Page 176 - Science Class 07

Gaseous Wastes of the drains are plastered to avoid soil erosion.

Gaseous wastes are generated by households, In rainy seasons, these drains get over-loaded
chimneys, factories, vehicles, thermal power and filthy water spread on roads and in streets
plants, etc. Gaseous wastes include harmful which causes diseases. Besides people throw
gases like carbon dioxide, carbon monoxide, wastes into the open drains and the drains get
sulphur dioxide, dust and other par culate choked. It also cause over flow of the drains.
ma er which include ash, metal par cles.

Liquid Wastes
Liquid wastes include domes c wastes
discharged from the kitchen, bathrooms and
toilets, besides, the effluent discharged from
factories. Waste water discharged from the
kitchen, bathroom and toilets is called sewage.
Overflowing of Drain

HARMFUL EFFECTS OF SEWAGE

The popula on of our country is increasing
1. Write any five most commonly wastes
rapidly. The popula on of our country has
generated in your home everyday?
2. Why the amount of wastes is increasing already crossed 1.10 billion. You already know
that land cannot be expanded with the increase
day-by-day?
3. Name any five bio-degradable wastes. in popula on.
4. What do you mean by non-biodgradable The density of popula on has increased
wastes? unexpectedly. In big ci es, a large number of
5. Write any five liquid wastes. people live in a small areas of land. Besides, the
more is the popula on the more of waste are
generated. The waste water discharged from
SEWAGE
the house hold or factories causes immense
You have studied about domes c liquid wastes damage to our environment as well as our
called sewage. It also contains a lot of health.
pollutants and other harmful materials which
Open drains or sewage are the breeding ground
generally lead to the pollu on of water bodies for flies, mosquitoes and other micro-organisms
as well as groundwater. In big ci es, there is a that spread diseases like cholera, jaundice,
huge network of drainage system to transport diarrhoea, dysentery, etc.
sewage to its des na on. Drainage can be
defined as the removal of surface or sub-
surface water from a given area by natural or
ar ficial means. In developed ci es, drains are

constructed under the ground called sewer. It
contains a network of pipes through which
waste water is sent to treatment plants for
purifica on. Small towns and villages have
open drainage system. In this system, the side Water Pollu on through Sewage

176 Science-7