New Organic and Tracer Components Sample Clauses

New Organic and Tracer Components. New organic and tracer components were added to UTCHEM. We have added multiple organic components so that we can model NAPL mixtures. Adding this capability to UTCHEM required developing a phase- behavior model for NAPL mixtures and the physical property models such as density and viscosity for each phase. We have also added additional water tracer components and gas phase tracers. New organic components Nonaqueous phase liquids (NAPLs) usually consist of more than one organic species that mix and form a single liquid. Common examples of such miscible species include TCE, TCA and PCE among many others. When NAPLs leak to the subsurface, they can dissolve and migrate into groundwater. To model the fate and transport of these soluble organics during remediation processes such as pump-and-treat, bioremediation and surfactant remediation, it is important to determine the migration of the individual soluble organics. The dissolution can be either a local equilibrium or a rate-limited (nonequilibrium) mass-transfer process. We have added the capability of multiple organic components to UTCHEM to model these NAPL mixtures. The multiple organic dissolution can be either local-equilibrium partitioning or a rate-limited mass transfer. We also developed and incorporated in UTCHEM a phase-behavior model for a mixture of NAPL mixtures, surfactant, and water. The physical-property models developed and implemented for a NAPL mixtures in UTCHEM were density, viscosity, and adsorption. A more detailed description of the model is given in Section 2.6 of this report. Three recent papers by Xxxxx et al. [1994a,b,c] show that the phase behavior of surfactants with both pure chlorocarbons and mixtures of chlorocarbons is similar to classical phase behavior with hydrocarbons. The phase behavior changes from microemulsion in equilibrium with excess oil (Xxxxxx Type I or Type II(-)) to microemulsion in equilibrium with excess aqueous and organic phase (Xxxxxx Type III), and to microemulsion in equilibrium with excess water (Xxxxxx Type II or Type II(+)) as salinity increases. The lower and upper limits of effective salinity are the effective salinities at which three phases form or disappear. The optimal salinity is defined as the midpoint of these two salinity limits . Hand's equation (Xxxx and Xxxxxx, 1978) is used in UTCHEM to describe the phase envelope and binodal curve. For organic mixtures, the upper and lower limits of effective salinity, the height of binodal curve at low...