How a Cumbrian company is taking on the world's sludge

The alleged discharge of raw sewage into Windermere has been blamed for causing harmful algal blooms during the summer by campaigners.

It is a problem which caught the attention of entrepreneur Brian Scowcroft, owner of Carlisle’s Kingmoor Park Enterprise Zone and the man behind a number of successful ventures across the UK.

Two years ago, Brian gave staff at Mitchell Dryers, which he owned and which was based at Kingmoor Park, the mission of developing a way to process sewage or sewage sludge - which is the semi-solid waste left over after the liquid and solid constituents of wastewater are separated by settling.

Mitchell Dryers went into liquidation last year, but not before chemical engineer James Meyer had developed a way to use its industrial drying expertise to process the waste.

A new company, Onunda - which is the old Norse name for Windermere - was subsequently set up with James as its chief technology officer.

Another well-known name from Cumbrian business, Tom Samson, was appointed as CEO.

Before taking on the role Tom was CEO of Rolls-Royce SMR, focused on bringing its small modular reactor technology to the county. Prior to that he was CEO of NuGen, the consortium behind the proposed, but ultimately unsuccessful, Moorside nuclear power station.

Tom says currently 90 per cent of the roughly one million tonnes of sludge produced in the UK every year ends up being spread on the land for agricultural purposes. Although this is legal, it causes environmental issues as the sludge contains micro-plastics, forever chemicals and pathogens as well as excessive nutrients which can also find their way into rivers and lakes.

The rest is incinerated, which comes with its own environmental concerns around air pollution.

"We had a team in Mitchell Dryers at the time that was designing and building gasifiers and dryers. Brian thought maybe there's a way we can use this technology to try and tackle this type of sewage pollution and try and turn the sewage problem into a source of value of energy and nutrients,” says Tom.

"James came up with this new integrated design using some of the gasification and dryer technologies that we had in Mitchell Dryers, together with some more innovative technology, to create a new process, which tries to extract all the energy, nutrient and values from sewage sludge to create a better outcome where there's no material being discharged back to the environment.

“We are not claiming Onunda is the solution to the problems in Windermere but it is where the inspiration for change came from.”

The process uses a series of drying and pressure vessels in which sewage is exposed to high pressure and temperatures to break it down into its constituent components.

This is then mechanically dewatered to destroy chemicals or microplastics and create a char which is put into a gasifier to create synthetic gas to provide the energy to power the process.

"We don't need to use any fossil fuels to treat the sewage or the sludge. In fact, we have excess synthetic gas that can produce clean power that goes back onto the grid,” says Tom.

A high nutrient liquid is produced as a byproduct which can be used in fertiliser and to fuel anaerobic digesters.

"Then we have a high ash residue, which is the ash that comes off the gasification process, and that contains very, very rich nutrients as well and stable properties that have applications in the construction industry and as a material which potentially can be used for other agricultural applications, but agricultural applications that don't leach into the waterways. It's not a wet slurry that goes onto land, it is a dry slurry that has certain nutrient properties,” says Tom.

"If we integrate this to an existing wastewater treatment plant, we could actually drive towards a solution where we significantly reduce their operating costs, we boost their biogas production and we remove the need to return any sludge back to land.”

Tom says Onunda is currently looking for a partner to work with to launch a pilot in the UK this year before commercialising it and taking it to a global market.

"It's a global problem and this is a global solution so we are really excited about the scale of that prospect,” says Tom.

While a pilot plant will process 30 tonnes a day, Tom says a commercial plant could tackle 350 tonnes daily. This means around 50 plants would be needed to deal with the sludge which the UK produces every year.

He says there is the potential for the process to create credits which could be purchased by housebuilders to fulfil government requirements on ensuring developments do not impact  nutrient neutrality in water catchments.

"We have spoken to some housebuilders, including in Cumbria, about how this technology could actually unlock nutrient neutrality credits and allow them to continue with their housebuilding plans,” says Tom.

“There's the possibility for those housebuilders then to potentially invest in a pilot plant or a commercial plant, because they would unlock those nutrient neutrality credits to begin building houses.

"The technology itself would appear to be doing exactly what the industry and what the environmental campaigners need to happen in order for us to be able to address nutrient imbalance by removing the sludge from the land. Onunda represents what is possible in the circular economy, turning waste into a source of nutrients and energy with no pollutants back into the environment.”

Although the business has a national and international focus, Tom says he would love for it to be used at wastewater treatment plants in Cumbria to help tackle pollution in local rivers and lakes.

He says Onunda’s environmental mission has a direct link back to his work in nuclear.

"I think there's lots more things happening positively in nuclear new build, but for me it was just taking too long. I'd given it everything I had to give and I thought it was time for me to try something different.

"Most of the world are struggling with how we deal with the consequences of sewage disposal. So it's an opportunity to have more of an impact in the environmental landscape at a quicker pace than I was having with nuclear.

"The purpose behind the nuclear industry and trying to address climate change is what drew me in and got me passionate about my contribution to that sector.

“It's that same purpose here. The purpose of finding technology and innovation that can be applied to address the negative environmental consequences of dealing with sewage and other organic waste is what has really driven me here to this position.”

Onunda are working in collaboration with Newcastle University and they have recently been successful in securing a Prosperity Partnership grant from Innovate UK to help further develop the technology.

To find out more go to www.onunda.com