CA1191287A - Process and device for uprating the utilization rate of gas dissolved in a liquid - Google Patents
Process and device for uprating the utilization rate of gas dissolved in a liquidInfo
- Publication number
- CA1191287A CA1191287A CA000409990A CA409990A CA1191287A CA 1191287 A CA1191287 A CA 1191287A CA 000409990 A CA000409990 A CA 000409990A CA 409990 A CA409990 A CA 409990A CA 1191287 A CA1191287 A CA 1191287A
- Authority
- CA
- Canada
- Prior art keywords
- liquid
- ditch
- gas
- mixing
- channel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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
- C02F3/1236—Particular type of activated sludge installations
- C02F3/1257—Oxidation ditches
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
- B01F23/20—Mixing gases with liquids
- B01F23/23—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
- B01F25/30—Injector mixers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
- B01F25/50—Circulation mixers, e.g. wherein at least part of the mixture is discharged from and reintroduced into a receptacle
- B01F25/51—Circulation mixers, e.g. wherein at least part of the mixture is discharged from and reintroduced into a receptacle in which the mixture is circulated through a set of tubes, e.g. with gradual introduction of a component into the circulating flow
-
- 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
- C02F3/1294—"Venturi" aeration means
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Biodiversity & Conservation Biology (AREA)
- Microbiology (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Organic Chemistry (AREA)
- Aeration Devices For Treatment Of Activated Polluted Sludge (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
Process and device for increasing the rate of solu-tion of gas in a liquid. A mixture of a liquid and gaseous component is fed into a covered channel for secondary mixing, said secondary mixing channel being disposed in an elongated circulation oxidation ditch. The energy of the mixture flow-ing out of the secondary mixing channel impels the liquid in the channel in the direction of the longitudinal axis of such channel, and increases the rate of solution of the gas in such liquid. At the same time, the gas-liquid discharge ratio is decreased while the rate of liquid component discharge is increased.
Process and device for increasing the rate of solu-tion of gas in a liquid. A mixture of a liquid and gaseous component is fed into a covered channel for secondary mixing, said secondary mixing channel being disposed in an elongated circulation oxidation ditch. The energy of the mixture flow-ing out of the secondary mixing channel impels the liquid in the channel in the direction of the longitudinal axis of such channel, and increases the rate of solution of the gas in such liquid. At the same time, the gas-liquid discharge ratio is decreased while the rate of liquid component discharge is increased.
Description
2~
The present invention relates to a process of and a device for saturating a liquid with a gas.
Various processes and devices have been employed for the saturation of liquids with gases; for example, DOS
2 612 255 utilizes injectors in a circulation trough. The economic advantage of such apparatus and process depends upon the rate of saturation of the liquid by the gas.
Through-flow saturation using steady flow transi-tion phenomena, such as a ring jump, has been shown to be an extremely suitable process for saturating a liquid with a gas, for example, in the most common case saturating water with air oxygen.
The amount of gas dissolved in the liquid is limited by the saturation concentration of such liqu.id with the gas under given conditions. The rate of dissolving of the gas is defined as the ratio of the amount of dissoLvecl g~s to the total amount of gas supp~ied to the liquid. Such rate d~pen~
most importantly among other factors upon the gas-liquid dis-charye ratio, that is, the ratio of the discharges of the gaseous and liquid components, in the through-flow mixing, and is limited by it. The rate of dissolving of the gas in the liquid can be increased by decreasing the gas-liquid discharge rate. This can be accomplished by the method and apparatus of the present invention without any perceptible loss of the energy required for dissolving the gas in the liquid.
According to the present invention, there is pro-vided a process for increasing the rate of solution of a yas in a liquid in through-flow mixing, comprising clrculating a mix-ture of a liquid and a gaseous component formed by dissolved gas together with other gases into an elongated circulation oxidation ditch in the direction of the longitudinal axis of such ditch, reducing the gas-liquid discharge ratio in such manner that the discharge of the liquid component emerging from a primary mixing conduit is increased by the part of the 2~
licluid discharge ~hich circulates in the circulation ditch, introducing the discnarge of liquid and gaseous component emerging from the primary mixing conduit directly into a secondary mixing channel which directly joins the circulation so that the transfer process which starts directly in the primary mixing conduit continues in the secondary mixing channel.
According to the present invention, there is also provided a device for increasing the rate of solution of a gas and a liquid in a primary through-flow mixing conduit, com-prising a reaction tank formed by at least one circulation oxidation ditch, a channel of secondary mixing in the circu-lation ditch, said seconclary mixing channel immediately join-ing the primary mixing conduit and belng in the shape o~ a covered channel :into which a mixture o~ liquid and CJa5 1~ .E~
ThereEore, in accordance with the prese~t invention the liquid in which the g~s is to be dissolved is circulated in an elongated endless circulation ditch, there being a pipe feeding a mixture of -the liquid and the gaseous component having an outlet disposed in the inlet part of the covered secondary mixing channel or trough ditch, the inlet ener~y of such gas-liquid mixture inducing circulation of the liquid in the ditch. The mixture of the liquid and gaseous component may be formed by steady flow transition phenomena, for example by a ring jun-lp. The gas-llquld mixture is leacl to the covered trough of a secondary mixing means which is preEer-ably disposed in the circulation ditch. As above-noted, the discharge energy of the gas-liquid mixture into the liquid in the ditch maintains the circulation of such liquid, as well as causing the gas-liquid mixture to be mixed with the liquid in the ditch. The rate of dissolving of the gas in the liquid increases with a decrease of the gas-liquid discharge ratio.
When the saturated liquid is not lead directly and is repumped, the inflow of the repumped liquid to the pump leads inwardly through a hole in a hydrodynamically designed bottom sill in the channel while maintaining the flow veloc-ities in the ditch. When a plurality of circulatlon ditches are employed for mixing, they can be interconnected in parallel or in series depending upon -the nature o:E the saturation pro-cess used.
The invention will be more readily understood upon consideration of the accompanying drawings, in which:
Fig. 1 is a schematic view in side elevation oi a portion of the apparatus of the invention including a through-flow mixer disposed in a circulation oxidation ditch;
Fig. 2 is a foreshortened view in plan of an instal-lation incorporating a plurality of circulation oxidation ditches each of which incorporates two through-flow mixers in ~5 accordance with the inventlon; and Figs. 3 and 4 illustrate respective alt~rna~ivc~
desiyns of a secondary mixing channel hy its beincJ recessecl under the bottom level of the oxidation ditch, the construc-tions of Figs. 3 and 4 being suitable for use in a shallow oxidation ditch.
Turning first to Fig. 1, in a continuous recircula-tion ditch 1 containing a liquid which extends to a level L
near the top thereof. In such portion of the ditch 1 there is an inflow pipe ~ extending from the bottom of the dikch up-wardly to a pump 5, the inflow pipe 4 having its lower inletend disposed within an opening or recess 6 in a streamlined bottom sill portion 7 of the ditch.
The pump 5 is provided with an exhaust manifold 9 from which there extend a plurality of laterally spaced dis-charge pipes 2 which extend horizontally for a short distance,then extend downwardly at 11 and finally are curved at the bottom so that such curved lower end 12 thereof lies within a laterally extended covered trough 3. As shown, discharge from the lower ends of the pipes 2 travel in the same direc-tion as the general flow of recirculating liquid in the ditch1. Near the top of eaeh of the pipes 2, adjaeent the dis-eharge manifold 9, there enters a vertieal gas-conducting pipe 10. The vertical portion of the pipe 2 is of somewhat larger diameter than the upper and lower end portions thereof, pipe 11 eonstituting a mixer for the liquid which has been fed thereto from the diseharge manifold and the gas whieh has been introduced thereinto through the pipe 10.
Turning now to Fig. 2, a plurality of recirculation oxidation ditches 1 are shown, such ditches being fed with the main body of liquid through a pipe 8 having entry ports 15 leading to the respective recirculation ditches; the ditches 1 and outlets 14 are thus eonneeted in series by the eonduits 8.
In eaeh of the reeireulation ditehes 1 -two pum~ ancl mixer units as shown in l~ig. 1 are disposed in oppos:L~
relationship adjaeent the opposite ends of the reci.reulation ditch. It will thus be seen that in each of ditehes 1 the main body of liquid in the ditch i.s driven in a generally eloekwise direetion b~ the gas-liquid mixture introdueed therein by the pump and mixer unit, the resulting mixture of the main body of liquid and the introduced gas~liquid mixture being eonstrained to travel lenyth~ise along one side of the diteh in the sub-diteh formed between the side oE the tan)c or diteh-forming member and a longitudi.nal dividing partition 13.
The gas-liquid mixture then travels around the end of the dividing partition, flows longitudinally of the diteh in a direction opposite that of the first longitudinal flow thereof and finally travels around the other end of the dividing partition 13.
~ he process and the device of the invention can be used to advantage in the chemieal and other industries, in water management, and partieularly in waste water treatment by oxidation as in the biological treatment of sewage.
In a preferred embodiment of the device of the invention the circulation ditch of a waste water treatment plant has a volume of 760 cubic meters, the water in the ditch moves longitudinally thereof with a velocity of 0.7 meters per second, the through-flow mixers 5, 9, lO/ 11 repump a mixture of liquid and gas into the main body of liquid in the ditch at the rate of 2 x 0.175 cubic meters per second, that is, in the ditch a discharge of 6.7 cubic meters per second is recirculated and the added amount of dissolved oxygen and the transfer rate per required unit of power are increased by 56%
over a known comparable prior art device.
Parts in Figs. 3 and 4 which are the same as those in Figs. 1 and 2 are designated by the same reference charac-ters as in the earlier figures. As above stated, the devices of Figs. 3 and ~ are suitable for use in a shallow oxidation ditch .
In the embodiment shown in E'ig. 3, the bottom :L6 o.E
ditch l slants at 17 at a relatively small angle with respect to the horizontal level surface 18. The lower end 12 of mixing pipe is disposed at the left hand end (the beginning of level surface 18). Somewhat to the xight of end 12 of pipe ll, and adjacent the right hand end of channel 3, the bottom l~ of ditch l slants shallowly upwardly to rejoin the level 16 of the general bottom of the ditch l.
In the embodiment of Fig. ~, the bottom 16 slants sharply downwardly at 20, and slants shallowly upward at 21 to regain the general level 16 of d.itch l. The outlet 12 of pipe ll is disposed within the space provided between the right hand end of surface 20 and the left hand end of surface 21.
The reaction ditch with longitudinal flow, in which circulates the saturated liquid e.g. the treated water with activated sludge that is brought into longitudinal movement by the outflow from one or more aeration devices from which the mixture of recirculated liquid and air (or another gas) flows ' 8~
into the reaction ditch in longitudinal direction in such a way, whereby the improvement lies in the withdrawal of water for recirculation from the reaction ditch by means of a hydraulically shaped bottom sill and by situating the covered canal of secondary mixing into the bottom pa~t of the ditch, whereby the aerator mixing tube opens into this canal, ~hus creating a triple successive mixing, first in the mixing tube, then in the covered canal of secondary mixing and finally in the ditch as such and that with electric energy saving, and these improvements incorporate:
(A) the hydraulically-shaped upward convex bottom sill situated on the reaction ditch bottom and ~n its upstream side it has the opening 6 that does not interfere with the upper convex part of the sill and into which is joined the tube 4, leadin~ to the pump 5, whereby the concave curve of the sill is designed so that during the inflow of the recircu~ated part o.~ th~ uid fQr the given liquid discharcJ~ abov~ th~ bottom sill no marked head loss occurs, (B) a low-pressure pump whose inlet is connected by the pipe 4 with the bottom sill and the outlet is connected with the aeration device that is open into the mixing tube 11, (Ct a covered secondary mixing channel 3, situated in the bottom part of the reaction ditch, whereby the covering of this channel is formed 1) by a horizontal separating wall situated above the reaction ditch bottom, or 2) by a horizon-tal or a slightly slanting separating wall situated flush with reaction ditch floor or below .it, whereby under the separating wall the reaction ditch bottom is gradually lowered 50 that a secondary mixin~ channel is thus formed under the separating wall, whereby the secondary mixing canal pro~ile and its location to the outlets of the primary mixing pipes 11 is chosen in such a way that turbulence created in the mixing tube 11 is maintained, whereby the length of the secondary mixing canal is only such, that the homogeneous bubble mixture of the gaseous component in the liquid is maintained in the secondary mixing channel, and (D) an aeration device joined by its liquid inlet to the pump and by its outlet to the mixing tube 11 with its lower end 12 open into the secondary mixing canal 3, into which it brings the recirculated liquid-air mixture which flows in the secondary mixing canal together with the respective part of the recirculated flow, whereby this arrangement a) forces the liquid in the reaction ditch to move in a longitudinal movement, b) creates a triple successive mixing with varying concentration gradients and that: the first mixing in the aerator and mixing tube 11, second mixing in the covered channel of secondary mixing 3 and the third mixiny at the outlet from this canal, where the liquid from the canal ~ets mixed with the other liquid, ~lowing in the ditcl~ in th~
conformable direction, c) it prolongs the total contact time of the gas bubbles with the liquid without creating undesirable air cushions or separating the phases, d) the mixing in the secondary mixing canal takes place in the point of the highest hydrostatical pressure without requiring for this effect a special device or con-structional modifications, e) although for this solution, an aerator of the ring-jump type is most advantageous also another aeration ~evice type can be used, this arrangement means an essential energy saving.
Although the invention is ~llustrated and described with reference to a plurality of embodiments thereof, it is to be expressly understood that it is in no way limited to the disclosure of such embodiments but is capable of numerous modifications within the scope of the appended claims.
The present invention relates to a process of and a device for saturating a liquid with a gas.
Various processes and devices have been employed for the saturation of liquids with gases; for example, DOS
2 612 255 utilizes injectors in a circulation trough. The economic advantage of such apparatus and process depends upon the rate of saturation of the liquid by the gas.
Through-flow saturation using steady flow transi-tion phenomena, such as a ring jump, has been shown to be an extremely suitable process for saturating a liquid with a gas, for example, in the most common case saturating water with air oxygen.
The amount of gas dissolved in the liquid is limited by the saturation concentration of such liqu.id with the gas under given conditions. The rate of dissolving of the gas is defined as the ratio of the amount of dissoLvecl g~s to the total amount of gas supp~ied to the liquid. Such rate d~pen~
most importantly among other factors upon the gas-liquid dis-charye ratio, that is, the ratio of the discharges of the gaseous and liquid components, in the through-flow mixing, and is limited by it. The rate of dissolving of the gas in the liquid can be increased by decreasing the gas-liquid discharge rate. This can be accomplished by the method and apparatus of the present invention without any perceptible loss of the energy required for dissolving the gas in the liquid.
According to the present invention, there is pro-vided a process for increasing the rate of solution of a yas in a liquid in through-flow mixing, comprising clrculating a mix-ture of a liquid and a gaseous component formed by dissolved gas together with other gases into an elongated circulation oxidation ditch in the direction of the longitudinal axis of such ditch, reducing the gas-liquid discharge ratio in such manner that the discharge of the liquid component emerging from a primary mixing conduit is increased by the part of the 2~
licluid discharge ~hich circulates in the circulation ditch, introducing the discnarge of liquid and gaseous component emerging from the primary mixing conduit directly into a secondary mixing channel which directly joins the circulation so that the transfer process which starts directly in the primary mixing conduit continues in the secondary mixing channel.
According to the present invention, there is also provided a device for increasing the rate of solution of a gas and a liquid in a primary through-flow mixing conduit, com-prising a reaction tank formed by at least one circulation oxidation ditch, a channel of secondary mixing in the circu-lation ditch, said seconclary mixing channel immediately join-ing the primary mixing conduit and belng in the shape o~ a covered channel :into which a mixture o~ liquid and CJa5 1~ .E~
ThereEore, in accordance with the prese~t invention the liquid in which the g~s is to be dissolved is circulated in an elongated endless circulation ditch, there being a pipe feeding a mixture of -the liquid and the gaseous component having an outlet disposed in the inlet part of the covered secondary mixing channel or trough ditch, the inlet ener~y of such gas-liquid mixture inducing circulation of the liquid in the ditch. The mixture of the liquid and gaseous component may be formed by steady flow transition phenomena, for example by a ring jun-lp. The gas-llquld mixture is leacl to the covered trough of a secondary mixing means which is preEer-ably disposed in the circulation ditch. As above-noted, the discharge energy of the gas-liquid mixture into the liquid in the ditch maintains the circulation of such liquid, as well as causing the gas-liquid mixture to be mixed with the liquid in the ditch. The rate of dissolving of the gas in the liquid increases with a decrease of the gas-liquid discharge ratio.
When the saturated liquid is not lead directly and is repumped, the inflow of the repumped liquid to the pump leads inwardly through a hole in a hydrodynamically designed bottom sill in the channel while maintaining the flow veloc-ities in the ditch. When a plurality of circulatlon ditches are employed for mixing, they can be interconnected in parallel or in series depending upon -the nature o:E the saturation pro-cess used.
The invention will be more readily understood upon consideration of the accompanying drawings, in which:
Fig. 1 is a schematic view in side elevation oi a portion of the apparatus of the invention including a through-flow mixer disposed in a circulation oxidation ditch;
Fig. 2 is a foreshortened view in plan of an instal-lation incorporating a plurality of circulation oxidation ditches each of which incorporates two through-flow mixers in ~5 accordance with the inventlon; and Figs. 3 and 4 illustrate respective alt~rna~ivc~
desiyns of a secondary mixing channel hy its beincJ recessecl under the bottom level of the oxidation ditch, the construc-tions of Figs. 3 and 4 being suitable for use in a shallow oxidation ditch.
Turning first to Fig. 1, in a continuous recircula-tion ditch 1 containing a liquid which extends to a level L
near the top thereof. In such portion of the ditch 1 there is an inflow pipe ~ extending from the bottom of the dikch up-wardly to a pump 5, the inflow pipe 4 having its lower inletend disposed within an opening or recess 6 in a streamlined bottom sill portion 7 of the ditch.
The pump 5 is provided with an exhaust manifold 9 from which there extend a plurality of laterally spaced dis-charge pipes 2 which extend horizontally for a short distance,then extend downwardly at 11 and finally are curved at the bottom so that such curved lower end 12 thereof lies within a laterally extended covered trough 3. As shown, discharge from the lower ends of the pipes 2 travel in the same direc-tion as the general flow of recirculating liquid in the ditch1. Near the top of eaeh of the pipes 2, adjaeent the dis-eharge manifold 9, there enters a vertieal gas-conducting pipe 10. The vertical portion of the pipe 2 is of somewhat larger diameter than the upper and lower end portions thereof, pipe 11 eonstituting a mixer for the liquid which has been fed thereto from the diseharge manifold and the gas whieh has been introduced thereinto through the pipe 10.
Turning now to Fig. 2, a plurality of recirculation oxidation ditches 1 are shown, such ditches being fed with the main body of liquid through a pipe 8 having entry ports 15 leading to the respective recirculation ditches; the ditches 1 and outlets 14 are thus eonneeted in series by the eonduits 8.
In eaeh of the reeireulation ditehes 1 -two pum~ ancl mixer units as shown in l~ig. 1 are disposed in oppos:L~
relationship adjaeent the opposite ends of the reci.reulation ditch. It will thus be seen that in each of ditehes 1 the main body of liquid in the ditch i.s driven in a generally eloekwise direetion b~ the gas-liquid mixture introdueed therein by the pump and mixer unit, the resulting mixture of the main body of liquid and the introduced gas~liquid mixture being eonstrained to travel lenyth~ise along one side of the diteh in the sub-diteh formed between the side oE the tan)c or diteh-forming member and a longitudi.nal dividing partition 13.
The gas-liquid mixture then travels around the end of the dividing partition, flows longitudinally of the diteh in a direction opposite that of the first longitudinal flow thereof and finally travels around the other end of the dividing partition 13.
~ he process and the device of the invention can be used to advantage in the chemieal and other industries, in water management, and partieularly in waste water treatment by oxidation as in the biological treatment of sewage.
In a preferred embodiment of the device of the invention the circulation ditch of a waste water treatment plant has a volume of 760 cubic meters, the water in the ditch moves longitudinally thereof with a velocity of 0.7 meters per second, the through-flow mixers 5, 9, lO/ 11 repump a mixture of liquid and gas into the main body of liquid in the ditch at the rate of 2 x 0.175 cubic meters per second, that is, in the ditch a discharge of 6.7 cubic meters per second is recirculated and the added amount of dissolved oxygen and the transfer rate per required unit of power are increased by 56%
over a known comparable prior art device.
Parts in Figs. 3 and 4 which are the same as those in Figs. 1 and 2 are designated by the same reference charac-ters as in the earlier figures. As above stated, the devices of Figs. 3 and ~ are suitable for use in a shallow oxidation ditch .
In the embodiment shown in E'ig. 3, the bottom :L6 o.E
ditch l slants at 17 at a relatively small angle with respect to the horizontal level surface 18. The lower end 12 of mixing pipe is disposed at the left hand end (the beginning of level surface 18). Somewhat to the xight of end 12 of pipe ll, and adjacent the right hand end of channel 3, the bottom l~ of ditch l slants shallowly upwardly to rejoin the level 16 of the general bottom of the ditch l.
In the embodiment of Fig. ~, the bottom 16 slants sharply downwardly at 20, and slants shallowly upward at 21 to regain the general level 16 of d.itch l. The outlet 12 of pipe ll is disposed within the space provided between the right hand end of surface 20 and the left hand end of surface 21.
The reaction ditch with longitudinal flow, in which circulates the saturated liquid e.g. the treated water with activated sludge that is brought into longitudinal movement by the outflow from one or more aeration devices from which the mixture of recirculated liquid and air (or another gas) flows ' 8~
into the reaction ditch in longitudinal direction in such a way, whereby the improvement lies in the withdrawal of water for recirculation from the reaction ditch by means of a hydraulically shaped bottom sill and by situating the covered canal of secondary mixing into the bottom pa~t of the ditch, whereby the aerator mixing tube opens into this canal, ~hus creating a triple successive mixing, first in the mixing tube, then in the covered canal of secondary mixing and finally in the ditch as such and that with electric energy saving, and these improvements incorporate:
(A) the hydraulically-shaped upward convex bottom sill situated on the reaction ditch bottom and ~n its upstream side it has the opening 6 that does not interfere with the upper convex part of the sill and into which is joined the tube 4, leadin~ to the pump 5, whereby the concave curve of the sill is designed so that during the inflow of the recircu~ated part o.~ th~ uid fQr the given liquid discharcJ~ abov~ th~ bottom sill no marked head loss occurs, (B) a low-pressure pump whose inlet is connected by the pipe 4 with the bottom sill and the outlet is connected with the aeration device that is open into the mixing tube 11, (Ct a covered secondary mixing channel 3, situated in the bottom part of the reaction ditch, whereby the covering of this channel is formed 1) by a horizontal separating wall situated above the reaction ditch bottom, or 2) by a horizon-tal or a slightly slanting separating wall situated flush with reaction ditch floor or below .it, whereby under the separating wall the reaction ditch bottom is gradually lowered 50 that a secondary mixin~ channel is thus formed under the separating wall, whereby the secondary mixing canal pro~ile and its location to the outlets of the primary mixing pipes 11 is chosen in such a way that turbulence created in the mixing tube 11 is maintained, whereby the length of the secondary mixing canal is only such, that the homogeneous bubble mixture of the gaseous component in the liquid is maintained in the secondary mixing channel, and (D) an aeration device joined by its liquid inlet to the pump and by its outlet to the mixing tube 11 with its lower end 12 open into the secondary mixing canal 3, into which it brings the recirculated liquid-air mixture which flows in the secondary mixing canal together with the respective part of the recirculated flow, whereby this arrangement a) forces the liquid in the reaction ditch to move in a longitudinal movement, b) creates a triple successive mixing with varying concentration gradients and that: the first mixing in the aerator and mixing tube 11, second mixing in the covered channel of secondary mixing 3 and the third mixiny at the outlet from this canal, where the liquid from the canal ~ets mixed with the other liquid, ~lowing in the ditcl~ in th~
conformable direction, c) it prolongs the total contact time of the gas bubbles with the liquid without creating undesirable air cushions or separating the phases, d) the mixing in the secondary mixing canal takes place in the point of the highest hydrostatical pressure without requiring for this effect a special device or con-structional modifications, e) although for this solution, an aerator of the ring-jump type is most advantageous also another aeration ~evice type can be used, this arrangement means an essential energy saving.
Although the invention is ~llustrated and described with reference to a plurality of embodiments thereof, it is to be expressly understood that it is in no way limited to the disclosure of such embodiments but is capable of numerous modifications within the scope of the appended claims.
Claims (3)
1. A process for increasing the rate of solution of a gas in a liquid in through-flow mixing, comprising cir-culating a mixture of a liquid and a gaseous component formed by dissolved gas together with other gases into an elongated circulation oxidation ditch in the direction of the longitu-dinal axis of such ditch, reducing the gas-liquid discharge ratio in such manner that the discharge of the liquid com-ponent emerging from a primary mixing conduit is increased by the part of the liquid discharge which circulates in the circulation ditch, introducing the discharge of liquid and gaseous component emerging from the primary mixing conduit directly into a secondary mixing channel which directly joins the circulation so that the transfer process which starts directly in the primary mixing conduit continues in the second-ary mixing channel.
2. A device for increasing the rate of solution of a gas and a liquid in a primary through-flow mixing conduit, comprising a reaction tank formed by at least one circulation oxidation ditch, a channel of secondary mixing in the circula-tion ditch, said secondary mixing channel immediately joining the primary mixing conduit and being in the shape of a covered channel into which a mixture of liquid and gas is fed.
3. A device according to claim 2, wherein the circulation ditch is provided with a hydrodynamically designed bottom sill having an inlet part therein which is connected to the inlet conduit of a pump, such pump propelling the liquid through the gas-liquid mixing device and the secondary mixing channel into the liquid being circulated in the circulation ditch.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CSPV6345-81 | 1981-08-25 | ||
| CS816345A CS223313B1 (en) | 1981-08-25 | 1981-08-25 | Method of increasing the exploitation degree of the dissolved gas in the liquid and device for executing the same method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1191287A true CA1191287A (en) | 1985-07-30 |
Family
ID=5410271
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000409990A Expired CA1191287A (en) | 1981-08-25 | 1982-08-24 | Process and device for uprating the utilization rate of gas dissolved in a liquid |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5884032A (en) |
| CA (1) | CA1191287A (en) |
| CS (1) | CS223313B1 (en) |
| DE (1) | DE3231563A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3724692A1 (en) * | 1987-07-25 | 1989-02-02 | Fred Dipl Ing Petersen | Method for introducing oxygen into water and apparatus for carrying out the method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1486697A (en) * | 1975-03-25 | 1977-09-21 | Dwars Ing Bureau | Process and installation for the purification of sewage |
-
1981
- 1981-08-25 CS CS816345A patent/CS223313B1/en unknown
-
1982
- 1982-08-24 CA CA000409990A patent/CA1191287A/en not_active Expired
- 1982-08-25 DE DE3231563A patent/DE3231563A1/en active Granted
- 1982-08-25 JP JP57146298A patent/JPS5884032A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0234649B2 (en) | 1990-08-06 |
| JPS5884032A (en) | 1983-05-20 |
| DE3231563C2 (en) | 1988-06-09 |
| CS223313B1 (en) | 1983-09-15 |
| DE3231563A1 (en) | 1983-03-10 |
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| MKEX | Expiry |