7.3  Composition of residential solid waste

The composition of solid waste means the different types of waste material that it consists of and their characteristics. As an urban WASH worker you may need to understand the factors that affect the composition of solid waste in your area. These factors include the season of the year, the habits or culture of the community, people’s educational or economic status and the geographical location.

  • Why do you think that the composition of waste produced by households might change at different times of year?

  • Some possible answers are:

    • Different foods are available at different times of year, so the amount of waste from preparing food (vegetable trimmings and so on) and its composition will change.
    • Wastes tend to be wetter during rainy seasons.
    • There may be more food waste produced during festival times and less produced when people are fasting.

Returning to the Bahir Dar survey mentioned earlier, Table 7.1 shows the major components of municipal solid wastes generated in Bahir Dar according to the 2010 study.

Table 7.1  Composition of municipal solid waste in Bahir Dar. (Forum for Environment/UNEP, 2010)

Solid waste componentPercentage by mass
Food wastes43.5
Garden waste11.9
Wood and charcoal1.7
Ash and soil20.2
Total 100
  • Figure 7.3 shows a bin containing solid waste from a kitchen. Using the types of wastes included in Table 7.1, list the types that you can identify in the bin in Figure 7.3.

  • The waste in the bin includes paper, a plastic bag (which may contain other materials), a plastic food pot, metal foil (the yogurt pot lid) and food waste.

Figure 7.3  Waste from an Ethiopian kitchen.

The composition of solid waste affects the length of time that it can be safely stored before disposal. If kept uncovered for too long, some waste will become a health hazard or cause some other nuisance. The recommended time for storage is shown in Table 7.2 for typical Ethiopian conditions where the waste is stored at normal temperatures in a container that is not sealed.

Table 7.2  Length of storage in days for different types of solid wastes and the potential problems from storing the waste for too long. (Tadesse, 2004)

Waste typeLength of storage in daysEffects if stored for longer
Food wastes 4Fly breeding
Residential waste7Flies, land pollution
Street sweepings7Unsightliness
Dead animals1Flies, animal diseases
Ashes14Air pollution from dust, unsightliness

7.2  Classification of solid wastes

7.3.1 Chemical composition of solid wastes