Cog Moors

The Cog Moors wastewater treatment works which treats wastewater for Dinas Powys, Sully, Penarth, Barry and the West of Cardiff has received a £50 million upgrade.

Cog Moors Wastewater Treatment Upgrade

Cog Moors is a wastewater treatment works which treats wastewater for Dinas Powys, Sully, Penarth, Barry and the West of Cardiff.

We have invested over £50 million to install an Advanced Anaerobic Digestion (AAD) plant along with other improvements to the existing site. This investment will enable us to create an energy neutral wastewater site by recovering energy from the waste we process onsite. This will help manage the effects of climate change, reduce our running costs and carbon footprint and help keep your bills low.

Once the plant is completed, it will:

  • Generate 1.5GWh capacity
  • Produce 2.028MWh of electricity a year
  • Generate enough energy required to power 4,800 homes per year
  • Help meet Welsh Water become carbon neutral by 2040

What is Advanced Anaerobic Digestion (AAD)?

An AAD plant is part of a combined heat and power facility consisting of 2 engines that use biogas from the anaerobic digestion of sewage sludge collected from waste in our sewer system to produce biogas (mainly a mixture of around 60% methane and 40% carbon dioxide) and a biosolid “cake” (a sustainable fertiliser that can be recycled on farmland).

How Does It Work?

The biogas is created by the anaerobic digestion of sewage sludge which is then used in gas powered engines to generate electricity which will be used to power the plant. The left over sludge becomes a biosolid “cake” and is collected and used as a sustainable soil enhancer and environmentally friendly alternative to chemical fertilisers.

Here is a diagram explaining how Advanced Anaerobic Digestion works:

Project Update

The brand new AAD plant is complete, and we are currently handing over the site to our operations team.

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Developing the AAD plant

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Here is a link to pictures outlining progress made in developing the AAD plant since the summer of 2019.

Engagement with the Community

Throughout our investment, we have been keeping the community informed through our regular newsletters, the In Your Area section of our website and through social media. We have also attended a number of community engagements events to keep you informed of developments in Cog Moors.

As a result of our work, we have also been actively promoting our Community Fund which gives communities to boost fundraising efforts for good causes in their area. If you live in an area where work is taking place – and you’re fundraising for projects to benefit the community – you could receive funding from Welsh Water up to a value of £1,000. Find out more here.

Over the last year, several groups within the Dinas Powys and Sully areas have successfully been awarded funding through Welsh Water’s Community Fund. Here are a few of those successful groups:

Dinas Powys

Dinas Powys Tennis Club: Dinas Powys Tennis Club received funding in August to increase the number of young people playing tennis by rejuvenating the junior hard courts and developing the Dinas Powys Tennis Academy.

Dinas Powys Art Group: Dinas Powys Art Group obtained funding in August for art equipment to improve their art techniques and encourage art throughout the community.

Dinas Powys Library and Activity Centre (DPLAC): DPLAC received funding in August to buy new children’s seating for them to sit, read and do activities at the library.

1st Dinas Powys Scout Group: 1st Dinas Powys Scout Group received funding in April to renovate their scout hall by installing a new wood floor in the main community room.

Murch Bowling Club: Murch Bowling Club secured funding in February. The money will be used to convert an outside grassed area which will include outside tables and chairs and provide an area where members and friends can watch the activities taking place on the bowling green.


Civil Aid Voluntary Rescue Association (C.A.V.R.A.): In August, C.A.V.R.A. obtained funding to go towards training to expand its expertise into rescue from weirs.

Sully Village Group: In February Sully Village Group obtained funding to install beach clean stations as part of their beach clean project.

Sully and Lavernock Library Trust: Sully and Lavernock Library Trust successfully secured funding in February to install a bookshelf mural sign which will help promote the library.

Lavernock NR Volunteer (part of The Wildlife Trust S Wales): Lavernock NR Volunteer secured funding in February. The money secured will be used to improve the local footpath network and purchase tools which will help volunteers with their work.

Cog Moors

In Your Area

To receive these updates by email, visit In Your Area and click Keep Me Informed.

Find out more
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Frequently Asked Questions

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We have also produced a Frequently Asked Questions page to answer additional questions.