Note: Descriptions are shown in the official language in which they were submitted.
CA 02380012 2002-02-11
WO 01/08824 PCT/US00/20562
1
Methods of Treating Waste
FIELD OF INVENTION
The present invention relates generally to a new method of treating
waste. Preferably, the present invention relates to a method of treating
articles of regulated wastes comprised of an acid polymer or a thermoplastic
polymer and a contaminant by degrading and/or chemically treating the
article.
BACKGROUND OF THE INVENTION
1o Waste disposal is an increasingly problematic concern for industrial
facilities. Over the past 20 years, governments around the world have
tightened environmental pollution regulations, resulting in stricter disposal
requirements. Regulated wastes particularly have experienced tighter waste
disposal regulations. The problem is magnified by the fact that ordinary
wastes can become hazardous simply be coming into contact, and absorbing
minimal amounts of regulated wastes. One particularly troublesome
regulated waste is generated from industrial painting.
Industrial painting is ordinarily performed in paint spray booths. In
a paint spray booth, paint over-spray indiscriminately contacts the walls,
2o and equipment located on the sides and overhead. Equipment is typically
protected from paint over-spray with disposable equipment jackets, and
walls can be protected by similar protective materials. However, these
equipment jackets and protective materials become splattered with the paint
over-spray, thereby making the equipment j ackets a regulated waste.
Consequently, when the equipment jackets or wall covers are removed, they
must be disposed of as a regulated waste. The disposal costs for items such
as equipment jackets is particularly burdensome due to the hazard level and
the volume of waste generated.
Disposal costs generally depend on the level of the waste's hazard
3o and the volume. The more hazardous the waste, the fewer available
CA 02380012 2002-02-11
WO 01/08824 PCT/US00/20562
2
disposal sites and the more expensive the disposal cost. Likewise, for any
waste, the bulkier the waste, the higher the disposal cost.
These problems with waste disposal have lead to a number of waste
treatment methods. Several methods treat waste by separating as many re-
usable and valuable fractions as possible. Other methods decontaminate
waste by directly heating the waste with a fluid.
SUMMARY OF THE INVENTION
The present invention relates to a method for treating wastes. One
to aspect of the present invention relates to a method of treating an article
of
regulated waste comprising the steps of: (a) providing an article comprising
at least one acid polymer and at least one contaminant; (b) dissolving at
least a portion of the article in a disposal liquid thereby creating a waste
mixture comprising waste solids and the disposal liquid; and (c) treating the
15 waste solids.
Another aspect of the present invention relates to a method of
treating an article of regulated waste comprising the steps of: (a) providing
an article comprising at least one thermoplastic polymer and at least one
contaminant; (b) dissolving at least a portion of the article in a disposal
2o liquid (i) to introduce at least a portion of the contaminants into the
disposal liquid and (ii) to create a waste mixture; (c) separating the
disposal
liquid from the waste mixture to obtain waste solids; and (d) treating the
waste solids to render a non-regulated waste.
Additional objectives and advantages of the invention will be set
25 forth in part in the description which follows, and in part will be obvious
from the description, or may be learned by practice of the invention. The
advantages of the invention will be realized and attained by means of the
elements and combinations particularly pointed out in the appended claims.
It is to be understood that both the foregoing general description and the
CA 02380012 2002-02-11
WO 01/08824 PCT/US00/20562
3
following detailed description are exemplary and explanatory only and are
not restrictive of the invention, as claimed.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention may be understood more readily by reference
to the following detailed description of preferred embodiments of the
invention and the Examples included therein.
Before the present compounds, compositions, articles, devices,
and/or methods are disclosed and described, it is to be understood that this
1o invention is not limited to specific articles of regulated waste, as such
may,
of course, vary. It is also to be understood that the terminology used herein
is for the purpose of describing particular embodiments only and is not
intended to be limiting.
As used in the specification and the appended claims, the singular
15 forms "a," "an" and "the" include plural referents unless the context
clearly
dictates otherwise. Thus, for example, reference to "an article" includes
mixtures of articles, reference to "a thermoplastic polymer" includes
mixtures of two or more such thermoplastic polymers, and the like.
Ranges may be expressed herein as from "about" one particular
2o value, and/or to "about" another particular value. When such a range is
expressed, another embodiment includes from the one particular value
and/or to the other particular value. Similarly, when values are expressed as
approximations, by use of the antecedent "about," it will be understood that
the particular value forms another embodiment. It will be further
25 understood that the endpoints of each of the ranges are significant both in
relation to the other endpoint, and independently of the other endpoint.
In this specification and in the claims which follow, reference will
be made to a number of terms which shall be defined to have the following
meanings:
CA 02380012 2002-02-11
WO 01/08824 PCT/US00/20562
4
References in the specification and concluding claims to parts by
weight, of a particular element or component in a composition or article,
denotes the weight relationship between the element or component and any
other elements or components in the composition or article for which a part
by weight is expressed. Thus, in a compound containing 2 parts by weight
of component X and 5 parts by weight component Y, X and Y are present at
a weight ratio of 2:5, and are present in such ratio regardless of whether
additional components are contained in the compound.
A weight percent of a component, unless specifically stated to the
1o contrary, is based on the total weight of the formulation or composition in
which the component is included.
By the term "effective amount" of a compound or property as
provided herein is meant such amount as is capable of performing the
function of the compound or property for which an effective amount is
expressed. The exact amount required will vary from process to process,
depending on recognized variables such as the compounds employed and
the processing conditions observed. Thus, it is not possible to specify an
exact "effective amount." However, an appropriate effective amount may
be determined by one of ordinary skill in the art using only routine
2o experimentation.
"Acid polymer" means a polymer that forms a salt in a basic
aqueous solution, such as aqueous solutions with a pH above about 7Ø
Example acid polymers include, but are not limited to, ethylene acrylic acid
polymers, ethylene methacrylic acid polymers, and derivatives, copolymers,
and mixtures thereof. Acid polymers are not water soluble in neutral pH
conditions at ambient temperatures but become soluble in water under
suitable pH and temperature conditions.
"Bi-directional Shake Test" means a test that measures the number
of particles generated and released by a stressed equipment jacket. This
test is based on American Standard Test Method F51.
CA 02380012 2002-02-11
WO 01/08824 PCT/US00/20562
"Biologically hazardous material" means infectious material,
potentially infectious material, and biologically active material such that an
article contaminated with this material is rendered a regulated waste. One
nonlimiting example of biologically active material is a pharmaceutical
agent.
"Chemically treating" means contacting an article with a chemical
other than water that chemically reacts with the article, or alters the charge
characteristics of the article, as opposed to simply encapsulating the
article.
"Contaminants" within the context herein means any material that
to renders an article a regulated waste. Example contaminants include, but are
not limited to, oil, paint, hydrocarbons, biologically active materials,
infectious material, potentially infectious material, and radioactive
material.
"Degrade" means to lessen the structural integrity and, to subdivide
the material into a greater number of parts. Thus, the degradation can occur
by shredding (i.e. cutting, grinding, or chopping), crushing, or at a
molecular level by dispersing or dissolving the material. The dispersion can
be only partial, but the article will still be considered to have been
dispersed
within the meaning of this document. For example, when certain
combinations of polymeric materials are used, less than half (by weight) of
2o the material may be dispersed or dissolved in solution. The remainder is
broken into pieces that can be retrieved. Degradation preferably facilitates
the eventual treatment of the material's hazardous characteristics, and
preferably occurs in a disposal liquid.
"Degradable polymer" means a polymer that undergoes a significant
change in its chemical structure under specific environmental conditions
resulting in a loss of some properties. Example degradable polymers
include hydrolytically degradable polymers such as polylactic acid,
polyesteramides, polyglycolic acid, polyhydroxy butyrate-co-valorate and
the like, and combinations thereof as copolymers, blends, mixtures, and the
3o like.
CA 02380012 2002-02-11
WO 01/08824 PCT/US00/20562
6
"Disperse" means that upon contact with a fluid under appropriate
conditions, the material disperses partially or completely into the fluid to
form a dispersion.
"Dissolve" means that upon contact with a fluid under appropriate
conditions, the weight of solid material is reduced by partial or complete
dissolution of the material into solution. In both dispersible and dissolvable
materials, the material preferably fragments or breaks apart structurally, if
it
does not dissolve or disperse completely.
"Hazardous" describes a solid waste, or combination of a solid and
liquid waste, which because of its quantity, concentration, or physical,
chemical, or infectious characteristics:
(a) may cause, or significantly contribute to an increase in mortality
or an increase in serious irreversible, or incapacitating reversible, illness;
(b) may pose a substantial present or potential hazard to human
health or the environment when improperly treated, stored, transported, or
disposed of, or otherwise managed; or
(c) has been defined as a hazardous substance in 42 U.S.C. 9601 or
by the Administrator of the Environmental Protection Agency.
Thus, articles of regulated waste include infectious waste generated
2o at hospitals (i.e. articles that have come into contact with bodily
fluids), and
industrial waste that must typically be managed as a "hazardous substance"
under 42 U.S.C. 9601, such as articles contaminated by paint.
"NDP" stands for novel degradable polymer and when used in this
specification refers to an ethylene-(meth)acrylic acid copolymer.
"Ethylene-(meth)acrylic acid copolymer," in turn, means a copolymer of
ethylene and acrylic acid, a copolymer of ethylene and methacrylic acid, a
mixture of copolymers of acrylic and methacrylic acids or terpolymers of
acrylic acid, methacrylic acid and ethylene. The ethylene-(meth)acrylic
acid copolymer preferably comprises 10-30 wt.% acid residues, more
3o preferably 15-25 wt.%.
CA 02380012 2002-02-11
WO 01/08824 PCT/US00/20562
7
The NDP may be present as an acid polymer. As used herein, the
term "ionomer" means a copolymer of ethylene and (meth)acrylic acid,
wherein the copolymer has been neutralized with a metal canon. Ethylene-
(meth)acrylic acid ionomers are typically obtained by partially reacting an
ethylene-(meth)acrylic acid copolymer with a metallic salt to form ionic
crosslinks between the (meth)acrylic acid moiety residues within a
copolymer chain or between neighboring chains. The cationic charge of the
metallic salt partially neutralizes the acid residues of the copolymer.
Preferably, about 50 to 60% of the residues of acidic moieties are
to neutralized; more preferably, about SS% of the acidic moiety residues are
neutralized. Suitable canons for neutralizing the acidic moieties are Na+,
K+, Li+, Cs+, Rb+, Hg+, Cu+, Be2+, Mg2~, Ca2+, Sr2+, Ba2+, Cu2+, Cd2+, Hg2+,
Snz+, Pb2+, Fe2+, Co2+, Ni2+, Zn2+, A13+, Sc3+, Fe3+ and Y3+. Preferred
cations include sodium, lithium and potassium ions.
The NDP may also be present as a blend of ionomer and ethylene-
(meth)acrylic acid copolymer. The blend of ionomer and ethylene-
(meth)acrylic acid copolymer can be present at various ratios, including less
than or greater than 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3,
1:4,
1:5, 1:6, 1:7, 1:8, and 1:9.
2o NDP is disclosed in U.S. Application Serial Nos. 08/923,698 and
08/766,765 which are incorporated by reference their entireties. A
particularly preferred NDP for film applications is NDP Treatable FiImTM
commercially available from Isolyser Company, Inc., Norcross, Georgia.
"Optional" or "optionally" means that the subsequently described
event or circumstance may or may not occur, and that the description
includes instances where said event or circumstance occurs and instances
where it does not. For example, the phrase "optionally substituted lower
alkyl" means that the lower alkyl group may or may not be substituted and
that the description includes both unsubstituted lower alkyl and lower alkyl
where there is substitution.
CA 02380012 2002-02-11
WO 01/08824 PCT/US00/20562
8
"Potentially infectious" means including, but not limited to, blood
and body fluids and materials or articles contaminated with blood or body
fluids that are typically considered to be infectious.
"Radioactive" means a material or article contaminated with
radioactive isotopes.
"Regulated Waste" includes ( 1 ) hazardous; (2) potentially
infectious; and (3) radioactive wastes. A "non-regulated waste" is a waste
that is not considered a regulated waste as disclosed herein.
"Readily Releasable Particles" means particles that exist on the
1o surface of a cover or jacket and can be removed without the application of
mechanical energy. This test is based on American Standard Test Method
F51. "Particle" means a solid or liquid object generally between 0.001 and
1000 ~m in size. The most common particle is lint."Surface Resistivity"
means resistance measured in ohms/square at 73°F and 50% relative
humidity.
"Thermoplastic polymer materials" means thermoplastic polymers,
thermoset polymers, solvent castable polymers, natural polymers, and
derivatives and copolymers of these polymers. These materials may be
manufactured into panels of knitted fabrics, woven fabrics, non-woven
2o fabrics, films, and molded panels using any available manufacturing method
including, but not limited to: single knit, double knit, interlock knit,
warped
knit, crocheted knit, air laid, dry laid, wet laid, hydroentangled, thermo
bonded, chemical bonded, blown extrusion, cast extrusion, hot melt
processing, blow molding or injection molding. These thermoplastic
polymer materials may be composites or a single layer.
"Water soluble" means that the polymer will completely dissolve
upon extended contact with water. Nonlimiting examples of water soluble
polymers include polyvinyl alcohol, poly aspartic acid, polyacrylic acid,
polymethacrylic acid, polyacrylamid, polyvinyl pyrrolidone, polyalkylene
CA 02380012 2002-02-11
WO 01/08824 PCT/US00/20562
9
oxides, complex carbohydrates, and derivatives, copolymers and mixtures
thereof.
Articles of regulated waste can be present in many forms, and
include knitted fabrics, woven fabrics, non-woven fabrics, films, and
molded parts of polymers configured using any available manufacturing
method including, but not limited to: single knit, double knit, interlock
knit, warped knit, crocheted knit, air laid, dry laid, wet laid,
hydroentangled,
thermo bonded, chemical bonded, blown extrusion, cast extrusion, hot melt
processing, blow molding or injection molding. Polymeric materials may
1o be composites or a single layer. Other articles of regulated waste may
include, but are not limited to, surgical drapes and gowns, woven sponges
and towels, personal protective garments, wipes, collection devices (such as
suction canisters), and equipment covers.
The article of regulated waste preferably comprises an acid polymer,
a thermoplastic polymer, natural fabric or fiber, or any combination of these
materials. One preferred class of articles comprises acid polymers alone or
in combination with water soluble polymers, degradable polymers and/or
dispersable polymers.
Examples of specific polymeric materials include polylactic acid,
2o polyethylene, polypropylene, ethylene vinyl acetate, polybutylene,
polyolefin, polyester, polyurethane, polyacrylate, polymethacrylate,
polyvinyl chloride, polyvinyl acetate, cellophane, polyvinyl alcohol, and
NDP, and blends of these materials. Polyvinyl alcohol and NDP are
preferred polymeric materials. Particularly suitable natural fabric or fiber
includes cotton, wool, leather, and silk, and blends of these materials.
Articles of regulated waste are discussed above. Used equipment
covers and jackets are examples of regulated waste. The ink industry uses
similar covers that can benefit from these improved disposal processes.
Infectious waste from hospitals benefits from these processes as well. The
3o article can be present as a film, a shaped and molded article, or as a
fibrous
CA 02380012 2002-02-11
WO 01/08824 PCT/US00/20562
fabric. The article can be absorbent, and can, for example, be used as an
industrial wipe to manage spills of hazardous materials, or to otherwise
wipe up hazardous liquids. Moreover, the article can be a fabric, a plurality
of non-fabric fibers, or granular material when used for such absorption.
5 The material can also be a filter used to trap fluid-borne contaminants from
liquid or gas streams.
One type of cover, and jackets that can be employed in the present
invention, are those articles that sustain a low release of particles. By "low
release" it is meant that the jacket is functional as an equipment jacket in a
1o desired low particle environment. This can be measured in a variety of
manners. For example, one preferred embodiment of the invention relates
to an article with less than 500,000 readily releasable particles per square
meter of equipment jacket, more preferably less than 100,000 readily
releasable particles per square meter. Another preferred embodiment of the
method of disposal of the present invention uses an article with less than 2.5
million particles per square meter of equipment jacket as measured with the
bi-directional shake test, more preferably less than 200,000 particles per
square meter. A further embodiment uses an article devoid of particles that
are readily visible to the naked eye.
2o The above-described low release of particles may result with or
without anti-particle treatment. Suitable anti-particle treatments include
laundering and application of surface coating agents.
The equipment that is protected by the article may contain delicate
electronic parts that are susceptible to damage from static electricity.
Therefore, a preferred embodiment of the invention provides a method of
disposal of an article that has anti-static properties and/or comprises an
anti-
static agent. Example antistatic agents include amines, glycerol esters,
quaternary ammonium compounds, anionics, alkane sulfonates, and the like
as disclosed in Modern Plastics, Mid-November 1998 issue, pages C47-
3o C51, which is incorporated in this application in its entirety.
Alternatively,
CA 02380012 2002-02-11
WO 01/08824 PCT/US00/20562
11
the article may have anti-static properties. One indication of anti-static
properties is surface resistivity. A suitable surface resistivity is based on
the
particular industrial application in which the article is employed. For
example, the NFPA (National Fire Protection Agency) standard for surface
resistivity is 1 x 101' ohms/square. Where anti-static properties are an
issue, it can often be desirable to meet this standard.
The articles) may be comprised of a monolithic film of
thermoplastic polymer material. Alternatively, the articles may be
comprised of additional layers, such as a reinforcing layer. The
to thermoplastic polymer panels) may have any thickness such that it has
sufficient strength to withstand the required use. One preferred
embodiment has a thermoplastic polymer panels) thickness of about 0.01
mm to about 0.6 mm. More preferably, the thickness is about 0.02 mm to
about 0.2 mm, with the range of about 0.03 mm to about 0.6 mm as the
most desirable thickness, most preferably 0.06 mm.
Similar articles can be used in medical applications where they can
become contaminated with blood and body fluids, which may be potentially
infectious. Treatment of these articles may include disinfection (signifying
a 106 reduction in vegetative microorganisms in an aqueous solution at
temperatures above 90 °C) or sterilization (defined as 106 reduction in
Bacillus spores) in an aqueous solution at temperatures above 118
°C for
time intervals appropriate to the level of treatment.
These same articles may also be contaminated with radioactive
waste. Degradation of these articles will release the radioactive
contamination into an aqueous solution which may be held for half life
degradation or filtering. The resulting aqueous solution can be safely
discharged.
The article may comprise paint, a liquid hydrocarbon, oil, ink, or
combinations of these substances. In one preferred embodiment, the article
3o comprises a polymeric material, natural fabric or fiber, and further
CA 02380012 2002-02-11
WO 01/08824 PCT/US00/20562
12
comprises paint, a liquid hydrocarbon, oil, ink, or combinations of these
substances, that have been splattered on or absorbed by the article.
A step of the process involves treating the article so as to dissolve
and/or degrade a portion of the article.
Degradation can occur by any of the methods discussed above. In a
preferred embodiment, the degradation occurs while contacting the article
with a disposal liquid at temperatures above about 37°C, 40°C,
45°C,
50°C, 55°C, 60°C, 65°C, 70°C,75°C,
80°C, 85°C, 90°C, 95°C, 100°C,
105°C, 110°C, 115°C, 120°C, 125°C,
130°C, 140°C, 150°C, 160°C,
170 ° C, 180 ° C, 190 ° C, 200 ° C, with
temperatures above 90 ° C particularly
preferred. Such high temperature treatment has two potential benefits: (1)
many materials dissolve or disperse in hot liquid (such as polyvinyl alcohol
and NDP), and dissolve or disperse better at hotter temperatures; and (2)
higher temperatures can disinfect the article and render it nonhazardous.
Higher temperatures are thus desirable whenever disinfection is desired,
regardless of the method of degradation. The high temperature treatment
can occur separately from any other step of the process, or alternatively the
article can be degraded, and/or chemically treated during or by the high
temperature treatment.
In still another preferred embodiment, the degradation occurs while
contacting the article with a disposal liquid of pH greater than about 6.5,
7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5,
or
14.0, where a pH greater than 10.0 is especially preferred. Such high pH
treatments are especially preferred when degrading articles comprising acid
polymers that degrade best at higher pH levels. In a particularly preferred
embodiment, the article comprises NDP, and is degraded at elevated pH
levels and temperatures. Any combination of temperature and pH can be
employed in the inventive process. These processes can include pH and
temperature combinations which are consistent with commercial and
3o traditional laundering, e.g., on the order of 70°F and pH on the
order of 9.5
CA 02380012 2002-02-11
WO 01/08824 PCT/US00/20562
13
to 12Ø In addition, combinations of pH and temperature conditions which
are greater than those associated with traditional or commercial washing can
be preferred in certain embodiments.
Where dispersable polymers, water soluble polymers and/or acid
polymers are employed, at least a portion of the article is dissolved in the
disposal liquid to form a waste mixture. The disposal liquid acts as a heat
and/or chemical transfer medium. As such, any suitable disposal liquid may
be used. Example disposal liquids include, but are not limited to, water.
The disposal liquid may include additional components that act as
1o processing aid, such as, but not limited to, surfactants, acids, bases, and
coagulants.
In one embodiment the article is degraded by shredding and
dispersing and/or dissolving the article, either simultaneously or
consecutively. In the case of articles made from acid polymers such as
NDP, degradation can be enhanced by shredding the article before or during
the pH and temperature treatment.
The process of the present invention includes the dissolution of at
least a portion of the article in the disposal liquid so as to form a waste
mixture comprising waste solids and the disposal liquid which preferably
2o includes at least a portion of the contaminants. The waste mixture
containing degraded waste solids and the disposal liquid, can be further
processed after dissolution by suitable treatment. The waste solids can be
treated by processes such as chemical treatment, disinfection, and
deactivation of biologically active materials.
Chemical treatment can occur by many methods known to workers
skilled in the art. For example, a paint contaminated article that has been
sufficiently degraded can be chemically treated. Chemical treatment can
also occur by contacting the article with a basic solution. The higher pH
can disinfect the article or render it nonhazardous. For example, a high pH
detackifies paint and renders articles contaminated by paint less hazardous.
CA 02380012 2002-02-11
WO 01/08824 PCT/US00/20562
14
The high pH treatment can thus function as chemical treatment apart from
the degradation step, or alternatively the article can be degraded and
chemically treated in the high pH.
Disinfection and/or deactivation of biologically active materials may
include denaturing proteins. This process may be performed by any
suitable method including, but not limited to, heat or an antimicrobial agent.
Any suitable antimicrobial/antifungal agent may be used, such as
chlorohexidine glucanate, iodophores, pyrithiones, isothiazolines, or
benzimidazoles. These agents may be present in any effective amount.
1o Treatment can preferably involve separating the waste solids from
the disposal liquid. The waste solids can then be disposed or further
processed, and the disposal liquid discharged with other waste water.
Depending on the size and nature of the waste solids, a number of
separation techniques may be used, including filtering and skimming. The
separated waste solids can then be dewatered and treated.
If some or all of the article has been dissolved or dispersed, it may
be appropriate to further treat the waste solids to facilitate its separation
from the disposal liquid. For example, when the article comprises NDP,
and has been degraded in a hot caustic solution, acid can be used to
2o precipitate the NDP out of solution. In a preferred embodiment, the pH of
the solution is lowered to 8.5 or below by adding an acid such as sulfuric
acid. Still further, the precipitated solids can be coagulated with a
coagulant such as alum to even further facilitate separation. Other
appropriate coagulants include, but are not limited to, aluminum and ferric
compounds and organic macromolecules known as polyelectrolytes (or
polymers). A proper dosage of the right polyelectrolyte can improve
finished water quality while significantly reducing sludge volume and
overall operation costs. Suitable coagulating and flocculating agents are
described in "E verything you want to know about Coagulation &
CA 02380012 2002-02-11
WO 01/08824 PCT/US00/20562
Flocculation," Zeta-Meter, Inc., 1993, which is incorporated herein by
reference in its entirety.
Thus, the invention provides a number of ways that regulated waste
streams can be managed. By degrading hazardous articles into smaller
5 pieces, one is able to better treat the article chemically. Treatment of
articles contaminated with paint is a good example. Although presented as
an example of the invention, it should in no way limit the scope of the
invention.
In this example, dissolution of a paint contaminated article gives
1o waste paint solids in a disposal liquid. However, complete dissolution of
the contaminated article is not necessary to employ these treatment
methods. These treatment methods can also be employed if the article is
degraded into pieces or particles which, because of their reduced size, can
be treated by similar methods. Thus, in one embodiment, the waste mixture
15 is treated to separate the waste paint solids which are then introduced to
a
paint sludge pit and managed along with the paint sludge from a paint
booth. In another embodiment, the article and/or any dissolved or dispersed
waste solids are recovered from the disposal liquid, and the liquid
discharged to an on-site waste water treatment process.
2o The degradation of the contaminated article can also facilitate
further processing of the waste other than by chemical treatment. Thus, as
mentioned above, the waste can be subsequently processed by shredding,
compacting or crushing. The material that is obtained is greatly reduced in
volume, and is more readily disposed. In a particularly useful embodiment,
one or more of the articles in a waste stream is degraded by dissolution or
dispersion, and reclaimed. The reclaimed articles and/or solids can then be
further processed by shredding, compacting or crushing (or otherwise
reduced in volume) before disposal. Sometimes valuable articles will
remain intact after the initial degradation step. When such articles are
3o present they can be recovered, and reused, before the rest of the waste
CA 02380012 2002-02-11
WO 01/08824 PCT/US00/20562
16
stream is further processed before disposal. This method has particular
application to medical waste, which can be disinfected during either the
degradation or shredding.
In one embodiment the method is used to treat articles collected in a
bag, in which only some of the articles are degradable, or the articles do not
fully dissolve or disperse when degraded. If the bag is degradable, then the
contents of the bag can be processed by first subjecting the bag and its
contents to degradation conditions (and optionally disinfection or chemical
treatment). Any contents that do not degrade, or which only partially
1o degrade, can be reclaimed after the degradation step, and either segregated
for reuse, or further processed by shredding, compacting or crushing. To
facilitate reclamation, the degradable bag and its contents can be placed into
a mesh bag or basket that does not degrade. Alternatively, the degradable
articles can be placed directly into the mesh bag or basket.
This invention can be further illustrated by the following examples
of preferred embodiments, although it should be understood that these
examples are included merely for purposes of illustration and are not
intended to limit the scope of the invention unless otherwise specifically
indicated. The starting materials are commercially available unless
otherwise described. All percentages are by weight unless otherwise
described.
Experimental
The following examples are put forth so as to provide those of
ordinary skill in the art with a complete disclosure and description of how
the compounds, compositions, articles, devices and/or methods claimed
herein are made and evaluated, and are intended to be purely exemplary of
the invention and are not intended to limit the scope of what the inventors
regard as their invention. Efforts have been made to ensure accuracy with
3o respect to numbers (e.g., amounts, temperature, etc.), but some errors and
CA 02380012 2002-02-11
WO 01/08824 PCT/US00/20562
17
deviations should be accounted for. Unless indicated otherwise, parts are
parts by weight, temperature is in °C or is at ambient temperature, and
pressure is at or near atmospheric.
Example 1
A 1.5 gram sample of NDP film was covered with a solvent-based primer
paint. The film was immersed in a 0.2 -0.5 wt% NaOH solution (5 wt.%
NDP, 95 wt.% NaOH solution) at 95 °C and agitated. A suspended
solution
was obtained from this procedure. The pH of the suspended solution was
about 12.0 units. The biochemical oxygen demand ("BOD"), chemical
to oxygen demand ("COD") and total suspended solids ("TSS") were
measured and the results are recorded as the "suspended solution" sample in
table 1.
A sulfuric acid solution was added to the suspended solution to bring the pH
below 8.0 units. Precipitation of the NDP and paint particles occurred when
the pH dropped below 8.5 units. A 5% alum solution was added to the
solution and this accelerated the rate of precipitation. After 20 minutes of
settling, the NDP and paint particles sank to the bottom of the container and
a clear supernatant layer remained on top. The supernatant was decanted
and measured for BOD, COD and TSS, reported as "supernatant" in table 1.
2o The settled NDP and paint particles were filtered and collected. Filtrate
water passed through the filter paper quite easily. A Toxicity Characteristic
Leaching Procedure ("TCLP") was performed on the filtered solids. The
results of the TCLP test indicated that the settled solids were below
regulatory limits for metals, volatiles and semi-volatiles, thus making the
solids a non-regulated waste.
CA 02380012 2002-02-11
WO 01108824 PCT/US00/20562
18
Table 1: Primer Paint- solvent based
Sample BOD (mg/Ll COD (mg/Ll TSS (mg/Ll
Suspended
solution 1500 6200 14000
Supernatant 1300 6000 110
Example 2
A 1.5 gram sample of NDP film was covered with a water-based color paint
1o and treated as described in example 1. The sample did not settle as quickly
or filter as easily as in example 1, but a clear supernatant was still
obtained.
The results for BOD, COD and TSS for the suspended solution and the
supernatant are included in table 2. The TCLP results indicated that the
settled solids were below regulatory limits for metals, volatiles and semi-
volatiles, thus making the solids a non-regulated waste.
Table 2: Color Paint- water based
Sample BOD lm~/Ll COD (mg/L) TSS lmg/L~
Suspended
solution 1200 10000 17000
Supernatant 330 2200 69
Example 3
A 1.5 gram sample of NDP film was covered with a solvent-based
clear paint and treated as described in example 1. The sample quickly
settled and filtered easily, but the supernatant was cloudy. The results for
BOD, COD and TSS for the suspended solution and the supernatant are
included in table 3. The TCLP results indicated that the settled solids were
3o below regulatory limits for metals, volatiles and semi-volatiles, thus
making
the solids a non-regulated waste.
CA 02380012 2002-02-11
WO 01/08824 PCT/LJS00/20562
19
Table 3: Clear Paint- solvent based
~ple BOD lmg/Ll COD (m /g-L1 TSS (m~/Ll
Suspended
solution 1400 8400 19000
Supernatant 100 4100 480
Throughout this application, various publications are referenced.
The disclosures of these publications in their entireties are hereby
1o incorporated by reference into this application in order to more fully
describe the state of the art to which this invention pertains.
It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention without
departing from the scope or spirit of the invention. Other embodiments of
the invention will be apparent to those skilled in the art from consideration
of the specification and practice of the invention disclosed herein. It is
intended that the specification and examples be considered as exemplary
only, with a true scope and spirit of the invention being indicated by the
2o following claims.
