Presentation is loading. Please wait.

Presentation is loading. Please wait.

Mass Transport of Pollutants. Dense Non-Aqueous Phase Liquids NAPLs – – Insoluble in water and – Separate phase Dense NAPLs – – More dense than water.

Similar presentations


Presentation on theme: "Mass Transport of Pollutants. Dense Non-Aqueous Phase Liquids NAPLs – – Insoluble in water and – Separate phase Dense NAPLs – – More dense than water."— Presentation transcript:

1 Mass Transport of Pollutants

2 Dense Non-Aqueous Phase Liquids NAPLs – – Insoluble in water and – Separate phase Dense NAPLs – – More dense than water – Chlorinated hydrocarbons Trichloroethylene-TCE Tetrachloroethylene- PCE Density increases with increasing halogenation Density difference of 0.1% causes sinking

3 Light Non-Aqueous Phase Liquids Light NAPLs – Lighter than water – Petroleum hydrocarbons Oil Gasoline Density difference between water and NAPL of 1% can influence flow Low viscosity NAPLs migrate more rapidly than high viscosity NAPLs

4 Transport Processes Conservation of Mass for dissolved substances in groundwater Rate of change of mass = Flux of mass out – Flux of mass in ± gain or loss of mass due to reactions x y z Mass flux inMass flux out

5 Solutes Conservative (nonreactive) – Do not react with water or soil, do not biologically or radioactively decay Nonconservative (reactive)

6 Physical Processes Controlling Flux Advection – Solutes carried along by flowing groundwater Diffusion – Transport by molecular diffusion Dispersion – Transport by mechanical mixing

7 Solute Spreading

8 Advection – Solutes carried along by flowing groundwater  = porosity v x = average velocity F = Advective flux = Total mass of solute which is carried across a unit area oriented normal to the bulk fluid motion

9 Diffusion – Molecular-based phenomenon – Net movement toward areas of lower concentration F = mass flux per unit area per unit time (M/L 2 /T) D * = apparent diffusion coefficient in soil (L 2 /T) C = solute concentration (M/L 3 ) ∂C/∂x = concentration gradient (M/L 3 /L)

10 Dispersion Mechanical Dispersion – Transport by mechanical mixing F = mass flux per unit area per unit time (M/L 2 /T) D x = dispersion coefficient (L 2 /T) C = solute concentration (M/L 3 ) ∂C/∂x = concentration gradient (M/L 3 /L)

11 F = mass flux per unit area per unit time (M/L 2 /T) D x = dispersion coefficient (L 2 /T) C = solute concentration (M/L 3 ) ∂C/∂x = concentration gradient (M/L 3 /L) Advection-Dispersion Equation

12 Mass Flux x y z Mass flux inMass flux out

13 Mass Balance Equation Mass accumulation

14 Solution

15 Error Function

16 Error Function Values Homework: Problems 881 and 884

17 Groundwater Monitoring

18

19

20 T08_10_04


Download ppt "Mass Transport of Pollutants. Dense Non-Aqueous Phase Liquids NAPLs – – Insoluble in water and – Separate phase Dense NAPLs – – More dense than water."

Similar presentations


Ads by Google