Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHOD AND APPARATUS FOR
RECLA~MI~G WASTE MATERIAL
Backqround and Summary of the Invention
The present invention relates to waste reclaiming
systems and, more particularly, to reclaiming systems which
are reusable.
Major metropolitan areas produce tons of garbage and
waste material every day. The garbage and waste material is
generally collected by sanitation departments and hauled off
to disposal sites or ~urned in costly waste to energy
conversion plants to reduce volume and generate energy. In
some instances, due to high land costs, the garbage and waste
material may be transported to another state for disposal. In
most areas, the disposal method of choice is use of a
landfill. This use of a landfill has involved simply burying
the waste. Generally, the landfills are filled with garbage
and waste material and covered over when completed. The site
is thereafter ill-suited for most purposes. Sites can also be
a source of groundwater and air pollution. Anerobic
decomposition at the site will produce contamination such as
hydrogen sulfide and methane gases. As the amount of garbage
continues to increase and the available land for landfills
diminishes, there is a need for an-alternative to long-term
dedication of ever-increasing amounts of land to landfills
that are themselves sources of pollution.
Previous landfill methods have also resulted in
concerns regarding dangerous leachates. Leachates are
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produced as the result of liquids percolating through the
wastes. Concern over leachates has caused regulation of
landfills. Current regulations require impermeable liners to
prevent leachates from contaminating groundwater supplies.
This concern demands a solution to minimize the amount of
leachate produced to afford maximum protection of the
groundwater.
Several different types of garbage and waste recovery
systems are illustrated in the art. ~enerally, these ~arbage
and waste recovery systems are illustrated by the following
patents. U.S. Patent Nos. 4,696,599, issued September 29,
1987 to Rakoczynski et al; 4,643,111, issued February 17, 1987
to Jones; 4,464,081, issued August 7, 1984 to Hillier et al;
4,350,461, issued September 21, 1982 to Valiga et al;
3,579,320, issued May 18, 1971 to Pesses; German Patent No.
3508824, issued September 18, 1986; Japanese Patent No.
61-178086, issued August 9, 1986; and Japanese Patent No.
58-33618, issued February 26, 1983. These patents disclose
different disposal systems.
The above-referenced patents, however, have several
disadvantages. One disadvantage is that the above-identified
art calls for the dedication of capital equipment at one
limited site yet does not provide for the reuse of the
components of the system. Another disadvantage is that
combustible and even potentially explosive materials such as
methane and hydrogen sulfide gas are not eliminated or
controlled. The above art does not provide for the full
reclaiming of the full range of materials after they have been
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introduced to the landfill. The above systems also produce a
substantially large amount of leachate with no mechanism to
effectively control or contain that leachate. The systems
also do not allow for easy repair of contamination paths
should one occur. The systems also require expensive
mechanisms and devices to treat the resultant leachate.
Accordingly,- it is an object of the present invention
to overcome the disadvantages of the relevant art. The
present invention provides a method which enables reuse of a
site dedicated to a landfill and also reuse of the components
within the landfill. The present invention provides for
control and use of combustible and/or harmful gases that are
given off during the decomposition of the waste material. The
present invention enables reclamation of the by-products of
the completed landfill, many of them being capable of reuse.
The present invention limits the amount of leachates produced
and provides effective use of the leachates in decomposition
of the wastes. The present invention allows for inspection of
leachate collection systems and cell liners and enables the
repair or replacement of both. The present invention also
enables continuous reuse of the landfill site instead of
covering it and rendering the land unfit for most other
purposes.
The present invention provides a method for processing
waste material whereby a cell of waste material is created,
this cell being sealed off from the surrounding environment by
means of a liner and a cover. The waste material is monitored
for decomposition and its leachate recirculated to enhance the
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decomposition. After decomposition has occurred, the
resultant material may be removed and separated into usable
fractions such as soil and recyclable metals, rubber, glass
and plastics. The empty cell may thereafter be reused for
processing another batch of waste.
From the following detailed description and claims
taken in conjunction with the drawings, other objècts and
advantages of the present invention will become apparent to
those skilled in the art.
Brief Description of the Drawings
Figure 1 is a plan view of a reclaiming landfill site
in accordance with the present invention.
Figure 2 is a perspective view of a single cell in
Figure 1 with a standing cover. The truck is not to scale
with the size of the cell as taught in the specification.
Figure 3 is a perspective view illustrating the
preparation of material for introduction into the cell in
accordance with the present invention.
Figure 4 is a plan view like that of Figure 1, with
several of the cells filled.
Figure s is a vertical cross-sectional view of a
filled cell of Figure 4 in accordance with the present
invention.
Fiaure SA is a vertical cross-sectional view of a
filled cell created above ground level.
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Figure 6 is a perspective view illustrating the removal
and separation of material from the cell in accordance with
the present invention.
Figure 7 is a plan view like that of Figure 1 with
several of the cells filled.
Detailed Description of the Preferred Embodiment
Referring to the figures, a system for handling and
reclaiming waste material is illustrated. The system
generally includes one or more cells 12-30.
For ease of explanation, the cells are arbitrarily
designated first to tenth and correspond with reference
numerals 12-30 (i.e., first reference numeral 12, second
reference numeral 14, etc.). Also, the cells are divided into
two columns. The following explanation of a slngle cell will
apply to all the cells at one time or another during the
disposal and reclaiming process. The progressive reclaiming
process stages, as will be explained herein, occur at
different times to different cells. However, all cells will
go through the below-described stages at different times
during the reclaiming process. Thus, the explanation of a
single cell will apply to all the cells.
The cells are formed in or on the ground and generally
have an overall rectangular shape, as shown in Figure 1. The
depth varies accordingly to the width and length of the cell.
Ordinarily, the first cell 12 is formed as a starting point
for the reclaiming process. The remaining second through
tenth cells may be formed at the same time the first cell is
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formed or at any point in time during functioning of the
system. A system may also consist of a single cell 12.
A liner 32, as seen in Figure 5, is positioned in the
first cell 12. Preferably, the liner 32 is formed from
materials such as high density polyethylene or the like. The
liner 32 material is selected to be satisfactory in preventing
leachate or the like from seeping through the liner into the
surrounding earth-or ground water from entering the cell. The
liner 32 forms to the contour of the cell 12 and is inspected
for tears or the like to insure that the liner 32 is
impermeable to liquid or the like attempting to enter or exit
the~ lined cell.
After the liner 32 has been positioned into the first
cell 12, a domed cover structure 34 is placed over the first
cell 12. The domed cover structure 34 may be an inflatable
dome or bubble with airlocks that allow a positive pressure to
be maintained to support the structure yet still allow passage
of personnel, vehicles, refuse and the like intu and out of
the cell 12. Positive pressure may be maintained by fans
powered by electricity generated from methane or other
combustible by-products of the landfill. The domed cover
structure 34 is large enough to enable trucks or the like to
pass into the cell. The domed cover structure 34 prevents
water such as rain, precipitation or the like from entering
the first cell 12 during filling of the first cell 12 with
garbage and waste material. The domed cover structure 34
controls the leachate formation during filling of the cell by
this control and/or elimination of the entry of water which
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includes precipitation during or after falling. The control
of additional moisture added to the cell during its filling
reduces the rate of decomposition of the waste, reducing the
formation of combustible or unpleasant gases, hence allowing
for more pleasant and efficient operations. The use of covers
to control the environment also denies access to undesirable
vectors such as birds or small animals.
After the liner has been positioned in the first cell
12 and checked for perforations, waste material may be added
into the first cell 12. Preferably, the garbage or waste
material is ground up by a grinder 36 as seen in Figure 3 to
reduce the formation of microenvironments. Grinding may take
the form of any method to homogenize the waste and thereby
reduce microenvironments and/or accelerate decomposition. Use
of a grinder 36 provides for a more homogeneous environment
within the cell. Microenvironments are often localized
pockets of waste whose time for bioreduction differs
substantially from the cell content as a whole. An example of
a microenvironment may be space inside an impermeable plastic
bag. It is possible that microenvironments may form in large
chunks of waste, taking additional time to decompose or
creating undesirable pockets of microorganisms.
The ground-up garbage and waste material may be added
directly into the lined first cell 12. A layer of waste
material 30 is placed in the lined cell possibly followed by
an alternating layer of cover soil 40 such as dirt,
nonbiodegradable material, partially biodegraded material or
the like as seen in Figure 5. Alternating layers of cover
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soil with garbage reduces or retards the potential for
combustion and limits the ability of combustion to travel,
much like fire breaks in a building. This process of
alternating layers of waste material 38 and cover soil 40 is
continued until the first cell 12 is full. Also, it is
possible that the garbage and waste material be added to the
cell directly eliminating the layering. Either method works
effectively to enable the decomposition or bioreduction of the
~iodegradable garbage or waste material. Bioreduction,
biodegradation, decomposition and composting are used to refer
to the action of oxygen, microorganisms and the like on
organic matter.
When the first cell 12 is full, the ratio of waste
material to cover soil can vary widely but often ranges from
about 1:5 to about 10:1; preferably from about 1:3 to about
10:1; and highly preferred at from about 1:1 to about 10:1.
As can be seen in Figure 5, the waste material 38 and
cover soil 40 are positioned into the first cell 12 until the
first cell 12 is full. Once the first cell 12 is full, a
cover 42 is placed over the first cell 12. The cover 42 is
impermeable to rain, precipitation or the like. The color of
the cover can be used to capture or reflect heat and thereby
affect the rate of decomposition. The cover 42 helps to
reduce the formation of leachate by preventing the
introduction of surface or rain water. The top of the
finished cell is flat and surrounded by a perimeter dike which
accepts additional moisture which can be introduced into the
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cell at a controlled rate depending on the desired rate of
decomposition.
Once the first cell 12 has been covered with cover 42,
the domed cover structure 34 is moved from the first cell 12
to cover the second cell 14. Conduit 44 is associated with
the first through tenth cells 12-30 for draining leachate from
the cells. Excess leachates collected from the bottom liner
(a m~imum of 12 inches is allowable) may be recirculated
through the cell. Excess leachates drained from the cells via
conduit 44 may be recirculated or processed in a leachate
treatment facility 46. Also, a conduit (not shown) is
associated with the first through tenth cells to enable water
or recirculated leachate to be passed into the cells to
control the rate of decomposition and the amount of leachate
formation. Water or recirculated leachates introduced into a
cell provides a more favorable environment for microorganisms
and hence speeds up the rate of decomposition. Genetically
engineered or selected strains of microorganisms such as
acidogens or methanigens can be seeded in the mixture to
accelerate the decomposition. Further, other conduits are
associated with the first through tenth cells to enable
removal and use of the methane produced during the
decomposition of the biodegradable waste material.
After the first cell 12 has been covered with cover 42,
it is monitored. During monitoring, water or the like may be
added to the decomposing material to accelerate its
decomposition. Thus, since the addition of water is
controlled, so is the leachate. The leachate would be
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monitored and any excess removed from the cells or
recirculated via conduit 44. The cover encapsulates the waste
and traps the gases that form. Methane gas or other
gaseous by-products of bioreduction are bled off of the cell
as the waste material decomposes. The methane gas or the like
may be used to run engines or generate electricity which
powers fans which hold up the domed cover structure 34. Thus,
the methane gas, which is produced during decomposition, is
utilized to power different machinery during the operation of
the system.
The above-identified process is started on the second
cell 14. The process is repeated and continues at all of the
cells until all the cells have been filled and covered as seen
in Figures 4 and 7.
At or about the time that the first column of cells
(first cell 12 through fifth cell 20) is filled with waste
material and cover soil, the first cell 12 should be ready for
mining or reclaiming. A cell may be considered ready when its
rate of decomposition levels off or when bioreduction is
substantially complete. Preferably, the sixth cell 22, which
opposes the first cell 12, is ready to be filled with waste
material and cover soil, as explained above. Also at this
time, the cover soil, such as dirt, is mined from the first
cell 12 to provide the cover soil of the sixth cell 22 as seen
in Figure 4.
During mining or reclaiming as illustrated in Figure 6,
the nonbiodegradable material 48 which includes metals, glass,
rubber and plastic materials which are not decomposed, is
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separated out from the humus or dirt 50 by a mining apparatus
52. Separation of materials can take the form of sifting,
shaking, screening, trom~eling, etc. The material may be
sifted or the like to separate the dirt or humus 50 from the
solid metallic, rubber, glass and plastic materials 18. The
metallic material such as aluminum, tin, copper, brass and the
like is recycled, as are the glass and rubber materials. The
plastic material such as bags, bottles and the like is
reclaimed for use as fuel or for recycling. Thus, the
recovering of material from the first cell 12 produces
valuable fractions which can be put to use. The seventh 24
through tenth 30 cells are continued to be filled as explained
above and are supplied with cover soil from the second 14
through fifth 20 cells. Thus, as the cells are filled down
the column, the opposing cell is mined or reclaimed as seen in
Figure 4.
Once the tenth cell 30 is filled, it is time to move
back to again fill the first cell 12 as seen in Figure 7. The
liner 32 in the now empty first cell 12 is inspected for tears
or perforations. If no perforations or tears appear, the
liner 32 is reused. If perforations or tears are present, and
the liner 32 cannot be repaired, the liner is replaced to
maintain its integrity against the transmission of leachates.
The domed cover structure 34 is removed from the tenth cell 30
and positioned above the first cell 12. Garbage and waste
material along with the cover soil, preferably from the sixth
cell 22 as explained above, is added into the first cell 12.
The above-identified process is again repeated. The process
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is designed to continue indefinitely. This enables the
above-disclosed landfill reclaiming site to be continually
reused. The reusability, along with being economical, does
not destroy the land nor render it unfit for future
alternative uses. Thus, the invention provides a reusable
landfill reclaiming system that may be set up in a designated
area and continued to be used and reused indefinitely all the
while controlling groundwater contamination and gaseous
emissions.
Figures 4 and 7 illustrate progressive times during the
process. In Figure 4, the first cell is being mined by a
mechanism like that of Figure 6 to provide cover soil for use
in the sixth cell 22 and other reusable materials. The second
14 through fifth 20 cells remain covered while the seventh 24
through tenth 30 are yet to be filled.
In Figure 7, the process has been completed through a
cycle. The first cell 12 is in the process of being filled
again. The second 14 through fifth 20 cells have been mined.
The sixth cell 22 is being mined to provide cover soil for the
first cell~12. The seventh 24 through tenth 30 cells are
covered while decomposition occurs.
Generally during mining or reclaiming of the cells,
there is more than enough cover soil from the mined or
reclaimed cell than is necessary for use as cover soil in the
opposing cell of the other column. This additional cover soil
results from the composting of the biodegradable material into
humus. Whereas, for example, a freshly filled cell may be 80%
new garbage and 20% cover soil, after bioreduction in the cell
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is complete, the ratio may now be 20~ of nonbiodegradable
material and 80% humus/dirt mixture. The reclaimed soil meets
most toxicological safety standards and may be sold as top
soil, humus, peat or the like. Thus, the present invention
produces a number of reusable reclaimed products.
An example of a landfill reclaiming system in
accordance with the present invention would be as follows. A
site on the order of several hundred acres would need to be
acquired. A location having dimensions of approximately
3,000 ft. x 2,400 ft. would be utilized for the cells. It is
hypothesized that a site of this size would be able to contain
approximately 7.2 million tons of waste material.
The 2,400 ft. dimension would be divided into two equal
parcels. The 3,000 ft. dimension would be subdivided into a
plurality of segments such as four or five equal segments. If
divided into five segments, the cells would therefore have
1,200 ft. x 600 ft. dimensions of a rectangular nature.
Provisions could be made for access lines to the cells. A
liner would be used having a thickness of approximately 60
mils and be manufactured from a high density polyethylene
material. A cover would be used having a 30 mil thickness and
be manufactured from a high density polyethylene material.
A leachate collection, recycling, and treatment system
would be provided. The base liner would be installed into the
first cell. The base liner would be installed t before the
addition of the waste material and cover soil into the cell.
The domed cover structure would be positioned over the first
cell to be filled prior to placement of the waste material.
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The garbage and waste material and cover soil would be ground
and deposited into the cell. Alternately, the cell could be
layered with alternate layers of garbage and waste material
and a daily cover of soil. Generally, the garbage and waste
material would make up about 80% of the material within the
filled cell. The daily cover soil makes up the remaining 20%.
However, the garbage and waste material could vary from about
10~ to about 100% of the total weight of the filled cell and
the cover soil about 0 to about 90% of the total weight of the
filled cell.
Mechanisms for withdrawing methane gases and the like
from the cell, mechanisms for adding water, recirculated
leachate, or the li~e to the cells, and mechanisms for
removing leachate from the bottom of the cell for recycling
would be coupled with the cells.
A cover would be placed over the cells once filled and
the content of the cells would be allowed to decompose. After
positioning of the cover on the filled cell, the domed cover
structure would be moved to the next cell. During
decomposition, methane or like gases would be withdrawn from
the cell and could be utilized to power fans for maintaining
the domed cover structure in an erect position over the cell
or as fuel for other needs on or off site. The filled cells
would be monitored for moisture content. Moisture content
would be adjusted to optimi7e rapid decomposition while
minimizing the amount of potential leachate. Water would be
pumped into the cell to increase the moisture content if
needed. The leachate would be monitored, controlled and, if
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necessary, removed during the decomposition period of the
waste material. This process would be repeated for all of the
cells. The process would continue so that the cells would be
continually reused. The present invention provides for a
reusable landfill with the above-mentioned advantages.
While the above describes the preferred embodiment of
the present invention, it will be understood that
modifications, variations and alterations may be made to the
present invention without deviating from the scope and fair
meaning of the subjoined claims.
