Note: Descriptions are shown in the official language in which they were submitted.
'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
'~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
-- 5
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
-- 10 --
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
- 13 -
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
- 14 -
'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
- 15 -
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
- 18 -
~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.
-- 19 --
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.
- 20 -
~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.
