Note: Descriptions are shown in the official language in which they were submitted.
209817~
PROCESS AND APPARATUS FOR THE BIOLOGICAL CONVERSION
OF ORGANIC MATERIAL IN BIOMASS
This invention relates generally to a process and an
apparatus for the biological conversion (composting) of
organic materials in biomass wherein the organic materials are
treated by finely comminuting and mixing them for a time in a
substantially enclosed environment.
It is known to one skilled in the art that organic materials,
in particular wastes form private households, restaurants etc.,
may be converted (composted) into reusable, valuable biomass.
It is known from DE-C-38 37 865 to compost in a drum-shaped
reaction container used together with a separate conditioning
apparatus wherein material, prior to being put into the
reaction container, is ground to a suitable particle size,
thereby allowing composting in the reaction container with a
shortened starter phase, that is, the composting is accelerated
more quickly. The advantage of having a fast acting conversion
reaction must be weighed against relatively cost-intensive
apparatus therefor, usually not suitable for stationary use in
restaurant operations and the like. It is further known from
prior art to compost in a one-step procedure with relatively
compact apparatus (DE-C-38 44 700) wherein the grinding and
mixing of the material to be treated takes place in one and the
same reactor until substantial composting is achieved. In this
regard, it is also known (DE-A-38 19 979) to accomplish
one-step composting in a rotary drum. The rotary drum may, for
example, be separated into two chambers (US patent 38 37 810;
DE-A-40 00 916) thereby allowing alternating operation so that
smaller batches may be processed. One-step batch composting
entails a comparatively long treatment period due to a
3S necessarily long starter period for each batch even when, as
already suggested
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(GB-C-l 022 127), the material to be treated is provided with
a suitable quantity of microorganisms for speeding up the
conversion process. Thus, a product is often thereby produced
which is unsuitable for immediate use, for example in garden
plants and the like, without further treatment. On the other
hand, apparatus of the latter kind have the advantage, due to
their compactness, that they are basically suitable for an
economical, stationary use at a place of waste creation.
It is an object of this invention to provide a process and an
apparatus as described above suitable to allow a conversion
of wastes into a reusable biomass in a shortened treatment
time period at a place of waste generation in a quasi-
continuous process. This invention is geared in particular to
an improvement of the biological conversion procedure of the
invention of German patent DE-C-38 44 700.
For a solution of this object reference is made to claims 1
and 9.
According to the invention, treatment of materials to be
composted takes place in a first chamber only until the
composting has reached a particular intermediate stage. A
portion of the material composted to this intermediate stage
is then moved into a second chamber where composting is
continued to a final stage involving the dying of
microorganisms. The portion of material composted only to the
particular intermediate stage remaining in the first chamber
ensures a high quantity of active microorganisms in this
chamber availabel for attacking further materials introduced
into the first chamber to immediately begin the process of
conversion. Thus, this invention allows, without occasional
adding of microorganisms, a continuously or quasi-
continuously composting process wherein after a certain
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starter phase continuously new material is filled into the
first chamber and partially composted material is moved from
the first into the second chamber for final composting. The
material is coninuously, or in intervals, turned over and
mixed in both chambers wherein this treatment may be combined
with a process of grinding, or comminuting the material.
Thereby, contact of waste material with surrounding air is
assured thus continuously providing the microorganisms with
sufficient oxygen for their work. The conversion, as an
exothermic process, involves development of heat which may be
used for warming air introduced into the chambers thereby
making it quite unnecessary to provide primary energy for
warming air. Also, the chambers, that is the housing, are
heat-insulated against the outer environment, thereby
allowing, in combination with the fact that the turning,
mixing and grinding of the material takes place in an
enclosed environment, the maintaining of process heat created
during conversion until the end of the reaction, i.e. for the
creation of optimal conditions of conversion in the
individual chambers. If desired, excess process heat may be
used for drying biomass from the second chamber in a third
chamber. The process of this invention allows a particularly
compact embodiment of the apparatus for its execution. A
preferred embodiment of such an apparatus comprises the two
chambers being pivotally arranged about a substantially
horizontal axis as it is known per se form the prior art. The
mixing and turning of material in the chambers can,
therefore, be performed in a particularly uncomplicated way
by means of controlled alternate (unison) turning of the
chambers. In addition, moving the material from the first
into the second chamber can be done by uncomplicated means.
According to another aspect of this invention, an apparatus
of the type in question comprising a substantially closed
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housing with an inlet and an outlet, a means for fine-
comminuting, and a means for mixing the organic materials
located in the housing, is characterized in that the housing
has at least two substantially closed housing portions
separated from each another, a first of which has the inlet
and a second of which has the outlet, that the housing is
rotatable about a substantially horizontal rotary axis, that
a connecting passage between the first and second housing
portions is provided and having a means for opening and
closing it, that the comminuting means comprises at least one
grinding device in at least the first housing portion, and
that a disengageable container unit is provided for receiving
the treated material said container unit having an inlet
opening and means for allowing detachable coupling it to the
housing, wherein the inlet opening in the coupled position of
the container unit is aligned with an outlet of the housing
in order to move treated material into the container unit
during rotation of the housing. After it is filled, the
container unit can be detached from the housing and replaced
by an empty unit, thereby allowing particularly economical
and hygienic handling of produced biomass. In this regard, a
device may be provided on the container unit, according to a
further embodiment of the invention, which allows the
coupling of several filled container units together into
transportation set which may be transported to a collection
point, in a particularly efficient manner, for example by
means of a truck.
The compactness of the apparatus makes it suitable for
immediate use at places of waste generation, for example at
restaurants and the like, for the conversion of relatively
large waste quantities into biomass without needing any
further final conditioning.
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The invention will be explained in more detail below by means
of embodiments and the drawings.
In the drawings:
Fig. 1 is a perspective, partially-schematic, view of a
biological conversion apparatus of the invention in a first
embodiment;
Fig. 2 shows the conversion apparatus as in Fig. 1 in a
longitudinal, axial, cross-sectional view together with a
schematic depiction of a control means for controlling the
functions of the conversion apparatus;
Fig. 3 depicts a modified conversion apparatus in a view
similar to that of Fig. 2, without the control means for
simplification;
Fig. 4 in a diagrammatical form showes the curves of
temperature and humidity of the conversion apparatus as in
Fig. 3;
Fig. 5 is a cross-sectional, partial view of a
conversion apparatus similar to that in Fig. 3 according to a
further embodiment of the invention, and
Fig. 6 is a perspective, partially-schematic, view of a
biological conversion apparatus according to a third
embodiment of the invention.
In Figs. 1 and 2, which depict a first embodiment of the
invention, reference numeral 1 indicates a housing and
numeral 2 indicates a pair of side frame- parts defining a
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horizontal axis 3 around which the housing is pivotally
positioned by means of the frame parts 2.
At a suitable place about the periphery of the housing 1 a
pair of openings 33, 34 is located with the openings being
axially adjacent to one another and closed by the shown
flaps.
The housing 1 preferably, as depicted, does not have a
substantially round shape, comprising, for example four
substanially smooth wall sections la-ld with adjoning pairs
of these wall sections forming funnel-shaped sump areas in
the interior of the housing 1 into which material to be
converted can accumulate when the said adjoining walls point
downwardly after rotating. However, the invention is not
limited to the embodiment of the housing 1. Rather, it can
also have a round or non-rectangular-polygonal-contour
configuration.
As Fig. 2 shows further, the housing 1 is heat-insulated
against outer environment by means of suitable insulation
material. The interior of the housing 1 is divided into two,
axially and adjoiningly positioned, housing areas or chambers
7 and 8 by a partition wall 6 extending in a radial plane
relative to the axis 3. Alternatively, two independent
housing units, heat-insulated against the outer environment,
may be arranged adjacently on the axis 3. Further, the
invention is not limited to a pair of housing portions or
housing units. Rather, further such units may be provided as
is shown, for example, in Fig. 3.
A passage or opening 9 in the partition wall 6 connects the
otherwise substantially enclosed housing areas 7,8. The
connecting passage 9 can be selectively opened or closed by
~ 7 ~ 2 098 175
means of a closure device 10. Even though other devices may
be provided, the depicted closure device is arranged in the
connecting passage 9 in the shape of a pivotal flap 10 which
may be pivoted by means of a suitable activating part 11, for
example a pneumatic piston-cylinder device, between a
position in which the connecting passage 9 is closed and a
position in which the connection between the housing areas 7
and 8 is open.
The connecting passage 9 is designed, as depicted, to be
positioned at a radially outwardly located point of the
partition wall 6, preferably near an apex of two adjoining
flat perimeter wall sections la-ld of the housing 1 whereby
material to be treated preferably accumulates in the area of
the connecting passage 9 when the connecting passage 9
reaches a downwardly-facing position after rotation of the
housing 1.
At a radially outwardly positioned place, for example
diametrically across from the connecting passage 9, a
comminuting device or grinder (as used herein, a "grinder" is
a device for reducing to smaller pieces) 12, for finely-
grinding the material to be treated, is positioned in the
interior of the first housing area 7. The grinder 12 may have
any suitable structure. In this embodiment of this invention,
the grinder 12 comprises a plurality of cutting elements
arranged on a shaft in the interior of the housing area 7
arranged substantially parallel to the rotary axis 3 by means
of a bracket 14. Such a grinder is described in DE-U-87 14
138 herein referred to for further details. A shaft end
reaching outwardly from the housing 1 is coupled to a motor
13 by means of which the shaft and thereby the cutting
elements of the grinder may be set into rotary motion.
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Although the diametrical arrangement of the grinder 12 in
relationship to the connecting passage 9 is preferred, it is
understood that the grinder 12 may also be in a non-
diametrical postition to the conneting passage 9 and that
furthermore more than one such grinder 12, if desired, can be
provided in the interior of the first housing area 7.
As shown also in Fig. 2, a further grinder 16 with a motor 17
can be centrically arranged on the rotary axis 3 in the
interior of the first housing area 7. The grinder 16 is
preferably designed such that a rough comminuting of material
introduced into the housing area 7 can be performed.
Also, a grinding device can be arranged in the interior of
the second housing area 8. Such a grinder 12' with a motor
13'can have a similar structure as that of the first grinder
12 of the first housing area 7. Although the driving means of
the grinder 12' is preferably independent from that of the
first housing area 7, a common driving means for both
grinders 12 and 12' could be designed in that cutting
elements of both grinders 12 and 12' are arranged on one
mutual shaft, extending through both housing areas 7 and 8.
The housing 1 comprises trunnions 18, 18' at its sidewalls
held in bearings in the frame parts 2 for pivotal mounting it
at the axis 3. On one of the trunnions 18, 18', a driving
means is mounted comprising a driving motor 4 and a reduction
gear 5, for example in the form of a chain and sprocket, in
order to set the housing 1 into rotary motion.
Numeral 21 relates to a means for controlling one or several
functions such as the rotary movement of the housing 1, the
position of the closure element 10 of the connecting passage
9, operation of the grinders 12, 12' and 16 etc. Temperature
2098175
measuring sensors 19 and 20 respectively for recording
temperatures in housing areas 7 and 8 suppley corresponding
signals to the control means 21 for controlling the above-
mentioned functions dependent upon the measured temperatures.
The control means 21 can further be designed such that
rotating housing 1 or operating the grinders as well as the
closure element 10 of the connecting passage 9 are controlled
dependent upon time and the temperatures measured in the
housing areas 7 and 8.
Finally, it should be noted that a device is provided,
although not depicted, for intake of warmed fresh air into
the interior of one or both housing areas 7, 8 and/or for the
output of air therefrom. The warming of the fresh air is
preferably achieved by using process heat created by
conversion of material thereby making entirely or almost
entirely unnecessary any induction of energy from outside. A
fresh air intake or outlet as well as a warming device can be
designed according to DE-C-38 37 865 herein referring to that
publication for details.
The conversion apparatus, arranged as described above,
functions as follows:
Material to be treated, which can be biologically degradable
wastes of all kinds, paricularly wastes from kitchen and
restaurant operations, is introduced into the first housing
area 7 through the inlet opening 33 in a precomminuted form.
As soon as a suitable degree of filling, for example 60-70%,
is reached, the inlet opening 33 is closed and a signal is
given to the driving motor 4 for rotating the housing 1.
During the rotation, the material in the first housing area 7
is continuously turned over. Further rough comminuting the
material can, if desired, be linked to this process by means
209817S
of the central grinder 16 to make the material a particle
size suitable for further conditioning by the fine-grinder
12.
The inserted material is turned and mixed for a period of
time with continual or stepped alternating rotation of the
housing 1. Since the radially-outwardly positioned fine-
grinder 12 is moved repeatedly through the introduced
material during the rotation of the housing 1, the material
is further chewed-up to a particle size suitable for
conversion. The rough grinder 16 can be disengaged after an
appropriate period of time.
Conversion of the material in the first housing area 7 is
coupled with a rise of temperature. Due to the insulation of
the housing 1 the conversion can take place without
substantial heat loss to the surroundings. For maintaining
favorable conversion conditions for activity of
microorganisms, warmed fresh air can be allowed into the
interior of the housing area 7 continuously or from time to
time.
Conversion of the material in the first housing area 7 is
continued according to this invention only until it is noted
that the temperature has stopped rising (end of conversion-
starting phase). Immediately afterwars, or after a suitable
period of time, for example several hours, the control means
21 gives a command to the actuating member 11 of the closure
element 10 to position the closure element such that
communication between the interiors of the first and second
housing areas 7 and 8 is achieved. Herein, the closure
element 10 can work as a guide baffle wherein it may guide
material in the first housing area 7 through the connecting
- 11- 209g175
passage 9 into the second housing area 8 in the manner of a
plow.
According to this invention, not the entire quantity of
material in the first housing area 7 is moved into the second
housing area 8, but only a suitable, partial quantity,
approximately between 30% and 70% of the load of the first
housing area 7. The proportion of material moved to that
remaining may vary depending on the kind of material to be
treated. Regarding biologically degradable wastes from
kitchen and restaurant operations, it has been found that
good results are achieved by moving approximately 50% of the
material in the first housing area 7 which has been converted
to an intermediate stage.
After moving the material into the second housing area 8, the
connecting passage 9 is closed again and new, untreated
material can be filled into the interior of the first housing
area 7 through the intake opening 33 up to a desired filling
level thereby having untreated as well as partially converted
material in the housing area 7.
The composting process of the material in the housing areas 7
and 8 is continued with further mixing and rotating as well
as grinding. In particular, in the second housing area 8 the
final composting process of the introduced, partially-
composted material into biomass is performed. A measurement
for determining an end of the conversion process in the
second housing area 8 is a decrease of temperature therein
from a measured maximum. The decrease of temperature
indicates that the activity of microorganisms is slowly
ending. It has been found that the conversion can be
considered to be substantially finished and that the material
from the second housing area 8 may be removed through the
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output opening 7, when the temperature in the second housing
area 8 has decreased by about 20% from a measured maximum.
The measured maximum temperatures in the housing areas 7 and
8 depend upon the condition of and the kinds of materials to
be treated and can be, for example, between 60 and 75C.
Allowing conversion in the first housing area 7 only up to an
intermediate stage provides for continuously sufficient
quantities of active microorganisms in that housing area
which ensure that the process of conversion of new input-
material (starting phase) is begun immediately. Therefore, a
characteristic feature of the invention is seperation of the
conversion process into a starter and a final phase which
take place substantially separated from one another, that is
without mutual influence.
In some cases, it may be necessary or desirable to subject
the biomass to a follow-up drying process. This can be
achieved according to this invention by combining with the
first and second housing areas 7 and 8 a further, third
housing area as depicted in Fig. 3. The third housing area 22
can be substantially structured like the first two housing
areas 7 and 8. However, it does not need to include a
grinder. Devices (not shown) are provided for allowing warmed
air into the third housing area 22 and for releasing air
therefrom with its absorbed humidity, thereby drying the
material in the third housing area 22 as well as decreasing
its temperature at the same time.
A connecting passage 23 and a partition wall 26 with a
closure means 29, similar to that between the first and the
second housing areas 7 and 8, allow a guided moving of
composted material from the second into the third housing
area 22. Further, an output means 24 may be provided for
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2098175
moving composted, dried, material out of the third housing
area 22. The output means 24 can, as depicted, comprise a
screw conveyor 28 arranged in a cylinder housing 27
concentrically to the rotary axis 3, the conveyor being
driven by a driving motor for moving the material out of the
interior of the housing area 22 to an output opening 30.
Fig. 3 shows further a modified embodiment of apparatus
for rotating the housing 1 about the rotary axis 3 by means
of driven rolls 31 situated laterally of the housing on which
roll rims 32 connected with the housing sidewalls are
supported so that a rotation of the rolls 31 effects a
corresponding rotation of the housing 1.
Numbers 12 and 12'indicate grinders extending into the
interior of the housing areas 7 and 8 form a circumferential
side of the housing l, in a different manner than in the
previously described embodiment. Further details for the
embodiment of the invention as in Fig. 3 can be obtained by
reference to the first embodiment described above.
Fig. 4 shows curves of temperature and humidity of
material being treated in the individual housing areas 7, 8
and 22. As can be recorgnized, conversion takes place in the
first and second housing areas 7 and 8, that is during the
starter and final phases, substantially without heat loss to
the environment and with substantially even level of
humidity of material being treated. Instead of or in addition
to a drying process a sterilization of the material can be
provided in the third chamber 22.
Fig. 5 shows a further embodiment of this invention.
This embodiment is substantially distinguished from Fig. 3 in
that the third chamber is omitted; instead a disengageable
container unit 40 is provided which can be selectively
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coupled to, or engaged with, the conversion apparatus. For
further details, Fig. 3 and its description are herein
referred to. In Fig. 5 the same or similar components as
those of the embodiment of Fig. 3 have the same reference
numerals, though are provided with the prime ' designations.
The disengagegable container unit 40 comprises a basically
closed container with a circumferential configuration adapted
to, or corresponding to, that of the housing 1' of the
conversion apparatus and has an inlet opening at its front
side. The inlet opening is arranged according to the outlet
passage 23' of the second housing portion 8' and can be
aligned therewith such that upon activation of the closing
means 29' the composted material located in the second
housing portion 8' may be moved into the disengageable
container unit 40.
Although other functional devices may be provided for
temporarily connecting the engageabel unit 40 with the
housing 1', the present embodiment provides therefor two or
more socket-shaped elements 41 arranged in a suitable manner
circumferentially to the unit 40, in each of which is held a
guide pin, or peg, 42 at one end while an opposite end
thereof is open. The guide pins 42 protrude from the socket-
shaped elements 41 substantially parallel to the rotary axis
3' of the apparatus and are capable of engaging receiving
elements 43, which are designed for this purpose and are
fixed to the housing 1'. Further, suitable means (not
depicted) are provided for locking the guide pins 42 in
engagement with the receiving elements 43 in a disengageable
manner.
When the unit 40 is attached to the housing 1' and positioned
such that the inlet openting of the unit 40 is aligned with
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the outlet passage 23' of the second housing portion 8', the
housing 1' and the unit 40 coupled to it are rotated and the
closing means 29' is activated at an appropriate time for
opening the outlet passage 23' and for moving composted
material, located in the second housing portion 8', into the
unit 40. When unit 40 is filled with composted material,
operation of the conversion apparatus is temporarily
interrupted for removel of the filled unit 40 from the
housing 1' and replacement thereof with an empty one. Since
the composted material has a substantially smaller volume
than that of this material to be treated an introduced into
the first housing portion 7', operation stops for exchanging
unit 40 are required only after treatment of substantial
amounts of introduced material.
For rotation of the housing 1', in addition to its being
driven by the driven rotation means 31', 32' of the
embodiment according to Fig. 3, it is supported by an
arrangement of rolls indicated at 44, which is provided
circumferentially of housing 1', so that engagement and
disengagement of unit 40 is not hindered by the arrangement
of these rolls.
As further indicated in Fig. 5 by dot-dash lines, a handling
device 60 may be provided with pins arranged such that they
can engage free ends of the socket-shaped elements 41 of the
engageable unit 40. The unit 40 can therefore be moved, after
disengagement from the housing 1', by an operator using the
handling device 60, to a collecting point from which several
filled units 40 may be transported together, for example by
means of a truck, for further use of the composted material.
For transport, the pins 42 of a disengaged unit 40 can be
engaged with the free ends of socket-shaped elements 41 of a
neighboring unit 40 so that two or several units 40 may be
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connected into a particularly easy-to-handle attached set for
transport.
Further, it should be noted that, if desired, the engageable
unit 40 may also be used in connection with a treatment
apparatus wherein composted material is first dried or
sterilized in a third chamber according to an embodiment as
in Fig. 3, before it is moved into the engageable unit 40.
The further embodiment of the invention shown in Fig. 6 has a
substantially vertical orientation in contrast to the
previously described embodiment. It comprises a heat-
insulated housing 100 with a closable inlet opening 116 on
its frontside providing access to a first housing area 107. A
grinder 112 for fine-grinding input material is provides in
the first housing area 107. The first housing area 107 is
definded by a partition wall 106 separating the interior of
the housing 100 into two separated, substantially vertically-
elongated, housing areas 107 and 108.
In a lower portion of each housing area 107 and 108 sumps 120
and 122 are formed in which material to be treated can
accumulate. In each housing area 107 and 108, a conveyor
device is arranged in the shape of, for example, screw
conveyors 121 and 123 for moving material from the respective
sumps 120 or 122 upwards thereby moving the material from a
lower level, substantially definded by the sumps 120 or 122,
to a higher level from where it may fall back to the lower
level in free fall.
The higher level of the first housing area 107 is in
particular located next to a delivery or connecting passage
109, interconnecting the first and second housing areas 107
and 108, and the higher level of the second housing area 108
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is next to an output opening 117. The connecting passage 109
as well as the output opening 117 can be opened and closed,
controlled by suitable, not shown, closure means.
Also not shown are devices for supplying warmed fresh air
into the housing areas 107 and 108 and for controlling
operation of the grinder 112 and the spiral conveyors 121,
123 as well as for opening and closing the connecting passage
109 and the output opening 117. These devices and other
details can be constructed analogously using the described
embodiments of Fig. 1 and 2 referred to herein.
Operation of the further embodiment of the invention of Fig.
6 corresponds to that of the embodiment described above. In
particular, conversion of material to be treated is achieved
in two steps, that is by allowing conversion in the first
housing area only up to a determinate intermediate stage and
finishing it only in the second housing area 108 while
leaving a portion of partially converted material in the
first housing area 107. Thereby it is assured that there will
always be a sufficient quantity of active microorganisms in
the first housing area 107 for starting conversion of newly
introduced material with an accordingly shortening of the
treatment period. In contrast to the above described
embodiment, rotating and mixing of the material to be treated
is here effected by moving the material between places of
higher and lower levels with an interim movement phase
defined by free fall.
It is understood that the invention is not limited to the
described and shown embodiments, but includes such
alternatives and modifications available to an ordinary
person skilled in the art using the teachings herein.
