Lecture 01: Importance of water and wastewater treatment.

Summary

In this inaugural lecture for the 'Water and Wastewater Treatment' course at IIT Roorkee, Professor Bhanu Prakash emphasizes the critical importance of the subject by highlighting the significant role of waterborne diseases in mortality rates, particularly in India. He discusses the historical context, including the impact of germ theory and the pioneering work of doctors like Ignaz Semmelweis and John Snow. The lecture also touches on the evolution of water treatment methods, such as filtration and chlorination, and their profound effect on public health. The professor concludes by stressing the ongoing relevance of these issues in developing countries and the potential for engineering solutions to improve global health.

Takeaways

• 📚 The lecture is an introduction to the water and wastewater treatment course for undergraduate civil engineering students at IIT Roorkee.
• 🌍 The course emphasizes the importance of water and wastewater treatment, highlighting its relevance through data on causes of death, particularly diarrheal diseases which are often waterborne.
• 💡 The lecturer, Bhanu Prakash, acknowledges Dr. Bill Bachelor of Texas A and M for his influence on the course content.
• 🔗 The course is a 30-hour UG course worth 4 credits at IIT Roorkee, and students must register via the NPTEL portal to take the exam.
• 📊 Data presented shows that diarrheal diseases are a significant cause of death in India, affecting 5% of the population across all age groups and up to 18% in children aged 1 to 4.
• 👶 The script discusses the high infant mortality rate in India, with three infants dying every two minutes, often due to a lack of access to clean water and sanitation.
• 🌿 Historically, the germ theory of disease was not widely accepted until the mid-1800s, and even medical professionals resisted practices like handwashing.
• 👩‍⚕️ The lecture tells the story of Ignaz Semmelweis, who faced resistance for his findings on handwashing and the reduction of childbed fever in hospitals.
• 🦠 It discusses 'Typhoid Mary,' an asymptomatic carrier of typhoid, illustrating the concept that healthy individuals can spread disease.
• 🏙️ The cholera epidemic in London and Dr. John Snow's discovery that cholera spreads through contaminated water were pivotal moments in understanding waterborne diseases.
• 🛠️ The lecture concludes by noting the importance of engineering in public health, with filtration and chlorination being key advancements in reducing waterborne diseases.

Q & A

Why is water and wastewater treatment considered a core course for civil engineering students?

Water and wastewater treatment is a core course for civil engineering students because it addresses critical aspects of public health and environmental safety. The course provides essential knowledge on how to manage water resources effectively, ensuring clean water supply and proper treatment of wastewater to prevent diseases and protect the environment.

What is the relevance of discussing the top 10 causes of death in a water and wastewater treatment course?

Discussing the top 10 causes of death, particularly diarrheal diseases, in a water and wastewater treatment course is relevant because it highlights the impact of waterborne diseases on public health. It underscores the importance of proper water treatment and sanitation in reducing mortality rates and improving overall health conditions.

How does the lecturer plan to provide data sources for the information presented in the course?

The lecturer intends to provide relevant links or sources at the end of each slide where the data is presented. Additionally, students can email the lecturer at [email protected] if they require the data and it was not provided in the slide.

What is the significance of the 30-hour course duration in the context of the curriculum?

The 30-hour course duration is significant as it equates to a 4-credit course at IIT Roorkee, indicating the depth and breadth of knowledge covered. Students should verify the credit equivalence in their specific curriculum to understand how it fits into their academic requirements.

Why is it important for students to register via the NPTEL portal for the course?

Registering via the NPTEL portal is crucial for students who wish to take the exam and receive credit for the course. The lecturer mentions that some students faced issues by enrolling through IIT Roorkee without registering on the NPTEL website, which caused complications once the deadline passed.

What is the role of助教 (Teaching Assistants) in the course?

助教 (Teaching Assistants) play a supportive role in the course by assisting students and answering their queries in discussion groups. They are there to help clarify concepts and provide guidance through the coursework.

How does the lecturer emphasize the importance of clean water in relation to infant mortality rates?

The lecturer emphasizes the importance of clean water by citing statistics that show a high infant mortality rate, with three infants dying every two minutes in India. This is attributed to the lack of access to clean water, sanitation, and proper nutrition, which are critical factors in reducing infant deaths.

What historical example is given to illustrate the impact of water treatment on public health?

The lecturer provides the historical example of Dr. John Snow's work during the 1854 cholera outbreak in London. By identifying the contaminated water pump as the source of the outbreak and advocating for the use of sand filters and chlorination, Snow's work significantly reduced the spread of cholera, demonstrating the profound impact of water treatment on public health.

Why does the lecturer mention the case of 'Typhoid Mary' in the context of water and wastewater treatment?

The case of 'Typhoid Mary' is mentioned to illustrate the concept of healthy carriers of diseases. Mary Mallon, despite showing no symptoms, was a carrier of the pathogen causing typhoid fever. This example highlights the importance of understanding disease transmission pathways, which is relevant to the field of water and wastewater treatment where carriers can contaminate water sources.

What is the significance of the statement that 'the greatest medical revolution of the previous century was not by doctors but by engineers'?

This statement emphasizes the critical role of engineering, particularly in the field of water and wastewater treatment, in preventing diseases and improving public health. Engineers' contributions to water treatment technologies have been as impactful as medical advancements in saving lives and reducing the spread of waterborne diseases.

Outlines

00:00

📚 Introduction to Water and Wastewater Treatment Course

The lecture begins with an introduction to a water and wastewater treatment course for undergraduate civil engineering students at IIT Roorkee, led by Bhanu Prakash. The instructor expresses gratitude to Dr. Bill Bachelor of Texas A and M for his influence on the course. The relevance of the course is discussed, emphasizing its status as a core requirement for civil engineering students. The lecture then delves into the importance of water and wastewater treatment by presenting data on the top causes of death in India, particularly highlighting the significant mortality rate due to diarrheal diseases, which underscores the course's significance in public health.

05:04

🔬 The Impact of Diarrheal Diseases and Waterborne Illnesses

This segment focuses on the prevalence of diarrheal diseases as a leading cause of death in India, especially among infants and young children. The lecturer uses statistical data to illustrate the high mortality rates associated with waterborne diseases and emphasizes the potential for prevention through proper water and wastewater treatment. The discussion also touches on the broader context of infant mortality and the role of clean water, sanitation, and nutrition in public health. The lecture concludes with a historical perspective on the evolution of medical understanding regarding the transmission of diseases, highlighting the shift from miasma theory to germ theory.

10:06

👨‍⚕️ The Pioneering Work of Ignaz Semmelweis in Infection Control

The lecture segment discusses the pivotal contributions of Ignaz Semmelweis to the field of medicine, specifically his discovery of the importance of hand hygiene in preventing the spread of infections. Semmelweis observed higher mortality rates in a doctor-led maternity ward compared to a midwife-led clinic and hypothesized that 'cadaverous particles' carried by doctors were responsible. His recommendation for doctors to wash their hands in chlorine solution significantly reduced maternal mortality. Despite the scientific validity of his findings, Semmelweis faced resistance and ridicule, which is reflective of societal challenges in accepting new scientific theories.

15:08

🌐 The Role of Prejudice in Pandemics and Public Health

This part of the lecture addresses the role of prejudice during pandemics, using historical examples such as 'Typhoid Mary' and the cholera epidemic in London. It discusses how societal prejudices can lead to the mistreatment of individuals perceived as carriers of disease, and how this prejudice can hinder public health efforts. The lecture also touches on the importance of scientific temper and the slow acceptance of new ideas in society, particularly in the context of public health and disease control.

20:08

🚰 The Evolution of Water Treatment and Its Impact on Public Health

The final segment of the lecture discusses the historical evolution of water treatment methods, such as sand filtration and chlorination, and their significant impact on reducing waterborne diseases like cholera and typhoid fever. The lecture highlights the role of engineers in public health advancements, contrasting the experiences of developing and developed countries in managing waterborne diseases. It concludes with a reflection on the importance of continued knowledge dissemination to improve global public health standards.

Keywords

💡Water and wastewater treatment

Water and wastewater treatment refers to the processes used to remove contaminants from municipal wastewater and produce treated wastewater that can be safely released into the environment or reused. In the video, this concept is central as it is the main subject of the course being discussed, highlighting its importance in civil engineering and public health.

💡Diarrheal diseases

Diarrheal diseases are conditions that cause severe diarrhea, often due to infections by bacteria, viruses, or parasites. The script emphasizes the significance of these diseases as a leading cause of death, especially among children, underscoring the relevance of proper water and wastewater treatment in reducing such fatalities.

💡Germ theory

The germ theory of disease suggests that many diseases are caused by microorganisms that are too small to be seen with the naked eye. In the video, the germ theory is mentioned as a foundational concept in understanding how diseases spread, particularly those related to waterborne pathogens.

💡Cholera

Cholera is a severe diarrheal disease caused by the bacterium Vibrio cholerae, which is often transmitted through contaminated water. The video script recounts historical outbreaks and the role of clean water in controlling the disease, illustrating the historical context and ongoing importance of water treatment.

💡Sanitation

Sanitation refers to the infrastructure and hygiene practices that prevent human contact with human excreta, which can contain pathogens. The video touches on sanitation as a critical factor in reducing waterborne diseases, linking it to the broader theme of environmental health.

💡Pathogens

Pathogens are disease-causing microorganisms, such as bacteria, viruses, and parasites. The script discusses how pathogens can contaminate water sources, leading to outbreaks of diseases like cholera and typhoid, emphasizing the need for effective water treatment processes.

💡Sand filtration

Sand filtration is a water treatment process that uses layers of sand and gravel to trap and filter out particles, including some pathogens. The video mentions this process as an early and effective method for reducing waterborne diseases, highlighting its historical significance in public health.

💡Chlorination

Chlorination is the process of adding chlorine to water to kill or inactivate harmful microorganisms. The video script describes how chlorination became a pivotal discovery in water treatment, significantly reducing the spread of waterborne diseases.

💡Typhoid fever

Typhoid fever is a life-threatening bacterial infection caused by Salmonella typhi, often spread through contaminated water or food. The video uses the term to discuss the historical impact of waterborne diseases and the importance of water treatment in disease prevention.

💡NPTEL

NPTEL (National Programme on Technology Enhanced Learning) is an initiative by seven Indian Institutes of Technology and the Indian Institute of Science to provide online courses. The video script mentions NPTEL as the platform through which the course is offered, indicating the modern approach to education and knowledge dissemination.

💡Civil Engineering

Civil Engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including water treatment facilities. The video script positions civil engineering as crucial in addressing public health issues through effective water and wastewater treatment.

Highlights

Introduction to the water and wastewater treatment course by Bhanu Prakash from IIT Roorkee.

Course relevance highlighted by its status as a core UG civil engineering course.

Importance of water and wastewater treatment emphasized through its impact on public health.

Data presentation on the top 10 causes of death in India, with a focus on diarrheal diseases.

Discussion on the significant role of waterborne diseases in infant mortality rates.

Historical context provided by the germ theory and its evolution in medical understanding.

Ignaz Semmelweis's pioneering work on hand hygiene in medical practice.

The tragic resistance faced by Semmelweis for his findings on infection control.

The role of prejudice and lack of scientific temper in public health crises.

Case study of 'Typhoid Mary', illustrating the concept of healthy carriers of disease.

John Snow's investigation into the London cholera epidemic and the significance of water quality.

The impact of sand filtration and chlorination on reducing waterborne diseases.

Graphical representation of cholera outbreaks and the effectiveness of preventive measures.

Historical data on typhoid fever cases and the role of filtration and chlorination in controlling them.

Engineers' contribution to medical revolutions through advancements in water treatment.

Challenges in India regarding diarrheal diseases and the potential for improvement through knowledge dissemination.

The course's aim to enhance the quality of life through better water and wastewater management.

Transcripts

Hello everyone welcome to the first lecture session for the course water and wastewater

treatment.

It is a UG course.

And I am Bhanu Prakash from the Department of Civil Engineering at IIT Roorkee.

So let us get this started without much delay.

First aspect I guess is.

I want to thank Dr. Bill Bachelor of Texas A and M who from whom I learned many aspects

including this particular course to right first I would like to do that.

And I would like to move on to the relevant aspects.

But first why why are we discussing this course?

Or what is the relevance water and wastewater treatment?

Obviously one answer is that you know it is typically mentioned as core course for UG

civil engineering students and that is you need to take that but other than that again

why is it listed as a core course?

And you know why this hullabaloo?

I guess right.

So let us look at some data here to understand why it is that we need to pay attention or

understand the aspects that we are going to discuss in this course.

So in this slide I have top 10 causes of deaths again here this is for all ages and this data

was collected between 2010 and 2013.

And obviously it goes without saying that here I am talking about India rates right.

And typically I provide the relevant link or the source from which I gathered the data

at the at the end of the slide right are the lower portion of this slide pardon me.

But if I do not and you still required the data you can always email me right.

So one aspect here I guess is my email [email protected] obviously you are going to have the TAs who

are going to assist you and answer your queries in the discussion groups.

But whenever you want to draw something to my attention on your response pronto you can

email me right.

So one other aspect is that this is a 30 hour course.

I believe that is going to be relevant for 4 credit if I am not wrong at least that is

the system in IIT Roorkee.

So you should check what it is what the credit equal and credits are for your particular

curriculum.

That is right and again as I mentioned this is an UG course.

Right you will have TAs who will assist you and will have home works.

And one other aspect that I wanted to mention here is that you know you have to register

via the NPTEL portal.

And if you want to take the exam obviously you know register for the exam to why I mentioned

is some students here they enrolled or took permission from IIT Roorkee website to enrol

in the NPTEL course without actually enrolling there via the NPTEL website.

And they were caught between IIT Roorkee and NPTEL once the deadline passed so enough of

that.

So let us move on here we are talking about top 10 causes of deaths all ages.

So obviously India sedentary lifestyles you know high carbohydrate and fat rich diet.

So cardiovascular diseases prime cause 23% obviously relatively more in males I guess

right?

And then we ill defined symptoms respiratory diseases yes related to air pollution typically

some this aspect too is also related to pollution increasing numbers of malignant tumours and

such.

But one aspect I guess that I want to mention at least that is relevant to this course right

away is the diarrheal diseases.

We see that even when we consider all age groups not just the relatively more susceptible

age.

people are the part of the population we see that diarrheal diseases leading to what to

save the death of 5% of our population right?

And then obviously you have other aspects.

But if we look at the relatively more susceptible

Fraction or parts of the population?

What do we have here?

Again the data that we have is top 10 cause of death but from for the ages 1 to 4.

And here you see that diarrheal diseases you know contribute to almost 18% deaths.

That is right 18% deaths.

And then again you have other diseases too but again we are going to look at diarrheal

diseases in greater detail.

We will see why I guess.

And one aspect to note is that the top 10 causes covered 91% deaths under this age group.

As you see all of the remaining calls it is just almost 9% or such.

So top 10 calls itself lead to what is it now 90% deaths and that is something to note.

And we also see that top 3 causes meaning pneumonia, diarrhoeal diseases and injuries

are responsible for more than 50% deaths.

And the reason that I guess I keep reiterating this particular aspect about diarrhoeal diseases

is that you know they are typically waterborne diseases . And it is easy to tackle and you

know save the lives of lakhs and lakhs of children every year.

Again will come back to that.

But one aspect as you see this infants who are relatively more susceptible are dying

in great numbers certainly due to diarrhoeal disease.

But once the relevant time and once the body has developed and has gotten used to the surroundings

or the environment where we are with respect to diarrhoeal disease we still see that diarrhoeal

disease occupies a place of infamy here a high place of infamy and it is still around

12%.

Earlier I guess it was around 18%.

And now it is around 12%.

So even in children that is not just in infants we see that you know what is it now the diarrhoeal

diseases?

12%?

I guess right so that is considerably higher.

Again let us look at some other data before we move on.

So three infants die every 2 minutes.

In India again this is with respect to India.

Why is that lack of access to clean water?

I should have mentioned clean water sanitation right and nutrition and other aspects.

But that is outside the scope of our course.

So we are not going to go into that.

And how many 8 lakh infant deaths were reported in India keep in mind that they are reported.

And again we are still a developing country our Government machinery is yet to capture

all the relevant aspects.

That is your cover all areas.

So I would think that we might probably be under reporting these deaths but to what extent

I guess that is up in the air the lowest in 5 years.

So one good aspect is that is decreasing.

But the infant death numbers are still the highest in the world.

Again this is with respect to this particular report now right?.

So that is something for you to look at.

So just to look at where we are whom we can compare ourselves with note that this is the

highest in the world but again this is not normalised as this is not per 1 lakh population

or sorry this is for the total population I guess.

So again we are accompanied by Nigeria 4,66,000 and then Pakistan and Congo right.

Obviously these are not normalised values.

So obviously you know the numbers might these numbers at least I guess should not be used

to draw petty or simplistic conclusions.

But one aspect to note that is that still we are pretty high in this particular category.

And one other aspect is that Nigeria and certainly Pakistan and Congo they are ravaged by war

or interceding conflict within the country obviously right.

And that is why the numbers are high.

But in our case as you saw you know we have pneumonia and what else please diarrhoeal

diseases contributing to a majority of the deaths and with respect to India we see that

it continues to show impressive decline in child deaths.

And we see that its share of global under 5 deaths for the first time is equaling its

share of childbirth.

Again that is something to note we are getting better compared to where we are ow were Pardon

me.

But still we have a long way to go right.

And germ theory.

And one aspect to know is that you know what is causing these deaths.

Now we know that it is germs pathogens right?

microorganisms which can get into our body and cause trouble to us or lead makers follow

and lead to death or mortality in some cases.

But earlier people did not know that people used to think that it was a bad smell that

used to cause deaths and they used to close their windows and such and think that that

was good enough to keep them safe from diseases.

And typically germs are pathogens which again were not known.

I guess at that time it was supposed to be prevalent only among the dirty population.

Typically when we say dirty I guess when we are talking about society based on class and

such.

Again it is based on income levels right.

But again germ theory here it is one aspect that here is one aspect I would like to point

out to you until the mid 1800s doctors did not bother washing their hands.

They would go dissecting a cadaver meaning a dead body which I guess they used to investigate

because at that time I guess science was not as developed as it is now.

And we were still learning about the human body and such.

So doctors would go directly from dissecting or dissecting a cadaver to delivering a child

that is right again without washing their hands.

Then Hungarian medic Ignaz I guess made an essential much resisted though we will see

why much registered breakthrough What is that about?.

So he was working in the Vienna General Hospital.

So he observed that the deaths from the dreaded child fever child bed fever in the doctor

led maternity ward were significantly higher than the midwife run clinic in the same hospital.

So in one in the same hospital you have two clinics right?

And one doctor led and the other midwife led and the number of deaths in this particular

doctor led ward was much higher.

So again keeping please note that germs were yet to be discovered.

And as I mentioned earlier people believed that disease was spread by bad smells in the

air which came from corpses sewage or vegetation right.

So trainee doctors at Vienna General what would they typically do?

They were dissect corpses and morgue to find out the reason or cause for disease and then

without washing their hands or such go to the maternity ward to deliver a baby.

Right?

So Ignaz he hypothesised that cadaverous particles he did not know what yet you know something

to do with cadavers from the morgue work to blame and that such particles on the hand

so the carrier was not in the air or such.

But something that was being carried by the doctor supposedly these noble what we say

people right again based on the professional work themselves the carriers of death from

one place to the other at least in this context.

So again where are we and that such particles are in the hands of doctors who are making

their way into the woman's bodies during death leading to death of the woman?

right?.

So he ordered the doctors to wash their hands and instruments in a chlorine solution.

Why chlorine?

Now we know that it is a good oxidising agent.

But at that time I guess the reasoning was unclear but it was a substance he hoped would

dispatch the deadly smell of the cadaverous particles note that chlorine has a pungent

smell.

So after this particular implementation of hand hygiene habits you know between the morgue

and the delivery room the rate of mortality for new mothers dropped drastically from 18%

to 1%.

But do people did people accept him or you know appreciate his findings or contributions

not that again people are typically not driven by science we are not in a society at least

not yet the world over where people have a scientific temper now right typically emotions

ego and such come into play.

So when Ignaz more or less you know suggested that doctors this noble people called are

acting as carriers of disease you know he was ridiculed and such.

So majority of the doctors in this time were from middle or upper class.

And they thought of themselves as very clean people again different aspects but I am not

going to go into that compared with the working class poor . Doctors were offended that they

could cause infections.

And he met a tragic and he has in our Ignaz Mr. Ignaz or Dr. Ignaz face great resistance

and met a tragic when he first lost his job and had a mental breakdown.

And he died at a relatively younger age of 47.

In a psychiatric institution this always happens in society when you know you are trying to

preach something radically new either with respect to science but obviously at that time

even Europe or the relatively more developed countries or western countries too did not

have scientific temple.

But now the situation improved there.

But again here I am talking about acceptance of an idea based on the scientific data or

the reasoning out there right.

So that is what was lacking at that time.

And obviously he was ridiculed.

But much later you know people started accepting or accepted the germ theory.

And what is this theory about?

It is that certain diseases are caused by the invasion of the body by microorganisms

these which are too small to be seen except through a microscope and obviously the people

Louis pasture right pasteurisation of milk and such you would have heard of this.

This person Joseph Lister the surgeon who more or less looked at disinfection I believe

all of the relevant surgical tools and such they got the credit for this particular theory.

But again this is what we observe again that is in society.

And I wanted to put that out there right?

Again the source you can look that up.

And one other aspect is you know how people think and act during pandemics and how prejudices

play a role.

Even during Corona we had people from particular community being targeted due to various reasons.

And then the poor who had no recourse to either good medical facilities or could not or those

who could not fall back on bank deposits or such to live what we say hermit like life

they were thrown out of most people's homes you know people they were not given their

monthly wage and they suffered a lot.

But again these prejudices always come into play during pandemics right?

Again that is something to keep in mind.

But here I have one particular case you know with respect to typhoid . Until then the world

did not know that healthy people could act as carriers.

I am healthy I have no symptoms, visible symptoms are such if not visible no fever or any such

symptoms.

But people did not know that you know a person like me could be a carrier of a particular

pathogen . So here we have someone here who was vilified

as typhoid Mary right.

And I guess we I have the picture from here and the article from the Hindu outlet.

Right.

So she was a cook.

And you know at that time there was an outbreak of what is it now typhoid related fevers and

deaths obviously and a private detective finally you know tried to solve the puzzle or rather

was able to solve this puzzle and linked her and forcibly made her you know are tested

her for this particular what do we see a pathogen that causes typhoid.

And then you know that was the first time people came to know that you know healthy

People can act as a carrier but people do not take it that way right.

So the quarantine her thinking that she was an oddball or case they will find her as typhoid

Mary.

And then they quarantined her for 26 years.

I am not going to draw the obvious comparisons with what is been happening in these couple

of months?

Please note that I am recording this lecture in 2020.

October.

And you know what is been happening with respect to the Coronavirus?

How people have been prejudiced against their own neighbours let's say people working with

them or for them and so on and so forth.

So again more or less the root cause of such issues is that prejudice and lack of scientific

temper but again what happens slowly but surely science catches up right.

Again here I have an aspect I will come back to this.

Data?

So there was a cholera epidemic in London right?

And it was discovered in 1854.

Anyway right it was spreading through water in London.The outbreak seemed less severe

in areas where sand filters were installed.

And the scientist John Snow found that the direct cause of the outbreak was water pump

contamination by sewage not sewage water.

So they had what was called a cesspit, suspect meaning you know your septic tanks where sewages

is collected and typically undergoes anaerobic degradation.

So suspects were common at that time obviously but they were believed the home and they were

taken to the River Thames and such.

So in that particular location though the sewage or not the sewage faeces lead to contamination

of the drinking water but not that the water does not taste different does not smell different

and the colour too colourless mixes so visually or with the primary senses people were not

able to distinguish it.

So what is it that he tried to do looking at this particular data he tried to disinfect

the water with chlorine.

since the water pump water in the pump tasted and smell normal.

The conclusion was that good taste and smell alone do not guarantee safe drinking water

and this was a deal breaker at that time.

Again people did not accept the findings of Dr. Jon Snow at that time.

But much later people started accepting sand filters and chlorination as a way to treat

and disinfect drinking water.

Again keep in mind that this was in 1854 germ theory two came about later and such let us

right.

(Videos Stars: 19:33) So for example here I have a graphic from

Wikipedia the source for which is given out here.

So from here you have the number of deaths with cholera as a cause this is London outbreak

the one in 1854 that we are just talking about.

So you see that it is relatively more concentrated in this particular area I guess.

No okay.

And this area and so again as I mentioned the person who will not pile up the statistics

or the data.

And what did he observed he observed that this particular pump was cause.

And also he observed that among the 2 water distribution or supply companies for those

people who are taking water from a particular company where you know falling ill more often

than to with respect to cholera . Why is that?

So this particular company number one ,I do not remember the name was taking water from

that part of Thames River into which people used to dump their sewage right.

So people did not want to have the sewage piling up near their home.

So they used to dump it into the river.

And at that time obviously the thought process was that it was through this.

I mean this is spread through the what is it air right.

And people did not understand that clear water which tastes and smells fine can also or acts

as a carrier of these pathogens.

So the company that was supplying this water the company or the people who are being supplied

by the water from this company fell ill more often.

And the other company which was taking water from upstream of the point of pollution are

relatively clear or unpolluted source they people those people did not experience as

many casualties or cases of cholera here?

(Videos Ends: 21:13)

So again this is one of the original data I guess I think this is from Wikipedia.

So again he stacked up such data in stacks original map by Jon Snow showing the clusters

of cholera cases indicated by this tag rectangles.

So here is the pump and you see that there is greater incidence of cholera you know in

that particular region.

So what did he do?

He took out that particular handle out there right.

So that is something to keep in mind Cholera again what is that look like?

It looks like gamma shaped I guess it is gamma shaped bacteria right?

Vibrio cholera infection right?

This is what we have now and slowly but surely though people started understanding.

But slowly again why is it because people are not typically very much ready to accept

data that flies in the face of their assumptions or what we say wisdom passed down generations.

People typically think that whatever was told in the past is what we say the God given truth

without typically applying logic or reasoning . Let us move on here.

So you are one aspect to note is that.

We looked at what is it now sand filtration.

And they do not present the data here.

Typically sand filtration alone brought down the number of cases of cholera by 50%.

So let us look at what we have here.

I have different process based on separation, separation process meaning at least in my

childhood we used to have what we say a cloth and we used to have.

And the cloth obviously used to act as a filter what are we trying to do we are trying to

remove those particles that are bigger in size than the pore size of this particular

cloth . Or the filter size of that particular cloth.

So here we have different suppression process based on relatively similar principle other

than with respect to reverse osmosis.

We have conventional filtration meaning with respect to activated carbon sand or such micro

ultra nano these came much later but let us concern ourselves with conventional filtration.

And here we have the relative sizes of different salts or viruses or pathogens of concern and

obviously molecular weight is given.

As the size decreases molecular weight approximate obviously decreases right and the size particle

range also decreases.

Here we have the size in micron right?

And what we see out here you know sand particles can be removed obviously by sand filtration.

And we see that a considerable fraction of bacteria can be removed from sand filtration

and that is what we see out here.

So the simple act of filtration will be able to remove a considerable fraction of bacteria

but not viruses obviously that is something to keep in mind versus just RNA right.

So that is one aspect to keep in mind.

So what we have out here.

We have typhoid fever cases per 1 lakh population from 1890 to 1935.

In Philadelphia okay.

And the case of who has this poor Lady Mary is typhoid Mary I guess right.

This was case in I believe New York or such she was the poor lady who was quarantined

for 26 years later on again healthy carriers also were identified but again she bore the

brunt of people's What can I say pent up anger if I may say so.

So what do we have here?

typhoid fever cases per 1 lakh population from 1890 to 1935 . So what do we have here?

Number of by typhoid cases you know they started going up you know relatively more what we

say densely packed societies or how your what we say population densities.

So greater sewage in that particular area sewage leading to what we say transmission

of disease into what we say the human beings water.

So that is what we see increasing cases.

But then people figured out that filters can be used.

And obviously you see a drastic decrease.

And then chlorination was discovered as a very effective way to disinfect.

And obviously what do we say treat the water for pathogens?

And then you know remarkably less I guess and at this point I guess carriers were discovered

and that this is why I guess you know it is written.

Into various journals and such that the greatest medical revolution of this previous century

was not by doctors but by engineers I guess.

So that is the reason why I guess we are going to look at this course in greater detail.

right.

As an in India we see that the cases due to what we see diarrhoeal deaths and such are

the deaths due to diarrhoeal and search are still remarkably high.

And we saw the case of the relatively more developed countries as in they went through

the same phase but that was relatively earlier.

But now we have a different challenges right infrastructure is an issue.

But again with respect to you know dissemination of knowledge this is what we are trying to

do now.

So with such dissemination of knowledge the hope is that we are going to be able to have

a better what we say quality of life for our citizens and humanity in genera right.

So how life expectancy in the USA but I am almost out of time.

So I will continue this in the next session.

And I thank you for your patience.