A sludge treatment system and method for maintaining an activated sludge process biological system

Abstract

The application discloses a sludge treatment system and method for maintaining an activated sludge biochemical system, and belongs to the technical field of sewage treatment. The system comprises a biochemical treatment system, a secondary sedimentation tank, a sludge composite classifier, a washing water supply unit and an intelligent control unit; the classifier tank body is divided into an overflow area, a washing area and a gravity sedimentation area, and is integrated with low-shear cloth water, multi-layer aged sludge collection, high-quality sludge backflow, sand discharge and pulse self-cleaning structures. The application can remove sand on line, remove aged sludge in a directional way, and stabilize the activity of biochemical sludge, and the equipment has strong adaptability, high automation degree and stable operation, and is suitable for stable operation and upgrading of the biochemical system of a sewage plant.

Description

Technical Field

[0001] This invention belongs to the field of activated sludge process operation optimization technology in wastewater treatment. Specifically, it relates to a sludge treatment system and method for maintaining activated sludge process biochemical systems. It is particularly suitable for online hydraulic separation of fine sand and gravel from sludge returned from secondary sedimentation tanks, directional removal of aged sludge flocs, and recovery of highly active and high-quality sludge, thereby achieving a complete system and process method for long-term stable sludge activity and low-energy intelligent operation and maintenance of the biochemical system. Background Technology

[0002] The activated sludge process is the most widely used biochemical treatment technology in the field of municipal and industrial wastewater treatment. However, during long-term continuous operation, there are two major operational challenges that severely restrict the treatment efficiency and operational stability of the biochemical system.

[0003] First, there are issues with sand accumulation in aeration tanks and wear and tear on aeration equipment. Grit chambers in the wastewater pretreatment stage cannot completely remove fine sand and gravel from the water. This sand and gravel continuously enters the aeration tank with the wastewater, and because its density is much greater than that of activated sludge, it accumulates at the bottom of the tank over a long period. On the one hand, this reduces the effective volume of the biochemical reaction tank and compresses the space for microbial reaction, leading to a decrease in the system's treatment load; on the other hand, continuous wear and tear on the aerators causes a decrease in oxygen transfer efficiency and a gradual increase in aeration energy consumption. Traditional sand removal methods can only be completed by shutting down water supply and production and manually cleaning the tank, resulting in extremely high downtime losses, labor costs, and environmental consequences, making it impossible to achieve routine online treatment.

[0004] Second, there is the issue of sludge aging and instability of the biological treatment system. Continuous operation of the biological treatment system generates loosely structured, poorly settling, and weakly pollutant-degrading sludge flocs. This aged sludge has no effective treatment capacity but occupies a portion of the system's sludge concentration, leading to a decrease in overall biological treatment efficiency. Traditional wastewater treatment plants commonly use a "one-size-fits-all" sludge discharge model, simultaneously discharging a large amount of high-quality, robust sludge with excellent settling properties and strong degradation activity. This easily causes an imbalance in the sludge concentration and a collapse in bacterial community activity within the biological treatment system. The system recovery period is typically several weeks long, severely impacting the stable operation of the wastewater treatment plant to meet standards.

[0005] Currently, the industry has begun to use mechanical sorting equipment such as hydrocyclones to pretreat returned sludge, but their own structural and technological defects are obvious: traditional hydrocyclone equipment relies on high-speed cyclone sorting, with large internal shear force, which easily breaks up robust activated sludge flocs, causing damage to sludge activity; the sorting hydraulic parameters are fixed and cannot adapt to seasonal and operating condition fluctuations in wastewater treatment plant water quality, water quantity, and sludge settling performance, resulting in unstable sorting accuracy.

[0006] In summary, existing technologies lack a complete sludge treatment system and intelligent process that can operate continuously online, protect sludge flocs with low shear, adapt to fluctuations in operating conditions, combine sand and gravel removal with targeted optimization of sludge activity, and operate stably for a long time without maintenance. Summary of the Invention

[0007] This invention aims to overcome the shortcomings of existing technologies and provide a sludge treatment system and method for maintaining activated sludge biological treatment systems. It solves the problems of sand accumulation and wear in aeration tanks, loss of high-quality sludge due to one-cut sludge discharge, high shear damage to sludge in traditional sorting, poor adaptability to operating conditions, easy blockage of pipelines, and high operation and maintenance costs. It achieves accurate three-phase sorting of sand, aged sludge, and high-quality sludge, optimizes microbial populations online, and maintains long-term stable treatment efficiency of biological treatment tanks.

[0008] To achieve the above objectives, the first aspect of the present invention provides a sludge treatment system for maintaining an activated sludge biochemical system, comprising a biochemical treatment system, a secondary sedimentation tank, a sludge composite separator, a washing and water supply unit, a sludge conveying unit, and an intelligent control unit; the sludge composite separator is configured as a separator tank with an upper cylindrical shape and a lower inverted conical shape, the interior of the separator tank being divided into an overflow zone, a washing zone, and a gravity settling zone from top to bottom; The overflow zone is equipped with a central guide tube, a watershed zoning structure, a uniform distribution device, a supernatant scum discharge system, and a multi-layered annular perforated aged sludge collection system arranged at different heights; the washing zone is equipped with a low-shear rising flow water distribution system, which is connected to a pulse flushing device; the gravity settling zone is equipped with an inverted conical thickening hopper, an annular perforated high-quality sludge return system, and a sand and gravel discharge system. The secondary sedimentation tank is connected to the mud-water mixture inlet pipe of the central guide tube via a sludge conveying unit and a sludge return pump bypass; the washing water supply unit includes a washing water pump, which is connected to the washing water inlet pipe of the low shear rising flow distribution system. The intelligent control unit includes a monitoring module and a control module. The monitoring module is used to collect the sludge operating parameters of the biological treatment tank and the sludge-water interface data inside the sorting tank. The control module is configured to adjust the outflow of the washing water supply unit and / or switch the annular perforated aging sludge collection system of different heights to work based on the real-time monitoring data. The annular perforated aging sludge collection system has several aging sludge collection holes evenly opened on the annular pipe wall. Each layer of annular perforated pipe is connected to an aging sludge discharge pipe. Each layer of aging sludge discharge pipe is equipped with an aging sludge discharge control valve. The supernatant scum discharge system includes a scum collection tank and a supernatant collection tank, the supernatant collection tank being connected to a supernatant discharge pipe; the scum collection tank is fixedly installed on the inner wall of the sorting tank by a scum collection tank bracket, and the scum collection tank is connected to the scum discharge pipe; The sand and gravel discharge system includes a sand and gravel discharge pipe and an automatic sand discharge valve; the annular perforated high-quality sludge return system is connected to a high-quality sludge return pump, and the output pipeline of the high-quality sludge return pump is connected to the anoxic / anaerobic zone of the biochemical treatment system. The aged sludge output end of the sludge composite separator is connected to the sludge thickening tank, and the sand and gravel output end is connected to the sand-water separator. The mud-water outlet of the sand-water separator and the discharge end of the sludge thickening tank are both connected to the sludge dewatering system.

[0009] Furthermore, the sludge composite separator is an integrated carbon steel corrosion-resistant sorting tank with an upper cylindrical and lower inverted conical shape, suitable for sludge volumes of 1000~5000m³. 3 / d sewage treatment capacity, cylindrical section diameter D=800~2000mm, cylindrical section height H1 to diameter ratio H1 / D=1.2~1.8, inverted cone section cone angle θ=50°~70°, preferably 60°; the inner wall of the tank is coated with ≥300μm epoxy coal tar anti-corrosion coating, the outer wall is sprayed with ≥200μm polyurethane topcoat, and the design service life is ≥15 years; Furthermore, the central guide tube is made of 304 stainless steel with a wall thickness of 4~6mm, an inner diameter d1=(0.15~0.25)D, a tube length L1=0.4~0.6H1, and a 60°~90° tapered flare at the bottom with a diameter d2=1.5~2.0d1 at the end of the flare. Furthermore, the sludge return pump is selected from screw pumps or centrifugal sludge pumps, with flow parts made of ductile iron / 304 stainless steel, rated flow rate Q_D=(0.1~0.3)Q_r (Q_r is the total return flow rate of the secondary sedimentation tank), head 10~20m, and frequency conversion speed range 30~100rpm; the washing water supply unit includes a washing water pump, which is a clean water centrifugal pump, rated flow rate Q_F=(0.5~2.0)Q_in, head 15~25m, and frequency conversion range 30~50Hz; Furthermore, the monitoring module collects MLSS and SV30 data from the biological treatment tank every 2 hours and calculates SVI, while simultaneously collecting height data from the radar-type sludge-water interface sensor (accuracy ±5mm) in the sorting tank. The control module has built-in SVI graded adjustment thresholds and sludge-water interface offset judgment thresholds. Based on real-time monitoring data, it adjusts the effluent flow rate of the washing water supply unit and / or switches the annular perforated aging sludge collection system at different heights to put into operation. When SVI ≤ 100mL / g, it maintains a 10%~15% diversion load; when 100 < SVI ≤ 150mL / g, it maintains a normal load; when 150 < SVI ≤ 200mL / g, the diversion ratio is increased to 20%~30%; when SVI > 200mL / g, it operates at full load and pushes an advanced alarm; when the sludge-water interface offset relative to the reference is > 10cm, it automatically switches to the corresponding height collection pipeline. Furthermore, the annular perforated aging sludge collection system uses a DN50~DN100 304 stainless steel annular pipe, with φ8~φ12mm aging sludge collection holes evenly opened on the pipe wall, the hole spacing is 30~50mm, the opening rate is 8%~15%, and each layer of annular pipe is equipped with 2~4 radial supports. Furthermore, the annular perforated high-quality sludge return system uses a DN80~DN150 304 stainless steel annular pipe, which is arranged in the area 0.3~0.5H2 (H2 is the total height of the cone section) from the bottom of the inverted conical thickening hopper, and is connected to the high-quality sludge return pump; the high-quality sludge return pump is a screw pump with a rated flow rate Q_E=(0.5~0.9)Q_in and a head of 8~15m, and the output pipeline of the high-quality sludge return pump is connected to the anoxic / anaerobic zone of the biochemical treatment system; Furthermore, the biochemical treatment system can be selected as A. 2 Processes such as O2, oxidation ditch, SBR, and CASS are used. In the anoxic / anaerobic zone, MLSS is controlled at 3000~5000mg / L and DO≤0.5mg / L. The secondary sedimentation tank is a radial / horizontal flow type with a surface loading of 0.8~1.5m³. 3 / (m 2 •h), return sludge concentration 8000~12000 mg / L; gravity thickener solid load ≤50 kg / (m²) 2 •d); The spiral sand separator separates particles with a diameter ≥0.2mm and a separation efficiency ≥95%; the dewatering system outputs mud with a moisture content ≤80%.

[0010] Furthermore, the uniform distribution device includes a reflector bracket and a reflector with the cone apex facing upwards. The reflector bracket is fixedly installed at the bottom of the central guide tube. The bottom of the central guide tube is configured with a flared structure, and the diameter of the reflector surface is larger than the diameter of the flared structure.

[0011] Furthermore, the watershed partitioning structure consists of multiple vertically arranged and spaced guide vanes, which are positioned between the outer periphery of the central guide tube and the inner wall of the sorting tank to eliminate local micro-vortices generated in the washing zone and stabilize the flow field.

[0012] Furthermore, the watershed partitioning structure consists of 304 stainless steel guide vanes with a thickness of 3-5 mm, a vane width b = 100-200 mm, a length L_g = 0.3-0.5H1, arranged in a ring array of 8-16 vanes, with the vane angle γ = 0°-15° to the radial direction.

[0013] Furthermore, the low-shear upward flow water distribution system includes an annular water distribution main pipe, radial water distribution branch pipes, and upward-facing slow-flow nozzles. The annular water distribution main pipe is connected to the rinsing water inlet pipe, and the rinsing water inlet pipe is equipped with the pulse flushing device.

[0014] Furthermore, the low-shear upward flow water distribution system includes a DN80~DN150 annular water distribution main pipe, DN40~DN80 radial water distribution branch pipes, and upward-facing conical slow-flow nozzles with a diameter of φ6~φ12mm, a nozzle spacing of 150~300mm, and an outlet flow velocity of 0.5~1.5m / s. The annular water distribution main pipe is connected to the washing water inlet pipe, and the washing water inlet pipe is equipped with the pulse flushing device. The pulse flushing device is activated every 6~12 hours, with each flush lasting 30~60 seconds, a flushing water pressure of 0.4~0.8MPa, and a normal washing water pressure of 0.05~0.15MPa.

[0015] Furthermore, the annular perforated high-quality sludge return system is located in the upper middle part of the inverted conical thickening hopper; the sand and gravel discharge pipe of the sand and gravel discharge system is installed at the bottom of the sorting tank, and an automatic sand discharge valve is installed on the sand and gravel discharge pipe.

[0016] Furthermore, the monitoring module collects operating parameters including mixed liquor suspended solids concentration (MLSS) and sludge settling ratio (SV30), and calculates the sludge volume index (SVI) based on the collected parameters. When an increase in SVI or a deterioration in sludge settling performance is detected, the control module increases the sludge feed load of the sludge composite separator (C) to enhance the sludge sorting effect.

[0017] Furthermore, the intelligent control unit connects to the plant's central control system via Modbus TCP / IP or OPC protocols to enable data uploading, fault alarms, remote parameter adjustment, and automatic generation of operation reports. It also adds feedforward predictive control logic to collect influent COD and ammonia nitrogen in real time, predict load fluctuations 20-30 minutes in advance, and adjust the sorting load accordingly.

[0018] A second aspect of the present invention provides a sludge treatment method for maintaining an activated sludge biological treatment system, implemented using the aforementioned sludge treatment system, comprising the following steps: S1. Sludge feed pretreatment: 10% to 30% flow rate of sludge-water mixture is drawn from the bypass of the return sludge pipeline of the secondary sedimentation tank. The shearing action generated by the impeller when the sludge return pump is working is used to break up only the loose and aged sludge flocs, while the dense and robust bacterial flocs are completely preserved, thus completing the non-powered pretreatment. S2. Low-shear hydraulic washing and sorting: The pretreated mud-water mixture is fed into the sorting tank through the mud-water mixture inlet pipe and the central guide tube. The washing water pump supplies water to the low-shear upward flow distribution system through the washing water inlet pipe, forming an apparent vertical upward flow of 0.2~0.5 mm / s across the tank cross-section within the washing zone; the optimal flow velocity under normal operating conditions is 0.30~0.35 mm / s, 0.20~0.30 mm / s under low load in winter, and 0.35~0.50 mm / s under high load in summer; the settling velocity of aged sludge flocs is 0.05~0. 0.15mm / s, which is less than the upward flow velocity, flows upward with the upward flow and is collected through the aging sludge collection hole by the annular perforated aging sludge collection system, and then discharged through the corresponding aging sludge discharge pipe; the high-quality activated sludge flocs have a settling rate of 0.4~0.8mm, penetrate the upward flow and settle downward, and are collected by the annular perforated high-quality sludge return system, and then transported back to the anoxic / anaerobic zone of the biochemical treatment system by the high-quality sludge return pump; heavy inorganic matter, including sand and gravel, settles to the bottom of the inverted conical thickening hopper and is intermittently discharged through the sand and gravel discharge pipe in conjunction with the automatic sand discharge valve; S3. Dynamic Operating Condition Control: Real-time collection of sludge operating parameters in the biological treatment tank and sludge-water interface height data in the sorting tank. Based on sludge settling performance and influent load prediction, adaptive adjustment of the upflow water supply, or switching of the working collection height corresponding to the first and second layer aged sludge discharge pipes, to stabilize the sorting interface in the tank and adapt to operating condition fluctuations; if the interface fluctuation is <5cm, the original pipeline is maintained; if the deviation is >10cm, the layer is automatically switched; if the deviation continues for more than 30 minutes, an equipment abnormality alarm is pushed. S4. Periodic self-cleaning operation and maintenance: The pulse flushing device starts the high-pressure pulse flushing water flow at preset intervals to thoroughly flush the annular water distribution main pipe, radial water distribution branch pipes and slow-flow nozzles, effectively preventing scale and blockage in the pipes and nozzles, and ensuring long-term stable operation of the equipment.

[0019] Furthermore, the entire sorting process is controlled through the coordinated action of guide vanes, slow-flow nozzles, and a large-section, low-velocity laminar flow structure, ensuring that the maximum shear rate of the fluid inside the tank is below 80s. -1 This value represents the critical threshold for the breakage of activated sludge flocs, preventing robust activated sludge flocs from being sheared and broken.

[0020] Furthermore, the total hydraulic retention time (HRT) of the sludge-water mixture in the sludge composite separator is controlled to be 15~25 min, with a mandatory upper limit of no more than 30 min. The HRT calculation formula is H=V_eff / Q_in (V_eff is the effective volume of washing and settling, and Q_in is the sludge inflow rate). If the time exceeds 30 min, the system will automatically alarm and increase the sludge inflow rate, effectively inhibiting the anaerobic phosphorus release phenomenon of activated sludge and ensuring the quality of effluent and the activity of sludge.

[0021] Beneficial effects Compared with the prior art, the present invention has the following outstanding technical advantages and beneficial effects: 1. Achieve online sand removal in aeration tanks, completely solving the problem of sand accumulation and wear. This invention relies on a complete sorting system to continuously separate fine sand and gravel from returned sludge online, eliminating the need for wastewater treatment plant shutdowns and manual sludge removal. It prevents sand accumulation, tank volume reduction, aerator clogging and wear, and decreased oxygen utilization from the source, significantly reducing equipment maintenance costs and downtime losses, and effectively extending the service life of the aeration system. It permanently avoids equipment wear caused by sand and gravel accumulation, saves on the huge maintenance costs of large-scale shutdowns for sludge removal, and extends the service life of the entire aeration equipment set.

[0022] 2. Achieve targeted optimization of sludge activity, completely eliminating the drawbacks of traditional "one-size-fits-all" sludge discharge. This invention uses precise sorting based on differences in hydraulic settling rates to selectively remove aged, loose flocs with no degradation activity, while retaining high-quality activated sludge with excellent settling performance and strong pollutant degradation capabilities, which is then returned to the biological treatment system. This continuously optimizes the microbial community structure of the biological treatment system, maintains long-term stable sludge activity, stabilizes MLSS levels within the tank, and significantly improves the biological treatment system's resistance to water quality and quantity shock loads, avoiding the problems of biological treatment system activity collapse and long recovery periods. Utilizing the Stokes settling principle, it distinguishes different floc settling velocities to achieve precise screening, targeting 50,000 m³ / h. 3 / d Scale Municipal A 2 According to theoretical calculations of the / O wastewater treatment plant, after 30 days of continuous and stable operation, the sludge volume SVI can be reduced by 31%, the SS in the secondary sedimentation effluent can be reduced by 48%, the daily average amount of excess sludge produced can be reduced by 19%, the aeration power consumption per ton of water can be reduced by 11%, and the sludge's shock resistance can be significantly improved.

[0023] 3. Low-shear and gentle sorting, protecting the integrity of sludge flocs throughout the process. This invention employs a low-shear upflow laminar flow field combined with guide vanes, slow-flow nozzles, and a large-section tank configuration to control the maximum shear rate of the fluid inside the tank to below 80s throughout the entire process. -1 This value represents the critical threshold for the disintegration of activated sludge flocs. Compared to the shortcomings of traditional cyclone equipment, which easily breaks down sludge due to high-speed shearing, this method can maximize the protection of robust sludge flocs, prevent secondary damage, and achieve high sorting accuracy and good sludge activity retention.

[0024] 4. Adaptive to fluctuations in operating conditions, with extremely high operational adaptability and stability. This invention is equipped with an intelligent closed-loop control system and a double-layer adjustable annular sludge collection pipeline. It can monitor the operating parameters of biochemical sludge and the status of the sorting interface in real time. When the sludge-water interface deviates from the reference by more than 10cm, it automatically switches to the aging sludge collection pipeline at the corresponding height and simultaneously adaptively adjusts the upflow rate. It can stably maintain the sorting and stratification in the tank under high and low loads in winter and summer, as well as water quality shock conditions. This solves the problems of fixed hydraulic parameters, inability to adapt to seasonal and water quality fluctuations, and easy failure of sorting effect of traditional sorting equipment, and significantly improves the system's operational fault tolerance and versatility. At the same time, the system builds a dual closed-loop control architecture of feedforward prediction of influent load and feedback of sludge index. It can be connected to the plant's central control system to complete real-time data upload, graded fault early warning, remote parameter adjustment, and automated control to adapt to fluctuations in all operating conditions.

[0025] 5. Energy-saving and consumption-reducing pretreatment without power, and low retrofit cost. This invention cleverly utilizes the shear force of the impeller of the existing secondary sedimentation tank return pump to complete the pre-dispersion treatment of aged flocs. There is no need to add new crushing pretreatment equipment and supporting energy consumption. The bypass can be completed by relying on the existing pipeline system in the plant area, which can realize the intelligent upgrade of the sewage treatment plant without interrupting production. The retrofit is cost-effective and the overall operating energy consumption is low.

[0026] 6. Integrated self-cleaning system enables long-term unattended and maintenance-free operation. This invention features a pulse-flushing self-cleaning water distribution structure. The pulse-flushing cycle can be set to 6-12 hours, with a single high-pressure reverse flushing duration of 30-60 minutes and a high-pressure flushing water pressure of 0.4-0.8 MPa. It can periodically flush the water distribution pipeline and nozzles, effectively inhibiting biofilm adhesion and dirt scaling and clogging. This solves the pain points of traditional sorting equipment, which is prone to clogging and requires frequent manual maintenance. The equipment has fewer moving parts, a high degree of automation, and extremely low operation and maintenance costs.

[0027] 7. Strict control of hydraulic parameters to avoid secondary pollution risks. This invention limits the hydraulic retention time to no more than 30 minutes, and controls it to 15-25 minutes under normal operating conditions. This effectively inhibits phosphorus release from the anaerobic decomposition of activated sludge during the sorting process, balancing sludge activity optimization with effluent total phosphorus safety, and avoiding water quality risks caused by excessive total phosphorus in the effluent. Attached Figure Description

[0028] Figure 1 This is a schematic cross-sectional view of the sludge composite separator of the present invention; Figure 2 This is a schematic diagram of the planar structure of the annular perforated aging sludge collection system of the present invention; Figure 3 This is a schematic diagram of the structure of the central guide tube of the present invention; Figure 4 This is a schematic diagram of the planar structure of the guide vane of the present invention; Figure 5This is a schematic diagram of the planar structure of the low-shear upward flow water distribution system of the present invention; Figure 6 This is a top view of the sludge composite separator of the present invention. Figure 7 This is a process flow diagram of the entire sludge treatment system of the present invention; Figure 8 for Figure 7 Schematic diagram of the central core sorting equipment area; Figure 9 for Figure 7 Schematic diagram of the mid-to-back-end sludge treatment unit structure; Figure 10 This is a schematic diagram of the sludge composite separator of the present invention; (It should be noted in the figure that the black arrows represent the treatment process of sludge fed into the secondary sedimentation tank by the sludge return pump; the blue arrows represent the treatment process of the low-shear upflow water distribution system; the brown arrows represent the process of separating aged sludge; the green arrows represent the process of separating high-quality sludge; and the red arrows represent the sand and gravel treatment process.) Figure 11 This is a flowchart illustrating the core control logic of the method of the present invention.

[0029] Reference numerals: 1-Central guide tube, 2-Annular perforated aged sludge collection system, 3-Low shear rising flow water distribution system, 4-Guide vane, 5-Inverted conical thickening bucket, 6-Automatic sand discharge valve, 7-Annular perforated high-quality sludge return system, 8-Pulse flushing device, 9-Sludge-water mixture inlet pipe, 10-Aged sludge discharge control valve, 11-Washing water inlet pipe, 12-Aged sludge collection hole, 13-Aged sludge discharge pipe, 13-1-First layer aged sludge discharge pipe, 13-2-Second layer aged sludge discharge pipe, 14-Sand and gravel discharge pipe, 15-Reflector plate, 16-Reflector plate support, 17-Central pipe, 18-Slow flow nozzle, 19-Radial water distribution branch pipe, 20-Annular water distribution main pipe, 21-Scum collection tank, 22-Supernatant collection tank, 23-Supernatant discharge pipe, 24-Scum collection tank support, 25-Scum discharge pipe; A-Biological treatment system, a-Anoxic / anaerobic zone, B-Secondary sedimentation tank, C-Sludge composite separator, D-Sludge return pump, E-High-quality sludge return pump, F-Washing water pump, G-Sludge thickening tank, H-Sand-water separator, I-Sludge dewatering system. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1:

[0032] This embodiment provides a sludge treatment system for maintaining an activated sludge biochemical system. The system is built at the downstream end of the activated sludge process in an existing municipal wastewater treatment plant. It employs a complete architecture including secondary sedimentation tank return sludge bypass diversion, online continuous sorting, differentiated component treatment, and high-quality sludge return and reuse. (Structure reference...) Figure 1-10 As shown, the system as a whole includes: a biochemical treatment system A, anoxic / anaerobic zone a, a secondary sedimentation tank B, a sludge composite separator C, a sludge conveying unit, a washing and water supply unit, an intelligent control unit, and a back-end sludge treatment unit. Each unit works in precise coordination to achieve intelligent operation of the entire process, including sludge-gravel separation, removal of aged sludge, recovery of high-quality sludge, and maintenance of system activity and steady state.

[0033] The sludge conveying unit includes a sludge return pump D and a supporting bypass diversion pipeline. The sludge returned after sedimentation in the secondary sedimentation tank B is not entirely returned to the biological treatment tank. Instead, a portion of the sludge-water mixture is diverted through the bypass pipeline and sent to the sludge-water mixture inlet pipe 9 after being pressurized by the sludge return pump D. The controllable shear force generated by the impeller rotation of the sludge return pump D is used to break up and pre-treat only the loose, low-strength, and fragmented aged sludge flocs. High-quality activated sludge with a dense structure, intact flocs, and excellent settling performance can pass through the pump body intact without breakage or damage. This achieves a native pretreatment effect without additional energy consumption or additional equipment, improving the accuracy of subsequent hydraulic separation from the source.

[0034] The sludge return pump D is selected as a screw pump or centrifugal sludge pump, with a rated flow rate QD = (0.1~0.3)Qr, where Qr is the total return flow rate of the secondary sedimentation tank. The head HD = 10~20m, and the speed n = 300~900rpm. Variable frequency speed control is preferred, with a speed range of 30~100Hz. The pump body's flow-through components are made of ductile iron or 304 stainless steel. Selection criteria: a bypass diversion ratio of 10%~30% can meet the sorting and processing requirements under different working conditions; variable frequency speed control can adaptively adjust the sludge inlet load and respond to changes in SVI; and a head of 10~20m is sufficient to overcome the internal resistance of the pipeline and the separator.

[0035] The sludge composite separator C adopts an integrated carbon steel anti-corrosion tank structure with an upper cylindrical and lower inverted conical shape, suitable for sludge volumes of 1000~5000m³. 3For a wastewater treatment plant with a capacity of [number] / day, the diameter D of the cylindrical section is 800~2000mm, and the ratio of the height H1 to the diameter H1 / D is 1.2~1.8. The cone angle θ of the inverted cone section is 50°~70°, preferably 60°. The inner wall of the tank is coated with a ≥300μm epoxy coal tar anti-corrosion coating, and the outer wall is coated with a ≥200μm polyurethane topcoat, with a design service life of ≥15 years. The rationale for this technical setup is that H1 / D=1.2~1.8 ensures sufficient separation height in the washing zone, and the 60° cone angle facilitates rapid sliding and concentration of sand and gravel, preventing sand accumulation and clogging at the bottom of the cone.

[0036] The interior of the tank is strictly divided into three independent functional flow zones along the vertical direction: the upper overflow zone, the middle washing zone, and the lower gravity settling zone. The flow fields in the three zones are stable and layered, and their functions do not interfere with each other, precisely matching the differences in settling dynamics of different components of sludge.

[0037] The overflow zone is the area for the diffusion of mud-water mixture feed and the enrichment and separation of aged sludge. The core configuration includes a central guide tube 1, a uniform distribution device, a watershed zoning flow stabilization structure, a multi-layer annular perforated aged sludge collection system 2, and a supernatant scum separation structure.

[0038] The central guide tube 1 is made of 304 stainless steel with a wall thickness of 4~6mm, an inner diameter d1=(0.15~0.25)D, and a length L1=0.4~0.6H1. A 60°~90° tapered flare is set at the bottom, with a flare end diameter d2=1.5~2.0d1. The rationale for this technical design is that 304 stainless steel has good corrosion resistance and wear resistance, and the flared structure can reduce the feed flow rate from 1.5~2.5m / s to 0.3~0.6m / s, reducing the impact of the feed on the stratification interface inside the tank.

[0039] The central guide tube 1 is vertically and coaxially arranged at the center of the tank. Its top end is connected to the mud-water mixture inlet pipe 9, and its bottom end extends to the upper part of the washing area and is equipped with a flared structure. This can transform the feed mud-water mixture from a concentrated jet to a gentle vertical flow, preventing high-speed feed impact from damaging the solid-liquid stratification interface inside the tank. A reflector bracket 16 is fixedly installed at the bottom of the central guide tube 1. The reflector bracket 16 is fixedly equipped with a reflector plate 15 with the apex of the cone facing upwards, and the diameter of the reflector plate 15 is larger than the flared diameter at the bottom of the central guide tube 1. After the mud-water mixture impacts the reflector plate 15 downwards, it diffuses radially and evenly in all directions along the conical plate surface, achieving low-shear water distribution throughout the entire area and completely eliminating feed deviation and local turbulence problems.

[0040] Between the outer periphery of the central guide tube 1 and the inner wall of the tank, multiple guide vanes 4 are arranged in a ring array and vertically at equal intervals, forming a flow field partitioning structure. The guide vanes 4 are made of 304 stainless steel plate, with a thickness of 3~5mm, a width b=100~200mm, a length Lg=0.3~0.5H1, and the number of ring array vanes n=8~16. The included angle γ between the vanes and the radial direction is 0°~15°. Rationale for this technical design: The vertical straight plate structure can cut and eliminate local micro-vortices inside the tank, ensuring an axisymmetric laminar flow state; the number of vanes matches the tank diameter to cover the entire cross-section, and the included angle of 0°~15° allows for fine adjustment of the flow field uniformity.

[0041] The guide vanes 4 are vertically spaced between the outer periphery of the central guide tube 1 and the inner wall of the sorting tank to eliminate local micro-vortices generated in the washing zone and stabilize the flow field.

[0042] A supernatant scum discharge system is installed in the upper part of the overflow area. The scum collection tank 21 is fixed to the uppermost part of the inner wall of the tank by the scum collection tank bracket 24. It is used to collect the suspended scum on the surface of the water. The collected scum is discharged through the scum discharge pipe 25. A supernatant collection tank 22 is set below the scum collection tank 21. The supernatant collection tank 22 is connected to the supernatant discharge pipe 23. It is used to collect the clarified supernatant after sorting. The supernatant flows back to the inlet of the plant or the front end of the secondary sedimentation tank B through the supernatant discharge pipe 23 to realize the recycling of water.

[0043] A double-layered annular perforated aged sludge collection system 2 is arranged at different heights in the lower part of the overflow zone. The annular perforated pipes are made of 304 stainless steel with specifications of DN50~DN100. Several aged sludge collection holes 12 are evenly distributed on the pipe walls. The aged sludge collection holes 12 are circular holes with a diameter of φ8~φ12mm, a center-to-center distance of 30~50mm, and an opening ratio controlled at 8%~15%. The rationale for this technical design is that the evenly distributed annular openings create a uniform negative pressure zone across the tank cross-section, avoiding localized high-speed flow fields caused by single-point suction; the opening ratio of 8%~15 ensures collection efficiency while preventing excessive suction from interfering with the lower layer's settling. Each layer of the annular pipe is fixed to the tank by 2~4 radial supports.

[0044] Each layer of annular perforated pipes is connected to a corresponding aged sludge discharge pipe 13. For example, there is a first layer of aged sludge discharge pipe 13-1 and a second layer of aged sludge discharge pipe 13-2. The two layers of pipes are laid out independently and are not connected to each other. Each aged sludge discharge pipe 13 is independently equipped with an aged sludge discharge control valve 10, which can be opened and closed independently to switch the working state. The double-layer height design can adapt to the height shift of the mud-water interface caused by different water qualities, different seasons, and different sludge settling properties, so as to realize adaptive switching of sorting conditions.

[0045] The washing area is the core area for fine sludge sorting, and is equipped with a low-shear upflow water distribution system 3 throughout. The low-shear upflow water distribution system 3 includes a DN80~DN150 annular water distribution main pipe 20, DN40~DN80 radial water distribution branch pipes 19, and upward-facing φ6~φ12mm conical slow-flow nozzles 18, with a nozzle spacing of 150~300mm and a nozzle outlet velocity of 0.5~1.5m / s. The rationale for this technical setup is that the conical gradually expanding nozzles reduce the outlet velocity and increase the water distribution coverage area, while the vertical upward arrangement ensures that the upflow field has no lateral disturbance component.

[0046] The annular water distribution main pipe 20 connects to the washing water inlet pipe 11, which is externally connected to the washing water pump F. The washing water pump F is a clean water centrifugal pump with a rated flow rate QF = (0.5~2.0)Qin, where Qin is the sludge inlet flow rate of the separator. The head HF = 15~25m, and the frequency conversion range is 30~50Hz. The water source is taken from the effluent of the secondary sedimentation tank B or reclaimed water from the plant area. Selection criteria: The washing water flow rate needs to be adjusted between 0.5 and 2.0 times the sludge inlet flow rate to achieve a tank cross-section upward flow velocity of 0.2~0.5mm / s; the 15~25m head can overcome the resistance of the water distribution pipeline and nozzles. The washing water pump F preferably draws effluent from the secondary sedimentation tank B as the washing water source, ensuring stable water quality, no impurities, no need for additional water treatment, and extremely low operating costs.

[0047] A pulse flushing device 8 is integrated and installed on the 11th section of the wash water inlet pipe. The pulse flushing device 8 is activated every 6 to 12 hours, with each flush lasting 30 to 60 seconds and a flushing water pressure of 0.4 to 0.8 MPa. The normal wash water pressure is 0.05 to 0.15 MPa. The pulse flushing device 8 adopts a timed high-pressure pulse working mode. Under normal sorting conditions, it is in standby mode and does not affect the water distribution flow field. During the timed operation and maintenance phase, the high-pressure pulse water flow is activated to flush the annular water distribution main pipe 20, the radial water distribution branch pipes 19, and all slow-flow nozzles 18 in reverse along the pipeline. This thoroughly removes biofilm, sludge scale, and small blockage impurities from the pipe wall, preventing the equipment from failing due to long-term clogging and achieving unattended self-cleaning.

[0048] A gravity settling zone is equipped with an inverted conical thickening hopper 5, with the tank cross-sectional area gradually decreasing from top to bottom to achieve rapid concentration and settling of heavy components. An annular perforated high-quality sludge return system 7 is installed in the upper part of the inverted conical thickening hopper 5. The annular perforated high-quality sludge return system 7 uses DN80~DN150 304 stainless steel pipe and is installed at a height h=0.3~0.5H2 from the bottom of the inverted conical thickening hopper 5, where H2 is the total height of the inverted conical section. The opening specifications are the same as those of the annular perforated aged sludge collection system 2. Rationale for this technical setup: This location is the core area for the settling and enrichment of high-quality activated sludge; the annular collection system allows for undisturbed extraction from the highest concentration layer.

[0049] The bottom of the inverted conical thickening bucket 5 is equipped with a sand and gravel discharge pipe 14, and an automatic sand discharge valve 6 is installed on the sand and gravel discharge pipe 14. The valve adopts an intermittent opening and closing mode to periodically discharge the fine sand, inorganic particles, and mud impurities that have settled and accumulated.

[0050] The annular perforated high-quality sludge return system 7 connects to the high-quality sludge return pump E. Pump E is a screw pump with a rated flow rate QE = (0.5~0.9) Qin and a head HE = 8~15m, preferably with variable frequency speed control. Selection criteria: The high-quality sludge return flow rate must match the influent sludge flow rate to ensure sludge balance in the biological treatment system; a low head is sufficient for the transport conditions of returning to the anoxic / anaerobic zone a. Pump E provides pressurized transport, precisely returning the sludge to the anoxic / anaerobic zone a of the biological treatment system A, supplementing the system's functional microbial community and optimizing the sludge population structure.

[0051] The system's backend forms a complete closed-loop treatment chain: the aged sludge output end of the sludge composite separator C is connected to the sludge thickener G, which is a gravity thickener with a solids load ≤ 50 kg / (m³). 2 ·d) After concentration, the sludge has a moisture content of 96%~98%. After concentration and volume reduction, it is sent to the sludge dewatering system I to complete solid-liquid separation. The sand and gravel output end is connected to the sand-water separator H. The sand-water separator H is a spiral sand-water separator with a processing capacity of 2~10L / s, a separation particle size ≥0.2mm, and a separation efficiency ≥95%. The sludge outlet of the sand-water separator H and the discharge end of the sludge thickening tank G are both connected to the sludge dewatering system I. The sludge dewatering system I uses a belt filter press or a centrifugal dewatering machine. The inlet sludge moisture content is 96%~98%, and the outlet sludge moisture content is ≤80%. The dewatered sludge is transported off-site for disposal.

[0052] The clean water after sand-water separation is returned to the plant's process system, and the separated sludge and impurities are collected in the sludge thickening tank G for unified disposal. There is no external pollution discharge and no material waste throughout the entire process.

[0053] Supporting structure foundation operating parameters: Biochemical treatment system A (optional) 2 The process involves an oxidation ditch, SBR, and CASS. In the anoxic / anaerobic zone a, the MLSS concentration of sludge is maintained at 3000~5000 mg / L, and DO ≤ 0.5 mg / L. High-quality returned sludge is introduced at the front end of the anoxic / anaerobic zone a, mixing with the influent and returned sludge before entering the biological treatment system. Secondary sedimentation tank B is a radial / horizontal flow sedimentation tank with a surface loading rate q = 0.8~1.5 m³ / h. 3 / (m 2 ·h), the concentration of returned sludge MLSSr = 8000~12000mg / L, the total amount of returned sludge in secondary sedimentation tank B Qr = (0.5~1.0)Q, where Q is the influent flow rate.

[0054] The intelligent control unit is the core of the system's automated and adaptive operation. The hardware includes an online MLSS detector, an SV30 acquisition module, an SVI calculation module, a radar-type mud-water interface sensor, and a programmable control module. The mud-water interface sensor has an accuracy of ±5mm. The monitoring module collects MLSS and SV30 data from the biological treatment tank every 2 hours and calculates the SVI. It also collects key parameters such as the mud-water interface height in the sorting tank, the washing water flow rate, and the sludge inlet flow rate.

[0055] The control module has built-in SVI grading and adjustment thresholds and sludge-water interface offset judgment thresholds: SVI ≤ 100 mL / g maintains a split load of 10~15; 100 < SVI ≤ 150 mL / g maintains a normal load; 150 < SVI ≤ 200 mL / g increases the split ratio to 20~30; SVI > 200 mL / g operates at full load and pushes an advanced alarm; when the sludge-water interface offset relative to the reference > 10 cm, it automatically switches the working height of the first layer of aged sludge discharge pipe 13-1 and the second layer of aged sludge discharge pipe 13-2 (this automatic switching is just an example; in actual operation, several layers of aged sludge discharge pipes 13 can be designed so that the appropriate height of the aged sludge discharge pipe 13 can be selected more accurately according to the sludge-water interface to collect aged sludge). When an increase in SVI and deterioration in sludge settling performance are detected, the control module increases the sludge inlet load of the sludge composite separator C to enhance the sludge sorting effect.

[0056] The intelligent control unit connects to the plant's central control system via Modbus TCP / IP or OPC protocol, adds feedforward predictive control logic, collects influent COD and ammonia nitrogen in real time, predicts load fluctuations 20-30 minutes in advance and adjusts the sorting load, and realizes data upload, fault alarm, remote parameter adjustment, and automatic generation of operation reports. Based on real-time monitoring data, the control module adaptively adjusts the effluent flow rate of the washing water pump F and / or switches the annular perforated aging sludge collection system 2 at different heights to work, stabilizing the sorting interface in the tank.

[0057] It needs to be emphasized again that the intelligent control unit of this invention can be implemented using a "feedforward + feedback" dual closed-loop control architecture, the specific logic of which is as follows: (a) Feedforward regulation (based on influent water quality prediction) The system collects real-time online data such as influent flow rate Q, influent COD, and influent ammonia nitrogen, and uses a built-in algorithm to predict the load change trend of the biochemical system in the next 2-4 hours. Predicting a load increase (COD or ammonia nitrogen increase > 20%): The system increases the sludge feed load 10-30 minutes in advance (the split ratio is increased from 15% to 25%) to remove aging sludge in advance and make room for new sludge; Predicted load reduction: The system reduces the sludge feed load to prevent excessive loss of high-quality sludge during sorting; (II) Feedback regulation (based on real-time SVI monitoring) The system automatically collects MLSS and SV30 every 2 hours, calculates SVI and executes the following logic: 1. SVI≤100: maintain conventional separation load (split ratio 10%~15%), and upflow flow velocity is 0.30~0.35mm / s; 2. 100<SVI≤150: maintain conventional separation load, and finely adjust the upflow flow velocity to 0.25~0.30mm / s (reduce washing intensity to protect sludge with weak settling performance); 3. 150<SVI≤200: trigger increasing the sludge inlet load for separation (the split ratio is increased to 20%~30%), adjust the upflow flow velocity to 0.35~0.45mm / s to strengthen the removal of aged sludge, and simultaneously trigger a central control early warning "High SVI, it is recommended to pay attention to sludge activity"; 4. SVI>200: trigger a high-level alarm "Serious sludge bulking / aging, manual intervention is recommended", the separator operates at full load (split ratio 30%), and simultaneously push diagnosis suggestions: check inlet water quality, investigate toxic substances, and evaluate nutrient ratio; (III) Feedback regulation (based on sludge-water interface height) The system monitors the layered interface in real time through an in-tank sludge-water interface sensor (radar type or hydrostatic type, accuracy ±5mm): 1. Interface moves up >10cm (relative to the reference): the aged sludge layer thickens or the settling performance deteriorates, the system automatically switches to the upper aged sludge discharge pipe 13-1, simultaneously reduces the washing water flow by 5%~10%, and reduces the upflow flow velocity to prevent high-quality sludge from being entrained; 2. Interface moves down >10cm: the aged sludge layer thins or the settling performance improves, the system automatically switches to the lower aged sludge discharge pipe 13-2, simultaneously increases the washing water flow by 5%~10% to ensure that aged fragments fully float up; 3. Interface fluctuates violently (持续>10min above ±15cm): the system determines it as water quality impact, triggers an alarm of "abnormal separation interface", and suggests manual inspection of inlet water quality; (IV) Linkage mechanism with central control system The system of the present invention is connected to the central control system of a sewage treatment plant through ModbusTCP / IP or OPC protocol to realize the following linkage: (1) Data upload: MLSS, SVI, SV30, operating status of the separator (sludge inlet flow, washing water flow, working layer, cumulative operating time) are uploaded to the monitoring interface of the central control system in real time; (2) Alarm push: when SVI>150, push "sludge aging early warning"; when SVI>200, push "serious sludge bulking alarm"; when the equipment fails, push the specific fault code; (3) Remote control: authorized personnel can remotely adjust the operating parameters of the separator (split ratio setting value, elutriation water flow setting value, pulse flushing cycle, etc.) through the central control system; (4) Operation report: the system automatically generates daily, weekly and monthly reports, including trend graphs of key indicators (SVI change curve, MLSS change curve, sludge discharge statistics, etc.) for operation and maintenance personnel to analyze.

[0058] Example 2:

[0059] This example is implemented based on the sludge treatment system supporting Example 1. The whole system includes a biochemical treatment system A, an anoxic / anaerobic zone a, a secondary sedimentation tank B, a composite sludge separator C, a sludge conveying unit, an elutriation water supply unit, an intelligent control unit, and a rear-end sludge disposal unit. The whole operation process is divided into four core operation steps, with built-in standardized hydraulic and automatic control threshold parameters, which adapts to three typical working conditions of sewage: low temperature and low load in winter, high temperature and high load in summer, and water quality sudden change impact; the fluid shear rate and hydraulic retention time are strictly controlled throughout the process to avoid problems such as sludge floc crushing, anaerobic phosphorus release in the tank, pipeline nozzle blockage, and separation accuracy failure. All control rules and working condition adaptation logic uniformly adopt the given standardized parameters for implementation. The specific operation process and complete control specifications are as follows: S1. Bypass split flow + non-power pretreatment step: when the system is in normal continuous operation, 10% to 30% of the returned sludge mixed liquor is constantly split by the bypass from the main pipeline of the returned sludge of the secondary sedimentation tank B, and the split ratio can be adaptively adjusted according to the sludge concentration of the biochemical tank; the split sludge mixed liquor is conveyed to the mixed sludge inlet pipe 9 through the sludge return pump D, and the pretreatment is completed by means of the inherent shear field generated by the rotation of the impeller of the sludge return pump D, which only disperses the aged sludge fragments with loose structure, low floc strength and no pollutant degradation activity, while the robust zoogloeal flocs with compact structure, good sedimentation performance and high activity are not damaged by shearing, and the original floc structure and biological activity are completely retained. This step does not require additional power equipment or additional energy consumption, and only relies on the original pump equipment in the plant to complete the pretreatment, which greatly improves the component distinction effect of subsequent hydraulic separation.

[0060] S2. Low-shear precise hydraulic elutriation separation step: the pretreated sludge mixed liquor is stably fed into the central guide cylinder 1 through the mixed sludge inlet pipe 9, uniformly diffused through the 60°~90° conical flaring structure at the bottom and the reflector 15, and then enters the elutriation zone; the elutriation water pump F continuously supplies water, forming a uniform vertical laminar upflow on the cross section of the elutriation zone. The upflow velocity adopts a graded control standard, and stepless adjustment is realized through frequency conversion speed regulation of the elutriation water pump F: 1. Optimal working flow rate under conventional working conditions: 0.30~0.35mm / s; 2. High-load working condition in summer (influent load > 120% of the designed value): 0.35~0.50mm / s, which enhances the upward carrying capacity of aged flocs; 3. Low-load operation in winter (influent load < 80% of design value): 0.20~0.30mm / s, to avoid excessive washing and loss of high-quality sludge. The sorting and stratification mechanism is as follows: Aged sludge flocs are fragmented and have low density, with a settling rate of only 0.05~0.15 mm / s. Unable to overcome the upward flow resistance, they float upwards with the water flow and enter the annular perforated aged sludge collection system 2 through the aged sludge collection hole 12. They are then transported to the sludge thickening tank G through the aged sludge discharge pipe in the corresponding working state. High-quality activated sludge flocs have a dense structure and high density, with a settling rate of 0.4~0.8 mm / s. They can penetrate the upward flow and settle downwards to the upper enrichment layer of the inverted conical thickening hopper 5. They are collected by the annular perforated high-quality sludge return system 7 and transported to the anoxic / anaerobic zone a of the biochemical treatment system A via the high-quality sludge return pump E. Sand and inorganic silt have the highest density and settle rapidly to the bottom of the inverted conical thickening hopper 5. They are intermittently and automatically discharged through the sand discharge pipe 14 and the automatic sand discharge valve 6, and sent to the sand-water separator H for treatment.

[0061] Full-process shear constraint: Relying on the three-fold structure of eliminating local vortices with guide vanes 4, reducing the velocity of the outflow jet with slow-flow nozzles 18, and achieving low-velocity laminar flow with a large cross-section of the tank, the maximum shear rate of the fluid inside the sorting tank is controlled at 80s. -1 80s -1 The critical threshold for activated sludge floc breakage can be determined by indirect calculation of the shear rate through influent flow rate, tank size, and water distribution structure parameters. The shear rate can be verified periodically using tracer tests to prevent shear damage to robust sludge flocs throughout the process.

[0062] Hydraulic Retention Time Control: The effective hydraulic retention time (HRT) of the sludge-water mixture in the sludge composite separator C is calculated using the formula HRT = V_eff / Q_in, where V_eff is the effective volume of the washing zone + gravity settling zone, and Q_in is the real-time sludge inflow rate. Under normal operating conditions, HRT is controlled at 15-25 minutes, with a mandatory upper limit of ≤30 minutes. The system calculates HRT in real-time; if the value exceeds 30 minutes, an automatic alarm is triggered, and the sludge inflow rate is increased while the washing water flow rate is decreased to inhibit anaerobic decomposition and phosphorus release of the sludge in the tank, preventing excessive total phosphorus in the effluent. S3. Intelligent Adaptive Dynamic Operating Condition Control Steps: The system adopts a triple closed-loop control logic of "influent water quality feedforward prediction + SVI sludge feedback + sludge-water interface feedback," collecting real-time data on influent COD, ammonia nitrogen, MLSS in the biological treatment tank, SV30, and the sludge-water interface height in the tank. It switches between interfaces and adapts to multiple operating conditions by executing two sets of control rules.

[0063] Supporting SVI graded load control standard: 1. SVI≤100mL / g: indicates excellent sludge settling performance, maintaining a conventional sludge feed ratio of 10%~15%; 2.100mL / g<SVI≤150mL / g: The sludge settling performance is judged to be normal, and the conventional sludge feed ratio should be maintained at 10%~15%; 3.150mL / g<SVI≤200mL / g: If the sludge settling performance is determined to be deteriorated (early stage of aging / expansion), the feed sludge diversion ratio will be automatically increased to 20%~30% to enhance the removal of aged sludge; 4. SVI > 200 mL / g: This indicates severe sludge bulking / aging. The equipment will operate at maximum sorting load, and a high-level alarm will be simultaneously triggered to prompt manual intervention.

[0064] Criteria for determining mud-water interface switching: 1. The fluctuation of the mud-water interface relative to the reference height is <5cm: Maintain the current washing water flow rate and the aged sludge collection pipeline unchanged; 2. The mud-water interface shifts upward by more than 10cm relative to the reference: It is determined that the aged sludge enrichment layer has floated up, and the first layer of aged sludge discharge pipe 13-1 is automatically switched to operation, and the flow rate of the washing water pump F is slightly reduced at the same time. 3. The mud-water interface shifts down more than 10cm relative to the reference: It is determined that the aged sludge enrichment layer has settled, and the second layer of aged sludge discharge pipe 13-2 is automatically switched to operation, and the flow rate of the washing water pump F is increased slightly at the same time. 4. If the interface fluctuates continuously for more than 30 minutes and cannot be stabilized: Push an alarm for abnormality in the sorting interface, prompting maintenance personnel to check the incoming water quality.

[0065] Three typical wastewater operating conditions adaptive operation schemes: 1. Low temperature and low load conditions in winter: In winter, the water temperature is low, the metabolic activity of microorganisms is weakened, the sludge is prone to slight aging, and the sludge-water interface moves upward as a whole; after the system recognizes the signal of a slight increase in SVI and the upward movement of the interface, it automatically switches the first layer of aging sludge discharge pipe 13-1, and adjusts the upward flow velocity to 0.30~0.50mm / s. At the same time, it reduces the sludge loading load in the sorting to prevent the loss of high-quality sludge and stabilize the sludge concentration and bacterial activity in the biological treatment tank.

[0066] 2. High temperature and high load conditions in summer: In summer, the influent load is relatively high, and the system sludge proliferates, producing a large number of fine and aged flocs, and the sludge-water interface shifts downward; the system automatically switches to the second layer of aged sludge discharge pipe 13-2, reduces the upward flow velocity to 0.20~0.30mm, and simultaneously increases the sorting sludge load by 20%~30%, and removes aged sludge with high intensity to avoid long-term accumulation and aging of sludge.

[0067] 3. Water quality shock fluctuation conditions: When influent COD and ammonia nitrogen experience sudden and significant fluctuations, the system relies on feedforward prediction logic to adjust the sorting load 20-30 minutes in advance, simultaneously and dynamically fine-tuning the upward flow velocity and switching collection pipelines. Stable stratification is restored quickly, preventing sorting failure and sludge activation collapse. Throughout full-condition operation, the system maintains a shear rate <80s. -1 The two mandatory constraint parameters, HRT≤30min, are not affected by seasonality or water quality fluctuations.

[0068] S4. Timed Pulse Self-Cleaning Maintenance Steps: The intelligent control unit has a built-in timer program. The pulse flushing device 8 has a preset flushing cycle of 6~12h, and the system default cycle is 8h. It can be adjusted according to the hardness of the water and the viscosity of the sludge on site. The duration of a single flush is 30~60s, with a default of 45s. The water pressure for regular washing is 0.05~0.15MPa, and the high-pressure water pressure for flushing is 0.4~0.8MPa.

[0069] Equipment execution logic: After the flushing cycle is reached, the normal flushing water supply is automatically cut off, and a high-pressure pulse water flow is started to flush the annular water distribution main pipe 20, the radial water distribution branch pipes 19, and all slow-flow nozzles 18 in reverse to remove biofilm, sludge scale, and nozzle blockage impurities from the pipe walls. After flushing is completed, the normal flushing water supply is automatically restored without manual unblocking, so as to achieve long-term unattended and stable operation of the equipment.

[0070] In this method, the complete set of backend material handling specifications includes: 1. The aged sludge discharged from the sludge composite separator C is transported to the sludge thickening tank G, which is a gravity thickening tank with a solids load ≤ 50 kg / (m³). 2 •d) After thickening, the sludge has a moisture content of 96%~98%, and the thickened sludge is sent to the sludge dewatering system I; 2. The sand and gravel discharge pipeline is connected to the sand-water separator H. The sand-water separator H is a spiral type with a processing flow rate of 2~10L / s. It can separate inorganic sand and gravel ≥0.2mm with a sand and gravel separation efficiency ≥95%. 3. The sand-water separator H separates clean water and returns it to the plant's process pipelines, while the bottom sludge and impurities flow into the sludge thickening tank G and are then uniformly sent to the sludge dewatering system I. 4. Sludge dewatering system I uses a belt filter press or centrifugal dewatering equipment. The feed moisture content is 96%~98%, and the moisture content of the dewatered sludge cake is ≤80%. The dewatered sludge is transported off-site for disposal.

[0071] Theoretical deduction and design example 3: 1. Application Scenario Setting This simulation example uses 50,000 m 3 / d Scale Regular Municipal A 2 Using the / O wastewater treatment plant as an application scenario, theoretical calculations of its operational performance were conducted, based on the complete sludge treatment system and process described earlier. The effective volume of the plant's biological treatment tank is 25,000 m³. 3 The total flow rate of returned sludge in the secondary sedimentation tank is Q_r = 0.7Q, where Q is the total daily influent flow rate of the plant, and the concentration of returned sludge (MLSS_r) is 10000 mg / L. Before the system was put into operation, the biological treatment tank had long suffered from sludge aging defects, and the operating indicators were continuously abnormal. The stable range of SVI was 160~190 mL / g, the SS in the effluent of the secondary sedimentation tank reached 18~25 mg / L, and the sludge discharge frequency was 2~3 times per day.

[0072] 2. Theoretical Derivation of Sorting Mechanism The sorting and stratification effect is achieved based on Stokes' law of particle settling: the particle settling velocity is positively correlated with the density difference between the particle and the water and the square of the particle size.

[0073] The aged sludge has a loose floc structure with a density ranging from 1.005 to 1.015 g / cm³. 3 The settling rate is only 0.05~0.15 mm / s; Healthy, high-quality activated sludge flocs have a dense structure with a density ranging from 1.025 to 1.040 g / cm³. 3 The settling rate is 0.4~0.8 mm / s.

[0074] The system's washing zone maintains a vertical upward flow field of 0.2~0.5 mm / s. The settling velocity of aged flocs is less than the upward flow velocity, so they float to the surface and are collected with the water flow; the settling velocity of high-quality flocs is higher than the upward flow velocity, so they are enriched and recovered downwards.

[0075] The extrapolation is that for every 10% decrease in the proportion of aged flocs in the system, the overall SVI can be reduced by 15~25 mL / g. In this scenario, the initial average SVI is 175 mL, and the target equilibrium SVI is 120 mL / g. The proportion of aged flocs needs to be reduced by 25%~35%, and the system can reach steady-state equilibrium after 30 days of continuous and stable operation.

[0076] 3. Baseline operating indicators before system commissioning (current theoretical baseline)

[0077] 4. Steady-state prediction operation data after 30 days of operation The system operation control parameters match all the constraints mentioned above: the sludge feed rate is 15%~25% of the total return flow rate, the washing water flow rate is 0.8~1.2 times the sludge feed flow rate, the optimal upward flow velocity in the washing zone is 0.30~0.35 mm / s, and the fluid shear rate inside the tank is less than 80 s⁻¹. -1 The hydraulic retention time is controlled at 15-25 minutes, with a forced upper limit of 30 minutes. Based on settling dynamics theory, the steady-state prediction indicators after 30 days of continuous operation are as follows:

[0078] 5. Theoretical prediction of auxiliary operation effect (1) Effect of reducing excess sludge Before commissioning, the moisture content was 98%, and the daily sludge discharge was approximately 320 cubic meters. 3 After being put into operation, the temperature dropped to 260m. 3 Overall sludge volume reduction of 19%; Mechanism: Traditional one-cut sludge discharge simultaneously discharges high-quality sludge, while this solution only separates aged flocs, and functional sludge is recycled and reused, significantly reducing the total amount of sludge discharged.

[0079] (2) Aeration energy consumption reduction effect The power consumption for aeration per ton of water is reduced from 0.28 kWh / m³. 3 The energy consumption was reduced to 0.25 kWh, a decrease of 11%. Mechanism: Healthy sludge has stronger microbial metabolic activity, which improves the efficiency of pollutant degradation under the same dissolved oxygen supply conditions and reduces the demand for aeration oxygen supply.

[0080] (3) Resistance of the biochemical system to water quality shock When the influent COD suddenly increases from 350mg / L to 620mg / L, the original process takes 48 hours to recover to meet the COD standard in the effluent; after installing this system, the recovery time is shortened to 24 hours, and the shock resistance is improved by 50%; Mechanism: The proportion of dense functional bacterial flocs in the pool is increased, the microbial community structure is more stable, and the ability to buffer water quality fluctuations is stronger.

[0081] 6. Theoretical Prediction Conclusions Based on Stokes' law of settling and the well-known water treatment mechanism of activated sludge floc density differences, it can be deduced that this complete sludge treatment system can be applied to 50,000 m³ / h. 3 / d Municipal A 2 After 30 days of continuous and stable operation, the sludge volume index (S) of the / O wastewater treatment plant decreased by approximately 31%, the suspended solids (SS) in the secondary sedimentation effluent decreased by 48%, the excess sludge production decreased by 19%, and the power consumption for aeration operation decreased by 11%. All predicted values ​​are derived based on the fundamental dynamics theory of water treatment and possess the theoretical inevitability that can be predicted by those skilled in the art, which can corroborate the optimization effect of the complete system of this invention on the problems of sludge aging and declining biochemical efficiency.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A sludge treatment system for maintaining an activated sludge biological treatment system, characterized in that, It includes a biochemical treatment system (A), a secondary sedimentation tank (B), a sludge composite separator (C), a washing and water supply unit, a sludge conveying unit, and an intelligent control unit; the sludge composite separator (C) is configured as a separator tank with an upper cylindrical shape and a lower inverted conical shape, and the interior of the separator tank is divided into an overflow zone, a washing zone, and a gravity settling zone from top to bottom; The overflow zone is equipped with a central guide tube (1), a watershed zoning structure, a uniform distribution device, a supernatant scum discharge system, and a multi-layered annular perforated aging sludge collection system (2) arranged at different heights; the washing zone is equipped with a low-shear rising flow water distribution system (3), which is connected to a pulse flushing device (8); the gravity settling zone is equipped with an inverted conical thickening hopper (5), an annular perforated high-quality sludge return system (7), and a sand and gravel discharge system; The secondary sedimentation tank (B) is connected to the mud-water mixture inlet pipe (9) of the central guide tube (1) via a sludge conveying unit and a sludge return pump (D); the washing water supply unit includes a washing water pump (F), which is connected to the washing water inlet pipe (11) of the low shear rising flow distribution system (3). The intelligent control unit includes a monitoring module and a control module. The monitoring module is used to collect the sludge operating parameters of the biochemical tank and the sludge-water interface data inside the sorting tank. The control module is configured to adjust the outflow of the washing water supply unit and / or switch the annular perforated aging sludge collection system (2) of different heights to work based on the real-time monitoring data. The annular perforated aging sludge collection system (2) has several aging sludge collection holes (12) evenly opened on the annular pipe wall. Each layer of annular perforated pipe is connected to an aging sludge discharge pipe (13). Each layer of aging sludge discharge pipe (13) is equipped with an aging sludge discharge control valve (10). The supernatant scum discharge system includes a scum collection tank (21) and a supernatant collection tank (22), the supernatant collection tank (22) being connected to a supernatant discharge pipe (23); the scum collection tank (21) is fixedly installed on the inner wall of the sorting tank by a scum collection tank bracket (24), and the scum collection tank (21) is connected to a scum discharge pipe (25). The sand and gravel discharge system includes a sand and gravel discharge pipe (14) and an automatic sand discharge valve (6); the annular perforated high-quality sludge return system (7) is connected to a high-quality sludge return pump (E), and the output pipeline of the high-quality sludge return pump (E) is connected to the anoxic / anaerobic zone (a) of the biochemical treatment system (A); The aged sludge output end of the sludge composite separator (C) is connected to the sludge thickening tank (G), and the sand and gravel output end is connected to the sand-water separator (H). The sludge-water outlet of the sand-water separator (H) and the discharge end of the sludge thickening tank (G) are both connected to the sludge dewatering system (I).

2. The sludge treatment system for maintaining an activated sludge biological system according to claim 1, characterized in that, The uniform distribution device includes a reflector bracket (16) and a reflector (15) with the cone apex facing upward. The reflector bracket (16) is fixedly installed at the bottom of the central guide tube (1). The bottom of the central guide tube (1) is configured as a flared structure, and the diameter of the reflector (15) is larger than the diameter of the flared structure.

3. The sludge treatment system for maintaining an activated sludge biological system according to claim 1, characterized in that, The watershed partition structure consists of multiple vertically arranged and spaced guide vanes (4). The guide vanes (4) are arranged between the outer periphery of the central guide tube (1) and the inner wall of the sorting tank to eliminate local micro-vortices generated in the washing area and stabilize the flow field.

4. The sludge treatment system for maintaining an activated sludge biological system according to claim 1, characterized in that, The low-shear upward flow water distribution system (3) includes an annular water distribution main pipe (20), radial water distribution branch pipes (19), and upward-facing slow-flow nozzles (18). The annular water distribution main pipe (20) is connected to the washing water inlet pipe (11), and the washing water inlet pipe (11) is equipped with the pulse flushing device (8).

5. The sludge treatment system for maintaining an activated sludge biological system according to claim 1, characterized in that, The annular perforated high-quality sludge return system (7) is located in the upper middle part of the inverted conical thickening hopper (5); the sand and gravel discharge pipe (14) of the sand and gravel discharge system is installed at the bottom of the sorting tank, and the sand and gravel discharge pipe (14) is equipped with an automatic sand discharge valve (6).

6. The sludge treatment system for maintaining an activated sludge biological system according to claim 1, characterized in that, The monitoring module collects operating parameters including mixed liquor suspended solids concentration (MLSS) and sludge settling ratio (SV30), and calculates the sludge volume index (SVI) based on the collected parameters. SVI grading control rule: SVI≤100mL / g, maintain 10%~15% split load; 100 < SVI ≤ 150 mL / g; maintain normal loading. When SVI < 150 and ≤ 200 mL / g, the split ratio is increased to 20%~30%; when SVI > 200 mL / g, the system is at full load and an advanced alarm is triggered; when an increase in SVI and deterioration in sludge settling performance are detected, the control module increases the sludge feed load of the sludge composite separator (C) to enhance the sludge separation effect.

7. A sludge treatment method for maintaining an activated sludge biological system, characterized in that, The sludge treatment system described in any one of claims 1 to 6 is implemented by comprising the following steps: S1. Sludge feed pretreatment: The sludge-water mixture is drawn out from the bypass of the return sludge pipeline of the secondary sedimentation tank (B). The shearing action generated by the impeller when the sludge return pump (D) is working is used to break up the loosely structured aged sludge flocs in the sludge-water mixture, thus completing the non-powered pretreatment. S2, Low-shear hydraulic washing and sorting: The pretreated mud-water mixture is sent into the sorting tank through the mud-water mixture inlet pipe (9) and the central guide tube (1). The washing water pump (F) supplies water to the low-shear upward flow distribution system (3) through the washing water inlet pipe (11), forming an apparent vertical upward flow field of 0.2-0.5 mm / s in the tank cross-section within the washing zone. The aged sludge flocs have a low settling velocity and flow upward with the upward flow, passing through the aged sludge collection hole (12) and the annular perforation. After being collected by the aging sludge collection system (2), the sludge is discharged through the corresponding aging sludge discharge pipe; the high-quality activated sludge flocs have excellent settling performance, penetrate the rising flow and settle downwards, and after being collected by the annular perforated high-quality sludge return system (7), they are transported back to the anoxic / anaerobic zone (a) of the biochemical treatment system (A) by the high-quality sludge return pump (E); heavy inorganic matter including sand and gravel settles to the bottom of the inverted conical thickening hopper (5) and is intermittently discharged through the sand and gravel discharge pipe (14) in conjunction with the automatic sand discharge valve (6); S3, Dynamic operating condition control: Real-time collection of MLSS, SV30, and mud-water interface data; if the interface offset is <5cm, maintain the parameter; if the offset is >10cm, switch the working collection height corresponding to the aging sludge discharge pipe (13) to adapt to operating condition fluctuations; if the interface continues to fluctuate for more than 30 minutes, push an abnormal alarm. S4. Periodic self-cleaning operation and maintenance: The pulse flushing device (8) starts high-pressure reverse flushing every 6~12 hours, each time for 30~60 seconds, to remove dirt and blockages from the water distribution pipes and nozzles.

8. The sludge treatment method for maintaining an activated sludge biological system according to claim 7, characterized in that, Throughout the entire sorting process, the maximum shear rate of the fluid inside the sorting tank must be kept below 80s. -1 This prevents robust activated sludge flocs from being sheared and broken.

9. The sludge treatment method for maintaining an activated sludge biological system according to claim 7, characterized in that, The residence time of the sludge-water mixture in the sludge composite separator (C) is controlled, which is normally 15-25 minutes and has a mandatory upper limit of ≤30 minutes. If the threshold is exceeded, the system will automatically alarm and increase the sludge inflow rate to inhibit anaerobic phosphorus release from the sludge in the tank.

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