question 1) analyse the waste generated in your house in a week paragraph
Answers
Answer:
Explanation:
There are several different ways of classifying solid waste. As you have seen, one way is to classify it by where it is generated. Another way is based on whether the waste is biodegradable or not.
Biodegradable solid wastes are those thatcan be broken down (decomposed) into their constituent elements by bacteria and other micro-organisms. Food waste, manures and waste from producing crops are the main biodegradable wastes. If the decomposition process takes place in the absence of air (anaerobically), methane gas can form. Methane is a powerful greenhouse gas and can explode if enough of it accumulates and an ignition source (such as an electrical spark) is present. The decomposition may also produce offensive and irritating smells.
However, controlled anaerobic decomposition can produce biogas – a useful fuel for heating, cooking and even power generation that you learned about in Study Session 5– as well as fertilisers and soil conditioners. Waste that decomposes in the presence of an adequate air supply (aerobically) under controlled conditions can produce compost, which can be used to improve the quality of soils.
Non-biodegradable (also sometimes called inorganic) solid wastes are those thatdo not decompose by microbial action. These wastes include plastic containers, scrap metal, food and drink cans and plastic bags.
Materials in solid wastes can also be classified as combustible or non-combustible, depending on whether they will burn or not.
Depending on the inherent dangers associated with its physical and chemical properties, solid waste can be classified as either hazardous or non-hazardous. Hazardous wastespose substantial or potential threats to public health or the environment. For example, toxic, infectious and corrosive (acidic or alkaline) substances are all likely to be classed as hazardous. Non-hazardous wastes are those that do not possess hazardous characteristics, although they can still be harmful to people or the environment. (Hazardous waste is described in more detail in Study Session 10.)
Can you think of any examples of non-hazardous wastes that could be harmful?
Reveal answer
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?
Reveal answer
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 component Percentage by mass
Food wastes 43.5
Paper 9.4
Plastics 3.3
Textile 1.3
Rubber 0.7
Leather 0.2
Garden waste 11.9
Wood and charcoal 1.7
Glass 1.1
Metals 1.3
Ash and soil 20.2
Others 5.6
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.
Reveal answer
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.
Waste type Length of storage in days Effects if stored for longer
Food wastes 4 Fly breeding
Residential waste 7 Flies, land pollution
Street sweepings 7 Unsightliness
Dead animals 1 Flies, animal diseases
Ashes 14 Air pollution from dust, unsightliness
7.3.1 Chemical composition of solid wastes
Knowing the chemical composition of solid waste is very important when planning for different waste management options. Key aspects of chemical composition are:
moisture content – the percentage of water in the waste
ash content – the amount of material remaining after burning the waste
heat content – also known as calorific value, which is the amount of heat energy produced when the waste is burned.
Full analysis could also identify the different chemical elements present in the waste.
In practice, the composition of a mixture of wastes is found by separating the components and testing each different material to find out its moisture, ash content and chemical composition, and combining the values to get the overall composition of the waste.