Mass Transport in Porous Media with and Without Chemical Reactions

Abstract

In this chapter the computation of multispecies (including single-species) mass transport in porous media with chemical reaction in particular is examined. The complexity of those reactive transport processes arising in natural and engineered porous media requires some specific treatment due to their nonlinearity and the occurrence of multiple unknowns. In the preceding Chap. 5 the constitutive relations in form of reversible reaction and irreversible chemical kinetics have been developed. It ends up with a set of mass transport equations for each chemical species k = 1, …, N of an arbitrary number, nonlinearly coupled by the rate expressions of chemical reaction in form of degradation type, Arrhenius type, Monod type or freely editable kinetics. A given species k can be either mobile associated with a liquid (aqueous) phase l or immobile associated with a solid phase s, so that N = N l + N s . Chemicals in the liquid phase are subject to advection and dispersion, while in a solid phase there is no advection and dispersion. We solve the reactive multispecies mass transport processes in multi-dimensional porous media under variably saturated, variable-density and nonisothermal conditions. The focus of this chapter is on the treatment of the species mass transport PDE system, while for the flow computations we refer to Chap. 9 for saturated porous media, to Chap. 10 for variably saturated porous media and to Chap. 11 for density-coupled problems. Nonisothermal aspects are subject of Chaps. 11 and 13.