Severn Trent has set out plans to scale up a successful trial of hydrogen production from wastewater using carbon fibre mats developed by researchers at the University of Warwick.
The project built upon research by the university into microbial electrolysis cells that use electromagnetic organisms to break down organic pollutants in wastewater and produce hydrogen.
The water company approached the team at the university to develop a more energy efficient way to treat wastewater as it works to reach carbon net zero by 2030. Process emissions pose a significant challenge to the sector’s efforts to lower greenhouse gases, with work to measure and capture emissions from sewage plants still in its infancy.
Earlier work by Warwick into using microbial electrolysis cells had proved cost prohibitive at scale and resulted in low hydrogen production rates. The researchers subsequently developed an alternative technique using recycled carbon fibre mats in place of more expensive graphite and trialled them on synthetic and real wastewater.
The tests showed the newer mats had better temperature tolerance so more bacteria developed on them. This resulted in more hydrogen being produced at a lower cost.
The trial was scaled up at Severn Trent’s largest sewage processing plant at Minworth where the carbon fibre mats removed 51% of organic pollutants and up to 100% of suspended solids while producing 18 times more hydrogen than the graphite mats.
Bob Stear, chief engineer at Severn Trent said: “The performance boost and cost savings demonstrated from this research mean that microbial electrolysis cell technology is one step closer to being cost competitive with existing wastewater treatment assets.”
Severn Trent plans to further scale up the technology at its test-bed treatment plant in Redditch.
Stuart Coles, who oversaw the work at the university, said: “By taking waste from the automotive and aerospace sectors, we have developed a circular solution to a longstanding problem. Instead of just treating the wastewater, we are now able to extract value from it in the form of hydrogen at a lower cost than ever before.”
The team will now optimise the design of the microbial electrolysis cells, which Coles said should result in even higher rates of hydrogen production and pollutant removal.