The Treatment of Ballast water

Marine invasive alien species have increased due to traffic and trade over the last few decades. Ballast water is a marine invasive pathway that has introduced new species into the Caribbean region. Ballast water is seawater that is stored by large vessels or ships to provide maneuverability and stability. It is often stored in ballast tanks and discharged at other locations when it is no longer needed. The ballast water can contain biological material ranging from microorganisms like phytoplankton and bryozoans to small fish.  

Ballast water has been used to stabilize vessels at sea since the introduction of steel-hulled vessels. The practices of improving propulsion and maneuverability, reducing stress on the ship hull, and counteracting for weight changes in cargo due to water consumption and fuel, help to maintain safe operating conditions throughout a voyage. 

There are many treatments for ballast water to prevent the spread of marine invasive alien species. Deoxygenation is a method used to kill any living organisms in ballast water. This requires the injection of an inert gas such as nitrogen into the ballast tank, which asphyxiates the organisms. Another method is heat treatment which entails heating the ballast water in the banks. Heat disinfects the ballast water, which can be released afterwards.  

The ballast method that is used globally is the use of the ultraviolet ballast water treatment method. This consists of UV lamps that surround a chamber through which the ballast water is allowed to pass. The UV lamps (Amalgam lamps) act on the DNA of the organism, rendering them harmless and preventing their reproduction. This method has been successfully used worldwide and is effective against a broad range of organisms. 

Protecting the Caribbean region considering the global expansion of trade, has been recognized by the International Maritime Organization. The International Maritime Organization adopted the Ballast Water Management Convention which is a treaty that prevents the spread of non-native, aquatic organisms, and pathogens through a ship’s ballast water. All countries in the subregion are signatories’ sans Dominica and St. and the Grenadines. Read more about this in our policy brief ‘Prevention and Management of Marine Invasive Alien Species in the Caribbean’

The Ballast Water Management Convention requires all ships to implement a ballast water management plan. All ships must keep a ballast water record book and are required to carry out ballast water management procedures to a given standard. Protecting marine environments is essential for the livelihoods of many around the world. 


Filtersafe – What is Ballast Water Treatment? 

Policy Brief – Prevention and Management of Marine Invasive Alien Species in the Caribbean 

International Maritime Organization – Ballast Water Management 

MarineInsight – How Ballast Water Treatment System Works?