Right
back at the prehistoric time, human beings have relied upon fish and shellfish
from the sea as a source of food. In recent years, people have also learned
that the sea is a major source of oxygen (gene-rating 80% of the oxygen in the
atmosphere) and of drinking water. Planktonic algae and other marine plants
produce oxygen which is dispersed by currents and thus provides a basis for
animal life throughout the oceans of the world. This is a superb example of
natural balance.
The
sea has always been a "natural dustbin" as well, with a cintinuing
inflow of muddy water, animal
waste
and even carcases. Yet such natural waste-products were easily "digested"
by the sea. Everything was held in balance in a finely-tuned natural system.
But,
fot the last 200 years, the artificial waste generated by human activity has
been accumulating into
a gigantic burden which has disrupted the natural balance and threatens marine
life throughout the world. Human beings are part of nature. If they destroy
the natural environment, the destroyed themselves.
1. Filtering for large impurities.
2.
Filtering for sand.
3.
Floating oil and grease to the surface.
4.Adding
chemicals to precipitate impurities dissolved in the water.
5.Allowing
impurities to settle and sink to the bottom.
6.
Disinfecting.
