Ofwat’s Innovation Fund has today announced 17 winners from the fourth Water Breakthrough Challenge, a competition that invited solutions with the potential to deliver wide-scale, transformational change benefitting customers, society and the environment.

An innovative solution to reduce the environmental impact of managing sewage sludge by turning it into a source of hydrogen and low-carbon products is one of the winners of a £40 million competition from Ofwat, the water regulator.

The Sewage Sludge Gasification project is a novel approach to sludge management that has today been awarded £2.3 million by Ofwat’s Innovation Fund. The project is one of 17 solutions awarded a share of £40 million in the water regulator’s latest innovation competition – the Water Breakthrough Challenge 4.

Sludge is a bi-product of treating sewage – a treated combination of solid matter and dead bacteria left over from the treatment process. The treated sludge is pathogen-free, rich in phosphorus and nitrogen, and has, for many years, been used in agriculture to enrich soil and improve its moisture retention.

Across the UK and Europe, there is a growing realisation that sludge also poses environmental challenges, since it may also contain microplastics, metals and PFAS (indestructible chemical compounds, also known as “forever chemicals”) which may enter the soil and eventually waterways. Innovative alternatives to managing sludge are needed.

Led by Yorkshire Water, the Sewage Sludge Gasification project seeks to alleviate significant challenges for the UK water industry and offer an alternative to recycling sludge to land.

The Advanced Thermal Conversion gasification process will convert treated sewage sludge into usable products such as biochar, vitrified ash 'stones' and a hydrogen-rich synthesis gas (syngas). By operating at a high temperature, the process aims to destroy other contaminants such as forever chemicals including PFAS and microplastics.

The project will demonstrate the circular economy in action by testing the biochar to treat wastewater and also as an additive in brick manufacturing. The carbon-rich biochar, which resembles small pieces of charcoal, could also be used as a soil improver to increase water and nutrient retention. As it doesn't readily decompose, it can also be used as a vehicle for sequestering carbon in soil, although it must be properly managed to ensure soil pH levels are not negatively impacted.

The vitrified ash 'stones' could be used as aggregate in the construction industry to reduce the embodied carbon footprint of concrete. Syngas is a blend of hydrogen, carbon monoxide, carbon dioxide and methane, and has the potential to be used to produce green electricity, along with other high-value products.

Yorkshire Water suggests that by using a power optimised plant configuration the gasification process could take the 160,000 dry tons of sludge it produces each year and generate around 50Mwe of power - enough that the gasification process would be energy self-sufficient.

On a national level, the UK produces around 1.2 million dry tons of sludge per year and this is increasing. The gasification process could potentially covert this sludge sustainable products, remove all sludge to land and generate 375 MW of renewable energy for use by the wider industry.

Dr Danielle Hankin, Innovation Programme Manager, Yorkshire Water, said:

"Converting treated sewage sludge into gas, biochar and ash 'stones' opens up new, more sustainable uses for this waste product. We’re proud to be pre-empting changes in legislation and consumer attitudes, by delivering a groundbreaking technology that benefits customers, the environment and future-proofs the water industry.

“Once proven, the gasification process will produce sustainable wastewater treatment media and construction material, generate green electricity, and could create high-value products such as biomethanol aviation fuel or hydrogen. Our work represents a pivotal step in driving the UK towards a greener, more resource-efficient future."

Helen Campbell, Senior Director, Ofwat said:

“What we do with treated sludge is not the most glamorous of subjects but cannot be ignored. The current approach of spreading treated sludge to land has environmental consequences, which could include microplastics and forever chemicals – both of which may enter the water system and affect water quality. This is not a problem unique to the UK – alternative solutions are needed around the world. The Innovation Fund has awarded funding to four projects today that will help accelerate innovative solutions to the problem and provide wider environmental benefits in the process.”

For more information, visit: https://waterinnovation.challenges.org/breakthrough4/

The full list of winners in the Water Breakthrough Challenge are:

• ALL-Streams HTO – led by Anglian Water - £1,380,591
• Developing a market-based approach to deliver SuDS through street works – led by Thames Water - £1,340,610
• Local Regeneration of Granular Activated Carbon – led by Dwr Cymru Cyfyngedig (Welsh Water) - £1,262,367
• METREAU: Microbial Electrochemical Technologies for REsource recovery And Utilisation – led by Northumbrian Water - £1,656,489
• No dig leak repair – From concept to reality – led by Thames Water - £6,039,069
• PFAS - A whole system approach to an impossible problem – led by Severn Trent Water - £1,781,200
• Pipebot Patrol – led by Northumbrian Water - £1,615,325
• Pipebots for Rising Mains – Technology Development Phase 2 – led by Thames Water - £1,656,229
• Proving the concept of sewage sludge pyrolysis – led by Thames Water - £6,205,773
• Reducing Water Demand through Behavioural Incentivisation – led by Severn Trent Water - £1,874,010
• River Deep Mountain AI – led by Northumbrian Water - £5,080,719
• Self-Calibrating Sensor Networks for Sustainable Water Management (SCSN) – led by Southern Water Services Limited - £1,586,000 Sewage Sludge Gasification (Sustainably addressing sludge-to-land, net-zero and emerging contaminant risks) (formerly known as SENECA) – led by Yorkshire Water - £2,329,332
• SuDS iQ: A National SuDS Collaboration & Evaluation Platform – led by Southern Water Services Limited - £959,243
• Support for All – led by Northumbrian Water - £1,849,851
• Tapping into sewer heat – led by Severn Trent Water - £1,978,515
• Transforming Bioresources - the Benefits of Biochar – led by Severn Trent Water - £694,431

The next round of the Water Breakthrough Challenge will open in autumn 2024. More information will be published in the summer

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