Therefore, it is necessary to find an alternative carbon source that can reduce costs while decreasing carbon emissions. During anaerobic fermentation, organic solid waste is hydrolyzed into dissolved organic matter and acidified into organic acids, making it easier for microorganisms to utilize solid waste. Many studies have tested the effectiveness of volatile fatty acids (VFAs) as a carbon source in the denitrification process. Food waste, as a typical type of organic urban solid waste, is abundant, has high organic matter content, and good biodegradability. The fermentation slurry produced by its anaerobic fermentation contains a large amount of VFAs, as well as lactic acid, alcohols, and other substances, which can be effectively utilized as a carbon source to enhance nutrient removal.

[0004] The patent application with application number "CN202311536444.2" and titled "A Liquid Composite Carbon Source for Wastewater Treatment" describes a technical solution that uses agricultural waste soaking liquid as a solvent to construct a dispersion system with a low-concentration composite carbon source, and adds trace elements and components such as potassium and phosphorus to provide comprehensive and rich nutritional conditions for water treatment microorganisms. Specifically, this composite carbon source uses boric acid, manganese chloride, zinc sulfate, and copper sulfate as trace elements, and constructs a composition with sodium nitrate, potassium dihydrogen phosphate, ferric ammonium citrate, disodium EDTA, sodium carbonate, calcium acetate, sodium acetate, glucose, and potassium lactate. This composition is then dissolved in the soaking liquid of corn stalks and rice husks to obtain the composite carbon source. While this method uses agricultural waste soaking liquid as a base, its components are insufficient to provide comprehensive nutrients for microorganisms; therefore, it still needs to be mixed with a low-concentration composite carbon source to support microbial growth and achieve the corresponding denitrification effect.

[0005] Chinese patent CN118771613A discloses a liquid composite carbon source for wastewater treatment and its preparation method. The liquid composite carbon source for wastewater treatment comprises the following raw materials in parts by weight: 100-120 parts plant extract, 3-6 parts functional filler, 3-5 parts functional additives, 2-4 parts glucose, 4-7 parts glycerol, 6-10 parts sodium acetate, 4-7 parts potassium lactate, and 2-5 parts compounded nanoparticles. The process involves mixing the functional filler, functional additives, glucose, glycerol, sodium acetate, potassium lactate, and compounded nanoparticles in a mixing device to obtain a mixture. This mixture is then placed in the plant extract and mixed to obtain the final liquid composite carbon source for wastewater treatment. The prepared liquid composite carbon source for wastewater treatment exhibits good carbon release rate performance and excellent denitrification performance. However, this method requires a large number of raw materials and involves a complex preparation method, requiring multiple raw materials to undergo ultrasonication, soaking, and drying operations, increasing the cost of using the carbon source.

[0006] In conclusion, it is essential to develop a low-carbon carbon source for wastewater treatment that also has good denitrification performance and low cost.

[0007] The purpose of this invention is to provide a method and system for enhancing the denitrification effect of wastewater treatment through anaerobic acid-producing fermentation broth from kitchen waste. This method utilizes kitchen waste to prepare a carbon source for wastewater treatment, possessing good ecological benefits while achieving excellent denitrification. It can solve the problems mentioned above in the existing technology.

[0008] According to a first aspect of the present invention, a method for enhancing the denitrification effect of wastewater treatment using anaerobic acid-producing fermentation broth from kitchen waste includes the following steps:

[0009] According to another aspect of the present invention, a system for enhancing the denitrification effect of wastewater treatment through anaerobic acid-producing fermentation broth from kitchen waste is also provided, comprising:

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0011] (1) Low-carbon and green, using kitchen waste to treat waste, avoiding additional carbon emissions from the use of chemical carbon sources.

[0012] (2) The cost is low. It utilizes kitchen waste to prepare carbon sources for wastewater treatment, and at the same time, it treats the kitchen waste.

[0013] This reduced the cost of using carbon sources in wastewater treatment plants. Summary of the Invention

[0014] The purpose of this invention is to provide a method and system for enhancing the denitrification effect of wastewater treatment through anaerobic acid-producing fermentation broth from kitchen waste. This method utilizes kitchen waste to prepare a carbon source for wastewater treatment, possessing good ecological benefits while achieving excellent denitrification. It can solve the problems mentioned above in the existing technology.

[0015] According to a first aspect of the present invention, a method for enhancing the denitrification effect of wastewater treatment using anaerobic acid-producing fermentation broth from kitchen waste includes the following steps:

[0016] Step 100: After the food waste is unloaded, it is crushed and sorted to remove glass, plastic and other non-degradable components, and then transported to a three-phase separator.

[0017] Step 200: After the kitchen waste enters the three-phase separator, the separated crude oil is transported off-site for sale. The solid and aqueous phases are fed into a homogenizing tank, homogenized, and then enter an anaerobic digester for anaerobic fermentation.

[0018] Step 300: After fermentation, the slurry is output from the anaerobic fermenter and enters a centrifuge. After centrifugation to remove solids, the fermentation liquid is transported to the sewage treatment plant through pipeline.

[0019] In one embodiment, the fermentation temperature of the anaerobic fermenter in step 200 is approximately 35°C.

[0020] In one embodiment, the hydraulic retention time of the anaerobic fermenter in step 200 is 7 days.

[0021] In one embodiment, the anaerobic fermenter described in step 200 has a fermentation pH of 6.

[0022] In one embodiment, the non-degradable components separated by crushing and decomposition in step 100 account for approximately 5%-10% of the total processed volume.

[0023] According to another aspect of the present invention, a system for enhancing the denitrification effect of wastewater treatment through anaerobic acid-producing fermentation broth from kitchen waste is also provided, comprising:

[0024] Unloading hopper, crushing and sorting system, three-phase separator, homogenizing tank, anaerobic fermentation tank, centrifuge, fermentation broth conveying pipeline.

[0025] The crushing and sorting system includes a feeding screw, a sorting separator, and a high-concentration sand remover; the sorting separator and the high-concentration sand remover are connected by pipelines; the high-concentration sand remover is connected to the three-phase separator by a pipeline.

[0026] The three-phase separator includes an oil phase outlet, a solid phase outlet, and an aqueous phase outlet; the solid phase outlet and the aqueous phase outlet of the three-phase separator are connected to a homogenizing tank via pipelines; the homogenizing tank is connected to an anaerobic fermentation tank via pipelines.

[0027] The anaerobic fermenter includes an inlet, an outlet, a stirrer, a steam heating pipeline, an exhaust port, and a reagent dosing pump; the outlet is connected to a centrifuge via a pipeline; the inlet is located at the top of the anaerobic fermenter; the outlet is located at the bottom of the anaerobic fermenter; the reagent dosing pump is located on the other side of the inlet; the steam heating pipeline surrounds the outside of the anaerobic fermenter; and the exhaust port is located next to the reagent dosing pump.

[0028] The centrifuge includes a fermentation broth outlet and a solid residue outlet; the fermentation broth outlet is directly connected to the fermentation broth conveying pipeline.

[0029] In one embodiment, the actual volume of the anaerobic fermenter is 10% larger than the actual volume of the reaction mixture;

[0030] In one embodiment, the insulation layer of the anaerobic fermenter is located on its exterior, and the insulation layer thickness is 0.075-0.1m; the insulation layer material is one or more of glass fiber insulation material, rock wool board, polyurethane foam, polystyrene board, and aluminum silicate fiber felt.

[0031] In one embodiment, the stirring speed of the agitator in the anaerobic fermenter is 40-85 rpm;

[0032] In one embodiment, the anaerobic fermenter has a minimum surface diameter to height ratio of 1 for a given volume.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] (1) Low-carbon and green, using kitchen waste to treat waste, avoiding additional carbon emissions from the use of chemical carbon sources.

[0035] (2) The cost is low. It utilizes kitchen waste to prepare carbon sources for wastewater treatment, and at the same time, it treats the kitchen waste.

[0036] This reduced the cost of using carbon sources in wastewater treatment plants. Attached Figure Description

[0037] The invention will now be described in more detail with reference to embodiments and the accompanying drawings.

[0038] Figure 1 This is a schematic diagram of a method for preparing carbon sources for wastewater treatment through anaerobic acid fermentation of kitchen waste. Figure 2This is a schematic diagram of a system for preparing carbon sources for wastewater treatment through anaerobic acid fermentation of kitchen waste.

[0039] Figure label:

[0040] 1. Unloading hopper 2. Crushing and sorting system

[0041] 3 Three-phase separator 4 Homogenizing tank

[0042] 5 Anaerobic fermenter 6 Centrifuge

[0043] 7. Fermentation broth conveying pipeline 201 Feed screw

[0044] 202 Sorting and Separating Machine; 203 High-Efficiency Sand Remover

[0045] 301 Oil phase outlet; 302 Solid phase outlet

[0046] 303 Aqueous phase outlet; 501 Feed inlet

[0047] 502 Discharge port; 503 Agitator

[0048] 504 Steam heating pipe; 505 Exhaust port

[0049] 506 Reagent dosing metering pump; 601 Fermentation broth outlet

[0050] 602 Solid Slag Export Detailed Implementation

[0051] The following example illustrates the implementation process of this invention by processing 1 ton of kitchen waste to produce anaerobic acid-producing fermentation liquid.

[0052] 1 ton of kitchen waste is unloaded from the unloading hopper and conveyed to the sorting and separating machine through the feeding screw from the outlet of the unloading hopper. The machine mainly removes larger impurities such as glass and plastic. After the larger impurities are removed, the kitchen waste is conveyed to the high-efficiency sand remover through the conveying pipeline to remove smaller impurities such as sand and gravel from the kitchen waste. After the crushing and sorting system, about 60-100 kg of impurities are removed. The food waste then enters a three-phase separator, where high temperature separates the grease from other substances, and the crude grease is discharged from the oil phase outlet, with a mass of approximately 50-80 kg. The solid and liquid phases are discharged from their respective outlets and collected in a homogenizing tank. The separated portion of the food waste is mixed and slurried in the homogenizing tank, and then transported through pipelines to the anaerobic digester. The slurry is fed into the digester through the inlet at the top of the digester, and the stirring device mixes the substances in the digester at a speed of 40-85 rpm. The food waste is fermented in the digester at 35°C and pH 6, with a hydraulic retention time of 7 days. During fermentation, due to the production of volatile fatty acids, a sodium hydroxide metering pump is installed above the digester to maintain the pH of the system, and sodium hydroxide is added quantitatively. At the same time, the carbon dioxide, hydrogen, methane, and other gases produced during fermentation are discharged and collected through the exhaust port of the anaerobic digester. The fermentation mixture is output from the fermentation liquid outlet pipe at the bottom of the fermenter to the centrifuge for processing. The centrifuge separates the fermentation slurry into solid residue and fermentation liquid. The solid residue is discharged and collected from the solid residue outlet, while the fermentation liquid is discharged directly from the fermentation liquid outlet. The fermentation liquid outlet is directly connected to the fermentation liquid conveying pipeline, so it is directly transported to the sewage treatment plant for use after being discharged from the fermentation liquid outlet.

[0053] The above description of the embodiments is intended to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a carbon source for wastewater treatment through anaerobic acid fermentation of kitchen waste, characterized in that, Includes the following steps: (1) After the kitchen waste is crushed and sorted to remove glass, plastic and other non-degradable components, it is transported to a three-phase separator. (2) After the kitchen waste enters the three-phase separator, the crude oil separated is transported and sold. The solid phase and aqueous phase are fed into the homogenizing tank, and after homogenization, they enter the anaerobic fermentation tank for fermentation. (3) After fermentation, the slurry is output from the anaerobic fermentation tank and enters the centrifuge. After centrifugation to remove solid residue, the fermentation liquid is transported to the sewage treatment plant through pipeline.

2. The method for preparing a carbon source for wastewater treatment through anaerobic acid fermentation of kitchen waste according to claim 1, characterized in that, The fermentation temperature of the anaerobic fermenter is 35℃.

3. The method for preparing a carbon source for wastewater treatment through anaerobic acid fermentation of kitchen waste according to claim 1, characterized in that, The hydraulic retention time of the anaerobic fermenter is 7 days.

4. The method for preparing a carbon source for wastewater treatment through anaerobic acid fermentation of kitchen waste according to claim 1, characterized in that, The anaerobic fermenter has a fermentation pH of 6.

5. The method for preparing a carbon source for wastewater treatment through anaerobic acid fermentation of kitchen waste according to claim 1, characterized in that, The separated non-degradable components account for approximately 5%-10% of the total processed volume.

6. A system for preparing a carbon source for wastewater treatment through anaerobic acid fermentation of kitchen waste, characterized in that, include: Unloading hopper (1), crushing and sorting system (2), three-phase separator (3), homogenizing tank (4), anaerobic fermentation tank (5), centrifuge (6), fermentation broth conveying pipeline (7) The crushing and sorting system (2) includes a feeding screw (201), a sorting separator (202), and a high-concentration sand remover (203); the sorting separator (202) and the high-concentration sand remover (203) are connected by a pipeline; the high-concentration sand remover (203) is connected to the three-phase separator (3) by a pipeline; The three-phase separator includes an oil phase outlet (301), a solid phase outlet (302), and an aqueous phase outlet (303); the solid phase outlet (302) and the aqueous phase outlet (303) of the three-phase separator (3) are connected to a homogenizing tank (4) via pipelines; the homogenizing tank (4) is connected to an anaerobic fermentation tank (5) via pipelines; The anaerobic fermenter (5) includes an inlet (501), an outlet (502), a stirrer (503), a steam heating pipe (504), an exhaust port (505), and a reagent dosing pump (506); the outlet (502) is connected to the centrifuge (6) via a pipe; the inlet (501) is located at the top of the anaerobic fermenter (5); the outlet (502) is located at the bottom of the anaerobic fermenter (5); the reagent dosing pump (506) is located on the other side of the inlet (501); the steam heating pipe (504) surrounds the outside of the anaerobic fermenter (5); the exhaust port (505) is located next to the reagent dosing pump (506). The centrifuge (6) includes a fermentation broth outlet (601) and a solid residue outlet (602); the fermentation broth outlet (601) is directly connected to the fermentation broth conveying pipeline (7).

7. The method for preparing a carbon source for wastewater treatment through anaerobic acid fermentation of kitchen waste according to claim 6, characterized in that, The actual volume of the anaerobic fermenter is 10% larger than the actual volume of the reaction mixture.

8. The method for preparing a carbon source for wastewater treatment through anaerobic acid fermentation of kitchen waste according to claim 6, characterized in that, The insulation layer of the anaerobic fermenter (5) is located on its exterior, and the insulation layer thickness is 0.075-0.1 meters; the insulation layer material is one or more of glass fiber insulation material, rock wool board, polyurethane foam, polystyrene board, and aluminum silicate fiber felt.

9. The method for preparing a carbon source for wastewater treatment through anaerobic acid fermentation of kitchen waste according to claim 6, characterized in that, The stirring speed of the agitator (503) in the anaerobic fermenter (5) is 40-85 rpm.

10. The method for preparing a carbon source for wastewater treatment through anaerobic acid fermentation of kitchen waste according to claim 6, characterized in that, The anaerobic fermenter (5) has a minimum surface diameter and height ratio of 1 for a given volume.

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