Note: Descriptions are shown in the official language in which they were submitted.
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A PROCESS FOR THE TWIRL AND CHEMICAL
DESTRUCTION OF TOXIC AND INFECTIOUS
_ BIOLOGICAL MURALS
Field Of The Invention
This invention relates to a method for
particle and chemically detoxifying and
destroying biological waste products, specifically
surgical and pathological hospital waste and clinical
and biological laboratory waste.
I Background Of The-Invention
Human and veterinary hospitals, surgical
clinics, pathology laboratories and associated
health care facilities -throughout the world are
routinely removing and disposing of tissues and body
15~ fluids from sick, injured and frequently infected
humans and animals. In addition, large volumes of
contaminated syringes, tubes, surgical bandages and
blood products enter the waste streams of these
institutions. In many cases, these materials are
harness and pose no threat of infection to persons
who handle or who are otherwise exposed to them.
In some cases however, these materials can contain
infective viruses pathogenic bacteria, toxins
Andover bacterial spores which constitute a threat
-to patients, health care professionals and the
general public. In many cases, hospital and clinical
waste carries with it a noxious odor and may be
considered unsightly.
In addition to the above-mentioned facilities,
there are numerous university and medical school
facilities in which research into the etiology ox
disease, experimental therapeutics and basic
research is conducted. Fermentation broths and
1 2 3
tissue cultures, as well as experimental animals,
may frequently contain higher concentrations of
rare and pathogenic organisms and toxic and Carson-
genie chemical agents than would be found in hospital
and clinical wastes. agricultural research facile
i-ties frequently produce mosses, -ferns and fungi
which reproduce through sporula-tion and which may
be either pathogenic or allergenic.
Recent advances in genetic engineering
enable the production of potent pharmaceuticals,
toxins, and other biochemical in large ferment-
lion cultures. Once the desired chemical products
have been isolated from the broth, the broth must
be properly treated to control both odor and the
possibility that potentially infectious agents
and toxins may bye released into the environment.
The disposal of small amounts of infectious
laboratory wastes, bandages and similar contain
axed materials has, since the invention of the
Chamber land autoclave in 1884, been performed using
wet steam. jet steam is effective against most
bacteria and mycotoxins, but is frequently ineffec-
live against spores, toxins and the so-called "slow"
viruses. team sterilization is extremely energy
intensive; must be monitored regularly for effective-
news, usually produces an odiferous product, and
results in no domination in the size of the waste.
The autoclaving of whole research animals and
large volumes of tissue is rarely practiced, except
in extreme emergencies.
Chemical -treatment of pathological waste
has never achieved routine use. Chemical treatment
of tissues requires the handling of comparatively
large volumes of corrosive and toxic chemicals, such
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as chloride of lime and formaldehyde. The end result
is an increased volume of a sterile, albeit chemically
hazardous, waste.
The incineration of whole bodies, parts
thereof and -tissues has been a routine procedure
at medical facilities, morgues, mortuaries and
veterinary hospitals. Incineration involves minimum
transportation within and especially outside of the
institution, produces a small volume of essentially
sterile waste, and is comparatively energy efficient.
Since the passage of the Hill-surton Act, all hasp-
tats constructed using federal funds have been
required to install a pathological incinerator.
Air quality regulations emanating from federal
Environmental Protection Agency and -from state
equivalents place limits upon the visible emissions
from such incinerators. Because retrofitting of
this equipment frequently entails major design
changes, particularly with older equipment, many
of these incinerators have been phased out. The
use of small, pathological incinerators for the
disposal of laboratory wastes and patient contact
items is limited by the design of a pathological
incinerator, which is typically a small solid
hearth, single chamber unit. The incineration of
significant volumes of plastic laboratory items such
as putter dishes and syringes results in the ems-
soon of large quantities of black smoke, and the BTU
content of these items frequently causes dramatic
changes in combustion chamber temperatures. The
incorporation of tissue and infectious waste into
the general waste stream of an institution has been
attempted a-t several large medical institutions, but
entails the installation of new and complex
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incinerators and the hiring of additional, qualified
operators, and is frequently beyond -the financial
capabilities of small and medium sized hospitals.
There exists, therefore, a need for a device
capable of destroying pathogenic organisms, spores
and viruses, as well as the tissues and laboratory
equipment in which they are contained, which device
is capable of significantly reducing the volume of
waste while producing Cassius end particulate
]() emissions of low -twixt or which are easily -trapped
or otherwise contained. The device should be
amenable -to predation in sizes suitable for install
lotion in facilities zoned for light industry
and require minimum operator training and service.
Finally, the cost of construction and operation
must be competitive with other, less efficient,
methods of disposal.
., .
Summary Of The Invention
This invention provides a process for the
destruction of toxic and infectious biological waste
products, e.g. human or animal tissues, biological
fluids such as blood, and bandages, cultures and
combustible laboratory apparatus entwining infer-
Titus Betty, bacterial spores, toxins and viruses,
as well as pharmacies and other trace chemicals
which may be included therein.
This process comprises the steps of: (a) heatincJ
said waste products in a sealed chamber, e.g. a solid
hearth, cJas-ticJht vessel, to vaporize volatile materials
end pyrolyze nonvolatile thereby producing an output
stream comprising yes with residual biological matter
especially residual physiologically active waste
such as pathogenic material entrained therein; lb)
passing said output stream into a bath of molten
aluminum.
The aluminum metal bath provides a long
residence time for the secondary thermal -treatment
of the pyrolyzes vases, as well as a chemically
reactive medium which reduces residual physiologic
gaily active waste as well as organic compounds of
physiological origin, typical pharmaceuticals, and
metal-based tissue strains -to hydrogen, hydrocarbons,
carbon, nitrogen, etc. The gaseous byprociucts from
the molten aluminum treatment do not require filter-
lion or scrubbing such as that which would normally
be required for the effluents from single and
multiple chamber incinerators and can, when containing
economic amounts of combustible gases, e.g.
hydrogen and hydrocarbons, be used for combustion,
e.g. to provide heat energy.
Brief Dose one Of The Drawing
Fig. l squashily illustrates a system
for carrying out the process herein
Detailed Description Of The Invention
As indicated above, heating of the waste
products herein in closed chamber means is carried
out to vaporize volatile materials and to pyrolyze
residual organic non-volati]es.
The gas produced in the initial vaporization
carries with it some solid and/or liquid biological
material. and is routed under pressure generated by
the vaporization of the volatile materials into the
bath of molten aluminum where the entrained solid and/or
liquid biological material is reduced by the molten
aluminum and is thus destroyed, along with the vital
components of the stream.
I I 1
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s heating in -the closed chamber means
continues, nonvolatile are pyrolyzed. The resulting
off-gases, which can have biological wastes entrained
-therein are routed to the molten aluminum bath where
sand biological wastes are roadhouses by -the molten aluminum
and destroyed. When further heating results in no
further vaporization the vapors remaining in the
pyrolyzes chamber may be swept into -the molten aluminum
by means of a stream of nitrogen or other inert gas.
It Turning now in more detail to the heating
step, the most volatile components in the waste
being treated, e.g. chemicals used in treating
pathological specimens such as ethyl alcohol and
Tulane, are flashed off. As heating continues and
the temperature in the waste which is being treated
increases, proteins coagulate and water vapor is
formed from ruptured cells, saline solution and the
fluids attendant -to tissue specimens. Fats, oils
and other organic compounds which are not water-
soluble are steam distilled during this initial
heating. On further heating, collagen-proteins
and any included higher molecular weight compounds
and other non-volatile materials begin to decompose
until the decomposition products become volatile.
it the conclusion of the heating step, the residue
remaining in the pyrolyzes chamber consists primarily
of carbon and metal salts, from tissues and from the
decompositiorl of bone. join they are present with
-the tissue, cellulosic materials such as bandages
and plastics decompose and volatilize at the appear-
private temperatures. Water-soluble organic compounds
such as pilarmaceuticals, stains, end compounds being
screened in such processes as -the Ames test or
toxicological feeding tests are either volatilized
at low temperatures or degraded at higher temperatures,
-thereby becoming volatile. Viruses and enzymes, which
are pretenses in character, are normally denatured
as the -temperature in the pyrolyzes chamber increases.
Pretenses materials Whitney tissues, however,
can be protected by the char of the -tissue surrounding
the protein and can remain viable as they pass out
ox the pyrolyzes chamber in small particles entrained
in the gases. Bacterial spores, which are particularly
Lo heat resistant, are likewise able under some circus-
stances, -to exit the chamber in this way.
It has been discovered herein that fishily-
jackal active materials and organic compounds in
gases from the heating, i.e. pyrolyzes, chamber
can be effectively treated by passage in-to
molten aluminum. The invention described herein
provides a method for treating pyrolyzes gases a-t
high temperatures under reducing conditions as well
as modifications necessary to a pyrolyzes chamber
to make secondary treatment efficient and controllable.
The pyrolyzes products of human and animal
-tissue, fermentation broths, bacterial cells, viruses,
spores and toxins are further decomposed when bubbled
through the bath of molten aluminum. The decomposed
products react with the hot aluminum metal end are
reduced to low molecular weight hydrocarbons, hydrogen,
nitrogen, etc. Since all biological materials which
can be volatilized in a pyrolyzes chamber are
composed, almost exclusively, of oxygen, carbon,
hydrogen, nitrogen, sulfur, phosphorus and, on
occasion, halogens, the resultant byproducts of the
reaction with the aluminum are limited in number
and character, regardless of -the biological nature
of the feed. or example, in addition to -the gaseous
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reaction products set forth above, other products
can include aluminum oxide and sulfide and on occasion
carbides, nitrides, phosphides or phosphorus. Because
the reactions are carried out under reducing condo-
-lions no water or carbon dioxide is formed or exhausted.
Effluent from the aluminum treatment can be
vented to the atmosphere. In such case it is
preferred to -flare the combustible materials. In
some cases, the effluent is preferably treated
with conventional gas treatment systems prior to
being vented to the atmosphere. It is preferred to
recover the heating values from the combustible
gases and in such case the combustible gases are
routed to a burner for this purpose.
Fig. 1 schematically illustrates a system
for carrying out the process herein. The system
includes a normally closed chamber means in the form
, of a heating pyrolyzes retort or chamber l which is
a refractory-lined vessel enclosed in a gas-tight,
preferably steel, encasement 2. Waste material to
be treated is fed into the chamber l bushes
through a door or chute (not depicted) which is
preferably fitted with casketed doors or other means
to prevent or minimize the entry of air. A second
casketed door (not depicted) is preferably fitted
just above the level of the hearth for the removal of
ashes. The chamber 1 can be heated by any conventional
underlining technique or, in the preferred embodiment,
electrically. The chamber 1 is equipped with a valved
Lyon. The chamber 1 communicates with a refractory-
lined vessel containing con aluminum bath 3 having an
upper surface 7 via a delivery tube 4 itch receives
exhaust from the top of -the chamber 1 and vents to a
point near -the bottom of the aluminum bath 3. The
2 3
tube is readily made from a refractory material,
although high temperature metal alloys are also
satisfactory. An exhaust stack 9 emanates from the
head space 10 above the molten aluminum, and may
discharge directly to the out-of-doors, through
a -treatment system as required to meet local emissions
regulations. In the preferred embodiment, the
exhaust includes a flash arrester. The valved inlet
5 is provided to admit air ox nitrogen and may be
I etude with a vacuum release device to prevent back--
syphoniny.
In operation, the waste material is introduced
into chamber 1 and the molten aluminum bath 3 is
brought up to operating temperature. Temperatures
So for the molten aluminum can range from its molting
point to its boiling point, i.e. from 660C. to
2450C., and are selected not only to provide
reduction, but also to provide decomposition of
thermally resistant and low reactivity materials.
Since the maximum operating temperature in the second
defy chamber of commercially available incinerators
is approximately 1400C., i-t can be seen that the
molten aluminum bath is capable of providing as much
or more heat than is available in the traditional
processes.
When the aluminum in vessel]. 8 has reached its
operating temperature, heat is applied to chamber 1
to raise the temperature in i-t to range from 600C.
-to 850C., preferably from 800C. to 825C. As the
temperature ion chamber 1 rises, vaporization and
pyrolyzes occur and the expansion and vitalization
force vapor and materiels entrained in it to
leave chamber 1 by the tube 4 and ultimately pass
into the molten aluminum bath 3, wherein reduction
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and secondary thermal treatment occurs and the treated
materiels are converted to innocuous compounds. Transfer
of gases, vapors and solids from chamber 1 to bath 3
is preferably assisted by the introduction of nitrogen
or other inert gas at line 5.
When the pyrolyzes process is completed, the
entry port can be reopened and the chamber 1 recharged.
alternatively, when all of the waste material has been
destroyed, the heat may be turned off and the valve
in line 5 opened to prevent back-syphoning as the
chamber cools. It is advantageous to introduce
nitrogen instead of room air into toe chamber during
cool-down to prevent flaring of any unburned material
on the hearth and to provide an oxygen deficient
atmosphere when the chamber is recharged.
The operation of this process in different
mechanical configurations is apparent to those
skilled in the art.
The following examples illustrate the practice0 of the invention without limitation thereof.
Exam
A young rat weighing 205 grams is humanely
sacrificed and placed in an 8 quart cast iron
pot. The pot is sealed with a cast iron lid
fitted with a copper wire gasket and secured by clamps.
-transfer -tube constructed of I inch ID SS316
tubing connects the pout to a Nixon graphite crucible
(size 16), approximately only filled with molten
aluminum. A stainless steel exhaust tube fitted
Thor a cover directs the gases from -the head
space above the aluminum to a glass cold finger
trap immersed in a dry ice/acetone bath. The cast
iron pyrolyzes chamber is heated by -two Meter burners.
The crucible is heated by a gas flame in a melting
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furnace. The pyrolyzes chamber is raised to a
temperature of 600-650C. as measured by a
thermistor and -the molten aluminum is maintained in
the liquid state throughout. After 30 minutes,
the heat is -turned off and the lid removed from the
pot. After an additional 15 minutes, the cold
finger -trap is removed and -the condensate is quanta-
natively removed to a tared lass vessel and weighed.
The liquid is then analyzed for -total organic carbon
(TOO); less -than 2 parts per million OKAY is found.
Exhume II
Using the apparatus as described in Example
1, three plastic putter dishes containing cultures
of Bacillus stearothermophilis are introduced into
the pyrolyzes chamber and the temperature raised
to a surface -temperature reading of ~00C. The
cold finger trap is replaced by a Matsson-Garvin
Jo ' slit to ajar sampler timed to complete one revolution
in 6C minutes. At the completion of the cycle, the
I ajar plate from the slit to ajar sample is covered
and removed to an incubator. After 72 hours at 37C.,
no growth is seen on the plate.
Example III
Five grams of ~-naphthylamine pa suspected
I carcinogen) us placed on 3 cyan filled putter dishes
containing a Salmonella culture to simulate an Ames
test and introduced into the pyrolyzes chamber, as
described in Example II. The slit to ajar sampler
is replaced by a glass Tube w to a serum cap on one
3J end. During the treatment 100 micro litter allocates
are removed via a yas-tight syringe a-t 15 minute
intervals. The allocates are injected into a gas
chrornatograph fit-ted with a flame ionization detector.
Substantially no bacteria or ~-naphthylamine is
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detected; acetylene is present at less than 50
parts per million. The ash in -the pyrolyzes chamber
is collected, slurries in a minimal amount of carbon
disulfide, filtered, concentrated by bubbling nitrogen
gas through the carbon disulfide in test tube and
analyzed by gas chromatography. Substantially no
bacteria or ~-naphthylamine is detectable in the
extra a t .
plastic 3 mill -thick bag with a volume of
1 quart is half-filled with cot-ton bandages and
a cotton hand towel. Ten l cc plastic Tuberculin
syringes are filled from a fermentation broth
containing approximately 5xlO spores (B. subtilis)
per lithe, their contents injected into the bandages,
and the syringe dropped into the bag. An additional
10 cc of broth is carefully poured onto the bandages
, and Roland the bag is tied with a wire utilizing
apparatus as described in Example II. The bag is
introduced into the iron pot and -the destruction
process is performed with sampling as described
in Employ II. After -three experiments the plates
from the slit to ajar sampler average fewer than 1
colony per plate. The contents of the pot, after
cooling, are washed out with 100 ml of sterile water,
filtered through coarse cloth, streaked on Tripticase
Soy ajar plates and incubated at 37C. for 72 hours.
The plates from the extraction of the ash contain
5-10 colonies per plate.
While -the foregoing describes preferred
embodiments, modifications within the scope of the
invention will be evident to those skilled in the
art. Thus, the Scope of the invention is intended
to be defined by the claims.
