Kitchen garbage treatment method

Abstract

The invention discloses a kitchen waste treatment method which comprises the following steps: primarily crushing and screening incoming kitchen waste, and intelligently sorting oversize products as coarse impurities to obtain recyclable impurities; pulping and screening the undersize product to obtain slurry, and intelligently sorting the oversize product as fine impurities and coarse impurities together; precipitating the slurry, and outwards transporting the precipitate; extruding the slurry to separate out slag and slurry; heating and cooking the slurry, and performing three-phase centrifugal separation to obtain solid-phase fine slag, wastewater and grease; the slag materials and the solid-phase fine slag are dried in a variable-pressure type complex-source drying box, and dried discharged materials are obtained; wastewater is collected into a waste liquid pool, part of waste liquid is returned to the pulping and sand setting step to dilute the slurry, and other waste liquid is subjected to sewage treatment. According to the method, part of nonbiodegradable impurities can be recycled, so that the recycling degree is improved; the material treatment time and the reaction occupied area can be reduced; organic slag can be directly dried, and various problems of anaerobic digestion treatment are avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of kitchen waste treatment, and particularly relates to a kitchen waste treatment method. Background Art

[0002] Kitchen waste refers to perishable organic waste such as fruits and vegetables, food scraps, leftovers, etc. generated in daily food processing, restaurant kitchen services, and corporate catering activities. my country's kitchen waste has complex components, high water content, and rich organic matter. It is easy to corrupt and breed bacteria and flies, which is harmful to the environment.

[0003] At present, the mainstream processing procedures for the front-end pretreatment of kitchen waste are relatively similar, mainly including coarse sorting, pulping sorting, sand settling, filter pressing dehydration, three-phase separation, etc. After the front-end pretreatment, the difficult-to-biodegrade impurities screened out are usually directly transported out for incineration, and the mainstream treatment method for the screened organic residue is anaerobic digestion.

[0004] Anaerobic digestion is the process of using a variety of microorganisms to decompose large molecular complex organic matter in waste into small molecular simple organic matter and inorganic substances under anaerobic conditions, and finally obtain biogas products. However, the current anaerobic digestion of kitchen waste still faces many problems: 1. The residence time of anaerobic digestion is usually not less than 30 days / batch, the processing time is long, and the required reactor volume is large (taking 50t / d processing capacity as an example, the required volume is at least 1500m 3 reactor); 2. The main component of biogas, the final product of anaerobic digestion, is CH4, but its proportion is only 40-70%. Biogas also contains a large amount of impurity gases such as H2S and CO2, which results in the biogas produced by anaerobic digestion cannot be directly used. It is necessary to configure additional physical, chemical or biological treatment facilities to purify the biogas, which increases the disposal cost; 3. Since most of the current mainstream anaerobic digestion reactors use wet digestion (feed solid content TS < 15%), in actual production, some of the residues produced by the front-end pretreatment cannot enter the anaerobic reactor; the byproducts of anaerobic digestion, biogas residues and biogas liquid, still contain a large amount of organic matter and nutrients. If not properly handled, they will cause secondary pollution to the environment. How to properly handle residues, biogas residues, and biogas liquid is a problem that needs to be solved urgently. Summary of the invention

[0005] Technical problems to be solved: In response to the above technical problems, the present invention provides a method for treating kitchen waste, which can recycle some impurities that are difficult to biodegrade and improve the degree of resource utilization; it can reduce material processing time and reaction area; it can directly dry organic residues and avoid various problems in anaerobic digestion treatment.

[0006] Technical solution: A method for treating kitchen waste, comprising the following steps: Step 1. Rough sorting: Preliminary crushing and screening of the incoming kitchen waste, and intelligent sorting of the sieved materials as coarse debris to obtain recyclable debris; Step 2. Pulping and screening: pulping and screening the undersize in step 1 to obtain slurry, and intelligently sorting the oversize as fine debris together with the coarse debris in step 1; Step 3. Sand settling: the slurry obtained in step 2 is precipitated and the precipitate is transported out; Step 4. Filter pressing and dehydration: the slurry after precipitation in step 3 is squeezed to separate the slag and the slurry; Step 5. Three-phase separation: The slurry in step 4 is heated and steamed and then subjected to three-phase centrifugation to separate solid phase fine residue, wastewater and grease; Step 6. Drying: drying the slag material in step 4 and the solid fine slag in step 5 in a transformer-type re-source drying box to obtain dried material; Step 7. Wastewater treatment: The wastewater in step 5 is collected into the waste liquid pool, part of the waste liquid in the waste liquid pool is returned to the pulping screening and sand settling steps to dilute the slurry, and the other waste liquid is treated with sewage.

[0007] Preferably, the screening particle size of the coarse debris in step 1 is not less than 55 mm.

[0008] Preferably, the intelligent sorting in step 1 is performed by an industrial robot equipped with AI vision, and the AI ​​vision collects materials, expands learning, and adds new target sorting objects according to sorting requirements.

[0009] Preferably, the screening particle size of the fine debris in step 2 is not less than 10 mm.

[0010] Preferably, the moisture content of the slag in step 4 is 60% to 80%.

[0011] Preferably, the cooking temperature in step 5 is 70°C.

[0012] Preferably, the drying process in step 6 is as follows: Step 6.1: Use microwave preheating alone, and select normal pressure ventilation for the air pressure environment until the material temperature reaches the highest temperature of the first stage and then maintain it for a specified time; Step 6.2 Turn off the microwave, turn on the oil temperature machine to continue heating, select closed pressurization for the air pressure environment, continue to increase the temperature to the highest temperature of the second stage, maintain it for a specified time, and then release the pressure; Step 6.3: After the pressure relief is completed, the air pressure environment is set to negative pressure ventilation, and low-temperature drying is performed until the drying is completed and the material is discharged.

[0013] Preferably, the heat source of the variable pressure regeneration drying box in step 6 includes: a microwave heat source and an oil temperature heat source, and the variable pressure environment includes: normal pressure ventilation, pressurized sealing and negative pressure ventilation.

[0014] Preferably, the dried material in step 6 is used as raw material or auxiliary material for fertilizer or feed production and processing.

[0015] Preferably, the water vapor generated by drying in step 6 is condensed into condensed water and then collected into a waste liquid pool.

[0016] Furthermore, in step 7, the mixing ratio of the condensed water and the waste liquid introduced into the waste liquid pool is 1:1.

[0017] Beneficial effects: The above technical solution adopted by the present invention has the following significant effects: 1. Use industrial robots equipped with AI vision for intelligent sorting to sort and collect recyclables from the debris screened out by the front-end processing. Compared with direct incineration, the degree of resource utilization is higher; 2. The total processing time is about 12~15h, which greatly shortens the material residence time compared with the mainstream anaerobic digestion process; 3. The shortening of material residence time reduces the demand for reaction space and saves floor space; 4. All organic residues produced by the front-end treatment are dried at high temperature to produce the final product, without any residue or biogas residue remaining, and no additional purification and collection facilities are required at the back end of the product; 5. Variable-pressure regeneration drying has the advantages of fast heating, small heat loss, and high degree of harmlessness. The final product is non-toxic and harmless, with complete reduction and certain economic value; 6. Dilute and adjust part of the waste liquid to effectively reduce the adhesion and hardening problems that may occur at the feed end of the equipment and reduce equipment loss; 7. The condensed water is mixed with the waste liquid and then discharged for treatment. Compared with the anaerobic digestion of biogas slurry, the treatment is less difficult. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. Example 1

[0020] like Figure 1 As shown, a method for treating kitchen waste comprises the following steps: Step 1. Rough sorting: The kitchen waste is initially crushed and screened, and the particles above the screen with a particle size of ≥55 mm are regarded as coarse debris. The coarse debris is transported to an industrial robot equipped with AI vision through a screw conveyor for intelligent sorting to obtain recyclable debris; In some embodiments, coarse impurities with a particle size of ≥80 mm are screened out; In some embodiments, coarse impurities with a particle size of ≥60 mm are screened out; In some embodiments, coarse impurities with a particle size of ≥50 mm are screened out.

[0021] Step 2. Pulping and screening: The undersize in step 1 is pulped and screened to obtain slurry, and the oversize with a particle size of ≥10 mm is regarded as fine debris. The fine debris is conveyed to an industrial robot equipped with AI vision through a gate screw, and is intelligently sorted together with the coarse debris in step 1; In some embodiments, fine debris with a size of ≥8 mm is screened out; In some embodiments, fine debris with a size of ≥6 mm is screened out.

[0022] Among them, the industrial robot equipped with AI vision sorts and collects recyclable debris with certain economic value, and the sorting targets include plastic bottles, plastic bags, milk cartons, etc. Intelligent sorting meets different sorting needs by replacing different sorting terminal equipment. According to the sorting needs, AI vision expands learning by collecting materials and adds new target sorting objects; in the case of incorrect or unsuccessful recognition of a certain type or category of debris, targeted AI deep learning should be carried out on the type or category of debris to improve the recognition success rate. The recognition success rate of a certain type or category of debris should reach 95% or above; In some embodiments, the sorting target is metal debris; In some embodiments, the recognition success rate should reach 99% or above.

[0023] Step 3. Sand settling: The slurry obtained in step 2 is precipitated by gravity to separate larger substances, such as broken bones, shells, glass, ceramics and other sediments. The sediments are slowly transported by the bottom conveyor to the external transport hinge for external transport.

[0024] Step 4. Filter pressing and dehydration: The slurry after precipitation in step 3 is conveyed to a double-shaft screw filter pressing and dehydration machine for extrusion to separate the slag with a moisture content of about 75% and the removed slurry; In some embodiments, the slurry is dewatered using a centrifugal dewatering machine; In some embodiments, slag having a moisture content of about 60% is separated; In some embodiments, slag having a moisture content of about 70% is separated.

[0025] Step 5. Three-phase separation: The slurry in step 4 is pumped into a cooking tank for heating and cooking to a temperature of 70°C to meet the requirements for three-phase separation, and then pumped into a horizontal three-phase centrifuge to separate solid phase fine slag, liquid phase wastewater and oil phase; In some embodiments, the cooking temperature reaches about 65°C; In some embodiments, the cooking temperature reaches about 80°C; In some embodiments, the cooking temperature reaches about 95°C; In some embodiments, a horizontal three-phase separator is used to separate the solid fine residue and the oil-water mixture, and then a vertical three-phase separator is used to separate the oil and water; In some embodiments, a vertical disc separator is used to separate the solid phase fine slag, the liquid phase wastewater and the grease phase.

[0026] Step 6. Drying: Dry the slag in step 4 and the solid fine slag in step 5 in a transformer-type regeneration drying box to obtain dried material; during the material heating process, select different heat sources (microwave preheating, oil temperature continuous heating) and different air pressure environments (normal pressure ventilation, closed pressurization, negative pressure ventilation) according to different heating periods. The dried material can be used as raw materials or auxiliary materials for fertilizer and feed production and processing; during drying, the negative pressure pump draws water vapor to the condensation pipeline, and the condensed water flows into the waste liquid pool. The specific drying process is as follows: 1) First, use microwave to preheat alone, and select normal pressure ventilation for the air pressure environment until the material temperature rises to about 90°C and maintains for about 0.5h; 2) Turn off the microwave, turn on the oil temperature machine for heating, select closed pressurization for the air pressure environment, raise the temperature to about 140°C, and maintain the air pressure at 0.3 MPa for 0.5 h, then release the pressure; 3) After the pressure relief is completed, the air pressure environment is selected for negative pressure ventilation, and low-temperature drying is carried out for 3 to 8 hours. The moisture content of the material is reduced to ≤15%. After the drying is completed, the material is discharged.

[0027] In some embodiments, the microwave and the oil temperature machine are turned on for heating at the same time, the air pressure environment is selected to be ventilated at normal pressure, and the microwave is turned off when the temperature rises to 120°C. When the oil temperature machine is used for heating, the air pressure environment is selected to be closed and pressurized, the temperature is raised to about 160°C, maintained for 1 to 2 hours, and then the pressure is released. After the pressure release is completed, switch to a negative pressure ventilation environment until the drying is completed; In some embodiments, microwave heating is first turned on, the air pressure environment is selected to be ventilated at normal pressure, and the microwave is turned off when the temperature rises to about 100°C. When an oil temperature machine is used for heating, the air pressure environment is selected to be closed and pressurized, the temperature is raised to about 170°C, and the pressure is released after maintaining for 1 to 3 hours. After the pressure release is completed, the negative pressure ventilation environment is switched until the drying is completed.

[0028] Step 7. Wastewater treatment: The wastewater in step 5 and the condensed water in step 6 are collected into the wastewater pool, part of the wastewater in the wastewater pool is returned to the pulping screening and sand settling steps to dilute the slurry, and the rest of the wastewater is pumped into the subsequent sewage treatment system for sewage treatment. Among them, the proportion of condensed water used for return is 50% of the total condensed water, and the mixing ratio of condensed water to wastewater is 1:1.

[0029] In some embodiments, the proportion of condensed water produced is 30%; In some embodiments, the output from step 2 is diluted; In some embodiments, both the input and output materials of step 2 are diluted.

[0030] It should be understood that the specific embodiments described above are only used to illustrate and explain the present invention, and are not used to limit the present invention.

Claims

1. A method for treating kitchen waste, characterized in that: The steps include: Step 1. Rough sorting: Preliminary crushing and screening of the incoming kitchen waste, and intelligent sorting of the sieved materials as coarse debris to obtain recyclable debris; Step 2. Pulping and screening: pulping and screening the undersize in step 1 to obtain slurry, and intelligently sorting the oversize as fine debris together with the coarse debris in step 1; Step 3. Sand settling: the slurry obtained in step 2 is precipitated and the precipitate is transported out; Step 4. Filter pressing and dehydration: the slurry after precipitation in step 3 is squeezed to separate the slag and the slurry; Step 5. Three-phase separation: The slurry in step 4 is heated and steamed and then subjected to three-phase centrifugation to separate solid phase fine residue, wastewater and grease; Step 6. Drying: drying the slag material in step 4 and the solid fine slag in step 5 in a transformer-type re-source drying box to obtain dried material; Step 7. Wastewater treatment: The wastewater in step 5 is collected into the waste liquid pool, part of the waste liquid in the waste liquid pool is returned to the pulping screening and sand settling steps to dilute the slurry, and the other waste liquid is treated with sewage.

2. A method for treating kitchen waste according to claim 1, characterized in that: The screening particle size of the coarse debris in step 1 is not less than 55 mm.

3. A method for treating kitchen waste according to claim 1, characterized in that: In step 1, intelligent sorting is performed by an industrial robot equipped with AI vision, and the AI ​​vision collects materials, expands learning, and adds new target sorting objects according to sorting requirements.

4. A method for treating kitchen waste according to claim 1, characterized in that: The screening particle size of the fine debris in step 2 is not less than 10 mm.

5. A method for treating kitchen waste according to claim 1, characterized in that: The moisture content of the slag in step 4 is 60% to 80%.

6. A method for treating kitchen waste according to claim 1, characterized in that: The cooking temperature in step 5 is 70°C.

7. A method for treating kitchen waste according to claim 1, characterized in that: The drying process in step 6 is as follows: Step 6.1: Use microwave preheating alone, and select normal pressure ventilation for the air pressure environment until the material temperature reaches the highest temperature of the first stage and then maintain it for a specified time; Step 6.2 Turn off the microwave, turn on the oil temperature machine to continue heating, select closed pressurization for the air pressure environment, continue to increase the temperature to the highest temperature of the second stage, maintain it for a specified time, and then release the pressure; Step 6.3: After the pressure relief is completed, the air pressure environment is set to negative pressure ventilation, and low-temperature drying is performed until the drying is completed and the material is discharged.

8. The method for treating kitchen waste according to claim 1, characterized in that: The dried material in step 6 is used as raw material or auxiliary material for fertilizer or feed production and processing.

9. A method for treating kitchen waste according to claim 1, characterized in that: The water vapor generated by the drying in step 6 is condensed into condensed water and then flows into the waste liquid pool.

10. A method for treating kitchen waste according to claim 9, characterized in that: The mixing ratio of the condensed water and the waste liquid introduced into the waste liquid pool in step 7 is 1:1.

Images