Radon-222 gas has unique properties allowing it to be used as an indicator for the
presence of organic phase liquids in the saturated zone. It naturally occurs in soils. It is
radioactive, making quantitative detection straight forward. A noble gas, it is chemically
inert and does not react with aquifer...
Continuous-flow and batch experiments were conducted with a column reactor
system containing Hanford aquifer material in order to evaluate the potential of in-situ
bioremediation of carbon tetrachloride (CT) at Hanford. The effectiveness of benzoate
and acetate as primary substrates was considered. Nitrate and sulfate were potential
electron acceptors. Transport experiments...
A mix-culture of methanogenic and sulfate-reducing bacteria was capable of degrading trichloroethylene (TCE) to dichloroethylene (DCE). The culture was incubated under anaerobic conditions within a soil sample taken from Gilbert-Mosley site, Wichita, Kansas. To stimulate the growth of indigenous bacteria, a carbon and energy source was added in this microcosm...
Persistence of Non aqueous phase liquids (NAPLs) in the subsurface at residual
saturations eventually contributes to undesirable groundwater contamination. Proper
characterization of subsurface NAPL, its location, composition and distribution, is
essential for the chosen remediation technology to be effective. It is also desirable to
assess the performance of remedial actions...
Batch microcosm studies were carried out to screen for microorganisms from the
subsurface of Hanford DOE site that could cometabolically transform chloroform (CF)
under aerobic conditions. The potential need for CF bioremediation at the Hanford site
has resulted from the large release of carbon tetrachloride (CT) to the subsurface, of...
At Site-300, Lawrence Livermore National Laboratory (LLNL), CA,
trichloroethene (TCE) is present along with tetraalkoxysilanes such as tetrabutoxysilane
(TBOS) and tetrakis(2-ethylbutoxy) silane (TKEBS), as subsurface contaminants.
Intrinsic transformation of TCE to cis-dichloroethene (c-DCE) was observed in the
groundwater at locations co-contaminated with TBOS or TKEBS. Attenuation of TBOS
and TKEBS...
Laboratory scale microcosm studies were conducted using site specific groundwater and aquifer solids to assess the feasibility of stimulating indigenous microorganisms in-situ to biologically transform Trichloroethylene (TCE) and its lesser chlorinated daughter products dichloroethylene (DCE) and vinyl chloride (VC). Three different treatments were conducted to determine the best approach for...
This microcosm study demonstrated the enhanced anaerobic transformation of vinyl chloride (VC) to ethylene. A previous microcosm study from Point Mugu site showed the accumulation of VC due to the slow transformation step of VC to ethylene. To overcome the rate-limiting step, two laboratory experiments tested the effect of trichloroethylene...
This research focuses on the anaerobic transformation of trichloroethylene (TCE) that is occurring in the subsurface of the Evanite site in Corvallis, OR. Two anaerobic studies were conducted to investigate the effects of microbial communities in the presence of different electron donors during the anaerobic degradation of trichlorofluoroethylene (TCFE), and...
A method is described for determining the partition coefficient, K, for radon gas
distributed between an aqueous phase and an organic solvent. The method uses
sequential extractions of radon into equal volume aliquots of organic solvent. The
radon-laden organic liquid is then counted on a liquid scintillation analyzer with alpha-beta...
The 1,1-dichloroethene (1,1-DCE) cometabolic transformation abilities of indigenous and bioaugmented microorganisms were compared in microcosms constructed with groundwater and aquifer solids from the Moffett Field site, CA. Microbial community structure in the microcosms and possible community shifts due to 1,1-DCE transformation stress was evaluated by terminal restriction fragment length polymorphism...
This study investigated the use of radon-222 as an in situ partitioning tracer for quantifying nonaqueous phase liquid (NAPL) saturations in the subsurface. Laboratory physical aquifer models (PAMs), field experiments, and numerical simulations were used to investigate radon partitioning in static (no-flow) experiments and in single-well, 'push-pull' tests conducted in...
The goal of this research was to mathematically simulate the ability of bioaugmented microorganisms to aerobically cometabolize a mixture of chlorinated aliphatic hydrocarbon (CAH) compounds during in-situ treatment. Parameter values measured from laboratory experiments were applied to the transport model with biotransformation processes included. In laboratory microcosm studies, a butane-grown,...
Laboratory and modeling studies were performed with a mixed-anaerobic-culture obtained from the Evanite site in Corvallis, Oregon. The culture completely transforms trichloroethene (TCE) to cis-dichloroethene (c-DCE), vinyl chloride (VC), and finally to ethene. Acetylene inhibition studies were used to examine the culture's microbial activities. Kinetic studies determined the half-saturated constant...
The aerobic transformation of TCE and cis-DCE by a tetrabutoxysilane-grown microorganism (Vancheeswaran et al., 1999) led to the investigation of novel substrates, including benzyl alcohol, for promoting cometabolism. The culture grew on carboxylic compounds and alcohols, but did not grow on formate, methanol, methane, propane, butane, ethylene, benzene, toluene, or...