Page 175 - Science Class 07

WASTE Non-biodegradable Wastes

Any unuseful and discarded material can be Unlike biodegradable wastes, there are some
reffered to as waste. Wastes are generated other waste materials which are not decom-
everywhere in the households, in the posed by.
industries, in schools and so on. Important Natural agents like bacteria and fungi are
domes c wastes include garbage, food waste, mostly organic compounds, metallic oxides,
metal wastes, poly bags, oil, detergent, excreta mercury, lead, arsenic, pes cides, DDT, etc.
of animal, etc. Industrials wastes include con nue to appear in the environment and
metals scraps, chemical effluent, and other cause severe harm to it. Synthe c polymers like

solid wastes. On the other hand, hospital or polythene bags very harmful. In fact, they have
clinical wastes include expired medicines, become a real threat to our environment.
syringes, needles, flesh, blood etc. SOLID, LIQUID AND GASEOUS WASTES
CLASSIFICATION OF WASTES Meterials are found in these physical forms and
hence wastes are also generated in all the three
We can classify wastes into the following groups:
physical forms — solid, liquid and gas.
v Biodegradable Wastes
Solid Wastes
v Non-biodegradable Wastes
Solid wastes cons tute the largest part of
Biodegradable Wastes wastes. Solid wastes are generated from
Some kinds of waste materials are decomposed households and industrial ac vi es. Plas c
by microorganisms rela vely quickly into the bo les, cans, n cans, glass bo les, etc. are the

raw materials of nature, called biodegradable solids wastes generated from households. Metal
wastes. These biodegradable wastes disap- scraps, old papers, packing materials etc. are
pear into the environment a er a few months generated from industries.
to many years. Some biodegradable wastes
materials are the remains of plants and
animals, co on, paper, rope, etc.
Since, these wastes are biodegradable, they do
not remain accumulated in the environment

and hence they do not cause a long term
environmental degrada on. Solid Wastes
Time taken to
Waste Materials
Biodegrade
Orange Peels 6 months

Co on 1-5 months
Paper 2-5 months
Rope 3-14 months

Leather Shoes 24-40 years
Tin Cans 50-100 years

Biodegradable Wastes Glass Bo les 1 million years

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