and for the past 14 years

I've been teaching crap.

(Laughter)

Not that I'm a bad teacher,

but I've been studying and teaching

about human waste

and how waste is conveyed

through these wastewater treatment plants,

and how we engineer and design

these treatment plants so that we can protect

surface water like rivers.

I've based my scientific career

on using leading-edge molecular techniques,

DNA- and RNA-based methods

to look at microbial populations in biological reactors,

and again to optimize these systems.

And over the years,

I have developed an unhealthy obsession with toilets,

and I've been known to sneak into toilets

and take my camera phone

all over the world.

But along the way, I've learned

that it's not just the technical side,

but there's also this thing called the culture of crap.

So for example,

how many of you are washers

and how many of you are wipers?

(Laughter)

If, well, I guess you know what I mean.

If you're a washer, then you use water

for anal cleansing. That's the technical term.

And if you're a wiper,

then you use toilet paper

or, in some regions of the world

where it's not available, newspaper

or rags or corncobs.

And this is not just a piece of trivia,

but it's really important to understand

and solve the sanitation problem.

And it is a big problem:

There are 2.5 billion people in the world

who don't have access to adequate sanitation.

For them, there's no modern toilet.

And there are 1.1 billion people

whose toilets are the streets

or river banks or open spaces,

and again, the technical term for that is

open defecation,

but that is really simply

shitting in the open.

And if you're living in fecal material

and it's surrounding you, you're going to get sick.

It's going to get into your drinking water,

into your food, into your immediate surroundings.

So the United Nations estimates

that every year, there are 1.5 million child deaths

because of inadequate sanitation.

That's one preventable death every 20 seconds,

171 every hour,

4,100 every day.

And so, to avoid open defecation,

municipalities and cities

build infrastructure, for example, like pit latrines,

in peri-urban and rural areas.

For example, in KwaZulu-Natal province in South Africa,

they've built tens of thousands of these pit latrines.

But there's a problem when you scale up

to tens of thousands, and the problem is,

what happens when the pits are full?

This is what happens.

People defecate around the toilet.

In schools, children defecate on the floors

and then leave a trail outside the building

and start defecating around the building,

and these pits have to be cleaned

and manually emptied.

And who does the emptying?

You've got these workers

who have to sometimes go down into the pits

and manually remove the contents.

It's a dirty and dangerous business.

As you can see, there's no protective equipment,

no protective clothing.

There's one worker down there.

I hope you can see him.

He's got a face mask on, but no shirt.

And in some countries, like India,

the lower castes are condemned

to empty the pits,

and they're further condemned by society.

So you ask yourself, how can we solve this

and why don't we just build Western-style flush toilets

for these two and a half billion?

And the answer is, it's just not possible.

In some of these areas, there's not enough water,

there's no energy,

it's going to cost tens of trillions of dollars

to lay out the sewer lines

and to build the facilities

and to operate and maintain these systems,

and if you don't build it right,

you're going to have flush toilets

that basically go straight into the river,

just like what's happening in many cities

in the developing world.

And is this really the solution?

Because essentially, what you're doing is

you're using clean water

and you're using it to flush your toilet,

convey it to a wastewater treatment plant

which then discharges to a river,

and that river, again, is a drinking water source.

So we've got to rethink sanitation,

and we've got to reinvent the sanitation infrastructure,

and I'm going to argue that to do this,

you have to employ systems thinking.

We have to look at the whole sanitation chain.

We start with a human interface,

and then we have to think about how feces

are collected and stored,

transported, treated and reused —

and not just disposal but reuse.

So let's start with the human user interface.

I say, it doesn't matter if you're a washer or a wiper,

a sitter or a squatter,

the human user interface should be clean

and easy to use, because after all,

taking a dump should be pleasurable.

(Laughter)

And when we open the possibilities

to understanding this sanitation chain,

then the back-end technology,

the collection to the reuse, should not really matter,

and then we can apply

locally adoptable and context-sensitive solutions.

So we can open ourselves to possibilities like,

for example, this urine-diverting toilet,

and there's two holes in this toilet.

There's the front and the back,

and the front collects the urine,

and the back collects the fecal material.

And so what you're doing is you're separating the urine,

which has 80 percent of the nitrogen

and 50 percent of the phosphorus,

and then that can then be treated

and precipitated to form things like struvite,

which is a high-value fertilizer,

and then the fecal material can then be disinfected

and again converted to high-value end products.

Or, for example, in some of our research,

you can reuse the water by treating it

in on-site sanitation systems

like planter boxes or constructed wetlands.

So we can open up all these possibilities

if we take away the old paradigm of flush toilets

and treatment plants.

So you might be asking, who's going to pay?

Well, I'm going to argue that governments

should fund sanitation infrastructure.

NGOs and donor organizations,

they can do their best, but it's not going to be enough.

Governments should fund sanitation

the same way they fund roads

and schools and hospitals

and other infrastructure like bridges,

because we know, and the WHO has done this study,

that for every dollar that we invest

in sanitation infrastructure,

we get something like three to 34 dollars back.

Let's go back to the problem of pit emptying.

So at North Carolina State University,

we challenged our students to come up with a simple solution,

and this is what they came up with:

a simple, modified screw auger

that can move the waste up

from the pit and into a collecting drum,

and now the pit worker

doesn't have to go down into the pit.

We tested it in South Africa, and it works.

We need to make it more robust,

and we're going to do more testing

in Malawi and South Africa this coming year.

And our idea is to make this

a professionalized pit-emptying service

so that we can create a small business out of it,

create profits and jobs,

and the hope is that,

as we are rethinking sanitation,

we are extending the life of these pits

so that we don't have to resort

to quick solutions

that don't really make sense.

I believe that access to adequate sanitation

is a basic human right.

We need to stop the practice

of lower castes and lower-status people

going down and being condemned to empty pits.

It is our moral, it is our social

and our environmental obligation.

Thank you.

(Applause)