Evaluation of Biostimulation and Bioaugmentation To Stimulate Hexahydro-1,3,5-trinitro-1,3,5,-triazine Degradation in an Aerobic Groundwater Aquifer.
Hexahydro-1,3,5-trinitro-1,3,5,-triazine (RDX) is a toxic and mobile groundwater contaminant common to military sites. This study compared in situ RDX degradation rates following bioaugmentation with Gordonia sp. strain KTR9 (henceforth KTR9) to rates under biostimulation conditions in an RDX-contaminated aquifer in Umatilla, OR. Bioaugmentation was achieved by injecting site groundwater (6000 L) amended with KTR9 cells (10(8) cells mL(-1)) and low carbon substrate concentrations (<1 mM fructose) into site wells. Biostimulation (no added cells) was performed by injecting groundwater amended with low (<1 mM fructose) or high (>15 mM fructose) carbon substrate concentrations in an effort to stimulate aerobic or anaerobic microbial activity, respectively. Single-well push-pull tests were conducted to measure RDX degradation rates for each treatment. Average rate coefficients were 1.2 day(-1) for bioaugmentation and 0.7 day(-1) for high carbon biostimulation; rate coefficients for low carbon biostimulation were not significantly different from zero (p values ≥0.060). Our results suggest that bioaugmentation with KTR9 is a feasible strategy for in situ biodegradation of RDX and, at this site, is capable of achieving RDX concentration reductions comparable to those obtained by high carbon biostimulation while requiring ~97% less fructose. Bioaugmentation has potential to minimize substrate quantities and associated costs, as well as secondary groundwater quality impacts associated with anaerobic biostimulation processes (e.g., hydrogen sulfide, methane production) during full-scale RDX remediation.
Environmental Laboratory, U.S. Army Engineer Research and Development Center , Vicksburg, Mississippi 39180, United States.
Mandy M
MM
Michalsen
Seattle District, U.S. Army Corps of Engineers , Seattle, Washington 98134, United States.
Aaron S
AS
King
Seattle District, U.S. Army Corps of Engineers , Seattle, Washington 98134, United States.
Rebecca A
RA
Rule
CB&I Federal Services, 17 Princess Road, Lawrenceville, New Jersey 08648, United States.
Mark E
ME
Fuller
CB&I Federal Services, 17 Princess Road, Lawrenceville, New Jersey 08648, United States.
Paul B
PB
Hatzinger
CB&I Federal Services, 17 Princess Road, Lawrenceville, New Jersey 08648, United States.
Charles W
CW
Condee
Environmental Laboratory, U.S. Army Engineer Research and Development Center , Vicksburg, Mississippi 39180, United States.
Fiona H
FH
Crocker
Environmental Laboratory, U.S. Army Engineer Research and Development Center , Vicksburg, Mississippi 39180, United States.
Karl J
KJ
Indest
Environmental Laboratory, U.S. Army Engineer Research and Development Center , Vicksburg, Mississippi 39180, United States.
Carina M
CM
Jung
School of Civil and Construction Engineering, Oregon State University , Corvallis, Oregon 97331, United States.
Jack D
JD
Istok
D001673:Biodegradation, Environmental; D060587:Groundwater; D014227:Triazines / Q000378:metabolism*
D014227:Triazines