10. Ballast Water

Ships are the transportation engines of the globalized world, responsible for moving around 90% of the global trade. Unfortunately, together with goods, food, and fuel, ships also transport uninvited aquatic organisms that can establish themselves in the receiving port with massive impact on the economy, public health, and the environment. With around 10 billion tons (10 km³) of ballast water being discharged every year, a United Nations led International Convention on the Control and Management of Ships’ Ballast Water and Sediments was adopted in 2004 and entered into force in 2017. The convention created regulatory framework to which the shipping industry and countries must comply. It means that all ships of 400 gross tonnage or more must manage their ballast water in a way that is approved under the convention. A great deal of work has been done by academic and industrial researchers to devise onboard ballast water treatment options based on various approaches. The regulations essentially have created a new unconventional water source based on treated ballast water. Two approaches are used for such treatments: onboard filtration (desalination) and onshore treatment (desalination). As desalinization is applied as a ballast-water treatment, the end-product (desalinated water) is free of invasive aquatic organisms and unhealthy chemical compounds and is usable for other economic activities such as public water supply and irrigation. Recent developments in desalinization processes have made membranes even more efficient, cost-effective, and compact, which is a perfect combination to be used onboard and onshore to produce a reusable, unconventional water from a ship’s ballast.