10.6 Ex-situ Solid Phase and Vapor Phase

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10.6 Ex-situ Solid Phase and Vapor Phase
http//www.frtr.gov/matrix2/top_page.html
Materials are taken from the Textbook Hazardous
Waste Management. 2nd Ed. Legrega et al., McGraw
Hill
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Ex-situ Solid/Vapor Phase

• Land treatment
• Composting
• Soil piles (Biopiles)
• Land farming

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Biopiles
Biopile treatment is a full-scale technology in
which excavated soils are mixed with soil
amendments and placed on a treatment area that
includes leachate collection systems and some
form of aeration. It is used to reduce
concentrations of petroleum constituents in
excavated soils through the use of
biodegradation. Moisture, heat, nutrients,
oxygen, and pH can be controlled to enhance
biodegradation.
http//www.frtr.gov/matrix2/section4/4_11.html
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Composting
http//www.frtr.gov/matrix2/section4/4_12.html
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Land farming
Land farming is a full-scale bioremediation
technology, which usually incorporates liners and
other methods to control leaching of
contaminants, which requires excavation and
placement of contaminated soils, sediments, or
sludges. Contaminated media is applied into lined
beds and periodically turned over or tilled to
aerate the waste.
http//www.frtr.gov/matrix2/section4/4_13a.html
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Slurry Phase Biological Treatment
Slurry phase biological treatment involves the
controlled treatment of excavated soil in a
bioreactor. The excavated soil is first processed
to physically separate stones and rubble. The
soil is then mixed with water to a predetermined
concentration dependent upon the concentration of
the contaminants, the rate of biodegradation, and
the physical nature of the soils. Some processes
pre-wash the soil to concentrate the
contaminants. Clean sand may then be discharged,
leaving only contaminated fines and washwater to
biotreat. Typically, a slurry contains from 10 to
30 solids by weight.
http//www.frtr.gov/matrix2/section4/4-14.html
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Land treatment
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Assimilative capacity

• Capacity limiting
• Conservative
• Rate limiting
• Non-conservative
• Application limiting
• Transport

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Case study

• BP Oil Alliance Refinery, Belle Chase, IN
• Constructions
• Subsurface drainage systems 4 in laterals _at_20 ft
  5-6 ft below that existing grade
• Treatment zone 4 4.5 ft buffer zone 3ft
• Dike 2 ft above land treatment surface around
  each lots
• Operations

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Case study
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Sampling Monitoring
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Composting

• Aeration
• Windrows
• Static piles
• Enclosed reactors
• An-aerobic/aerobic

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Accepting the equation 10-16, it can be used to
determine the degradation rate constants.
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Enhanced Bioremediation

• Typical Oxygen-Enhanced Bioremediation System for
  Contaminated Ground water with Air Sparging
• Oxygen-Enhanced H2O2 Bioremediation System
• Typical Nitrate-Enhanced Bioremediation System  

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Enhanced Bioremediation
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Oxygen Enhancement with Air Sparging

• Air sparging below the water table increases
  ground water oxygen concentration and enhances
  the rate of biological degradation of organic
  contaminants by naturally occurring microbes.
• Air sparging also increases mixing in the
  saturated zone, which increases the contact
  between ground water and soil.
• The ease and low cost of installing
  small-diameter air injection points allows
  considerable flexibility in the design and
  construction of a remediation system.
• Oxygen enhancement with air sparging is typically
  used in conjunction with SVE or bioventing to
  enhance removal of the volatile component under
  consideration.

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Oxygen Enhancement with Hydrogen Peroxide

• During hydrogen peroxide enhancement, a dilute
  solution of hydrogen peroxide is circulated
  through the contaminated ground water zone to
  increase the oxygen content of ground water and
  enhance the rate of aerobic biodegradation of
  organic contaminants by naturally occurring
  microbes.

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Nitrate Enhancement

• Solubilized nitrate is circulated throughout
  ground water contamination zones to provide an
  alternative electron acceptor for biological
  activity and enhance the rate of degradation of
  organic contaminants.
• Development of nitrate enhancement is still at
  the pilot scale.
• This technology enhances the anaerobic
  biodegradation through the addition of nitrate.
• Fuel has been shown to degrade rapidly under
  aerobic conditions, but success often is limited
  by the inability to provide sufficient oxygen to
  the contaminated zones as a result of the low
  water solubility of oxygen and because oxygen is
  rapidly consumed by aerobic microbes.
• Nitrate also can serve as an electron acceptor
  and is more soluble in water than oxygen.
• The addition of nitrate to an aquifer results in
  the anaerobic biodegradation of toluene,
  ethylbenzene, and xylenes.
• The benzene component of fuel has been found to
  biodegrade slower under strictly anaerobic
  conditions.
• A mixed oxygen/nitrate system would prove
  advantageous in that the addition of nitrate
  would supplement the demand for oxygen rather
  than replace it, allowing for benzene to be
  biodegraded under microaerophilic conditions.