A treatment system and method for treating flue gas of a sludge drying and carbonizing plant in cooperation with an activated sludge system of a biochemical tank of a sewage treatment plant

Abstract

The present application provides a kind of based on sewage treatment plant biochemical pond activated sludge system collaborative processing sludge dry carbonization plant flue gas processing system and method, system includes sequentially connected cyclone dust collector, cloth bag dust collector, reclaimed water spray tower, demister, booster fan and sewage treatment plant biochemical pond, micro-bubble cyclone aerator is arranged in biochemical pond, top is equipped with sealing cover plate and is connected with micro-negative pressure fan and chimney.Method includes two-stage dust removal, reclaimed water spray cooling demisting, booster delivery, micro-bubble cyclone aeration biodegradation, five steps of covering collection and discharge.The present application utilizes adjacent sewage plant biochemical pond activated sludge to degrade flue gas malodorous substance, without separately building deodorization system;Construct cyclone dust removal plus cloth bag dust removal plus reclaimed water spray plus wire mesh demisting pretreatment process to fully remove dust;Two-stage reverse cyclone impeller is used to generate micro-bubbles, to ensure that flue gas and activated sludge are in full contact, while flue gas residual oxygen replenishes biochemical pond aeration, to achieve waste treatment and energy and material synergy.

Description

Technical Field

[0001] This invention relates to the field of sludge treatment and waste gas treatment technology, and in particular to a treatment system and method for co-treating flue gas from sludge drying and carbonization plants based on the activated sludge system in the biochemical tank of a wastewater treatment plant. Background Technology

[0002] Sludge drying and carbonization technology has been developed in my country for over 20 years. After drying and carbonization, sludge produces a large amount of low-molecular-weight organic matter, water vapor, and sludge-based biochar, demonstrating certain advantages in sludge reduction, harmlessness, and resource utilization. However, the large amount of gas generated during the sludge drying and carbonization process is accompanied by a strong odor, which has a negative impact on the plant area and surrounding environment. Effective elimination of these odorous gases will facilitate the widespread adoption of this technology.

[0003] In sludge treatment processes employing drying and carbonization, the carbonization pyrolysis gas mostly needs to enter the secondary combustion chamber for deep combustion, converting the pyrolysis gas into small molecules such as carbon dioxide, water, nitrogen oxides, and sulfur oxides. The heat generated from combustion is then introduced into the drying furnace to dry the sludge, achieving heat recycling and reducing the sludge moisture content to approximately 20% to 30%. Finally, the flue gas from the drying furnace is discharged into the flue gas treatment system. The odor source of this sludge treatment system is mainly the odor-causing gases generated during the sludge drying process. These gases are primarily organic compounds, including ammonia, hydrogen sulfide, sulfur dioxide, methanethiol, dimethyl sulfide, benzene compounds, amines, and other complex organic compounds. Effectively treating these odorous gases is crucial for accurately addressing the odor problem in sludge treatment plant flue gas.

[0004] Traditional flue gas treatment processes in drying and carbonization plants typically involve a combination of dust removal, chemical scrubbing, and biological deodorization. These processes generally require the separate construction of a complete deodorization system, resulting in high project investment costs. Furthermore, they do not adequately address issues such as flue gas cooling and demisting, leading to poor biological treatment effects and the emission of large amounts of dense smoke with poor sensory characteristics.

[0005] Most wastewater treatment plant biological treatment tanks utilize the activated sludge process. Activated sludge contains an extremely complex microbial ecosystem, in which many microorganisms, such as Bacillus and Pseudomonas, can effectively adsorb and degrade malodorous substances like ammonia, hydrogen sulfide, methanethiol, and dimethyl sulfide in flue gas, exhibiting excellent deodorization performance. Simultaneously, by treating the malodorous gases in the flue gas, the deodorizing bacteria in the activated sludge are screened, promoted, and multiplied, and then returned to the upstream anaerobic and anoxic tanks to further remove hydrogen sulfide, ammonia, and other malodorous gases from the wastewater, improving the deodorization efficiency of the wastewater treatment plant. Therefore, utilizing existing wastewater treatment plant biological treatment tanks to treat flue gas from sludge drying and carbonization plants can fully leverage the deodorization function of the wastewater treatment plant, achieving waste-to-waste treatment. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies in the treatment of flue gas from sludge drying and carbonization plants, which require separate construction, have high investment costs, and have poor treatment effects. This invention provides a treatment system and method based on the co-treatment of flue gas from sludge drying and carbonization plants using activated sludge from the biochemical tanks of adjacent wastewater treatment plants. This system utilizes activated sludge from the biochemical tanks of adjacent wastewater treatment plants to biodegrade odorous substances in the flue gas, eliminating the need for a separate deodorization system, reducing engineering investment, and simultaneously achieving energy and material synergy between flue gas treatment and the biochemical system.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A treatment system for co-treating flue gas from a sludge drying and carbonization plant based on an activated sludge system in a wastewater treatment plant's biochemical tank includes a cyclone dust collector, a bag filter dust collector, a greywater spray tower, a demister, a booster fan, and a wastewater treatment plant's biochemical tank, all connected sequentially by pipelines. The inlet of the cyclone dust collector is connected to the flue gas outlet of the sludge drying furnace. A microbubble cyclone aerator is installed inside the wastewater treatment plant's biochemical tank, and the microbubble cyclone aerator is connected to the outlet of the booster fan via a flue gas conveying pipeline. A sealing cover is installed on the top of the wastewater treatment plant's biochemical tank, forming a sealed space between the sealing cover and the wastewater treatment plant's biochemical tank. A micro-negative pressure fan is connected to the sealed space via a pipeline, and the outlet of the micro-negative pressure fan is connected to a chimney via a pipeline.

[0008] Furthermore, the outlet of the cyclone dust collector is connected to the inlet of the bag filter dust collector through a pipe. The cyclone dust collector is used to remove dust particles with an aerodynamic diameter greater than 5μm from the flue gas, while the bag filter dust collector is used to remove dust particles with an aerodynamic diameter less than 5μm from the flue gas.

[0009] Furthermore, the air inlet of the greywater spray tower is connected to the air outlet of the bag filter through a pipe. The greywater spray tower has multiple spray layers, each connected to a greywater inlet pipe. The greywater spray tower also has a packing layer and a greywater outlet pipe at the bottom.

[0010] Furthermore, the microbubble cyclone aerator includes a flue gas inlet pipe, an inlet valve, a mud-water mixture guide component, a first-stage forward cyclone impeller, a second-stage reverse cyclone impeller, and an umbrella-shaped outlet guide component. One end of the flue gas inlet pipe is connected to the outlet of the booster fan through a pipe, and the other end of the flue gas inlet pipe is connected to the mud-water mixture guide component. The inlet valve is installed on the flue gas inlet pipe. The first-stage forward cyclone impeller and the second-stage reverse cyclone impeller are sequentially installed inside the mud-water mixture guide component. The umbrella-shaped outlet guide component is installed at the top of the mud-water mixture guide component.

[0011] Furthermore, the biological treatment tank of the wastewater treatment plant includes an anaerobic tank, an anoxic tank, and an aerobic tank arranged in parallel. Microbubble vortex aerators are arranged at the bottom of the aerobic tank. The sealing cover is a polyester fiber cover with polyvinylidene fluoride coating, and the sealing cover is suspended above the tank body of the wastewater treatment plant by steel cables.

[0012] This invention also provides a method for treating flue gas from a sludge drying and carbonization plant based on a co-treatment system of activated sludge in a biological treatment tank of a wastewater treatment plant. The method, employing the aforementioned treatment system, includes the following steps: S1. The flue gas discharged from the sludge drying furnace is sequentially passed into a cyclone dust collector and a bag dust collector for two-stage dust removal treatment. S2. The flue gas after dust removal is introduced into the greywater spray tower, and greywater from the sewage treatment plant is used to spray the flue gas in a counter-current manner to cool it down and pre-deodorize it. S3. The cooled flue gas is passed into a demister to remove water mist, and then pressurized by a booster fan before being transported to the biological treatment tank of the sewage treatment plant. S4. The flue gas is cut into microbubbles and dispersed in the activated sludge by microbubble cyclone aerators arranged in the biological treatment tank. The activated sludge microorganisms adsorb and degrade the malodorous substances in the flue gas. S5. The flue gas treated in the biological treatment tank is collected by the top sealing cover and transported to the chimney by a micro negative pressure fan to meet emission standards.

[0013] Furthermore, in step S1, the cyclone dust collector removes dust particles with an aerodynamic diameter greater than 5 μm from the flue gas, and the bag filter removes dust particles with an aerodynamic diameter less than 5 μm from the flue gas. The inlet velocity of the cyclone dust collector is controlled between 15 and 23 m / s.

[0014] Furthermore, in step S2, the flue gas enters from the bottom of the greywater spray tower and comes into countercurrent contact with the greywater sprayed from top to bottom, reducing the flue gas temperature to below 40°C. The greywater after spraying is discharged and used for sludge conditioning or heat recovery.

[0015] Furthermore, in step S4, the microbubble vortex aerator cuts the flue gas into microbubbles with a diameter of about 0.2 mm through two-stage counter-current vortex impellers, so that the residence time of the flue gas in the aerobic tank reaches more than 30 seconds.

[0016] Furthermore, in step S2, the spray water volume is adjusted according to the season to control the flue gas outlet temperature. In winter, the flue gas outlet temperature is increased to 50 to 60°C to synergistically enhance the activity of activated sludge in the biological treatment tank. In summer, the flue gas outlet temperature is controlled at around 35°C.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention adopts a collaborative treatment system architecture of adjacent business types treating waste with waste, breaking through the inertia of thinking in the same factory area. It makes full use of the coordination of treatment systems of different business types in geographically adjacent locations, and uses the biological system of sewage treatment plant to treat the high-temperature flue gas of sludge drying. The core significance is to treat waste with waste and share resources. There is no need to build a separate flue gas treatment system for sludge drying and carbonization plant. The special pollution treatment capacity of the biological pool of adjacent sewage treatment plant is directly used to treat the flue gas, which greatly reduces the investment cost of the project.

[0018] 2. This invention achieves full synergy of energy and matter in the flue gas treatment and biological tank aeration systems. The flue gas from sludge drying and carbonization is used as the aeration source for the biological tank. The residual oxygen in the flue gas can serve as supplementary air for the biological tanks in the wastewater treatment plant, reducing energy consumption. The front-end can control the effect of greywater spraying, and appropriately increasing the flue gas temperature in winter allows the flue gas to enter the wastewater treatment system with a certain amount of heat, effectively improving the sludge activity in the biological tanks. Furthermore, the activated sludge in the aeration tank absorbs odorous gases from the sludge drying flue gas, which is beneficial for enriching dominant bacteria with deodorizing functions. These bacteria are then returned to the anoxic and anaerobic tanks, further enhancing the deodorizing function of the wastewater treatment plant. This fully enhances the multi-faceted synergistic treatment benefits of the flue gas system (oxygen supplementation), the heat preservation system (heat preservation), and the bacteria cultivation system (sludge-based aeration), improving the material and energy efficiency of both the flue gas system and the biological system.

[0019] 3. This invention constructs a pretreatment combination process of cyclone dust collector, bag filter dust collector, greywater spraying, and wire mesh demisting. Targeting the wide particle size distribution of dust in sludge drying and carbonization plants, the cyclone dust collector primarily removes large-diameter dust particles, the bag filter removes small-diameter dust particles, the greywater spraying further intercepts micron-sized fine particles, and the wire mesh demisting removes water mist. This process effectively removes dust and water mist from the flue gas, ensuring the safe and stable operation of the downstream aeration system.

[0020] 4. This invention uses a microbubble vortex aerator for biological treatment of flue gas, which differs from the microporous aeration discs and aeration pipes used in traditional biological treatment tanks. It adopts a microbubble vortex aerator with a large channel structure to prevent micron-sized dust in the flue gas from clogging the aerator. The two-stage counter-current vortex impeller cuts and generates microbubbles with a diameter of about 0.2 mm, ensuring that the dried flue gas can stay in the biological treatment tank for more than 30 seconds. This provides sufficient contact time for the activated sludge to fully adsorb and degrade odorous substances in the flue gas. At the same time, the microbubbles can effectively improve the utilization rate of flue gas in the bubbles. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating the overall process flow of the system of the present invention. Figure 2 This is a layout diagram of the flue gas treatment system of the biological treatment tank in a wastewater treatment plant according to the present invention; Figure 3This is a detailed structural diagram of the microbubble vortex aerator of the present invention.

[0022] Explanation of reference numerals in the attached drawings: 1. Drying furnace; 2. Cyclone dust collector; 3. Bag filter dust collector; 4. Greywater spray tower; 5. Demister; 6. Booster fan; 7. Biological treatment tank of wastewater treatment plant; 71. Anaerobic tank; 72. Anoxic tank; 73. Aerobic tank; 74. Microbubble cyclone aerator; 741. Flue gas inlet pipe; 742. Inlet valve; 743. Sludge-water mixture guide component; 744. First-stage forward cyclone impeller; 745. Second-stage reverse cyclone impeller; 746. Umbrella-shaped outlet guide component; 8. Micro-negative pressure fan; 9. Chimney. Detailed Implementation

[0023] The technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] like Figure 1 As shown in the figure, this embodiment provides a treatment system for the co-treatment of flue gas from a sludge drying and carbonization plant based on an activated sludge system in a wastewater treatment plant's biological treatment tank. The system includes a cyclone dust collector 2, a bag filter 3, a greywater spray tower 4, a demister 5, a booster fan 6, and a wastewater treatment plant's biological treatment tank 7, all connected sequentially by pipes. The inlet of the cyclone dust collector 2 is connected to the flue gas outlet of the sludge drying furnace 1 via a pipe. The outlet of the cyclone dust collector 2 is connected to the inlet of the bag filter 3 via a pipe. The outlet of the bag filter 3 is connected to the inlet of the greywater spray tower 4 via a pipe. The outlet of the greywater spray tower 4 is connected to the inlet of the demister 5 via a pipe. The outlet of the demister 5 is connected to the inlet of the booster fan 6 via a pipe. The outlet of the booster fan 6 is connected to a microbubble cyclone aerator 74 arranged within the wastewater treatment plant's biological treatment tank 7 via a flue gas conveying pipe. The top of the biological treatment tank 7 of the sewage treatment plant is equipped with a sealing cover plate, which forms a closed space between the sealing cover plate and the biological treatment tank 7. The closed space is connected to a micro negative pressure fan 8 through a pipe, and the air outlet of the micro negative pressure fan 8 is connected to a chimney 9 through a pipe.

[0025] Cyclone dust collector 2 is mainly used to remove larger dust particles with an aerodynamic diameter greater than 5μm from the flue gas. Its selection is determined based on the required air volume of the drying and carbonization system, ensuring an inlet air velocity of 15 to 23 m / s. It is made of high-temperature resistant, corrosion-resistant, and wear-resistant alloy steel to adapt to the high-temperature and corrosive conditions of the sludge drying flue gas. Bag dust collector 3 is mainly used to remove smaller dust particles with an aerodynamic diameter less than 5μm from the flue gas. The filter bags are made of high-temperature resistant and acid-corrosion-resistant needle-punched felt filter media capable of long-term stable operation at 180℃. The operating temperature of the bag dust collector must be higher than the water dew point and acid dew point of the flue gas to prevent condensation and bag clogging. Cyclone dust collector 2 and bag dust collector 3 are connected in series to form a two-stage dust removal system, maximizing the removal of dust from the flue gas.

[0026] The flue gas, after undergoing two-stage dust removal, enters the greywater spray tower 4 for cooling. The greywater spray tower 4 employs a spray tower structure with three or more spray layers. Each spray layer has multiple nozzles, made of acid-resistant and high-temperature-resistant stainless steel, with a diameter of 5 to 8 mm. The spray layers are connected to the greywater supply system of the wastewater treatment plant via a greywater inlet pipe. An impurity filter is installed on the greywater inlet pipe to prevent impurities in the greywater from clogging the spray tower nozzles. The greywater spray tower 4 contains a layer of metal Pall ball packing below the spray layers to increase the gas-liquid contact area and achieve a sufficient cooling effect. A greywater discharge pipe is located at the bottom of the greywater spray tower 4. The sprayed greywater is discharged through this pipe and can be transported to a sludge treatment plant for sludge conditioning or used for heat recovery through a heat exchanger. Flue gas enters from the bottom of the greywater spray tower 4, coming into counter-current contact with the greywater sprayed from top to bottom. After heat exchange and cooling, the outlet temperature drops to below 40℃. In actual operation, the spray water volume can be flexibly adjusted according to the operating conditions of the wastewater treatment plant. In winter, the flue gas outlet temperature can be appropriately increased to 50-60℃ to synergistically enhance the microbial activity of activated sludge in the biological treatment tank. In summer, the temperature can be controlled at around 35℃ to ensure stable operation of the biological treatment system. During the greywater spraying process, water-soluble odor components such as hydrogen sulfide and ammonia in the flue gas can be effectively absorbed, achieving a pre-deodorization effect. At the same time, it further intercepts and removes residual micron-sized fine particulate matter in the flue gas, preventing fine particulate matter from entering the subsequent booster fan and biological treatment tank aeration system and causing equipment blockage.

[0027] After being cooled by spraying with recycled water, the flue gas is saturated and carries a large amount of water mist. It then enters the demister 5 for demisting. The demister 5 is a wire mesh demister, which has two sections of wire mesh arranged sequentially along the flue gas flow direction to effectively intercept the water mist in the flue gas and discharge it out of the system, ensuring that the moisture content of the flue gas entering the subsequent booster fan 6 meets the equipment's operating requirements.

[0028] After demisting, the flue gas enters the booster fan 6. The booster fan 6 pressurizes the cooled, dried flue gas and delivers it to the microbubble cyclone aerator 74 in the biological treatment tank 7 of the wastewater treatment plant. The selection of the booster fan 6 must fully consider factors such as the water depth of the biological treatment tank, the head loss of the aeration equipment, and the head loss along the pipeline to ensure sufficient air pressure to deliver the flue gas to the bottom of the biological treatment tank. The booster fan 6 also serves to maintain the negative pressure of the upstream drying and carbonization equipment system, ensuring the safe and stable operation of the drying furnace and carbonization furnace, while preventing the leakage of odor from the drying and carbonization system. The outlet of the booster fan 6 is connected to the microbubble cyclone aerator 74 through the flue gas conveying pipe. Since the flue gas is saturated with water vapor after being sprayed, a condensate drain pipe is installed at the lowest point of the flue gas conveying pipe and at the end of the pipe. An automatic drain valve is installed on the condensate drain pipe to periodically drain the condensate generated in the pipe due to the cooling of the flue gas, so as to avoid water accumulation occupying the flow area of ​​the pipe, increasing the conveying resistance, affecting the operation of the blower and the aeration effect, and at the same time preventing acidic condensate from corroding the pipe.

[0029] like Figure 2 As shown, the biological treatment tank 7 of the wastewater treatment plant includes an anaerobic tank 71, an anoxic tank 72, and an aerobic tank 73 arranged in parallel. These tanks are separated by partition walls, and water flow channels are provided between adjacent tanks. Microbubble vortex aerators 74 are arranged at the bottom of the aerobic tank 73. These aerators have a liftable structure and are evenly distributed at the bottom of the aerobic tank 73. The spacing can be adjusted according to the operating conditions of the aerobic tank 73, especially in areas with low pollutant concentrations at the end of the aerobic tank 73, where the density can be increased. The microbubble vortex aerators 74 feature a liftable and mobile design, eliminating the need for fixed installation and allowing for easy maintenance and relocation, reducing equipment maintenance costs and improving treatment efficiency.

[0030] like Figure 3 As shown, the microbubble cyclone aerator 74 includes a flue gas inlet pipe 741, an inlet valve 742, a mud-water mixture guide component 743, a primary forward cyclone impeller 744, a secondary reverse cyclone impeller 745, and an umbrella-shaped outlet guide component 746. One end of the flue gas inlet pipe 741 is connected to the outlet of the booster fan 6 via a pipe, and the other end of the flue gas inlet pipe 741 is connected to the lower part of the mud-water mixture guide component 743. The inlet valve 742 is installed on the flue gas inlet pipe 741 to control the flue gas intake. The mud-water mixture guide component 743 has a vertical cylindrical structure with an opening at the bottom for the mud-water mixture to enter. A first-stage forward swirling impeller 744 and a second-stage reverse swirling impeller 745 are arranged sequentially from bottom to top inside the mud-water mixture guide component 743. The swirling directions of the first-stage forward swirling impeller 744 and the second-stage reverse swirling impeller 745 are opposite. An umbrella-shaped outlet guide component 746 is arranged at the top of the mud-water mixture guide component 743 and has an inverted V-shaped umbrella cover structure.

[0031] The working principle of the microbubble cyclone aerator 74 is as follows: High-pressure flue gas enters the mud-water mixture guiding component 743 through the flue gas inlet pipe 741. Under the guidance of the airflow, the flue gas mixes with the mud-water mixture entering from the bottom. The mixture undergoes a first-stage forward cyclone impeller 744 for initial cyclone cutting, followed by a second-stage reverse cyclone impeller 745 for a second reverse cyclone cutting. These two stages of impellers cut the flue gas into microbubbles with a diameter of approximately 0.2 mm. These cut microbubbles are further impacted and dispersed into the water through the umbrella-shaped outlet guiding component 746, ensuring full contact with the mud-water mixture in the biological treatment tank. This increases the residence time of the bubbles in the water, ensuring that the flue gas residence time in the aerobic tank 73 reaches more than 30 seconds, providing sufficient gas-liquid contact time for activated sludge microorganisms to fully adsorb and degrade odorous substances. The microbubble cyclone aerator 74 adopts a large-channel structure design, exhibiting good tolerance to residual micron-sized dust in the flue gas and is less prone to clogging.

[0032] Biological treatment tank 7 in the wastewater treatment plant is the core component of the flue gas treatment system. It utilizes the complex microbial ecosystem within the activated sludge to adsorb and biodegrade odorous substances in the flue gas. The activated sludge contains various functional microorganisms, including Bacillus, Pseudomonas, Thiobacillus, and photosynthetic bacteria. These microorganisms effectively adsorb and degrade odorous substances such as ammonia, hydrogen sulfide, methanethiol, and dimethyl sulfide in the flue gas, converting them into odorless or low-odor substances. Simultaneously, residual oxygen in the flue gas serves as a supplementary aeration source for the biological treatment tank, regulating the dissolved oxygen content of the biological system and reducing the energy consumption of the wastewater treatment plant.

[0033] The flue gas treated by activated sludge in the biological treatment tank is collected through a sealed cover and then centrally discharged. The sealed cover is made of polyester fiber coated with polyvinylidene fluoride and is suspended above the biological treatment tank 7 of the sewage treatment plant by steel cables to form a closed space. While ensuring a sealing effect, it has the advantages of large span, light weight, and convenient construction. On the one hand, it can effectively collect the flue gas treated by the biological treatment tank and prevent the unorganized escape of the treated gas. On the other hand, it allows operators to observe the operation status inside the biological treatment tank through the cover. A micro-negative pressure fan 8 is set up next to the biological treatment tank to create a micro-negative pressure state in the aerobic tank 73, which fully collects the treated flue gas in the tank. The collected flue gas is transported to the chimney 9 through pipelines and centrally discharged after testing to meet the odor pollutant emission standards.

[0034] The treatment method of this invention is implemented according to the following steps: First, the high-temperature flue gas from the outlet of the sludge drying furnace 1 is first introduced into a cyclone dust collector 2 via a pipeline. The cyclone dust collector 2 removes larger dust particles with an aerodynamic diameter greater than 5 μm from the flue gas. The inlet velocity is controlled at 15 to 23 m / s. Then, it enters a bag filter 3 to remove smaller dust particles with an aerodynamic diameter less than 5 μm, completing two-stage dust removal. Second, the flue gas after two-stage dust removal enters a greywater spray tower 4. The flue gas enters from the bottom of the tower and comes into countercurrent contact with greywater sprayed from the wastewater treatment plant from top to bottom for heat exchange, cooling, and pre-deodorization, reducing the flue gas temperature to below 40°C. Simultaneously, it further intercepts micron-sized fine particles. The sprayed greywater is discharged and used for sludge conditioning or heat recovery. During operation, the spray water volume can be adjusted according to the season. In winter, the flue gas outlet temperature is increased to 50 to 60°C, and in summer, it is controlled at... The temperature is around 35℃. The third step involves the cooled flue gas entering the demister 5, where two sections of wire mesh remove entrained water mist. The demistered flue gas is then pressurized by the booster fan 6 and sent to the biological treatment tank 7 of the wastewater treatment plant via a flue gas pipeline. The booster fan 6 simultaneously maintains negative pressure in the upstream system. The fourth step involves the flue gas passing through a microbubble cyclone aerator 74 located at the bottom of the aerobic tank 73. The gas is then cut into microbubbles with a diameter of approximately 0.2mm by two stages of reverse flow: a primary forward cyclone impeller 744 and a secondary reverse cyclone impeller 745. These microbubbles disperse in the activated sludge, and the flue gas remains in the aerobic tank 73 for more than 30 seconds. Microorganisms in the activated sludge adsorb and degrade odorous substances in the flue gas, while residual oxygen in the flue gas simultaneously replenishes the aeration in the biological treatment tank. The fifth step involves the treated flue gas being collected through a top sealing cover. A micro-negative pressure fan 8 creates a micro-negative pressure in the aerobic tank 73, and the collected flue gas is discharged through the chimney 9 after meeting emission standards.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A treatment system for the co-treatment of flue gas from a sludge drying and carbonization plant based on an activated sludge system in a wastewater treatment plant's biological treatment tank, characterized in that, The system includes a cyclone dust collector (2), a bag filter (3), a greywater spray tower (4), a demister (5), a booster fan (6), and a sewage treatment plant biochemical tank (7), which are connected in sequence by pipes. The air inlet of the cyclone dust collector (2) is connected to the flue gas outlet of the sludge drying furnace (1). The sewage treatment plant biochemical tank (7) is equipped with a microbubble cyclone aerator (74). The microbubble cyclone aerator (74) is connected to the air outlet of the booster fan (6) through a flue gas conveying pipe. The top of the sewage treatment plant biochemical tank (7) is equipped with a sealing cover plate. A sealed space is formed between the sealing cover plate and the sewage treatment plant biochemical tank (7). The sealed space is connected to a micro negative pressure fan (8) through a pipe. The air outlet of the micro negative pressure fan (8) is connected to a chimney (9) through a pipe.

2. The treatment system for the co-treatment of flue gas from a sludge drying and carbonization plant based on an activated sludge system in a wastewater treatment plant's biological treatment tank, as described in claim 1, is characterized in that... The outlet of the cyclone dust collector (2) is connected to the inlet of the bag dust collector (3) through a pipe. The cyclone dust collector (2) is used to remove dust particles with an aerodynamic diameter greater than 5 μm in the flue gas, and the bag dust collector (3) is used to remove dust particles with an aerodynamic diameter less than 5 μm in the flue gas.

3. The treatment system for the co-treatment of flue gas from a sludge drying and carbonization plant based on an activated sludge system in a wastewater treatment plant's biological treatment tank, as described in claim 1, is characterized in that... The air inlet of the greywater spray tower (4) is connected to the air outlet of the bag filter (3) through a pipe. The greywater spray tower (4) is provided with multiple spray layers. The spray layers are connected to greywater inlet pipes. The greywater spray tower (4) is provided with a packing layer. The bottom of the greywater spray tower (4) is provided with a greywater discharge pipe.

4. The treatment system for the co-treatment of flue gas from a sludge drying and carbonization plant based on an activated sludge system in a wastewater treatment plant's biological treatment tank, as described in claim 1, is characterized in that... The microbubble swirl aerator (74) includes a flue gas inlet pipe (741), an inlet valve (742), a mud-water mixture guide component (743), a first-stage forward swirl impeller (744), a second-stage reverse swirl impeller (745), and an umbrella-shaped outlet guide component (746). One end of the flue gas inlet pipe (741) is connected to the outlet of the booster fan (6) through a pipe, and the other end of the flue gas inlet pipe (741) is connected to the mud-water mixture guide component (743). The inlet valve (742) is installed on the flue gas inlet pipe (741). The first-stage forward swirl impeller (744) and the second-stage reverse swirl impeller (745) are sequentially installed inside the mud-water mixture guide component (743). The umbrella-shaped outlet guide component (746) is installed on the top of the mud-water mixture guide component (743).

5. The treatment system for the co-treatment of flue gas from a sludge drying and carbonization plant based on an activated sludge system in a wastewater treatment plant's biological treatment tank, as described in claim 1, is characterized in that... The wastewater treatment plant biochemical tank (7) includes an anaerobic tank (71), an anoxic tank (72) and an aerobic tank (73) arranged in parallel. The microbubble vortex aerator (74) is arranged at the bottom of the aerobic tank (73). The sealing cover is a polyester fiber cover with polyvinylidene fluoride coating. The sealing cover is suspended above the tank body of the wastewater treatment plant biochemical tank (7) by steel cable.

6. A method for treating flue gas from a sludge drying and carbonization plant based on a co-treatment system of activated sludge from a biological treatment tank in a wastewater treatment plant, characterized in that... The processing system according to any one of claims 1 to 5 includes the following steps: S1. The flue gas discharged from the sludge drying furnace is sequentially passed into a cyclone dust collector and a bag dust collector for two-stage dust removal treatment. S2. The flue gas after dust removal is introduced into the greywater spray tower, and greywater from the sewage treatment plant is used to spray the flue gas in a counter-current manner to cool it down and pre-deodorize it. S3. The cooled flue gas is passed into a demister to remove water mist, and then pressurized by a booster fan before being transported to the biological treatment tank of the sewage treatment plant. S4. The flue gas is cut into microbubbles and dispersed in the activated sludge by microbubble cyclone aerators arranged in the biological treatment tank. The activated sludge microorganisms adsorb and degrade the malodorous substances in the flue gas. S5. The flue gas treated in the biological treatment tank is collected by the top sealing cover and transported to the chimney by a micro negative pressure fan to meet emission standards.

7. The method for treating flue gas from a sludge drying and carbonization plant based on a co-treatment system of activated sludge from a biological treatment tank in a wastewater treatment plant, as described in claim 6, is characterized in that... In step S1, the cyclone dust collector removes dust particles with an aerodynamic diameter greater than 5 μm from the flue gas, the bag filter removes dust particles with an aerodynamic diameter less than 5 μm from the flue gas, and the inlet velocity of the cyclone dust collector is controlled between 15 and 23 m / s.

8. The method for treating flue gas from a sludge drying and carbonization plant based on a co-treatment system of activated sludge in a biological treatment tank of a wastewater treatment plant, as described in claim 6, is characterized in that... In step S2, the flue gas enters from the bottom of the greywater spray tower and comes into countercurrent contact with the greywater sprayed from top to bottom, reducing the flue gas temperature to below 40°C. The greywater after spraying is discharged and used for sludge conditioning or heat recovery.

9. The method for treating flue gas from a sludge drying and carbonization plant based on a co-treatment system of activated sludge in a biological treatment tank of a wastewater treatment plant, as described in claim 6, is characterized in that... In step S4, the microbubble vortex aerator cuts the flue gas into microbubbles with a diameter of about 0.2 mm through two-stage counter-current vortex impellers, so that the residence time of the flue gas in the aerobic tank reaches more than 30 seconds.

10. The method for treating flue gas from a sludge drying and carbonization plant based on a co-treatment system of activated sludge in a biological treatment tank of a wastewater treatment plant, as described in claim 6, is characterized in that... In step S2, the spray water volume is adjusted according to the season to control the flue gas outlet temperature. In winter, the flue gas outlet temperature is increased to 50 to 60°C to synergistically improve the activity of activated sludge in the biological treatment tank. In summer, the flue gas outlet temperature is controlled at around 35°C.

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