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Volume 2
Journal of Environmental Research
Page 21
JOINT EVENT
July 26-27, 2018 Rome, Italy
&
6
th
Edition of International Conference on
Water Pollution & Sewage Management
4
th
International Conference on
Pollution Control & Sustainable Environment
Mansor Kashir et al., J Environ Res 2018, Volume: 2
The effectiveness of chemical oxidation in remediating hot and saline groundwater impacted with
hydrocarbons
Mansor Kashir
1
and
Rick McGregor
2
1
Saudi Aramco, Saudi Arabia
2
InSitu Remediation Services Ltd., Canada
A
series of laboratory microcosm experiments and a field-pilot test was performed to evaluate the potential for the
in
situ
chemical oxidation of aromatic hydrocarbons and methyl tertiary butyl ether (MTBE), in saline, high temperature
(greater than 30) groundwater. Groundwater samples from a site in Saudi Arabia were amended in the laboratory portion
of the study with the chemical oxidants persulfate, percarbonate and stabilized hydrogen peroxide to evaluate the changes
in select hydrocarbons and MTBE concentrations with time. Almost complete degradation of the aromatic hydrocarbons,
naphthalene and trimethylbenzene was found in the groundwater samples amended with persulfate and stabilized hydrogen
peroxide whereas the percarbonate-amended samples showed little to no degradation of the target hydrocarbon compounds
in the laboratory. Isotopic analyses of the persulfate-amended samples suggested that C-isotope fractionation for xylenes
occurred after approximately 30% reduction in concentration with a decline in the δ13C values of xylenes of about 1%. Based
on the laboratory results, pilot-scale testing at a Saudi Arabian field site was carried out to verify the persulfate laboratory
results. Results obtained from the pilot test indicated that all the target compounds decreased substantially with time. pH of
the groundwater remained neutral following injections whereas oxidation-reduction potential remained anaerobic throughout
the injection zone with time. Nitrate concentrations decreased within the injection zone suggesting that the nitrate may be
consumed by denitrification reactions while sulfate concentrations increased as expected within the reactive zone suggesting
that the persulfate was being reduced to sulfate. Overall, the injection of the oxidant persulfate was shown to be an effective
approach to treating dissolved aromatic and associated hydrocarbons within the groundwater. The generation of sulfate as a
byproduct was an added benefit as the sulfate could be utilized by sulfate-reducing bacteria (SRBs) presents within the subsurface
to further biodegrade any remaining hydrocarbons. The results of the pilot-study using stabilized hydrogen peroxide as an
oxidant suggested that the hydrogen peroxide was not stabilized by citric acid but instead the citric acid enhanced the oxidation
of the target compounds including the oxidation of BTEX and MTBE. It appears that the citric acid may be chelating natural
metal activators, such as ferric iron, and enhancing their activation function. Analysis of the BTEX compounds indicated
a degradation percent of greater than 99% over the course of the study whereas MTBE was degraded by greater than 50%.
Analysis of the TBA prior to and post injection suggested that TBA was not generated and in most cases TBA was degraded
by greater than 75% during the pilot test. CSIA analysis indicated the
13
C within the MTBE and benzene was enriched during
the oxidation process. Bacterial analysis showed a dramatic change in the bacteria community makeup with aerobic bacteria
responding quickly to the addition of stabilized hydrogen peroxide.
Recent Publications
1. Mansor Kashir, et al. (2015) Chemical oxidation of high saline, high temperature groundwater impacted by
hydrocarbons. Remediation Journal USA 25(2):55–70.
2. Mansour Kashir, et al. (2014) Aerobic biodegradation of hydrocarbons in high temperatures and saline groundwater.
Remediation Journal USA 24(2):77–90.
3. Mansor Kashir, et al. (2009) A kinetic model for the remediation of hydrocarbon impacted soils using low temperature
oxidation. Journal of ASCE Practice Periodical for Hazardous Toxic and Radioactive Waste Management 11(4):259-
267.
4. Mansor Kashir, et al. (2007) A numerical model simulating the remediation of hydrocarbon impacted soils using low
temperature oxidation. Journal of Environmental Modeling and Assessment 13(2):265-274.
5. Mansor Kashir and Yanful E (2001) Hydraulic conductivity of bentonite permeated with acid mine drainage. Canadian
Geotechnical Journal Canada 38(5):1034-1048.