Microbial Growth in Fuel Systems
Free water at the fuel-water interface in storage tanks creates an ideal environment for microbes to proliferate. Sulfate-reducing bacteria (SRB) and Hormoconis resinae (the jet fuel fungus) consume hydrocarbons as a carbon source and produce acidic metabolites that corrode tank linings and pipework. The biomass itself clogs filters and causes rapid filter differential pressure buildup, leading to unscheduled shutdowns and maintenance.
Biodiesel blends (FAME) are especially susceptible due to higher water solubility and richer nutrient content. In tropical climates like Indonesia’s, elevated temperatures further accelerate microbial growth rates, making consistent biocide treatment essential across storage, distribution, and end-use applications.
Common indicator: Dark sludge at tank bottom, green or black biofilm at the fuel-water interface, or rapid pressure buildup across fuel filters are all signs of active microbial contamination requiring immediate treatment.
Fuel Types and Microbial Risks
| Fuel Type | Key Risk | Biocide Approach |
|---|---|---|
| Diesel / ULSD | Bacterial and fungal growth; MIC tank corrosion; filter plugging from biomass | Shock dose to eliminate existing contamination; maintenance dose through supply chain |
| Biodiesel Blends | Accelerated growth. FAME is nutrient-rich and retains more water | Higher treat rates; biocide must be compatible with FAME; regular monitoring at terminals |
| Gasoline / Ethanol Blends | Phase separation creates free water layer; ethanol-tolerant microbes | Ethanol-compatible biocide; control of interface contamination |
| Aviation Turbine Fuel | Hormoconis resinae clogs aircraft filters and degrades tank sealants | DEF STAN 68-251 / ASTM D6424 approved products (typically DiEGME-based FSII or Biobor JF) |
| Marine Bunker / VLSFO | Microbial growth in settling tanks; instability from multi-source blending | Broad-spectrum treatment compatible with residual fuel systems |