Ultraviolet (UV) radiation is commonly used to purify water as direct exposure to this form of light kills harmful bacteria. UV photocatalyst systems (that use light to accelerate a chemical reaction) are already used for water purification. A major barrier to their widespread take-up has however been their use of mercury lamps. Used to produce UV, the lamps are relatively bulky and inefficient, while the mercury poses a risk to human health and the environment.

As an alternative, the EU-funded project AQUA-PULSE has developed a prototype system that is, in tests, effective against a wide range of chemicals and organisms, yet safer and cleaner than systems using mercury lamps.

Instead of using mercury lamps the project combined low-cost UV light emitting diodes (LEDs) with a specially tailored material called titanium dioxide (TiO2) that works as a photocatalyst. The UV light breaks down organic chemicals, bacteria and other pollutants in water.

“There are still some refinements needed in terms of design, but I am convinced that our prototype is more compact, aesthetically pleasing and environmentally friendly than what is on the market currently,” says AQUA-PULSE project coordinator Liam Lewis of the Cork Institute of Technology in Ireland.

AQUA-PULSE’s technology has been hailed a ‘disruptive technology’ that has the potential to shake up the water purification industry by offering a cheaper, more compact alternative to existing technologies, adds Lewis.

Testing and modelling

For the prototype, the team tested various UV LEDs in a range of configurations until they arrived at the best arrangement. Several photocatalysts were also examined until the researchers found the optimal material. Finally, a prototype reactor using an immobilised photocatalyst with UV LEDs was built and tested by one of the project's SME partners in Norway.

The AQUA-PULSE technology is, for the moment at least, best suited for use in aquaculture, and in particular, in small volume recirculating systems such as fish tanks.

“We think the AQUA-PULSE system would be a great fit with fish farming,” says Lewis. “But we will also explore other potential industries.”

Water purification is commonplace in residential homes, offices and hotels, as well as in water supply and wastewater treatment.

Strong growth predicted

The two-year project brought together three European small to medium-sized enterprises (SMEs) and three educational establishments operating in different yet complementary, technology areas. The finished water purification technology is expected to bring significant commercial benefits to all of the SME partners, be they suppliers of components, manufacturers or sellers. The global demand for water treatment products is €35 billion annually, with strong growth foreseen.

The AQUA-PULSE project has now ended but says Lewis, it is only a matter of time until the SME partners capitalise on the research and bring a ground-breaking product to market.