Note: Descriptions are shown in the official language in which they were submitted.
~ ~05~591
As is well known, the problem o~ disposing of
organic wastes has reached crisis proportions, Originally,
waste products from human civi]iza~ion were disposed of by
merely pourin~ them into la~es and rivers or dumping them
on unused land. However, as the human population has grown
and as civilization has become more and more complex these
are no longer suitable solutions to the problem of waste ,
disposal, because, at the present time, our rivers and
lakes have become so polluted that animal and plant life
growing therein has gradually been destroyed. Morever, such
a large amount of waste material is now being disposed of
in such a manner that even the oceans are no longer adequate
to take care of it.
In recent times many methods have ~een devised
to solve the problem of disposing of organic wastes. How-
ever, for the most part, the methods are so expensive that
so far very little has been done in solving the problem.
In addition to the pollution problem created
by the ever-growing population of the world, the excess
population has also created a need for more food material.
However, arable land is decreasing because of the loss of
topsoil, and even if arable land were not decreasing, there
would still be a need for more and more food grown on the
:
existing arable land, which, inter alia, requires increased
production of cheap and ïnexpensive fertilizers.
From the foregoing, it is apparent that it is a
- desideratum in the art to provide an inexpensive method for
aisposal of organic wastes in a way which would not pollute
the environment. Moreover, an excellent solution to the
problem of disposing of such wastes would be to utilize them
to create topsoil and/or fertilizer in order to better feed
the ever-growing population.
- The primary ob~ect of the present invention
therefore is to disclose and provide a method for easil~
. : .
cbr/~
105'~591
convertin~ organic was~es into inert materials which a~e
" easily disposed of without pollution of the environment.
Broadly stated, the present invention ~s defined
as a method of converting organic waste material into inert
material, which includes intimately admixing.organic waste
material with a water-soluble inorganic acid selected from
the group consisting of hydrochloric acid, sulfuric acid, .
and sulfur trioxide, until the acid penetrates and contacts
substantially all of the organic waste material, the ration
of acid to organic waste on a dry weight basis between about
1:30 and 1:2; and reacting the resulting mixture by heating
to a temperature between about 200 and 300F under conditions
which rapidly remove water from the reaction zone, until
said organic waste material is converted to an essentially
dry, water-insoluble black, humus-like char which is sub-
stantially insoluble in alkaline solutions below about
240F .
- Another object of the present invention is to
disclose and provide a process for compacting the diverse
organic waste materials of society, such as garbage, sewage
solids and manures, rubbish and trash, by converting the
wastes into uniform granular char products, of considerably
reduced weight and volume, which are suitable for use as
.non-polluting landfill; by reacting the organic wastes with
certain acids under drying conditions, removing residual
acid and
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cbr/J~
105Z5~1
other water-soluble cont minant~ by washin~ the resultant crude char product
with waeer (from which the acid may be recovered for re-u8e), and utilizing
ehe re8ulting inert product a8 a landfill.
Another ob~ect of the present invention is to disclo~e and provide a
method for disposing of organic wastes which includes converting said organic
wastes into the alkali salts of humic-acid-like material8 and mixing ssid
humic-acid-like materials into soil in order to condition or build up the top-
soil and/or to fertilize the soil; by reacting the organic humus-like char
product of the acid charring of wastes with alkalis at elevated temperatures
10 to produce the alkali salt6 of humic-acid-like materials, neutralizing said
alkali salts with appropriate fertilizing substances (e.g. phosphoric acid),
and mixing the resultant materials into the soil.
The present invention provides a process for converting the organic
waste materials of civilizat$on into uniform, non-flam~ble, non-offensive and
useful products. Thi8 invention converts these organic wastes into dry, easily
friable materials of considerably retuced weight and volume, which greatly
facilitates handling and transportation while simultaneousl~ a~ding disposal of
such waste material~ by extending the capacieies of landf~ll sites. Another
benefit of the process of this invention is the conversion of the aforesaid
20 orgsnic wastes into easily friable alkali salts o$ humic-acid-like materials,
which can be utilized as topsoil conditioners and/or fertilizers. Said alkali
salts of the humic-aS~id-l~ke materials can be produced so a~ to contain potash,
nitrogen, phosphates, and other minerals and trace elementæ which ncrmally will
be present in the organit waste materials of human soGiety.
The present invention converts such diverse organic waste material3
as animal manure and sewage solids, paper and gra~s clippings, coffee grounds
and table scraps, into useful products. Moreover, the present invention simpli-
fies sewage treatment by allow~ng present facilities to be used primarily for
purification of the liquids becau3e the present invention can be utilized on
30 the sewage solids, thereby eliminating the time-consuming digestion of sewage
~olids presently performed by sewage treatment plants.
Additionally, the present invention is able to convert agricultural
wastes and industrial wastes having substantial carbohydrate and protein con-
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~OS;~591
tent to useful products, such waste m~terials including: woodJ sawdust, ~traw,cardboard, cane bagasse, oat hulls, cotton gin wastes, animal manures, bark,
paper, etc.
The present inventio~ converts all of the above wastes into a dry,
easily friable, inert black product, somewhat re~embling natural humus, by
charrin~ the waste materials by reacting them with certain acids at moderately
high temperatures (about 220 to 240F) under strongly dehydrating conditions.
When freed of residual acid and other water ~oluble contaminants by washing
with water, this humus-like char product can be utilized as a landfill, and
10 additionally mEly be useful as an intermediate for the productiol~ of chemicals
such as plastics or fuels by e.g. hydrogenation, pyrolysis, catalytic reduc-
tive cracking, gasification as with coal, etc. Reaction of the humus-l~ke char
product with alkalis at elevated temperatures (about 500F) yields the alkali
salts of high-lecular-eight polycarboxylic acids which re~e~le natural humic
acids, (C40H30013)n, and which can be utilized as soil conditioners, fertilizers,
flocculants, etc.
Generally speaking, the excellent results of the present invention are
obtained by adding a certain amount of water soluble inorganic acid to the
shredted or ground waste materials and heating this mixture of acid and waste
20 under strongly dehydrating conditions to a ~ufficient temperature and for a
sufficient length of time to "char" the material. During this charring process
gasses are given off, which primarily consist of S02, N02, and other acid gasses
which can be prevented from con~aminating the atmosphere by passing them through
alkaline scrubbing towers, etc. The resulting inert black humus-like product
is insoluble in water; it can be freed of residual acid and other water-soluble
contaminants by washing it with water, from which the acld can be recovered for
re-use where economically feasible. The easily-friable black humus-like prod-
uct thus formed can be utilized as an inert, non-polluting landfill. If desired,
the inert, black humus-like product can be mixed, wet or dry, with 8 strongly
30 alkaline mater~al and this mixture heated to a temperature above 240F, and
preferably above 450F, which causes the humus-like product to react with the
alkaline material, forming the water-soluble alkali salts of black, humic-acid-
like materials.
--3--
lO5Z59~
During the charring proces6 it is believed that the acid is acting
a8 8 dehydration catalyst to change the cellulose and other carbohydrates,
protein, and fats, etc. found in organic waste material into the inert humus-
like char product. Naximum shredding, grinding, and pre-soaking of the organic
waste material with acid will insure complete contact of the acid with the waste
material which substantially reduces the amount of acid utilized and the length
of time required to obtain complete charring.
Some of the acid utilized during the charring process will be neu-
tralized by the ammonia, amines, and other cations present in the raw material.
The free acid remaining after charring can be recovered from the crude char
product by washing it with water, or the residual acid can be neutralized by
adding e.g. ammonia or potassium hydroxide in order to increase the fertilizing
capacity of the product. Since the humus-like char product i9 insoluble in
water, when washed free of residual acid and soluble salts it is an inert, non-
polluting material, suitable for use as landfill. Also, since the weight and
volume of the char product are reduced by 40% or more as compared to the raw
waste materials, this would greatly extend the capacity of landfill sites.
Furthermore, being inert, the humus-like product can be used to loosen heavy
soils just as sand or silt does; in this case neutralizing the residual acid
in the crude char product with suitable alkaline compounds will add fert~lizing
properties to the soil filler or loosener.
The charring process is more economical if the acid is thoroughly
dlspersed i~ the organic waste material so that the acid will contact as much
of the organic waste material as feasible. In order to insure this, it is
preferred if the organic waste material i8 crushed, ground, or chopped into
8mall pieces, depending on the particular organic waste material being treated.
These relatively small particles of organic waste material are then allowed to
remain in contac~ with the acid until all of the waste material has been pene-
trated by the acid.
Where the waste materials, such a8 city rubbish, contain metals,
glass, etc., it is preferred that the current processes for shredding and
removing metals, glass etc. be utilized prior to treating the organic waste
material with the acid.
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iO5Z591
With finely divided, absorbent solids, uniform contact of all the
solid with concentrated acid is readily accomplished. With coarse solids 8uch
as wood chips, however, which absorb the acid slowly, it i8 desirable that the
waste be soaked in a large volume of dilute acid long enough to allow complete
penetration and wetting of the solid wsste by the acid solution. After soaking,
it i~ generally desirable that any excess acid solution be re ved. This can
be accomplished by any convenient means such as filtering or squeezing the
orgsnic waste material between screens or rollers, leaving the waste uniformly
wet with sufficient acid to effect the desired charring. It should be noted
that this i8 not critic~l, but only convenient, inasmuch as if it is desirable
that the organic material-be neutralized after charring, less alkali will be
requiret to neutralize the!residual acid ~f any acid in excess of that required
to effect charring has been re ved prior to the charring. It is self evident
that city rubbish, for exsmple, might contain cement, plaster, or other caus-
tic materials which would neutralize a portion of the acid used. This is no
problem when an excess of dilute acid is used to soak the waste prior to char-
ring, but the presence of such caustic materials should be taken into account
when determining the amount of acid ~eeded when the material is simply wet with
acid and charred.
Acids which are generally usable in the present invention are in-
organic water-soluble mineral acids such as S03, sulfuric acid, and hydro-
chloric acid. The term water-soluble inorganic acid includes those waeer-
soluble salts which when dissolved in water produce a strong acid and a weak
base which will not neutralize the strong acid. Exemplary of such water-
~oluble acid-producing salts are aluminum chloride, AlC13; ferric chloride,
FeC13; zinc sulfate, ZnS04; sodium hydrogen sulfate, NaHS04; and similar
chlorides, sulfates and no-hydrogen ~ulfate6.
The use of the various acid-producing salts such as those listet
above suggests that many industrial waste acids can be used in the charring
step. Such waste acid~ or sludges which can be used would contain the acid-
producing sulfates or chlorides of copper, tin, iron, nickel, chromium~ alumi-
num, zinc, etc., etc.. The crude chars thus obtained might in some cases be
acceptable as landfill when neutralized with appropriate alkaline materials
--5--
~(~S2S91
such as lime, limestone, or soda ash, provided the nitrate ion concentration in
the product were kept below a specified level. Where such chars are to be
further converted to the humic-acid-like soil conditioner/fertilizer mixes, the
industrial wastes can be selected for incorpration into the acid charring step
so that the final product would contain the st beneficial concentration of
various metal ions and trace elements.
From the foregoing, it is apparent that the important criterion of
the acid charring step is to have the organic waste in contact with hydrochloric
or sulfuric acid, regardless of the state in which the acid i8 added to the
organic waste material, during the heating and drying process which forms the
char.
Since the acid is acting as a catalyst, and i8 concentrated during the
heating and drying processes of the chsrring step, the starting concentration of
the acid i8 not important, and one can utilize 98% or 100% acid to as low as 10%
or even 5%, and still obtain the char. Economic con6iderations ~uggest that as
little water be added with the acid as processing details permit, since this
water along with water form~d in the dehydration reaction in the charring step
must be evaporated. Similarly, the total amount of acid added to the organic
waste material is not particularly critical: as little as 3% acid based on the
weight of the raw waste material will cause substantial charring and weight re-
duction, whereas if maximum weight reduction and/or maximum conversion of the
wa6te to the humNs-like char product is desired, the weight ratio of acid to
waste material should be about ôX to 10% or higher. ~owever, utilizing large
a unts of acid will entail re ving eonsiderable residual acid after the char-
ring process is completed, or in the alternative, utilizing large amounts of
alkali material to neutralize the residual acid. Therefore, it is preferred if
the amount of available acid utilized is less thsn about 50Z, with the prefer-
red range being from 5% to 20X by weight, based on the dry weight of the organic
waste material.
The rate and extent of charring are variable, and depend to some extent
on the temperature of reaction and the starting concentration of the acid used.
For example, utilizing a concentrated acid results in re rapid charring and
lower starting temperatures may be used. The temperature at which the charring
--6--
lOSZ591
starts will vary from around 180F when concentrated sulfuric acid is used, to
above about 212F with dilute acid, since both the water of dilution and the
water formed in the charring process must be evaporated as the char forms.
If concentrated sulfuric acid in the amount of about 50% or more by
weight of the organic wa~te material is added, an extreme exotherm can occur
even when the starting materials are at room temperature if the organic waste
material contains moisture. The initial rise in temperature is no doubt due to
the high heat of hydrat~on of H2S04. Though charring appears to start in concen-
trated sulfuric acid at about 180F, it is impossible to determine the tempera-
ture exactly, since in the laboratory the heat of reaction and hydration raises
the temperature of the rsaction mass to above 350F within seconds. Excessive
oxidation is evident under theæe conditions, since large amounts of SO2 are
evolved at the higher temperature. Charring with concentrated sulfuric acid
could be controlled by mixing the acid and waste just prior to spraying them
into an air cyclone, for example, where the reaction temperature would be con-
trolled by the temperature of the large volume of air involved, to between about
220 and 240F. In this case, the crude char product would contain a very large
amount of residual acid, which could be removed by washing with water and then
concentrated for re-use.
~hen dilute acids, eOg. sulfuric acid of less than about 90% concen-
tration, are used, in order to obtain maximum yields of the de~ired humus~like
char product the reaction must be carried out at temperatures above about 212F
under conditions which remove the water, thus concentrating the acid, as rapidly
as possible so as to minimize decomposition side-reactions. Since both the
water used in diluting the acid and the water formed by the dehydration charring
reaction must be removed rapidly once heating is begun, it is preferred that the
charring reaction be carried out at about 220 to 240F. However, since charring
with concentrated sulfuric acid starts at around 180F this lower temperature
could be employed if a special means of rapidly removing water from the zone of
reaction were also used. For example, the charring of the organic waste with
concentrated sulfuric acid at 200 F under partial vacuum would be entirely
satisfactory. The scid catalyzed dehydration reaction has also been carried
out in refluxing toluene, using benzene sulfonic and toluene sulfonic acids, as
105Z591
catalysts. In this case the water was removed from the zone of reaction by the
toluene and collected from the refluxing toluene by a water trap. This would
not appear practical in terms of preparing a landfill or fertilizer/soil con-
ditioner. Ho~ever, it might be the most economical procedure for preparing a
humus-oil slurry for converting the humus to liquid and gaseous fuels and other
useful chemicals by processes similar to those used for gasi~ication, reductive
cracking, and liquification of co~l. That is, sufficient toluene or similar
solvent, along with the acid catalyst, could be added to a slurry of the organic
waste material in an appropriate fraction of oil. Subsequent heating while
refluxing the solvent would remove the water as the humus formed, the solvent
could then be distilled off for re-use, leaving the humus slurried in the oil
ln what may be an excellent form for subsequent hydrogenation, etc.
Commercially, the charring proces~ would be carried out in various
suitably designed equipment, most likely rotary kilns, continuous tray dryers,
or hot-air-cyclone reactors, etc.
If volatile acids or acid-producing gases such as HCl or S03 are u6ed,
it is necessary to carry out the charring reaction in a system wherein the acid
volatilized along with the water produced in the dehydration process is re-
covered. Excess acid can be used initially, or the acid concentration in the
reaction zone can be aug~ented periodically as required to maintain the char-
ring reaction. When HCl is added as an aqueou~ solution of AlC13 or FeC13, etc.,
this volatilization does not occur to any significant extent. An advantage of
the use of HCl is that reaction conditions might be 80 controlled that st of
the HCl would be triven off during the charring process, leaving a char product
nearly free of residual acid.
One can tell when the reaction is completed in forming the humus-like
char product, because this char is black~ resinou6, water-insoluble material.
The crude reaction product also contains residual acid and other water-soluble
contaminants which are absorbed onto the ea6ily friable humus-like char mate-
rial. The6e residual acids and water-soluble contaminants can be removed by
washing the crude char product with water, from which they may be recovered if
desired. The wa~hed char product is an inert material, well suited to u6e as
a non-polluting landfill. Alternatively, if it is desired that the char product
-8-
lOS;~5~1
be used ~8 a 80il loosener, etc., wherein the water-soluble side-products mi8ht
be of value as fertilizers, it i6 preferrable that the residual acid be neutra-
lized by the addition of alkaline substances of fertilizing value, such as
ammonia, potash, or lime, etc., rather than w~shing the crude char product.
The humus-like char product can be converted to the water-soluble
alkali salts of black, humic-acid-like materials by reacting the char product
with alkalis at elevated temperatures. After the crude char is washed or
neutralized, the char is then mixed with an alkali-metal or alkaline-earth
hydroxide, or an alkali metal carbonate or silicate, or a mixture of an alkaline
earth carbonate with hydroxide, both the char and the alkaline material being in
powder form, or slurried together in a water solution. This mixture is then
heated to above 240F when the alkaline material used is e.~. potassium hydrox-
ide, or above 450F when other lessalkaline materials are used, which causes
the humus-like char product to react with the alkali~e material, producing the
water-soluble alkali salts of the black humic-acid-like materials. These salt~
can be neutralized for use as soil conditioners and fertilizers, preferrably by
adding phosphoric acid, potassium dihydrogen phosphate, ammonium dihydrogen
phosphate, or other suitable acidic materials which would augment the fertiliz-
ing capacity of the final product. If desired, the humic-like acids can be
recovered from solution~ of the alkali salts by acidifying the solutions and
filtering off the resultant humlc-acid-like precipitates.
The precise temperature of the reaction of the humus-like char product
with the alkaline material depends on the strength and concentration of the
hydroxides, carbonates, or silicates u~ed. The a unt of alkali used is not
critical, as partial conversion of the inert humus-like char to the 30il-con-
ditioning humic-acid-like materials will occur with a dry weight ratio of about
5% alkali to humus-like char. Where essentially complete conversion is desired,
it is necessary to use about 30~ by weight of sodium hydroxide based on the dry
weight of the humus-like char, or an equivalent amount of any of the other
alkaline materials, for example 40Z by weight of potassium hydroxide.
Example~:
In the following examples, which are solely for the purpose of ~arifi-
cation and are not to be considered limiting, the temperatures given are in
105;~591
degrees Fahrenheit unless ~xpressly 6tated otherwise. Unless specifically
stated otherwise, all of the charring reactions described below were carried
out in a pre-heated drying-oven, with the acid-soaked raw organic waste mate-
rial spread out in a thln, 1/2" to 1" layer in a shallow pyrex dish, so as to
favor rapid evaporation of water from the reaction zone.
Conversion of Or~anic Wastes to HU~LS~ r ~rod- --:
Several samples approximating normal garbage were prepsred as follows:
each sample totalled 100 grams, containing 10 gram~ of each of the following:
sawdust, paper (1/2 inch squares), thin cardboard (1/2 inch squareæ), heavy cor-
rugated cardboard (1/2 inch squareg), coffee grounds, sausage, egg shells, can-
ned whole kernel corn, peanuts, carrots, and bones with meat and gristle. The
last fiv ingredients were crushed to pieces of approximately 1/8 inch or
smaller before being added to the mix.
Example 1
To the first sample 5 ml. of conc. (93%) H2S04 mixed with 195 ml.
H20 was added, the mixture was stirred nnd allowed to stand for one hour. After
one hour, the excess liquid was removed by squeezing the sample between two
coarse strainers. Approximately 110 ml. of a light brown acidic liquid of pH
1 or lower was recovered. The sample was then placed in a preheated drying
oven at approximately 200F. After one hour, no reaction was apparent. After
several hours a slight charring occurred on the edges of the mass. After over-
night (16 hour) heating at higher temperatures (up to 270F), the sample was
almost entirely charred, some of the thicker pieces were brown rather than
black, however, and ~here were a few pieces of peanuts which had not blackened.
Egg shells also did not blacken. Two minutes of grinding broke the dry product
into a coar~e shiny black powder, with bits of egg shell and a few large pieces
of brownish black material. Total weight: 65.2 grams.
Example 2
To the second sample, 10 ml. of conc. (93%) H2S04 mixed in 190 ml. of
30 H20 was added. This sample was then processed as ln the first example, 105 ml.
of liquid being removed after soaking. This sample also did not char appreci-
ably during the first hour, but was slightly charred after three to four hours,
and was completely charred after overnight heating. Except for the egg shells,
-10-
105Z59~
the sample protuced 8 very iine and uniform dull ~lack dry powder, with only a
very few larger pieces of a bornish-black color. Total weight: 49.0 grams.
ExamP le 3
To the third sample, 15 ml. of conc. (93%~ H2S04 mixed with 185 ml.
H20 was added, 110 ml. of liquid was recovered aiter ~oaking one hour. ThiA
sample was considerably charred after one hour's heating. Grinding the com-
pletely charred mix after overnight heatin8 produced a coarse, slightly floc-
culent black powder, containing bits of egg shell and a very few slightly
larger brownish-black pieces. Unlike the other two samples, there was a slight
somewhat sweet odor, similar to certain plant ioods or artificial fertilizers.
Total weight: 71.4 grams.
Exa~p~e_~
The fourth sample was soaked in a mixture of 60 ml. conc. HCl and
140 ml. H20 for one-half hour. The treatment and results were identical to
samples 1 and 2. 40 grams of dry black solid were produced, which appeared
only slightly re charred than samples 1 or 2.
ExamPle 5
Samples of raw sewage sludge and fresh horse manure were obtained
from the Hyperion Sewage Treatment Plant in El Segundo, California, ant from
the Long Beach Riding Stables, Long 8each, California, re8pectively. Two samples
of the manure were treated as follows:
a. 50 grams of manure was mixed with 10 ml. of conc. H2S04 dissolved
in 40 ml. H20.
b. 50 grams of manure was mixed with 50 ml. of conc. HCl.
Both samples were heated at 240F for about one hour, sample a.
yielded 22 grams of blac~ char, sample b. yielded 7.5 grams of brown ch~r.
Neither dark char was soluble in water.
Example 6
Four samples were prepared from the sewage sludge:
a. 100 ml. of raw sewage was mixed with 20 ml. of conc. (93S) H2S04.
b. 100 ml. of raw sewage was mixed with 10 ml. of conc. H2S04.
c. 100 ml. of raw sewage was mixed with 50 ml. of conc. (37~) HCl.
d. 100 ml. of raw sewage was mixed with 25 ml. of conc. HCl.
-11-
105Z59~
These samples were heated overnight at 240 - 260 F. Sample a.
yielded 16.5 grams of a black, rubbery char; ssmple b. yieldet 10.1 grams of a
dry cake char; sample c. yielded 7.5 grams of gummy black char snd sample d.
yielded 7.5 grams of a slightly gummy black char.
Example 7
Three 20-gram samples of "garbage" were prepared, each consistlng of
2 gr~ms sawdust, 2 grams paper, 2 grams cardboard, 2 gram~ coffee grounds, 2
grsms egg shells, 2 grams ground bone and gristle, 2 grams crushed csrrots, 2
grams sausage, 2 grams peanuts, and 2 grams crushed corn.
a. The first sample was sprayed during mixing in a blender with 2.0
grAms of H2S04, using a medical atomizer. The cardboard began to disintegrate
into loose fibers as soon as the first of the acid was added. Hesting the sam~
at 240F for an hour produced 11.5 grams of dark black dry char which powdered
easily.
b. The second sample was sprayed with 5 grams of conc. HCl. Heating
overnight at 240 - 260 F producet 13.2 grams of brown, partially-charred
material.
c. The third sample was sprayed wlth 10 gram~ of conc. ~Cl. 14 grams
of partially-charred material resulted.
ExamPle 8
a. 100 grams of raw sewage sludge from the Lomita Sewage Treatment
Plant was dried on a hot plate for ten minutes, yielding 5.5 grams of dry
fibrous residue and ash. It appears that the water content of the sludge i8
in excess of 90%.
b. 7.5 grams of residue (as above~ was pulverized in a blender, and
305 grams of ~2S04 was sprayed into the stirred material. 10.0 grams of the
acid-wetted matter was heated at 240F for about ~hree hours, yielding a black
fibrous char with a few pieces of unreacted tan or grey fibers which had ap-
parently not been wetted by the acid. 6 grams of crude char was produced.
Example 9
Three samples were prepared by mixing raw sewage sludge from the
Lomita Sewage Treatment Plant with sawdust. These samples were treated with
H2S04 and charred as follows:
-12-
lOSZS91
a. 10 ml. of conc. H2S04 was added to 70 gram~ of slutge, ant the
resulting mixture was mixed with 30 grams of sawdu~. After standing for one
hour to insure thorough wetting of the sawdust, the mixture was heated to 240F
for about two hours. The resultant crude char was rinsed with H20 and dried,
yielding 6.5 grams of humus-like char material.
b. 10 ml. of H2S04 was mixed with 80 grams of sludge, then this
mixture was added to 20 grams of sawdust and stirred thoroughly and treated as
in the above examples. This procedure yielded 15 grans of rinsed and dried
humus-like char.
c. 10 ml. of H2S04 was mixed with 90 grams of sludge and 10 grams of
sawdust as above, which yielded 18.3 grams of unrinsed char which gave a pH of
about 2 when rinsed in 500 ml. of H20. After rinsing and drying, the humus-
like char weighed 13 grams.
Example 10
a. 20 grams of garbage as in O above, were preheated to 240F, then
sprayed with 2 ml. of H2S04 using a medical atomizer. Charring of the sample
occurred i ediately wherever droplets of the acid made contact with it. Sub-
sequent overnight heating resulted in complete charring except where no acid
had contacted the bottom of the sample.
b. 20 grams of garbage was preheated to 240 F, then sprayed with con.
HCl using a medical atomizer. The 4.5 ml. of acid used produced copious fumes,
and appeared to evaporate from the hot sample before sufficient contact for
charring. Subsequent heating overnight produced a sample which was only slight-
ly charred. Reaction with HCl spparently must be done under conditions where
the acid is allowed to soak into the sample or is constantly added to the zone
of reaction.
Example 11
a. 100 grams of similar shredded rubbish mix, uniformly wetted with
50 grams of 50% sulfuric acid, was placed in a 1 liter flask equipped with a
sealed stirrer and set up to operate at the reduced pressure obtained by a
water aspirator. The waste was stirred at 76F under the indicated partial
vacuum for about 1/2 hour; no blackening of the solids occurred. The reaction
flask was then immersed abcve the level of the solids in a water bath preheated
-13-
105ZS91
to 200F. Within a few minutes some of the solids began to blacken. At the
end of three hours heating at 200F the solids appeared totally black and dry.
The crude char product was washed and dried to yield 62 grams of the black,
humus-like product. Upon fusion with NaOH by the method described in example
12, below, a high conversion to black humic-acid-like material was obtained.
b. In a similar preparation, using 30 grams of FeC13 dissolved in
water in place of the sulfuric acid, 56 grams of black humus-like product was
obtained.
Example 12
a. 10 grams of shredded orgsnic waste mix was mixed with 150 ml.
toluene in a flask equipped with a reflux condenser and water trap. During
about 1/2 hour of refluxing to dry the system, 0.6 ml. of water collected in
the trap; no apparent change in color was notet. One ml. of concentrated (93%)
sulfuric acid was then added, and refluxing continued. The organic solids
began to turn black, and water again began to collect in the trap almost immedi-
ately. Refluxing was continued until no more water was collecting in the trap,
à total of 3.7 ml. of water was collected, the solids were considerably black-
ened. A second ml. of sulfuric acid was added and refluxing continued.
~urther water collected, giving a total of 4.6 ml. water. The crude black char
20 was separated from the toluene by filtration, washed with water, and dried,
yielding 4.8 grams of black humus-like product. 2 grams of this humus-like
material was intimately ground with 2 grams of KOH (C.P.) and the mix gently
heated over a flame in a metal spoon while stirring, until a soft melt was
formed. The black melt was dissolved in 100 ml. of water, giving a dark red-
dish-black strongly alkaline solution from which only a trace of insoluble
material was removed by filtration. The solution was acidified with dilute
acid; a voluminous precipitate of black humic-acid-like product was formed,
which slowly ~ettled leaving a colorless water layer.
b. Alst identical results were obtained using 3 grams of benzene
30 sulfonic acid in place of the sulfuric acid to yield 5.2 grams of the humus-
like product from 10 grams of shredded organic waste.
Water-Soluble Acid-Producin~ Salts and Acid Sulfate Salts
The procedure is essentially the same as with the mineral acids; the
105~5~1
waste material is soaked in a water solution of the salt, the excess solution
drained or filtered off, and the ma~erial charred by heating.
Example 13
Four samples approximating "normal" garbage were prepared as in 7)
above.
2. 20 grams of garbage wa~ soaked for one-half hour in 50 ml. of
solution containing 10 grams of AlC13-6H20. The sample was then heated to
240F. Sllght charring occurred after one hour, and derate charring occur-
red after overnight heating. 13 grams of unwashed char was obtained, which pro-
duced a pH of 6 in 100 ml. of water u~ed as a rinse. Further rinsing and dry-
ing yielded 13 gr8ms of black to brown humus-like char, mixed wlth some un-
charred paper and cardboard.
b. 20 grams of "garbage" was soaked for one-half hour in 50 ml. of
solut~on containing 10 grams of FeC13 6H20. Upon heating to 240F, some char-
ring was observed almost immediately. Overnight heating at 240F resulted in
a dry dark black char. There was no evidence of uncharred starting m~terial.
11 grams of unwashed char was produced, which gave a p~ of 3 to the first 100
ml. of wash water. Further rins~ng and drying yielded 9 grams of humus-like
char.
c. 20 grams of garbage was soaked for one-half hour in 50 ml. of
solution containing 10 grams of ZnS04-H20. Treatment as above yielded 13.5
gram~ of unwashed, partially-charred material, which produced a pH of 6 in 100
ml. of wash water. The rinsed and dried char weighed 10 gramw.
d. 20 grams of garbage wa~ so~ked for one-half hour in 50 ml. of
H20 containing 10 grams of ~H4HS04. Charrlng was nearly complete after over-
night heating at 240F. 14 grams of unwashed char was produced, which gave a
pH of 2 in 100 ml. of rinse water. After rinsing and drying, the humus-like
char weighed 12.5 grams.
Rinsin~ the Char.
In examples 9) a, b, c, and 13) ~, b, c, and d above, the char was
crushed, soaked or slurried in tap water, and the excess water decanted. The
wet char was then placed on a #200 mesh screen, and remaining water drained off.
This process was repeated with each sample until the rinse water showed a pH of
lOS~S91
7.
Examples 15) a-l, b-l, c-l, 17) and ~) below, illustrate the poor
results of not rinsing the chsr prior to alkali fusion. If the sample i8 not
rinsed, the residual acid, especially in the sulfuric acid^produced chars,
requires that exsess alkali be added in order to neutralize the acid ~o that
the alkali fusion can occur.
Preparation of Humic Acid Salts.
A. Usin~ alkali metal or alkaline-earth hYdroxides.
Example 14
a. 6 grams of dry humus-like char and 6 grams of NaOH (C.P.) were
10 ground together, charged into a smsll pressure bomb, and heated at 480 - 500 F
for o~e hour. The fused mass was dried to a constant weight of 11.5 grams. The
re~ultant brownish black salts were very soluble in water.
b. 6 grams of humus-like char and 4.ô grams of NaOII treated as above
yielded 10.4 grams of soluble sodium salts.
Example 15
Three 10-gram samples from each of the above powdered chars, examples
1) through 3) above, were soaked with 25 ml. samples of H20 containing XOH to
prepare the following nine samples for alkali-fusion tests:
~.i. 10 grams of char 1) snd 2 grams of XOH in 25 ml. H20.
20 ii. 10 grams of char 1) and 5 gra~s of XOH in 25 ml. H20.
iii. 10 grams of char 1) and 8 grams of KOH in 25 ml. H20.
b.i. 10 grams of char 2) and 2 grams of K~)H in 25 ml. H20
ii. 10 grams of char ~) and 5 grams of KOH in 25 ml. H20.
iii. 10 grams of char 2) and 8 grams of XOH in 25 ml. H20.
c.i. 10 grams of char O and 2 grams of Kt~H in 25 ml. H20.
ii. 10 grsms of char ~) and 5 grams of KOH in 25 ml. H20.
iii. 10 grams of char ;~) and 8 grams of XOH in 25 ml. H20.
The nine samples were allowed to soak for three hours to achieve
uniform wetting of the char with the KOH solution, and then dried for one-half
30 hour in an oven at about 250F.
The samples were then transferred to a high-temperature oven and
heated for 45 minutes. The initial oven temperature was 350F., snd the maxi-
o temperature reached was 440 F, at the end of the heating period.
105~5~1
The samples were then tested for solubility in water:
Solubility of char sample~:
(a) Char 1) - Insoluble - black particles floated on top ~ettled to
bottom.
(b) Char 2) ~ Insoluble - same as above.
(c) Char 3~ - Insoluble - same as above.
Solubility of alkali fusion samples:
a. i. Very slightly soluble - formed a brown color in H20.
ii. Soluble - formed a dark brown color, few solids left.
iii. Soluble - ~ame as above.
b. i. Very slightly soluble - formed a faint brown color in water.
ii. Soluble - dark brown, few solids left undissolved.
iii. Soluble - same as above.
c. i. Insoluble - water remained clear, black solids settled or
floated.
ii. Soluble - brown color in H20.
iii. Soluble - dark brown color.
2xamP1e 16
A 25-grsm sample of the HCl-char sample 4) above, was then prepared
for fusion with KOH by soaking the sample in 50 ml. of a solution containing
0.2 grams of KOH per ml. There was a slight brownish color produced in the
liquid portion of ~hi~ slurry, indicating that some of the crude char was dis-
solving in the ROH solution. The æample was dried at 240F.
The samples were then placed in an oven at 530F. for about five
minute3. Product yield and 301ubility was then determined after cooling the
sample.
Char 4) yielded 29.5 grama of product. The dark brown solid which
resulted was soluble in water and had a pH of 9 or 10.
The char~ from samples 5) a. and b. were soaked with KOH solution as
follows:
a. i. 10 grams of char ~ a. was mixed with 25 ml. of solution
contsining 5 gr~m~ of KOH. The slurry became hot and gave off steam, indicat-
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1(~5ZS9~
ing that not all the acid had evaporated during heating.
ii. 7.5 gr~ms of char 5) b~ WA8 mixed with 25 ml. of ~olution
cont~ining 5 grams of KOH. This char did not wet ea~ily, and soaked up re
liquid than char 1).
These were then dried at 240 F for two to three hours. The dry sample
ii. was derately soluble in water, yielding dark brown solutions~ This lndi-
cates partial fusion even at this low temperature. Further heating, at 530F
for five minutes, yielded a black powder from sample i., and a dark brown powder
from sample ii.
b. The solubility of the black sample i., even after heating at
530 F, wss negligible. 0.25 grams placed in 50 ml. of H20 yielded a pH of 3,
indicating that the KOH had been insufficient even to neutralize the acid
remainin8 in the char. This sample was treated with 10 ml. of reagent KOH
solution, and again driet at 240F. The pN of the mixture before drying ~as
3bout 13. After this second KOH treatment and heating, the sample was trans-
formed into a brown material of moderate solubility, ,5 grams of which in 50 ml.
of H20 gave a pH of 11.
The solubility of the dark brown sample ii. was quite high. The pH
of the dark brown solution was about 9.
ExamPle 18
The crude chars from the sewage, example 6) above, were prepared for
fu~ion with KOH as follows:
a. i. 10 gram~ of char 6) a. was mixed with 25 ml. of solution
containing S grams of KOH.
ii. 10 grams of char 6) b. was mixed with 25 ml. of solution
containing 5 grams of KOH.
iii. 7.5 grams of char 6) c. was mixed with 25 ml. of solution
containing 5 grams of KOH.
iiii. 7.5 grams of char 6) d. was mixed with 25 ml. of solution
containing 5 grams of KOH.
The slurry of char 6~ a. and KOH became hot and gave off stesm, indi-
cating excess acid remained. Char 6) became warm.
The slurries were dried overnight at 240 - 260F, and then heated
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1(~5;~59~
to 530F for five minutes.
b. i. Sample i. yielded a gray powder contnining some white chunks.
The sample was not soluble. 0.25 8rams placed in 50 ml. of H20 gave a pH of 3,
indicating acid remained after heating. This ssmple was then soaked in 10 ml.
of reagent KOH, and dried at 240F. After this second attempt at fusion with
KOH, the sample was transformed into a brown material which w s highly soluble,
yielding a dark brown solution. 0.5 gsams in 50 ml. o~ water gave a pH of ll
or sbove.
~i. Sample ii. yielded a gray powder which was not soluble.
0.25 grams in 50 ml. of water gave a pH of 6. This sa~ple was Also ~oaked with
10 ml. of KOH and dried, as above. The results of the re-treatment with KOH
were the same as with sample i. above. 0.5 grams of sample ii. yielded a dark
brown solution in 50 ml. of water, having 8 pH of 11 ar above.
iii. Sample iii. yielded a moderately soluble light brown powder.
0.25 grams in 50 ml. gave a pH of 11 or ~bove. This solution also showed sus-
pended fine particles as in sample iii.
Example 19
2.5 grams of KOH in 20 ml. of water was added to 5.0 grams of each of
the crude chars produced in ~ above. These were then dried for 30 minutes in
an oven at 530 F.
a. Sample 7) a. yielded a dark brown powder, 0.25 grams of which in
50 ml. of water gave a dark brown solution of pH 10.
b. Sample 7) b. yielded a similar dark powder which was less soluble
than 17) 8. or b. 0.25 grams in 50 ml. of water gave a pH of 9.
Example 20
10-grame samples of the chars from the firs~ garbage tests, samples
1), 2) and 3) above, were each soaked in 25 ml. of water containing 5 grams of
Ca(OH)2, dried at 240 - 260F, and heated for five minutes at 530F. The pH
was tested with 0.25 grams of sample dissolved in 50 ml. of water.
a. Sample 1) y~elded a dark brown powder which was soluble, with a
few undissolved solids. The pH was about lC.
b. Sample 2) yielded a black powder which was somewhat soluble, giv-
ing a brown solution with many undissolved solids, and a pH of 9.
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lOS~591
c. Sample 3) yielded a brown powder which was slightly ~oluble, giv-
ing a light brown ~olution, of pH 8 or 9.
Example 21
15 ml. of reagent KOH was added to char 8) above, and this slurry was
heated at 240F for one and one-half hours, yielding a brownish-black product
with some white alkali residue. This material was somewhat soluble in water,
producing a brown solution, Further heating at 240F for two hours yielded a
brown solid of low solubility.
Exam~le 22
a. 15 ml. of reagent ROH and 3 ml. of water were added to water
washed char 9) a. above, and mixed thoroughly, then heated to 450F for 15
minutes. The black residue produced weighed 18.7 grams and ~as highly soluble
in water. 1 8ram dissolved in 100 ml. of water gave a dark brown 301ution of
pH 10 to 11.
b. 15 ml. of reagent KOH and 20 ml. of water were added to char 9)
b. above, and mixed thoroughly. This slurry was heated to 450 F for 15 minutes,
yielding 25 grams of black solid residue. This residue is of moderate solu-
bility, giving a brown solution and much suspended fines. 1 gram in 100 ml. of
water gives a pH of about 11.
c. 15 ml. of reagent KOH and 10 ml. of water were added to char 9)
c. above, and the resultan~ slurry was heated to 450F for 15 minutes. 16 grams
of brownish-black material resulted. 1 gram of this ~aterial gave a pH of about
11 when dissolved in 100 ml. of water. The material was quite soluble, forming
a dark brown solution with some suspended fines.
B. Usin~ alkali-metal carbonates.
Exsmple 23
a. 4 grams of humus-like char ~ a. was then ~oaked in 20 ml. cf a
solution containing 2 grams of R2C03. Overnight heating at 240 F produced a
brownish-black residue of derate solubility in water. 1 gram placed in 100
ml. of water produced a light brown solution of pH 7. Fusion had apparently
occurred with those portions of the ~ample which had charred in the first step.
b. 4 grams of char ~ was fused overnight at 240F with 2 grams
of R2C03. The resultant dark brown material was highly soluble in water, 1 gram
-20-
105;~ 591
in 100 ml. of water giving a dark brown solution of pH 9.
c. Fusion of 4 grams of char 13) c. with 2 grams of Na2C03, as above,
yielded a partially-soluble dark brown material. Extent of fusion ~pparently
corresponds to extent of charring in first step.
d. Fusion of 4 grams of char 13) c. with 2 grams of Na2C03 gave most-
ly soluble dark brown material, which produced a dark brown solution of pH 9
when 1 gram was added to 100 ml. of water. Extent of fus~on appears to corre-
spond to extent of charring.
Miscellaneous ExamPles
ExamPle 24
The sodium salts of example~ ~) a. and b. were ac~dified using }~Cl
to a pH of 6.5 to yield black humic acid precipitates, which were separated by
decantation and subsequent filtration. The precipitates were washed with very
dilute HCl ~nd dried.
Analyses oP these and similar products shows them to be humic-acid-
like compounds, containing carboxylic acid and hydroxyl groups, of a basic
structuré approximating (C23~226)n
Example 25
The humic acid salts from examples 15), 1;6), 17), 19) and 20) were
20 mixed together, dissolvet in water, and acidified with dilute sulfuric acid to
a pH of approximately 7 to yield precipitates. These were not rinsed, but were
dried by evaporation so as to avoid 1088 of trace minerals present in the origi-
nal sample and salts added. The dried sample was analyzed for nitrogen, potash,
and phosphate to determine possible value as a fertilizer. The results of this
analysis showed:
Total nitrogen 1.51%
Potash 17.35%
Phosphate (as phosphoric acid) 1.30X
Example 26
Examples 21) and 22) were mixed together and treated in a similar
manner, giving the following results:
Total nitrogen 0.14%
Potash 35.65%
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~05;~591
Phosphate (as phosphoric acid) 0.58%
The potash content of the final product could be decreased (or in-
creased) by controlling the amount of potassium hydroxide or carbonate 90 as
to give optimNm concentration for use as fertilizer. Ammonium acid phosphate
could be used in the neutralization to control nitrogen and phosphate content.
Example 27
Attempts to ignite char ~, humus salts 20) and 22) a., b. and c.,
and humus 26) and 27), using an 1800 F oxyacetylene torch caused a reddish glo~
in the samplec~ but no self-sustaining combustion could be initiated.
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