NCERT Class 7 Science Wastewater Story

NCERT Class 7 Science Wastewater Story. Download NCERT Chapters and Books in pdf format. Easy to print and read. Copies of these textbooks may be downloaded and used as textbooks or for reference. Refer to other chapters and books at other links (NCERT now providing you soft copies of all textbooks of all subjects from class first to twelfth online). 

18 Wastewater Story

All of us use water in our homes and make it dirty. Dirty! Are you surprised? 

Rich in lather, mixed with oil, black– brown water that goes down the drains from sinks, showers, toilets, laundries is dirty. It is called wastewater. This used water should not be wasted. We must clean it up by removing pollutants. Have you ever thought where the wastewater goes and what happens to it?

18.1 WATER, OUR LIFELINE

Clean water is a basic need of human being. Let us make a mindmap of the many uses of clean water. Clean water that is fit for use is unfortunately not available to all. It has been reported that more than one billion of our fellow human beings have no access to safe drinking water. This accounts for a large number of water-related diseases and even deaths. Women and girls walk for several kilometres to collect clean water, as you read in Chapter 16. Is it not a serious matter for human dignity? 

You have studied in Chapter 16 about the increasing scarcity of freshwater due to population growth, pollution, industrial development, mismanagement and other factors. Realising the urgency of the situation on the World Water Day, on 22 March 2005, the General Assembly of the United Nations proclaimed the period 2005–2015 as the International Decade for action on “Water for life”. All efforts made during this decade aim to reduce by half the number of people who do not have access to safe drinking water. Cleaning of water is a process of removing pollutants before it enters a water body or is reused. This process of wastewater treatment is commonly known as “Sewage Treatment”. It takes place in several stages.

18.2 WHAT IS SEWAGE?

Sewage is wastewater released by homes, industries, hospitals, offices and other users. It also includes rainwater that has run down the street during a storm or heavy rain. The water that washes offroads and rooftops carries harmful substances with it. Sewage is a liquid waste. Most of it is water, which has dissolved and suspended impurities. These impurities are called contaminants.

Exercises

1. Fill in the blanks:

(a) Cleaning of water is a process of removing __________.

(b) Wastewater released by houses is called ____________.

(c) Dried ____________ is used as manure.

(d) Drains get blocked by ____________ and ____________.

2. What is sewage? Explain why it is harmful to discharge untreated sewage into rivers or seas.

3. Why should oils and fats be not released in the drain? Explain.

4. Describe the steps involved in getting clarified water from wastewater.

5. What is sludge? Explain how it is treated.

6. Untreated human excreta is a health hazard. Explain.

7. Name two chemicals used to disinfect water.

8. Explain the function of bar screens in a wastewater treatment plant.

9. Explain the relationship between sanitation and disease.

10. Outline your role as an active citizen in relation to sanitation.


Please refer to attached file for NCERT Class 7 Science Wastewater Story

Tags: 

 


Click to View or Download pdf file
Click for more Science Study Material

Latest NCERT & CBSE News

Read the latest news and announcements from NCERT and CBSE below. Important updates relating to your studies which will help you to keep yourself updated with latest happenings in school level education. Keep yourself updated with all latest news and also read articles from teachers which will help you to improve your studies, increase motivation level and promote faster learning

How to Effectively Answer CBSE Board Examination Question Papers

The intend of this article is to share the best ways to answer the CBSE Board Examination. Usually most of the students tend to become nervous at the times of the board examination. In this article we will share the most effective ways to make the answers to the CBSE...

Tricks for Utilization of additional time introduced in CBSE Board Exams

Tricks for Proper Utilization of Add-On 15 Minutes introduced in CBSE Board Exams The intend of this article is to share the best suggestions and guidelines to utilize the extra 15 minutes provided for reading the question paper in CBSE Board Examination. These extra...

The CBSE Science Challenge 2020

The CBSE Science Challenge - 2020 Science is inexplicably linked with our lives and helps us to understand the world around us better. Scientific and technological developments contribute to progress and help improve our standards of living. By engaging with this...

Celebration of Republic Day by CBSE

As you are aware, Republic Day is celebrated every year on 26th January to honour the Constitution and Republic of our country. Celebration of this occasion annually helps youth and children of our country to be aware of the significance of Indian Constitution, unity...

Digital Marks Sheets Migration Certificates and Pass Certificates

CBSE pioneered in providing digital academic documents through its academic repository called “Parinam Manjusha” and DigiLocker.  As on now result data from 2004 till this year is available in the repository.  Approx. 12 crores digital academic documents are available...

×
Studies Today