CA2006928C - Decanter device - Google Patents
Decanter deviceInfo
- Publication number
- CA2006928C CA2006928C CA 2006928 CA2006928A CA2006928C CA 2006928 C CA2006928 C CA 2006928C CA 2006928 CA2006928 CA 2006928 CA 2006928 A CA2006928 A CA 2006928A CA 2006928 C CA2006928 C CA 2006928C
- Authority
- CA
- Canada
- Prior art keywords
- pipe
- tank
- membrane
- decanter
- outlet
- 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 - Fee Related
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- Separation Using Semi-Permeable Membranes (AREA)
- Centrifugal Separators (AREA)
Abstract
Disclosed is a decanter device for use to withdraw supernatant liquid from a reactor tank containing a mixture of liquids of different densities or a liquid mixed with solid particles to be separated. The device comprises a perforated pipe mounted inside the tank. The pipe has a plurality of inlets in the form of small orifices opening into the tank, and at least one outlet leading out of the tank. An inflatable membrane is mounted inside the pipe in such a manner as to extend over the small orifices and sealingly close the inlets of the pipe when it is inflated, and to extend away from the small orifices and away from the outlet to allow supernatant liquid to flow out of the tank through the pipe when the membrane is not inflated.
source of air or water under pressure is used for inflating the membrane whenever desired to sealingly close the inlets of the pipe and thus prevent liquid or solids to penetrate in the pipe during reaction within the reactor tank. This device is particularly useful for biological wastewater treatment reactors.
source of air or water under pressure is used for inflating the membrane whenever desired to sealingly close the inlets of the pipe and thus prevent liquid or solids to penetrate in the pipe during reaction within the reactor tank. This device is particularly useful for biological wastewater treatment reactors.
Description
2()~
BACKGROUND OF THE INVENTION
a) Field of the invention The present invention relates to a decanter device for use to withdraw supernatant liquid from a tank containing a mixture of liquids of different densities or a mix-ture of a liquid and solid particles to be separated.
b) Description of the Prior Art Decanter devices o~ different structures are presently known and commonly used in the wastewater treatment industry to decant supernatant liquid from a tank OE reseEvoi~N usually called "reactor", containing a liquor to be processe~, consisting of a mixture of liquids of different ~ensities or a mixture of a 1iquid and solid partic1es.
The biologica1 wastewater treatments which are carried out in ~he }eactor, usually involve meehanical, biological, physical and/o} chemical reactlons and~or 2~ processings which Eesult in an homogeneous mixin~ of the processed liquor. AfteE suffieient }ea¢tioM tim2, it is often necessary to separate the liquids andlor solids. Such a separation is normally done by allowinglthe mixture to sediment by gravity. To achieve such a sedimentation, mixing is simply interrupted for a period of time sufficient to allow for gravity separation to OCCUE withln the liquor.
- Then, the denser OE heavier liquid or particles slowly deposit at the bottom of the reactor while the lighter or clearer liquid "moves" up to the surface, e.g. on top of the sediments, where it forms a supernatant liquid solution that can be decanted (e.g. removed) from the reactor through a pipe known as a "decanter device" leading out of the reactor and having at least one opening so located in the reactor as to enable withdrawing of the supernatant liquid.
,, ... .
- -' ' 9~8 As aforesaid, decanter devices of many kinds have been designed and are presen-tly used -to remove supernatant liquid solutions from reactors, especially from those used for carrying out the municipal and industrial wastewater treatment process known as "sequential batch reactor (SBR) treatment processes".
Considering that most applications, especially in SBR processes, require improved performances to cope with the continuous superior requirements for supernatant quality in terms of separation and suspended sollds content, the decante~ device to be used in the reacto~ tank must be very efficient and must satisfy several very specific re~irements.
To bette} understand such req~utrements, it is~ 15 worth-reminding that during the reaction stage; the whole content of the tan~ is normally thoroughly mixed so that the liquor becomes homogeneous. There~ore, the solids are put in suspension and can enter the decanter device if the same simply consists o~ a hollow pipe or trough leading out of the tank.
During the settling stage, the solid~ particles that have already entered the decanter devi~e settle within~
the device and thus become trapped inside. When the decante} device is operated to remove the supernatant liquid, the so-t}apped solids are then ~lushed out o~ the tank, thereby greatly reducing the general performance of the process.
To avoid such a problem, three solutions have been proposed up to now.
The first solution consists in providing the decanter device with at least one gravity solids drainage opening. This opening is formed by inclined partitions merging together towards the bottom of the reactor. Such an opening can be used to withdraw the supernatant liquid as ., .
. . , : .
::
:. :, :.
:
~.
' :. : ' .
,. ~ :
200~9~3 well as to drain the solids. The major inconveniences attributed to such a decanter are as follow.
First of all, keeping in mind that a high hydraulic capacity is a must to keep the productivity to its maximum, one can see that there is a real danger of disturbing the settled solids at the bottom of tank with such a decanter, where the supernatant li~uid withdrawal orientation is toward from the bottom of the reactor. As a result, operation of such a device is limited, particularly if the decanter device is fixed and already submerged submerged at the desired low water level of the reactor.
Secondly, such a device does not prevent solids from penetrating. I~ solids are free to ~enetrate the decan~er device, they must also be evacuated prior to operating the decanter. Some mechanical devices may succeed in doing a reasonable job but such mechanical devices must be checked regularly and maintained in proprer order. A
ceEtain limitation of success is thus existing when using this ty~e of device.
2~ A second solution that has been proposed to solve the above mentioned problem consists in using a decanter device of the same type as above, and partially seaLing the downward openingts) of this decanter device, using an air-lock to do so.
With such a design approach, a downward inclined partition opening is still used to withdraw the supernatant liquid and/or drain solids. The opening is however closed by an atmospheric air trap or lock that can be created by introduction of air in the pipe at the end of a decanting cycle or by a controlled vent line using a solenoid valve (see Canadian patent No. 1,249,228 to Mikkle Mandt).
The disavantages of this second solution are as follow:
- One again, it involves downward orientation of ..... .
20~9~3 the supernatant liquid withdrawal.
- Some solids can penetrate within of the air lock portion of the decanter and may be drained back prior to the decanting stage.
- Air-trap seals are always subject to failure and may well suffer slow leaks. This may become critical particularly if not used f~equently. Also, in the absence of proper heater/defrost system, ice formation in the vent line can be a serious source o~ problems.
- The regulation opening must be in the ~orm o~ a long narrow opening inside the unit. As proper head loss is critical to withdraw the liquid uniformly, a very narrow openin~ is used and represents al po~entia~l ~logging/
maintenance problem. The narrow openin~ is; no,t aceessible as it must be built inside the un~it.
- The unit must be built air tight and/watertight and thus is expensive to build. It is normally built in moulde~ ~iberglass OE stainless steel and its sealing, inte~Etty must be periodically re-checke~.
2~ ~ thi~d solution that has bee~ propose~ so far to solve the a~bove mentioned; problem eonsists in designing the~
decanter device in such a manner that its inlet openings can be positioned completely out of the water so that it becomes impossible for any water/solids to penetrate during the reaction stage.
This solution is the most efficient and safe but requires serious mechanical involvements and thus quite complicated structure at the end.
OBJECT AND SUMMARY OF THE INVENTION
An object of the present invention is to provide a new decanter device which overcomes all the drawbacks of the existing devices as explaned hereinabove. More parti-... ~.....
: , ,1 ~o~
cularly, the invention proposes a new decanter device which incorporates positive seal means to close its inlet openings so that no water/solids can penetrate during the reaction stage.
S ~nother object of the invention is also to provide a new decanter device which allows efficient decantation in a reactor tank while being much less expensive to manu-factuEe and to maintain than most of the e~isting devices.
In accordance with the invention, -these objects aEe aehieved with a decanter device foE use to remove supernatant liquid from a tan~ containing a mixture of liguid~ of diff;erent densities~ ~E~ u~id, and so].id ~aEtieles t~ be~sepaEa~ted, which device eor~pElses:
- a. pe~forated pipe. mounte~ riside the tank, the pipe compEising a plurality of inlets. lni the form of small oEifices, positionedl along the pipei and Qpening into the tank, and at least one outlet leading out of the tan~;
- an inflatable membrane mounted inside the pipe in such ài manner as to exten~ oveE the srnalt. oElf~ces and 20~ thus sea~ingly close the lnlets: of the p!ipe when~ the membrane is inflated, and to extend awaly fEom, t~ese small apeEtures and a~ay from the pipe outl;et to a~ w supeEnatant liquid to flow out of the tan~ throu~h this pipe when the membrane is not inflated; and - means foE inflating the membrane whenever desired In accordance with a preferred~ embodir~ent o~ the invention, the inflatable membrane i9 in the form of at least one elongated balloon extending along the pipe inside the same, and the means for inflating the membrane comprises a source of air or water under pressure operatively connected to each balloon in order to blow it up whenever desired to close the small orifices and thus seal the decanter device.
., .~ ", ~,. . .
.
;~()0~9~
In accordance with another embodiment of the invention, the pipe extends horizontally inside said tank and the small orifices provided in the pipe are opening upwardly. Moreover, means may be provided for adjusting the height level position of the pipe inside the tank.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention, the way it works and its numerous advantages will be better understood upon reading of the following non restrictive description of some preferred embodiments thereof, made with reference to the accompagning drawings in which:
Fig. 1 is a cr~ss-sectional plan view of a decanter device accor~ing to a first embodiment of the invention;
Fig. 2 is a cross-sectional plan view of a decanteE device accoEdin~ to a second embodiment of the invention;
20Fi~. ~ iS a si~e elevation, cross-sectional view of the right end of the devices shown in Figs. 1 and 2;
Fig. 4 is top ~lan view of ai decanter device according to a third embodiment of the invention, which is of the floating type;
25Fig. 5 is a ~ront elevational view of the device shown in Fig. 4;
Fig. 6 is a sidie elevation view of the device shown in Figs ~ and 5; and Fig. 7 is a front elevational view of a decanter device according to a fourth embodiment of the invention, which can be of the fixed or floating type and is connected to an effluent pump.
.ii, ......
.
~. .
,: .,~ .....
~o~
GENERAL DESCRIPTION OF TI~E INVENTION
The decanter device 1 according to the first embodiment of the inven-tion as shown in Figs. 1 and 3 is inten-ded to be used to remove supernatant liquid from a tank contai-ning a mixture of liquids of different densities or of liquid and solid particles to be separated. The device 1 comprises a perforated pipe 5 made of a standard corrosion resistant ma-terial such as polyethylene or stainless s-teel. The pipe 5 ex-tends horizontally on a wall support 9 located within the tank 3 at proper level to allow supernatant liquid gravity withdrawal As shown in Fig. 3, the pipe 5 may be mounted to the support 9 by means of steel saddles 11 and adjusta~le threaded studs ~3 The perforated pipe 5 comprises a plurality of inlets in the form of small calibrated orifices 15 positioned alon~
its wall. As clearly shown, the orifices 15 are aligned and regularly spaced apal~t along the pipe 5. The orifices are also upwardly oriented with their axes e~tending from 0 to 89~, pre-ferably from 15 to 75~ and more preferably at about 45~ with respect to the horizontal.
The pipe 5 also comprises at least one outlet 17 lead-ing out of tank 3. In the embodiment shown in Fig. 1, this outlet 17 integrally extends from one opened end 19 of the pipe 5 and is connected to an effluent discharge 21 by a flange 23.
The device 1 as shown in Figs. 1 and 3 also comprises an inflatable membrane in the form of an elongated balloon 25 made of plastic or rubber material, that extends along the pipe 5 inside the same. The balloon is sized to completely fill up the pipe when it is inflated.
This balloon 25 that can be described best as a specially designed pneumatic air chamber similar to the one used in certain vehicle tire, may be provided with two ;~, . y......
200~92~3 opened ends to be anchored at each end of the pipe 5.
However, as is shown in Fig. 1, the balloon 25 is preferably provided with one opened end 27 only, its other end being closed or sealed depending on the decanter configuration.
The opened end of the balloon is sealingly connected to the other end 29 of the pipe which is closed by a blind flange 3l. Advantageously, the balloon 25 itsel~
may be used as a gasket as shown in Fig. 1 to seal the blind ~lange 31 to the end 29 of the pipe.
Inflating means are provided to blow up the balloon 25 inside the pipe 5 whenever desired. These means comprises a source of air OE water under pressure connected in a ~le~ible air or water pipe 33 and a steel or plastic hose adaptor 35 to an openin~ 37' provi~ed in the blind ~lange 31.
As can now be understood, actuation o~ the in~lating means causes admission o~ air or water undeE
pressure in the balloon 25~ and inflation o~ the ballooni.
Such an in~lation can be carried out to such an extendi that all the inlet orifices 15 o~ the pipe S are positively-ealed. Thus, the balloon act as a dia~hragm valve precluding any mixed 1iquid~solias ~rom entering the decanter device and/or to discharge out of the reactor.
As long as the inflation is maintainedj the liquor in the tank 3 is positively excluded from penetrating inside the pipe 5.
To operate the decanter, the pressure can simply be releasing by opening the pipe 33 to the atmosphere or connecting it to a vacuum pump.
This venting action rapidly collapses the balloon 25 inside the pipe 5 of the decanter 1, opening all its orifices 15 and thus allowing the supernatant liquid to penetrate .he pipe 5 and be subsequently evacuated from the reactor via the outlet 17 and discharge 21.
,.
9~3 It is worth mentioning that when the decanter 1 is so operated, it is always submerged in the liquid and the normal liquid submersion static pressure is sufficient to rapidly deflate (collapse) the membrane. It is also worth mentioning that the balloon 25 is anchored in such a way to the pipe 5 that it always remains in place (uniformly laid inside the decanter pipe body) while the supernatant liquid flows out, because the direction of flow is opposite from the balloon anchor point.
In accordance with a second embodiment Or the invention shown in Fig. 2, the device comprises two elongatea balloons 25,25' each opened at one end only. The pipe 5' is ~:-shaped and has two opposite ends 19 an~ 29 that are both close~ by blin~ f~an~es 31,31'. The ~ipe S also ~5 has a centEa~ opening 17 which acts as an outlet. The opene~ ends o~ the balloons are sealingly connected ~ the closed ends 19,~9 of the pipe 5 in the same manner as disclose~ heEeinabove.
Means are also pEovided for in~lating~ both balloon~. These means may be similar to those previously described e~cept that they need two flexible pipes 33,33' that have to extend from the pressure source to both ends 19 and 29 of the pipe 5 to inflate both balloons simul-taneously.
The following avantages are inherent of this invention:
1. It allows for upward flow withdrawal of the supe}natant liquid. As a result, no hydraulic effect is created toward the bottom of the tank 3 where the heavier but easily resuspendable material or solids are settled.
2. Because only upward flow withdrawal is carried out, the decanter device 1 can be mounted at a much deeper submersion without disturbing the sludge blanket. More, the decanter device 1 can be rigidly mounted instead of being ..
2 [)~)~9~
mounted on a complicated floating assembly. Such a mounting mode is simpler to fabricate, build and operate.
3. UniEorm withdrawal rates all across the en-tire length of the decanter device 1 are achieved. Such a 5 perfect flow regulation is very important and is posi-tively achieved by using calibEated orifices 15 well distributed and accessible over the entire length of the pipe 5.
BACKGROUND OF THE INVENTION
a) Field of the invention The present invention relates to a decanter device for use to withdraw supernatant liquid from a tank containing a mixture of liquids of different densities or a mix-ture of a liquid and solid particles to be separated.
b) Description of the Prior Art Decanter devices o~ different structures are presently known and commonly used in the wastewater treatment industry to decant supernatant liquid from a tank OE reseEvoi~N usually called "reactor", containing a liquor to be processe~, consisting of a mixture of liquids of different ~ensities or a mixture of a 1iquid and solid partic1es.
The biologica1 wastewater treatments which are carried out in ~he }eactor, usually involve meehanical, biological, physical and/o} chemical reactlons and~or 2~ processings which Eesult in an homogeneous mixin~ of the processed liquor. AfteE suffieient }ea¢tioM tim2, it is often necessary to separate the liquids andlor solids. Such a separation is normally done by allowinglthe mixture to sediment by gravity. To achieve such a sedimentation, mixing is simply interrupted for a period of time sufficient to allow for gravity separation to OCCUE withln the liquor.
- Then, the denser OE heavier liquid or particles slowly deposit at the bottom of the reactor while the lighter or clearer liquid "moves" up to the surface, e.g. on top of the sediments, where it forms a supernatant liquid solution that can be decanted (e.g. removed) from the reactor through a pipe known as a "decanter device" leading out of the reactor and having at least one opening so located in the reactor as to enable withdrawing of the supernatant liquid.
,, ... .
- -' ' 9~8 As aforesaid, decanter devices of many kinds have been designed and are presen-tly used -to remove supernatant liquid solutions from reactors, especially from those used for carrying out the municipal and industrial wastewater treatment process known as "sequential batch reactor (SBR) treatment processes".
Considering that most applications, especially in SBR processes, require improved performances to cope with the continuous superior requirements for supernatant quality in terms of separation and suspended sollds content, the decante~ device to be used in the reacto~ tank must be very efficient and must satisfy several very specific re~irements.
To bette} understand such req~utrements, it is~ 15 worth-reminding that during the reaction stage; the whole content of the tan~ is normally thoroughly mixed so that the liquor becomes homogeneous. There~ore, the solids are put in suspension and can enter the decanter device if the same simply consists o~ a hollow pipe or trough leading out of the tank.
During the settling stage, the solid~ particles that have already entered the decanter devi~e settle within~
the device and thus become trapped inside. When the decante} device is operated to remove the supernatant liquid, the so-t}apped solids are then ~lushed out o~ the tank, thereby greatly reducing the general performance of the process.
To avoid such a problem, three solutions have been proposed up to now.
The first solution consists in providing the decanter device with at least one gravity solids drainage opening. This opening is formed by inclined partitions merging together towards the bottom of the reactor. Such an opening can be used to withdraw the supernatant liquid as ., .
. . , : .
::
:. :, :.
:
~.
' :. : ' .
,. ~ :
200~9~3 well as to drain the solids. The major inconveniences attributed to such a decanter are as follow.
First of all, keeping in mind that a high hydraulic capacity is a must to keep the productivity to its maximum, one can see that there is a real danger of disturbing the settled solids at the bottom of tank with such a decanter, where the supernatant li~uid withdrawal orientation is toward from the bottom of the reactor. As a result, operation of such a device is limited, particularly if the decanter device is fixed and already submerged submerged at the desired low water level of the reactor.
Secondly, such a device does not prevent solids from penetrating. I~ solids are free to ~enetrate the decan~er device, they must also be evacuated prior to operating the decanter. Some mechanical devices may succeed in doing a reasonable job but such mechanical devices must be checked regularly and maintained in proprer order. A
ceEtain limitation of success is thus existing when using this ty~e of device.
2~ A second solution that has been proposed to solve the above mentioned problem consists in using a decanter device of the same type as above, and partially seaLing the downward openingts) of this decanter device, using an air-lock to do so.
With such a design approach, a downward inclined partition opening is still used to withdraw the supernatant liquid and/or drain solids. The opening is however closed by an atmospheric air trap or lock that can be created by introduction of air in the pipe at the end of a decanting cycle or by a controlled vent line using a solenoid valve (see Canadian patent No. 1,249,228 to Mikkle Mandt).
The disavantages of this second solution are as follow:
- One again, it involves downward orientation of ..... .
20~9~3 the supernatant liquid withdrawal.
- Some solids can penetrate within of the air lock portion of the decanter and may be drained back prior to the decanting stage.
- Air-trap seals are always subject to failure and may well suffer slow leaks. This may become critical particularly if not used f~equently. Also, in the absence of proper heater/defrost system, ice formation in the vent line can be a serious source o~ problems.
- The regulation opening must be in the ~orm o~ a long narrow opening inside the unit. As proper head loss is critical to withdraw the liquid uniformly, a very narrow openin~ is used and represents al po~entia~l ~logging/
maintenance problem. The narrow openin~ is; no,t aceessible as it must be built inside the un~it.
- The unit must be built air tight and/watertight and thus is expensive to build. It is normally built in moulde~ ~iberglass OE stainless steel and its sealing, inte~Etty must be periodically re-checke~.
2~ ~ thi~d solution that has bee~ propose~ so far to solve the a~bove mentioned; problem eonsists in designing the~
decanter device in such a manner that its inlet openings can be positioned completely out of the water so that it becomes impossible for any water/solids to penetrate during the reaction stage.
This solution is the most efficient and safe but requires serious mechanical involvements and thus quite complicated structure at the end.
OBJECT AND SUMMARY OF THE INVENTION
An object of the present invention is to provide a new decanter device which overcomes all the drawbacks of the existing devices as explaned hereinabove. More parti-... ~.....
: , ,1 ~o~
cularly, the invention proposes a new decanter device which incorporates positive seal means to close its inlet openings so that no water/solids can penetrate during the reaction stage.
S ~nother object of the invention is also to provide a new decanter device which allows efficient decantation in a reactor tank while being much less expensive to manu-factuEe and to maintain than most of the e~isting devices.
In accordance with the invention, -these objects aEe aehieved with a decanter device foE use to remove supernatant liquid from a tan~ containing a mixture of liguid~ of diff;erent densities~ ~E~ u~id, and so].id ~aEtieles t~ be~sepaEa~ted, which device eor~pElses:
- a. pe~forated pipe. mounte~ riside the tank, the pipe compEising a plurality of inlets. lni the form of small oEifices, positionedl along the pipei and Qpening into the tank, and at least one outlet leading out of the tan~;
- an inflatable membrane mounted inside the pipe in such ài manner as to exten~ oveE the srnalt. oElf~ces and 20~ thus sea~ingly close the lnlets: of the p!ipe when~ the membrane is inflated, and to extend awaly fEom, t~ese small apeEtures and a~ay from the pipe outl;et to a~ w supeEnatant liquid to flow out of the tan~ throu~h this pipe when the membrane is not inflated; and - means foE inflating the membrane whenever desired In accordance with a preferred~ embodir~ent o~ the invention, the inflatable membrane i9 in the form of at least one elongated balloon extending along the pipe inside the same, and the means for inflating the membrane comprises a source of air or water under pressure operatively connected to each balloon in order to blow it up whenever desired to close the small orifices and thus seal the decanter device.
., .~ ", ~,. . .
.
;~()0~9~
In accordance with another embodiment of the invention, the pipe extends horizontally inside said tank and the small orifices provided in the pipe are opening upwardly. Moreover, means may be provided for adjusting the height level position of the pipe inside the tank.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention, the way it works and its numerous advantages will be better understood upon reading of the following non restrictive description of some preferred embodiments thereof, made with reference to the accompagning drawings in which:
Fig. 1 is a cr~ss-sectional plan view of a decanter device accor~ing to a first embodiment of the invention;
Fig. 2 is a cross-sectional plan view of a decanteE device accoEdin~ to a second embodiment of the invention;
20Fi~. ~ iS a si~e elevation, cross-sectional view of the right end of the devices shown in Figs. 1 and 2;
Fig. 4 is top ~lan view of ai decanter device according to a third embodiment of the invention, which is of the floating type;
25Fig. 5 is a ~ront elevational view of the device shown in Fig. 4;
Fig. 6 is a sidie elevation view of the device shown in Figs ~ and 5; and Fig. 7 is a front elevational view of a decanter device according to a fourth embodiment of the invention, which can be of the fixed or floating type and is connected to an effluent pump.
.ii, ......
.
~. .
,: .,~ .....
~o~
GENERAL DESCRIPTION OF TI~E INVENTION
The decanter device 1 according to the first embodiment of the inven-tion as shown in Figs. 1 and 3 is inten-ded to be used to remove supernatant liquid from a tank contai-ning a mixture of liquids of different densities or of liquid and solid particles to be separated. The device 1 comprises a perforated pipe 5 made of a standard corrosion resistant ma-terial such as polyethylene or stainless s-teel. The pipe 5 ex-tends horizontally on a wall support 9 located within the tank 3 at proper level to allow supernatant liquid gravity withdrawal As shown in Fig. 3, the pipe 5 may be mounted to the support 9 by means of steel saddles 11 and adjusta~le threaded studs ~3 The perforated pipe 5 comprises a plurality of inlets in the form of small calibrated orifices 15 positioned alon~
its wall. As clearly shown, the orifices 15 are aligned and regularly spaced apal~t along the pipe 5. The orifices are also upwardly oriented with their axes e~tending from 0 to 89~, pre-ferably from 15 to 75~ and more preferably at about 45~ with respect to the horizontal.
The pipe 5 also comprises at least one outlet 17 lead-ing out of tank 3. In the embodiment shown in Fig. 1, this outlet 17 integrally extends from one opened end 19 of the pipe 5 and is connected to an effluent discharge 21 by a flange 23.
The device 1 as shown in Figs. 1 and 3 also comprises an inflatable membrane in the form of an elongated balloon 25 made of plastic or rubber material, that extends along the pipe 5 inside the same. The balloon is sized to completely fill up the pipe when it is inflated.
This balloon 25 that can be described best as a specially designed pneumatic air chamber similar to the one used in certain vehicle tire, may be provided with two ;~, . y......
200~92~3 opened ends to be anchored at each end of the pipe 5.
However, as is shown in Fig. 1, the balloon 25 is preferably provided with one opened end 27 only, its other end being closed or sealed depending on the decanter configuration.
The opened end of the balloon is sealingly connected to the other end 29 of the pipe which is closed by a blind flange 3l. Advantageously, the balloon 25 itsel~
may be used as a gasket as shown in Fig. 1 to seal the blind ~lange 31 to the end 29 of the pipe.
Inflating means are provided to blow up the balloon 25 inside the pipe 5 whenever desired. These means comprises a source of air OE water under pressure connected in a ~le~ible air or water pipe 33 and a steel or plastic hose adaptor 35 to an openin~ 37' provi~ed in the blind ~lange 31.
As can now be understood, actuation o~ the in~lating means causes admission o~ air or water undeE
pressure in the balloon 25~ and inflation o~ the ballooni.
Such an in~lation can be carried out to such an extendi that all the inlet orifices 15 o~ the pipe S are positively-ealed. Thus, the balloon act as a dia~hragm valve precluding any mixed 1iquid~solias ~rom entering the decanter device and/or to discharge out of the reactor.
As long as the inflation is maintainedj the liquor in the tank 3 is positively excluded from penetrating inside the pipe 5.
To operate the decanter, the pressure can simply be releasing by opening the pipe 33 to the atmosphere or connecting it to a vacuum pump.
This venting action rapidly collapses the balloon 25 inside the pipe 5 of the decanter 1, opening all its orifices 15 and thus allowing the supernatant liquid to penetrate .he pipe 5 and be subsequently evacuated from the reactor via the outlet 17 and discharge 21.
,.
9~3 It is worth mentioning that when the decanter 1 is so operated, it is always submerged in the liquid and the normal liquid submersion static pressure is sufficient to rapidly deflate (collapse) the membrane. It is also worth mentioning that the balloon 25 is anchored in such a way to the pipe 5 that it always remains in place (uniformly laid inside the decanter pipe body) while the supernatant liquid flows out, because the direction of flow is opposite from the balloon anchor point.
In accordance with a second embodiment Or the invention shown in Fig. 2, the device comprises two elongatea balloons 25,25' each opened at one end only. The pipe 5' is ~:-shaped and has two opposite ends 19 an~ 29 that are both close~ by blin~ f~an~es 31,31'. The ~ipe S also ~5 has a centEa~ opening 17 which acts as an outlet. The opene~ ends o~ the balloons are sealingly connected ~ the closed ends 19,~9 of the pipe 5 in the same manner as disclose~ heEeinabove.
Means are also pEovided for in~lating~ both balloon~. These means may be similar to those previously described e~cept that they need two flexible pipes 33,33' that have to extend from the pressure source to both ends 19 and 29 of the pipe 5 to inflate both balloons simul-taneously.
The following avantages are inherent of this invention:
1. It allows for upward flow withdrawal of the supe}natant liquid. As a result, no hydraulic effect is created toward the bottom of the tank 3 where the heavier but easily resuspendable material or solids are settled.
2. Because only upward flow withdrawal is carried out, the decanter device 1 can be mounted at a much deeper submersion without disturbing the sludge blanket. More, the decanter device 1 can be rigidly mounted instead of being ..
2 [)~)~9~
mounted on a complicated floating assembly. Such a mounting mode is simpler to fabricate, build and operate.
3. UniEorm withdrawal rates all across the en-tire length of the decanter device 1 are achieved. Such a 5 perfect flow regulation is very important and is posi-tively achieved by using calibEated orifices 15 well distributed and accessible over the entire length of the pipe 5.
4. The inlet orifices are not subject to clogging. Quite large callbEated orifices 15 ¢an be used lO without loosing good flow Eegulation ~ue to calculated head loss through the flow passages. Continuous long, narrow openings instead of calibrated~ laEge orifices (l to 2"
ty~ically)~ can be pEoblemat~ an~ cause o~cas~io~al clog~in~
thEouyh solid handling~, and can require malntenance in 15 addition to being subject to promo~e loweE peEfoEman~es.
ty~ically)~ can be pEoblemat~ an~ cause o~cas~io~al clog~in~
thEouyh solid handling~, and can require malntenance in 15 addition to being subject to promo~e loweE peEfoEman~es.
5. The decanteE device ~ a~lso ha~ a~ higher hydraulic capacity. As upward wlthdrawal is safeE, higher withdrawal rate can be achleye~ w~ithou~ soltds entEàinme~t~
So, largeE decanteE pipes 5 can b~ used with ~iggeE in~iet 2n orifices 15. This-a~l~ws faster withdrawa~l an~ thus increases treatment plant capacity.~
So, largeE decanteE pipes 5 can b~ used with ~iggeE in~iet 2n orifices 15. This-a~l~ws faster withdrawa~l an~ thus increases treatment plant capacity.~
6. No solid~ is wash-out with the~ su~ernatant liquid when the decanter device 1 is used, as soli~s are positively excluded from penetEating the pipe 5 at all 25 times.
~ . There is no scum OE floating solids entrainment. The water level can easily be controlled so that decanting is turned off before water le~el reaches the level of the inlet orifice 15. Even if the inlet orifices 30 reach the water level, the flow will be immediately interrupted as the orifices 15 will start to draw air be~ore any appreciable quantity of scum can penetrate inside the decanter pipe 5. Then, when re-in~1ating the membrane or balloon 25, inner solids/liquid will be essen-tialy expulsed .~
: , :
.
:
:~ -::
9~i3 from the pipe 5 by physical movement of the membrane gradually occupying all the inside space of the pipe 5.
8. The device 1 may also be used fo~ scum withdrawal. Tf required, when water level reaches about 2"
above the inlet orifices, the decanter can be used as a scum removal device. To achieve such a duty, the water level must be maintained at a proper valve (very close -to the orifices level) so that surface currents are generated entraining the floating solids inside the pipe S. Water level can be maintained ¢onstant by admitting water from a water source into the tank 3 (preferably treated water).
Scum removal may also be achieved by keeping the inlet oEifices 15 at the proper level ~close to water level) by using a float mechanism or slowl~ turning the pipe about its axis so that the orifices 15 follow the water level down ~or a sufficient period of time.
9. These is no need anymore for a large ef~1uent valve. Normally, large (8" up 30" ~) ef~1uent valves a~e used to control the gravi~y discharge of the decanteE.~
Because the device accordin~ to the invention is essentially a "diaphraym ope~ated valve", such larye control valves or questionable air lock devices aEe no longer necessary.
10. The decanter device 1 can be made floating.
Easy conversion o~ the fixed device 1 shown in Fig. 1 into a floating device can be achieved as shown in Figs. 4 to 6.
By using air as the inflatiny fluid, the pipe 5 can be designed to float using the air volume of the membrane only.
No additional floats or mechanism are necessary. As a matter of fact, the only additional elements that are guiding rails or bars 37 extending vertically from the supports 9 to force the pipe to remain in position during its ascension and a flexible outlet conduit 39 extending between the rigid outlet 17 of the pipe and the discharge connecting flange 23 to allow the pipe to move up and down.
, 2~ 9~
In such a floating mode, the posi-tion of the floating pipe 5 in the -tank 3 can be adjusted in such a manner that the inlet orifices 15 drilled close to the top of the pipe 5 are brought completely out of ~he liquid, i.e. moved up over the level of th:is liquid in the reactor, hence preventing any solid or liquid from penetrating inside the pipe S. Alternatively, the position of the floating pipe 5 can be adjusted so that the pipe 5 floats only to a certain level where the inlet orifices 15 that are maintained submerged and sealed by the balloon 25.
To achieve controlled floatation of the pipe 5, additional floats 41 as shown in Figs. 4 to 6 can be use~.
~uch floats 41 prevents the decanteE from sinkin~ readily under the liquor level once the balloon 25 is deflated. The floats 41 that are added allow to maintain the pipe 5 at constant submer~ence during the entire decantation sta~e of the process.
ll. The decanter device 1 may incorpoEate a pump 43 as shown in Fig. 7. Regardless if a ~i~ed or floatin~
decanter device is preferred, the pump 43 may be ~onnected to the outlet of t~e pipe 5 when ~ravity discharge is not possible. This pump 43 can be of sumbersible type or of a dry plt type.
I~ use is made of a submersible pump 43, a flexible section pipe 39 is recommended. The outlet of a flexible pipe 39 as disc~osed hereinabove can be connecte~
directly to the pump suction as in shown in Fig. 7 so that the pump can be readily retrieved from the water for inspection using a standard quick break-away pump discharge submerged connection and guide rail 45. This arrangement allow to conserve a perfect seal between the pump suction and the decanter pipe 5 during operation and service periods. The same flexible hose 39 of course also allows vertical movement of the device 1 i-f a combined floating/
.
, : :
'~
0~9~3 ~umped decanter device 1 is used as is shown in Fig. 7 12. The pipe 5 used in the device according -to the invention can be selected among a variety large of standard pipes available inall kind of material.
13. Operation of the decanter device 1 is very simple and can be readily understood by anyone.
14. Last of all, the device 1 according to the invention is rather inexpensive to build. Because it is made of readily available components, the device 1 can be built very inexpensively. ~y way of example a polyethylene pipe and a neoprene/rubber/ plastic membrane can be used to manufacture it. The pipe can also be replaced by another body of the same type, suc~ as a through or conduit o~ any shape.
The decanter device 1 according to the invention can be used wherever supernatant liquid must be removed from a tank as part of a process. Main applications can be enumerated as into:
- Oil separator tanks in the refiners industriest - Chemical solution ~anks in the chemical in~ustries;
- WateE and liquor tanks in the drinking and food industries;
- Water and other liquid tanks in the chemical/physical treatment industries; and - Water tank in the biological/physical treatment industries.
One of the preferred applications is certainly the separation of solids from a mixed biological liquor as intensively used to treat municipal and industrial wastewater. More particularly, the device according to the invention is capable of being applied into biological digesters where adjustment in the concentration of biological solids is achieved by decanting the supernatant i9~
water and subsequently adding more mixed liquor.
Another preferred application is in the biological waste treatment process known as Sequential Batch Reactor (SBR) process. In this process, the wastewater is treated 5 as a standard aerobic activated sludge but using sequential batch volumes to do so. Usually, several reactor tanks must be used if wastewater is to be handled in a continuous way, because the treatment process is occuring in a closed reac-tor e.g. with intermittent discharges only once the 10 biological trea-tment has been achieved. In such a SBR
process, large quantities of clear, treated water must be discharged quickly and efficiently out of each reactor tank at the end of each batch treatment or cycle, -thereby }equiring a specially designed decanter device.
As can be understood, the invention described he~einabove is particularly well designed to provide the best possible performance for such application into SBR.
~ i "~
: .
~ . There is no scum OE floating solids entrainment. The water level can easily be controlled so that decanting is turned off before water le~el reaches the level of the inlet orifice 15. Even if the inlet orifices 30 reach the water level, the flow will be immediately interrupted as the orifices 15 will start to draw air be~ore any appreciable quantity of scum can penetrate inside the decanter pipe 5. Then, when re-in~1ating the membrane or balloon 25, inner solids/liquid will be essen-tialy expulsed .~
: , :
.
:
:~ -::
9~i3 from the pipe 5 by physical movement of the membrane gradually occupying all the inside space of the pipe 5.
8. The device 1 may also be used fo~ scum withdrawal. Tf required, when water level reaches about 2"
above the inlet orifices, the decanter can be used as a scum removal device. To achieve such a duty, the water level must be maintained at a proper valve (very close -to the orifices level) so that surface currents are generated entraining the floating solids inside the pipe S. Water level can be maintained ¢onstant by admitting water from a water source into the tank 3 (preferably treated water).
Scum removal may also be achieved by keeping the inlet oEifices 15 at the proper level ~close to water level) by using a float mechanism or slowl~ turning the pipe about its axis so that the orifices 15 follow the water level down ~or a sufficient period of time.
9. These is no need anymore for a large ef~1uent valve. Normally, large (8" up 30" ~) ef~1uent valves a~e used to control the gravi~y discharge of the decanteE.~
Because the device accordin~ to the invention is essentially a "diaphraym ope~ated valve", such larye control valves or questionable air lock devices aEe no longer necessary.
10. The decanter device 1 can be made floating.
Easy conversion o~ the fixed device 1 shown in Fig. 1 into a floating device can be achieved as shown in Figs. 4 to 6.
By using air as the inflatiny fluid, the pipe 5 can be designed to float using the air volume of the membrane only.
No additional floats or mechanism are necessary. As a matter of fact, the only additional elements that are guiding rails or bars 37 extending vertically from the supports 9 to force the pipe to remain in position during its ascension and a flexible outlet conduit 39 extending between the rigid outlet 17 of the pipe and the discharge connecting flange 23 to allow the pipe to move up and down.
, 2~ 9~
In such a floating mode, the posi-tion of the floating pipe 5 in the -tank 3 can be adjusted in such a manner that the inlet orifices 15 drilled close to the top of the pipe 5 are brought completely out of ~he liquid, i.e. moved up over the level of th:is liquid in the reactor, hence preventing any solid or liquid from penetrating inside the pipe S. Alternatively, the position of the floating pipe 5 can be adjusted so that the pipe 5 floats only to a certain level where the inlet orifices 15 that are maintained submerged and sealed by the balloon 25.
To achieve controlled floatation of the pipe 5, additional floats 41 as shown in Figs. 4 to 6 can be use~.
~uch floats 41 prevents the decanteE from sinkin~ readily under the liquor level once the balloon 25 is deflated. The floats 41 that are added allow to maintain the pipe 5 at constant submer~ence during the entire decantation sta~e of the process.
ll. The decanter device 1 may incorpoEate a pump 43 as shown in Fig. 7. Regardless if a ~i~ed or floatin~
decanter device is preferred, the pump 43 may be ~onnected to the outlet of t~e pipe 5 when ~ravity discharge is not possible. This pump 43 can be of sumbersible type or of a dry plt type.
I~ use is made of a submersible pump 43, a flexible section pipe 39 is recommended. The outlet of a flexible pipe 39 as disc~osed hereinabove can be connecte~
directly to the pump suction as in shown in Fig. 7 so that the pump can be readily retrieved from the water for inspection using a standard quick break-away pump discharge submerged connection and guide rail 45. This arrangement allow to conserve a perfect seal between the pump suction and the decanter pipe 5 during operation and service periods. The same flexible hose 39 of course also allows vertical movement of the device 1 i-f a combined floating/
.
, : :
'~
0~9~3 ~umped decanter device 1 is used as is shown in Fig. 7 12. The pipe 5 used in the device according -to the invention can be selected among a variety large of standard pipes available inall kind of material.
13. Operation of the decanter device 1 is very simple and can be readily understood by anyone.
14. Last of all, the device 1 according to the invention is rather inexpensive to build. Because it is made of readily available components, the device 1 can be built very inexpensively. ~y way of example a polyethylene pipe and a neoprene/rubber/ plastic membrane can be used to manufacture it. The pipe can also be replaced by another body of the same type, suc~ as a through or conduit o~ any shape.
The decanter device 1 according to the invention can be used wherever supernatant liquid must be removed from a tank as part of a process. Main applications can be enumerated as into:
- Oil separator tanks in the refiners industriest - Chemical solution ~anks in the chemical in~ustries;
- WateE and liquor tanks in the drinking and food industries;
- Water and other liquid tanks in the chemical/physical treatment industries; and - Water tank in the biological/physical treatment industries.
One of the preferred applications is certainly the separation of solids from a mixed biological liquor as intensively used to treat municipal and industrial wastewater. More particularly, the device according to the invention is capable of being applied into biological digesters where adjustment in the concentration of biological solids is achieved by decanting the supernatant i9~
water and subsequently adding more mixed liquor.
Another preferred application is in the biological waste treatment process known as Sequential Batch Reactor (SBR) process. In this process, the wastewater is treated 5 as a standard aerobic activated sludge but using sequential batch volumes to do so. Usually, several reactor tanks must be used if wastewater is to be handled in a continuous way, because the treatment process is occuring in a closed reac-tor e.g. with intermittent discharges only once the 10 biological trea-tment has been achieved. In such a SBR
process, large quantities of clear, treated water must be discharged quickly and efficiently out of each reactor tank at the end of each batch treatment or cycle, -thereby }equiring a specially designed decanter device.
As can be understood, the invention described he~einabove is particularly well designed to provide the best possible performance for such application into SBR.
~ i "~
: .
Claims (7)
1. A decanter device for use to withdraw supernatant liquid from a tank containing a mixture of liquids of different densities or liquid and solid particles to be separated, said device comprises:
- a perforated pipe mounted inside the tank, said pipe comprising a plurality of inlets in the form of small orifices positioned along said pipe and opening into the tank, and at least one outlet leading out of said tank;
- an inflatable membrane mounted inside the pipe in such a manner as to extend over said small orifices and sealingly close the inlets of said pipe when said membrane is inflated, and to extend away from said small orifices and away from said at least one outlet to allow supernatant liquid to flow out of the tank through said this pipe when the membrane is not inflated; and - means for inflating the membrane whenever desired.
- a perforated pipe mounted inside the tank, said pipe comprising a plurality of inlets in the form of small orifices positioned along said pipe and opening into the tank, and at least one outlet leading out of said tank;
- an inflatable membrane mounted inside the pipe in such a manner as to extend over said small orifices and sealingly close the inlets of said pipe when said membrane is inflated, and to extend away from said small orifices and away from said at least one outlet to allow supernatant liquid to flow out of the tank through said this pipe when the membrane is not inflated; and - means for inflating the membrane whenever desired.
2. A decanter device as claimed in claim 1, wherein said inflatable membrane is in the form of at least one elongated balloon, extending along the pipe inside the same, and wherein said means for inflating said membrane comprises a source of air or water under pressure operatively connected to said at least one balloon in order to blow it up whenever desired, to close said small orifices.
3. A decanter device as claimed in claim 2, wherein said pipe extends horizontally within said tank, and wherein said small orifices provided in said pipe are upwardly oriented.
4. A decanter device as claimed in claim 2, wherein:
- said device comprises one elongated balloon exclusively;
- said elongated balloon is opened at one end only;
- said opened end of the balloon is sealingly connected to one closed end of said pipe;
- said pipe has another, opened end which acts as said outlet; and - said means for inflating said membrane further comprise an air or water pipe connecting said air or water source to an opening provided in said one closed end of said pipe.
- said device comprises one elongated balloon exclusively;
- said elongated balloon is opened at one end only;
- said opened end of the balloon is sealingly connected to one closed end of said pipe;
- said pipe has another, opened end which acts as said outlet; and - said means for inflating said membrane further comprise an air or water pipe connecting said air or water source to an opening provided in said one closed end of said pipe.
5. A decanter device as claimed in claim 4, wherein:
- said pipe extends horizontally within said tank;
- said other end of said pipe is sealingly connected to a flexible outlet extension leading out of said tank; and - said decanter device further comprises means for adjusting in height the position of said pipe inside said tank.
- said pipe extends horizontally within said tank;
- said other end of said pipe is sealingly connected to a flexible outlet extension leading out of said tank; and - said decanter device further comprises means for adjusting in height the position of said pipe inside said tank.
6. A decanter device as claimed in claim 2, wherein:
- said device comprises two elongated balloons;
- each of said balloons is opened at one end only;
- said pipe has two opposite closed ends and a central opening acting as said outlet;
- said opened ends of said balloons are sealingly connected to said closed ends of said pipe, respectively;
and - said means for inflating said membrane further comprise air or water pipes connecting said air or water source to openings provided in both of said closed ends of said pipe.
- said device comprises two elongated balloons;
- each of said balloons is opened at one end only;
- said pipe has two opposite closed ends and a central opening acting as said outlet;
- said opened ends of said balloons are sealingly connected to said closed ends of said pipe, respectively;
and - said means for inflating said membrane further comprise air or water pipes connecting said air or water source to openings provided in both of said closed ends of said pipe.
7. A decanter device as claimed in claim 6, wherein:
- said pipe extends horizontally inside said tank;
- said outlet opening of said pipe is sealingly connected to a flexible outlet extension leading out of said tank; and - said decanter device further comprises means for adjusting in height the position of said pipe inside said tank.
- said pipe extends horizontally inside said tank;
- said outlet opening of said pipe is sealingly connected to a flexible outlet extension leading out of said tank; and - said decanter device further comprises means for adjusting in height the position of said pipe inside said tank.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2006928 CA2006928C (en) | 1989-12-29 | 1989-12-29 | Decanter device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2006928 CA2006928C (en) | 1989-12-29 | 1989-12-29 | Decanter device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2006928A1 CA2006928A1 (en) | 1991-06-29 |
| CA2006928C true CA2006928C (en) | 1997-12-16 |
Family
ID=4143902
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2006928 Expired - Fee Related CA2006928C (en) | 1989-12-29 | 1989-12-29 | Decanter device |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2006928C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5888026A (en) * | 1997-01-24 | 1999-03-30 | Her Majesty The Queen In Right Of Canada, As Represented By The Minister Of Natural Resources | Backfill paste production facility and method and apparatus for producing high density slurry and paste backfills |
| US6168352B1 (en) | 1997-01-24 | 2001-01-02 | Her Majesty The Queen In Right Of Canada, As Represented By The Minister Of Natural Resources | Apparatus for producing high density slurry and paste backfills |
-
1989
- 1989-12-29 CA CA 2006928 patent/CA2006928C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CA2006928A1 (en) | 1991-06-29 |
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| MKLA | Lapsed |