TY - JOUR
T1 - Evaluation of a horizontal permeable reactive barrier for preventing upward diffusion of volatile organic compounds through the unsaturated zone
AU - Mahmoodlu, Mojtaba G.
AU - Hassanizadeh, S. Majid
AU - Hartog, Niels
AU - Raoof, Amir
AU - van Genuchten, Martinus Th
PY - 2015/11/1
Y1 - 2015/11/1
N2 - Permeable reactive barriers are commonly used to treat contaminant plumes in the saturated zone. However, no known applications of horizontal permeable reactive barriers (HPRBs) exist for oxidizing volatile organic compounds (VOCs) in the unsaturated zone. In this study, laboratory column experiments were carried out to investigate the ability of a HPRB containing solid potassium permanganate, to oxidize the vapors of trichloroethylene (TCE), toluene, and ethanol migrating upward from a contaminated saturated zone. Results revealed that an increase in initial water saturation and HPRB thickness strongly affected the removal efficiency of the HPRB. Installing the HPRB relatively close to the water table was more effective due to the high background water content and enhanced diffusion of protons and/or hydroxides away from the HPRB. Inserting the HPRB far above the water table caused rapid changes in pH within the HPRB, leading to lower oxidation rates. The pH effects were included in a reactive transport model, which successfully simulated the TCE and toluene experimental observations. Simulations for ethanol were not affected by pH due to condensation of water during ethanol oxidation, which caused some dilution in the HRPB.
AB - Permeable reactive barriers are commonly used to treat contaminant plumes in the saturated zone. However, no known applications of horizontal permeable reactive barriers (HPRBs) exist for oxidizing volatile organic compounds (VOCs) in the unsaturated zone. In this study, laboratory column experiments were carried out to investigate the ability of a HPRB containing solid potassium permanganate, to oxidize the vapors of trichloroethylene (TCE), toluene, and ethanol migrating upward from a contaminated saturated zone. Results revealed that an increase in initial water saturation and HPRB thickness strongly affected the removal efficiency of the HPRB. Installing the HPRB relatively close to the water table was more effective due to the high background water content and enhanced diffusion of protons and/or hydroxides away from the HPRB. Inserting the HPRB far above the water table caused rapid changes in pH within the HPRB, leading to lower oxidation rates. The pH effects were included in a reactive transport model, which successfully simulated the TCE and toluene experimental observations. Simulations for ethanol were not affected by pH due to condensation of water during ethanol oxidation, which caused some dilution in the HRPB.
KW - Diffusion
KW - Horizontal permeable reactive barrier
KW - Potassium permanganate
KW - Unsaturated zone
KW - VOC vapors
UR - http://www.scopus.com/inward/record.url?scp=84940107656&partnerID=8YFLogxK
U2 - 10.1016/j.jenvman.2015.08.025
DO - 10.1016/j.jenvman.2015.08.025
M3 - Article
AN - SCOPUS:84940107656
SN - 0301-4797
VL - 163
SP - 204
EP - 213
JO - Journal of Environmental Management
JF - Journal of Environmental Management
M1 - 4989
ER -