Question

How is water purified on a large scale at water works ? Explain with the help of a labelled diagram. Name the substance which is added to kill germs in the drinking water supply ?

Answer 1

At water works, the process of water purification involves three steps which are:

1. Sedimentation .

2. Filtration .

3. Chlorination or Disinfection .

Explanation:

1) Sedimentation:

• The water pumped from sources such as rivers, lakes or dams is stored in large tanks or reservoirs, otherwise called as settling tanks, for a few hours.
• This allows mud, sand and other suspended particles in the water to settle down.
• Further, potash alum is added in a small quantity to help the suspended particles settle down quickly and this solid that settles at the tank’s bottom is called sediment (thus the name called sedimentation tanks). The clean water over the sediment layer is now processed.

2) Filtration:

• Layers of sand and gravel are used to filter the water from the sedimentation tank.
• However, better-quality water can be afforded if filtration is carried out through activated charcoal which is a special type of vacuum-heated charcoal with a tendency to strongly hold the impurities.

3) Chlorination:

• Chlorine gas or hypochlorite is then used to kill the germs such as certain types of bacteria and other microbes in the filtered water.
• Chlorine is highly toxic, and the process of chlorination prevents the spread of water-borne diseases such as dysentery, typhoid, cholera, etc.

Answer 2

Answer:

Explanation:

I have small answer for you.

Water is purified on a large scale at water works by different methods like sedimentation, devastation, loading, filtration and chlorination.

Chlorine is used to kill the germs in the drinking water.

Hope it helps you.