Ballast water treatment techniques: review and suggestions regarding use in the Arctic and Great Lakes

The retreating ice cover opens up the opportunity for new shipping routes, and consequently shipping traffic in the Arctic region is increasing and with this the risk of introducing non-indigenous species (NIS) via ballast water. Ballast water must therefore be treated to prevent the transport of NIS in an environmentally friendly way to minimise the environmental impact of the treatment. There is, however, limited information on the suitability of different ballast water treatment methods for use specifically in Arctic conditions. A literature study was conducted to identify and summarise different ballast water treatment methods, evaluate their potential for use in the Arctic, and to identify gaps in the current knowledge on Arctic ballast water treatment for further investigation. As winter conditions on the Great Lakes present a useful analogue for Arctic operation, these conditions were also included in the scope of work. Three basic methods for ballast water treatment were addressed: mechanical systems, physical disinfection, and chemical treatments. In ballast water treatment systems often a combinations of these techniques is applied. From the literature, each technique was described and evaluated regarding key environmental conditions present in the Arctic and Great Lakes regions, such as salinity, temperature and turbidity.