Newsletter and Technical Publications
<Municipal Solid Waste Management>
Sound Practices
Incineration
1.5.1 Introduction
The primary benefit of MSW incineration is a
substantial reduction of the weight (up to 75%) and volume (up to 90%) of solid
waste, which can be valuable if landfill space is scarce. The generation of
revenues from energy production, known as waste-to-energy incineration, can also
partially offset the cost of incineration, although there are typically less
expensive forms of energy production available. Incineration breaks down some
hazardous, non-metallic organic wastes and destroys bacteria and viruses, which
is the main benefit of incineration of medical wastes. (Incineration of medical
wastes is discussed briefly in the Special wastes part of the Sound Practices
section.) In considering the MSW incineration option, decision makers must weigh
the benefits of incineration against the significant capital and operating
costs, potential environmental impacts, and technical difficulties of operating
an incinerator.
MSW incineration is typically only cost-effective in regions where land
suitable for landfilling is scarce. Such landfill scarcity can arise due to
geographical constraints, as with a highly urbanized region or island, or
environmental conditions, as in regions where the water table is high.
Jurisdictional and political boundaries can also constrain the size and number
of sites available for landfilling, thereby increasing the attractiveness of
incineration.
At the present time, there are factors that make incineration difficult or
inadvisable in many developing countries. Notable among them are the high
capital and operating costs involved, relative to national income levels, and
the comparatively low cost of sanitary landfilling. As detailed below, it is
difficult to incinerate wastes in many developing countries due to their high
moisture and low energy content. In addition, the technical infrastructure
required to maintain incineration facilities, including their pollution control
equipment, is generally not currently available in developing countries. The
elements of infrastructure that are often lacking include highly trained
personnel, constant availability of technologically advanced testing and repair
facilities, and a well functioning system for ensuring the quick availability of
spare parts. However, many countries are currently improving their technical
capabilities, so some of these problems may be less of a factor in the future.
| Factors affecting technology choice
MSW incineration can constitute a sound practice only in situations
where most or all of the following conditions hold:
- suitable landfill space is scarce, making incineration a
cost-effective alternative;
- the necessary environmental controls are properly installed and
maintained;
- the facility is properly sized and sited to fit well with other
components of the MSWM system;
- the material to be burned is combustible and has sufficient energy
content; and
- there are nearby energy markets.
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For environmentally sound incineration, air pollution control equipment must
be serviced regularly by highly specialized personnel. Monitoring equipment is
costly and requires aggressive maintenance and servicing by trained technicians.
In summary, when incineration is done in a manner that has low adverse health
and environmental impacts it is expensive. When it is done poorly (with low
financial costs) it can be expensive in terms of human health and environmental
impacts.
Given these conditions, incineration with or without energy recovery does not
appear to be a sound option for most situations encountered in developing
countries. It is not surprising, therefore, that there are few examples of
successful MSW incineration in such countries and several examples of premature
attempts to adopt this technology. For example, Buenos Aires, Mexico City, New
Delhi, and S‹o Paulo, among other cities, have had to shut down incinerators
due to high costs or environmental considerations.
It is important to recognize, however, that some developing countries do have
considerable technical expertise and, increasingly, the capital necessary to
install and operate incinerators. It may be possible, therefore, to introduce
this technology into such countries in an environmentally sound manner if there
is a serious commitment to maintaining the relatively expensive environmental
controls that incineration requires. Particularly in the case of very large or
low-lying cities where landfill space is scarce even in the surrounding area, it
may be necessary to consider incineration. Even in these cases, however, wet
wastes and wastes with low calorific value, if predominant, will make
incineration difficult or perhaps impossible without the use of supplementary
fuel. As real per-capita GNP rises, the mix of wastes generated is likely to
become more combustible, just as financial and technical capacities are
improving. This confluence of factors would make incineration more possible.
Some countries that have emerged from developing country status are
definitely able to incinerate their wastes. Singapore operates three MSW
incinerators that handle about 90% of the MSW generated. South Korea also has
many incinerators. MSW incineration is also being considered in Bangkok, where
three incineration plants located at landfills are already operating, primarily
to incinerate hazardous wastes.
Pilot projects supported by bilateral or international aid, or joint ventures
with firms from industrialized countries, may make such initiatives more
feasible, since they can make foreign capital and technology training available
in developing countries. For example, a waste-to-energy incinerator has recently
been constructed in Tanzania with assistance from a foreign government. However,
even in cases where the initial capital costs of an incinerator are partly or
wholly subsidized by an outside country or organization, the costs of properly
operating and maintaining an incinerator and its environmental controls will
still be unattractive in most developing country situations. In cases where
there is very substantial local capacity to reliably and continuously operate
technically demanding equipment, incineration could make sense if all of the
other criteria for sound incineration are also met.
It should also be noted that municipal managers, in making decisions about
MSWM facilities, have sometimes faced considerable pressure from private vendors
of incinerators, as well as attractive-looking solutions offered by bilateral or
international development agencies. It is critical that decisions about the
adoption of incineration be made with the utmost care and that all of the pros
and cons of incinerators be considered carefully before any decision is made.
Outside resources can be valuable here if they provide sound advice about making
choices in the face of many pressures and much conflicting information.
The situation is different in the most urbanized regions of many
industrialized countries where land prices are often high, landfill space is
limited, and environmental controls are more strictly applied. Because of these
circumstances these countries have considerable experience with incineration.
Many regions in Europe, Japan, and the United States incinerate a significant
portion of their MSW in a manner that meets current environmental standards.
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