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NONAQUEOUS PHASE LIQUIDS

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Non-Aqueous - not miscible with water. Phase Liquid ... solid and a gas. the shape of a given mass depends on the container, the volume being independent ... – PowerPoint PPT presentation

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Title: NONAQUEOUS PHASE LIQUIDS


1
NON-AQUEOUS PHASE LIQUIDS
  • Vera Williams
  • April 30, 2003

2
N A P L
  • Non-Aqueous - not miscible with water
  • Phase Liquid - characteristics of a liquid
  • state of matter between a solid and a gas
  • the shape of a given mass depends on the
    container, the volume being independent
  • practically incompressible

3
N A P L
  • Organic compound
  • Usually relatively non polar
  • Has weaker molecular interactions
  • Exhibit interfacial tensions ltltlt water
  • Generally non-wetting with respect to water
  • Wetting with respect to air
  • tend to enter the largest pores first

4
N A P L
  • LNAPL
  • Light Non-Aqueous Phase Liquid
  • density lt than water which is 1 kg/L
  • DNAPL
  • Dense Non-Aqueous Phase Liquid
  • density gt than water

5
N A P L
  • When LNAPL comes in contact with water, it
  • floats on the top
  • partitions in the vadose zone - a vapor phase
  • and a soluble phase in the capillary water
  • preferentially contained in a lens formed over
    capillary zone (water saturation ratio at or near
    1.0)
  • broadening as a function of time

6
N A P L
  • LNAPL moves with the water table
  • entrapment - as water table rises, organic layer
    moves upward also
  • drainage /reconsolidation - as water table drops,
    so does the LNAPL, broadening the elevation range
  • smear zone Sorganic liquid gt Sor (Sor -NAPL
    sat. soil, drainage causes discontinuity)

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9
N A P L
  • DNAPLS may have a different mobility in the
    earth than water. Hydraulic conductivity is a
    function of the intrinsic permeability of the
    formation as well as properties of the liquid.
    All other things in the formation being equal,
    the relative mobility of a NAPL to water will be
    equal to the ratio of ?/?. This means, when
    spilled on the land surface or discharged to the
    subsurface, DNAPLs move vertically under gravity.

10
N A P L
  • K ki?g/?
  • K hydraulic conductivity
  • ki intrinsic permeability
  • ? fluid density
  • g gravitational constant
  • ? fluid viscosity
  • (Fetter,1999) reduces to ?/?

11
N A P L
  • K k?, ???g??, k????
  • K hydraulic conductivity
  • k intrinsic permeability
  • ? fluid density
  • g gravitational constant
  • ? fluid viscosity
  • ? fluidity of the permeating liquid
  • (Hillel,1998) reduces to ? is primarily a fn ?

12
N A P L
  • DNAPL
  • move vertically in the vadose zone with gravity
  • Water is the wetting liquid (occupies the smaller
    pores)
  • DNAPL migrates thru larger pores displacing the
    air

13
N A P L
  • At capillary zone it displaces the water, and
    will continue downward as long as it has
    sufficient mass to overcome the capillary forces
    that hold the water in the pores
  • Most chlorinated solvents are more dense and less
    viscous than water, so they finger, or
    stringer their way down

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15
N A P L
  • Remediation Technologies include
  • In Situ treatment at the site in place, and
  • Ex Situ the contaminated medium is first
  • moved to another location to treat, then
  • disposed of

16
N A P L
  • In Situ technologies
  • Sparging
  • Contaminated soil bioremediation (natural
    attenuation)
  • Leaching and chemical reaction (permeable
    reactive barriers)
  • Vitrification
  • Isolation/containment

17
Ex Situ Technologies
  • Pump and treat
  • Soil Vapor Extraction (SVE)
  • Multiphase Extraction (MPE)
  • Free product recovery
  • Land treatment
  • Incineration
  • Soil washing
  • Asphalt incorporation
  • Solidification
  • /stabilization
  • Excavation

18
N A P L
  • Problem/OpportunityIn the remediation of soil
    and groundwater systems, a major concern is the
    time required for contaminants in the subsurface
    to be released and biodegraded. Cleanup via
    in-situ bioremediation can take up to 100 years
    at sites where contaminants must be desorbed via
    diffusion. Many "pump-and-treat" processes are
    thought to fail partly because desorption
    releases the contaminants very slowly. Another
    cause of slow release could be the limited
    mobility of non-aqueous-phase liquids (NAPLs),
    which become pooled or trapped within soil
    matrices. For these sites, innovative
    technologies are needed to achieve rapid,
    efficient cleanup at competitive costs.

19
N A P L
  • Foam remediation technologies have the potential
    to increase the applicability of in-situ
    bioremediation. Unlike other approaches, foams
    can be designed to remove pollutants and enhance
    bioremediation simultaneously. Although foams
    have been applied successfully underground for
    enhanced oil recovery, they have not yet been
    systematically applied to environmental
    remediation problems closer to the surface.
    Argonne National Laboratory is exploring the
    opportunity to adapt and mature this existing
    technology for environmental remediation
    purposes, such as for the cleanup of hazardous
    waste at federal facilities.

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