Ground Transport

The Ground and Transport sector is essential for global mobility, relying on fuel quality and vehicle reliability to ensure effective movement across road and rail. However, microbial contamination of ground fuels, combined with microbiologically influenced corrosion, poses substantial operational and financial risks by compromising fuel quality, jeopardising vehicle safety, and weakening infrastructure.

Microbial contamination of ground fuels occurs when bacteria, yeasts, and moulds grow in fuel systems, often due to the presence of water in storage tanks resulting from condensation or contamination from environmental sources during transfer or storage.  The now commonplace use of biodiesel blends further increases in the potential for microbial contamination in fuels, as biofuels are more hygroscopic and the bio-component, Fatty Acid Methyl Ester (FAME), is readily biodegradable by microorganisms.

Substantial microbial growth in fuel storage tanks can lead to the formation of microbial sludges.  Transfer of fuels contaminated with microbial material can clog vehicle fuel filters and engine injectors, leading to potential performance issues, higher maintenance costs, and engine longevity, and additional maintenance of the engine and fuel systems to ensure smooth operations.

Microbiologically influenced corrosion is also a major concern for fuel tanks, pipelines, and vehicle fuel systems.  Multicellular microbial biofilms containing bacteria embedded in extracellular polymeric substances (EPS) are known as biofilms.  Biofilms can either result in microbiologically influenced corrosion by direct action on surfaces, for instance by producing acid, or more commonly can create an oxygen gradient in a “corrosion cell” on the surface, resulting in corrosive electron flow across the surface.  A specific type of microorganism known as Sulphate Reducing Bacteria (SRB) produce highly corrosive hydrogen sulphide as by-product of metabolism that quickly deteriorates metal surfaces; the resultant microbiologically influenced corrosion risks fuel leaks and structural damage and poses a significant health hazard to personnel due to the presence of highly toxic hydrogen sulphide.  The effects of microbiologically influenced corrosion are particularly pronounced in aging fuel infrastructure and vehicle fleets, where microbiologically influenced corrosion can lead to costly repairs and frequent component replacements.

Effective management of microbes in fuel is essential for ensuring fuel reliability, minimising downtime, and extending vehicle life.  Preventative strategies to mitigate microbial contamination in ground fuels include biocide use, effective water removal, and routine fuel testing.  Regular tank cleaning and the use of antimicrobial additives further protect fuel systems.  As the sector integrates biofuels and adapts to changing fuel compositions, managing microbial risks will remain a critical priority for sustainable and safe transport operations.