The
wonders of waste
A £200 million investment at United Utilities’ Davyhulme wastewater treatment works in
Greater Manchester has put the site right at the forefront when it comes to sewage treatment
Davyhulme wastewater
treatment works (WwTW) in
Greater Manchester, serving
a combined domestic and
industrial load that is equivalent to 1.2
million people, has become a beacon
for United Utilities’ highly sophisticated
approach to sewage treatment and sludge
management and disposal. It is the
outcome of a recently completed £200
million four-year upgrade to modernise the
company’s largest such treatment plant.
The works can deal with a massive
throughput of 750 million litres per day
(Mld), even as Manchester’s continued
economic growth brings ever more
people and businesses to the area.
The requirement to operate at the
leading edge was clearly compelling and
the capability of the works has been
massively enhanced to cope
with future demand and tighter
environmental standards.
Only visit the new-look WwTW and
you will nd an operation where 91,000
tonnes per annum of biosolids (the
‘sludge’ produced both on site and
from seven other feeder sites) can be
processed via thermal hydrolysis and
anaerobic digestion to produce a highquality
soil conditioner for farmers, plus
biogas. The works has the exibility to
either clean the gas into biomethane for
injection into the local gas supply grid or
use it as fuel to power CHP (Combined
Heat and Power) engines, generating
electrical energy for the site – and even
powering a eet of electric vehicles for
the site operations team.
SEWAGE FARM
It wasn’t always this way, of course.
Davyhulme started life as a ‘sewage farm
in the countryside’, treating the city’s
wastewater before releasing it into the
Manchester Ship Canal. The Davyhulme
Treatment Works opened in 1894 and
has been at the forefront of innovation
ever since, not least with a breakthrough
in the drive to improve the treatment
process when, in 1914, two chemists,
Ardern and Lockett, discovered the
‘Activated Sludge Process’, soon after in
use worldwide.
Fast forward to today, and Davyhulme
is one of the biggest wastewater
treatment works in the UK, draining the
entire western side of Manchester. The
site operates 24 hours a day, every day.
In heavy rain, ows of more than 30,000
litres per second are treated at the works.
Employing Ardern and Lockett’s activated
sludge process, wastewater containing
organic matter is aerated in an aeration
basin, in which micro-organisms (bugs)
metabolise the suspended and soluble
organic matter.
“The problem Ardern and Lockett had
to overcome was the continual loss of
micro-organisms being carried through
the ow out of the aeration basin, due to
their suspension in the liquid, rather than
being xed onto a media-based process,”
points out Dave Frain, Davyhulme WwTW
production manager for United Utilities.
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