Ballast Water Treatment Methods

Ships need ballast water for their stability and manoeuvrability. This water is not pure, but it contains a sample of the local ecosystem at the place of intake. Within a few days to weeks, vast quantities of water are shipped from one continent to the other. At the port of destination, ballast water is often pumped overboard, including the organisms it still contains. The receiving ecosystem is not always well adapted to the reception of newly introduced species. Such new species sometimes develop into a plague, pushing native species to the edge of their existence.
Ships transport 5-10 billion tons of ballast water annually all over the globe, loaded with a enormous variety of organisms. These organisms belong to the natural ecosystem in the port of origin but are often not present in the ports of destination at the end of a ship’s journey. In hundreds of cases around the world, this has resulted in severe damage to the receiving ecosystem because the non native organisms developed into a pest. This can have a high impact on the ecosystem, resulting in a decrease of stocks of commercially valuable fish, shellfish species and occasionally outbreaks of diseases like cholera. To minimize these risks for the future, the International Maritime Organization (IMO) of the United Nations (UN) has adopted a Ballast Water Convention in 2004. This Convention states that starting in 2009 for ships with a ballast water capacity below 5000m3 to finally all ships (> 50,000 in number) in 2016 should install certified Ballast Water Treatment (BWT) equipment on board.…