The small-scale trial to remove a straw-coloured tinge from the water, caused by resins in the fibres being recycled, ran continuously for several months.

According to Arvia co-founder and technical director Nigel Brown, "taking out the colour means the water can be re-used".

Approximately 5% of Shotton's effluent water was treated by the unit. The mill is now evaluating data from the trail to calculate the economic impact of the process.

UPM UK head of energy & utilities Andrew Bronnert said the tests could improve the water treatment process: "For paper mills, water usage is an important issue and the target is a closed-loop system. This could lead us further towards closed-loop water."

However, Bronnert added that a closed-loop system would still need energy to cool the water.

Brown said the process may have applications for removing any organic colouring from the water, including ink. This could offer a solution for de-inking digital print, particularly dye-based inks used in high-speed inkjet machines. There may also be applications for treating printers' waste water.

"If it’s water-based and organic, I’d assume we could treat it," Brown added.

Nyex is a chemical-free process for adsorption – it works in a similar way to the activated carbon techniques commonly employed in water treatment but can be electrically regenerated rather than needing to be sent to landfill or incinerated.

It was developed with work carried out by the School of Chemical & Analytical Sciences at The University of Manchester, where Brown’s co-founder and the firm’s research director Ted Roberts is senior lecturer.