At present, the issue of organization of medical waste disposal system and introduction of equipment-based method of disinfection in health care institutions has become particularly relevant due to changes in the requirements of the Russian environmental and health legislation. First of all, this is a result of entry into force on August 1 of the Decree of Rosprirodnadzor of July 18, 2014 No. 445 "On approval of the federal classification waste catalog", in which there is only one group containing medical waste, namely: "Wastes of neutralization of biological and medical waste." Neutralization, as is known, should provide two conditions that classical chemical disinfection of waste does not fulfill:
- Complete loss of pathogenicity of medical waste by means of equipment-based disinfection using physical methods;
- Loss of marketable appearance of medical waste.
Thus, after chemical disinfection, medical waste must be transferred to a specialized organization for neutralization. The high cost of services rendered by organizations that neutralize medical waste centrally, encourages medical institutions to organize their own sites for medical waste disposal and to equip them with special equipment. The market for waste treatment equipment is characterized by a variety of technologies, so every medical organization is able to select the most optimal model, but it requires careful preparation when forming criteria for selection of equipment that include, among others:
- Cost of equipment;
- The cost of works for preparation of premises, water supply systems, power supply, etc., in accordance with the requirements of the equipment manufacturer;
- Operational costs, including the cost of consumables, electricity, equipment growth-supporting microenvironments;
- The cost of maintenance, repair, spare parts;
- Equipment performance;
- The range of materials and products to be processed in the equipment;
- Requirements for qualification of personnel, that operates the equipment;
- Ease of use of the equipment.
Sanitary rules for medical waste management include the following methods of equipment-based disinfection of medical waste: Saturated waster steam under excessive pressure, temperature, radiation, electromagnetic radiation. However, within the framework of the conference of the parties to the Basel Convention on the Control over Transboundary Movement of Hazardous Wastes and their Disposal held in Geneva in 2002, the UN adopted the "Technical Guidelines for the Environmentally Sound Management of Biomedical and Healthcare Wastes," which included steam sterilization and dry heat sterilization. Several domestic manufacturers produce autoclaves for disinfection of medical wastes, which have high or low capacity. Efficiency of the steam sterilization and disinfection method is an undeniable generally accepted fact. Nevertheless, when making a decision on a type of autoclave for medical waste treatment, several important factors need to be addressed:
1. Purpose of autoclave
In accordance with the requirements of § 5.4 SanPiN 184.108.40.20690-10: "The physical method of disinfection of B and C class wastes ... can be used in the presence of special equipment - facilities for medical waste disinfection"
Thus, the technical documentation for the autoclave must include a statement, that it is intended for disinfection of medical waste. An attempt to use a steam sterilizer intended for processing of medical products as medical waste treatment equipment can cause not only difficulties in the work of the operating personnel (inconvenience of loading-unloading operations, lack of special loading baskets for wastes and other factors described below), but also some objections from the supervisory authorities.
2. Efficiency of decontamination process using saturated water vapor
1). Vapor permeability of packaging materials
The main factor affecting an effectiveness of steam disinfection/sterilization of objects is vapor permeability of packaging materials, since saturated water vapor exerts its effect only when it comes into direct contact with the surface being disinfected. The regulatory documentation includes the following requirements for packaging used for steam disinfection:
- item 220.127.116.11 GOST ISO 11607-2011: "The compatibility of the material with respect to the sterilization process should confirm that the packaging is sufficiently permeable to all physical and chemical agents that affect the effectiveness of the particular sterilization method and the sterilization process does not impair the physical properties of the material over time."
- Clause 18.104.22.168 of the Guidelines MU 3.1.2313-08: "When using this method of decontamination, the bodies and pistons of syringes should be placed in a special, vapor-permeable single-use package that is resistant to high temperatures and intended for sterilization of medical devices."
In practice, when autoclaved, the medical waste is placed in polypropylene bags that withstand the high temperatures, but are not vapor permeable. Therefore, there are recommendations not to close the package completely, leaving a small hole in its neck in order to provide a contact of the steam with the medical waste inside. However, this operation can not be standardized and contradicts the requirements of sanitary regulations indicating a necessity to tie or close the package at the end of collection and prohibit any movement of waste outside of the unit in open containers (paragraph 4.13 SanPiN 22.214.171.12490-10).
In some cases, the equipment manufacturer recommends to place the medical wastes packed in a normal polyethylene bag into an open, heat-resistant polypropylene bag. In the process of steam processing, a gradual destruction of the polyethylene bag and a contact of the steam with the medical waste occur. However, in this case, the steam contact occurs only through the open neck of the bag, and most of the surfaces "hinder" the disinfection process , since it does not possess the vapor permeability property. Thus, at the moment there are no proposals for packages intended for collection and decontamination of medical waste that meet simultaneously the requirements for vapor permeability, heat resistance, moisture resistance and leak tightness. Even more questions arise when autoclaving containers with sharp instruments closed with a tightly fitting lid, which prevents spontaneous opening: The steam is unable to fully heat the entire volume of such container containing a significant amount of air.
The most effective and safe epidemiologic solution of the above-mentioned problems related to removal of air from the load and providing a direct contact of saturated water vapor with all surfaces of medical waste is preliminary shredding of wastes in the working chamber of the autoclave, which is provided by all western manufacturers of similar equipment.
2). Efficiency of air removing from the working chamber and the load
Packages for medical wastes transferred for disinfection are characterized by voluminousness, heterogeneity of morphological composition and loose packing of materials, high specific gravity of porous products and products with cavities, which leads to formation of significant number of air pockets inside the load with medical waste. The autoclave for disinfection of medical waste must guarantee efficient removal of air from the entire volume of the load by repeated pre-evacuation, otherwise it is necessary to significantly increase the duration of the sterilization cycle.
3. Sanitary-epidemiological and environmental safety of emissions and effluents
When choosing an autoclave for medical waste treatment, it is necessary to pay attention to the presence of filters and other devices that ensure removal of the condensate and air from the microbiological contaminations, otherwise the equipment will be potentially hazardous for personnel and will contribute to spread of the infectious disease.
4. Other factors, which influence selection of autoclave for disinfection of medical wastes:
- For their long-term correct operation without breakdowns the autoclaves require connection to a sewerage system, it is necessary to ensure the proper quality of the supply water, which may require organization of filtration and water treatment systems.
- Autoclaves operate at elevated pressure, and therefore require approval of the project premises, special training for the operators.
- Exposure to saturated steam does not change the appearance of the medical waste, so the equipment must be equipped with either knives built in the working chamber or with separate devices for grinding the pressing of the wastes after the treatment.
Equipment, which principle of action is based on treatment of waste with dry hot air (at temperatures above 160°C), also requires manufacturers to address a number of issues, in particular:
- Development of medical waste packaging materials, resistant to high temperatures:
Polyethylene bags start to deform at temperatures over 100°C, polypropylene bags - at 140°C; the absence of heat-resistant packaging leads to baking of waste on the wall of the working chamber, the formation of carbon deposits, which is extremely difficult to clean.
- Providing uniform and rapid warm-up of the entire volume of loaded medical waste.
"Megatekhnika" LLC has solved the above-mentioned tasks at production of the "SAMot" medical waste decontamination and disinfection unit: Medical waste, collected in polyethylene bags, are placed in special heat-resistant bags that withstand heating up to 215°C. Heat-resistant bags with an open neck are in turn placed in the loading baskets located in the working chamber. "SAMot" system provides disinfection of class B and C medical wastes in 200°C/30 min mode. The load is heated from all the sides by the heat transfer:
- from heated walls and the bottom of the working chamber;
- from the air distributor located in the center of the working chamber;
- from hot air supplied by the fans from the distributor directly to the medical waste through the maximally wide neck of the bag (forced convection);
- from the already heated medical waste located in the outer layer of the load (natural convection).
Thus, a quick heating of the medical waste load is achieved: Total cycle time on the average makes 60-70 minutes with the load volume 85 to 420 liters (depending on the model).
During disinfection there is a simultaneous change in appearance of medical wastes by sintering (forming a single waste mass). The stage of multistage filtration of air cooling from the working chamber completes the cycle of medical waste treatment in the "SAMot" system. At the same time, air from the working chamber passes through the developed system of filters, which provides elimination of dust particles, aerosols, gaseous contaminants, elimination of odors.
"SAMot" system, which has recently entered the market of medical waste treatment equipment, has already established itself as an effective equipment by the domestic manufacturer, since it has the following advantages:
- High performance:
One disinfector-destructor "SAMot" is able to meet the requirements of 1300-1500 bed hospital.
- The cost of equipment is 2-3 times lower than that of autoclaves for medical waste with similar productivity.
- Complete destruction of infectious origin and change in appearance of medical waste in one device:
In order to change the appearance of the waste there is no need for additional equipment - shredders or presses, while at the same time "SAMot" system itself does not contain any cutting elements that often fail, which reduces the costs of maintenance and repair.
SAMot system is easy to use: you need only one button to switch it on. Wide loading hatch, diameter 600 mm - 1000 mm so you can place large packages inside the working chamber. In order to operate the equipment you don't need any specialized training for the operating personnel.
- Compactness of the "SAMot" system makes it possible to install several pieces of equipment in the same room.
- "SAMot" disinfector-destructor does not require any connection to sewerage, filtration or water treatment systems, so it is possible to save considerable amount of money in preparing the premises for installation of the equipment.
- The "SAMot" system is equipped with in-process monitoring means:
- chemical indicators that change color after successful duty cycle - they can be used in every cycle.
- biological indicators containing the Bacillus subtilis BKM-B-911 microorganism resistant to dry hot air.
An opportunity of comprehensive control increases the reliability of the medical waste neutralization process in the "SAMot" system.
- Ecological and epidemiological safety of treated waste:
Pursuant to cl. 2.2. SanPiN 126.96.36.19990-10 B and C class waste products processed in the disinfectant destructor "SАМот" can be accumulated, temporarily stored, transported, destroyed and disposed together with class A wastes.
- The warranty period for the disinfector-destructor "SAMot" is 24 months.
Thus, users of the "SAMot" system will receive a simple and effective technology for disinfection and changing the appearance of medical waste, including not only the equipment, but the entire range of necessary consumables by the Russian manufacturer, "Megatekhnika" LLC (Saint Petersburg), that is also an important factor in the existing economic situation.