Exercises

1. Fill in the blanks:
(a) Cleaning of water is a process of removing pollutants_.
(b) Wastewater released by houses is called sewage.
(c) Dried sludge is used as manure.
(d) Drains get blocked by cooking oils and fats.

2. What is sewage? Explain why it is harmful to discharge untreated
sewage into rivers or seas.
Sewage is wastewater released by homes, industries, hospitals, offices,
and other uses.
It is harmful to discharge untreated sewage into rivers or seas because
● Untreated sewage can cause harm to aquatic life.
● Most of the wild animals in the forest depend on sources like rivers
and ponds for water discharge of impurities into them can cause
harm to wildlife also.

3. Why should oils and fats be not released in the drain? Explain.
Because it leads to hardening and blocks the pipes. In open-drain fats
and oils clog the soil pore which reduces the effectiveness in filtering
water by the soil. So oils and fats should be disposed of properly into a
dustbin.

4. Describe the steps involved in getting clarified water from wastewater.
The steps involved in getting clarified water from wastewater are :
Step 1: Large objects like rags, sticks, cans, plastic packets, napkins are removed.
Step 2: Water then goes to a grit and sand removal tank. The speed of the incoming
wastewater is decreased to allow sand, grit, and pebbles to settle down.
Step 3: (i)water is allowed to settle large sloped tanks towards the middle for settlement of
solid-like feces at the bottom which is then removed with a scrapper ( sludge).
(ii) the skimmer removes the floatable solids like oil and grease. Water so cleared is called
clarified water

5. What is sludge? Explain how it is treated.
During the process of wastewater treatment, the water is allowed to
settle in a large tank sloped towards the middle. Solid wastes like faces
settle down at the bottom of the tank. these are then removed with the
help of a scraper. This is called sludge.
Treatment :
Floatable solids like oil and grease are removed from the skimmer. It is
then transferred into a separate tank where it is decomposed by the
anaerobic bacteria. The Biogas produced in the process can be used as
fuel or can be used to produced electricity.

6. Untreated human excreta is a health hazard. Explain.
Untreated human excreta is a health hazard because it causes soil and
water pollution.
Water: Groundwater is a source of water for wells, tube wells, springs, and many rivers.
It also leads to many diseases.

7. Name two chemicals used to disinfect water.
Chlorine and Ozone are the two chemicals used to disinfect water.

8. Explain the function of bar screens in a wastewater treatment plant
Bar screen removes large objects like rags, sticks, cans, plastic packets
and napkins, etc..

9. Explain the relationship between sanitation and disease.
Poor sanitation and contaminated drinking water is the cause of a large
number of diseases.

A very large fraction of our people defecate in the open, on dry
riverbeds, on railway tracks, near fields, and many a time directly in
water.
Poor sanitation causes:
1.water pollution (both surface and groundwater).
2. soil pollution
3. it leads to many water brown diseases like cholera, typhoid, polio,
meningitis, hepatitis, and dysentery.

10. Outline your role as an active citizen in relation to sanitation.
Being an active citizen we can
1. Approach the municipality or the gram panchayat.
2. Insist that the open drains be covered.
3. If the sewage of any particular house makes the neighborhood dirty, you should request
them to be more considerate about others’ health.
4. We all have a role to play in keeping our environment clean and healthy. Adopting good
sanitation practices should be our way of life.
5. A lot can be done if people work together. There is great power in collective action.

11. Here is a crossword puzzle: Good luck!