Ozone as a ballast water treatment technology

At MEPC 79 in December 2022, a relative newcomer, AirTree GmbH of Germany, submitted its BWMS for basic approval, but this was not granted. This BWMS uses a filter on uptake and treatment through in-tank ship-derived ozone.

Little is available on the website regarding the ballast water treatment system, but it seems to be connected to ozone-producing technology which originated in Taiwan.

According to the Ballast Water Treatment Technology database, there is one other ozone-based ballast water treatment system.

This comes from South Korea in the form of the NK-03 BlueBallast II from NK Co, which has a flow rate of between 200 to 8,000 m³ per hour. Very few other details are available, but it is reported NK-03 BlueBallast II received IMO basic active substance approval at MEPC 56 (July 2007) and IMO final active substance approval at MEPC 59 (July 2009).

In March 2020, the NK Co system was type-approved by the US Coast Guard.

According to the NK Co website, ozone treats ballast water in the following fashion, “A ship-board ozone generator takes ambient air and strips away the nitrogen, concentrating the oxygen content which is then passed through a high-voltage or high-frequency electrical field to produce ozone.”

“The ozone is then injected into the incoming ballast water to oxidise and neutralise any harmful aquatic species. A percentage of the aquatic species, especially any bacteria and viruses in the ballast water, are killed by direct contact with the ozone. The remainder are killed or neutralised when the ozone reacts with other chemicals that occur naturally in seawater, to form hypobromous acid, a highly effective disinfectant in its own right.”

Ozone as a treatment medium for ballast water systems has also attracted further academic research. A paper, Ballast water treatment by ozone nanobubbles, submitted by Petroula Seridou, Eleftheria Kotzia, Konstantinos Katris, and Nicolas Kalogerakis to the Journal of Chemical Technology and Biotechnology, describes using ozone in the form of nanobubbles.

The study is designed to explore and provide insight into inactivation of heterotrophic bacteria in saline water and examine the use of ozone nanobubbles for disinfecting saline water.