A multi-source organic solid waste collaborative treatment system and process

Abstract

The present invention relates to the technical field of resource utilization of domestic waste and kitchen waste, and discloses a multi-source organic solid waste collaborative treatment system and process, which includes a kitchen waste pretreatment unit, a food waste pretreatment unit, a mixing unit, and a dry anaerobic fermentation unit. The discharge ends of the kitchen waste pretreatment unit and the food waste pretreatment unit are communicated with the feed end of the mixing unit, and the discharge end of the mixing unit is communicated with the feed end of the dry anaerobic fermentation unit. The mixing unit is provided with an anti-winding mixer. In this solution, after the kitchen waste small coarse residue and kitchen sludge obtained from the treatment of kitchen waste and the food waste organic matter obtained from the treatment of food waste are mixed according to the mass ratio in this solution, the acid-base, pH, ammonia nitrogen, microorganisms, etc. of the three raw materials in the tank affect each other and complement each other, effectively complementing and utilizing the organic matter and microorganisms of the three, improving the treatment efficiency among them, changing the traditional way of external treatment, and effectively reducing the external treatment cost.

Description

Technical Field

[0001] The present invention relates to the technical field of resource utilization of domestic waste and food waste, and specifically relates to a multi-source organic solid waste collaborative treatment system and process. Background Art

[0002] Food waste and kitchen waste have a high solid content rate and a high organic matter content, and generally anaerobic fermentation treatment is adopted. Anaerobic fermentation, as a technology for treating organic waste and converting it into bioenergy, is complex in that it is restricted by various factors including raw material components, particle size, pH value, and ammonia nitrogen level, and these factors are directly related to fermentation efficiency and gas production capacity. In actual operation, due to the complex composition of food waste and kitchen waste, anaerobic fermentation will face problems such as stratification, acidification, uneven heating, and reduced fermentation efficiency, seriously affecting the stability and economy of the anaerobic fermentation system.

[0003] At present, anaerobic fermentation technologies are divided into two major categories: wet and dry. The wet anaerobic fermentation technology is relatively mature, but its application scope is severely restricted due to the requirement of "low solid content rate materials". In contrast, dry anaerobic fermentation has more advantages because it can treat high solid content waste (25% - 45%), has a smaller floor area, lower energy consumption, and less biogas slurry output.

[0004] The prior art CN214937410U discloses a mixed dry anaerobic fermentation treatment system for food waste and kitchen waste, which can treat food waste and kitchen waste simultaneously, reduce the production of biogas slurry, correspondingly reduce the later biogas slurry treatment cost, and reduce the economic cost. However, the prior art still has the following technical problems when mixing and treating food waste and kitchen waste: (1) In the existing mixed anaerobic fermentation, the effect of mixed anaerobic fermentation of materials is often poor due to difficult material preparation (such as inappropriate ratios), and the utilization efficiency of organic matter in food waste and kitchen waste is low; (2) When the existing dry anaerobic fermentation system treats the collaborative anaerobic fermentation of multiple organic solid wastes, it is easy to form a high load due to uneven mixing of materials and high impurity gas content, resulting in "system instability" and phenomena such as gas production inhibition and even system collapse; (3) In the existing mixed dry anaerobic fermentation, even if the raw materials are crushed into small particle sizes, there are still long cloth strips, plastics, fibers, etc. in the kitchen waste, which entangle with each other during the mixing process to form long strip-shaped objects again and entangle the equipment, resulting in increased equipment damage and increased equipment maintenance costs; (4) After the strip-shaped objects in the existing waste entangle the equipment, it is necessary to stop work for cleaning, reducing the operation stability and continuity of the system equipment, and thus resulting in low treatment efficiency.

[0005] In summary, developing a multi-source organic solid waste collaborative treatment system and process with high efficiency and good results not only effectively makes up for the deficiencies of the existing technology, but also can simultaneously treat various organic solid wastes, improve the treatment efficiency, reduce the equipment cost of the production line, and is of great significance for the efficient treatment of organic solid wastes. Summary of the Invention

[0006] The present invention aims to provide a multi-source organic solid waste collaborative treatment system and process to solve the technical problems that in the existing mixed anaerobic fermentation, the effect of mixed anaerobic fermentation of materials is often poor due to inappropriate material mixing ratios, resulting in low utilization efficiency of organic matter in food waste and kitchen waste.

[0007] To achieve the above object, the present invention adopts the following technical solution: A multi-source organic solid waste collaborative treatment system includes a food waste pretreatment unit, a kitchen waste pretreatment unit, a mixing unit, and a dry anaerobic fermentation unit. The discharge ends of the food waste pretreatment unit and the kitchen waste pretreatment unit are connected to the feed end of the mixing unit, and the discharge end of the mixing unit is connected to the feed end of the dry anaerobic fermentation unit. The mixing unit is provided with an anti-winding mixer.

[0008] The principle and advantages of this solution are as follows:

[0009] 1. Reduce treatment costs: Since the solid content, organic matter content, oil content, and heavy substance content of kitchen waste organic matter, food waste small coarse residue, and food waste sludge vary greatly. Therefore, different mixing ratios have a greater impact on the load impact and stable operation of the dry anaerobic digestion system. Compared with the existing mixed anaerobic fermentation, in which the effect of mixed anaerobic fermentation of materials is often poor due to inappropriate material mixing ratios, ultimately resulting in low utilization efficiency of organic matter in food waste and kitchen waste, in this solution, after mixing the food waste small coarse residue, food waste sludge obtained from food waste treatment and kitchen waste organic matter obtained from kitchen waste treatment according to the mass ratio in this solution, the acid-base, PH, ammonia nitrogen, microorganisms, etc. of the three raw materials in the tank affect each other and complement each other, effectively complementing and utilizing the organic matter and microorganisms of the three, improving the treatment efficiency between them, and improving the effect of mixed anaerobic fermentation. It not only effectively improves the utilization efficiency of organic matter in food waste and kitchen waste, but also changes the traditional way of external treatment, effectively reducing the external treatment cost.

[0010] 2. Improve the energy recovery rate from organic solid waste: In the process of dry anaerobic fermentation of the three types of organic solid waste in this solution, each has its own advantages and disadvantages. By mixing the three and optimizing the mixing ratio, this solution effectively improves the efficiency and effect of dry anaerobic fermentation, obtaining biogas, digestion residues, and biogas slurry. Among them, biogas, as a renewable energy source, can be used for power generation, heating, or as vehicle fuel after purification; the mixed fermentation biogas sludge can be used as fertilizer, soil conditioner, or further processed into biochar, biomass fuel, etc.; the biogas slurry (or leachate) contains dissolved organic matter, nutrient elements, etc., and can be used as farmland irrigation water or liquid fertilizer after appropriate treatment (such as filtration, disinfection, and adjustment of nutrient components). Through long-term experiments, the applicant found that the treatment cycle for 110t of mixed materials in this solution (where 10t is kitchen waste sludge, providing microorganisms and fluidity for fermentation; a total of 100t of kitchen waste organic matter and kitchen waste coarse residue, providing mixed organic matter for mixed fermentation) is 20 - 35 days, and the biogas production volume is as high as 16,000 cubic meters (i.e., the biogas production volume is as high as 160 cubic meters per ton of mixed organic matter). And after testing, the mass ratio of the biogas sludge produced after mixed fermentation to the total feed amount is about 20%, and it can be used as fertilizer, soil conditioner, etc. after simple treatment. The fermentation cycle of the mixed dry anaerobic fermentation in this solution is short, and the energy utilization rate is high.

[0011] 3. Effectively avoid blockage, continuously produce to improve efficiency and reduce maintenance costs: By setting an anti-winding mixer in the mixing unit stage, this solution facilitates the uniform mixing of multi-source solid waste in the mixing stage without the situation of mixed materials blocking the equipment, thereby realizing continuous mixing and continuous feeding to the dry anaerobic fermentation unit, further improving production continuity and production efficiency; in addition, the non-blockage of the equipment can further reduce the equipment maintenance cost and improve production benefits.

[0012] Preferably, as an improvement, the mixing unit includes a connected material pit and an anti-winding mixer. There is a mixing conveyor pipe connected between the discharge end of the anti-winding mixer and the dry anaerobic fermentation unit, and a piston pump is provided on the mixing conveyor pipe; the anti-winding mixer includes a base, a mixing cylinder rotatably connected to the base, and a driving mechanism for driving the mixing cylinder to rotate. The two ends of the mixing cylinder are respectively a feed end and a discharge end, and a mixing and dispersing section is arranged inside the mixing cylinder, and segmented spiral blades are arranged inside the mixing and dispersing section.

[0013] Technical effect: With the above settings in this solution, it is convenient to realize the mixing of kitchen waste small coarse residue, kitchen waste sludge, and kitchen waste organic matter. And by setting segmented spiral blades, it is convenient for the mixed materials to be quickly dispersed and separated during the rotation and tumbling with the mixing cylinder after entering the mixer, preventing winding and blocking the equipment.

[0014] Preferably, as an improvement, at least two groups of segmented spiral blades with different spacings are arranged inside the mixing and dispersing section.

[0015] Technical effect: With the above settings in this solution, it is convenient to adapt to the multi-level mixing of the mixed materials. Specifically, during the rotation of the mixing drum, the spiral blades with different pitches can prompt the materials to roll alternately in the axial direction, break up the mixed state of the previously mixed materials and remix them, further avoiding the agglomeration of materials and clogging of the equipment; moreover, the segmented spiral blades with different pitches also contribute to the uniform distribution and mixing of the mixed materials in the length direction of the mixing drum, improving the mixing uniformity.

[0016] Preferably, as an improvement, along the direction from the feed end to the discharge end, a conveying section is further provided at the rear end of the mixing and dispersing section. A continuous spiral blade is provided in the conveying section, and the length of the conveying section is less than or equal to one-third of the length of the mixing drum.

[0017] Technical effect: With the above settings in this solution, it is convenient to effectively push the mixed materials to discharge in a spiral manner. The combination of the two spiral blades (continuous spiral blade and segmented spiral blade) can effectively improve the continuity and stability of the multi-source material mixing. By limiting the length of the conveying section, it is convenient to shorten the settlement distance of heavy substances such as sand and gravel in the mixed materials during the conveying process, reduce their settlement and adhesion to the inner wall of the mixing drum, and thus reduce the mixing effect. In addition, when the length of the conveying section is less than one-third of the mixing drum, it is also convenient to centrally push the mixed materials to discharge, ensure the conveying efficiency and the feeding volume, and thus reduce the problem that the mixed materials are wound and clogged again during the screw conveying process.

[0018] Preferably, as an improvement, the mixing drum is inclined, and the feed end is higher than the discharge end; the aperture of the feed end of the mixing drum is larger than that of the discharge end, and the inclination taper of the mixing drum is 2-4°, preferably 2°.

[0019] Beneficial effect: With the above settings in this solution, it is convenient to further improve the discharge speed of the mixed materials. Limiting the inclination taper of the mixing drum can effectively prevent the materials from being transmitted too fast and being unevenly mixed.

[0020] Preferably, as an improvement, the pressure angle ɑ of the spiral blade is 15-20° and the height is 45-55 mm.

[0021] Technical effect: By limiting the pressure angle ɑ of the spiral blade in this solution, that is, the inclination angle between the spiral direction of the spiral blade and the radial plane of the mixing drum is 20°, it is convenient to push the mixed materials forward during the rotation of the mixing drum, avoid the materials from rolling in place, and thus accelerate the discharge speed of the mixed materials. The applicant found through long-term experiments that when the pressure angle is greater than 20°, although the conveying efficiency of the materials can be improved, it is not conducive to the dispersion and mixing of the materials. When the pressure angle is less than 15°, it is not conducive to the material conveying and is also prone to increasing the risk of jamming due to material aggregation. And by limiting the height of the spiral blade in this solution, it is beneficial to ensure the pushing volume of the materials, while reducing the risk of the materials winding and hanging on the spiral blade, and reducing the problems of blockage and stagnation.

[0022] Preferably, as an improvement, a pusher block is provided near the feeding end of the spiral blade along the spiral direction of the spiral blade, and the long axis of the pusher block is parallel to the axial direction of the mixing cylinder; the pusher block divides the space between adjacent spiral blades into a sliding material mixing gap and a pusher conveying gap.

[0023] Beneficial effects: With the above settings in this solution, it is convenient to fully mix the materials while transporting the mixed materials forward. Specifically, a pusher groove is formed between the pusher block and the spiral blade, a pusher conveying gap for pushing the material forward is formed between the pusher block and the adjacent spiral blade, and a sliding material mixing gap is formed between the end of the pusher block far from the spiral blade and the adjacent spiral blade. When the material is pushed to the upper half of the mixing cylinder by the rotation of the mixing cylinder, the material slides or rolls back to the lower half of the mixing cylinder under the action of gravity and is mixed with other materials again, and then continues to be transported forward under the push of the pusher block and the spiral blade, realizing the full mixing and forward transportation of the material in the mixing cylinder.

[0024] Preferably, as an improvement, the spiral blades of the spiral blade and the pusher block are trapezoidal, and the edges of the trapezoid are chamfered into an arc shape.

[0025] Beneficial effects: With the above settings in this solution, it is convenient to further reduce the risk of materials hanging on the spiral blade and blocking or jamming the equipment. Specifically, when the material is somewhat viscous and easy to stick, the arc-shaped spiral blade and the top of the pusher block are not easy to entangle and hang the material and are not easy to stick, and when the material falls, it has a certain effect of breaking up.

[0026] Preferably, as an improvement, the kitchen waste pretreatment unit includes a sorting machine, a pulping machine, an impurity removal machine, an oil removal machine, an anaerobic fermentation tank and a dehydrator that are connected in sequence through pipelines; the outlets of the sorting machine and the pulping machine are also connected to a washing and squeezing device, the washing and squeezing device is connected to a coarse material impurity box, and the outlet of the impurity removal machine is also connected to a small coarse residue receiving box; the outlet of the oil removal machine is also connected to a swill oil temporary storage box, and the outlet of the dehydrator is respectively connected to a sewage treatment device and a kitchen waste sludge box; the small coarse residue receiving box and the kitchen waste sludge box are both connected to the material pit.

[0027] Technical effects: With the above settings in this solution, it is convenient to process kitchen waste into coarse material residues, kitchen waste small coarse residues, kitchen waste swill oil, kitchen waste sludge and fermented sewage (obtained by fermentation of the sewage treatment device). Among them, the coarse material residues and kitchen waste swill oil can be classified and recycled, and the fermented sewage is discharged after passing the index detection. The remaining kitchen waste small coarse residues and kitchen waste sludge still contain solid content, organic matter and microorganisms (such as fermentation bacteria), etc., and are mixed in the material pit for further fermentation treatment.

[0028] Preferably, as an improvement, the dry anaerobic fermentation unit includes a fermentation tank, the discharge port of the fermentation tank is connected to an extruder and a reflux pipe, and the reflux pipe is connected to an anti-winding mixer.

[0029] Beneficial effects: With the above settings in this solution, it is convenient for a part of the fermentation mixture to flow back into the anti-tangling mixer, which is conducive to bringing the high-concentration microorganisms in the fermentation mixture back to the fermentation stage, effectively supplementing the microbial supply of the mixed materials in the fermentation stage; while the other part of the fermentation mixture is subjected to solid-liquid separation by an extruder into sewage and biogas sludge (specifically extrusion residue), thus facilitating subsequent classification treatment.

[0030] Preferably, as an improvement, the kitchen waste pretreatment unit includes a crusher, a magnetic separator, a disc screen, a drum screen and a crusher connected in sequence. The magnetic separator is also connected to a magnetic slag box; both the disc screen and the drum screen are connected to an impurity box to collect coarse slag; another outlet of the crusher is connected to a kitchen waste organic matter temporary storage box, and the kitchen waste organic matter temporary storage box is connected to a material pit.

[0031] Technical effects: With the above settings in this solution, it is convenient to pretreat kitchen waste to obtain kitchen waste organic matter, and initially mix the kitchen waste organic matter, kitchen waste small coarse slag and kitchen waste sludge in the material pit. Among them, the disc screen and the drum screen are convenient for realizing two-stage screening of kitchen waste, removing the impurities that cannot be decomposed in advance, so as to facilitate the centralized recovery of organic matter in the kitchen waste organic matter and improve the recycling rate of waste resources.

[0032] Preferably, as an improvement, this solution also provides a multi-source organic solid waste co-treatment process, including the following steps:

[0033] Step 1: Treat kitchen waste into kitchen waste small coarse slag and kitchen waste sludge;

[0034] Step 2: Treat kitchen waste into kitchen waste organic matter;

[0035] Step 3: Mix the kitchen waste small coarse slag, kitchen waste sludge and kitchen waste organic matter to obtain a mixed material; the mass ratio of the kitchen waste small coarse slag, kitchen waste sludge and kitchen waste organic matter in the mixed material is 1-3:1-3:10;

[0036] Step 4: Carry out dry anaerobic fermentation on the mixed material.

[0037] Technical effects: With the above settings in this solution, it is convenient for multi-source solid waste to be mixed and fermented to recover the organic matter in the mixed material. Specifically, the kitchen waste organic matter mainly supplies the organic matter required for fermentation. However, it still contains 10-20% impurities (among which sand and gravel account for 3-5%). When the organic matter decomposes and the impurities settle, it is easy to block the equipment; the kitchen waste small coarse slag can not only provide the organic matter required for fermentation, but also provide support for the mixed material, avoiding its settlement and blocking the equipment, and also facilitating its efficient dry anaerobic fermentation; the kitchen waste sludge mainly provides the microorganisms required for fermentation, and at the same time increases the fluidity of the mixed material. The combination of the three effectively improves the efficiency and effect of the mixed fermentation.

[0038] Through long-term experiments, the applicant found that given the high organic matter content and high treatment difficulty in small kitchen waste residues, if the addition amount of small kitchen waste residues is too low, it will not only reduce the biogas production, but also significantly reduce the treatment efficiency of small kitchen waste residues, resulting in slow digestion speed and accumulation of small kitchen waste residues in the plant area, increasing the plant cost; and if the amount of small kitchen waste residues used is too small, the fermentation efficiency will be reduced due to the lack of structural support, resulting in the collapse of the mixed materials. If the amount of small kitchen waste residues used is too large, although the biogas production will increase, the frequency of equipment blockage will increase. The inventor analyzed the reason: there is also a large amount of organic matter in the small waste residues as a support. When the organic matter is decomposed, the mixed materials will form cavities, and the sand and gravel around the cavities will settle and collapse, blocking the equipment, thus reducing the fermentation continuity. Given that the organic matter content of kitchen waste sludge is not high and its viscosity is relatively large, if there is too much kitchen waste sludge, the cohesion of biogas slurry will increase, affecting the dehydration effect of biogas slurry. Specifically, in this solution, a screw extruder (with a screen) will be used for solid-liquid separation of the fermented biogas slurry. If there is too much kitchen waste sludge, the fermented biogas sludge will be discharged from the screen, instead reducing the solid waste removal effect. If there is too little kitchen waste sludge, the fermentation effect will be reduced due to the lack of microorganisms; given that kitchen waste sludge can also increase the cohesion and fluidity of the mixed materials, if there is too little kitchen waste sludge, the cohesion and support effect on the refractory and non-degradable impurities in the mixed materials will be reduced, resulting in sedimentation and agglomeration of the impurities, reducing the fluidity of the overall fermentation mixture, and further increasing the risk of equipment blockage.

[0039] Preferably, as an improvement, in step four, the dry anaerobic fermentation temperature is 41 ± 3 °C, and the hydraulic retention time HRT is 20 - 35 d.

[0040] Technical effect: With the above settings in this solution, it is convenient to improve the resource recovery utilization rate and increase the biogas production. Through long-term experiments, the applicant found that if the fermentation temperature is too high, such as operating at a high temperature of 50 - 55 °C, although the fermentation efficiency will be accelerated and the biogas production will increase, at the same time, the ammonia nitrogen will increase, resulting in ammonia nitrogen inhibition and damage to the biochemical system, and the system stability will deteriorate; and the energy consumption during high-temperature operation increases, resulting in increased costs; if the fermentation temperature is too low, the fermentation efficiency will be reduced, thereby reducing the biogas production and the treatment efficiency of the mixed materials; if the hydraulic retention time is too short, the biogas production will be affected due to incomplete fermentation; if the hydraulic retention time is too long, the stability of the biochemical system will be affected due to the sedimentation of heavy substances (such as sand and gravel, ceramic fragments, etc.) and the enrichment of ammonia nitrogen.

[0041] Preferably, as an improvement, in step four, it also includes that the fermentation mixture of the mixed materials is refluxed to the mixing stage, and the reflux ratio is 30 - 50%.

[0042] Technical effect: By limiting the reflux ratio to 30-50% (i.e., the proportion of the refluxed fermentation mixture in the total feed is 30-50%), this solution facilitates bringing the high-concentration microorganisms in the fermentation mixture back to the fermentation stage, effectively supplementing the microbial supply in the fermentation stage of the mixed materials. The reflux to the mixing stage can also make the distribution of microorganisms in the mixed materials more uniform, significantly improving the fermentation efficiency. Moreover, the refluxed fermentation mixture has a low solid content rate, which can effectively dilute the mixed materials entering the fermentation tank, increasing their fluidity and fermentation efficiency. Through long-term experiments, the applicant found that if there is no reflux, the fermentation effect will be reduced due to reasons such as few microorganisms in the materials and poor fluidity of the materials. At the same time, no reflux will also damage the structure of the mixed materials, affecting the fermentation effect. If the reflux ratio is too high, it will affect the discharge and reduce the stability of the biochemical system due to excessive circulation ratio causing heavy substance sedimentation and enrichment of various heavy metals. If the reflux ratio is too low, it will cause problems such as insufficient inoculated microorganisms, slow mixing speed of the mixed materials, poor homogeneity, resulting in an increase in VFA, etc., instead reducing the actual load capacity of the anaerobic tank.

[0043] Preferably, as an improvement, in step three, the pH of the mixed materials is 5-7.

[0044] Technical effect: With the above settings in this solution, it is convenient to improve the fermentation effect. Through long-term experiments, the applicant found that if the pH of the mixed materials is too high, the activity of acid-producing bacteria will be affected due to excessive alkalinity, inhibiting the hydrolysis and acidification stage of fermentation. If the pH of the mixed materials is too low, it will promote the hydrolysis and acidification process and inhibit the methanogenic bacteria, thereby affecting the methanogenesis process and reducing the gas production.

[0045] Preferably, as an improvement, the solid content rate of the mixed materials is 25-35%, the organic matter content is 60-80%, the oil content rate ≤ 1%, and the particle size ≤ 6 cm.

[0046] Technical effect: With the above settings in this solution, it is convenient to effectively improve the mixed fermentation efficiency and effect of multi-source organic solid waste. The moisture content of the small coarse residue is 80%, and the organic matter content is 80-85%. In the Chongqing area, the components of the small coarse residue mainly include peppers, Chinese prickly ash, plastics, fiber-like organic matter, ceramic fragments, etc. Due to its high moisture content, low calorific value, and complex composition, it cannot meet the admission requirements for incineration or landfill. If it enters the backend disposal system, it will accelerate equipment wear.

[0047] The solid content of the biogas residue (i.e., kitchen waste sludge) obtained from the anaerobic fermentation of kitchen waste is 30-35%, and the organic matter content is 55-60%. The overall TS (Total Solids) in the kitchen waste organic matter is 27-35% (as a reference, the solid content is 30%), and the VS (Volatile Solids) is 65-75%. Among them, the organic matter content in TS is as high as 75%. The solid waste contains about 20% of impurities such as plastics and sand and gravel, which often causes winding and jamming phenomena, and at the same time will cause the aggregation and settlement of heavy substances in the tank, affecting the normal operation of the system.

[0048] After mixing the kitchen waste coarse residue, kitchen waste sludge and kitchen waste organic matter according to the above mass ratio, the obtained mixed material has a solid content of 25-35%, an organic matter content of 60-80%, an oil content of ≤1%, and a particle size of ≤6 cm, which is more conducive to improving the fermentation efficiency and effect. The applicant found through long-term experiments that if the solid content in the mixed material is too high, it will cause jamming of each device and poor material flow, and at the same time will affect the stability of the biochemical system due to poor fluidity. If the solid content is too low, it will affect the feeding and discharging of the system due to the settlement of heavy substances and the aggregation and winding of plastics, etc. The specific manifestations are: heavy substances settle in the tank, occupying the actual effective volume, causing damage to the agitator, etc., and being unable to maintain the homogeneity in the tank. If the organic matter content in the mixed material is too high, it will cause the settlement of heavy substance impurities and block the equipment due to the formation of cavities during the degradation of organic matter, and at the same time will increase the load of the anaerobic system, resulting in ammonia nitrogen inhibition due to the increase of ammonia nitrogen while the gas production increases, and then the biochemical system will be damaged and the system stability will become poor; if the organic matter content is too low, it will affect the stable operation of the feeding and discharging system due to too many impurities and insufficient nutrition, and at the same time it is difficult to maintain the continuous and stable operation of the biochemical system in the tank. If the oil content is too high, it will affect the VFA in the tank due to the slow hydrolysis of grease and damage the stability of the biochemical system; if the particle size is too large, it will cause wear and jamming of the equipment due to various winding and blockages and unable to feed and discharge normally, thus greatly reducing the fermentation continuity; if the particle size is too small, it will cause the settlement of heavy substance impurities in the tank due to the lack of structural objects in the tank.

[0049] Preferably, as an improvement, the organic matter contains 10-20% of refractory impurities, and the refractory impurities include a combination of short plastics, lignocellulose and sand and gravel.

[0050] Technical effect: With the above settings in this solution, it is convenient to maintain the material balance in the tank. The applicant found through long-term experiments that if the proportion of refractory impurities in the organic matter is too high, it will easily cause equipment jamming and affect the biogas production due to too many impurities; if the proportion of refractory impurities in the organic matter is too low, it will damage the homogeneity in the tank and cause settlement due to the lack of structural supports in the tank, thus affecting the fermentation effect.

[0051] Preferably, as an improvement, the content of heavy substances in the mixed material is 2-5%; the heavy substances are one or more combinations of glass, ceramics, and sand and gravel.

[0052] Technical effect: With the above settings in this solution, it is convenient to reduce equipment wear and reduce sedimentation blockage. Through long-term experiments, the applicant found that if the content of heavy substances is too high, it will damage the balance in the tank due to sedimentation, and cause equipment blockage and equipment wear.

[0053] Preferably, as an improvement, the feed rate of the dry anaerobic fermentation tank = V 发酵罐有效容积 / HRT.

[0054] Technical effect: With the above settings in this solution, it is convenient to maintain the activity of the bacteria. If the feed rate of the dry anaerobic fermentation cannot be met, it is necessary to increase the amount of biogas residue sludge to ensure the fluidity of the materials in the tank and the replenishment of bacteria, so as to ensure that the HRT value does not exceed 40. Through long-term experiments, the applicant found that during the experiment with a treatment volume of 110 t / d of mixed materials (wherein, 100 t of mixed organic matter composed of kitchen waste small coarse residue and kitchen waste organic matter, 10 t of kitchen waste sludge, and the effective volume of the fermentation tank is 2100 t), if the supply of raw kitchen waste small coarse residue and kitchen waste organic matter is not timely, it is necessary to increase the amount of biogas residue sludge, so as to control the overall inlet and outlet of the anaerobic tank to be stable, ensure that the HRT value does not exceed 40, and thus improve the fermentation effect and efficiency. However, although this method can ensure the feed rate, it will increase the proportion of biogas residue sludge in the mixed solid waste, resulting in difficulty in solid-liquid separation in the mixed fermentation product, and causing part of the biogas sludge to leak out of the screen in the extruder, thus reducing the solid waste removal effect. Description of the drawings

[0055] Figure 1 It is a schematic structural diagram of a multi-source organic solid waste collaborative treatment system in Embodiment 1 of the present invention.

[0056] Figure 2 It is a schematic structural diagram of the anti-winding mixing device in Embodiment 1 of the present invention.

[0057] Figure 3 It is a schematic structural diagram of the mixing cylinder in Embodiment 1 of the present invention.

[0058] Figure 4 is Figure 2 a schematic diagram of the shape of the spiral blade in

[0059] Figure 5 It is a schematic structural diagram of the mixing unit and the dry anaerobic fermentation unit in Embodiment 1 of the present invention.

[0060] Figure 6 It is a process flow diagram of a multi-source organic solid waste collaborative treatment process in Embodiment 1 of the present invention. Detailed implementation manners

[0061] The present invention will be further described in detail below in conjunction with embodiments, but the implementation manners of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following embodiments and experimental examples are conventional means well-known to those skilled in the art, and the materials, reagents, etc. used can all be obtained from commercial channels.

[0062] The markings in the attached drawings of the specification include: base 1, mixing cylinder 2, feeding end 21, discharging end 22, motor 3, driving gear 31, driven gear 32, spiral blade 4, pushing block 5, pushing and conveying gap 51, and sliding and mixing gap 52.

[0063] Embodiment 1

[0064] This solution provides a multi-source organic solid waste collaborative treatment system, basically as shown in the attached Figures 1 to 5 figures: It includes a kitchen waste pretreatment unit, a food waste pretreatment unit, a mixing unit, and a dry anaerobic fermentation unit. The discharging ends of the kitchen waste pretreatment unit and the food waste pretreatment unit are communicated with the feeding end of the mixing unit, the discharging end of the mixing unit is communicated with the feeding end of the dry anaerobic fermentation unit, and the mixing unit is provided with an anti-winding mixer.

[0065] The mixing unit includes a connected material pit and an anti-winding mixer. A mixing and conveying pipe is connected between the discharging end of the anti-winding mixer and the dry anaerobic fermentation unit, and a feeding plunger pump is provided on the mixing and conveying pipe; as Figure 2 shown, the anti-winding mixer includes a base 1, a mixing cylinder 2 rotatably connected to the base 1, and a driving mechanism for driving the mixing cylinder 2 to rotate. The driving mechanism includes a motor 3, a driving gear 31 connected to the motor 3, and a driven gear 32 sleeved outside the mixing cylinder 2, and the driving gear 31 meshes with the driven gear 32.

[0066] As Figure 3As shown in the figure, the two ends of the mixing cylinder 2 are respectively a feeding end 21 and a discharging end 22. The mixing cylinder 2 is inclined, and the feeding end 21 is higher than the discharging end 22; the aperture of the feeding end 21 of the mixing cylinder 2 is larger than that of the discharging end 22. As a reference, the inclination taper of the mixing cylinder 2 is 2 - 4°, preferably 2°, to avoid the material being transported too fast. A mixing and dispersing section is arranged inside the mixing cylinder 2, and segmented spiral blades 4 are arranged inside the mixing and dispersing section. As an improvement, at least two groups of segmented spiral blades 4 with different pitches are arranged inside the mixing and dispersing section, which is convenient for dispersing and separating the material during mixing to avoid it winding into a mass and blocking the equipment. As an improvement, along the direction from the feeding end 21 to the discharging end 22, a conveying section is also arranged at the rear end of the mixing and dispersing section. A continuous spiral blade 4 is arranged inside the conveying section, and the length of the conveying section is less than or equal to one-third of the length of the mixing cylinder 2. The pressure angle ɑ of the spiral blade 4 is 15 - 20°, and the height is 45 - 55 mm, which is convenient for dispersing and pushing the mixed material forward during the rotation of the mixing cylinder 2, improving the conveying speed and avoiding the mixed material rolling in place. Specifically, in this embodiment, equally spaced and segmented spiral blades 4 are arranged inside the mixing cylinder 2.

[0067] A pushing block 5 is arranged near the feeding end 21 of the spiral blade 4 along the spiral direction of the spiral blade 4, and the long axis of the pushing block 5 is parallel to the axial direction of the mixing cylinder 2. A pushing groove (not shown in the figure) is formed between the pushing block 5 and the spiral blade 4. The pushing block 5 divides the space between adjacent spiral blades 4 into a sliding and mixing gap 52 and a pushing and conveying gap 51. Among them, a pushing and conveying gap 51 for pushing the material forward is formed between the pushing block 5 and the adjacent spiral blade 4, and a sliding and mixing gap 52 is formed between the end of the pushing block 5 far from the spiral blade 4 and the adjacent spiral blade 4. When the material rotates with the mixing cylinder 2 to the upper half part of the mixing cylinder 2, the material slides or rolls back along the sliding and mixing gap 52 under the action of gravity to the lower half part of the mixing cylinder 2 and is mixed with other materials again, and then continues to be conveyed forward under the push of the pushing block 5 and the spiral blade 4, realizing the full mixing of the material inside the mixing cylinder 2. As a reference, the pushing block 5 is 300 mm long, and the sliding and mixing gap 52 is 200 mm long. The gap makes it easier for the material to be mixed, avoiding the material being all piled up in the pushing groove and directly discharging with the rotation of the mixing cylinder 2 and being difficult to be evenly mixed.

[0068] As Figure 4 shown in the figure, the shapes of the spiral blade 4 and the pushing block 5 are both inclined "trapezoids", and the edges of the "trapezoids" are chamfered into arcs. Because when the material has some viscosity and is easy to stick, the top ends of the arc-shaped spiral blade 4 and the pushing block 5 are not easy to wind and hang the material and are not easy to stick, and when the material falls, it has a certain dispersing effect.

[0069] As Figure 2As shown in the figure, the kitchen waste pretreatment unit includes a sorting machine, a pulping machine, an impurity removal machine, an oil removal machine, an anaerobic fermentation tank and a dehydrator connected by pipelines; the outlets of the sorting machine and the pulping machine are also connected to a washing and squeezing device, the washing and squeezing device is connected to a coarse material impurity box, and the outlet of the impurity removal machine is also connected to a small coarse residue receiving box; the outlet of the oil removal machine is also connected to a swill oil temporary storage box, and the outlet of the dehydrator is respectively connected to a sewage treatment device and a kitchen waste sludge box; both the small coarse residue receiving box and the kitchen waste sludge box are connected to a material pit.

[0070] The kitchen waste pretreatment unit includes a crusher, a magnetic separator, a disc screen, a drum screen and a crusher connected in sequence. The magnetic separator is also connected to a magnetic material slag box; both the disc screen and the drum screen are connected to an impurity box to collect coarse residues; another outlet of the crusher is connected to a kitchen waste organic matter temporary storage box, and the kitchen waste organic matter temporary storage box is connected to a material pit. Kitchen waste organic matter is obtained and preliminarily mixed with kitchen waste organic matter, kitchen waste small coarse residues and kitchen waste sludge in the material pit.

[0071] As Figure 5 As shown in the figure, the dry anaerobic fermentation unit includes a fermentation tank, which is a vertical anaerobic fermentation tank or a horizontal anaerobic fermentation tank. As a reference, the fermentation tank in this solution is specifically a vertical anaerobic fermentation tank. The top of the fermentation tank is connected to a biogas collection device, and the discharge port of the fermentation tank is connected to an extruder and a reflux pipe, and the reflux pipe is connected to an anti-tangling mixer. As a reference, the bottom of the fermentation tank is provided with a discharge port, the discharge port is connected to a bottom discharge screw, the outlet of the bottom discharge screw is connected to an extruder and a reflux pipe, and the other end of the discharge of the reflux pipe is connected to the feed end of the anti-tangling mixer. A discharge plunger pump is provided on the connecting pipeline between the extruder and the bottom discharge screw. The mixed fermented material is discharged from the fermentation tank through the discharge port, and then is respectively connected to the anti-tangling mixer through the reflux pipe and connected to the extruder through the discharge plunger pump. The discharge port of the extruder is respectively connected to an extrusion slag box and a sewage box to collect and temporarily store the mixed fermented biogas sludge and sewage.

[0072] This solution also provides a multi-source organic solid waste co-treatment process, which is completed by using the above multi-source organic solid waste co-treatment system. As Figure 6 shown in the figure, it includes the following steps:

[0073] Step 1: Treat kitchen waste into kitchen waste small coarse residues and kitchen waste sludge;

[0074] Step 2: Treat kitchen waste into kitchen waste organic matter;

[0075] Step 3: Mix the kitchen waste small coarse residues, kitchen waste sludge and kitchen waste organic matter to obtain a mixed material. The mass ratio of the kitchen waste small coarse residues, kitchen waste sludge and kitchen waste organic matter in the mixed material is 1-3:1-3:10.

[0076] Specifically, the moisture content of the kitchen waste small coarse residue obtained in Step 1 of this solution is 80%, and the organic matter content is 80-85%; among them, the components of the small coarse residue mainly include peppers, Chinese prickly ash, plastics, fibrous organic matter, ceramic fragments, etc. Due to its high moisture content, low calorific value, and complex composition, it cannot meet the entry requirements for incineration or landfill. If it enters the backend disposal system, it will accelerate equipment wear.

[0077] The solid content of the biogas residue obtained from the anaerobic fermentation of kitchen waste (i.e., the kitchen waste sludge obtained in Step 1) is 30-35% (as a reference, the solid content of the kitchen waste sludge obtained in this example is specifically 32%), and the organic matter content is 55-60%.

[0078] The overall TS (i.e., solid content) in the kitchen waste organic matter is 27-35% (as a reference, the solid content of the kitchen waste organic matter in this example is 30%), and the VS (Volatile Solids) is 65-75%. Among them, the organic matter content in TS is as high as 75%. The solid waste contains about 20% of impurities such as plastics and sand and gravel, resulting in frequent entanglement and blockage, and at the same time causing the aggregation and settlement of heavy substances in the tank, affecting the normal operation of the system.

[0079] The pH of the mixed material obtained by mixing kitchen waste small coarse residue, kitchen waste sludge, and kitchen waste organic matter in a mass ratio of 1-3:1-3:10 is 5-7 (i.e., the pH during feeding is 5-7, and as the anaerobic fermentation progresses, the pH of the mixed fermented material in the fermentation tank is 7.8-8.5), the solid content is 25-35%, the organic matter content is 60-80%, the oil content ≤ 1%, and the particle size ≤ 6 cm. Among them, the organic matter contains 10-20% of refractory impurities, and the refractory impurities include a combination of short plastics, lignocellulose, and sand and gravel.

[0080] Step 4: Carry out dry anaerobic fermentation on the mixed material. The fermentation temperature is 41±3°C, and the hydraulic retention time HRT is 20-35 d. Collect biogas, fermentation sewage, and biogas residue respectively. Specifically, after fermentation, it also includes the reflux of the fermentation mixture, and the reflux ratio is 30-50%, which is convenient to supplement microorganisms for the mixed material and improve its fermentation efficiency. Another part of the fermentation mixture is transported to an extruder, and through the combined action of the screw conveyor and the screen in the extruder, the fermentation mixture is separated into solid and liquid phases as extruded residue (i.e., biogas residue) and fermentation sewage.

[0081] During the fermentation process, it is also necessary to ensure a certain amount of feeding and discharging to maintain the activity of the strains. If the feeding amount for dry anaerobic fermentation cannot be met, the amount of biogas residue sludge needs to be increased to ensure the fluidity of the materials in the tank and the supplement of strains, so as to ensure that the HRT value does not exceed 40.

[0082] Experimental Example 1: Differences in the treatment effects of kitchen waste organic matter under different parameter combinations

[0083] Specifically, the dry anaerobic tank of Chongqing Luoqi Catering Kitchen Factory was used as the test carrier to specifically demonstrate the influence of factors such as the raw material mixing ratio and hydraulic retention time on the fermentation results in a multi-source organic solid waste coordinated treatment process of this scheme. The value differences of Examples 1 to 4 and Comparative Examples 1 to 7 are detailed in Table 1, and the total feed amount of each Example and Comparative Example is maintained at 100t / d.

[0084] During the production process, the gas production, the proportion of methane in the biogas, the total solids (TS), pH, total organic carbon (TOC or TAC), volatile fatty acids (VFC), and the average value of ammonia nitrogen are continuously detected and calculated. The production is continued for one year and the blockage cycle is recorded.

[0085] Table 1 Differences in values ​​and results of Examples 1 to 4 and Comparative Examples 1 to 7

[0086]

[0087] Experimental data show that this solution effectively achieves continuous production of multi-source organic solid waste while improving fermentation effect (such as ensuring gas production) by limiting the mass ratio of the three raw materials in the mixture, hydraulic retention time (HRT), reflux ratio and other parameters, thereby effectively improving fermentation efficiency. Specifically, during the one-year continuous production of multi-source organic solid waste in this solution, the equipment rarely gets blocked or stopped during the normal production and maintenance cycle of the equipment (generally). Specifically, even if the production is continuous, the period of equipment blockage and stoppage is as long as 2 to 3 months, effectively achieving continuous production of multi-source organic solid waste.

[0088] The applicant also found in long-term experiments that if the proportion of small coarse slag is too high (such as comparative example 1), it will lead to high gas production per ton, increased VFA, increased ammonia nitrogen, which will increase the system load, and the biochemical system will be destroyed due to the inhibition of ammonia nitrogen, and the system stability will deteriorate, which is not conducive to the continuous and efficient treatment of kitchen waste organic matter. If small coarse kitchen slag is not added (such as comparative example 2), the organic matter in the multi-source organic solid waste will be reduced due to the lack of support, which will reduce its fermentation effect and gas production. If only small coarse kitchen slag and kitchen sludge that mainly provides microbial action are added (such as comparative example 3), the fermentation process will be accelerated due to the lack of organic matter, and the excessive consumption of organic matter will cause the mixed material to form cavities after the reaction. The sand and gravel around the cavity will settle and collapse and block the equipment, thereby reducing the continuity of fermentation (blocking period 1 to 3 days).

[0089] The kitchen waste sludge can enhance the microorganisms in the system, improve the adhesion and fluidity of the materials, and accelerate the fermentation efficiency without easily clogging the system. If the dosage of the sludge is too high, for example, in Comparative Example 6, the dosage of the sludge is increased to 5, although it effectively improves the activity of the strains and increases the gas production, etc., but the excessive sludge will also reduce the subsequent solid-liquid separation effect, resulting in the sludge entering the fermentation sewage from the sieve holes. This is not only not conducive to the recycling of microorganisms in the sludge (if the microbial content is high, it can be used to treat kitchen waste oil), but also the sludge will increase the viscosity of the fermentation wastewater, reduce the solid waste removal effect in the fermentation mixture, and instead increase the treatment cost of the fermentation sewage. If no kitchen waste sludge is added (such as in Comparative Example 7), the fermentation effect will be reduced due to the lack of microorganisms, and the binding effect on refractory or non-degradable impurities will also be reduced due to the lack of sludge, resulting in the sedimentation and agglomeration of impurities and increasing the risk of equipment blockage.

[0090] If the residence time (HRT) is too short (such as in Comparative Example 4), the biogas production will be affected due to incomplete fermentation; if the hydraulic retention time is too long (such as in Comparative Example 5), the sedimentation of heavy substances (such as sand, ceramic fragments, etc.) and the enrichment of ammonia nitrogen, etc. will affect the stability of the biochemical system, and instead lead to blockage and equipment shutdown.

[0091] If there is no reflux or the reflux ratio is too low (such as in Comparative Example 8), the fermentation effect will be reduced due to reasons such as few microorganisms in the materials and poor fluidity of the materials. At the same time, no reflux will also destroy the structure of the mixed materials and affect the fermentation effect.

[0092] Experimental Example 2: Influence of the dosage of small kitchen waste residues on dry anaerobic fermentation

[0093] Referring to the process flow of a multi-source organic solid waste dry fermentation process in Example 1 of this solution, multi-source solid waste mixed dry anaerobic fermentation is carried out with different dosages of small kitchen waste residues. The result detection and statistical methods are referred to Experimental Example 1, and the results are recorded in Table 2.

[0094] Table 2 Influence of the dosage of small kitchen waste residues on dry anaerobic fermentation

[0095]

[0096] Experimental data show that as the proportion of small kitchen waste residues in the mixed materials increases, although the biogas production per ton of raw materials is high, both VFA and ammonia nitrogen will increase accordingly, increasing the treatment difficulty of the fermentation sewage and also aggravating the system blockage. Even when the dosage of small kitchen waste residues is the same as that of kitchen waste organic matter (such as in Comparative Example 13), the anaerobic tank will be blocked after running for one day or even half a day, and it needs to be cleaned out, unable to continuously ferment and produce, seriously reducing the fermentation efficiency of multi-source solid waste.

[0097] The above are only embodiments of the present invention, and common general technical solutions and / or characteristics in the solutions are not described in detail herein. It should be noted that for those skilled in the art, without departing from the technical solutions of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicability of the patent. The protection scope claimed in this application shall be subject to the content of its claims, and the specific implementation manners described in the specification can be used to interpret the content of the claims.

Claims

1. A multi-source organic solid waste collaborative treatment process, characterized by: The multi-source organic solid waste collaborative treatment system is adopted, and the multi-source organic solid waste collaborative treatment system includes a restaurant kitchen waste pretreatment unit, a kitchen waste pretreatment unit, a mixing unit and a dry anaerobic fermentation unit. The discharge ends of the restaurant kitchen waste pretreatment unit and the kitchen waste pretreatment unit are connected to the feed end of the mixing unit, and the discharge end of the mixing unit is connected to the feed end of the dry anaerobic fermentation unit. The mixing unit is provided with an anti-winding mixer; The anti-winding mixer comprises a base, a mixing barrel rotatably connected to the base, and a driving mechanism for driving the mixing barrel to rotate. The two ends of the mixing barrel are a feeding end and a discharging end respectively. The mixing barrel is tilted, and the feeding end is higher than the discharging end. A mixing and dispersing section is arranged in the mixing and dispersing section. Segmented spiral sheets are arranged in the mixing and dispersing section. A pushing block is arranged near the feeding end of the spiral sheet along the spiral direction of the spiral sheet, and the long axis of the pushing block is parallel to the axial direction of the mixing barrel. The pushing block divides the space between adjacent spiral sheets into a sliding material mixing gap and a pushing and conveying gap. The process comprises the following steps: Step 1: Process the food waste into small coarse food residue and food sludge; Step 2: Process the kitchen waste into kitchen organic matter; Step 3: mixing small coarse food residues, food sludge and food waste organic matter to obtain a mixed material; the mass ratio of small coarse food residues, food sludge and food waste organic matter in the mixed material is 1 to 3:1 to 3:10; Step 4: subjecting the mixed material to dry anaerobic fermentation; the dry anaerobic fermentation temperature is 41±3°C, and the hydraulic retention time HRT is 20-35d; and also includes the return of the biogas slurry after the fermentation of the mixed material, and the return ratio is 30-50%.

2. A multi-source organic solid waste collaborative treatment process according to claim 1, characterized in that: The mixing unit comprises a connected material pit and an anti-winding mixer; a mixing conveying pipe is connected between the discharge end of the anti-winding mixer and the dry anaerobic fermentation unit, and a plunger pump is provided on the mixing conveying pipe; the aperture of the feed end of the mixing barrel is larger than the aperture of the discharge end, and the inclination taper of the mixing barrel is 2 to 4°; the pressure angle ɑ of the spiral blades is 15 to 20° and the height is 45 to 55 mm.

3. A multi-source organic solid waste collaborative treatment process according to claim 2, characterized in that: The mixing barrel has an inclination taper of 2°.

4. The multi-source organic solid waste collaborative treatment process according to claim 1, characterized in that: At least two groups of segmented spiral blades with different spacings are arranged in the mixing and dispersing section; along the direction from the feeding end to the discharging end, a conveying section is also arranged at the rear end of the mixing and dispersing section, and continuous spiral blades are arranged in the conveying section. The length of the conveying section is less than or equal to one third of the length of the mixing barrel.

5. The multi-source organic solid waste collaborative treatment process according to claim 1, characterized in that: The shapes of the spiral blade and the pusher block are both inclined "trapezoidal", and the chamfered edges of the "trapezoidal" are arc-shaped.

6. The multi-source organic solid waste collaborative treatment process according to claim 1, characterized in that: The restaurant kitchen waste pretreatment unit comprises a sorting machine, a pulping machine, a debris remover, an oil remover, an anaerobic fermentation tank and a dehydrator which are connected in sequence by pipelines; the outlets of the sorting machine and the pulping machine are also connected with a washing and squeezing device, the washing and squeezing device is connected with a coarse material impurity box, the outlet of the debris remover is also connected with a small coarse slag receiving box; the outlet of the oil remover is also connected with a sewage oil temporary storage box, the outlet of the dehydrator is respectively connected with a sewage treatment device and a restaurant kitchen sludge box; the small coarse slag receiving box and the restaurant kitchen sludge box are both connected with a material pit.

7. The multi-source organic solid waste collaborative treatment process according to claim 1, characterized in that: The dry anaerobic fermentation unit comprises a fermentation tank, a material outlet of the fermentation tank is connected with an extruder and a reflux pipe, and the reflux pipe is connected with an anti-winding mixer.

8. The multi-source organic solid waste collaborative treatment process according to claim 1, characterized in that: The mixed material has a solid content of 25-35%, an organic matter content of 60-80%, an oil content of ≤1%, and a particle size of ≤6 cm.

9. A multi-source organic solid waste collaborative treatment process according to claim 8, characterized in that: The organic matter contains 10-20% of hard-to-degrade impurities, which include a combination of short plastics, wood cellulose and sand and gravel.

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