U.S. patent application number 13/650607 was filed with the patent office on 2013-02-14 for microwave remediation of medical wastes.
This patent application is currently assigned to ASHWIN-USHAS CORPORATION. The applicant listed for this patent is ASHWIN-USHAS CORPORATION. Invention is credited to Prasanna Chandrasekhar.
Application Number | 20130039812 13/650607 |
Document ID | / |
Family ID | 42646317 |
Filed Date | 2013-02-14 |
United States Patent
Application |
20130039812 |
Kind Code |
A1 |
Chandrasekhar; Prasanna |
February 14, 2013 |
MICROWAVE REMEDIATION OF MEDICAL WASTES
Abstract
Methods, devices, and remediation compositions for the microwave
remediation of medical wastes are provided. The remediation
compositions include a microwave active fluid including a microwave
active liquid, a microwave enhancer, and a viscosity modifying
agent. Methods include immersing medical waste in the remediation
composition and then irradiating the medical waste and the
remediation composition to remediate the medical waste. The devices
include a container for the medical waste and the remediation
composition, a microwave radiation source and a temperature
monitoring device.
Inventors: |
Chandrasekhar; Prasanna;
(Holmdel, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ASHWIN-USHAS CORPORATION; |
Marlboro |
NJ |
US |
|
|
Assignee: |
ASHWIN-USHAS CORPORATION
Marlboro
NJ
|
Family ID: |
42646317 |
Appl. No.: |
13/650607 |
Filed: |
October 12, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12483398 |
Jun 12, 2009 |
8318086 |
|
|
13650607 |
|
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Current U.S.
Class: |
422/106 ;
422/105; 422/119; 422/186 |
Current CPC
Class: |
A61L 2/12 20130101; A61L
11/00 20130101 |
Class at
Publication: |
422/106 ;
422/119; 422/105; 422/186 |
International
Class: |
A61L 2/18 20060101
A61L002/18; B01J 19/12 20060101 B01J019/12 |
Goverment Interests
REFERENCE TO GOVERNMENT GRANT
[0002] This invention was supported in part by funds obtained from
the U.S. Government (United States Army, Chemical and Biological
Defense Division, contract number M67854-02-C-1106). The U.S.
Government may have certain rights in the invention.
Claims
1. A device for medical waste remediation utilizing microwave
radiation, the device comprising: (a) a remediation chamber
configured to contain medical waste and a remediation composition;
(b) a magnetron for delivering microwave radiation to at least the
remediation chamber; (c) a medical waste comminuter configured to
comminute the medical waste; and (d) a reservoir configured to
contain a remediation composition, wherein the reservoir is in
fluid communication with the remediation chamber.
2. The device of claim 1, comprising a housing, wherein the housing
includes the remediation chamber.
3. The device of claim 2, wherein the housing comprises a waveguide
to direct the microwave radiation from the magnetron into the
remediation chamber.
4. The device of claim 1, wherein the remediation chamber comprises
an aperture.
5. The device of claim 4, comprising a remediation chamber closure
operably connected to the aperture of the remediation chamber.
6. The device of claim 1, comprising a first waste receptacle sized
to fit within the remediation chamber.
7. The device of claim 6, wherein the remediation chamber comprises
a retainer configured to retain the first waste receptacle in the
remediation chamber.
8. The device of claim 6, wherein the first waste receptacle
comprises a plurality of openings.
9. The device of claim 6, comprising a temperature probe in
communication with the first waste receptacle.
10. The device of claim 6, comprising a liquid sensor configured to
determine the liquid content of medical waste in the first waste
receptacle.
11. The device of claim 6, comprising a second waste receptacle
adjacent to the first waste receptacle, the first and second waste
receptacles being oriented to allow transfer of medical waste from
the first waste receptacle to the second waste receptacle through
an adjustable opening in the remediation chamber.
12. The device of claim 6, comprising a filter configured to filter
a remediation composition.
13. The device of claim 1, comprising a filter configured to filter
a remediation composition.
14. The device of claim 1, comprising a pump in fluid communication
with the reservoir and the remediation chamber, the pump adapted to
transfer a remediation composition from the reservoir to the
remediation chamber.
15. The device of claim 1, wherein the medical waste comminuter
comprises a cutter assembly configured to cut the medical waste, a
grinder configured to grind the medical waste or a combination
thereof.
16. The device of claim 15, comprising a first motor configured to
drive the cutter assembly.
17. The device of claim 16, comprising a controller configured to
control the device, the controller being in communication with the
first motor, the cutter assembly, the magnetron and the pump.
18. The device of claim 17, comprising a temperature probe in
communication with a first waste receptacle and the controller.
19. The device of claim 17, comprising a liquid sensor for
determining the liquid content of the medical waste in a first
waste receptacle, the liquid sensor being in communication with the
controller.
20. The device of claim 16, comprising a first waste receptacle and
a first waste receptacle rotator, wherein the first motor is in
communication with the first waste receptacle rotator.
21. The device of claim 20, comprising a second motor configured to
drive the cutter assembly.
22. The device of claim 15, wherein the cutter assembly comprises a
piston.
23. The device of claim 15, comprising a remediation chamber
closure, wherein the cutter assembly extends through the
remediation chamber closure.
24. The device of claim 1, wherein the remediation chamber
comprises an adjustable opening for egress of remediated medical
waste.
25. The device of claim 1, comprising a first chamber comprising a
medical waste introducer configured to introduce medical waste, at
least one grinder configured to grind the medical waste, and
wherein the remediation chamber is in fluid communication with the
first chamber.
26. The device of claim 25, comprising at least one grinder motor
configured to drive the at least one grinder.
27. The device of claim 25, wherein the first chamber and the
remediation chamber are separated by a fluid-permeable layer.
28. The device of claim 27, wherein the fluid-permeable layer
comprises a valve.
29. The device of claim 25, wherein the first chamber comprises a
piston configured to direct the medical waste to the at least one
grinder.
30. The device of claim 25, wherein the first chamber comprises an
angled sub floor configured to direct the medical waste to the
remediation chamber.
31. The device of claim 25, wherein the remediation chamber
comprises a medical waste rotator configured to rotate the medical
waste.
32. The device of claim 25, wherein the remediation chamber
comprises a waste receptacle.
33. The device of claim 32, wherein the waste receptacle comprises
walls with a plurality of openings.
34. The device of claim 25, comprising a finish chamber configured
to receive remediated medical waste from the remediation
chamber.
35. The device of claim 34, wherein the finish chamber is operably
connected to the remediation chamber through a valve of the
remediation chamber such that the remediated medical waste is
received into the finish chamber through the valve of the
remediation chamber.
36. The device of claim 34, wherein the finish chamber comprises a
waste container for receiving remediated medical waste.
37. The device of claim 34, wherein the finish chamber comprises an
opening for removing remediated medical waste.
38. The device of claim 25, wherein the medical waste introducer
comprises an opening in the first chamber.
39. The device of claim 25, wherein the first chamber comprises two
grinders configured to grind the medical waste
40. The device of claim 1, wherein the remediation chamber
comprises a drain configured to drain a remediation
composition.
41. The device of claim 1, comprising a remediation
composition.
42. The device of claim 41, wherein the remediation composition
comprises a microwave active fluid.
43. The device of claim 1, comprising a first chamber comprising a
medical waste introducer configured to introduce medical waste, a
rotatable cutter assembly configured to cut the medical waste, a
medical waste director configured to direct the medical waste to
said rotatable cutter assembly, and wherein the remediation chamber
is in fluid communication with the first chamber.
44. The device of claim 43, wherein the first chamber comprises a
floor configured to direct the medical waste to the remediation
chamber.
45. The device of claim 43, comprising a second chamber and a fluid
permeable layer, wherein the fluid permeable layer separates the
first chamber from the second chamber.
46. The device of claim 43, comprising at least one rotatable
cutter motor configured to drive the rotatable cutter assembly.
47. The device of claim 43, wherein the remediation chamber
comprises a drain configured to drain a remediation
composition.
48. The device of claim 43, wherein the remediation chamber
comprises a cooling supply configured to cool a remediation
composition in the remediation chamber.
49. The device of claim 48, comprising at least one cooling supply
motor configured to drive the cooling supply.
50. The device of claim 43, wherein the first chamber comprises two
rotatable cutter assemblies.
51. The device of claim 43, wherein the remediation chamber
comprises a waste receptacle.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 12/483,398, filed Jun. 12, 2009, the entirety of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0003] This invention relates to a method, an apparatus and
chemical compositions for the microwave remediation of medical
wastes.
BACKGROUND OF THE INVENTION
[0004] Medical wastes, e.g., infectious hospital medical wastes,
represent a major component of hazardous wastes generated in the
U.S. annually. In 2000, the U.S. generated more than 4.5 million
tons of medical wastes. The method used most widely for their
disposal continues to be incineration. Incineration suffers from
problems of high handling, packaging and transportation costs,
residual environmental pollution, high overall cost and severe
local opposition. Those problems have been exacerbated by the
provisions of the Clean Air Act of 1990. Alternatives to
incineration, such as on-site autoclaving and shred-and-steam (with
the steam generated by microwaves) suffer from similar
drawbacks.
[0005] In current practice, medical wastes in hospitals,
physicians' offices, medical labs, or other medical settings are
currently segregated at the point of generation as "bio-medical
waste", "bio-hazard (sharps)" and regular non-infective trash.
Those medical wastes are then collected and transported to a
centralized facility. From there, part of the medical wastes,
typically about 35%, are treated by microwave-steam methods in very
large, plant-like facilities set up in large, dedicated rooms or in
multiple, mobile tractor-trailers (e.g. those offered by Stericycle
Inc (Lake Forest, Ill.) or Sanitec Inc (Sun Valley, Calif.)). The
remaining medical waste is transported off-site, frequently to
another state or province, for incineration in very large
incineration facilities. The entire centralized collection
methodology entails a large overhead with, e.g., specialized
training required for the medical waste transporters.
[0006] What current technology lacks is a relatively
small-footprint, local-area, relatively portable, relatively
inexpensive, point-of-service system for remediation of the medical
wastes at or close to where they are generated. Current technology
also lacks the ability to treat medical wastes on site in a
cost-effective and facile manner.
[0007] Microwave chemistry and biology utilize microwave radiation,
frequently from domestic (2.45 GHz) microwave ovens, to take the
place of heat reflux or catalysts in carrying out organic and
inorganic reactions. Reactions that may take days under thermal
reflux at high temperatures can be completed in under an hour and
sometimes in minutes under microwave radiation.
[0008] Among the requirements for a microwave version of a
conventional chemical reaction is a microwave-active solvent or
reactant, or both. The requirement for microwave activity is the
presence of a dipole. Thus, for instance, a Cl-benzene, which has a
dipole and is thus microwave active, may be substituted as a
solvent for benzene, which is microwave-inactive. A key feature of
microwave reactions is complete penetration and activation of the
entire reaction mass from the inside of the mass. Large reaction
masses are completely penetrated with microwave energy instantly,
rather than being heated "from the outside", as in conventional
heating, with the heat slowly penetrating to the interior. There is
no "penetration depth" or "gradient". Even the strongest
microwave-absorbers absorb only about 15% of the total microwave
radiation, the rest passing through them. Scattering from small
metal components, if present, is reabsorbed by surrounding
components. Due to this feature, microwave reactions do not require
stirring or mixing.
[0009] It is important to recognize that microwave chemistry is not
just an alternative method of heating, although rapid and
penetrating heating is one of the important effects of
microwaves.
[0010] Microwave radiation causes rapid rotational and
rotational/vibrational activation and relaxation at the microwave
frequency, e.g. 2.45 GHz or 2.45 billion times a second. This
causes microwave-induced bond cleavage and rapid bringing together
of activated reaction complexes. Thus, heating is just one of
several effects of microwaves.
[0011] This "not just heating" effect of microwaves has been
documented in innumerable literature studies of chemical reactions.
For example, there are innumerable cases of, e.g., a particular
chemical reaction requiring reflux at a specific temperature for,
say, 36 hours, whilst a corresponding microwave reaction, verified
with fiber optic sensors to occur at the very same temperature, is
complete in, say, 1 hour. If the microwave effect were a pure
heating effect, then the microwave reaction would also require
about 36 hours, not 1 hour. Examples of reactions for which such a
direct microwave-vs.-heat comparison is available are listed in
detail by Lidstrom et al. for more than 300 specific types of
microwave reactions with specific references cited. Lidstrom, P.;
Tierney, J.; Wathey, B.; Westman, J., "Microwave Assisted Organic
Synthesis--A Review", Tetrahedron, 57, 9225-9283 (2001) and
references therein; Majetich, G., Hicks, R., "The use of microwave
heating to promote organic reactions", J. Microwave Power &
Electromagnetic Energy, 30, 27-45 (1995); Whittaker, A. G., Mingos,
D. M. P., "The application of microwave heating to chemical
syntheses", J. Microwave Power & Electromagnetic Energy, 29,
195-219 (1994); Dauerman, L.; Windgasse, G.; Zhu, N.; He, Y.,
"Microwave treatment of hazardous wastes: physical chemical
mechanisms", Mat. Res. Soc. Symp. Proc., 269, 465-469 (1992);
Wicks, G. G.; Clark, D. E.; Schulz, R. L.; Folz, D. C., "Microwave
Technology for waste management applications, including disposition
of electronic circuitry", Microwaves III, Proc. Am. Ceramic Soc. 79
(1992); and Oda, S. J., "Dielectric processing of hazardous
materials--present and future opportunities", Mat. Res. Soc. Symp.
Proc., 269, 453-464 (1992). Some examples of these include:
N-alkylation (including urea and hydrazide formation); alkylation
(including C-alkylation, N-alkylation); radical Michael addition;
Knoevenagel, Wittig and other condensations; cycloadditions;
esterification and trans-esterification; reactions with
heterocycles.
[0012] The solvent medium is an important component in microwave
chemistry/biology. The presence of an efficacious microwave-active
solvent can be determinative of success. It is also true to say
that, in spite of extensive theoretical and experimental studies,
many aspects of microwave chemistry/biology are still not
completely understood. For example, it is not completely understood
why certain reactions progress extremely well under microwaves
while others do not. Published studies that document these issues
include the following: Writeups on the work of Prof. Ajay Bose's
group at Stevens Institute of Technology (Hoboken, N.J.) in:
Chemical & Engineering News, May 20, 1996 and Feb. 10, 1997,
and refs. Therein; Bose, A. K.; Banik, B. K.; Lavlinskaia, N.;
Jayaraman, M.; Manhas, M. S., "MORE Chemistry in a Microwave",
Chemtech, 27, 18-24 (1997), references cited therein; Bose, A. K.;
Manhas, M. S.; Ganguly, S, N.; Sharma, A. N. and Banik, B. K. MORE
Chemistry for less pollution: Applications for process development.
Synthesis 2002, 11 1578-1591. Bose, A. K.; Ganguly, S, N.; Manhas,
M. S.; Vidyanathan, S.; Bhattacharjee, A; Sochanchinwung, R. and
Sharma, A. N. Microwave assisted synthesis of an unusual dinitro
phytochemical. Tet. Lett., 2004, 45, 1179-1181; Pramanik, B. N.;
Ing, Y. H.; Bose, A. K.; Zhang, L. K.; Liu, Y. H.; Ganguly, S, N.
and Bartner, P. L. Rapid cyclopeptide analysis by microwave
enhanced Akabori reaction. Tet. Lett., 2003, 45, 2565-2568;
Pramanik, B. N.; Mirza, U. A.; Ing, Y. H.; Liu, Y. H.; Bartner, P.
L.; Weber, P. C. and Bose, A. K. Microwave-enhanced enzyme reaction
for protein mapping by mass spectrometry: A new approach to protein
digestion in minutes. Protein Science, 2002, 11, 2676-2687; Manhas,
M. S.; Banik, B. K.; Mathur, A.; Vincent, J. E.; Bose, A. K.,
"Vinyl .beta.-Lactamsas Efficient Synthons: Eco-Friendly Approaches
via Microwave Assisted Reactions", in "Recent Aspects of
.beta.-Lactam Chemistry", Tetrahedron Symposia in Print, 56,
5587-5601 (2000); Bose, A. K.; Manhas, M. S.; Banik, B. K.;
Barakat, K. J.; Wagle, D. R., "Microwave Assisted Rapid and Simple
Hydrogenation", J. Org. Chem., 64 (16), 5746-5753 (1999); Pramanik,
B. N., Mirza, U. A., Ing, Y. H., Liu, Y. H., Bartner, P. L., Weber,
P. C. and Bose, A. K. "Microwave-enhanced enzyme reaction for
protein mapping by mass spectrometry: A new approach to protein
digestion in minutes". Protein Science, 2002, 11, 2676-2687;
Pramanik, B. N., Ing, Y. H., Bose, A. K., Zhang, L. K., Liu, Y. H.,
Ganguly, S, N. and Bartner, P. L "Rapid cyclopeptide analysis by
microwave enhanced Akabori Reaction." Tet. Lett., 2003, 44,
2565-2568.
[0013] Among theories seeking to explain the unique microwave
chemistry phenomenon is one that posits that extensive rotation
induced by microwaves (again, 2.45 billion times a second for 2.45
GHz microwaves) leads to greater probability of collision of
reactive molecules in the precise rotational conformation required
for chemical reaction to occur successfully.
[0014] Peterson (U.S. Pat. No. 5,759,486) discloses an apparatus
and method for microwave sterilization of medical, surgical,
veterinary and dental instruments at atmospheric pressure. The
apparatus uses a microwave oven, a sterilization chemical, and
water. The method requires a sterilization chemical that has a
boiling point greater than 100.degree. C., and utilizes
poly(ethylene glycol) (PEG). Among the possible sterilizing
chemicals cited are glycerin, propylene glycol, and di(propylene
glycol). Instruments to be sterilized are placed in a tray, covered
with the sterilizing chemical, the tray covered and placed in
microwave oven. The tray and cover can be stainless steel, glass
and microwave-transparent plastics such as polyimides. The
microwave oven is activated for 4 to 5 minutes. The sterilizing
chemical is drained and sterile water then used to wash the
instruments. The method requires the separate production of sterile
water by distillation of the rinsates.
[0015] Cha (U.S. Pat. No. 6,830,662) discloses a process for
microwave destruction of harmful substances such as chemical and
biological warfare ("CW" and "BW") agents as well as certain types
of biological wastes such as animal remains. Acetonitrile is
utilized as an example of a chemical agent that is related to a
class of cyanide containing CW agents. Acetonitrile gas is passed
over a carbonaceous bed containing a silica-based oxidation
catalyst mixed with SiC particles. Upon directing 400 watts of 2.45
GHz microwave power at the bed, "complete destruction" of the
acetonitrile is noted. In a typical, similar application to
pyrolysis of solid medical waste, a two-stage reactor having
carbonaceous beds is employed. In another application,
sterilization of an Escherichia coli culture flowing over a bed of
activated carbon, while subject to the same microwave power, was
achieved rapidly.
[0016] Mednikov (U.S. Pat. No. 6,537,493) discloses an apparatus
for microwave sterilization of wastes. The key feature of this
invention is circular waveguides directing 2.45 GHz microwaves from
opposite directions into a sterilization chamber where they
"collide". The invention uses a pressure-retaining, hermetically
sealable sterilization chamber. Microwaves are used to generate
steam from a liquid reservoir substantially within the chamber.
[0017] Schiffmann et al. (U.S. Pat. No. 5,811,769, U.S. Pat. No.
5,645,748 and U.S. Pat. No. 5,552,112) disclose a sterilization
method and system that uses a container for containing metallic
medical instruments while being subjected to microwave radiation.
An enclosed outer space having a microwave-active layer is used to
generate heat, which raises the temperature of an enclosed inner
space sufficient for sterilization. The invention does not use
water/steam, but rather relies on the maintenance of a temperature
of at least 204.4.degree. C. (400.degree. F.) for a period of time
sufficient for sterilization. Schifmann et al. (U.S. Pat. No.
5,837,977) describe a heating container with a microwave-reflective
dummy load, in which a reflective inner container is contained
within a microwave-transparent outer container, for use in a
sterilization apparatus.
[0018] Other examples of methods and systems for remediation of
medical waste include Tomasiello (U.S. Pat. No. 6,344,638 and U.S.
Pat. No. 6,245,985), Held et al. (U.S. Pat. No. 5,833,922 and U.S.
Pat. No. 5,709,842), Bridges et al. (U.S. Pat. No. 5,641,423 and
U.S. Pat. No. 5,609,820), Held et al. (U.S. Pat. No. 5,607,612),
Goldner et al. (U.S. Pat. No. 5,270,000), Katschnig et al. (U.S.
Pat. Nos. 6,524,539, 5,879,643, 5,403,564, 5,407,641 and
5,246,674), Goldner (German Pat specification 3,505,570),
McCullough et al. (U.S. Pat. No. 6,097,015), Wicks et al. (U.S.
Pat. No. 6,262,405 and U.S. Pat. No. 5,968,400), Kutner et al.
(U.S. Pat. No. 5,413,757 and U.S. Pat. No. 5,019,344), Riley (U.S.
Pat. No. 5,792,421), Graves et al. (U.S. Pat. No. 6,159,422), Eser
et al. (U.S. Pat. No. 5,759,488), Pearson (U.S. Pat. No.
7,028,623), Pappas (U.S. Pat. No. 5,348,235), Drake (U.S. Pat. No.
5,223,231), Varma et al. (U.S. Pat. No. 6,646,241), Uesugi (U.S.
Pat. No. 5,178,828), Shieh et al. (U.S. Pat. No. 5,708,259 and U.S.
Pat. No. 5,429,799), Kawashima et al. (Japanese Pat specification
No. 6098930), Kamata et al. (Japanese Pat specification 7047112),
Fukui et al, (Japanese Pat specification 5095992), Kameda et al.
(Japanese Pat specification 5023657, Japanese Pat specification
5015866, and Japanese Pat specification 5057268), Terayama et al.
(Japanese Pat specification No. 2001-314847), Kawahara et al.
(Japanese Pat specification 2004-358036), Takahashi et al.
(Japanese Pat specification No. 2004-181022), Kunieda et al.
(Japanese Pat specification No. 2006-204374), Nakajima (Japanese
Pat specification No. 3126462), Mori et al. (Japanese Pat
specification No. 3068487), Won Sam (U.S. Pat. No. 5,397,551 and
Canadian Pat No. 2,073,213), Schiller (German Pat specification No.
4,201,491), Marshall et al. (PCT application WO95/14,496), Hunt
(U.S. Pat. No. 5,951,947), Langenegger (British Pat specification
No. 2,320,247), Podzorova et al. (Russian Pat specification No.
2,221,592), Tang et al. (Chinese Pat. specification 2741684Y),
Zhang et al. (Chinese Pat specification 1698984), Sin (Korean Pat
specification 2006-0017907), Novak (U.S. Pat App. Pub. No.
2007/0102279 and British Pat specification No. 2,435,039), Pilema
(German Pat No. 3,913,472).
[0019] However, there is still a need for a simple, inexpensive,
ambient-pressure, environmentally benign, non-toxic, low-power,
point-of-service method and apparatus for remediation of medical
waste at or close to the point of its generation, and its further
rendition into unrecognizable medical wastes suitable for disposal
as ordinary refuse or "Class 10 municipal medical waste". Thus, it
is an object of the invention to provide a simple, inexpensive,
ambient-pressure, environmentally benign, non-toxic, low-power,
point-of-service method and apparatus for remediation of medical
waste at or close to the point of its generation, and its further
rendition into unrecognizable medical wastes suitable for disposal
as ordinary refuse or "Class 10 municipal medical waste".
SUMMARY OF THE INVENTION
[0020] A microwave-active fluid ("MAF") composition for medical
waste remediation is provided. The MAF includes a microwave active
liquid ("MAL") having a boiling point from about 150.degree. C. to
about 300.degree. C., a microwave enhancer, and a viscosity
modifying agent which modifies the viscosity of the microwave
active liquid. The rotational excitation of microwaves causes a
breakdown in the tertiary and quaternary structure of proteins
(including such elements as specific H-bonds). Microwaves thus
cause rapid breakdown and denaturing of proteins, thus killing
individual organisms, be they bacteria or viruses. Furthermore, the
deep and instant penetration of the reaction mass by microwaves
facilitates access to bacteria or viruses that may be lodged in
parts of amorphous wastes that are otherwise inaccessible to
methods such as standard autoclaving or heat sterilization, unless
these are carried out for extended lengths of time. In summary,
microwaves achieve sterilization of wastes with a combination of
the dual effects of heating (i.e., temperature) and the
microwave-induced bond-cleavage (denaturing effect).
[0021] The invention is further directed to a method for preparing
the microwave active liquid composition for medical waste
remediation comprising the steps of:
[0022] (a) mixing a viscosity modifying agent into a microwave
active liquid (MAL) having a boiling point from about 150.degree.
C. to about 300.degree. C. to form a solution, while maintaining
the temperature of the solution at about 100.degree. C. to about
150.degree. C. during mixing to form a solution;
[0023] (b) cooling the solution of (a) to less than about
30.degree. C. to form a gel comprising the microwave active
liquid;
[0024] (c) adding a microwave enhancer to the microwave active
liquid in the gel of (b) under conditions sufficient to form a
sol;
[0025] (d) cooling the sol of (c) to at least 30.degree. C. for a
time sufficient for any unincorporated microwave enhancer to
separate from said sol;
[0026] (e) irradiating the cooled sol of (d) under conditions
sufficient to heat the sol to at least about 150.degree. C.;
[0027] (f) cooling the irradiated sol of (e) to at least about
100.degree. C.;
[0028] (g) optionally repeating steps (e) and (f) at least one
time;
[0029] (h) irradiating the cooled sol of (d) under conditions
sufficient to heat the sol to at least about 150.degree. C.;
[0030] (i) cooling the irradiated sol of (h) to less than about
3.degree. C. to form a gel and
[0031] (j) isolating the gel formed in (i) to yield the microwave
active liquid composition for medical waste remediation.
[0032] Alternatively, the method for preparing a composition for
medical waste remediation, a microwave active fluid, includes
mixing a viscosity modifying agent into a MAL having a boiling
point from about 150.degree. C. to about 300.degree. C. to form a
solution, while maintaining a temperature of about 100.degree. C.
to about 150.degree. C. during mixing. The solution is cooled to
less than about 30.degree. C. where it forms a gel. A microwave
enhancer is mixed into the gel to form a sol. A dispersing agent is
added to the sol and the sol/dispersing agent mixture is milled.
The sol is separated from the dispersing agent to form the medical
waste remediation composition.
[0033] A method for microwave irradiation of medical waste is also
provided. The method includes placing the medical waste in a
microwave-transparent container. A remediation composition is added
to the container in a quantity sufficient to immerse the medical
waste therein. The remediation composition includes a
microwave-active fluid including a microwave active liquid having a
boiling point from about 150.degree. C. to about 300.degree. C., a
microwave enhancer, and a viscosity modifying agent. The container
with the medical waste immersed in the remediation composition is
irradiated for a time sufficient to remediate the medical
waste.
[0034] A system for medical waste remediation is provided. The
system includes a container and a container lid. The system also
includes a waste receptacle for holding medical waste. The waste
receptacle allows the medical waste to be immersed in a remediation
composition, and is sized to fit in the container. The remediation
composition includes a microwave-active fluid including a microwave
active liquid having a boiling point from about 150.degree. C. to
about 300.degree. C., a microwave enhancer, and a viscosity
modifying agent. The system also includes a temperature probe for
measuring the temperature of the remediation composition, and a
microwave oven for irradiating the medical waste and the
remediation composition.
[0035] A device for medical waste remediation utilizing microwave
radiation is provided. The device includes a housing including a
remediation chamber having an aperture, a remediation chamber
closure for placement on the aperture of the remediation chamber; a
rotatable cutter assembly for cutting waste in the remediation
chamber; a motor driving the cutter assembly and a magnetron for
delivering microwave radiation into the remediation chamber. The
device also includes a first waste receptacle, a reservoir for
containing a remediation composition, a pump, and a controller. The
first waste receptacle is sized to fit within the remediation
chamber. The reservoir is in fluid communication with the
remediation chamber. The pump is in fluid communication with the
reservoir and the remediation chamber, and transfers the
remediation composition from the reservoir to the remediation
chamber. The controller controls the device and is in communication
with the motor, the cutter assembly, the magnetron, and the
pump.
[0036] Another device for medical waste remediation utilizing
microwave radiation is provided. The device includes a first
chamber and a remediation chamber. The first chamber includes an
opening for introducing medical waste and at least one grinder for
grinding the medical waste. The remediation chamber is in fluid
communication with the first chamber, and includes a drain for
draining a microwave active fluid for remediating the medical
waste. The device also includes at least one magnetron for
delivering microwave radiation to at least the remediation chamber,
at least one motor for driving the grinder, and a fluid reservoir
for housing the microwave active fluid. The fluid reservoir is in
fluid communication with at least the remediation chamber.
[0037] Yet another device for medical waste remediation utilizing
microwave radiation is provided. This device comprises:
[0038] a housing including a remediation chamber having a bottom
with an adjustable opening; a remediation chamber top assembly, the
assembly comprising a chamber top including an opening therethrough
and a rotatable cutter and piston assembly extending through the
opening; a motor in communication with a means to rotate a first
waste receptacle and in communication with the cutter and piston
assembly; a magnetron;
[0039] a waveguide to direct microwave radiation from the magnetron
into the remediation chamber;
[0040] a first waste receptacle sized to fit within the remediation
chamber, the first waste receptacle having a plurality of openings
therein, the first waste receptacle adapted for at least a portion
of the chamber top; the chamber top adapted for covering the first
waste receptacle;
[0041] a reservoir to contain a remediation composition, the
reservoir in fluid communication with the remediation chamber;
[0042] a pump to transfer the remediation composition between the
reservoir and the first waste receptacle;
[0043] a second waste receptacle, the second waste receptacle
positioned adjacent the first waste receptacle wherein the
adjustable opening is adapted for transfer of medical waste from
the first waste receptacle to the second waste receptacle, and
wherein the second waste receptacle further comprises a grinder and
shredder for reducing the size of the medical waste after microwave
irradiation thereof;
[0044] a controller attached to the housing and in communication
with the motor, the cutter and piston assembly, the magnetron, the
waste receptacles, the pump, and the adjustable opening;
[0045] a temperature probe, the temperature probe being in
communication with the first waste receptacle and the controller;
and
[0046] a liquid sensor for determining the liquid content of the
medical waste in the first waste receptacle, the liquid sensor
being in communication with the controller.
[0047] Another device for medical waste remediation utilizing
microwave radiation comprises:
[0048] a first chamber comprising a means for introducing medical
waste and at least one grinder for grinding the medical waste;
[0049] a remediation chamber in fluid communication with a first
chamber, the remediation chamber optionally comprising a drain for
draining a microwave active fluid for remediating the medical
waste;
[0050] at least one magnetron for delivering microwave radiation to
at least the remediation chamber;
[0051] at least one motor for driving the grinder; and
[0052] a fluid reservoir for housing the microwave active fluid,
the fluid reservoir in fluid communication with at least the
remediation chamber.
[0053] Yet another device for medical waste remediation utilizing
microwave radiation encompassed by the invention comprises a device
for medical waste remediation utilizing microwave radiation, the
device comprising:
[0054] a first chamber comprising a means for introducing medical
waste, at least one rotatable cutter assembly for cutting medical
waste in said first chamber, a means for directing said medical
waste to said rotatable cutter assembly and floor for directing
said medical waste to a remediation chamber;
[0055] a remediation chamber which is in fluid communication with
said first chamber, said remediation chamber comprising a waste
receptacle and a cooling supply for cooling fluid in said
remediation chamber;
[0056] a fluid permeable layer separating the first chamber from
the second chamber;
[0057] a reservoir in fluid communication with the remediation
chamber, said remediation chamber comprising a drain for draining a
microwave active fluid for remediating medical waste;
[0058] at least one motor driving the rotatable cutter
assembly;
[0059] at least one means (e.g., a magnetron) for delivering
microwave radiation to at least the remediation chamber and
[0060] at least one motor driving the cooling supply for cooling
fluid in said remediation chamber.
[0061] A method for medical waste remediation using a device of the
present invention is provided. The method includes loading the
medical waste into a first waste receptacle and then loading the
first waste receptacle into a remediation chamber of a housing. The
housing includes the remediation chamber having an aperture, a
remediation chamber assembly for placement on the remediation
chamber, a motor driving a cutter assembly and a magnetron for
delivering microwave radiation into the remediation chamber. The
medical waste is immersed in a remediation composition in the first
waste receptacle. Microwave radiation from the magnetron is
delivered to irradiate the medical waste for a time sufficient to
remediate the medical waste. The remediation composition is drained
from the first waste receptacle and the remediation chamber and may
be transferred from the first waste receptacle to a second waste
receptacle for disposal. In a particular embodiment, the size of
the medical waste may be reduced anytime after loading the medical
waste into the first waste receptacle and before transferring the
waste from the first waste receptacle to a second waste receptacle.
Alternatively, the irradiated medical waste is transferred to a
second waste receptacle where the size of the irradiated medical
waste is reduced. The size of the medical waste may be reduced by
shredding and grinding and optionally cutting and/or
compacting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0062] For the purpose of illustrating the invention there is shown
in the drawings various forms, which are presently preferred; it
being understood, however, that this invention is not limited to
the precise arrangements and instrumentalities particularly
shown.
[0063] FIG. 1 is a schematic view of an apparatus for microwave
treatment of medical waste.
[0064] FIGS. 2A and 2B are schematic views of another apparatus for
microwave treatment of medical waste.
[0065] FIG. 3 is a rear view of the MAF reservoir of the apparatus
shown in FIG. 2A.
[0066] FIG. 4 is a schematic illustration of the interaction
between the controller and the components of the apparatus of FIG.
2A.
[0067] FIG. 5 illustrates operation of the apparatus of FIG. 2A
after addition of the MAF into the remediation chamber.
[0068] FIG. 6 illustrates transfer of the treated medical waste
into the second waste receptacle of the apparatus of FIG. 2A.
[0069] FIG. 7 illustrates the operation of an adjustable opening of
the apparatus of FIG. 2A.
[0070] FIGS. 8A, B and C are flow charts describing a process for
microwave treatment of medical waste.
[0071] FIG. 9 is a schematic illustration of a second waste
receptacle of the apparatus of FIG. 2A.
[0072] FIG. 10 is a schematic of another apparatus for microwave
treatment of medical waste.
[0073] FIGS. 11A and 11B are schematic views of an apparatus for
microwave treatment of medical waste, the apparatus having multiple
grinders to grind the medical waste prior to remediation.
[0074] FIGS. 12A and 12B are schematic views of apparatus for
microwave treatment of medical waste, the apparatus having a
grinder to grind the medical waste prior to remediation.
[0075] FIG. 13 shows the FTIR spectra of an unfiltered MAF
according to the invention, (i) before microwave irradiation, and
(ii) after 21 microwave irradiation cycles.
[0076] FIG. 14(a) shows a proton spectrum for pure PEG.
[0077] FIG. 14(b) shows a .sup.13C NMR spectrum for pure PEG.
[0078] FIG. 14(c) shows a proton spectrum for an unfiltered MAF
according to the invention, after 21 microwave cycles.
[0079] FIG. 14(d) shows a .sup.13C NMR spectrum for an unfiltered
MAF according to the invention, after 21 microwave cycles. Samples
were diluted with chloroform-d for the .sup.1H NMR and acetone-d6
for the .sup.13C NMR.
[0080] FIG. 15(a) shows the Total Ion Current (TIC) chromatogram
from a representative GC-MS spectrum for an MAF according to the
invention after 21 microwave irradiation cycles, giving elution
times in minutes. This chromatogram was identical to that for pure
poly(ethylene glycol) (PEG). For each of the observed chromatogram
elution peaks, electron ionization (EI) mass spectra were obtained.
These again corresponded to molecules expected from the EI mass
spectra of PEG, and nothing else. A detailed analysis showed that
these mass spectra products were just pyrolysis products of PEG, an
artifact of the GC-MS technique, where the sample is ionized in a
vacuum and then subject to high effective temperatures. The
retention times of the elution peaks in the TIC chromatogram, and
the corresponding compound (molecule), were: (16.25 min,
2,2'-oxybis-ethanol); (20.91 min, triethylene glycol); (24.97 min,
2,2'-[oxybis(2,1-ethanediyloxy)bis-ethanol]); (28.47 min,
18-crown-6-ether); 31.58 min, 18-crown-6-ether); (34.74 min,
18-crown-6-ether); (39.70 min, 18-crown-6-ether); (47.77 min,
18-crown-6-ether).
[0081] FIG. 15(b) shows the mass spectrum for one of the pyrolysis
products, 2,2'-oxybis-ethanol, corresponding to the elution time of
16.25 min in the TIC chromatogram of FIG. 15(a).
[0082] FIG. 16 is a side view of another apparatus for microwave
treatment of medical waste.
DETAILED DESCRIPTION OF THE INVENTION
[0083] While the compositions, methods and devices heretofore are
susceptible to various modifications and alternative forms,
exemplary embodiments will herein be described in detail. It should
be understood, however, that there is no intent to limit the
invention to the particular forms disclosed, but on the contrary,
the intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the invention
as defined by the appended claims.
[0084] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the relevant art. Although any methods and
materials similar or equivalent to those described herein can also
be used, the preferred methods and materials are now described.
[0085] A microwave-active fluid (MAF) composition for remediation
of medical waste is provided. As used herein, "medical waste"
includes, but is not limited to medical, hospital, biological, and
other related wastes. For example, medical waste includes, but is
not limited to, any of the following or combinations thereof:
gloves, cotton swabs, bandages, pads, tapes, tissues and culture
dishes, partly or substantially infected and/or contaminated.
Medical waste also includes metallic "sharps", including needles,
syringes, scalpels, suture tools, other disposable surgical tools,
blades and glass items, again partly or substantially infected
and/or contaminated; cultures/stocks of infectious agents; blood
and blood products; pathological wastes; bodily fluids and related
liquid wastes, whether contaminating items such as cotton bandages
or present alone; and animal waste. Liquid wastes generally make up
less than about 5 wt. % (weight/weight) of medical wastes. However,
medical wastes as used herein are not limited to those percentages.
That is, medical wastes as used herein includes compositions having
less than about 5 wt. % liquid waste, compositions having about 5
wt. % liquid waste, and compositions having greater than about 5
wt. % medical waste. Preferably, metallic sharps make up less than
about 25 wt. % of the medical waste, and more preferably less than
about 20 wt. % of the medical waste.
[0086] Medical waste is immersed in the MAF and both the medical
waste and MAF are exposed to microwave radiation to remediate the
medical waste. As used herein, "remediate" means sterilizing and
chemically breaking down (e.g., breaking down protein structures)
of material such that biological activity of pathogens and other
microbes is inhibited or terminated. As used herein, "microwave
radiation" includes radio-frequency radiation in the range from
about 0.3 to about 300 GHz. Preferably the radio-frequency
radiation is from about 0.4 to about 6 GHz. This preferred range
includes the common microwave frequencies employed in heating,
0.915 GHz for industrial applications and 2.45 GHz for domestic
(e.g. kitchen) applications.
[0087] The medical waste can be placed in a microwave-transparent
container to which a remediation composition can be added in a
quantity sufficient to immerse the medical waste therein. The
remediation composition includes an MAF including a microwave
active liquid ("MAL"), a microwave enhancer, and a viscosity
modifying agent. The MAL, the microwave enhancer, and the viscosity
modifying agent are combined to form the MAF. The medical waste
immersed in the remediation composition may be covered with a
microwave-transparent weight. Alternatively, the
microwave-transparent weight can be placed on the medical waste
before the medical waste is immersed in the remediation
composition. A microwave-transparent lid is place onto the
container and the container with the immersed medical waste is
placed into a device that generates microwaves. The device is
activated to irradiate the immersed medical waste for a time period
sufficient to remediate the medical waste.
[0088] A temperature probe can be inserted into the remediation
composition to monitor the temperature of the remediation
composition before, during and/or after irradiation.
[0089] The irradiation step can be continuous or intermittent.
Preferably, the total irradiation time (including any pauses in the
irradiation cycle) is less than about 240 minutes. More preferably,
the total irradiation time is from 5 minutes to about 60
minutes.
[0090] Without wishing to be bound by any theory, it is believed
that effectiveness of the MAF in remediating the medical waste can
be ascribed, at least in part, to the rotational excitation caused
by microwave radiation, which results in a breakdown in the
tertiary and quaternary structure of proteins (including such
elements as specific H-bonds). Microwave radiation causes rapid
breakdown and denaturing of proteins, thus killing individual
organisms such as bacteria or viruses. The deep and instant
penetration of the reaction mass by microwave radiation also
facilitates access to individual organisms such as bacteria or
viruses that may be lodged in parts of amorphous medical wastes
that are otherwise inaccessible to methods such as standard
autoclaving or heat sterilization, unless these are carried out for
extended lengths of time. As a result, microwave radiation, as
described herein can achieve remediation of medical wastes with a
combination of the dual effects of heating (i.e., temperature) and
the microwave-induced bond-cleavage (denaturing) effect of the
radiation on the medical waste.
[0091] The MALs selected for the MAF of the present invention have
a boiling point from about 150.degree. C. to about 300.degree. C.
Preferably, the boiling point is from about 210.degree. C. to about
285.degree. C. Preferably, the MALs have a high microwave activity.
As used herein with respect to MALs, "high microwave activity"
means exhibiting a temperature rise under microwave irradiation,
for a given volume and irradiation time, of at least about 1.5
times and preferably greater than about 2 times that of water.
Preferably, the MALs are non-toxic and environmentally benign and
do not generate significant toxic, hazardous or gaseous products,
upon microwave irradiation, and resultant heating up to their
boiling point. Preferably, the MALs are water-soluble. Preferably,
the MALs have an ability to retain solid microwave enhancers such
as activated carbon, SiC and Fe.sub.3O.sub.4 as a stable sol or gel
with or without the assistance of a viscosity modifying agent
(e.g., an emulsifying, gelling or sol-stabilizing agent).
[0092] Preferred MALs that satisfy the above criteria include the
family of poly(glycols), such as poly(ethylene glycol) (PEG) and
poly(propylene glycol) (PPG) of all molecular weights. The MAL can
be glycerol and its acid esters, such as glycerol monostearate and
glycerol lactate, and combinations thereof. The MALs can be a
combination of different liquids. For example, the MALs can be a
combination of different poly(glycols).
[0093] Other potential MALs, such as di(ethylene glycol),
di(propylene glycol) and triethanolamine, which all possess
microwave activity, do not fulfill the above requirements. Most
notably those potential MALs lack non-toxicity and high microwave
activity.
[0094] In one embodiment, the MAL is PEG having a molecular weight,
M.sub.n, less than about 420, and preferably from about 200 and
about 420, where it remains a liquid. At M.sub.n above about 420,
PEG generally is a highly viscous liquid and at M.sub.n
significantly above 420, PEG is a waxy solid. Highly viscous and
waxy solid PEGs are generally not preferred in this invention.
[0095] PEG also has relatively low thermal and electrical
conductivity when compared to those properties of water. The low
electrical conductivity aids in eliminating any arcing effect
(i.e., electrical current flowing through normally nonconductive
material such as air) of thin metal films in the immersed medical
wastes. As long as metallic medical wastes remain immersed in PEG,
no arcing is observed during the microwave process. Metallic films,
which may be present in medical waste, include, but are not limited
to, films on metalized plastic, films on compact discs, and the
like. The low thermal conductivity of PEG minimizes heat transfer
to the container or outer vessels while maximizing the "temperature
effect" component of the remediation mechanism (i.e., the
remediation of the medical waste through exposure to high
temperatures).
[0096] PEG and other poly(glycols) are water-rinsable and have
rinsates that are benign and are disposed of readily. The presence
of small amounts, less than about 10 v/v % (volume/volume), of
water or aqueous solutions in the poly(glycols) does not
significantly affect their remediation properties. PEG and other
poly(glycols) are also inexpensive.
[0097] When irradiated with microwave radiation, the MAL can aid in
remediating medical waste immersed therein in two ways. First, when
irradiated, the MAL heats up, thereby exposing the medical waste to
increased temperatures. Second, when irradiated, the MAL exhibits
denaturing properties that allow the irradiated MAL to break down
proteins and chemical bonds in other biological molecules in the
medical waste.
[0098] The MAF also includes one or more microwave enhancers. The
microwave enhancers contribute to the heating of the MAF, thereby
contributing to the heating portion of the dual microwave effect
(heating effect combined with the microwave-induced chemical
bond-cleavage effect) which aides in the remediation of medical
wastes. Microwave enhancers preferably have a high
microwave-activity. As used herein with respect to microwave
enhancers, "high microwave activity" means exhibiting a temperature
rise under microwave irradiation, for a given weight and
irradiation time of at least about 1.5 times and preferably greater
than about 2 times that of water. Preferably, the microwave
enhancers are non-toxic and environmentally benign and do not, upon
microwave irradiation, generate toxic, hazardous or gaseous
products.
[0099] Microwave enhancers include solids having significant
microwave activity due to the presence of strong dipoles. The
microwave enhancers include meso-, micro- or nano-particulate
microwave-active solids. Among these are materials such as SiC,
Fe.sub.3O.sub.4 and activated carbon. In a particular embodiment,
the activated carbon is a decolorizing activated charcoal. The
microwave enhancer may be activated carbon, SiC, Fe.sub.3O.sub.4 or
any combination thereof. Preferably, the microwave enhancer is
activated carbon.
[0100] Activated carbon is believed to derive its polarity from
adsorbed impurities. Activated carbon includes, but is not limited
to, the following commercially available varieties: decolorizing
activated charcoal; activated carbon, granular, mesh 2 to 150 and
(-)100 mesh; carbon nanopowder, amorphous. SiC may include, but is
not limited to, the following commercially available varieties:
(-)400 mesh; 100 to 450 mesh; and nanopowder. Fe.sub.3O.sub.4 may
include, but is not limited to, the following commercially
available varieties: powder, average particle size 5 microns; and
nanopowder, particle size 20 to 30 nm.
[0101] SiC is a refractory material used in microwave
instrumentation such as pyrolyzers and ashing systems, e.g. those
manufactured by Milestone, Inc., Shelton, Conn. and others. As an
illustration of the microwave absorption properties of SiC, 2 g of
SiC (mesh size -400) placed at the midpoint of the platen in a 1.2
KW oven such as a Sears KENMORE.RTM. microwave oven (Model
721.62461, 1.2 KW, 2.45 GHz, 13.5 Amp) irradiated for 10 minutes
achieves a temperature of over 1000.degree. C. Activated carbon and
Fe.sub.3O.sub.4 have somewhat smaller temperature effects, i.e.
achieve somewhat lower temperatures under identical conditions. It
should be appreciated that the temperature achieved by irradiating
the microwave enhancer is simply a measure of the microwave
activity of the material. Besides their microwave activity, SiC,
Fe.sub.3O.sub.4 and activated carbon also possess other
advantageous properties, such as non-toxicity, environmental
benignness and fair chemical inertness.
[0102] The microwave enhancer can be from about 0.25 wt. % to about
5 wt. % of the MAF. Preferably, the microwave enhancer is from
about 0.5 wt. % to about 2 wt. % of the MAF.
[0103] The MAF also includes one or more viscosity modifying
agents. The viscosity modifying agents assist in incorporating the
microwave enhancers into the MAL such that a milk-like sol results.
Viscosity modifying agents are soluble in the selected MAL.
Preferably, the viscosity modifying agents have a sol-forming
ability in the MALs. Preferably, the viscosity modifying agents
have an ability to act as gelling agent and/or emulsifier for the
microwave enhancers.
[0104] Viscosity modifying agents include, for example, gelling
agents, emulsifiers and stabilizers of the MAL. In one embodiment,
the viscosity modifying agent is poly(ethylene oxide) (PEO), of
average molecular weight, M.sub.v, 100,000 to 8,000,000. Other
potential gelling agents, such as, by way of example, poly(vinyl
alcohol) (PVA), do not fulfill the requirement of solubility and
gelling capability.
[0105] In one embodiment, the viscosity modifying agent includes
PEO of M.sub.v, 100,000 to 500,000. In another embodiment the
viscosity modifying agent includes PEO of M.sub.v, 200,000, at a
concentration of about 1 wt. % in the MAF.
[0106] The viscosity modifying agent can be from about 0.01 wt. %
to about 5 wt. % of the MAF. Preferably, the viscosity modifying
agent is from about 0.1 wt. % to about 1 wt. % of the MAF.
[0107] In a particular embodiment, the viscosity modifying agent is
soluble in microwave active liquid. An example is PEO. In one
embodiment, where PEO is the viscosity modifying agent and PEG is
the MAL, the PEO, at concentrations from 0.01 wt. % to 5 wt. %,
acts as a sol-stabilizing agent to a stable sol in the PEG. PEO is
transparent to microwaves, i.e. microwave-inactive. PEO also aids
in the rendering into sols in PEG of microwave enhancers such as
SiC, activated carbon and Fe.sub.3O.sub.4, materials that would
normally simply precipitate out of the PEG. Sols of activated
carbon (1% w/w) and PEO (1% w/w) in PEG can maintain their
stability and milk-like homogeneity over extended periods, for
example, up to about eight months.
[0108] Preferred components of the MAF, such as PEG, PEO, SiC,
activated carbon and Fe.sub.3O.sub.4, are generally environmentally
benign, non-toxic and chemical inert. PEG is listed in the Merck
Index as a food additive. PEG at an M.sub.n of about 285 to about
315 has a boiling point at about 270.degree. C., which precludes
the production of vapors, harmful or otherwise, from both the PEG
itself and any medical wastes immersed in the PEG during the
heating that occurs during microwaving.
[0109] The MAF can be prepared by first dissolving a viscosity
modifying agent such as PEO into a MAL such as PEG to form a
solution, while mixing the solution and maintaining the temperature
of the solution at about 100.degree. C. to about 15.degree. C. The
solution can be cooled to less than about 50.degree. C., preferably
less than about 30.degree. C., and most preferably from about
15.degree. C. to about 30.degree. C. to form a gel. A microwave
enhancer can then be mixed into the gel to form a sol.
[0110] Preferably, when the microwave enhancer added the gel, it is
first mixed with the gel for greater than about 10 minutes. More
preferably, the mixing time is greater than about 30 minutes. Most
preferably, the mixing time is greater than about 60 minutes. In
one embodiment, the mixing time is from about 60 minutes to about
90 minutes. In another embodiment, the mixing time is from about 60
minutes to about 120 minutes. The mixing can be continuous or
intermittent. The mixing can be performed by standard mixing
techniques such as stirring with a magnetic stir bar. Mixing is
performed at a temperature ranging from 90.degree. C.-130.degree.
C. and preferably at about 100.degree. C.
[0111] The mixture may then be cooled to less than about 20.degree.
C. to about 40.degree. C. and preferably about 30.degree. C. after
mixing for a time sufficient to separate any unreacted microwave
enhancer from the sol, for example, from about three hours to about
16 hours. The cooled sol is then irradiated (e.g., microwave) under
conditions sufficient to heat the sol to at least about 150.degree.
C. and preferably between about 150.degree. C.-250.degree. C. The
irradiated sol is cooled to at least about 100.degree. C. and
preferably between about 50.degree. C. to about 100.degree. C. The
irradiation and cooling steps may be repeated at least once and may
be repeated up to 20 times. The cooled sol is then irradiated under
conditions sufficient to heat the sol to at least 150.degree. C.
and preferably between about 150.degree. C.-250.degree. C. The
irradiated sol is cooled to less than about 30.degree. C. to form a
gel. The gel formed is isolated, by, for example, decantation to
separate from unreacted solid microwave enhancer. This solid
microwave enhancer is removed and microwave active liquid
composition for medical waste remediation is obtained.
[0112] A dispersing agent may be optionally added to the sol to act
as a milling agent. The sol/dispersing agent mixture can be milled
and then the sol separated from the dispersing agent to yield a
composition for medical waste remediation, i.e., the MAF. The
dispersing agent, if employed, preferably is added to the sol at a
concentration from about 30 v/v % to about 70 v/v % of the sol.
More preferably, the dispersing agent is added to the sol to a
concentration from about 40 v/v % to about 60 v/v %. Most
preferably, the dispersing agent is added to a concentration of
about 50 v/v %.
[0113] The sol containing the dispersing agents can be milled in a
standard jar, or ball mill, for example. The milling time is
preferably at least about 5 minutes, more preferably at least about
10 minutes, and most preferably at least about 30 minutes.
Preferably, the milling time is less than about 120 minutes. More
preferably, the milling time is less than about 60 minutes. Most
preferably, the milling time is from about 30 minutes to about 60
minutes. The milling can be continuous or intermittent. The milling
can be performed by standard milling techniques.
[0114] In one embodiment, the sol containing the dispersing agents
is milled from about 10 minutes to about 60 minutes. The resultant
sol is decanted to separate the sol from the dispersing agents. The
dispersing agents can be washed with water for reuse. The decanting
produces a gel or sol of the microwave enhancer in the solution of
the viscosity modifying agent (i.e., sol-stabilizer) in the MAL,
i.e. it yields the MAF.
[0115] In one embodiment of preparing the MAF, about 0.01 to about
5 wt. % of PEO is dissolved with stirring at about 100.degree. C.
to about 150.degree. C., in PEG of M.sub.n about 200 to about 415
for about 1 hour. In another embodiment, about 1 wt. % PEO of
M.sub.v about 200,000 can be dissolved with stirring at 100.degree.
C. to 150.degree. C., in PEG of M.sub.n about 200 to about 415 for
about 1 hour.
[0116] Preferably, the PEG/PEO solution is allowed to cool to less
than about 50.degree. C., more preferably to less than about
30.degree. C., and most preferably to room temperature (i.e., about
25.degree. C.) to form a gel. The solution can be stirred during
cooling and then allowed to stand after the cooling is complete.
The solution can be capped or covered. If allowed to stand, the gel
is preferably mixed before the microwave enhancer is added to the
gel to form a sol. Preferably, the microwave enhancer is added at a
concentration of about 0.01 to about 5.0 wt. %, more preferably at
a concentration of about 0.1 to about 1.0 wt. %, and most
preferably at a concentration of about 0.5 wt. % of the sol.
[0117] In one embodiment of the present invention, the dispersing
agent added to the sol comprises spherical or partially spherical
solid or hollow objects. The objects can be one or more of glass
beads or balls, ceramic beads or balls, metal beads or balls, or
stainless steel beads or balls, for example. Preferably, the
objects have a diameter from about 0.1 mm to about 20 mm, more
preferably from about 0.1 mm to about 10 mm, and most preferably
from about 2 mm to about 4 mm. Preferably, the objects are added to
the sol at an amount from about 30 to about 70 v/v % of the sol,
more preferably about 40 to about 60 v/v %, and most preferably
about 50 v/v %.
[0118] The MAF is effective in remediating bacteria-infected
medical wastes and medical wastes infected with other biological
molecules. It is believed that the MAF is also effective in
remediating virus-infected medical waste.
[0119] What follows is a discussion of a device and method with
reference to the drawings, where like numerals identify like
elements. There is shown in FIG. 1 an embodiment of a system for
microwave remediation of medical waste. The system is considered to
be a "manual" or "laboratory test" system; and generally used for
testing the efficacy of various MAF formulations, but the
embodiment is not limited to that use. The system includes a vessel
2 containing medical waste 4, and an MAF composition 10.
[0120] Preferably, the vessel 2 is made of microwave-transparent
material. As used herein, "microwave-transparent materials" are
"low-loss materials" in microwave parlance. They are characterized
by low value of microwave extinction parameter ".di-elect cons.".
Microwave-transparent materials include materials that are
microwave transparent and materials that are substantially
microwave transparent. Examples of microwave-transparent materials
include borosilicate glass, PTFE ((polytetrafluoroethylene, sold
under the trademark TEFLON.RTM., DuPont Corporation, Wilmington
Del.), poly(imide) (PI) or poly(ether imide) (PEI). In addition to
the microwave transparency of PTFE, PI and PEI, those materials
also have an ability to withstand high temperatures. PTFE, PI and
PEI withstand maximum MAF temperatures of 240 to 300.degree. C.,
which may be achieved practicing the medical waste remediation
methods described herein. PTFE, PI and PEI and are substantially
chemically inert to substances generally found in medical
wastes.
[0121] The medical waste 4 may be retained by a weight 3 to insure
that the medical waste 4 is immersed in the MAF composition 10. As
shown in FIG. 1, the MAF composition 10 is added so that the fluid
level is above the level of the weight 3. The weight 3 can be made
of PTFE or other microwave-transparent materials. The weight can be
of a thickness and density that allows the weight 3 to weigh down
the medical waste 4 within the MAF composition 10, while allowing
for circulation of the MAF composition 10 within the vessel 2. The
weight 3 can include perforations or holes 3a to allow flow of the
MAF composition 10 within the vessel 2, and which can ease the
submersion of the weight 3 in the MAF composition 10.
[0122] The vessel 2 is covered with a lid 1, preferably made of the
same material as the vessel 2. The lid 1 can be, for example, about
1 to about 2 cm thick. The lid 1 can be loose-fitting or provide a
tight seal with the vessel 2. The lid 1 may take the form of a
plate or an inverted dish.
[0123] A temperature probe 5, which may be fiber optic temperature
sensor, can be inserted within the vessel 2 to monitor the internal
temperature of the MAF composition 10 during the microwave
treatment of the medical waste 4. In a particular embodiment, the
amount of irradiation in the microwave chamber is based on the
temperature reading from the temperature probe.
[0124] The microwave oven 12 can, for example, be a domestic
("kitchen") microwave oven, such as a Sears KENMORE.RTM. microwave
oven (Model 721.62461, 1.2 KW, 2.45 GHz, 13.5 Amp). With this
microwave oven 12, the loaded vessel 2 can be placed in the
microwave oven 12 and irradiated for about 10 to about 30 minutes
to remediate the medical waste 4. If a different size microwave
oven is used (e.g., 500 W to 5 KW), the irradiated times necessary
to remediate the medical waste 4 would be adjusted accordingly.
[0125] As shown in FIG. 1, the vessel 2 includes an opening 7 on a
side. The opening 7 is of a size sufficient to accommodate a cable
6 from the temperature probe 5. The temperature probe 5 is placed
in the center of the immersed medical waste 4, with its cable 6
transiting the vessel through the opening 7 described above. The
cable 6 can be an optical fiber cable for probe 5 where probe 5 is
a fluoro-optic temperature sensor. The cable 6 of the temperature
probe 5 can be made of a material having a size that is sufficient
and durable to exit the microwave oven through its closed door,
without impeding the functioning of the probe 5 or the microwave
oven 12. In one embodiment, the opening has a diameter of no
greater than 2 mm, and the temperature probe 5 is a LUXTRON.RTM.
model One sensor (registered trademark of Luxtron, Inc., Santa
Clara, Calif.), used to measure temperature within the MAF
composition 10.
[0126] For a typical collection of medical wastes, the proportion
of MAF composition 10 to medical wastes 4 can be, for example,
about 1.5:1 (vol/weight), which generally is sufficient to immerse
all types of medical wastes in the MAF composition 10. For example,
for 100 g of medical waste 4, 150 mL of the MAF composition 10 can
be employed, and for 400 g of medical waste 4, about 600 mL of MAF
composition 10. The parameter that determines the actual volume of
the MAF composition 10 used is that the medical waste 4 should be
completely immersed in the MAF. If necessary, the medical waste can
be compressed by the administration of a weight 3 on top of the
medical waste 4 and/or by applying mechanical pressure to the
medical waste 4. Preferably, the medical waste 4 is compressed
before being immersed in the MAF composition 10, but it can be
compressed after immersion.
[0127] The microwave remediation is carried out for a time
sufficient to remediate the medical waste 4. Preferably, the total
irradiation time is from about 5 minutes to about 60 minutes. The
precise irradiation time will be dependent on factors such as size
and power of microwave oven 12, amount of medical waste 4, and
other similar factors. The exact time can be determined by feedback
from the temperature probe 5. The feedback can be monitored
manually and manual adjustments to the irradiation cycle can be
made. Alternatively, the feedback can be automated with a
controller 14. The controller 14 can receive temperature inputs
from the temperature probe 5 and adjust the irradiation cycle
accordingly. For example, the controller can be programmed to shut
off the microwave oven once a predetermined temperature is reached.
After a period of cooling, the controller can then restart the
microwave oven after a predetermined time or when a predetermined
"cooled" temperature is reached or the controller can signal that
remediation is complete.
[0128] It is contemplated that a minimum residence time of about 5
minutes at about 200.degree. C. is a threshold to ensure
remediation. It is further contemplated that this residence time
and temperature applies to a large variety of medical waste types,
varied infectious organisms (both bacteria and viruses), varied
medical waste/MAF ratios, and varied microwave irradiation times.
In keeping with the above residence time, the microwave irradiation
may be turned off for short periods of time, for example, about 120
seconds or less, during the total irradiation cycle, either
manually or automatically, depending on the feedback from the
temperature probe. Preferably, the temperature is maintained at
least about 40.degree. C. below the boiling point or the
decomposition temperature of the MAF. For example, when PEG is used
as the MAL, a maximum temperature of 240.degree. C. may be set in
the feedback loop that controls the microwave oven based on the
temperature information. When this temperature is reached, the
microwave irradiation can be shut off for, for example, about 30 to
about 90 seconds, then turned on again for, for example, about a
60-second period. The cycle can be repeated as needed. This process
can be done manually or automatically by programming the controller
14 to interact with the temperature probe 5 and the microwave oven
12.
[0129] In a particular embodiment, a typical 400 g sample of
medical waste 4 immersed in 600 mL of MAF composition 10 and placed
in the microwave oven 12. The microwave oven is run for about 15
minutes, at which time the microwave oven is temporarily shut off.
Through 30 minutes, the number of such shutoffs does not exceed
two, each not exceeding about 60 seconds. A typical final
temperature for the MAF is in the range of about 230.degree. C. to
about 235.degree. C. After the final temperature is reached, the
microwave oven is shut off and the vessel is removed from the
microwave oven. The MAF is then allowed to cool to near ambient
(room) temperature. The cooling period in ambient air is
approximately twice the microwave irradiation time.
[0130] The MAF advantageously has the consistency of a very thin
gel at ambient temperature and a milk-like sol at the higher
temperatures reached in the microwave process; it remains so
throughout the procedure. As a result of this temperature control,
negligible vapors will be produced during the remediation, and any
such vapors are contained within the vessel and its lid. These
vapors are seen to be absent on cooling of the vessel, indicating
either condensation or dissolution into the MAF. Little (about 1%)
to none of the microwave enhancers of the MAF is lost onto the
medical waste substrates, due to the sol-like nature of the
MAF.
[0131] After cooling, the medical waste 4 may be press-strained to
remove the MAF composition 10 from the medical waste 4. The MAF
composition 10 can be press-strained directly into the microwave
vessel 2 or into another container. The press-straining can be done
by hand, by pressing down on the weight 3 to effect the straining,
or by other known means. Generally, less than about 10% of the
volume of the MAF composition 10 is retained in the medical waste
4. The more rigorous the press-straining, the less the volume of
MAF composition 10 that is lost in the medical waste 4. It is
contemplated that the volume of the MAF composition 10 in the
medical waste can be reduced to below about 2.5%. The recovered MAF
composition 10 can be re-used multiple times. It is contemplated
that the MAF composition 10 can be reused as many as 20 or more
times.
[0132] Detailed chemical and other analyses of the MAF following
multiple (greater than about 20) uses of MAF according to the
invention have shown no hazardous or toxic products; the data are
given in Example 8 below. After approximately 20 uses, the MAF's
volume generally is sufficiently reduced such that the lost volume
must be made up with the addition of fresh MAF. The MAF can be
discarded in ordinary sewerage by non-commercial entities, with
negligible financial and environmental implications. For example,
when PEG, a food additive, is used as the MAL, it has been
determined that the MAF can generally be discarded in household
sewerage without any pre-treatment.
[0133] Another embodiment of a system of the invention is shown in
FIGS. 2-9. FIG. 8 is a block diagram of the microwave remediation
procedure using this embodiment. The remediation instrument
represented in these figures is referred to generally as remediator
100.
[0134] For treatment in the system of FIGS. 2-9, medical waste 4 is
collected in one of several ways. In one collection method, medical
waste 4 such as medical waste is collected in a "red bag", e.g. 182
in FIG. 2B. A "red bag" is a bag used for collection of
biohazardous medical waste. Such bags are available commercially
from suppliers such as ScienceWare/Bel-Art or other commercial
vendors. One or more of the bags can be held within a larger,
preferably perforated, microwave-transparent (PTFE such as DuPont
TEFLON.RTM.) waste receptacle 102 shown in FIG. 2B. When full or
when it is desired to treat or empty the medical waste 4, the
entire waste receptacle 102 is transported to the remediator 100,
where it can interlock into a main remediation chamber 120 (the bag
can be tied or sealed first, depending on the type being used). The
advantage of this approach is that multiple waste receptacles 102,
i.e., waste receptacles deployed at multiple points of medical
waste collection, can feed into a single remediator 100. The cost
of the waste receptacles 102 is small in relation to the cost of
the remediator 100, and this mode of use also facilitates maximum
use of the remediator 100.
[0135] In another collection method, medical waste 4 is collected
in a standard, commercially available "sharps/bio-hazard" container
which may be made of propylene. The sharps container can be kept in
the same manner within the larger waste receptacle, and interlocked
with the remediator 100 when full. The waste receptacle 102 can be
made of any of the same materials as described for vessel 2. PTFE
is the preferred material for the waste receptacle 102 due to its
microwave transparency. In addition, PTFE is chemically inert and
has thermal durability (to over 280.degree. C.). The waste
receptacle 102 comprises a wall 104 and a base 106. The base 106
includes one or more adjustable openings 108. As shown in FIG. 7,
the adjustable opening 108 may include an iris diaphragm 110,
having a plurality of blades 110. Alternatively, the adjustable
opening 108 may include a gate valve, a "flower-petal" valve, a
hinged door, or another similar arrangement. The adjustable opening
can be controlled manually such as with a hand crank or wheel. The
adjustable opening can be controlled automatically, for example,
being programmed such that its operation is under the control of
controller 114. The adjustable opening can be controlled through a
combination of automatic and manual control, such as automatic
control with a manual override feature. As shown, the wall 104 is
cylindrical, but other shapes can be utilized. As shown in FIG. 2B,
the wall 104 can be perforated with a plurality of holes 112 to
permit MAF ingress and egress. The holes 112 in the waste
receptacle 102 wall 104 can be spaced randomly, asymmetrically or
evenly spaced. As shown in FIG. 2B, the holes 112 are evenly spaced
in the waste receptacle 102. The size of the holes or perforations
depends on the desired microwave frequency. For example, for a
microwave frequency from about 2 to about 3 GHz, the size of the
holes or perforations are preferably greater than about 1 cm, more
preferably greater than about 2 cm, and most preferably greater
than 3 cm.
[0136] The waste receptacle 102 may be of various sizes, with the
determinative factor on size being the waste receptacle's ability
to fit into the remediator 100. The waste receptacle 102 can have a
circular, triangular, or rectangular cross section, and it can have
a cross section of any other symmetrical or asymmetrical shape. A
cylindrical waste receptacle may have, for example, dimensions of
about 12 cm diameter by about 20 cm depth, with a resultant volume
capacity slightly over 2 liters. A cylindrical waste receptacle of
that size can hold approximately 1.4 kg of medical waste.
[0137] The waste receptacle 102 can be interlocked into the main
remediation chamber 120, which may have, for example, dimensions of
about 18 cm diameter by 30 cm depth, with a resultant volume
capacity of about 7.5 liters. In this embodiment, the MAF reservoir
130 holds about 7.5 L of fluid at room temperature, and about 7.4 L
at an MAF temperature of 220.degree. C. Generally, less than half
of the maximum capacity of the MAF reservoir 130 is utilized during
remediation. The overall dimensions of the remediator 100
preferably are approximately those of a tabletop photocopier.
[0138] The dimensions and capacities for the waste receptacle,
remediation chamber and the MAF reservoir are merely illustrative
and in no way limit the scope of the invention. The precise
dimensions and capacities will be determined based on demand, space
requirements, and other similar factors.
[0139] After the waste receptacle 102 has been placed into the
remediation chamber 120, the chamber can be closed by placement
and/or attachment of a chamber assembly 140. In this embodiment,
the chamber assembly 140 includes a chamber closure 142 to close
the top aperture of the remediation chamber 120. The chamber
closure 142 may be a lid, a cover, a door, or other similar devices
to close the aperture of the remediation chamber. The aperture can
be located on top of the remediator 100, on the side of the
remediator 100, or on the bottom of the remediator 100.
[0140] As shown in FIG. 2A, the chamber assembly 140 also includes
motors 144, drivers 146 and 148, a magnetron 150, and an optional
waveguide 152. The chamber assembly also includes a central opening
154 through which pass a pair of shafts 156 and 158. The pair of
shafts 156 and 158 are positioned such that inner shaft 156 is
rotationally positioned inside outer shaft 158. The pair of shafts
156 and 158 is attached to the lid 160 of the waste receptacle 102,
and to a cutter blade 162. The motors 144 and magnetron 150 are in
communication with the controller 114, attached to chamber closure
142. Alternatively, the magnetron 150 and the motors 144 can be
separately positioned.
[0141] When the chamber assembly 140 is attached, lid 160 is
slidably retained within the waste receptacle 102. The lid 160
contains the medical waste 4 and the added MAF composition 10. The
lid 160 can act as a piston to facilitate removal of the remediated
medical waste from the waste receptacle 102. The lid 160 can also
aid in directing the remediated medical waste into a second waste
receptacle 180, which can include a grinder, which includes
shredders and other devices that can reduce the size of the medical
waste. The second waste receptacle may be adjacent to the first
waste receptacle and the first and second waste receptacles may be
oriented to allow transfer of the medical waste from the first
waste receptacle to the second waste receptacle through an
adjustable opening in the remediation chamber. Lid 160 contains an
opening 164, through which passes inner shaft 156. Outer shaft 158
is attached to the outer surface 166 of lid 160, and drives the
rotation of the waste receptacle 102.
[0142] The waveguide 152 directs microwave radiation from the
magnetron 150 into the remediation chamber 120. The remediator 100
can operate without a waveguide 152 if, for example, the magnetron
150 is mounted more centrally.
[0143] A first motor 144 controls the operation of the waste
receptacle 102 and is in communication with a means to rotate the
first waste receptacle, and second motor 144 drives the cutter
assembly and thus controls operation of the cutter blade 162, the
cutter blade 162 being kept beneath the lid 160 when the cutter
blade 162 is not being used for cutting bags of medical waste. The
inner cutter blade shaft 156 is connected to first motor 144 by a
driver 146, which can be a drive belt or other means of directing
power from a motor to a shaft, as known to those skilled in the
art. While the cutter blade 162 is shown as a fan-like blade
extending from the top of the remediator 100, other orientations
are contemplated. For example, the cutter assembly and thus the
blade 162 can extend from the bottom, side, top, through the
remediator chamber closure and any combination thereof. Other
designs are also contemplated. For example, the blade 162 can
comprise vertical blades like kitchen blender blades. Various sizes
are also contemplated, the size generally being dependent on the
size of the remediator 100.
[0144] Second motor 144 is connected to the outer shaft 158 by a
driver 148, which may be a drive belt or other means of directing
power from a motor to a shaft, as known to those skilled in the
art. The drivers 146 and 148 may be different or identical,
depending upon manufacturing decisions. Second motor 144 controls
rotation of the waste receptacle 102.
[0145] As shown in FIG. 2A, the remediation chamber 120 includes at
least one temperature probe 5. Preferably, the remediation chamber
120 includes at least two temperature probes 5. The temperature
probe 5 may, for example, be a LUXTRON.RTM. One sensor described
earlier. Alternatively, the temperature probe 5 may be a
thermocouple with a suitably shielded connector. The temperature
probe 5 can be attached to the inner wall 122 of the remediation
chamber 120. The temperature probe is in communication with the
first waste receptacle and controller.
[0146] FIG. 2A illustrates two magnetrons 150 as sufficient to
provide microwave irradiation of the remediation chamber 120. The
magnetrons 150 can be, for example, Panasonic 2M265 (Matsushita
Electrical, Japan), Hitachi 2M21A magnetron (Hitachi, Ibaraki,
Japan) or MWO 1420B (Sun Rise Ltd., Japan). The total power of both
magnetrons is less than 2.5 KW. Greater and lesser amount of power
is contemplated and may be dependent on factors such as size of the
remediation chamber 120, amount of MAF, amount of medical waste,
orientation of the magnetrons 150 in relation to the remediation
chamber 120, and other similar factors.
[0147] An outer shell 124 and an inside shell 122 of the
remediation chamber 120 preferably are metal. Preferably, the
inside shell 122 is a metal with an MAF resistant coating, or
stainless steel. Appropriate waveguides 152 channel microwaves
generated at the two magnetrons 150 into the remediation chamber
120.
[0148] As will be apparent to those skilled in the art, the
dimensions described herein are for purposes of illustration only,
and larger or smaller remediators 100, and its component parts, may
be constructed without departing from the spirit and scope of this
invention.
[0149] The operation of the remediator 100 is described as follows
and in FIG. 8A.
[0150] After loading of the medical wastes (Step 202) in the
remediator 100, its main cycle is activated at step 204 (FIG. 8A).
This causes the cutter-piston 162 to come down into the bag 182,
cutting it open (if it is sealed) as well as dispersing and
compacting the contents. Step 204 can be completed in from a few
seconds to tens of minutes. Preferably, medical waste 4 is
homogenously distributed in the remediation chamber 120. The
initial cutter-piston cycle aids in puncturing the bags holding the
medical waste 4, and aids in distribution of the medical waste
within the remediation chamber 120. The cutter-piston cycle can
also serve to compact the medical waste 4. Compaction may reduce
the volume of the medical waste 4 to a greater extent than having a
shredder/grinder unit before the microwave cycle. The reduction in
volume before the microwave irradiation cycle is commenced may be
about 50%.
[0151] Preferably, step 204 is completed in from about 1 minute to
about 2 minutes. Step 206 can be initiated after step 204 is
completed. Alternatively, Step 204 and step 206 can be run
concurrently either for the entire time of Step 204 or for only a
portion of time of step 204. In step 204, the MAF composition 10
fills the remediation chamber 120 from the MAF reservoir 130. The
volume of MAF composition 10 added is generally about 3 L for the
embodiment described herein but can be more or less depending on
the size of the remediator 100, and its component parts, and on the
amount of medical waste 4 in the remediation chamber 120. A pump
132, also in communication with controller 114, dispenses the MAF
composition 10 into the remediation chamber 120 through tubing 134.
Once sufficient amounts of the MAF composition 10 are in the
remediation chamber 120, step 208 can be initiated which includes
beginning irradiation. Step 208 can range from about 10 minutes to
about 30 minutes. The irradiation times can be adjusted, preferably
to ensure residence times at 200.degree. C. of at least 5 minutes.
The waste receptacle 102 can be rotated within the remediator 100
during this time period. Preferably, the rotation is at a slow
spin, generally from about 2 to about 20 revolutions per minute
("rpm"). The rotation can be accomplished by having the waste
receptacle 102 on a rotating plate (e.g. a turntable), having a
rotating arm descending from the top assembly attached to the waste
receptacle 102, or by other means known by those skilled in the
art.
[0152] After completion of step 208, there is a cooling period of
step 210. The cooling period preferably is from about three to
about five minutes in duration. During or after step 210, the MAF
composition 10 is drained in step 212. During step 212, the MAF
composition 10 preferably passes through a filter 136, which acts
as a sieve to separate the MAF composition 10 from any
small-particulate remediated medical wastes, including any
partially molten plastics, that may be small enough to be carried
with the MAF composition 10 during the fill/drain cycles.
Typically, the small-particulate remediated medical wastes that may
need to be filtered out of the MAF composition 10 comprises less
than 1% by weight of the total medical wastes. The filter unit 136
may be physically removed and cleaned of accumulated (i.e.,
filtered) debris, preferably every five remediation cycles. The
drain cycle may also serve to further cool the MAF composition 10.
Step 214 is then initiated and may comprise rotating the first
waste receptacle between the draining step and transferring the
waste to remove liquid from the irradiated medical waste. In
particular, Step 214 includes spinning the medical waste 4 after
the MAF composition 10 has been removed, thereby further drying the
medical waste 4. This step can be run for a period of from about 1
to 10 minutes, preferably about 5 minutes. Preferably, the rotation
is a fast spin, which is generally on the order of between 10-20
times the slow speed described above for the waste receptacle 102.
Steps 206, 208, 212, and 214 are like those of a clothes washing
machine, and the waste receptacle 102 has a configuration that
resembles a top-loading washing machine.
[0153] At the end of step 214, the medical waste 4 is nearly dry,
about as dry as clothes from a clothes washer after a comparable
spin cycle. The absorbent components of the medical waste 4, such
as cotton swabs or tissues, retain some of the MAF composition 10.
The amount of MAF composition 10 retained by the medical waste 4 is
generally less than about 2.5% of the original volume of the MAF
composition 10. The small retention of the MAF composition 10 in
the medical waste 4 is aided by using only about half of the volume
capacity of the microwave chamber, which allows for rapid cooling
of the MAF composition 10. The rapid cooling allows for easier
draining of the MAF composition 10 because the MAF composition 10
is less viscous at lower temperatures.
[0154] The final temperature achieved in the MAF after microwave
irradiation and the temperature drop at the end of the cooling
period will vary with the type and amount of medical wastes
remediated. Generally, in one embodiment, the final temperature
after irradiation is about 250.degree. C., and the temperature
after 5 minutes of cooling is about 175.degree. C.
[0155] Step 216 follows completion of the spin-dry cycle. In step
216, the irises 108 at the bottom 106 of the waste receptacle 102
open and the remediated medical wastes are dumped into the second
waste receptacle 180, as shown in FIGS. 5-6 and 9. Step 218 is
performed in the second waste receptacle 180, which can include
shredding and grinding of the irradiated medical waste 4. The
second waste receptacle 180 may be assembled from commercially
procured components. Inexpensive grinder/shredder heads of varied
size and capacity and specifically designed for medical wastes are
available from various commercial sources per se (i.e. not as part
of a full shredder unit). Exemplary vendors are SSI Shredding
Systems Inc. (Wilsonville, Oreg.), Franklin-Miller (Livingston,
N.J.) and Gross (Heilbronn, Germany). As shown in FIG. 9, two
shredder heads 190 and 192 can be used serially. A preferable
serial arrangement includes a coarse grinder 190, with a larger
spacing, for large objects, e.g. larger syringes and pieces of
gowns; and a second, fine grinder 192, for finer grinding. The
second waste receptacle 180 may be customized for a specific
application, such as, for example, use within a hospital ward, an
Intensive Care Unit ("ICU"), a doctor's clinic and so on.
[0156] The second waste receptacle 180 includes a wall 184 and a
bottom 186. A divider 196 that contains an adjustable opening 108,
such as a second iris diaphragm, can serve as a top for the second
waste receptacle 180. Alternatively, the adjustable opening 108 can
be positioned on the side or bottom of the second waste receptacle
180. While the size of the second waste receptacle 180 can vary in
different embodiments, its capacity should be at least that of a
fully loaded waste receptacle 102. The second waste receptacle 180
includes a motor 188 in communication with the controller 114, one
or more shredder heads 190 and 192, and/or the adjustable opening
108.
[0157] The final product, at the end of the processing cycle, is
generally an unrecognizable fine-particulate solid medical waste
194, classified as Class 10 municipal waste and suitable for
disposal as ordinary household refuse, in landfills, and the like.
This product can be bagged and sealed as part of step 220. An
optional compactor step may be added as the final step, which would
further compact the treated medical wastes, further reducing the
volume and removing an additional, small amount of MAF still
present in the treated medical wastes.
[0158] Due to the comparatively high MAF temperatures encountered
during the remediation process, the joint seals and valves used in
the apparatus shown in FIG. 2 et seq. should be made for function
with high temperature fluids. High temperature joint seals and
valves are widely available from both commercial suppliers as well
as scientific suppliers, for example, retailers such as
McMaster-Carr Supply Co., Grainger, Cole-Parmer and Anko
Products.
[0159] The advantage of the shredding/grinding the medical waste
after remediation, as embodied in the present invention, is that
the shredder/grinder unit does not have to be decontaminated after
each use because the medical waste passing through it has already
been remediated. The design of the remediator 100 and the microwave
irradiation cycles ensure that all its components become remediated
at the end of the irradiation cycle, primarily through being
immersed in the MAF during microwaving. The MAF drained back into
the liquid reservoir after the cycles are complete is sterile.
[0160] An optional, final step in the remediation process may be
further compaction of the medical wastes after they have been
processed through the second waste receptacle 180. Although this
step is not explicitly shown in the drawings, FIGS. 5-6 illustrates
the medical waste being pushed into the second waste receptacle 180
by the cutter-blade 162. By pushing the cutter blade 162 further
into the second waste receptacle 180, further compaction can occur.
This step can squeeze out an additional approximately 50% of the
MAF still remaining absorbed in the medical wastes.
[0161] Other embodiments are set forth in FIGS. 8B and 8C. In FIG.
8B, Steps 200-204 are generally the same as set forth for FIG. 8A.
However, in FIG. 8B, the Cutter/Piston, may act to also shred the
waste in Step 204. In yet another embodiment set forth in FIG. 8C,
step 204 may be eliminated and the grinder/shredder is activated
immediately after step 202. The procedure followed is similar to
that set forth step 218 in FIG. 8A. The shredding/grinding step
designated step 205 (as in FIG. 8A) is followed by Steps 206, 208,
210, 214, 216 and 220. Step 208, the irradiation step, may range
from about 20 to about 240 minutes. The time may be dependent on
the total MAF volume, which may vary from about 3 L to about 70 L.
The cooling period in step 210 may range from about 5 to about 20
minutes. Further, in step 220, the medical waste may be removed
from the waste container.
[0162] Preferred approximate times for each of the steps for the
operation of the apparatus as described above, and with a typical
medical waste sample may be as shown in Table 1.
TABLE-US-00001 TABLE 1 Operation of Apparatus (Steps) Step
Description Preferred Time Range 204 (FIG. 8A, B) Cutter-piston
about 1 to about 2 minutes cycle 206 (FIG. 8A, 8B, 8C) MAF fill
cycle about 1 minute 208 (FIG. 8A, 8B, 8C) Microwave about 10 to
about 240 minutes irradiation cycle 210 (FIG. 8A, 8B, 8C) Cooling
period about 3 to about 20 minutes 212 (FIG. 8A, 8B, 8C) MAF drain
cycle about 1 to about 2 minutes Sieve emptying about 0.5 to about
1 minute step 214 (FIG. 8A, B, C) Spin-dry cycle about 5 minutes
216 (FIG. 8A, B) Load second about 0.5 to about 1 minute waste
receptacle 218 (FIG. 8A) Shredding/ about 2 minutes 205 (FIG. 8C)
grinding 220 (FIG. 8A, C) Seal final med- about 0.5 to about 1
minute ical waste bag
[0163] The total of these times ranges from about 25 to about 260
minutes. These times do not include the optional, final step of
further compaction.
[0164] The process can be performed at ambient pressure without any
seals of any kind.
[0165] All cycles described in the foregoing, i.e. the entire
microwave remediation process, can be automated, with a central,
programmable, microprocessor-based controller 114. The controller
114 can include a feedback loop from the two temperature sensors 5
within the main remediation chamber 120. The controller 114 can
control the power to the magnetron 150, the adjustable opening 108,
the shedder/grinder of the second waste receptacle 180, the pumps
132, the motors 144, the cutter blade 162, and any other component
that can be controlled by automation. The control can be based on
predetermined time intervals, feedback from the temperature probes
5, and on other similar parameters.
[0166] Remediator 100 can also include a liquid sensor 116 to
determine the liquid content of the medical waste. The liquid
sensor 116 can be positioned approximately one-tenth of the way up
the remediation chamber wall 122. If the liquid content of the
medical waste exceeds a specified concentration, for example, 10%
liquid by volume, the sensor 116 will send a signal to the control
means 114 to alert the operator to dispose of the MAF liquid after
the remediation cycle has been completed, rather than to reuse it,
since the MAF would then be diluted ca. 10% with non-MAF liquids,
reducing its efficacy. Thus, at the end of the remediation cycle,
the used MAF is removed from the remediator 100, and discarded, and
the reservoir 130 can be replenished with a fresh quantity of
MAF.
[0167] Another system of the invention is illustrated in FIG. 10,
which shows a remediator 200. Remediator 200 shares many of the
same components as remediator 100. Remediator 200 includes a main
remediation chamber 220 wherein a waste receptacle 202 can be
placed. The remediation chamber 220 and the waste receptacle 202
may have the same components and characteristics described above
for remediation chamber 120 and waste receptacle 102, respectively.
As with remediator 100, medical waste 4 is immersed in the MAF
composition 10, which may be added and removed from the remediation
chamber 220 through piping or tubing 231 in fluid communication
with an MAF reservoir. The MAF reservoir can be integral with
remediator 200 or can be a separate apparatus.
[0168] Remediator 200 includes a chamber assembly 240, which is
connected to the main remediation chamber 220 by hinge 241. Other
connections are also contemplated and it is also contemplated that
the chamber assembly 240 can be placed on the remediation chamber
220 without connecting it. The chamber assembly includes a lid 260
that closes the medical waste receptable 202. Alternatively, the
lid 260 can be independent of the chamber assembly 240.
[0169] Remediator 200 includes blades 262 for cutting the medical
waste 4. As shown, the blades 262 are oriented at the bottom of the
remediation chamber 220 as a series of blade clusters.
Alternatively, it is contemplated that the cutting of medical waste
4 can be performed by a single blade, a series of single blades, a
blade cluster, and/or a series of blade clusters oriented on the
top, sides, and/or bottom of the remediation chamber 220.
[0170] The remediator 200 can include a second waste receptacle for
grinding the remediated medical waste. Alternatively, the second
waste receptacle can be a unit separate from the remediator 200.
The remediated medical waste in the remediator 200 may be disposed
into the separate second waste receptacle through a
raise-swivel-and-dump mechanism, much like the way contents of a
dumpster are emptied into a trash truck.
[0171] Another system of the invention is illustrated in FIGS. 11A
and 11B, which show a remediator 300. The remediator 300 includes a
first chamber 319. The first chamber 319 includes an opening 321
into which medical waste can be introduced. As shown, the opening
is closed by a lid 323 having a hinge 325 and a latch 327. The
latch 327 locks the lid 323 to the first chamber 319.
[0172] Closures other than the illustrated lid 323 are
contemplated. For example, the remediator 300 can include a snug
fit closure, a sliding closure, a loose fit closure, a center
opening closure, and other closures known to one skilled in the
art.
[0173] Locking mechanisms other than the illustrated latch 327 are
contemplated. For example, the remediator 300 can include a lock
and bolt setup, a hook and loop arrangement, a snap, a button, and
other similar mechanisms.
[0174] As shown in FIGS. 11A and 11B, on top of the lid 323 is a
piston assembly 364, which includes a motor 367 and a piston arm
364. The piston arm 364 extends through the lid to a piston head
365. In operation, the piston head 365 compacts medical waste in
the first chamber 319, and directs the medical waste to two
grinders 363 that grind the medical waste prior to remediation.
[0175] The grinders 363 may be driven by at least one motor. As
shown, the grinders 363 rotate in opposite directions, which
directs the medical waste between the grinders 363 thereby allowing
the grinders 363 to reduce the size of the medical waste. The
grinders 363 preferably can cut steel (e.g., syringes) and other
similar materials that are commonly found in medical waste. The
grinders 363 may be commercial off the shelf grinders or custom
designed grinders.
[0176] Preferably, the grinders 363 produce ground medical waste in
which substantially all of the medical waste is less than about 1
inch in size, more preferably less than about 0.5 inch in size, and
most preferably less than about 0.25 inch in size. The smaller size
allows for better treatment of the medical waste. For example, a
smaller size allows for remnant liquids trapped in partially cut
syringes, etc. to be remediated more effectively.
[0177] As shown, the first chamber 319 also includes an angled
floor 303 for directing the ground medical waste to a remediation
chamber 320, which is in fluid communication with the first chamber
319. The first chamber 319 and the remediation chamber 320 may be
separated by, for example, a fluid permeable layer. The fluid
permeable layer comprises a valve. As shown in FIG. 11A, the valve
is a butterfly valve 309. As shown in FIG. 11B, the valve is a mesh
gate valve 311. Other valves are contemplated and may be selected
based on, for example, the ability of the valve to hold the weight
of the medical waste. Preferably, the valve, when closed, allows
fluid transfer between the remediation chamber 320 and the first
chamber 319, but prevents solids from passing between the two
chambers. For example, the valve may be a mesh gate valve.
[0178] The remediation chamber includes a waste receptacle 302,
which houses the ground waste during remediation. The waste
receptacle 302 may be made of any of the same materials as
described for vessel 2. PTFE is the preferred material for the
waste receptacle 302 due to its microwave transparency, chemical
inertness and thermal durability (to over 280.degree. C.). The
waste receptacle 302 includes a wall 304 and a base 306. The base
306 includes an opening 308, which may be an adjustable opening
such as the adjustable opening 108 of remediator 100 described
above.
[0179] As shown, the wall 304 is cylindrical, but other shapes can
be utilized. The wall 304 can be perforated with a plurality of
holes 312 to permit MAF ingress and egress. The holes 312 in the
waste receptacle wall 304 can be spaced randomly, asymmetrically or
spaced evenly. The size of the holes or perforations depend on the
desired microwave frequency. For example, for a microwave frequency
from about 2 to about 3 GHz, the size of the holes or perforations
are preferably greater than about 1 cm, more preferably greater
than about 2 cm, and most preferably greater than 3 cm.
[0180] The waste receptacle 302 may be of various sizes, with the
determinative factor on size being the waste receptacle's ability
to fit into the remediator 300. The waste receptacle 302 can have a
circular, triangular, or rectangular cross section, and it can have
a cross section of any other symmetrical or asymmetrical shape. A
cylindrical waste receptacle may have, for example, dimensions of
about 12 cm diameter by about 20 cm depth, with a resultant volume
capacity slightly over 2 liters. A cylindrical waste receptacle of
that size can hold approximately 1.4 kg of medical waste.
[0181] Preferably, the remediation chamber includes a means for
rotating the medical waste to allow for a more even application of
the microwave radiation to the medical waste in the waste
receptacle 302. For example, the waste receptacle 302 can be
rotatable. Preferably, the rotation is at a slow spin, generally
from about 2 to about 20 revolutions per minute ("rpm"). The
rotation can be accomplished by having the waste receptacle 302 on
a rotating plate (e.g. a turntable), having a rotating arm attached
to the waste receptacle 302, or by other means known by those
skilled in the art. Preferably, the waste receptacle includes a bar
across the bottom to assist in forcing the medical waste to the
sides of the waste receptacle 302 during rotation. The waste
receptacle may contain one or more supports 305.
[0182] The remediation chamber 320 includes a drain 329 for
draining a MAF, which is used in remediating the medical waste. The
drain is in fluid communication with a MAF reservoir 380. After
remediation, the MAF can be drained from the remediation chamber,
run through a filter 381, and then stored in the MAF reservoir 380
until it is needed again. When it is needed, the MAF can be pumped
from the MAF reservoir 380 to the first chamber 319 though piping,
conduits, or any other manner known to one skilled in the art.
Alternatively, the MAF is pumped into the remediation chamber 320.
The remediation chamber further comprises a motor 397 for filling
and draining of liquid. The remediation chamber 320 may include one
or more temperature sensors as described with respect to remediator
100. The remediation chamber 320 may include one or more liquid
sensors as described with respect to remediator 100.
[0183] The remediator 300 also includes at least one magnetron 350
for delivering microwave radiation to at least the remediation
chamber. As shown, the magnetron 350 is centrally located on the
remediator 300 such that microwave radiation can be delivered to
the remediation chamber 320 and the first chamber 319. The
remediator may have multiple (e.g., 2-6) magnetrons. As previously
noted, the remediator contains a slanting floor 303. In a
particular embodiment, the slanting floor 303 microwave transparent
(e.g., made of PTFE) and the magnetron(s) is placed to the outside
of the slanting floor. In the event that the slanting floor or
subfloor 303 is made of metal, the magnetron is placed in a
different location. The remediator 300 may also include a waveguide
for directing the microwave radiation from the magnetron into at
least the remediation chamber 320, and preferably into the
remediation chamber 320 and the first chamber 319. More than one
waveguide may be used.
[0184] The remediator 300 also includes a finish chamber 317 for
receiving remediated medical waste from the remediation chamber
320. The finish chamber 317 is, as shown, separated from the
remediation chamber 320 by a non-permeable layer such as a valve or
door. The valve or door may be part of the remediation chamber 320,
part of the finish chamber 317, or integral to both the remediation
chamber 320 and the finish chamber 317. As shown in FIG. 11A, the
valve is a butterfly valve 309A. As shown in FIG. 11B, the valve is
a gate valve 311A. In a particular embodiment, as shown in FIG.
11B, the operation of these valves and movement of material between
the upper and lower chambers and between the lower chamber and
waste receptacle may be controlled by motors 377A and 377B
respectively.
[0185] The finish chamber 317 includes a waste container 313 for
receiving the remediated medical waste. Preferably, the waste
container 313 is removable through an opening 315. The opening 315
may be at the bottom of the finish chamber 317 or on one of the
sides of the finish chamber 317.
[0186] Remediator 300 and its associated components may be
automated and/or controlled by a controller as described with
respect to remediator 100.
[0187] Another system of the invention is illustrated in FIGS. 12A
and 12B, which shows a remediator 400. Remediator 400 shares many
of the same elements as remediator 300. The remediator 400 includes
a first chamber 419, a remediation chamber 420, and a finish
chamber 417.
[0188] The first chamber 419 includes an opening 421 into which
medical waste can be introduced. The opening is closed by a lid
423. As shown in FIGS. 12A and 12B, the lid 423 is a snug fit
closure. Other closures such as the ones described above with
respect to the remediator 300 are also contemplated.
[0189] The first chamber 419 includes a motor 487 and a piston arm
464. The piston arm 464 extends through the side of the first
chamber 419 to a piston head 465. As shown, the piston head 465, in
its fully retracted position, is offset from the wall of the first
chamber 419. The offset allows for full decontamination of the
piston head 465. In operation, the piston head 465 directs the
medical waste in the first chamber 419 toward a grinder 463 that
grinds the medical waste prior to remediation. The medical waste is
also guided by a subfloor 403, which aids in preventing the medical
waste from passing through the first chamber 419 without being
reduced in size.
[0190] The grinder 463 may be driven by at least one motor. The
grinder 463 preferably can cut steel (e.g., syringes) and other
similar materials that are commonly found in medical waste. The
grinder 463 may be a commercial off the shelf grinder or custom
designed grinder.
[0191] Preferably, the grinder 463 produces ground medical waste in
which substantially all of the medical waste is less than about 1
inch in size, more preferably less than about 0.5 inch in size, and
most preferably less than about 0.25 inch in size. The smaller size
allows for better treatment of the medical waste. For example, a
smaller size allows for remnant liquids trapped in partially cut
syringes, etc. to be remediated more effectively.
[0192] As shown, the first chamber 419 also includes an angled
floor (also referred to as "sub-floor") 403 for directing the
ground medical waste to a remediation chamber 420, which is in
fluid communication with the first chamber 419. The first chamber
419 and the remediation chamber 420 may be separated by, for
example, a fluid permeable layer. The first chamber 419 and the
remediation chamber 420 may be separated by, for example, a valve.
As shown in FIG. 12A, the valve is a butterfly valve 409. As shown
in FIG. 12B, the valve is a gate valve 411. Other valves are
contemplated and may be selected based on, for example, the ability
of the valve to hold the weight of the medical waste. Preferably,
the valve, when closed, allows fluid transfer between the
remediation chamber 420 and the first chamber 419, but prevents
solids from passing between the two chambers. For example, the
valve may be a mesh gate valve.
[0193] The remediation chamber includes a waste receptacle 402,
which houses the ground waste during remediation. The waste
receptacle 402 may be made of any of the same materials as
described for vessel 2. PTFE is the preferred material for the
waste receptacle 402 due to its microwave transparency, chemical
inertness and thermal durability (to over 280.degree. C.). The
waste receptacle 402 includes a wall 404 and a base 406. The base
406 is angled to an opening 408, which may be an adjustable opening
such as the adjustable opening 108 of remediator 100 described
above. The chamber may further comprise one or more supports
405.
[0194] As shown, the wall 404 is cylindrical, but other shapes can
be utilized. The wall 404 can be perforated with a plurality of
holes 412 to permit MAF ingress and egress. The holes 412 in the
waste receptacle wall 404 can be spaced randomly, asymmetrically or
spaced evenly. The size of the holes or perforations depend on the
desired microwave frequency. For example, for a microwave frequency
from about 2 to about 3 GHz, the size of the holes or perforations
are preferably greater than about 1 cm, more preferably greater
than about 2 cm, and most preferably greater than 3 cm.
[0195] The waste receptacle 402 may be of various sizes, with the
determinative factor on size being the waste receptacle's ability
to fit into the remediator 400. The waste receptacle 402 can have a
circular, triangular, or rectangular cross section, and it can have
a cross section of any other symmetrical or asymmetrical shape. A
cylindrical waste receptacle may have, for example, dimensions of
about 12 cm diameter by about 20 cm depth, with a resultant volume
capacity slightly over 2 liters. A cylindrical waste receptacle of
that size can hold approximately 1.4 kg of medical waste.
[0196] Preferably, the remediation chamber 420 includes a means for
rotating the medical waste to allow for a more even application of
the microwave radiation to the medical waste in the waste
receptacle 402. For example, the waste receptacle 402 can be
rotatable. Preferably, the rotation is at a slow spin, generally
from about 2 to about 20 revolutions per minute ("rpm"). The
rotation can be accomplished by having the waste receptacle 402 on
a rotating plate (e.g. a turntable), having a rotating arm attached
to the waste receptacle 402, or by other means known by those
skilled in the art. Preferably, the waste receptacle includes a bar
across the bottom to assist in forcing the medical waste to the
sides of the waste receptacle 402 during rotation.
[0197] The remediation chamber 420 includes a drain 429 for
draining a microwave active fluid, which is used in remediating the
medical waste 4. The drain is in fluid communication with a MAF
reservoir 480. After remediation, the MAF can be drained from the
remediation chamber, run through a filter 481, and then stored in a
MAF reservoir 480 until it is needed again. When it is needed, the
MAF can be pumped from the MAF reservoir 480 to the first chamber
419 though piping, conduits, or any other manner known to one
skilled in the art. The remediation chamber further comprises a
motor 497 for filling and draining of liquid.
[0198] The remediation chamber 420 may include one or more
temperature sensors as described with respect to remediator 100.
The remediation chamber 420 may include one or more liquid sensors
416 as described with respect to remediator 100.
[0199] The remediator 400 also includes at least one magnetron 450
for delivering microwave radiation to at least the remediation
chamber. The remediator may have multiple (e.g., 2-6) magnetrons.
In a particular embodiment, the subfloor 403 is microwave
transparent (e.g., made of PTFE) and the magnetron is placed to the
outside of the subfloor 403. In the event that the subfloor 403 is
made of metal, the magnetron is placed in a different location. As
shown, the magnetron 450 is centrally located on the remediator 400
such that microwave radiation can be delivered to the remediation
chamber 420 and the first chamber 419. The remediator 400 may also
include a waveguide for directing the microwave radiation into at
least the remediation chamber 420, and preferably into the
remediation chamber 420 and the first chamber 419. More than one
waveguide may be used.
[0200] The remediator 400 also includes a finish chamber 417 for
receiving remediated medical waste from the remediation chamber
420. The finish chamber 417 is, as shown, separated from the
remediation chamber 420 by a non-permeable layer such as a valve or
door. The valve or door may be part of the remediation chamber 420,
part of the finish chamber 417, or integral to both the remediation
chamber 420 and the finish chamber 417. As shown in FIG. 12A, the
valve is a butterfly valve 409A. As shown in FIG. 12B, the valve is
a gate valve 411A. In a particular embodiment, as shown in FIG.
11B, the operation of these valves and movement of material between
the upper and lower chambers and between the lower chamber and
waste receptacle may be controlled by motors 477A and 477B
respectively.
[0201] The finish chamber 417 includes a waste container 413 for
receiving the remediated medical waste. Preferably, the waste
container 413 is removable through an opening 415. The opening 415
may be at the bottom or the finish chamber 417 or on one of the
sides of the finish chamber 417.
[0202] Remediator 400 and its associated components may be
automated and/or controlled by a controller as described with
respect to remediator 100.
[0203] In operation, remediator 300 operates in a similar manner as
remediator 400, and thus the operation of the two is described
together. With the valve 309, 311, 409, 411 between the first
chamber 319, 419 and the remediation chamber 320, 420 closed, a
user or mechanical device lifts the lid 323, 423 and inserts
medical waste into the first chamber 319, 419. The lid 323, 423 is
closed and, if present, the latch 327 is closed. MAF from the MAF
reservoir 380 or 480 is added to the first chamber so as to fill
the first chamber 319, 419 and the remediation chamber 320, 420.
Thus, the MAF, the remediation composition is dispensed from a
reservoir for immersing medical waste. The piston head 365, 465
presses the medical waste into the grinders 363, 463 (in remediator
300, the piston head 365 pushes the medical waste vertically into
the grinders 363, while in remediator 400, the piston head 465
pushes the medical waste horizontally into the grinder 463). The
grinders 365, 465 grind the medical waste, thereby reducing the
size of it.
[0204] MAF is added into either the first chamber 319, 419 or the
remediation chamber 320, 420, and allowed to fill up all of the
remediation chamber 320, 420 and a portion of the first chamber
319, 419.
[0205] The MAF can be added before, during, or after the addition
of the medical waste. For example, the MAF may be added before the
medical waste is placed in the first chamber 319, 419. The MAF may
be added after the medical waste has been placed in the first
chamber 319, 419, but before the medical waste is compacted by the
piston head 365, 465 and/or ground by the grinders 363, 463. Adding
the MAF before grinding aids in the grinding. The MAF may be added
after the medical waste has passed through the grinders 363,
463.
[0206] After the medical waste has been ground, it is deposited
into the remediation chamber 320, 420. Once the ground medical
waste and the MAF are in the remediation chamber, microwave
radiation is applied to the remediation chamber 320, 420 from the
magnetron 350, 450 to remediate the medical waste. The microwave
radiation can also be applied to the first chamber 319, 419 that is
filled or partially filled with the MAF. The application of the
microwave radiation to the first chamber 319, 419 aids in
sterilizing the first chamber 319, 419, including the grinder
heads.
[0207] After the medical waste has been remediated, the MAF is
drained from the first chamber 319, 419 and the remediation chamber
320, 420 through drain 329, 429. The used MAF is run through a
filter 381, 481 and stored in a MAF reservoir 380 or 480 for later
use. The remediated medical waste may be subjected to a spin cycle
(i.e., a cycle similar to the spin cycle of a laundry washing
machine) in the waste receptacle 302, 402 to remove MAF that is
still in the medical waste after the remediation chamber 320, 420
has been drained.
[0208] The remediated medical waste may then be transferred to the
waste container 313, 413 of the finish chamber 317, 417 by the
opening of the valve 309A, 311A, 409A, 411A. To aid in the removal
of the waste from the remediated waste, forced air may be
introduced into the first chamber 319, 419, remediation chamber
320, 420, and/or finish chamber 317, 417. The waste container 313,
413 can then be removed and the remediated medical waste disposed
of with municipal waste.
[0209] Many other design variations are possible in the
above-described embodiments, such that the initial cutter-piston
action may be up or down, horizontal or vertical, and/or in the
form of cutter-blades or grinders. The remediation chamber can be
top opening, side opening, or bottom opening. With side and bottom
opening, proper seals would be necessary to prevent leakage of the
MAF. An additional fill/drain cycle may be used to further cool the
MAF after the remediation. The MAF reservoir may be equipped with
external, aerodynamic flutes, and a small fan may be provided for
its further cooling. The filter trap process for retaining the
solids from the MAF after remediation may be automated. Multiple
magnetrons may be used. Single-mode and multimode microwave
functionality may be introduced. Thus, the step of delivering the
step of delivering the microwave radiation comprises an
intermittent delivery of the microwave radiation.
[0210] Another system of the invention is illustrated in FIG. 16,
which show a remediator 500. As will be set forth in further detail
below, in contrast to remediators 300 and 400, the remediator 500
is front loading, does not contain a valve separating the upper and
lower chamber and requires less than about 70 liters of MAF in
contrast to about 200 liters of MAF. The remediator 500 includes a
first chamber 519. As noted above, the first chamber 519 in
contrast to remediators 300 and 400 is front loading. Waste is
introduced by turning the knob 527 to create an opening and
corresponds to step 202 set forth in Table 1 and FIG. 8C. The knob
527 also serves as a latch.
[0211] As shown in FIG. 16, on top of the remediator is a waste
press 565 that acts as a means for directing the medical waste
introduced in the first chamber 519 to two cutting wheels 563 that
act as a rotatable cutting assembly and comminute the medical waste
prior to remediation set forth in Table 1 and FIG. 8C. The waste
press may be flush with one or both sides of the remediator and may
be driven by at least one motor.
[0212] The cutting wheels 563 may be driven by at least one motor.
The cutting wheels 563 work in a manner similar to the schemes set
forth for cutting wheels 363 and 463. Further, the blades of the
cutting wheels serve to control the flow of liquid from the first
chamber 519 to the remediation chamber 520 and may prevent solids
from passing between the two chambers. The blades of the cutting
wheels may be lubricated with a cutter spray lubricator 575.
[0213] As shown, the first chamber 519 also includes an angled
floor containing two components 503A and 503B for directing the
ground medical waste to a remediation chamber 520, which is in
fluid communication with the first chamber 519. The first chamber
519 and the remediation chamber 520 may be separated by, for
example, a fluid permeable layer.
[0214] MAF from an MAF reservoir may be added to either the first
chamber 519 or the remediation chamber 520 and allowed to fill up
all of the remediation chamber 520 and a portion of the first
chamber 519 and corresponds to steps 206 set forth in Table 1 and
FIG. 8C. The MAF may be added before or after the grinding
step.
[0215] The remediation chamber 520 includes a receptacle 502, which
houses the ground waste during remediation. The receptacle 502 may
be made of any of the same materials as described for vessel 2.
PTFE is the preferred material for the waste receptacle 502 due to
its microwave transparency, chemical inertness and thermal
durability (to over 280.degree. C.). The receptacle may also be
made of metal, which is opaque to microwaves. The receptacle 502
includes a wall 504 and a base 506. The receptacle may be
removable. The container may be unlocked via a handle 573. The wall
504 can be perforated with a plurality of holes 512 to permit MAF
ingress and egress. The holes 512 in the waste receptacle wall 504
can be spaced randomly, asymmetrically or spaced evenly. If the
receptacle is made of material that is not transparent to
microwaves, such as metal, then the size of the holes or
perforations depends on the desired microwave frequency. For
example, for a microwave frequency from about 2 to about 3 GHz, the
size of the holes or perforations are preferably greater than about
1 cm, more preferably greater than about 2 cm, and most preferably
greater than 3 cm.
[0216] The waste receptacle 502 may be of various sizes, with the
determinative factor on size being the waste receptacle's ability
to fit into the remediator 500. The waste receptacle 502 can have a
circular, triangular, or rectangular cross section, and it can have
a cross section of any other symmetrical or asymmetrical shape. A
cylindrical waste receptacle may have, for example, dimensions of
about 12 cm diameter by about 20 cm depth, with a resultant volume
capacity slightly over 2 liters. A cylindrical waste receptacle of
that size can hold approximately 1.4 kg of medical waste.
[0217] The remediation chamber 520 may include one or more
temperature sensors as described with respect to remediator 100.
The remediation chamber 520 may include one or more liquid sensors
516 as described with respect to remediator 100. Medical waste is
deposited into the remediation chamber 520 after the medical waste
is ground.
[0218] The remediator 500 may also include at least one magnetron
for delivering microwave radiation to at least the remediation
chamber as set forth in step 208 of FIG. 8C and Table 1. More than
one magnetron may be used. In a particular embodiment, two-six
magnetrons are used. In a preferred embodiment, four magnetrons are
used. In yet another preferred embodiment, the four may be placed
at the four directions (north, south, east, west) on the four walls
of the remediation chamber 520, for example 1/3 of the way up each
wall. The remediator 500 may also include a waveguide for directing
the microwave radiation from the magnetron into at least the
remediation chamber 520, and preferably into the remediation
chamber 520 and the first chamber 519. More than one waveguide may
be used. As previously noted, the remediator contains a slanting
floor 503. In a particular embodiment, the slanting floor 503 is
microwave transparent (e.g., made of PTFE) and at least one
magnetron is placed to the outside of the slanting floor. In the
event that the slanting floor 503 is made of metal, the magnetron
is placed in a different location. The microwave radiation can also
be applied to the first chamber 519 that is filled or partially
filled with the MAF.
[0219] The remediation chamber 520 may also contain a liquid
cooling supply 569 that serves to cool the liquid in the remediator
as set forth, for example in Step 210 of FIG. 8C and Table 1. The
cooling supply may be controlled by one or more motors 599.
[0220] After the medical waste has been remediated, the MAF may be
drained (see step 212 of FIG. 8C and Table 1) into the reservoir.
The remediated medical waste may be subjected to a spin cycle (see
step 214 of FIG. 8C and Table 1) in the waste receptacle to remove
MAF that is still in the medical waste after the remediation
chamber has been drained. The waste receptacle may be subsequently
detached from the remediator and the contents may be emptied.
[0221] Thus, the description of the specific embodiments in the
foregoing and in the examples below will fully reveal the general
nature of this invention, such that others can, through application
of current and extant knowledge, readily adapt the above-described
specific embodiments without departing from the spirit and scope of
the present invention. Such adaptations are intended to be
understood within the meaning and range of equivalents of the
disclosed embodiments, and the descriptions in this invention are
for the purpose of illustration and not limitation.
Example 1
Microwave Activity
[0222] Microwave activity in a liquid molecule is dependent upon
the presence of a strong dipole in the molecule. Thus, water, a
small, polar molecule, displays significant microwave activity.
Certain MALs display far greater microwave activity, as measured by
the temperature (heating) effect, than water. Among these are
poly(glycols), such as poly(propylene glycol) PPG or PEG. Their
microwave activity, in comparison to that of water, can be
illustrated by the temperature effect seen in the following
example.
[0223] Seventy mL of de-ionized water were taken in a 100 mL beaker
and placed at the midpoint of the platen in a 1.2 KW kitchen
microwave (Sears KENMORE.RTM. Model 721.62462201) (Registered
trademark of KCD IP, LLC, Hoffman Estates, IL) at an initial
25.degree. C. The microwave was run on high for 2.5 minutes. The
identical process was then carried out for 70 mL of PEG (molecular
weight, M.sub.n, 285-315). It was seen that the PEG attained a
temperature of 257.degree. C. but did not begin boiling, whereas
the water achieved 97.degree. C. and just started to boil.
[0224] The MAF compositions listed in Table 2 were irradiated using
a Sears KENMORE.RTM. Model 721 62462 microwave oven (1.2 KW, 2.45
GHz, 13.5 Amperes). The MAL, where present in the MAF compositions,
was poly(ethylene glycol) M.sub.n=200-415 ("PEG"). The viscosity
modifying agent, where present in the MAF compositions, was
poly(ethylene oxide), M.sub.w 200,000 ("PEO"). The microwave
enhancer, where present in the MAF compositions, was activated
carbon, DARCO.RTM. (Registered trademark of Norit Americas, Inc.),
20 to 40 mesh ("activated-C"). Each composition comprised 50 mL
fluid in a 100 mL beaker. All composition percentages are in wt. %.
All were stable milk-like sols. The microwave activity of the MAF
are illustrated, in comparison to that of water, in Table 2.
TABLE-US-00002 TABLE 2 Microwave activity of MAF compositions Temp.
Temp. Temp. Temp. MAF (.degree. C.), (.degree. C.), at (.degree.
C.), at (.degree. C.), at Composition initial 60 sec 120 sec 157
sec Tap water 24.0 97.2 100, 100, boiling boiling PEG 24.0 178.0
239.3 256.5 0.5% activated-C, 24.0 180.5 233.5 255.0 1% PEO in PEG
1% SiC, 1% PEO 24.0 274.3, in PEG boiling 5% activated-C, 24.0
325.1, 1% PEO in PEG boiling 2.5% activated-C, 24.0 311.3, 1% PEO
in PEG boiling 5% Fe.sub.3O.sub.4, 1% 24.0 271.0 PEO in PEG
[0225] Examples 2 to 7 illustrate the medical waste remediating
capability of MAFs of the invention.
Example 2
AOAC (Association of Official Analytical Chemists) Sporicidal
Test
[0226] The AOAC Sporicidal Test, an industry-standard test, was
used to determine the remediation capability of an MAF of the
present invention. The MAF used in these tests had the following
composition: MAL=PEG, M.sub.n 200-415, b.p.>275.degree. C.
(Sigma-Aldrich); viscosity modifying agent=PEO M.sub.v 200,000
(Sigma-Aldrich), 1 wt. % in PEG; microwave
enhancer=activated-charcoal ("decolorizing", Sigma-Aldrich), 1 wt.
% in PEG. The MAF was prepared by dissolving the PEO in the MAL at
105.degree. C. with stirring over 1.5 hours. The resulting solution
was allowed to cool to 80.degree. C. The activated-charcoal was
added to the PEO/PEG solution with stirring at 80.degree. C. for an
additional 0.5 hour to form a sol. The sol was then allowed to cool
to room temperature.
[0227] For each test, 10 mL of the MAF was placed in each of 6
sterile tubes. Five Bacillus subtilis AOAC Carriers (Porcelain
Penicylinders or Black Silk Suture Loops) were inoculated into each
of the six tubes. The preparation of test materials and the actual
testing followed AOAC procedures required for a full AOAC
Sporicidal Test. The tubes of MAF with carriers and without
closures were placed in a 1.5 L PYREX.RTM. glass beaker, which was
covered with a PYREX.RTM. glass plate. The covered beaker with
carrier tubes was placed in a Sears KENMORE.RTM. microwave oven
(Model 721.62461, 1200 Watts, 2.45 GHz). The covered beaker was
placed at the end of one of the tripod legs in the microwave oven's
rotating glass plate (i.e., off center). The covered beaker and its
contents were exposed to microwave irradiation for a predetermined
time, as noted in the results (Table 3) below. The tubes were
positioned in the beaker with the bottoms pointing to the periphery
of the beaker during the microwave exposure.
[0228] Following microwave exposure, the beaker was removed to a
certified laminar flow bench. Exposed carriers were transferred to
individual tubes of fluid thioglycolate medium. After a 30-minute
neutralization period, carriers were subcultured from the first
tube to a second tube of fluid thioglycolate medium. Both sets of
subcultured tubes were incubated at 37.degree. C. and observed for
growth (+) or no growth (-). During exposure, suture loops
disintegrated in some cases. Consequently, for subculturing in
those cases where loops disintegrated, a standardized loop (4 mm)
was used to subculture from the exposed tube and also for the
second sub-cultured tube.
[0229] The MAF of the present invention achieved spore kill of B.
subtilis in a shorter period than other non-traditional sporicidal
products.
[0230] Results of the Sporicidal Test are listed in Table 3
below.
TABLE-US-00003 TABLE 3 AOAC Sporicidal Screening Test Results For
An MAF With (Bacillus subtilis ATCC 19659), Exposure Test No. Test
Date Time Carriers/No Results Results 1A Feb. 10, 2007 15 min P-30
0+/30 0+/30 2A Feb. 14, 2007 15 min S-30 3+/30 3+/30 3A Feb. 19,
2007 11 min P-30 0+/30 0+/30 4A Feb. 24, 2007 5 min P-30 0+/30
0+/30 5A Mar. 3, 2007 17 min S-30 1+/30 1+/30 6A Mar. 19, 2007 19
min S-30 0+/30 0+/30 (LEGEND: P = Penicylinder; S = Suture Loops.)
(Results quoted as Number positive/Number exposed. Thus 1+/30
indicates 1 positive result out of 30 exposed samples.)
Example 3
MAF Remediation of Bacteria
[0231] To determine the effect of MAF treatment on bacteria,
substrates were inoculated with bacterial cultures to form
infectious medical wastes ("IMW") as described as below. The IMW
were treated with a quantity of the MAF prepared as in Example 2,
and microwave irradiated. The treated and irradiated IMW were
tested for biological activity as described below. MAF was also
prepared as described in Example 2.
[0232] Accordingly, preparation of the IMW began by collecting
substrates (samples), which included: bandages, cotton gauze,
cotton balls, self-adhesive bandages (pad portion and adhesive
portion), cotton plugs, latex and vinyl gloves, swabs, cultures,
plastic syringes (plunger and receptacle part), metal syringe
needles, disposable scalpels and other small surgical instruments.
All non-metallic substrates were cut into strips of 1 cm by 3 cm.
Metallic substrates (scalpels, syringe needles) were taken as is.
In addition to the non-metallic and metallic substrates,
commercially procured microbe sample strips and/or pellets
(retained in open vials) (B. subtilis, MicroBiologics, St. Cloud,
Minn. and Fisher Scientific, Pittsburgh, Pa.) were also used as
substrates. Finally, a liquid content of at least 5 wt. %, absorbed
into the cotton swabs and plugs, was ensured in order to emulate
actual medical waste samples as close as possible. This was done by
soaking dry swabs with a 5 wt. % liquid, such as, for example,
water or a bacterial culture medium.
[0233] Bacteria for use in the present example included one or more
of the following: Bacillus cereus, B. subtilis (aerobic bacteria,
cultures procured from ATCC) (American Type Culture Collection,
Manassas, Va.); Clostridium beijerinckii (anaerobic bacterium,
cultures procured from ATCC), B. anthracis V1B, and Mycobacterium
tuberculosis H37Rv (pathogenic bacteria, cultures at Center for
Biodefense, University of Medicine & Dentistry of New Jersey
("UMDNJ", New Jersey Medical School), Newark, N.J.). For the
Bacillus and Clostridium species, only spores were used for all
tests. Spores are much hardier than the bacteria, and the killing
of spores is more definitive proof of remediation than killing of
bacteria. The work with the pathogenic organisms was carried out in
a hood in a BSL-3 laboratory at the Center for Biodefense, Newark,
N.J.
[0234] The porous or absorbent substrates, such as gauze and cotton
plugs, were soaked in the bacterial culture. The non-absorbent
substrates, such as the gloves and the plastic portion of
self-adhesive bandages (such as BAND-AIDS.RTM.), were infected by
pouring about 3 mL of liquid culture onto them, and allowing this
to partially dry (about 20 mins in air). Syringe needle tips and
the top part of syringes were simply filled with the culture. The
culture was laid on metallic parts such as scalpels, and allowed to
dry under incubation conditions. The infected parts were marked
with circular markings using a microbiological marker pen. The
medical wastes were enclosed in a perforated TEFLON.RTM. bag or
envelope, for ease of handling and also to emulate practical use of
the invention with "red bags". (TEFLON.RTM. is the material of
choice for use in microwaves because it is substantially
microwave-transparent and is chemically inert and non-stick.) In
addition to the above, commercially available B. subtilis "microbe
sample strips" were also included as part of the IMW.
[0235] The bacterial-inoculated IMW was then immersed in MAF in a
cylindrical crystallizing dish made of borosilicate glass. The
weight of the IMW was 400 g, and 600 mL of the MAF was used for
immersion, providing a 1/1.5, w/v IMW/MAF ratio. A flat, circular
borosilicate glass cover, or, alternatively, an inverted PYREX.RTM.
backing dish, was placed loosely on top of the crystallizing dish.
The crystallizing dish was then placed in a Sears KENMORE.RTM.
microwave oven (Model 721.62461, 1.2 KW, 2.45 GHz), such that it
was centered on the midpoint of one of the turntable tripod legs,
i.e., about 10 cm off center. The microwave was then run on the
"high" setting for 20 minutes. The temperature was monitored with a
LUXTRON.RTM. One fluoro-optic sensor. The temperature observed at
10 min. was 235.degree. C. The oven was switched off for 60 seconds
(10.sup.th to 11.sup.th minute). It was run again on "high" from
the 12.sup.th through the 17.sup.th minute, switched off again from
the 17.sup.th to the 18.sup.th minute, and run again through 20
minutes. The final temperature observed was 237.degree. C. No fumes
or other external manifestation of reactions or other processes
were visible at the end of the microwave run. The dish and cover
were then removed from the microwave using oven mitts and allowed
to cool in ambient air for 15 minutes. The IMW was press-strained
and then cultured, as described in the next paragraph.
[0236] For growth of cultures, a minimum of 96 hours (4 days) was
allowed. Cultures were grown using Miller LB (Luria-Bertani) broth
and LB agar Difco medium (Fisher Scientific), at 30.degree. C.,
with Gram stain, for the aerobic organisms, and brain-heart
infusion agar for the anaerobic cultures. Each experiment was
carried out in triplicate.
[0237] The experiments in this example were preformed in the same
manner and with the same materials as Example 3, except that in
this Example, actual "red-bag medical wastes" (blood-soaked
bandages, needles, etc.) were used as samples in place of the
bacteria-inoculated IMW prepared as described in Example 3. The
red-bag medical wastes were obtained from the UMDNJ Hospital,
Newark, N.J. Tests were conducted in the Biosafety Level ("BSL")-3
facility at the Center for Bio-Defense, Newark, N.J. "Sample" runs,
with microwave irradiation of the red-bag medical wastes immersed
in the MAF, are designated in Table 4 as "M". "Reference" runs,
with immersion of the medical wastes in the MAF but no microwave
exposure, are designated in Table 4 as "R". "Control" runs, with
neither immersion of the medical wastes in the MAF nor microwave
exposure, are designated in Table 4 as "C".
[0238] The results are summarized in Table 4. The results are the
summary of more than 100 individual experiments, each run in
triplicate. The Reference and Control runs showed profuse culture
growth.
TABLE-US-00004 TABLE 4 Results from Examples 3, 4: Use of MAF to
Remediate IMW and Actual Red-Bag Hospital medical wastes Medical
Serial waste Type, Results @ Results @ # weight Organism Run Type
96 h 14 d 1. IMW, 400 g Bacillus cereus (aerobe) M, 11 minutes (-)
(-) IMW, 400 g '' C (+) IMW, 400 g '' R (+) 2. IMW, 400 g B.
subtilis (aerobe) M, 13 minutes (-) (-) IMW, 400 g '' C IMW, 400 g
'' R (+) 3. IMW, 550 g B. cereus M, 15 minutes (-) (-) IMW, 550 g
'' C (+) IMW, 550 g '' R (+) 4. IMW, 350 g B. cereus M, 7 minutes
(-) (-) IMW, 350 g '' C (+) IMW, 350 g '' R (+) 5. IMW, 400 g
Clostridium M, 13 minutes (-) (-) beijerinckii (anaerobe) IMW, 400
g Clostridium C (+) beijerinckii (anaerobe) IMW, 400 g Clostridium
R (+) beijerinckii (anaerobe) 6. IMW, 2 kg B. cereus M, 19 minutes
(-) (-) IMW, 2 kg '' C (+) IMW, 2 kg '' R (+) 7. IMW, 300 g
Bacillus anthracis M, 13 minutes (-) (-) V1B (pathogen) IMW, 300 g
Bacillus anthracis C (+) V1B (pathogen) IMW, 300 g Bacillus
anthracis R (+) V1B (pathogen) 8. IMW, 300 g Mycobacterium M, 13
minutes (-) (-) tuberculosis, H37Rv (pathogen) IMW, 300 g
Mycobacterium C (+) tuberculosis, H37Rv (pathogen) IMW, 300 g
Mycobacterium R (+) tuberculosis, H37Rv (pathogen) 9. "Red bag
Varied bacteria and M, 13 minutes (-) (-) medical viruses present
in wastes", hospital medical 350 g wastes "Red bag Varied bacteria
and C (+) medical viruses present in wastes", hospital medical 350
g wastes "Red bag Varied bacteria and R (+) medical viruses present
in wastes", hospital medical 350 g wastes ABBREVIATIONS: For
medical waste Type: IMW = infected medical waste, mixed medical
waste prepared as described above For Run Type column: R =
"Reference", immersion in MAF but no microwave exposure; C =
"Control", no microwave liquid and no microwave exposure. M =
Microwave exposure run, exposure time given. For Results column:
(+) = growth. (-) = no growth. h = hours d = days
Comparative Examples
Comparative Example 5
Use of PEG to Remediate IMW
[0239] The experiments in this example were preformed in the same
manner and with the same materials as Example 3, except that the
IMW was immersed in PEG only, and not the fully formulated MAF as
described in Example 3. Thus, no microwave enhancers and no
viscosity modifying agents were added to the MAL. "Sample" runs,
with microwave irradiation of the IMW immersed in the MAL, are
designated in Table 5 as "M" (for "microwave"). "Reference" runs,
with immersion of the IMW in the MAL but no microwave exposure, are
designated in Table 5 as "R". "Control" runs, with neither
immersion of the IMW in the MAL nor microwave exposure, are
designated in Table 5 as "C".
TABLE-US-00005 TABLE 5 Summary Results Of Example 5: PEG Only As
The MAF To Remediate IMW Medical Serial waste Type, Results @
Results @ # weight Organism Run Type 96 h 14 d 10. IMW, 400 g
Bacillus M, 18 (-) (-) cereus (aerobe) minutes IMW, 400 g Bacillus
C (+) cereus (aerobe) IMW, 400 g Bacillus R (+) cereus (aerobe) 11.
IMW, 400 g B. subtilis M, 20 (-) (-) (aerobe) minutes IMW, 400 g B.
subtilis C (aerobe) IMW, 400 g B. subtilis R (+) (aerobe) 12. IMW,
400 g Clostridium M, 22 (-) (-) beijerinckii minutes (anaerobe)
IMW, 400 g Clostridium C (+) beijerinckii (anaerobe) IMW, 400 g
Clostridium R (+) beijerinckii (anaerobe) ABBREVIATIONS: For
medical waste Type: IMW = infected medical waste, mixed medical
waste prepared as described above. For Run Type column: R =
"Reference", immersion in MAF but no microwave exposure; C =
"Control", no microwave liquid and no microwave exposure. M =
Microwave exposure run, exposure time given. For Results column:
(+) = growth. (-) = no growth. h = hours d = days
[0240] It is seen that while PEG alone is able to achieve
remediation, the microwave irradiation times are significantly
longer than those for the fully formulated MAF of the present
invention, as seen in the results presented in Table 5. Thus, the
fully formulated MAF of the present invention is superior to PEG
alone.
Comparative Example 6
Comparison of the Present Invention with Standard Steam
Autoclaving
[0241] The microwave procedure as described in Example 3 was
compared to autoclaving of the identical charge of 350 g of medical
waste in a standard laboratory autoclave (All American "Electric
Pressure Steam Sterilizer", Model N.degree. 25X, 120 V, 1050 W,
8.75 A, total capacity (volume) about. 10 L). The microwave
procedure took 15 minutes to complete. The final temperature
observed was 235.degree. C. All samples showed no microbial growth
after 14 days of culturing. The autoclave procedure took a total of
81 minutes, including the time required to reach the recommended
steaming pressure of 20 psi and the recommended residence time of
at least 20 minutes at this pressure. The autoclaved samples also
showed no microbial growth after 14 days of culturing. The total
energy expended in the microwave procedure was 0.279 KWH
(kilowatt-hours), and that expended in the autoclave procedure was
1.418 KWH to obtain the same degree of sterilization. Thus, the
microwave procedure expended just 19.7% of the energy of the
autoclave procedure to obtain the same degree of sterilization. The
microwave procedure also accommodated a sample of 700 g or larger,
whereas the autoclave accommodated a maximum of 450 g, limited by
volume of the container and supporting vessels within the
autoclave.
Comparative Example 7
Comparison of Heat-Only Remediation Vs. Microwave-Based Remediation
of the Present Invention
[0242] The samples for this example comprised dry spores of
Bacillus subtilis or Bacillus cereus, or cotton swabs inoculated
with those spores.
[0243] In the microwave run, the samples were introduced into a
microwave oven (Sears KENMORE.RTM. microwave oven (Model 721.62461,
1.2 KW, 2.45 GHz) and maintained at 150.degree. C. for 1 minute or
3 minutes, immersed in 50 mL of MAF prepared according to Examples
2-4, held in a 100 mL beaker. MAF temperature was monitored
carefully using LUXTRON.RTM. fiber-optic sensors. Two runs each of
triplicates were carried out for all four sample types (dry
Bacillus subtilis, dry Bacillus cereus, Bacillus subtilis cotton
swab, Bacillus cereus cotton swab). Both exposure times, 1 min and
3 min, resulted in no microbial growth at 96 hours and 14 days for
all four sample types.
[0244] In a corresponding, non-microwave, heat-only experiment,
identically prepared samples were immersed in the same MAF
(identical volume and identical vessel), but heated in a mineral
oil bath, at a steady temperature of 150.degree. C., for exposure
times of 1, 3 and 7 minutes. Temperature was monitored with a
thermometer immersed in the MAF. All three exposure times, i.e. 1,
3 and 7 minutes, showed significant microbial growth at 96 hours
(TNTC, "too numerous to count").
[0245] In both the microwave and the non-microwave (heat-only)
experiments, the following additional runs were also carried out:
"Reference"--samples immersed in the MAF, but having no microwave
or heat exposure; and "Control"--samples cultured directly, i.e.
with no immersion in MAF and no microwave or heat exposure. All
Reference and Control runs showed significant microbial growth, too
numerous t count, at 96 hours, as expected, for all sample
types.
[0246] These results demonstrate that the microwave chemistry
effect in microwave remediation is not just a temperature effect.
Microwaves cause disruption of the tertiary and quaternary
structure of proteins in bacteria (or other organisms),
"denaturing" them and thus eventually causing death of the
organisms. The results show the unique and predominant effect of
microwave chemistry as compared to non-microwave heat
sterilization.
Example 8
Analyses of Post-Microwave Degradation/-Decomposition Products
[0247] One of the concerns with any remediation method for medical
wastes is the possibility of potentially toxic or otherwise
hazardous waste products. Table 6 summarizes results of a
literature study conducted to identify possible degradation
products that could result from the processes of the present
invention. As just some examples of some of studies of direct
relevance to the present invention are: (i) For analysis of
products of burning of medical waste such as surgical gloves and
cotton pads, Levendis, Y. A.; Atal, A.; Carlson, J. B.; del Mar
Esperanza Quintana, M., "PAH and soot emissions from burning
components of medical waste: examination/surgical gloves and cotton
pads", Chemosphere, 42, 775-783 (2001); (ii) For semi-volatile and
volatile compounds from pyrolysis and combustion of poly(vinyl
chloride) (PVC) and polyethylene Aracil, I.; Font, R.; Conesa, J.
A., "Semi-volatile compounds from the pyrolysis and combustion of
polyvinyl chloride", J. Anal. Applied Pyrolysis, 74, 465-478
(2005); (iii) For studies on the thermal decomposition products of
a variety of plastics specifically found in medical wastes and
studies of "low-temperature" pyrolysis products of PEG Lattimer, R.
P., "Mass spectral analysis of low-temperature pyrolysis products
from poly(ethylene glycol)", J. Anal. Applied Pyrolysis, 56, 61-78
(2000). ("Pyrolysis" and "combustion" refer, respectively, to
thermal breakdown in the absence and presence of oxygen). The data
from the literature study is compiled in Table 6.
TABLE-US-00006 TABLE 6 Summary Of Thermal Degradation (Pyrolysis
And Combustion) Studies Of MAF Components And Medical wastes A.
PRODUCTS FROM POLY(ETHYLENE GLYCOL) (PEG) A.1 Low Temperature
Pyrolysis, 150 to 250.degree. C. PEG oligomers,
HO--(--C.sub.2H.sub.4--O--).sub.n--H, n > 10 typically. Oligomer
of Ethyl ether,
C.sub.2H.sub.5--O--(--C.sub.2H.sub.4--O--).sub.n--H, n > 10
typically. A.2 Higher Temperature Pyrolysis, >250.degree. C.
Other products, e.g. methyl, vinyl ethers, in oligomer form (n >
10 typically) as above. B. FROM IMW ("RED BAG MEDICAL WASTES") B.1
High temperature (1 000.degree. C.) combustion, of latex gloves,
sterile cotton pads, etc., all "red bag" medical wastes Besides CO,
CO.sub.2, NO.sub.x, main medical wastes are particulates (soot) and
polynuclear aromatic compounds (PACs). PACs: From Latex:
Naphthalene (most), phenanthrene (2.sup.nd), acenaphthylene
(3.sup.rd), pyrene (4.sup.th). From Cotton: Acenaphthylene (most),
naphthalene (2.sup.nd), pyrene (4.sup.th). But all much smaller
quantities than from Latex. C. FROM POLYETHYLENE (HDPE) C.1 High
temperature (500.degree. C.) combustion Mostly CO.sub.2, CO. Alpha,
omega- olefins, alpha-olefins, n-paraffins other main products.
E.g. ethylene, propylene, n-butane, 1,3-butadiene. On the basis of
this, it is expected that main products in our experiments would be
expected to be oligo-ethylenes. We should also look out for
aldehydes. D. FROM POLY(VINYL CHLORIDE) (PVC) D.1 At 500.degree. C.
(studied to 1000.degree. C.) Mainly CO.sub.2, CO. HCl produced
which further reacts to give other products. Methane, ethane,
ethylene, benzene are other major products.
[0248] Using the information from Table 6 as a point of comparison,
an analysis of the products (i.e., the medical waste and MAF after
remediation), after 21 microwave runs, using the MAF prepared
according to Example 2 were carried out, encompassing a wide
variety of techniques, including spectroscopy (FTIR, .sup.13C and
proton NMR, UV-Vis), mass spectrometry and chromatography. The
present example summarizes these results. As the results show, no
toxic or hazardous products were indicated.
[0249] FIG. 13 shows the FTIR spectra of (i) Unused MAF prepared
according to Example 2. The spectrum of the unused MAF was nearly
identical to that of PEG, M.sub.n 200 to 415, which was the main
component of the MAF. (ii) Used MAF prepared according to Example
2, and put through 21 microwave runs as described in Example 4. The
MAF was not filtered during the runs. The spectra of the Unused MAF
and the Used MAF were nearly identical. Thus, after 21 uses, the
MAF was essentially free of degradation products.
[0250] FIG. 14(a) shows a proton spectrum for pure PEG. FIG. 14(b)
shows a .sup.13C NMR spectrum for pure PEG. FIG. 14(c) shows a
proton spectrum for an unfiltered MAF according to the invention,
after 21 microwave cycles. FIG. 14(d) shows a .sup.13C NMR spectrum
for an unfiltered MAF according to the invention, after 21
microwave cycles. Samples were diluted with chloroform-d for the
.sup.1H NMR and acetone-d6 for the .sup.13C NMR. In the proton
spectra, the only other significant peaks are centered at 3.65 ppm.
There are three types of H present: --O--CH.sub.2--CH.sub.2--O--
(triplets, ethers, 3.0-4.0 ppm), HO--CH.sub.2-- (singlet, alcohols,
0.5-5.5 ppm) and HO--CH.sub.2--CH.sub.2--O-- (triplets, alcohols,
3.0-4.0 ppm). This is consistent with PEG. The peaks of the pure
PEG and the Used MAF spectra are nearly identical. Some slight
differences between the spectra can be attributed to sample
preparation (dilution accuracies) for the NMR analysis. Thus, the
pure PEG and the Used MAF spectra are identical, indicating no
observable degradation products. Although the spectra of PEG
decomposition products such as tetraethylene glycol are somewhat
similar, they have distinctive features which are not seen in the
Used MAF spectrum. Decomposition products such as saturated alkanes
would show up in the 0-2 ppm range and vinyls would present in the
6-7 range. Any decomposition product from PVC again would present
outside of the 3-4 ppm range. PACs would show up as aromatics in
the 6.0-8.0 ppm range. None of these peaks are present in the Used
MAF spectra, indicating that none of these decomposition products
were produced.
[0251] In the case of the .sup.13C NMR spectra, C--O carbons
resonate in the 50-70 ppm shift range. All carbons in PEG are C--O
carbons, so the only peaks for PEG are in this range. The pure PEG
and the Used MAF spectra both have three peaks in the 60-70 ppm
range. These spectra are nearly identical.
[0252] Most of the proposed thermal degradation products (from
Table 6) would appear as peaks outside of the 60-70 ppm region of
PEG peaks. Aromatics, aldehydes, esters, and alkanes would appear
above 100 ppm. No unidentified peaks were present in this range,
once again indicating no decomposition products formed in the used
MAF.
[0253] FIG. 15(a) is a the chromatogram portion of a representative
GC-MS spectrum for an MAF according to the invention after 21
microwave irradiation cycles, and gives elution times in minutes).
FIG. 15(b) shows the mass spectrum for one of the pyrolysis
products, 2,2'-oxybis-ethanol, corresponding to the elution time of
16.25 min in the TIC chromatogram of FIG. 15(a).
[0254] A detailed analysis showed that the products were just
pyrolysis products of PEG, an artifact of the GC-MS technique,
where the sample is ionized in a vacuum and then subject to high
effective temperatures.
[0255] The conclusion from the comparative data in Table 6 and
FIGS. 13-15 is that there is no trace of any hazardous or toxic
decomposition products from microwave runs utilizing the present
compositions and methods, and certainly nothing resembling the
products typically found in the many studies of "low-temperature"
pyrolysis and combustion of the components of the MAF and the
components of the medical wastes, such as anthracene and
poly-aromatic hydrocarbons (PAHs) (as summarized in Table 6). This
applies to degradation products from both the MAF and the medical
wastes.
[0256] One feature of nearly all the literature studies presented
in Table 6 is that even when they refer to "low temperatures", the
temperatures, typically are at least 300.degree. C., which are
higher than temperatures contemplated using the compositions and
methods described herein. For example, Lattimer's "low-temperature"
pyrolysis study of PEG actually describes pyrolysis under Argon ion
flow at temperatures of 150.degree. C. to 325.degree. C. Other
studies typically use even higher temperatures, of 500.degree. C.
to up to 1500.degree. C. These higher temperatures facilitate a
more, not less, advantageous comparison with the present
compositions and methods. For if it is shown that the products
observed from thermal degradation of the relevant materials at much
higher temperatures are not observed with the much lower
temperatures of the present invention, then this establishes that
the much lower temperatures of the present invention could not
produce any toxic or hazardous substances.
[0257] It will be appreciated by those skilled in the art that the
present invention may be practiced in various alternate forms and
configurations. The previously detailed descriptions of the
disclosed compositions and methods are presented for clarity of
understanding only, and no unnecessary limitations should be
implied therefrom.
[0258] The invention described and claimed herein is not to be
limited in scope by the specific embodiments herein disclosed,
since these embodiments are intended as illustrations of several
aspects of the invention. Any equivalent embodiments are intended
to be within the scope of this invention. Indeed, various
modifications of the invention in addition to those shown and
described herein will become apparent to those skilled in the art
from the foregoing description. Such modifications are also
intended to fall within the scope of the appended claims.
* * * * *