During The Purification Of Water For City Supply The Raw Water From The River Lake Is Allowed To Stand Undisturbed In Large Tanks. What Happened Here ? And What Are Other Stepscan Be Formed To Get Pure Water For Daily Use?
Answers
Answer:
sedimentation
Explanation:
the tank allow the sand to get down
Purification of water on a large scale!
Water is purified on a large scale in establishments that are known as waterworks. Usually, the following steps are taken to purify water.
1. Sedimentation:
Water pumped from the source (river, lake or dam) is allowed to stand in large tanks, called settling tanks, for a few hours. Mud, sand and other suspended particles settle down. The addition of a small quantity of potash alum (K2SO4 . A12(SO4)3 . 24H2O) helps the suspended particles to settle down quickly. The solid that settles at the bottom of the tank is called sediment. That is why these tanks are also called sedimentation tanks. The water over the sediment layer is more or less clean.
2. Filtration:
The water from the sedimentation tank is filtered through layers of sand and gravel. Filtration is also done through activated charcoal, which affords better-quality water. Activated charcoal is a special type of charcoal made by heating ordinary charcoal in vacuum. This charcoal holds the impurities strongly.
3. Chlorination:
The filtered water is then treated with chlorine gas, which kills germs. You can see for yourself that alum helps the suspended particles of water to settle down quickly.