Ballast water treatment technologies
The entry into force, on September 8, 2017, of the International Convention for the Control and Management of Ships’ Ballast Water and Sediments, requires that most ships navigating Canadian waters are equipped with a ballast water treatment system once the convention’s provisions had been translated into Canada’s legal and regulatory framework.
Ballast water treatment systems are meant to either kill or inactivate (make infertile) aquatic organisms that are present in ballast water. These organisms may be non-indigenous and pose a threat to public health, marine infrastructures and ecosystems once the ballast water is released into the receiving waters.
There are three categories of treatment systems: mechanical (e.g. filtration, flocculation), physical (e.g. UV radiation, ultrasounds, deoxygenation) and chemical (e.g. chlorine or ozone disinfection, electrolytic chlorination). Most treatment systems combine at least two of these methods to make sure the treated ballast water meets IMO’s discharge standards.
Choosing the right treatment method is very complex as it involves many limiting factors such as: available space on board, physical and chemical properties of the waters in which the ship navigates (temperature, salinity, and turbidity) impacting the system’s effectiveness, the ease and cost of installation, the treatment of residues, etc. The choice is particularly limited within the St. Lawrence and the Great Lakes because ships must navigate in waters with variable temperatures and salt concentrations. Ocean going vessels that operate in the Great Lakes therefore require a system that is able to operate in different environments.
Several ship owners operating in the St. Lawrence have been actively involved in research and development or test-trialed systems on board their ships.
For instance, Canada Steamship Lines (CSL) tested several prototypes in the Great Lakes under a U.S. Coast Guard voluntary program. CSL was also able to test the effectiveness of filters to treat their ballast waters.
For its part, Fednav has invested millions of dollars over the last years to test multiple treatment systems to be able to confidently order twelve treatment systems to be installed on its new vessels. It is the first company in the Great Lakes to do so, well before the convention entered into force.