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