CN112939211B - Device and method for enhancing aeration by utilizing hydraulic shearing and gas buoyancy - Google Patents
Device and method for enhancing aeration by utilizing hydraulic shearing and gas buoyancy Download PDFInfo
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- CN112939211B CN112939211B CN202110178481.5A CN202110178481A CN112939211B CN 112939211 B CN112939211 B CN 112939211B CN 202110178481 A CN202110178481 A CN 202110178481A CN 112939211 B CN112939211 B CN 112939211B
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/02—Aerobic processes
- C02F3/12—Activated sludge processes
- C02F3/1278—Provisions for mixing or aeration of the mixed liquor
- C02F3/1284—Mixing devices
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/24—Treatment of water, waste water, or sewage by flotation
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F7/00—Aeration of stretches of water
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2201/00—Apparatus for treatment of water, waste water or sewage
- C02F2201/002—Construction details of the apparatus
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2201/00—Apparatus for treatment of water, waste water or sewage
- C02F2201/002—Construction details of the apparatus
- C02F2201/005—Valves
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2203/00—Apparatus and plants for the biological treatment of water, waste water or sewage
- C02F2203/006—Apparatus and plants for the biological treatment of water, waste water or sewage details of construction, e.g. specially adapted seals, modules, connections
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/22—O2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
Abstract
The invention provides a device for strengthening aeration by utilizing hydraulic shearing and gas buoyancy, which comprises an air bubble generating unit and an air lift circulation unit, wherein the air bubble generating unit comprises an aeration core pipe, a blower and a booster pump; the aeration core pipe comprises a rotational flow cavity section with a cavity structure inside, and is provided with a liquid inlet, an air inlet and a bubble outlet; the airlift loop unit comprises an inner loop area and an outer loop area. Liquid enters the aeration core pipe from the tangential direction to make high-speed rotational flow movement, gas enters from the bottom and is sheared by the directional momentum of the fluid to generate a micro bubble group, the micro bubble group rises along with the mixed liquid under the action of the gas buoyancy in the inner circular flow area, the mixed liquid in the outer circular flow area falls under the action of the density difference, and part of the mixed liquid in the aeration tank is sucked by the inner circular flow area to form liquid-phase circulation enhanced aeration. The invention can increase the turbulence degree in the aeration tank, keep the sludge suspended and quickly oxygenate, uniformly distribute the dissolved oxygen in the aeration tank, and simultaneously avoid the problems of blockage, damage and the like of an aeration device.
Description
Technical Field
The invention belongs to the field of wastewater treatment, and particularly relates to a device and a method for enhancing aeration by utilizing hydraulic shearing and gas buoyancy.
Background
The biological method for treating waste water is a method for purifying water by decomposing degradable organic matters in the waste water by utilizing the metabolism of microorganisms, and is the most common water treatment method at present due to the advantages of large treatment capacity, small investment, economy, reliability and the like. Wherein, the treatment effect of the aerobic biological method which is widely applied is often limited by the high and low aeration performance in the aeration tank, and the main parameters of the aeration performance comprise the energy consumption of aeration equipment, the oxygenation capacity, the oxygen utilization rate, the sludge suspension degree and the like. In the existing aerobic biological sewage treatment process, aeration equipment has high energy consumption and low oxygenation capacity and oxygen utilization rate, and sludge precipitation can be caused when the aeration quantity is reduced, so that the sewage treatment rate is reduced.
The aeration type mainly includes surface aeration and blast aeration, wherein the surface aeration utilizes the centrifugal projection and lifting action of the impeller to fully mix air and water to achieve the purpose of oxygenation, but the surface aeration can only oxygenate the surface water body of the aeration tank, the bubble fragmentation is not obvious, the deep sewage can not be aerated, the effect of suspending sludge in the aeration tank can not be achieved, and the aeration efficiency is low. The blast aeration uses a blower capable of generating certain air quantity and pressure to force air or other gases into the water body through a conveying device and a gas diffusion plate or a diffusion pipe so as to oxygenate the water body.
The blowing aeration is mostly applied to microporous aeration pipes, and the two types are common at present:
one is the ordinary aeration pipe that the ceramic sintering formed, and the pipe wall can produce a lot of micropores in sintering process, can produce small bubble, and its shortcoming is: easy blockage, large pressure drop, easy damage of materials, great reduction of performance after damage, short service life and difficult replacement. It is second tubular diaphragm micropore aeration pipe, uses special material to make, has evenly distributed's punchhole on the diaphragm, during the aeration, receives the atmospheric pressure effect, and the punchhole opens, reaches the purpose of aeration diffusion, and when closing, the diaphragm itself is closed punchhole under the elastic action to sewage can not flow backwards and block up the punchhole, and its shortcoming is: the aeration oxygenation performance is influenced by the size of the opening of the membrane, the diameter of the opening is too large, and the aeration performance is low; the open pore is too small, the resistance is increased, and the consumption is increased; and the membrane is easy to age, fall off and tear, so that the oxygenation capacity is reduced. The maintenance frequency of the two aeration pipes is high, the maintenance workload is large, and the aeration tank needs to be emptied.
Therefore, there is a need to develop a new aeration apparatus and method to solve the above technical problems.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a device and a method for strengthening aeration by utilizing hydraulic shearing and gas buoyancy, which aim to solve the problems and technical defects that an aeration system in the prior art is easy to block and damage, large in pressure drop, low in oxygenation efficiency, uneven in aeration, poor in mixing effect and the like.
In order to achieve the purpose, the invention adopts the following technical scheme:
an apparatus for enhancing aeration using hydraulic shear and gas buoyancy for use in an aeration tank for biologically treating wastewater, said apparatus comprising an air bubble generating unit and an air-lift circulation unit, wherein:
the bubble generation unit comprises an aeration core pipe arranged at the bottom of the aeration tank, and an air blower and a booster pump which are arranged outside the aeration tank and connected with the aeration core pipe through pipelines; the aeration core pipe comprises a cylindrical rotational flow cavity section, the interior of the rotational flow cavity section is of a cavity structure, the side wall of the rotational flow cavity section is provided with a liquid inlet, the direction of the liquid inlet is tangential to the side wall of the rotational flow cavity section, the bottom of the rotational flow cavity section is provided with an air inlet, and the top of the rotational flow cavity section is provided with a bubble outlet; the outlet of the blower is connected with the air inlet of the aeration core pipe through a pipeline; the outlet of the booster pump is connected with the liquid inlet of the aeration core pipe through a pipeline;
the air-lift circulation unit is arranged above an aeration core pipe of the air bubble generation unit in the aeration tank and comprises a circulation inner cylinder and a circulation outer cylinder which are of a double-cylinder nested structure, an inner circulation area is arranged in the circulation inner cylinder, and an outer circulation area is arranged between the circulation inner cylinder and the circulation outer cylinder; the bottom of the circulation inner cylinder is provided with a bottom bracket which is fixed at the bottom of the aeration tank; the bottom of the circulation outer cylinder is fixedly connected with the bottom of the circulation inner cylinder through an outer cylinder bracket.
The invention is further provided that a gas regulating valve is arranged between the blower and the air inlet and is used for controlling the air inlet flow of the air entering the aeration core pipe; and a liquid regulating valve is arranged between the booster pump and the liquid inlet and is used for controlling the liquid flow entering the aeration core pipe.
The invention is further arranged that the structural sizes of the aeration core pipes are different according to different water depths of the aeration tank, and specifically the structural sizes are as follows:
when the depth of water in the aeration tank is 2-4m, the diameter of the liquid inlet is 2-4mm, the diameter of the air inlet is 2-3mm, and the diameter of the bubble outlet is 10-20 mm;
when the depth of water in the aeration tank is 4-6m, the diameter of the liquid inlet is 4-6mm, the diameter of the air inlet is 4-5mm, and the diameter of the bubble outlet is 20-30 mm;
when the depth of water in the aeration tank is 6-8m, the diameter of the liquid inlet is 8-10mm, the diameter of the air inlet is 8-10mm, and the diameter of the bubble outlet is 30-50 mm.
The invention is further arranged that the liquid inlet is arranged at 2/3-4/5 of the height of the cyclone cavity section.
The bottom of the circular inner cylinder is 5-10cm higher than the bubble outlet of the aeration core pipe and is used for reserving a pipeline installation space and a channel for forming local circular flow; in order to ensure that the mixed liquid in the outer circulation area is discharged into the aeration tank, the bottom of the circulation outer cylinder is 30-50cm higher than the bottom of the circulation inner cylinder.
The invention is further arranged that the height of the circulation inner cylinder is different according to different water depths of the aeration tank, and specifically comprises the following steps:
when the depth of the aeration tank is 2-4m, the height of the circulation inner cylinder is 1-3 m;
when the depth of water in the aeration tank is 4-6m, the height of the circulation inner cylinder is 3-5 m;
when the water depth of the aeration tank is 6-8m, the height of the circulation inner cylinder is 5-7 m.
The invention is further configured that, in order to ensure high turbulence degree in the air-lift circulation unit, the top of the circulation outer cylinder is 15-30cm higher than the water surface.
The invention is further provided that the diameter of the circulation inner cylinder is 25-100cm, and the diameter of the circulation outer cylinder is 1.8-2.5 times of the diameter of the circulation inner cylinder.
The aeration tank is further provided with a plurality of aeration strengthening devices, and the gap width of the adjacent air-lift circulation units is 1-2 m.
The invention also provides a method for strengthening aeration by using the device, which comprises the following steps:
(1) sewage is pressurized by a booster pump, tangentially enters the aeration core pipe, and performs high-speed rotational flow motion along the inner wall of the rotational flow cavity section; air is pressurized by a blower, enters the cyclone cavity section of the aeration core pipe, and is sheared by the directional momentum of the high-speed moving cyclone liquid to generate a micro-bubble group;
(2) the micro bubble groups enter the inner circulation area of the air-lift circulation unit along with the mixed liquid of the sewage, the mixed liquid in the inner circulation area is increased in turbulence under the constraint of the circulation inner cylinder, the surface updating rate of the bubbles is accelerated, the effective contact probability of pollutants, microorganisms and dissolved oxygen in the sewage is increased, and the degradation rate of the pollutants is improved;
(3) the mixed liquid in the inner circulation area moves upwards under the action of gas buoyancy, and overflows to the outer circulation area when rising to the top of the circulation inner cylinder; the bubble content of the outer circulation area is low, the buoyancy is low, the relative density is high, and the mixed liquid moves downwards under the action of the density difference and flows into the aeration tank;
(4) because the density in the inner circular flow area is small, the mixed liquid in the part of the aeration tank is sucked into the circular flow inner cylinder from the bottom under the action of the density difference and rises in the inner circular flow area along with the bubble group to form a local circular flow surrounding the air-lift circular flow unit.
The invention is further set that the working pressure of the booster pump is 0.1-0.4Mpa, and the working pressure of the blower is 0.02-0.1 Mpa.
The invention has the beneficial effects that:
(1) by utilizing the hydraulic directional momentum shearing principle, high-speed swirling state fluid is generated in the swirling cavity section of the bubble generation unit, air is filled in the bottom of the swirling cavity section, the fluid is sheared at high speed to generate a micro bubble group, the pore passage in the bubble generation unit is large, the structure is compact and high in strength, the problems of blockage, damage, falling and the like of the traditional microporous aeration pipe cannot occur, the service life is long, and the maintenance cost is low.
(2) The air-lift circulation unit is arranged on the upper portion of the bubble generation unit to form local liquid phase circulation, the turbulence degree of the aeration tank is increased, the oxygen transfer rate is accelerated, the gas-liquid-solid mixing effect is improved, the effective contact probability of microorganisms, dissolved oxygen and pollutants is increased, the pollutant removal rate is accelerated, in addition, the condition that the dissolved oxygen concentration in the aeration tank is uneven along with the distribution of areas can be improved due to the arrangement of the circulation unit, the microorganisms are guaranteed to be in a suspension state, and the effective utilization rate of the microorganisms is improved.
(3) According to the concentration of the pollutants in the incoming sewage, the air inflow of the air blower and the liquid inlet amount of the booster pump are controlled by adjusting the gas regulating valve and the liquid regulating valve, and the concentration of dissolved oxygen in the aeration tank is controlled to be maintained under the optimal working condition. Different from the traditional aerator, the blast volume is reduced, the turbulence effect in the aeration tank can not be reduced, and the suspension state of the sludge is still kept.
Drawings
FIG. 1 is a schematic view of an apparatus for enhancing aeration according to the present invention;
FIG. 2 is a schematic structural view of an aeration core tube according to the present invention;
fig. 3 is a plan view of an aeration core tube according to the present invention;
FIG. 4 is a schematic diagram of a gas lift loop unit according to the present invention;
FIG. 5 is a top view of a gas lift circulation unit in accordance with the present invention;
FIG. 6 is a plan view showing the arrangement of an aeration enhancing apparatus according to example 2 of the present invention;
FIG. 7 is a schematic view showing the construction of an apparatus for enhancing aeration according to example 2 of the present invention;
fig. 8 is a plan view showing the arrangement of the aeration enhancing apparatus according to example 3 of the present invention.
Detailed Description
The dissolved oxygen content in the aeration tank for treating the wastewater by a biological method is generally controlled to be 2-6mg/L, the dissolved oxygen content is too low, the microbial activity is reduced, and the removal rate of pollutants is reduced; and the dissolved oxygen content is too high, which can cause oxygen poisoning of activated sludge and lose the capacity of treating pollutants in sewage, so the dissolved oxygen content in the aeration tank needs to be controlled within a certain range, and the dissolved oxygen content fluctuates along with the concentration difference of the pollutants in the inflow water. Conventional blast aeration can only control the dissolved oxygen concentration by reducing aeration amount or intermittent aeration, but this seriously affects the suspended state of sludge, and the turbulent effect is reduced, thereby reducing the effective contact probability of microorganisms, dissolved oxygen and pollutants.
The inventor utilizes the rotational flow shearing action of a liquid phase to shear the air blown by a blower with directional momentum, so that a micro-bubble group is generated, and the size of the air inflow is controlled by an external blower. The outlet bubble plume sheared by hydraulic force has higher turbulence degree, so the turbulence degree of the mixed liquid in the aeration tank cannot be influenced by the reduction of air input, and the mixing effect of gas, liquid and solid phases in the aeration tank cannot be influenced.
In addition, the micro-bubbles have obvious gain effect on aeration oxygenation in sewage treatment, and the water depth of the aeration tank is generally 3-7 meters in order to increase the retention time of the micro-bubbles in water. The rising speed of the micro-bubbles is slower than that of millimeter-sized bubbles, so that the retention time of the micro-bubbles can be fully increased, but the coanda effect exists in adjacent micro-bubble plumes, the original flowing direction of the bubbles can be changed, the bubbles can be unevenly distributed in the rising process, partial area aeration is excessive in the aeration tank with large area and large depth, partial area aeration is insufficient, the distribution of the concentration of dissolved oxygen is uneven, and the utilization rate of microorganisms is low.
The inventor arranges the air-lift circulation unit, so that the turbulence degree of an internal liquid phase of micro-fine bubbles is increased under the constraint of the air-lift circulation unit, the condition of uneven distribution of the bubbles is reduced, the effective contact probability of pollutants, microorganisms and dissolved oxygen is increased, and the degradation rate of the pollutants is improved. Meanwhile, under the action of density difference, the mixed liquid moves upwards inside the circular inner cylinder of the air-lift circular flow unit, and the mixed liquid moves downwards outside the circular inner cylinder to form local circular flow, so that the mixing of gas, liquid and solid phases is enhanced, the microorganisms are ensured to be in a suspended state, and the effective utilization rate of the microorganisms is improved.
The present invention will be described in further detail with reference to examples. It is to be understood that the following examples are for illustrative purposes only and are not to be construed as limiting the scope of the present invention, and that certain insubstantial modifications and adaptations of the invention may be made by those skilled in the art based on the teachings herein.
Example 1
Fig. 1 shows an apparatus for enhancing aeration by generating fine bubbles by using hydraulic shear and gas buoyancy according to the present invention, the apparatus for enhancing aeration comprises a bubble generating unit 1 and an air-lift circulation unit 2 installed above the bubble generating unit 1, the bubble generating unit 1 comprises an aeration core pipe 4 arranged at the bottom of an aeration tank 3, and a blower 5 and a booster pump 6 connected to the aeration core pipe 4 through a pipeline and disposed outside the aeration tank 3.
Wherein, the aeration core tube 4 is located at the center of the bottom of the gas lift circulation unit 2, as shown in fig. 2 and 3, the aeration core tube 4 comprises a cylindrical cyclone cavity section 41, the inside of the cyclone cavity section 41 is a cavity structure, the side wall of the cyclone cavity section 41 is provided with a liquid inlet 42, the direction of the liquid inlet 42 is tangential to the side wall of the cyclone cavity section 41, the bottom of the cyclone cavity section 41 is provided with an air inlet 43, and the top is provided with a bubble outlet 44, so that sewage enters the cavity structure of the cyclone cavity section 41 tangentially through the liquid inlet 42 to perform high-speed cyclone motion, air enters the cavity structure through the air inlet 43, and is sheared by the directional momentum of the sewage in a cyclone state to generate a micro-bubble group which is discharged from the bubble outlet 44; the air blower 5 is connected with the air inlet 43 of the aeration core pipe 4 through a pipeline; the booster pump 6 is connected with the liquid inlet 42 of the aeration core pipe 4 through a pipeline.
A part of the sewage treated by the aeration tank 3 horizontally flows into the aeration tank 3, and a part of the sewage is fed by the booster pump 6 and enters the aeration tank 3 through the aeration core pipe 4.
As shown in fig. 4 and 5, the air-lift circulation unit 2 includes a circulation inner cylinder 21 and a circulation outer cylinder 22 in a double-cylinder nested structure, an inner circulation area 23 is formed inside the circulation inner cylinder 21, and an outer circulation area 24 is formed between the circulation inner cylinder 21 and the circulation outer cylinder 22; the bottom of the circulation inner cylinder 21 is provided with a bottom bracket 25 for supporting the air-lift circulation unit 2; the bottom of the circulation outer cylinder 22 is higher than the bottom of the circulation inner cylinder 21 and is connected through an outer cylinder bracket 26, so as to fixedly support the circulation outer cylinder 22 outside the circulation inner cylinder 21.
Further, a gas regulating valve 7 is installed between the blower 5 and the air inlet 43, and is used for controlling the intake flow of air; and a liquid regulating valve 8 is arranged between the booster pump 6 and the liquid inlet 42 and is used for controlling the liquid flow entering the aeration core pipe 2.
Furthermore, the material of the aeration core pipe 4 is stainless steel.
Further, the liquid inlet 42 is disposed at 2/3-4/5 of the height of the swirl chamber section 41.
Further, the structural size of the aeration core pipe 4 is different according to the water depth of the aeration tank 3. When the water depth of the aeration tank 3 is 2-4m, the diameter of the liquid inlet 42 is 2-4mm, the diameter of the air inlet 43 is 2-3mm, and the diameter of the bubble outlet 44 is 10-20 mm; when the depth of water in the aeration tank 3 is 4-6m, the diameter of the liquid inlet 42 is 4-6mm, the diameter of the air inlet 43 is 4-5mm, and the diameter of the bubble outlet 44 is 20-30 mm; when the depth of the aeration tank 3 is 6-8m, the diameter of the liquid inlet 42 is 8-10mm, the diameter of the air inlet 43 is 8-10mm, and the diameter of the bubble outlet 44 is 30-50 mm.
Further, the aeration core pipe 4 is directly fixed in the aeration tank 3 through a pipeline for air intake and liquid intake, or is fixed with the bottom of the aeration tank 3.
Further, the bottom bracket 25 and the inner circulation cylinder 21 are welded, and the bottom bracket 25 is fixed at the bottom of the aeration tank 3 through a bolt connection.
Further, the distance from the bottom of the circulation inner cylinder 21 to the air bubble outlet 44 of the aeration core pipe 4 is 5-10cm, and the circulation inner cylinder is used for reserving a pipeline installation space and forming a local circulation channel; in order to ensure a high degree of turbulence in the air-lift circulation unit 2, the top of the circulation outer cylinder 22 is 15-30cm above the water surface; in order to ensure that the mixed liquid in the external circulation area 24 is discharged into the aeration tank 3, the bottom of the circulation outer cylinder 22 is 30-50cm higher than the bottom of the circulation inner cylinder 21.
Further, the height of the circulation inner cylinder 21 is different according to the water depth of the aeration tank 3. When the water depth of the aeration tank 3 is 2-4m, the height of the circulation inner cylinder 21 is 1-3 m; when the depth of the aeration tank 3 is 4-6m, the height of the circulation inner cylinder 21 is 3-5 m; when the depth of the aeration tank 3 is 6-8m, the height of the circulation inner cylinder 21 is 5-7 m.
Further, the diameter of the circulation inner cylinder 21 is 25-100cm, and the diameter of the circulation outer cylinder 22 is 1.8-2.5 times of the diameter of the circulation inner cylinder 21, so that gas, liquid and solid phases in the gas lift circulation unit 2 are uniformly mixed.
Further, a plurality of the aeration enhancing devices are included in the aeration tank 3, and the gap width of the adjacent air-lift circulation units 2 is 1-2m in order to ensure the suspension and high turbulence degree of microorganisms in the aeration tank 3.
A method for enhancing aeration using the apparatus, the method comprising the steps of:
(1) sewage is pressurized by a booster pump 6, tangentially enters a cyclone cavity section 41 of the aeration core pipe 4 under certain pressure, and performs high-speed cyclone motion along the inner wall of the cyclone cavity section 41; air is pressurized by the blower 5, enters the cyclone cavity section 41 from the bottom of the aeration core pipe 4 under certain pressure, and the cyclone liquid moving at high speed carries out directional momentum shearing on the air to generate a micro-bubble group;
(2) the micro bubble groups enter the inner circulation area 23 of the air-lift circulation unit 2 along with the mixed liquid of the sewage, under the constraint of the circulation inner cylinder 21, the turbulent motion of the mixed liquid of the inner circulation area 23 is increased, the surface updating rate of bubbles is accelerated, the effective contact probability of pollutants, microorganisms and dissolved oxygen in the sewage is increased, and the degradation rate of the pollutants is improved;
(3) the mixed liquid in the inner circulation area 23 moves upwards under the action of the buoyancy of the bubbles, and when the mixed liquid rises to the top of the circulation inner cylinder 21, the bubbles, sewage and microorganisms are sprayed out from the top of the inner circulation area 23 and overflow to the outer circulation area 24; the outer circulation area 24 has small bubble content, small buoyancy and large relative density, and the mixed liquid moves downwards under the action of density difference and flows into the aeration tank 3;
(4) due to the small density inside the inner circulation area 23, the mixed liquid in part of the aeration tank 3 is sucked into the circulation inner cylinder 21 from the bottom under the action of the density difference, and rises along with the bubble group in the inner circulation area 23 to form a local circulation around the air-lift circulation unit 2.
Further, in order to ensure the high-speed rotational flow state of the liquid in the rotational flow cavity section 41, the booster pump 6 needs to reach a certain working pressure. Meanwhile, in order to reduce energy consumption, the working pressure of the booster pump 6 is 0.1-0.4Mpa under the condition of ensuring the high-speed rotational flow state of the liquid in the rotational flow cavity section 41.
Further, because the rotational flow field in the rotational flow cavity section 41 exists, a constant negative pressure is generated in the rotational flow cavity section 41, the working pressure of the blower 5 is greatly reduced, and further, the energy consumption of the blower is reduced. In order to ensure the stable air input, the working pressure of the blower 5 is 0.02-0.1Mpa, and the apparent air speed at the air inlet 43 is 0.001-0.01 m/s.
Furthermore, the aeration core pipe 4 generates a large amount of micro-bubble groups, the diameters of the bubbles are 50-1000 μm, and the micro-bubble groups have extremely large specific surface area, oxygen mass transfer rate and oxygenation efficiency.
Furthermore, the arrangement of the air-lift circulation unit 2 reduces the horizontal flow velocity of the sewage in the aeration tank 3, the horizontal flow velocity of the sewage in the aeration tank is generally 0.3-0.5m/s, the sewage forms a shunt in the aeration tank 3, and part of the sewage moves towards the bottom of the air-lift circulation unit 2, so that the hydraulic retention time and the turbulent effect of the sewage in the aeration tank are increased.
The aeration strengthening device and the aeration strengthening method can stably generate a large amount of micron-sized bubbles, have higher oxygenation capacity, are different from the traditional microporous aerator in bubble generation units, have no microchannels, have high structural strength, cannot cause the problems of blockage and damage due to impurities in sewage, have long running period, ensure the high turbulence degree in the aeration tank, and strictly control the size of air inflow so as to ensure the reasonable dissolved oxygen concentration in the tank; in addition, the air-lift circulation unit enables local liquid phase circulation to be generated in the aeration tank, the problem of uneven distribution of a bubble aeration area can be solved, the hydraulic retention time is increased, the effective contact probability of microorganisms, pollutants and dissolved oxygen is increased, and the pollutant degradation rate is increased.
Example 2
The device described in embodiment 1 is adopted to generate micro-bubbles by utilizing hydraulic shearing and gas buoyancy to strengthen aeration, and a traditional blast aeration device is modified. As shown in FIGS. 6 and 7, the width of the aeration tank 3 is 10m, the water depth is 5-6m, and the water flow direction is from left to right. In consideration of modification cost, energy consumption and hydraulic retention time, the original aeration head 11 of the first half section of the aeration tank 3 is modified, and the original aeration head 11 is adopted in the second half section.
It is calculated that the aeration enhancement means composed of the air bubble generation unit 1 and the air-lift circulation unit 2 are arranged in 5 rows, 4 in each row, along the width direction of the aeration tank 3. The gap width of the adjacent air-lift circulation units 2 is 1.5-2m, and the distance between the outermost air-lift circulation unit 2 and the pool wall is 0.5-0.8 m. The diameter of the liquid inlet 42 of the aeration core pipe 4 of the air bubble generation unit 1 is 6mm, the diameter of the air inlet 43 is 4mm, and the diameter of the air bubble outlet 44 is 25 mm; the circulation inner cylinder 21 of the air-lift circulation unit 2 has a diameter of 50cm and a height of 4m, and the circulation outer cylinder 22 has a diameter of 80 cm.
The method of the embodiment 1 is adopted to strengthen aeration, a booster pump 6 pumps part of sewage to each aeration core pipe 4, an air blower 5 blows air into each aeration core pipe 4, and micro-fine bubble groups are generated in the aeration core pipes 4; the gas regulating valve 7 and the liquid regulating valve 8 respectively regulate the gas inlet and the liquid inlet quantity and maintain the concentration of dissolved oxygen in the aeration tank; the micro bubble group enters the air lift circulation unit 2 to form local circulation enhanced aeration.
In the embodiment, the plurality of bubble generation units 1 and the air-lift circulation unit 2 act together, so that the overall turbulence effect of the aeration tank at the first half section is increased, the oxygen transfer rate and the pollutant removal rate are increased, the Biochemical Oxygen Demand (BOD) of the sewage is reduced to be below 20mg/L after the sewage is treated by the aeration enhancing device after the first half section of the aeration tank is modified, the pollutant removal rate reaches the overall pollutant removal rate of the traditional aeration tank before modification, and under the condition that the size of the aeration tank is not modified, the bubble generation units 1 and the air-lift circulation unit 2 enhance the pollutant removal effect and ensure the quality of the effluent.
Example 3
The aeration tank 3 has the width of 10m, the length of 11m and the water depth of 5-6m, four partition walls 9 are sequentially arranged in the aeration tank 3 along the length direction, one end of each partition wall 9 is connected with the inner wall of one side of the aeration tank in the length direction, the other end of each partition wall 9 is spaced from the inner wall of the other side of the aeration tank in the length direction by 2m, and the partition walls 9 are arranged in a crossed mode to form a serpentine flow channel. The partition 9 divides the aeration tank 3 into five flow passages 10, the first four flow passages 10 have a width of 2m, and the fifth flow passage 10 has a width of 2.5 m.
The device for strengthening aeration, which consists of the bubble generation unit 1 and the air-lift circulation unit 2, is arranged in the middle of the flow channel 10, and the distance between two adjacent air-lift circulation units 2 is 2 m. The diameter of the liquid inlet 42 of the aeration core pipe 4 of the air bubble generation unit 1 is 6mm, the diameter of the air inlet 43 is 4mm, and the diameter of the air bubble outlet 44 is 25 mm; the circulation inner cylinder 21 of the air-lift circulation unit 2 has a diameter of 50cm and a height of 4m, and the circulation outer cylinder 22 has a diameter of 80 cm. And an area of the fifth flow channel 10, which is 5m away from the water outlet, is not provided with a device for strengthening aeration, so that the sewage can conveniently flow into the next-stage sewage treatment tank.
The method of the embodiment 1 is adopted to strengthen aeration, a booster pump pumps part of sewage to each aeration core pipe, and an air blower blows air into each aeration core pipe to generate a micro-bubble group in the aeration core pipe; the micro bubble group enters the air lift circulation unit to form local circulation enhanced aeration. Sewage in the aeration tank enters from the first flow channel, passes through each aeration strengthening device arranged in the flow channel, sequentially flows through the second flow channel, the third flow channel and the fourth flow channel, passes through each flow channel of the aeration tank, and then flows out from the fifth flow channel.
The arrangement of the partition wall enables the sewage to change from horizontal flow to serpentine flow, the hydraulic retention time of the sewage in the aeration tank is increased, the arrangement of the width of the flow channel meets the requirement of a device for strengthening aeration on generating local circulation, the turbulence degree in the whole flow channel is large, the mixing effect is good, the concentration of dissolved oxygen in the flow channel is uniform, the activity of microorganisms is high, the effective contact probability of the microorganisms, the dissolved oxygen and pollutants is large, and the removal rate of the pollutants is accelerated; and the setting of partition wall, under the less condition of aeration tank area, its water conservancy dwell time of assurance that can be fine effectively reduces aeration tank's area and maintenance cost.
Claims (11)
1. An apparatus for enhancing aeration using hydraulic shear and gas buoyancy for use in an aeration tank for biologically treating wastewater, wherein the apparatus for enhancing aeration comprises a bubble generation unit and an air-lift circulation unit, wherein:
the bubble generation unit comprises an aeration core pipe arranged at the bottom of the aeration tank, and an air blower and a booster pump which are arranged outside the aeration tank and connected with the aeration core pipe through pipelines; the aeration core pipe comprises a cylindrical rotational flow cavity section, the interior of the rotational flow cavity section is of a cavity structure, the side wall of the rotational flow cavity section is provided with a liquid inlet, the direction of the liquid inlet is tangent to the side wall of the rotational flow cavity section, the bottom of the rotational flow cavity section is provided with an air inlet, and the top of the rotational flow cavity section is provided with a bubble outlet; the outlet of the blower is connected with the air inlet of the aeration core pipe through a pipeline, the working pressure of the blower is 0.02-0.1Mpa, and the apparent air speed at the air inlet is 0.001-0.01 m/s; the outlet of the booster pump is connected with the liquid inlet of the aeration core pipe through a pipeline;
the air-lift circulation unit is arranged above an aeration core pipe of the air bubble generation unit in the aeration tank and comprises a circulation inner cylinder and a circulation outer cylinder which are of a double-cylinder nested structure, an inner circulation area is arranged in the circulation inner cylinder, and an outer circulation area is arranged between the circulation inner cylinder and the circulation outer cylinder; the bottom of the circulation inner cylinder is provided with a bottom bracket which is fixed at the bottom of the aeration tank; the bottom of the circulation outer cylinder is fixedly connected with the bottom of the circulation inner cylinder through an outer cylinder support.
2. The apparatus for enhancing aeration according to claim 1, wherein a gas regulating valve is installed between the blower and the air inlet for controlling the inflow of air into the aeration core tube; and a liquid regulating valve is arranged between the booster pump and the liquid inlet and is used for controlling the liquid flow entering the aeration core pipe.
3. The aeration enhancement device according to claim 1, wherein the aeration core pipes have different structural dimensions according to the water depth of the aeration tank, and specifically comprise:
when the depth of water in the aeration tank is 2-4m, the diameter of the liquid inlet is 2-4mm, the diameter of the air inlet is 2-3mm, and the diameter of the bubble outlet is 10-20 mm;
when the depth of water in the aeration tank is 4-6m, the diameter of the liquid inlet is 4-6mm, the diameter of the air inlet is 4-5mm, and the diameter of the bubble outlet is 20-30 mm;
when the depth of water in the aeration tank is 6-8m, the diameter of the liquid inlet is 8-10mm, the diameter of the air inlet is 8-10mm, and the diameter of the bubble outlet is 30-50 mm.
4. An enhanced aeration apparatus according to claim 1, wherein said liquid inlet is provided at 2/3 to 4/5 of the height of said cyclone chamber section.
5. The apparatus for enhancing aeration according to claim 1, wherein the bottom of the circulation inner cylinder is 5-10cm higher than the bubble outlet of the aeration core pipe for leaving a pipe installation space and a channel for forming a partial circulation; in order to ensure that the mixed liquid in the outer circulation area is discharged into the aeration tank, the bottom of the circulation outer cylinder is 30-50cm higher than the bottom of the circulation inner cylinder.
6. The apparatus for enhancing aeration according to claim 1, wherein the height of the circulation inner cylinder is different according to the water depth of the aeration tank, and specifically comprises:
when the depth of the aeration tank is 2-4m, the height of the circulation inner cylinder is 1-3 m;
when the depth of water in the aeration tank is 4-6m, the height of the circulation inner cylinder is 3-5 m;
when the water depth of the aeration tank is 6-8m, the height of the circulation inner cylinder is 5-7 m.
7. An apparatus for enhancing aeration according to claim 1 wherein the top of said circulation outer cylinder is 15-30cm above the water surface to ensure a high degree of turbulence in said air-lift circulation unit.
8. The apparatus for enhancing aeration according to claim 1, wherein the diameter of the circulation inner cylinder is 25-100cm, and the diameter of the circulation outer cylinder is 1.8-2.5 times the diameter of the circulation inner cylinder.
9. The aeration enhancement device according to claim 1, wherein the aeration enhancement device is provided with a plurality of aeration enhancement devices, the aeration enhancement devices are arranged in 5 rows along the width direction of the aeration tank, each row is provided with 4 aeration enhancement devices, and the gap width of the adjacent air-lift circulation units is 1-2 m.
10. A method of enhancing aeration using hydrodynamic shear and gas buoyancy, using the apparatus of any one of claims 1-9, characterized in that the method comprises the steps of:
(1) the sewage is pressurized by a booster pump, tangentially enters the aeration core pipe and performs high-speed rotational flow motion along the inner wall of the rotational flow cavity section; air is pressurized by a blower, enters the cyclone cavity section of the aeration core pipe, and is sheared by the directional momentum of the cyclone liquid moving at high speed to generate a micro-bubble group;
(2) the micro bubble groups enter the inner circulation area of the air-lift circulation unit along with the mixed liquid of the sewage, the mixed liquid in the inner circulation area is increased in turbulence under the constraint of the circulation inner cylinder, the surface updating rate of the bubbles is accelerated, the effective contact probability of pollutants, microorganisms and dissolved oxygen in the sewage is increased, and the degradation rate of the pollutants is improved;
(3) the mixed liquid in the inner circulation area moves upwards under the action of gas buoyancy, and overflows to the outer circulation area when rising to the top of the circulation inner cylinder; the bubble content of the outer circulation area is less, the buoyancy is small, the relative density is large, and the mixed liquid moves downwards under the action of the density difference and flows into the aeration tank;
(4) due to the fact that the density in the inner circular flow area is small, the mixed liquid in the part of the aeration tank is sucked into the circular flow inner cylinder from the bottom under the effect of the density difference and rises in the inner circular flow area along with the bubble groups, and partial circular flow surrounding the air-lift circular flow unit is formed.
11. The method for enhancing aeration of claim 10, wherein the operation pressure of the booster pump is 0.1-0.4Mpa, and the operation pressure of the blower is 0.02-0.1 Mpa.
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| US7261283B1 (en) * | 1999-05-15 | 2007-08-28 | Hirofumi Ohnari | Swing type fine air bubble generating device |
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| US7261283B1 (en) * | 1999-05-15 | 2007-08-28 | Hirofumi Ohnari | Swing type fine air bubble generating device |
| CN201276470Y (en) * | 2008-10-31 | 2009-07-22 | 新疆联合环保工程有限公司 | Series side-installed jet biological fluidized bed for processing high concentration wastewater |
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