A low-depth plug-flow aerobic granular sludge treatment device and a method for changing a four-corridor carousel oxidation ditch into a continuous-flow aerobic granular sludge

Abstract

The present application relates to water treatment device technical field, specifically provide four corridor carousel oxidation ditch is changed into continuous flow aerobic granular sludge method, including the following steps: flow state reconstruction, aeration system reconstruction, water distribution backflow system, granular sludge cultivation system building. Beneficial effect lies in, realizes the low depth pool application aerobic granular sludge technology, the removal efficiency of pollutants is significantly improved, significantly reduces operating cost, realizes granular sludge stable cultivation, enhances the anti-impact load capacity of system, the transformation cost is low, and energy consumption is less.

Description

Technical Field

[0001] This invention relates to the field of water treatment equipment technology, specifically a low-depth plug-flow aerobic granular sludge treatment device and a method for converting a four-corridor carousel oxidation ditch into a continuous flow aerobic granular sludge treatment device. Background Technology

[0002] With increasing environmental awareness and increasingly stringent environmental regulations, countries are continuously raising the requirements for effluent quality from wastewater treatment plants, especially regarding the removal of nutrients such as nitrogen and phosphorus. Traditional wastewater treatment processes are facing severe challenges in upgrading. How to upgrade existing wastewater treatment facilities at low cost to meet the latest environmental requirements is a pressing issue that urgently needs to be addressed.

[0003] The Carrousel oxidation ditch is a widely used modified activated sludge process. It is essentially an extended aeration system that uses circulating water in a ring-shaped ditch to degrade organic matter and remove nitrogen and phosphorus.

[0004] The characteristics of the Carrousel oxidation ditch are as follows: 1. The effective water depth is shallow (usually 2.5~4m), the reaction rate is slow, and the land area required for the same treatment scale is large; the ring ditch design has high requirements for the site shape, the space utilization rate of the pool is low, and a large amount of land needs to be acquired for new treatment scale.

[0005] 2. Surface aeration / inverted umbrella aeration equipment is prone to wear and tear and has a high failure rate. Underwater mixing equipment is prone to sludge entanglement, requiring frequent maintenance and incurring high maintenance costs. The average service life of the equipment is 8 to 10 years.

[0006] 3. Suitable for wastewater treatment plants with stable influent water quality and low discharge requirements (such as rural wastewater and low-standard municipal wastewater), projects with sufficient site and low sensitivity to energy consumption and sludge disposal costs.

[0007] Upgrading the Carrousel oxidation ditch directly requires the addition of denitrification filters, advanced treatment units, etc., which involves a large amount of work and a long period of time.

[0008] Continuous flow aerobic granular sludge process is a rapidly developing new biological treatment technology in the field of wastewater treatment. Due to its unique granular structure and internal microenvironment differences, aerobic granular sludge has a strong resistance to shock loads and can efficiently remove pollutants such as organic matter, nitrogen, and phosphorus within a short hydraulic retention time. It can also maintain stable treatment effects under fluctuating water quality conditions, making it an ideal alternative to solve the shortcomings of traditional processes.

[0009] However, the common effective water depth of this process is 4 to 6 meters. Modifying it under shallow pool conditions such as the Carrousel oxidation ditch presents many technical challenges. At the same time, the formation of aerobic granular sludge requires a suitable organic load, necessary hydraulic shear force, and a rich microbial community. How to meet the above conditions on the basis of the original structure of the oxidation ditch has become the key to process modification.

[0010] Based on this, the present invention provides a low-depth plug flow aerobic granular sludge treatment device and a method for converting a four-corridor Carrousel oxidation ditch into a continuous flow aerobic granular sludge treatment device, in order to solve the difficult problems of upgrading and transforming the Carrousel oxidation ditch. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to provide a low-depth plug flow aerobic granular sludge treatment device and a method for converting a four-corridor carousel oxidation ditch into a continuous flow aerobic granular sludge treatment device. This solves the problems of poor shock resistance, low treatment efficiency, high energy consumption, high upgrading and transformation costs of the existing carousel oxidation ditch system, and insufficient pool depth, which makes it difficult to utilize the existing aerobic granular sludge device.

[0012] This invention discloses a method for converting a four-channel Carrousel oxidation ditch into a continuous flow aerobic granular sludge treatment, comprising the following steps: S1, Flow Modification Install partition walls within the Carrousel oxidation ditch to break the original circular flow pattern of the ditch and transform it into a corridor-type flow channel; S2, Aeration System Modification The original inverted umbrella aeration or surface aeration methods have been abandoned and replaced with an adjustable blower bottom aeration system; S3, Water Distribution and Return System A water distribution channel is installed at the common wall of the Carrousel oxidation ditch I and IV. The water distribution channel is equipped with water distribution holes, or it can be replaced with a water distribution pipe with small holes according to actual process requirements. The wastewater treated in the micro-aerobic aeration zone is evenly distributed to the aerobic granular sludge generator through the water distribution holes / pipes. S4. Construction of granular sludge cultivation system An aerobic granular sludge generator is built into the IV corridor of the microaerobic aeration zone. This generator has the dual functions of granular sludge cultivation and sludge-water separation, providing a suitable hydraulic and biochemical environment for microbial self-flocculation to form granular sludge. An air-lift device is connected to the sludge hopper of the aerobic granular sludge generator. The air-lift device is directly connected to the anaerobic zone, replacing the traditional pump return method. The air-lift device lifts the granular sludge at the bottom of the generator and returns it to the anaerobic zone. The sludge return ratio is strictly controlled at ≤100%, ensuring that the granular sludge is evenly distributed in each functional zone, providing a guarantee for the stable cultivation and recycling of granular sludge.

[0013] Furthermore, in step S1, the carrousel oxidation ditch is divided into two independent functional zones by a partition wall: an anaerobic zone and a micro-aeration zone. The micro-aerobic aeration zone consists of the original I, II, III, and IV corridors of the Carrousel oxidation ditch connected in a longitudinal direction to form an integrated plug-flow cell, ensuring that the sewage flows unidirectionally along the corridors; The circulation ditch of the Carrousel oxidation ditch is designated as an anaerobic zone. Low-speed flow mixers are installed in the anaerobic zone. The operating parameters of the low-speed flow mixers are based on avoiding damage to the granular sludge structure. This ensures that the sludge and wastewater are fully mixed, while preventing the granular sludge from being broken up, thus ensuring the stable progress of the reaction in the anaerobic zone.

[0014] Furthermore, in step S2, the adjustable blower bottom aeration system is equipped with independent aeration points, air pipes, a valve control system, and a gas flow meter, and is paired with a variable frequency blower. By precisely adjusting the aeration volume, the dissolved oxygen concentration in the micro-aerobic aeration zone can be controlled in a gradient manner. The overall dissolved oxygen concentration in the micro-aeration zone is controlled at ≤1.0 mg / L, with the dissolved oxygen content in corridors I and II controlled at 0~0.5 mg / L, and the dissolved oxygen content in corridors III and IV controlled at 0.5~1.0 mg / L. This creates a dissolved oxygen gradient that gradually increases along the flow direction within the oxidation ditch, which is suitable for the metabolic needs of microorganisms.

[0015] Furthermore, in step S3, the flow velocity of the sewage through the distribution pipe is 0.3~0.5m / s.

[0016] This invention also discloses a low-depth plug-flow aerobic granular sludge treatment device, comprising a carousel oxidation ditch, an anaerobic zone, and a microaerobic aeration zone; The anaerobic zone is located at the ends of the carousel oxidation ditch where the inlet and outlet are located, and the anaerobic zone is equipped with a low-speed propeller; a return channel is provided between the anaerobic zone and the aeration zone; The micro-aeration zone is a series-connected transformation of the Carrousel oxidation ditch corridor. A water distribution channel is provided on the partition wall between the anaerobic zone and the microaerobic aeration zone; the inlet is connected to the anaerobic zone, and the outlet is connected to the outlet of the microaerobic aeration zone. An aerobic granular sludge generator is installed near the outlet in the micro-aerobic aeration zone.

[0017] The beneficial effects of this invention are as follows: 1. Aerobic granular sludge technology was implemented in low-depth water tanks. 2. Pollutant removal efficiency is significantly improved. By creating a gradient of organic matter concentration along the flow path through a corridor-type plug flow, combined with precise control of the dissolved oxygen gradient, the granular sludge forms an aerobic, facultative, and anaerobic microenvironment from the outside in. This allows for the simultaneous realization of multiple biochemical reactions, including nitrification and denitrification, short-cut nitrification and denitrification, denitrification for phosphorus removal, and aerobic excess phosphorus uptake, significantly improving nitrogen and phosphorus removal efficiency and organic matter degradation efficiency. At the same time, the plug flow mode rapidly removes a large amount of organic matter at the front end, while achieving fine treatment of nitrogen and phosphorus at the back end, making full use of microbial resources to further improve the overall treatment effect and meet high-standard effluent requirements.

[0018] 3. Significantly reduce operating costs Replacing traditional surface aeration with adjustable bottom blower aeration improves oxygen transfer efficiency. Combined with a zoned independent aeration system and variable frequency blowers, a segmented oxygen supply strategy is implemented—sufficient aeration in areas with high organic matter concentration and appropriate reduction in aeration in areas with low concentration, avoiding ineffective energy consumption and reducing system energy consumption by 20-30%. The excellent settling performance and efficient metabolic characteristics of granular sludge reduce excess sludge production by 30-40%, significantly lowering sludge disposal costs and achieving comprehensive optimization of operating costs.

[0019] 4. Achieve stable cultivation of granular sludge By constructing an organic matter concentration gradient along the flow path using a corridor-type push flow system, a "feast-hunger" growth environment for microorganisms is simulated. Combined with the regulation of dissolved oxygen gradient and appropriate hydraulic shear force, the system promotes the self-flocculation of microorganisms to form granular sludge. The airlift reflux system replaces the traditional pump reflux system, avoiding mechanical damage to the granular sludge by the pump body, while ensuring the uniform distribution of granular sludge in each functional zone. This ensures the uniformity and stability of granular sludge formation and solves the technical problem of granular sludge cultivation under shallow pool conditions.

[0020] 5. Enhance the system's resistance to shock loads. The plug-flow pattern creates a dual gradient of pollutants and dissolved oxygen, which enriches the granular sludge with different functional microbial communities (aerobic, facultative, and anaerobic), cultivating a highly adaptable and tolerant microbial community structure. At the same time, the corridor-type series plug-flow structure can effectively buffer the impact of fluctuations in influent water quality and quantity, greatly enhancing the system's resistance to shock loads and ensuring the stability of treatment results.

[0021] 6. Low retrofit cost and low energy consumption This invention is based on the modification of the original structure of the Carrousel oxidation ditch. The process upgrade can be completed simply by dividing the ditch with partition walls, replacing the aeration system, and adding water distribution channels and generators. No major reconstruction or expansion is required, resulting in low engineering costs and a short cycle. At the same time, the process parameters can be flexibly adjusted according to the actual influent water quality and treatment requirements. It is suitable for upgrading and transforming Carrousel oxidation ditches of different scales and with different effluent standards, and has broad engineering application value. Attached Figure Description

[0022] Figure 1 Structural diagram of the invention; Among them: 1-Carrousel oxidation ditch body, 2-anaerobic zone, 3-micro-aeration zone, 4-return channel, 21-low-speed propeller, 31-partition wall, 311-water distribution channel, 32-aerobic granular sludge generator; Detailed Implementation The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical embodiments of the present invention, and should not be used to limit the scope of protection of the present invention.

[0023] Example 1 This invention discloses a method for converting a four-channel Carrousel oxidation ditch into a continuous flow aerobic granular sludge treatment, comprising the following steps: S1, Flow Modification Install partition walls within the Carrousel oxidation ditch to break the original circular flow pattern of the ditch and transform it into a corridor-type flow channel; S2, Aeration System Modification The original inverted umbrella aeration or surface aeration methods have been abandoned and replaced with an adjustable blower bottom aeration system; S3, Water Distribution and Return System A water distribution channel is installed at the common wall of the Carrousel oxidation ditch I and IV. The water distribution channel is equipped with water distribution holes, or it can be replaced with a water distribution pipe with small holes according to actual process requirements. The wastewater treated in the micro-aerobic aeration zone is evenly distributed to the aerobic granular sludge generator through the water distribution holes / pipes. S4. Construction of granular sludge cultivation system An aerobic granular sludge generator is built into the IV corridor of the microaerobic aeration zone. This generator has the dual functions of granular sludge cultivation and sludge-water separation, providing a suitable hydraulic and biochemical environment for microbial self-flocculation to form granular sludge. An air-lift device is connected to the sludge hopper of the aerobic granular sludge generator. The air-lift device is directly connected to the anaerobic zone, replacing the traditional pump return method. The air-lift device lifts the granular sludge at the bottom of the generator and returns it to the anaerobic zone. The sludge return ratio is strictly controlled at ≤100%, ensuring that the granular sludge is evenly distributed in each functional zone, providing a guarantee for the stable cultivation and recycling of granular sludge.

[0024] In this embodiment, in step S1, the carrousel oxidation ditch is divided into two independent functional zones by a partition wall: an anaerobic zone and a micro-aerobic aeration zone. The micro-aerobic aeration zone consists of the original I, II, III, and IV corridors of the Carrousel oxidation ditch connected in a longitudinal direction to form an integrated plug-flow cell, ensuring that the sewage flows unidirectionally along the corridors; The circulation ditch of the Carrousel oxidation ditch is designated as an anaerobic zone. Low-speed flow mixers are installed in the anaerobic zone. The operating parameters of the low-speed flow mixers are based on avoiding damage to the granular sludge structure. This ensures that the sludge and wastewater are fully mixed, while preventing the granular sludge from being broken up, thus ensuring the stable progress of the reaction in the anaerobic zone.

[0025] In this embodiment, the adjustable blower bottom aeration system in step S2 is equipped with independent aeration points, air pipes, a valve control system, and a gas flow meter, and is paired with a variable frequency blower. By precisely adjusting the aeration volume, the dissolved oxygen concentration in the micro-aerobic aeration zone can be controlled in a gradient manner. The overall dissolved oxygen concentration in the micro-aeration zone is controlled at ≤1.0 mg / L, with the dissolved oxygen content in corridors I and II controlled at 0~0.5 mg / L, and the dissolved oxygen content in corridors III and IV controlled at 0.5~1.0 mg / L. This creates a dissolved oxygen gradient that gradually increases along the flow direction within the oxidation ditch, which is suitable for the metabolic needs of microorganisms.

[0026] In this embodiment, during step S3, the flow velocity of the sewage through the distribution pipe is 0.3~0.5m / s.

[0027] This invention also discloses a low-depth plug-flow aerobic granular sludge treatment device, comprising a carousel oxidation ditch, an anaerobic zone, and a microaerobic aeration zone; The anaerobic zone is located at the ends of the carousel oxidation ditch where the inlet and outlet are located, and the anaerobic zone is equipped with a low-speed propeller; a return channel is provided between the anaerobic zone and the aeration zone; The micro-aeration zone is a series-connected transformation of the Carrousel oxidation ditch corridor. A water distribution channel is provided on the partition wall between the anaerobic zone and the microaerobic aeration zone; the inlet is connected to the anaerobic zone, and the outlet is connected to the outlet of the microaerobic aeration zone. An aerobic granular sludge generator is installed near the outlet in the micro-aerobic aeration zone.

[0028] To further illustrate the beneficial effects of this application, data from before and after the renovation of the carousel oxidation ditch at a wastewater treatment plant are used as application examples and comparative examples, respectively.

[0029] Application Example 1 After the upgrade of the biological treatment system of the wastewater treatment plant, the effluent quality has been significantly improved, energy and chemical consumption have been significantly reduced, operation and maintenance efficiency has been enhanced, and the effluent has consistently met the quasi-IV standard (TN<12mg / L).

[0030] The parameters for aerobic granular sludge are as follows: Chi Shen 4~6m Particle size range 0.1~0.6mm MLSS (Mixed Lime Sludge Concentration) 5000~12000 mg / L Sludge Volume Index (SVI) 30~50mL / g SRT (Sludge Retention Time) 10~30d DO (aerobic segment) ≤1.0mg / L reactor form Continuous flow After the modification, the effluent from the biological treatment system is as follows: COD: ≤30mg / L, average effluent COD 18mg / L; Ammonia nitrogen: ≤1.2mg / L, average effluent concentration 0.3mg / L; TN: ≤10mg / L, average effluent concentration 7.2mg / L; TP: ≤1.0mg / L, average effluent concentration 0.67mg / L; Phosphorus removal agents are reduced by 60%, carbon sources by 100%, and electricity consumption by 30%.

[0031] Comparative Example 1 Before the modification, the effluent from the biological treatment system was: COD: ≤50mg / L Ammonia nitrogen: ≤5.0 mg / L TN: ≤15mg / L TP: ≤2.5mg / L By comparing the above application example 1 and comparative example 1, it can be seen that the effect of the present invention is better than that of the traditional carousel oxidation ditch.

[0032] To further demonstrate that the configuration of this invention solves the problem of shallow application of aerobic granular sludge, the granular sludge data in Application Example 1 is compared with that of ordinary granular sludge as follows: Comparative Example 2 Chi Shen 6~8m 4~6m Common particle size range 1.0~2.0mm 0.1~0.6mm MLSS (Mixed Lime Sludge Concentration) 6000 ~ 10000 mg / L 5000~12000 mg / L Sludge Volume Index (SVI) 20~50 mL / g 30~50mL / g SRT (Sludge Retention Time) 10 ~ 20 d 10~30d DO (aerobic segment) 2.0 ~ 4.0 mg / L ≤1.0mg / L reactor form Sequential batch Continuous flow By comparing the above application example 1 and comparative example 2, and considering the water purification effect of application example 1, it can be seen that the present invention solves the problem of applying aerobic granular sludge at shallow depths by configuring aerobic granular sludge parameters.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for converting a four-corridor carousel oxidation ditch into a continuous flow aerobic granular sludge treatment, characterized in that... The process includes the following steps: S1, Flow Modification Install partition walls within the Carrousel oxidation ditch to break the original circular flow pattern of the ditch and transform it into a corridor-type flow channel; S2, Aeration System Modification The original inverted umbrella aeration or surface aeration methods have been abandoned and replaced with an adjustable blower bottom aeration system; S3, Water Distribution and Return System A water distribution channel is installed at the common wall of the Carrousel oxidation ditch I and IV. The water distribution channel is equipped with water distribution holes, or it can be replaced with a water distribution pipe with small holes according to actual process requirements. The wastewater treated in the micro-aerobic aeration zone is evenly distributed to the aerobic granular sludge generator through the water distribution holes / pipes. S4. Construction of granular sludge cultivation system An aerobic granular sludge generator is built into the IV corridor of the microaerobic aeration zone. This generator has the dual functions of granular sludge cultivation and sludge-water separation, providing a suitable hydraulic and biochemical environment for microbial self-flocculation to form granular sludge. An air-lift device is connected to the sludge hopper of the aerobic granular sludge generator. The air-lift device is directly connected to the anaerobic zone, replacing the traditional pump return method. The air-lift device lifts the granular sludge at the bottom of the generator and returns it to the anaerobic zone. The sludge return ratio is strictly controlled at ≤100%, ensuring that the granular sludge is evenly distributed in each functional zone, providing a guarantee for the stable cultivation and recycling of granular sludge.

2. The method for converting a four-corridor carousel oxidation ditch into a continuous flow aerobic granular sludge as described in claim 1, characterized in that... The carrousel oxidation ditch is divided into two independent functional zones by a partition wall: an anaerobic zone and a microaerobic aeration zone. The micro-aerobic aeration zone consists of the original I, II, III, and IV corridors of the Carrousel oxidation ditch connected in a longitudinal direction to form an integrated plug-flow cell, ensuring that the sewage flows unidirectionally along the corridors; The circulation ditch of the Carrousel oxidation ditch is designated as an anaerobic zone. Low-speed flow mixers are installed in the anaerobic zone. The operating parameters of the low-speed flow mixers are based on avoiding damage to the granular sludge structure. This ensures that the sludge and wastewater are fully mixed, while preventing the granular sludge from being broken up, thus ensuring the stable progress of the reaction in the anaerobic zone.

3. The method for converting a four-corridor Carrousel oxidation ditch into a continuous flow aerobic granular sludge as described in claim 1, characterized in that... In step S2, the adjustable blower bottom aeration system is equipped with independent aeration points, air pipes, a valve control system, and a gas flow meter, and is paired with a variable frequency blower. By precisely adjusting the aeration volume, the dissolved oxygen concentration in the micro-aerobic aeration zone can be controlled in a gradient manner. The overall dissolved oxygen concentration in the micro-aeration zone is controlled at ≤1.0 mg / L, with the dissolved oxygen content in corridors I and II controlled at 0~0.5 mg / L, and the dissolved oxygen content in corridors III and IV controlled at 0.5~1.0 mg / L. This creates a dissolved oxygen gradient that gradually increases along the flow direction within the oxidation ditch, which is suitable for the metabolic needs of microorganisms.

4. The method for converting a four-corridor Carrousel oxidation ditch into a continuous flow aerobic granular sludge as described in claim 1, characterized in that... In step S3, the flow velocity of the sewage through the distribution pipe is 0.3~0.5m / s.

5. A low-depth plug-flow aerobic granular sludge treatment device, characterized in that... This includes the Carrousel oxidation ditch body, anaerobic zone, and microaerobic aeration zone; The anaerobic zone is located at the ends of the carousel oxidation ditch where the inlet and outlet are located, and the anaerobic zone is equipped with a low-speed propeller; a return channel is provided between the anaerobic zone and the aeration zone; The micro-aeration zone is a series-connected transformation of the Carrousel oxidation ditch corridor. A water distribution channel is provided on the partition wall between the anaerobic zone and the microaerobic aeration zone; the inlet is connected to the anaerobic zone, and the outlet is connected to the outlet of the microaerobic aeration zone. An aerobic granular sludge generator is installed near the outlet in the micro-aerobic aeration zone.

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