Investigation of the Impact of Marine Algae on the Corrosion of Mild Steel

Corrosion is a significant and continuous issue for all structures and vessels in the marine environment. Biocorrosion is a complex and poorly understood component of this and algal factors in isolation are the focus of this enquiry. An experiment was conducted to investigate the effects of the presence of marine algae Dunaliella tertiolecta on the corrosion of mild steel. These particular algae were selected because of their robustness and tolerance of adverse environmental conditions and their widespread existence. The aim of the experiment was to ascertain the effects of blooming algae on the corrosion of steel in a marine structure. Seven tubs of water were setup: a control containing filtered seawater; three to which a certain amount of algae was added; and three with double the concentration of algae added. In each of these tubs a piece of mild steel was suspended. The results uncovered three main findings. After 70 days, the amount of steel lost through corrosion was greater in the pieces exposed to algae than in the control, but the difference is small. Over a more extended period of time, the difference in corrosive damage was shown to be more for pieces immersed in algae. The nature of corrosion in seawater is more detrimental than in pieces subjected to algae.