Remediation Technologies - Environmental Investigation and Remediation - page 353

injection interval was best situated not more than 10 ft below the target interval for maximum
removal. Reductions as high as 88% were achieved in some of the monitoring wells (Table 7.3), and
all the target contaminant concentrations decreased during the pilot test period. However, none of
the concentrations were reduced to the detection limits during the i eld pilot test. The recommenda-
tion of this study was for the design and implementation of a full-scale system with more intense
oxidation in the source zone and lesser efforts in the dissolved portion of the plume. The project is
ongoing at the time of publication.
Kerfoot and Brolowski (2006) and Kerfoot (2008) described bench- and i eld-scale pilot-testing
for 1,4-dioxane oxidation using ozone alone and ozone with hydrogen peroxide. Ozone reactivity
exhibited a 1,4-dioxane removal rate of 0.15% per minute and total removal rates of 69-78% in
soil slurries contaminated with 1,4-dioxane and chloroethene. Overall, the reaction rates were
computed to be in the range of values previously dei ned for TCE and perchloroethylene, indicat-
ing that ISCO application of this technology could be as effective for 1,4-dioxane removal as for
TCE and perchloroethylene removal. A i eld application was performed with the Perozone ®
system (Kerfoot Technologies, Inc., Mashpee, MA), which uses hydrogen peroxide-coated ozone
microbubbles ( m) delivered with a proprietary sparging system, referred to as the C-Sparger ®

(Kerfoot Technologies, Inc., Mashpee, MA) (Kessel et al., 2005). The two-month-long study eval-
uated the technology application in a barrier coni guration designed to protect an open-water
channel affected by groundwater discharges. Preliminary results indicated decreases in 1,4-dioxane
c onc ent r a t ion s w it h i n t h e ~2 5 -fe et r a d iu s of i n l uence of the injection wells. Kerfoot and Brolowski
(2006) noted that the removal rates depended upon contaminant concentrations and competitive
destruction, because of the presence of other organic contaminants. Later bench-scale testing
of nanoscale (250 nm) ozone sparge bubbles, produced by a miniature Laminar Spargepoint ®
(Kerfoot Technologies, Inc., Mashpee, MA), indicated equivalent effectiveness between ozone
alone and ozone plus hydrogen peroxide. The nanobubbles exhibited a greater resistance to col-
lapse and a longer half-life (more than 20 h) than microbubbles (Kerfoot, 2008). This technology
was applied as a full-scale remedy for the site, but results were not available at the time of
publication.
A i eld pilot study performed by Pall Corporation (2004) involved injecting hydrogen peroxide
alone (to be combined with naturally occurring ferrous iron as a Fenton's reagent reaction), ozone
alone, and ozone plus hydrogen peroxide. Results indicated that all three methods were effective
to varying degrees. Ozone injection caused signii cant decreases in 1,4-dioxane concentrations,
but also caused the formation of bromate above the maximum contaminant level of 10 ppb. The

< 50 μ

TABLE 7.3
ISCO Field Pilot Study Results

Initial
Concentration
in July 2005
(

Concentration
in June 2006
(

Change Since
Start of Pilot
Study (%)

Concentration
in August 2006
(

Change Since
Start of Pilot
Study (%)

Well COC μ g/L) μ g/L) μ g/L)

EW-1 (63 ft) TCE 660 65 -90 120 -82

EW-1 (63 ft) 1,4-Dioxane 750 47 -94 250 -67

MW-33A TCE 940 180 -81 130 -86

MW-33A 1,4-Dioxane 630 99 -84 74 -88

MW-20 TCE 520 110 -79 140 -73

MW-20 1,4-Dioxane 140 79 -44 71 -49

Source: Sadeghi, V.M. and Gruber, D.J., 2007, In situ oxidation of 1,4-dioxane with ozone and hydrogen peroxide. Poster
presentation at URS's Environmental Technology and Management Seminar, Oakland, CA.