WO1991000927A2

WO1991000927A2 - Particulate solid aminoplasts and method for their use in sanitary maintenance of biological wastes

Info

Publication number: WO1991000927A2
Application number: PCT/US1990/003854
Authority: WO
Inventors: Fritz Kramer
Original assignee: Fritz Kramer
Priority date: 1989-07-12
Filing date: 1990-07-10
Publication date: 1991-01-24
Also published as: AU6069990A; CN1049359A; WO1991000927A3

Abstract

A solid particulate urea formaldehyde foam is used to treat biological waste materials commonly stored indoors with a slow continual release of formaldehyde in an amount that is toxic to microorganisms but does not cause harm to humans. Liquids are absorbed into the foam creating a solid disposable mass which may be disposable in a landfill. Waste odors are overcome.

Description

PARTICULATE SOLID AMINOPLASTS AND METHOD FOR THEIR USE IN SANITARY MAINTENANCE OF BIOLOGICAL WASTES The present invention relates to solid particulate urea for¬ maldehyde foam polymers which are useful in the treatment of bi- ological waste materials commonly stored indoors by slow contin¬ ual release of formaldehyde in an amount that is toxic to micro¬ organisms but does not cause harm to humans.

Backgroun ς>f the Invention

A serious problem exists in the containment of biological waste materials due to inherent offensive odors, generated by microbial attack of the waste material and the high disease spreading potential upon human or animal contact with these wastes.

While biological wastes such as_f for example, animal and hu- man excrement, blood, excised tissue or organs, used bandages, syringes, dead animal bodies or food wastes, are generated from time to time in a wide variety of situations, they are regularly produced in various procedures carried out in hospitals, medical clinics for treatment of humans and animals, doctors' offices, laboratories, restaurants a d food processing plants.

Due to the high disease spreading potential, offensive odor and appearance of these wastes, it: has become difficult and/or expensive to contain them and to dispose of them in an environ¬ mentally acceptable manner. They also present a hazard due to spills from punctured containers during handling. Such wastes, as liquid waste, are not accepted at landfill operations and, therefore, must be disposed of by more expensive methods, such as incineration.

An especially hazardous situation arises when medical wastes are disposed of due to the probable contamination by pathogenic organisms or toxins. Of particular concern are wastes containing human blood because of possible contamination by pathogens, es¬ pecially the human immunodeficiency virus (HIV) , the causative factor for acquired immunodeficiency disease (AIDS) . Formaldehyde is well known in the art as a disinfectant with potent bacteriacidal, fungicid l and viruscidal activity. In moderately high concentrations, its vapors are irritating to hu¬ man mucus membranes and higher concentrations are intolerable to humans. However, a suitable method for treating biological wastes which are in relatively close proximity to humans with formaldehyde at a sustained low level, at which it is active a~ gainst microorganisms, but nob harmful to humans, is unknown in the art.

Description of the Prior Art There has been a long felt need for a simple, inexpensive method for rendering biological wastes inoffensive. This has been accentuated recently by the highly publicized pollution of beaches in the United States by medical wastes. As a result, of this, the public has avoided these beaches out of fear of pos¬ sible contact with such waste containing pathogens, especially the human immunodeficiency virus (HIV) .

While a number of antimicrobial agents, including formalde¬ hyde, are known in the art, their use for sanitary disposal of biological wastes has not been found suitable due to either economic reasons, or to adverse effects upon humans and animals exposed to them.

Methods for the preparation of aminoplast resins are well known in the art. For example, the Isochaum process described in U.S. Patent No. 2,860,856 is a method wherein a mixture of foam¬ ing agent solution and air is formed, mixed with a liquid syn- thetic resin, such as a precondensate of urea and formaldehyde, and the resulting foam cured by a curing accelerator for the resin. Examples of such accelerators are oxalic acid and phosphoric acid. The accelerator is added to the foam just before it is expelled from the apparatus, so that the foam tends to cure and harden very soon.

U.S. Patent No. 4,107,105 discloses a method for reducing a shrinkage in the above described aminoplast foams by inclusion of glucose, fructose or sucrose in the formation.

Kramer, U.S. Patent No. 4,421,788 discloses a method whereby the urea formaldehyde plastic foam is expelled from a slit shaped nozzle under high pressure to break the foam into gener ally discrete particles which are propelled toward a surface to be coated with foam at high velocity. The plastic foam thus pro¬ duced are particularly useful for coating the surface of a land¬ fill and for sealing the surface thereof. gum ary of the invention

The present invention provides a novel method for maintain¬ ing a biological waste material under sanitary conditions which comprises the steps of:

(a) generating a wet urea formaldehyde aminoplast foam containing unreacted formaldehyde,

(b) breaking up the aminoplast foam into particles having a diameter in the range of from 0.5 to 20 millimeters,

(c) maintaining said particles in a sealed airtight environ¬ ment until ready for use, and (d) providing said particles in needed quantity in an envi¬ ronment which contains or is intended to contain a biological waste material, said particles being present in an amount that will generate formaldehyde at a level which is suitable for con¬ trol of microbial growth on said waste material. The present invention also provides a novel method for main¬ taining a biological waste material under sanitary conditions which comprises the steps of:

(a) generating a wet urea formaldehyde aminoplast foam con¬ taining unreacted formaldehyde; (b) breaking up the freshly generated aminoplast foam into particles having a diameter of from 0.5 to 20 millimeters;

(c) storing said particles in a sealed airtight container, and

(d) as needed, adding said particles to a receptacle which contains, or is intended to contain, a biological waste materi¬ al, said particles being present in an amount that will generate formaldehyde at a level which is suitable for control of micro¬ bial growth in said waste material.

An especially preferred method for preparing an aminoplast foam of the invention employs:

( i) an aqueous solution of urea and formal ehy e.

T methylolurea or dimethylolurea modified with from 4 to 12% fruc¬ tose by weight,

(ii) a catalytic amount of an acid accelerator, and (iii) a suitable foaming agent, said aqueous solution being mixed with a gas under a pressure of from 100 to 150 p.s.i. to form a wet hardenable plastic foam.

It is preferred to allow the aminoplast foam generated such as in part (a) , to form in a thick layer which is maintained un¬ der conditions which minimize the loss of water and formaldehyde from the foam while it is curing to a solid. Layers of from 6 - 12 inches.thick have been found to be especially useful, forming the thick layer on a plastic sheet and covering it with another such sheet has been found to be a preferred method for minimiz¬ ing loss of volatiles. Preferred acid accelerators are phosphoric acid or oxalic acid.

Preferred particulate wet plastic foams of the invention are those that contain from 0.05 to 1.0% of unreacted formaldehyde by weight. A further object of the invention is to provide a particu¬ late form of a urea formaldehyde wet aminoplast foam. Preferred particles of aminoplast foam are those having a diameter of from 0.5 to 20 millimeters and particles of from one to ten mm, all especially preferred. Another object of the invention is to provide a wet particu¬ late urea formaldehyde aminoplast foam which is useful for main¬ taining waste tissue, organs, bandages, used syringes, body fluids including blood, animal excrement or dead animal bodies under sanitary conditions. An especially preferred such use is for maintaining body fluids, especially blood, under sanitary conditions prior to disposal.

It is a further object of the invention to provide an eco¬ nomical method for sanitary control of biological wastes under conditions which are not harmful to humans. It is also an object of the invention to provide a method which substantially reduces or eliminates offensive odors which commonly emanate from biological wastes due to formation of mal¬ odorous products of microbial metabolism.

Another object of the invention to provide a method in which the particles are of sufficient quantity to absorb liquid from said waste.

Yet a further object of the invention is to provide biologi¬ cal wastes in a non-liquid form containing a particulate ami¬ noplast foam of the invention which are suitable for disposal in landfill operations rather than their disposal by a considerably more expensive method, such as incineration.

Yet another object of the invention; is to provide a method whereby codisposal of a biological waste and a particulate ami¬ noplast foam which is exposed to high temperature and high hu¬ midity generates additional formaldehyde gas by decomposition of the urea formaldehyde aminoplast. For example, exposure of a mixture of said aminoplast foam and biological waste in a land¬ fill operation to a temperature of 40°C, or higher, and 90% rel¬ ative humidity causes decomposition of the aminoplast with release of formaldehyde and urea. The formaldehyde thus produced will continue to deactivate any microorganisms which come in contact with the waste material.

Storage of biological wastes prior to their disposal, e.g., by incineration or dumping in a landfill, has long been a problem. Such wa__^~es are routinely generated by hospitals, clin¬ ic, laboratorie__ , especially those doing research, offices of medical doctors, dentists and veterinarians, as well as by restaurants and food processing plants. When such wastes are al¬ lowed to stand under ordinary conditions microbial growth on the waste is rapid. Byproducts are thus produced which are often of¬ fensive to both the sight and smell of those in close proximity to the waste. Such waste__ are also potential sources of patho¬ genic organisms which can cause diseases or infections to both animals, and humans. Whiie numerous potential diseases that may be spread by un¬ sanitary handling of biological wastes will be apparent to those

SUBSTITUTE SHζET of skill in the medical art, especially worrisome in this regard are biological wastes containing human blood which might contain the human immunodeficiency virus (HIV) , the causative agent for AIDS. The present invention provides a unique, novel method for rendering biological waste materials less contagious by reducing or eliminating the microorganisms contained therein by treating the waste with a suitable amount of wet aminoplast foam parti¬ cles containing from about 0.05 to 1% by weight of unreacted formaldehyde. The formaldehyde gas emanating from the foam particles will retain in the receptacle, since the formaldehyde (d = 1.067) is of higher density than air (d = 1.000) .

Furthermore, the amount of formaldehyde which might escape the waste receptacles during such treatment is insignificant and does not pose any hazard to humans. Formaldehyde molecules in the air are unstable and have a short shelf life (hours to days) . They decompose readily into water and carbon dioxide and present no long term hazard to humans. Typical of the recepta¬ cles used for such wastes are plastic bags, for example, those made from polyethylene of polypropylene, or heavy plastic or metal buckets or baskets.

A commonly employed such receptacle is a red polyethylene bag placed inside a suitable cardboard container. Medical insti¬ tutions often use red plastic bags to differentiate the contents from other wastes.

The term "sanitary" as used herein means that substantial growth of microorganisms such as, for example, various bacteria, fungi and viruses present in the biological waste does not take place or that a significant number of said microorganisms are destroyed. As a result, the decomposition of the waste and re¬ sulting foul odor and appearance are substantially eliminated. The term "sanitary" does not imply that an otherwise obnoxious waste, for example, due to the offensive chemical nature of the undecomposed waste itself, would be rendered safe with regard to its chemical content.

The term "aminoplast" is well known to those of skill in the

SUBSTITUTESHEET art. It defines a class of thermosetting aminoplastic resins made by the reaction of an amine or ammonia with an aldehyde. As used herein, the term "aminoplast" refers to resins made from urea, formaldehyde or a prepolymer of urea and formaldehyde, op- tionally modified with fructose. Examples of said prepolymers are methylolurea and dimethylolurea.

The aminoplasts which are employed to provide the desired particulate foams of the invention are generated by a variety of methods such as those described by Bauer in U.S. Patent No. 2,860,856; by Korf in U.S. Patent No. 4,107,105 and by Kramer in U.S. Patent No. 4,421,788. A preferred method employs an ami¬ noplast foam which is generated under a gas pressure of at least 100 p.s.i. A preferred such pressure is in the range of about 100 to 160 p.s.i. Preferred gases are air and nitrogen and air is especially preferred for reasons of economy.

As was noted above, the preferred process employs a catalyt¬ ic amount of an acid accelerator. While a variety of such ac¬ celerators are known to those of skill in the art, preferred ac¬ celerators are phosphoric acid and oxalic acid. By the term "catalytic amount" as used herein, means from about 0.2 to 2.0 percent of said accelerator based on the weight of resin.

In the present invention, it has been surprisingly found that use of a suitable amount of a plasticizer such as fructose provides a foam mass which rapidly solidifies. The solidified foam mass readily provides a particulate solid upon grating or grinding, which is found to contain from 0.05% to 1% unreacted formaldehyde by weight. Preferred levels of fructose plasticizer are from 4 to 12% by weight, based on the weight of resin, an especially preferred amount is in the range of from 7 to 10% by weight.

A number of commercially available foaming agents which are suitable for production of the invention, aminoplast foams will be known to those of skill in the art. Examples of such suitable foaming agents are the sodium alkylnapthalene sulfonates. The aminoplast foam generated by the above described methods are ordinarily formed into thick layers of from about 3 to 18

__- C' i _ inches, preferably 6 to 12 inches, covered to prevent substan¬ tial loss of moisture and formaldehyde, and allowed to cure for from about one to 24 hours. The cured foam is then cut into blocks and milled or grated to obtain the desired particulate form. An especially convenient method is to grate the foam blocks through a wire mesh screen.

It has also been found that it is preferable to maintain the particles in a sealed airtight environment until ready for use or store the aminoplast foam particles of the invention under conditions which minimize loss of water and formaldehyde until they are added to a waste receptacle. Thus, the foam particles are preferably stored in airtight containers. Suitable for such use are sealable plastic bags, for example, those made of poly¬ ethylene, polypropylene or mixtures thereof. Also suitable are rigid plastic or certain metal boxes or cans and the like, which can be tightly sealed. In this connection it has been found that wet aminoplast foam particles absorb liquid wastes much more rapidly than such particles which have been allowed to lose a substantial part of their water content. The formaldehyde containing particulate foams of the inven¬ tion are used in an amount which is suitable for control of mi¬ crobial growth in biological waste materials. By the term "con¬ trol of microbial growth" as used herein means that the micro¬ organisms present will be substantially deactivated or destroyed or will be maintained at levels below that which can produce of¬ fensive odors. It will be apparent to those of skill in the art that the amount of aminoplast foam particles required in each instance will vary, depending upon the particular type and a- mount of biological waste and its condition when brought into contact with said foam particles. However, as a general rule, an amount of foam particles which are sufficient to substantially absorb the moisture present in the biological waste and cover it with a layer of from about 1 to 3 centimeters, will suffice. Of course, substantially more or less of the solid particulate ami- noplast foam will be required in certain cases. However, the a- mount required in each case will readily become apparent to

SUBSTITUTESH5ET those of skill in the art upon repeated use with a given bio¬ logical waste.

The wet solid particulate aminoplast foams of the invention have a wide variety of applications related to disposal of bio- logical wastes. For example, when surgically removed organs, tissue or blood are treated with the instant aminoplast foam particles, they can be stored at room temperature for periods of from one to ten days or more without evident development of foul odor and with minimal decomposition. Ordinary storage of suchwastes gives rise to foul odors and evident decomposition within several hours at room temperature.

If biological wastes such as, for example, expired animal bodies, waste organs or tissue are to be stored for more than a few hours, they must be refrigerated or frozen to avoid de- composition, etc. Use of the particulate aminoplast foams of the invention allows for storage of such wastes at ambient tempera¬ ture for extended periods, without development of substantial odor or decomposition.

As mentioned above, the invention method is also useful in treating blood containing wastes to destroy the HIV virus. Of course, other viruses, such as for example those which are caus¬ ative for herpes and hepatitis infections, are also destroyed. The following examples are illustrative of the invention. Example 1

A 55 gallon (208 liter) drum containing 50 gallons (189 li¬ ters) of urea formaldehyde resin prepolymer and 7% fructose by weight of resin, is mixed with 51.5 gallons (199 liters) of foaming agent, which two components are expanded into a foam. weighing approximately 2.5 lbs. per cubic foot by compressed air at a pressure of 100 p.s.i. (293 kg/cm2) . The foaming agent was prepared by mixing 2.5 gallons (9.5 liters) of concentrate with 50 gallons (189 liters) of concentrate with 50 gallons (189 liters) of tap water. The foaming agent concentrate consisted of a commercial sodium alkylnaphthalene sulfonate and 10 lbs. (4.54) kg) phosphoric acid accelerator (2% phosphoric acid by weight, based on the weight of resin) .

- * > __. i_ Ei» • By means of a foaming gun equipped with a wand, the equip¬ ment is that disclosed by Kramer in U.S. Patent No. 4,421,788, a 6 to 12 inch (15 to 30 cm) thick layer of foam was deposited on¬ to plastic sheets (5 mils thick, 12 x 50 ft.) and then covered with another plastic sheet to cure overnight. The cured foam was cut into chunks of about 12 x 12 x 18 inches (30 x 30 x 45 cm) which were rubbed on a wire mesh screen mounted over an open clean 55 gallon drum. The wire mesh was 0.375 to 0.50 inches (9.5 to 12.7 mm) . The resulting wet particulate solid aminoplast foam was promptly transferred to one gallon (3.5 liter) poly¬ ethylene bags which were tied shut to provide an airtight container. The particles range in size from about one to ten millimeters in diameter and are found to contain 0.35% unreacted formaldehyde by weight. The moisture content of the foam was 75% by weight.

Example 2 In a veterinary hospital, a pregnant female cat was spayed, during which six fetuses and the cat's uterus were removed. The fetuses, uterus and associated wastes and blood were all depos- ited into a red plastic receptacle bag. A large handful of the above aminoplast foam particles was thrown into the receptacle. This was sufficient to absorb the apparent liquids present in the waste and cover it with a thin about (about 5 to 10 mm) lay¬ er of particles. The bag was closed closed by means of the at- tached drawstring and stored under ambient conditions for seven days. Upon opening the bag, the contents were free of foul odor and little evidence of decomposition of the wastes was noted. By contrast, when a comparable waste is stored for 24 hours, but without addition of the aminoplast particles, under comparable conditions, an intense foul odor is very apparent and substantial decomposition is evident.

Example 3

In the same veterinary hospital, the foul smelling excrement from a dog suffering from severe diarrhea was received in a pan beneath the screen cage. The excrement was covered with a 3 to 6 mm layer of the instant aminoplast foam particles. The liquid

SUBSTITUTE SHEET excrement was substantially absorbed and the foul odor was not apparent after a few minutes. After storage overnight at room temperature, the contents of the pan was still found to be free of malodor. Example 4

Under ordinary conditions employed in veterinary hospitals and medical research laboratories, dead animals must be stored under refrigeration prior to disposal to avoid the development of obnoxious odors and decomposition. When a dead cat was placed in a red plastic waste disposal receptacle bag and covered with a layer of the above aminoplast foam particles, it was stored at ambient temperature (23°C) without evidence of decomposition or development of foul odor for 24 hours.

When the above procedure is repeated with various dead ani- mals, including dogs, mice rats and hamsters, the results are substantially the same.

Exampl 5

In an animal crematorium a, dead dog had been stored in an open 55 gallon drum for several days, at ambient termperture, prior to incineration. The dead dog developed substantial obnox¬ ious odors and decomposed. When the dead dog was covered with a layer of two or three inches of the above aminoplast foam parti¬ cles, the odor was taken away.

Example 6 In medical hospitals, red plastic waste disposal bags (bed bags) disposed open within a cardboard container, are used for disposal of medical wastes. These bags are kept at the bedside of each patient. During the course of the day, all of the pa¬ tients medical wastes, including bandages, disposable syringes, used paper towels and napkins and the like are put into the bed bags, which are removed each day for disposal.

When one or two handfulls of the wet aminoplast foam parti¬ cles of Example 1 are placed in each bag, they can be kept at the bedside for two days without development of offensive odor or appearance.

The terms and expressions which are employed are used as

Si V iSi f i c f terms of description; it is recognized, though, that various modifications are possible.

It is also understood the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the inven¬ tion which, as a matter of language, might fall therebetween.

SUBSTITUTESHEET

Claims

Having described certain forms of the invention in some de¬ tail, what is claimed is:

1. A method for maintaining a biological waste material un¬ der sanitary conditions which comprises the steps of: (a) generating a wet urea formaldehyde aminoplast foam containing unreacted formaldehyde,

(b) breaking up the aminoplast foam into particles hav¬ ing a diameter in the range of from 0.5 to 20 millimeters,

(c) maintaining said particles in a sealed airtight en- vironment until ready for use, and

(d) providing said particles in needed quantity in an environment which contains or is intended to contain a biologi¬ cal waste material, said particles being present in an amount that will generate formaldehyde at a level which is suitable for control of microbial growth on said waste material.

2. A method according to claim 1 wherein in step (a) said aminoplast foam is prepared from:

(i) an aqueous solution of urea and formaldehyde, me- thylolurea, dimethylolurea, or methylolurea or dimethylolurea modified with from 4 to 12% fructose by weight,

3. A method according to claim 2 wherein said wet foam gen¬ erated is formed into a thick layer which is maintained under conditions which minimize loss of water and formaldehyde from said foam while it cures to a solid.

4. A method according to claim 3 wherein said layer is from 6 to 12 inches thick and loss of water and formaldehyde is mini¬ mized by covering the layer with plastic sheets.

5. A method according to claim 2 wherein said acid ac¬ celerator is phosphoric acid or oxalic acid and said weight of fructose is from 7 to 10%.

6. A method according to claim 2 wherein said particles have a diameter of from one to ten millimeters.

7. A method according to claim 2 wherein said wet plastic foam contains from 0.05 to 1% unreacted formaldehyde by weight and from 60 to 80% water by weight.

8. A method according to claim 7 wherein said plastic foam contains from 0.1 to 0.5% unreacted formaldehyde by weight and from 70 to 80% water by weight.

9. A method according to claim 1 wherein said biological waste material is a member selected from the group consisting of an animal tissue, animal organ, bandage, used syringe, a body fluid and a bodily excretion.

10. A method according to claim 9 wherein said animal is a human.

11. A method according to claim 10 wherein said waste mate¬ rial is a body fluid.

12. A method according to claim 11 wherein said body fluid is blood.

13. A particulate form of a urea formaldehyde aminoplast foam when prepared by the method of claim 1, steps (a) and (b) .

14. A particulate form of a urea formaldehyde aminoplast foam when prepared by the method of claim 2.

15. A method according to claim 1 including the step of pro¬ viding said particles in sufficient quantity to absorb liquid from said waste.

16. A method according to claim 2 including the step of pro- viding said particles in sufficient quantity to absorb liquid from said waste.

17. A method for maintaining a biological waste material un¬ der sanitary conditions which comprises the steps of:

(b) breaking up the aminoplast foam into particles hav¬ ing a diameter ^"in the range of from 0.5 to 20 millimeters,

(c) storing said particles in a sealed airtight con¬ tainer, and (d) as needed, adding said particles to a receptacle which contains or is intended to contain a biological waste a terial, said particles being present in an amount that will gen¬ erate formaldehyde at a level which is suitable for control of microbial growth on said waste material.

18. A method according to claim 17 wherein in step (a) said aminoplast foam is prepared from:

19. A method according to claim 17 including the step of providing said particles in sufficient quantity to absorb liquid from said waste.

20. A method according to claim 18 including the step of providing said particles in sufficient quantity to absorb liquid from said waste.

SUESTITUTE STO