Water Closet. Image credit rakbathware.com

Water Closet. Image credit rakbathware.com

ZIMSEC O Level Combined Science Notes: Water closet/Flush toilet

  • Is part of the water borne sewage
  • This means that wastes from the toilet are carried by water to a place where it is processed
  • This is very common in urban homes ¬†and places where there is a water supply
  • It is most suitable in places where the population is high
  • The Water Closet is complex and expensive to install and operate
Water Closet. Image credit metaefficient.com

Water Closet. Image credit metaefficient.com

  • It consists of a bowl of earthenware, plastic or fiberglass
  • This makes the seat clean and attractive and easy to clean
  • The bowl is designed so that there is a water seal (a curved/looped part in the seat)
  • The seal always contains water to prevent bad smell from the main sewer pipeline from escaping into the room
  • The seat as a lid which must closed during the flashing process to prevent splashing
  • The sewage from these Water closets/Flush toilets are disposed of in three ways:

1 Cesspits

A cesspit

A cesspit

  • Also known as the pit
  • It is made up of a single underground tank, which collects raw sewage from flush toilets
  • Water seeps through the walls of the pit into the ground
  • Bacteria in the tank break down wastes
  • The pit fills up after some time and must be emptied by waste removal companies

2 Septic Tanks

A septic tank

A septic tank

  • Is a modification of the cesspit
  • It is made up of two chambers
  • In the first chamber which is also known as the decomposition chamber
  • Anaerobic bacteria are actively involved
  • They slowly decompose the waste
  • In the second chamber the waste is sprinkled over stones,
  • Jelly forms, ciliates and aerobic bacteria are involved
  • Ciliates feed on bacteria and break down organic substances such as urea
  • When the water leaves the second tank it seeps back into the ground
  • Sludge has to be regularly removed from the first tank
  • It is often used as organic compost and manure

3. Centralised Sewage treatment works

To access more topics go to the Combined Science Notes page


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