A numerical model (MISER) for the simulation of coupled physical, chemicaland biological processes in soil vapor extraction and bioventing systems

The efficiency and effectiveness of soil vapor extraction (SVE) and biovent ing (BV) systems for remediation of unsaturated zone soils is controlled by a complex combination of physical, chemical and biological factors. The Mi chigan soil vapor extraction remediation (MISER) model, a two-dimensional n umerical simulator, is developed to advance our ability to investigate the performance of field scale SVE and BV systems by integrating processes of m ultiphase flow, multicomponent compositional transport with nonequilibrium interphase mass transfer, and aerobic biodegradation. Subsequent to the mod el presentation, example simulations of single well SVE and BV systems are used to illustrate the interplay between physical, chemical and biological processes and their potential influence on remediation efficiency and the p athways of contaminant removal. Simulations of SVE reveal that removal effi ciency is controlled primarily by the ability to engineer gas flow through regions of organic liquid contaminated soil and by interphase mass transfer limitations. Biodegradation is found to play a minor role in mass removal for the examined SVE scenarios. Simulations of BV systems suggest that the effective supply of oxygen may not be the sole criterion for efficient BV p erformance. The efficiency and contaminant removal pathways in these system s can be significantly influenced by interdependent dynamics involving biol ogical growth factors, interphase mass transfer rates, and air injection ra tes. Simulation results emphasize the need for the continued refinement and validation of predictive interphase mass transfer models applicable under a variety of conditions and for the continued elucidation and quantificatio n of microbial processes under unsaturated field conditions. Published by E lsevier Science B.V.