Page 160 - Ripples SCIENCE 7 - TEJPUR Edition 2024 Answer Key

18. Wastewater Management

Chapter in a Nutshell

v Clean drinking water is a necessity for all human beings. Our body needs it to perform
several life processes.
v Contaminated water is unfit for consumption & may cause several water-borne diseases.

v When oceans, seas, rivers, lakes, ponds & underground water get contaminated, it is known
as water pollution.

v The substances that pollute water are called pollutants.
v The causes of water pollution are waste from the industries, oil or liquid petroleum spills

that occur in water bodies due to human activities or oil container accidents, agricultural
practices and sewage.

v Sewage is the wastewater from domestic, industrial & commercial sources that contains
various impurities. These impurities may be organic impurities, inorganic impurities,
disease-causing bacteria, saprotrophic bacteria, nutrients & other microbes.

v Effects of improper sewage management are – soil contamination, water contamination via
improper wastes, severe weather due to climate contamination, dangerous to animals &

marine life & eutrophication.
v The pipes carrying away the sewage are connected to an underground network of pipes
called a sewer.

v A sewerage is a network of sewers that carries the wastewater from the point where it is
produced to the main sewer or sewage treatment plant.

v In a sewerage system, manholes are provided at the junction of two or more sewers. They
are used for the purpose of maintenance, repair & cleaning.

v Wastewater Treatment Plants (WWTPs) are large setups where wastewater is cleaned
before being released into the nearest water body or for being reused.

v The sewage treatment involves physical, chemical & biological processes to remove
impurities from the wastewater.
v The physical process of WWTP involves filtration, reducing size of solid waste, removal of

grit & sand and sedimentation.
v The biological process includes the use of anaerobic bacteria to produce biogas, aeration to

pump air into the clarified water so that bacteria can proliferate.
v The chemical process involves chlorination & treatment with ozone & ultraviolet radiations

that help kill germs present in the water to make it fit for drinking.

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