Activated persulfate oxidation as a first step in a treatment train In-situ chemical oxidation ha... more Activated persulfate oxidation as a first step in a treatment train In-situ chemical oxidation has been applied in several cases for the remediation of contaminated sites. Activated persulfate is an innovative oxidant that constitutes an alternative to the most commonly used oxidants such as permanganate, ozone and Fenton’s reagent. In this work, we investigated the efficiency of activated persulfate oxidation against MTBE, Trichloroethylene (TCE) and 1,1,1-Trichloroethane (TCA) in both aqueous and soil-water systems using heat and ferrous ion as activators. Heat-activated persulfate oxidation at 40oC was the most effective method and achieved 98.6% removal of MTBE, and 89.9% of TCE in the soil-water systems within 24 hours. Considerable TCA removal was only observed in the aqueous systems. Iron-activated persulfate was very effective in the first hours but its efficiency was thereafter limited. Further experiments with MTBE and the use of complexing agents for improving/controlling iron availability did not increase the efficiency. In conclusion, the use of heat-activated persulfate seems most promising, and in addition, the increased aquifer temperatures may be beneficial to subsequent microbial degradation processes.
Critical Reviews in Environmental Science and Technology, Jan 4, 2010
... AIKATERINI TSITONAKI,1 BENJAMIN PETRI,2 MICHELLE CRIMI,3 HANS MOSBÆK,1 ROBERT L. SIEGRIST,2 a... more ... AIKATERINI TSITONAKI,1 BENJAMIN PETRI,2 MICHELLE CRIMI,3 HANS MOSBÆK,1 ROBERT L. SIEGRIST,2 and ... Lyngby, Denmark 2Environmental Science and Engineering Division, Colorado School of Mines, Golden, Colorado, USA 3Environmental Health ... A mbient ...
Mapping high permeability sand occurrences in clayey till is fundamental for protecting the under... more Mapping high permeability sand occurrences in clayey till is fundamental for protecting the underlying drinking water resources. Crosshole ground penetrating radar (GPR) amplitude data have the potential to differentiate between sand and clay, and can provide 2D subsurface models with a decimeter‐scale resolution. We develop a probabilistic straight‐ray‐based inversion scheme, where we account for the forward modeling error arising from choosing a straight‐ray forward solver. The forward modeling error is described by a Gaussian probability distribution and included in the total noise model by addition of covariance models. Due to the linear formulation, we are able to decouple the inversion of traveltime and amplitude data and obtain results fast. We evaluate the approach through a synthetic study, where synthetic traveltime and amplitude data are inverted to obtain slowness and attenuation tomograms using several noise model scenarios. We find that accounting for the forward modeling error is fundamental to successfully obtain tomograms without artifacts. This is especially the case for inversion of amplitude data since the structure of the noise model for the forward modeling error is significantly different from the other data error models. Overall, inversion of field data confirms the results from the synthetic study; however, amplitude inversion performs slightly better than traveltime inversion. We are able to characterize a 0.4–0.6 m thick sand layer as well as internal variations in the clayey till matching observed geological information from borehole logs and excavation.
Activated persulfate oxidation as a first step in a treatment train In-situ chemical oxidation ha... more Activated persulfate oxidation as a first step in a treatment train In-situ chemical oxidation has been applied in several cases for the remediation of contaminated sites. Activated persulfate is an innovative oxidant that constitutes an alternative to the most commonly used oxidants such as permanganate, ozone and Fenton’s reagent. In this work, we investigated the efficiency of activated persulfate oxidation against MTBE, Trichloroethylene (TCE) and 1,1,1-Trichloroethane (TCA) in both aqueous and soil-water systems using heat and ferrous ion as activators. Heat-activated persulfate oxidation at 40oC was the most effective method and achieved 98.6% removal of MTBE, and 89.9% of TCE in the soil-water systems within 24 hours. Considerable TCA removal was only observed in the aqueous systems. Iron-activated persulfate was very effective in the first hours but its efficiency was thereafter limited. Further experiments with MTBE and the use of complexing agents for improving/controlling iron availability did not increase the efficiency. In conclusion, the use of heat-activated persulfate seems most promising, and in addition, the increased aquifer temperatures may be beneficial to subsequent microbial degradation processes.
Critical Reviews in Environmental Science and Technology, Jan 4, 2010
... AIKATERINI TSITONAKI,1 BENJAMIN PETRI,2 MICHELLE CRIMI,3 HANS MOSBÆK,1 ROBERT L. SIEGRIST,2 a... more ... AIKATERINI TSITONAKI,1 BENJAMIN PETRI,2 MICHELLE CRIMI,3 HANS MOSBÆK,1 ROBERT L. SIEGRIST,2 and ... Lyngby, Denmark 2Environmental Science and Engineering Division, Colorado School of Mines, Golden, Colorado, USA 3Environmental Health ... A mbient ...
Mapping high permeability sand occurrences in clayey till is fundamental for protecting the under... more Mapping high permeability sand occurrences in clayey till is fundamental for protecting the underlying drinking water resources. Crosshole ground penetrating radar (GPR) amplitude data have the potential to differentiate between sand and clay, and can provide 2D subsurface models with a decimeter‐scale resolution. We develop a probabilistic straight‐ray‐based inversion scheme, where we account for the forward modeling error arising from choosing a straight‐ray forward solver. The forward modeling error is described by a Gaussian probability distribution and included in the total noise model by addition of covariance models. Due to the linear formulation, we are able to decouple the inversion of traveltime and amplitude data and obtain results fast. We evaluate the approach through a synthetic study, where synthetic traveltime and amplitude data are inverted to obtain slowness and attenuation tomograms using several noise model scenarios. We find that accounting for the forward modeling error is fundamental to successfully obtain tomograms without artifacts. This is especially the case for inversion of amplitude data since the structure of the noise model for the forward modeling error is significantly different from the other data error models. Overall, inversion of field data confirms the results from the synthetic study; however, amplitude inversion performs slightly better than traveltime inversion. We are able to characterize a 0.4–0.6 m thick sand layer as well as internal variations in the clayey till matching observed geological information from borehole logs and excavation.
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Papers by Aikaterini Tsitonaki