Ship ballast tanks a review from microbial corrosion and electrochemical point of view

Microbiologically Influenced Corrosion (MIC) is the term used for the phenomenon in which corrosion is initiated and/or accelerated by the activities of microorganisms. MIC is a very serious problem for the ship industry as it reduces structural lifetime in combination with safety risks for crewmembers or inspection personal and increases maintenance costs. This review aims to focus on the importance and mechanisms of MIC in ship ballast tanks (SBTs). First section presents a literature review of general aspects of ballast tanks: structural properties including predominant environmental conditions. Second section summarizes the fundamental corrosion mechanisms within SBTs from an electrochemical point of view. Third section links microbial corrosion mechanism with electrochemical processes summarizing types of microorganisms, mechanisms of MIC and possible triggers for biofilm formation within this enclosed environment. For this an integral model, linking environmental parameters such as oxygen concentration, corrosion rate, nutrient availability and the microbial species of this environment is introduced in this paper. Fourth section gives an outlook on surface treatment and coating application in SBT. The last section considers the practical aspects of MIC detection and possible counterstrategies for engineers/operators and inspection personal. This paper gives a comprehensive overview of MIC processes in ship ballast tanks addressing engineers, equipment manufacturers and operators by offering practical solutions for an appropriate SBT management.