Wastewater story Class 7 Notes Science Chapter 13

Introduction

Water is essential for many things we do every day. When you wash your hands, take a shower, or flush the toilet, the water that goes down the drain becomes wastewater. It's dirty and filled with things we don’t want in our water. But instead of just letting it go, we need to clean it. Have you ever thought about where this dirty water goes and how it gets cleaned? 

Water, Our Lifeline

Clean water, a basic human need, gets contaminated easily by humans and it is not safe for drinking. Drinking contaminated water results in diseases such as cholera, typhoid, and diarrhea. Polluted water can also prove fatal.
Water getting polluted in various ways

Water gets contaminated and scarcity of clean water is due to various reasons, examples of which include:

• People take baths and wash clothes in rivers and lakes.
• Many people bathe their animals in rivers and lakes.
• Increase in the population, industries, and improper disposal of waste.

It was on March 22, 2005, that the United Nations declared 2005-2015 as the International Decade for the Action "Water for Life". Hence, March 22nd is celebrated as World Water Day. The aim of the initiative was to reduce the number of people without access to clean drinking water by half.

Clean water is needed not only for drinking but also for cooking, washing and bathing. A lot of waste water is produced at home, which needs to be cleaned before it drains into rivers or lakes and also before it is reused.
Uses of clean water

Process of Cleaning Water

The process of cleaning water, known as sewage treatment, involves several stages to remove pollutants before it enter a water body or is reused. 

• Waste water released from homes, industries, hospitals and offices, and water collected during rains from rooftops or streets, is collectively termed Sewage.
• This sewage is liquid waste containing dissolved impurities, and the impurities are called contaminants, which contain many harmful substances.

What is Sewage? 

Sewage is dirty water that comes from homes, businesses, hospitals, and other places. It also includes rainwater that flows down the streets during storms. It is liquid waste, consisting of water and many impurities.

Sewage Water

1. Organic impurities: Organic impurities include animal waste, urine, oil, vegetable and fruit waste, feces, pesticides and herbicides.
   Inorganic impurities: Inorganic impurities include phosphates, nitrates and metals.
   
   
   Vibrio cholera causes cholera 
2. Bacteria: Bacteria like vibrio cholera which causes cholera and salmonella
   paratyphi which causes typhoid.
   
   
   Salmonellatyphi causes typhoid
3. Nutrients: Sewage contains some useful nutrients, such as phosphorus and nitrogen.
4. Other microbes: Microbes such as protozones which cause dysentery are also present in sewage water.

Sewage

Water Freshens Up an Eventful Journey

• The network of small and big pipes that carry wastewater is called sewers, and all sewers together form the sewerage.
• Wastewater is carried from home to the point of disposal, that is the wastewater or sewage treatment plant.
• After the treatment of wastewater, the clean water is released into nearby water bodies.
• Sewerage has manholes that can be used to clear blockages.
• Manholes are located every 50 - 60 metres in the sewerage.

If there is no sewage facility, then wastewater is directly drained into nearby streams and lakes, which results in water contamination.

Treatment of Polluted Water

Wastewater Treatment Plant(WWTP)

Wastewater treatment involves physical, chemical, and biological processes to remove contaminants.

Wastewater Treatment Plant(WWTP)The following are steps of water treatment:

Alternate Arrangement For Sewage Disposal

(i) To enhance sanitation, promoting low-cost onsite sewage disposal systems.
On-site Sewage Disposal System

(ii) Examples include septic tanks, chemical toilets, and composting pits.

(iii) Septic tanks are suitable for areas lacking sewerage, such as hospitals or isolated buildings. It is an underground chamber made of concrete, fiberglass, or plastic that is used to treat sewage from homes and buildings in areas without access to centralized sewer systems. 
Septic Tank System

(iv) Organizations offer innovative toilets that don't require manual cleaning.

(v) Waste from these toilets flows into a biogas plant. A biogas plant is a facility that turns organic waste into biogas through anaerobic digestion. Organic waste, like food scraps or manure, is broken down by bacteria in the absence of oxygen, producing biogas composed mainly of methane and carbon dioxide.

Biogas Plant

(vi) This biogas can be used as a renewable energy source for cooking, heating, electricity generation, and more.  

Sanitation at Public Places

• Fairs, railway stations, bus depots, airports, and hospitals are busy places where large amounts of waste are generated due to thousands of daily visitors.
• Proper waste disposal is vital to stop diseases from spreading, especially since open defecation and poor sanitation can cause epidemics and disease transmission.
• Government rules on sanitation might not always be enforced well. 

The "Swachh Bharat" mission initiated by the Government of India in 2016 aims to improve sanitation, including proper sewage disposal and providing toilets for all.

Swachh Bharat Mission But everyone can help by avoiding littering and taking their trash to proper disposal places, even if there's no bin nearby.

Conclusion

Mahatma Gandhi once said, " “No one need to wait for anyone else to adopt a humane and enlightened course of action.” 

We must understand our role in keeping water sources healthy by practicing good sanitation habits every day. Each of us can make a significant impact by taking individual responsibility and inspiring others with our energy, ideas, and optimism. When people come together and work collectively, remarkable things can be achieved.