WO2004043866A1 - Apparatus for the biological treatment of wastewater - Google Patents
Apparatus for the biological treatment of wastewater Download PDFInfo
- Publication number
- WO2004043866A1 WO2004043866A1 PCT/KR2003/002424 KR0302424W WO2004043866A1 WO 2004043866 A1 WO2004043866 A1 WO 2004043866A1 KR 0302424 W KR0302424 W KR 0302424W WO 2004043866 A1 WO2004043866 A1 WO 2004043866A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- aeration tank
- wastewater
- bubble collection
- oxygen
- tank structure
- Prior art date
Links
- 239000002351 wastewater Substances 0.000 title claims abstract description 90
- 238000011282 treatment Methods 0.000 title abstract description 28
- 238000005273 aeration Methods 0.000 claims abstract description 133
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 69
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 69
- 239000001301 oxygen Substances 0.000 claims abstract description 69
- 244000005700 microbiome Species 0.000 claims abstract description 28
- 239000000203 mixture Substances 0.000 claims abstract description 24
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims abstract description 22
- 238000013019 agitation Methods 0.000 claims abstract description 21
- 238000000034 method Methods 0.000 claims abstract description 18
- 235000015097 nutrients Nutrition 0.000 claims abstract description 14
- 230000008569 process Effects 0.000 claims abstract description 14
- 239000000126 substance Substances 0.000 claims abstract description 14
- 239000010802 sludge Substances 0.000 claims abstract description 8
- 238000002347 injection Methods 0.000 claims description 17
- 239000007924 injection Substances 0.000 claims description 17
- 230000004888 barrier function Effects 0.000 claims description 7
- 230000000903 blocking effect Effects 0.000 claims description 4
- 230000003014 reinforcing effect Effects 0.000 claims 2
- 238000009434 installation Methods 0.000 abstract description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 230000000630 rising effect Effects 0.000 description 5
- 230000029058 respiratory gaseous exchange Effects 0.000 description 4
- 239000007789 gas Substances 0.000 description 3
- 230000005484 gravity Effects 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 238000007792 addition Methods 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000003134 recirculating effect Effects 0.000 description 2
- 238000010008 shearing Methods 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 239000012080 ambient air Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 238000011221 initial treatment Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000013049 sediment Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
Classifications
-
- 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
-
- 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
- C02F3/26—Activated sludge processes using pure oxygen or oxygen-rich gas
-
- 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
Definitions
- the present invention relates to an apparatus for the biological treatment of wastewater, and more particularly to an aeration tank using a pure oxygen activated sludge process, in which pure oxygen is injected into the aeration tank in order to activate microorganisms, and organic substances and nutrients in the wastewater are decomposed by the activated microorganisms.
- a typical aeration tank In a conventional activated sludge method, which is a type of biological treatment processes of sewage or organic wastewater, a typical aeration tank has a water depth of approximately 4m to 5m and a low oxygen transfer rate of 5% to 10%, and requires a large installation site, thus being ineffective in terms of installation cost and operation cost from an economic standpoint and in terms of treatment efficiency and volume of the aeration tank structure from a technical standpoint.
- various attempts have been made including a contact media process in which contact media is provided in the aeration tank. This improved the treatment efficiency to some degree but failed to bring it to a satisfactory level. And separation of the microorganisms from the media after an extended use made it difficult to maintain stable treatment. Oxygen transfer rate and utilization efficiency also need to be further improved.
- the present invention has been made in view of the above problems, and it is an object of the present invention to provide an aeration tank for biological treatment of wastewater, in which transfer rate and utilization efficiency of the oxygen in the wastewater introduced into the aeration tank are improved, thereby efficiently treating organic substances and nutrients in the wastewater.
- the volume of the aeration tank structure can be minimized, remarkably reducing installation cost, operation cost and the installation site requirement.
- an aeration tank using a pure oxygen activated sludge process in which pure oxygen is injected into the aeration tank so as to activate microorganisms, and organic substances and nutrients of the wastewater are decomposed by the activated microorganisms, comprising: an aeration tank structure; and a bubble collection and recirculation facility including: a bubble collection device installed in the aeration tank structure for guiding and collecting oxygen bubbles which are undissolved in the wastewater and travel upwards in the aeration tank structure; and an agitation device installed below the bubble collection device in the aeration tank structure for agitating and mixing the mixture of the wastewater, the microorganisms and the oxygen bubbles while moving them down to the lower portion of the aeration tank along a designated direction.
- the bubble collection device may include: a bubble collection hood installed in the aeration tank structure to collect the oxygen bubbles which travel upward in the aeration tank undissolved and unused and a hunch formed on the inner walls of the aeration tank structure to block and guide the oxygen bubbles, which travel upward undissolved and unused, to the underside of the bubble collection hood.
- a bubble collection hood installed in the aeration tank structure to collect the oxygen bubbles which travel upward in the aeration tank undissolved and unused and a hunch formed on the inner walls of the aeration tank structure to block and guide the oxygen bubbles, which travel upward undissolved and unused, to the underside of the bubble collection hood.
- the agitation device may be a submersible mixer.
- the agitation device may include: an injection nozzle; and a circulation pump to introduce the raw wastewater and recirculating mixed liquor of wastewater and microorganisms into the aeration tank structure at a designated speed through the injection nozzle.
- the aeration tank may further comprise a draft tube for guiding the flow of the mixed liquor transferred by the agitation device to a designated direction.
- the aeration tank may further comprise a flow barrier plate installed on the bubble collection hood to make sure that the raw wastewater introduced into the upper portion of the aeration tank be transferred to the area below the bubble collection hood so that the raw wastewater passes through the aeration zone without bypassing it.
- the aeration tank may further comprise subsidiary submersible mixers installed in the aeration tank structure to supplement the aeration and mixing effect of the above described agitation devices consisting of submersible mixers or injection nozzles.
- the number of each of the bubble collection device, the agitation device and the draft tube may be plural.
- the raw wastewater introduced into the aeration tank structure is mixed with pure oxygen produced by oxygen generator and then introduced into the aeration tank, and this mixture of wastewater and oxygen bubbles is hurled down from the underside of the bubble collection device to the lower portion of the aeration tank structure by the agitation device and then rises upward again.
- Oxygen bubbles increased in size due to the coalescing in the process get dispersed again into fine bubbles by the agitation device and the turbulence created by it. With its very large specific surface area, fine oxygen bubbles get easily dissolved in the wastewater and used in the respiration of the microorganisms.
- the bubble collection and recirculation facility guides and directs these rising bubbles back into the bubble collection hood for recirculation and reuse preventing the loss of oxygen through the air-water interface. Then, the oxygen bubbles are dispersed into fine bubbles by the agitation device installed below the bubble collection hood and the turbulence created by it, and recirculated again down to the lower portion of the aeration tank.
- the oxygen supplied to the aeration tank structure is sufficiently dissolved in the wastewater through the above recirculation cycle of the oxygen without dissipating into the atmosphere. Accordingly, the aeration tank in accordance with the present invention maintains a high level of dissolved oxygen in the aeration tank without sealing its top and maximizes transfer rate and utilization efficiency of the oxygen, thereby increasing treatment efficiency of organic substances and nutrients in the wastewater and remarkably reducing installation cost, operation cost and installation site requirement.
- Fig. 1 is a schematic longitudinal-sectional view of an apparatus for biological treatment of wastewater in accordance with a first embodiment of the present invention
- Fig. 2 is a schematic longitudinal-sectional view of an apparatus for biological treatment of wastewater in accordance with a second embodiment of the present invention
- Fig. 3 is a schematic longitudinal-sectional view of an apparatus for biological treatment of wastewater in accordance with a third embodiment of the present invention.
- Fig. 4 is a schematic cross-sectional view of the apparatus for biological treatment of wastewater in accordance with the third embodiment of the present invention
- Fig. 5 is a schematic longitudinal-sectional view of an apparatus for biological treatment of wastewater in accordance with a fourth embodiment of the present invention.
- Fig. 1 is a schematic longitudinal-sectional view of an apparatus for biological treatment of wastewater in accordance with a first embodiment of the present invention.
- Raw wastewater after its • primary treatment, is introduced into an aeration tank structure 100 by gravity fall, or through an inlet pipe 80 by a circulation pump 50.
- the mixture of wastewater, microorganisms and oxygen usually taken from the bottom of the aeration tank structure 100 is connected to the circulation pump 50 through a drain pipe 51, and mixed with the raw wastewater introduced thereinto through the inlet pipe 80, and then is transferred back into the aeration tank structure 100.
- Oxygen to be used for the respiration of microorganisms is generated by oxygen generator 10 installed at the outside of the aeration tank structure 100, and supplied to the upper end of a draft tube 40 through an oxygen supply pipe 11.
- a bubble collection hood 20 to prevent bubbles of the supplied oxygen from rising to the air-water interface and dissipating into the atmosphere, and an injection nozzle 30 installed downwards from a central location of the bubble collection hood 20 for injecting the wastewater supplied through an inlet pipe 52 at a designated speed or higher.
- the position of the injection nozzle 30 installed on the bubble collection hood 20 can be changed.
- the draft tube 40 for directing the wastewater introduced into the aeration tank structure 100 through the injection nozzle 30 at a designated angle is installed in the aeration tank structure 100.
- a subsidiary submersible mixer 35B is installed in the aeration tank structure 100 for improving mixing efficiency, and thus energy efficiency.
- the wastewater is injected into the draft tube 40 at a high speed through the circulation pump 50 and the injection nozzle 30, and the oxygen bubbles supplied through the oxygen supply pipe 11 are dispersed into fine bubbles having a comparatively large specific surface area by passing through the shearing zone below the injection nozzle 30, thereby being easily mixed with and dissolved in the wastewater.
- Most oxygen bubbles in the mixture get dissolved in the mixed liquor of wastewater and microorganisms while moving down towards the bottom of the aeration tank structure 100.
- the oxygen bubbles which are not dissolved in the mixture and travel upward, are collected and directed to the upper end of the draft tube 40 by the hunch 70 and the bubble collection hood 20.
- the oxygen bubbles are also sucked into the draft tube 40, and get dispersed into fine bubbles at the shearing zone below the injection nozzle 30. Then, the fine bubbles recirculate again towards the bottom of the aeration tank structure 100. It is possible to prevent the oxygen bubbles from flowing into the circulation pump 50 through the drain pipe 51 by adjusting the length of the draft tube 40.
- subsidiary submersible mixers 35A and 35B are installed for improved mixing and energy efficiency.
- the energy efficiency and mixing efficiency are reduced. Accordingly, it is preferable to have large portion of the mixing done with the subsidiary submersible mixers.
- Fig. 2 is a schematic longitudinal-sectional view of an apparatus for biological treatment of wastewater in accordance with a second embodiment of the present invention.
- Pure oxygen generated by the oxygen generator 10 passes through the oxygen supply pipe 11, and is supplied into the aeration tank through diffusers installed at the bottom of the aeration tank structure 100.
- the pure oxygen can also be introduced into the aeration tank structure 100 through the injection nozzle 30 together with the wastewater pumped back into the aeration tank by the circulation pump 50.
- the apparatus of the above-described second embodiment is designed in such a way that the raw wastewater does not pass through the circulation pump 50, but is introduced into the aeration tank structure 100 by gravity flow.
- FIGs. 3 and 4 are respectively schematic longitudinal-sectional and cross-sectional views of an apparatus for biological treatment of wastewater, in which the upper portion of an aeration tank structure 100 above the bubble collection hood 20 is divided into two parts by a flow barrier plate 60, in accordance with a third embodiment of the present invention.
- the flow barrier plate 60 When raw wastewater is introduced into the aeration tank structure 100, the flow barrier plate 60 prevents its shortcutting to the outlet from the aeration tank and make sure it flows down to the aeration zone below the bubble collection hood 20 through an opening in the left as shown by oblique lines so that the wastewater is sufficiently aerated for satisfactory decomposition of the organic substances and oxidation of the nutrients. Thereafter, the aerated wastewater is transferred above the bubble collection hood 20 through a rightside opening shown also by oblique lines for deaeration. Accordingly, the flow barrier plate 60 serves to allow the wastewater introduced into the aeration tank structure 100 to go through the aeration process without fail in the area under the bubble collection hood 20.
- the installation position of the bubble collection hood 20 and the flow barrier plate 60 in the aeration tank structure 100 can be suitably adjusted according to the types and compositions of the wastewater.
- Fig. 5 is a schematic longitudinal-sectional view of an apparatus for biological treatment of wastewater in accordance with a fourth embodiment of the present invention.
- the injection nozzle 30 and the circulation pump 50 used in the first to third embodiments are replaced with a submersible mixer 30'.
- Raw wastewater is introduced by gravity flow to the top of the aeration tank structure 100, or is introduced to the upper end of the draft tube 40 through the inlet pipe 52.
- oxygen generated by the oxygen generator 10 is supplied to the aeration tank structure 100 through a gas supply pipe 11A and mixed with the raw wastewater. Further, the oxygen may be supplied to the bottom of the aeration tank structure 100 through a gas supply pipe 1 IB.
- the submersible mixer 30' installed above the draft tube 40 serves to agitate and mix the raw wastewater and the oxygen introduced in the draft tube 40 at a high speed so that the wastewater, oxygen bubbles and microorganisms are well mixed and blended and simultaneously transferred down to a designated direction in the aeration tank structure 100. Further, the submersible mixer 30' serves to suck the undissolved oxygen bubbles rising upward, towards the center of the underside of the bubble collection hood 20,and into the upper end of the draft tube 40 and disperse them into fine bubbles.
- the oxygen transfer rate and utilization efficiency are maximized thanks to the increased specific surface area of the fine bubbles.
- a subsidiary submersible mixer 30 'A is installed in the aeration tank structure 100.
- the subsidiary submersible mixer 30'A serves to agitate the mixture of oxygen gas and wastewater transferred below the draft tube 40 at a high speed, thereby improving the contacting efficiency of the mixture and preventing sediments on the bottom of the aeration tank structure 100.
- mixers with high RPM.
- energy efficiency is impaired, it is preferable to use a high RPM submersible mixer 30' with small capacity and have a larger subsidiary submersible mixer 30'A with low RPM for most of the mixing requirement.
- the oxygen bubbles rising toward the top of the aeration tank structure 100 along the inner walls thereof are blocked by the hunch 70, and directed toward the central part of the underside of the bubble collection hood 20. Then, most of the bubbles are re-introduced into the draft tube 40, and repeatedly recirculated undergoing the above-described process.
- the apparatus in accordance with the fourth embodiment can repeatedly recirculate the mixture of wastewater, oxygen and microorganisms causing them to be thoroughly mixed, thereby maximizing oxygen transfer rate and utilization efficiency, which in turn insures increased efficiency in decomposition of organic substances and nutrient removal from the wastewater.
- the present invention provides an aeration tank for biological treatment of wastewater, in which the transfer rate and utilization efficiency of the oxygen introduced into the aeration tank are remarkably improved. It will enable more efficient treatment of organic substances and nutrients in the wastewater and subsequently reduction of the aeration tank structure volume, realizing substantial reduction of the installation cost, operation cost and the installation site requirement. Further, the aeration tank of the present invention enhances the reliability for the treatment efficiency of the wastewater and convenience in operation.
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- Life Sciences & Earth Sciences (AREA)
- Biodiversity & Conservation Biology (AREA)
- Microbiology (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Activated Sludge Processes (AREA)
- Aeration Devices For Treatment Of Activated Polluted Sludge (AREA)
Abstract
Disclosed is an aeration tank using a pure oxygen activated sludge process, in which pure oxygen is injected into the aeration tank so as to activate microorganisms, and organic substances and nutrients of the wastewater are decomposed by the activated microorganisms, comprising an aeration tank structure, and a bubble collection and recirculation facility including a bubble collection device installed in the aeration tank structure for guiding and collecting oxygen bubbles, which are undissolved in the wastewater and travel upward in the aeration tank, and an agitation device installed below the bubble collection device in the aeration tank structure for transferring the mixture of wastewater and oxygen introduced into the aeration tank structure along a designated direction while agitating the mixture. The aeration tank maintains a high concentration of dissolved oxygen therein, and maximizes oxygen transfer rate and utilization efficiency in the wastewater, thereby remarkably increasing treatment efficiency of the organic substances and nutrients in the wastewater and reducing the installation cost, the operation cost and the installation site requirement.
Description
APPARATUS FOR THE BIOLOGICAL TREATMENT OF WASTEWATER
Technical Field
The present invention relates to an apparatus for the biological treatment of wastewater, and more particularly to an aeration tank using a pure oxygen activated sludge process, in which pure oxygen is injected into the aeration tank in order to activate microorganisms, and organic substances and nutrients in the wastewater are decomposed by the activated microorganisms.
Background Art
In a conventional activated sludge method, which is a type of biological treatment processes of sewage or organic wastewater, a typical aeration tank has a water depth of approximately 4m to 5m and a low oxygen transfer rate of 5% to 10%, and requires a large installation site, thus being ineffective in terms of installation cost and operation cost from an economic standpoint and in terms of treatment efficiency and volume of the aeration tank structure from a technical standpoint. In order to solve the above-described problems and increase the treatment efficiency, various attempts have been made including a contact media process in which contact media is provided in the aeration tank. This improved the treatment efficiency to some degree but failed to bring it to a satisfactory level. And separation of the microorganisms from the media after an extended use made it difficult to maintain stable treatment. Oxygen transfer rate and utilization efficiency also need to be further improved.
Further, there has been proposed a pure oxygen aeration method in which pure oxygen is used to increase the treatment efficiency of the wastewater and reduce the installation site requirement by increasing the height of the aeration tank. However, the pure oxygen aeration method requires excessive installation cost and still achieves insufficient treatment efficiency. Furthermore, the most commonly used form of the above pure oxygen aeration method requires an aeration tank having a hermetically
sealed structure, thus being disadvantageous in that installation cost is high and carbon dioxide gas generated by the respiration of the microorganisms is not easily exhausted.
As a result of our continuous research efforts with the aim of overcoming the above-mentioned difficulties, we came to finalize our invention after confirming that by providing the bubble collection and recirculation device as will be described in the following chapters in an aeration tank of a pure oxygen activated sludge process in which pure oxygen is injected into the aeration tank so as to activate microorganisms and organic substances and nutrients are decomposed by these microorganisms, oxygen transfer rate and utilization efficiency can be substantially improved, and overall treatment efficiency can be increased, thereby resulting in the minimization of the aeration tank structure volume and thus substantial reduction of installation cost, operation cost and site requirement.
Disclosure of the Invention
Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide an aeration tank for biological treatment of wastewater, in which transfer rate and utilization efficiency of the oxygen in the wastewater introduced into the aeration tank are improved, thereby efficiently treating organic substances and nutrients in the wastewater. At the same time, the volume of the aeration tank structure can be minimized, remarkably reducing installation cost, operation cost and the installation site requirement. In accordance with the present invention, the above and other objects can be accomplished by the provision of an aeration tank using a pure oxygen activated sludge process, in which pure oxygen is injected into the aeration tank so as to activate microorganisms, and organic substances and nutrients of the wastewater are decomposed by the activated microorganisms, comprising: an aeration tank structure; and a bubble collection and recirculation facility including: a bubble collection device installed in the aeration tank structure for guiding and collecting oxygen bubbles which are undissolved in the wastewater and travel upwards in the aeration tank structure; and an agitation device installed below the bubble
collection device in the aeration tank structure for agitating and mixing the mixture of the wastewater, the microorganisms and the oxygen bubbles while moving them down to the lower portion of the aeration tank along a designated direction. Preferably, the bubble collection device may include: a bubble collection hood installed in the aeration tank structure to collect the oxygen bubbles which travel upward in the aeration tank undissolved and unused and a hunch formed on the inner walls of the aeration tank structure to block and guide the oxygen bubbles, which travel upward undissolved and unused, to the underside of the bubble collection hood.
Further, preferably, the agitation device may be a submersible mixer.
Further, preferably, the agitation device may include: an injection nozzle; and a circulation pump to introduce the raw wastewater and recirculating mixed liquor of wastewater and microorganisms into the aeration tank structure at a designated speed through the injection nozzle.
Moreover, preferably, the aeration tank may further comprise a draft tube for guiding the flow of the mixed liquor transferred by the agitation device to a designated direction. Preferably, the aeration tank may further comprise a flow barrier plate installed on the bubble collection hood to make sure that the raw wastewater introduced into the upper portion of the aeration tank be transferred to the area below the bubble collection hood so that the raw wastewater passes through the aeration zone without bypassing it. Further, preferably, the aeration tank may further comprise subsidiary submersible mixers installed in the aeration tank structure to supplement the aeration and mixing effect of the above described agitation devices consisting of submersible mixers or injection nozzles.
Moreover, if necessary, the number of each of the bubble collection device, the agitation device and the draft tube may be plural.
In accordance with the present invention, the raw wastewater introduced into the aeration tank structure is mixed with pure oxygen produced by oxygen generator and then introduced into the aeration tank, and this mixture of wastewater and oxygen bubbles is hurled down from the underside of the bubble collection device to the lower portion of the aeration
tank structure by the agitation device and then rises upward again. Oxygen bubbles increased in size due to the coalescing in the process get dispersed again into fine bubbles by the agitation device and the turbulence created by it. With its very large specific surface area, fine oxygen bubbles get easily dissolved in the wastewater and used in the respiration of the microorganisms. Without the bubble collection and recirculation facility by the present invention, oxygen bubbles, injected into the aeration tank, but undissolved and unused in the wastewater will travel upward towards the top surface and get vented into the ambient air, thus resulting in the loss of energy and impaired economy. However, in the present invention, the bubble collection and recirculation facility guides and directs these rising bubbles back into the bubble collection hood for recirculation and reuse preventing the loss of oxygen through the air-water interface. Then, the oxygen bubbles are dispersed into fine bubbles by the agitation device installed below the bubble collection hood and the turbulence created by it, and recirculated again down to the lower portion of the aeration tank.
Thus, the oxygen supplied to the aeration tank structure is sufficiently dissolved in the wastewater through the above recirculation cycle of the oxygen without dissipating into the atmosphere. Accordingly, the aeration tank in accordance with the present invention maintains a high level of dissolved oxygen in the aeration tank without sealing its top and maximizes transfer rate and utilization efficiency of the oxygen, thereby increasing treatment efficiency of organic substances and nutrients in the wastewater and remarkably reducing installation cost, operation cost and installation site requirement.
Brief Description of the Drawings
The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
Fig. 1 is a schematic longitudinal-sectional view of an apparatus for biological treatment of wastewater in accordance with a first embodiment of the present invention;
Fig. 2 is a schematic longitudinal-sectional view of an apparatus for biological treatment of wastewater in accordance with a second embodiment of the present invention;
Fig. 3 is a schematic longitudinal-sectional view of an apparatus for biological treatment of wastewater in accordance with a third embodiment of the present invention;
Fig. 4 is a schematic cross-sectional view of the apparatus for biological treatment of wastewater in accordance with the third embodiment of the present invention; and Fig. 5 is a schematic longitudinal-sectional view of an apparatus for biological treatment of wastewater in accordance with a fourth embodiment of the present invention.
Best Mode for Carrying Out the Invention
Now, preferred embodiments of the present invention will be described in detail with reference to the annexed drawings. The descriptions of such embodiments have been made only for a better understanding of the present invention. Those skilled in the art will appreciate that various modifications, additions, and substitutions to the embodiments are possible, without departing from the scope and spirit of the present invention as disclosed in the accompanying claims.
Fig. 1 is a schematic longitudinal-sectional view of an apparatus for biological treatment of wastewater in accordance with a first embodiment of the present invention. Raw wastewater, after its • primary treatment, is introduced into an aeration tank structure 100 by gravity fall, or through an inlet pipe 80 by a circulation pump 50. The mixture of wastewater, microorganisms and oxygen, usually taken from the bottom of the aeration tank structure 100 is connected to the circulation pump 50 through a drain pipe 51, and mixed with the raw wastewater introduced thereinto through the inlet pipe 80, and then is transferred back into the aeration tank structure 100.
Oxygen to be used for the respiration of microorganisms is generated by oxygen generator 10 installed at the outside of the aeration tank structure 100, and supplied to the upper end of a draft tube 40 through
an oxygen supply pipe 11.
In the aeration tank structure 100, there is provided a bubble collection hood 20 to prevent bubbles of the supplied oxygen from rising to the air-water interface and dissipating into the atmosphere, and an injection nozzle 30 installed downwards from a central location of the bubble collection hood 20 for injecting the wastewater supplied through an inlet pipe 52 at a designated speed or higher. Here, if necessary, the position of the injection nozzle 30 installed on the bubble collection hood 20 can be changed. Preferably, the draft tube 40 for directing the wastewater introduced into the aeration tank structure 100 through the injection nozzle 30 at a designated angle is installed in the aeration tank structure 100.
A hunch 70 for blocking and guiding oxygen bubbles, which are introduced into the aeration tank but undissolved in the water and travel upward, to the inside of the bubble collection hood 20, is installed on the inner walls of the aeration tank structure 100 below the bubble collection hood 20.
A subsidiary submersible mixer 35B is installed in the aeration tank structure 100 for improving mixing efficiency, and thus energy efficiency.
The wastewater is injected into the draft tube 40 at a high speed through the circulation pump 50 and the injection nozzle 30, and the oxygen bubbles supplied through the oxygen supply pipe 11 are dispersed into fine bubbles having a comparatively large specific surface area by passing through the shearing zone below the injection nozzle 30, thereby being easily mixed with and dissolved in the wastewater. Most oxygen bubbles in the mixture get dissolved in the mixed liquor of wastewater and microorganisms while moving down towards the bottom of the aeration tank structure 100. The oxygen bubbles, which are not dissolved in the mixture and travel upward, are collected and directed to the upper end of the draft tube 40 by the hunch 70 and the bubble collection hood 20. Here, when the mixture around the upper end of the draft tube 40 is sucked into the draft tube 40 at a comparatively high speed, the oxygen bubbles, increased in size due to coalescing, are also sucked into the draft tube 40, and get dispersed into fine bubbles at the shearing zone below the injection nozzle 30. Then, the fine bubbles recirculate again towards the bottom of the aeration tank structure 100. It is possible to prevent the oxygen
bubbles from flowing into the circulation pump 50 through the drain pipe 51 by adjusting the length of the draft tube 40.
In this embodiment, if necessary, subsidiary submersible mixers 35A and 35B are installed for improved mixing and energy efficiency. In case the collection and recirculation of the oxygen bubbles and mixing with the wastewater entirely depend on the injection nozzle 30 and the circulation pump 50, the energy efficiency and mixing efficiency are reduced. Accordingly, it is preferable to have large portion of the mixing done with the subsidiary submersible mixers. Since oxygen, once introduced into the aeration tank structure 100, is sufficiently dissolved in the wastewater by the above-described recirculation process without dissipating into the atmosphere, and used in the respiration of the microorganisms therein, and the powerful circulation of the mixture by means of the circulation pump 50 and the injection nozzle 30 improves the transfer efficiency of the oxygen into the wastewater, the treatment efficiency of the wastewater is remarkably improved. Accordingly, since most of the oxygen bubbles, which are not dissolved in the wastewater and travel upward in the aeration tank, are collected back and then reused in this embodiment of the present invention, the oxygen transfer rate and utilization efficiency are maximized, thereby more efficiently treating organic substances and nutrients of various types of wastewater, compared with prior arts.
Fig. 2 is a schematic longitudinal-sectional view of an apparatus for biological treatment of wastewater in accordance with a second embodiment of the present invention. Pure oxygen generated by the oxygen generator 10 passes through the oxygen supply pipe 11, and is supplied into the aeration tank through diffusers installed at the bottom of the aeration tank structure 100. In this case, the pure oxygen can also be introduced into the aeration tank structure 100 through the injection nozzle 30 together with the wastewater pumped back into the aeration tank by the circulation pump 50.
One end of the drain pipe 51 is positioned above the bubble collection hood 20, and the other end of the drain pipe 51 is connected to the circulation pump 50, thereby allowing the water in the upper and lower portions of the bubble collection hood 20 to be efficiently blended. Unlike the first embodiment, the apparatus of the above-described
second embodiment is designed in such a way that the raw wastewater does not pass through the circulation pump 50, but is introduced into the aeration tank structure 100 by gravity flow.
Although some parts of the apparatus of the second embodiment differ from those of the first embodiment, the apparatus of the second embodiment has the same effect as the first embodiment in that it improves the utilization efficiency and transfer rate of the oxygen by recirculating the mixture of oxygen and wastewater with a bubble collection and recirculation facility, and thus improve the treatment efficiency of the wastewater. Figs. 3 and 4 are respectively schematic longitudinal-sectional and cross-sectional views of an apparatus for biological treatment of wastewater, in which the upper portion of an aeration tank structure 100 above the bubble collection hood 20 is divided into two parts by a flow barrier plate 60, in accordance with a third embodiment of the present invention. When raw wastewater is introduced into the aeration tank structure 100, the flow barrier plate 60 prevents its shortcutting to the outlet from the aeration tank and make sure it flows down to the aeration zone below the bubble collection hood 20 through an opening in the left as shown by oblique lines so that the wastewater is sufficiently aerated for satisfactory decomposition of the organic substances and oxidation of the nutrients. Thereafter, the aerated wastewater is transferred above the bubble collection hood 20 through a rightside opening shown also by oblique lines for deaeration. Accordingly, the flow barrier plate 60 serves to allow the wastewater introduced into the aeration tank structure 100 to go through the aeration process without fail in the area under the bubble collection hood 20.
Here, the installation position of the bubble collection hood 20 and the flow barrier plate 60 in the aeration tank structure 100 can be suitably adjusted according to the types and compositions of the wastewater.
Fig. 5 is a schematic longitudinal-sectional view of an apparatus for biological treatment of wastewater in accordance with a fourth embodiment of the present invention. In this embodiment, the injection nozzle 30 and the circulation pump 50 used in the first to third embodiments are replaced with a submersible mixer 30'.
Raw wastewater is introduced by gravity flow to the top of the aeration tank structure 100, or is introduced to the upper end of the draft
tube 40 through the inlet pipe 52. During this process, oxygen generated by the oxygen generator 10 is supplied to the aeration tank structure 100 through a gas supply pipe 11A and mixed with the raw wastewater. Further, the oxygen may be supplied to the bottom of the aeration tank structure 100 through a gas supply pipe 1 IB.
The submersible mixer 30' installed above the draft tube 40 serves to agitate and mix the raw wastewater and the oxygen introduced in the draft tube 40 at a high speed so that the wastewater, oxygen bubbles and microorganisms are well mixed and blended and simultaneously transferred down to a designated direction in the aeration tank structure 100. Further, the submersible mixer 30' serves to suck the undissolved oxygen bubbles rising upward, towards the center of the underside of the bubble collection hood 20,and into the upper end of the draft tube 40 and disperse them into fine bubbles. As the undissolved oxygen bubbles, increased in size by coalescing while rising upward, get dispersed into fine bubbles by the submersible mixer 30' and the turbulence created by it, the oxygen transfer rate and utilization efficiency are maximized thanks to the increased specific surface area of the fine bubbles.
In case the aeration tank structure 100 has a large depth of water, a subsidiary submersible mixer 30 'A is installed in the aeration tank structure 100. The subsidiary submersible mixer 30'A serves to agitate the mixture of oxygen gas and wastewater transferred below the draft tube 40 at a high speed, thereby improving the contacting efficiency of the mixture and preventing sediments on the bottom of the aeration tank structure 100. In order to disperse the oxygen bubbles into fine ones, it is preferable to use mixers with high RPM. As, however, with a high RPM mixer, energy efficiency is impaired, it is preferable to use a high RPM submersible mixer 30' with small capacity and have a larger subsidiary submersible mixer 30'A with low RPM for most of the mixing requirement. The oxygen bubbles rising toward the top of the aeration tank structure 100 along the inner walls thereof are blocked by the hunch 70, and directed toward the central part of the underside of the bubble collection hood 20. Then, most of the bubbles are re-introduced into the draft tube 40, and repeatedly recirculated undergoing the above-described process. The apparatus in accordance with the fourth embodiment can
repeatedly recirculate the mixture of wastewater, oxygen and microorganisms causing them to be thoroughly mixed, thereby maximizing oxygen transfer rate and utilization efficiency, which in turn insures increased efficiency in decomposition of organic substances and nutrient removal from the wastewater.
Industrial Applicability
As apparent from the above description, the present invention provides an aeration tank for biological treatment of wastewater, in which the transfer rate and utilization efficiency of the oxygen introduced into the aeration tank are remarkably improved. It will enable more efficient treatment of organic substances and nutrients in the wastewater and subsequently reduction of the aeration tank structure volume, realizing substantial reduction of the installation cost, operation cost and the installation site requirement. Further, the aeration tank of the present invention enhances the reliability for the treatment efficiency of the wastewater and convenience in operation.
Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
Claims
1. An aeration tank using a pure oxygen activated sludge process, in which pure oxygen is injected into the aeration tank so as to activate microorganisms, and organic substances and nutrients in the wastewater are decomposed by the activated microorganisms, comprising: an aeration tank structure; and a bubble collection and recirculation facility consisting of: a bubble collection device installed in the aeration tank structure for guiding and collecting oxygen bubbles, which are undissolved in the wastewater and travel upward; and an agitation device installed in the aeration tank structure below the bubble collection device for transferring the mixture of wastewater and oxygen introduced into the aeration tank structure along a designated direction and agitating the mixture.
2. The aeration tank as set forth in claim 1, wherein the bubble collection device includes: a bubble collection hood installed in the aeration tank structure for collecting the oxygen bubbles, which are undissolved in the wastewater and travel upward in the aeration tank; and a hunch formed on the inner walls of the aeration tank structure for blocking and guiding the oxygen bubbles, which are undissolved in the wastewater and tyravel upward in the aeration tank, to the underside of the bubble collection hood.
3. The aeration tank as set forth in claim 1, wherein the agitation device comprises a submersible mixer.
4. The aeration tank as set forth in claim 1, wherein the agitation device includes: an injection nozzle; and a circulation pump for introducing raw wastewater and circulating the wastewater into the aeration tank structure at a designated speed through the injection nozzle.
5. The aeration tank as set forth in claim 1, further comprising: a draft tube for directing the flow of the mixture transferred by the agitation device to a designated direction.
6. The aeration tank as set forth in claim 1, further comprising: a flow barrier plate installed on the bubble collection hood for preventing the raw wastewater introduced into the upper portion of the aeration tank from shortcutting to the outlet and directing it to the lower portion of the aeration tank below the bubble collection hood so that the raw wastewater is aerated without fail.
7. The aeration tank as set forth in any one of claims 1 through 6, further comprising: subsidiary submersible mixer(s) installed in the aeration tank structure for reinforcing the mixing capacity of the agitation device which mixes wastewater with oxygen and microorganisms.
8. An aeration tank using a pure oxygen activated sludge process, in which pure oxygen is injected into the aeration tank so as to activate microorganisms, and organic substances and nutrients of the wastewater are decomposed by the activated microorganisms, comprising: an aeration tank structure; and a bubble collection and recirculation facility consisting of: a bubble collection device comprising: a bubble collection hood installed in the aeration tank structure for guiding and collecting oxygen bubbles, which are undissolved in the wastewater and travel upward in the aeration tank; and a hunch formed below the bubble collection hood on the inner walls of the aeration tank structure for blocking and directing the oxygen bubbles to the underside of the bubble collection hood; an agitation device including a submersible mixer installed below the bubble collection hood in the aeration tank structure for transferring the mixture of wastewater and oxygen introduced into the aeration tank structure along a designated direction and agitating the mixture; and a draft tube for guiding the flow of the mixture transferred by the agitation device to a designated direction in the aeration tank.
9. An aeration tank using a pure oxygen activated sludge process, in which pure oxygen is injected into the aeration tank so as to activate microorganisms, and organic substances and nutrients of the wastewater are decomposed by the activated microorganisms, comprising: an aeration tank structure; and a bubble collection and recirculation facility consisting of: a bubble collection device comprising: a bubble collection hood installed in the aeration tank structure for guiding and collecting oxygen bubbles, which are undissolved in the wastewater and rise upward in the aeration tank; and a hunch formed below the bubble collection hood on the inner walls of the aeration tank structure for blocking and directing the oxygen bubbles to the underside of the bubble collection hood; an agitation device comprising an injection nozzle installed below the bubble collection hood in the aeration tank structure for transferring the mixture of wastewater with oxygen and microorganisms along a designated direction in the aeration tank and agitating the mixture; and a circulation pump for introducing the raw wastewater and circulating wastewater into the aeration tank structure at a designated speed through the injection nozzle; and a draft tube for guiding the flow of the mixture transferred by the agitation device to a designated direction in the aeration tank.
10. The aeration tank as set forth in claim 8 or 9, further comprising: a flow barrier plate installed on the bubble collection hood for preventing the raw wastewater introduced into the upper portion of the aeration tank from shortcutting to the outlet and directing it to the lower portion of the aeration tank below the bubble collection hood so that the raw wastewater is aerated without fail.
11. The aeration tank as set forth in claim 8 or 9, further comprising: subsidiary submersible mixer(s) installed in the aeration tank structure for reinforcing the mixing capacity of the agitation device which mixes wastewater with oxygen and microorganisms.
12. The aeration tank as set forth in claim 8 or 9, wherein the number of each of the bubble collection device, the agitation device and the draft tube is two or more.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2003277728A AU2003277728A1 (en) | 2002-11-13 | 2003-11-12 | Apparatus for the biological treatment of wastewater |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR10-2002-0070221 | 2002-11-13 | ||
| KR1020020070221A KR20040042081A (en) | 2002-11-13 | 2002-11-13 | Sewage and wastewater treatment process and facilities |
| KR1020020079451A KR20040051785A (en) | 2002-12-13 | 2002-12-13 | Bubble Arresting and Recycling Method and Facilities for Biological Reactors of Wastewater Treatment Plants |
| KR10-2002-0079451 | 2002-12-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2004043866A1 true WO2004043866A1 (en) | 2004-05-27 |
Family
ID=32314155
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/KR2003/002424 WO2004043866A1 (en) | 2002-11-13 | 2003-11-12 | Apparatus for the biological treatment of wastewater |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AU2003277728A1 (en) |
| WO (1) | WO2004043866A1 (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007089113A1 (en) * | 2006-02-02 | 2007-08-09 | Jai-Hun Lee | Pure oxygen aeration system for wastewater treatment |
| CN110002688A (en) * | 2019-04-30 | 2019-07-12 | 倍杰特集团股份有限公司 | It is a kind of efficiently to mention mark system |
| CN110550752A (en) * | 2019-09-12 | 2019-12-10 | 国网湖南省电力有限公司 | Special nitrogen deoxidization aeration equipment of current conversion station |
| CN111003886A (en) * | 2019-12-11 | 2020-04-14 | 清华大学深圳国际研究生院 | Method and system for removing odor substances in sludge water |
| CN114558468A (en) * | 2022-03-18 | 2022-05-31 | 四川旅发环保科技有限公司 | Biological aeration device for fecal sewage treatment equipment |
| KR102539757B1 (en) * | 2022-04-15 | 2023-06-02 | 이근형 | Gas dissolution equipment |
| CN116789285A (en) * | 2023-08-22 | 2023-09-22 | 山东省科学院生态研究所(山东省科学院中日友好生物技术研究中心) | Inclined stirring oxygenation device and oxygenation method for sewage treatment |
| JP7474601B2 (en) | 2020-02-18 | 2024-04-25 | アクアス株式会社 | Gas-liquid dispersion device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2007089113A1 (en) * | 2006-02-02 | 2007-08-09 | Jai-Hun Lee | Pure oxygen aeration system for wastewater treatment |
| CN110002688A (en) * | 2019-04-30 | 2019-07-12 | 倍杰特集团股份有限公司 | It is a kind of efficiently to mention mark system |
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| JP7474601B2 (en) | 2020-02-18 | 2024-04-25 | アクアス株式会社 | Gas-liquid dispersion device |
| CN114558468A (en) * | 2022-03-18 | 2022-05-31 | 四川旅发环保科技有限公司 | Biological aeration device for fecal sewage treatment equipment |
| KR102539757B1 (en) * | 2022-04-15 | 2023-06-02 | 이근형 | Gas dissolution equipment |
| CN116789285A (en) * | 2023-08-22 | 2023-09-22 | 山东省科学院生态研究所(山东省科学院中日友好生物技术研究中心) | Inclined stirring oxygenation device and oxygenation method for sewage treatment |
| CN116789285B (en) * | 2023-08-22 | 2024-05-03 | 山东省科学院生态研究所(山东省科学院中日友好生物技术研究中心) | Inclined stirring oxygenation device and oxygenation method for sewage treatment |
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| Publication number | Publication date |
|---|---|
| AU2003277728A1 (en) | 2004-06-03 |
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