Note: Descriptions are shown in the official language in which they were submitted.
~17~372
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Device for Purifying ~aste W~ter or Ground ~ater, and It~ Use
The invention relates to a device for purifying waste water
or ground water which is contaminated with organic substances
that are biodegradable and can be separated by
adsorption/desorption, which is characterized by
a) a fermentation system used for biodegradation
b) an absorber system which is equipped with a regenerative
polymer adsorbent that is upstream or downstream from the latter,
which is equipped with a feed pipe and a discharge pipe, as well
as with a steam feed and a drainpipe for the desorbate and the
purified water, respectively, as well as
c) a return pipe that connects the output of the downstream
system to the input of the upstream system.
The invention further relates to the use of the device for
purifying waste water or ground water.
It is known that with the aid of microbiological processes,
high rates of degradation of biodegradable compounds in
contaminated ground water or waste water can be achieved but that
the degradation in this process is generally not complete, so
that the guideline values specified by the law for surface waters
are not reached. The use of the adsorptive process results in
observing the prescribed guideline values, but requires a very
expensive process for disposal of the desorbate that accumulates.
It has now been found that by combining the two processes,
their advantages can be used in an ideal way and their
disadvantages can be eliminated.
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Based on diagrammatic Figures 1 and 2, the possibilities of
these combinations can be explained in more detail:
Figure 1 shows a device for purifying waste water or ground
water, which is characterized by an upstream fermentation system,
a downstream adsorber system, and a return pipe, which causes the
desorbate coming out to the input of the fermentation system to
be recycled.
In this embodiment, the ground water or waste water is thus
first fed for microbiodegradation of the contaminants and then is
fed to the absorber system, which almost completely removes the
residues of organic substances that are contained in the water.
The desorbate that accumulates is then recycled to the ground
water stream of microbiology.
Figure 2 shows a device for purifying waste water or ground
water, which is characterized by an upstream adsorber system, a
downstream fermentation system and a return pipe, which causes
the fermentation solution coming out to be recycled to the
discharge point of the waste water or ground water. In this
embodiment, the ground water is fed directly to the adsorber
system, and microbiological fermentation is used only to treat
the desorbate.
In practice, it is generally most advantageous to feed a
portion of waste water or ground water to the fermentation system
and the remainder to the adsorber system and in this way to
adjust the reaction parameters so that the treatment of the waste
water or ground water requires as little steam as possible.
217~3723
For the device according to the invention, basically all
fermentation systems are suitable that can be used for treating
waste water or ground water (B. Atkinson Biochemical Reactors,
Pion Ltd., Lyndon 1974), but fermentation systems that make
possible continuous fermentation are to be preferred.
An especially preferred device according to the invention is
one whose fermentation system consists of one to three fluidized-
bed fermenters, as described in non-prepublished PCT/DE93/00~14.
These fluidized-bed fermenters are characterized by an
inverted cone-shaped fermentation chamber (13 with two feed pipes
(2 and 3) that are optionally equipped with control valves (4 and
5), of which one feed pipe (2) is arranged vertically in the cone
vertex and the second (3) is arranged non-vertically in the cone
vertex at 0.02 to 0.3 times the fermentation chamber height and a
sedimentation chamber (6) that is present above fermentation
chamber (1), which has one or two drainpipes (7 and 8) that are
optionally equipped with control valves (9 and 10).
The special design of this fluidized-bed fermenter has the
effect that a turbulent flow prevails in its fermentation chamber
(1) if the liquid to be fermented is fed simultaneously via
vertical and horizontal feed pipes (2 and 3). This flow then
passes into sedimentation chamber (6) in an almost laminar flow.
If such continuously fed fermenters are inoculated with a
microorganism culture, the latter forms pellet-like agglomerates,
which are suspended in the fluidized bed of fermentation chamber
(1) and sink back into sedimentation chamber (6), after a growth
phase because of the turbulent flow. Because of these
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conditions, these fluidized-bed fermenters are considerably
better suited for continuous fermentation of large amounts of
liquid over a long period than the previously-known fluidized-bed
fermenters, such as, for example, the device described in
European Patent EP-B-0258611. Consequently, these fluidized-bed
fermenters are especially suitable for, e.g., biological waste-
water or ground-water treatment.
The design of these fluidized-bed fermenters is basically
determined by the type of microorganism cultures that are to be
used in them. If these are microorganism cultures which sediment
relatively quickly, such as, for example, microorganism
immobilizates, as described in International Patent Application
W0 88/08825, or fungi cultures, a fluidized-bed fermenter with a
fermentation chamber (1) and sedimentation chamber (6) of a
relatively low height is preferably used. In the case of
relatively poorly sedimenting microorganism cultures, as bacteria
cultures generally are, a fluidized-bed fermenter with a
relatively tall fermentation chamber (1) and sedimentation
chamber (6) is preferred. It is not necessary, however, that a
specially configured fermenter be used for each microorganism
culture used; by properly regulating the rates of intake of the
liquids to be fermented through vertical and nonvertical feed
pipes (2 and 3), continuous fermentation can generally also be
achieved with fluidized-bed fermenters according to the invention
that are not optimally configured for the special case.
Generally, these fluidized-bed fermenters are to be
configured in such a way that the upper diameter of fermentation
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chamber (1) is 0.1 to 0.8 times its height. In the case of these
numerical values, it is not taken into consideration that the
fermentation chamber normally has a truncated cone vertex, which
is suitable simply because the fermenters can be cleaned more
easily.
It was already mentioned that non-vertically aligned feed
pipe (3) is arranged in the shell of the cone at 0.02 to 0.3
times -- especially 0.05 to 0.15 times -- the fermentation
chamber height, and two feed pipes are aligned in such a way that
a fluidized bed is produced when the fermenter is put into
operation in the fermentation chamber. Non-vertically-aligned
feed pipe (3) can be arranged horizontally in such a way that the
horizontal line that points from the intake opening of this feed
pipe to the fermentation chamber axis crosses this axis. To
create a readily reproducible turbulent flow, it is suitable,
however, for the longitudinal axis of the non-vertically-aligned
feed pipe and the horizontal lines that point from the intake
opening of this feed pipe to the fermentation chamber axis to
form an angle vertically and/or horizontally that does not exceed
the value 70 in the vertical or a value 60 in the horizontal.
If this feed pipe (3) is arranged pointing vertically upward, the
angle is preferably 10 to 60 (especially 30 to 40); if the
pipe is vertical, but is arranged pointing downward, the angle
suitably has a value of between 10 and 60 (especially 20 to
4S). If optionally feed pipe (3) is additionally arranged
offset horizontally, the angle is preferably 5 to 60 and
especially 20 to 45.
21703f7~
_ 6
It is obvious to one skilled in the art that the terms
~horizontal" and "vertical" are not meant in the mathematical
sense, but that the feed pipes can deviate within the usual
tolerances from an exact horizontal or vertical arrangement.
Generally, drain pipes (2 and 3) are equipped with conventional
control valves (4 and 5) and are connected via a common pipe to a
storage vessel that is intended to receive the solution to be
fermented.
It was already mentioned that these fluidized-bed fermenters
have a sedimentation chamber (6) that is present above
fermentation chamber (1), which has one or preferably two
drainpipes (7 and 8) that are optionally equipped with control
valves (9 and 10).
This sedimentation chamber (6) can be configured in such a
way that it represents a continuation of the cone-shaped
fermentation chamber without transition; in contrast, it can also
be configured, for example, in such a way that it consists of one
or two cylindrical components that are optionally provided with a
conical broadening. In this case, it can be dimensioned in such
a way that its upper diameter is 1 to 3 times (especially 1.5 to
2.5 times) the upper diameter of fermentation chamber (1).
Sedimentation chamber (6) is preferably dimensioned in such a way
that it has 0.2 to 0.5 times the height of fermentation chamber
(1). Sedimentation chamber (6) has one or preferably two
drainpipes that are optionally equipped with control valves (9
and 10). Two drainpipes are then suitable if the intention is to
recycle a portion of the fermented liquid into the fermentation
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cycle to dilute the liquid to be fermented until virtually
complete conversion of the substrates contained therein can be
achieved. In this case, the drainpipe used for recycling is
suitably arranged somewhat deeper (preferably 20 to 40% below the
upper drainpipe) than the pipe used for drainage.
Just like conventional fermenters, these fluidized-bed
fermenters can also be equipped with the conventional auxiliary
devices that make possible temperature equalization, pH control,
ventilation and/or sterilization of the fermenter content. It
can be made of glass and/or noncorroding metal in the same way as
conventional fermenters.
Based on the drawings, these fluidized-bed fermenters are to
be explained in more detail.
Here:
Figure 3 shows a lengthwise section through a fluidized-bed
fermenter according to the invention.
Figure 4 shows a cross-section through the fluidized-bed
fermenter of Figure 1 at the level of plane A-B.
Figure 5 shows a lengthwise section through a fluidized-bed
fermenter with built-in temperature-equalizing, ventilating, and
sterilizing devices.
Figure 6 shows a diagrammatic representation of a
fermentation unit with a fluidized-bed fermenter according to the
invention, and
Figure 7 shows a diagrammatic representation of a
fermentation unit with two fluidized-bed fermenters that are
connected in series.
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The fluidized-bed fermenter shown in Figure 3 is intended
for treating waste water with bacteria cultures. It consists of
cone-shaped fermentation chamber (1) with a truncated cone
vertex, sedimentation chamber (6), as well as feed pipes (2 and
3) that are equipped with control valves (4 and 5) and drainpipes
(7 and 8) that are equipped with control valves (9 and 10).
Fermentation chamber (1) has a height of 2300 mm and an upper
diameter of 600 mm. Vertical feed pipe (2) and, at a height of
230 mm, nonhorizontal feed pipe (3), which is inclined vertically
upward and forms an angle of 35 with it and with the horizontal
line, leads into it. Sedimentation chamber (6) is arranged on
the upper edge of fermentation chamber (1). This consists of two
cylindrical components that are provided with a conical
broadening, is closed above and has an upper diameter of 1300 mm
and a total height of 1300 mm. (Hatched area 12 of Figure 1 is
intended to symbolize the region in which the bacteria culture is
swirled. The chamber identified by number 16 is to symbolize the
largely bacteria-free chamber). Below the upper cover, two
drainpipes (7 and 8) are attached facing one another, of which
one pipe (8), which is used for the discharge of the fermentation
broth, is arranged 250 mm below the upper cover of the
sedimentation chamber and pipe (9), which is used for recycling,
is arranged 600 mm below the upper cover of the sedimentation
chamber. The fermenter is made of stainless steel. It is clear
from Fig. 4 that nonvertical feed pipe (3) with the straight line
pointing from its intake to the fermentation axis forms an angle
~ of 35.
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,,
The fluidized-bed fermenter shown in Figure 5 has the same
design as that described in Figure 1, but it also has a circular
incoming air pipe (13) just above the bottom that is equipped
with nozzles 1, a superheated steam pipe (14), which can be used
in it to sterilize the fermenter contents, and a double shell
(lS) that covers the fermentation chamber for receiving the
temperature-equalizing liquid.
The fermentation unit diagrammatically depicted in Figure 6
basically consists of a fluidized-bed fermenter, as explained in
Figure 1, and a ~e~ pipe (17) that is equipped with a metering
pump (22) as well as a feed pipe for feeding additive (19) for
controlling pH, a feed pipe for feeding H202 as an oxygen donor
(20), a feed pipe for feeding nutrient medium (21), and a feed
pipe for feeding waste water (18), which is connected by a branch
to feed pipes (2 and 3).
1 m3 of waste water and of the reflux adjusted to pH = 7 and
enriched with nutrient medium are fed hourly by feed pipe (18) to
the fermenter that is inoculated with an isolated bacteria-mixed
culture which is isolated from the corresponding waste water
sludge, and control valves (4 and S) of feed pipes (2 and 3) are
set in such a way that after the growth phase has ended (about 2
to 6 weeks), a stable fluidized bed with a constant microorganism
density results in the fermenter. Then, 1 m3 of purified waste
water is removed hourly from the fermenter via one drainpipe (7),
while 7 to 14 m3 of purified waste water is recycled per hour via
the other drainpipe (8) to dilute the waste water or ground water
that is fed in.
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Finally, the fermentation unit that is diagrammatically
depicted in Figure 5 can be mentioned, which is basically
distinguished from the device sketched in Figure 4 in that it has
two fermentation units t23 and 24), which in principle have the
same design as the unit shown in Fig. 4, and drainpipe 32 for
removal from unit 24 is used to feed waste water or ground water
to fermentation unit 23. This unit can be adjusted by
correspondingly adjusting the control valves so that the
fermenters are connected in parallel or in series.
As an adsorber system, the device according to the invention
can have a conventional adsorber column that is equipped with a
feed pipe and drainpipe for water, a steam feed pipe, and a
desorber drainpipe.- Each of these pipes has a control valve,
which makes it possible to switch the column from adsorption to
desorption. The column is fed with a regenerative polymer
adsorbent, such as, for example, Wofatit Y 77 (now EP63), Y 59 or
EP61 of the Firma Chemie AG tChemical Company AG], Bitterfeld or
XAD2 or XAD4 of the Firma Roehm und Haas tRoehm and Haas
Company], in the usual way and is used for adsorption and
desorption in a way that is well-known to one skilled in the art
(Ullmann's Encyclopedia of Industrial Chemistry 5th Ed. Vol. B3,
VCH Verlagsgesellschaft DE Weinheim, Chapter 9, Chem.-Ing.-Techn.
tChem. Eng. Techn.], MS 1202/84 ref. in Chem.-Ing. Techn. 56,
1984, 242f and Chem. Techn. 43, 1991, 51f).
Such an adsorption system that consists of a single adsorber
column has the disadvantage, however, that it cannot operate
continuously. Therefore, it is more advantageous, in the device
. .' 21~037~1
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according to the invention, to use an adsorption system, which
consists of 2 to 12 adsorber columns that are connected to one
another in such a way that a portion of it is used for adsorbing
contaminants in water, while one or-optionally also several
columns are desorbed by means of steam.
In Figure 8, such an adsorption system is explained in more
detail:
This system consists of four adsorber columns 41 to 44. It
shows a state of the system in which waste water or ground water
is introduced into columns 44, 41 and 42 connected in series via
the opened control valves of feed pipe 46 and the purified water
is ~ Arged via drainpipe 47, collected in reservoir 51, and
sent via a pump 50 as coolant into condenser 49 and finally via
pipe 52 into the ground water. At the same time, steam is
introduced into column 43 via the corresponding control valve
from steam pipe 45, and the desorbate is removed via drainpipe
48, completely condensed in condenser 49, and returned via pipe
52 to the fermentation system.
Figure 9 shows a diagrammatic representation of a device
according to the invention for purifying waste water or ground
water, which basically consists of a fermentation system
according to Figure 6 and an adsorber system according to Figure
8.
