SAND No. 2010-3070 C
Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company,
for the United States Department of Energy’s National Nuclear Security Administration
under contract DE-AC04-94AL85000.
Remediation of Hazardous Waste
In-situ and Ex-situ Processes
1.
2.
3.
History and Types of Hazardous Waste Sites
Discussion about Past Practices
Remediation Technologies
• Containment
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Grout curtains, slurry walls, capping
Monitoring
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Pump and treat, Air/steam stripping, soil vapor
extraction
Soil washing, solidification, mobile incineration
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Carbon adsorption, bioremediation
Source Control (Soils, Sediments, Sludges)
Groundwater Treatment
2
The Late 20th Century Became a Time
to Focus on Man Made Pollution
SAND No. 2010-3070 C
Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company,
for the United States Department of Energy’s National Nuclear Security Administration
under contract DE-AC04-94AL85000.
Surface and Groundwater Contamination
Leads to Health Problems, Water Shortage
• Mining
• Acid mine drainage
• Heavy metals – Hg, Cr, Pb
• Industrial / Commercial Pollution
• Dyes and pigments
• Petroleum / gasoline
• Agricultural runoff
• Pesticides
• Nutrients – nitrates, phosphates
• Salinization – Sodium, chloride
• Sewage
• Pathogens - Enteric
• Nutrients – Nitrates, phosphates
• Contaminated animal feed
Textile Waste
Gasoline
Mining Waste
SAND No. 2010-3070 C
Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company,
for the United States Department of Energy’s National Nuclear Security Administration
under contract DE-AC04-94AL85000.
The History of Hazardous Waste Pollution
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In 1962, renowned author and naturalist, Rachel Carson, warned
growing contamination “great underground seas” (i.e.,
groundwater) in “Silent Spring.”
Love Canal – New York, USA. Buried barrels of chemicals
underneath new housing development (1950s). Became main
cause for the Superfund legislation. Removed from Superfund in
2004.
Valley of the Drums – Kentucky, USA, 23 acre site with a large
number of leaking drums. Fire at site in 1966. Not completely
cleaned up until 1990.
Times Beach – Missouri, USA community where contaminated oil
was used for dust control from 1972-1975.
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Superfund Sites in the US
Current
Proposed
Complete
Source: Wikipedia Superfund
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Various Pathways Exist for
Contamination From Land Disposal
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Solid Waste can Directly Impact
Human Health
• Solvents – Gasoline, diesel,
chlorinated
• Leachates – Acid waste, heavy
metals
• Hazardous waste – Metals,
paints, solvents, pesticides
• Leaking fuel tanks – Gasoline,
diesel
• Refuse - Decaying animal and
plant matter
SAND No. 2010-3070 C
Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company,
for the United States Department of Energy’s National Nuclear Security Administration
under contract DE-AC04-94AL85000.
Contaminated Land Disposal is Closely
Linked to Water Cycle
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Drinking Water, Wastewater Contaminants
Directly Affect Public Health
Pathogens
Bacteria – Enteric, fecal
Protists – Cysts and spores
Virus - Enteric
Metals
Copper
Lead
Arsenic
Disinfection byproducts
Trihalomethane - CHCl3,,CH2Cl2,
CH2ClBr
Haloacetic acid – CH2ClCO2H
Pesticides
SAND No. 2010-3070 C
Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company,
for the United States Department of Energy’s National Nuclear Security Administration
under contract DE-AC04-94AL85000.
General Lessons Learned in
Remediating Hazardous Waste Sites
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The larger the scope of contamination, the more limited the
cleanup options.
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After the pollutant has dispersed the groundwater may be
undrinkable for years
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Liability and funding for remediation may be quite expensive
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More Lessons Learned
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Cleanup is much more costly and time consuming
than properly managing wastes in the first place.
◦ Treatment and excavation costs
◦ Continuous expense for monitoring
Landfills, lagoons, piles and land spreading will
often create large areas of contamination
Chlorinated solvents are often high density and
thus will “sink” toward groundwater. (DNAPL)
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Remediation can Take Various Pathways
Containment:
Seals off all possible exposure pathways between a
hazardous waste disposal site and environment.
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Slurry Walls
Grout curtains
Drainage systems
Capping
Monitoring
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Slurry Walls and Grout Curtains
are Containment Technologies
Basic Grout Curtain Containment System
Slurry Wall
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Containment Remediation- Slurry Wall
Emplaces Impermeable Barrier
Slurry Wall
• Dig trench around an area
• Backfill trench with an
impermeable material (clay)
slurry
Cross Section of a Slurry Wall
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Slurry Walls are Impermeable Barriers
Made of Clay Materials
Slurry Walls can be placed in a
circular fashion to divert
groundwater around contaminant
Plan View Slurry Wall
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Grout Curtains Injected in the Subsurface
Solidification Reduces Permeability
Grouting
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Inject liquid, slurry, or emulsion under pressure into the
soil
Slury fills pore space
Two types
◦ Particulate – solid + liquid solidifies
◦ Chemical – Liquid +liquid that gels
Grouts are limited when high water table or rapid GW
flow
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Containment Remediation Proceeds in
Steps, Combined with Extraction
Downgradient Barrier and Extraction
Wells (Top and Side Views)
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Upgradient Barrier and Extraction Wells
Love Canal Capping Containment and Drain
Love Canal Barrier, Drain and Capping System
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Groundwater Monitoring is Necessary
to Protect Drinking Water
All containment remedies are accompanied by an extensive
groundwater monitoring.
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Different Technologies used for
Groundwater Remediation
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Groundwater Remediation Reduces
Spread of Contamination
Principally used to remove or reduce hazardous
waste contamination from the groundwater aquifer
passing through or near the site.
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Pump and Treat (including lowering of GW table)
Steam Stripping
Air Stripping
Carbon Adsorption
Bioremediation
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Source Control Prevents Continued
Release or Spread of Contaminants
Used to remove or reduce hazardous waste contamination
from sludges and soils near the site.
 Soil
Vapor Extraction (SVE)
 Air Sparging
 Bioremediation (including Bioventing and Bioreactors)
 Air Stripping and Steam Stripping
 Soil Washing and Soil Flushing
 Stabilization/Solidification
 Vitrification
 Thermal Desorption
 Mobile Incineration
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Pump and Treat
Basic Pump and Treat System (Top and Side Views)
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Air and Steam Stripping for Source Control
Steam Stripper
Air Stripper
These can be used in conjunction with Soil Vapor
Extraction or Groundwater Treatment
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Air Stripping Process - Water Treatment
Air Stripping System
Packed Tower
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Steam Stripping Process – Water Treatment
Typical Steam Stripping Flow Diagram
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Carbon Adsorption - Water Treatment and
Soil Vapor
Fixed-bed Carbon Adsorption Unit
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Carbon Adsorption System
Different Technologies used for
Soil Remediation
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Soil Vapor Extraction (SVE)
• Volatiles swept from
groundwater
• Optional air sparge
• Volatiles captured or
treated at surface
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Soil Vapor Extraction (SVE)
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Air Sparging Enhanced SVE
• SVE commonly enhanced with air
sparging.
• Air sparging involves the active pumping
of ambient air into the subsurface soil
and groundwater to enhance the
collection of volatiles through the SVE
system.
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Bioremediation can Occur In-situ or Ex-situ
•
In-situ typically enhances naturally occurring biological activity
• circulating nutrient and oxygen-enriched water-base solution
• forced air movement provides oxygen to enhance naturally
occurring microbes.
•
Bioventing has air flow rate lower than Soil Vapor Extraction (SVE)
• deliver oxygen
• minimizing volatilization.
•
In-situ biological treatment is effective for non-halogenated volatiles
and fuel hydrocarbons.
•
Technology is less effective for non-biodegradable compounds and
for soils with low permeability.
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Biotreatment of Groundwater (In-situ)
• Use natural occurring and/or
enhanced organisms
• Enhanced biotreatment
involves add O2 and nutrients.
• Proper mixture of O2, nutrients
and bacteria are site-specific
and chemical-specific.
• Technique limited by pH, temp,
toxicity of contaminants, and to
aquifers with high permeability.
• Advantages:cost, minimal
surface facilities minimal public
exposure.
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In-situ Bioremediation
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Bioremediation for Petroleum Waste (Ex-situ)
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Ex Situ bioremediation involves excavating the
contaminated soil
Placing it into biotreatment cells
Adding nutrients to enhance biological activity
Periodically turning it over to aerate the water.
The moisture, heat, nutrients, oxygen, and pH are
usually controlled in the process.
Separation of decontaminated solids
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Ex-situ Bioremediation for Petroleum Waste
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Bioremediation Organisms
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A variety of bacteria
and yeast have been
successfully deployed
in situ and ex situ
biological treatment
systems.
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Soil Washing: Ex-situ
• Excavation
• Wash soil with leaching agent or surfactant
• Not effective with clay or high organic content
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Soil Flushing : In-situ
• Apply water solution to enhance contaminant mobility
• Generated leachate intercepted
• Especially good for halogenated and high permeability soil
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Solidification – Stabilization (S/S)
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Solidification methods physically encapsulate hazardous
waste into a solid material matrix of high structural
integrity.
Stabilization techniques chemically treat hazardous waste
by converting them into a less soluble, mobile or toxic
form.
Principally used for metal-bearing wastes.
Limited applicability to organic wastes.
Typically used to concentrate contaminants prior to S/S.
2 Main types of processes: cement and pozzolanic.
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Cement Stabilization (Ex-situ)
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Description
◦ Slurry of wastes and water is mixed with portland cement
to form a solid.
Advantages
◦ Low cost
◦ Readily available mixing equipment
◦ Relatively simple process
◦ Suitable for use with metals
Disadvantages
◦ Solids are suspended, not chemically bound
 subject to leaching
◦ Doubles waste volume
◦ Requires secondary containment
◦ Incompatible with many wastes
 Organics, some sodium salts, silts, clays, and coal or lignite.
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Pozzolanic Processes (Ex-situ)
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Description
◦ Waste is chemically reacted with lime and a fine-grained
siliceous material (fly ash, ground blast furnace slag,
cement kiln dust) to form a solid.
Advantages
◦ Low costs;
◦ Readily available mixing equipment;
◦ Suitable for power-plant wastes (FGD sludges, etc.) as
well as a wide range of industrial wastes, including
metals, waste oil, and solvents
Disadvantages
◦ Increases waste volume
◦ May be subject to leaching
◦ Requires secondary containment.
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Generic Elements Of A Typical
Ex-situ S/S Process
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Metals/Cyanide S/S Treatment Train
S/S most commonly used for heavy metals and or
cyanides.
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In-situ Vitrification Process - Specialized S/S
Thermal process converts contaminated soil to chemically inert stable
glass/crystalline product.
 Electrical current produces heat –melts soil
 Molten zone grows destroying/encapsulating hazardous constituents
and metals
 Hood for volatile emissions
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• Involves a wide variety of units such as
small liquid waste incinerators at right.
• Multiple trailer rotary kiln for complex
sludges and drummed waste, below.
• Infrared (electrically heated) “soil
roaster” are also used. Infrared is a
form of indirect heating using electric
current instead of fuel oil to generate
heat.
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Acknowledgement and Background
Richard Fortuna, President, Strategic
Environmental Analysis, L.C.
www.richardfortuna.com
SEA.LLC@richardfortuna.com
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31 years experience evaluating technologies and developing preventive
policies for HW management
Developed key provisions of the U.S. statute governing daily waste
management; The Resource Conservation and Recovery Act (RCRA)
Participated in enactment of the “Superfund” cleanup law. RCRA is
intended to prevent the creation of additional “Superfund” or leaking
waste sites
Worked with over 200 companies in evaluating waste treatment
technologies and policies
Authored a text on major reforms to RCRA.
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