A fermentation device for recovering carboxylic acid while reducing greenhouse gas emission

Abstract

The application provides a fermentation device for recycling carboxylic acid while reducing greenhouse gas emission, comprising a fermentation container, a sludge inlet assembly, a water decanting assembly, a hydraulic circulation assembly, a heating and insulation assembly, a stirring assembly, a medicament regulating assembly and a monitoring and control assembly. The fermentation device of the application recycles carboxylic acid from all primary sludge and residual sludge of a sewage treatment plant, produces a carboxylic acid mixture with a specific ratio through operation and reaction parameter control of the fermentation device, greatly reduces the emission of methane and other greenhouse gases produced in fermentation, and adds the recycled carboxylic acid mixture to a primary and secondary tank to realize clean and super-clean sewage treatment and efficient removal of greenhouse gases. The carboxylic acid industrial product can be recovered by separating and purifying the supernatant to realize resource recovery. Compared with the prior art, the application has the advantages of optimized hydraulic conditions and trace element adjustment function, integrated fermentation and product water decanting separation, energy-saving and environment-friendly insulation design, high automation degree and real-time monitoring, and no need for additional microbial strains.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of municipal drainage, in particular to a fermentation device and method for recovering carboxylic acid while reducing greenhouse gas emissions. BACKGROUND

[0002] At present, a large number of sewage plants add a large amount of additional carbon sources such as methanol, acetic acid, sodium acetate, propionic acid, glucose, etc. due to the lack of carbon sources required for nitrogen and phosphorus removal in sewage. In recent years, the requirements for effluent quality are continuously improved, and the demand for carbon sources is gradually increasing, which doubles the energy consumption of sewage plants. In addition, the treatment and disposal of a large amount of sludge generated during sewage treatment is difficult, and the resource utilization of sludge needs to be solved urgently.

[0003] Recent studies have shown that sludge generated in sewage treatment plants (mainly including sludge generated in the pretreatment link and residual sludge generated in the biological treatment link) contains a large amount of carbohydrates, proteins and fats, etc., which are all slow organic carbon sources. If they are converted into efficient organic carbon sources (such as carboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, etc.), they can be used to significantly promote the nitrogen and phosphorus removal process in the biological reaction tank, and by adjusting the pH value and the concentration of trace elements in the sewage, the metabolic balance of functional microorganisms in the reaction tank can be regulated, thereby inhibiting the metabolic activity of non-functional microorganisms (such as methanogenic bacteria), avoiding the emission of greenhouse gases such as methane, and achieving the goal of carbon emission reduction. Therefore, the preparation of efficient organic carbon sources-carboxylic acids from sludge is particularly important for promoting the low-carbon operation of sewage plants.

[0004] At present, the research on sludge fermentation at home and abroad mainly focuses on the mechanism of acid production under different sludge fermentation conditions, and the theoretical analysis is heavy, and the development progress of equipment for actual engineering application is relatively slow. The requirements of bacteria on pH value, temperature, etc. in the process of sludge anaerobic fermentation are relatively complex, and in actual large-scale engineering application, most of the existing equipment are limited to adding drugs to the sludge for pretreatment, or only consider the form of the equipment to meet the fermentation conditions, etc., and the cost of drug addition and temperature control is high. For example, the invention patent with the application number 202211043645.4 “Preparation method of carbon source for primary sludge in sewage plant”, only adjusts the pH value to the isoelectric point to pretreat the sludge; the utility model patent with the application number 202321878183.8 “Device for producing acid by anaerobic fermentation of residual sludge based on potassium ferrate” pretreats the sludge by adding reagents. Such technologies weaken the process control of sludge fermentation itself, and have not been widely used in engineering.

[0005] In summary, there is still a lack of a fermentation device with the functions of hydraulic condition optimization and substrate metabolism regulation, which can integrally recover carboxylic acid while reducing greenhouse gas emissions with high efficiency and low cost. SUMMARY

[0006] The purpose of the present application is to optimize the process parameters by improving the internal hydraulic conditions of the sludge anaerobic fermentation device and adjusting the substrate metabolism, so that the sludge produced by the sewage treatment plant is more efficiently, energy-saving and low-carbon fermented in the fermentation device to produce high-quality carbon source, and then the high-quality carbon source is reused in the anoxic tank of the sewage treatment plant, thereby significantly improving the nitrogen and phosphorus removal efficiency of the anoxic tank, reducing the amount of additional carbon source in the anoxic tank, and reducing greenhouse gas emissions, achieving the goal of reducing cost and increasing efficiency.

[0007] To achieve the above purpose, the present application provides a fermentation device for recovering carboxylic acid while reducing greenhouse gas emissions, which comprises a fermentation container, a sludge inlet assembly, a water decanting assembly, a hydraulic circulation assembly, a heating and insulation assembly, a stirring assembly, a medicament regulating assembly and a monitoring and control assembly; the lower part of the side wall of the fermentation container is provided with a sludge inlet and a hydraulic circulation inlet, the middle and upper part of the side wall is provided with a hydraulic circulation outlet, and the upper part of the side wall is provided with a carboxylic acid outlet; the sludge inlet assembly is connected to the sludge inlet and extends into the interior of the fermentation container; the water decanting assembly is arranged at the top of the fermentation container and is connected with the carboxylic acid outlet to decant the fermented carboxylic acid from the top of the fermentation container and transport it to the anoxic tank; the hydraulic circulation assembly is connected with the hydraulic circulation inlet and the hydraulic circulation outlet, and the circulation pump is used to suck and return the sludge to realize the stirring of the sludge in the fermentation container; the heating and insulation assembly is arranged on the side wall of the fermentation container to heat and insulate the sludge in the fermentation container; the stirring assembly fully stirs the sludge through the multi-stage paddles arranged in the fermentation container; the medicament regulating assembly is connected with the fermentation container and transports the medicament into the fermentation container; the monitoring and control assembly comprises a controller and a monitoring instrument arranged in the fermentation container, the monitoring instrument continuously monitors the temperature, pH value and water quality of the sludge in the fermentation container, and the controller adjusts the process parameters of the sludge inlet assembly, the hydraulic circulation assembly, the heating and insulation assembly, the stirring assembly and the medicament regulating assembly in real time according to the monitoring results, so as to ensure that the temperature of the sludge in the fermentation container is stably maintained at 35-55℃, and a carboxylic acid with a predetermined concentration is produced; the concentration of the produced carboxylic acid is S V The calculation formula is:

[0008]

[0009] S V The concentration of the produced carboxylic acid is S P The concentration of the produced carboxylic acid is S h The concentration of the produced carboxylic acid is S m,h The maximum specific utilization rate of the hydrolysis product is k h The concentration of the carboxylic acid producing bacteria is XS,h Ks is the half-saturation constant for growth of carboxylic acid producing bacteria; K I,h k is the coefficient for the effect of carboxylic acid concentration on growth of carboxylic acid producing bacteria; k m,v k is the maximum specific utilization rate of carboxylic acid; X v k is the concentration of methanogenic microorganisms; k is the maximum specific substrate removal rate constant; k d,h k is the endogenous decay rate of carboxylic acid producing bacteria microorganisms; k d,v k is the endogenous decay rate of methanogenic microorganisms.

[0010] Further, the sludge feeding assembly comprises a sludge feeding pipe, a sludge feeding pump with adjustable flow rate, and a sludge feeding pipe support, the sludge feeding pipe extends into the fermentation container through a sludge feeding port in the side wall of the fermentation container until the outlet of the sludge feeding pipe is located in the central region of the fermentation container, and the sludge feeding pipe support is supported below the sludge feeding pipe; the sludge feeding pump is connected to the inlet of the sludge feeding pipe for pumping primary sludge or residual sludge generated by the sewage treatment plant; the monitoring and control assembly controls the flow rate of the sludge feeding pump in the sludge feeding assembly in real time according to the monitoring results, and controls the sludge fermentation residence time in the fermentation container to be 5-8 days, so that the sludge feeding flow rate matches the carboxylic acid production efficiency.

[0011] Further, a residue discharging port is formed in the upper part of the side wall of the fermentation container, and the carboxylic acid outlet is connected to the aerobic tank of the sewage treatment plant for conveying the fermented carboxylic acid supernatant to the aerobic tank; the water decanting assembly comprises a water decanting device, a carboxylic acid pipeline, a scum skimming machine, and a scum collecting tank; the water decanting device comprises a rectangular or annular water decanting tank, the tank opening of the water decanting tank is arranged at the top of the fermentation container, the carboxylic acid produced by sludge fermentation is clarified and stratified at the top of the sludge, and the supernatant at the top flows into the water decanting tank in an overflow manner through the tank opening of the water decanting tank; one end of the carboxylic acid pipeline is connected to the tank body of the water decanting tank, and the other end is connected to the carboxylic acid outlet; the scum skimming machine is arranged at the top of the fermentation container and is driven by a skimming motor, and is used for skimming the scum on the surface of the carboxylic acid supernatant into the scum collecting tank; the tank opening of the scum collecting tank is 0.5-5 cm higher than the surface of the carboxylic acid supernatant, the tank body of the scum collecting tank is inclined downward at an angle, the lowest part is connected to the residue discharging port, and the collected scum is discharged from the fermentation container through the residue discharging port.

[0012] Further, the water circulation assembly comprises a circulation pump, a circulation sludge inlet main pipe, a circulation sludge inlet distribution head, a circulation sludge inlet branch pipe and a circulation sludge outlet pipe; the circulation sludge inlet distribution head is located in the central area of the bottom of the fermentation container, the circulation sludge inlet branch pipe is evenly connected to the periphery of the circulation sludge inlet distribution head in a radial manner; one end of the circulation sludge inlet main pipe is connected to the circulation sludge inlet distribution head, and the other end penetrates out of the water circulation inlet; the circulation pump is arranged outside the fermentation container, the inlet of the circulation pump is connected to the outlet of the circulation sludge inlet main pipe, and the outlet of the circulation pump is connected to the circulation sludge outlet pipe located in the upper part of the fermentation container; the circulation sludge outlet pipe penetrates into the fermentation container from the water circulation outlet, and is provided with a plurality of circulation sludge outlet openings; when the circulation pump is working, sludge is sucked from the bottom of the fermentation container through the circulation sludge inlet branch pipe and the circulation sludge inlet main pipe, and then the sludge is pumped to the circulation sludge outlet pipe and is sprayed out at high speed through the circulation sludge outlet openings, the working flow of the circulation pump is 10-50 times of the effective volume of the fermentation container divided by 24, the hydraulic circulation of sludge in the fermentation container is realized, and the hydraulic flow state of the sludge is optimized.

[0013] Further, the heating and heat preservation assembly comprises a heating facility and a heat preservation layer; the heating facility is an electric heating tape wound on the sludge inlet pipe of the sludge inlet assembly and / or the side wall of the fermentation container, a hot water coil heated by a water source heat pump and / or a heating structure arranged in the fermentation container; the heat preservation layer is arranged on the side wall of the fermentation container to reduce heat loss of the fermentation container; the monitoring and electric control assembly adjusts the heating and heat preservation assembly in real time, so that the temperature of the sludge in the fermentation container is stably maintained at 35-55℃.

[0014] Further, a blender mounting hole is formed in the top surface of the fermentation container; the stirring assembly comprises a blender with variable and adjustable rotating speed, a multi-stage paddle, a rotating shaft and a heat transfer circulation pipe; the blender is eccentrically mounted in the blender mounting hole, and the rotating shaft thereof extends into the fermentation container; the multi-stage paddle is mounted on the middle and lower part of the rotating shaft and is evenly divided into 2-5 layers to sufficiently stir the sludge in the fermentation container; the rotating speed of the multi-stage paddle is 20-60 r / min; each layer of the multi-stage paddle comprises a plurality of paddle blades, a hydraulic support rod and a flexible connector, the plurality of paddle blades are connected by the flexible connector, and the included angle between the plurality of paddle blades is adjusted by the extension and contraction of the hydraulic support rod; when the stirring intensity of the sludge needs to be increased, the included angle between the plurality of paddle blades is increased; otherwise, the included angle is reduced.

[0015] Further, the stirring assembly further comprises a heat transfer circulation pipe, the heat transfer circulation pipe penetrates through the rotating shaft and the plurality of paddles, the heat transfer circulation pipe comprises a heat inlet pipe and a heat return pipe in communication with the heat inlet pipe, the heat transfer medium supplied by the water source heat pump flows into the heat inlet pipe, and heat is conducted to the sludge through the rotating shaft and the plurality of paddles, and the cooled water flows back to the water source heat pump from the heat return pipe.

[0016] Further, the medicament regulating assembly comprises a medicament distributor, a medicament feeding pipe provided with a metering pump, and a medicament tank; the medicament tank is located outside the fermentation container and is connected to the medicament distributor located inside the fermentation container through the medicament feeding pipe penetrating through the fermentation container; the medicaments in the medicament tank comprise one or more of alkali liquor, acid liquor, and trace element solution; the monitoring and control assembly adjusts the flow rates of the alkali liquor, the acid liquor, and the trace element solution in the medicament regulating assembly in real time through the metering pump, so that the pH value of the sludge in the fermentation container is maintained at 8-10, and the concentrations of the trace elements in the sludge are maintained as follows: Cu 2+ , 20-65 mmol / L; Mn 2+ , 2.5-6.0 mmol / L; B 3+ , 15.0-28.5 mmol / L, Mo 6+ , 4.0-6.2 mmol / L; W 6+ , 7.0-12.2 mmol / L; Ni 2 + , 3.0-5.5 mmol / L; Co 2+ , 10.0-18.3 mmol / L; Zn 2+ , 25.5-35.0 mmol / L; Ca 2+ , 10.5-30.5 mmol / L.

[0017] Further, the medicament distributor is a ring-shaped medicament distributor, which is arranged 20-100 cm below the liquid level in the fermentation container, and a plurality of medicament injection ports for uniformly injecting the medicaments into the sludge are distributed on the ring-shaped medicament distributor.

[0018] Further, the medicament regulating assembly further comprises an inert gas storage cabin, an inert gas feeding pipe, and inert gas stripping injection ports; the inert gas storage cabin is located in the medicament tank and is in communication with the inert gas feeding pipe; the inert gas feeding pipe is horizontally arranged at the bottom of the fermentation container, and a plurality of inert gas stripping injection ports are uniformly distributed on the inert gas feeding pipe; the inert gas stripping injection ports spray nitrogen, helium, or argon at a predetermined flow rate, which is used for stripping the residual dissolved oxygen in the sludge and maintaining the anaerobic environment of the sludge fermentation.

[0019] Further, the fermentation device further comprises a venting assembly, the bottom of the fermentation container is provided with a venting opening; the venting assembly comprises a plurality of venting branch pipes, a venting transfer box and a venting pipe; the inlet of the venting branch pipe faces downward and is spaced apart from the bottom surface of the fermentation container by 3-30 cm; the venting transfer box is a hollow box body, the side wall of the venting transfer box is connected with the plurality of venting branch pipes; one end of the venting pipe is connected with the venting transfer box, the other end of the venting pipe passes out of the venting opening and is used for venting the sludge and carboxylic acid in the fermentation container when the device is overhauled.

[0020] Further, the side wall of the fermentation container is provided with a plurality of instrument monitoring openings, the instrument monitoring openings are uniformly distributed along the side wall of the fermentation container from a high position to a low position at a certain rotation angle; the monitoring instruments are embedded in the instrument monitoring openings and comprise a thermometer, a pH meter and a water quality monitoring probe, the thermometer, the pH meter and the water quality monitoring probe are respectively used for continuously monitoring the temperature, the pH value and the water quality of the sludge in the fermentation container; the water quality monitoring probe can simultaneously monitor the concentrations of organic matter COD, total nitrogen TN, total phosphorus TP, total organic acid root, acetic acid root, propionic acid root, butyric acid root and pentanoic acid root in the sludge; the controller can adjust the flow of the circulating pump in the hydraulic circulating assembly and the rotating speed of the stirrer in the stirring assembly in real time, so that the data monitored by the thermometers, the pH meters and the water quality monitoring probes at different positions tend to be consistent.

[0021] Compared with the prior art, the fermentation device for recycling carboxylic acid while reducing greenhouse gas emission has at least the following advantages:

[0022] 1. High automation degree and real-time monitoring

[0023] The present application studies the carboxylic acid concentration S V The calculation formula can continuously monitor the temperature, pH and water quality in the fermentation container by monitoring the electric control assembly, and can adjust the operating parameters of each component in real time according to the monitoring results, so as to ensure that the device is in the best operating state; the high automation degree and real-time monitoring function improve the operation stability and operation simplicity of the device, and reduce the manual intervention and operation errors.

[0024] 2. Substrate metabolism regulation and greenhouse gas emission reduction

[0025] The present application combines hydraulic circulation and medicament regulation, and realizes uniform disturbance and reflux of sludge through a hydraulic circulation assembly, thereby improving completeness and efficiency of the sludge fermentation process. The substrate metabolism regulation includes regulation of pH value, temperature and trace element concentration in the fermentation device, thereby ensuring stability and optimization of the fermentation environment, promoting conversion of the sludge into efficient organic carbon sources (such as carboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, etc.), and through addition of the above-mentioned efficient organic carbon sources to the anoxic tank, the abundance of denitrifying key microorganisms (such as Hyphomicrobium, Solanecus, Pseudomonas, etc.) can be increased by 6%-12%, the abundance of biological reaction pool phosphorus removal microorganisms (such as Xanthobacter, Accumulibacter, Thauera, etc.) can be increased by 15%-49%, and expression of denitrification and phosphorus removal key genes (such as polyphosphate kinase encoding, PHA synthase encoding, NO reductase encoding, etc.) can be promoted, thereby promoting denitrification and phosphorus removal, achieving metabolic balance regulation of functional microorganisms in the reaction tank, inhibiting metabolic activity of non-functional microorganisms (such as methanogenic bacteria), avoiding emission of greenhouse gases such as methane, and achieving the goal of carbon emission reduction.

[0026] 3. Integrated fermentation and product decanting separation

[0027] The integrated design of the fermentation container, the decanting assembly and the skimmer realizes efficient separation and direct utilization of fermentation products. The carboxylic acid supernatant produced by fermentation is transported to the anoxic tank through the decanting assembly, thereby promoting the denitrification and phosphorus removal process, and the remaining sludge after fermentation continues to enter the original sludge treatment process. This design simplifies the operation process, reduces the secondary treatment steps, and enables the fermentation products to be directly and efficiently applied to the wastewater treatment system.

[0028] 4. Energy-saving and environmentally-friendly heat preservation design

[0029] The present application maintains the temperature in the fermentation container at 35-55℃ by using heat preservation equipment, thereby fully utilizing the heat generated by sludge fermentation and not requiring a large amount of additional heat input. The present application provides multiple low-energy heat preservation and heat exchange modes, which can be selected according to actual needs. Compared with the high-energy additional heating mode of the prior art, the present application significantly reduces energy consumption, saves resources, and improves the environmental friendliness and economy of the device.

[0030] 5. No need for additional addition of microbial strains

[0031] The integrated device of the present application can be self-operated after starting, and does not require additional addition of microbial strains, relying on its own system circulation and regulation to realize efficient fermentation of sludge. This not only reduces the operating cost, but also reduces the use of chemicals and the potential impact on the environment, making the entire treatment process more green and environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only need to be some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0033] Figure 1 The cross-sectional view of the fermentation device for recovering carboxylic acid and reducing greenhouse gas emission according to the present application.

[0034] Figure 2 The plan view of the fermentation device for recovering carboxylic acid and reducing greenhouse gas emission according to the present application.

[0035] Figure 3 The pipeline plan layout of the hydraulic circulation assembly according to the present application.

[0036] Figure 4 The pipeline plan layout of the sludge feeding assembly and the venting assembly according to the present application.

[0037] Figure 5 The structure diagram of the stirring assembly according to the present application.

[0038] Figure 6 The schematic diagram of different operating states of the stirring assembly according to the present application.

[0039] Figure 7 The structure diagram of the water decanting tank according to the present application.

[0040] Figure 8 The paddle lifting angle diagram in the embodiment 2 according to the present application.

[0041] Figure 9 The process flow diagram of the practical application of the present application.

[0042] Figure 10 The influence of the produced carboxylic acid according to the present application on the key genes for denitrification and phosphorus removal after being added into the aerobic tank.

[0043] Figure 11 The influence of the produced carboxylic acid according to the present application on the key microorganisms for phosphorus removal after being added into the aerobic tank.

[0044] Figure 12 The influence of the produced carboxylic acid according to the present application on the key microorganisms for denitrification after being added into the aerobic tank.

[0045] Reference: 1-fermentation vessel, 101-inlet, 102-carboxylic acid outlet, 103-vent, 104-discharge, 105-hydraulic circulation inlet, 106-hydraulic circulation outlet, 107-inspection manhole, 108-mixer mounting hole, 109-exhaust port, 110-breathing port, 111-sampling port, 112-instrument monitoring port, 113-supporting angle plate;

[0046] 2-inlet assembly, 21-inlet pipe, 22-inlet pipe support, 23-inlet pipe outlet;

[0047] 3-water decanting assembly, 31-decanting device, 311-decanting tank, 32-carboxylic acid pipeline, 33-supporting partition, 34-skimming machine, 35-froth collecting tank;

[0048] 4-hydraulic circulation assembly, 41-circulation pump, 42-circulation inlet pipe, 43-circulation inlet distribution head, 44-circulation inlet branch pipe, 45-circulation inlet pipeline support, 46-circulation outlet pipe, 47-circulation outlet port, 48-circulation outlet pipeline support;

[0049] 5-heating and heat preservation assembly, 51-heating facility, 52-heat preservation color steel corrugated board, 53-heat preservation ring;

[0050] 6-stirring assembly, 61-mixer, 611-connection device, 62-multi-stage paddle, 621-paddle, 622-hydraulic support rod, 623-flexible connector, 63-rotating shaft, 631-heat inlet pipe 631, 632-heat return pipe, 64-shaft end, 65-heat transfer circulation pipe;

[0051] 7-chemical control assembly, 71-ring-shaped chemical distributor, 72-chemical feeding pipe, 73-chemical spraying port, 74-metering pump, 75-chemical feeding tank, 76-inert gas storage cabin, 77-inert gas feeding pipe, 78-inert gas stripping spraying port;

[0052] 8-vent assembly, 81-vent branch pipe, 82-vent transfer tank, 83-vent pipe;

[0053] 9-monitoring and control assembly, 91-thermometer, 92-pH meter, 93-water quality monitoring probe. DETAILED DESCRIPTION

[0054] The technical solutions of the present application will be described clearly and completely in combination with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0055] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0056] Embodiment 1

[0057] Referring to Figure 1 The present application provides a fermentation device for recovering carboxylic acid while reducing greenhouse gas emissions, which comprises a fermentation container 1, a sludge inlet assembly 2, a water decanting assembly 3, a hydraulic circulation assembly 4, a heating and insulation assembly 5, a stirring assembly 6, a medicament regulating assembly 7, a venting assembly 8 and a monitoring and control assembly 9.

[0058] Referring to Figures 2-4 The fermentation container 1 is arranged on the ground near the sewage treatment facility, for containing the sludge generated by the sewage treatment facility and fermenting it into carboxylic acid which is easy to be utilized by microorganisms in the nitrification tank. The sludge inlet assembly 2 is connected to the lower part of the fermentation container 1, for conveying primary sludge or residual sludge generated by the sewage treatment facility into the fermentation container 1; the water decanting assembly 3 is arranged at the top of the fermentation container 1, for decanting the fermented carboxylic acid from the top of the fermentation container 1 and conveying it to the nitrification tank, thereby promoting the denitrification and phosphorus removal process of the microorganisms in the nitrification tank; the hydraulic circulation assembly 4 is arranged in the fermentation container 1, which realizes the agitation of the sludge in the fermentation container 1 through the suction and return of the circulating pump 41, thereby improving the hydraulic circulation flow state of the sludge; the heating and insulation assembly 5 is used to heat the sludge in the fermentation container 1 to a suitable temperature and reduce the heat dissipation of the sludge; the stirring assembly 6 fully stirs the sludge in the fermentation container 1 through multiple stages of paddles, so that the sludge is evenly distributed; the medicament regulating assembly 7 realizes the regulation of the growth and metabolism environment of the microorganisms in the sludge by conveying medicaments into the fermentation container 1, thereby promoting the carboxylic acid production efficiency and improving the quality of the produced carboxylic acid; the venting assembly 8 is arranged at the bottom of the fermentation container 1, for completely venting the sludge in the fermentation container 1 during maintenance; the monitoring and control assembly 9 is used to continuously monitor the temperature, pH and water quality of the sludge in the fermentation container 1, and according to the monitoring results, the process parameters of the sludge inlet assembly 2, the hydraulic circulation assembly 4, the heating and insulation assembly 5, the stirring assembly 6 and the medicament regulating assembly 7 are adjusted in real time, so as to ensure that the fermentation device is in the best operating condition.

[0059] The fermentation container 1 is made of 304 or SS316 stainless steel, and has a cylindrical or egg-shaped overall shape; the lower part of the side wall of the fermentation container 1 is provided with a sludge inlet 101, a hydraulic circulation inlet 105, a vent 103 and an inspection manhole 107, the middle and upper part of the side wall is provided with a hydraulic circulation outlet 106, the upper part of the side wall is provided with a carboxylic acid outlet 102 and a slag discharge port 104; a plurality of sampling ports 111 and a plurality of instrument monitoring ports 112 are uniformly provided on the lower part to the upper part of the side wall of the fermentation container 1, and the sampling ports 111 and the instrument monitoring ports 112 are uniformly distributed along the side wall of the fermentation container 1 from high to low with a certain rotation angle; the sampling ports 111 are each connected with a sampling pipe, and the sampling pipe is provided with a stop valve; the top surface of the fermentation container 1 is also provided with an inspection manhole 107, and is also provided with a mixer mounting hole 108, an exhaust port 109 and a breathing port 110; the exhaust port 109 is used for discharging the gas generated in the fermentation container 1; the breathing port 110 is used for maintaining the air pressure balance in the fermentation container 1; an automatic exhaust check valve is arranged at the top of the exhaust port 109, and the gas in the fermentation container 1 can only go out but cannot go in; a reverse air inlet check valve is arranged at the top of the breathing port 110, and the gas can only enter the fermentation container 1 but cannot be discharged; the bottom surface of the fermentation container 1 is provided with a support angle plate 113 for stably supporting the entire device on the ground; the top surface of the fermentation container 1 is provided with a tank top plate, a tank top reinforcing steel bar and a tank top fence structure, so that the staff can conveniently overhaul the device through the inspection manhole 107 on the top of the fermentation container 1.

[0060] The sludge inlet assembly 2 is connected to the lower part of the fermentation container 1, and comprises a sludge inlet pipe 21, a sludge inlet pump with adjustable flow and a sludge inlet pipe support 22; the sludge inlet pipe 21 is connected with the sludge inlet 101 at the lower part of the side wall of the fermentation container 1 and extends into the fermentation container 1 through the sludge inlet 101, until the sludge inlet pipe outlet 23 is located in the central region of the fermentation container 1, and the sludge inlet pipe support 22 is supported below the sludge inlet pipe 21; the sludge inlet pump is located outside the fermentation container 1 and is connected with the inlet of the sludge inlet pipe 21, and is used for pumping primary sludge or residual sludge generated by a sewage treatment facility, and the moisture content of the primary sludge or residual sludge is 95%-99.5%; the flow of the sludge inlet pump can be adjusted according to the operation requirements of the fermentation device. The monitoring electric control assembly 9 adjusts the flow of the sludge inlet pump in the sludge inlet assembly 2 in real time according to the monitoring result, controls the sludge fermentation residence time in the fermentation container 1 to be 5-8d, so that the sludge inlet flow is matched with the carboxylic acid production efficiency.

[0061] The water decanting assembly 3 is located at the top of the fermentation container 1, and comprises a water decanting device 31, a carboxylic acid pipeline 32, a support partition plate 33, a skimming machine 34 and a floating slag collecting tank 35; the water decanting device 31 comprises a rectangular or annular water decanting tank 311 (see Figure 7), the notch of the decanting tank 311 is arranged at the top of the fermentation container 1, the carboxylic acid produced by the fermentation of the sludge is clarified and stratified at the top of the sludge, the clarified liquid at the top flows into the decanting tank 311 through the notch of the decanting tank 311 in an overflow manner, one end of the carboxylic acid pipeline 32 is connected with the tank body of the decanting tank 311, and the other end is connected with the carboxylic acid outlet 102, the carboxylic acid outlet 102 is communicated to the aerobic tank of the sewage treatment facility, and is used to transport the clarified liquid of the fermented carboxylic acid to the aerobic tank, the skimming machine 34 is arranged at the top of the fermentation container 1, is driven by the skimming motor 341, and is used to skim the scum on the surface of the carboxylic acid clarified liquid into the scum collecting tank 35, the notch of the scum collecting tank 35 is 0.5-5cm higher than the liquid surface, the tank body of the scum collecting tank 35 is inclined downward at an angle, the lowest part is connected with the residue discharge port 104, and the collected scum is discharged from the fermentation container 1 through the residue discharge port 104.

[0062] The hydraulic circulation assembly 4 comprises a circulation pump 41, a circulation sludge inlet main pipe 42, a circulation sludge inlet distribution head 43, a circulation sludge inlet branch pipe 44, a circulation sludge inlet pipeline support 45, a circulation sludge outlet pipe 46, a circulation sludge outlet port 47 and a circulation sludge outlet pipeline support 48. The circulation sludge inlet main pipe 42, the circulation sludge inlet distribution head 43 and the circulation sludge inlet branch pipe 44 are all arranged at the bottom of the fermentation container 1 and are sequentially connected, the circulation sludge inlet distribution head 43 is arranged at the center area of the bottom of the fermentation container 1, the circulation sludge inlet branch pipes 44 are evenly connected around the circulation sludge inlet distribution head 43 in a radial manner, and the circulation sludge inlet pipeline support 45 supports the circulation sludge inlet branch pipes 44 from below, one end of the circulation sludge inlet main pipe 42 is connected with the circulation sludge inlet distribution head 43, and the other end penetrates out from the hydraulic circulation inlet 105, the circulation pump 41 is arranged outside the fermentation container 1, the inlet of the circulation pump 41 is connected with the outlet of the circulation sludge inlet main pipe 42, and the outlet of the circulation pump 41 is connected with the circulation sludge outlet pipe 46 arranged at the upper part of the fermentation container 1, the circulation sludge outlet pipe 46 penetrates into the fermentation container 1 from the hydraulic circulation outlet 106 and is provided with a plurality of circulation sludge outlet ports 47, when the circulation pump 41 works, the sludge is sucked from the bottom of the fermentation container 1 through the circulation sludge inlet branch pipes 44 and the circulation sludge inlet main pipe 42, is then pumped to the circulation sludge outlet pipe 46 under pressure, and is finally jetted out through the circulation sludge outlet ports 47 at a high speed, so that the hydraulic circulation of the sludge in the fermentation container 1 is realized, and the hydraulic flow state of the sludge is optimized. The circulation sludge outlet pipeline support 48 is arranged at the middle and upper part of the fermentation container 1 and is used to support the circulation sludge outlet pipe 46. The working flow rate of the circulation pump 41 (unit: m 3 / h) is 10-50 times of “effective volume V (m 3 ) of the fermentation container 1 ÷ 24 (h)”, so that the residence time of the sludge in the fermentation container 1 is 5 days under the working condition of continuously feeding the primary sludge and discharging the carboxylic acid.

[0063] The heating and insulation assembly 5 comprises a heating facility 51 and an insulation layer; the heating facility 51 is an electric heating tape wound on the sludge inlet pipe 21 of the sludge inlet assembly 2 and / or the sidewall of the fermentation container 1 or a hot water coil heated by a water source heat pump, and / or a heating structure arranged inside the fermentation container 1; the insulation layer is arranged on the sidewall of the fermentation container 1 to reduce heat loss of the fermentation container 1; the insulation layer can be an insulation color steel corrugated board 52 arranged on the sidewall of the fermentation container 1 and fixed by insulation rings 53, the number of the insulation rings 53 is multiple, and the insulation rings 53 are evenly arranged on the outside of the fermentation container 1 at certain intervals in the height direction to effectively fix the insulation color steel corrugated board 52. The heating structure arranged inside the fermentation container 1 can have various forms, for example, a heat transfer circulating pipe type in heating mode one and an electric heating tape type in heating mode two. The monitoring and control assembly 9 adjusts the heating and insulation assembly 5 in real time to maintain the temperature of the sludge in the fermentation container 1 at 35-55℃.

[0064] Please refer to Figure 1 、 Figures 5-8 , the stirring assembly 6 comprises a stirring machine 61 with variable frequency and adjustable rotating speed, multi-stage paddles 62, a rotating shaft 63, shaft ends 64 and a heat transfer circulating pipe 65; the stirring machine 61 is eccentrically installed in a stirring machine installation hole 108 on the top surface of the fermentation container 1, and the rotating shaft 63 thereof extends into the fermentation container 1; the multi-stage paddles 62 are evenly divided into 2-5 layers and are arranged in the middle and lower parts of the fermentation container 1 to fully stir the sludge in the fermentation container 1; the stirring machine 61 is designed with variable frequency and is connected to the rotating shaft 63 through a connecting device 611, and the rotating speed thereof can be adjusted as required; specifically, the frequency of the stirring machine 61 can be adjusted at a frequency of 100%-30%, and preferably, the frequency of the stirring machine can be dynamically adjusted at a frequency of 15 Hz-50 Hz. The connecting device 611 can select a rotary joint or a current collector ring according to different heating modes. The rotating speed of the multi-stage paddles 62 is 30 r / min; the multi-stage paddles 62 are evenly and fixedly arranged on the rotating shaft 63, and the shaft ends 64 are located at the bottom of the rotating shaft 63; each layer of the multi-stage paddles 62 comprises a plurality of paddle blades 621, a hydraulic support rod 622 and a flexible connector 623; the plurality of paddle blades 621 are connected by the flexible connector 623, as shown in Figure 6 , the included angle between the plurality of paddle blades 621 can be adjusted in size under the expansion and contraction of the hydraulic support rod 622, and when it is necessary to increase the stirring intensity of the sludge, the included angle between the plurality of paddle blades 621 is increased; otherwise, the included angle is reduced. In this embodiment, the included angle between the plurality of paddle blades 621 of the first layer is 180°, the included angle between the plurality of paddle blades 621 of the second layer is 90°, and the included angle between the plurality of paddle blades 621 of the third layer is 60°; the included angle adjustment process also has the effects of impurity separation and broken fiber-like winding.

[0065] When the heating structure arranged inside the fermentation container 1 is a heat transfer circulating pipe, the heat transfer circulating pipe penetrates the rotating shaft 63 of the stirring assembly 6, and includes a heat inlet pipe 631 and a heat recovery pipe 632 in communication with the heat inlet pipe 631; the rotating shaft 63 and the paddle 62 are hollow and filled with heat conducting oil or water as heat transfer medium; hot water or steam supplied by the water source heat pump flows into the heat inlet pipe 631, and the heat is conducted to the outer surface of the rotating shaft 63 and the paddle 621 through the heat transfer medium in the rotating shaft 63 and each paddle piece 621, and then to the sludge, thereby playing an internal heating role; the cooled heat transfer medium then flows back to the water source heat pump from the heat recovery pipe 632. Further, the user can select the heat transfer medium according to the actual fermentation needs. Due to the characteristics of the medium, heat conducting oil is preferably used as the heat transfer medium for high-temperature fermentation (55°C), and water is preferably used as the heat transfer medium for medium-temperature fermentation (35°C). When this heating method is used, the stirrer 61 is connected to the rotating shaft 63 through a rotating joint, and the rotating shell of the rotating shaft 63 does not conflict with the heat transfer circulating pipe.

[0066] When the heating structure arranged inside the fermentation container 1 is an electric heat tracing tape, the electric heat tracing tape 634 is wound inside the rotating shaft 63 and the paddle 621 as a heat transfer medium, and the heat is directly conducted to the outer surface of the rotating shaft 63 and the paddle 621, and then to the sludge, thereby playing an internal heating role. The electric heat tracing tape 634 has various arrangement forms, and can be wound in the middle of the rotating shaft 63 and the paddle 621, or embedded in the middle of the rotating shaft 63 and the paddle 621 in a vein-like manner. Further, the user can configure according to the volume of the fermentation container 1 and the selected size of the stirrer 61. Specifically, the connection between the rotating shaft 63 and the paddle 621 is flexible, so that the heating effect is not affected when the paddle 621 is raised and lowered. When this heating method is used, the stirrer is connected to the rotating shaft through a current collecting ring, and the rotation of the rotating shaft 63 does not affect the power supply and heat transfer of the electric heat tracing tape.

[0067] The medicament regulating assembly 7 comprises a ring-shaped medicament distributor 71, a medicament feeding pipe 72 provided with a metering pump 74, a medicament tank 75, an inert gas storage tank 76, an inert gas feeding pipe 77, and inert gas stripping nozzles 78. The medicament tank 75 is located outside the fermentation container 1 and is connected to the ring-shaped medicament distributor 71 located inside the fermentation container 1 through the medicament feeding pipe 72 penetrating the fermentation container 1. The ring-shaped medicament distributor 71 is arranged 20-100 cm below the liquid level in the fermentation container 1, and a plurality of medicament nozzles 73 for uniformly spraying medicament into the sludge are distributed on the ring-shaped medicament distributor 71. The medicament in the medicament tank 75 includes one or more of alkaline solution, acid solution, and trace element solution. The inert gas storage tank 76 is located in the medicament tank 75 and is in communication with the inert gas feeding pipe 77. The inert gas feeding pipe 77 is horizontally arranged at the bottom of the fermentation container 1 and is uniformly provided with a plurality of inert gas stripping nozzles 78. The inert gas stripping nozzles 78 can spray nitrogen, helium, or argon at a suitable flow rate to strip the residual dissolved oxygen in the sludge and maintain the anaerobic environment of the sludge fermentation. The metering pump 74 pumps the medicament in the medicament tank 75 to the medicament feeding pipe 72 at a suitable flow rate, and the medicament is uniformly sprayed into the sludge through the plurality of medicament nozzles 73 distributed on the ring-shaped medicament distributor 71, and then fully mixed with the sludge under the action of the hydraulic circulating assembly 4 and the stirring assembly 6. The monitoring and control assembly 9 adjusts the flow rates of the alkaline solution, acid solution, and trace element solution in the medicament regulating assembly 7 in real time through the metering pump 74, so that the pH value of the sludge in the fermentation container 1 is maintained at the most suitable 8-10, and the concentrations of the trace elements in the sludge are maintained as follows: Cu 2+ , 20-65 mmol / L; Mn 2+ , 2.5-6.0 mmol / L; B 3+ , 15.0-28.5 mmol / L, Mo 6+ , 4.0-6.2 mmol / L; W 6+ , 7.0-12.2 mmol / L; Ni 2+ , 3.0-5.5 mmol / L; Co 2+ , 10.0-18.3 mmol / L; Zn 2+ , 25.5-35.0 mmol / L; Ca 2+ , 10.5-30.5 mmol / L. Based on years of work experience, the inventors have found through experiments that trace elements are key components of the activity centers of various microbial reductase and denitrification and phosphorus removal key genes. These elements have their own functions, and there is also a synergistic effect between some elements. They can improve the hydrolysis process of soluble proteins, fats, and polysaccharides in the fermentation process and promote the activity regulation of microbial intracellular enzymes for synthesizing carboxylic acids from hydrolysis products. When the pH value of the sludge in the fermentation container 1 is maintained at the most suitable 8-10 and the above-mentioned trace element composition range, the activity (represented by ATP) of acid-producing bacteria is increased by an average of 1.3-1.5 times. Specifically, the added Cu2+ Mn 2+ B 3+ Zn 2+ Co 2+ Cu 2+ Mo 6+ Ni 2+ Zn 2+ Cu 2+ Ca 2+ W 6+ Co 2+ Ca

[0068] The venting assembly 8 includes a plurality of venting branch pipes 81, a venting transfer box 82 and a venting pipe 83. The inlet of the venting branch pipe 81 faces downward and is spaced 3-30 cm from the bottom surface of the fermentation container 1. The venting transfer box 82 is a hollow box body, the side wall of which is connected with the plurality of venting branch pipes 81. One end of the venting pipe 83 is connected with the venting transfer box 82, and the other end penetrates out of the venting opening 103, which is used to periodically discharge sludge and completely vent the sludge and carboxylic acid in the fermentation container 1 during device maintenance.

[0069] The monitoring electric control assembly 9 comprises a thermometer 91, a pH meter 92, a water quality monitoring probe 93 and a controller, the thermometer 91, the pH meter 92 and the water quality monitoring probe 93 are respectively embedded in different instrument monitoring ports 112, for continuously monitoring the temperature, pH value and water quality of the sludge in the fermentation container 1; the water quality monitoring probe 93 can simultaneously monitor the concentrations of organic matter COD, total nitrogen TN, total phosphorus TP, total organic acid root, acetic acid root, propionic acid root, butyric acid root and valeric acid root in the sludge; the controller of the monitoring electric control assembly 9 can adjust the process parameters of the sludge feeding assembly 2, the hydraulic circulation assembly 4, the heating and heat preservation assembly 5, the stirring assembly 6 and the medicament control assembly 7 in real time according to the monitoring results, so that the temperature of the sludge in the fermentation device is stably maintained at 35-55℃, and the carboxylic acid of a predetermined concentration is generated; the fermentation container 1 can adopt a batch type or a continuous type operation mode, and the sludge feeding amount and the sludge discharging amount are adjusted and controlled by the monitoring electric control assembly 9.

[0070] The concentration of the sludge organic matter COD in the fermentation container 1 and the concentration S of the sludge hydrolysis product carboxylic acid V The calculation formula is:

[0071]

[0072] S V The generated carboxylic acid concentration is calculated in terms of COD; S P The organic matter concentration in the sludge to be treated is calculated in terms of COD; S h The reaction hydrolysis product concentration contains the concentrations of protein, fat and carbohydrate, and is calculated in terms of COD; N1 is the frequency output power of the circulating pump hydraulic stirring; N2 is the frequency output power of the mechanical stirring of the stirrer; a is the stirring intensity adjustment coefficient of the stirrer; k m,h The maximum specific utilization rate of the hydrolysis product; X h The carboxylic acid producing bacteria microbial concentration; K S,h The half-saturation constant of the growth of the carboxylic acid producing bacteria; K I,h The influence coefficient of the carboxylic acid concentration on the growth of the carboxylic acid producing bacteria; k m,v The maximum specific utilization rate of the carboxylic acid; X v The methanogen microbial concentration; k is the maximum specific substrate removal rate constant; k d,h The endogenous decay rate of the carboxylic acid producing bacteria; k d,v The endogenous decay rate of the methanogen.

[0073] The controller of the monitoring electric control assembly 9 can calculate the generated carboxylic acid concentration according to the fermentation tank sludge properties (protein, carbohydrate and amino acid ingredient composition), carboxylic acid producing bacteria microorganisms, methanogenic bacteria activity and endogenous decay rate, variable frequency stirring output power and intensity adjustment coefficient, etc. using the above formula; meanwhile, the carboxylic acid concentration generated by the fermentation device can be dynamically adjusted according to the need, such as adjusting the reaction progress in the fermentation tank by adjusting the angle of each blade of the stirrer, or generating a specific ratio of carboxylic acid mixed solution (acetic acid concentration: propionic acid concentration can be 1:1, 2:1, etc. for adjusting the biological reaction tank) by adjusting the ratio and concentration of protein, carbohydrate and amino acid in the sludge. When the recovered carboxylic acid is mainly acetic acid (the actual experiment shows that the highest acetic acid accounts for up to 78% of the total carboxylic acid, and the propionic acid is less than 18%), the fermentation device can make the acetic acid yield increase by an average of 4.5 times compared with the traditional technology, and the greenhouse gas generation amount is reduced by an average of 82%; when the recovered carboxylic acid is mainly propionic acid (the highest propionic acid accounts for up to 63% of the total carboxylic acid), the fermentation device can make the propionic acid yield increase by an average of 3.2 times compared with the traditional technology, and the greenhouse gas is reduced by an average of 71%.

[0074] The application also provides a fermentation method for recovering carboxylic acid while reducing greenhouse gas emission, which comprises the following steps:

[0075] Step one, the fermentation device for recovering carboxylic acid while reducing greenhouse gas emission is arranged on the ground near the sewage treatment facility; the fermentation device is the fermentation device described above, which will not be described here again, and the specific distance and relative position of the fermentation device from the sewage treatment facility are not particularly limited, and the actual terrain is referred to for the convenience of construction, labor saving and material saving;

[0076] Step two, the sludge to be treated is transported into the fermentation tank 1 by using the sludge feeding assembly 2 connected to the lower part of the fermentation tank 1; the sludge to be treated is the primary sludge or residual sludge generated by the sewage treatment facility, and the water content is 95%-99.5%, and the sludge feeding flow is adjusted according to the operation demand of the device, and the sludge fermentation residence time in the fermentation tank is generally controlled to be 5-8d;

[0077] Step three, the sludge in the fermentation tank 1 is pumped and returned by using the hydraulic circulation assembly 4 to realize the stirring of the sludge in the fermentation tank 1 and improve the hydraulic circulation flow state of the sludge; the sludge in the fermentation tank 1 is heated and kept warm by using the heating and keeping warm assembly 5; the sludge in the fermentation tank 1 is fully stirred by using the stirring assembly 6 to make the sludge evenly distributed; the medicament is transported into the fermentation tank 1 by using the medicament control assembly 7 to realize the control of the growth and metabolism environment of the microorganisms in the sludge, improve the fermentation carboxylic acid production efficiency and improve the quality of the produced carboxylic acid;

[0078] Wherein, when the circulating pump 41 is working, the sludge is pumped from the bottom of the fermentation container 1 through the circulating sludge inlet branch pipe 44 and the circulating sludge inlet main pipe 42, and then is pumped to the circulating sludge outlet pipe 46 through the pressurization of the circulating pump 41, and is finally sprayed out through the circulating sludge outlet 47 at high speed. The working flow rate of the circulating pump 41 is 10-50 times of the effective volume of the fermentation container 1 per 24 hours. 3 / h 3 ÷24h 2+ , the hydraulic circulation of the sludge in the fermentation container 1 is realized, and the hydraulic flow state of the sludge is optimized.

[0079] Step four, the temperature, pH value and water quality of the sludge in the fermentation container 1 are continuously monitored through the monitoring of the electric control assembly 9, and the process parameters of the sludge inlet assembly 2, the hydraulic circulation assembly 4, the heating and insulation assembly 5, the stirring assembly 6 and the medicament control assembly 7 are adjusted in real time according to the monitoring results, so that the fermentation device is in the optimal operating condition to produce the predetermined concentration of carboxylic acid. The optimal operating condition includes that the sludge fermentation residence time in the fermentation container 1 is 8 days, the temperature of the sludge in the fermentation container 1 is stably maintained at 35°C, the sludge is uniformly distributed, the pH value of the sludge in the fermentation container 1 is maintained at 10, and the concentrations of the trace elements in the sludge are as follows: Cu 2+ , 20-65 mmol / L; Mn 2+ , 2.5-6.0 mmol / L; B 3+ , 15.0-28.5 mmol / L, Mo 6+ , 4.0-6.2 mmol / L; W 6+ , 7.0-12.2 mmol / L; Ni 2+ , 3.0-5.5 mmol / L; Co 2+ , 10.0-18.3 mmol / L; Zn 2+ , 25.5-35.0 mmol / L; Ca 2+ , 10.5-30.5 mmol / L

[0080] Step five, the carboxylic acid supernatant produced by fermentation is decanted from the top of the fermentation container 1 through the water decanting assembly 3, and is transported to the aerobic tank of the sewage treatment facility to promote the nitrogen and phosphorus removal process.

[0081] Further, the monitoring electric control assembly 9 calculates the concentration of the carboxylic acid produced by the fermentation container 1 according to the process parameters and the above formula, or dynamically adjusts the process parameters of the fermentation device according to the predetermined concentration of the carboxylic acid.

[0082] In this embodiment, the average moisture content of the sewage plant primary sludge or excess sludge actually entering the fermentation device is 97%-98%, the sludge fermentation residence time in the fermentation container is controlled to be 5d; and the flow rate of the circulating pump 41 in the hydraulic circulation assembly 4 and the rotating speed of the stirrer 61 in the stirring assembly 6 are adjusted in real time, so that the data monitored by the thermometers 91, the pH meters 92 and the water quality monitoring probes 93 at different positions tend to be consistent; at the same time, the heating and heat preservation assembly 5 is adjusted in real time, so that the temperature of the sludge in the fermentation container 1 is stably maintained at 35℃; in addition, the flow rate of the metering pump 74 of the reagent regulation assembly 7 is adjusted in real time, so that the pH value of the sludge in the fermentation container 1 is maintained at 10, and the concentrations of trace elements in the sludge are as follows: Cu 2+ , 40mmol / L; Mn 2+ , 3.0mmol / L; B 3+ , 20.0mmol / L, Mo 6+ , 5.0mmol / L; W 6+ , 9.0mmol / L; Ni 2+ , 4.0mmol / L; Co 2+ , 15.0mmol / L; Zn 2+ , 30.0mmol / L; Ca 2+ , 20.0mmol / L.

[0083] The fermentation device for recovering carboxylic acid while reducing greenhouse gas emissions according to the embodiment of this example can continuously output carboxylic acid mixed supernatant with a COD concentration of 19807mg / L, in which the concentrations of acetate, propionate, butyrate and pentanoate are 6932mg / L, 3960mg / L, 3896mg / L and 3373mg / L respectively. After continuously conveying the carboxylic acid to the anoxic tank inside the reaction tank of the sewage treatment plant with a treatment capacity of 15000m 3 / d, the COD of the anoxic tank can be stably increased by 58.1mg / L, which significantly promotes denitrification and phosphorus removal, saves a large amount of additional carbon source, and saves direct economic benefits of carbon source up to 1.31 million yuan / year, while reducing indirect economic benefits of greenhouse gas emissions such as methane up to 5 million yuan / year.

[0084] Example 2

[0085] The fermentation device for recovering carboxylic acid while reducing greenhouse gas emissions according to this embodiment has the same basic structure and use method as Example 1, and specifically:

[0086] The fermentation container 1 is made of 304 or SS316 stainless steel and has a cylindrical or egg-shaped overall shape;

[0087] The front end of the sludge inlet pipe 21 is connected with a sludge inlet pump for pumping municipal sludge or kitchen waste; the sludge and kitchen waste entering the device have a water content of 95%-97%; the flow of the sludge inlet pump and the sludge outlet pump can be adjusted according to the operation requirements of the device, so that the residence time of the sludge in the fermentation container 1 is 8 days in the working condition of continuously feeding primary sludge and discharging water by decanting, and the temperature of the sludge in the fermentation container 1 is stably maintained at 35°C.

[0088] The notch of the scum collecting tank 35 is higher than the liquid surface by 0.5-5 cm.

[0089] The heating facility 51 includes an electric heat tracing band wound on the sludge inlet pipe 21 or the side wall of the fermentation container 1, a hot water coil heated by a water source heat pump, or a heating rod arranged inside the fermentation container 1.

[0090] The multi-stage paddle 62 is divided into three layers, which are all arranged in the lower middle part of the fermentation container 1 and used for fully stirring the sludge in the fermentation container 1; the heat-conducting circulating pipe 65 spreads heat to the sludge through the rotating shaft 63 and each paddle 621 by the hot steam flowing through the pipe, thereby playing a heating role.

[0091] The multi-stage paddle in the embodiment changes the lifting angle of the paddle plate step by step with the fermentation time, as shown in Figure 8 .

[0092] The annular medicine distributor 71 is arranged below the liquid surface of the fermentation container 1 by 20-100 cm.

[0093] The medicine in the medicine tank 75 includes lye, acid liquid or trace element solution; the acid and lye control the optimal pH value in the fermentation container to be pH=10; the trace element solution controls the concentration of trace elements in the fermentation container to be Cu 2+ 60 mmol / L, Mn 2+ 6.0 mmol / L, B 3+ 28.0 mmol / L, Mo 6+ 6.0 mmol / L, W 6+ 12.0 mmol / L, Ni 2+ 5.0 mmol / L, Co 2+ 18.0 mmol / L, Zn 2+ 35.0 mmol / L, Ca 2+ 30.0 mmol / L; the inert gas stripping spout 78 can spray helium at a suitable flow rate for stripping the residual dissolved oxygen in the sludge and maintaining the anaerobic environment of the sludge fermentation.

[0094] The inlet of the vent branch pipe 81 faces downward and is spaced from the bottom surface of the fermentation container 1 by 3-30 cm.

[0095] The fermentation device for recovering carboxylic acid and reducing greenhouse gas emission according to the embodiment can continuously output carboxylic acid with a COD concentration of 37931 mg / L. The concentrations of acetate, propionate, butyrate and pentanoate in the mixed supernatant of the carboxylic acid are 8638 mg / L, 8891 mg / L, 8327 mg / L and 8576 mg / L, respectively. The carboxylic acid is continuously fed into a biological reaction tank of a sewage treatment plant with a treatment capacity of 500,000 m 3 / d, the expression of key genes for denitrification and phosphorus removal is enhanced, and the key genes for phosphorus removal mainly include ppk (encoding polyphosphate kinase) which catalyzes the conversion of ATP to polyphosphate, and phaC (encoding PHA synthase) which is responsible for the synthesis of poly-β-hydroxybutyric acid. The polyphosphorus bacteria provide energy in anaerobic conditions by storing PHA. The key gene for denitrification is norC (encoding NO reductase) which reduces NO to N2O under anoxic or anaerobic conditions. For example, Figure 10 , after adding the sludge fermentation liquor, the abundance of the two key phosphorus removal genes in the aerobic tank and the anaerobic tank is significantly improved.

[0096] After the recovered carboxylic acid is added to the biological reaction tank of the sewage treatment plant, the overall COD of the influent is increased by 59.6 mg / L, which significantly promotes denitrification and phosphorus removal, saves a large amount of additional carbon source, and saves the direct economic benefit of carbon source by 6.63 million yuan / year, while reducing the indirect economic benefit of greenhouse gas emission such as methane by 15 million yuan / year.

[0097] Embodiment 3

[0098] The fermentation device for recovering carboxylic acid and reducing greenhouse gas emission according to the embodiment has the same basic structure and use method as embodiment 1, and the specific implementation manner is as follows:

[0099] The fermentation container 1 is made of 304 stainless steel and has a cylindrical shape.

[0100] The front end of the sludge inlet pipe 21 is connected with a sludge pump for pumping primary sludge or residual sludge in the sewage treatment facility. The moisture content of the primary sludge or residual sludge is 98%. The flow rate of the sludge pump can be adjusted according to the operation requirements of the device, so that the residence time of the sludge in the fermentation container 1 is 6 days under the condition of continuously feeding the primary sludge and discharging the carboxylic acid by decanting, and the temperature of the sludge in the fermentation container 1 is stably maintained at 35°C.

[0101] The slot of the scum collection tank 35 is higher than the liquid surface by 3 cm.

[0102] The heating facility 51 is in the form of a heating rod arranged inside the fermentation container 1.

[0103] The multi-stage paddle 62 is divided into 2-5 layers and arranged in the middle and lower parts of the fermentation container 1.

[0104] The annular medicine distributor 71 is arranged 20-100 cm below the liquid level in the fermentation container 1.

[0105] The medicine in the medicine tank 75 includes alkaline solution, acid solution or trace element solution; the acid and alkaline solution control the optimal pH value in the fermentation container to be pH=10; the trace element solution controls the trace element concentration in the fermentation container to be: Cu 2+ 65 mmol / L; Mn 2+ 2.5 mmol / L; B 3+ 15.0 mmol / L; Co 2+ 10.0 mmol / L; Zn 2+ 25.5 mmol / L; the inert gas blowing nozzle 78 can spray helium at a suitable flow rate to blow off the residual dissolved oxygen in the sludge and maintain the anaerobic environment of the sludge fermentation.

[0106] The inlet of the vent branch pipe 81 is downward and spaced 20 cm from the bottom surface of the fermentation container 1.

[0107] The fermentation device for recovering carboxylic acid while reducing greenhouse gas emission implemented according to the example can continuously output carboxylic acid mixture with COD concentration of 28971 mg / L. The carboxylic acid mixture contains acetic acid, propionic acid, butyric acid and valeric acid with concentrations of 10138 mg / L, 8691 mg / L, 2657 mg / L and 2877 mg / L respectively.

[0108] The application method process flow of the fermentation device for recovering carboxylic acid while reducing greenhouse gas emission implemented according to the example is shown in Figure 9 The fermentation device collects all primary sludge and residual sludge from the primary sedimentation tank and sludge concentration tank in the sewage treatment plant to ferment and recover carboxylic acid, controls the reaction parameters to avoid the production of methane and other greenhouse gases during sludge fermentation, and adds the produced carboxylic acid to the biological reaction tank to realize the coordinated removal of COD, N, P and other pollutants and CO2, N2O, NO and other greenhouse gases in the sewage.

[0109] As Figure 11 The carboxylic acid is continuously transported to the treatment capacity of 30000 m 3 / d sewage treatment plant biological reactor (including anaerobic tank, anoxic tank and aerobic tank), after adding sludge fermentation liquid, the abundance of the main phosphorus removal key microorganisms in the anaerobic tank was significantly improved, Flavobacterium, Candidatus Accumul ibacter, Thauera and Dechloromonas, their abundance increased by 115%-149% compared with the blank group. At the same time, the addition of carboxylic acid also increased the abundance of key denitrification microorganisms, including Hyphomicrobium, Terrimonas and Pseudomonas. Figure 12 As shown in the results, after adding sludge fermentation broth, the abundance of the main denitrifying microorganisms in the reaction tank, Hyphomicrobium, Terrimonas, and Pseudomonas, increased by 106%-112% compared to the blank control. The carboxylic acids produced by the new process achieve clean and efficient wastewater biological treatment. Fermentation broth containing a certain amount of propionic acid (which accounts for more than 30% of the total carboxylic acids) achieves better nitrogen and phosphorus removal rates (an average increase of 25.4% and 31.3%, respectively), reduces CO2, N2O, NO, and sludge production (an average reduction of 71.1%, 65.3%, 23.4%, and 43.1%, respectively), and reduces the addition of chemical carbon sources in wastewater treatment plants by 38-100%. The process works as follows: the fermentation broth contains trace elements such as propionic acid and copper ions. The former enables the functional microorganisms to synthesize more polyhydroxyvaleric acid (PHV) during the anaerobic stage, resulting in the rate of its oxidative decomposition to generate energy and reducing power during the aerobic and anoxic stages more closely matching the rate of phosphorus absorption and denitrification, promoting phosphorus absorption and denitrification and reducing the production of CO2, N2O, and NO. The latter, a key component in the active center of various denitrifying reductases, promotes denitrification and reduces the accumulation of intermediate products. The input of this carboxylic acid can steadily increase the COD of the bioreactor by 57.2 mg / L, significantly promoting nitrogen and phosphorus removal, and saving a large amount of external carbon source addition. The direct economic benefits generated by the carbon source savings amount to 3.23 million yuan / year, while the indirect economic benefits generated by the reduction of greenhouse gas emissions such as methane amount to 8 million yuan / year.

[0110] Table 1 Experimental parameters of each embodiment (trace element concentration unit mmol / L)

[0111]

[0112] Table 2 Experimental results of each embodiment and control group (concentration unit mg / L)

[0113] Experimental results COD Acetate Propionate Butyrate Valerate Example 1 19807 6932 3960 3896 3373 Control 1 14231 3952 2643 3247 2195 Example 2 37931 8638 8891 8327 8576 Control 2 26094 5853 6231 6127 6098 Example 3 28971 10138 8691 2657 2877 Control 3 20155 6453 5337 2319 2501

[0114] In summary, the fermentation device for recovering carboxylic acid while reducing greenhouse gas emission of the present application is used for collecting and processing all primary sludge and excess sludge from a sewage treatment plant to ferment and recover carboxylic acid, and can also ferment and produce carboxylic acid by mixing municipal kitchen waste and sludge, generate a specific ratio of carboxylic acid mixture through the operation and reaction parameter control of the fermentation device, significantly reduce the emission of methane and other greenhouse gases generated during fermentation, and the recovered carboxylic acid mixture can be added to the biological reaction tank of the sewage treatment plant to achieve clean and ultra-clean sewage treatment and the simultaneous and efficient removal of greenhouse gases such as CO2, N2O and NO during the reaction process, and the supernatant can be separated and purified to recover carboxylic acid industrial products to achieve resource recovery.

[0115] Compared with the effect of commonly purchased acetic acid chemicals as a supplemental carbon source in sewage treatment plants, the fermentation liquid containing a certain amount of propionic acid (which accounts for more than 30% of the total carboxylic acid) generated by the fermentation device of the present application from organic waste such as sludge and kitchen waste can obtain better nitrogen and phosphorus removal rates (an average increase of 25.4% and 31.3%, respectively), while producing less N2O, CO2 and sludge (an average reduction of 71.1%, 23.4% and 43.1%, respectively). The mechanism by which the increase in the proportion of propionic acid greatly improves the efficiency of sewage treatment is that propionic acid can make the sewage treatment functional microorganisms synthesize more polyhydroxyvalerate (PHV) in the anaerobic stage, so that the rate of energy and reducing power produced by its oxidation and decomposition in the aerobic and anoxic stages is more matched with the rate of phosphorus absorption and denitrification, promoting phosphorus absorption and denitrification and reducing the production of CO2 and N2O.

[0116] Compared with the prior art, the fermentation device and method for recovering carboxylic acid while reducing greenhouse gas emission of the present application have at least the following advantages:

[0117] 1. Substrate metabolism regulation and greenhouse gas emission reduction

[0118] The present application combines hydraulic circulation and medicament regulation, and realizes uniform disturbance and reflux of sludge through the hydraulic circulation assembly, thereby improving the completeness and efficiency of the sludge fermentation process. The substrate metabolism regulation includes the regulation of pH value, temperature and trace element concentration in the fermentation device, which ensures the stability and optimization of the fermentation environment, promotes the conversion of sludge into efficient organic carbon sources (such as carboxylic acids such as acetic acid, propionic acid, butyric acid and valeric acid), and through the addition of the above-mentioned efficient organic carbon sources to the biological reaction tank, the abundance of denitrifying key microorganisms (such as Hyphomicrobium, Stenomphium and Pseudomonas, with an abundance increase of 6%-12%) can be significantly improved, the expression of denitrification key genes (such as polyphosphate kinase, PHA synthase and NO reductase) can be enhanced, denitrification can be promoted, the metabolic balance of functional microorganisms in the reaction tank can be regulated, the metabolic activity of non-functional microorganisms (such as methanogenic bacteria) can be inhibited, the emission of greenhouse gases such as methane can be avoided, and the goal of carbon emission reduction can be achieved.

[0119] 2. Integrated fermentation and product decanting separation

[0120] The integrated design of the fermentation container, decanting assembly and skimmer realizes efficient separation and direct utilization of fermentation products. The decanting assembly transports the fermentation-produced carboxylic acid supernatant to the nitrification tank, promoting the denitrification and phosphorus removal process, while the residual sludge after fermentation continues to enter the original sludge treatment process. This design simplifies the operation process, reduces the secondary treatment steps, and enables the fermentation products to be directly and efficiently applied to the wastewater treatment system.

[0121] 3. Energy-saving and environmentally-friendly insulation design

[0122] The present application maintains the temperature in the fermentation container between 35-55℃ using insulation equipment, fully utilizing the heat generated by sludge fermentation, without the need for a large amount of additional heat input. The present application provides a variety of low-energy insulation and heat exchange methods, which can be selected according to actual needs. Compared with the high-energy additional heating method of the prior art, the present application significantly reduces energy consumption, saves resources, and improves the environmental friendliness and economy of the device.

[0123] 4. High degree of automation and real-time monitoring

[0124] The present application studies the carboxylic acid concentration S V The calculation formula allows continuous monitoring of the temperature, pH and water quality inside the fermentation container by monitoring the electronic control assembly, and real-time adjustment of the operating parameters of each component based on the monitoring results to ensure that the device is in the best operating state. The high degree of automation and real-time monitoring function improves the operational stability and ease of operation of the device, reducing manual intervention and operational errors.

[0125] 5. No need for additional microbial strains

[0126] The integrated device of the present application can operate automatically after starting without the need for additional microbial strains, relying on its own system circulation and regulation to achieve efficient fermentation of sludge. This not only reduces operating costs, but also reduces the use of chemical agents and potential environmental impact, making the entire treatment process more environmentally friendly.

[0127] For those skilled in the art, various corresponding changes and modifications can be made to the above-described technical solutions and concepts, and all such changes and modifications should be within the scope of protection of the claims of the present application.

Claims

1. A fermentation device for recovering carboxylic acid and reducing greenhouse gas emissions, characterized in that: The fermentation container (1) comprises a fermentation container (1), a mud inlet assembly (2), a decanting assembly (3), a hydraulic circulation assembly (4), a heating and heat preservation assembly (5), a stirring assembly (6), a drug regulating assembly (7) and a monitoring and electronic control assembly (9); a mud inlet (101) and a hydraulic circulation inlet (105) are provided at the lower part of the side wall of the fermentation container (1), a hydraulic circulation outlet (106) is provided at the middle and upper part of the side wall, and a carboxylic acid outlet (102) is provided at the upper part of the side wall; the mud inlet assembly (2) is connected to the inlet The mud outlet (101) extends into the interior of the fermentation container (1); the decanting component (3) is arranged at the top of the fermentation container (1) and is connected to the carboxylic acid outlet (102) to decant the fermented carboxylic acid from the top of the fermentation container (1) and transport it to the biogas tank; the hydraulic circulation component (4) is connected to the hydraulic circulation inlet (105) and the hydraulic circulation outlet (106), and the sludge is sucked and returned to the fermentation container (1) through the circulation pump (41) to realize the ) agitation of the sludge in the fermentation container (1); the heating and heat preservation component (5) is arranged on the side wall of the fermentation container (1) for heating and heat preservation of the sludge in the fermentation container (1); the stirring component (6) fully stirs the sludge through the multi-stage blades (62) arranged in the fermentation container (1); the drug control component (7) is connected to the fermentation container (1) and delivers the drug into the fermentation container (1); the monitoring electronic control component (9) includes a controller and a monitoring instrument arranged in the fermentation container (1), the monitoring instrument continuously monitors the temperature, pH value and water quality of the sludge in the fermentation container (1), and the controller adjusts the process parameters of the mud feeding component (2), the hydraulic circulation component (4), the heating and heat preservation component (5), the stirring component (6) and the drug control component (7) in real time according to the monitoring results to ensure that the temperature of the sludge in the fermentation container (1) is stably maintained at 35-55°C and a predetermined concentration of carboxylic acid is generated; the generated carboxylic acid concentration S V The calculation formula is: S V is the concentration of carboxylic acid produced, calculated as COD; S P is the concentration of organic matter in the sludge to be treated, measured in COD; S h is the concentration of the reaction hydrolysis product, including protein, fat and carbohydrate concentration, measured in COD; N1 is the output power of the circulating pump hydraulic stirring frequency conversion; N2 is the output power of the stirrer mechanical stirring frequency conversion; a is the stirrer stirring intensity adjustment coefficient; k m,h is the maximum specific utilization rate of hydrolysis products; X h is the concentration of carboxylic acid-producing bacteria; K S,h is the half-saturation constant of carboxylic acid-producing bacteria growth; K I,h k is the effect coefficient of carboxylic acid concentration on the growth of carboxylic acid-producing bacteria; m,v is the maximum specific utilization rate of carboxylic acid; X v is the concentration of methanogen microorganisms; k is the maximum specific substrate removal rate constant; k d,h k is the endogenous decay rate of carboxylic acid-producing bacteria; d,v is the endogenous decay rate of methanogens.

2. The fermentation device for recovering carboxylic acid and simultaneously reducing greenhouse gas emissions according to claim 1, characterized in that: The mud inlet assembly (2) comprises a mud inlet pipe (21), a mud inlet pump with adjustable flow rate, and a mud inlet pipe bracket (22). The mud inlet pipe (21) extends into the fermentation container (1) through the mud inlet opening (101) on the side wall of the fermentation container (1) until the mud inlet pipe outlet (23) is located in the central area of ​​the fermentation container (1). The mud inlet pipe bracket (22) is supported below the mud inlet pipe (21). The mud inlet pump is connected to the inlet of the mud inlet pipe (21) and is used to pump primary sludge or residual sludge generated by the sewage treatment facility. The monitoring electronic control assembly (9) regulates the flow rate of the mud inlet pump in the mud inlet assembly (2) in real time according to the monitoring results, and controls the sludge fermentation residence time in the fermentation container (1) to be 5-8 days, so that the mud inlet flow rate matches the carboxylic acid production efficiency.

3. The fermentation device for recovering carboxylic acid and simultaneously reducing greenhouse gas emissions according to claim 1, characterized in that: The fermentation container (1) is provided with a slag discharge port (104) at the upper portion of the side wall, and the carboxylic acid outlet (102) is connected to the biogas tank of the sewage treatment facility for conveying the fermented carboxylic acid clarified liquid to the biogas tank; the decanting assembly (3) comprises a decanter (31), a carboxylic acid pipeline (32), a slag skimmer (34), and a scum collecting tank (35); the decanter (31) comprises a rectangular or annular decanter (311), the notch of the decanter (311) being arranged at the top of the fermentation container (1), the carboxylic acid produced by sludge fermentation is clarified and layered at the top of the sludge, and the clarified liquid at the top flows into the decanter through the notch of the decanter (311) in an overflow manner. trough (311); one end of the carboxylic acid pipeline (32) is connected to the trough body of the decanting trough (311), and the other end is connected to the carboxylic acid outlet (102); the skimmer (34) is arranged on the top of the fermentation container (1), driven by the skimmer motor (341), and is used to skim the scum on the surface of the carboxylic acid clarified liquid into the scum collection trough (35); the trough opening of the scum collection trough (35) is 0.5-5 cm higher than the liquid surface of the carboxylic acid clarified liquid, the trough body of the scum collection trough (35) is inclined downward, and the lowest point is connected to the scum discharge port (104), and the collected scum is discharged from the fermentation container (1) through the scum discharge port (104).

4. The fermentation device for recovering carboxylic acid and simultaneously reducing greenhouse gas emissions according to claim 1, characterized in that: The hydraulic circulation assembly (4) includes a circulation pump (41), a circulation mud inlet main pipe (42), a circulation mud inlet distribution head (43), a circulation mud inlet branch pipe (44) and a circulation mud outlet pipe (46); the circulation mud inlet distribution head (43) is located in the central area of ​​the bottom of the fermentation container (1), and the circulation mud inlet branch pipe (44) is radially and evenly connected to the periphery of the circulation mud inlet distribution head (43); one end of the circulation mud inlet main pipe (42) is connected to the circulation mud inlet distribution head (43) The circulating pump (41) is connected to the fermentation container (1), and the other end passes through the hydraulic circulation inlet (105); the circulating pump (41) is arranged outside the fermentation container (1), the inlet of the circulating pump (41) is connected to the outlet of the circulating mud inlet main pipe (42), and the outlet of the circulating pump (41) is connected to the circulating mud outlet pipe (46) located in the upper middle part of the fermentation container (1); the circulating mud outlet pipe (46) passes through the fermentation container (1) from the hydraulic circulation outlet (106) and is provided with a plurality of circulating mud outlets (47).

5. The fermentation device for recovering carboxylic acid and simultaneously reducing greenhouse gas emissions according to claim 1, characterized in that: The heating and heat-insulating component (5) includes a heating facility (51) and a heat-insulating layer; the heating facility (51) is an electric heating tape wound around the mud inlet pipe (21) of the mud inlet component (2) and / or the side wall of the fermentation container (1) or a hot water coil heated by a water source heat pump, and / or a heating structure arranged inside the fermentation container (1); the heat-insulating layer is arranged on the side wall of the fermentation container (1) to reduce heat loss from the fermentation container (1); the monitoring electronic control component (9) adjusts the heating and heat-insulating component (5) in real time so that the temperature of the sludge in the fermentation container (1) is stably maintained at 35-55°C.

6. The fermentation device for recovering carboxylic acid and simultaneously reducing greenhouse gas emissions according to claim 1, characterized in that: The top surface of the fermentation container (1) is provided with a mixer installation hole (108); the stirring assembly (6) comprises a mixer (61) with variable frequency and adjustable speed, a multi-stage blade (62), a rotating shaft (63) and a heat transfer circulation pipe (65); the mixer (61) is eccentrically installed in the mixer installation hole (108), and its rotating shaft (63) extends into the fermentation container (1); the multi-stage blade (62) is installed at the middle and lower part of the rotating shaft and is evenly divided into 2-5 layers for fully stirring the sludge in the fermentation container (1); The rotation speed of the multi-stage blades (62) is 20-60 r / min; each layer of the multi-stage blades (62) includes a plurality of blades (621), a hydraulic support rod (622) and a flexible connector (623); the plurality of blades (621) are connected by the flexible connector (623); the angle between the plurality of blades (621) is adjusted by the extension and contraction of the hydraulic support rod (622); when the sludge stirring intensity needs to be increased, the angle between the plurality of blades (621) is increased; otherwise, the angle is reduced.

7. The fermentation device for recovering carboxylic acid and simultaneously reducing greenhouse gas emissions according to claim 6, characterized in that: The stirring assembly (6) further includes a heat transfer circulation pipe (65), which passes through the rotating shaft (63) and the plurality of blades (621). The heat transfer circulation pipe (65) includes a heat inlet pipe (631) and a heat return pipe (632) connected to the heat inlet pipe (631). A heat transfer medium supplied by a water source heat pump flows into the heat inlet pipe (631), and heat is transferred to the sludge through the rotating shaft (63) and the plurality of blades (621). Cooling water flows back to the water source heat pump from the heat return pipe (632).

8. The fermentation device for recovering carboxylic acid and simultaneously reducing greenhouse gas emissions according to claim 1, characterized in that: The drug regulating component (7) includes a drug distributor, a drug delivery pipe (72) provided with a metering pump (74), and a drug box (75); the drug box (75) is located outside the fermentation container (1) and is connected to the drug distributor located inside the fermentation container (1) through the drug delivery pipe (72) passing through the fermentation container (1); the drug in the drug box (75) includes one or more of alkali solution, acid solution, and trace element solution; the monitoring electronic control component (9) adjusts the flow of alkali solution, acid solution, and trace element solution in the drug regulating component (7) in real time through the metering pump (74), so that the pH value of the sludge in the fermentation container (1) is maintained at 8-10, and the concentration of trace elements in the sludge is maintained at: Cu 2+ , 20-65 mmol / L; Mn 2+ , 2.5-6.0 mmol / L; B 3+ , 15.0-28.5 mmol / L, Mo 6+ , 4.0-6.2 mmol / L; W 6+ , 7.0-12.2 mmol / L; Ni 2+ , 3.0-5.5 mmol / L; Co 2+ , 10.0-18.3 mmol / L; Zn 2+ , 25.5-35.0 mmol / L; Ca 2+ , 10.5-30.5 mmol / L.

9. The fermentation device for recovering carboxylic acid and simultaneously reducing greenhouse gas emissions according to claim 8, characterized in that: The drug distributor is an annular drug distributor (71) which is arranged 20-100 cm below the liquid surface in the fermentation container (1). The annular drug distributor (71) is provided with a plurality of drug nozzles (73) for uniformly spraying the drug into the sludge.

10. The fermentation device for recovering carboxylic acid and simultaneously reducing greenhouse gas emissions according to claim 8, characterized in that: The drug regulating assembly (7) further comprises an inert gas storage tank (76), an inert gas delivery pipe (77) and an inert gas stripping nozzle (78); the inert gas storage tank (76) is located in the drug adding box (75) and is connected to the inert gas delivery pipe (77); the end of the inert gas delivery pipe (77) is horizontally arranged at the bottom of the fermentation container (1) and is evenly distributed with a plurality of inert gas stripping nozzles (78).

11. The fermentation device for recovering carboxylic acid and simultaneously reducing greenhouse gas emissions according to claim 1, characterized in that: The fermentation device further comprises a venting assembly (8), and a venting port (103) is provided at the bottom of the fermentation container (1); the venting assembly (8) comprises a plurality of venting branch pipes (81), a venting transfer box (82) and a venting pipe (83); the inlet of the venting branch pipe (81) faces downward and is 3-30 cm away from the bottom surface of the fermentation container (1); the venting transfer box (82) is a hollow box, and its side wall is connected to the plurality of venting branch pipes (81); one end of the venting pipe (83) is connected to the venting transfer box (82), and the other end passes through the venting port (103).

12. The fermentation device for recovering carboxylic acid and simultaneously reducing greenhouse gas emissions according to claim 1, characterized in that: The side wall of the fermentation container (1) is provided with a plurality of instrument monitoring ports (112), which are evenly distributed along the side wall of the fermentation container (1) from a high position to a low position at a certain rotation angle; the monitoring instruments are embedded in the instrument monitoring ports (112), including a thermometer (91), a pH meter (92) and a water quality monitoring probe (93), and the thermometer (91), the pH meter (92) and the water quality monitoring probe (93) are respectively used to continuously monitor the temperature, pH value and water quality of the sludge in the fermentation container (1); the controller adjusts the flow rate of the circulation pump (41) in the hydraulic circulation component (4) and the speed of the stirrer (61) in the stirring component (6) in real time, so that the data monitored by the thermometer (91), the pH meter (92) and the water quality monitoring probe (93) at different positions tend to be consistent.

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