Patent Application
20240198400
The present invention pertains to the field of biotechnology, environment, and health. The invention consists of a formulation and method used for the sterilization, transformation, and final disposal or recycling of inputs, in particular personal protective equipment (PPE) exposed to SARS-CoV-2 (SARS: Severe Acute Respiratory Syndrome) that is generated in health care centers, medical offices, residential homes, industry, educational institutions, recreation centers, and public places.
As the COVID-19 pandemic spreads around the world, there is growing concern about how to manage the waste generated by suspected infected patients, by the staff caring for them, and by clinical laboratories that perform diagnostic tests. In establishments such as supermarkets, restaurants, factories, educational institutions, recreation centers, and public places, personal protective equipment is used both by the personnel providing the service and by the users and is periodically discarded and is potentially contaminated with SARS-CoV-2. In addition, people diagnosed with COVID-19 who remain at home with mild symptoms will also generate potentially infectious waste. The World Health Organization (WHO) advises that any system that exercises best practices for handling infectious waste must be capable of managing waste potentially infected with SARS-CoV-2. Specifically, waste associated with COVID-19, including PPE (Personal Protective Equipment), is not managed differently from other infectious waste.
PPE is defined as any input, equipment, apparatus, or device that is specially designed and manufactured to protect the human body, in whole or in part, from specific risks of work accidents, occupational diseases, or dangerous environments. Various types of PPE exist for different types of risks, but it generally serves to protect the head, ears, face, eyes, upper limbs, and lower limbs. The official Mexican standards in which criteria are established for the use of PPE in Mexico are: NOM-017-STPS-2008, NOM-113-STPS-2009, NOM-023-STPS-2012, and NOM-026-STPS-2008026, which are regulated by the Ministry of Labor and Social Welfare (Secretaria del Trabajo y Previsión Social).
The use of PPE by healthcare workers and the general public has increased dramatically, so establishments that provide specialized waste management services are overwhelmed. The exact viability of SARS-CoV-2 is currently not known. However, the best scientific evidence available at this time indicates that it may be up to 3 days on hard surfaces such as plastic.
In addition, outside the hospital environment, masks, disposable tissues, face coverings, PPE, and other non-biodegradable waste related to SARS-CoV-2 must be collected separately, deposited in a double bag, and labeled with the date. If there is any possibility that any PPE could be improperly and illegally reused, it must be transformed so as to eliminate its inherent morphological characteristics and thereby render it unrecognizable. Once the PPE has undergone the sterilization and transformation processes, the resulting waste can be sent for final disposal or recycling.
Since PPE is a tool for limiting the risk of contagion in health personnel involved in caring for patients who are suspected of being infected or are diagnosed with COVID-19 as well as in the general population that is potentially exposed to the SARS-CoV-2 virus, these inputs, once used, are classified as Biohazardous Waste (RPBI in Mexico).
Biohazardous wastes are those materials generated during medical care services, at funeral homes, biological companies, inter alia, which contain biohazardous agents and can cause harmful effects to health and the environment. In accordance with Official Mexican STANDARD NOM-087-ECOL-SSA1-2002, biohazardous waste must be treated by physical or chemical methods that ensure the elimination of pathogenic microorganisms and that the processed waste is unrecognizable for final disposal thereof.
The treatment of biohazardous waste is currently carried out using different methods, with the most commonly used being incineration, sterilization by autoclaving, application of microwaves, and finally sterilization or chemical disinfection. Biohazardous waste best management practices indicate that it should be treated using non-incineration methods. On account of the Persistent Organic Pollutants (POPs) produced by incineration, both the WHO (World Health Organization) and the United Nations Environment Program (UNEP) support processes for managing infectious waste that do not employ incineration. Incineration is a much less efficient process than other existing technologies, and it has a greater carbon footprint. Capturing energy from burning waste is the most polluting and expensive form of energy generation. With regard to chemical sterilization, different disinfectants such as chlorine dioxide, sodium hypochlorite, ethylene oxide, formaldehyde gas, glutaraldehyde, or peracetic acid can be used. Peracetic acid has exhibited great biocidal capacity, and the compounds are completely innocuous when released into the environment.
Peracetic acid, also called peroxyacetic acid or simply PAA, is known for its high oxidative capacity. This compound has a condensed formula of CH3COOOH and a molecular mass of 76.05 g/mol. This aggregate has a pungent odor, is clear, and is normally diluted with water when used as a sterilizing agent. The most common aqueous formulations contain peracetic acid in a concentration of between 5, 15, and 35 percent with respect to the total solution, and it is formulated in the presence of acetic acid and hydrogen peroxide; these two compounds are in chemical equilibrium and form PAA. Concentrations below 5% have been observed to have broad antimicrobial and biocidal activity, and studies exist which demonstrate the elimination of bacteria and fungi. Nevertheless, the percentage characterization that is to be employed and the effect thereof on viruses is still limited.
Due to its oxidizing capacity and rapid action, peracetic acid in dilution with hydrogen peroxide has unique advantages over other disinfectants. The environmental impact of this mixture is non-existent, since it hydrolyzes readily and very quickly (between 20 to 25 minutes at a low concentration in water) into acetic acid and oxygen. At present, this component is used in the food industry for cleaning fruit, vegetables, and meat processing rooms. However, given its great germicidal capacity against virus (spores, bacteria, and fungi), it is used for the sterilization of surgical instruments and virus culture areas in pharmaceuticals, the latter representing an advancement over discarding aldehydes as sterilants.
Finally, PAA offers the possibility of being used for the sterilization of biohazardous waste and combined with a destruction process (leaving them unrecognizable); the biohazardous waste generated by the PPE treated in this manner could be classified as unrecognizable special waste. This would provide an alternative with no environmental impact AND no risk of exposure to SARS-CoV-2 infection for personnel and the general population. Previous Solutions.
According to official Mexican standard NOM-087-ECOL-SSA1-200, the management of biohazardous waste includes different operations ranging from the identification, separation, packaging, stockpiling, collection and transport, treatment, and final disposal of the waste. Likewise, the standard indicates that biohazardous waste must be treated by physical or chemical methods that ensure the elimination of pathogenic microorganisms and transform them into unrecognizable materials. Some solutions have been described in which chemical methods are used to eliminate pathogenic microorganisms from biohazardous waste, but they do not have an integrated process for rendering it unrecognizable; indeed, there is no news of any comprehensive solution that allows for the inactivation of biohazardous waste and the destruction thereof to the point of becoming unrecognizable material while also offering the possibility of recycling.
Based on an analysis of prior art documents, inventions do exist which attempt to solve similar problems, as is the case of the invention described in document MX2011011577A of Oct. 31, 2011, which discloses a mixture in aqueous solution containing formaldehyde, ethylene oxide, and methanol for sterilizing biohazardous waste that is the subject of a management plan to eliminate the infectious characteristics thereof. However, unlike our invention, it does not propose a method for rendering the waste unrecognizable, nor does it present the option of being able to recycle the waste.
The invention detailed in document EP0442909B1, dated Oct. 14, 1988, describes an improved infectious waste treatment system in which infectious waste is broken up and converted into a liquid or liquid/sludge form and then chemically disinfected by means of a disinfectant in a precisely controlled batch process over time. The disinfection process takes place in a hermetically sealed container to ensure against the release of pathogens into the atmosphere. The process produces a non-toxic and non-infectious liquid or liquid/sludge residue that can be safely discharged into a sanitary sewer or otherwise disposed of environmentally. The peracetic acid-based chemical constituting the basis of our invention is not used in this process.
The invention described in document U.S. Pat. No. 6,096,266A of Jul. 10, 1998 describes a method for disinfecting and sterilizing materials contaminated by microbes in which contaminated materials, such as medical instruments and waste from medical laboratories or hospitals, are disinfected and sterilized using a combination of peracetic acid and ozone in a sterilization chamber. Peracetic acid is formed within the sterilization chamber by introducing liquid hydrogen peroxide and liquid acetic acid therein. Unlike our invention, the development of the disinfectant material does not require a solution generation device that includes a device and a formulation.
On the other hand, document EP0945404A2, dated Mar. 23, 1998, describes an invention in which the disinfectants according to the invention with high microbicidal activity contain up to 5% by weight of performic acid in addition to hydrogen peroxide and peracetic acid; these can be obtained by adding a source of formic acid, such as formic acid, a water-soluble salt thereof, or a lower formic acid ester, to an aqueous phase containing 5 to 50% by weight of hydrogen peroxide and 1 to 15% by weight of peracetic acid and, if a salt is added, a mineral acid as well. The preferred agents are obtained through the addition of 0.1 to 1 mol of sodium formate or formic acid per kg of the agent to be produced to an equilibrium peracetic acid containing mineral acid with 0.5 to 6% by weight of peracetic acid. That invention, although it makes use of peracetic acid, contains a different formulation from the one developed herein, so that both the application and the formulation itself are totally different from our invention, which additionally allows for the integration of a process for disposing of the infected items.
The invention described in document U.S. Pat. No. 5,520,888A dated Feb. 1, 1994, where a reactor/sterilizer for disinfecting contaminated medical and/or biological waste comprises, according to the invention, at least one grinder to reduce the size of solid waste that is to be disinfected, means for feeding waste into the grinder, a freezer or ice maker that traps sanitizing concentrations of ozone from an ozone generator in ice so that ice can be added to biomedical waste prior to a shredding step. In the disinfection method, the invention relates to treating biological and/or medical waste with ozone-containing ice by mixing the ice with the waste and allowing the ice to melt, thereby releasing ozone and exposing the waste to effective ozone concentrations in order to disinfect the waste. In preferred embodiments, the biomedical reactor/sterilizer has both a coarse shredder and a grinder. The grinder produces a slush or slurry of waste and ozone that contains ice. As the slurry temperature increases, the trapped ozone is released in a sustained manner as the ice melts over time and mixes with and disinfects the debris. This invention, although it seeks to solve the same problem, differs in that the form and proportions of the formulation described are totally different by virtue of the formulation of our invention, since it has a greater virucidal capacity due to the content of its formulation.
Based on an analysis of prior art, it can be seen that, with respect to the previously described problem of the sterilization of personal protective equipment, there are no inventions that have been developed or tested for cases of exposure to SARS-CoV-2, which is quite new, and the invention described in this document provides the virucidal and disinfectant capacity for hazardous biological waste in the same place in which the infected equipment is generated, since the infectious capacity of the virus is such that it requires immediate and effective actions to avoid spread through personal protective equipment exposed to the virus.
It is the object of the invention to provide a formulation and method for the treatment and final disposal or recycling of PPE that has been potentially contaminated or is totally contaminated by SARS-CoV-2, thereby eliminating the infectious characteristics thereof and transforming it into unrecognizable materials. This formulation and method allows for:
The characteristic details of the formulation and method used for the sterilization, transformation, and final disposal or recycling of personal protective equipment exposed to SARS-CoV-2 in the same place where it is generated are clearly described in the following description and in the appended illustrative drawings.
A closed biohazardous waste chemical grinding and washing system is recommended for carrying out this process. For this system, a three-phase electrical connection of 230 V at 60 Hz is recommended. Likewise, a cold water intake (at the temperature of the water supply intake), ¾ inch at a pressure of 3.5 to 5.5 bar, should be used. A drain outlet of at least 50 mm diameter or at least 2 inches at ground level is recommended for the wastewater outlet. The lighting can be at a normal level (domestic with natural light or 2 100-watt incandescent bulbs), an internet connection is recommended (since the equipment can be monitored remotely), and it must be installed in a ventilated place capable of providing a free space with a recommended area of 3×4 meters.
For the application of the formulation, a grinding process was developed for the treatment of the waste which includes the combination of the process and the peracetic acid-based formulation that transforms biohazardous waste into unrecognizable special waste. This process consists of grinding and chemical disinfection under controlled conditions for time and the concentration of the chemical sterilization solution, whereupon the volume of the waste is reduced by destroying the waste until it is unrecognizable and pathogens are rendered inactive. As a result of the process, leachate is obtained having characteristics that enable it to be disposed of in general drainage, as well as transformed solid waste that is free of pathogens and can be treated as special waste that can be recycled or disposed of in the manner of municipal garbage. In Mexico, the leachate can be discarded in general drainage in compliance with official Mexican standard NOM-001-SEMARNAT-1996, which establishes the maximum permissible limits of contaminants in wastewater discharges in national waters and lands. These limits are on the concentration of basic contaminants, as well as pathogenic and parasitic contaminants, acute toxicity, and true color, and heavy metals and cyanides. On the other hand, also in the case of Mexico, the transformed solid waste can be treated as special waste in compliance with official Mexican standard NOM-052-SEMARNAT-2005, which establishes the characteristics, the identification, classification, and lists of hazardous waste. This standard indicates that waste shall be considered hazardous if it presents any of the following characteristics: corrosivity, reactivity, explosivity, environmental toxicity, flammability, and bio-infectiousness. It is important to mention that the permissible limits may vary according to the application-specific regulations in a given country.
The waste destruction process consists of the following stages: loading, grinding, chemical washing, drainage, and output of solids. In the loading stage, the biohazardous waste generated as a result of exposure of the personal protective equipment to SARS-CoV-2 is introduced, and the sprinklers carry out a first rinse in the upper chamber of the equipment. During grinding, the waste is destroyed and then exposed to a chemical wash through the action of a mixture of water with peracetic acid. Finally, during drainage and output of solids, the leachate comes out through a drain valve, and the sterilized solids are removed by means of a screw conveyor. This solid waste is collected in containers for its subsequent final destination as common garbage.
In order to be able to dispose of the biohazardous waste in the manner of municipal garbage, it must not have any pathogenic microorganism that continues to be considered a biohazardous waste. Therefore, between 72,000 and 88,000 parts per million (PPM) or 72 to 88 grams per liter of peracetic acid was obtained upon producing the mixture of hydrogen peroxide, acetic acid, and sulfuric acid. These components are found in the proportions of 40-80% (hydrogen peroxide), 10-40% (acetic acid), and 1-10% (sulfuric acid), with acetic acid (CH3COOH) and hydrogen peroxide hydrogen (H2O2) reacting to form peracetic acid, and with the presence of sulfuric acid (H2SO4) stabilizing this molecule. Its stable formula is as follows:
This solution was diluted to 1 and 0.5% volume/volume with potable water. This yielded solutions of 200 to 400 ppm or 200 to 400 mg per liter of peracetic acid. These solutions were used to validate their virucidal capacity in biohazardous wastes contaminated with New Castle-type viruses.
A cell culture of HEK 293 cells (human embryonic kidney 293 cells) distributed in a 24-well plate was monitored for 96 hours. During the first 24 hours after the exposure of the supernatant liquid to the biohazardous waste, untreated and treated with the sterilizing solution, no cytopathic evidence was found, as can be seen in
On the other hand, HEPG2 and MCF7 cells exposed to leachate and solids only for HEPG2 exhibit a behavior similar to that of HEK293, with the exposed cultures not showing any signs of cytopathy, just like the negative control; this is shown in
After MTT processing,
However, the positive control has a viability of 45%, showing cell death due to the presence of the virus and the replication and proliferation thereof. In order to avoid having a low cell viability in the negative control that might affect the reading, the culture was not continued for another 24 hours. MTT was not necessary for HEPG2 and MCF7, since cell death at 96 hours was evident for both cultures in the positive control, whereas in the negative control and in the experimental wells the confluence reached exceeded 90%; this is shown in
Process Validation and Formulation with Waste with Other Microorganisms.
The bactericidal and fungicidal action was verified using five different species: Escherichia coli and Pseudomona aureginosa, representing the bacteria in the gram-negative group; Staphylococcus aureus and Bacillus subtillus, representing the bacteria in the gram-positive group, and Candida albcans as a fungus. These microorganisms were allowed to grow on nutrient media to proliferation. After 24 hours, 3 batches of waste prepared with sterile residue from needles, syringes, sheets, compresses, and cotton pads were contaminated. Samples were taken from the various proliferating suspensions, with dilutions up to 10×−6 being prepared in triplicate. Each batch was then eliminated in the system with concentrations of 0.5 and 1% volume/volume for 5 minutes, respectively (washing). At the end of each process, 3 ml of the liquid sample were neutralized with sodium hydroxide. Subsequently, each sample was taken for subsequent culturing in specific agar solutions for each microorganism; these were allowed to incubate for 24 hours. After incubation, the Colony Forming Units (CFU) were counted for quantification.
A clear elimination of pathogens from 6 Log10 to 7 Log10 was observed among all species, the cultures having been left exposed to the practical acid solution with no evidence of any colony formation. Formed colonies were observed in the positive controls, indicating the proliferation of the microorganism.
The sterilizing liquid and the grinding process show efficacy in the elimination of the New Castle virus from the biohazardous waste, and the absence of other microorganisms that might cause these wastes to be categorized as biohazards was likewise confirmed. The cultures that were inoculated with the treated and neutralized supernatant behaved like a healthy culture, whereas the control that was inoculated with the untreated supernatant fluid exhibited signs of mild (at 72 hours) to severe (94 hours) cytopathy. Likewise, the presence of other microorganisms such as bacteria and fungi was verified, demonstrating that the combination of peracetic acid and a grinding system is a binomial for the transformation of biohazardous waste to special waste which, in addition to being free of pathogens, is unrecognizable.
The formulation that was obtained as a result of all of the analyses described and yields the best results is as follows:
A chemical formulation for the treatment and final disposal or recycling of personal protective equipment (PPE) exposed to SARS-CoV-2, characterized in that it comprises:
In addition, and in conjunction with the formulation described, a crushing and grinding process is required in order to render biohazardous waste from exposure of personal protective equipment to SARS-CoV-2 unrecognizable with the option of being recycled, and it provides the appropriate physical environment for the reaction mixture with the peracetic acid-based chemical agent of the resulting formulation, said process being characterized in that it comprises:
The reaction mixture for the treatment and final disposal or recycling of PPE contaminated or potentially contaminated by SARS-CoV-2, eliminating the infectious characteristics thereof and transforming it into unrecognizable materials. This reaction mixture allows for:
The preceding description of the disclosed definitions is provided in order to enable any person skilled in the art to implement or use the present invention. Various modifications to these definitions and/or implementations will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein, but should be granted the broadest scope consistent with the following claims and the principles and novel features disclosed herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| MX/A/2020/013871 | Dec 2020 | MX | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/MX2021/050087 | 12/15/2021 | WO |
