Note: Descriptions are shown in the official language in which they were submitted.
_. ~~~E~:a;''
GL-1C
PROCESS FOR PREPARING ORGANIC
COMPOST FROM MUNICIPAL REFUSE
Field of the Invention.
A process for preparing high-quality organic compost material
from municipal refuse material is described. In this process, the
municipal refuse material is contacted with earthworms, earthworm
castings, and moisture under controlled reaction conditions.
Description of the prior art.
It is well known that organic compost material which contains
a substantial amount of available water is a desirable commodity.
Processes for readily converting garbage into organic compost
materials are known to those in the art, but the products they
produce generally suffer from major disadvantages. Thus, for
example, United States patent 4,108,625 discloses a process in
which waste cotton is fermented for four months and then contacted
with earthworms for one month; the product produced by this
process only contains about 36.5 weight percent of moisture.
Thus, for example, United States Patent 4,501,604 discloses a
process in which a fermented mixture of animal excrement and wood
is mixed with crushed animal carcass, such mixture is allowed to
ferment for two months, the fermented mixture is then mixed with
earthworms, and such mixture is maintained under specified
conditions for 9 months. The product obtained in this latter
patent has a moisture content of 43.5 weight percent.
It is an object of this invention to provide a process for
converting municipal refuse into a high-quality organic compost
material.
1
2
~030~~2.
Summary of the Invention
In accordance with this invention, there is
provided a process for converting municipal garbage
into organic compost material.
s According to an object of an aspect of the present
invention there is provided a process for preparing an
organic compost material with a water content of from
about 45 to about 92 weight percent, a carbon content
of from about 27 to about 85 weight percent (by weight
io of dry compost material), a pH of from about 6.2 to
about 8.0, and a particle size distribution such that
substantially zero percent of the particles in the
compost material are greater than about 2.0 inches,
from about 0.5 to about 35 weight percent of the
i5 particles in the compost material are greater than 1.0
inch, from about 0.5 to about 35 percent of the
particles in the compost material are less than 1.0
inch but greater than 0.25 inches, and at least about
50 weight percent of the particles in the compost
2o material are smaller than about 0.25 inches, comprising
the steps of:
a. providing a shredded refuse material, wherein:
1. said shredded material has a particle size
such that substantially all of its particles
2s are smaller than 5.0 inches;
2. said shredded material is comprised of from
about 5 to about 96 weight percent of a
cellulosic material selected from the group
consisting of alpha-cellulose, beta-
3o cellulose, gamma-cellulose, and mixture
thereof;
3. at least about 20 weight percent of said
cellulosic material in said shredded material
is wood cellulose with a degree of
35 polymerization of less than about 900;
2a
b. adding a sufficient amount of water to said
shredded refuse material to saturate it with
water;
c. providing an earthworm material which is a mixture
s of earthworm castings and a material selected from
the group consisting of earthworms, earthworm
eggs, and mixtures thereof;
d. contacting said saturated shredded refuse material
with said earthworm material to form a compostable
io mass of material which consist from about 20 to
about 2,000 pounds of earthworm castings and from
about 1 to about 100 pounds of earthworm material
selected from the group consisting of earthworms,
earthworm eggs, and mixtures thereof, for each ton
15 of saturated, shredded refuse material in said
compostable mass;
e. for at least about the first thirty days after
said compostable mass has been formed, maintaining
the water content in said compostable mass at a
2o concentration of at least about 80 percent by
adding water to said compostable mass; and
f. subjecting said compostable mass to a temperature
of from about 0 to about 54 degrees centigrade
while maintaining the water content in said
2s compostable mass at a concentration of from about
45 to about 92 weight percent for from about 4 to
about 8 months.
According to another object of an aspect of the
present invention there is provided a process for
3o preparing an organic compost material, comprising the
steps of:
a. providing a refuse material with a moisture
content of from about 5 to about 40 weight percent,
wherein:
A
2b (I~~~~~2
1. said refuse material has a particle size such
that substantially all of its particles are
smaller than 2.0 inches;
2. said refuse material is comprised of from
s about 1 to about 50 weight percent of a
cellulosic material selected from the group
consisting of alpha-cellulose, beta-
cellulose, gamma-cellulose, and mixture
thereof;
io b. adding a sufficient amount of water to said refuse
material to saturate it;
c. providing an earthworm material which is a mixture
of earthworm castings and a material selected from
the group consisting of earthworms, earthworm
i5 eggs, and mixtures thereof.
d. contacting said saturated refuse material with
said earthworm material to form a compostable mass
of material which consist from about 20 to about
2,000 pounds of earthworm castings and from about
20 1 to about 100 pounds of earthworm material
selected from the group consisting of earthworms,
earthworm eggs, and mixtures thereof, for each ton
of saturated, shredded refuse material in said
compostable mass;
2s e. for at least about the first thirty days after
said compostable mass has been formed, maintaining
the water content in said compostable mass at a
concentration of at least about 80 percent by
adding water to said compostable mass; and
3o f. subjecting said compostable mass to a temperature
of from about 0 to about 54 degrees centigrade
while maintaining the water content in said
compostable mass at a concentration of from about
45 to about 92 weight percent for from about 3 to
3s about 6 months.
2c
Description of the drawing
The present invention will be more fully
understood by reference to the following detailed
description thereof, when read in conjunction with the
s attached drawings, wherein:
Figure 1 is a flow sheet illustrating a preferred
process of the invention.
Description of the preferred embodiments
In the preferred process of this invention, a
to specified mixture of worms and refuse material is
provided. This preferred process of this invention is
illustrated in Figure 1, which is a flow diagram.
Referring to Figure l, a specified starting
material is charged to hopper 10. The starting
i5 material preferably contains from about 5 to about 96
weight percent, by dry weight, of a cellulosic material
c A ~ A r~ i- c~ rl f r rim t h o r~. r !. , , ,-. .. ...., '. . ., ~ : .,.
.,. ~. r _ i ~ L _
A
a-, n c,
ff ~~~~~~~
cellulose, beta-cellulose, gamma-cellulose, and mixtures thereof.
The term dry weight, when referring to the starting material,
refers to the composition of the material minus the moisture in
it. It is preferred that from about 10 to about 70 percent, by
dry weight, of the starting material be comprised of said
cellulosic material. It is more preferred that the starting
material comprise from abut 20 to about 60 dry weight percent of
said cellulosic material.
The forementioned forms of cellulose are described in, e.g.,
F. D. Snell and L. S. Ettre's Encyclopedia of Industrial Chemical
Analysis", Volume 9 (Interscience, New York, 1972),
A substantial amount of the cellulosic material in the
starting reagent is primarily wood pulp. As is known to those
skilled in the art, wood pulp is comprised of alpha-, beta-, and
gamma-celluloses in the ratios from about 85.9 to about 98.2
weight percent of alpha-cellulose, from about 0.7 to about 5.9
weight percent of beta-cellulose, and from about 1.1 to about 13.3
weight percent of gamma-cellulose. In this wood pulp, the weight/
weight ratio of alpha-cellulose to gamma-cellulose is from about
6.6 to about 89.09.
At least about 20 percent of the cellulosic material in the
starting reagent is wood cellulose with the composition described
above and with a degree of polymerization less than about 900.
The degree of polymerization can be determined by means well known
to those skilled in the art; see, e.g., J.P. Casey's "Pulp and
Paper: Chemistry and Chemistry Technology," Third Edition, Volume
I (Wiley-Interscience, New York, 1980). Cellulosic materials with
a substantially higher degree of polymerization will take too long
a .
to degrade.
In addition to containing said cellulosic material, the
shredded refuse material often also contains from about 4 to 95
weight percent (on a dry basis) of a putrescible non-cellulosic
material (such as, e.g. xylan, glucomannan, galacgan, araban, and
other saccharides and polysaccharides) or a non-putrescible, non-
cellulosic material. As is known to those skilled in the art,
non-putrescible material is material which will not putrify when
in the presence of moisture, earthworm castings and earthworms
and/or earthworm eggs. Some suitable non-putrescible materials
include glass materials, plastic materials, metallic materials,
rubber rocks, and the like.
In the process of this invention, a specified amount of
earthworm material is used; the earthworm material is usually
comprised of a mixture of earthworm castings and either earthworms
and/or earthworm eggs. This earthworm material is mixed with or
contacted with the shredded refuse. In the embodiment where the
earthworm material is placed on top of the shredded reuse, the
activity of the earthworms will cause a mixing of the materials so
that a substantially homogeneous product will be obtained after a
period of months. In another embodiment, the earthworm material
is mixed with the shredded refuse.
In general, from about 20 to abut 2,000 pounds of earthworm
castings and from about 1 to about 100 pounds of earthworms and/or
earthworm eggs are mixed with every ton (dry weight) of shredded
material. It is preferred to mix from about 40 to 1,000 pounds of
earthworm castings and from about 2 to about 25 pounds of
earthworms and/or their eggs with each ton (dry weight) of
4
shredded refuse material.
In the first step of this preferred process, municipal refuse
is fed into hopper 10. The preferred municipal refuse used is
generally a heterogeneous mixture with greatly varying properties,
sizes, and shapes. Heavy items in the waste often include glass,
metals, rock, leather, rubber, and dense plastics. Light items in
the waste often include yard waste, food waste, and paper.
In one embodiment, the municipal refuse is comprised of both
organic and inorganic components. In general, from about 69 to
about 100 percent of the refuse is organic.
The municipal refuse usually will comprise from about 59 to
about 73 percent, by total weight of refuse, of light organic
material such as, e.g., paper, plastics, textiles, and other low
density materials. The refuse will also often comprise from about
3 to about 8 percent, by total weight of refuse, of heavy
combustible organic material such as, e.g., corrugated paper,
heavy plastics, textiles, wood, leather, rubber, and other organic
matter. In addition, the refuse will often contain from about 7
to about 12 percent, by total weight of refuse, of light waste
such as, e.g., small particles of food waste, animal waste and
litter, and lawn waste and garden waste.
To the extent that there is inorganic material in the
municipal refuse, the refuse will often comprise about 0 to about
0.4 percent of heavy ferrous metals (such as engine blocks,
appliances, piping, angle irons, casting, and other massive
ferrous materials), and/or from about 3 to about 8 percent of
light metals (such as tin cans, nails, bottle and jar caps, and
miscellaneous scrap metal), and/or from the 0.01 to about 0.1
._. ~.~ Y .d i ~i
percent of heavy non-ferrous metals (such as copper-based and
zinc-based alloys), and/or from about 0.01 to about 0.4 percent of
aluminum (such as, e.g., shredded aluminum can stock), and/or from
about 1 to about 9 percent of glass, and/or from about 2 to about
percent of sand (derived from, e.g., free-flowing fine ceramics,
bricks, stones, and other easily pulverized materials.
By way of illustration and not limitation, organic
constituents present in municipal refuse may include
carbohydrates, starches, amino acids and other simple, water
soluble structures, and the more complex hemicelluloses,
celluloses, proteins, fats, oils, and waxes.
From hopper 10, the municipal refuse is passed via line 12 to
refuse recycle processing plant 14. These plants 14 are well
known to those skilled in the art and are referred to, e.g., in an
article by Glaub, Diaz, and Savage entitled "Preparing Municipal
Solid Waste for Composting," Biocycle, November 12, 1984, the
disclosure of which is hereby incorporated by reference into this
specification.
In processing Plant 14, the refuse is preprocessed, i.e., the
compostable fraction of the refuse is preferably segregated, size-
reduced, and air-classified. In the segregation step, the heavy
ferrous metal components of the refuse are removed with a magnet.
In the size reduction step, the refuse from which the heavy
ferrous metal components have been removed in ground and chopped
to an average size of from about 0.5 to about 10 inches. In the
air-classification step, heavy inorganic materials (such as rocks
and glass) are separated from the refuse. As a result of these
segregation, size-reduction, and air-classification steps, a
6
G':, a"o a f'~, P , ~.~
fa ~ F ~a ;.!
product may be produced which has an average particle size of from
about 0.5 to about 10 inches and is comprised of at least about 95
percent, by weight, of organic material.
The heavy ferrous metal components and the heavy inorganic
materials, which are removed from the refuse in processing plant
14 are fed via line 16 to hopper 18. The remaining product, which
is comprised of at least 95 weight percent of organic material, is
fed via line 20 to shredder 22, in which the particle size of the
material may be further reduced so that it is from about 0.5 to
about 5.0 inches and, preferably, from about 0.5 to about 3.0
inches. The term "shredder," as used in refuse processing, refers
to a size reduction device and includes, e.g., horizontal
hammermills, vertical hammermills, flail mills, pulpers, and shear
shredders.
In one alternative embodiment, hopper 26 is comprised of
source-separated household refuse such as, e.g., cardboard,
plastics, paper, food wrappers, leaves, lawn clippings, wood
products, tree-trimmings, and the like. In this embodiment, such
source-separated household refuse is fed via line 24 to shredder
22 where it may be mixed with organic matter from plant 14 or,
alternatively, used as the sole material in shredder 22.
The shredded material from shredder 22 is then passed via
line 28 to a screen to insure that substantially all material has
a particle size less than 5 inches. The oversize material is
recycled via line 32 to line 24 to shredder 22.
The shredded, screened material is then transported to a
field and charged to vessel 34 in which it is thoroughly saturated
with water. A sufficient amount of water is added to vessel 34 to
7
saturate the shredded and screened material, and the saturated
material is then placed onto a bed.
As used in this specification, the term "saturated" refers to
a material which contains at least about 45 weight percent of
water, by total weight; the water content can be determined by a
test described elsewhere in this specification. It is preferred
that the saturated material contain from about 45 to about 92
weight percent of water. In one embodiment, the water content of
the material is maintained at least about 80 weight percent for
the first 30 days of the process.
At this point in the process, one has the option of placing
the shredded, saturated material onto a closed bed or an open bed.
A closed bed is one which does not allow water to seep out of its
bottom or sides. The shredded material is usually placed in a pit
in the ground, a construction of loosely-fitting wooden boards, a
construction of concrete blocks stacked together, or any other
construction which allows a substantial amount of moisture to seep
through the bottom or sides of the bed.
In one embodiment, the organic compost material produced by
applicant's process with a closed bed, after it has been washed,
has about 55 to about 350 parts per million of total soluble salt
content and has an as-washed pH which is no greater than 0.4 pH
units less than its unwashed pH. By comparison, the organic
compost material produced by the open bed process, after washing,
generally is comprised of from about 20 to about 150 parts per
million of total soluble salt content and has an as-washed pH
which, for any given starting pH, will be less than that which
exists for the comparable closed bed product.
8
' .t
The saturated material from vessel 34 may be fed to either
new bed 36 and/or to old bed 38 via lines 40 and 42.
New bed 36 generally has no decomposed waste material in it
prior to the addition of the saturated material from vessel 34.
This saturated material is fed to new bed 36 and spread to a depth
of from about 2 to about 5 feet. It is preferred that the bed be
from about 3 to about 5 feet wide and any suitable length such as,
e.g., from about 4 to about 500 feet. In one embodiment, the
width of the bed is about 4 feet and the length of the bed is
about 18 feet.
Old bed 38 generally contains decomposed waste material which
usually has been derived from saturated material from vessel 34
and/or comparable saturated material from one or more other
sources. In this old bed, which contains composed material and
castings from earthworms, the saturated material from vessel 34 is
spread to a depth of from about 0.5 inches to about 3.0 feet and,
preferably, from about 1.0 to about 2.0 feet. As with the new
bed, the width of this bed is preferably from about 3 to about 5
feet (and, more preferably, about 5 feet), and the length of the
bed is from about 4 feet to about 500 feet (and more preferably is
about 18 feet.
As is known to those skilled in the art, the term "castings
from earthworms" refers to excreted matter from earthworms and is
generally comprised of microorganisms, inorganic minerals, and
organic matter in a form available to plants. These castings also
contain enzymes such as proteases, amylases, lipases, cellulases,
and chitinases.
Means for producing earthworm castings are well known to
9
c~.?~ ~ f.
~f~~_~~.~i,~t
those skilled in the art and are disclosed, e.g., in: (1) R.E.
Gaddie, Sr., and D.E. Douglas' "Earthworms for Ecology and
Profit," Volumes 1 and 2 (Bookworm Publishing Company, Ontario,
California, 1977); (2) Lunt, H.A. and Jacobsen, H.G.M., "The
Chemical Composition of Earthworm Casts," Soil Science 58(6): 367-
375; and (3) the publications listed on pages 253-254 of Volume 2
of Gladdie and Douglas' "Earthworms for Ecology and Profit."
The earthworm castings, which generally are produced in an
established bed, are transferred from earthworm source 44 via line
46 to new bed 36 and old bed 38. In general, castings are placed
on top of new bed 36 to a depth of from about 1 inch to about 5
inches, and preferably to a depth of from about 2 to about 4
inches. Castings are placed on top of old bed 38 to a depth of
from about 0.5 to about 5.0 inches and, preferably, from about to
about 2 inches. The purpose of spreading the earthworm castings
on top of these beds is to prevent them from smelling.
Boy 48 represents a means for monitoring the moisture in beds
36 and 38. The moisture in beds 36 and 38 should be maintained at
a level sufficient so that the bed contains from about 45 to about
92 weight percent of water and, preferably, from about 50 to about
80 weight percent of water. In one preferred embodiment, during
the first 30 days the mixture of castings and saturated material
is in the bed, its moisture content is maintained at a level of at
least about 70 weight percent of water.
The moisture content of the material in the bed may be
evaluated by means well known to those skilled in the art. Thus,
for example, one may use A.S.T.M. E7909-81 ("RESIDUAL MOISTURE IN
A REFUSE-DERIVED FUEL ANALYSIS SAMPLE"). In this test, a sample
_"
of the material is placed in a "referee type" drying oven which is
constructed so as to have a uniform temperature within the
specimen chamber, have a minimum excess air volume, and be capable
of constant temperature regulation at a temperature of 107 plus or
minus 3 degrees centigrade; such a drying oven is described at
section 6.1.1 of A.S.T.M. E790-81 and is illustrated in Figure 1
of A.S.T.M. Method D 3173. In the procedure described in A.S.T.M.
test E790-81, the sample is charged into a container, which is
then covered. Thereafter, the covered container containing the
sample is weighed, the cover is removed, and the uncovered sample
is heated in the referee oven at a temperature of 107 plus or
minus 3 degrees for one hour. The sample is then removed from
the oven, covered, and cooled in a dessicator oven dessicant. The
covered container is then weighed, and the percent moisture in the
sample is then calculated by the formula:
$ M = W - D x 100
W
wherein $ M is the percent moisture in the sample, W is the weight
of the undried sample, and D is the weight of the dried sample.
In the process of this invention, after the earthworm
castings are added to the bed comprised of the refuse material,
the mixture of castings and refuse material is maintained for a
period of from about four to about eight months at a moisture
content of from about 45 to about 92 percent and at a temperature
of from about 0 to about 54 degrees centigrade. It is preferred
to subject the material to these conditions for a period of from
about five to about seven months. The time the material is
subject to these conditions is critical. If the reaction time is
11
t~ ~ C
less than four months, a relatively low yield of the product
with the desired moisture content and particle size distribution
will be obtained. If the mixture is maintained under the
specified conditions for more than eight months, the product
obtained will show a decrease in its moisture content when it is
removed from the bed and subjected to ambient conditions.
In one preferred embodiment, the moisture content of the bed
is maintained at from about 50 to about 80 weight percent of water
while its temperature is maintained at from about 50 to about 32
degrees centigrade.
Any means known to those skilled in the art for monitoring
moisture may be used in applicant's process. Thus, by way of
illustration and not limitation, one can use the capacitance
method, the resistance method (conductance), the Karl Fischer
method, the electrolysis method, the dew-point method, and the
like. These methods, and the apparatuses which are utilized with
them, are describe don pages 22-52 to 22-56 of Robert H. Perry and
Cecil H. Chilton's "Chemical Engineers' Handbook," Fifth edition
(McGraw-Hill Book Company, New York, 1973). Chapter 22 of this
book, which relates in general to process measurement and process
control, appears at pages 22-1 to 22-148.
Lines 50 and 52 extend from beds 36 to 38 to measuring means
48. If insufficient water is present in either bed 36 and/or 38,
additional water is added to one or both of these beds via lines
54 and 56.
One of the functions of the moisture in beds 36 and 38 is to
maintain the temperature of these beds within a specified range.
It is preferred that the temperature of the bed, at the midpoint
12
F
of its width and depth, be from about 0 to about 54 degrees
centigrade and, more preferably, from about 0 to about 38 degrees
centigrade. In another embodiment, the temperature of the bed is
maintained at from about 0 to about 21 degrees centigrade. In
addition to measuring the moisture content of the material in the
bed, or as an alternative thereto, one can measure the
temperature of the bed at its midpoint to insure that it is within
the desired range.
The temperature in each of beds 36 and 38 is monitored by
temperature measuring means 58 which is connected to such beds by
lines 60 and 62. Any of the temperature measuring means known to
those skilled in the art can be used in this process. By way of
illustration and not limitation, one can use thermocouples,
resistance thermometers, liquid-in-glass thermometers, and the
like.
The chemical composition of each of beds 36 and 38 may be
monitored by analytical means 64, which is connected to beds 36
and 38 by line 66 and 68. Analytical means 64 measures the
organic/inorganic ratio of the organic compost in the bed; when
this ratio is from about 0.33 to about 1.5, the composting process
is finished and compost may be discharged from one or both of the
beds to screen 70. Analytical means 64 also can be used to
measure the carbon/nitrogen ratio of the compost in the beds. It
is preferred that this carbon/nitrogen ratio be from about 2 to 9
about 10. Standard methods of elemental analysis may be used to
measure such ration.
In order to maintain the depths of beds 36 and 38 at from
about 1 to about 5 feet, additional material may be added from
13
vessel 34 to bed 36 and/or 38. Means for monitoring the depths of
beds 36 and 38 (not shown) may be used in the process.
When the compost in the beds is mature, it is discharged from
the beds to screen 70, via lines 72. Screen 70 is usually a 12.7
millimeter screen, although coarser screens (up to about 1.0
inches) or finer screens (down to about 6.35 millimeters) can also
be used. Oversize material (which is often comprised of plastic
material), any undecomposed organic or inorganic material, and the
like, is passed via line 74 to air classifier/separator 76. Air
classifier/separator 76 separates the oversize material into a
light plastics fraction and a heavy, undecomposed organic and
inorganic fraction. The light plastics fraction is passed via
line 78 to washer 80, where the plastic material is subjected to a
light water wash and then passed via line 82 to drier 84, wherein
it is dried to a moisture content of from about 0 to about 25
percent, by weight. Thereafter, the dried plastic material is
passed via line 86 to storage, for sale. The heavy undecomposed
organic and/or inorganic fractions) are passed via line 88 to
separator 90. In separator 90, the heavy fractions(s) are
submerged in water. The portion of the slurry which settles
consists primarily of metal and/or other inorganic materials; this
portion is passed via line 92 for further processing to separate
out the metals and inorganics by known techniques such as, e.g.,
that described in Biocycle, page 20 (4), 1983.
The undersized material which passes through screen 70 is
comprised of earthworm castings and earthworms. It is preferred
that screen 70 be so constructed that the earthworms are passed
via line 94 to bin 96 (where they may be further processed before
14
_'
being marketed) and the earthworm castings are passed via line 98
into earthworm source 44.
In one alternative embodiment, the heavy organic/inorganic
material from separator 88 is passed via line 91 and 100 to bin
18. In this embodiment, the materials in bin 18 are submerged in
water. The materials that float or that are suspended in water
are passed via line 102 to shredder 22. The materials that
settle out of the slurry are fed vial line 104 for further
processing.
The organic compost material of the invention.
The organic compost material produced by the process of this
invention is preferably comprised of from about 45 to about 92
percent, by weight, of water. It is preferred that the compost
material comprise from about 50 to about 80 weight percent of
water. In one embodiment, the compost material comprises at least
70 weight percent of water.
The particle size distribution of the organic compost
produced by the process of this invention is relatively fine.
This is advantageous inasmuch as a relatively fine particle size
distribution allows plants in said material to adsorb more
nutrients, adsorb more water, and be aerated by more air.
The particle size distribution of the organic compost
produced by the process of this invention can be determined by
means well known to those skilled in the art. Thus, e.g., one
can use the particle size measurement techniques described on
pages 8-4 to 8-8 of Perry and Chilton's "Chemical Engineers'
Handbook," Fifth Edition (McGraw-Hill Book Company, New York,
1973).
f~~~~~~
In general, substantially none of the particles in the
organic compost material are larger than 2.0 inches. From about
0.5 to about 35 weight percent of the particles in the organic
compost material have a size in the range of from about 1.0 inches
to about 2.0 inches. From about 0.5 to about 35 weight percent of
the particles in the organic compost have a size in the range of
from about 0.25 inches to about 1.0 inches. At least about 50
weight percent of the particles in the organic compost material
have a particle size less than about 0.25 inches. It is preferred
that at least about 60 weight percent of the particles in the
compost material have a particle size less than about 0.25 inches.
In one preference embodiment, the organic compost material
has a particle size distribution such that at least 70 percent, by
weight, of its particles are smaller than about 0.25 inches. it
is more preferred to have at least 80 weight percent of the
compost particles be smaller than about 0.25 inches, and it si
even more preferred to have at least about 90 weight percent of
the compost particles be smaller than about 0.25 percent.
The organic compost material produced by the process of this
invention possesses a pH which is suitable for most agricultural
uses. The pH of the compost material produced by the process of
this invention is from about 6.2 to about 8.0 and, preferably,
from about 7.0 to about 7.9. pH may be determined by conventional
means. Thus, e.g., 100 grams of the organic compost material may
be mixed with sufficient water to make up 1,000 milliliters, and
the pH of the mixture may then by determined by conventional
means.
The carbon/nitrogen ratio for the organic compost material
16
~~~~~'~
produced by the process of this invention is usually from about 5
to about 20. The test for determining the carbon/nitrogen ratio
of an organic compost is described in an article by Hirai,
Chanyasak, and Kubota entitled "A Standard Measurement for Compost
Maturity," which appeared in the November 12, 1983 issue of
Biocycle at pages 54-56.
In one embodiment, the carbon/nitrogen ratio for the organic
compost material is from about 8 to about 15.
The organic compost material of this invention preferably has
an organic/inorganic ratio of from 0.33 to about 1.5. The
organic/inorganic ratio of the organic compost material is
determined by a test in which a sample of the organic compost
material is first oven dried at 105 degrees centigrade until its
weight is stable, the oven dried material is then weighed, and
then the oven dried material is tested for percent ash in
accordance with A.S.T.M. Test D-3174-82. The amount of organic
material in the oven dried sample is deemed to be the original
weight of the oven dried sample minus the weight of ash. The
ratio of the weight of the organics/weight of the ash is then
calculated.
In one embodiment, the ratio of organic matter/inorganic
matter is the organic compost material is from about 0.6 to about
1Ø In another embodiment, said ratio is from about 0.7 to about
0.9.
The plastic component of the product of the invention.
The process of this invention may be utilized to produce
several useful products, one of which may be a "plastic component"
which contains little or no ash, relatively little water, and a
17
'! "
_elatively high heat content.
The plastic component which can be produced by the process of
this invention contains little or no ash content. As used in this
specification, the term "ash content" refers to the percentage of
incombustible material in the fuel; it is that portion of a
laboratory sample remaining, after heating under standard
conditions to constant weight until all the combustible material
has been burned away. Means for determining the ash content of a
fuel are well known to those skilled in the art. Reference may be
had, e.g., to A. Nelson's "A Dictionary of Mining," (Philosophical
Library , New York, NY, 1965). Reference also may be had to
A.S.T.M. Test D-3174-82, "Test Method for Ash in the Analysis
Sample of Coal and Coke.
The plastic component which can be produced by the process of
this invention usually will contain from about 0 to about 17
percent, by weight, of ash. In one embodiment, the plastic
component contains from about 9 to about 17 percent of ash. In
another embodiment, the plastic component contain from about 12 to
about 15 percent of ash.
The plastic component, in addition to containing little or no
ash, also contains relatively little water. Means for determining
the amount of water in such a component are well known to those
skilled in the art. Reference may be had, e.g., to A.S.T.M. Test
D-3178-851, "Test Method for Moisture in the Analysis Sample of
Coal and Coke.
The plastic component is usually comprised of from about 0 to
about 25 percent, by weight, of water, and, preferably, from about
0 to about 22 weight percent of water. It is most preferred to
18
~~ It ,r.
t~ i~',~
have from about 0 to about 20 weight percent of water in the
plastic component.
The plastic component generally has a relatively high heat
value. The heat value of the plastic material may be determined
by, e.g., A.S.T.M. Test D-3286-85, "Test Method for Gross Caloric
Value of Coal and Coke by the Isothermal Bomb Calorimeter." Said
plastic material usually has a heat value of from about 4,800 to
about 20,000 British Thermal Units (b.t.u.'s) per pound. In one
embodiment, the heat content of the plastic material is from about
5,700 to about 12,000 b.t.u.'s per pound. In another embodiment,
the heat content of said material is from about 6,800 to about
8,000 b.t.u.'s per pound.
One of the unique features of the process of this invention
is that it is capable of producing a plastic product with a high
"combustible quotient." The term "combustible quotient", as used
in this specification, refers to the ratio of the caloric content
of the plastic component divided by the sum of the ash content and
the water content of the plastic material. To determine this
quotient, one first determines the ash content, the water content,
and the heat value of said plastic component by A.S.T.M. Tests D-
3174-82, D-3173-85, and D-3286-85, respectively. Thereafter, one
adds the ash content and the water content to obtain the total
percent of incombustible material in the plastic. This total
percent of incombustible material is then divided into the heat
content of the plastic material to give one the combustible
quotient (in b.t.u's/pound-percent).
In general, the combustible quotient of said plastic
component is from about 100 to about 2,000. In one embodiment,
19
said quotient of the plastic material is from about 200 to about
700.
The term "plastic component" (or "plastic material"), as used
in this specification refers to a synthetic organic polymeric
material. The term "organic," as used in this case, refers to a
carbon-containing material. The term "poymeric material" refers
to any substance composed of very large molecules which consist
essentially of recurring, long-chain structural units. By way of
illustration, some plastic materials include poly (ethylene
terephthalate); linear polyamides such as, e.g., nylon;
polyacrylamides; sarans; polyethylenes; polypropylenes;
polyacrylonitriles; and the like. Polymleric materials are
described in B. Golding's "Polylmers and Resins" (D. Van Nostrand
Company, Inc., Princeton, New Jersey, 1959).
In one embodiment, the process of this invention is capable
of producing a unique mixture of plastic material and organic
compost which is usually comprised of from about 0.1 to about 50
percent of plastic material and from about 50 to about 99 percent
of organic compost, by combined weight of plastic material and
organic compost. It is preferred that this mixture be comprised
of from about 1 to about 20 weight percent of plastic material and
from about 80 to about 99 weight percent of organic compost. In
determining the relative percentage of organic and plastic
material, one follows a process in which the moisture content of
the mixture is adjusted to 50 weight percent; the plastic material
is then separated from the organic compost; the amounts of plastic
material and organic compost are then determined; and the
percentages of each material in the mixture, by weight of the
6:y ~-. ;:~y n x~
total of plastics and organic compost material, and then
calculated.
The following examples are presented to illustrate the
claimed invention but are not to be deemed limitative thereof.
Unless otherwise specified, all parts are by weight and all
temperatures are in degrees centigrade.
EXAMPLE 1
A new worm bed was prepared in a pit 1.0 foot deep, 8.0 feet
long, and 3.0 feet wide. Wooden sides were erected around the
bed, and they extended the height of the bed 2.0 feet about the
ground.
A 96 cubic foot sample of air classified organic refuse
("Refuse Derived Fuel", also known as "RDF") was obtained from the
Monroe County Refuse Recycle Center in Rochester, New York. This
sample comprised shredded paper, cardboard, plastics, and cloth;
it did not appear to contain metal or glass. A 1.0 pound sample
of this material was placed on a 2.0 inch screen. Gentle
agitation caused the material to fall freely through the screen.
Two other such samples were chosen at random and sifted. This
evaluation indicated that the refuse material had been
satisfactorily shredded by the Recycle Center.
The material was then saturated with water. A 10 pound
sample of the dry refuse material soaked up 80 pounds of water.
Samples of the wetted refuse material were squeezed by hand. It
was found that, with the samples, 60 to 80 percent of the water
could be squeezed by hand out of the material.
The wetted refuse material was placed in the bed, filling the
bed to about 0.5 feet from the top (a volume of 60 cubic feet).
21
C
i.f
Castings were removed from a previously established bed which
contained several varieties of earthworms: Eisenia foetida, from
the class Annelepigeo; Allobophora calliginosa and L. rubellus,
from the class Annelendogeno; and L. terrestris, from the class
Anneldiageo. These classes of earthworms are defined in "Advances
in Ecological Research", Vol. 15, page 379 (1986).
A covering of 3 inches of castings from the previously
established bed was spread onto the surface of the new bed. The
castings contained about 3 ounces per cubic foot of castings of
mixed, young, small earthworms (approximately 400 earthworms per
ounce). There were also about 200 earthworm eggs per cubic foot
of castings. An additional 6 pound of mature Eisenia foetida and
L. rubellus worms were added to the bed. The covering of casting
successfully eliminated orders arising from the bed.
After two months, the bed was permeated with small
earthworms, averaging about 0.5 inches in length and weighing
about 200 worms per ounce. The mature earthworms which had been
added at the start of the experiment were evenly distributed
throughout the bed. Visual examination indicated that some
decomposition had occurred, but not to any great extent.
After six months, the material appeared to be completely
composted. A sample was sifted through a 1/2 inch screen. The
material which passed through the screen comprised plastics,
compost, and earthworms. There were some pieces of wood present,
but not sign of paper, cardboard, or food substances.
The daily morning misting was terminated, and the bed was
covered to protect it from rain and to dry it.
The dried bed material was removed from the bed and placed on
22
~A~02~2
a 1/2 inch screen. With gentle agitation, the castings rapidly
passed through the screen. The earthworms were separated from the
bed material; depending on the motion of the screen, the
earthworms were either allowed to pass through the screen or were
carried tot he edge of the screen and then dumped into a bin. The
plastics present in the material now easily separated and remained
on top of the screen. The larger worms, which were allowed to
pass through the 1/2 inch screen, were separated using a 1/4 inch
screen. The worms which separated with the plastics quickly
crawled down, away from the sunlight. An alternative method of
collecting the earthworms, which proved to be nearly as effective,
was to spread the castings onto a board in bright sunlight and to
slowly remove the top one to two inches of castings eery 15
minutes. The earthworms rapidly crawled down, away from the
light. With this process, about 12 ounces of earthworms could be
separated from the bed for every 64 pounds of castings present.
The castings were collected and evaluated. Analysis
indicated that the "dry" castings removed from the bed contained
57.4 percent moisture and 24.2 percent ash. The heat content of
the organic compost was 1690 b.t.u./lb. The pH of the composted
material, as evaluated with a Beckman pH meter, was 7.2.
EXAMPLE 2
In substantial accordance with the procedure of Example l, a
bed was constructed which was lined with plastic to retain
moisture, and was sheltered from the rain in order to control the
addition of moisture to the bed.
A sample of 48 cubic feet of RDF was saturated with water and
placed in the bed. The material was covered with three inches of
23
r
worm castings which contained only newly born (still white) worms
and earthworm eggs, all of the adult earthworms having been
removed by hand. The covering again successfully eliminated the
odor from the bed.
After two months, the bed was permeated with small worms
which were about 1/2 inch in length. The fibrous composition of
the RDF made it impractical to attempt to harvest the worms or
plastics at this stage.
The bed was maintained in a building in which the temperature
was allowed to drop to 35 degrees Fahrenheit. The bed was turned
with a pitchfork on a weekly basis.
After six months, an 84 pound batch of the material from the
bed was sifted through a 1/2 inch screen. The material readily
separated into two crude products. The organic compost material,
which passed through the screen, weighed 64 pounds. The oversize
material contained larger pieces of plastics, wood, and fibers;
this oversize material is referred to as the "synthetic mix".
The worms were separated by hand from a representative sample
of the material and were found to contain 12 ounces of worms per
64 pounds of compost, and about 3.5 ounces of worms per 20 pounds
of untreated synthetic mix.
One sample of the organic compost was evaluated without being
washed. One sample of organic material was washed once, one
twice, and one three times. Thereafter, using Spurway test
extract solutions, the pH, nitrate, phosphorus, potassium,
calcium, and soluble salt content of the samples were determined.
The results are presented below in Table 1.
24
C'p 't, r .'
~ ~~a~ ~.. a i J
Table 1
Once Twice Thrice
Unwashed Washed Washed Washed
Sample Sample Sample Sample
pH 7.5 7.9 7.9 7.9
Nitrate, ppm. 69 --- --- 5
Phosphorus, ppm. 5 --- --- 8
Potassium, ppm. 60 --- --- 35
Calcium, ppm. 100 --- --- 75
Soluble salts, ppm. 155 110 80 55
EXAMPLE 3
A worm bed was prepared by digging a pit 3 feet deep, 16 feet
long, and 4 feet wide. Around the pit was placed a 2 foot high
wooden side, making the depth of the bed a total of 5.0 feet.
Source separated household refuse, consisting of cardboard,
plastics, paper, food refuse, leaves, lawn clippings, wood
products, and tree trimmings were shredded using a 5 h.p. garden
variety shredder-chopper which generally produced 0.5 to 3.0 inch
diameter material. The shredded material was soaked in a
wheelbarrow and placed into the pit. The bed was filled to its
top, a level two feet above ground level.
In substantial accordance with the procedure of Example 1,
the bed was covered with 2.0 inches of castings. In addition, 50
pounds of mixed adult earthworms (see Example 1) were added.
The bed was kept moist using a sprinkling system which
sprayed a fine mist onto the bed every morning for 15 minutes. No
effort was made to prevent rain from falling onto the bed's
surface.
~~~~~E~~rr
After two weeks, a substantial amount of settling had
occurred. More refuse was shredded, wetted, and added as
described above and covered with castings. This process was then
continued every two weeks for the next six months, at which time
settling still occurred but did not appear to lower the bed below
the ground level. Thereafter, no further refuse was added, and
the material was permitted to compost.
The daily misting maintained the temperature of the bed at or
below 90 degrees Fahrenheit. After an additional six months
period, the only recognizable organic material was the un-
decomposed plastics and some larger pieces of wood. The material
was then sifted through a 1/2 inch screen to yield 1.5 pounds of
plastic and 15 pounds of worms per ton of castings.
A 16 ounce sample of bedding material was sifted through a
1/2 inch screen. All but about 1.5 ounces of the material passed
through the screen, some of which was plastic material. Worms
were removed from the compost material, and lumps present were
crushed by hand to determine actual particle size. The material
was again sifted using a 1/16 inch screen to give 1.7 ounces of
fine wood chips and particles and 14 ounces of a fine-grained
compost material.
The organic compost material passing through a 1/2 inch
screen was saturated by placing it in a bin of water and
thereafter by draining the material on a cotton cloth placed on a
1/2 inch screen. The material was weighed 24 hours after
draining. Then a 2 pound sample of the material was placed in a
105 degree Fahrenheit oven. Every hour a portion of the sample
was removed from the oven and weighted. When three successive
26
readings indicated a change of less than 0.1 ounce, the sample was
removed from the oven and weighed a final time. The sample
weighed 3.8 ounces. Thus it had a moisture capacity, as defined
this specification, of greater than 840 percent, and a moisture
content of 88 weight percent.
The earthworms used in applicant's process are well known to
those skilled in the art and are described in many publications
cited elsewhere in this specification. Earthworms belong to the
order Oligochaeta; they form 14 families and 1800 species. Thus,
Lumbricids include Lumbricus Terrestris (night crawlers),
Lumbricus Rubellus (redworm, red wigglers, hydrid red worm,
English red, California red, etc.) Thus, other earthworms include
Allolobophora Caligenosa (field worms), Octolasium, Diplocardia
Verrucosa (slime worms), Allolobophora Cholorotica (green worms),
Pheretime (swamp worms), and the like.
It is to be understood that the aforementioned description is
illustrative only and that changes can be made in the apparatus,
the ingredients and their proportions, and in the sequence of
combinations and process steps as well as in other aspects of the
invention herein without departing from the scope of the invention
as defined in the following claims.
27
