I University of Nebraska  Lincoln Impact of Ethanol Releases: Long-Term Monitoring Results Roy F. Spalding Nebraska Ethanol Safety and Environmental Coalition Meeting Aurora, NE February 4, 2010

Collaborators Kansas Dept of Health & Environment Greg Hattan Minnesota Pollution Control Agency Mark Toso Tom Higgins Adam Sekely University of Nebraska-Lincoln Mary Exner, co-PI Dave Fitzpatrick, graduate student

Ethanol Properties Influencing Fate and Transport  Cosolvency  Surface tension  Specific gravity  Interfacial tension  Phase separation  Bioremediation

Vapor Pressure (mm Hg) If vapor pressure > 100 mm Hg Volatilization from free phase (NAPL) Vaporization of residual product from dry soil Law of Partial Pressure P total = P MTBE + P other constituents P MTBE = X MTBE P o MTBE P i (mm Hg) 27–28 0.8– –0.8 Gasoline Constituent MTBE Benzene Toluene Ethylbenzene Xylenes % by Volume 11% 1% 10% 2% 10% (NSTC, OSTP Report, June 1997) Arulanantham et al., 1999 Iso-octane (49)

Benzene Toluene Ethylbenzene Xylene BTEX

,000 10, ,000 Benzene Toluene Xylenes COSOLVENCY Volume Fraction of Ethanol in the Aqueous Phase Aqueous Phase Concentration (mg/L) Powers (2001)

Surface Tension Surface / Interfacial Tension (dyne/cm) Percent Ethanol in Aqueous Phase Interfacial Tension Properties Impacting Ethanol & Gasoline in Capillary Fringe Powers (2001)

Mixing Ethanol-Blended Fuels with Water (Adapted from B.P. Stafford, 2007) ethanol water gasoline 2 phase field 1 phase field E10 E95 E85

Water Table gasoline and/or ethanol water groundwater  Contaminant spreading in thin layer in collapsed capillary fringe due to decreased interfacial tension.  Predominately anaerobic microbial degradation within the capillary fringe and conversion to methane. Attenuation in the Capillary Fringe

CH 3 CH 2 OH SO 4 -2 = 2 CO H 2 O S mg SO 4 -2 /liter consumes 46 mg ethanol /liter CH 3 CH 2 OH + H 2 O → CH 3 COOH + 2 H 2 CH 3 COOH → CO 2 + CH 4 Ethanol Attenuation Mechanisms  Degradation by sulfate reduction:  Fermentation:

~10,000 Gs residual ethanol after product removal and soil excavation Balaton, Minnesota July 28, 2004 ~90,000 Gs of d-ethanol released

Balaton, Minnesota

D. Oxygen: 4.3 Years After Derailment

Methane: 2.8 Years After Derailment

Methane: 4.3 Years After Derailment

Benzene: 4.3 Years After Derailment SOURCE ZONE C 2 H 5 OH: never detected by us CH 3 CO 2 H: mg/L NO 3 -N: ND in most wells SO 4 2- : 2 – 3 mg/L Fe 2+ : >10 mg/L Mn 2+ : ND H 2 S: ND

November 22, 2006 ~24,877 Gs of d-ethanol released 12,500 Gs recovered No soil excavation Cambria, Minnesota

Methane: 0.5 Years After Derailment

Methane: 2 Years After Derailment SOURCE ZONE C 2 H 5 OH : 120 µg/L – 0.16% CH 3 CO 2 H : <3,090 mg/L C 6 H 6 : ~50 – 900 µg/L D.O.: < 2 mg/L SO 4 2- : generally < 5 mg/L Fe 2+ : > 10 mg/L H 2 S: ND

Tanker held 28,488 Gs of ethanol 28,000 Gs were released South Hutchinson, Kansas August 31, 2005

South Hutchinson, Kansas

D. Oxygen: 1 Year After Derailment

D. Oxygen: 3.5 Years After Derailment

Methane: 1 Year After Derailment

Methane: 1.3 Years After Derailment

Methane: 2 Years After Derailment

Methane: 2.8 Years After Derailment

Methane: 3.5 Years After Derailment SOURCE ZONE C 2 H 5 OH : < ,000 µg/L C 6 H 6 : 100 – 560 µg/L

Acetate: 3.5 Years After Derailment SOURCE ZONE H 2 : 3 – 50 nmoles Fe 2+ : >10 mg/L Mn 2+ : ND H 2 S: usually ND NO 3 -N: <1.5 mg/L SO 4 2- : ~45 – 100 mg/L

 Ethanol accumulates & persists in the collapsed capillary fringe (CF) and some may be released to gw after 2 years.  Buoyant ethanol (sg = 0.79 g/cc) floats above the water table.  A protective biofilm coating develops around the ethanol delaying anaerobic degradation and production of methane.  Ethanol concentrations may remain toxic to microbial attenuators within the envelope.  Methane continues to be produced years after the release. Observations of and Explanations for Ethanol’s Unconventional Behavior

Hypothesis for Ethanol’s Persistence in the Source Zone

 A controlled ethanol release test site with about 10 feet to groundwater is needed.  The site should be fully instrumented with volatile traps, gas probes, lysimeters, neutron probe tubes, down-hole camera tubes, and multilevel samplers.  The study will focus on reactions in the CF.  Concentrations of ethanol, methane & hydrogen will be measured routinely by students.  Geoprobe™ cores and biotraps will be used to monitor changes in the microbial community as indicated by chemical indicator changes.  The site will allow improved quantification of the ethanol leached to the CF and its persistence in the CF. Future Research

Acknowledgements Bruce Bauman, API John Landwehr, Pinnacle Engineering Shane Jensen, UNL Nebraska Ethanol Board

Thank You!