PFAS

Ofwat announces that the Yorkshire Water ATC Gasification Project has been awarded a share of PS40million in its latest Water…


A consortium led Yorkshire Water has received PS2.3m (£2.3 million) from the Ofwat Innovation Fund for its Advanced Thermal Conversion Gasification (ATC) technology.

This project is led by Yorkshire Water in partnership with Enertecgreen, a gasification technology provider, along with Queen’s University Belfast and other partners including Thames Water, United Utilities. Anglian Water. Scottish Water. Irish Water. Northern Ireland Water. Southern Water. Wessex Water.

Gasification is a process that converts sewage sludge to useful products, such as biochar and vitrified ash “stones” or a hydrogen-rich synthetic gas (syngas). The process is designed to operate at high temperatures in order to destroy other contaminants, such as microplastics and chemicals like PFAS.

The project, if successful, will show the circular economy at work by testing biochar both as a media for wastewater treatment and as an additive to brick production.

Carbon-rich biochar can be used to improve soils, increase water retention and nutrients, and because it does not decompose easily, it is also an effective way of sequestering soil carbon.

The’stones of vitrified ash’ can be used in construction to reduce carbon footprint. Syngas, a mixture of hydrogen, carbon monooxide, methane and carbon dioxide, can be used for green electricity as well as other high-value products like aviation fuel.

Dr Danielle Hankin, innovation programme manager, Yorkshire Water, said:

“The conversion of sewage sludge to gas, biochar, and ash stones opens up new, sustainable uses for waste products. We are proud to have pre-empted changes in legislation and consumer attitude by delivering an innovative technology that benefits consumers, the environment, and future-proofs water industry.

Once proven, Gasification will create sustainable wastewater treatment media, construction materials, green electricity and high-value products like biomethanol or aviation fuel. Our work is a crucial step towards driving the UK to a more sustainable, resource-efficient future.”


Helen Campbell, senior director, Ofwat said:

There are many challenges that need to be addressed in the water sector. Some are well-known, while others are not. Our fourth Water Breakthrough Challenge called for solutions that could deliver a wide-scale, transformative change for customers and society – which is exactly what the winners of today have done. Raingardens, which prevent flooding, green energy produced from treated sewage and robots patrolling the pipes are just some of the solutions that the Water Breakthrough Challenge winners have come up with.

The Water Breakthrough Challenge, organized by Challenge Works in partnership with Arup and Isle Utilities is one of several competitions run by Ofwat to encourage innovation and collaboration within the water sector.

It supports initiatives to help tackle the most challenging challenges in the water sector such as achieving net-zero, protecting natural ecologies, and reducing leakage.


Background

ATC Gasification was designed to reduce greenhouse gas emissions, mitigate legislative changes regarding the disposal of sewage waste and provide an alternative for energy independence.

The UK produces approximately 1.4 million tonnes per year of solid sewage sludge, of which 87% are currently digested anaerobically and used on the land. The process is currently under pressure, and incineration or landfilling are neither environmentally sustainable nor financially feasible alternatives.

Yorkshire Water has been researching alternatives to the existing process for more than 12 years. This began with a pyrolysis trial at Esholt and culminated with the development of a small-commercial ATC Gasification plant at Lower Brighouse in Huddersfield, in partnership with Enertecgreen.

Yorkshire Water is delighted with the OIF’s success after a series of interactions. The project will be implemented in partnership with ETG and Queen’s University Belfast. The project will gasify and dry batches of 100% sewage over a 20-week period, proving its technical and commercial viability as a sustainable conversion process.


Gasification product utilisation

Yorkshire Water estimates that due to the tightening of phosphorus removal permits, its consumption of ferricsulphate coagulant will increase from 7,000 tonnes to 77,000 tons per year by 2025. This is expected to cost an additional PS19m each year.

Queen’s University Belfast’s initial lab-scale research has shown that biochar derived from Gasification could be used to treat wastewater to remove phosphorus, and as an alternative to ferric dosage. The University will evaluate the Gasification process’ ability to destroy contaminants such as microplastics and PFAS.

Enertecgreen has already begun discussions with the UK’s largest brick producer about the use of vitrified ash stone and biochar in the construction industry. Biochar is being used as a carbon-source in the production sustainable fertilisers.

Syngas rich in hydrogen could be used locally to generate power and heat, or fed into the national grid. It could also be converted into high-value products like biomethanol or aviation fuel.

Once proven, the modular Gasification Process could be used as a centralised sludge-processing hub or it will allow water companies to process their sludge locally, converting them into renewable energy and valuable products. It will be the first time 100% of sludge is processed at a large-scale.


Benefits

Gasification converts 80% the energy of sludge into usable energy. It also reduces the regulatory risks that come with the disposal of sludge on land. Gas and heat are produced from every 10 tonnes dry sludge.

The plant produces more than enough power and heat to meet all of its own needs, and any surplus energy is available to meet other power and heating demands.

Yorkshire Water produces approximately 160,000 tons of dry sludge each year. Gasification can generate 50MWee using a power optimized plant configuration. This will make the process energy independent. The excess energy can be used for other parts of the business, contributing to Yorkshire Water’s Net Zero goals.

The UK produces approximately 1.2 million tons of dry sludge each year, and the number is growing. Gasification could convert this sludge in sustainable products and remove it from the land. It would also generate 375MW of renewable electricity for industry.

It is important to note that the sludge has been processed and consumed, so that there are no solid residues on the land. All contaminants such as microplastics or chemicals like PFAS have also been destroyed.

Syngas will be initially used to generate electricity, but in the future it will be converted into bio-energy products such as bio-methanol or sustainable aircraft fuel.