Method for harmless and resourceful treatment of kitchen waste

Abstract

This invention belongs to the technical field of harmless treatment and resource utilization of solid waste, specifically involving a method for the harmless treatment and resource utilization of kitchen waste, including the following steps: S1, sorting the kitchen waste, deodorizing it, and then performing solid-liquid separation to obtain solids and filtrate; S2, adjusting the pH of the filtrate obtained in S1 to 12-13, adding a demulsifier, allowing it to stand, recovering the upper layer of grease, and obtaining a lower layer of clarified liquid; the demulsifier is made of fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride, and polyaluminum chloride; drying and burning the solid obtained in S1 to obtain biochar; S3, subjecting the lower layer of clarified liquid obtained in S2 to advanced oxidation and biochemical treatment to obtain effluent. This invention can effectively reuse kitchen waste, alleviating the social and environmental problems caused by kitchen waste, and is suitable for widespread application.

Description

Technical Field

[0001] This invention belongs to the field of harmless treatment and resource utilization technology of solid waste, specifically relating to methods for harmless treatment and resource utilization of kitchen waste. Background Technology

[0002] Food waste varies across my country, but generally, due to my country's unique cooking methods, most food waste is characterized by high water content, high oil content, and easy decomposition. The high water content causes incineration of food waste, lowering furnace temperatures and leading to incomplete combustion and the formation of dioxins. Direct landfilling of food waste is detrimental to landfill stability and leachate treatment. Furthermore, byproducts of food waste, such as "garbage pigs" and "swill oil," pose significant health risks. Therefore, the treatment and disposal of food waste is increasingly attracting widespread public attention.

[0003] Oily wastewater from food waste contains grease with complex composition and forms, generally existing as suspended oil, dispersed oil, emulsified oil, dissolved oil, and oily solids. High-concentration emulsified grease is the most difficult to treat. While various oil-water separation technologies exist for food wastewater, each has its limitations, making it impossible to simultaneously reduce costs and improve treatment efficiency. How to achieve cost-effective and efficient oil-water separation from food waste is a major challenge facing the food waste treatment industry. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for the harmless and resource-based treatment of kitchen waste. It employs a demulsifier for effective demulsification, thereby improving the oil-water separation effect. The emulsifier raw materials are readily available and simple to prepare, thus reducing the cost of kitchen waste treatment.

[0005] The present invention is specifically implemented through the following technical solution.

[0006] The method for harmless and resource-based treatment of kitchen waste includes the following steps:

[0007] S1. The kitchen waste is sorted, deodorized, and then subjected to solid-liquid separation to obtain solids and filtrate.

[0008] S2. Adjust the pH of the filtrate obtained in S1 to 12-13, add a demulsifier, and heat to 40-60℃ with stirring to carry out the reaction. After the reaction is completed, let it stand, recover the upper oil layer, and use it as a raw material for biodiesel to obtain the lower clear liquid.

[0009] The demulsifier is made from the following components: fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride, and polyaluminum chloride, wherein the mass ratio of fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride, and polyaluminum chloride is 1:1:1:1-3:1-3.

[0010] The solid obtained from S1 was dried and burned to obtain biochar;

[0011] S3. The lower clarified liquid obtained in S2 is subjected to advanced oxidation treatment and biochemical treatment to obtain effluent.

[0012] In some embodiments of the present invention, in S2, the mass ratio of fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride, and polyaluminum chloride is 1:1:1:1-2:1-2, and the mass ratio of anhydrous calcium chloride to polyaluminum chloride is 1:1.

[0013] In some embodiments of the present invention, the demulsifier in S2 is used as follows: first, anhydrous calcium chloride and polyaluminum chloride are mixed to prepare mixture one, mixture one is added to the filtrate, the temperature is raised to 40-60°C and stirred, then mixture two, which is prepared by mixing fly ash, calcium oxide and magnesium oxide, is added, and the reaction is continued by stirring.

[0014] In some embodiments of the present invention, in step S2, after adding mixture one, the stirring time is 20-30 minutes, and after adding mixture two, the stirring continues for 30-60 minutes.

[0015] In some embodiments of the present invention, in S1, the sorted kitchen waste is added to a deodorizing agent for deodorization. The deodorizing agent is made from the following raw materials in parts by weight: 3-6 parts of 95% alcohol, 0.5-1 parts of orange peel, and 0.1-0.3 parts of bamboo leaves. The liquid obtained after soaking the orange peel and bamboo leaves in alcohol for 10-15 days is the deodorizing agent.

[0016] In some embodiments of the present invention, in S1, the amount of deodorant added is 0.5%-1% of the mass of the sorted kitchen waste.

[0017] In some embodiments of the present invention, in step S3, ferrous salt is added to the lower clarified liquid obtained in step S2, and the mixture is stirred. Then hydrogen peroxide is added and the mixture is stirred for 5-10 minutes. The wastewater is heated to 40-60°C and reacted for 2-4 hours. The supernatant is then discharged.

[0018] In some embodiments of the present invention, in step S3, the supernatant is introduced into the MBR reactor. The membrane module is a hollow fiber membrane with a pore size of 0.1-0.2 micrometers, a sludge concentration of 6-10 g / L, a hydraulic retention time of 5-8 h, a temperature of 20-30 °C, a pH of 7.5-8.5, and a dissolved oxygen of 0.1-0.3 mg / L.

[0019] In some embodiments of the present invention, the composite functional microbial community in the MBR reactor includes 15-35% aerobic ammonia oxidizing bacteria, 25-35% anaerobic ammonia oxidizing bacteria, 10-15% denitrifying bacteria, 5-15% sulfate-reducing bacteria, and 5-10% iron-reducing ammonia oxidizing bacteria.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. This invention first sorts and deodorizes kitchen waste, then performs solid-liquid separation. The solid is used to prepare biochar, and the liquid is separated into oil and water to obtain grease for use as biofuel. It should be noted that because kitchen waste in my country has a high oil content, especially when mixed with cleaning agents, it easily forms emulsified oil, which is difficult to handle using traditional oil-water separation methods. To address this problem, this invention adds a special demulsifier during oil-water separation. This demulsifier is prepared from fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride, and polyaluminum chloride. Among them, fly ash has a large specific surface area and strong adsorption capacity, which can play a role in charge neutralization and adsorption bridging, disrupting the stability of the system and absorbing water from the emulsified oil system. The reduction of water helps to demulsify the emulsified oil system. Calcium oxide and magnesium oxide help maintain the alkaline environment of the system and help dehydrate the system. Anhydrous calcium chloride and polyaluminum chloride work together to adsorb water while coagulating and settling, achieving the effect of demulsification. In practical application, anhydrous calcium chloride and polyaluminum chloride are first mixed and then added to the emulsified oil. After stirring to break the emulsion, fly ash, calcium oxide, and magnesium oxide are added for further demulsification. Through these two demulsification processes, the emulsified oil can be efficiently separated into oil and water. The separated water is then treated through advanced oxidation and biological processes to obtain effluent that meets standards and can be directly discharged.

[0022] 2. The processing technology of this invention is simple, and the raw materials of the demulsifier used are simple, which reduces the processing cost. It can effectively recycle food waste and alleviate the social and environmental problems caused by food waste. It is suitable for promotion and application. Detailed Implementation

[0023] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below with reference to specific embodiments and data, but the embodiments are not intended to limit the present invention.

[0024] Unless otherwise specified, the experimental and detection methods described in the following embodiments are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0025] The difficulty in treating food waste is largely due to its diverse and complex composition, particularly the presence of oil and water, which causes the waste to emulsify. Separating this emulsified grease from the water is crucial. This invention proposes a treatment method for high-concentration emulsified grease, the key being the use of a demulsifier. This demulsifier is composed of the following components: fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride, and polyaluminum chloride, with a mass ratio of 1:1:1:1-3:1-3. The method for harmless and resource-based treatment of food waste includes the following steps:

[0026] S1. The kitchen waste is sorted, deodorized, and then subjected to solid-liquid separation to obtain solids and filtrate.

[0027] S2. Adjust the pH of the filtrate obtained in S1 to 12-13, add a demulsifier, and heat to 40-60℃ with stirring to carry out the reaction. After the reaction is completed, let it stand, recover the upper oil layer, and use it as a raw material for biodiesel to obtain the lower clear liquid.

[0028] The demulsifier is made from the following components: fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride, and polyaluminum chloride, with a mass ratio of 1:1:1:1-3:1-3. Fly ash has a large specific surface area and strong adsorption capacity, which can play a role in charge neutralization and adsorption bridging, thereby destabilizing the system and absorbing moisture from the emulsified oil system. The reduction of moisture helps to demulsify the emulsified oil system. Calcium oxide and magnesium oxide help to maintain the alkaline environment of the system and help to dehydrate the system. Anhydrous calcium chloride and polyaluminum chloride work synergistically to adsorb moisture while coagulating and settling, thus achieving the effect of demulsification.

[0029] In practical use, the demulsifier of the present invention is first mixed with anhydrous calcium chloride and polyaluminum chloride, then added to the emulsified oil and stirred to demulsify. After stirring, fly ash, calcium oxide and magnesium oxide are added to further demulsify. Through the above two-step demulsification process, the emulsified oil can be separated into oil and water efficiently.

[0030] The solid obtained from S1 was dried and burned to obtain biochar;

[0031] S3. The lower clarified liquid obtained in S2 is subjected to advanced oxidation treatment and biological treatment to obtain effluent. The advanced oxidation treatment and biological treatment are carried out using existing technologies.

[0032] The present invention will be specifically described below through the following embodiments and comparative examples.

[0033] Example 1

[0034] A method for the harmless and resource-based treatment of kitchen waste, characterized by comprising the following steps:

[0035] S1. The kitchen waste is sorted and deodorized by adding a deodorizing agent. The deodorizing agent is made from the following raw materials in parts by weight: 5 parts of 95% alcohol, 1 part of orange peel, and 0.1 parts of bamboo leaves. The orange peel and bamboo leaves are soaked in alcohol for 15 days. The liquid obtained is the deodorizing agent. The amount of deodorizing agent added is 0.5% of the mass of the sorted kitchen waste. After deodorization, solid-liquid separation is performed to obtain solid and filtrate.

[0036] S2. Adjust the pH of the filtrate obtained in S1 to 12 and add a demulsifier. The demulsifier is used as follows: first, mix anhydrous calcium chloride and polyaluminum chloride to prepare mixture one. Add mixture one to the filtrate, heat to 40°C and stir for 20 minutes. Then add mixture two, which is prepared by mixing fly ash, calcium oxide and magnesium oxide, and continue stirring for 30 minutes. After the reaction is completed, let it stand, recover the upper oil layer and use it as a raw material for biodiesel to obtain the lower clear liquid.

[0037] The demulsifier is made from the following components: fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride, and polyaluminum chloride, wherein the mass ratio of fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride, and polyaluminum chloride is 1:1:1:1:1, and the mass ratio of anhydrous calcium chloride to polyaluminum chloride is 1:1.

[0038] The solid obtained from S1 was dried and burned to obtain biochar.

[0039] S3. Add ferrous salt to the lower clarified liquid obtained in S2, stir, then add hydrogen peroxide and continue stirring for 5 minutes; heat the wastewater to 40℃, react for 2 hours, and discharge the supernatant. Pass the supernatant into an MBR reactor. The membrane module is a hollow fiber membrane with a pore size of 0.1-0.2 micrometers, a sludge concentration of 6 g / L, a hydraulic retention time of 5 hours, a temperature of 20℃, a pH of 7.5, and a dissolved oxygen concentration of 0.1 mg / L. In the MBR reactor, the composite functional microbial community includes 35% aerobic ammonia oxidizing bacteria, 25% anaerobic ammonia oxidizing bacteria, 15% denitrifying bacteria, 15% sulfate-reducing bacteria, and 10% iron-reducing ammonia oxidizing bacteria. The treated water is then effluent.

[0040] Example 2

[0041] A method for the harmless and resource-based treatment of kitchen waste, characterized by comprising the following steps:

[0042] S1. The kitchen waste is sorted and deodorized by adding a deodorizing agent. The deodorizing agent is made from the following raw materials in parts by weight: 5 parts of 95% alcohol, 1 part of orange peel, and 0.1 parts of bamboo leaves. The orange peel and bamboo leaves are soaked in alcohol for 15 days. The liquid obtained is the deodorizing agent. The amount of deodorizing agent added is 1% of the mass of the sorted kitchen waste. After deodorization, solid-liquid separation is performed to obtain solid and filtrate.

[0043] S2. Adjust the pH of the filtrate obtained in S1 to 13 and add a demulsifier. The demulsifier is used as follows: first, mix anhydrous calcium chloride and polyaluminum chloride to prepare mixture one. Add mixture one to the filtrate, heat to 60°C and stir for 30 minutes. Then add mixture two, which is prepared by mixing fly ash, calcium oxide and magnesium oxide, and continue stirring for 60 minutes. After the reaction is completed, let it stand, recover the upper oil layer and use it as a raw material for biodiesel to obtain the lower clear liquid.

[0044] The demulsifier is made from the following components: fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride, and polyaluminum chloride, wherein the mass ratio of fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride, and polyaluminum chloride is 1:1:1:3:3, and the mass ratio of anhydrous calcium chloride to polyaluminum chloride is 1:1.

[0045] The solid obtained from S1 was dried and burned to obtain biochar.

[0046] S3. Add ferrous salt to the lower clarified liquid obtained in S2, stir, then add hydrogen peroxide and continue stirring for 10 minutes; heat the wastewater to 60℃, react for 4 hours, and discharge the supernatant. Pass the supernatant into an MBR reactor. The membrane module is a hollow fiber membrane with a pore size of 0.1-0.2 micrometers, a sludge concentration of 10 g / L, a hydraulic retention time of 8 hours, a temperature of 30℃, a pH of 8.5, and a dissolved oxygen of 0.3 mg / L. In the MBR reactor, the composite functional microbial community includes 35% aerobic ammonia oxidizing bacteria, 25% anaerobic ammonia oxidizing bacteria, 15% denitrifying bacteria, 15% sulfate-reducing bacteria, and 10% iron-reducing ammonia oxidizing bacteria. The treated water is then effluent.

[0047] Example 3

[0048] A method for the harmless and resource-based treatment of kitchen waste, characterized by comprising the following steps:

[0049] S1. The kitchen waste is sorted and deodorized by adding a deodorizing agent. The deodorizing agent is made from the following raw materials in parts by weight: 5 parts of 95% alcohol, 1 part of orange peel, and 0.1 parts of bamboo leaves. The orange peel and bamboo leaves are soaked in alcohol for 15 days. The resulting liquid is the deodorizing agent. The amount of deodorizing agent added is 0.6% of the mass of the sorted kitchen waste. After deodorization, solid-liquid separation is performed to obtain solid and filtrate.

[0050] S2. Adjust the pH of the filtrate obtained in S1 to 12 and add a demulsifier. The demulsifier is used as follows: first, mix anhydrous calcium chloride and polyaluminum chloride to prepare mixture one. Add mixture one to the filtrate, heat to 50°C and stir for 30 minutes. Then add mixture two, which is prepared by mixing fly ash, calcium oxide and magnesium oxide, and continue stirring for 30 minutes. After the reaction is completed, let it stand, recover the upper oil layer and use it as a raw material for biodiesel to obtain the lower clear liquid.

[0051] The demulsifier is made from the following components: fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride, and polyaluminum chloride, wherein the mass ratio of fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride, and polyaluminum chloride is 1:1:1:2:2.

[0052] The solid obtained from S1 was dried and burned to obtain biochar.

[0053] S3. Add ferrous salt to the lower clarified liquid obtained in S2, stir, then add hydrogen peroxide and continue stirring for 5-10 minutes; heat the wastewater to 50℃, react for 2 hours, and discharge the supernatant. Pass the supernatant into an MBR reactor. The membrane module is a hollow fiber membrane with a pore size of 0.1-0.2 micrometers, a sludge concentration of 8 g / L, a hydraulic retention time of 6 hours, a temperature of 25℃, a pH of 7.5, and a dissolved oxygen concentration of 0.2 mg / L. In the MBR reactor, the composite functional microbial community includes 35% aerobic ammonia oxidizing bacteria, 25% anaerobic ammonia oxidizing bacteria, 15% denitrifying bacteria, 15% sulfate-reducing bacteria, and 10% iron-reducing ammonia oxidizing bacteria. The treated water is then effluent.

[0054] Example 4

[0055] A method for the harmless and resource-based treatment of kitchen waste, characterized by comprising the following steps:

[0056] S1. The kitchen waste is sorted and deodorized by adding a deodorizing agent. The deodorizing agent is made from the following raw materials in parts by weight: 5 parts of 95% alcohol, 1 part of orange peel, and 0.1 parts of bamboo leaves. The orange peel and bamboo leaves are soaked in alcohol for 15 days. The liquid obtained is the deodorizing agent. The amount of deodorizing agent added is 1% of the mass of the sorted kitchen waste. After deodorization, solid-liquid separation is performed to obtain solid and filtrate.

[0057] S2. Adjust the pH of the filtrate obtained in S1 to 12 and add a demulsifier. The demulsifier is used as follows: first, mix anhydrous calcium chloride and polyaluminum chloride to prepare mixture one. Add mixture one to the filtrate, heat to 60°C and stir for 20 minutes. Then add mixture two, which is prepared by mixing fly ash, calcium oxide and magnesium oxide, and continue stirring for 60 minutes. After the reaction is completed, let it stand, recover the upper oil layer and use it as a raw material for biodiesel to obtain the lower clear liquid.

[0058] The demulsifier is made from the following components: fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride, and polyaluminum chloride, wherein the mass ratio of fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride, and polyaluminum chloride is 1:1:1:1:1.

[0059] The solid obtained from S1 was dried and burned to obtain biochar.

[0060] S3. Add ferrous salt to the lower clarified liquid obtained in S2, stir, then add hydrogen peroxide and continue stirring for 9 minutes; heat the wastewater to 60℃, react for 2 hours, and discharge the supernatant. Pass the supernatant into an MBR reactor. The membrane module is a hollow fiber membrane with a pore size of 0.1-0.2 micrometers, a sludge concentration of 10 g / L, a hydraulic retention time of 5 hours, a temperature of 30℃, a pH of 7.5, and a dissolved oxygen concentration of 0.3 mg / L. In the MBR reactor, the composite functional microbial community includes 35% aerobic ammonia oxidizing bacteria, 25% anaerobic ammonia oxidizing bacteria, 15% denitrifying bacteria, 15% sulfate-reducing bacteria, and 10% iron-reducing ammonia oxidizing bacteria. The treated water is then effluent.

[0061] Comparative Example 1

[0062] Compared to Example 1, no demulsifier is added, and the specific steps include:

[0063] S1. The kitchen waste is sorted and deodorized by adding a deodorizing agent. The deodorizing agent is made from the following raw materials in parts by weight: 5 parts of 95% alcohol, 1 part of orange peel, and 0.1 parts of bamboo leaves. The orange peel and bamboo leaves are soaked in alcohol for 15 days. The liquid obtained is the deodorizing agent. The amount of deodorizing agent added is 0.5% of the mass of the sorted kitchen waste. After deodorization, solid-liquid separation is performed to obtain solid and filtrate.

[0064] S2. Adjust the filtrate obtained from S1 and let it stand. Recover the upper layer of oil and use it as a raw material for biodiesel to obtain the lower layer liquid.

[0065] The solid obtained from S1 was dried and burned to obtain biochar.

[0066] S3. Add ferrous salt to the lower layer obtained in S2, stir, then add hydrogen peroxide and continue stirring for 5 minutes; heat the wastewater to 40℃, react for 2 hours, and discharge the supernatant. Pass the supernatant into an MBR reactor. The membrane module is a hollow fiber membrane with a pore size of 0.1-0.2 micrometers, a sludge concentration of 6 g / L, a hydraulic retention time of 5 hours, a temperature of 20℃, a pH of 7.5, and a dissolved oxygen concentration of 0.1 mg / L. In the MBR reactor, the composite functional microbial community includes 35% aerobic ammonia oxidizing bacteria, 25% anaerobic ammonia oxidizing bacteria, 15% denitrifying bacteria, 15% sulfate-reducing bacteria, and 10% iron-reducing ammonia oxidizing bacteria. The treated wastewater is then obtained.

[0067] Comparative Example 2

[0068] Compared to Example 1, the demulsifier does not contain anhydrous calcium chloride or polyaluminum chloride, and specifically includes the following steps:

[0069] S1. The kitchen waste is sorted and deodorized by adding a deodorizing agent. The deodorizing agent is made from the following raw materials in parts by weight: 5 parts of 95% alcohol, 1 part of orange peel, and 0.1 parts of bamboo leaves. The orange peel and bamboo leaves are soaked in alcohol for 15 days. The liquid obtained is the deodorizing agent. The amount of deodorizing agent added is 0.5% of the mass of the sorted kitchen waste. After deodorization, solid-liquid separation is performed to obtain solid and filtrate.

[0070] S2. Adjust the pH of the filtrate obtained in S1 to 12 and add a demulsifier. The demulsifier is used as follows: add it to a mixture of fly ash, calcium oxide and magnesium oxide, stir for 30 minutes, let it stand after the reaction is complete, recover the upper oil layer and use it as a raw material for biodiesel to obtain the lower liquid layer.

[0071] The demulsifier is made from the following components: fly ash, calcium oxide, and magnesium oxide, with a mass ratio of fly ash, calcium oxide, and magnesium oxide of 1:1:1.

[0072] The solid obtained from S1 was dried and burned to obtain biochar.

[0073] S3. Add ferrous salt to the lower layer obtained in S2, stir, then add hydrogen peroxide and continue stirring for 5 minutes; heat the wastewater to 40℃, react for 2 hours, and discharge the supernatant. Pass the supernatant into an MBR reactor. The membrane module is a hollow fiber membrane with a pore size of 0.1-0.2 micrometers, a sludge concentration of 6 g / L, a hydraulic retention time of 5 hours, a temperature of 20℃, a pH of 7.5, and a dissolved oxygen concentration of 0.1 mg / L. In the MBR reactor, the composite functional microbial community includes 35% aerobic ammonia oxidizing bacteria, 25% anaerobic ammonia oxidizing bacteria, 15% denitrifying bacteria, 15% sulfate-reducing bacteria, and 10% iron-reducing ammonia oxidizing bacteria. The treated wastewater is then obtained.

[0074] Comparative Example 3

[0075] Compared to Example 1, the demulsifier does not contain fly ash, calcium oxide, or magnesium oxide, and specifically includes the following steps:

[0076] S1. The kitchen waste is sorted and deodorized by adding a deodorizing agent. The deodorizing agent is made from the following raw materials in parts by weight: 5 parts of 95% alcohol, 1 part of orange peel, and 0.1 parts of bamboo leaves. The orange peel and bamboo leaves are soaked in alcohol for 15 days. The liquid obtained is the deodorizing agent. The amount of deodorizing agent added is 0.5% of the mass of the sorted kitchen waste. After deodorization, solid-liquid separation is performed to obtain solid and filtrate.

[0077] S2. Adjust the pH of the filtrate obtained in S1 to 12 and add a demulsifier. The demulsifier is used as follows: first, mix anhydrous calcium chloride and polyaluminum chloride to prepare mixture one. Add mixture one to the filtrate, heat to 40°C and stir for 20 minutes. After the reaction is complete, let it stand, recover the upper oil layer and use it as a raw material for biodiesel to obtain the lower clear liquid.

[0078] The mass ratio of anhydrous calcium chloride to polyaluminum chloride is 1:1;

[0079] The solid obtained from S1 was dried and burned to obtain biochar.

[0080] S3. Add ferrous salt to the lower clarified liquid obtained in S2, stir, then add hydrogen peroxide and continue stirring for 5 minutes; heat the wastewater to 40℃, react for 2 hours, and discharge the supernatant. Pass the supernatant into an MBR reactor. The membrane module is a hollow fiber membrane with a pore size of 0.1-0.2 micrometers, a sludge concentration of 6 g / L, a hydraulic retention time of 5 hours, a temperature of 20℃, a pH of 7.5, and a dissolved oxygen concentration of 0.1 mg / L. In the MBR reactor, the composite functional microbial community includes 35% aerobic ammonia oxidizing bacteria, 25% anaerobic ammonia oxidizing bacteria, 15% denitrifying bacteria, 15% sulfate-reducing bacteria, and 10% iron-reducing ammonia oxidizing bacteria. The treated water is then effluent.

[0081] The performance of the above embodiments and comparative examples is then tested.

[0082] (1) Oil-water separation effect in the examples and comparative examples: 100 mL of the oil-water mixture system in Examples 1-4 and Comparative Examples 1-3 was taken and allowed to stand. The separation of the oil phase and water phase after standing was observed. The results are shown in Table 1:

[0083] Table 1. Separation of oil and aqueous phases after S2 was allowed to stand in Examples 1-4 and Comparative Examples 1-3.

[0084]

[0085]

[0086] As shown in Table 1, the dehydration amount of Examples 1-4 of the present invention is higher than that of Comparative Examples 1-3. Comparative Example 1, without the addition of a demulsifier, has a poor final oil-water separation effect, the smallest dehydration amount, an unclear oil-water interface, and an unclear aqueous phase. This indicates that simply using ordinary settling treatment cannot ultimately yield a high-quality oil and aqueous phase, fully demonstrating the significant difficulty in treating kitchen waste in this invention. Although a demulsifier was added in Comparative Example 2, anhydrous calcium chloride and polyaluminum chloride were not added. The oil-water separation effect was improved compared to Comparative Example 1, but still not as good as Examples 1-4. This indicates that anhydrous calcium chloride and polyaluminum chloride are effective for demulsification in this invention and are essential components. Comparative Example 3, without the addition of fly ash, calcium oxide, and magnesium oxide, also has a better oil-water separation effect than Comparative Example 1, but still worse than Examples 1-4. This also indicates that fly ash, calcium oxide, and magnesium oxide are effective for demulsification.

[0087] (2) The components of the S3 treated effluent in Examples 1-4 and Comparative Examples 1-3 were analyzed, and the results are shown in Table 2.

[0088] Table 2. Effluent composition of Examples 1-4 and Comparative Examples 1-3

[0089]

[0090]

[0091] As shown in Table 2, the oil content in the effluent treated by Examples 1-4 was relatively low, while the oil content in Comparative Examples 1-3 was relatively high. This is consistent with the results in Table 1, indicating that the demulsifier used in the demulsification process is very effective. Correspondingly, the COD content in Examples 1-4 was also low, meeting the discharge requirements and allowing for direct discharge.

[0092] This invention not only effectively separates oil and water when treating kitchen waste, but also allows the separated oil to be used as a raw material for biodiesel, and the solid to be prepared into biochar, turning waste into treasure and realizing the resource utilization of kitchen waste. Furthermore, the water at the treatment site is treated to meet the discharge standards, achieving the harmless treatment of kitchen waste, which is economical and environmentally friendly.

[0093] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, it is intended to include any modifications and variations that fall within the scope of the claims and their equivalents.

Claims

1. A method for the harmless and resource-based treatment of kitchen waste, characterized in that, Includes the following steps: S1. The kitchen waste is sorted, deodorized, and then subjected to solid-liquid separation to obtain solids and filtrate. S2. Adjust the pH of the filtrate obtained in S1 to 12-13, add demulsifier, and heat to 40-60℃ with stirring to carry out the reaction. After the reaction is completed, let it stand and separate the upper oil and the lower clear liquid. The demulsifier is made from the following components: fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride and polyaluminum chloride, and the mass ratio of fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride and polyaluminum chloride is 1:1:1:1-3:1-3; The method of using the demulsifier is as follows: first, mix anhydrous calcium chloride and polyaluminum chloride to prepare mixture one, add mixture one to the filtrate, heat to 40-60℃ and stir, then add mixture two prepared by mixing fly ash, calcium oxide and magnesium oxide, and continue stirring to react; The solid obtained from S1 was dried and burned to obtain biochar; S3. The lower clarified liquid obtained in S2 is subjected to advanced oxidation and biochemical treatment to obtain effluent.

2. The method according to claim 1, wherein the method further comprises the steps of: In S2, the mass ratio of fly ash, calcium oxide, magnesium oxide, anhydrous calcium chloride, and polyaluminum chloride is 1:1:1:1-2:1-2, and the mass ratio of anhydrous calcium chloride to polyaluminum chloride is 1:

1. ​ 3. The method according to claim 2, wherein the method further comprises the steps of: adding a certain amount of water to the kitchen waste; and mixing the kitchen waste and the water. In S2, after adding mixture one, stir for 20-30 minutes. After adding mixture two, continue stirring for 30-60 minutes.

4. The method according to claim 1, wherein the method further comprises the steps of: adding a certain amount of water to the kitchen waste; and mixing the kitchen waste and the water. In step S1, the sorted kitchen waste is added to a deodorizing agent for deodorization. The deodorizing agent is made from the following raw materials in parts by weight: 3-6 parts of 95% alcohol, 0.5-1 parts of orange peel, and 0.1-0.3 parts of bamboo leaves. The liquid obtained after soaking the orange peel and bamboo leaves in alcohol for 10-15 days is the deodorizing agent.

5. The method according to claim 4, wherein the method further comprises the step of: In S1, the amount of deodorant added is 0.5%-1% of the mass of the sorted kitchen waste. ​ 6. The method according to claim 1, wherein the method further comprises the steps of: adding a certain amount of water to the kitchen waste; and mixing the kitchen waste and the water. In S3, ferrous salt is added to the lower clarified liquid obtained in S2, and the mixture is stirred. Then hydrogen peroxide is added, and the mixture is stirred for 5-10 minutes. The wastewater is heated to 40-60℃ and reacted for 2-4 hours. The supernatant is then discharged.

7. The method according to claim 6, wherein the method further comprises the step of: In step S3, the supernatant is introduced into the MBR reactor. The membrane module is a hollow fiber membrane with a pore size of 0.1-0.2 micrometers, a sludge concentration of 6-10 g / L, a hydraulic retention time of 5-8 h, a temperature of 20-30℃, a pH of 7.5-8.5, and a dissolved oxygen of 0.1-0.3 mg / L. ​ 8. The method according to claim 7, wherein the method further comprises the step of: In the MBR reactor, the complex functional microbial community consists of the following percentages by mass: aerobic ammonia oxidizing bacteria 15-35%, anaerobic ammonia oxidizing bacteria 25-35%, denitrifying bacteria 10-15%, sulfate-reducing bacteria 5-15%, and iron-reducing ammonia oxidizing bacteria 5-10%. ​

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