3428 Research report: Guidelines for the investigation of relationship between water content in biodiesels and microbial growth and contamination

Overview:

This publication presents the results of a laboratory study undertaken to investigate the influence of water content on the extent of microbiological contamination in hydrocarbon diesel (B0) and two biodiesel blends (B10 and B20).

The investigation consisted of two parts:

• The relationship between microbiological contamination and water content in laboratory microcosms for each fuel, which simulated fuel stored in tanks. The microcosms were held under defined conditions of temperature and humidity over a 14-week test period.
• The settling time for water and microorganisms in microcosms containing B10 and B20 at 400 ppm total water content was investigated.

For both parts of the investigation, the vertical profile of microbiological contamination and water content was determined by analysing sub-samples drawn from four distinct depths of fuel in each microcosm.

This publication provides details on the influence of:

• FAME concentration on the vertical distribution and concentration of water in fuel;
• FAME concentration on the vertical distribution and extent of microbial contamination in fuel;
• total water content on the vertical distribution and extent of microbial contamination in fuel, and
• settling time on the vertical distribution of microbiological contamination and water content in fuel.

This report follows on from the findings of EI Research report: Investigation of microbiological susceptibility of biodiesel and biodiesel blends and was commissioned by the EI Microbiology Committee.