A new type of restaurant kitchen waste treatment process and device

Abstract

The present invention belongs to the technical field of food waste treatment, and specifically relates to a novel food waste treatment process and apparatus. The process comprises: pulping and sorting the food waste to obtain slurry and impurities A (impurities B and coarse residue C); discharging the slurry and impurities B into a wastewater tank; performing solid-liquid separation of the coarse residue C to obtain leachate, which is then discharged into the wastewater tank; discharging wastewater E from the wastewater tank into a desander, undergoing secondary desandering, and obtaining heated slurry; separating the heated slurry to obtain wastewater F, which is then sent to a homogenization tank; partially recirculating the hot liquid from the homogenization tank, and fermenting a portion to obtain fermentation slurry, which is then subjected to solid-liquid separation to obtain a liquid carbon source, which is then sent to a denitrification process. The apparatus used in the process comprises a hydraulic pulper, a press, a wastewater tank, a desander, a desander, a three-phase centrifuge, a homogenization tank, a carbon source preparation tank, and an inclined plate sedimentation tank. The present invention is suitable for small-scale food waste treatment projects, operates stably, and can effectively treat byproducts.

Description

Technical Field

[0001] The present invention belongs to the technical field of restaurant and kitchen waste treatment, and in particular relates to a novel restaurant and kitchen waste treatment process and device. Background Art

[0002] Depending on its source, food waste can be divided into catering waste and kitchen waste. The former, which originates from leftovers from restaurants, canteens, and other catering establishments, is characterized by high production volume, a wide variety of sources, high organic matter content, and a relatively high oil content. The latter, which primarily consists of household scraps discarded from daily cooking, is not as large as catering waste. However, with growing awareness of waste separation among residents and the promotion of relevant policies, the production of kitchen waste is increasing. Due to limited capacity at municipal landfills, many regions restrict the entry of food waste into these facilities. Direct incineration of municipal waste at incineration plants results in low organic matter utilization. Furthermore, the high moisture content of food waste results in significant fluctuations in calorific value, hindering stable boiler operation and control. In this context, there is an urgent need for small-scale food waste treatment projects capable of processing 20-50 tons / day. Currently, the more mature food waste treatment processes include crushing, pulping, separation, pretreatment, anaerobic units, and biogas slurry treatment, resulting in lengthy and complex process chains.

[0003] On the other hand, as my country's sewage treatment plant discharge standards have tightened, the issue of excessive total nitrogen has received increasing attention. Currently, most sewage treatment plants primarily utilize biological denitrification processes, where denitrification requires organic matter (carbon sources) as electron donors. However, many projects are limited by production processes, resulting in a severe imbalance in the C / N ratio of wastewater between 1:1 and 3:1. To meet the operational requirements of biological denitrification, additional carbon sources (such as methanol, sodium acetate, glucose, glycerol, and composite carbon sources) are required. This increases process steps and hinders recycling.

[0004] Many researchers have conducted experiments using food waste fermentation to produce carbon sources under sealed anaerobic conditions. However, during the anaerobic acid production process, methanogens produce methane, resulting in low organic acid production and high system pH, which requires the addition of acid for regulation.

[0005] At present, many improvements have been made in this regard in the patent literature, but there are still some problems:

[0006] (1) Patent application with publication number CN112626139A: Method and device for producing carbon source from kitchen waste. The fermentation pathway is difficult to control and there is a lack of effective measures to inhibit methanogenic activity, which makes organic acids easy to be used for methane production. The lactic acid bacteria culture process is complicated and the engineering utilization and promotion are difficult.

[0007] (2) Patent publication number CN111333179B: A method for denitrifying carbon sources from wastewater by lactic acid fermentation of food waste: The prepared carbon source separation equipment is difficult to operate and is not suitable for small-scale food waste treatment projects.

[0008] (3) Patent application with publication number CN114890630A: A process and apparatus for treating wastewater by using food wastewater as a carbon source and mixing it with leachate: Carbohydrates, proteins and other macromolecular substances in food wastewater require a long oxidation time to be decomposed into small molecular dissolved organic matter so that microorganisms in the wastewater can effectively utilize them.

[0009] (4) Patent application with publication number CN103834560A: An acid-producing fermentation tank for processing food waste to generate carbon sources: it is necessary to adjust the acid and alkali at the same time, the operation control is difficult, and the fermented slurry requires high-precision separation equipment to achieve effective separation.

[0010] Therefore, in order to solve this situation, it is necessary to adopt a treatment process and equipment that is suitable for small-scale food waste treatment projects, has stable operation, and can resource-based by-products. Summary of the Invention

[0011] The first object of the present invention is to provide a novel restaurant kitchen waste treatment process, which is suitable for small-scale restaurant kitchen waste treatment projects, has stable operation, and can effectively treat by-products.

[0012] A new method for treating kitchen waste includes the following steps:

[0013] S1 pulping and sorting: The food waste is transported to a hydraulic pulping machine for pulping and sorting to obtain a slurry and impurities A, wherein the impurities A include impurities B and coarse residue C;

[0014] S2. The slurry and the impurities B are discharged from the hydraulic pulping machine into the wastewater tank;

[0015] S3. The coarse residue C is discharged from the hydraulic pulping machine into the press for solid-liquid separation to obtain leachate and coarse residue D, the leachate is discharged into the wastewater tank, the coarse residue D is transported for disposal;

[0016] S4. The wastewater in the wastewater tank E is discharged into the desander to obtain coarse sand and slurry after desanding, and the coarse sand is transported for disposal,

[0017] Wherein, the wastewater E includes at least one of the slurry, the impurities B, and the leachate;

[0018] S5. The slurry after desanding is sent to the desander for secondary desanding to obtain a heated slurry and fine sand, and the fine sand is discharged into a storage tank;

[0019] S6. The heated slurry is sent to a three-phase centrifuge for separation to obtain grease, solid residue, and wastewater F. The grease is sent to an external grease storage tank, the solid residue is sent to an external breeding equipment, the solid residue is solid waste, and the wastewater F is sent to a homogenization tank for temporary storage;

[0020] S7. The hot liquid in the homogenization tank is returned to the hydraulic pulper, the hot liquid is part of the wastewater F, and the remaining wastewater F is sent to the carbon source preparation tank for fermentation to obtain a fermentation slurry;

[0021] S8. Discharging the fermentation slurry into an inclined plate sedimentation tank for solid-liquid separation to remove surface suspended matter, thereby obtaining a liquid carbon source, sludge, and scum. The sludge includes bottom sludge and non-bottom sludge. The bottom sludge is internally returned from the inclined plate sedimentation tank to the carbon source preparation tank, while the scum and non-bottom sludge are externally returned from the inclined plate sedimentation tank to the hydraulic pulper.

[0022] S9. sending the liquid carbon source to a denitrification process.

[0023] The above technical solution addresses the long process chains and complex biogas slurry treatment of existing food waste treatment projects. Small-scale food waste treatment projects, in particular, have extremely low biogas utilization rates. Most projects employ PPP or BOT models, complicating urban health management. The present invention utilizes pretreatment followed by hydrolysis and fermentation to produce a carbon source, shortening the process chain, requiring fewer steps and equipment, eliminating the need for additional biogas slurry treatment, and generating a value-added carbon source product, potentially making food waste treatment projects profitable.

[0024] Another object of the present application is to provide a novel food waste treatment device according to the above, which is used in the novel food waste treatment process. The device includes a hydraulic pulper, a wastewater tank, a sand remover, a desander, a three-phase centrifuge, a homogenization tank, a carbon source preparation box, and an inclined plate sedimentation tank connected in sequence by pipelines; a press is connected in parallel between the hydraulic pulper and the wastewater tank.

[0025] Preferably, the hydraulic pulping machine includes a filtering device 1, which has a filter plate inside. The filtering device 1 is used to filter the slurry and the impurity A, and separate the impurity A into impurity B and coarse residue C, the particle size of the impurity B is smaller than the mesh diameter of the filter plate, and the coarse residue C is unbroken matter and matter with a particle size exceeding the mesh diameter of the filter plate; the hydraulic pulping machine also includes a water outlet, which is connected to the wastewater tank through a pipe 1; the hydraulic pulping machine also includes a water inlet.

[0026] Preferably, the hydraulic pulping machine is connected to a screw conveyor via a second pipeline, the second pipeline is located on the upper side of the first filtering device, and the second pipeline is used to convey the coarse residue C; the screw conveyor is connected to the press via a third pipeline, and the press is used to press and separate the coarse residue C;

[0027] The press includes a second filtering device, wherein a screen is provided in the second filtering device, and the screen is used for filtering and separating the leachate and the coarse residue D.

[0028] Preferably, the press is connected to the wastewater tank via pipeline nine, the wastewater tank is connected to the desander via pipeline four, and the desander is connected to the desander via pipeline five.

[0029] Preferably, the desander includes an agitator, which is used to stir the desandered slurry. The desander is provided with an electromagnetic induction heating coil connected in parallel or in series, and the electromagnetic induction heating coil is used to heat the desandered slurry, with a heating temperature of 80°C to 100°C and a heating time of 30min to 45min.

[0030] Using the above technical solution, existing methods for heating food waste slurry often use biogas boilers or electric heating boilers, and the heated steam is directly injected for heating. This method has a heat utilization rate of 50% to 60%, which is low. It often requires equipment such as water softening devices and steam boilers, resulting in a long process chain, complex operation, high investment and operating costs, and significant safety risks. The present invention uses electromagnetic induction heating coils and desanders to directly heat the slurry. The electromagnetic induction heating coils can generate an alternating magnetic field through a high-frequency alternating current. The desander rotates internally to cut the alternating magnetic lines of force, generating alternating currents (eddy currents) internally. The eddy currents cause the atoms within the slurry to move at high speed and irregularly, reducing the investment in the steam boiler system and achieving a heat utilization rate of over 95%. This not only reduces equipment investment costs, but also simplifies the process flow, reducing operating costs by over 40%, and avoiding the 8% to 10% additional wastewater treatment required in the pretreatment process.

[0031] Preferably, the desander is connected to a three-phase centrifuge via a pipeline 6, the three-phase centrifuge comprises a solid residue outlet, a grease outlet, and a wastewater outlet, and the three-phase centrifuge is used to centrifuge the heated slurry;

[0032] The solid residue outlet is connected to external breeding equipment, the grease outlet is connected to an external grease storage tank, and the wastewater outlet is connected to the homogenization tank.

[0033] Preferably, the homogenization tank is connected to the water inlet via a reflux pipe 1, and the reflux pipe 1 is used for hot liquid reflux.

[0034] Preferably, the homogenization tank is connected to the carbon source preparation box through pipe eight, and the carbon source preparation box includes grid A and grid B, an overflow port is provided between grid A and grid B, an aeration pipe or aeration plate for aeration is provided at the bottom of the carbon source preparation box, and grid A is connected to a sludge return pipe.

[0035] Conventional carbon source preparation using the aforementioned technical solution, which employs composite bacterial inoculation or fermentation tanks to produce organic acids, is difficult to inhibit under strictly anaerobic conditions. Some organic acids are then used by methanogens to produce methane, resulting in low organic acid concentrations in the carbon source. However, the present invention utilizes aeration conditions where the ORP is greater than -250 mV, exceeding the minimum activation level of -300 mV for methanogens. This effectively inhibits methanogenic activity and achieves efficient accumulation of organic acids in the system.

[0036] Preferably, the sludge return pipe is connected to the inclined plate sedimentation tank through a sludge discharge return pipe, the sludge discharge return pipe and the sludge return pipe are used to internally reflux the sludge at the bottom, a scraper is provided on the upper part of the inclined plate sedimentation tank, the scraper is used to remove suspended matter on the surface of the fermentation slurry, the inclined plate sedimentation tank is also connected to the return pipe 2, and the return pipe 2 is used to externally reflux the scum and the non-bottom sludge.

[0037] The above technical solution typically utilizes pre-treated food waste slurry for hydrolysis and fermentation under an anaerobic environment to produce organic acids. This results in poor slurry sedimentation, necessitating the use of high-speed centrifugation equipment or filter presses, which increases equipment investment costs. The present invention utilizes hydrolysis and fermentation in an aerated environment to produce high concentrations of organic acids, resulting in excellent sludge settling performance. Using a mature sludge sedimentation tank, it achieves both solid-liquid separation and simple equipment, resulting in low operating costs and a high-quality carbon source.

[0038] The beneficial effects of the present invention are:

[0039] First, the patented system uses the hot liquid slurry (wastewater F) from the three-phase centrifuge to recirculate the sludge from the homogenization tank and inclined plate sedimentation tank for washing and slurry conditioning. The hot liquid from the three-phase centrifuge dissolves the oil and fat condensed on the surface of the food waste solids in the hydraulic pulper, flushing it into the liquid phase and improving the system's oil extraction rate. Furthermore, because the solids content of the three-phase centrifuge wastewater F is between 8% and 10%, and the solids content of the return sludge is less than 2%, significantly lower than the 12% to 15% solids content of the initial food waste slurry, slurry conditioning is achieved on the food waste pulped material, maintaining a stable solids content of 10% to 12% in the incoming slurry, which facilitates the stable operation of the three-phase centrifuge.

[0040] Second, existing methods for heating food waste slurry often use biogas boilers or electric boilers, with the heated steam directly injected for heating. This method has a low heat utilization rate of 50% to 60%. It often requires a tap water softening device, a steam boiler, a heat exchanger, and other equipment. This results in a long process chain, complex operations, high investment and operating costs, and significant safety risks. The present invention uses electromagnetic induction heating coils and a desander to directly heat the slurry. The heating equipment is integrated with the desander. Taking advantage of the low viscosity of the heated slurry, the centrifugal force of the agitator and the stratification effect of the upwelling hot steam achieve solid-liquid separation of grit and slurry. The desander eliminates the need for external steam for heating. The electromagnetic induction heating coil generates an alternating magnetic field through a high-frequency alternating current. The desander rotates internally, cutting through the alternating magnetic field lines, generating alternating currents (eddy currents). These eddy currents cause atoms within the slurry to move at high speeds and in a random manner, reducing the investment required for a steam heating boiler system. The thermal utilization rate of electromagnetic induction heating is over 95%. Compared with conventional electric heating or biogas boiler heating, it simplifies the process flow, which reduces equipment investment costs and operating costs by more than 40%. At the same time, it avoids the pretreatment process and the 8% to 10% treatment volume of sewage.

[0041] Third, compared with the existing food waste treatment process that requires an additional water volume of 20% to 30% of the food waste treatment volume, the food waste treatment process of the present invention controls the additional water volume to 3% to 5% of the food waste treatment volume, and the additional water volume is mainly equipment washing water and vehicle washing water.

[0042] Fourth, the present food waste treatment process eliminates the need for anaerobic digestion and biogas slurry treatment systems, and produces a value-added organic carbon source (liquid carbon source), significantly reducing process steps and lowering the investment and operating costs of food waste projects. The present process requires minimal water input, resulting in a low biogas slurry volume. Wastewater F from the three-phase centrifuge is used in the carbon source preparation tank and inclined plate sedimentation tank to produce an organic carbon source. After sedimentation and separation, the liquid carbon source can be sold to a sewage treatment plant for denitrification in the denitrification stage, i.e., a sewage treatment denitrification unit. The solid phase (solid residue) from the three-phase centrifuge is high in protein and carbohydrates and can be used in aquaculture equipment.

[0043] Fifth, the present invention utilizes food waste fermentation to produce a carbon source under aerated conditions (in a carbon source preparation box), which can effectively inhibit methanogenesis, promote the accumulation of organic acids during the fermentation process, and increase the proportion of organic matter (carbon source) in the system clear liquid. However, existing anaerobic fermentation processes are often accompanied by anaerobic digestion processes, which induce methane production and alkalinity in the system, resulting in a high pH. External acid solution is required to adjust the pH of the system to maintain stable operation.

[0044] Sixth, the present invention utilizes an inclined plate sedimentation tank for solid-liquid separation of the fermentation slurry, resulting in low SS (superoxide dismutase) (SS) in the clear water after separation. By using an aerated environment for fermentation and acid production, the SV30 of the acclimated sludge is less than 40%, demonstrating excellent settling performance. The clear water after sedimentation separation achieves SS of 1000 mg / L. This clear water serves as a supplemental carbon source for the denitrification stage of wastewater treatment. This invention eliminates the need for a high-speed centrifuge and avoids the addition of flocculants that could affect the quality of the finished carbon source, reducing both the investment and operating costs of the centrifuge.

[0045] In summary, the present invention is suitable for small-scale food waste treatment projects, has stable operation, and can effectively treat by-products. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0047] Figure 1 It is a schematic diagram of the process flow of the present invention;

[0048] Figure 2 It is a schematic diagram of the overall structure of the device of the present invention;

[0049] The markings in the figure are: 1. Hydraulic pulper; 2. Filter device 1; 3. Water inlet; 4. Water outlet; 5. Pipeline 1; 6. Pipeline 2; 7. Screw conveyor; 8. Pipeline 3; 9. Press; 10. Filter device 2; 11. Wastewater tank; 12. Pipeline 4; 13. Desander; 14. Pipeline 5; 15. Desander; 16. Agitator; 17. Pipeline 6; 18. Three-phase centrifuge; 20. Solid residue outlet; 21. Grease outlet; 22. Wastewater outlet; 23. Pipeline 7; 24. Homogenization tank; 25. Pipeline 8; 26. Carbon source preparation box; 27. Grid A; 28. Grid B; 29. ​​Overflow; 30. Sludge return pipe; 31. Inclined plate sedimentation tank; 32. Sludge return pipe; 33. Sludge scraper; 34. Return pipe 1; 35. Return pipe 2; 36. Pipeline 9; 37. Pipeline 10. DETAILED DESCRIPTION

[0050] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0051] Unless otherwise specified, the equipment and materials used in the examples can be easily obtained from commercial companies:

[0052] Example 1

[0053] like Figure 1 and Figure 2 As shown, a new type of restaurant kitchen waste treatment process and device,

[0054] The process includes the following steps,

[0055] S1 pulping and sorting: The food waste is transported to a hydraulic pulping machine 1 for pulping and sorting to obtain a slurry and impurities A, impurities A includes impurities B and coarse residue C;

[0056] S2. The slurry and impurities B are discharged from the hydraulic pulping machine 1 into the wastewater tank 11;

[0057] S3. The coarse residue C is discharged from the hydraulic pulping machine 1 into the press 9 for solid-liquid separation to obtain leachate and coarse residue D, the leachate is discharged into the wastewater tank 11, the coarse residue D is transported for disposal;

[0058] S4. The wastewater in the wastewater tank 11 is discharged into the desander 13 to obtain coarse sand and slurry after desanding, and the coarse sand is transported for disposal, wherein the wastewater E includes a slurry, impurities B, and leachate;

[0059] S5. The slurry after desanding is sent to the desander 15 for secondary desanding to obtain the heated slurry and fine sand, and the fine sand is discharged into the storage tank;

[0060] S6. The heated slurry is sent to a three-phase centrifuge 18 for separation to obtain grease, solid residue, and wastewater F. The grease is sent to an external grease storage tank, and the solid residue is sent to an external breeding equipment, preferably a breeding equipment for black soldier flies incubators, the solid residue is solid waste, and the wastewater F is sent to the homogenization tank 24 for temporary storage;

[0061] S7. The hot liquid in the homogenization tank 24 is returned to the hydraulic pulper 1, the hot liquid is a portion of the wastewater F, and the remaining wastewater F is sent to the carbon source preparation tank 26 for fermentation to obtain a fermentation slurry;

[0062] S8. The fermentation slurry is discharged into the inclined plate sedimentation tank 31 for solid-liquid separation to remove surface suspended matter to obtain a liquid carbon source, sludge and scum. The sludge includes sludge at the bottom and sludge at the non-bottom. The sludge at the bottom is returned from the inclined plate sedimentation tank 31 to the carbon source preparation tank 26, and the scum and sludge at the non-bottom are returned from the inclined plate sedimentation tank 31 to the hydraulic pulper 1.

[0063] S9. Send the liquid carbon source to an external denitrification process.

[0064] The device is used in the above process and comprises a hydraulic pulping machine 1 .

[0065] The hydraulic pulping machine 1 is preferably a hydraulic vortex pulping and sorting machine. As is known, the hydraulic pulping machine 1 includes a rotor, which is used to rotate to generate a vortex in the hydraulic pulping machine 1 to sort the food waste. The hydraulic pulping machine 1 also includes a heating device, which is a steam heater or a jacket heater. The heating device is used to heat the food waste, accelerate the dissolution of animal fat in the food waste, improve the oil extraction rate of the entire device, improve the impurity removal rate of the food waste, and improve the overall performance of the device in treating waste. The hydraulic pulping machine 1 is also equipped with a filter device 2 on the lower side. The filter device 2 contains a filter plate, and the mesh diameter of the filter plate is preferably 6mm. The filter device 2 is used to filter the slurry and impurities A, impurities B are substances with a particle size not exceeding 6mm, and coarse residue C is unbroken substances and substances with a particle size exceeding 6mm.

[0066] The hydraulic pulping machine 1 has a water outlet 4 at the bottom, which is connected to the wastewater tank 11 through a pipe 5; the hydraulic pulping machine 1 has a water inlet 3 at the top.

[0067] The hydraulic pulping machine 1 is connected to the screw conveyor 7 via the second pipe 6. The second pipe 6 is located on the upper side of the filter device 2. The second pipe 6 is used to convey the coarse residue C. The outlet of the screw conveyor 7 is connected to the press 9 via the third pipe 8. The press 9 is used to press and separate the coarse residue C.

[0068] A second filter device 10 is installed at the bottom of the press 9. A screen is provided inside the second filter device 10 for filtering and separating the leachate and the coarse residue D.

[0069] The press 9 is connected to the wastewater tank 11 through a pipe 9 36. The press 9 is also connected to a hydraulic control system (not shown in the figure). The hydraulic control system can control and adjust the discharge rate of the leachate and coarse slag D in real time through back pressure control to control the moisture content of the leachate to not exceed 65%.

[0070] The wastewater pool 11 is connected to the desander 13 through the pipe 12. The desander 13 is used to remove heavy materials (including shells, glass, porcelain pieces, sand and gravel, etc.) in the wastewater E. The specific gravity of heavy materials is greater than 2000kg / m 3 , prevent heavy substances from damaging subsequent equipment (including pipeline six 17 and three-phase centrifuge 18), and can reduce the sand settling inside the carbon source preparation box 26 during fermentation and remove particles that affect fermentation.

[0071] Desander 13 is connected to desander 15 via pipeline 5 14. Desander 15 is conical in shape and is used for secondary desandering, minimizing damage to three-phase centrifuge 18 and pipeline 6 17. A vertical agitator 16 is installed within desander 15, preferably with blades inclined at 45°. Agitator 16 is used to stir the desandered slurry. Electromagnetic induction heating coils are connected in parallel or in series within desander 15. These coils include an AC rectifier, a medium-frequency or high-frequency power converter, and an induction coil.

[0072] The electromagnetic induction heating coil is used to heat the slurry after desanding. The heating temperature is 80℃~100℃ and the heating time is 30min~45min. Heating can extract and dissolve the floating oil, dispersed oil and emulsified oil in the slurry from the water phase of the slurry, thereby improving the oil extraction rate and heat utilization rate. The heat utilization rate can reach more than 95%, and the kinematic viscosity of the slurry can be reduced by more than 80%. There is an electromagnetically controlled knife gate valve at the bottom of the desander 15, which controls the outflow rate of the heated slurry.

[0073] The electromagnetically controlled knife gate valve is connected to the three-phase centrifuge 18 through a pipe six 17. Preferably, the three-phase centrifuge 18 is a horizontal spiral centrifuge, which is used to centrifuge the heated slurry; the three-phase centrifuge 18 has a solid residue outlet 20, a grease outlet 21, and a wastewater outlet 22 at the bottom. The solid residue outlet 20 is connected to an external breeding equipment, preferably a black soldier fly incubator, the grease outlet 21 is connected to an external grease storage tank, and the grease in the grease storage tank can be sold later. The wastewater outlet 22 is connected to the homogenization tank 24 through a pipe seven 23. The moisture content of the solid residue obtained by the three-phase centrifuge 18 is ≤80%, the solid content (TS) of the wastewater F is 8~10%, the oil content in the aqueous phase of the wastewater F is ≤0.5%, and the grease-water impurity ratio is ≤3%.

[0074] The homogenizing tank 24 is connected to the water inlet 3 of the hydraulic pulping machine 1 through a return pipe 34, and the return pipe 34 is used for hot liquid return.

[0075] The homogenization tank 24 is also connected to the carbon source preparation box 26 through a pipe 8 25. Preferably, the carbon source preparation box 26 is a fermentation tank. The carbon source preparation box 26 includes a grid A 27 and a grid B 28. An overflow port 29 is provided between the grid A 27 and the grid B 28. When blocked, the overflow port 29 is used to discharge the wastewater F. An aeration pipe or an aeration disk for aeration is provided at the bottom of the carbon source preparation box 26. The grid A 27 is connected to the sludge return pipe 30.

[0076] Carbon source preparation tank 26 contains post-bacterial sludge. This post-bacterial sludge is obtained from municipal sludge and then inoculated and inoculated. Before use, carbon source preparation tank 26 is air-dried for three days to activate the microbial activity in the sludge. After entering carbon source preparation tank 26, wastewater F sequentially flows from compartment A to compartment B. The temperature of carbon source preparation tank 26 is controlled at 37-42°C, and the residence time is 3-6 days. The dissolved oxygen in compartment A 27 is 0-1.0 mg / L, and in compartment B 0-0.5 mg / L. The ORP is -250 mV to -100 mV, and the pH is 5.5-6.0. The post-bacterial sludge concentration in carbon source preparation tank 26 is 14-19 g / L. Alkaline solution is used to automatically adjust the pH in carbon source preparation tank 26. Aeration volume and time are automatically controlled based on dissolved oxygen and ORP. Aeration tubes or aeration plates can be used for intermittent or continuous aeration.

[0077] The sludge return pipe 30 is connected to the inclined plate sedimentation tank 31 through the sludge return pipe 32 at the bottom of the inclined plate sedimentation tank 31. A scraper 33 is provided on the upper part of the inclined plate sedimentation tank 31. The scraper 33 is used to remove suspended matter on the surface of the fermentation slurry. Among them, the sludge return pipe 32 and the sludge return pipe 30 are used for internal recirculation of the sludge at the bottom; the inclined plate sedimentation tank 31 is also connected to the return pipe 2 35, which is used for external recirculation of scum and sludge not at the bottom.

[0078] The inclined plate sedimentation tank 31 is also connected to an external denitrification process.

[0079] The novel kitchen waste treatment device proposed in this application, combined with the treatment process, works as follows:

[0080] S1. Pulping and Sorting: Food waste is transported to a hydraulic pulper 1 for pulping and sorting. Liquid is introduced into the hydraulic pulper 1 through a water inlet 3. The high-speed rotation of the rotor causes the materials (food waste) to rub against each other, simultaneously washing organic matter from the packaging and fibers of the food waste away by the liquid flow. The waste is then filtered through a filter layer device 2 to produce a slurry and impurities A, which include impurities B and coarse residue C. Impurities B and the slurry are discharged through a pipe 5 into a wastewater tank 11.

[0081] The coarse slag C enters the screw conveyor 7 from the second pipe 6, and then enters the press 9 from the screw conveyor 7 through the third pipe 8 for squeezing and separation, and then passes through the second filter device 10 for filtration and separation to obtain leachate and coarse slag D. The leachate enters the wastewater pool 11 from the ninth pipe 36, and the coarse slag D is transported out for disposal.

[0082] The wastewater (including slurry, impurities B, and leachate) in the wastewater tank 11 is discharged from the pipeline 4 12 into the desander 13 to obtain coarse sand and desanded slurry. The coarse sand is transported out for disposal, and the desanded slurry is discharged into the desander 15 through the pipeline 5 14. In the desander 15, it is stirred by the stirrer 16 and heated by the electromagnetic induction heating coil to obtain heated slurry.

[0083] The heated slurry is discharged into the three-phase centrifuge 18 through the pipe six 17, and is separated into three phases by the three-phase centrifuge 18 to obtain grease, solid residue, and wastewater F. The solid residue is solid waste. The grease is sent to the external grease storage tank from the grease outlet 21, and the solid residue is sent to the external black soldier fly incubator from the solid residue outlet 20. The wastewater F is sent to the homogenization tank 24 from the pipe seven 23 for temporary storage.

[0084] The hot liquid (a portion of the wastewater F) in the homogenization tank 24 is returned to the water inlet 3 through the reflux conduit 1 34, and the remaining wastewater F is sent to the carbon source preparation tank 26 through the pipeline 8 25 for fermentation. The wastewater F passes through the A grid 27 and the B grid 28 in sequence, and is simultaneously aerated by the aeration pipe or aeration disk to obtain a fermentation slurry.

[0085] The fermentation slurry flowing out of cell B enters the inclined plate sedimentation tank 31 from the pipe 10 37, undergoes solid-liquid separation in the inclined plate sedimentation tank, and the scraper 33 regularly removes suspended matter on the surface of the fermentation slurry to obtain liquid carbon source, sludge and scum. The sludge includes bottom sludge and non-bottom sludge. The bottom sludge is returned to the carbon source preparation box 26 from the sludge return pipe 32 and the sludge return pipe 30, and the scum and non-bottom sludge are returned to the hydraulic pulping machine 1 from the outside of the return pipe 2 35, avoiding the need to add a process chain to additionally process the scum, and also saving energy and protecting the environment. Then, it is discharged to the outside through the hydraulic pulping machine 1, and the liquid carbon source is sent to the external denitrification and denitrification process to be used as the carbon source for the external denitrification and denitrification process.

[0086] Example 2

[0087] A novel process and device for treating food waste is provided, which differs from Example 1 in the following aspects, and the remaining aspects are the same as those of Example 1:

[0088] When the solid content of wastewater F is 8~10%, it enters the carbon source preparation box 26. The temperature of the carbon source preparation box 26 is controlled at 37~42°C, the residence time is 3 days, the dissolved oxygen in cell A is 0~1.0 mg / L, the dissolved oxygen in cell B is 0~0.5 mg / L, the ORP is -250mv~-100mv, the pH is 5.5~6.0, and the sludge concentration after bacterialization in the carbon source preparation box is 14~19 g / L. An acid-base pH adjustment and dosing device system is used in the carbon source preparation box 26. The aeration volume and time are automatically controlled according to the dissolved oxygen and ORP. The aeration mode of the aeration pipe or aeration plate is intermittent aeration or continuous aeration. In the fermentation slurry: the COD concentration in the supernatant reaches 100g / L, the total organic acid reaches 30g / L, the COD / TN is 77~110, and the NH3 / TN is 80%~85%. After the fermentation slurry enters the inclined plate sedimentation tank, the outlet SS does not exceed 6000mg / L.

[0089] Example 3

[0090] A novel process and device for treating food waste is provided, which differs from Example 1 in the following aspects, and the remaining aspects are the same as those of Example 1:

[0091] When the solid content of wastewater F is 8~10%, it enters the carbon source preparation box 26. The temperature of the carbon source preparation box 26 is controlled at 37~42°C, the residence time is 4 days, the dissolved oxygen in cell A is 0~1.0 mg / L, the dissolved oxygen in cell B is 0~0.5 mg / L, the ORP is -250mv~-100mv, the pH is 5.5~6.0, and the sludge concentration after bacterialization in the carbon source preparation box 26 is 14~19 g / L. Anaerobic digestion liquid is used to adjust the pH in the carbon source preparation box 26. The solid content of the anaerobic digestion liquid does not exceed 2%. The addition ratio of the anaerobic digestion liquid to the wastewater F is 2:1~3:1. The aeration volume and time are automatically controlled according to the dissolved oxygen and ORP. The aeration mode of the aeration pipe or aeration plate is intermittent aeration or continuous aeration. In the fermentation slurry: the COD concentration in the supernatant reaches 47g / L, the total organic acid reaches 21g / L, the COD / TN is 20~25, and the NH3 / TN is 80%~85%. After the fermentation slurry enters the inclined plate sedimentation tank, the outlet SS does not exceed 1000~3000mg / L.

[0092] Comparative Example 1

[0093] A process for treating kitchen waste comprises the following steps:

[0094] The kitchen waste is transported to a hydraulic pulper 1 for pulping and separation to obtain pulp and impurities A, wherein the impurities A include impurities B and coarse residue C;

[0095] The food waste was fed to a hydrolysis reactor with a stirring device installed inside. The residence time was no more than three days. The pH of the reactor on the hydrolysis reactor was 4.0-4.5, resulting in a slurry. The slurry was discharged and observed to show no obvious stratification. The slurry was then discharged into a centrifuge for solid-liquid separation at a speed exceeding 2000 r / min to obtain a clear liquid. The clear liquid contained COD of 60-80 g / L, total organic acid of 6-10 g / L, SS of 30,000-40,000 mg / L, NH3 of 400-800 mg / L, NH3 / TN of 20%-40%, and TP of 200-400 mg / L.

[0096] The clear liquid is sent to the external denitrification process. The final wastewater effluent TN of this process is 100~200mg / L and TP is 20~40mg / L.

[0097] Testing: The added carbon source on the market was used as Comparative Example 2. The liquid carbon source of the present application (Examples 1-3) and the added carbon source on the market (food-grade glucose) were added to the external denitrification and denitrification process, and the denitrification and phosphorus removal effects of the effluent quality of Examples 1-3 and Comparative Examples 1-2 were tested. The dissolved oxygen in the nitrification tank of the denitrification and denitrification process was controlled to 2 mg / L, and the nitrification liquid reflux ratio was 10-20. The test results are shown in Table 1 below:

[0098] Table 1

[0099]

[0100] The test values ​​in this application are based on the following standards:

[0101] (1) Chemical oxygen demand test standard: HJ 828-2017 Determination of chemical oxygen demand in water - Dichromate method;

[0102] (2) Ammonia nitrogen detection standard: HJ 535-2009 Water quality - Determination of ammonia nitrogen - Nessler's reagent spectrophotometric method;

[0103] (3) Total nitrogen detection standard: HJ 636-2012 Water quality - Determination of total nitrogen - Alkaline potassium persulfate digestion - UV spectrophotometry;

[0104] (4) Total phosphorus testing standard: GB 11893-89 Water quality—Determination of total phosphorus—Ammonium molybdate spectrophotometric method;

[0105] (5) Organic acid (VFA) test standard: DB34T 2499-2015 Determination of volatile fatty acids in liquor industry wastewater - Acidification distillation titration method;

[0106] (6) SS testing standard: GB / T 11901-1989 Determination of suspended solids in water by gravimetric method

[0107] (7) MLSS test standard: GB / T 11901-1989 Determination of suspended solids in water by gravimetric method

[0108] The abbreviations used in this application are commonly used abbreviations in sewage treatment, as follows:

[0109] (1) SS: suspended solids

[0110] (2) TN: total nitrogen

[0111] (3) TP: total phosphorus

[0112] (4) COD: Chemical oxygen demand

[0113] (5) MLSS: sludge concentration

[0114] (6) C / N: carbon-nitrogen ratio

[0115] (7) ORP: Oxidation-reduction potential.

[0116] Result analysis: It can be seen from Comparative Example 1 and Examples 1 to 3 that the TN of Comparative Example 1 can reach 8 times that of the present application, the TP can reach 3 times that of the present application, and the pH value cannot reach 7.0 to 7.5; and it is clearly known that the C / N ratio of high-concentration sewage is low. In order to achieve the effluent meeting the urban pipe standard, Examples 1 to 3 can achieve denitrification and phosphorus removal effects by adding an external carbon source, and can also effectively treat the by-products in the process of the present application. In addition, the present application does not require the preparation of a high-speed centrifuge, and can also avoid the addition of flocculants, which affects the quality of the finished carbon source, reduces the process, and reduces the difficulty of operation. It can be seen from Comparative Example 2 and Examples 1 to 3 that the C / N value of denitrification and phosphorus removal using the liquid carbon source of the present application is lower than that of glucose, that is, C / N=5:1, the C / N difference between Comparative Example 2 and the present application can reach 2, the TP of Comparative Example 2 can reach 2 times that of the present application, and the MLSS value can reach 2 times that of the present application. When the dissolved oxygen controlled in the nitrification tank is 2 mg / L and the nitrification liquid reflux ratio is 10 to 20, combined with the process and apparatus of the present application, the total nitrogen and total phosphorus in the effluent can meet the standards, and the sludge production in the sewage system is lower.

[0117] Therefore, the present invention has fewer steps, is suitable for small-scale kitchen waste treatment projects, has stable operation, has low operating difficulty, and can effectively treat by-products.

[0118] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A process for treating kitchen waste, characterized in that: The following steps are included: S1. Pulping and sorting: The food waste is transported to a hydraulic pulping machine (1) for pulping and sorting to obtain a slurry and impurities A, wherein the impurities A include impurities B and coarse residue C; S2. discharging the slurry and the impurities B from the hydraulic pulping machine (1) into a wastewater tank; S3. The coarse residue C is discharged from the hydraulic pulper (1) into a press (9) for solid-liquid separation to obtain leachate and coarse residue D, the leachate is discharged into the wastewater tank (11), and the coarse residue D is transported for disposal; S4. The wastewater E in the wastewater tank (11) is discharged into the desander (13) to obtain coarse sand and slurry after desanding, and the coarse sand is transported for disposal. Wherein, the wastewater E includes at least one of the slurry, the impurities B, and the leachate; S5. The desandered slurry is sent to a desander (15) for secondary desandering to obtain heated slurry and fine sand, and the fine sand is discharged into a storage tank; wherein the desander (15) has electromagnetic induction heating coils connected in parallel or in series; S6. The heated slurry is sent to a three-phase centrifuge (18) for separation to obtain oil, solid residue, and wastewater F. The oil is sent to an external oil storage tank, and the solid residue is sent to an external breeding equipment. The solid residue is solid waste, and the wastewater F is sent to a homogenization tank (24) for temporary storage. S7. The hot liquid in the homogenization tank (24) is returned to the hydraulic pulper (1), the hot liquid being a portion of the wastewater F, and the remaining wastewater F being sent to the carbon source preparation tank (26) for fermentation to obtain a fermentation slurry; wherein the bottom of the carbon source preparation tank (26) is provided with an aeration pipe or an aeration plate for aeration; S8. Discharging the fermentation slurry into an inclined plate sedimentation tank (31) for solid-liquid separation, removing surface suspended matter, and obtaining a liquid carbon source, sludge, and scum, wherein the sludge includes bottom sludge and non-bottom sludge, the bottom sludge is internally refluxed from the inclined plate sedimentation tank (31) to the carbon source preparation tank (26), and the scum and the non-bottom sludge are externally refluxed from the inclined plate sedimentation tank (31) to the hydraulic pulper (1); S9. sending the liquid carbon source to a denitrification process.

2. A food waste treatment process according to claim 1, wherein a food waste treatment device is used in the process, characterized in that: The device comprises a hydraulic pulping machine (1), a wastewater tank (11), a desander (13), a desander (15), a three-phase centrifuge (18), a homogenizing tank (24), a carbon source preparation box (26), and an inclined plate sedimentation tank (31), which are sequentially connected by pipelines; a press (9) is connected in parallel between the hydraulic pulping machine (1) and the wastewater tank (11).

3. A kitchen waste treatment process according to claim 2, characterized in that: The hydraulic pulping machine (1) includes a filter device (2) having a filter plate therein, and the filter device (2) is used to filter the slurry and the impurity A, and separate the impurity A into impurities B and coarse residue C, wherein the particle size of the impurity B is smaller than the mesh diameter of the filter plate, and the coarse residue C is a substance having a particle size exceeding the mesh diameter of the filter plate; The hydraulic pulping machine (1) further comprises a water outlet (4), wherein the water outlet (4) is connected to the wastewater pool (11) via a pipe 1 (5); the hydraulic pulping machine further comprises a water inlet (3).

4. A kitchen waste treatment process according to claim 3, characterized in that: The hydraulic pulping machine (1) is connected to the screw conveyor (7) via the second pipe (6), the second pipe (6) is located on the upper side of the first filter device (2), and the second pipe (6) is used to convey the coarse residue C; the screw conveyor (7) is connected to the press (9) via the third pipe (8), and the press (9) is used to press and separate the coarse residue C; The press (9) includes a second filtering device (10), wherein a screen is provided in the second filtering device (10), and the screen is used to filter and separate the leachate and the coarse residue D.

5. A kitchen waste treatment process according to claim 4, characterized in that: The press (9) is connected to the wastewater tank (11) via a pipeline nine (36), the wastewater tank (11) is connected to the desander (13) via a pipeline four (12), and the desander (13) is connected to the desander (15) via a pipeline five (14).

6. A process for treating food waste according to claim 5, characterized in that: The desander (15) includes a stirrer (16), the stirrer (16) is used to stir the desanded slurry, and the electromagnetic induction heating coil is used to heat the desanded slurry, the heating temperature is 80°C to 100°C, and the heating time is 30 minutes to 45 minutes.

7. A process for treating food waste according to claim 6, characterized in that: The desander (15) is connected to a three-phase centrifuge (18) via a pipe six (17). The three-phase centrifuge (18) includes a solid residue outlet (20), a grease outlet (21), and a wastewater outlet (22). The three-phase centrifuge (18) is used to centrifuge the heated slurry. The solid residue outlet (20) is connected to external breeding equipment, the grease outlet (21) is connected to an external grease storage tank, and the wastewater outlet (22) is connected to the homogenization tank (24).

8. A process for treating food waste according to claim 3, characterized in that: The homogenization tank (24) is connected to the water inlet (3) via a reflux pipe (34), and the reflux pipe (34) is used for hot liquid reflux.

9. A process for treating food waste according to claim 2, characterized in that: The homogenization tank (24) is connected to the carbon source preparation box (26) via a pipe eight (25). The carbon source preparation box (26) includes a grid A (27) and a grid B (28). An overflow port (29) is provided between the grid A (27) and the grid B (28). The grid A (27) is connected to a sludge return pipe (30).

10. A process for treating food waste according to claim 9, characterized in that: The sludge return pipe (30) is connected to the inclined plate sedimentation tank (31) through the sludge return pipe (32). The sludge return pipe (32) and the sludge return pipe (30) are used to internally return the sludge at the bottom. A scraper (33) is provided on the upper part of the inclined plate sedimentation tank (31). The scraper (33) is used to remove suspended matter on the surface of the fermentation slurry. The inclined plate sedimentation tank (31) is also connected to a second return pipe (35). The second return pipe (35) is used to externally return the scum and the sludge not at the bottom.

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