Ship technology could enhance process-water safety

A technology used for treating ballast seawater on ships is now being offered as an alternative to chemical-based water treatments in the process industries.

To protect local ecosystems, ships are obliged to ensure that the ballast water they release does not contain unwanted foreign bodies when it is jettisoned – often thousands of miles away from where it was taken on board.

Conventionally, a combination of boiling, filtering and chemicals is used to kill bacteria, viruses and other microbiological impurities, but Swedish company Wallenius has developed a chemical-free approach to the problem.

The ‘advanced oxidation technology’ (AOT) uses the action of light on photocatalytic semiconductor surfaces, to produce free radicals, which break down microorganisms and other pollutants in water. It is said to achieve 99.999% Legionella ‘kill rates’ within microseconds, and require less energy and cost than existing treatments.

Wallenius is now exploring wider uses for AOT, which is already employed in evaporative cooling systems in the Scandinavia and Germany. Other target applications include treating water used in manufacture and as an ingredient in the food and beverage industries

In hot and cold water systems, AOT can stop bacteria from entering the storage tanks and then keep the water “fresh” when re-circulating. It can also be used on hot water services to reduce operating temperatures, while retaining bacterial cleanliness.

“Our clients have to battle with the combined pressures of having to save money, be green and remain compliant with legislation. The Wallenius AOT approach [uses] less energy and cost to achieve greater safety and reassurance.” said Steven Booth of Guardian Water Treatment, which is introducing the technology across the UK.