10.4.2  Incineration

Incineration, as opposed to open burning, is the combustion of waste material in an enclosed container with an air supply and ideally fitted with a chimney. The combustion process can be controlled to some extent so less pollution is produced and a chimney helps to reduce the impact by sending product gases upwards into the atmosphere. An incinerator of the type that may be used in large schools or hospitals is shown in Figure 10.5(a). Smaller, lower-cost incinerators may be built from bricks (Figure 10.5(b)). These can be built locally and are the type you are most likely to see.

Figure 10.5  (a) A metal incinerator with a chimney. (b) A brick incinerator is simpler and cheaper to build.

Incinerators are mostly used in Ethiopia to treat healthcare waste or waste in other institutions such as schools. They are preferable to open burning but they still generate smoke and other pollutants. They need to be operated with care to make sure they function correctly and to minimise possible pollution. Good practices in managing small incinerators include the following:

  • Make sure there is a sufficient air supply to the container where the burning takes place. Usually the air flows upwards through the chamber, so the bars that the burning waste sits on should not be blocked.
  • Most pollution is formed when the incinerator is heating up, so use firewood or clean, dry waste at the start.
  • Waste should be added to the incinerator regularly so that the temperature does not fall and cause smoke to be formed. Generally, wet waste should be added in small amounts and ideally mixed with dry waste.
  • The ash should be removed when cold and then buried. Care must be taken to avoid light ash blowing away in the wind.
  • The incinerator should be in a fenced-off area – when operating, the external surfaces will become very hot.
  • The incinerator operators should be trained adequately. They should wear protective clothing (gloves, face masks, etc.), especially when burning healthcare waste. They should have access to and use handwashing facilities at the end of each shift and before meal breaks.

10.4.1  Open burning

10.5  Types of hazardous waste