83
BOD varies from one ……………………..to the other and on the basis
of BOD found in a particular water body we can determine if the
water body is ………………………..or not.
16in
sewage
treatment
facilities
the
sewage
can
……………………….various treatment ……………………,a s a first step
……………………….are
removed
and
…………………….liquid
is
discharged to the receiving waters.
if a greater reduction of BOD is required , the supernatant liquid can
be subjected to ………………………treatment
17the treatment process depends on …………………….of the
receiving water to contain the treated sewage . After biological
treatment , if the receiving water require a further treatment ,
the liquid can be
retained in………………………….with sands or
sediments to filter ………………………
18the
desinfection
of
sewage
consists
of
…………………………..certain
types
of
………………………….such
as
………………………or
…………………………..
These
chemicals
can
interract with ………………………….of the sewage
and
produce
…………………….
19Marine
organisms
are………………………..by
the
different
substances thrown by humans in the ocean , either by
……………………..or …………………them.