Water-to-Air Mass Transfer of VOCs: Laboratory-Scale Air Sparging System

Interphase mass transfer between fluids in subsurface formations: A review

“…Braida and Ong [232] developed a simple model to predict vapor phase concentrations in air sparging applications based on the air-water interfacial area determined from the number and characteristics of air channels, the diffusive mass transfer zone (MTZ) in the aqueous phase around the gas channels and a userdefined rate limited volatilization parameter. The basis of the MTZ concept had been presented earlier by Chao et al [233].…”

Remediation of saturated soil contaminated with petroleum products using air sparging with thermal enhancement

“…The following equation represents a first-order kinetic process, which models the non-equilibrium mass transfer between air and water phases (Chao et al, 1998):…”

“…Also they observed a slight increase in removal rate when benzene and toluene coexisted in the test soil compared to when they existed alone. Chao et al (1998) developed non-equilibrium water-toair mass transfer experiments for six volatile organic compounds during air sparging in soil columns packed with coarse, medium, or fine sand or glass beads. They performed a numerical study and assumed that the concentration in the bulk phase remained constant due to slow diffusion of VOCs in the aqueous phase to the air-water interface as compared to the rapid volatilization of VOCs at the air-water interface.…”

Simulation and optimization technologies for petroleum waste management and remediation process control

“…For example, Roberts and Wilson (1993) used the compartment model to describe the removal of dispersed DNAPL dropets from contaminated aquifers by AS; Wilson et al (1994b) incorporated the kinetics of NAPL solution and contaminant diffusion from low-permeability porous layers to their previous models; Gó mez-Lahoz et al (1994) investigated the diffusion-induced concentration rebound after shutdown of an AS system; Wilson et al (1994a) considered effects of air channeling to their models based on the assumption that the sparging air moved through persistent channels in the aquifer and VOC transport to the sparging air was caused by diffusion/dispersion; more recent enhancement to Wilson's models was achieved by considering the biodegradation effects (Wilson and Norris, 1997) and random features of air channels (Wilson et al, 1998). Chao et al (1998) conducted a series of air sparging column experiments to investigate the non-equilibrium air-water mass transfer of VOCs in the saturated porous media. A lumped parameter model based on a ''two-zone'' concept was developed to estimate the air-water mass transfer coefficients.…”