ZIMSEC O Level Combined Science Notes: Waste disposal
- Several terms are used when dealing with waste
- Sewage-is the name given to human excrement (faeces and urine) when collected together.
- Sewage also includes kitchen waste and industrial waste
- Waste is also known as effluent
- Sewage waste is collected in a watery form the waste is carried either in solution or in suspension
- Refuse and garbage-refer to solid waste that accumulates as a result of domestic and industrial activity
- Examples include paper, tins, plastic bags, bottles etc
- Biodegradable waste-is waste that can be decomposed by bacteria and fungi.
- Examples are food leftovers, vegetables and cereals
- It is usually made up of organic substances
- Non biodegradable refuse-is refuse that cannot be acted on by bacteria/fungi.
- It includes plastics, polystyrene (e.g restaurant kaylite)
- This type of refuse is usually made up inorganic materials
- Recycling-this involves the use of waste and saves on raw materials in manufacturing
- It minimises waste and pollution
- It controls vectors such as rodents, flies and mosquitos thus helping to prevent spread of results
Methods of sewage disposal
- Sewage is an ever present form of waste
- Several methods have been devised to deal with it
- Methods include-
- Pit latrine
- Blair ventilated pit toilet
- Water closet(WC)
To access more topics go to the Combined Science Notes page
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