The present invention relates to a device and method for treatment of waste and in particular to the generation and use of a liquid disinfectant for treating infectious waste.
In the normal course of operation, hospitals generate a variety of waste which is not suitable for normal disposal. While some or most hospital waste may be harmless, it is difficult to distinguish such harmless waste from infectious waste. As a result, all of the waste from a hospital must be treated as if it may be harmful. Also, sensitivity to the handling of hospital waste has been raised as a result of AIDS and other health issues. Recently, the bird flu spread rapidly and initially was not well understood. As world travel has increased, so has the ability of infections, like the bird flu, to spread rapidly, and the need to contain outbreaks is greater than ever before. For all of these reasons, there is a need to deal properly with hospital waste.
Common methods of treating hospital waste include systems having a steam autoclave or an ethylene oxide autoclave. U.S. Pat. No. 6,726,136 for “Waste treatment plant,” describes a system including an autoclave. Other systems include incinerators. Unfortunately, incinerators may be difficult to construct and operate, and may create environmental issues. Autoclaves may also be expensive and difficult to operate. Systems including autoclaves may also require additional steps to complete disinfecting waste.
U.S. Pat. Nos. 5,424,925 and 5,656,248 for “Multi-stage infectious waste treatment system,” both assigned to the assignee of the present application, describe waste treatment systems which grind waste into small particle size, and then soak the waste in a volatile liquid disinfectant. The '248 patent teaches the advantages of using aqueous chlorine dioxide as a liquid disinfectant. The '248 patent further teaches generating chlorine dioxide from a combination of sodium chlorite and a weak organic acid. While there are several advantages in using aqueous chlorine dioxide, the generation of chlorine dioxide from sodium chlorite and a weak organic acid results in a delay in the introduction of chlorine dioxide when a low chlorine dioxide concentration is measured, and in a delay in stopping the production of chlorine dioxide when the desired concentration is reached. Because the infectious waste treatment equipment can only be operated within a range of disinfectant concentrations, periods of non-operation result. The '925 and the '248 patents are herein incorporated by reference.
Other hospital wastes that have been subject to special treatment are Trace Chemo and Suction Canisters. Trace Chemo is trace material left in used waste containers, tubes, needles etc. after use. Trace Chemo medical waste is considered empty waste because the Chemo that was once inside of the waste containers, tubes, needles etc. is no longer inside. Presently, Trace Chemo is treated by burning.
Suction Canisters are filled with fluids and contents from the operating room. Because the contents inside the canister are fluids or gelled fluid, it is difficult for them to reach disinfecting temperatures using known treatment methods. Presently, the only method commonly utilized to treat Trace Chemo and Suction Canisters is incineration.
The present invention addresses the above and other needs by providing an infectious waste treatment system which uses a chlorine dioxide disinfectant generated by combining precursors comprising sodium chlorite, acid, and bleach. The waste is ground into small pieces and soaked in the chlorine dioxide. The chlorine dioxide is generated by combining dilute aqueous precursors metered by fixed flow restrictors. An efficient set of precursors comprises an approximately 25 percent aqueous sodium chlorite solution, an approximately 12 percent to approximately 50 percent citric acid solution, and approximately a 12 percent industrial bleach (i.e., sodium hypochlorite) solution such as sold under the trademark Clorox®. A continuous gas monitoring system measures the concentration of chlorine dioxide in the system and commands the chlorine dioxide generator to generate chlorine dioxide when necessary. When a low liquid disinfectant level is measured, the chlorine dioxide is generated by combining the precursors with water. When the liquid disinfectant level is acceptable, the chlorine dioxide is generated by combining the precursors with existing liquid disinfectant.
In accordance with one aspect of the invention, there is provided a hospital waste treatment system. The hospital waste treatment system comprises a grinder for receiving unprocessed waste material and grinding the unprocessed waste material to produce ground material, a main solution tank for receiving the ground material from the grinder, and a liquid disinfectant in the main solution tank for disinfecting the ground material. The liquid disinfectant comprises an aqueous chlorine dioxide solution. The aqueous chlorine dioxide is generated from precursors comprising aqueous sodium chlorite, an acid, and a bleach. A chlorine dioxide generator is used for combining the precursors with a flow to generate the aqueous chlorine dioxide to add to the liquid disinfectant. The chlorine dioxide generator includes an eductor for drawing the precursors into a flow and the amount of the individual precursors drawn into the eductor is regulated by fixed flow restrictors.
In accordance with another aspect of the invention, there is provided a hospital waste treatment system. The hospital waste treatment system comprises a grinder for receiving unprocessed waste material and grinding the unprocessed waste material to produce ground material, a main solution tank for receiving the ground material from the grinder, and a liquid disinfectant in the main solution tank for disinfecting the ground material. The liquid disinfectant comprising aqueous chlorine dioxide generated from precursors. The precursors used to generate the aqueous chlorine dioxide comprise aqueous sodium chlorite, citric acid, and aqueous sodium hypochlorite. A chlorine dioxide generator is used for combining the precursors with a flow to generate aqueous chlorine dioxide to add to the liquid disinfectant.
The above and other aspects, features and advantages of the present invention will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings wherein:
Corresponding reference characters indicate corresponding components throughout the several views of the drawings.
The following description is of the best mode presently contemplated for carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims.
A waste treatment system 10 according to the present invention is shown in
Continuing with
A continuous gas monitoring system 38 monitors the liquid disinfectant level in the main solution tank 18 and composition (i.e., strength) of the liquid disinfectant, and controls the generation of liquid disinfectant (see
The auger 20 is preferably a shaftless auger residing in an auger housing 21 supported by an auger strut 23 and is powered by an auger motor 22 which is preferably connected to the auger 20 through a gearbox 22a. The auger 20 further includes a fluid trap 28 where the liquid disinfectant used to wet the ground waste is trapped and recirculated back into the main tank. A rotatable section 26 of the auger housing 21 may be rotationally positioned relative to the auger housing 21 at various rotations to adjust the position of a chute 24. If the chute 24 is pointed down, the back pressure on the flow of the ground waste is minimized, and the amount of liquid disinfectant removed by the fluid trap 28 is minimized. As the chute 24 is rotated away from a pointed down position, the back pressure on the flow of the ground waste is increased, and the amount of liquid disinfectant removed by the fluid trap 28 is increased. If the chute 24 is rotated to an upward position, the back pressure on the flow of the ground waste is maximized, and the amount of liquid disinfectant removed by the fluid trap 28 is maximized.
A side view of the main solution tank 18 suitable for use with the waste treatment system 10 is shown in
Continuing with
A bubble tank assembly 128 is partially submerged in the disinfectant liquid below the static fluid level 78a and to preferably within approximately one half inch of the bottom of the main solution tank 18, and is further described in
A second side view of the main solution tank 18 (an opposite side view from FIGS. 1 or 3) showing the continuous gas monitoring system 38, the pump 90, and liquid disinfectant generator elements are shown in
Continuing with
The liquid disinfectant precursors preferably comprise an approximately 12 percent industrial clorox bleach (i.e., sodium hypochlorite), an approximately 12 percent to approximately 50 percent citric acid solution, an approximately 25 percent sodium chlorite solution as precursors for chlorine dioxide, and an anti-form agent. The chemical manifold 112 is in serial fluid communication between the main solution tank and the pump inlet, thus introducing the precursors into a flow of the liquid disinfectant into the pump 90.
The continuous gas monitoring system 38 includes a continuous gas monitoring device which uses a diaphragm pump to provide the gas flow received through the gas sample tube 129 to a sensor. The sensor's electrical output is sent through a sensor circuit board to a digital panel meter which processes the sensor output and produces a digital readout in Parts Per Million (PPM) of the chemical levels in the liquid disinfectant. The continuous gas monitoring system 38 compares the measured gas level to the preset alarm levels and activates alarm indicators when gas levels exceed user set levels. If low gas levels are detected, a signal is sent to the liquid disinfectant generator to generate additional chlorine dioxide. If the liquid disinfectant is low, water is added to the systems. The continuous gas monitoring system 38 further includes data logging for recording data including chemical levels, fluid level, maintaining level, and kill ratio.
The static liquid level 78a (see
A detailed view of the chemical manifold 112 is shown in
A method for treating hospital waste according to the present invention is described in
The method of the present invention may further be exercised to treat Trace Chemo and Suction Canister hospital waste. Trace Chemo is trace material left in used waste containers, tubes, needles etc. after use. Trace Chemo medical waste is considered empty waste because the chemo that was once inside of the waste containers, tubes, needles etc. is no longer inside. Because Trace Chemo waste is considered empty waste, it simply needs to be ground or burned. Because the present invention grinds the waste that is introduced to it, Trace Chemo can be processed using the method described in
Suction Canisters are filled with fluids and contents from the operating room. Because the contents inside the canister are fluids or gelled fluid, it is difficult for them to reach disinfecting temperatures. Using the method of the present invention, the Suction Canister is broken open and all of the contents inside become in direct contact with the liquid disinfectant which disinfects the contents.
While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.
The present application is a Continuation In Part of U.S. application Ser. No. 11/190,343, filed Jul. 26, 2005, for “INFECTIOUS WASTE TREATMENT” which application is incorporated herein by reference.
Number | Date | Country | |
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Parent | 11190343 | Jul 2005 | US |
Child | 11212009 | Aug 2005 | US |