High-density gas stripping clarification device and method

Abstract

The invention belongs to the technical field of water treatment, and particularly relates to a high-density gas stripping clarification device and method. The high-density gas stripping clarification device comprises a clarification tank main body, a grid reaction system consisting of an ascending column and a descending column, a rotational flow reaction system consisting of two rotational flow reaction areas, a pipeline mixer, a sludge collection tank, an inclined pipe, a gas stripping sludge discharge pipe, a sludge reflux pump, related connecting pipelines and control valves, grid flocculation is performed outside the clarification tank, and rotational flow reaction co-directional flocculation is performed inside the clarification tank; and the sludge in the clarification tank is pumped back into the water inlet pipe in front of the rotational flow reaction area through a sludge reflux pump after being subjected to gas stripping to be concentrated in the sludge collecting tank, so that sludge reflux is formed. When the turbidity of the raw water changes within 1500NTU, the turbidity of the effluent purified by the clarification tank reaches within 0.5-1.0 NTU, and the surface load reaches 15-18m / h. According to the invention, the water quality of the discharged water is improved, the investment and the occupied area are reduced, and the occupied area and the investment are only 50-70% of those of the traditional process.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a high-density air lift clarification device and method. Background Art

[0002] For nearly a hundred years, the treatment process of water plants has basically been based on four processes: coagulation, sedimentation, filtration and disinfection. With the continuous improvement and development of water supply theory, changes have been promoted in process design and treatment structure forms. Different from the principle of separating flocs by free sedimentation under gravity in ordinary sedimentation tanks, the clarification process strengthens the traditional water treatment technology, integrating the mixing of reagents, flocculation and sedimentation processes. It is a water treatment process with a simple structure and small footprint. In the clarification process, the small flocs generated by coagulation rise in the clarification column with the raw water. During the rising process, the flocs gradually increase due to frequent collisions and form larger flocs. This process increases the concentration of the floc layer, enhances the interception capacity of particulate matter, and improves the water purification effect. Therefore, clarification tanks have broad application prospects in small and medium-sized water plants.

[0003] However, in actual applications, clarifiers are sensitive to changes in the amount, quality and temperature of raw water. The reason is that the turbidity of surface raw water is usually low, resulting in a small number of flocs, fine particles, light weight, and easy floating. These problems will significantly affect the formation and stability of the floc layer, and thus affect the treatment effect of the clarification process and the quality of the effluent. Especially when the raw water changes significantly in a short period of time, the stability of the floc layer is easily affected, resulting in deterioration of the effluent quality. In addition, some types of clarifiers, such as hydraulic circulation clarifiers, consume a lot of energy during operation. This is mainly reflected in the head loss at the nozzles and throats. The water flow rate in these parts is faster, and the energy loss is correspondingly larger.

[0004] In recent years, Chinese researchers have mainly studied and transformed clarifiers through micro-eddy theory and shallow pool theory. In 2003, Wang Xijun et al. introduced the structural characteristics and technical parameters of an improved hydraulic circulation clarifier in the "Technical and Economic Discussion on the Potential Development and Transformation of Hydraulic Circulation Clarifiers" in "Railway Standard Design". The grid reaction replaced the original nozzle mixing flocculation, and the inclined tube sedimentation was used to improve the sedimentation efficiency. The water production capacity of the modified hydraulic circulation clarifier can be increased by 1 to 2 times, the impact load resistance is greatly improved, and the adaptability is enhanced. Patent 200610026116.8 "A High-efficiency and Energy-saving Water Purification Process and Device" replaced the nozzle with a mesh spoiler device to strengthen the flocculation reaction, but in general, the above-mentioned transformation has the problem of short flocculation time. In 2006, Sun Jianwei et al. introduced the structural characteristics and technical parameters of an improved hydraulic circulation clarifier in "Application of Improved Hydraulic Circulation Clarifier in Advanced Wastewater Treatment" in "Chemical Technology and Economy". The double nozzles replaced the original single nozzle and added inclined tube sedimentation, but the transformation did not completely eliminate the nozzles, and the energy consumption was high. Patent CN03147869.7 "High-efficiency composite clarification reaction tank and coagulation and sedimentation water treatment process" provides a high-efficiency composite clarification reaction tank and coagulation and sedimentation water treatment process. The process is similar to the structure of the French high-density sedimentation tank, and PAM is added as a coagulant to improve the sedimentation efficiency, but no sludge return system is set. Patent CN103623623A proposes a method for uniforming the mud layer of the clarifier of a water treatment system. A swirl distribution pipe is arranged in the floc layer to form a swirl floc layer, and the floc layer is subjected to appropriate hydraulic disturbance, which not only increases the collision probability of particles in the floc layer, but also improves the uniformity of the floc layer, avoiding the short-flow problem that may be caused by the increase in the cross-sectional area of ​​the large pool, but the patent does not involve the reaction system and mud discharge solution in the clarifier. The above solution mainly studies and transforms the clarifier through micro-vortex theory and shallow pool theory, but still does not solve the problem of changes in water quality and water quantity during the operation of the clarifier, and it is difficult to meet the requirements of stable operation of the clarifier. Therefore, the operator of the clarifier generally needs to have high professional knowledge and skills, and needs to pay close attention to the changes in the water quality of the raw water during operation, and adjust the operating parameters in time. It is necessary to study and develop a new type of clarifier device and process to simplify the operation and management of the system as much as possible while meeting the condition of excellent effluent water quality. Summary of the invention

[0005] The object of the present invention is to provide a high-density air lift clarification device to solve the problems of short reaction time, unstable operation of sludge flocculent layer, complex operation and management in traditional clarification tanks.

[0006] The high-density air stripping clarification device proposed by the present invention has a structure as follows: Figure 1As shown, it includes: a clarification tank body 23, a grid reaction system composed of a grid reaction rising column 2 and a grid reaction descending column 3, a cyclone reaction system composed of a cyclone reaction zone 5 and a cyclone reaction zone 6, a pipeline mixer 1, a sludge collection tank 14, an enhanced contact flocculation zone 7, a sludge suspension zone 8, an inclined pipe 11, an air lift sludge discharge pipe 10, a sludge return pump 21, and related connecting pipelines and control valves; wherein:

[0007] The clarification tank body 23 is in the shape of a cylinder; the cyclone reaction system is arranged in the middle part of the clarification tank body 23; the cyclone reaction zone 5 and the cyclone reaction zone 6 are both in the shape of a cylinder, and the cyclone reaction zone 5 is located in the middle of the cyclone reaction zone 6, and the lower part of the cyclone reaction zone 6 is connected to the trumpet-shaped water distribution baffle 20; the cyclone reaction zone 5 and the cyclone reaction zone 6 are respectively provided with a cyclone plate 19 inside, and the cyclone plate 19 is composed of a number of spiral blades uniformly arranged around the rotating axis, and the number of spiral blades is generally 2 to 7 layers, which are arranged parallel from top to bottom and at equal intervals, and the distance between two adjacent cyclone plates 19 is 500 to 1500 mm. The main function of the cyclone plate 19 is to form a cyclone to strengthen the unidirectional flocculation effect of the alum flocs.

[0008] The water distribution baffle 20 is arranged at the lower opening of the cyclone reaction zone 6, and the horizontal angle of the water distribution baffle 20 is 45-60 degrees. The water distribution baffle 20 is a trumpet-shaped extension of the cyclone reaction zone 6, and its main function is to slow down the outlet flow velocity of the cyclone reaction zone 6.

[0009] A sludge suspension zone 8 is formed between the barrel wall of the clarifier tank body 23 and the outer side of the cyclone reaction system; an enhanced contact flocculation zone 7 is formed between the lower port of the cyclone reaction system and the bottom of the clarifier tank body 23;

[0010] A water inlet pipe 4 is provided at the lower middle of the clarification tank body 23, the upper end of which is connected to the lower end of the cyclone reaction zone 5, and a flocculant B adding interface is provided on the water inlet pipe 4 for adding flocculant B; the other end of the water inlet pipe 4 is connected to the lower end of the descending column 3;

[0011] The layout in the clarifier 23 is, from bottom to top, the reinforced contact flocculation zone 7, the sludge suspension zone 8, the inclined tube (inclined plate) 11, the clear water zone 9 and the water collection tank 12; the inclined tube (inclined plate) 11 is a conventional design in the field of water treatment, located above the sludge suspension zone, and its main function is to ensure that the water flow is in a stable laminar state, to prevent the particles from being disturbed by the flocculation during the sedimentation process, and to provide a larger wetted perimeter and a small hydraulic radius, thereby improving the sedimentation efficiency and the effluent water quality. Generally, the diameter of the inclined tube is selected to be DN32 to DN60 (DN is the nominal diameter of the pipe, which refers to the average value of the outer diameter and the inner diameter, also known as the average inner diameter, in mm), and the inclination angle is 55 degrees to 65 degrees (preferably 60 degrees). The water collection tank 12 is a conventional design in the field of water treatment, located about 0.8m to 1.2m above the inclined tube (inclined plate) 11, and its function is to uniformly collect the effluent of the clarifier and discharge it from the clarifier, and a perforated pipe or triangular weir structure can be used.

[0012] The grid reaction system is located outside the clarification tank body 23, wherein the grid reaction rising column 2 and the grid reaction descending column 3 are arranged in parallel, and the upper ends are connected; the rising column 2 and the descending column 3 are respectively provided with multiple mesh plates 22 arranged in sequence from top to bottom, which are used to generate a grid flocculation reaction when the raw water after adding the flocculant passes through, and the bottom of the rising column 2 is connected to the raw water inlet; the pipeline mixer 1 is arranged on the inlet pipeline, and the pipeline mixer 1 is provided with a flocculant A adding interface for adding flocculant A; the pipeline mixer 1 mixes the incoming raw water and flocculant A; a control valve is provided at the lower end of the inlet pipeline at the bottom of the rising column 2;

[0013] The mesh plates 22 generally have 2 to 7 layers, which are arranged in parallel and at equal intervals from top to bottom, and the mesh openings gradually increase along the water flow direction. Increase to

[0014] The sludge collection tank 14 is located outside the clarification tank body 23; it is divided into two parts, the lower part is the sludge sedimentation area 16, and the upper part is provided with a supernatant collection tank 15; its function is to evenly collect the effluent from the sludge collection tank 14 and discharge it into the clarification tank. A perforated pipe or triangular weir structure can be adopted. Generally, it is located 0.1 to 0.3 m below the upper edge of the sludge collection tank 14.

[0015] A sludge return pipe 18 is provided between the bottom of the sludge collection tank 14 and the water inlet pipe 4 at the bottom of the cyclone reaction zone 5; a sludge return pump 21 is provided at the bottom of the sludge collection tank 14 to pump the concentrated sludge into the water inlet pipe 4 through the sludge return pipe 18 to form sludge reflux.

[0016] In the sludge suspension area 8 in the clarifier body 23, a plurality of (usually 4-16, evenly arranged, the specific number is determined according to the size of the pool) air lift mud discharge pipes 10 are arranged. The lower part of the air lift mud discharge pipe 10 enters the enhanced contact flocculation area 7, the lower end of the air lift mud discharge pipe 10 is located at the bottom of the enhanced contact flocculation area 7, and the upper end is connected to the connecting pipe 24; the middle and lower part of the air lift mud discharge pipe 10 is connected with an air pipe 26 at an acute angle, and the air volume in the air pipe 26 is adjusted by an air valve 27. When the air is When the air valve 27 is opened, compressed air enters the air lift mud discharge pipe 10 through the air pipe 26, and the gas generates a large number of tiny bubbles in the air lift mud discharge pipe 10, which go up through the air lift mud discharge pipe 10 and enter the connecting pipe 24. The entry of air generates an upward water flow in the air lift mud discharge pipe 10, and sucks the sludge in the enhanced contact flocculation zone 7 at the lower end of the air lift mud discharge pipe 10. The air carries the water and sludge into the connecting pipe 24, and then flows into the sludge collection tank 14 for concentration.

[0017] In the present invention, the specific structure of the swirl plate in the swirl reaction zone is mainly composed of swirl blades, and its main function is to generate a swirl flow field in the cylindrical cavity to enhance the probability of flocculation reaction. Specifically, it can be designed into the following two structural modes: the swirl plate body is circular, and its structure is as follows: Figure 3 As shown, this structure can be used in the cyclone reaction zone 5; the cyclone plate body is annular, and its structure is as shown Figure 4 As shown, this structure is mainly used in the cyclone reaction zone 6.

[0018] In the present invention, the lower ends of the reaction rising column 2, the reaction descending column 3 and the sludge collecting tank 14 are designed to be funnel-shaped, and the lower opening of the funnel is connected to relevant pipelines.

[0019] In the present invention, the lower part of the clarification tank 23 is designed to be two cones (generally, the cone angle is 45° to 60° to facilitate sludge sedimentation), mainly for storing sludge.

[0020] In the present invention, drain valves 13 are respectively provided on the pipelines of the two conical parts of the rising column 2, the descending column 3, and the lower part of the clarifier body 23; a sludge return control valve 25 is provided on the sludge return pipe 18, which is in a normally open state during normal operation and is mainly used to prevent water from flowing back in the clarifier when the water pump 21 is overhauled. A control valve 17 is provided on the lower pipe of the sludge collection tank 14, which is mainly used for emptying the sludge collection tank.

[0021] In the present invention, the pipeline mixer 1 is a conventional general equipment in water supply.

[0022] In the present invention, the inclined tube (inclined plate) 11 is a common device in water treatment.

[0023] In the present invention, the water collecting tank 12 disposed on the upper part of the clarification tank 23 and the water collecting tank 15 disposed on the upper part of the sludge collecting tank 14 mainly collect the effluent evenly.

[0024] In the present invention, the height and size of the grid reaction rising column 2, the grid reaction descending column 3, the cyclone reaction zone 5 and the cyclone reaction zone 6, the sludge collection tank 14 and the clarification tank body 23 are determined according to the water volume.

[0025] Based on the above-mentioned high-density air stripping clarification device, the present invention also provides a high-density air stripping clarification method, the specific steps are:

[0026] After the raw water is added with coagulant A and mixed quickly through pipeline mixer 1, it enters the grid reaction column for flocculation reaction. The grid reaction column is located on one side of the clarification tank and is divided into two sections: grid reaction rising column 2 and grid reaction descending column 3. A mesh plate 22 is provided in the grid reaction column. After the raw water flows through the mesh plate, the potential energy is converted into kinetic energy to generate vortex, thereby generating flocculation reaction. Generally, there are 2 to 7 layers, which are arranged in parallel from top to bottom and at equal intervals. The mesh size gradually increases along the water flow direction. Increase to The flow rate gradually decreases; the water flow basically completes the initial flocculation reaction after passing through the grid reaction, and the colloids and suspended matter in the water are flocculated to form initial de-disordered alum flocculent particles.

[0027] Before the water flows through the water inlet pipe 4 and enters the cyclone reaction zone 5, flocculant B is added. After the water flows into the cyclone reaction zone 5 and the cyclone reaction zone 6, the flocculant B is fully mixed with the raw water under the action of the cyclone plate 19. The cyclone generated by the cyclone plate 19 increases the collision probability between the destabilized fine particles in the raw water, so that the initial de-turbulent alum flocs of small particles are flocculated into large particles and dense alum flocs, which is conducive to sedimentation in the subsequent inclined tube. The cyclone reaction zones 5 and 6 are located in the middle of the clarification tank. The cyclone plates 19 are arranged in the cyclone reaction zones 5 and 6, parallel and equidistant from top to bottom. Generally, the cyclone plates are 2 to 7 layers, and the distance between the two cyclone plates is 500 to 1500 mm.

[0028] Under the action of the cyclone plate 19, the cyclone reaction extends all the way to the lower enhanced contact flocculation zone 7 of the cyclone reaction zone 6. The water flow stays in this area for a long time (generally more than 30 minutes), which effectively strengthens the same-direction flocculation reaction. After the water flow passes through the water distribution baffle 20, it rises to the mud suspension layer 8 area. The mud suspension layer 8 is around the outside of the cyclone reaction zone 6. The upper part of this area is the inclined tube (inclined plate) 11. Large particles of alum settle in the inclined tube (inclined plate) 11. When the water flow velocity just makes the resistance of the particles equal to their gravity in the water (in a state of dynamic equilibrium), the particles are in a suspended state. As the raw water continues to pass through, the mud particles in a dynamic equilibrium state gradually accumulate. When the concentration reaches a certain level (about thousands of milligrams / liter), a mud suspension layer 8 is formed. The raw water passing through the sludge suspension layer is equivalent to the crowded sedimentation of sludge in still water. The sludge has a loose structure and a large surface area. The coagulation process of the raw water on the surface of the sludge group (contact coagulation) is much stronger than in water (free coagulation), so the coagulation effect is also improved. An inclined pipe 11 is set above the sludge suspension layer 8, and a water collection tank 12 is set above the inclined pipe 11. After passing through the sludge suspension layer, the water flow is precipitated through the inclined pipe (inclined plate) 11, and then discharged from the clarification tank by the water collection tank 12 to enter the later stage process.

[0029] The sludge discharge of the high-density clarification tank consists of two parts: (1) the sludge is lifted by the air lift sludge discharge pipe 10 and then precipitated and concentrated in the sludge collection tank 14; (2) the sludge is directly discharged through the bottom sludge discharge pipe. The air lift sludge discharge pipes 10 are evenly arranged in the enhanced contact flocculation zone 7, and the number is 4 to 16. The specific number of sludge discharge pipes is determined according to the size of the tank area. One end of the air lift sludge discharge pipe 10 is located at the bottom of the enhanced contact flocculation zone 7, and the other end is connected to the connecting pipe 24. In the enhanced contact flocculation zone 7, large particles of sludge settle to the bottom and enter the sludge collection tank 14 through the air lift sludge discharge pipe 10. After being concentrated in the sludge collection tank 14, the concentrated sludge is pumped into the water inlet pipe 4 through the sludge return pipe 18 to form sludge reflux. The sludge reflux amount is 1% to 5% of the total inlet water volume. A supernatant water collection tank 15 is provided at the upper part of the sludge collection tank 14, and the water collection tank 15 is connected to the water collection tank 12, and the effluent of the clarifier is collected and sent to the subsequent filter tank. An emptying valve 13 is provided at the bottom of the clarifier body 23, and a sludge collection tank vent pipe 17 is provided in the sludge collection tank 14, which is used to discharge water and sludge in the device out of the device.

[0030] The amount of flocculant added in the above system is determined by the six-joint stirring flocculation test of raw water to determine the optimal amount of agent added. The residence time of the cyclone reaction zone 5 and 6 is 2.5-5min, and the GT value is 2000-4000 (G is the hydraulic gradient s -1 , T is the hydraulic retention time (s). The hydraulic retention time in the enhanced contact flocculation zone 7 and the sludge suspension zone 8 is greater than 30 minutes. The sludge return volume controlled by the return pump is 1%-5% of the total treated water volume, which is determined according to the raw water quality and other conditions.

[0031] The technical features and performance advantages of the present invention mainly include:

[0032] 1. The outside of the clarifier is grid flocculation, and the inside is cyclone reaction co-directional flocculation, which strengthens the co-directional flocculation reaction. In particular, the cyclone reaction extends to the enhanced contact flocculation zone 7 at the bottom of the inclined tube 11. The hydraulic retention time of the water flow in this area is relatively long, which effectively prolongs the flocculation reaction time. After passing through the high-concentration sludge suspension layer 8, it is conducive to the growth of small particles into dense large particles, which not only improves the sedimentation efficiency of particles in the system, but also improves the stability of the clarification reaction system.

[0033] 2. The high-density clarifier of the present invention is a clarifier that combines sludge suspension and sludge circulation. There are not only the enhanced contact flocculation zone 7 and the sludge suspension zone 8 inside the clarifier, but also part of the sludge is concentrated in the sludge collection tank through the air lift sludge discharge pipe 10, and then pumped back to the water inlet pipe 4 before the cyclone reaction zone through the sludge return pump 21, forming a sludge return. The water flows in the water inlet pipe 4, flows through the cyclone reaction zones 5 and 6, and passes through the enhanced contact flocculation zone 7 to the sludge suspension zone 8. There are sludge flocs with a high concentration, which enhances the probability and intensity of the flocculation collision reaction, and is conducive to the formation of large-particle dense alum flowers, which not only improves the sedimentation efficiency, but also enhances the adaptability of the clarifier to the raw water quality. When the turbidity of the raw water changes within 1500NTU, the turbidity of the effluent after purification by the high-density air lift clarifier can reach within 0.5-1.0NTU, and the surface load can reach 15-18m / h. While improving the effluent quality, it reduces investment and floor space. Compared with traditional processes, the floor space and investment are only about 50% to 70% of traditional processes.

[0034] 3. In the enhanced contact flocculation zone 7, large particles of sludge settle to the bottom and enter the sludge collection tank 14 through the air lift sludge discharge pipe 10, and are concentrated in the sludge collection tank 14. The upper part of the sludge collection tank 14 is provided with a supernatant water collection tank 15, which is connected to the water collection tank 12. The supernatant of the sludge collection tank is mixed with the effluent of the clarification tank and then merged into the subsequent filter tank. The self-consumption of water in this process is only 50% of that of the traditional technology, saving water resources. The sludge collection tank is set up, and the generated sludge residue is concentrated to the maximum extent. The concentration of the concentrated sludge can reach 5-15g / L; the present invention optimizes the sludge discharge system of the clarification tank, making the system more stable and simplifying the sludge discharge operation.

[0035] 4. The present invention optimizes both flocculation dosing and sludge discharge, which is beneficial to the long-term operation of the system. Two flocculation dosing points are set up to add flocculants and coagulants respectively. The sludge discharge in the high-density clarification tank adopts air lift to discharge sludge continuously, which effectively guarantees the stable operation of the clarification tank and avoids the situation where the sludge layer is too high in concentration and causes the sludge layer to expand and affect the water discharge of the system. The present invention simplifies and optimizes the dosing, reaction, sludge discharge and other processes of the entire clarification system, and the operation control is simple, which is convenient for the long-term stable operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a structural diagram of the high-density gas lift clarification device.

[0037] Figure 2 This is a plan view of a high-density air lift clarifier.

[0038] Figure 3 Schematic diagram of the circular swirl plate shape.

[0039] Figure 4 Schematic diagram of the shape of the annular swirl plate.

[0040] Numbers in the figure: 1 is a pipeline mixer, 2 is a grid reaction rising column, 3 is a grid reaction descending column, 4 is a water inlet pipe, 5 is a cyclone reaction zone, 6 is a cyclone reaction zone, 7 is an enhanced contact flocculation zone, 8 is a sludge suspension zone, 9 is a clean water zone, 10 is an air lift sludge discharge pipe, 11 is an inclined pipe, 12 is a water collecting tank, 13 is an emptying valve, 14 is a sludge collection tank, 15 is a supernatant water collecting tank, 16 is a sludge sedimentation zone, 17 is a sludge collection tank venting pipe, 18 is a sludge return pipe, 19 is a cyclone plate, 20 is a water distribution baffle, 21 is a sludge return pump, 22 is a mesh plate, 23 is a clarifier tank body, connecting pipe 24, 25 is a sludge return valve, 26 is an air pipe, and 27 is an air valve. DETAILED DESCRIPTION

[0041] Example 1 This process is used for the transformation of a water plant. The original process of the water plant is a water treatment process with a 250 t / h hydraulic circulation clarifier and a gravity valveless filter in series as the core. When the inlet turbidity is 0-60 NTU, the effluent is generally around 3-5 NTU. Through the transformation, the original clarifier is equipped with a grid flocculation device, a cyclone reaction zone, a water distribution baffle, an air lift mud discharge system, and an inclined pipe. The parameters used in the design are as follows: the total flocculation time is 30.1 minutes, the mesh is three specifications, and the mesh sizes used are 25×25mm, 35×35mm and 50×50mm respectively. The spacing of the cyclone plate is 800mm, with a total of 13 layers, and the GT value is 3450 in total. The hydraulic retention time in the enhanced contact flocculation zone 7 and the sludge suspension zone 8 is 45min, there are 8 air lift pipes, and the sludge return volume is 5%.

[0042] After the above improvements, when the inlet turbidity is between 0 and 60 NTU, the outlet turbidity is within 0.5 to 1 NTU, and the hourly water output of the hydraulic circulation clarifier increases from the original 250 tons / hour to 480 tons / hour, saving the original 5 to 7 meters of head loss at the clarifier nozzle, reducing energy consumption, and the self-consumption of water in the clarifier is 50% of that of the traditional process.

[0043] Example 2

[0044] A newly built water plant with a capacity of 30,000 tons / day adopts the high-density air lift clarifier process of the present invention for purification. After adding drugs and mixing in the pipeline mixer, the water enters the high-density air lift clarifier. Its main design parameters are as follows:

[0045] Flow rate in water inlet pipe: 0.9m / s

[0046] The grid reaction system consists of a grid reaction rising column and a grid reaction descending column, a mesh flow device: 14 layers, the spacing is 600mm, the water flow velocity in the mesh is 0.18m / s, and the rising velocity in the reaction chamber is 0.03m / s. The cyclone reaction zone is set in the high-density clarification tank with 12 layers of cyclone reaction plates, the spacing is 700mm, and the total GT value is 3250. The hydraulic retention time in the enhanced contact flocculation zone 7 and the sludge suspension zone 8 is greater than 40min, the total flocculation reaction time is 43min, a DN32 inclined pipe is used, the diameter of 16 air lift sludge pipes is DN80, and the sludge return pump ratio is 5%.

[0047] Flocculant PAC is added before the pipeline mixer 1, and flocculant PAM is added to the water inlet pipe 4. The dosage of PAC is 15 mg / L, and the dosage of PAM is 0.15 mg / L.

[0048] When the inlet turbidity is within 1200NTU, the outlet water is below 1.0NTU (generally 0.2-0.4NTU), the net area of ​​the water plant is 2.0 acres, the self-consumption of water is about 1%, and the operating cost is 0.15 yuan / ton of water (chemicals, electricity, etc.).

Claims

1. A high-density airlift clarification device, characterized in that: include: A clarifier body (23), a grid reaction system consisting of an ascending column (2) and a descending column (3), a cyclone reaction system consisting of a first cyclone reaction zone (5) and a second cyclone reaction zone (6), a pipeline mixer (1), a sludge collection tank (14), an inclined pipe (11), an air lift sludge discharge pipe (10), a sludge return pump (21), and related connecting pipelines and control valves; wherein: The clarification tank body (23) is in the shape of a cylinder; the cyclone reaction system is arranged in the middle part of the clarification tank body (23); wherein the first cyclone reaction zone (5) and the second cyclone reaction zone (6) are both in the shape of a cylinder, and the first cyclone reaction zone (5) is located in the middle of the second cyclone reaction zone (6), and the lower part of the second cyclone reaction zone (6) is connected to a trumpet-shaped water distribution baffle (20); the first cyclone reaction zone (5) and the second cyclone reaction zone (6) are respectively provided with cyclone plates (19) inside, and the cyclone plates (19) are composed of a plurality of spiral blades uniformly arranged around the rotation axis, and the number of spiral blades is generally 2 to 7 layers, which are arranged parallel from top to bottom and at equal intervals, and the distance between two adjacent cyclone plates (19) is 500 to 1500 mm; the cyclone plates (19) are used to form a cyclone to enhance the unidirectional flocculation effect of alum flocs; The water distribution baffle (20) is arranged at the lower opening of the second cyclone reaction zone (6), and the horizontal angle of the water distribution baffle (20) is 45 to 60 degrees; the water distribution baffle (20) is a trumpet-shaped extension of the second cyclone reaction zone (6) and is used to slow down the outlet flow rate of the second cyclone reaction zone (6); A sludge suspension zone (8) is formed between the barrel wall of the clarifier tank body (23) and the outer side of the cyclone reaction system; an enhanced contact flocculation zone (7) is formed between the lower port of the cyclone reaction system and the bottom of the clarifier tank body (23); A water inlet pipe (4) is provided at the lower middle of the clarifier body (23), the upper end of the water inlet pipe (4) is communicated with the lower end of the first cyclone reaction zone (5), and a flocculant B adding interface is provided on the water inlet pipe (4) for adding flocculant B; the other end of the water inlet pipe (4) is connected to the lower end of the descending column (3); The layout inside the clarifier body (23) is, from bottom to top, an enhanced contact flocculation zone (7), a sludge suspension zone (8), an inclined pipe (11), a clear water zone (9) and a water collecting tank (12); the inclined pipe (11) is located above the sludge suspension zone (8) and is used to ensure that the water flow is in a stable laminar state, to prevent particles from being disturbed by flocculation during the sedimentation process, and to provide a larger wetted perimeter and a smaller hydraulic radius, thereby improving the sedimentation efficiency and the effluent quality; the diameter of the inclined pipe is DN32 to DN60, and the inclination angle is 55 to 65 degrees; the water collecting tank (12) is located 0.8 m to 1.2 m above the inclined pipe (11) and is used to uniformly collect the effluent from the clarifier and discharge it from the clarifier; The grid reaction system is located outside the clarification tank body (23), wherein the rising column (2) and the descending column (3) are arranged in parallel and the upper ends are connected; the rising column (2) and the descending column (3) are respectively provided with a plurality of mesh plates (22) arranged in sequence from top to bottom, which are used to generate a grid flocculation reaction when the raw water after adding the flocculant passes through; the bottom of the rising column (2) is connected to the raw water inlet; the pipeline mixer (1) is arranged on the inlet pipeline, and the pipeline mixer (1) is provided with a flocculant A adding interface for adding flocculant A; the pipeline mixer (1) mixes the incoming raw water and flocculant A; a control valve is provided at the lower end of the inlet pipeline at the bottom of the rising column (2); The mesh plates (22) have 2 to 7 layers, are arranged in parallel and at equal intervals from top to bottom, and the mesh openings gradually increase in the direction of water flow. Increase to The sludge collection tank (14) is located outside the main body (23) of the clarification tank; it is divided into two parts, the lower part is a sludge sedimentation area (16), and the upper part is provided with a supernatant water collection tank (15) for uniformly collecting the effluent of the sludge collection tank (14) and discharging it into the clarification tank. The sludge collection tank (14) is located 0.1 to 0.3 m below the upper edge of the sludge collection tank (14); A sludge return pipe (18) is provided between the bottom of the sludge collection tank (14) and the water inlet pipe (4) at the bottom of the first cyclone reaction zone (5); a sludge return pump (21) is provided at the bottom of the sludge collection tank (14) to pump the concentrated sludge into the water inlet pipe (4) through the sludge return pipe (18) to form sludge return; A plurality of evenly arranged air lift mud discharge pipes (10) are provided in the mud suspension area (8) in the clarifier body (23). The lower part of the air lift mud discharge pipe (10) enters the enhanced contact flocculation area (7), the lower end of the air lift mud discharge pipe (10) is located at the bottom of the enhanced contact flocculation area (7), and the upper end is connected to the connecting pipe (24); an air pipe (26) is connected at an acute angle to the middle and lower part of the air lift mud discharge pipe (10), and the air volume in the air pipe (26) is adjusted by an air valve (27). When the air valve (27) is opened, the air volume in the air lift mud discharge pipe (26) is adjusted by an air valve (27). When the compressed air passes through the air pipe (26) and enters the air lift mud discharge pipe (10), the compressed air goes up through the air lift mud discharge pipe (10) and enters the connecting pipe (24). As the air enters and rises, a large number of tiny bubbles are generated in the air lift mud discharge pipe (10); these bubbles rise in the liquid and suck the sludge in the enhanced contact flocculation zone (7) at the lower end of the air lift mud discharge pipe (10). The air carries the sludge to the connecting pipe (24), and then flows into the sludge collection tank (14) for concentration.

2. The high-density air stripping clarification device according to claim 1, characterized in that: The specific structure of the swirl plate in the swirl reaction zone is composed of swirl blades installed, which are used to generate a rotating flow field in the cylindrical cavity to enhance the probability of flocculation reaction; the specific structure is designed into the following two structural modes: the main body is circular, and this structure is used in the first swirl reaction zone (5); the main body is annular, and this structure is used in the swirl reaction zone (6).

3. The high-density air stripping clarification device according to claim 1, characterized in that: The lower ends of the reaction ascending column (2), the reaction descending column (3), and the sludge collecting tank (14) are designed to be funnel-shaped, and the lower openings of the funnels can be connected by relevant pipelines.

4. The high-density air stripping clarification device according to claim 1, characterized in that: The lower part of the clarifier body (23) is designed as two cones to facilitate the storage of sludge.

5. The high-density air stripping clarification device according to claim 1, characterized in that: The pipelines of the two conical parts of the ascending column (2), the descending column (3) and the lower part of the clarifier body (23) are respectively provided with drain valves (13); a sludge return control valve (25) is provided on the sludge return pipe (18), which is in a normally open state during normal operation and is used to prevent water backflow in the clarifier when the water pump (21) is repaired; and a control valve (17) is provided on the lower outlet pipeline of the sludge collection tank (14) for emptying the sludge collection tank.

6. The high-density air stripping clarification device according to claim 1, characterized in that: The height and size of the ascending column (2), the descending column (3), the first cyclone reaction zone (5), the second cyclone reaction zone (6), the sludge collection tank (14) and the clarification tank body (23) are determined according to the water volume.

7. A high-density gas stripping clarification method based on the device according to any one of claims 1 to 6, characterized in that: The specific steps are: (i) raw water is added with coagulant A and mixed quickly through a pipeline mixer (1), and then enters a grid reaction column for flocculation reaction; after the water flows through the grid reaction, the initial flocculation reaction is basically completed, and the colloids and suspended matter in the water are flocculated to form initial de-turbulent alum flocculent particles; (ii) before the water flows through the water inlet pipe (4) and enters the first cyclone reaction zone (5), a flocculant B is added. After the water flows into the first cyclone reaction zone (5) and the second cyclone reaction zone (6), the flocculant B is fully mixed with the raw water under the action of the cyclone plate (19). The cyclone generated by the cyclone plate (19) increases the collision probability between the destabilized fine particles in the raw water, so that the initial de-turbulent alum flocs of small particles are flocculated into large and dense alum flocs, which is conducive to sedimentation in the subsequent inclined tube; (iii) Under the action of the cyclone plate (19), the cyclone reaction extends to the lower part of the second cyclone reaction zone (6) in the enhanced contact flocculation zone (7), and the water flow stays in this zone for a period of time to enhance the same-direction flocculation reaction; when the water flow passes through the water distribution baffle (20) and rises to the sludge suspension layer (8) area, the sludge suspension layer (8) is around the outside of the second cyclone reaction zone (6), and the upper part of this area is an inclined tube (11), and large alum particles settle in the inclined tube (11). When the water flow velocity just makes the resistance of the particles equal to their gravity in the water, that is, in a state of dynamic equilibrium, the particles are in a suspended state; as the raw water continues to pass through, the Sludge particles in a dynamic equilibrium state gradually accumulate, and when the concentration reaches a certain level, a sludge suspension layer (8) is formed; raw water passing through the sludge suspension layer is equivalent to the crowded sedimentation of sludge in still water. Sludge has a loose structure and a large surface area. The coagulation process of raw water is much stronger when it is carried out on the surface of the sludge group in contact than when it is carried out in water. Therefore, the coagulation effect is improved; an inclined pipe (11) is arranged above the sludge suspension layer (8), and a water collecting tank (12) is arranged above the inclined pipe (11); after passing through the sludge suspension layer, the water flows through the inclined pipe (11) for sedimentation, and then is discharged from the water collecting tank (12) to the clarification tank and enters the subsequent process; (iv) sludge removal; sludge removal includes two parts: lifting through the air lift sludge discharge pipe (10) to the sludge collection tank (14) for sedimentation and concentration, and then removing; and directly discharging the sludge through the bottom sludge discharge pipe. Specifically, in the enhanced contact flocculation zone (7), large particles of sludge settle to the bottom and enter the sludge collection tank (14) through the air lift sludge discharge pipe (10). After being concentrated in the sludge collection tank (14), the concentrated sludge is pumped into the water inlet pipe through the sludge return pipe (18). (4) sludge reflux is formed in the sludge collection tank (14), and the sludge reflux amount is 1% to 5% of the total water volume of the inlet; a supernatant liquid collecting tank (15) is provided on the upper part of the sludge collection tank (14), and the supernatant liquid collecting tank (15) is connected to the collecting tank (12), and the effluent of the clarification tank is collected and sent to the subsequent filter tank; an emptying valve (13) is provided at the bottom of the clarification tank body (23), and the sludge collection tank (14) is provided with a sludge collection tank vent pipe (17) for discharging water and sludge in the device out of the device.

8. The high-density gas stripping clarification method according to claim 7, characterized in that: The amount of flocculant added is determined by the six-joint stirring flocculation test of raw water; the residence time in the first cyclone reaction zone (5) and the first cyclone reaction zone (6) is 2.5 to 5 minutes, the GT value is 2000-4000, and G is the hydraulic gradient s -1 , T is the hydraulic retention time s; the hydraulic retention time in the enhanced contact flocculation zone (7) and the sludge suspension zone (8) is greater than 30 minutes; the sludge return volume is controlled by the return pump to be 1%-5% of the total treated water volume.

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