Analytical Analysis of VOC Remediation by Horizontal Permeable Reactive Barriers for Time-Dependent Source

Various natural and man-made objects, like industrial waste buried beneath soil emit many harmful gases known as Volatile Organic Compounds (VOCs) are hazardous for living beings. If released in environment VOCs can contaminate air, soil, and groundwater, causing health risks like dizziness, organ damage, and cancer. Their migration through unsaturated soil occurs via diffusion, advection and dispersion. Horizontal Permeable Reactive Barriers (HPRBs) are an effective in situ method to remediate and oxidize VOCs in the vadose zone. The degradation of an HPRB due to long-term interaction with VOCs occurs over several years; therefore, mathematical modeling is an effective and necessary tool for predicting its long-term behavior, as conducting experiments over such extended timescales in real life is impractical. In this study, an analytical diffusion-reaction model is presented to investigate VOC transport from a subsurface source, through the unsaturated soil layer, and into a HPRB. The model accounts for time-dependent conditions and the transport process is analyzed separately under the effects of various parameters involved. The obtained simulation through graph shows good agreement with the behavior observed in experiment. This study provides insight into the long-term performance and durability of the HPRB, which will help in barrier design and lifetime assessment.