Most wastes in hospitals and medical clinics are non-hazardous general waste and non-infectious waste generated while treating patients.
Categories of hospital medical waste as classified by the World Health Organization (WHO) are infectious waste, pharmaceutical waste, waste with a high content of heavy metals, pressurised containers, sharps, highly infectious waste, genotoxic/cytotoxic waste and radioactive waste. The last three categories are considered to be highly hazardous and therefore require special attention.
Disposal Methods
Incineration is generally considered the preferred technology for some, if not all, medical wastes. On-site incinerators operating on a batch basis or regional incinerators operating on a continuous basis is considered as the appropriate technology. The cost of meeting stringent air pollution control emission standards being high, many developed countries are taking steps to steam, sterilise, irradiate, chemically disinfect or gas/vapour sterilize some of the medical wastes.
Biological waste must be incinerated, autoclaved or treated by other approved methods. Liquid or soluble semi-solid wastes must be discarded into a sewage treatment system that provides secondary treatment or into a septic tank system.
Pathological waste should be destroyed by incineration under high heat (i.e., over 900oC with an afterburner temperature at over 800oC). Development of a regional medical waste facility is required to reach these temperatures and have adequate afterburning and pollution control. Smaller individual hospital or clinic incinerators may not be able to reach these temperatures and afterburning retention periods. Volatilised metals (such as arsenic, mercury, lead) and dioxins and furans could result from inadequate burning temperatures and retention periods.
Other procedures to consider may include chemical disinfection or sterilisation (i.e., irradiation, microwave, autoclave, or hydroclave) followed by secure landfill disposal of residuals. Following complete disinfection, some wastes may be recycled. For example, recycling by specialised contractors is sometimes arranged after disinfection of thick plastics, such as intravenous bags, tubs and syringes.
Laboratory chemical wastes need to be source segregated according to their recycling potential and compatibility; and those, which are non-recyclable, may require stabilisation, neutralisation, encapsulation or incineration.
Hospital wastewater treatment sludge requires treatment like anaerobic digestion, composting and incineration, which raises temperatures to levels that destroy pathogenic microorganisms.
Sharps must be incinerated or autoclaved. They may be taken without other treatment to a landfill in a rigid, puncture-resistant leak-proof container, as long as the container is segregated from other wastes, is transported without compaction and is placed in a segregated area of the landfill.
Pharmaceutical wastes require destruction, secure land disposal or return to the manufacturer for destruction through chemical or incineration methods.
Radioactive wastes typically include isotopes such as technetium 99, gallium 67, iodine 125, iodine 131, cesium 137, iridium 192, thallium 201, and thallium 204. These wastes are seldom present in low-income and middle-income developing countries, because the hospitals do not have the equipment and technology to generate these wastes. If generated, these wastes should be stored safely until the radioactivity has declined to acceptable levels and then disposed with general refuse to sanitary landfill.
Mehul Pandya Senior Sector Manager-Healthcare, JohnsonDiversey India
