CA1232169A - Process for the thermal and chemical destruction of toxic and infectious biological materials - Google Patents

Abstract

Abstract Of The Disclosure Biological waste products are destroyed in a process involving pyrolyzes and reduction using molten aluminum.

Description

-123211~

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 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 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 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.

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 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 I Jo 3 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 practice 0 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 1232~

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 23~

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.

Claims (5)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the destruction of biological waste products comprising the steps of (a) heating said waste products in a sealed chamber to vaporize volatiles and to pyrolyze non-volatiles and producing an output stream comprising gas with residual biological matter entrained therein, (b) passing said output stream into a bath of molten aluminum.

2. Process as described in claim 1 wherein the waste products comprise tissue from a mammal.

3. Process as described in claim 1 wherein the waste products comprise biological fluids.

4. Process as described in claim 1 wherein the waste products comprise infectious bacteria or their spores.

5. Process as described in claim 1 wherein the waste products contain carcinogenic agents.