Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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"Process for the biological treatment of organic
materials and apparatus for carrying out the process'
The invention relates to a process for the
biological treatment of organic materials. The invention
equally relates to an associated apparatus for carrying out
the process.
Description of the prior art:
The waste industry has been subjected for some
years to an accelerated restructuring process. In this
process, the problem of disposal and utilization of
biological wastes from households, commerce and industry
is also increasingly assuming prominence. Numerous
processes have been disclosed for the biological,
mechanical/biological or chemical/biological residual
waste utilization. The best-known process used is com-
posting animal and plant wastes, the organic substances
being substantially degraded or converted by micro-
organism~ in an aerobic conversion process. In addition
to the aerobic rotting process, anaerobic fermentation
for treating biological wastes has also been disclosed,
which likewise decomposes refuse with the action of
microorganisms, with the exclusion of air. The two
processes are used in waste technology either individ-
ually or in combination.
In particular during composting using an aerobic-
treatment, in a known preliminary rotting process, the
material, to mix it, is continuously agitated in a
rotting drum and is converted to fresh compost in a
period of approximately one to two days. In the case of
a static preliminary rotting, the material to be com-
posted is at rest, and is aerated during this. This
requires a considerable amount of space, in particular
for the subsequent secondary rotting operation as well.
The advantage of the dynamic preliminary rotting with
continuous mixing of the refuse mixture is the good
aeration of the material, the occurrence of anaerobic
points in the material being prevented.
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The anaerobic treatment of organic refuse wastes
or biowastes which has likewise been disclosed in recent
years is based on an anaerobic fermentation, i . a . on a
digestion process, which, with the exclusion of air,
leads to biogas production in a weakly exothermic reac-
tion. A process of this type has been disclosed, for
example, by EP 0 037 612 B1, in which organic wastes are
treated in a static process in a reactor with a leaching
liquid which leaches soluble inorganic and/or organic
materials from the material to be treated. This process
takes place with the exclusion of air, i.e. under
anaerobic conditions, as a so-called hydrolysis.
A disadvantage of this known process is, owing to
the static disposition of the material, the formation of
short-circuit flow channels, i.e. the applied liquid
seeks the path of least resistance, via isolated
channels, owing to a type of chimney effect, so that the ---°'
material .
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is only incompletely irrigated with washing liquid. The
result is dead zones which are not leached, or are leached
only insufficiently.
A process for the biological treatment of organic waste became
known from WO-A-95/20 554 in which easily degradable organic
waste materials are to be converted into compost only by means
of an aerobic process. The organic substance is thereby
reduced by a biological degradation. To accomplish this, air
is conveyed from the upper air chamber by means of ventilators
downward through the material and filtered off by low-pressure
suction. To accelerate the biological degradation process,
the material is broken up with various agitating devices at a
preset location in a cross-grain manner and, if necessary,
wetted with a water curtain. The shelves loaded with waste
are then gradually pushed with a hydraulic ram through the
composter, removed at the back and, if appropriate, introduced
again at the front.
Object and advantages of the invention:
The object underlying the invention is to propose an improved
process for the biological treatment, in particular, of wet
organic materials (biorefuse), in which said disadvantages do
not occur and which represents, in particular, an extremely
effective and inexpensive treatment method for such materials.
The central concept underlying the invention here is that a
combined treatment of the material in the form of a leaching
process and a targeted aerobic material treatment leads to a
very highly effective rotting of the product. In this
process, the invention makes use of individual process steps,
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some of which are known per se, which in combination, however,
lead to an effective treatment of the biorefurse.
The process according to the invention has the advantage, in
particular, that on account of a dynamic treatment of the
material, short-circuit flow channels are prevented or
destroyed both in the vertical and in the horizontal direction
in the material, so that the irrigation carried out with
leaching liquid covers the material uniformly and in all
places, so that no dead zones form. The organic mass is
continuously or discontinuously circulated and simultaneously
subjected to an aerobic decomposition of material. In the
course of this, the irrigation is carried out from top to
bottom, with periodic simultaneous exposure to an airstream
from bottom to top to achieve aerobic degradation.
The rotting process is carried out in a reactor constructed
according to the invention having an appropriate circulation
device for the material and an irrigation system and means for
feeding fresh air
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15 ing the leaching liquid.
The subclaims specify advantageous and expedient
developments of the process according to the invention.
It is particularly advantageous to operate the
reactor in the through-flow mode, i.e. the reactor is
20 charged from one side with material which is slowly
transported through the reactor owing to the circulation
mechanism. On the other side, the material is accordingly
taken out of the reactor.
A flow-through mode of this type has the advan
25 tape, in particular, that different material properties
exist over the length of the reactor, since, owing to the
residence time of several days, the degree of degradation
of the material changes over the length of the reactor
and the material can accordingly be subjected to a
30 different treatment. As a result, treatments differing in
space and time, in particular over the length of the
reactor, are carried out both with leaching liquid and
with fresh air for the aerobic rotting.
The reactor according to the invention therefore
35 makes possible extremely flexible handling of the
material to be introduced, depending on its composition
and, in particular, depending on organic loading, tem
perature and water content, in particular the aerobic
conversion of the material being able to be measured over
V. ~ 'v1
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the length of the reactor and the process being able to be
under closed-loop or open-loop control.
The degree of filling of the reactor with the
material to be treated and its three-dimensional shaping and
the irrigation of the surface of the material are
advantageously matched to one another in such a manner that
the maximum possible material surface area is uniformly
irrigated, so that no dead zones are formed.
It is further advantageous that, in the lower area
of the reactor, a plurality of chambers are provided which
equally serve for feeding fresh air and/or as an outlet for
the leaching liquid, the chambers being covered in
particular by a screen filter to avoid as far as possible
passage of material. The covering screen can be cleaned by
backflushing, a plurality of chambers being able to
interact.
It can also be advantageous to flood the lower
area of the reactor with leaching liquid in order to produce
a type of flotation of the material for better circulation,
which is preferably expedient in the case of very tough
and/or very dry material.
The process according to the invention is
preferably further developed by the fact that various
mechanical/biological stages are arranged downstream of the
through-flow reactor, which stages purify and regenerate the
leaching liquid and free this from the high organic loading
by an anaerobic treatment. A leaching liquid treated in
this manner can be recirculated back to the reactor
according to the invention.
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According to one aspect of the present invention,
there is provided a process for biological treatment of
organic waste material in a solids reactor, comprising the
steps of: charging the reactor with the waste material at a
first end of the reactor; feeding air to the waste material
so the air flows through the waste material in a first
direction, to cause an aerobic degradation of organic
substances in the waste material, whereby the waste material
heats to a process temperature in the reactor; applying
leaching liquid to the material so the leaching liquid flows
through the waste material in a second direction opposite to
the first direction and so that at least one of soluble
organic substances, soluble inorganic substances, and water
soluble fatty acids are leached from the waste material into
the leaching liquid: agitating, circulating and transporting
the waste material with an agitating/circulating/
transporting mechanism in the reactor to mix the waste
material, prevent the formation of liquid bypass channels in
the waste material, and transport the waste material towards
a second end of the reactor: and removing the leaching
liquid charged with at least one of soluble organic
substances, soluble inorganic substances, and water soluble
fatty acids at a lower part of the reactor.
According to another aspect of the present
invention, there is provided the process as described
herein, wherein the material is transported in at least one
of forward and backward directions through the reactor along
its length, and wherein at least one of the steps of the
application of leaching liquid and the feeding of air are
selected to be carried out uniformly, or varying over the
length of the reactor depending on the composition of the
material.
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According to still another aspect of the present
invention, there is provided the process as described
herein, wherein the applying step includes applying the
leaching liquid uniformly and simultaneously with feeding of
air, wherein aerobic degradation of the material causes
heating of the material and the leaching liquid, and the
heated leaching liquid causes leaching of at least one of
soluble organic substances, soluble inorganic substances,
and water soluble fatty acids.
According to yet another aspect of the present
invention, there is provided the process as described
herein, wherein the second end has an outlet area having an
outlet port for the material, the process further comprising
at least one of the following steps to reduce water content
of the material in the outlet area: reducing or shutting off
application of leaching liquid; and increasing feeding of
air; and wherein the process further comprises the step of:
sanitizing the material in the outlet area by feeding a
preheated backflow liquid during a predetermined time
interval.
According to a further aspect of the present
invention, there is provided the process as described
herein, comprising the step of using at least one of open
loop control and closed loop control to select between
continuous and discontinuous circulation of the material
depending on at least one of the organic loading,
temperature, and water content of the material.
According to yet a further aspect of the present
invention, there is provided the process as described
herein, wherein the reactor has a free air space above the
material that enables uniform application of leaching liquid
to the upper surface of the material.
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According to still a further aspect of the present
invention, there is provided the process as described
herein, wherein the lower part of the reactor has at least
two chambers which perform at least one of the functions of:
feeding fresh air; and providing an outlet for leaching
liquid, wherein the chambers are separated from the interior
of the reactor by a screen to prevent entry of solids into
the chambers.
According to another aspect of the present
invention, there is provided the process as described
herein, further comprising the step of cleaning the screen
by backflushing the reactor interior by flooding at least
one of the two chambers with a backflush liquid and feeding
the backflush liquid to an adjacent chamber.
According to yet another aspect of the present
invention, there is provided the process as described
herein, wherein air is forced in a direction along the
reactor interior during backflushing operation.
According to another aspect of the present
invention, there is provided the process as described
herein, further comprising the step of flooding the reactor
with leaching liquid via at least one of the two chambers so
that the material floats on the liquid and the floating
material is transported in at least one of forward and
backward directions in the reactor.
According to still another aspect of the present
invention, there is provided the process as described
herein, wherein the agitating/circulating/transporting
mechanism comprises a spined agitator having a horizontal
shaft passing through the reactor interior and a stirring
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arm, wherein the material is processed in the form of a
disk-shaped or plug-shaped advance of the material.
According to yet another aspect of the present
invention, there is provided the process as described
herein, further comprising the steps of: taking the leaching
liquid out of the reactor; feeding the leaching liquid to
downstream treatment stages; subjecting the liquid to at
least one of a mechanical treatment, an anaerobic treatment,
and a following aerobic treatment, to purify the liquid for
regeneration; and feeding the treated leaching liquid to
back flush at least one of the chambers and the free space
situated above the material in the reactor.
According to a further aspect of the present
invention, there is provided the process as described
herein, wherein the reactor has treatment stages comprising:
an interference separator for separating sink materials and
discharging floating suspended materials; and an anaerobic
methane reactor for treating the leaching liquid, so that
organic-enriched leaching liquid is degraded and purified by
methane bacteria with the formation of biogas as metabolic
product, wherein the purified leaching liquid is fed to an
aerobic purification stage to produce an aerobic state, and
wherein the purified and regenerated leaching liquid is fed
back to the reactor.
According to yet a further aspect of the present
invention, there is provided the process as described
herein, wherein the reactor has a material inlet area and
the process further comprises the step of adding activated
sludge from an aerobic activation plant to accelerate
reaction in the inlet area.
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According to still a further aspect of the present
invention, there is provided the process as described
herein, wherein the reactor has a material outlet area, and
the process further comprises the step of re-circulating a
portion of the treated material from the outlet area and
adding the portion to the inlet area to accelerate the
reaction.
According to another aspect of the present
invention, there is provided an apparatus for carrying out a
process for biological treatment of wet organic waste
material using a reactor to leach at least one of soluble
organic substances, soluble inorganic substances, and water
soluble fatty acids, out of the material, the apparatus
comprising: an elongate reactor; an agitating/circulatingl
transporting mechanism having a horizontal reversibly
rotating shaft; an inlet port for the materials an outlet
port for the material; spraying arms for applying leaching
liquid in the reactor interior; and chambers provided in a
lower part of the reactor said chambers performing at least
one of receiving the liquid and feeding fresh air.
According to yet another aspect of the present
invention, there is provided the apparatus as described
herein, wherein the agitating/circulating/transporting
mechanism comprises paddle shaped or blade shaped
circulation elements turnable to select between creating
forward and backward motion of the material.
According to another aspect of the present
invention, there is provided the apparatus as described
herein, wherein the circulation elements are disposed on the
shaft in at least one of the following configurations:
opposite each other, overlapping each other, and adjacent
each other.
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According to still another aspect of the present
invention, there is provided the apparatus as described
herein, wherein the circulation elements are axially offset
by a predetermined angle, and have at least one of an
inclined surface and curved surface.
According to yet another aspect of the present
invention, there is provided the apparatus as described
herein, further comprising a transport device to re-
circulate treated material to the inlet area.
According to a further aspect of the present
invention, there is provided a process for biological
treatment of organic waste materials using a solid waste
reactor, comprising the steps of: charging the reactor with
the waste material at a first end of the reactor; feeding
air and water to the waste material to cause aerobic
degradation of the material, whereby the material heats to a
process temperature; applying a leaching liquid to the waste
material so that at least one of soluble organic substances,
soluble inorganic substances, and water soluble fatty acids
are leached from the waste material and transferred into the
leaching liquid; agitating, circulating and transporting the
waste material with an agitating/circulating/transporting
mechanism to mix the waste material, prevent the formation
of bypass channels in the waste material, and transport the
waste material towards a second end of the reactor; removing
the leaching liquid from the lower portion of the reactor;
treating the removed leaching liquid to obtain regenerated
leaching liquid; feeding the regenerated leaching liquid to
the reactor for use in the applying step; and removing the
material at the second end of the reactor.
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Description of the drawings:
Advantages with respect to the apparatus according
to the invention for carrying out the process are specified
in more detail in the description of an exemplary embodiment
below,
wherein:
Fig. 1 shows a side view of a reactor according to
the invention for treating the bio-refuse having downstream
stages in a
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diagrammatic representation for treatment
of the leaching liquid,
Figs. 2 to 6 show a longitudinal section through the
reactor having a chamber situated at the
bottom in various operating states,
Fig. 7 shows a detail of the longitudinal view
of the agitator shaft.
Description of the invention:
The schematic diagram shown in Fig. 1 shows a
plant 1 for the biological treatment of preferably wet
biorefuse having a plurality of components, consisting of
a solids reactor 2 for treating the organic material and,
connected downstream of the reactor 2, processing stages
3 to 5 for after-treatment and reprocessing of the
reusable leaching liquid.
The reactor 2, in accordance with the drawing in
Fig. 1, consists of an elongate housing 6 having a
vertical cross section as shown in Figures 2 to 5. The
length 1 of the housing can differ very greatly, depend-
ing on the size of the plant, and, completely by way of
example, 1 can be 20 to 30 m. The height h of the reactor
compartment is in this case 4 to 5 m. In the lower area,
the cross section of the reactor housing 6' is roughly
cylindrical, and in the upper area 6", rather, is
rectangular (Fig. 2), triangular (Fig. 3) or, overall,
oval (Fig. 4). Through the reactor housing 6 passes a
horizontal shaft 7, which is preferably constructed as a
spined agitator 8 having paddle- or blade-shaped
circulation elements 9. The shaft 7 is driven via a drive
motor 10.
According to the drawing in Fig. l, the housing
6 of the reactor 2 has at its one end, at the top left in
the figure, a filling port 11 through which the reactor
is charged with an organically loaded material 13 in
accordance with the arrow 12. This is in particular wet
organic materials or biomasses which originate in par-
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ticular from biological wastes from households, from the
food-processing industry, agriculture, or from an organic
fraction of the residual refuse (landfill refuse) or the
like (biorefuse). Materials having the most varied
compositions both with respect to organic loading and
with respect to degree of moisture and initial tempera-
ture can be used.
At the other end of the reactor 2, in accordance
with the drawing in Fig. 1, at the lower right end, there
is situated an outlet port 14 for the material 13 after
treatment has been carried out, which material is dis-
charged from the reactor in accordance with arrow 15.
The reactor 2 shown in Fig. 1 is filled in its
interior 17 up to a mean filling height hF with material
13, so that an overlying air space 16 is established. The
filling height of the material can be, for example, two
thirds of the overall height h.
In the upper area of the reactor interior 17,
there are situated a multiplicity of spray arms 18 for
subjecting the material 13 to a leaching liquid 19 which
exits from the spray arms 18 in accordance with an arrow
representation. An upper feed line 20 having a control
valve 21 leads the leaching liquid 19 to the individual
spray arms 18. In the exemplary embodiment according to
Fig. 1, for example, seven spray arms 18 are arranged
distributed over the length of the reactor interior.
In the lower area of the reactor 2, in the
exemplary embodiment according to Fig. 1, a plurality of
chambers 22, and in particular four chambers 22, are
arranged adjacently which are separated from the interior
17 of the reactor by means of a covering screen 23, so
that the material 13 does not, as far as possible, fall
into the chamber 22. The screen hole diameter is between
6 and 12 mm and is, in particular, 8 mm in diameter. This
diameter is symbolized by dl.
The chamber 22 has a double function. Firstly, it
serves to collect the leaching liquid which passes
through the material 13. This leaching liquid is desig-
nated 19' in the chamber 22 and is led to a manifold 26
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via an outlet line 24 having a valve arrangement 25.
In addition, the chamber 22 serves to treat the
material 13 with fresh air 27, as is shown symbolically
by arrows in Fig. 1. The fresh air is fed via a com-
pressor 28 to a manifold 29, and from there is fed via
control valves 30 via the line 31 to the respective
chamber 22.
On account of the possibility provided for
backflushing and flooding the reactor interior 17 with
leaching liquid from the chambers 22 , an overf low wall 32
or overflow edge is provided in the area of the outlet
port 14. The associated upper liquid level 33 is shown
symbolically.
The lower manifold 26 for the leaching liquid
removed from the chambers leads via a shared line 34
having a valve arrangement 35 to the downstream process
ing stages 3 to 5 for treating the leaching liquid. These
treatment stages comprise, in particular, firstly an
inberfere~rc~- separat-o-x---3 --wizich--serves - to- -separate ofd
sink material of all types, such as, for example, sand,
stones or the like, i.e. all substances which pass
through the screen 23 as sink material. Sedimenting
materials are removed via a conveyor device 36, float
materials or suspended materials such as plastic, wood or
the like are removed from the interference separator via
a skimmer device 37.
The leaching liquid thus purified in the inter-
ference separator 3 is led via a line 38 by pump 39 to a
downstream anaerobic reactor stage 4 which is
constructed, for example, as a methane reactor. In this
methane reactor, the organics-enriched leaching liquid is
degraded and purified by methane bacteria, biogas or
methane gas 40 being formed as metabolic product.
Finally, the downstream treatment stage comprises
a further aerobic purification reactor 5 which, via a
line 41, converts the anaerobic state of the leaching
liquid into an aerobic state, an aerator 42 ensuring an
aerobic decomposition and activation of the leaching
liquid.
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Conventional components and plant sections
according to the known process diagram can be used for
these three downstream treatment stages 3 to 5 for the
leaching liquid.
The leaching liquid, which has been thus treated
and purified and, in particular, freed from high organic
loading, is taken off from the aerobic purification stage
5 via a line 43 and fed to a manifold 44 by a pump 45.
This manifold 44 leads to the individual feed lines 20 to
the spray arms 18.
A leaching liquid treated in this manner con-
sists, after a defined start-up phase of the plant 1, of
a slightly acidified liquid, the acidification of the
pure water initially used as leaching liquid taking place
owing to the aerobic treatment of the material 13 in the
reactor 2. This process corresponds to a hydrolysis, i.e.
to a dissolution of soluble salts with acidification of
the water.
The plant and, in particular, the solids reactor
2 act as follows:
The material 13 which is fed continuously or
discontinuously to the inlet port 11 of the reactor 2
generally consists of a wet organic material, in par-
ticular biorefuse, as mentioned at the outset. The
filling height of the material 13 is approximately
hF p~ 2/3 of the internal height h, so that an upper air
space 16 is formed. In this case, in accordance with the
depiction in Figs. 2 to 5, the filling height hF is
dimensioned such that virtually the entire width B of the
surface 46 of the material 13 can be sprayed with leach-
ing liquid 19. For this reason, the upper area of the
reactor, to avoid reduction in the material surface area
at a corresponding filling height, is constructed to be
rectangular (Fig. 2), triangular (Fig. 3) or, overall,
oval (Fig. 4) in cross section.
The uniform spraying of the material 13 with the
slightly acidified liquid 19 by the spray arms 18 causes
a leaching of soluble organic and/or inorganic substances
and/or water-soluble fatty acids which are formed by
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decomposition of the material 13. It is of importance
here that the material 13 is continually and continuously
or discontinuously circulated by a type of spined
agitator 8 having paddle-shaped or blade-shaped
circulation elements 9, in order firstly to obtain good
mixing of the material 13. However, the circulation also
serves, in particular, for avoiding so-called vertical
and horizontal short-circuit flow channels, which would
form in the material 13 owing to the liquid stream of the
leaching liquid, so that nonuniform wetting or leaching,
and thus dead zones, would form. The paddle-shaped or
blade-shaped agitator arms 9 can, in accordance with the
drawing in Fig. 1, be arranged in a multiplicity next to
and/or opposite one another, the paddle-shaped end blades
9 being able to lie adjacently or overlapping, so that a
type of disk-shaped circulation of the material occurs.
On account of the rotary motion of the shaft 7 (arrow
47), in addition, slow longitudinal transport in the
direction of the arrow 48 through the reactor interior 17
takes place, so that the material 13 migrates slowly
through the reactor and finally, after a residence time
of, for example, 4 to 8 days, leaves the reactor interior
17 through the outlet port 14.
During this treatment procedure and, in parti
cular, simultaneously or intermittently to the leaching
process, fresh air 27 is supplied in a specific manner
via the lower chambers 22 to the material 13, which leads
to a simultaneous aerobic treatment of the material
together with an exothermic self -heating of the material .
This aerobic treatment is completed with a
microbiological degradation of the organic substances by
appropriate microorganisms, the intensive odor develop-
ment being encapsulated on account of the closed con-
struction of the reactor. The upper air space 16 of the
reactor above the material 13 is continually exhausted by
a suction pump 49 via an air outlet orifice 50, so that
adequate aeration of the upper air space 16 also occurs.
The targeted extraction of the upper air by means of
reduced pressure ensures that only aerobic conditions are
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present in the upper air space 16 as well.
On account of the continuous or discontinuous
flow of the material 13 over the longitudinal direction
of the reactor, highly different material compositions
are situated within the reactor as a result of the
different residence time. For example, relatively fresh
and untreated material is situated in the area of the
filling port 11, whereas in the area of the rear outlet
port 14 the material has already been treated for, for
example, between 4 and 8 days. Accordingly, over its
length 1, the reactor can comprise highly different
treatment stages which can vary greatly.
Measuring devices, which are not shown in more
detail, for determining the most varied parameters of the
material, such as its composition, its temperature, the
moisture content etc., are assigned to the reactor,
further measured data being available on the leaching
liquid and the feed air. Depending on the progress of the
treatment, the adjacently arranged spray arms 18 can then
receive different flow rates of leaching liquid, in order
to obtain varying leaching of the material composition
present beneath each one . Equally, the, for example four,
chambers 22 lying beneath can receive different flow
rates of fresh air 27, in order to influence the aerobic
decomposition process of the material 13. Correspon-
dingly, the mixing of the material which is carried out
can additionally affect the material properties. For
example, in the case of an aerobic degradation of the
material, a certain increase in the surface area of the
organic material takes place, which at the same time
would promote the process of leaching by the leaching
liquid 19. Therefore, depending on the degree of aerobic
degradation carried out, the optimum amount of leaching
liquid must be added here, which can be determined by
experiment. Furthermore, for example, increasing the
temperature of the leaching liquid, owing to the aerobic
decomposition of the material, has a beneficial effect on
the subsequent treatment stages 3 to 5, in order to
obtain optimum regeneration of the leaching liquid. A
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preferred treatment of the material in the starting area
and in the final area of the reactor is described in
claims 3 and 4.
The interior 17 of the reactor 2 can therefore be
monitored by means of appropriate measuring devices and
the progress of the process can be controlled by a preset
program or else as a function of the measured values.
The adjacent lower chambers 22 are closed by the
covering screens 23 in such a manner that the material 13
as far as possible cannot pass into the chamber 22. A
critical factor for this is the mesh width having the
diameter dl.
However, from time to time the screen 23 must be
cleaned of impurities or blockages, which is performed by
a backflush operation. For this purpose, the liquid 19'
present and collected in the chamber 22 is either backed
up by closing the valves 25, so that the liquid rises
within the chamber 22, or purified leaching liquid is
taken off from the line 43, 44 via a manifold 51 and
specifically fed to the chamber 22 via feed lines 52
having a valve arrangement 53 (see Figs. 4, 5). The
liquid can be backed up here up to an upper liquid level
33 corresponding to the height of the overflow wall 32.
By a possible additional impingement of this liquid
compartment with compressed air via the compressor 28,
the respective impinged screen 23 can be blown free and
thus cleaned. This operation is also supported, in
particular, by means of the liquid pump 45 or a further
pump 54 in the manifold 51.
The covering screen 23 cleaning operation can
also be carried out in such a manner that in each case
only one chamber or only certain chambers are subjected
to a backflushing operation and the backflushing liquid
ascending as a result is removed in the adjacent, or one
of the adjacent, chambers. Thus, for example, the first
and third chamber 22 in Fig. 1 can each be drained into
the adjacent chamber during the backflushing operation.
Backing up the liquid, for example, up to a
liquid level 33 can, furthermore, also have the effect
~
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that the material 13 floats on this liquid cushion and
this material can be more readily mixed, in particular,
in the case of tough or very dry material.
As mentioned above, the material 13 can have
highly variable treatment with leaching liquid 19 and
fresh air 27 with simultaneous or intermittent circu
lation of the material. For example, approximately
0.5-2 m3 of leaching liquid per day and per metric ton of
material are converted in the reactor. The operating time
of the agitator can be between 5 and 60 min per hour, at
a speed of 1 to 2 rpm.
Fig. 2 shows, as an example, irrigation of the
material over as far as possible all of the upper surface
46 over its maximum possible width with simultaneous
circulation of the material by means of the spine
agitator 8. The leaching liquid 19 uniformly passing
through the liquid [sic] is collected in the lower area
of the chamber 22 as liquid 19'. In this state, there is
an additional exposure to fresh air 27, so that the
aerobic decomposition process of the material 13 takes
place simultaneously.
In the usual state, the leaching process and the
fresh air feed take place simultaneously. Fig. 3 shows
fresh air feed 27 alone without the leaching operation.
Fig. 4 shows the backflush operation up to a
depth of liquid having a liquid level 33 as described
above. As a result, the material floats on this liquid
cushion, so that the circulating agitator 8 can carry out
mixing more readily. A slight elevation of the material
within the reactor is not harmful during this mixing
operation.
The depiction of the arrangement in Figs. 2, 3
shows the fresh air feed operation via the line 31 having
valve arrangement 30 via the lower covering screen 23 to
the material 13. The air serves for the aerobic
degradation or the aerobic decomposition of the material
by microorganisms, the air being collected in the upper
air space 16 and extracted from the reactor interior 17
via the air outlet port 50.
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Fig. 5 shows the back wash operation via the line
52 with valve 53 open, with simultaneous impingement by
compressed air; Fig. 4 shows this operation without
compressed-air impingement, i.e. valve 30 closed.
The process according to the invention and the
associated apparatus can be still further optimized by
the measures described below.
As shown in Fig. 1, an additional partition and
submerged wall 55 is mounted in the area of the inlet
port 11. This submerged wall 55 prevents the fresh
material introduced from being able to pass unhindered on
the material surface 46 from the entrance 11 in a pseudo-
short circuit to the exit 14. The fresh material must
rather initially pass through below the submerged wall 55
along the path indicated by the arrow 56 and cross the
lower part of the reactor.
In special cases it can be expedient for the
material treated in the reactor to be sanitized prior to
exit from the solids reactor 2, i.e. for it to be sub-
jected to a defined temperature for a defined time. This
can be expediently carried out by the rear vessel content
13 being additionally heated on a defined section 11
(1/3 - 1/4) 1. For this purpose, for example, from line
43, via a parallel line 57, circulation water is taken
off which is heated in a heat accumulator which is not
shown in more detail, or is heated in a heat exchanger 58
which is shown diagrammatically. The circulation water of
the line 57 can then be added in a targeted manner in the
upper area of the reactor either to the manifold 44 or
targeted impingement is carried out, e.g. via feed line
20 in the rear reactor area. This is shown diagram-
matically in Fig. 1 via the last feed line 20'.
An expedient development of the process can also
be continuous or discontinuous addition of activated
sludge or excess sludge from an activation plant in the
area of the filling port 11. The aerobic microorganisms
introduced together with the activated sludge represent
a reaction accelerator for the biological conversion of
the organic materials. This addition is indicated dia-
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grammatically by arrow 59. Microorganisms already adapted
to the waste material have proved to be particularly
advantageous in this case, which microorganisms can be
taken off either from the aerobic percolate treatment
stage or, for example, from a biological leachate water
purification plant. The division of the material stream
into a substream 15', indicated in the area of the
outlet port 14, also enables partial recycling via the
line 60 of material treated in the percolator 6. An
10 additional transport element 61 can support this
operation. The partial recycling of material treated in
the percolator 6 and of the microorganisms which are
already adapted present therein can likewise accelerate
the reaction. This is shown diagrammatically via the feed
15 line 60 by arrow 62 in the area of the inlet port 11.
According to the depiction of the invention in
Figures 2 to 4, the agitator 8 has corresponding stirrer
arms or circulation elements which lead radially away
from the drive shaft 7. According to the drawing in
Figs. 5 and 6, to support the stirring effect, the
agitator 8 can also change its direction at intervals. In
this case, the stirring effect can be reinforced by a
blade-like twisting of the stirrer arms 8 or circulation
elements being performed at a pitch angle x in accordance
with Fig. 5 or else by a curved arrangement in accordance
with the drawing in Fig. 6. In the case of a blade-shaped
arrangement of the stirrer arms 8, the main direction of
rotation is indicated by e. When the direction of
rotation is in the direction of arrow e, optimum mixing
is achieved. However, with material 13 which is highly
fouled, for example with plastic films and strings, etc. ,
these may become wound round the stirrer arms 8. In order
to free the stirrer arms 8 from this fouling, the
agitator shaft 7 is rotated at intervals in the opposite
direction in accordance with arrow f, by which means, on
account of the slightly inclined, tangential or curved
arrangement of the stirrer arms 8, the fouling is scraped
off from the stirrer arms 8 by the friction on the
material 13 itself. The same effect is produced both in
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the drawing according to Fig. 5 and that according to
Fig. 6.
According to the drawing as in to Fig. 6, in
addition, the lower screen 23 can further be cleaned by
means of the agitator. For this purpose, at the ends of
the stirrer arms 8, an expendable part 63 can be mounted
as a slide. This expendable part, or this scraper, 63 at
the ends of the stirrer arm 8 can be introduced, adjusted
or exchanged from the exterior via the additional port 65
by a clamping apparatus 64 not shown in more detail.
In the case of a vessel 6' in cylindrical
arrangement according to Fig. 6, in addition, the
agitator 8 can be displaced off-center, preferably
downward, by a distance z from the longitudinal
cylindrical axis 66. As a result of this arrangement, the
agitator radius Ra is less than the cylindrical vessel
radius R1, so that the scrapers 63 as a result only act
on the lower screen 23 and do not cause undesired wear on
the vessel inner wall.
According to the detail of the longitudinal view
of the agitator shaft 7 shown in Fig. 7, the stirrer arms
8 can advantageously also be mounted on the shaft 8 [sic]
twisted by an angle y. Such a twisting of the stirrer
arms causes a blade effect similar to a ship's screw and
thus an axial advance in parallel to the longitudinal
axis of the agitator shaft 7. If, for example, the
agitator shaft 7 is rotated in the direction of the arrow
e, the material 13 is transported in the direction of
flow g. If the direction of rotation is changed to accord
with the arrow f, the material is shifted in the direc-
tion of the arrow h. The direction of rotation of the
agitator shaft 7 can therefore cause a forward or
backward thrust of the material by the stirrer arms
twisted in the shape of a propeller.
With certain material compositions, this above-
described effect is required for back-mixing and inocu-
lation of fresh material 12 with the reactor material 13.
The invention is not restricted to the exemplary
embodiment shown and described. Rather, it also includes
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developments which can be made by those skilled in the
art within the scope of the patent claims.
