The growing quantum of medical wastes (also known as biomedical wastes or healthcare wastes) is posing significant public health and environmental challenges across the world. The situation is alarming in developing countries due to improper disposal methods, insufficient physical resources, and lack of research on medical waste management. The key technologies for medical waste treatment include steam sterilization, advanced steam sterilization, microwave treatment, dry heat sterilization, alkaline hydrolysis, biological treatment and plasma gasification.
Steam sterilization (or autoclaving) is the most common alternative treatment method. Steam sterilization is done in closed chambers where both heat and pressure are applied over a period of time to destroy all microorganisms that may be present in healthcare waste before landfill disposal. Among alternative systems, autoclaving has the lowest capital costs and can be used to process up to 90% of medical waste, and are easily scaled to meet the needs of any medical organization.
Advanced autoclaves or advanced steam treatment technologies combine steam treatment with vacuuming, internal mixing or fragmentation, internal shredding, drying, and compaction thus leading to as much as 90% volume reduction. Advanced steam systems have higher capital costs than standard autoclaves of the same size. However, rigorous waste segregation is important in steam sterilization in order to exclude hazardous materials and chemicals from the waste stream.
Microwave treatment is a promising technology in which treatment occurs through the introduction of moist heat and steam generated by microwave energy. A typical microwave treatment system consists of a treatment chamber into which microwave energy is directed from a microwave generator. Microwave units generally have higher capital costs than autoclaves, and can be batch or semi-continuous.
Chemical processes use disinfectants, such as lime or peracetic acid, to treat waste. Alkaline digestion is a unique type of chemical process that uses heated alkali to digest tissues, pathological waste, anatomical parts, or animal carcasses in heated stainless steel tanks. Biological processes, like composting and vermicomposting, can also be used to degrade organic matter in healthcare waste such as kitchen/food waste and placenta.
Plasma gasification is an emerging and promising solution for medical waste management. A plasma gasifier is an oxygen-starved reactor that is operated at the very high temperatures which results in the breakdown of wastes into hydrogen, carbon monoxide, water etc. The main product of a plasma gasification plant is energy-rich syngas which can be converted into heat, electricity and liquids fuels. Inorganic components in medical wastes, like metals and glass, get converted into a glassy aggregate.
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