Modeling Transport of Multiple Organic Compounds: Segregated Transport‐Sorption/Solubilization Numerical Technique

The transport of multiple organic contaminants in the subsurface may be affected by their mutual interactions. Conventional modeling approaches cannot simulate the transport of multiple organic species whose sorption and/or solubilization is interdependent. This paper describes a numerical modeling approach for characterizing interactive solute sorption and solubilization reactions coupled with one‐dimensional advective‐dispersive transport in porous media. This numerical approach, referred to as segregated transport‐sorption/solubilization (STSS), allows for interphase mass transfer at each time step after solute advection and dispersion have occurred. The overall capabilities of the STSS technique include modeling equilibrium or nonequilibrium transport of individual and multiple solutes with linear or nonlinear sorption isotherms. Application of this modeling approach is illustrated for the transport of a conservative tracer, a surfactant, a hydrophobic organic compound (HOC), and a polychlorinated biphenyl (PCB) mixture. The coupling of sorption modules for phenanthrene and surfactant is used to reasonably describe surfactant‐enhanced flushing of sorbed phenanthrene from a sand column.