Think of a substance with a sight and smell that disgusts us.
Something we're hard-wired to avoid.
But look beyond our disgust and we might see it's a substance
with amazing potential to be the ultimate renewable resource,
capable of solving some of humanity's greatest challenges.
Its gases have the potential to generate power.
It's full of nutrients that are essential to agriculture.
And it contains medical secrets that could transform health care.
I'm talking about human waste, about sewage.
I'm Dr George McGavin.
With exclusive access to one of Europe's
most advanced sewage works,
I'm setting out to prove that poo could be priceless.
It's black gold, isn't it, really?
Uncovering how a revolution in the science of human waste
could transform our lives.
So you could supply gas to 28,000 homes.
Bold enough to join me on this quest
is materials scientist Dr Zoe Laughlin.
It doesn't smell in any way disgusting.
I want to get up close and personal with what we flush away...
It's just like a horror hatch into raw sewage. It's not pleasant.
..to get to grips with exactly what's in it... Oh!
..and discover the mind-boggling microbiology being used to clean it.
Oh! Wow! It's massive!
Look at it.
With a pop up lab based at this sewage works,
we're even going to search for new life in sewage
that could have amazing medical properties.
You have discovered a biological entity
which is potentially a life-saver.
Every new one that we find is another patient
that we can potentially treat.
Join us on an incredible journey into a hidden world
where we face up to our faeces
and uncover the secret science of sewage.
Pretty much all of us will flush something down the toilet
several times a day.
Our developed world affords us the luxury
of never having to think about it again.
A cistern full of water carries the unmentionable "it" away
into a hidden network of pipes.
But where is "away"?
What we flush has to go somewhere.
And that somewhere is a place like this.
This is Minworth Sewage Works on the eastern outskirts of Birmingham.
Run by Severn Trent Water, it's one of the biggest in the country,
a square kilometre of pipes and pools dedicated to processing
the waste water of Birmingham and the Black Country.
Every day, it's on the receiving end
of 1.7 million people's faecal matter.
This massive treatment plant is the ideal place
to investigate how stripping resources out of sewage
can turn it back into water clean enough to return to the environment.
We're going to take you through each stage of the process, beginning
at the point where the raw sewage arrives on site - the inflow.
Which is where I find Zoe.
Zoe, I'm feeling rather overwhelmed now.
Our job is to persuade people that this is a valuable resource.
It's absolutely disgusting, but I can't take my eyes off it.
It gives a whole new meaning to Poohsticks!
HE GUFFAWS
At peak flow, this is 12, nearly 12,500 litres a second.
That's a billion litres a day.
But it hasn't rained for days, so this is just normal toilet
flushing... It's regular... ..and drains on the roads, yeah.
Regular sewage. Regular sewage.
This isn't a storm flow.
I mean, this is just humanity.
This is just the waste product of a large number of people.
That's all it is.
But when we say raw sewage, what do we mean?
What does it actually comprise of?
Perhaps what few of us realise is that sewage plants
don't just deal with human waste, it's all the water we use.
Anything that goes down the sink, from the dishwasher, the washing
machine, the shower, the bath,
anything that ends up in the drains, all of it.
So what's in this disgusting torrent that's a resource?
And what things shouldn't be in there at all?
To find out, Zoe's set up a demonstration at our pop-up lab
to deconstruct sewage.
What I've got here, George,
is a tank that can hold up to 140 litres of water.
Now, that's the volume of how much one person uses every day.
And send it to the sewage treatment plant.
And we send it full of muck.
And what I'm going to do to it is add in all of the things
that we put down the drain over the course of a day.
30% of household water is used for flushing toilets.
So that's where we'll start.
This is two litres of urine.
This is what an average adult would produce... All righty.
..you know, in a day, if you're well hydrated. Yeah, all right.
In this instance, this is apple juice.
And that contains lots of nitrogen, uric acid, urea, creatinine,
all those things that are very rich in nitrogen
which you have to get out of your system.
Time for a poo. Time for a poo. Time for a poo.
The average adult produces one poo a day of 250g in mass.
Ha!
This is soya bean paste, which is an industry standard
for simulating turds in a toilet.
So I'm going to put in... 250g. ..250g.
231. Not bad. Not bad. Not bad.
In fact, this is quite wet, which isn't far off
what a real poo would be like, because 75% is water.
And then, of the stuff that's not water,
you've got half of that just as biomass, really.
So, bacteria and... And protein. ..protein, fat.
If you've got too much fat in your diet, you'll get the floater.
The protein and biomass in poo equals potential energy,
but as a possible resource, it's now massively diluted.
This amount of poo and pee in this much water
means that human waste makes up less than 2% of raw sewage.
There's something marginally convincingly gross about it,
now it's in the water especially.
But we also add around 25g of toilet paper.
The school of wrap it round the hand, which is bad for the plumbing,
but it is a natural way in which people go.
An average person uses 50 sheets a day.
This is predominantly cellulose.
So this is a natural fibre which will break down pretty easily.
Another 30% of our water use is from the bathroom sink and shower,
over 40 litres worth.
On average, we each add an estimated 30ml of personal hygiene
products a day.
There's a bit of shower gel.
One. Oh, and I did wash my hair.
Shampoo.
Toothpaste. There we go.
These all contain surfactants,
chemicals that act as foaming agents.
Along with sodium hypochlorite in bleach,
these elements will be diluted and break down.
Around... That'll do.
Water use in the kitchen makes up a further 30% of sewage.
And here we can add up to 50ml of detergents
and cleaning agents.
Oh!
All these products are designed to break down in water,
but not everything that we pour down the sink will dissolve.
Sort of sauces and oils on plates definitely go in.
In particular - fats.
And that's what you shouldn't put down the drain, really.
No, but when it's a liquid state, you can see how people do.
Yeah, yeah.
What we can see here is how crucially
the molecular characteristics of fat prevent it dissolving in water.
And in a sewage pipe, it can congeal, causing fatberg blockages.
Once it sort of hits the sewer system,
the turbulence of the flowing water churns it up.
So to simulate that...
Wow, that is...that is a mixer. ..I get the big blender.
BLENDER WHIRS
So now, it's starting to go browner.
Wow! The turds are definitely being agitated.
That's what I like to hear. Yes.
Right, there we go. I want to compare what we have created,
what you have created,
to a bottle of intake water,
which we got from the plant.
And, you know, it's... Not far off. It's not far off, is it?
At the beginning, this was a valuable resource.
It was clean, safe drinking water.
And now I've just come along and contaminated it and made a problem.
But in that problem are, there's energy,
there's minerals that can be reclaimed.
There's stuff in here that's worth having.
But imagining there's stuff in sewage worth having
goes against every natural instinct we have towards it.
We are disgusted by faeces.
It's a socially evolved behaviour.
Babies will play in it, but we learn that excrement is dirty,
it makes you ill.
Scientifically, we know that sewage teems with harmful bacteria
like salmonella and E.coli.
Even traces of Covid-19 have been detected in it.
We pass it out in our poo.
Our bodies are designed to get rid of it.
But does that mean that all viruses and bacteria in us
and in sewage are bad?
Now, this is where the science of shit gets really fascinating.
The bacteria in our intestines, the gut microbiome or flora,
number not in their millions and billions, but in their trillions.
And science is just beginning to understand it.
The bacteria in our gut are a complex and unexplored universe,
individual to each of us.
Yes, they help us digest our food,
but they also protect us from diseases.
There are particular types of bacteria in our intestines
that kill off harmful pathogens.
But when we get sick, often, conventional health care's
default response is to treat us with antibiotics.
This can kill off all the bacteria in our gut, good and bad,
sometimes leaving us even more vulnerable to disease,
especially superbugs.
Just a tiny sample of poo contains millions of unknown good bacteria
and even viruses capable of fighting off disease.
And this is where sewage has the potential to offer
one of the most counterintuitive resources imaginable.
Medicine.
I'm being joined by a true pioneer of the science of sewage,
Dr Ellie Jameson.
And right now, this world-class scientist is, rather bizarrely,
fishing in sewage for a nanoscopic organism she calls a phage.
So this is where the sewage first comes into...
Oh, I've just got a bit of lumpy stuff in there.
..into the sewage works.
This is where all the bacteria and the phages are.
This is an enhanced photograph of a phage
taken with a powerful electron microscope.
It's an entity so small, it's measured in nanometres,
a millionth of a millimetre.
What is a phage?
So, it's a virus which only infects bacteria.
So, it can't kill any plants or animals,
but it will kill the bacteria.
Why do you want to work on phages?
What use are they to us?
Well, to us, so I'm interested in bacteriophages
which kill superbugs.
So the superbug that I'm interested in is klebsiella,
and that's becoming more of a problem in hospitals.
It's causing pneumonia infections and causing urinary tract infections
which can go on to cause septic shock as well.
Superbugs like klebsiella and E.coli are bacteria
resistant to antibiotics.
But science has discovered that phages will act against them.
How do they attack a bacterium?
So, first of all, they've got little receptors on the legs,
so these bits which come down, like the lunar lander,
so the bit which would land on the moon first, like the legs,
which recognise the bacteria. Right.
And when they stick to a protein that they recognise,
they bind to that and then they can inject their DNA or RNA
inside that bit. Straight into the bacterium? Yeah.
And that basically takes over the bacterium completely. Yeah.
And that will help us to treat infections that we currently
aren't able to treat.
Yes. So, especially in klebsiella, there's a lot of klebsiella
which pick up antibiotic resistance,
and there's some which are multidrug resistant as well.
So resistant to all the common antibiotics that we use.
So by using bacteriophage, these will kill the bacteria,
but also they'll help our existing antibiotics to work better
so we can use them in combination with antibiotics to cure a patient.
So instead of killing off everything in your gut,
like when you have antibiotics, they will just target the thing
which is causing the problem in you
and leave all the other bacteria intact.
Science has known about the existence of bacteriophages
and their therapeutic properties for decades.
But the targeted hunt for them in sewage as an alternative
to antibiotics is a relatively new approach.
This is a churning mass of all sorts of bacteria and viruses,
and out of that soup, you want to extract something
that could be the next wonder drug.
Yeah, that's what we're looking for in here.
There could be loads of things in there that nobody's ever seen before
that could kill the next bacteria which are going to cause problems.
So it's really interesting to find out about these things and get
as many as we can, the different ones to help us to help medicine
and improve the future of medicine.
Ellie's returning to her laboratory for now,
where she'll clean up and analyse her sewage sample for phages.
I'll catch up with her later to see if she's found any
and if they're active against any superbugs.
Meanwhile, Minworth's never-ending torrent of sewage keeps on coming.
And I want to get a closer look at the engineering systems
being used here to process it.
The material science and engineering challenge here is staggering,
bearing in mind that sewage is always flowing and waste water
always needs cleaning.
I want to see where this process begins.
A secret of sewage science
is to always keep the effluent moving.
The architecture of the plant channels the waste water
from where it arrives at the inflow towards stage one of the process,
an area known as the screens.
This set of massive structures are the first point
of sewage filtration.
Keeping the system operational is technician Andy.
Oh, my God.
Andy, what I'm actually... Is this the raw sewage coming in?
Yes, this is, this is the raw sewage coming through these screens.
The flow, everything comes down the drains, through the kitchens,
toilets, comes through here until it hits one of the screens over here.
I can see lumps of brown. Anything that goes down the drain.
Inside the screen structures are angled caterpillar-track-like sieves
constantly rotating.
The sewage flows into the lower part of the track.
Large solid objects like plastics are lifted to the top
and fall into the collection bin below.
But anything liquid or small enough, including poo particles,
pass straight through the 6mm size holes in the sieves.
You'll be amazed how many car wheels come down here, and tyres.
There's a football that we took out this morning.
There's a basketball in one of the ones over there,
which we will get round to later.
I want to take a closer look at the inner workings of these screens.
But as Andy opens the inspection hatch,
the true horror of the sewage system is revealed.
Oh, hell's bells.
Wet wipes.
As you can see, most of this, a lot of these are wipes.
That is... Wet wipe, wet wipe.
A little bit of plastic.
So it's not... The cellulose of toilet paper isn't the problem,
it's the heavy weave and the denseness of the wet wipe.
That's right. It doesn't, it doesn't break up.
It just shreds into smaller pieces, which don't go through the screens,
they end up here.
Wet wipes have only become an issue in the last 20 years.
Now, nearly 15 billion are used in the UK every year
and many get flushed, contributing to 75% of all sewer pipe blockages.
And actually, the closer you look, the more you see,
there's a huge amount of human hair, almost felting it all together.
Wow.
It's just like a horror hatch into raw sewage.
It's not a pleasant... No. ..view, no.
How long have you worked here? 17 years.
Do you feel like you've become used to it?
Is there something...? What's your immune system like?
When you open it up and see a dead rat hanging by its tail,
no, it's still a bit of a shocker.
The sewage passing through the screens
is now a filthy, sieved soup.
With all the elements mixed together,
it's harder than ever to see this as a resource,
especially for generating power with.
And why even go to the effort?
The answer is, we need to.
With fossil fuels unsustainable,
renewable energy sources offers a solution to powering the planet.
Wind and solar can be unpredictable.
But sewage is constant.
In the UK, we produce 11 billion litres of it a day.
The single biggest volume of human waste we produce is urine,
two litres a day each, and it's rich in minerals.
So do these minerals have a value as a resource?
And could we use them more efficiently instead of flushing them
into the sewage mix?
Could there ever be such a thing as pee power?
I've come to Bristol, where an incredible new biotechnology
has been developed, one capable of generating clean energy
from a resource we all produce.
Time for me to spend a penny.
Partly because I need to go, as a gentleman in my vintage often does,
but more importantly because I need to charge my mobile phone.
This is going to power my phone.
I've come to a state of the art research facility
full of mysterious wired up devices and whirring dials.
But centre stage in this lab is a urinal.
Above it is a circuit board and a phone charger.
I'm told all I have to do is to plug my phone in...
Let me stick it in.
..and pour my pee sample into the urinal.
Honestly, I cannot believe this is going to work.
I mean, it's like one of those things, like, ah!
I have never done this before.
And switch on the current.
Ah, there you are. It's charging.
Wow!
The magic happens round the back in this unlikely looking bank
of battery-like fuel cells.
Its inventor, Professor Ioannis Ieropoulos,
is explaining how these cells work.
This is known as a microbial fuel cell technology.
It's using live bacteria that generate electricity.
So what is in my urine?
What is it in there that they can use?
It contains carbon, phosphorus, potassium,
sulphur, magnesium, creatinine.
And these are elements that the microbes will require
to continue living and growing.
The fuel cells' central tube is porous ceramic
that microbes colonise and urine permeates through.
As elements in urine are consumed, electrons generated by the microbes
are picked up by the cells' opposing wire coils.
Where do the microbes...? Because there has to be particular sorts
of microbes, not just any bug will do.
How do you locate them?
There's a plethora of microbes out in the natural environment
and this is exactly what we have been using.
So what we would tend to do is collect a sample from a pond
or a lake, a river sediment,
bring it in the lab and then put it inside this microbial fuel cell,
which is connected to the circuit that's drawing current
and demanding to have electrons flowing through.
Each fuel cell produces 1.5 volts -
but link together in series like batteries,
and you boost the output.
But Ioannis' vision for this amazing technology goes much further
than a phone charger.
He's scaling it up as a unit that can be built into the fabric
of houses and instantly draw on urine to provide electric power.
If you can imagine just taking a standard brick
and converting it by simply integrating microbial fuel cells
and continuously taking the household waste water,
and then we generate electricity we require for charging devices,
lighting up rooms, DC refrigerators would be the future.
But how far in the future are we talking?
Whilst all this kit might look like a prototype,
Ioannis' technology is very close to being rolled out.
The work has been funded by the Bill & Melinda Gates Foundation,
by the UK EPSRC and by the European Commission.
And from those funders, we have got our objectives
which are to deliver the technology
outside of this lab to the society.
For this technology to benefit UK homes, separate unisex urinals
and plumbing add-ons could pipe pee directly to the cells.
In the quest for diverse energy sources sitting alongside
solar and wind, this has incredible potential,
and there's no doubt it's renewable.
If we have microbial fuel cells in the walls,
then we are tapping on a ubiquitous and never-ending fuel.
It's so exciting. The whole thing is so exciting.
It's just, this is what science should be about, especially now.
Oh, my goodness. We need this stuff.
I couldn't agree with you more.
Well, I absolutely love that.
In terms of what we're investigating,
is there any value in our waste,
this is it answered and realised in a way that is truly inspiring.
You can imagine a future when all of us will have microbial fuel cells
built into the fabric of our homes,
generating power from our pee at source.
But, you know, I can't help wondering if generations from now,
our descendants will think we were totally insane
to simply flush our waste away.
Back at Minworth Sewage Works, the waste we've simply flushed away
is in full flow.
Having come through stage one's screens,
where the largest solid materials are taken out,
the main solid elements left are millimetre sized poo particles
and grease from cooking fats.
But how can any of this be isolated and extracted for use
as a resource from such a finely sieved soup?
Now, the sewage is channelled from the stage one screens
into stage two of the treatment process - the settlement tanks.
There are 22 of these massive circular tanks for the second part
of the processing stage,
and I want to find out exactly what's settling in them.
Compared to the gushing torrent at the inflow,
everything's got rather sedate.
Just like Zoe's demonstration earlier showed us,
I can see fat and grease floating on top of the sewage.
But as Minworth's senior technician Phil explains,
the secret science at this stage
exploits how sewage behaves when it's not flowing so fast.
So it's a very simple idea, heavy stuff sinks to the bottom
and then anything that floats is grease or fats.
Yeah, you get the fats on the rise there, you see in the tanks there.
We have scum traps, so they'll just go into a well
and then we'll take that away.
All the grease will naturally sit on the top.
And the scraper hook paddle it down into there.
And that big bar there is just constantly moving.
Yeah, yeah. Fairly slowly. Yeah, very slow.
But it's below the surface of the sewage in these tanks
that the crucial settlement process of this stage is taking place.
Like sediment in wine, gravity takes effect
and millions of broken up poo particles are simply sinking,
forming a sludge in the tank's conical bottom.
The slowly revolving rake arm scrapes the sludge
into a collection tank below.
The now much cleaner sewage water above
filters over the tank's baffle
and is channelled onto the next stage of treatment.
But what happens with that settled sludge
collecting underneath the settlement tank?
I'm going to get a closer look via an inspection well.
OK. You're prepared? Yeah, yeah. Are you ready? I'm ready.
So far, the smell on site hasn't been that overwhelming,
but the settled sludge absolutely stinks.
Stand back. Well, I think I will, yeah.
Now that the poo has been separated out of the sewage,
gases like hydrogen sulphide are more concentrated.
There's a spicy top note of indole and skatole produced by bacteria
that's particularly offensive.
But there's also a gas in here which is odourless,
one that has phenomenal potential as yet another energy resource -
methane.
The crucial thing about methane is it's volatile
and incredibly flammable.
So is there a way we could somehow extract the methane in here
and exploit it as a resource?
And if so, how?
The sludge from the settlement tanks is piped across Minworth
to 16 giant silos called biodigesters.
Acting like pressure cookers, conditions inside the biodigesters
are engineered to force a bacterial reaction in the sludge,
causing methane gas to be released.
Given that this is a hugely hazardous environment,
this is as close as I'm permitted to get.
But explaining the process is sludge scientist Charlotte.
So, Charlotte, that sludge that I had in a container,
thick like emulsion paint, that stuff is heated...
About 40 degrees, which is optimum for the bacteria to work at.
The sludge is fed in.
On this site it's held at about 20 to 30 days in there.
And that's where the fun starts.
Inside the biodigesters, special bacteria are added to the sludge.
The atmosphere inside the digesters is airless
and along with the temperature, that causes the bacteria to start feeding
on the proteins and carbohydrates in the sludge.
In so doing, the bacteria give off a methane-rich biogas
that rises up in the digesters and is piped off.
It's then injected into the National Grid,
supplementing our supply of natural gas we drill for
in the North Sea and import.
How much gas can it produce?
How many homes could it heat?
Well, last week, George, we actually broke our record where we
was able to power 28,000 homes from what we produced in a day.
28...? 28,000 homes.
So you could supply gas to 28,000 homes? That's correct, yes.
So the person frying their bacon and eggs in the morning
might not be aware that what they're cooking with
is a gas flame that has been produced by what they may have
deposited in their toilet a couple of weeks before.
That's correct, yeah. It's the state of the world.
I love it.
Methane from sewage isn't going to supply gas to every home in the UK,
but it can form part of our diverse suite of renewable energy sources
like wind and solar that we need to provide us with power.
But the beauty of methane or biogas is that it'll fuel more
than just central heating and cookers.
And so, Zoe is heading off on a road trip
to investigate what else poo can power.
What if I told you
we could use it to get from 0-60 in under ten seconds?
Meet the Bio-Bug, a converted VW that runs on methane gas
derived from sewage.
Or as I like to call it - the Dung Beetle.
With government targets committing the UK to net zero carbon emissions
by 2050, I'm keen to see if methane gas has potential
to be a cleaner alternative to petrol and diesel.
I'm meeting sustainable transport specialist Francis Marsh,
who promotes poo power as a viable vehicle fuel.
Considering this was powered by methane gas,
it was a pleasure to drive, but how does it actually work?
Well, it all happens round the back here.
We'll pump in the upgraded biomethane
into the rear of the vehicle at 200 bar of pressure.
And then we've got some gas canisters in the boot here.
It's like you're going to go scuba diving. Absolutely.
So these gas cylinders hold enough gas to go about 200 miles.
And then, is it a normal engine?
Well, if you pop the hood, we'll have a look. Hang on.
OK.
Yeah, I mean, this just looks like most car engines I've seen.
Yeah, absolutely. So it's fundamentally exactly the same,
very few parts that have changed.
So we've got the injectors here that are slightly different,
that's a modification, and then the engine management system,
which is also slightly different.
There's a global push towards electric cars,
but battery technology requires vast amounts of lithium,
which is a finite resource, whereas biomethane is infinite.
So does it generate lower emissions?
Absolutely. So 99% less particulate matter being emitted out of
a tailpipe, 90% reduction in carbon dioxide.
And I suppose being able to fuel vehicles
that would traditionally be quite heavy pollutants like buses
and, you know, dustbin lorries. Yeah, exactly.
That would work in built up urban areas where air quality
is traditionally very poor.
You can save probably around about 150 tonnes of CO2 per year
using a heavy goods vehicle on this fuel.
So this is a way in which you could actually tackle the most polluting
type of vehicle and not scrap the whole vehicle,
just convert the engine and run a much cleaner journey.
Yeah, absolutely.
So far at Minworth, we've followed the process through the stage one
screens, where larger solids are filtered out...
..then on to the stage two settlement tanks,
where chunkier poo particles sink,
a sludge that's piped off for methane gas production.
The water being filtered out of the settlement tanks
is now a lot cleaner than when it first arrived on site.
But the next process has to operate at a microbial level.
The problem is, it's full of minute poo particles,
too small to sink in the primary stage tanks,
as well as the ammonia from our urine.
So how on earth do you remove these microelements from sewage
and make the water safe enough to return to the environment?
Having being channelled from the stage two settlement tanks,
the filtered sewage is now entering stage three of the treatment
process - the activated tanks.
Here in these six gigantic pools, incredible activity is taking place.
Massive green pipes are pumping air into the sewage,
churning it up like a nightmarish Jacuzzi.
It looks alive and it is.
The pumped oxygen gives life to trillions of naturally occurring
microorganisms in the sewage that actually eat the tiny poo particles
and ammonia, cleaning the water.
I'm desperate to see if we can get a look at these tiny life forms
under a microscope back in our pop-up lab.
I come bearing a container of the finest activated sludge,
hopefully bursting with living microorganisms.
Well, I'll be quite interested to see what's actually in this.
I'm taking the tiniest sample from the stage three sewage.
That's a nice bit of gunk.
But by magnifying it a few hundred times under a microscope,
hopefully we can see some of these tiny life forms
cleaning the poo particles.
There's things moving about. Oh! Look at that.
There's something going on there. Definitely things moving.
Oh! Look at, look at that.
Look at that microorganism.
It's got, it's got a sort of tail part. That is definitely alive.
Some sort of almost mouthpiece action, I saw there.
Yeah. Whoa! Look at that. Oh, my word.
Look at that! It's got propellers.
That is beautiful.
So that is a single celled organism,
it has a little row of cilia, or hairs, at its front end.
And it's basically gathering bacteria, just sucking, you know,
all the water through it.
So those, almost those propellers, that turbine...
Yeah. That's just hair just drawing the water in.
So it's cleaning the bacteria.
So this activated sludge contains all kinds of bacteria.
I mean, literally gazillions of them.
In just a few millilitres of this activated sludge,
we've accessed a nanoverse of microorganisms
eating up the poo particles and bacteria, and cleaning the sewage.
Oh! He's hoovered up a friend. What he's doing?
No, no, no. It's just...
But that, that's being drawn towards it because of the water stream.
It's sucking air in. That's rather beautiful.
Oh, look at that. Oh!
THEY BOTH GASP Wow! It's massive!
Oh, George.
Oh! Look at it. It's a monster.
Look at the size of that.
Oh, my God.
It's clearly hoovering up... It's almost got a mouthpiece.
Yeah, yeah. Can you see it open up a little bit?
See, this mouthpiece here, I almost want it to...
Go and, eat that bit. Go on, matey, get it.
These tiny aquatic life forms can be found in all freshwater
and even in soil, breaking down organic matter.
But now science, as we're seeing here,
is able to harness them as incredible cleaning biotechnology.
George, can we track down its body? Want to see the whole length of it.
Let's go down to the back end. It's a giant.
Oh, look, and there's the other end. Wow!
There's the other end of it.
And there's its gut, you can see the gut.
Yeah, the tract inside.
It's thrilling.
And there's numerous different species with their own exotic names.
These are called rotifers.
There's naidids and stalked ciliates all hard at work.
But we have to remember that this activity is occurring
in millions of litres of sewage here.
It's bioengineering on a mind-boggling scale.
Incredibly, the microorganisms in the stage three activated tanks
can complete their task of cleaning the sewage
in as little as five hours.
Whilst this process continues, I want to investigate how sewage
could help with one of the biggest challenges we might face
in the future.
The threat to our soil.
In 2020, the United Nations published a report
based on the work of 300 scientists.
It warned that the planet's soil, vital for food production,
is at risk of being degraded by a combination of factors
not yet fully understood,
like climate change, intensive agriculture and deforestation.
But here, sewage might be able to provide yet another resource -
compost.
I've come to the Centre for Alternative Technology in Mid Wales.
A facility that's been developing compost toilets for 30 years.
I'm meeting the centre's microbiologist, Louise Halestrap.
What a great setting, a loo with a view.
It's a space I'd be really happy to spend some time in.
But it is a composting toilet. It is a composting toilet.
The different thing is there's not white porcelain and water.
So instantly, you're confronted with a black dark hole.
Now, that's on purpose, because the other option will be
looking at a pile of loo paper and poo.
You're literally dumping into a void. Yeah.
So then you just use the toilet and go, "Eurgh, no flush."
Instead of water, you add wood shavings.
The carbon in the wood balances with the nitrogen in the waste.
So what's left behind at the business end?
How does this alternative system
offer another means of resource recovery?
The poo and stuff plops down into this half of the chamber,
and then once a year, or once every year and half,
the whole toilet is moved to the other side
and it comes down into this chamber.
So the left is your live shit pile
and the right is last year's... Composting shit pile.
So the idea behind that is hygiene.
So us compost workers who are having to deal with this shit, literally,
are safe from very fresh poo,
which has pathogens in it.
After two years, it becomes stable or benign.
So two years is the thing.
But I know this pile's been sitting there for about three years,
so we can have a look at that, if you want. Please. Yeah, yeah.
In the sealed chamber, it's our friends,
the naturally occurring microorganisms doing the work,
consuming bad bacteria and pathogens in our poo and composting it down.
I'm a microbiologist, I would not be touching this
if I didn't think it was safe.
So that is human waste and sawdust plus three years.
There's not a lot in there. The average human's poo is about 250g.
Dry weight, that's about 50g.
So if you think, during the composting process
the poo's going to be eaten, ingested by microorganisms
and then they're going to give off carbon dioxide and water,
and then eventually it's only 50g dry weight.
So it's about the fifth of the size it was.
Do you want to grab some and have a sniff? Please.
Right, I'm going to get in. Here we go.
It's actually...
I mean, it smells like soil, it doesn't smell in any way disgusting,
but there's definitely a soil-y feeling.
If I squeeze it together, it's slightly damp as well.
All the active volatile nutrients, like the phosphorus and the nitrogen
and carbon, are all in there and they've been stabilised.
So they've been locked in to the humus,
which is the kind of brown stuff that soil is.
And they do kind of magical things to the soil.
They release only when the plant needs it.
I mean, basically, fertiliser. It's more of a soil conditioner.
A fertiliser is more like a sports drink for the crops,
whereas soil conditioner is more like a wholefood.
So a nitrogen, phosphorus, potassium, industrial
man-made fertiliser would be kind of fast food,
and then this is good nutrition for life.
Here at the centre, they've applied their compost, or humanure,
to enrich the soil of the apple orchard on site.
They're not growing anything like root vegetables in the compost
as an extra safety precaution, but food like apples growing
above ground rather than in it is deemed OK.
And a bumper crop they produce, too.
I have to say, I find a composting toilet appealing.
It solves two problems with one piece of kit.
Firstly, you save phenomenal amounts of water,
but secondly, you're capturing a critical resource
to nurture plants with.
But can it scale?
Let's face it, putting a composting toilet
in every home isn't practical.
But, although perhaps a slightly stomach churning idea,
if we did it right, using our own excrement to help grow food
is worth considering, especially since the chemical fertilisers
designed to keep soil productive use minerals that the planet
is running out of, and minerals our poo and pee is rich in.
So how can we scale up using our own human waste as compost?
The answer to that lies back at Minworth.
Here at Minworth Sewage Works,
they're extracting every last possible resource from sewage
right up to the very end of the treatment process.
1.7 million people's number twos pass through here every day.
That's potentially a lot of compost.
I'm heading back towards Minworth's massive biodigester gas plant.
You know all that sludge that gets piped there
and turned into methane gas for the grid?
Well, all that poo hasn't just simply evaporated.
They've still got hundreds of tonnes of dried solids left.
And guess what they're going to do with that?
They're turning those dried solids into food for plants
on an epic scale.
To make it safe from pathogens, the sludge goes through an advanced
system called thermal hydrolysis.
It's heated to above 160 degrees and pasteurised.
I'm meeting bioresources manager Simon Farris to find out more.
This is where we're taking the solid material out at the end.
So this is everything that's left after we've extracted as much
of the energy out of it as we possibly can.
So what we've got here is essentially something
that's quite rich in nitrogen, phosphorus
that we can actually take out onto land and use as a soil conditioner
for certain types of crops. This looks absolutely fantastic.
I mean, it's...
It's black gold, isn't it, really? Yeah, essentially.
So loads of stuff that the world is running out of right now
is still containing that. There's a slight ammonia whiff. Not too much.
There's a little bit of an ammonia whiff, but that's some of the
nitrogen that's in there that we can actually use to replenish
some of the soil and condition it in the way that we want to.
I would have no qualms about eating a root vegetable, or a tomato
or whatever that had been grown using this.
Is that a general feeling or does there...?
Are people alarmed about it in any way?
So there's a huge amount of legislation at the moment
that governs what we can and can't take out to land
and it's quite tight. Particularly here in the West Midlands,
we've got zinc from galvanising companies and there are other heavy
metals that come out of industry that come down the sewer to us.
And what we have to do is, we have to make sure that all of those
stay within very tight constraints in a way that we can ensure
how it's used is safe for public consumption.
The end result looks much the same as the compost Zoe had held
in her hand, but it's not as pure.
The reality of our "everything in it" sewage system
means that although it can be applied to farmland,
like this field near Minworth, its use in agriculture is limited,
strictly not for farm to fork produce.
In the UK though it's mainly used to grow crops like this oilseed rape,
which is then turned into animal feed.
But all the nutrients are there in our waste - the nitrogen,
the phosphorus, the vital resources to feed the soil to feed us.
Arguably, we've taken our soil for granted for too long.
But by being more careful about what we send into sewers,
then we could have a renewable resource available
to keep replenishing some of our soil with the nutrients it needs.
Using our own waste for agriculture and energy is one thing,
but can science go even further?
Might sewage be a secret resource for revolutionary health benefits?
Earlier, Dr Ellie Jameson went fishing in the raw sewage
here at Minworth in search of phages, nanoscopic entities
that can kill deadly superbugs like E. Coli and klebsiella.
And I'm keen to see what, if anything,
she's managed to isolate in her sewage sample.
Ellie, I'm very excited. You've been on a phage fishing expedition.
What have you found? Yeah, so, while we've been hunting for phages
we've taken the water from Minworth and we've filtered it
to get out the cells that were in the sewage.
So take out bacteria, any human cells...
Any human cells. ..any debris.
So all it leaves behind? It should just leave behind phages.
Yeah. Viruses.
So, yeah, then we can kind of look at those a bit closer.
So, and when you look at that under the transmission electron
microscope, you can see these phage particles.
So these are some of the phages that we've got from our sewage.
So, have you any idea what these are? Are these new ones?
Yeah, these are new ones that we've never looked at before.
So a result, new phages found in sewage.
But do these ones have the power to act against deadly superbugs
like E.coli and klebsiella?
From that, then I've taken my cultures of E.coli and klebsiella
and I've added some of this filtered sewage into it.
So these are some of the E.coli on its own. Yeah.
And we have found that there are some phages in there so...
Oh! Oh! Show me. So if we hold it up,
there's a few little faint spots, so they're really round spots,
these are where the phage plaques are.
So where the phage have eaten away at that lawn of bacteria.
Oh, yes.
So you know that there was a phage in there
that has killed the bacteria. That's brilliant.
We can't pick up these tiny holes on camera, but under the microscope,
the effect of the phages on the E.coli is dramatic.
So that's a big hole. Yeah.
That's like a lawn of the bacteria round the edge
with just this giant big hole in the middle of it.
Can I just get my head around this?
You have isolated a new sort of phage from the sewage there.
Yeah. And it's active against E.coli. Yeah.
I mean, this is big.
You have discovered a biological entity,
which is potentially a life-saver.
That's a good day's work.
A good day's work!
This is... This is ground-breaking stuff.
Yeah, it is, yeah. Every new one that we find is another patient
that we can potentially treat, so these are really exciting results.
But how long do you think it'll be before this sort of treatment
is available on the NHS?
So on the NHS, well, that involves these big clinical trials,
which often take maybe ten to 15 years to come to fruition.
So there's this big lag.
But what we're hoping is to get some trials set up,
where we can use them in palliative care and that kind of stage.
So there's still work involved to establish if this new phage
is indeed life-saving and becomes mainstream.
But when permission's been given to use phage treatment in the past,
it's had remarkable success.
At Great Ormond Street, where they treated a patient who had cystic
fibrosis, she'd had a double lung transplant and then got a bacterial
infection afterwards... And was obviously very vulnerable.
Very, very sick, very ill, very vulnerable already.
And she had been sent home on palliative care.
That means it's the end. That's the end of life care, yeah,
just make you comfortable.
And then since having phage treatment,
she's actually got back that quality of life
and she's been able to return to school.
I mean, that is just, that's the grail, isn't it? Yeah, yeah.
That's why we're targeting these superbugs - E.coli and klebsiella
are really important superbugs in the hospitals.
So to have something in the arsenal we can actually treat them with
would be amazing.
For me, Ellie's discovery is the most astonishing
of all the resources that sewage has to offer,
completely at odds with our natural reaction to it as a substance
that's quite simply disgusting.
But of course, it does need cleaning,
and now Minworth's sewage is reaching the end of its journey
through the plant.
The microorganism in the stage three activated tanks have nearly
completed the job of eating the poo particles, bacteria and ammonia
in the sewage.
And senior technician Phil is getting Zoe a sample
to see the results of this extraordinary bioengineered
cleaning process before it goes on to the final stage.
That should settle now. Right, let's have a closer look.
That's amazing. In just that short amount of time,
stuff is settling, and you can see these little micro currents.
It's as if something's...dissolved.
Look at that.
We want a clear water at the top and the solids at the bottom.
Because actually at the moment this has been very agitated.
So it's not going to look as clear as it really is.
No, no, it'll have a lot more time to settle in there.
We're picking it up, we're moving it about.
You take a final effluent sample and you'll see the clearness of it.
it looks like you've just bought it from the supermarket
or out your tap.
It's amazing how powerful microorganisms are
at just breaking things down and treating things as food
and naturally cleaning our water.
The sludgy solids at the bottom, full of microorganisms,
are introduced back into the activated tanks,
whilst the clearing water at the top
is channelled to Minworth's final tanks.
After a last stage of settlement, the water being filtered off
looks like this.
Clear and deemed safe enough to return to the environment.
Incredibly, it's piped out of the site
and dilutes into the nearby River Tame, then joins the Trent,
the UK's third longest river.
Well, Zoe, was that fun? ZOE CHUCKLES
Enlightening. What it has done is totally changed my view
of a sewage works.
You know, I mean, it is an incredible entity.
Completely. The sheer volume of liquid and solids
that arrive here every second,
thousands of litres of the stuff turn up here continuously.
It's a machine for dealing with this tsunami of stuff.
To go from kind of mechanical engineering in the screens,
churning through and taking out the rag,
to then the bioengineering on that microscopic scale
and seeing the world inside that activated slurry.
And you realise that's an incredible ecosystem that's alive.
We saw it. All those little animals, I mean, literally,
gazillions of them.
I mean, they're working for us incredibly hard.
It's cutting edge stuff, actually, what they're doing here.
What this investigation has revealed is
that a sewage plant like this, using the very latest biotechnology,
can be a secret gold mine of fuel, of vital soil conditioners
and even of life-saving new treatments.
We might not be the stage of going for a number two
and filling up the family car with it yet,
but in this brave new world, the secret science of sewage
is only just getting started.
How do microbes affect our health?
To explore the science of what lives in us and on us, go to...
..and follow the links to the Open University.