Reballasting at sea, as recommended by the IMO guidelines, currently provides the best available measure to reduce the risk of transfer of harmful aquatic organisms, but is subject to serious ship-safety limits. Even when it can be fully implemented, this technique is less than 100% effective in removing organisms from ballast water. It is important that alternative, effective ballast water management and/or treatment methods are developed as soon as possible, to replace reballasting at sea.
Significant research and development (R&D) efforts are underway by a number of scientific and engineering research establishments around the world, aimed at developing a more complete solution to this problem. Options being considered include:Mechanical treatment methods such as filtration and separation. Physical treatment methods such as sterilisation by ozone, ultra-violet light, electric currents and heat treatment. Chemical treatment methods such adding biocides to ballast water to kill organisms. Various combinations of the above.
All of these possibilities currently require significant further research effort. Major barriers still exist in scaling these various technologies up to deal effectively with the huge quantities of ballast water carried by large ships (e.g. about 60,000 tonnes of ballast water on a 200,000 DWT bulk carrier). Treatment options must not interfere unduly with the safe and economical operation of the ship and must consider ship design limitations.
A global ballast water treatment R&D directory has been released in response to a call for such an initiative. There are a large number of projects underway around the world looking at new methods for treating ballast water to remove or kill organisms.The directory can be accessed as a database on the GloBallast website in the Ballast Water Treatment section.