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Video 6.6: Conversation with Marie Hart
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Water Supply and Sanitation Policy in Developing Countries Part 1: Understanding Complex Problems
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University of Manchester
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À partir de la leçon
Development Paths for Water and Sanitation Services
Rencontrer les enseignants
Prof Dale WhittingtonProfessor
Manchester Business School
Dr Duncan ThomasLecturer
Alliance Manchester Business School
[BLANK_AUDIO]
This year is a landmark in terms of wastewater treatment.
We're celebrating the centenary of our, the publication
of Ardern and Lockett's work on activated sludge.
This presentation focusses on Davyhulme and the work that was carried out
there, and also looks at how the works has changed over the century.
So I'm going to go through some of the changes that
have happened over the years at Davyhulme Waste Water Treatment Works.
And also look at some of the external factors that have driven the changes at
the works, and also how the works has
impacted on the development of waste water globally.
So I'd like to put into context the
works development with restre, with respect to social factors.
However, let's have a look at Davyhulme itself.
It's United Utilities' largest waste water treatment works.
It has a really large footprint, and as you can see, it's bounded by the
Manchester Ship Canal and the M60, as well
as many domestic dwellings and some retail facilities.
The works itself treats 1.2 million population
equivalent, and the dry weather flow of the
works is 340 megaliters a day and flow to full treatment is 714 megaliters a day.
So you can see it is a very large treatment works.
So let's have a look at Manchester in the Victorian era.
It was a very different place then to the Manchester that we know today.
In the middle of the 1800s, there were a hundred drainage areas within the city.
And there were many challenges that we saw there.
So for instance, lots of over population, crowding, grimy streets in the city.
And that was due to the discharge of waste onto the streets.
So that brought many problems, and you can imagine, issues
with health and well being of the people in the area.
Water had started to be brought into the city.
And then there was a need to develop a drainage network.
So in 1853, the metropolitan city of Manchester was founded.
So let's look at some of the changes and
the growth of Manchester over the period from 1838 onwards
[BLANK_AUDIO]
As you can see, there's quite a lot of
development as the areas and the small districts come together.
The population was rising.
And with that growth in population, as I've
mentioned, there are many health issues that were considered.
There were a number of typhoid outbreaks, and there were
Royal Commission reports that were published in 1865 and 1868.
There was also a Public Health Act that was brought out in 1875.
And in 1876 we saw the River Pollution Act.
These were measures to try and understand the impact on
health and the impact on pollution in the water courses.
As drainage areas were developed, the drainage, the, the waste was taken
from the streets and actually discharged into the water courses.
So the plan, and the foresight of some of the town engineers and the
people at Manchester Corporation were to look at building a treatment works.
So there were many developments.
One of the major developments as a precursor to the opening of Davyhulme,
which happened in 1894, was the opening of the Manchester Ship Canal in 1893.
This meant that there was a link now to the, from the city of Manchester to
Liverpool, and along the ship canal, and that helped in terms of trading.
Treatment at the new works at Davyhulme consisted, in the early days,
of screening, followed by solid-liquid separation
where sedimentation was used with chemical precipitation.
This allowed us to separate solid and liquids.
And the liquid element was then treated across
the land and eventually discharged through the ship canal.
The solid element was the sludge.
That was taken, pressed, initially disposed of
into sludge lagoons or, again, onto land.
But latterly, disposal was via ships to
the Irish Sea via the Manchester Ship Canal.
You can see here one of the boats that was used
at that time, it's the S.S. Joseph Thompson, in the early days.
Treatment at Davyhulme Treatment Works developed
further, and the land filtration was replaced
by contact beds or bacteria beds or percolating filters, as they're known now.
The next big step forward, though, was the discovery
by Ardern and Lockett of the activator sludge process.
They published their work in 1914, and that also
coincided with the start of the first world war.
However, work continued at Davyhulme, and the first plant using an
activated sludge plant at Davehulme Works was running in 1918.
Over the years, the flow to the works and the
load that was being treated, increased due to increases in population.
In Manchester, the population had risen to over half a million.
And the treatment works had to be extended.
So the original activated sludge plant that we saw that was
running in 1914 treated only four and a half megalitres a day.
So further extensions to the treatment works were required.
This first major extension to the works started in 1926 and was completed in 1934.
Davyhulme, over the years, has been known as a
site where new technologies have been developed and tried.
And this continued during this extension phase.
So a treatment works was being built and put in, but
actually it was an opportunity to look at the design as well.
So three different forms of activated sludge plant were installed at the time.
They were a simplex unit, Sheffield's bio-aeration
system, and a diffused air system as well.
This was so that we could look at the
treatment, the design, and look to optimize the whole process.
We can see here, some photographs in the early days
of different types of aeration plant that was being developed.
And these are plants in around the northwest and other parts of the UK.
So now you're going to see a very short video which
is a photomontage of the Davyhulme Treatment Works over the years.
[MUSIC]
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There were many changes to the Davyhulme Treatment Works over the years.
And there were also many changes in the water industry at the time.
For example, in 1948, there were 32 river boards set up in England and Wales.
The next big change, though, was in
1974 where the whole water industry was restructured.
At this time, Manchester and Liverpool Waterworks Corporations were combined
into an organization that was known as North West Water Authority.
Then came privatization in 1989, and North West Water P.L.C was formed.
The next big change to us as a company was then in 1995 when North West Water and
Norweb merged to form United Utilities, the company that we're known as today.
Wider in the industry though, remember, in
1998 there were changes to sludge disposal.
And this was actually banned at sea.
This was quite significant, especially at Davyhulme, where
sludge disposal had to be reconsidered, and part
of the whole sludge strategy for the company
was reviewed, and there were many changes made.
On this slide here you can see some of the changes
in the effluent quality concerns that have happened over the years.
And the main thing to note here is the drive towards nutrient removal.
So you can see, our big challenge at the moment
is heading towards a one milligram per litre ammonia standard.
Ammonia removal is something that we've been interested
in at Davyhulme over a number of years.
This is mainly because Davyhulme was identified as the single
major contributor to high levels of ammonia in the Mersey Estuary.
It was found that there were six and a half tons
of ammonia being discharged, per day, to the estuary from the works.
North West Water proposed to deal with this.
And a number of studies and investigations were carried out.
Back in 1989, work was carried about by John Dolan and Nigel Horne.
And they did some on-site trials, and looked at some
investigations onto different types of treatment processes that we could use.
The reason we investigated so heavily at that time, was
because it was found previously in the 1950s and 60s,
that nitrification on the works was being inhibited, primarily due
to the types of trade effluent that we had on site.
Now the history of the works is such that over
the years there were many heavy industries in the area.
For example, munitions and jet engines were developed in
the local area around the time of the wars.
And this heavy industry led to different types
of heavy metals, and some inhibitory compounds being discharged.
The North West has got a long history of industry.
If you go back to the industrial revolution it was textiles and cotton.
So we can see that there have been many
different types of industry and discharges over the years.
I suppose later days, it's more along the
lines of petrochemicals and electronics that we're looking at.
So, getting back to Davyhulme and effluent
treatment and nitrification, the outcome, really, of the
trials was that a new process that had
been developed in France was given a debut.
And again, Davyhulme was at the forefront here when in 1991 a pilot plant of
a biostar process, was tried and tested and found
to be successful, and then the full-scale plant was constructed and operational.
The plant in 1998 then treated all of
the effluent from activated sludge plants one and two.
And this created the nitrification that we needed.
Another major challenge for us at the treatment works is on odour control.
Again, cast your mind back to those old photographs that I showed you earlier.
And you'll see the development around the site.
The population grew, and local residents were really close to the boundary.
Now, as a company we have a responsibility to be
a good neighbor to our local residents and retail organizations.
Over the years, there's been a lot
of heightened public awareness with regard to odour.
And there have been many local action groups, and social
media has obviously played a part in this as well.
So with the development of domestic and retail in the area, we've
found that we've had to do a more in terms of odour control.
In 2003, a major odour control project was online.
This saw the air from underneath primary tanks and the activated
sludge plant ASP one on site, being collected and treated.
There were big challenges for us with this project.
As I've mentioned a number of times, the flows to the
works are quite large and this is very large treatment works.
And that in itself brings many challenges.
Our primary tanks here, two prim, two of these
primary tanks, the circular ones, are 55 metre diameter.
So to cover these was an amazing challenge.
These geodesic domes, you can see here, were constructed
over the adjacent storm tanks, and then lifted into position.
As you can see from the photographs, the lift occurred at nighttime.
This is because we needed optimum weather conditions, so really
low, low wind to enable us to do a safe lift.
A thousand-ton crane was used because the weight
and span that was needed for the lift.
It helped as well though, having the lift overnight, because it meant
that there was less interruption to the traffic on the nearby motorway.
Maybe some motorists complained of UFOs landing that night, who knows.
But, the success of the project was
down to the successful installation of these covers.
Just to give you a sense of scale for the odor control plant.
It's a three-stage wet chemical scrubber on the activated sludge plant area.
And the slab where the tanks are and the, and
the different processes, is comparable to the size of Big Ben.
So, again, a big challenge to us, on the site.
This plant actually treats 140,000 meters cubed per hour
of air that is extracted from under the covers.
The next big project that we've seen at
Davyhulme Wastewater Treatment Works is the SBAP project.
So, that's Sludge Balanced Acid Program.
And this was a project that we generated to enable us to look at
solid waste in terms of, of resource rather than a waste to be disposed of.
The project consists of thermal hydrolysis, and it
was a plant that was commissioned in 2013.
So, a really recent addition to the site.
It was a 100 million Pound investment, and really is the next step of innovation
for the site, considering the energy requirement for the site.
And this helps us in terms of reducing our energy.
Next, you'll see a short video on that, and some of the
people that were involved in the project discussing the benefits that they've seen.
[MUSIC]
>> We're actually on the Davyhulme
Wastewater Treatment Works site, where you can
actually see it is part of the thermal hydrolysis plot that's been situated here.
[MUSIC]
>> Part of the situation in the utilities is that we produce about 210,000 tons
dry solid a year, of sludge, most of which goes to arable agricultural lands.
That land bank is under tremendous pressure.
>> 40% of United Utilities sludge comes through this site.
Because the plant behind us actually takes the sludge up to a great
100 degrees celsius at high pressure, and holds it there for, you know,
for 20 minutes, 30 minutes or so, it kills off all the nasty
bugs that people are worried about when you spreading sludge to the land.
So it opens a much broader land bank to us.
>> We spread it on the grasslands.
And in the northwest of England there's a
lot more grassland than there is arable land.
[MUSIC]
>> The main difference between the sludge that we're getting now than
the sludge that we had before, is it's a lot better consistency.
It don't run off across the yard.
It's, it's a solider product and the smell is reduced.
It puts a lot more quality into your grass.
If you spread the sewage where sheep and lambs are grazing,
you can tell the difference in the lambs that come off that
ground, because the new stuff that's coming now, there's zero bacteria in
it, whereas the other stuff, it were, wasn't half neat, I think.
If we didn't have the sewage being tipped
we'd probably have to cut back on stock numbers,
because the ground wouldn't carry the same amount
of stock, or use more expensive, like, fertilizer alternatives.
[MUSIC]
>> We've been producing energy from, from sewage
sludge, for decades we've been doing that now.
And technology behind us, a process, called
thermal hydrolysis, owned by a company called Cambi.
The plant behind us now, as it stands
today, is the world's largest thermal hydrolysis plant.
So the technology cycle has enabled us to do what we've done today.
I'm sure over the next 20 years it'll move on further.
>> The biogas that's used in the engines obviously creates power.
The power is actually adequate to not only run the new process that
we've installed on the rest, but also the entire treatment works at Davyhulme.
>> The energy cost to import to Davyhulme before
SBAT came along, was approximately 1.5 million Pounds a year.
And, by having this, we will actually be exporting energy.
So we'll actually be saving 1.5 million, and exporting our energy as well.
>> Taking, generally what's known as a waste, which
is sludge, and really maximizing the energy recovery from it.
[MUSIC]
>> 99 years ago activating sludge process was, was developed on this site, and then
99, 100 years later, we're switching on and
operating the world's largest plant of its kind.
It's something that the site team are really proud of, I'm really
proud of, and all the people at UU are really proud of.
[MUSIC]
>> At United Utilities, we're passionate about health and safety.
And I just wanted to give you an understanding of how things have
changed over the years, in terms of operation and maintenance at the works.
If you look at this gentleman in the normal operation at the works back in
the earl 1900s, personal protection equipment was definitely
something that was not considered at that time.
Or if it was, it was of a very different standard to that that we see today.
If you notice, the hand railing and the lighting for the area, is
not really of the standard that we would expect on our treatment works today.
So I've talked a lot about the plant, and how things
have changed over the years, in terms of different types of technology.
I think it's worthwhile to consider, as well, that the
design and the design methods that we've used over the years,
and looking at the projects from the 1900s through to the
current day, the way we carry those out has changed significantly.
So we're looking at the changes from drawings of the past, to
building information modeling, and this will enable us to
review the assets that we have and manage them over the whole asset life cycle.
It's a means of doing 3D models, doing
some visualization, and helping us in terms of
our design when we're looking at clashes, and
also access lifting and maintenance and safe operation.
So, really it is the future for us.
We can look at trends, and we have a store where all the data is at our fingertips.
The next big project for Davyhulme Waste
Water Treatment Works, we've termed the modernization project.
This is a project to help us in achieving our one milligram
per liter ammonia standard, which is the next big driver for our consent.
We're currently evaluating tenders for the new treatment works,
and we've also commenced some enabling works on the site.
Part of the project and the consideration for this,
is so that we have no net loss on biodiversity.
As a company that's interested in protecting the environment,
and that is one of our fundamental practices, then looking
at the treatment works and how it could impact on
the environment locally is a major consideration for this project.
There will obviously be some works carried out on the site that will
have an impact on local wildlife, and some of the plants and species nearby.
So what we've done is we've looked at
neighboring land that we own, and looking at an
opportunity that we could create new environments there,
to compensate for any losses on the treatment works.
This is all part of being a good neighbor, as well as looking after
the residential area and minimizing the impact
in terms of construction traffic, as well.
So, what could it look like?
Well, this is potentially what the new works could look like.
A bit of a change that's occurred over the 120 years of the site.
As you can see, the population has encroached on the site.
And there are many retail facilities nearby.
You can possibly see the Snow Dome nearby, as well.
So, the challenges have certainly been there for Davyhulme.
So, as you can see, Davyhulme has been at the heart of the community.
The developments on the site have worked
with the community in terms of allowing expansion,
and the expansions on the works have had
to occur because of the increased population nearby.
All of that, though, is really down to the
foresight of those engineers in the early days of
Manchester Corporation, and the work that they did in
developing drainage systems and developing the waste water treatment works.
But then, think back to Ardern and Lockett, who, without their invention,
the world of waste water treatment would not be as it is today.
They've allowed, in their invention of
activated sludge, they've allowed us to expand
urban communities to a degree that would
not have been possible without that process.
The contribution to the health and welfare of people in communities,
and economic expansion, can really be contributed to this.
So to summarize, I think Davyhulme is a
site that's seen many changes over the years.
It has grown, and shaped itself with the community.
And I really feel it's set to continue.
And if you look at the new projects, activated sludge is definitely going
to be at the heart of the community for a long time to come.
[BLANK_AUDIO]
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