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��e-CONTENT �CLASS-VII SUB: SCIENCE �Chapter-18

WASTE WATER STORY

Prepared By: –Narayan Kadam.(TGT.SCI.)

JNV VALSAD (GUJ.)

NAVODAYA VIDYALAYA SAMITI NOIDA.

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Learning Outcomes/Objectives

Wastewater story guides the students to become a responsible citizen.
Students will learn about sanitation, ways of sewage disposal and sanitation at public places.
Students will understand their role in keeping the environment clean and healthy.
They will receive guidance to maintain good sanitation.
Students will learn the importance of water.

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Contents

1. What is waste water? waste water could be reused?

2. Diffrentiate between dirty water and clear water.

3. Sources of waste water.

4. Importance of World Water Day.

5. Sewage, Sewar, Sewarage.

6. Impurities in sewage and treatment on sewage(WWTP-Wastewater treatment plant)

7. How to become an active citizen?

8. Better house keeping practices.

9. Sanitation –domestic and public places.

10. Diseases, and control.

11. Conclusion

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Waste Water

What is wastewater ?

Water contaminated with harmful and undesirable substances is called wastewater.

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Water, our lifeline
Water for life

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Sources of waste water.

Sewage

Sewage, is wastewater that is produced by homes, industries, hospitals and other sources. It is a liquid waste with suspended and dissolved impurities.

Sewer

An underground conduit for carrying off drainage water and waste matter.

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Sewerage

Sewerage is the infrastructure that conveys sewage or surface runoff using sewers. Transport system that carries sewage from point of production to the point of disposal.

Manhole

A small covered opening in a paved area allowing access beneath, especially one leading to a sewer.

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Contaminants of sewage water

Organic impurities	Inorganic impurities	Nutrients	Bacteria	Other microbes
Human faeces, animal waste, oil, urea(urine), pesticides, fruit and vegetable waste etc.	Nitrates, phosphates, metals.	Phosphorus, nitrogen	Vibrio cholera (which causes cholera), salmonella paratyphi (which causes typhoid)	Protozones - which causes dysentery

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Water Freshens Up-�An eventful journey.�� Activity.�

Mixed impurities, kept in sunlight for 2 days before treatment.

After aeration, air bubbles generate bacteria which eat organic waste and reduce the smell

Filtration of water after aeration

Add few drops of chlorine solution.

Now it's clear water

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Waste water treatment plant

Treatment of waste water involves physical, chemical and biological processes.

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Bar Screen

�Large objects like rags, sticks, cans, plastic packets, napkins etc. are removed.

Grit and sand removal tank

�Speed of the incoming waste water is decreased to allow sand, grit and pebbles to settle down

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Sedimentation tank
In this step, water is allowed to settle in a large tank which is sloped towards the middle. Solids like faeces settle at the bottom are removed with scraper. This is called sludge. Floatable wastes like oil and grease are removed by skimmer.

Aeration tank�Air is pumped in the clarified water to help aerobic bacteria to grow, which consumes human waste, food waste, soaps and other unwanted matter. After several hours the suspended microbes settle at bottom i.e., activated sludge. Water is removed from the top.

Activated sludge (97% water)
Water is removed using sand drying beds or machines.
Dried sludge is used as manure for soil.

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Waste water treatment plant

(Flowchart)

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Become an active citizen�

Eucalyptus plants

�It has been suggested that we should plant eucalyptus trees all along sewage ponds. These trees absorbs all surplus waste water rapidly and release pure water vapor into the atmosphere.

Our responsibility as a citizen

�Inform sewage leakage, open drains, overflow drains, unhygienic and unsanitary conditions witnessed at any place to municipality or gram panchayat.

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Better housekeeping practices�

Should not throw oil and fats in the drains
Avoid throwing chemicals like paints, solvents, insecticides, � medicines etc. because it may kill microbes that help to purify water.
Avoid throwing used tea leaves, solid food remains, soft toys, cotton, sanitary towels etc.

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Human excreta is treated by earthworms.
Low water use toilet for safe processing of human waste.
The operation of the toilet is very simple and hygienic.
Human excreta is completely converted into vermi cakes. A resource much needed for soil.

Vermi-processing toilets

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Sanitation: domestic and public

Domestic hygiene-�- Washing hands and bathing regularly�- Laundering
Public/community hygiene�- Market places and fairs�- Railway stations�- Airports�- Bus depots�- Hospitals�

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Low cost onsite sewage disposal systems. Eg- Septic tanks, chemical toilets, composting pits.
Septic tanks are suitable for places where there is no sewerage system, for hospitals, isolated buildings and cluster of 4-5 houses.
On-site human waste disposal technology: no scavenging required. Excreta from toilet seats flow through covered drains into biogas plant.

Alternative arrangement for sewage disposal

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Diseases and control

Causes of diseases:�- Consumption of contaminated water and food.�- Defecation in open
Diseases:�- Cholera, typhoid, polio, meningitis, hepatitis and � dysentery��Control:�- Swachh bharat �- proper waste disposal��

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Conclusion�

Our role is to keep our environment clean and healthy. It's our responsibility to keep water resources clean and adopt good sanitation practices.
Biogas (which is a source of energy) can be generated with the help of the sludge that is produced in WWTP.
By adopting good sanitation practices we can keep our environment pollution free and clean.