Dear students in today's lecture and hence
for we will be talking about other applied
environmental problems, which use ah which
apply them molecular biology and macro biology
understanding to treat environmental contamination
and environmental problems. And today we are
going to start with wastewater. Now ah there
is lot of focus at currently in India on sanitation
ah through the Swachh Bharat Abhiyan and ah
making show that we get the eliminate opendafication,
but the question arises ok we get rid of opendafication
people can are are required for defecate in
toilets public or private toilets, but what
happens to the faecal matter and the urine
after the person has defecated.
The where does it go where is it dumped of
how is it treated and that job is done by
wastewater treatment plants we call them wastewater,
because ah we ah do not have dry toilets we
use wet toilets. So, we use water for flushing
for cleaning and the water contained in faecal
matter in its surface quite substantial. So,
when this wastewater we call it wastewater
ah very politely.
So, this wastewater typically in developed
countries is collected through a wastewater
collection system, it goes to a centralize
facility or de centralize facility which then
treats this wastewater employees microbes
ah to get rid of organics in the wastewater,
and treats it to a degree that it can be now
safely released in the aquatic systems. However,
in a country like India the major problem
is that first of all we do not have a good
and reliable wastewater collection system
and secondly, many parts of the country still
do not have functional wastewater treatment
plants.
For example, um why why do not you do this
go ahead and find out this week if your town
your city your village has a wastewater treatment
facility or not. And if it does go ahead try
to make a visit to it and if you are unable
to make a visit to it look up the information
of how much MLD the ah plant is or not, and
one of the questions in your homework this
week would be about your local wastewater
treatment plant. In case you do not have a
local wastewater treatment plant for example,
I live in Roorkee and unfortunately in Roorkee
right.
Now, we do not have a wastewater treatment
plant. So, basically all are faecal matter
first droughts an aerobically inner septic
tanks and then is disposed to aquatic systems
and causes much damage to our environment,
and also to our public health because microbes
love to greed in that rich decomposing faecal
matter and many of them and many of them can
be pathogens and; obviously, we have flies
and other vectors that in carry diseases from
the faecal matter and expose humans and other
living beings to the diseases.
So, if you live in a city or a town or place
like myself, which does not have a wastewater
treatment plant, then your job in this weeks
homework would be to find out the nearest
wastewater treatment plant to your place and
ah its so, happens that I have a map of wastewater
treatment plants that are atleast on paper
functional in India.
So, I will be able to know where you are and
what is the closest wastewater treatment plant
for you so, but its your job to find out and
then to find out how much MLD million litres
of ah per day of wastewater does it receive,
and does it treat and at times you know do
your wastewater treatment plaint plant might
have a unique approach to cleaning waste for
example, many of the plants in India ASP based
what is ASP activated sludge process? We will
be talking about it today and in the next
lecture, but many um um wastewater treatment
plant atleast the recent one, that are built
through public private partnership are SBR
base which is sequence say sequence batch
reactor base.
So, we will be talking about that very briefly.
So, ah you also need to find out what kind
of wastewater treatment plant it is and how
much MLD of wastewater receive everyday now
dear students ah coming back to the wastewater
scenario in our country because our wastewater
collection system is non-existent in large
parts of the country, even if you are using
a toilet to defecate where does the toilet
go and how do we treat it will determine the
impact on public health.
So, there is some criticism right now ah among
scientist about the current approach of the
government to focus more on stopping the opendafication
bringing people ah into the toilets instead,
without focusing on what do we do with the
waste that will be generated and collected
in the toilets. So, ah today I want to talk
about wastewater I mean very briefly talk
about the history of wastewater treatment
plant ok then compare what is happening abroad
in different countries and what is happening
in India. And um if not in this lecture then
definitely in the other lecture I want to
present few slides to you about ah giving
a comparison of how different countries take
care of the human waste.
So, let us get started with wastewater treatment
water and wastewater microbiology.
Water is the most common source of water borne
diseases obviously, but not only that water
borne diseases make the major chunk of infectious
diseases across the country. So, it very important
for us to take good care of water the other
thing is water is essential for life we cannot
survive without water and here is a beauty.
The more populated the region is the more
dense its water demand is more concentrated
its water demand is, and also the more dense
its wastewater generation would be. So, if
I have a sparcly dense ah sparcly populated
place, then the wastewater generated per kilometres
square would be much lower and thus the burden,
it will cast on public health would be lower
versus in congested cities with a lot of people
living vertically stand over each other, there
we generate lot of waste per kilometre square,
and that makes the large cities and heavily
populated regions and heavily populated countries
such as India very well to water borne outbreaks.
Now, one example I would like to give, whenever
ah a mass population is mobilized after the
water briefly earlier whenever mass population
is mobilized they ah re setup refugee camps
where the refu ah refugees can stay and survive,
until we find a solution of how to either
rehabilitate them back to the home town home
place or to rehabilitate them in new lands.
So, ah in this intern period when they are
staying in the refugee camps, the population
density is very high the wastewater treatment
infrastructure is nonexistence. So, even though
let us say a it is arriving and giving them
clean water, but nobody is taking care of
the wastewater and as a result refugee camps
are very very susceptible to water borne illnesses.
So, whether we look at after the major earthquake
that really devastated the island, ah when
the refugee camps were setup and people lost
their wastewater collection system what resulted
was a very sad choleraoutbreak. Another example
would be the what on ah . So, in there we
have ah the one of one of the largest ah refugee
population in the world that history has ever
seen. Now these people were living in refugee
camps to some degree have access to the invertor,
because people are really trying hard to get
this minimum ah essentials to them; however,
there is no infrastructure in place to take
care of the wastewater treatment plant and
thus the is not only seeing a refugee crisis,
but is also seen the worst outbreak.
As we as I talk right now and. So, these examples
that happen ah when there was a natural disaster
or manmade disaster like war and refugee camps
were setup. But what we have in our Indian
cities is not very far or from a refugee camp.
We have lot of people packed together they
probably have access to clean water because
um the government takes to ensure that it
can supply water to you and with the water
is treated to a certain degree that ah you
will not fall sick given the general immunity
of our country men and women and those who
cannot those who do not use municipal supplied
water they have access to aqua guard, filters
or bottled water to keep them safe. However,
every individual no matter whether you you
drink water from bottled water from a water
fountain, from municipal supplied water or
from a well that you trust and ah let us say
it reliable well no matter where you drink
water from the all generate waste and ah many
a times water borne illnesses they do not
they are a simtomic, they do not show symptoms
in us.
So, as a result I might be how doing diseases
that do not know about it or maybe even I
know about it, but there is nothing I can
do except defecate in the place that I am
supposed to defecate in my defecated matter
will then makes with the communities defecated
matter let us see we are using toilets. So,
the toilets will become the focus point focal
point for the defecated defecal matter of
the entire community. When that happens we
have lot of biomass in place and the biomass
is the perfect food that the pathogens are
used to atleast the water want pathogens and
the gut micro biotise is used to, and this
is the place where microbes can ah multiply
readily. And if we have ah poor management
and these defecal matter either infiltrating
to a drinking water system or the infiltrating
to a ground water system or contaminated surface
water system or just lye outside open exposed
as ah pools of defecal matter then they become
a source of diseases.
So, again to coming back to the point heavily
populated areas are more vulnerable for outbreak
such a water borne diseases, because ah lot
more faecal matter is generated and if you
do not have adequate ah wastewater infrastructure
wastewater collection and treatment infrastructure,
then we are likely to have serious diseases.
Now the question that might arise well in
India, we are heavily populated and as I mentioned
earlier we do not have good wastewater collection
system, we do not have good savage treatment
system for example, Roorkee does not have
a single wastewater treatment plant. So, lakhs
of people living in Roorkee their waste is
just contaminating the environment and we
defecate every day its not um ah the amount
of waste we generate as a community is in
enormous enormous .
So, the question arises why is Roorkee not
seeing why why are people not dying out of
water borne diseases and there was a simple
answer to that is well nor not all water borne
diseases are as infectious as choleras, choleras
highly infectious it requires very little
infectious dose to ah to ah infect healthy
individual and the other thing is the cholera
microbe survives in the environment. So, even
if they are few cholera microbes that have
been defecated by human being, and water source
has been contaminated or food source has been
contaminated or just the faecal matter is
lying in a picks up the cholera it can. In
fact, many people very fast. And the other
thing is that the cholera ah kills really
fast because the diarrhoea is really severe
that is cost by which is cost by cholera.
So, coming back to the question why in India
do we not alarmed about the water borne outbreaks
ok. The 2 explanations were this ah many people
will tell you that we indians have developed
ah certain level of immunary, which is partly
correct partly not the other thing is ah unfortunately
we ah the people who are more susceptible
to getting water borne illnesses, such as
the middle class lower middle class and the
really a social economically under privileged
class of people in India, um take it as a
part of life getting water borne illnesses.
Getting diarrhoea is part of life getting
jaundice is part of life, getting typhoid
is part of life. We do not question in a public
health illnesses do not are not very particular
about collecting the data and making it public
and saying ok these regions in the country
are endemic to ameba histolytica diarrhoea,
these regions have an outbreak of typhoid
these um there is something about our culture
our current culture that we take it for granted
we do not question it we suffer silently and
with the other thing, but that is a different
lecture completely.
So, India is sitting on a major outbreak of
multiple water borne illnesses and there is
another thing I want to ask. So, another part
of your homework is to do a small family and
neighbourhood survey, and find out in the
list of water borne diseases is given to you
in the question, find out what water borne
diseases had affected your neighbours your
family your friends in past one year.
So, all you need to do is against every disease
you just put a tally mark and then count how
many ah what kind of diseases have been your
family and your um friends and neighbours
have been affected in last one year and how
many times. For example, the place where I
come from entamoeba histolytica is endemic.
So, people get that amoebic decentry very
often and its not I if I say that I yes I
did get amoebic decentry in last one, year
its an inaccurate presentation because I might
have got the decentry 20 times last year.
So, in that case I would want you to draw
20 write withdraw one tally and then write
20 next to it. So, we know that the one person
got ah the amoebic decentry last year 20 times.
So, both information are important how many
people got what diseases they got and how
many times were they infected all right let
us move on I have already talked about recent
outbreaks of cholera. So, now, let us move
on about half of the world population faces
scarcity of water. So, forget about having
water that is not safe half of the population
still does not have enough water to drink
and to live. And if you ah I hope you realize
the importance of drinking water hopefully
most of us are ah most of us have access to
drinking water, but many in our own country
maybe some of us who are attending this class
do not have access to clean drinking water.
2.4 billion people like access to adequate
sanitation this was in 2006 the figures have
improved.
But they nearly still the same nearly 2 billion
people across world do not have access to
adequate sanitation.
And where do you think this 2 billion people
are most of this 2 billion people are in India.
Most of the this 2 billion people who do not
have sanitation are in India and that is the
reason why the country is ah ah pushing away
from open defecation and encouraging people
to use toilets instead now here is a problem
when people do not have good sanitation system
we promote water borne diseases earlier our
focus was on drinking water and making sure
people have good quality, and save water to
drink because if the water is contaminated
and you drink and you fall sick and that is
quite quick this sickness will come quite
quite quickly. Now if you do not have adequate
wastewater treatment plant you are contaminating
a water sources and your food more frequently.
So, you are more susceptible to fall in sick
anywhere. So, we have to do ah we have to
wage our efforts, we have to put efforts in
tackling both the water treatment and wastewater
treatment. Now how does wastewater treatment
work? And because this is applied in moment
microbiology class, let us see how and why
is ah microbiology very important for wastewater
treatment. So, in wastewater treatment we
have usually have multiple steps we start
with this wastewater correction process.
So, the wastewater is collected from different
parts of the city or the area or the region
that ah comes under the waste purview of the
wastewater treatment plant and then it is
taken to the wastewater treatment plant. Now
ah one thing I wanna mention in most developed
countries that I am familiar with usually
there is a pipe system like how we had drinking
water distribution system there is a wastewater
collection system, that um that is also laid
at the time of constructing a city planning
a city. ah In India we have that to in many
cities and many regions, but I have noticed
that in India many a times we have tankers
they come and they collect the waste from
septic tanks or wastewater collections ah
tanks and then they carry it to the wastewater
treatment plant.
So, instead of many a times instead of having
pipes that are laid under the town under the
city, which carry the wastewater to the wastewater
treatment plant, we actually have tankers
that come that fill the waste and then they
carry it. So, this is a quite unique feature
that I have noticed in our country and I think
its fun any ways. So, the wastewater gets
eventually either whether it comes from tankers
or from pipes its get collected into ah ah
wastewater treatment plant, this the first
step that wastewater undergoes is screening.
So, we get rid of the big particles maybe
surprised the amount the kind of waste we
see in a wastewater treatment plants, ah in
many parts of the world we have note we have
found parts of car; in wastewater treatment
plant we have found dead bodies of animals
and even human beings ah people have an routinely
we find agricultural produce.
So, we have the kitchen waste coming in wastewater
treatment plant, these things really mess
up the functioning of wastewater treatment
plant. Because if they pass through the screening
stage let us say a lemon passes through the
screening stage or um in India we have many
of us have an habit of eating ah [FL] which
comes in aluminium foils. So, this aluminium
ah aluminium pouches.
Now these are we have use shampoos that cover
aluminium and plastic pouches or sashes. Now
these the aluminium is really bad for wastewater
treatment plant because it easily passes through
the scream because these sashes are usually
requite small or thin, they pass through the
scream and ones, they have passed they have
they have seen stay cause severe abrasion
of rest of the wastewater treatment system.
So, one of the request that I have that um
from all the students please spread awareness
about this and inform people not to throw
waste into their pots. If you are using a
toilet do not throw ah household waste inside
your toilet ah you should have another land
field waste tree or or solid waste management
system for that, this is only for wastewater
this is only for human waste and not for aluminium
foils, shampoo sashes and definitely not for
agriculture produce automobile parts and dead
bodies.
Any way after screening we have the next step
called sedimentation; in sedimentation now
that we have screamed the wastewater of the
big parts, now the great and the big part
we allow the remaining great sand and other
inner particles and even ah un instable unstable
particles to settle in the sedimentation tank.
Now, this is very important because in sedimentation
tank just because of gravity, some 50 percent
of ah biologically unstable material and um
particulate matter is removed. So, ones the
sedimentation is happened the supernatant
goes for further treatment and this is aerobic
oxidation, which is aerobic oxidation if you
remember from microbiology microbes are consuming
oxygen and they are oxidizing the electron
donor.
So, microbes will take the oxygen, we supply
them lot of oxygen and then they consume the
wastewater ah they consume the faecal matter
and all other organics that are present in
the wastewater. The settled solids in the
sedimentation tank, they go for anaerobic
oxidation. So, this is in absence of air,
but there is oxidation we will talk about
it, but for now know that screening and sedimentation
are called primary treatment because together
they are very physical processes this is this
sieving, this is basically mechanical sieving
and sedimentation is sedimentation vary mechanical
process we are not using chemicals yet we
are not using biological process yet to clean
the wastewater. In aerobic oxidation an aerobic
oxidation we use microbial processes.
So, in aerobic oxidation ah the 2 methods
broadly one is where we have microbes ah planktonic
in the waste water. So, they float freely
in the wastewater they interact intimately
with the waste and then they degrade it and
they irritant heavily such system is called
activated sludge system. So, sludge is the
biomass and the waste material together, trickling
filter systems are different there here we
have stationary biofilms. So, microbes are
stationary and the water trickles to them.
So, here we have its much like the ah if you
remember from acid main drainage, we talked
about reactive barrier on one side we have
contaminated water and as it passes through
the reactive barrier the microbes ah reduces
sulphide and then we get clean water out of
the barrier. Similarly in trickling filter
we have a trickling filter, wastewater drops
from the top and as ah the water trickles
down, it it goes interacts with microbes and
the trickling filter which degrade the organics
and then we get literally very clean water
below the trickling filter.
So, these are the 2 ways and 2 methods in
aerobic oxidation and the differences that
in activated sludge process, the microbes
are mobile and they are mixed with the wastewater
in trickling filter they are stationary and
they are attached to the filter. Now this
part is called secondary treatment because
it utilizes micro bio chemical processes for
cleaning water. Now ah the supernatant went
for aerobic oxidation, the um sedimented portion
the certain portion goes for anaerobic oxidation.
Now this happens at three different temperatures.
So, we have warm, hot and hotter and um mostly
mesophilic and thermophilic conditions are
where we do anaerobic oxidation and um the
the point is that we digest the sludge. So,
the sludge that was collected from the bottom
of sedimentation tank is digested and then
it is dried or de watered.
So, we can do de watering through different
techniques, we can centrifuge it we can press
it, ah we can sun dry it, we can blow in whatever
way different drying techniques and ones we
have dried we have ah reduced the volume of
the sludge, and now this can be incinerated
or used as fertilizer or could be buried under
the land. um Now ones we have treated the
water coming back here, ones we have treated
the supernatant and to petty good degree the
turbidity reaches usually reaches the ah it
should reach yours ah regulated regulatory
values your BOD should go to regulatory values,
your chemicals that can degraded ah aerobically
by microbes, they should go to um regulatory
values and even the n p n which is a way of
measuring microbial population, that should
also go to regulatory values in the next step
is disinfection.
So, we add chlorine or other disinfectents
and we get rid of the microbes. So, um its
quite possible that through screening sedimentation
and even aerobic oxidation, some pathogens
have survived and we do not want these pathogens
going and ah going out in the environment
and being exposing to animals and human beings.
So, we undergo disinfection process, then
this is the treated effluent is discharge
to the water body. So, this is basically wastewater
treatment process for you .
Now, let us look at some pictures and let
us look at the kinetics of the wastewater
and about how the microbial processes worked
. Ok. So, and this is very important because
this is in line with a UN millennium a development
goal, we were hoping that by 2015 we will
have um safe drinking water access and access
to adequate sanitation, but ah India is yet
to meet its target ok. So, first of all if
this is the wastewater, we need to find out
what is there in wastewater. So, um you would
know that in wastewater, domestic wastewater
we have pathogens.
So, ah because they are coming from a faecal
matter, we have microbes that live in a gut
and these microbes some of them might be pathogenic.
But they might not be in enough dose to infect
us or we maybe we have very good immune system
and we are not simtomic we do not throw the
symptoms, but most likely its going to have
lot of microbes and some pathogens. Also it
will have solids, some solids will be dissolved
some would be suspended, some would be volatile
and some would be fixed. It might have fat
oil and grease they together called as fog
now why would fat oil and grease come into
domestic wastewater if it is just human faecal
matter. Because its not just human faecal
matter many a times grease is also disposed
in the wastewater treatment plant for example,
in many homes across the world even the kitchen
ah wastewater is ah combine with the sewage
and it goes to together it goes to wastewater
in that case we might have lot of fat oil
and grease.
Now, BOD and COD I have talked about BOD before
and COD ah I do not think I have talked, but.
So, its a good idea to go over them again,
now BOD and COD BOD stands for biochemical
oxygen demand COD is chemical oxygen demand
ok. Its very hard for us to measure how much
bio degradable organics are present in the
water and how much organics are present in
the water that can be degraded chemically.
So, um the way we find out about how much
organics are present in water and how much
of it can be degraded biologically is by exposing
the wastewater to microbes and then allowing
them to degrade it. And as microbes degrade
it they consume dissolved oxygen and dissolved
oxygen goes down. So, the ah um the principle
behind um measuring waste by allowing microbes
to eat the waste is that the more the waste
is present the more oxygen will be depleted
in 5 days 3 days or any given time period
by microbes.
So, by looking at how much the oxygen is falling,
we get an idea of how much waste was present.
If lot of waste was present then almost all
oxygen would be consumed little waste was
present little or in bio degradable organics
were present, then ah microbes will not need
to consume lot of dissolved oxygen. So, basically
what we do is we take wastewater we dilute
it enough. So, that we do not always get ah
no oxygen left or less than 2 milligram of
per litre oxygen left um and then we allow
microbes to eat it we add microbes allow them
to eat the wastewater and then we notice how
much BOD has dropped and then we extrapolate
and find out how much BOD was present.
So, that is BOD. BOD biochemical oxygen demand
by looking at the oxygen demanded by biology
by ah biological agents that is microbes to
consume a waste will give me an idea of how
much waste was present. Now COD is chemical
oxygen demand bio ah microbes are not the
only ways to degrade the waste or we can also
use certain chemicals to completely oxidize
the waste right into even mineralization.
So, this is chemical oxygen demand we use
a very strong oxidizing agents such as um
k 2 c r 2 o 7 ah and then ah very well standard
using a very well standardized protocol we
oxidize all the way carbonal carbonaceous
material that can oxidized.
So, we know that because COD is ah chemical
oxidation, the part of the ah organics or
carbon based materials that microbes could
not degrade in time, because let us say its
toxic or because its ah recalcitrant does
not like to bio degrade or it microbes do
not eat it anyway all these would be included
in COD along with bio degradable fraction.
So, BOD is always less than COD or equal to
COD ok. Now BOD and COD are usually soluble
or particulate matter and then in domestic
wastewater we have also nutrients.
So, urine is very rich in nitrogens nitogen
is important, it also might have phosphorous
it will have phosphorus in orthophosphate
or organic phosphorus, and we need to remove
nitrogen and phosphorus also and I hope I
have mentioned about this in one of the previous
lectures, if not here is a brief review for
you that nitrogen and phosphorus are very
important to remove from a wastewater because
if we have access of nitrogen and phosphorous
going out from the effluent into the environment
and it let us a goes to a surface water body
its going to promote algal bloom and if algal
bloom happens then lake dies lake eutrophication
happens and we do not want that. So, there
is a particular ratio of nitrogen to phosphorous
and that ratio should be respected.
So, we want to reduce nitrogen and phosphorous,
our recently propose guidelines require us
to reduce nitrogen phosphorous a lot. And
then wastewater might have toxins like heavy
metals pesticides and solvents same question
again how will heavy metal pesticides and
solvents find their way into wastewater, well
many of us have a habit of dumping our ah
waste pesticide waste solvent into toilets
and that is how it ends up there the other
reason is many a times um in our kitchen,
we deal with chemicals that have xenobiotics
in them that have solvents in them that have
heavy metals on them even our vegetables and
fruits that tent to have lot of pesticides
residues on them or others gets washed and
it goes to the wastewater. Now this is very
important part because the microbes they want
to outcompete pathogens remember pathogens
want a host ah millennium host cholera wants
to infect human being, it does not want to
infect another bacteria.
So, other bacteria want to outcompete cholera
,ah in a wastewater treatment plant because
there are no human or there are less human
obviously, um we want to degrade solids microbes
to degrade solids to degrade fog to degrade
BOD COD to get rid of nutrients, but the toxins
will they will effect ; however, the microbes
degrade these ah solids fog BOD COD and nutrients
because the heavy metals pesticides solvents
and other um ah contaminants such as pharmaceuticals
many of which are antimicrobial. So, they
actually kill the microbes, which get rid
of all the waste they will affect the functioning
of wastewater treatment plant and does not
require lot of pharmaceuticals to ah kill
microbes.
So, if let us say ah a wastewater treatment
plant now is begins to receive wastewater
from a pharma industry, then that will have
lot of antimicrobials. And it might actually
kill the plant there is an incident that ah
my advisor doctor with us she was in Colorado
state university there was ah there was ah
local wastewater treatment plant which died
like it just stopped working and they wanted
to know what happened and then they found
out that ah that wastewater treatment plant
was exposed to very high levels of mercury,
and then they trace that mercury was coming
from when I if I remember it correctly it
was coming from ah an ah small factory plant
right next to her laboratory and and that
was the reason why the wastewater treatment
plant died. So, if you put a really bad toxin
in your toilet it might kill a local wastewater
treatment plant ah we do not kill it, but
you kill the microbes that are doing your
job.
So, please be very careful about what you
are putting in your toilet, this is very very
important for public health and environmental
health. um Dear students ah this is all for
today in the next lecture we will talk more
about how wastewater treatment works and what
is wastewater treatment biology, what what
are different organisms that participate in
wastewater treatment that are very activated
and who wha who and what do they do eat. Because
there are some microbes like protozoa that
eat bacteria there are some microbes that
exclusively eat BOD COD. So, we will talk
about these things in the next lecture that
is all for today.
Thank you .
