Utility Week

UTILITY WEEK | JANUARY 2022 | 41 gases which is rich in methane that can be used in place of fossil fuels." Gysin says that while the bacteria involved in the two cold processes to be tested are similar to those found in the anaerobic procedures currently used to treat sludge, the wastewater involved is far more dilute and lower in temperature. "Anaerobic digesters are heated to around 37C – this wouldn't be feasible for the huge volumes of wastewater we treat," she says. "Cold anaerobic treatment has been suc- cessfully applied in warmer climates – our challenge is to create the conditions in which the bacteria can treat wastewater at the ambient temperatures experienced year- round throughout the UK." Enabling rapid adoption Despite the challenges posed by a milder climate, Gysin believes cold anaerobic pro- cesses could "completely transform" the water industry's wastewater treatment operations. "Not only will it reduce the amount of energy consumed and the direct emissions produced, but it will also reduce sludge pro- duction," she explains. Utility Week Live 2022 See this content brought to life at Utility Week Live, 17-18 May 2022, NEC Birmingham New approaches to wastewater treatment and resource recovery is one of the frontline challenges at the heart of Utility Week Live 2022's live content programme. View the challenges and be alerted for tickets to the industry's most eagerly awaited reunion at utilityweeklive.co.uk "Reducing sludge production may seem counter intuitive because we generate energy from sludge, however we would be reducing the production of the surplus activated or secondary sludge, which is typically harder to digest and therefore yields less energy than primary sludge. "We anticipate that we would continue to anaerobically digest primary sludge at our larger sites, generating energy in the form of biogas," Gysin continues. "Sludge from smaller sites is typically transported to a local sludge treatment centre by road tanker. At small sites we are seeking to elimi- nate up to 96% of the sludge production to avoid transporting it by road, thereby further reducing carbon emissions, costs and vehicle movements." She adds that the input of the project partners will be "crucial" in ensuring that the project develops a robust and widely applicable solution. "We believe our partnership with six other water companies and the University of South Wales is ideally placed to do this and to enable the rapid adoption of cold anaero- bic digestion once it is proven," Gysin says. "Additionally, we will create an oppor- tunity for water companies to play an important role in the circular economy by recovering nutrients – nitrogen and phos- phorus – that could be used in a range of applications from fertilisers to energy production. "In that respect, this project is just the beginning. We recognise that a successful circular economy model will require wider collaboration with additional stakeholders. We believe the open innovation model that we are adopting throughout will continue to enable innovation beyond the project." Understanding process performance With regards to next steps, Gysin explains that the consortium is poised to roll out its mobile pilot plant to test a novel technology con‹ guration for cold anaerobic wastewater treatment. "The mobile pilot will be operated at a number of sites – across multiple partners – to understand how the process performs with diŽ erent wastewater characteristics," she says. "We will then build a commercial scale demonstration plant at a Thames Water site to prove the technology con‹ guration at scale and de-risk the subsequent rollout. "In parallel with this, Dwr Cymru Welsh Water will be adapting its existing anaerobic demonstration plant at Builth Wells to treat crude sewage – rather than settled sewage – making the solution more bene‹ cial for smaller sites." Stuart Stone, UW Innovate editor Widespread adoption of cold anaerobic digestion would result in the sector produced less sludge Photo: Thames Water Photo: Thames Water

• Cover