Innovative technology set to super-power United Utilities’ sludge treatment to boost green energy production

An innovative and sustainable technology is set to boost the amount of sustainable biogas that United Utilities generates from Stockport’s sewage sludge.                                                    

The water company for the North West has partnered with Royal HaskoningDHV to enhance the sludge treatment process at Stockport. The introduction of the new technology is expected to increase biogas production by more than 20%. It also reduces the amount of chemicals used in the process.

The innovative project is a first for the UK and is backed by funding from the Department for Energy Security and Net Zero’s Industrial Energy Efficiency Accelerator programme (IEEA).

Sewage sludge is the leftover material from the wastewater treatment process, United Utilities collect this and send it to one of their 13 digestion sites which are located at waste water treatment facilities around the region. It is put into an anaerobic digester to generate renewable biogas which is then used in a combined heat and power unit to produce electricity and heat to power the wastewater treatment facility.

The Stockport Sludge Treatment facility is located at Stockport Wastewater Treatment Works and processes sludge from other wastewater treatment facilities in the area. Just over 600 cubic metres of sludge are processed every day – enough to fill an Olympic sized swimming pool every four days.

The combined heat and power unit at Stockport currently generates more than 9,700 kilowatt-hours of renewable energy every day, the equivalent of the power used by 1,230 homes each year.

Boosting the amount of gas generated by 20% supports United Utilities’ Net Zero commitment and will bring Stockport Wastewater Treatment Works closer to achieving energy neutrality as well as reducing greenhouse gas emissions.

Tom Lissett , Bioresource and Green Energy Director at United Utilities explains: “Here at Stockport we don’t just provide great wastewater services for more than 400,000 members of the community – we aim to do that in a way that helps make the North West greener, healthier and stronger.

“Innovation is critical to make our services as sustainable and cost-effective as possible. We’re really pleased to be a partner in this project, recognising the benefits of retrofitting and optimising the performance of existing assets, rather than investing in new build.

“This is one of a range of exciting projects which will maximise the potential of our bioresources, reduce carbon emissions and support the decarbonisation of energy production in the UK.

“The results of this trial won’t just benefit United Utilities, the findings will be shared with other water companies in the UK.”

Paul Lavender, Director Water Utilities UK, Royal HaskoningDHV added: “We are delighted to have successfully secured funding from the UK government for our sludge digestion project for United Utilities. This is a positive step for energy efficiency and sustainable wastewater treatment.”

Paul McKinney, Associate Director at the Carbon Trust and programme manager for the IEEA said: “The IEEA is supporting decarbonisation across a wide range of sectors, and we are excited to be supporting this innovation which will hopefully lead to a significant reduction in carbon emissions associated with sludge processing.”

The technology is due to be operational at Stockport by autumn 2024.