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1
<br />' where
<br /> GWODO,,= GW oxidant demand in mg 03 consumed/L GW
<br /> [03 Consumed],o„tro, = change in 03 concentration in the absence of GW in mg/L
<br />! [03 Consumed]rw = change in 03 concentration in the presence of GW in mg/L
<br /> Vtot=total volume of solution (ozonated water+ GW) in L
<br />' VoW = volume of GW in L
<br />' 2.3 Confirmation of Contaminant Removal
<br /> To confirm that COCs were removed and estimate the amount of removal due to
<br />' destruction versus volatilization, soil and GW were sparge with either nitrogen gas or
<br /> ozone Three reactors containing 2L of GW and 200 g soil were prepared The reactors
<br /> were capped and the contents mixed via magnetic stirrers After 20 minutes, aqueous
<br />' samples were collected and analyzed for TPH-g, BTEX, MTBE, TBA, acetone, and
<br /> metals (Al, Sb, As, Ba, Be, Cd, Cr, Co, Cu, Fe, Pb, Mn, Hg, Mo, Ni, Se, Ag, T1, W, V,
<br /> and Zn) These concentrations were taken to be "Time 0" Two of the reactors were then
<br /> fitted with a gas dispersion tube for sparging and a vent for off-gases One reactor was
<br /> sparged with---1 2% w/w (15 g/m3) ozone in air, the other with nitrogen The reactors
<br /> were sparged for 6 25 hours at a flowrate of 500 mL/min The third reactor served as a
<br /> Control and was not sparged Aqueous samples were collected at 2 25 hours, and 4 25
<br /> 10 hours and analyzed for acetone At the end of the test(6 25 hours), aqueous samples
<br /> were analyzed for all COCs Off-gases from the nitrogen and ozone sparged reactors
<br />' were collected in Tedlar bags for 0-30 minutes and 30-60 minutes and analyzed for
<br /> COCl (Note that it is not possible to collect all of the off-gases due to the large volume
<br /> expected ) Soil was not analyzed
<br /> 2.4 Effect of Ozonation on Secondary Water Quality parameters
<br /> Post-treatment water samples from Section 2 3 were collected and analyzed for alkalinity,
<br /> anions (chloride, nitrate, sulfate), cations (Na, K, Mg, Ca) conductivity, hexavalent
<br /> chromium, metals (Al, Sb, As, Ba, Be, Cd, Cr, Co, Cu, Fe, Pb, Mn, Hg, Mo, Ni, Se, Ag,
<br /> Tl, W, V, and Zn), oxidation reduction potential (ORP), pH, and total dissolved solids
<br /> (TDS) Untreated soil was also analyzed for metals
<br /> 2.5 Natural Attenuation of Cr(VI)
<br /> Two tests were performed to assess whether Cr(VI) generated during ozonation could
<br />` potentially naturally attenuate The first was measurement of the available reducing
<br /> capacity of soil as described by Bartlett (Bartlett, R J 1991 "Chromium Cycling in Soils
<br /> and Water Links, Gaps and Methods," Environmental Health Perspectives, 92, 17-24),
<br /> the second was a similar test using treated site groundwater and untreated site soil
<br /> i
<br /> PRIMA Environmental 4 Eva[of Ozone
<br /> January 27, 2005 ENSR-Unocal 5098
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