1. Sediment in Ethanol Blended Gasoline (Impact on underground storage tank)
August 25, 2016

2. Background Information Georgia State Oil Laboratory Activities FY2016 (from 7/1/2015 – 6/30/2016)
12,451 fuel samples across Georgia were tested.
Sample failure rate was extremely high:
1083 samples did not meet Georgia State specifications
8.7% of fuel sample failed
Three major categories of failures
Flashpoint (discussed in 2015 August meeting)
Sediment (our focus for today)
Water-related issue

5. Why focus on sediment in gasoline
Increase from less than 5% in FY2012 to more than 30% of all failure fuel samples in FY2016
90% of sediment failed samples were gasoline
99.9 % of sediments were orange/tan in color
Sometimes, it take 24 hours to be visualized
May affect more than 2% retail stations
Potential clogging fuel injector orifices or fuel filters
The workmanship clause in ASTM D4814 (ethanol blended gasoline) states that “gasoline shall be visually free of undissolved water, sediment, and suspended matter”

6. What is the SEDIMENT?
Colonies

7. A milky layer of colonies

8. What is this sediment ?
Fungi, bacteria, molds, yeasts or metallic materials (rusts)
Hypothesize one type of sediments is bacteria known as “Acetobacter” – more evidence is needed
Acetobacter probably not harmful to humans
Bacteria can survive in an acidic environment with a pH of 4
Orange in color, clusters (colonies); about 2-micron diameter and about 8-micron long
Produce acid in the presence of ethanol and oxygen
Working with a local college (ABAC) to confirm the bacteria hypothesis – using SEM, DNA sequence, or apply a research grant (?).

9. Acetobacter bacteria spores

10. Treatment Recommendation
Thorough cleaning of the tank
May need to apply a biocide treatment
Install a minimum of 2-micron nominal filter at the pump dispenser (E85 uses 1-micron filter)
Best Treatment
keep water out from entering underground tanks
early detection (microbial growth detection kits)

11. If Microbe Untreated
Water/ethanol phase provides an environment for microbial growth
Bacteria generates low molecular weight acids
Acids corrode may some underground tanks
The rate of corrosion would accelerate in the present of ethanol. (Ethanol is much more electrical conductive than gasoline and would create an electromagnetic reaction)
COSTLY: to replace underground tanks