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<Municipal Solid Waste Management>

Sound Practices

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.

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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