Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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A CLEAN-WATER OUTLET
Field of the Invention
The present invention relates to a clean-water outlet, in
particular for the discharge of clean water from SBR plants,
having a float, a closable outlet element disposed thereon
which possesses an inlet section for the supply of the clean
water into the outlet element and having a discharge line
connected to the outlet element for the discharge of clean
water. In this instance, the semi-batch reactor or SBR is
being used as one element in a waste water treatment
installation. SBR's are used in a wide variety of chemical
processes, and are commonly used in waste water treatment
installations.
Background of the 'Invention
Such clean water outlets are frequently used in SBR water
treatment plants, and are used therein at the end of the
biological treatment of the waste water, for example at the end
of the cycle for an SBR to discharge or decant the water
treated during such a cycle. The clean water outlet therefore
must be capable of ensuring draining-off of the treated water,
and of retaining the biomass in the SBR, so that it is
available for use in subsequent treatment cycles. Generally
during the clean-water discharge step, the biomass is largely
in a sedimented state, with a small part floating upon the
clean water surface.
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Accordingly, there is a demand on an optimum clean-water outlet that this be
disposed
in a floating manner in order to ensure the greatest possible distance to the
sedimented
sludge at all times. Furthermore, a clean-water outlet must be of a closable
design.
This makes it possible only to open the outlet when clean water is to be
discharged,
whereas in the other phases, i.e. during the activation and mixed phases, it
is fully
closed. This prevents any sludge penetrating and being taken into the outlet
during
the clean-water discharge.
Due to the fact that the sludge is also present in part as float, an ideal
clean-water
outlet must also meet the task of discharging the water not directly at.the
.water
surface, but below it in order to retain the floating sludge accordingly.
Further, the
clean-water outlet must be designed in such a way that the flow rates are
limited
during the discharge of the water so that sedimented sludge is not whirled
along.
Generic clean-water outlets are known which possess a float and a discharge
wo.ir
disposed below the surface of the water. The discharge weir is connected to a
hose or
pipe line through which the clean-water supplied to the discharge weir is
discharged.
To meet the required closability of the clean-water outlet, the discharge weir
in clean-
water outlets of the prior art is closed by means of a mechanism disposed
above the
float and opened only as required, i.e. during decanting. In such a clean-
water outlet, it
is a disadvantage that, on the one hand, mechanical parts are needed to open
and close
the clean-water outlet and that, on the other hand, the leak-proofness of the
outlet
cannot be reliably guaranteed, in particular after longer use, due to wear
phenomena.
Summary of the Invention
It is therefore the object of the present invention to further develop a
generic clean-
water outlet in such a way that this possesses no mechanically moving parts at
all to
open and close the outlet and also closes reliably after longer operation.
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This object is solved on the basis of a generic clean-water outlet by the
inlet section
being designed in such a way that it can be closed by means of an air or gas
cushion,
by means being provided by means of which the air or gas cushion can be
generated in
the inlet section and by a deaerator being provided by means of which the air
or gas
cushion can be eliminated from the inlet section. A clean-water outlet of such
a design
meets the demands given above and furthermore possesses the advantage that no
mechanically moving parts are needed to close the clean-water outlet or the
outlet
element. Rather, the closing is based on the creation of an air or gas cushion
which is
disposed in such a manner in the inlet section of the outlet element that this
can be
reliably closed and accordingly prevents water from penetrating the discharge
element.
A further advantage over clean-water outlets of the prior art results from the
fact that
the wear of sealing elements, which can lead to the clean-water outlet having
corresponding leaks, is of no importance in the present case as the closing
effect is
achieved exclusively by the air or gas cushion in accordance with the
invention.
In accordance with a preferred aspect of the present invention, the inlet
section is
disposed between the outlet element and the float.
It is of particular advantage if the outlet element is designed as a discharge
weir. The
inlet section of the clean-water outlet can be formed by the overflow edge of
the
discharge weir and a groove-shaped recess of a component of the clean-water
outlet
disposed opposite the discharge weir. Accordingly, in accordance with the
invention,
an air or gas cushion is formed in the groove-shaped recess to close the clean-
water
outlet, by means of which the access of water via the overflow edge of the
discharge
weir is effectively prevented.
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In accordance with a preferred aspect of the present invention, the component
disposed opposite the discharge weir is the float of the clean-water outlet.
Instead of
this, it is equally possible to provide any other component which possesses a
corresponding groove-shaped recess on its side allocated to the overflow edge.
In accordance with a first aspect of the present invention, there is provided
a clean-
water outlet for extraction of clean water below the surface of the water in a
plant,
comprising
(i) a float having a closable outlet element disposed thereon and an inlet
section for
feeding the clean water into the outlet element;
(ii) a discharge line connected to the outlet element for discharging the
clean water;
(iii) a generating means for generating an air or gas cushion in the inlet
section; and
(iv) a venting means for extraction of the air or gas cushion from the inlet
section,
wherein the inlet section is constructed and arranged to be closable by means
of the air
or gas cushion.
In another aspect of the present invention, it is provided that the deaerator
comprises a
valve. The means to generate an air or gas cushion can comprise a compressor.
In accordance with a preferred aspect of the present invention, means can be
provided,
by means of which the float and the outlet element can be fixed in a
horizontal
position. This is advantageous particularly for the reason that the centre of
gravity of
the clean-water outlet in accordance with the present invention is pushed
upwards by
the air cushion generated from time to time, whereby the stable position of
the clean-
water outlet in the water is impaired.
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Two guide elements running parallel and rotatably disposed on the clean-water
outlet
and a mounting device can be provided, the distance of the rotating axles on
the
mounting device and the clean-water outlet being identical and the connecting
lines of
the rotating axles on the mounting device and the clean-water outlet running
in
parallel. The guide elements are disposed in the sense of a parallelogram, by
means of
which it is also ensured that the horizontal orientation of the outlet element
and of the
float is maintained irrespective of the level of the water.
It is particularly advantageous if one of the guide elements is formed by the
discharge
line.
In a further aspect of the present invention, it is provided that at least one
of the guide
elements is hinged to the clean-water outlet and to the mounting device at two
points
in each case.
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Brief Description of the Drawings
Further details and advantages of the present invention are described by means
of an
embodiment shown in the drawing in which
Fig. I shows a schematic cross-section view of the cleari-water outlet in
accordance with the invention in a closed state and. during the
decanting phase;
Fig. 2 shows a schematic representation of the clean-water outlet in
accordance with the invention in a side view and a top view;
Fig. 3 shows a schematic representation of a generic clean-water outlet of
the prior art;
Fig. 4 shows a schematic representation of a clean-water outlet of the prior
art having a decanter disposed below the water's surface;
Fig. 5 shows a schematic representation of a clean-water outlet of the prior
art having a discharge bath which can be lowered into the tank.
Fig. 6 shows a schematic representation of a clean-water outlet of the ,prior
art having a siphon; and
Fig. 7 shows a schematic representation of a clean-water outlet of the prior
art having a telescoping discharge line.
Detailed Description
Fig. I shows in a schematic cross-section view the clean-water outlet in
accordance
with the invention in the closed state (top) and during the decanting phase
(below).
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Below the float 10, the discharge weir 30 is disposed which possesses the
circumferential overflow edge 32. In its lower region disposed opposite the
overflow
edge 32, the float 10 possesses the groove-shaped recess 12. The inlet region
20 of the
discharge weir 30 is accordingly limited by the overflow edge 32 and the
groove-
shaped recess 12.
Furthermore, a compressor 50 is provided which is connected by a flexible line
to the
float 10, lines for the supply of the compressed air to the groove-shaped
recess 12
being provided inside the float 10.
The discharge weir 30 is connected at its lower region to the discharge,line
40, by
which the clean water supplied to the discharge weir 30 is let out therefrom.
As Fig. 1, bottom, illustrates, a valve 60 is further provided which is
connected to the
air or gas lines extending in the float 10 and connecting to the groove-shaped
recess
12. In Fig. 1, top, the valve 60 and in Fig. 1, bottom, compressor 50 is not
shown.
If the discharge weir 30 is to be closed, compressed air or any gas mixture is
led by
means of the compressor 50 and the lines extending therefrom into the groove-
shaped
recesses 12, with a corresponding air or gas cushion being created therein.
Here, the
overflow edge 32 of the discharge weir 30 is disposed in accordance with the
invention in such a way that an overflow over this edge 32 by clean water is
impossible when the groove-shaped recess 12 is filled with the air or gas
mixture.
The discharge line 40 further possesses a stop element (not shown) preferably
disposed outside the clean-water tank which is only opened when clean water is
to be
discharged.
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If clean water is now to be decanted, the valve 60 shown in Fig. 1, bottom, is
opened,
whereby the air or the gas is eliminated from the groove-shaped recess 12 and
the inlet
section 20 is released for the passage of water. The water flows in accordance
with the
arrows shown in Fig. 1, bottom, first through the inlet section 20 into the
discharge
weir 30 and is discharged therefrom through the discharge line 40.
Fig. 2, top, shows in a schematic side view, guide elements 40, 80 running in
parallel
and disposed on the clean-water outlet and the mounting device 70. Here, the
guide
element 40 is formed by the discharge line 40. Both guide elements 40, 80 are
rotatably connected by the rotating axles 85 with the clean-water outlet and
the
mounting device 70. The distance of the rotating axles 85 on the mounting
device 70
and the clean-water outlet is identical. Furthermore, the connecting lines of
the
rotating axles 85 on the mounting device 70 and on the clean-water outlet are
disposed
in parallel to each other. The rotating axles 85 thus determine the four
corner points of
a parallelogram. By means of such an arrangement, it is achieved thatthe
discharge
weir 30 is always held in a horizontal position or that the clean-water outlet
is always
held in the plane described in Fig. 2, top, by Y-Y, irrespective of the water
level.
Fig. 2, bottom, shows that the guide element 80 on the clean-water outlet and
on the
mounting device 70 is hinged in each case at two points 85. It therefore
results that
any moving possibility of the clean-water outlet is no longer given in the
plane X-X.
Figs. 3 to 7 show clean-water outlets of the prior art.
Fig. 3 shows a generic clean-water outlet with a float 10 and a discharge weir
30
disposed thereunder. The discharge weir 30 is opened and closed by means of a
valve
to be actuated mechanically, the valve actuation being effected by the
mechanism 90
located above the float 10. The discharge weir 30 is connected to the
discharge line 40
for the discharging of the clean water.
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Fig. 4 shows a decanting device in which the clean-water discharge is always
performed under the water's surface. Here, there is the disadvantage that
during the
aeration and mixing, the closing of the discharge line 40 is impossible, which
leads to
the fact that at these times, sludge can penetrate the discharge line.
Fig. 5 shows a clean-water outlet in which an outlet bath 100 can be lowered
into the
tank by means of a mechanical lowering device 110 while at the other times,
the bath
100 is raised outside the tank. In such a clean-water outlet, there is a
disadvantage in
that the outlet bath 100 is always travelled through the float layer during
the lowering
and during raising always takes up float and removes it from the tank.
The clean-water outlet of Fig. 6 comprises a siphon 120 by means of which
water can
be discharged from the tank. Here, the disadvantage results that, on the one
hand, the
possible lowerings of the water level are limited and, on the other hand, the
distance to
the float level is not optimum.
Fig. 7, finally, shows a clean-water outlet in which the clean water is
discharged via a
discharge weir 30 which is mounted on floats 10 and is accordingly always held
at the
water's surface in this way. In this clean-water outlet, the discharge line 40
has a
telescope-like design and is telescoped together by a corresponding amount
when the
water level falls. Here, the disadvantage results that the seal of the
discharge lines 40
connected together in a telescope-like manner, can only be designed with
limitations
with the result that sludge can penetrate the discharge line 40. Furthermore,
the
possible lowering of the water level is limited.
