Method and system for high-value utilization of restaurant kitchen waste

Abstract

The present invention discloses a method and system for high-value utilization of restaurant kitchen waste. The method comprises: using the slurry after oil extraction as a leaching liquid to wash the waste; using a separation screen for filtering; sending the filtrate to a three-phase oil extractor for oil extraction, sending part of the slurry after oil extraction as a leaching liquid to leaching, sending part of the remaining slurry to an ammoniation tank, and sending the other part to an anaerobic tank; the slurry after ammoniation is centrifuged by a disc centrifuge to obtain an organic carbon source, discharging solid residue and returning part of the solid residue to the ammoniation tank, and sending the remaining solid residue and another part of the slurry in the remaining slurry to an anaerobic tank for anaerobic reaction. The present invention develops an organic carbon source using restaurant kitchen waste as raw material, improves the efficiency of restaurant kitchen waste treatment, and improves the degree of resource utilization of restaurant kitchen waste.

Description

Technical Field

[0001] The present invention relates to the technical field of restaurant kitchen waste treatment, and in particular to a method and system for high-value utilization of restaurant kitchen waste. Background Art

[0002] Restaurant kitchen waste contains a large amount of organic matter such as oil, protein, amino acids, etc. If it is not properly disposed of, it will cause serious environmental pollution. Restaurant kitchen waste has a high utilization value after recycling. The oil can be used as industrial raw materials after recovery, the protein and amino acids can be used as feed additives, and the residue can be used as raw materials for anaerobic biogas production. The invention recognizes that the hydrolyzate of restaurant kitchen waste has a high carbon-nitrogen ratio. The development of an organic carbon source using restaurant kitchen waste as raw material can simultaneously reduce the cost pressure and water treatment pressure of sewage treatment plants and restaurant kitchen waste plants. However, the current treatment process has a low utilization rate of restaurant kitchen waste, a long treatment time, and low treatment efficiency. In addition, in order to improve the ammonia nitrogen conversion rate, membrane treatment is usually used to intercept organic nitrogen. However, while intercepting organic nitrogen, a lot of COD will also be intercepted, which results in the COD not being fully utilized; and the treatment cost and maintenance cost are also high. Summary of the Invention

[0003] According to one embodiment of the present invention, the purpose is to provide a method and system for high-value utilization of restaurant kitchen waste, thereby improving processing efficiency and resource utilization. The above purpose can be achieved through the implementation of the following technical solutions:

[0004] According to one aspect of the present invention, the present invention provides a method for high-value utilization of restaurant kitchen waste, comprising:

[0005] The sorted kitchen waste is sent to the leaching equipment. Under the action of stirring, the slurry after oil extraction is used as the leaching liquid to wash the waste, so that the waste is hydrolyzed and acidified during the leaching process.

[0006] The leached liquid after washing is sent to the separation sieve for filtration;

[0007] The filtrate after filtering through the separation screen is sent to the three-phase oil extractor for oil extraction, and part of the slurry after oil extraction is sent to the leaching equipment as the elution liquid, and the remaining slurry is divided into the first slurry and the second slurry;

[0008] feeding the first slurry in the remaining slurry into an amination tank for amination reaction;

[0009] The ammoniation slurry is sent to a disc centrifuge, and the organic carbon source and solid residue are obtained by centrifugation using the disc centrifuge, and part of the solid residue after centrifugation is returned to the ammoniation tank;

[0010] The second slurry in the remaining slurry and the solid residue remaining after reflux are sent together into an anaerobic tank for anaerobic reaction.

[0011] Optionally, 75% to 85% of the solid residue after centrifugation is returned to the ammoniazing tank.

[0012] Optionally, 65% to 75% of the remaining slurry is used as the second slurry, and the rest is used as the first slurry.

[0013] Optionally, in the elution equipment, the temperature is controlled at 30° C. to 40° C., and the pH is controlled at 5.5 to 6.0; and the hydrolysis and acidification time in the elution stage is controlled at 48 h to 60 h.

[0014] Optionally, in the step of sending part of the slurry after oil extraction to the leaching equipment as a leaching liquid, the delivery is controlled according to the slurry amount being 2 to 4 times the amount of garbage.

[0015] Optionally, during the amination reaction, the temperature is controlled at 45° C. to 50° C., the pH is 6.0 to 6.5, and the hydraulic retention time of the amination tank is 2.5 days to 3.5 days.

[0016] Optionally, during the anaerobic reaction, the temperature is controlled at 51° C. to 53° C. and the pH is controlled at 6.6 to 7.5.

[0017] Optionally, the method further includes:

[0018] Part of the biogas after anaerobic combustion is used to generate electricity, and the waste heat during the combustion and power generation process is used as an oil extraction heat source to heat the garbage in the three-phase oil extraction machine, and the temperature is controlled at 70℃~75℃.

[0019] Optionally, the method further comprises: purifying part of the biogas after anaerobic treatment to prepare biogas.

[0020] Optionally, the method further includes: centrifugal dehydration of the post-anaerobic biogas slurry, preparing fertilizer using the biogas residue after centrifugal dehydration, and performing water treatment on the liquid phase after centrifugal dehydration.

[0021] Optionally, the method further includes: using the solid residue obtained by filtration through a separation sieve to feed insects; using the insects to prepare high-protein feed; and using insect feces to prepare organic fertilizer; wherein the heat source required in the preparation of the high-protein feed comes from the waste heat in the anaerobic biogas combustion power generation process.

[0022] According to another aspect of the present invention, the present invention provides a system for high-value utilization of restaurant kitchen waste, comprising:

[0023] It includes a washing device, a separation screen, a three-phase oil extractor, an ammonia tank, a disc centrifuge, and an anaerobic tank arranged in sequence; among which,

[0024] The top of the elution equipment is provided with an eluent injection device, an agitator is provided inside, and the inlet of the eluent injection device is connected to the slurry outlet pipe of the three-phase oil extractor;

[0025] The separation screen is connected to the outlet of the washing equipment;

[0026] The inlet of the three-phase oil extractor is connected to the filtrate outlet of the separation screen, and the slurry outlet of the three-phase oil extractor is connected to the leaching equipment, the ammoniation tank and the anaerobic tank respectively;

[0027] The ammoniazing tank is used to receive the slurry sent by the three-phase oil extractor and perform an ammoniazing reaction;

[0028] The disc centrifuge is connected to the outlet of the ammoniation tank and has an organic carbon source outlet and a solid residue outlet; wherein the solid residue outlet is connected to the ammoniation tank to reflux the solid residue, and the solid residue outlet is also connected to the anaerobic tank;

[0029] The anaerobic tank is used to respectively receive the slurry conveyed by the three-phase oil extractor and the solid residue conveyed by the disc centrifuge, and perform anaerobic reaction.

[0030] Optionally, flow meters are provided on the pipelines connecting the slurry outlet to the leaching equipment, the ammoniaization tank and the anaerobic tank respectively.

[0031] Optionally, a reflux flow controller is provided at the solid slag outlet.

[0032] Optionally, the system further includes: a biogas power generation device connected to the biogas outlet of the anaerobic tank, and an insect breeding device connected to the solid residue outlet of the separation screen; wherein the waste heat boiler of the biogas power generation device is connected to the three-phase oil extractor, and is used to heat the slurry in the three-phase oil extractor using waste heat; the insect breeding device is used to raise insects using solid residue as raw material, and the raised insects are used to prepare high-protein feed, and the insect feces are used to make organic fertilizer.

[0033] Optionally, the separation screen is composed of three layers of screens, wherein the aperture of the upper layer of screen is 6mm to 10mm, the middle layer is 2mm to 5mm, and the bottom layer is 0.3mm to 1mm.

[0034] Optionally, the disc centrifuge is a disc centrifuge with a continuous slag discharge function, and the disc centrifuge has a plurality of micro-pore nozzles spaced around the drum cover, and the micro-pore nozzles are located above the intermittent discharge port.

[0035] Beneficial Effects: According to one embodiment of the present invention, a portion of the slurry after three-phase oil extraction is used as a leaching liquid to wash the garbage, causing hydrolysis and acidification to begin during the leaching process. The filtered filtrate is then sent to a three-phase oil extractor for oil extraction. Part of the remaining slurry after oil extraction is sent to an ammoniation tank, and another portion is sent to an anaerobic tank. The ammoniation tank is centrifuged in a disc centrifuge to obtain an organic carbon source. Solid residue is discharged and part of the solid residue is returned to the ammoniation tank. The remaining solid residue and the remaining slurry are sent to the anaerobic tank for anaerobic reaction. This high-value utilization method develops an organic carbon source using restaurant kitchen waste as raw material, improving the efficiency of restaurant kitchen waste treatment and the degree of resource utilization.

[0036] Compared with the prior art, some embodiments of the present invention also have the following advantages:

[0037] 1) The "slurry after three-phase oil extraction" is used as the eluent to elute the garbage. A large number of hydrolytic acidifying bacteria accumulate in the slurry after three-phase oil extraction, which can increase the hydrolysis and acidification efficiency. The eluent allows the garbage to fully contact the hydrolytic acidifying bacteria, further improving the biological hydrolysis and acidification efficiency. The eluent is used to advance the hydrolysis to the pretreatment stage of the food waste, so that the hydrolysis reaction runs through the elution, separation, and three-phase oil extraction processes, saving hydrolysis and acidification time, eliminating the need for a separate hydrolysis tank, and shortening the overall process time.

[0038] 2) By returning a portion of the solid residue from the disc centrifuge to the ammoniaization tank, the ammonia-forming bacteria in the ammoniaization tank are continuously enriched, increasing the ammoniaization rate and the ammonia-nitrogen conversion rate. The returned solid residue also adjusts the pH value in the ammoniaization tank. Furthermore, the optimal pH range for ammonia-forming bacteria is relatively narrow, and a large reflux rate of 75% to 85% of the solid residue provides an optimal environment for the ammoniaization bacteria. Furthermore, by only returning a portion of the solid residue, while the remaining 15% to 25% is discharged, the accumulation of toxic substances in the ammoniaization tank is avoided, and the loss of excessive ammonia-forming bacteria is also minimized.

[0039] 3) By sending part of the slurry after oil extraction by the three-phase oil extractor and the remaining solid residue after reflux into the anaerobic tank, since hydrolysis and acidification run through the leaching, separation and oil extraction processes, the slurry after oil extraction and the solid residue after dishing have basically completed hydrolysis and acidification. Both contain a large amount of volatile acid, which enters the anaerobic tank, accelerating the anaerobic biogas production rate and increasing the biogas volume.

[0040] 4) By sending part of the slurry after oil extraction by the three-phase oil extractor to the ammonia tank, the ammonia reaction is carried out in the ammonia tank, thereby improving the ammonia nitrogen conversion rate, eliminating the need for subsequent membrane treatment, and retaining high-quality COD to the maximum extent. There is no need to worry about the degradation of organic nitrogen during the use of the obtained organic carbon source.

[0041] 5) After ammonia nitrogen treatment, most of the suspended solids (SS) are removed by using a disc centrifuge, the carbon-nitrogen ratio (C / N) is improved, and some nitrogen-containing organic matter is also removed, eliminating the complex suspended solids treatment process, reducing the use and maintenance costs, and reducing the equipment footprint.

[0042] 6) The solid residue filtered by the separation screen is combined with insect breeding, and insect breeding is used to make resource utilization of the solid residue, thereby reducing the disposal cost of the solid residue and increasing the secondary utilization rate of restaurant kitchen waste.

[0043] 7) Post-anaerobic biogas is used for biogas power generation and / or biogas purification to produce biogas, reducing direct methane emissions. In addition, while biogas power generation is being performed, the waste heat is used for heating in front-end processing, such as serving as a heat source to heat the slurry in the three-phase oil extractor, thus maximizing resource utilization and eliminating the need for excessive external energy sources for the overall process. Heating can be provided by the process itself, reducing energy consumption.

[0044] 8) The overall process effectively separates solids from liquids and utilizes both the solid residue and filtrate to maximize their potential. For example, the solid residue can be used to feed insects to produce protein feed and organic fertilizer, solid residue recirculation can improve ammoniation efficiency, and the hydrolyzed liquid can be used to generate an organic carbon source, which can then be anaerobicly reacted with the solid residue to produce biogas. This resourceful utilization of food waste reduces waste disposal costs and minimizes environmental impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a process flow chart for high-value utilization of restaurant kitchen waste according to one embodiment of the present invention.

[0046] Figure 2 Schematic diagram of the arrangement position of the micro-hole nozzle in a disc centrifuge in one embodiment of the present invention.

[0047] Figure 3 The figure is a schematic diagram of the arrangement of micro-hole nozzles along the periphery of the drum cover in a disc centrifuge according to one embodiment of the present invention. DETAILED DESCRIPTION

[0048] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0049] The present invention provides a system for high-value utilization of restaurant kitchen waste, comprising a sequentially arranged rinsing device, a separation screen, a three-phase oil extractor, an ammoniation tank, a disc centrifuge, and an anaerobic tank. The slurry outlet of the three-phase oil extractor is connected to the rinsing device, the ammoniation tank, and the anaerobic tank, respectively; the solid residue outlet of the disc centrifuge is connected to the ammoniation tank for solid residue recirculation, and the solid residue outlet is also connected to the anaerobic tank.

[0050] The present invention provides a method for high-value utilization of restaurant kitchen waste, which is based on a leaching-separation-oil extraction-ammoniation-disc centrifugation-anaerobic process for high-value utilization. Part of the slurry after oil extraction in a three-phase oil extractor is used as a leaching liquid, part of the solid residue after disc centrifugation separation is returned to an ammoniation tank, and the remaining solid residue and the remaining slurry after oil extraction are sent to an anaerobic tank. This method realizes the preparation of an organic carbon source using restaurant kitchen waste as raw material, improves the restaurant kitchen waste treatment efficiency, and improves the degree of resource utilization.

[0051] In addition, in a preferred embodiment, the slurry remaining after oil extraction is divided into two parts, one part enters the ammoniation tank for ammoniation, and the other part is sent to the anaerobic tank to produce biogas, thereby improving the efficiency of the anaerobic reaction and obtaining an organic carbon source. The inventors have found that using 65% to 75% of the remaining slurry as the second slurry, for example, 65%, 70%, 75%, etc., and the rest as the first slurry, can achieve better results. There are a large amount of VFAs in the slurry after oil extraction. By sending the large amount of slurry to the anaerobic tank, the efficiency of the anaerobic reaction can be effectively improved and the biogas production can be increased. The remaining slurry can be treated by ammoniation and centrifugation to obtain an organic carbon source. It should be noted that the method for controlling the amount of slurry after oil extraction is not limited. For example, a flow meter can be set on the pipeline connecting the slurry outlet of the three-phase oil extractor to the leaching equipment, the ammoniation tank and the anaerobic tank respectively, and the flow meter can be used to control the slurry to be utilized according to the above ratio.

[0052] Furthermore, in a preferred embodiment, by returning a portion of the solid residue after disc centrifugation to the ammoniation tank and discharging the remainder without recirculation, the ammonia nitrogen conversion rate is increased, and the resulting organic carbon source does not need to consider organic nitrogen degradation during use. The inventors have found that returning 75% to 85% of the solid residue after centrifugation to the ammoniation tank, for example, 75%, 80%, 85%, etc., while not recirculating the remaining solid residue and sending it to the anaerobic tank, can achieve better results. Recirculating the solid residue at the above ratio, on the one hand, maintains a good bacterial residence time and increases the ammoniation rate; on the other hand, not recirculating the remaining solid residue can prevent the accumulation of toxic substances in the ammoniation tank, which is more conducive to bacterial growth and renewal. Furthermore, controlling the discharge volume to 15% to 25% does not result in excessive loss of ammoniation bacteria. It should be noted that the method for controlling the solid residue return rate is not limited. For example, a return rate controller can be provided at the solid residue outlet. Specifically, this can be a weighing device, a volume measuring device, etc. to ensure the solid residue return rate.

[0053] In addition, in a preferred embodiment, when high-value utilization is achieved, a leaching-separation-oil extraction-ammoniation-disc centrifugation-anaerobic process is adopted. The inventors have also improved and optimized the reaction conditions of leaching, ammoniation and anaerobic treatment respectively.

[0054] The inventors of this application have noted that the current prior art typically requires approximately three days to complete hydrolysis and acidification. Hydrolysis and acidification are performed simultaneously, and acidification is rapid (completed in a few hours), but the hydrolysis process is long and slow. To address this issue, a method has been developed that utilizes a leaching solution to advance hydrolysis to the pretreatment stage of food waste, allowing hydrolysis and acidification to proceed throughout the leaching, separation, and three-phase oil extraction stages, significantly saving time. Furthermore, in a preferred embodiment, the hydrolysis and acidification time during the leaching stage is 48 to 60 hours, for example, 48 hours, 50 hours, 52 hours, 54 hours, 56 hours, 58 hours, 60 hours, etc., and then, after subsequent separation and three-phase oil extraction, the hydrolysis and acidification process is complete, saving time for the subsequent hydrolysis and acidification process and ensuring efficient anaerobic reaction. In addition, when the slurry after oil extraction is used as the eluent to elute the garbage under stirring, the temperature in the eluent equipment is controlled at 30℃~40℃, and the pH of the leachate formed in the eluent is controlled at 5.5~6.0. Under this condition, eluent can further improve the hydrolysis and acidification efficiency and shorten the hydrolysis and acidification time.

[0055] In addition, when part of the slurry and part of the solid residue are refluxed into the amination tank after three-phase oil extraction, when the amination reaction is carried out, preferably, the temperature is controlled to be 45°C to 50°C, the pH is 6.0 to 6.5, and the hydraulic retention time of the amination tank is 2.5 days to 3.5 days. Under the above conditions, amination can effectively improve the ammonia nitrogen conversion rate, avoid COD loss due to membrane treatment, and the obtained organic carbon source does not need to consider the problem of organic nitrogen degradation in the subsequent use process.

[0056] In addition, the remaining solid residue after disc reflux and the remaining slurry after oil extraction enter the anaerobic tank together. During the anaerobic reaction, the temperature is controlled at 51℃~53℃ and the pH is 6.6~7.5. A large amount of volatile organic acids in the solid residue and slurry can be directly utilized by methanogens. Under these conditions, the anaerobic reaction efficiency is greatly improved and the biogas production rate is increased.

[0057] In addition, the current conventional intermittent disc centrifuge mainly includes a drum, a distribution plate, and a disc group coaxial with the distribution plate. The suspension is added through a feed pipe located in the center of the drum. When the suspension flows through the gap between the discs, the solid particles settle on the discs under the action of the centrifuge to form sediment. The sediment slides along the surface of the discs and detaches from the discs and accumulates in the large diameter part of the drum. Subsequently, the sediment is discharged from the intermittent discharge port here regularly, and the separated liquid is discharged from the drum from the upper liquid outlet. However, the inventors found that the conventional intermittent slag-discharging disc centrifuge has an original structure with a maximum slag discharge time of usually 2 minutes. Since the kitchen waste itself contains a lot of suspended matter, if too much feed is fed in a short period of time, the slag chamber will be blocked. In order to avoid blockage and improve separation efficiency, in a preferred embodiment, a disc centrifuge with a continuous slag discharge function is used.

[0058] Specifically, if Figure 3 and Figure 2 As shown, multiple smaller micro-hole nozzles are spaced around the drum cover, and the micro-hole nozzles are located above the intermittent discharge port. During the centrifugal treatment process of the disc centrifuge with the above structure, the solid matter in the suspension of food waste is thrown to the inner wall of the drum under the action of centrifugal force; Figure 2 The solids with large particles and high density in the lower middle part are gathered at the rotation center farthest from the disc centrifuge. This part can be understood as the component with larger particle size. The solids gathered here are waiting for intermittent discharge and are discharged outward from the intermittent discharge port at 360° without dead angles. Figure 2 The solids with the lowest density and the smallest particles in the middle and upper part are squeezed to a point closer to the rotation center of the disc centrifuge, and the small particles of solids gathered in the drum closest to the rotation center can be continuously discharged outward through the micro-hole nozzles set on the drum cover.

[0059] Furthermore, the number of openings and the size of the openings are designed according to the number of small particles in the solid food waste. For example, the number of micro-hole nozzles can be 4 to 12. Figure 3 As shown, there may be 8 of them, and the diameter may be 0.4 to 1.0 mm, etc. The diameters of the multiple micropore nozzles may be the same or different.

[0060] In addition, in order to prevent the solids sprayed from the micro-hole nozzle from clogging, a high-pressure jet blowing device is also set at the edge of the disc top cover to blow the solids out of the disc, thereby preventing the solids from clogging the disc.

[0061] Figure 1 The schematic diagram shows the process flow of the method for high-value utilization of restaurant kitchen waste in one embodiment of the present invention. The overall process flow of this embodiment is as follows: Figure 1After the food waste is collected, it is sorted into large and fine materials to remove plastic and other debris, which are then transported out for disposal.

[0062] 1) The sorted garbage enters the elution equipment and is eluted with the elution liquid under stirring. The elution liquid comes from the liquid phase after the three-phase oil extraction.

[0063] In this step, the "slurry after three-phase oil extraction" is used to advance the hydrolysis and acidification to the pretreatment stage of the food waste. A large number of hydrolysis and acidification bacteria are accumulated in the slurry after three-phase oil extraction, and the low content of other bacteria will not cause a decrease in acid production due to excessive acid consumption. It can be understood as a targeted cultivation of a group of acid-producing bacteria, which can produce acid to the greatest extent and increase the efficiency of hydrolysis and acidification. For example, in a comparative example of the present application, the slurry after the anaerobic digestion stage is used to perform the above operation. However, the results show that the methanogens and the like present in the slurry after anaerobic digestion will consume the volatile acids produced after hydrolysis and acidification, resulting in a decrease in acid production. Furthermore, the hydrolysis and acidification time in the leaching equipment is controlled at 48h to 60h, for example, 54h. By controlling this time, the garbage can be hydrolyzed and acidified after subsequent separation and three-phase oil extraction.

[0064] Furthermore, the rinsing equipment in this embodiment is equipped with a stirrer installed horizontally inside to simultaneously agitate and propel the garbage. This horizontal arrangement and spraying method ensures that the garbage comes into full contact with the hydrolytic and acidifying bacteria. A rinsing liquid injection device is installed at the top of the rinsing equipment, equipped with a flow controller. The rinsing water flow rate is controlled to be 2 to 4 times the total amount of garbage feed. Multiple nozzles evenly arranged in the rinsing liquid injection device evenly distribute the rinsing liquid over the garbage, ensuring full contact with the hydrolytic and acidifying bacteria.

[0065] In addition, the rinsing device also includes a temperature controller, such as a heating component and a temperature detector, to control and detect the temperature within the rinsing device. Furthermore, the rinsing device temperature is controlled at 30°C to 40°C, specifically 35°C. Furthermore, the pH of the eluent is controlled at 5.5 to 6.0, specifically 5.5. Industrial alkali can be used to adjust the pH.

[0066] Since hydrolysis is the rate-limiting step in the hydrolysis and acidification process, the slurry after three-phase oil extraction allows the garbage to fully contact the hydrolysis and acidification bacteria, and optimizes the elution conditions including temperature, pH environment, time, etc., to further accelerate the hydrolysis of the garbage and complete the hydrolysis during the separation and three-phase oil extraction process, shortening the overall process time. The hydrolysis and acidification stage runs through the elution, separation, and three-phase oil extraction stages and is completed in the above stages, without the need to build a separate hydrolysis tank.

[0067] 2) After being hydrolyzed in the leaching process, the kitchen waste enters the separation screen for solid-liquid separation.

[0068] The separation screen can be composed of three layers of screen mesh. The pore size of the upper layer is 6-10 mm, the middle layer is 2-5 mm, and the bottom layer is 0.3-1 mm. The separation screen can filter out large solid particles. The waste liquid obtained by filtering with the three-layer structure with the above pore sizes meets the feed of the three-phase oil extraction machine, eliminating large particles in the slurry after oil extraction, meeting the elution requirements and facilitating the ammoniation and anaerobic reactions.

[0069] In an optional embodiment, the solid residue can be used as feed for insect farming, such as black soldier flies. The system can also be connected to a high-protein feed preparation device or an organic fertilizer preparation device, allowing the insects to be processed into high-protein feed and the insect feces to be used as organic fertilizer. This embodiment utilizes solid residue to feed insects, not only reducing solid residue disposal costs but also increasing the secondary conversion rate of restaurant kitchen waste, further enhancing the high-value utilization of restaurant kitchen waste.

[0070] 3) The filtrate after separation screen enters the three-phase oil extractor for oil extraction, and the slurry after oil extraction will be divided into three parts for utilization.

[0071] In addition, during the oil extraction process, the waste heat after biogas power generation is used to heat the garbage, saving energy consumption. In order to extract oil more efficiently, the temperature can be controlled at 70-75°C, for example, 72°C, and the refined crude oil can be sold outside. The slurry outlets of the three-phase oil extractor are respectively connected to the leaching equipment, the ammoniation tank and the anaerobic tank. Part of the slurry after oil extraction is transported to the leaching equipment through a pipeline as a leaching liquid. Preferably, the transportation is controlled according to the slurry amount being 2-4 times the amount of garbage, for example, 3 times, so that the garbage can fully contact the hydrolysis and acidification bacteria and accelerate the hydrolysis of the garbage. The remaining slurry is further divided into two parts, namely the first slurry and the second slurry. Preferably, 65% to 75% of the remaining slurry is used as the second slurry and sent to the anaerobic tank, and the rest is the first slurry and sent to the ammoniation tank.

[0072] In this example, 30% of the remaining slurry enters the ammoniation tank, and 70% enters the anaerobic tank. The slurry after oil extraction contains a large amount of VFAs. By sending the majority of the slurry to the anaerobic tank, the anaerobic reaction efficiency and biogas production can be effectively improved. Furthermore, the remaining slurry can be used to produce an organic carbon source after ammoniation and disc separation.

[0073] 4) After oil extraction, the slurry enters the ammonia tank for ammonia reaction, with the temperature controlled at 45-50°C, pH 6.0-6.5, and the hydraulic retention time of the ammonia tank at 2.5-3.5 days, for example, 3 days, to improve the ammonia nitrogen conversion rate.

[0074] Table 1 shows the inlet and outlet water quality of the ammoniation tank in a specific embodiment.

[0075] Table 1 Water quality of inlet and outlet of ammonia tank

[0076] index pH TN (mg / L) <![CDATA[NH3-N(mg / L)]]> COD (mg / L) VFAs (mg / L) Water ingress 5.5-5.8 3000-4500 500-800 110000-180000 25000-35000 Water 6.0-6.5 2500-4000 1400-2300 100000-160000 30000-32000

[0077] As can be seen from Table 1, after the oil-extracted slurry enters the ammoniation tank, the organic nitrogen is converted to ammonia nitrogen through the ammoniation reaction under the above conditions, and the ammonia nitrogen conversion rate is very high, so there is no need for a subsequent membrane treatment process. Moreover, membrane treatment uses a membrane to intercept organic nitrogen, and while the membrane intercepts organic nitrogen, it also intercepts a lot of COD, which will cause COD loss. However, the present invention, by ammoniation-treating the oil-extracted slurry in the ammoniation tank under the above conditions, maximizes the retention of high-quality COD (≥100,000 mg / L), improves the high-value utilization of food waste, and does not need to worry about the degradation of organic nitrogen during the use of the organic carbon source obtained after centrifugation.

[0078] 5) The slurry after the ammoniation treatment is passed into a disc centrifuge and centrifuged. The main parameters of the disc centrifuge are shown in Table 2 below:

[0079] Table 2 Main parameters of disc centrifuge

[0080] project parameter Number of micro-hole nozzles 4 Micropore nozzle diameter 0.4-1.0mm Drum inner diameter Ф420mm Disc outer diameter Ф270mm Disc half cone angle 40° Number of discs 125 Rib form Tilt form Disc clearance 0.5mm Drum speed 5700r / min Separation factor 8000G Design feed pressure Mpa 0.2～0.3 Designed discharge pressure Mpa 0.2～0.6 Motor speed 1450r / min Phase / Frequency / Voltage 3P / 50Hz / 380V

[0081] Table 3 shows the water quality at the inlet and outlet of the disc centrifuge in a specific embodiment.

[0082] Table 3 Inlet and outlet water quality of disc centrifuge

[0083] index TN (mg / L) <![CDATA[NH3-N(mg / L)]]> COD (mg / L) VFAs (mg / L) SS (mg / L) C / N Water ingress 2500-4000 1400-2300 100000-160000 30000-32000 75000-90000 25-40 Water 1600-1800 1000-1200 75000-90000 25000-28000 3000-5500 42-56

[0084] Table 3 shows that after centrifugation using a disc centrifuge, the suspended solids (SS) in the three-phase water dropped to 5500 mg / L or less, largely removed. The carbon-nitrogen ratio (C / N) significantly increased from 25-40 to 42-56, partially removing nitrogen-containing organic matter. The resulting organic carbon source, discharged from the disc centrifuge's organic carbon source outlet, is then subjected to ammoniation and disc separation of the oil-extracted slurry, reducing its organic nitrogen content. This eliminates concerns about organic nitrogen degradation during subsequent use.

[0085] In the present invention, the solid residue outlet of the disc centrifuge is connected to the ammoniation tank and the anaerobic tank, respectively, and part of the solid residue is refluxed to the ammoniation tank, while the rest is sent to the anaerobic tank. Preferably, during reflux, 75% to 85% of the solid residue after centrifugation is refluxed to the ammoniation tank. The effects of partial solid residue reflux are as follows: first, there are a large number of ammonia-forming bacteria in the solid residue, and reflux can continuously enrich the ammonia-forming bacteria, thereby improving the ammoniation rate and ammonia nitrogen conversion rate; second, solid residue reflux can adjust the pH value in the ammoniation tank; third, the optimal pH range of ammonia-forming bacteria is relatively small, so a large amount of solid residue is refluxed to stabilize the pH value, and the solid residue can also provide a small amount of alkalinity.

[0086] In this embodiment, 80% of the solid residue after centrifugation is returned to the ammoniation tank, and the remaining 20% ​​is sent to the anaerobic tank. This solid residue return ratio ensures a good bacterial residence time, while this solid residue discharge ratio prevents the accumulation of toxic substances in the tank, promotes bacterial growth and renewal, and prevents excessive loss of ammoniation bacteria.

[0087] 6) The three-phase water, i.e., the second slurry after oil extraction, is fed into the anaerobic tank along with the remaining solid residue after dishing out. The pH in the anaerobic tank is controlled at 6.6-7.5 and the temperature is maintained at 51-53°C for anaerobic reaction under these conditions. In the present invention, the hydrolysis reaction proceeds throughout the rinsing, separation, and three-phase oil extraction processes. The three-phase water and solid residue have essentially completed hydrolysis and acidification, containing a large amount of volatile organic acids. After being fed into the anaerobic tank together, they can be directly utilized by methanogens, significantly improving the efficiency of the anaerobic reaction and increasing the biogas production rate.

[0088] In addition, if Figure 1 As shown, the system may also include a biogas power generation device connected to the biogas outlet, a biogas purification and biogas production device, a water treatment device connected to the biogas liquid outlet, and a biogas residue fertilizer production device connected to the biogas residue outlet. The biogas liquid after anaerobic treatment is centrifugally dehydrated, and the resulting solid biogas residue can be mixed with insect feces to produce organic fertilizer. After dehydration, the liquid phase undergoes water treatment. The biogas enters the boiler room of the biogas power generation device and is burned to generate electricity. In addition, some of the biogas can be purified to produce biogas. Furthermore, the waste heat from the boiler room is used for heating three-phase oil extraction and can also be used for drying insect pupae during insect farming. By calculating the carbon emission reductions in insect farming, organic carbon source utilization, and biogas power generation, the carbon emission reductions can be traded on the carbon trading market.

[0089] The description of the present invention has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the form disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles of the invention and its practical application and to enable those skilled in the art to understand the invention and design various embodiments with various modifications as are suited for specific applications.

Claims

1. A method for high-value utilization of restaurant kitchen waste, characterized in that: include: The sorted restaurant kitchen waste is sent to a leaching device, and under stirring, the slurry after oil extraction is used as a leaching liquid, and the slurry amount is controlled to be 2 to 4 times the amount of the waste, so that the waste is hydrolyzed and acidified during the leaching process; in the leaching device, the temperature is controlled at 30°C to 40°C, and the pH is controlled at 5.5 to 6.0; the hydrolysis and acidification time in the leaching stage is controlled at 48h to 60h; The leached liquid after washing is sent to the separation screen for filtration; The filtrate after filtering through the separation screen is sent to a three-phase oil extractor for oil extraction, and part of the slurry after oil extraction is sent to the elution equipment as a leaching liquid, 65% to 75% of the remaining slurry is used as the second slurry, and the rest is used as the first slurry; sending the first slurry in the remaining slurry into an amination tank for amination reaction; The ammoniation slurry is sent to a disc centrifuge with a continuous slag discharge function, and the organic carbon source and solid slag are obtained by centrifugation in the disc centrifuge, and part of the solid slag after centrifugation is returned to the ammoniation tank; The second slurry in the remaining slurry and the solid residue remaining after reflux are sent together into an anaerobic tank for anaerobic reaction.

2. The method for high-value utilization of restaurant kitchen waste according to claim 1, characterized in that: 75% to 85% of the solid residue after centrifugation is returned to the ammoniation tank.

3. The method for high-value utilization of restaurant kitchen waste according to any one of claims 1 to 2, characterized in that: During the amination reaction, the temperature is controlled at 45°C to 50°C, the pH is 6.0 to 6.5, and the hydraulic retention time of the amination tank is 2.5 to 3.5 days; And / or, during anaerobic reaction, the temperature is controlled at 51° C. to 53° C. and the pH is controlled at 6.6 to 7.

5.

4. The method for high-value utilization of restaurant kitchen waste according to claim 1, characterized in that: The method further comprises: Part of the biogas after anaerobic treatment is used for combustion and power generation, and the waste heat from the combustion and power generation process is used as an oil extraction heat source to heat the garbage in the three-phase oil extraction machine, with the temperature controlled at 70℃~75℃; Use part of the biogas after anaerobic purification to prepare biogas; The anaerobic biogas slurry is centrifugally dehydrated, the biogas residue after centrifugal dehydration is used to prepare fertilizer, and the liquid phase after centrifugal dehydration is subjected to water treatment.

5. The method for high-value utilization of restaurant kitchen waste according to claim 1, characterized in that: The method further comprises: The solid residue obtained by filtering through a separation screen is used to feed insects; the insects are used to prepare high-protein feed; and the insect feces are used to prepare organic fertilizer; wherein the heat source required in the process of preparing the high-protein feed comes from the waste heat in the process of burning biogas after anaerobic power generation.

6. A system for the method for high-value utilization of restaurant kitchen waste as claimed in any one of claims 1 to 5, characterized in that: It includes sequentially arranged leaching equipment, separation screen, three-phase oil extractor, ammonia tank, disc centrifuge with continuous slag discharge function, and anaerobic tank; among which, The top of the elution equipment is provided with an eluent injection device, an agitator is provided inside, and the inlet of the eluent injection device is connected to the slurry outlet pipeline of the three-phase oil extractor; The separation screen is connected to the outlet of the elution device; The inlet of the three-phase oil extractor is connected to the filtrate outlet of the separation screen, and the slurry outlet of the three-phase oil extractor is respectively connected to the leaching equipment, the ammoniation tank and the anaerobic tank, and the slurry outlet is respectively connected to the leaching equipment, the ammoniation tank and the anaerobic tank. A flow meter is provided on the pipeline; The ammoniation tank is used to receive the slurry sent by the three-phase oil extractor and perform an ammoniation reaction; The disc centrifuge is connected to the outlet of the ammoniation tank, and has an organic carbon source outlet and a solid slag outlet; wherein the solid slag outlet is connected to the ammoniation tank to reflux the solid slag, and the solid slag outlet is also connected to the anaerobic tank; The anaerobic tank is used to receive the slurry conveyed by the three-phase oil extractor and the solid residue conveyed by the disc centrifuge respectively, and perform anaerobic reaction.

7. The system for high-value utilization of restaurant kitchen waste as claimed in claim 6, characterized in that: A reflux controller is provided at the solid slag outlet; The system also includes: a biogas power generation device connected to the biogas outlet of the anaerobic tank, and an insect breeding device connected to the solid residue outlet of the separation screen; wherein the waste heat boiler of the biogas power generation device is connected to the three-phase oil extractor, and is used to heat the slurry in the three-phase oil extractor by using the waste heat; the insect breeding device is used to raise insects using the solid residue as raw material, and the raised insects are used to prepare high-protein feed, and the insect feces are used to make organic fertilizer.

8. The system for high-value utilization of restaurant kitchen waste as claimed in claim 6, characterized in that: The separation screen is composed of three layers of screens, wherein the aperture of the upper layer of the screen is 6mm to 10mm, the aperture of the middle layer is 2mm to 5mm, and the aperture of the bottom layer is 0.3mm to 1mm; And / or, the disc centrifuge has a plurality of micro-pore nozzles spaced around the drum cover, and the micro-pore nozzles are located above the intermittent discharge port.

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