Ballastivesi

Ballastivesi is the Finnish term for ballast water, the water that ships take on or discharge into ballast tanks to maintain stability, trim, draught, and maneuverability when cargo is loading or unloading. Ships may fill ballast tanks in port or at sea and later release the water to adjust buoyancy as needed.

The water taken on board can be seawater or freshwater, depending on the voyage and the tank’s location. Ballast water often contains microorganisms, plankton, small invertebrates, sediments, nutrients, and chemicals. When discharged in a different port or coastal area, these organisms can become invasive species, disrupt local ecosystems, and spread pathogens or pollutants. The issue is particularly acute in enclosed or sensitive marine and brackish environments, including the Baltic Sea and other inland seas.

To mitigate ecological risks, international and national rules govern ballast water management. Ships are required to have a ballast water management plan and a ballast water record book, and they must comply with discharge standards or ballast water treatment requirements. Management methods fall into two broad categories: ballast water exchange (BWE), which replaces coastal water with open-ocean water to reduce coastal organism concentrations, and ballast water treatment systems (BWMS) installed on board that physically or chemically treat water before discharge. Common treatment technologies include filtration, UV irradiation, chemical disinfection, and electrochlorination.

Regulatory frameworks include the International Maritime Organization’s Ballast Water Management Convention and regional implementations. In regions such as the Baltic Sea, special considerations and stricter controls are applied due to sensitive ecosystems. Ongoing advances aim to reduce costs, improve reliability, and prevent the spread of invasive species while maintaining safe maritime operations.