METHODE DE TRAITEMENT DE DECHETS URBAINS

METHOD OF TREATING GARBAGE

Abrégé anglais

ABSTRACT OF THE DISCLOSURE
The treatment and disposal of garbage is a serious
problem in many municipalities. Landfill sites are
increasingly difficult to find and often present environmental
and social concerns. A relatively simple solution to the
problem is to treat garbage from which recyclable material has
been removed by extracting liquid therefrom using pressure and
heat, destroying bacteria using heat and/or ultraviolet
radiation, compacting and baling the garbage, and finally
packaging the garbage in an airtight, impervious film of
polyethylene or another plastic. The thus packaged garbage
can readily be stacked for storage on an impervious surface
such as pavement.

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS
FOLLOWS:
1. A method of treating garbage comprising the
steps of shredding the garbage; extracting liquid from the
garbage; destroying bacteria in the garbage; compacting and
baling the thus sterilized garbage; and packaging the garbage
in an airtight plastic material for storage by stacking on an
impervious surface.
2. A method according to claim 1, including the
step of separating recyclable materials from the garbage prior
to shredding.
3. A method according to claim 1, wherein bacteria
destruction is effected by ultraviolet irradiation of the
garbage prior to liquid extraction.
4. A method according to claim 3, wherein liquid
extraction is effected by subjecting the garbage to
compression to squeeze liquid therefrom, and heating the thus
treated garbage to vaporize any remaining liquid.
5. A method according to claim 1, including the
step of passing dry air over the garbage following bacteria
destruction to cool the garbage prior to compacting and
baling.
6. A method according to claim 1, 2 or 5, wherein
said plastic material is a low density, linear polyethylene.

Description

1321 989
This invention relates to a method and apparatus for
treating waste, and in particular conventional garbage.
By conventional garbage is meant ordinary domestic,
commercial and industrial waste. The treatment of hazardous
waste is beyond the scope of the present invention.
The quantity of garbage produced by mankind,
especially in so-called developed countries has increased
exponentially over the past few decades. Ours is a larse
consumption, throw away society which generates larger and
larger quantities of waste. Disposal of such waste has long
been a problem and in some areas the problem has reached
crisis proportions.
By far the most common (and least expensive) method
of disposing of garbage is landfilling, i.e. the placing of
garbage in dumps or landfill sites. However, for the most
part such sites rapidly become filled and it is necessary to
search for other suitable sites. Because of environmental
concerns such as ground water pollution, it is increasingly
difficult to find a site acceptable to local residents,
environmentalists and other interested parties. Some
municipalities and other governing bodies have taken the
initiative by attempting to educate the public and encouraging
the recycling of portions of garbage. Other attempted
solutions to the waste problem include incineration and
composting. However, most currently used method of treating
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garbage have proven to be unacceptable for a variety of
reasons including cost and environmental safety.
The object of the present invention is to provide an
inexpensive solution to the above defined problems in the form
of a relatively simple, safe method of treating garbage.
Accordingly, the present invention relates to a
method of treating garbage comprising the steps of shredding
the garbage; extracting liquid from the garbage; destroying
bacteria in the garbage; compacting and baling the thus
sterilized garbage; and packaging the garbage in an airtight
plastic material for storage by stacking on an impervious
surface.
The invention will be described in greater detail
with reference to the accompanying drawings, both figures of
which are schematic block diagrams of preferred embodiments of
the method of the present invention. For the sake of
simplicity, whenever possible the same reference numerals have
been used in both drawings to designate the same or similar
elements.
As mentioned above, many municipalities have
encouraged or are in the process of teaching the public to
separate some recyclable waste such as newspapers, glass and
metal from garbage.
With reference to Fig. 1, this preliminary
separation step in garbage treatment is identified at 1 as the
first step in the method of the present invention. Obviously,
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if carried out by the public, this step will not form part of
applicant's method.
Assuming that recyclable material has already been
removed from the garbage, the first step of the present
inventiGn is the feeding of the material into a comminutor 2.
The comminutor 2, which is intended to break the garbage into
small pieces to facilitate subsequent treatment thereof. It
will be appreciated that it is not necessary to pulverize the
garbage, but merely to shred the garbage for increasing the
surface area thereof.
The comminuted garbage is fed by conveyor (not
shown) to an ultraviolet ray treater 3, where the garbage is
irradiated with sufficient ultraviolet light to kill all or
most of the bacteria. During this step of the method the
garbage can be agitated to expose the maximum possible surface
area to the ultraviolet light sources.
In the next step of the method, the garbage is fed
into a liquid extractor 4 defined by opposed rollers (not
shown) for subjecting the garbage to high pressures, whereby
~ liquid is extracted from the garbage. The liquid thus
extracted is subjected to distillation at 5 and condensed in a
condenser 6 for re-use or discharge into the
environment.
Any liquid remaining in the garbage is removed in a
dehydrator station 7. Dehydration is effected using heat
andcontrolled pressure. The vapour thus removed form the
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garbage is fed to the condenser 6. By subjecting the garbage
to sufficiently high heat and pressure, any remaining bacteria
are killed.
The now relatively clean garbage is fed to a
compactor and baler 8 where the garbage is compressed into
rectangular bundles. The bundles are subjected to packaging
at 9, i.e. vacuum packed in laminated, reinforced polyethylene
bags and sealed.
Finally, the sealed bags of garbage in the form of
blocks are stored on solid ground such as a paved area where
the blocks are stacked and covered to protect the bags from
the adverse effects of the sun and other weather conditions.
Obviously, the stacked blocks are easy to monitor to ensure
that no breakage occurs. Thus the likelihood of pollution is
decreased.
As shown in Fig. 2 in a second embodiment of the
invention, following the manual or mechanical preliminary
separation step indicated at 1 and shredding in the comminutor
2, liquid is extracted in an extractor 4 (a) by passing
shredded garbage between sets of rollers (not shown) where
some liquid is removed from the garbage, and (b) using heat.
In the heating step, the compressed, shredded garbage is
passed on a conveyor through a tunnel oven at a temperature of
100C. Dry air passes through the oven to remove vapour
escaping from the garbage.
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The thus treated garbage remains on the conveyor for
transporting through a chamber indicated at 3 in which the
temperature is raised to 120C using infrared or black
radiation. The chamber can be part of the tunnel oven, and is
intended to destroy bacteria. Bacteria can also be destroyed
using ultraviolet or other radiation, or by ozonation.
The garbage leaving the bacteria destruction chamber
is fed through another chamber 10 for cooling by dry air. The
cooled garbage is compacted and baled using pressure in a
baling press 8. If necessary, depending upon bale size,
weight and shape, the bales are tied or strapped before shrink
or vacuum packaging at 9 in a linear, low density polyethylene
film or bag.
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