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Newsletter and Technical Publications
<Municipal Solid Waste Management>
Sound Practices
Special wastes
1.7.2 Medical waste
Medical waste is one of the most problematic types of
wastes for a solid waste authority. When such wastes enter the MSW stream,
pathogens in the wastes pose a great hazard to the environment and to those who
come in contact with the wastes.
Waste generated within hospital premises has three main components: common
wastes, for example, administrative office waste and kitchen waste; pathogenic
or infectious wastes (these also contain sharps); and hazardous wastes (mainly
those originating in the laboratories containing toxic substances). The quantity
of the first type of waste tends to be much larger than the second and third
types.
Ideally, as recommended in the accompanying box, these three types of waste
should be separated. However, separation is possible only when there is
significant management commitment, in-depth and continuous training of
personnel, and permanent supervision to ensure that the prescribed practices are
being followed. Otherwise, there is always a risk that infectious and hazardous
materials will enter the common waste stream.
| Sound practices for managing medical waste
Sound practices for managing medical wastes are characterized by:
- source separation within the hospital, (a) that isolates
infectious and hazardous wastes from non-infectious and non-hazardous
ones, through color coding of bags or containers; (b) that source
separates and recycles the large quantities of non-infectious
cardboard, paper, plastic, and metal; (c) that source separates
compostable food and grounds wastes and directs them to a composting
facility if available; and (d) that is characterized by thorough
management monitoring;
- take-back systems, where vendors or manufacturers take back
unused or out-of-date medications for controlled disposal;
- tight inventory control over medications, to avoid wastage
due to expiration dates (really a form of waste reduction);
- piggy-back systems for nursing homes, clinics, and doctors'
offices, so that they can funnel their wastes through hospital waste
systems in the vicinity;
- treatment of infectious waste through incineration, or by
disinfection(including autoclaving, chemical reaction, microwaves,
and irradiation). In the case of incineration this may be done within
the hospital premises or in a centralized facility. An incinerator is
difficult and expensive to maintain, so it should be located in a
hospital only when the hospital is large or where it provides services
to other nearby hospitals. Otherwise, a centralized incinerator that
provides services to hospitals in one region or city is more
appropriate. In the case of disinfection, residues from these
processes should still be treated as special wastes, unless a detailed
bacteriological analysis is carried out.
- proper disposal of hospital wastes. In many developing
countries none of the above treatment systems are widely available, so
final disposal of infectious and hazardous components of the wastes is
necessary. Since in many developing countries there are no landfills
specifically designed to receive special wastes, hospital wastes need
to go to the local landfill or dump. In this case, close supervision
of the disposal process is critical in order to avoid contact with
waste pickers. Final disposal should preferably be done in a specially
designated cell, which should be covered with a layer of lime and at
least 50 cm of soil. When no other alternative is available for final
disposal, hospital wastes may be disposed of jointly with regular
wastes. In this case, however, hospital wastes should be covered
immediately by a meter thickness of ordinary MSW and always be placed
more than two meters from the edge of the deposited waste.
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