YorkTalks 2020: How microbial communities can aid us in turning wastewater into low carbon energy - Lake Harding Association

YorkTalks 2020: How microbial communities can aid us in turning wastewater into low carbon energy

YorkTalks 2020: How microbial communities can aid us in turning wastewater into low carbon energy

By Micah Moen 0 Comment January 21, 2020


So I think probably the major
challenge for the next 10 years is working out how
we get humanity to stop putting so much
carbon into the atmosphere. We’re completely
addicted to energy. And that encompasses all
our lives, sometimes in ways that we don’t
really think about. So for example, you
may or may not realise, but the UK uses 5% of all the
electricity it consumes to make drinking water. So I’m not going to talk
about drinking water. As you can probably tell
from the title of my talk, I’m going to talk about this. So what you can see
here is wastewater. This is a small fraction
of the wastewater. This is actually at the
water treatment works down the road in
Naburn, where they treat the equivalent of about– water from a quarter
of a million people. So Yorkshire Water produces
about two billion liters of drinking water a day. Obviously, most of that
turns into wastewater. You can see here from
the color that there’s stuff in that wastewater. That’s mainly organic
material, so it’s been biologically produced. And we need to do
something with that waste. So what actually happens in
water treatment in the UK is, the raw water comes onto site. It goes into large
funnel-shaped containers. And most of the organic material
is allowed to settle out, and that’s called
primary sludge. Then the dirty water
from this process is decanted out into
a secondary vessel, like the one I just showed you. And we blow bubbles into it. And those bubbles
allow microbes to grow. Those microbes grow on
the organics in the waste, in the water, the waste,
turn it into more microbes, and then settle out so that
the water is cleaner again. But again, even in wastewater,
that uses 1% of all the UK’S electricity. And this was a good
idea at the time. But this is essentially
Victorian technology that we’re talking about
for treating wastewater. Then the cleaner water
now is decanted again into trickle bed filters. You’ve probably seen these
on the sides of motorways. And again, there’s
another biological process going on here that really
polishes the water, so that what’s discharged
as final effluent back into the rivers is cleaner
than the water that’s taken out of the
rivers to make drinking water from in the first place. Yorkshire Water
assured me that when everything’s working
properly, you can drink this final effluent. But I’ve never managed to
find anyone that will actually do that in front of me. [LAUGHTER] So the bit that I’m
really interested in is the primary and
secondary sludges that are collected here. They’re put into
another vessel, which is called an anaerobic
digester, where some very ancient, complex
microbiology is going on. That’s done in the absence of
oxygen, hence the anaerobic. And it is a very complicated
microbial community. And by doing that,
that organic material is converted into biogas,
which is a mixture of methane and carbon dioxide, and a
nitrogen-rich digestate, which can be used as fertiliser. Now, this microbial community
is not an artificial community. It exists in nature. It’s been around for a
very, very long time, and it happens in
the environment. So for example, anywhere where
there is an absence of oxygen, you’ll get this kind of
microbial community forming. Lakes are a good example. The University of
York has a lake. And sure enough, if you
stand there for long enough, you’ll see bubbles
rise to the surface. If you collect those bubbles,
you’ll see that they’re biogas. And the easy way
to demonstrate that is to set fire to it,
because it’s methane. So if you take your
son into the lake, then you can collect the
gas and set fire to it. [LAUGHTER] So again, clearly, there is
a biological process here that we can use to break
down the waste in our sewage. But we can’t just
dump all our sewage into water bodies
like rivers and lakes. I mean, that is something
that we have done in the past. That is something that still
happens in certain countries. I won’t name any,
but I have been places where that is the case. So instead what we do is we
engineer this whole process. And this is Yorkshire Waters
most recently commissioned plant. Knostrop in Leeds,
this is a 75 million pound investment in
treating sewage sludge. And this hopefully gives you
some sort of idea of the scale. These are the
anaerobic digesters that they’ve built at Leeds. Each of those digesters
is eight stories high. They stand 22 meters
from the ground up. Each one of those contains
7.2 million liters of sludge. And it produces a lot
of gas, some of which is held in this gas
bag here until it can be converted into electricity. So this is great. But this is 75 million
pounds worth of investment basically to treat
the sludge in Leeds. So what happens as
the population grows? Obviously, you can build
more and more facilities. But that gets expensive
very, very quickly. So the goal of the work
that I’ve been doing– which is being sponsored through
the Royal Society and with Yorkshire Water– is to see if we can
improve this process. There’s been a
lot of engineering around moving sewage
and mixing sewage. But there’s been very little
involved in engineering the microbial process here. So can we basically
put more material through the same assets so
that no more need to be built? And that’s important from
a carbon point of view, not just from the
energy point of view. But because, again,
concrete is a huge emitter of carbon dioxide. So actually, concrete produces
about 8% of all the carbon dioxide emissions
that we have globally. So we don’t want to
build more things. So the problem is, if you’re
dealing with facilities at 7 and 1/2 million litre
scale, then people don’t want you to do
experiments with them. And the infrastructure
for sewage sludge needs to work 24/7,
365 days a year. If it breaks, you would
know, and there would be a lot of very unhappy people. So to get around this,
again, Yorkshire Water have invested in facilities
at the University of York, which are shown here. We now have 65 litre
anaerobic digesters in the biology
department, which allow us to model the
process that you’ll be seeing at a very large
scale, and try and optimise without interrupting
normal services. And clearly, at the centre
of this is microbiology. So here’s one of the
key microbes that has been growing in my lab,
which actually produces methane at the end of this process. And there are a lot
of individual microbes in these communities. So for each millilitre
of sewage sludge, we’re talking about
100 million microbes. So that means that
we’ve got billions in each of our 5 litre pots. And again, if you go back to
the really large-scale systems, then this is where you realise
you should check your facts before you produce the slides. So one of my colleagues
said with great authority that there are more microbes
in an anaerobic digester than there are stars
in the universe. He’s a very eminent scientist,
so I absolutely believed it. I produced slide to say,
in an anaerobic digester there are more
microbes and there are stars in the universe. And then I thought, you know
what, I better check this. [LAUGHTER] So I went to the
European Space Agency. They estimate there are
between 10 to the 22 and 10 to the 24 stars in the universe. So it’s obviously
only an estimate. We can’t count that many. I did a calculation, and I
realised that we’re a little bit off. [LAUGHTER] But surprisingly, not very much. So if you take these four
digesters at Knostrop, they have somewhere between
1/3 and 30 times fewer cells than there are in the entire
universes in terms of stars. So if you look actually
at anaerobic digesters across the UK,
yeah, there are more microbes in anaerobic
digesters than there are stars in the universe. So this is a complex system
with a lot of things going on. How do we understand this? How do we try and
make sense of it so that we can start to
engineer this community? So what we’ve done is we have
gone, not to this facility, because this facility
has only been online for about six months,
but a similar facility at Naburn in York, just by the
Designer Outlets, and sampled the microbes
over a period of time. So Naburn also has
eight digesters. They’re not quite this large. They’re only 1.8
million litres each. We collected a lot of samples
over eight or nine months. And we started to
analyse the DNA. Now traditionally,
DNA sequencers are enormous and expensive. They’re kind of the size
of washing machines. They take a long time to run. They give you a
huge amount of data, which is difficult to analyse. But things have changed
quite dramatically recently. So now, the latest DNA
sequencers– and this is an instrument that’s
produced by a company called Oxford Nanopore, which is run,
actually, by a York biology graduate. And you literally can put your
DNA sequencer in your pocket. Now, this is good for
a number of reasons, not just because it
gives you something to wave around when you’re
giving this kind of talk. But it means that
sequencing is cheaper. It’s also faster. And it’s giving us a
different sort of data. It’s giving us much longer
pieces of information, which theoretically
are easier to analyse. In reality, that’s not the case. So we started sequencing
using this technology, and then realised that we had an
issue with analysing our data. So we initially used
York’s supercomputer. At the time, we had a facility
called [? York, ?] which turned out to not be very super. We uploaded data onto it. It ran for a month,
and it crashed, and we didn’t get any results. Fortunately, the
University of York has a collaboration with Google. They allowed us to use
Google Cloud to do this. After two weeks, we
did get a result. They told us it would
have cost 8,000 pounds were we to do that usually. But in the meantime,
the University of York had invested in a much
more super supercomputer, which is called Viking. We managed to sneak on it as
soon as it was switched on, and before the rest of the
university was using it. [LAUGHTER] And managed to analyse our
data in just over a day. And this is the kind
of thing you see. So each one of these panels
now is an individual microbe that we’ve been able to identify
from within that mixture of microbes living
in the community in the anaerobic digester. And if we zoom in on
one of these panels, you can see that this is how
this particular microbe has behaved over nine months
in Digester 1, 2, 3, and 4. What’s remarkable here is that,
even though these are operating at enormous scale, the community
within these individual digesters is reacting
in the same way to the material that’s
going into the digester. And what that means is,
this microbial community is ultimately very
predictable, which means that we really do have
the potential to engineer this. And this is the
first time it’s been shown at any kind of scale, that
these microbial communities, despite having thousands
of different species and despite having trillions
of different individuals, are behaving in a
very predictable way. So what does that mean for us? That’s not what
should have happened. Can we go– OK. Right. So anaerobic digestion
is a great way of recovering
resources from sewage. And in fact, now those
are called bioresources. Obviously, we get
biogas from this. And that can be used to
create electricity and heat. We get digestate, which
can be used as fertiliser. But AD doesn’t just work
on wastewaters material. It works on all sorts
of organic waste. So food waste is
another thing that can be used in
anaerobic digestion, and, importantly, farm residues. So the statistics
are, if we were able to collect all of the
animal manures produced by agriculture across
the world and put it through anaerobic digestion,
that would generate enough power or energy for
all of global agriculture, and we’d still have
energy left over. There are more things
we can do with this. The biogas can be used
just for domestic cooking as a drop-in replacement
for natural gas. But equally, it can be
upgraded to biomethane and used to run lorries. And it’s really, at the moment,
the only viable alternative to fossil fuels is
compressed methane in these kinds of trucks. It can also be upgraded and
put directly into the grid. And if you live in Sherburn in
Elmet, or other places locally, a proportion of the gas that
you’re using from your mains is biogas. But we can go further
than that when we start to engineer the community. We can reform the biogas
into methanol and hydrogen to make even cleaner fuels. But we can also
engineer this community so that it produces more
interesting molecules straight away, rather than methane. And there’s already
been some very nice work done in the States where
they’ve demonstrated the production of isoprene,
which can be directly used as a petrol replacement. Or we can start to engineer
higher value molecules, like the ones that Mike
was just talking about. And at that point,
I need to stop, say thank you to all
these people, particularly the Royal Society and Yorkshire
Water for their support. Thank you. [APPLAUSE]

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