Final Step in Wastewater Treatment Video Lecture | Science Class 7

hello friends this video on wastewater
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now once the secondary treatment is over
as I said the water which comes out
after the secondary treatment is
considerably clean however the final
round of treatment is given by the third
shield treatment and this is the final
cleaning process of water so once this
is done water can be reused so this
water in fact in many sewage treatment
plants what happens is after the second
after the secondary treatment is done
then only the the water is directly
disposed off into the rivers or oceans
but in some plants the tertiary
treatment is also done it is always
advisable to do the tertiary treatment
so it is the final cleaning process and
here the remaining inorganic compounds
and parasites that is disease-causing
microorganisms which might have been
present here like bacteria or viruses
they are all removed in this step
because if these parasites remain there
they can cause diseases in human beings
and that is why we always advise
everyone to bring clean water so one way
of doing tertiary treatment is
chlorination or chlorine water treatment
so here chlorine is added to water in
the form of length drop drops so when
chlorine and chlorine is the extremely
toxic it's a very small amount of
chlorine needs to be added to the water
and that chlorine being toxic is capable
of killing all the microorganisms it can
kill all the parasites that might have
been present in the water however care
should be taken that excess of cleaning
chlorine should not be added because it
because as I said a chlorine is
poisonous so it can be harmful to the
water quality if you are adding too much
of chlorine then the water itself
becomes poisonous and then you dispose
the seawater into a river or a ocean and
then that water might harm the aquatic
life therefore chlorine needs to be
added only in very small quantities and
that needs to be managed very carefully
but yes since chlorine is toxic it is
also capable of killing the
disease-causing microorganisms so this
is one way of chlorination is one way of
secondary or tertiary treatment another
way is along water treatment so what
does alum so alum is again a chemical
substance which which is capable in fact
chemically it is hydrated potassium
aluminium sulfate so hydrated
potassium aluminium sulfate so this is
alum and how atom can clean water and it
has the ability to remove the phosphorus
particles so let's say this is silty
water this is muddy water so you take
some muddy water you put some pieces of
alum in it either in pieces or in liquid
form you put alum inside it leave it for
some time you mix it properly and then
leave it for some time and what you'll
observe is that small phosphorus
particles very tiny phosphorus particles
they all start for making groups and you
you will be able to see lumps of those
kinds of phosphorus particles so they
all start coming together for and then
they can be easily removed with the help
of filters you see here the all the
muddy particles they have like it was
not really mind but it also contains a
lot of inorganic compounds like
phosphorus and they all come together
they form lamp like structures and then
you can very easily remove them by
filtration so that's how annal can be
used for tertiary treatment of water
this is called alum water treatment now
not only chlorine a chlorine and alum
there are a couple of other chemicals
which can also be used for final
cleaning process of water one such
example is ozone another example is
bleaching powder so all these are also
chemicals which have the ability to
clean or to get the water rid of micro
or inorganic compounds so now we have
breached towards the end of sewage
treatment plant or wastewater treatment
plant and what do we see we could
successfully convert the wastewater into
clean water so we started off with
wastewater which contains so much of
impurities which contain organic
impurities which contain in organic
impurities which contain parasites so
everything was there but by the end of
the entire process preliminaries
treatment primary secondary tertiary so
now we have clean water it doesn't have
organic impurities it doesn't have any
other type of impurity and now when you
dispose of this gained water into the
river so obviously we are safe because
we are and the best thing is that we
have not wasting that water we are not
wasting the waste water we are utilizing
even the waste water and that that's the
most beautiful thing so that's how we
saw that how a sewage treatment yarns
hold for how wastewater treatment plants
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