Super-material graphene deployed in water purification

Water filtration membranes can be made twice as efficient using graphene. Image: Evove.

It has been known for years that graphene - the strongest material ever discovered - has a key role to play in supplying cheaper, cleaner water.

The challenge has been turning tiny laboratory trials of different technological approaches into large-scale industrial applications. Now a UK technology company, Evove, has successfully developed applications for graphene beyond the lab to to make water filtration membranes twice as efficient.

Water filtration membranes are used in all kinds of facilities, including water and wastewater treatment, desalination plants, food processing, oil & gas and mining. One of the big challenges for the engineers operating the plants is that the membranes easily get clogged - or fouled - and have to be cleaned with chemicals or replaced.

By developing a graphene-based coating that can be applied to any filtration membrane, Evove’s scientists say they can ensure the membrane filtration pores are more precise and regular, enabling the membranes to better separate and filter particulates.

“Not only does the membrane perform more effectively and foul much less often, it also uses a lot less energy to process liquids.”

Tom Pugh, Evove

Tom Pugh, vice-president of product development at Evove, explained, “We have applied our graphene-oxide coatings to all membranes regardless of material, shape or size. As the performance of the membranes improves, the advantages soon stack up.

“Not only does the membrane perform more effectively and foul much less often, it also uses a lot less energy to process liquids.”

Reduction of energy use is a touchstone for the water and wastewater sector, which has ambitious goals on net zero carbon emissions. Some 31.5 billion tonnes of carbon are emitted globally each year, and the water sector is responsible for 1 billion tonnes of it – around one-thirtieth.

Better water filtration can contribute to reducing that energy and carbon load – and lowering cost in the process. This is especially important in the water sector in England and Wales, where the plan is to reach net zero carbon emissions by 2030, 20 years ahead of the national target for all sectors.

What is less well known is that using graphene oxide coated membranes can help in the recovery and reuse of valuable resources like phosphorus and lithium from wastewater, while mitigating the risk of them polluting the water environment.

Pugh said, “Phosphorus is mined in only a few countries of the world and supplies are being depleted, but it is essential for use as a fertiliser to grow food. By taking phosphorus back out of sewage and wastewater, and refining it, it can be put back on the land in a circular loop.

“Lithium can also be extracted from mineral-rich waters like geo-thermal water, and is becoming ever more valuable due to the popularity of battery-driven electric vehicles. Currently, most of the lithium we used is mined, sent across the world for processing, and then sent around the world again within batteries.

"It’s a crazy and costly supply chain that localised harvesting from water can disrupt.”