Copper load to the marine environment from Impressed Current Anti-Fouling (ICAF) systems
Typ
Examensarbete på grundnivå
Program
Publicerad
2021
Författare
Alexanderson, Jonatan
Sjöström, André
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The seawater cooling system onboard a vessel is essential for propulsion and operation. Without a functioning seawater cooling system, the vessel’s safety will be compromised; all equipment dependent on cooling would overheat, and most vessels also rely on seawater for firefighting. Therefore, it is crucial to minimise the settling of mussels and other biofouling species that reduce the water flow inside the pipework. There are several different treatment methods to use, and one of the most common is Impressed Current Anti Fouling (ICAF). ICAF relies on electrolytic release of copper ions into the sea chest and seawater pipework. As mussel larvae are very sensitive to copper ions, the method is efficient to prevent growth inside the pipes. This study aimed to investigate the amount of heavy metals, especially copper, emitted to the sea from ICAF systems. Samples from the seawater cooling system onboard nine ships (seven RoPax ferries, one RoRo-vessel and one tanker) were analysed with respect to metal content. The results revealed that the copper emissions from ICAF were significantly higher, with a median value of 42,7 μg/l, than the concentration of 2 μg/l given by the manufacturers. Depending on the vessels, the environmental load of copper from ICAF was ranging from 74-182% of the load from the vessels’ antifouling paint. The conclusion was that the copper load caused by ICAF-treated seawater must be accounted for when considering the emissions caused by ships.
Beskrivning
Ämne/nyckelord
electrolysis , MGPS , ICAF , copper emissions , seawater cooling system , mussels , heavy metals , vessels