Building NextGen wastewater treatment systems

The four-year NextGen project brings together a partnership of 30 organisations to demonstration solutions for water in the circular economy. The democase in Severn Trent (UK) evaluates and improves the anaerobic processes to make it suitable for our colder, more variable climates. Estimations go that 22,000 wastewater treatment plants across Europe consume more than 1% of the EU’s overall electricity consumption.

To put this into a local perspective, Severn Trent spends an average of £15 million per year on energy to run its activated sludge plants, says Peter Vale, the technical lead for innovation at UK utility, Severn Trent. The ambition of the democase is to build an energy-positive WWTP, by switching from energy-intensive aerobic treatment to energy neutral, potentially even energy positive, anaerobic treatment.

Europe’s largest AnMBR

One notable development is the development of “Europe’s largest” Anaerobic MBR, (AnMBR) process. Historically used in warmer climates, such as Brazil, Anaerobic treatment has been successfully implemented to treat the wastewater from millions. Severn Trent has been working with partners Cranfield University to see how anaerobic treatment works in more variable climates.

“It makes no sense at all, in terms of an energy balance, if you start heating the wastewater,” he says. “We are focused on making the process viable for much colder temperatures with weaker wastewater, rather than sludge”. The key is the addition of the membrane, which intensifies the process and makes it work in colder environments. The method also allows the recovery of nutrients from the AnMBR effluent that can be used in high-value fertiliser products. Furthermore, the ammonia can serve as an “energy store”, either directly used as a fuel or converted to hydrogen. It may even be possible to produce added-value products such as protein, according to the technical lead.

Farmer partnerships are key

Generating additional valuable nutrients from wastewater streams is one thing. Selling them to the market on a large scale is another. Severn Trent has set up a dedicated farm liaison team that communicates with the region’s well-developed agricultural community. We bring in the end-users, the farmers and the regulators into these circular economy conversations from the start,” adds Vale to assure the product what the farmers want, rather than what can we produce.

Creating regional resource hubs

Christos Makropoulos, a professor at the National Technical University of Athens and a principal scientist at KWR, believes the potential is to turn wastewater plants, such as Spernal, into regional “resource hubs”, but regulatory challenges remain. “We have the technology available to create regional resource hubs, but regulatory and governance challenges remain because we have to connect multiple industries and stakeholders,” he says. “I would be very happy if, by 2030, there was one state-of-the-art treatment plant, with a new vision and business models in place, all underpinned by digital technologies and data in each member state.