Researchers report breakthrough in hydrogen-producing wastewater treatment technology

TECHNOLOGY UPDATE

Researchers at the University of Warwick have developed a system that could reduce significantly the cost of producing hydrogen from untreated wastewater using an established laboratory scale method. Hydrogen is seen as a promising substitute for petrol and natural gas in transport and heating.

The Warwick team has used recycled carbon fibre matting as electrodes in so-called Microbial Electrolysis Cells (MECs) These cells harnesses the capacity of some bacteria and other microscopic organisms to accelerate the breakdown of sewage and other organic material by electric current to produce hydrogen.

Carbon matting, the researchers said, costs a fraction of 1% of the “several hundreds of pounds per square metre” for graphite or carbon block electrodes used in MEC’s to date. And the researchers have reported that the bacteria it developed on recycled carbon fibre electrodes, had better temperature tolerance and produced more hydrogen than existing systems.

The carbon matting finding emerged from a study by the Warwick team – commissioned by Seven Trent Water – into more energy-efficient ways to treat wastewater. As well as producing hydrogen from organic constituents the MECs clean wastewater. According to Severn Trent Water, a pilot scheme at its Minworth waste treatment site, processed up to 100 litres of wastewater a day and removed 51% of organic pollutants and up to 100% of suspended solids from the water while producing 18 times more hydrogen, at 100% purity, than systems using conventional carbon electrodes.

Project leader, Dr Stuart Coles, from the University of Warwick said: “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 next phase of this work is look at optimising the design of the microbial electrolysis cells and further reduce the level of pollutants in the water. This in turn should help produce even more hydrogen,” Coles added.

Chief engineer at Severn Trent, Bob Stear, said: “The performance boost and cost savings demonstrated from this research mean that MEC technology is one step closer to being cost competitive with existing wastewater treatment assets. We’re currently scoping scaling up the technology at our test-bed plant in Redditch.”