Give reasons for the following:

Q1. Why should chemicals like paints, solvents and medicines should not be thrown down the drain?

Ans:

Chemicals like paints, solvents and medicines should not be thrown down the drain because:

1. These chemicals may kill microbes that help purify water.
2. They can contaminate water, leading to environmental pollution.

Q2. Why should solid waste like used tea leaves, solid food remains, etc. should not be thrown down the drain?

Ans:

Tea leaves, solid food remains, etc. should not be thrown down the drain because:

1. These wastes choke the drains, causing blockages.
2. They restrict the free flow of oxygen, hampering the degradation process.

Q3. Why is speed of water reduced in a grit and sand removal tank?

Ans:

1. A grit & sand removal tank is used to separate sand, rocks, stones, etc. from the wastewater.
2. Speed of water reduced in a grit and sand removal tank to allow sand, grit and pebbles to settle down.

Q4. Eucalyptus trees are planted all along sewage ponds. Give reason.

Ans:

Eucalyptus trees are planted all along sewage ponds because:

1. They absorb all surplus wastewater rapidly.
2. Then they release pure water vapour into the atmosphere.

Q5. Why should open drains be covered?

Ans:

Open drains should be covered because:

1. They cause offensive smell & are disguisting to see.
2. During rainy season, the drains start overflowing & create mud pools on the roads.
3. They are very unhygienic due to which flies, mosquitoes & other insects breed in it.

Q6. Why should we avoid throwing waste in drains?

Ans:

We should avoid throwing waste in drains becaue:

1. It causes blockages and flooding of drains.
2. It leads to pollution of water bodies.
3. Proper waste disposal is important for sanitation.

Answer the following questions in short:

Q1. What are the components of sewage?

Ans:

Sewage is a complex liquid waste containing suspended solids, organic & inorganic impurities, nutrients, saprophytes & disease-causing bacteria & other microbes.

Q2. What is wastewater?

Ans:

Wastewater is the black–brown dirty water which is rich in lather, mixed with oil, that goes down the drains from sinks, showers, toilets, laundries, etc.

Q3. What it means by cleaning of water?

Ans:

Cleaning of water is a process of removing pollutants from the wastewater at a wastewater treatment plant before it enters a water body or is reused. 

Q4. What is the function of the skimmer in a wastewater treatment plant?

Ans:

Skimmer removes the floatable solid & liquid waste like oil & grease from the wastewater.

Q5. How is biogas formed from sludge?

Ans:

Sludge is decomposed by the anaerobic bacteria in a separate tank to form biogas.

Q6. How water is removed from activated sludge?

Ans:

Activated sludge contains 97% water which is removed by sand drying beds or machines.

Q7. What is a sewerage?

Ans:

Sewerage is a network of big & small pipes called sewers which act like a transport system that carries sewage from the point where it is produced to the point of disposal, i.e. treatment plant.

Q8. What is a vermi-processing toilet?

Ans:

Vermi-processing toilet is a toilet where human excreta is treated by earthworms & converted to vermi cakes which are used as manure.

Q9: What is the cause of large number of disease?

Ans:

Poor sanitation and contaminated drinking water is the cause of a large number of diseases.

Q10. What are the onsite methods of sewage disposal?

Ans:

The onsite methods of sewage disposal are septic tanks, chemical toilets or composting pits. 

Q11. Septic tanks are suitable for which places?

Ans:

Septic tanks are suitable for places where there is no sewerage system, for hospitals, isolated buildings or a cluster of 4 to 5 houses.

Q12. How Indian government is contributing towards sanitation?

Ans:

In the year 2016, the Government of India has initiated, “Swachh Bharat” mission under which a lot of drives for proper sewage disposal and providing toilets for everyone has been started.

Q13. What are common sources of sewage?

Ans:

The common sources of sewage are housholds, industries, hospitals, offices & other users.

Q14. List the water borne disease.

Ans:

The water borne disease are cholera, typhoid, polio, meningitis, hepatitis and dysentery.

Answer the following questions:

Q1. Why is untreated sewage harmful?

Ans:

When sewage is untreated:

1. It can causes & spreads water borne diseases like cholera, dysentery & typhoid.
2. Untreated sewage pollutes & contaminates rivers, lakes, and other water bodies, making them unsafe for use. 
3. It can harm aquatic life in rivers and oceans.
4. It can degrade soil quality & harm the plants.

Q2. What are the main components of sewage in detail?

Ans:

Sewage is a liquid waste which consists of:

1. Organic impurities include human, fruit, vegetable & animal waste, urea, pesticides, etc.
2. Inorganic impurities consist of nitrates, phosphates & metals.
3. Nutrients like nitrogen and phosphorus.
4. Bacteria that cause water borne diseases like typhoid, cholera, etc.
5. Other microbes like protozones that cause dysentery.

Q3. How does the process of sedimentation work in sewage treatment plant?

Ans:

1. Sedimentation is the process in which heavier waste particles in water settle at the bottom of a tank.
2. In the grit & sand removal tank, grit, sand & pebbles settle down.
3. Then in water clarifier tank, solids wastes like faeces settle at the bottom of the tank.
4. As the waste settles at the bottom of the tank, it can be separated from the wastewater to obtain clarified water.

Q4. How is clarified water further treated in wastewater treatment plant?

Ans:

1. Air is pumped into the clarified water through aerator.
2. This helps growth of aerobic bacteria which consume human waste, food waste, soaps & other unwanted matter still remaining in clarified water. 
3. The suspended microbes settle at the bottom of the tank as activated sludge.
4. The water is removed from the top & can be discharged into water bodies.

Q5. What are the benefits of vermi-processing toilets?

Ans:

Benefits of vermi-processing toilets are:

1. Human excreta is treated by earthworms & converted to vermi cakes that are used as manures for plants.
2. It is a low water-use toilet for safe processing of human waste.
3.  It is very simple, hygienic & environment friendly.

Q6. How can we contribute to sanitation?

Ans:

We can contribute to sanitation by:

1. Not litter at public places. If dustbin is not there, then carry the litter home & through it in dustbin.
2. Adopting good sanitation practices should be our way of life.
3. We must influence & encourage others to maintain proper sanitation.

Q7. What is the importance of community clean-up activities?

Ans:

Community clean-up activities:

1. Help to keep the environment clean and healthy.
2. Raise awareness about sanitation issues.
3. Leads to better public health.