L15 : Water pollution : Control - Air Water Pollution, Science, Class 8 Video Lecture - Class 8 | Best Video for Class 8

hello friends this video on air and
water pollution part 15 is brought to
you by example calm no more fear from
exam now how should this image be
disposed and what can happen if it is
not properly it is most so inappropriate
switch dispersion and cause pollution
now what do we mean by inappropriate
sewage disposal so if this sewage which
contains so many harmful and poisonous
substances if they are directly disposed
into water they are immediately going to
come back to us so the same excreta and
the same reasons are going to come back
to us in the form of one of these either
the water well you take back with them
in any of these for the water you drink
or the water which we use for cooking so
we are only going to get it back so let
us see how the sewage discharge can harm
the equity like what will happen if we
directly dispose the sewage into a water
body now inside that water body a lot of
equity animals sleep now sewage
discharge into water bodies
this will cause microbes caused bio
degradation of organic matter not a
sewage contains a lot of organic matter
so the volcanic matter is biodegradable
that means it is broken down into
simpler forms and this break down is
done by microbes primarily by bacteria
and fungi so all these microbes they end
in bio degradation of organic matter now
for doing this bio degradation or
decomposition they need oxygen so they
start utilizing a lot of oxygen so as a
result the same thing the oxygen gets
used up now these uncles they also need
oxygen now when there is no oxygen what
will happen to them
they will start dying so lack of oxygen
will kill the aquatic life
so therefore sewage discharge should not
be done directly into water bodies
because they contain a lot of organic
man
which kept me for the broken down so and
break down needs oxygen now the question
is then what can be done so the switch
needs to eat treat it before it is
disposed off and for how is it treated
for that we just discussed the sewage
treatment so the sewage needs to be
treated in sewage treatment plants
before this motion now what happens in
sewage treatment plant here it is more
toxic substances present in the sewage
gets converted into less toxic ones so
that at least the army effects can be
reduced so the entire treatment happens
in two stages that has primary treatment
and secondary treatment so in primary
treatment what happens is whatever
unwanted
bigger particles are present they are
physically removed from the sewage so
that is primary treatment and then
secondary treatment whatever organic
matter is present that is broken down
into simpler forms with the help of
microbes and at the end of secondary
treatment whatever is left out that has
very less content of harmful substances
so that can be directly disposed of it
to water bodies so here we are not going
to talk about the entire primary and
secondary treatment but let us see what
happens how exactly it is done we will
not discuss the complete thing but at
least I will give you an overview so let
us start with the primary treatment of
sewage so here particles are physically
removed from the sewage by using one of
the following process Federation so here
what happens swollen particles can be
removed from a liquid by passing it
through any such substance which has
force on it so the pores will allow the
liquid to pass through it but it will
stop the solids for example when you
prepare tea so that you separate the tea
leaves from the liquid so for that we
use a sieve so that seam has small pores
so that will allow the liquid to pass
through it but it will stop the tea
leaves from passing through it so the
same concept applies the
so whatever bigger particles will be
present in the sewage that will get
blocked by the origination the next
process the sedimentation in
sedimentation what happens is the
heavier particles are separated from the
liquid so we see the particles a
behavior they will set an out at the
bottom under the influence of gravity
and then the free liquid from the above
can be pour out can be taken in some
other vessel so these are with the help
of these two methods all big particles
big unwanted particles can be removed
from the sewage so you see this is how
filtration happens by passing it through
pores of a filter so this filter could
be some more tightness this is a
laboratory setup of a filter and in
segmentation so when you take the entire
sewage initially it will be like this
where there are particles suspended
everywhere in the sewage now after a
period of time the heavier particles
will settle down so these are the
greater ones and then you get a clear
comparatively clear liquid above so this
is the product this is the final product
of primary treatment of sewage and then
this is taken ahead for secondary
treatment now we will not discuss in
detail about secondary treatment but I
think you got an idea that how the
sewage is treated so that the at least
the whole toxic substances can be
removed out of it now with this we got a
fair idea about what are the different
causes that cause water pollution so let
us quickly look at how water pollution
can be controlled the some of the ways
by which we can control water pollution
are proper sewage disposal
after sewage treatment so the swish
should be properly treated now for now
when it is completely treated only then
it should be disposed off segregation of
wastes the waste products should be
segregated so that the biodegradable
waste products which can be broken down
for dilation
not be disposed of in the water because
if they are disposed of into water again
there will be lack of oxygen because
biodegradation activity will need an
oxygen shadow warms should be preferred
over bigger ones for domestic and
industrial beasts because shallow ponds
are like old points they do not have lot
of water but big ponds they have lot of
water so basically if even after proper
sewage treatment after that also when
you are planning through the wastes or
dispose them into a water body trying to
choose a pond which is smaller and
shallower so that the amount of water
that will get impacted will be less and
void the use of fertilizer before n that
is very important fertilizers should be
applied Tiny's so it should not be
followed by irrigation or rainfall so
you should try from your end that you do
not apply fertilizer just before aim
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