What type of ballast refers to seawater introduced into cargo tanks after cargo discharge?

The term that describes seawater introduced into cargo tanks after cargo discharge is known as "dirty ballast." In the context of tanker operations, when seawater is taken on as ballast to stabilize the vessel after the cargo has been unloaded, it may carry sediments, contaminants, or residues that have accumulated in the tanks or in the water. This is particularly the case for tankers that have previously transported oil or chemicals, where using seawater can involve carrying with it certain pollutants.

This terminology helps in differentiating between various types of ballasts used during the operations of tankers. While "clean ballast" refers to water that has been treated to remove any residues, "dirty ballast" indicates the presence of pollutants alongside the seawater. Understanding this distinction is crucial in managing the environmental impact of ballast water discharge and adhering to regulatory guidelines regarding the treatment of ballast before it is released back into the sea.