CA1200927A - Arrangement for biological cleaning of water - Google Patents
Arrangement for biological cleaning of waterInfo
- Publication number
- CA1200927A CA1200927A CA000433348A CA433348A CA1200927A CA 1200927 A CA1200927 A CA 1200927A CA 000433348 A CA000433348 A CA 000433348A CA 433348 A CA433348 A CA 433348A CA 1200927 A CA1200927 A CA 1200927A
- Authority
- CA
- Canada
- Prior art keywords
- space
- arrangement
- activating
- separating
- separating space
- 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
- C02F3/1278—Provisions for mixing or aeration of the mixed liquor
- C02F3/1294—"Venturi" aeration means
-
- 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
-
- 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
- C02F3/28—Anaerobic digestion processes
-
- 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
- Life Sciences & Earth Sciences (AREA)
- Microbiology (AREA)
- Biodiversity & Conservation Biology (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Physical Water Treatments (AREA)
- Aeration Devices For Treatment Of Activated Polluted Sludge (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
Arrangement for biological cleaning of water comprising a container within which an activating space and at least a single separating space, separated from the activating space by an inclined wall, advantageously of conical shape are provided, which inclined wall passes over in its lower part to a return passage connecting both said spaces. A number of transfer channels are provided in the separating space above said inclined wall, the upper parts of these channels connected to the upper part of the activating space, the lower parts thereof opening into the lower part of the separating space. A gassing and/or mixing system is provided in the lower part of the activat-ing space.
Arrangement for biological cleaning of water comprising a container within which an activating space and at least a single separating space, separated from the activating space by an inclined wall, advantageously of conical shape are provided, which inclined wall passes over in its lower part to a return passage connecting both said spaces. A number of transfer channels are provided in the separating space above said inclined wall, the upper parts of these channels connected to the upper part of the activating space, the lower parts thereof opening into the lower part of the separating space. A gassing and/or mixing system is provided in the lower part of the activat-ing space.
Description
'7 The present invention relates to an arrangement for biological cleaning of water.
Compact arrangements for biological water cleaning combining in a common but internally subdivided container the biological activating process with a follow-ing separation of the activated sludge, where for separa-tion of the activated sludge the system of fluid filtration is used are more and more used. The technology of fluid filtration represents in the technology of biological water cleaning a substantial improvement. At some arrangements of this type however some drawbacks are appearing, worse-ning the results of water cleaning or reducing the capacity of the arrangement, possibly also requiring more attention.
These drawbacks are showing in an increased a amount of not dissolved materials in the outlet of the arrangement particularly when cleaning concentrated waste waters. It has been found that these drawbacks are in some cases originating due to an unsuitable transfer of the activating mixture from the activating space to the sepa-rating space. At these arrangements the separating spaceis separated from the activating space by at least one inclined partition wall with a transfer channel serving for transfer of the activated mixture from the activating space to the separating space formed by another inserted wall in order to protect the separating space sufficiently from the intensive streaming within the activating space and in order to distribute the supplied mixture uniformly in the g ~ ~
. ~
~,1 3~2~
Another function of -the transfer channel is the degassing of the activating mixture entering the separating space.
The activating mixture is at aerobic biological water cleaning oversaturated by nitrogen as due to the sub-stantial intensity of aeration required for a sufficient supply of oxygen and due to larger depths of submersion of the aeration system in the activating space a degree of nitrogen solved in the mixture is achieved corresponding the pressure determined by the depth of submersion. In conse-quence thereof in case the separa-ting space is situated above the activating space, the activating mixture is in the sepa-rating space oversaturated so that nitrogen is released even in the separating space, what is not welcomed.
At anaerobic biological water cleaning with gen-eration of biogas, the water is analogically oversaturated by generated gases, for instance by methane and carbon dioxide. In case the activating mixture oversatura-ted by gas enters the separating space, -the oversaturated gas sti.cks on the surface of sludge particles and part of the activated sludge is floating in consequence thereof. The flo-tation of sludge in the course of separation leads to an unwelcomed escape of flotated sludge into the off-take of cleaned water.
.At actual arrangements the degassing is in case of a higher oversaturation by gas not sufficiently effective with the result of the mentioned increase of no-t dissolved materials in the off-take, which of course as secondary result also reduces the parameters of cleaned water expressed in units BSK5 and C~iSK. This de-teriora-tion of the quality of water can attain also more than threefold the values which could be achieved without the dis-turbing influence of flo-ta-tion oE sludge.
The mentioned unwelcomed escape of sludge not only deteriorates the cluali-ty of cleaned water, but it also '~2~ 92l7 reduces the concentration of activa-ted sludge in the activation and thus also its proper efficiency.
Another drawbac]c of mentioned arrangements is the difficult accessibility of the transfer channel enabling in the course of opera-tion no cleaning or adjustment. In case of accidental choking of a part of the transfer channel a disturbance of the equilibrium of the supplied mix-ture into the separating space is created, due to which a distrubance of the required streaming in the separating space is gen erated, leading to a discharge of sludge from the separating space to the off-take and thus equally to an increase of not dissolved materials in the cleaned water. The impossibility of adjustmen-t of the throughflow over the transfer channel in the course of operation substantially reduces the pos-sibility to apply some kinds of effective aeration systems.
Another drawback of described arrangements is alsothe meeting of the stream of the activated mixture entering the separating space with the flow of separated sludge, returning from the separating into the activating space, what due to a damping of the return of the separated sludge limits the value of the maximum value of the material load of the surface in the separation and thus also the output of the whole arrangement~
Another drawback of actual arrangements is the dependence on the flow in the separation of -the flow in the activation, what equally limits the possibility of applica-tion of different types of aeration systems in -the arrange-ment. At actually known arrangements the flow in the separating space is substantially determined by the vertical flow in the activating space, generating a driving force for -the flow oE the ac-tiva-ting mixture and for -the return of concentrated ac-tivated sludge due to the pressure difference on the inlet and outlet of the separating space. That makes difficult any application of very efficient ~eration ~`~2~3~ 7 systems which generate a substantially horizontal flow in the activating space, particularly at larger heights of the arrangement.
The inserted wall of known arrangements forming with an inclined partition wall a transfer channel is due to its dimensions demanding on material and its mounting i5 relatively difficult.
It is an object of this invention to eliminate or at least to substantially reduce the mentioned draw-backs.
According to the present invention, there is provided an arrangement for biological water cleaning com-prising a container including an activating space and at least one separating space, separated from the activating space by at least one inclined partition wall for instance of conical shape, to the lower part of which a return pas-sage is joined, ccnnecting the separating space with the activating space, at least one transfer channel arranged abo~e said inclined partition wall in the separating space, the upper part of said transfer channel connected by its inlet to the upper part of the activating space, a gassing system provided in the activating space/ the lower part of the transfer channel terminating by an outlet in the lower part of the separating space.
The cross sectional area of flow of the transfer channel increases advantageously toward its outlet.
Preferably, the transfer channel is arranged directly on the inclined partition wall.
Preferably, the distribution of transfer channels is, for a good functionning and good efficiency, symmetri-cal with respect to the vertical axis of the container and their number is uneven.
An easy adjustment, access and assembling is achieved if the inlet of the transfer channel is at the ~t9t~
level o the surface in the activating space, including a regulating element arranged for instance directly on the inlet as an adjustable overflow, whereby the transfer channel can alternatively extend above the surface in the activating space, where it is provided with an opening.
In order to improve the functionning it is advantageous if the plane determined by the outlet of the transfer channel is vertical.
In order to improve the degassing ~ t~
- 4a -,.
:~2~D~ '7 flotation, a degassing insert, for instance a grid can be provided in the activating space in Eron-t of the inlet into the transfer channel.
Good parameters of -the arrangement can be obtained if the sum of throughflowing areas of regulating elements at the inlet of transfer channels form 0,05% to 2% oE the area of the surface in -the separating space and the sum of through-Elowing areas of the outlets of transfer channels form 4~ to-12~ oE the area of the surface of the separa-ting space.
Preferred embodimenks of -the arrangemen-t according to this invention are diagrammatically shown as examples in the attached drawings wherein:
Fig. 1 shows an arrangement with a single separating space and with a number of transfer channel in an axial sectional elevation, Fig. 2 the same arrangement in top view, Fig. 3 an arrangement with a number of separating spaces comprising a number of transfer channels in an axial sectional elevation, Fig. 4 the arrangement from Fig. 3 in top view, Fig. 5 an arrangement suitable for anaerobic cleaning of highly contaminated waste water in vertical sectional elevation.
The arrangement shown in Fig. 1 and 2 is suitable for aerobic cleaning of water. It is of the so called monobloc type, comprising a known activating space l for activation and an e~ually known separa-ting space 2 for fluid filtration in a single, in the case given cylindrical con-tainer with a mantle 3 and a bottom 4. The Separatillg space
Compact arrangements for biological water cleaning combining in a common but internally subdivided container the biological activating process with a follow-ing separation of the activated sludge, where for separa-tion of the activated sludge the system of fluid filtration is used are more and more used. The technology of fluid filtration represents in the technology of biological water cleaning a substantial improvement. At some arrangements of this type however some drawbacks are appearing, worse-ning the results of water cleaning or reducing the capacity of the arrangement, possibly also requiring more attention.
These drawbacks are showing in an increased a amount of not dissolved materials in the outlet of the arrangement particularly when cleaning concentrated waste waters. It has been found that these drawbacks are in some cases originating due to an unsuitable transfer of the activating mixture from the activating space to the sepa-rating space. At these arrangements the separating spaceis separated from the activating space by at least one inclined partition wall with a transfer channel serving for transfer of the activated mixture from the activating space to the separating space formed by another inserted wall in order to protect the separating space sufficiently from the intensive streaming within the activating space and in order to distribute the supplied mixture uniformly in the g ~ ~
. ~
~,1 3~2~
Another function of -the transfer channel is the degassing of the activating mixture entering the separating space.
The activating mixture is at aerobic biological water cleaning oversaturated by nitrogen as due to the sub-stantial intensity of aeration required for a sufficient supply of oxygen and due to larger depths of submersion of the aeration system in the activating space a degree of nitrogen solved in the mixture is achieved corresponding the pressure determined by the depth of submersion. In conse-quence thereof in case the separa-ting space is situated above the activating space, the activating mixture is in the sepa-rating space oversaturated so that nitrogen is released even in the separating space, what is not welcomed.
At anaerobic biological water cleaning with gen-eration of biogas, the water is analogically oversaturated by generated gases, for instance by methane and carbon dioxide. In case the activating mixture oversatura-ted by gas enters the separating space, -the oversaturated gas sti.cks on the surface of sludge particles and part of the activated sludge is floating in consequence thereof. The flo-tation of sludge in the course of separation leads to an unwelcomed escape of flotated sludge into the off-take of cleaned water.
.At actual arrangements the degassing is in case of a higher oversaturation by gas not sufficiently effective with the result of the mentioned increase of no-t dissolved materials in the off-take, which of course as secondary result also reduces the parameters of cleaned water expressed in units BSK5 and C~iSK. This de-teriora-tion of the quality of water can attain also more than threefold the values which could be achieved without the dis-turbing influence of flo-ta-tion oE sludge.
The mentioned unwelcomed escape of sludge not only deteriorates the cluali-ty of cleaned water, but it also '~2~ 92l7 reduces the concentration of activa-ted sludge in the activation and thus also its proper efficiency.
Another drawbac]c of mentioned arrangements is the difficult accessibility of the transfer channel enabling in the course of opera-tion no cleaning or adjustment. In case of accidental choking of a part of the transfer channel a disturbance of the equilibrium of the supplied mix-ture into the separating space is created, due to which a distrubance of the required streaming in the separating space is gen erated, leading to a discharge of sludge from the separating space to the off-take and thus equally to an increase of not dissolved materials in the cleaned water. The impossibility of adjustmen-t of the throughflow over the transfer channel in the course of operation substantially reduces the pos-sibility to apply some kinds of effective aeration systems.
Another drawback of described arrangements is alsothe meeting of the stream of the activated mixture entering the separating space with the flow of separated sludge, returning from the separating into the activating space, what due to a damping of the return of the separated sludge limits the value of the maximum value of the material load of the surface in the separation and thus also the output of the whole arrangement~
Another drawback of actual arrangements is the dependence on the flow in the separation of -the flow in the activation, what equally limits the possibility of applica-tion of different types of aeration systems in -the arrange-ment. At actually known arrangements the flow in the separating space is substantially determined by the vertical flow in the activating space, generating a driving force for -the flow oE the ac-tiva-ting mixture and for -the return of concentrated ac-tivated sludge due to the pressure difference on the inlet and outlet of the separating space. That makes difficult any application of very efficient ~eration ~`~2~3~ 7 systems which generate a substantially horizontal flow in the activating space, particularly at larger heights of the arrangement.
The inserted wall of known arrangements forming with an inclined partition wall a transfer channel is due to its dimensions demanding on material and its mounting i5 relatively difficult.
It is an object of this invention to eliminate or at least to substantially reduce the mentioned draw-backs.
According to the present invention, there is provided an arrangement for biological water cleaning com-prising a container including an activating space and at least one separating space, separated from the activating space by at least one inclined partition wall for instance of conical shape, to the lower part of which a return pas-sage is joined, ccnnecting the separating space with the activating space, at least one transfer channel arranged abo~e said inclined partition wall in the separating space, the upper part of said transfer channel connected by its inlet to the upper part of the activating space, a gassing system provided in the activating space/ the lower part of the transfer channel terminating by an outlet in the lower part of the separating space.
The cross sectional area of flow of the transfer channel increases advantageously toward its outlet.
Preferably, the transfer channel is arranged directly on the inclined partition wall.
Preferably, the distribution of transfer channels is, for a good functionning and good efficiency, symmetri-cal with respect to the vertical axis of the container and their number is uneven.
An easy adjustment, access and assembling is achieved if the inlet of the transfer channel is at the ~t9t~
level o the surface in the activating space, including a regulating element arranged for instance directly on the inlet as an adjustable overflow, whereby the transfer channel can alternatively extend above the surface in the activating space, where it is provided with an opening.
In order to improve the functionning it is advantageous if the plane determined by the outlet of the transfer channel is vertical.
In order to improve the degassing ~ t~
- 4a -,.
:~2~D~ '7 flotation, a degassing insert, for instance a grid can be provided in the activating space in Eron-t of the inlet into the transfer channel.
Good parameters of -the arrangement can be obtained if the sum of throughflowing areas of regulating elements at the inlet of transfer channels form 0,05% to 2% oE the area of the surface in -the separating space and the sum of through-Elowing areas of the outlets of transfer channels form 4~ to-12~ oE the area of the surface of the separa-ting space.
Preferred embodimenks of -the arrangemen-t according to this invention are diagrammatically shown as examples in the attached drawings wherein:
Fig. 1 shows an arrangement with a single separating space and with a number of transfer channel in an axial sectional elevation, Fig. 2 the same arrangement in top view, Fig. 3 an arrangement with a number of separating spaces comprising a number of transfer channels in an axial sectional elevation, Fig. 4 the arrangement from Fig. 3 in top view, Fig. 5 an arrangement suitable for anaerobic cleaning of highly contaminated waste water in vertical sectional elevation.
The arrangement shown in Fig. 1 and 2 is suitable for aerobic cleaning of water. It is of the so called monobloc type, comprising a known activating space l for activation and an e~ually known separa-ting space 2 for fluid filtration in a single, in the case given cylindrical con-tainer with a mantle 3 and a bottom 4. The Separatillg space
2 is separated from the ac-tivating space l by an inclined partition wall 5 of funnel shape, which passes over at the bottom into a return passage 6, having for ins-tance -the shape oE a c~lindrical mantle 7 joined to -the lower edge 8 of -the inclined parti-tion wall 5. The return passage 6 terminates 3L2~)~92'~
into the activa-ting space 1 above the bot-tom ~.
Transfer channels 9 are situated on -the partition wall 5 in the separating space 2. These transEer channels 9 have a throughflow cross sec~ion for instance of circular shape, which increases downwards and are provided in their upper part with an inlet 10 connected with the upper part of the activating space 1, aavantageously at the level of the surface 11 and terminate a-t the bottom by an outlet 12 opening into the separating space 2 above the lower edge 8 o the inclined partition wall 5 whereby the plane of the outlet 12 of the transfer channel 9 is vertical.
The level of the free surface 11 is common both for the liquid in the activating space 1 and in the separat-ing space 2. The outlets 12 of transfer channels 9 and the return passage 6 are, if viewed in a vertical projection, covered by a bubble collector 13 formed by a conical mantle 14 passing over in its top part to a cylindrical extension 15 extending above the surface 11, where below this surface 11 an off-take of flotated sludge is provided connected to a sludge removal 17 provided with a closure 18.
The inlets 10 of transfer channels 9 are provided with regulating elements, for instance of the shape of adjustable overflows 19 for adjustment of the throughflow area of the inlet 10.
The transfer channels 9 extend advantageously above the surface 11 and are provided with openings 20 enabling an easy access of the maintenance -to the adjustable overflow 19 and to the whole transfer channel 9.
The number of transfer channels 9 can be differ-ent; there are six at the described arrangement. It is however more advantageous iE an uneven number of transfer channels 9 .is provided, as their outlets 12 are not si-tuated directly against oppositely arranged outlets 12.
A collecting ring 21 with collecting openings 22 P~2'~
is situated in the upper p~rt of the separating space 2 directly below the level of the surface 11, represen-ting a subsurface off-take of cleaned wa-ter connected over a drain-ing conduit 23 and a known regulating overflow 24 wlth a storage container 33O Degassing elements 25, in -the case given of grid shape are advantageously provided in front of inl.ets 10 of transfer channels 9 in the top part of the activating space l.
The supply 26 of raw water terminates in the upper part oE the activating space 1. ~t the bottom 4 a conduit 27 for emptying of the arrangement is provided.
The acti.vating space l is provided with known gassing, in the case given aeration system comprising an air distributor 28 and aeration elements 29. The activating space 1 commu-nicates in its upper part with the free atmosphere overchimneys 30. An adjustable overflow 31 with an adjus-table ring 34 for taking~off surplus activated sludge connec-ted to a drain 32 arranged a-t the surface 11 in the activating space 1.
An arrangement for anaerobic cleaning of concen-trated waste water with generation of biogas, which is not shown in the drawings is arranged in the same way as the arrangement described on hand of Fig. 1 and 2 with the dif-ference, that the activa-ting space l is not aerated by air, but is mixed by biogas. ~-t this modification of the arrange-ment it is possible to utilize for distribution of biogas to the activating mixture the above mentioned aeration system connected -to a no-t shown blower, the suction side of which is connected to the chimney 30. The mixing of -the mixture can be provided by suitable mechanical means and for its required heating care has to be taken off.
The described arrangement opera-tes as follows.
Raw water is supplied to the s-torage container 40 and is pumped by a pump 37 over the supply 26 -to the activating 2~7 space 1.
In the alternative for activating cleaning of waste water the activating mixture is in -the activatiny space 1 intensively areated by the described gassing system comprising a distributor 28 and aeration elements 29, whereby an intensive flow of the activa-ting mixture in the vertical direction is generated.
In case concentrated waste waters are cleaned, where a large volume of the activating space 1 is required, the height of -the liquid columns therein at-tains even more than 10 m. In case of an intensive aeration of -the activat-iny Mixture, required in order to achieve the necessary amount of oxygen, a saturation of gases, particularly by nitrogen, possibly also by generated CO2 is achieved in the activated mixture, corresponding to the pressure in the lower part of the activating space 1.
Prior to entering transfer channels 9 over inlets 10, the activating mixture flows along the degassing inserts 25, where due to changes of pressure caused by changes of the speed of flow, a separation of excess dissolved gas takes place, whereby the oversaturation of the activating mixture is reduced.
Air used for aeration of the activating mixture is removed from -the closed activating space 1 by way of chimneys 30 situated above the surface 11. The inlets 10 of transfer channels 9 are, as has been already told, situated at the level of the surface 11. The magnitude of of the flow of the activa-ting mixture over transfer channels 9 is regulated by adjustment of the throughflow area oE the inle-t 10, both by the adjustable overflows 19 and also by -the height of the sur:Eace 11 adjustable by -the regulating over-Elow 2~1 on the ou-tle-t 23 of cleaned water from -the collect-ing ring 21. The regulation of -the throughflow through transfer channel.s 9 by changing the level o:E the sur:Eace 11 by the regulating overflow 2~ can be used a-t -the aera-tion system shown in Fig. 1.
The adjustable overflows 19 can be used Eor regulation of -the -throughflow in individual transfer chan-nels 9 in case of application of a so called unsymmetricalaeration system, as for instance with an in~ector 35 which is applied at the arrangement shown in Fig. 3 and 4 and which will be described later. The optimum throughflow through transfer channels 9 is twice to three times -the amount of wa-ter cleaned in the apparatus. A reduction or increase of this -throughflow reduces the efficiency of sepa-ration and the adjustment of the op-timum throughflow -through transfer channels 9 is for a correct functionning of the arrangement important.
The described arrangement according to this inven-tion enables an easy access of the maintenance to inlets 10 and their mentioned adjustment even in the course of opera-tion, what makes substan-tially easier the adjustmen-t of optimum conditions in -the course of operation.
The free surface 11 of the activation and the adjustable overflow 19 on inlets 10 of transfer channels 9 furthermore contribute to the separation of excess gas - by flow over overflows 19 - and thus to a removal of the over-saturation of the activating mixture, entering the separating space 2.
The intensive turbulence in the space above the degassing elements 25 due to the flow of air for aeration of the activating mixture, particles of gas, separated in the course of the degassing process are separated from sludge particles, whereby any sticking o-f gas bubbles on the surface o sludge particles is prevented and the sludge has no ten-dency for flotation.
The activating mixture en-ters over -transfer chan-nels 9 into the lower part of the separating space 2 and in g 2~7 case of a change of -the direction of Elow at -the ou-tlet 12 from the transfer channel 9 in the upward direc-ti.on once more a local acceleration of the flow takes place with a possibility of separation of residual gas in the activa-ting mixture. In the course of passage of the activa-ting mixture through the separating space 2 the separation of activated sludge from cleaned water by filtration in the fluid filtra-tion layer is accomplished. The cleaned water is ta]cen o-ff by the collec-ting ring 21, over the draining condui-t 23 and the regulating overflow 24.
The activated sludge retained in the separating space 2 forms a fluid fil-tration layer which re-tains by filtration further activated sludge en-tering -the separating space 2.
Due to widening of the throughflow cross section of the separa-ting space 2 upwards, the flow lines of water in the separating space 2 are inclined from the vertical line toward the inclined partition wall 5, what leads together with the action of gravitation forces on the fluid layer - to a gradual movement of particles of the fluid layer toward the inclined partition wall 5 and thus -to a thickening of the fluid layer at this lnclined partltion wall 5.
Due to this thickening, sinking thickened flows of concentrated activated sludge are generated along this incl.ined partition wall 5. These thickened flows are flowing on the inclined partition wall 5 around the transfer channels 9 up to -the return passage 6 whereby they are sitll more thiclcened in the course of this flow.
Due -to the described flow of the thickened sludge Erom the separating space 2 below the outlets 12 of transfer channels 9, the activa-ting mixture which is ~ust entering by way of these channels 9 is forced - due to ~he law of continuity - to flow upwards into the separating space 2 as
into the activa-ting space 1 above the bot-tom ~.
Transfer channels 9 are situated on -the partition wall 5 in the separating space 2. These transEer channels 9 have a throughflow cross sec~ion for instance of circular shape, which increases downwards and are provided in their upper part with an inlet 10 connected with the upper part of the activating space 1, aavantageously at the level of the surface 11 and terminate a-t the bottom by an outlet 12 opening into the separating space 2 above the lower edge 8 o the inclined partition wall 5 whereby the plane of the outlet 12 of the transfer channel 9 is vertical.
The level of the free surface 11 is common both for the liquid in the activating space 1 and in the separat-ing space 2. The outlets 12 of transfer channels 9 and the return passage 6 are, if viewed in a vertical projection, covered by a bubble collector 13 formed by a conical mantle 14 passing over in its top part to a cylindrical extension 15 extending above the surface 11, where below this surface 11 an off-take of flotated sludge is provided connected to a sludge removal 17 provided with a closure 18.
The inlets 10 of transfer channels 9 are provided with regulating elements, for instance of the shape of adjustable overflows 19 for adjustment of the throughflow area of the inlet 10.
The transfer channels 9 extend advantageously above the surface 11 and are provided with openings 20 enabling an easy access of the maintenance -to the adjustable overflow 19 and to the whole transfer channel 9.
The number of transfer channels 9 can be differ-ent; there are six at the described arrangement. It is however more advantageous iE an uneven number of transfer channels 9 .is provided, as their outlets 12 are not si-tuated directly against oppositely arranged outlets 12.
A collecting ring 21 with collecting openings 22 P~2'~
is situated in the upper p~rt of the separating space 2 directly below the level of the surface 11, represen-ting a subsurface off-take of cleaned wa-ter connected over a drain-ing conduit 23 and a known regulating overflow 24 wlth a storage container 33O Degassing elements 25, in -the case given of grid shape are advantageously provided in front of inl.ets 10 of transfer channels 9 in the top part of the activating space l.
The supply 26 of raw water terminates in the upper part oE the activating space 1. ~t the bottom 4 a conduit 27 for emptying of the arrangement is provided.
The acti.vating space l is provided with known gassing, in the case given aeration system comprising an air distributor 28 and aeration elements 29. The activating space 1 commu-nicates in its upper part with the free atmosphere overchimneys 30. An adjustable overflow 31 with an adjus-table ring 34 for taking~off surplus activated sludge connec-ted to a drain 32 arranged a-t the surface 11 in the activating space 1.
An arrangement for anaerobic cleaning of concen-trated waste water with generation of biogas, which is not shown in the drawings is arranged in the same way as the arrangement described on hand of Fig. 1 and 2 with the dif-ference, that the activa-ting space l is not aerated by air, but is mixed by biogas. ~-t this modification of the arrange-ment it is possible to utilize for distribution of biogas to the activating mixture the above mentioned aeration system connected -to a no-t shown blower, the suction side of which is connected to the chimney 30. The mixing of -the mixture can be provided by suitable mechanical means and for its required heating care has to be taken off.
The described arrangement opera-tes as follows.
Raw water is supplied to the s-torage container 40 and is pumped by a pump 37 over the supply 26 -to the activating 2~7 space 1.
In the alternative for activating cleaning of waste water the activating mixture is in -the activatiny space 1 intensively areated by the described gassing system comprising a distributor 28 and aeration elements 29, whereby an intensive flow of the activa-ting mixture in the vertical direction is generated.
In case concentrated waste waters are cleaned, where a large volume of the activating space 1 is required, the height of -the liquid columns therein at-tains even more than 10 m. In case of an intensive aeration of -the activat-iny Mixture, required in order to achieve the necessary amount of oxygen, a saturation of gases, particularly by nitrogen, possibly also by generated CO2 is achieved in the activated mixture, corresponding to the pressure in the lower part of the activating space 1.
Prior to entering transfer channels 9 over inlets 10, the activating mixture flows along the degassing inserts 25, where due to changes of pressure caused by changes of the speed of flow, a separation of excess dissolved gas takes place, whereby the oversaturation of the activating mixture is reduced.
Air used for aeration of the activating mixture is removed from -the closed activating space 1 by way of chimneys 30 situated above the surface 11. The inlets 10 of transfer channels 9 are, as has been already told, situated at the level of the surface 11. The magnitude of of the flow of the activa-ting mixture over transfer channels 9 is regulated by adjustment of the throughflow area oE the inle-t 10, both by the adjustable overflows 19 and also by -the height of the sur:Eace 11 adjustable by -the regulating over-Elow 2~1 on the ou-tle-t 23 of cleaned water from -the collect-ing ring 21. The regulation of -the throughflow through transfer channel.s 9 by changing the level o:E the sur:Eace 11 by the regulating overflow 2~ can be used a-t -the aera-tion system shown in Fig. 1.
The adjustable overflows 19 can be used Eor regulation of -the -throughflow in individual transfer chan-nels 9 in case of application of a so called unsymmetricalaeration system, as for instance with an in~ector 35 which is applied at the arrangement shown in Fig. 3 and 4 and which will be described later. The optimum throughflow through transfer channels 9 is twice to three times -the amount of wa-ter cleaned in the apparatus. A reduction or increase of this -throughflow reduces the efficiency of sepa-ration and the adjustment of the op-timum throughflow -through transfer channels 9 is for a correct functionning of the arrangement important.
The described arrangement according to this inven-tion enables an easy access of the maintenance to inlets 10 and their mentioned adjustment even in the course of opera-tion, what makes substan-tially easier the adjustmen-t of optimum conditions in -the course of operation.
The free surface 11 of the activation and the adjustable overflow 19 on inlets 10 of transfer channels 9 furthermore contribute to the separation of excess gas - by flow over overflows 19 - and thus to a removal of the over-saturation of the activating mixture, entering the separating space 2.
The intensive turbulence in the space above the degassing elements 25 due to the flow of air for aeration of the activating mixture, particles of gas, separated in the course of the degassing process are separated from sludge particles, whereby any sticking o-f gas bubbles on the surface o sludge particles is prevented and the sludge has no ten-dency for flotation.
The activating mixture en-ters over -transfer chan-nels 9 into the lower part of the separating space 2 and in g 2~7 case of a change of -the direction of Elow at -the ou-tlet 12 from the transfer channel 9 in the upward direc-ti.on once more a local acceleration of the flow takes place with a possibility of separation of residual gas in the activa-ting mixture. In the course of passage of the activa-ting mixture through the separating space 2 the separation of activated sludge from cleaned water by filtration in the fluid filtra-tion layer is accomplished. The cleaned water is ta]cen o-ff by the collec-ting ring 21, over the draining condui-t 23 and the regulating overflow 24.
The activated sludge retained in the separating space 2 forms a fluid fil-tration layer which re-tains by filtration further activated sludge en-tering -the separating space 2.
Due to widening of the throughflow cross section of the separa-ting space 2 upwards, the flow lines of water in the separating space 2 are inclined from the vertical line toward the inclined partition wall 5, what leads together with the action of gravitation forces on the fluid layer - to a gradual movement of particles of the fluid layer toward the inclined partition wall 5 and thus -to a thickening of the fluid layer at this lnclined partltion wall 5.
Due to this thickening, sinking thickened flows of concentrated activated sludge are generated along this incl.ined partition wall 5. These thickened flows are flowing on the inclined partition wall 5 around the transfer channels 9 up to -the return passage 6 whereby they are sitll more thiclcened in the course of this flow.
Due -to the described flow of the thickened sludge Erom the separating space 2 below the outlets 12 of transfer channels 9, the activa-ting mixture which is ~ust entering by way of these channels 9 is forced - due to ~he law of continuity - to flow upwards into the separating space 2 as
3~'~
previously men-tioned. Due to the described arrangement of the apparatus both these klnds of flow are sufficiently distinc-tl.y separated.
The mentioned thickened sludge flows over re-turn passage 6 back into the activating space 1. Due to differ-ence of speclfic weight of the entering activating mixture and the outflowing separated sludge a force is generated due to gravi-tation, which together with the throughflow of cleaned water through the whole arrangement generates the described :Elow -through the apparatus. I'he speed of Elowing of the activating mixture in the transfer channels 9 is thereby de-termined by this force and by the magni.tude of throughflow areas of adjustable overflows 19.
A certain speed of flow of the activating mix-ture in the transfer channels 9 is optimum for different kinds of waste waters. At a lower than optimum speed, the obtain-able limit of concentration of activated sludge in the activating space 1 is lower than the optimurn concentration.
At a higher than optimum speed, disturbances of the fluid filtra-tion layer due to induced :Elow start to show, in-creasing the unwelcomed escape of suspension into the off-take of cleaned water. The possibility of an easy adjus-t-ment of the optimum flow by means of adjustable overflows 19 is thus advantageous for achievement of -the maximum output of the arrangement at given conditions. As the gen-eration of the required flow in transfer channels 9, in the separating space 2 and in the return passage 6 is -together with the thickened flows from -the separating space 2 just suf:Eicient for crea-tion of the required Elow in transEer channels 9, no o-ther force acting on inlets 10 to transfer channels 9 and on the outle-t from -the return passage 6 is re~1ired. Therefore -the operation of separation does not depend Oll the flow in -the separating space 2, which is solely li.mited by the condition, not to generate a force acting ayainst the direction oE flow into ancl from tlle separating space 2. It is thus possible -to apply in -the activating space 1 differen-t methods of gassing with different kinds of flow.
In order -to retain some still possible flo-tating sludge - what can occur due to separation of gas particles on the surface of particles of ac-tiva-ted sludge in the course of passage of -the activating mixture over the outlet 12 of the transfer passage 9 - a bubble collector 13 is provided. The flotating sludge is in -the b~bble collector 13 taken off from i-ts upper part by the off-take 16 of Elotating sludge, the upper edge of which is situated below the level of the surface 11 and in case the closure 18 is opened, the flotated sludge is drained beyond the arrangement due to pressure of the water column above the edge of the off--take 16.
Due -to the degassing of the activating mixture and retaining of the flotating sludge, the tendency for flo-tation of sludge in the separating space 2 -to the surface of cleaned water is substantially reduced. Due to the subsur-face off-take of cleaned water by means of a submerged collecting ring 21, the escape of flotating sludge into the off-take is practically fully prevented. The surplus ac-ti-vated sludge is taken off by the ad~ustable overflow 31 either continually or intermitten-tly.
The result of the described arrangement is a reduc-tion oE the escape of the suspension of activated sludge into the off-take of cleaned water to a minimum, showing in the quality of cleaned wa-ter, particularly as expressed in values of not dissolved material :in units BSK5 and CIISIC~ As the eEEiciency of El-lid filtration, so far removal of no-t dis-solvecl material is concerned, in case -the disturbing influ-ences of flota-tion are eliminated - is very high, a high eEficiency of water cleaning can be achieved by -the described ~LZC~?~
solution.
This effect shows particularly in case highly concentrated waste wa-ters are cleaned in particularly hiyh column shaped apparatus with a large heigh-t o:E the ac-tivat-ing space, where -the oversaturation of the ac-tivating mix-ture at the level of the separating space is high and flota-tion due to separation of gas would achieve such values, that the escape of ac-tivated sludge would reduce its concentra-tion in the activating space and would thus substantially limit the proper cleaning process. The arrangemen-t of the appa-ratus according to -this invention is not only significant for the quality of cleaned water bu-t also for the possibility of uti.lizing this type of apparatus for column shaped arrange-ments which are in many cases very advantageous due -to low claims on the building si-te and reduced claim on power due to a higher efficiency of transfer o-f oxygen at larger heights of the activating space 1, where a minimum consumption of power is at a height of the activating space 1 around 15 m.
In addition to suppression of the flotation effect, the efficiency of separation by fluid fil-tration as already mentioned - depends on the uniform flowing in -the fluid fil-ter and on the intensity of return of -the collected activa-ted sludge from the separating space 2 back into the activating space 1. The transfer channels 9 secure a uniform supply of the activating mixture into the separating space 2 as their throughflow area is widening from the inlet 10 to their outlet 12 so that the speed of flow of the mixture is sub-sequently reduced and a sufficient magnitude of the through-flow area of the ou-tlet 12 secures a reduc-tion of -the flow speed oE the activating mixture to such an extent, tha-t no disturbing currents are induced in the fluid filter in the separatillg space 2 from -the activating space 1, which would reach the surface of the fluid fil-ter and would dis-turb it, what would show in an increased escaping of -the suspension into the off-take oE cleaned water. The uniform flow of the activating mixture into the separating space 2 is also suppor-ted by an uneven number of transfer channels 9 as it prevent a front collision of two curren-ts of opposite direc-tion from two opposite transfer channels 9 which would takeplace if an even number of these channels 9 would be used, where at a frontal collision there is a stronger inclination for generation of an induced flow in the separating space 2.
As example of a calculation of the flow and of forces in the separating space 2 the following calculation is presented.
Let up suppose that -the activating space 1 con-tains a mixture with activated sludge with a sludge index of50 ml.g with a concentration of 10 kg of dry substance for one m3. Let us furthermore suppose a thickening of sludge returned by the return passage 6 into the activating space 1 to a concentration of 15 kg dry substance for 1 m3 what is the maximum, determined by the sludye index. The differ-ence of pressure between the inlet 10 into the transfer channel 9 and the outlet Erom the return passage 6 which is caused by one me-ter of the column of the return channel amounts to 49 Newton/m2. For an overall heigh-t of this column for instance 2 m the pressure difference is 98 N/m2.
This pressure difference generates according to the equation of Bernoulli a flow of the activating mix-ture at a speed of 0,44 m/s. The regulating overflows have to be adjusted for this speed by the adjustable overflows 19.
If the supply of water in-to the apparatus amounts to Q m3/s, the off-take of cleaned water from the separating space 2 is in case of a s-tabilized operation the same if we suppose that at stabilized conditions -the same amount of sludge which enters the separating space 2 is returned to the activatlng space 1, the flow through the return passage 6 is at these condi-tions 2 ~, so tha-t -the overall passage '9~
through transfer channels 9 is 3 Q/s.
Let us furthermore suppose that the speed of the off-take of water at the surface of the separating space 2 is o,2 mm/s, then if -the speed at -the adjustable overflows 19 should be 0,44 m/s, the overall throughflow area of ad~ustable overflows 19 is equal to 0,136% of the magnitude of the surface of the separating space 2. In order to pre-vent creation of induced currents in the separating space 2 the actual flow speed at the outlets 12 of -transfer channels 9 has to be lower than 0,01 m/s. To -that a throughflow area of the outle-ts 12 larger than 6% of the magnitude of -the surface in -the separating space 2 is corresponding. The mentioned calculation is solely an example which should concretely demonstrate the function of the whole arrangement.
At other conditions and for other kinds of water the starting values of the calculation will be of course different. It is however possible to determine generally limits wi-thin which the critical values of -the arrangement should be in order to secure the correct functionning. These values are for the overall throughflow area of the regulating elemen-t 19 0,05% to 2% of the magnitude of the area of the surface in the separating space 2 and for the throughflow area of outlets 12 of transfer channels ~ 4% to 12% of the magnitude of the surface in the separating space 2.
A similar functionning has also the arrangement described on hand of Fig. 1 and 2 for anaerobic water clean-ing with produc-tion of biogas. At -this modification no aeration is used, but gas generated in the course of the anaerobic process is blown-in into -the activa-ting space 1.
The blowing-in of biogas has the task to maintain -the acti-vated sludge in suspension. The produced and blown-in biogas ls tllereaf-ter taken-off over chimneys 30 into a not silown storage con-tainer of biogas. For blowing-in biogas the same system can be applied as a-t the aerobic application for its 2~
distribution, i.e. the distributor 28 and aeration elements 29 including a not shown blower, connected to -the mentionecl storage container of biogas. In tha-t case the degassing inserts 25 in front of the inlets 10 of transfer channels 9 remove methane and CO2. Otherwise the operation of the arrangement - with exception of the different process - is substantially the same as in case of an aerobic water cleaning.
Fig. 3 and 4 show another embodiment of the ar-rang~ment accordincJ to this invention which is particularly suitable for aerobic cleaning of waste waters of larger capacity. The difference against the arrangement shown in Fig. l and 2 is the application of more than one separating space 2 with a common activating space 1 in a single arrange-ment and the application of another gassing system. At this arrangement seven separating spaces 2, situated in a single container with a mantle 3 are used. The design of separating spaces 2 is the same as the design of separating spaces according to Fig. l and 2.
Contrary to the arrangement as in Fig. l and 2 the surface 11 between the individual separating spaces 2 communicates wi-th the atmosphere. As the area of the sur-face 11 in the activating space 1 is here subs-tantially larger, the degassing of the activating mix-ture is at this surface sufficient and it is not necessary to install degassing inser-ts 25 in front o~ the inlets 10 into the transfer channels 9. ~s the activating space 1 is not closed, no chimneys 30 are required. Otherwise the arrange-ment is in the no-t described parts thereof -the same as at the arran~emen-t described above, i.e. the arrangement ac-cording to Fig. 1 and 2.
The gassing sys-tem, which has the function of hydraulic aeration comprises injectors 35 connec-ted both -to the pressure conduit 36 of raw wa-ter and -to air supplies 38 ~ J~ 7 which extend above the surf~ce ll.
The injectors 35 are provided in -the lower par-t of the activating space l in known Venturi -tubes 39 beyond the vertical axis of the arrangement so that they generate in operation a rising helical flow of the aerated activating mixture with local escape of air on the surface of the acti-vating space.
A known floating indicator 43 in a s-torage tank 40 controls a valve 45 of a -transfer conduit 46 in order to ma:Lntain the required level of -the surface 44 in the s-torage tank 40 of raw water.
The arrangemen-t shown in Fig. 3 and 4 operates as follows. Raw water enters over the supply 26 the storage tank 40 after having been previously mechanically cleaned.
The pump 37 pumps the raw wa-ter over the pressure conduit 36 into the injector 35 where the supplied water is mixed wi-th air sucked on over the air supply 38.
The used gassing system not only aerates the activating mixture in the activating space 1, but simulta-neously imparts a motion to it, which is utilized for main-tenance of the activated sludge in suspension and for homogenizing the whole content of the activating space 1.
The hydraulic aeration aggregate should advantageously create a movement as shown in Fig. 3 and 4 where a circulat-ing motion within the activating space l is obtained.
In order to remove the influence of local out-bursts of the aera-ted activating mixture on the surface ll on the flow in the -transfer channels 9, a corresponding adjustment of adjustable overflows 1~ on inlets lO can be used.
The off-take of cleaned water from individual separating spaces 2 can be adjus-ted by regula-ting overflows 24 Eor each separating spaces individually. Otherwise the Eunctionning of the arrangement according to Fig. 3 and 4 ~2(~S~
is the same as that of the arrangement shown ln Fig. 1 ancl 2.
Al-though the cylindrical shape of the mantle 3 of the container of the arrangement is advantageous bo~h from the point of view of construction and also of the flow in the activating space 1, the arrangement according to this invention is not limited to a circular shape of the con-tainer. Particularly in case of a pneumatic aerating sys-tem it is possible to situate the separating spaces in rectangular containers.
The arxangement according to this invention has a number of advantages. The inlets 10 of transfer channels 9 as adjustable overflows 19 on the surface 11 and an alter-native addition of degassing inserts 25 in front of these inserts 10 enables a perfec-t removal of the oversaturation by air from -the activa-ting mix-ture which enters the separat-ing space 2 and thus eliminates the flotation of particles of activated sludge in the separation even in case of a high intensity of aeration of the activation and the-application of a deeply submerged aeration system.
The easy accessibility of inlets 10 of transfer channels 9 enables in case of need their easy cleaning even in the course of operation and a prevention of possible failures.
The occurance of failures due to choking of the transfer system is furthermore limited by the described shape of transfer channels 9 the accessibility of the inlets 10 enables an easy adjustment of the throughflow through these channels in the course of operation, enabling thus both an easy adjustment of conditions of operation of the apparatus according -to requiremen-ts and also adjustment oE
a possible assyme-try of the flow in the activatin~ space 1 and the elimination of a deformation oE the surface due to mentioned local outbursts of the activating mixture. That ~26~ '7 enables to apply at the arrangement different aera-ting systems, what in turn not only lncreases the ~lexibility of the arrangement, but in case of application of an injec-tor 35 enables to achieve a high energetic efficiency of aeration and an advantageous application particularly a-t column type apparatus with a heigh-t of -the water column in the activating space more than 5 m.
The separation of the flow of the ac-tivating mix-ture entering -the separating space 2 and of the separated sludge returning from -this space increases -the maximum value of the surface load by material of the separation, increases the maximum value of the surface load by material of the separation and thus increases the capacity of the arrangement up to 30% according to conditions of cleaning.
The construction of transfer channel 9 furthermore transfers the carrying out of built-in elements from the diffucult accessible activating space 1 to -the easier acces-sible separating space 2 and thus simplifies the assembling of built-in elements.
Another simplification of assembling enables the possibility of application of whole prefabricated transfer channels 9 where in the course of assembling solely a packing in the region of the inlet 10 is required. The construction of transfer channels 9 reduces furthermore claims on material for their manufacture. As no further inserted wall has to be suspended on the inclined partition wall 5 in order to provide a transfer channel 9 which partition wall 5 has solely the task to separate bo-th working spaces 1 and 2, it is possible to reduce its weight to the maximum using thin-walled material, what -toyether with reduc-tion of claims on material for building transfer channels 9 reduces substan-tially the weight of all built-in elements of the appara-tus for biological water cleaning, enabling -thus the achievemen-t of substantial savings.
9~
The arrangement shown in Fig. 5 is suitable Eor anaerobic sep-ticization of organically highly contaminated waste waters with production of biogas. From the arrange-ment shown in Fig. 3 and 4 it differs in that it is closed by a cover 47. ~assing elements 29 connected by a connect-ing conduit 38 to a not shown blower, connected in turn to a no-t shown storage tank of generated biogas, into which the off-take ~8 of biogas is terminating, serve for mixing the mixture in -the activating space 1.
The arrangement is fur-thermore provided with hot water heating 49 connected to a not shown source of hot water, which is partly heated by the genera-ted biogas.
This arrangement operates as follows. Raw water en-ters over the pressure conduit 36 the activating ~pace 1 which is mixed pneumatically by means of biogas blown-in into the activating mixture by gassing elements 29. The activating mixture is additlonally heated by hot water heating ~9. The source of heat is part of biogas generated by the proper anaerobic process of methanogenesis. In the course of taking-off the activating mixture, anaerobic activated sludge is separated similarly as at the aerobic alternative and is automatically returned back to the activation. Thus the concentration of activated sludge in the activation is increased and consequen-tly also the pro-cess of anaerobic methanogenesis is intensified. Thisin-tensification has two consequences. Due to increase of the concentration of the activated sludge -the intensifica-tion of the process enables a reduction of the volume of anaerobic septification and thus also a reduction of the detention, what means in addition of reduc-tion of investment costs also a reduction of heat losses. The second conse-quence is in that the increased concentra-tion enables to process also less concentrated waste waters with less dry material, enlarging thus -the possibilities of utilization.
~2~U~
The off-take of cleaned water, of sludge and oE gas has to be provided with not shown water closures in order to secure the airtightness of the arrangement.
previously men-tioned. Due to the described arrangement of the apparatus both these klnds of flow are sufficiently distinc-tl.y separated.
The mentioned thickened sludge flows over re-turn passage 6 back into the activating space 1. Due to differ-ence of speclfic weight of the entering activating mixture and the outflowing separated sludge a force is generated due to gravi-tation, which together with the throughflow of cleaned water through the whole arrangement generates the described :Elow -through the apparatus. I'he speed of Elowing of the activating mixture in the transfer channels 9 is thereby de-termined by this force and by the magni.tude of throughflow areas of adjustable overflows 19.
A certain speed of flow of the activating mix-ture in the transfer channels 9 is optimum for different kinds of waste waters. At a lower than optimum speed, the obtain-able limit of concentration of activated sludge in the activating space 1 is lower than the optimurn concentration.
At a higher than optimum speed, disturbances of the fluid filtra-tion layer due to induced :Elow start to show, in-creasing the unwelcomed escape of suspension into the off-take of cleaned water. The possibility of an easy adjus-t-ment of the optimum flow by means of adjustable overflows 19 is thus advantageous for achievement of -the maximum output of the arrangement at given conditions. As the gen-eration of the required flow in transfer channels 9, in the separating space 2 and in the return passage 6 is -together with the thickened flows from -the separating space 2 just suf:Eicient for crea-tion of the required Elow in transEer channels 9, no o-ther force acting on inlets 10 to transfer channels 9 and on the outle-t from -the return passage 6 is re~1ired. Therefore -the operation of separation does not depend Oll the flow in -the separating space 2, which is solely li.mited by the condition, not to generate a force acting ayainst the direction oE flow into ancl from tlle separating space 2. It is thus possible -to apply in -the activating space 1 differen-t methods of gassing with different kinds of flow.
In order -to retain some still possible flo-tating sludge - what can occur due to separation of gas particles on the surface of particles of ac-tiva-ted sludge in the course of passage of -the activating mixture over the outlet 12 of the transfer passage 9 - a bubble collector 13 is provided. The flotating sludge is in -the b~bble collector 13 taken off from i-ts upper part by the off-take 16 of Elotating sludge, the upper edge of which is situated below the level of the surface 11 and in case the closure 18 is opened, the flotated sludge is drained beyond the arrangement due to pressure of the water column above the edge of the off--take 16.
Due -to the degassing of the activating mixture and retaining of the flotating sludge, the tendency for flo-tation of sludge in the separating space 2 -to the surface of cleaned water is substantially reduced. Due to the subsur-face off-take of cleaned water by means of a submerged collecting ring 21, the escape of flotating sludge into the off-take is practically fully prevented. The surplus ac-ti-vated sludge is taken off by the ad~ustable overflow 31 either continually or intermitten-tly.
The result of the described arrangement is a reduc-tion oE the escape of the suspension of activated sludge into the off-take of cleaned water to a minimum, showing in the quality of cleaned wa-ter, particularly as expressed in values of not dissolved material :in units BSK5 and CIISIC~ As the eEEiciency of El-lid filtration, so far removal of no-t dis-solvecl material is concerned, in case -the disturbing influ-ences of flota-tion are eliminated - is very high, a high eEficiency of water cleaning can be achieved by -the described ~LZC~?~
solution.
This effect shows particularly in case highly concentrated waste wa-ters are cleaned in particularly hiyh column shaped apparatus with a large heigh-t o:E the ac-tivat-ing space, where -the oversaturation of the ac-tivating mix-ture at the level of the separating space is high and flota-tion due to separation of gas would achieve such values, that the escape of ac-tivated sludge would reduce its concentra-tion in the activating space and would thus substantially limit the proper cleaning process. The arrangemen-t of the appa-ratus according to -this invention is not only significant for the quality of cleaned water bu-t also for the possibility of uti.lizing this type of apparatus for column shaped arrange-ments which are in many cases very advantageous due -to low claims on the building si-te and reduced claim on power due to a higher efficiency of transfer o-f oxygen at larger heights of the activating space 1, where a minimum consumption of power is at a height of the activating space 1 around 15 m.
In addition to suppression of the flotation effect, the efficiency of separation by fluid fil-tration as already mentioned - depends on the uniform flowing in -the fluid fil-ter and on the intensity of return of -the collected activa-ted sludge from the separating space 2 back into the activating space 1. The transfer channels 9 secure a uniform supply of the activating mixture into the separating space 2 as their throughflow area is widening from the inlet 10 to their outlet 12 so that the speed of flow of the mixture is sub-sequently reduced and a sufficient magnitude of the through-flow area of the ou-tlet 12 secures a reduc-tion of -the flow speed oE the activating mixture to such an extent, tha-t no disturbing currents are induced in the fluid filter in the separatillg space 2 from -the activating space 1, which would reach the surface of the fluid fil-ter and would dis-turb it, what would show in an increased escaping of -the suspension into the off-take oE cleaned water. The uniform flow of the activating mixture into the separating space 2 is also suppor-ted by an uneven number of transfer channels 9 as it prevent a front collision of two curren-ts of opposite direc-tion from two opposite transfer channels 9 which would takeplace if an even number of these channels 9 would be used, where at a frontal collision there is a stronger inclination for generation of an induced flow in the separating space 2.
As example of a calculation of the flow and of forces in the separating space 2 the following calculation is presented.
Let up suppose that -the activating space 1 con-tains a mixture with activated sludge with a sludge index of50 ml.g with a concentration of 10 kg of dry substance for one m3. Let us furthermore suppose a thickening of sludge returned by the return passage 6 into the activating space 1 to a concentration of 15 kg dry substance for 1 m3 what is the maximum, determined by the sludye index. The differ-ence of pressure between the inlet 10 into the transfer channel 9 and the outlet Erom the return passage 6 which is caused by one me-ter of the column of the return channel amounts to 49 Newton/m2. For an overall heigh-t of this column for instance 2 m the pressure difference is 98 N/m2.
This pressure difference generates according to the equation of Bernoulli a flow of the activating mix-ture at a speed of 0,44 m/s. The regulating overflows have to be adjusted for this speed by the adjustable overflows 19.
If the supply of water in-to the apparatus amounts to Q m3/s, the off-take of cleaned water from the separating space 2 is in case of a s-tabilized operation the same if we suppose that at stabilized conditions -the same amount of sludge which enters the separating space 2 is returned to the activatlng space 1, the flow through the return passage 6 is at these condi-tions 2 ~, so tha-t -the overall passage '9~
through transfer channels 9 is 3 Q/s.
Let us furthermore suppose that the speed of the off-take of water at the surface of the separating space 2 is o,2 mm/s, then if -the speed at -the adjustable overflows 19 should be 0,44 m/s, the overall throughflow area of ad~ustable overflows 19 is equal to 0,136% of the magnitude of the surface of the separating space 2. In order to pre-vent creation of induced currents in the separating space 2 the actual flow speed at the outlets 12 of -transfer channels 9 has to be lower than 0,01 m/s. To -that a throughflow area of the outle-ts 12 larger than 6% of the magnitude of -the surface in -the separating space 2 is corresponding. The mentioned calculation is solely an example which should concretely demonstrate the function of the whole arrangement.
At other conditions and for other kinds of water the starting values of the calculation will be of course different. It is however possible to determine generally limits wi-thin which the critical values of -the arrangement should be in order to secure the correct functionning. These values are for the overall throughflow area of the regulating elemen-t 19 0,05% to 2% of the magnitude of the area of the surface in the separating space 2 and for the throughflow area of outlets 12 of transfer channels ~ 4% to 12% of the magnitude of the surface in the separating space 2.
A similar functionning has also the arrangement described on hand of Fig. 1 and 2 for anaerobic water clean-ing with produc-tion of biogas. At -this modification no aeration is used, but gas generated in the course of the anaerobic process is blown-in into -the activa-ting space 1.
The blowing-in of biogas has the task to maintain -the acti-vated sludge in suspension. The produced and blown-in biogas ls tllereaf-ter taken-off over chimneys 30 into a not silown storage con-tainer of biogas. For blowing-in biogas the same system can be applied as a-t the aerobic application for its 2~
distribution, i.e. the distributor 28 and aeration elements 29 including a not shown blower, connected to -the mentionecl storage container of biogas. In tha-t case the degassing inserts 25 in front of the inlets 10 of transfer channels 9 remove methane and CO2. Otherwise the operation of the arrangement - with exception of the different process - is substantially the same as in case of an aerobic water cleaning.
Fig. 3 and 4 show another embodiment of the ar-rang~ment accordincJ to this invention which is particularly suitable for aerobic cleaning of waste waters of larger capacity. The difference against the arrangement shown in Fig. l and 2 is the application of more than one separating space 2 with a common activating space 1 in a single arrange-ment and the application of another gassing system. At this arrangement seven separating spaces 2, situated in a single container with a mantle 3 are used. The design of separating spaces 2 is the same as the design of separating spaces according to Fig. l and 2.
Contrary to the arrangement as in Fig. l and 2 the surface 11 between the individual separating spaces 2 communicates wi-th the atmosphere. As the area of the sur-face 11 in the activating space 1 is here subs-tantially larger, the degassing of the activating mix-ture is at this surface sufficient and it is not necessary to install degassing inser-ts 25 in front o~ the inlets 10 into the transfer channels 9. ~s the activating space 1 is not closed, no chimneys 30 are required. Otherwise the arrange-ment is in the no-t described parts thereof -the same as at the arran~emen-t described above, i.e. the arrangement ac-cording to Fig. 1 and 2.
The gassing sys-tem, which has the function of hydraulic aeration comprises injectors 35 connec-ted both -to the pressure conduit 36 of raw wa-ter and -to air supplies 38 ~ J~ 7 which extend above the surf~ce ll.
The injectors 35 are provided in -the lower par-t of the activating space l in known Venturi -tubes 39 beyond the vertical axis of the arrangement so that they generate in operation a rising helical flow of the aerated activating mixture with local escape of air on the surface of the acti-vating space.
A known floating indicator 43 in a s-torage tank 40 controls a valve 45 of a -transfer conduit 46 in order to ma:Lntain the required level of -the surface 44 in the s-torage tank 40 of raw water.
The arrangemen-t shown in Fig. 3 and 4 operates as follows. Raw water enters over the supply 26 the storage tank 40 after having been previously mechanically cleaned.
The pump 37 pumps the raw wa-ter over the pressure conduit 36 into the injector 35 where the supplied water is mixed wi-th air sucked on over the air supply 38.
The used gassing system not only aerates the activating mixture in the activating space 1, but simulta-neously imparts a motion to it, which is utilized for main-tenance of the activated sludge in suspension and for homogenizing the whole content of the activating space 1.
The hydraulic aeration aggregate should advantageously create a movement as shown in Fig. 3 and 4 where a circulat-ing motion within the activating space l is obtained.
In order to remove the influence of local out-bursts of the aera-ted activating mixture on the surface ll on the flow in the -transfer channels 9, a corresponding adjustment of adjustable overflows 1~ on inlets lO can be used.
The off-take of cleaned water from individual separating spaces 2 can be adjus-ted by regula-ting overflows 24 Eor each separating spaces individually. Otherwise the Eunctionning of the arrangement according to Fig. 3 and 4 ~2(~S~
is the same as that of the arrangement shown ln Fig. 1 ancl 2.
Al-though the cylindrical shape of the mantle 3 of the container of the arrangement is advantageous bo~h from the point of view of construction and also of the flow in the activating space 1, the arrangement according to this invention is not limited to a circular shape of the con-tainer. Particularly in case of a pneumatic aerating sys-tem it is possible to situate the separating spaces in rectangular containers.
The arxangement according to this invention has a number of advantages. The inlets 10 of transfer channels 9 as adjustable overflows 19 on the surface 11 and an alter-native addition of degassing inserts 25 in front of these inserts 10 enables a perfec-t removal of the oversaturation by air from -the activa-ting mix-ture which enters the separat-ing space 2 and thus eliminates the flotation of particles of activated sludge in the separation even in case of a high intensity of aeration of the activation and the-application of a deeply submerged aeration system.
The easy accessibility of inlets 10 of transfer channels 9 enables in case of need their easy cleaning even in the course of operation and a prevention of possible failures.
The occurance of failures due to choking of the transfer system is furthermore limited by the described shape of transfer channels 9 the accessibility of the inlets 10 enables an easy adjustment of the throughflow through these channels in the course of operation, enabling thus both an easy adjustment of conditions of operation of the apparatus according -to requiremen-ts and also adjustment oE
a possible assyme-try of the flow in the activatin~ space 1 and the elimination of a deformation oE the surface due to mentioned local outbursts of the activating mixture. That ~26~ '7 enables to apply at the arrangement different aera-ting systems, what in turn not only lncreases the ~lexibility of the arrangement, but in case of application of an injec-tor 35 enables to achieve a high energetic efficiency of aeration and an advantageous application particularly a-t column type apparatus with a heigh-t of -the water column in the activating space more than 5 m.
The separation of the flow of the ac-tivating mix-ture entering -the separating space 2 and of the separated sludge returning from -this space increases -the maximum value of the surface load by material of the separation, increases the maximum value of the surface load by material of the separation and thus increases the capacity of the arrangement up to 30% according to conditions of cleaning.
The construction of transfer channel 9 furthermore transfers the carrying out of built-in elements from the diffucult accessible activating space 1 to -the easier acces-sible separating space 2 and thus simplifies the assembling of built-in elements.
Another simplification of assembling enables the possibility of application of whole prefabricated transfer channels 9 where in the course of assembling solely a packing in the region of the inlet 10 is required. The construction of transfer channels 9 reduces furthermore claims on material for their manufacture. As no further inserted wall has to be suspended on the inclined partition wall 5 in order to provide a transfer channel 9 which partition wall 5 has solely the task to separate bo-th working spaces 1 and 2, it is possible to reduce its weight to the maximum using thin-walled material, what -toyether with reduc-tion of claims on material for building transfer channels 9 reduces substan-tially the weight of all built-in elements of the appara-tus for biological water cleaning, enabling -thus the achievemen-t of substantial savings.
9~
The arrangement shown in Fig. 5 is suitable Eor anaerobic sep-ticization of organically highly contaminated waste waters with production of biogas. From the arrange-ment shown in Fig. 3 and 4 it differs in that it is closed by a cover 47. ~assing elements 29 connected by a connect-ing conduit 38 to a not shown blower, connected in turn to a no-t shown storage tank of generated biogas, into which the off-take ~8 of biogas is terminating, serve for mixing the mixture in -the activating space 1.
The arrangement is fur-thermore provided with hot water heating 49 connected to a not shown source of hot water, which is partly heated by the genera-ted biogas.
This arrangement operates as follows. Raw water en-ters over the pressure conduit 36 the activating ~pace 1 which is mixed pneumatically by means of biogas blown-in into the activating mixture by gassing elements 29. The activating mixture is additlonally heated by hot water heating ~9. The source of heat is part of biogas generated by the proper anaerobic process of methanogenesis. In the course of taking-off the activating mixture, anaerobic activated sludge is separated similarly as at the aerobic alternative and is automatically returned back to the activation. Thus the concentration of activated sludge in the activation is increased and consequen-tly also the pro-cess of anaerobic methanogenesis is intensified. Thisin-tensification has two consequences. Due to increase of the concentration of the activated sludge -the intensifica-tion of the process enables a reduction of the volume of anaerobic septification and thus also a reduction of the detention, what means in addition of reduc-tion of investment costs also a reduction of heat losses. The second conse-quence is in that the increased concentra-tion enables to process also less concentrated waste waters with less dry material, enlarging thus -the possibilities of utilization.
~2~U~
The off-take of cleaned water, of sludge and oE gas has to be provided with not shown water closures in order to secure the airtightness of the arrangement.
Claims (13)
1. Arrangement for biological water cleaning comprising a container including an activating space and at least one separating space, separated from the activating space by at least one inclined partition wall for instance of conical shape, to the lower part of which a return passage is joined, connecting the separating space with the acti-vating space, at least one transfer channel arranged above said inclined partition wall in the separating space, the upper part of said transfer channel connected by its inlet to the upper part of the activating space, a gassing system provided in the activating space, the lower part of the transfer channel terminating by an outlet in the lower part of the separating space.
2. Arrangement as in claim 1, wherein the area of the throughflow cross section of the transfer channel in-creases toward its outlet.
3. Arrangement as in claim 1, wherein the trans-fer channel is arranged directly on the inclined partition wall.
4. Arrangement as in claim 1, wherein the inclined partition wall forms part of the transfer channel.
5. Arrangement as in claim 1, wherein a bubble collector is provided in the separating space; the outlet of the transfer channel in the lower part of the separating space being situated below and within the vertical projection of said bubble collector.
6. Arrangement as in claim 1, wherein the trans-fer channel is distributed symmetrically with respect to the vertical axis of the container, their number being uneven.
7. Arrangement as in claim 1, wherein the inlet of the transfer channel is at the level of the surface in the activating space and is provided with a regulating element.
8. Arrangement as in claim 7, wherein the regu-lating element is an adjustable overflow.
9. Arrangement as in claim 7, wherein the trans-fer channel extends above the level of the surface in the separating space, an opening being provided in the upper part of this extension as inlet.
10. Arrangement as in claim 1, wherein the plane of the outlet of the transfer channel is substantially vertical.
11. Arrangement as in claim 1, wherein a degas-sing insert is arranged in front of the inlet of the trans-fer channel in the upper part of the activating space.
12. Arrangement as in claim 1, wherein the sum of magnitudes of throughflow areas of regulating elements at inlets of transfer channels amounts to 0,05% to 2% of the magnitude of the area of the surface in the separating space and the sum of magnitudes of throughflow areas of outlets of transfer channels amounts to 4% to 12% of the magnitude of the area of the surface in the separating space.
13. Arrangement as in claim 1, comprising an injector, a gas supply, a Venturi tube and a pressure con-duit of raw water, said injector being arranged in the lower part of the activating space in the Venturi tube, and being adapted to generate a rising helical flow of the gassed activating mixture, with local outbursts of gas on the sur-face of the activating mixture.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CSPV5733-82 | 1982-07-30 | ||
| CS825733A CS231837B1 (en) | 1982-07-30 | 1982-07-30 | Device for a biological water purification |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1200927A true CA1200927A (en) | 1986-02-18 |
Family
ID=5402784
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000433348A Expired CA1200927A (en) | 1982-07-30 | 1983-07-27 | Arrangement for biological cleaning of water |
Country Status (6)
| Country | Link |
|---|---|
| AT (1) | AT381297B (en) |
| CA (1) | CA1200927A (en) |
| CS (1) | CS231837B1 (en) |
| DE (1) | DE3326326A1 (en) |
| IT (1) | IT1197685B (en) |
| NL (1) | NL8302527A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3408378A1 (en) * | 1984-03-08 | 1985-09-19 | Krupp Polysius Ag, 4720 Beckum | AIR CONTROLLED PUTTING MACHINE |
| AT386186B (en) * | 1984-07-13 | 1988-07-11 | Waagner Biro Ag | METHOD AND DEVICE FOR PREVENTING BUBBLE FORMATION IN THE ADMINISTRATION OF A LIQUID SATURED WITH REACTION GAS |
| IL104385A (en) * | 1992-01-17 | 1995-12-31 | Applied Research Systems | Method and apparatus for growing biomass particles |
| DE10022148A1 (en) * | 2000-05-08 | 2002-02-07 | Katrin Riebensahm | Method and device for cleaning domestic sewage |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT335931B (en) * | 1973-12-04 | 1977-04-12 | Agrotechnika Np | REACTOR FOR BIOLOGICAL WATER TREATMENT |
| DE2705243A1 (en) * | 1977-02-09 | 1978-08-17 | Bayer Ag | SINGLE-STAGE PROCESS FOR THE CONTINUOUS ENTRY OF OXYGEN-CONTAINING GASES INTO ANIMATED SLUDGE-CONTAINING WASTEWATER |
| CS200027B1 (en) * | 1978-06-15 | 1980-08-29 | Svatopluk Mackrle | Device for the biological treatment of water |
-
1982
- 1982-07-30 CS CS825733A patent/CS231837B1/en unknown
-
1983
- 1983-07-14 NL NL8302527A patent/NL8302527A/en not_active Application Discontinuation
- 1983-07-19 AT AT264483A patent/AT381297B/en not_active IP Right Cessation
- 1983-07-21 DE DE19833326326 patent/DE3326326A1/en active Granted
- 1983-07-27 IT IT4875283A patent/IT1197685B/en active
- 1983-07-27 CA CA000433348A patent/CA1200927A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| AT381297B (en) | 1986-09-25 |
| ATA264483A (en) | 1986-02-15 |
| DE3326326C2 (en) | 1993-04-22 |
| IT8348752A0 (en) | 1983-07-27 |
| DE3326326A1 (en) | 1984-02-09 |
| CS231837B1 (en) | 1984-12-14 |
| NL8302527A (en) | 1984-02-16 |
| IT1197685B (en) | 1988-12-06 |
| CS573382A1 (en) | 1984-05-14 |
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry |