Transcript Sediment in Ethanol Blended Gasoline

Sediment in Ethanol Blended Gasoline
(Impact on underground storage tank)
August 25, 2016
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
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”
What is the SEDIMENT?
Colonies
A milky layer of
colonies
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 (?).
Acetobacter bacteria spores
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)
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