Humate-Induced Remediation of Petroleum Contaminated Surface Soils
EPA Grant Number: R827015-01-0
Title: Humate-Induced Remediation of Petroleum Contaminated Surface Soils
Investigators: Mark A. Nanny, R. Paul Philp, Vladimir E. Andrusevich
Institutions: University of Oklahoma
EPA Project Officer: Bala Krishnan
Project Period: June 1, 2000 to June 30, 2001
Project Amount: $102,228
Research Category: Bioremediation of oil spills
Description:
Objective(s) of the Research Project:
To determine: 1) if
humate-induced remediation is a viable and feasible remediation
technique, and 2) if it is, determine the primary remediation
mechanism, i.e., stimulation of biodegradation, adsorption, or a
combination of both. These objectives will be accomplished by:
1) identifying the humate, or humates, with the greatest sorption
capacity, and 2) identifying and characterizing the predominant
mechanism(s) of the humate-induced remediation process(es) using
microcosms containing either pristine or contaminated surface
soil collected from a petroleum drilling field near Oklahoma
City, OK.
Progress Summary/Accomplishments:
Microcosm results (n-C17/pristine and n-C18/phytane ratios)
indicate that by day 68, biodegradation is occurring in
microcosms containing field-contaminated soil, but not in the
pristine soil + fresh petroleum microcosms. Moreover, humate #2
appears to mildly accelerate petroleum biodegradation in the
field-contaminated soil microcosms. The reason postulated for
this observation is that the field-contaminated soil contains
microflora capable of degrading petroleum, while the pristine
soil does not.
Rock Evaluation Analysis of microcosm residues (soil + humate
material remaining after CH2Cl2:CH3OH extraction) (days 2, 38,
and 68) shows that humate # 2, in the presence of
field-contaminated soil, is adsorbing petroleum. This is in
contrast to the pristine soil + fresh petroleum microcosms where
no petroleum adsorption by humate is occurring. Pyrolysis GC/MS
results show increasing incorporation of low-end aliphatics from
petroleum into these residues over the 68 day period.
The petroleum adsorption capacity of humate #2 was quantified
using Rock Evaluation Analysis to examine the residues of
freeze-dried humate #2 samples exposed to varying amounts of
fresh petroleum for 24 hours prior to CH2Cl2:CH3OH extraction.
Results demonstrated that humate #2 retains 0.27 g petroleum/gram
of humate #2. Of the original petroleum that was exposed to
humate #2, 81% of its original components remain adsorbed to
humate #2. Also discovered was that humate "as is" (i.e. not
freeze-dried), did not display this strong adsorption. These and
the above microcosm results suggest that petroleum adsorption by
"as is" humate is a kinetically slower process compared to
freeze-dried humates, presumably due to the fact that water
molecules must be displaced from the humate surface before
petroleum components can be adsorbed.
Publications/Presentations:
None to date, however a patient disclosure is being filed on the
use of humates for remediation of petroleum-contaminated surface
soils, with the assistance of University of Oklahoma's Office of
Technology Development.
Future Activities:
- Continue gas chromatographic analysis of microcosm extracts for
identification of biodegradation and/or adsorption processes, as
well as continue Rock Evaluation Analysis and Pyrolysis-GC/MS
analysis of microcosm residues after solvent extraction.
- Analyze microcosm extracts to determine extent of adsorption of
petroleum aromatic compounds by humate.
- Independently measure petroleum adsorption by humate #2 using
gravimetric experiments, and compare with Rock Evaluation
Analysis results.
- 13C-NMR and pyrolysis-GC/MS characterization of humate #2 and
#5.
- Start preliminary microcosm experiments with humates #2 and #5
to test: 1) the ability of humate #5 to adsorb/enhance
biodegradation of petroleum, and 2) the influence of moisture on
humate performance.
Supplemental Keywords: Adsorption, biodegradation