United States
Environmental Protection Agency
Office of Solid Waste and
Emergency Response (5203P)
EPA 542-F-l 0-006
March 2010
Green Remediation Best Management Practices:
Bioremediation
Office of Superfund Remediation and Technology Innovation
Quick Reference Fact Sheet
The U.S. Environmental Protection Agency (EPA) Principles for
Greener Cleanups outlines the Agency's policy for evaluating
and minimizing the environmental "footprint" of activities
undertaken when cleaning up a contaminated site.1 Use of
the best management practices (BMPs) recommended in
EPA's series of green remediation fact sheets can help project
managers and other stakeholders apply the principles on a
routine basis, while maintaining the cleanup objectives,
ensuring protectiveness of a remedy, and improving its
environmental outcome.2
Overview
Bioremediation actively enhances the effects of naturally
occurring biological processes that degrade contaminants
in soil, sediment, and groundwater. In situ processes
involve placement of amendments directly into
contaminated media while ex situ processes transfer the
media for treatment at or near ground surface. Green
remediation BMPs for bioremediation address the
techniques for:
• Biostimulation: injection of amendments into
contaminated media to stimulate contaminant
biodegradation by indigenous microbial populations.
Amendments may include air (oxygen) by way of
bioventing, oxygen-releasing compounds to keep an
aquifer aerobic, or reducing agents such as carbon-rich
vegetable oil or molasses to promote growth of
anaerobic microbial populations
• Bioaugmentation: injection of native or non-native
microbes to a contaminated area to aid contaminant
biodegradation; successful bioaugmentation may
involve prior addition of biostimulation amendments to
create the conditions favorable for microbial activity
• Land-based systems: treatment of contaminated soil or
sediment through surface mixing with amendments or
placement of soil/sediment in surface piles or treatment
cells, such as composting or landfarming, and
• Bioreactors: treatment of contaminated soil or
groundwater in a controlled environment to optimize
degradation, such as an in situ bioreactor landfill or
biological permeable reactive barrier (biobarrier) or an
ex situ batch- or continuous-feed reactor.
Designing a Bioremediation System
Early and integrated planning will help design a
bioremediation project involving activities with a minimal
environmental footprint. Effective design will provide
flexibility for modified site or engineering parameters as
cleanup progresses while continuing to accommodate
current or future use of a site. Options for reducing the
footprint of bioremediation implementation can be
affected by local, state, and federal regulatory
requirements. Permits for underground injections, for
example, vary considerably among state regulatory
programs.3 Option evaluation also examines the short-
and long-term advantages and disadvantages of in situ
versus ex situ bioremediation techniques in terms of green
remediation core elements.
Materials
& Waste
Core Elements of Green Remediation
Reducing total energy use and increasing renewable
energy use
Reducing air pollutants and
greenhouse gas emissions
Reducing water use and negative
impacts on water resources
Improving materials management
and waste reduction efforts, and
Enhancing land management and
ecosystem protection
Energy
Successful bioremediation relies on adequate site
characterization and development of a good conceptual
model to assure thorough delineation of the contaminant
source area(s) and plumes. Effective modeling will
typically lower the potential for unnecessary activities and
associated natural resource consumption or waste
generation.4" Techniques such as three-dimensional
imaging, for example, can help optimize placement of
injection boreholes. Representative field data are needed
during in situ bioremediation design to assure: (1)
influential factors such as aquifer hydraulic conductivity,
groundwater geochemistry, and soil heterogeneity and
adsorptive capacity are well understood, (2) the radius of
influence for any injected substrates reaches the entire
target area and spacing of multiple injection points
provides optimal substrate control, and (3) any excavation
for techniques such as installation of a trenched biobarrier
are conducted in a surgical manner.4
Efficiency in energy and natural resource consumption can
be achieved through BMPs that optimize initial design of a
bioremediation system. Early bench-scale treatability tests
on soil collected from the target treatment area will help:
• Determine the onsite mass of contaminant parent and
daughter products, other metabolic products, and
existing microbial populations
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Demonstrate specific biodegradation mechanisms of
potential microbial cultures, chemical substrates, or
amendments
Evaluate potential delivery methods and dispersion
characteristics under simulated aquifer conditions,
including use of options such as biodegradable
surfactants
Select the most suitable reagents or amendments and
optimal concentrations or proportions, and
Determine any need for supplemental technologies to
destroy contaminants in hot spots or areas anticipated
to involve lengthy periods of microbial acclimation.
Profile: Bioaugmentation at MAG-1 Site,
FortDix, NJ
* Began bioaugmentation design through laboratory tests on
MAG-1 groundwater samples to evaluate efficacy of a
commercial bacterial culture in degrading targeted
chlorinated volatile organic compounds (CVOCs) that were
resistant to degradation by native bacteria
* Dispersed the microbial inoculant through a groundwater
recirculation system, which minimized construction of new
wells and associated resource consumption
* Optimized the system within six months of the first (of two)
injections to reduce the initially high volume of buffering
agents and extensive well fouling, resulting in reduced
material consumption and equipment maintenance
* Decreased CVOCs nearly 99% within one year of project
startup without negative impacts to natural groundwater
conditions
Natural resource efficiencies also are gained by
conducting an onsite pilot test that evaluates methods for
delivering the selected substrate or amendment to a
portion of the treatment area. Green remediation BMPs
applied during a bioremediation pilot test will help
optimize full-scale operations and may identify adverse
environmental impacts in the field; for example, improper
addition of nutrients in certain aquatic environments could
quickly cause algal blooms.
Use of innovative reagents from non-traditional sources
can significantly reduce consumption of virgin natural
resources while beneficially using various waste products.
For instance, enzymes are often introduced into the
remedial process to additionally stimulate microbial
degradation of contaminants. These enzymes commonly
exist in agricultural or industrial byproducts that may be
readily available from local sources. One example is
manure compost, which can provide various enzymes
depending on the feedstock and maturity. Another
byproduct gaining use for bioremediation purposes is
spent-mushroom compost, which can be supplied at little
or no cost by local producers. Evaluating potential use of
products often considered to be waste will include
examining the product's traditional fate and demand in
markets other than site remediation.
Land-based systems and in situ bioreactors can
particularly benefit from use of commercial waste.
"Supermulch" contains common byproducts such as
municipal biosolids, wood ash, and paper sludge that can
be included in recipes for soil amendments or placed in a
permeable reactive barrier to enhance activity of
indigenous microbial populations. This approach can also
be integrated with phytoremediation to encourage
contaminant degradation and volatilization while
enriching soil for revegetation in significantly disturbed
areas such as mining sites.
Project designers can establish a schedule for periodic
review of the selected bioremediation process and related
decision points to:
• Determine if any improvements to field operations could
reduce natural resource consumption and waste
generation while maintaining bioremediation efficacy
• Identify any innovative materials that recently
demonstrated success in biologically degrading
contaminants while reducing the project's
environmental footprint
• Identify unanticipated environmental impacts such as
uncontrolled production of secondary byproducts, sub-
optimal nutrient levels, or changes in non-targeted
indigenous microbial populations, and
• Identify other processes that could accelerate
biodegradation in certain areas without significantly
increasing the project footprint; for example, some
injection wells could be equipped with passive air flow-
control devices and renewable energy-powered blowers
to deliver air to the subsurface after bioaugmentation is
conducted.
Future optimization may include introduction of alternate
amendments to remediate portions of a site showing
marginal biodegradation progress or alternate methods to
increase efficiency of reagent delivery.
Integrated planning of bioremediation activities at
Marine Corps Base Camp Lejeune enabled injections of
emulsified vegetable oil and sodium lactate in four
borings to be completed within only one week, which
reduced field redeployment and associated fuel use.
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Profile: Soil Composting at Former JolietArmy
Ammunition Plant, Will County, IL
* Conducted pilot-scale field tests on compost windrows to
optimize the designed soil amendment recipe, amendment
timing, loading rate, and turning frequency
• Constructed a 20-acre composting facility to treat 280,000
tons of excavated explosives-contaminated soil with
amendments such as manure, wood chips, stable bedding,
and spent biodigestor waste from local producers
• Installed a one-million-gallon basin to capture stormwater
runoff for onsite aquifer infiltration
• Began early transfer of uncontaminated acreage to the
U.S. Forest Service in 1997 to the newly formed Midewin
National Jallgrass Prairie, with subsequent transfers of
additional parcels as remediation progressed; by 2002, all
(19,000) targeted acres were conveyed to the Prairie
• Completed soil cleanup in 2008, three years ahead of
schedule, through implementation of an integrated cleanup
and reuse plan for 3,000 acres now under development as
business parks and an engineer training center
Constructing a Bioremediation System
Best management practices initiated during bioremedi-
ation design can continue in the construction phase and
during operation and maintenance (O&M). A significant
portion of the environmental footprint left by construction
of a bioremediation system involves the installation and
testing of wells used to deliver the selected reagents and
monitor performance. Recommended practices include:
• Using direct-push technology for constructing temporary
or permanent wells rather than typical rotary methods,
wherever feasible, to eliminate the need for disposal of
cuttings and improve efficiency of substrate delivery into
discrete vertical intervals
• Maximizing reuse of existing or new wells and boreholes
for injections to avoid a range of wasted resources, and
• Using groundwater recirculation processes allowing
multiple passes of groundwater through fewer wells.
Recommended practices for designing, constructing, and
operating wells, such as those used for in situ injection
and groundwater recirculation, are provided in: Green
Remediation Besf A/lonogemenf Practices: Pump and Treat
Technologies.4c Additional practices for subsurface air
delivery are provided in Green Remediofion Besf
A/lonogemenf Practices: Soil Vapor Extraction & Air
Sparging.Ad
Project managers of land-based bioremediation systems
can reduce the project footprint through BMPs such as:
• Constructing a retention pond within a bermed
treatment area to store, treat, use, or release diverted
stormwater
• Reclaiming clean or treated water from other site
activities for use in injection slurries or as injection
chase water
• Integrating a landfarm rain shield (such as a plastic
tunnel) with rain barrels or a cistern to capture
precipitation for potential onsite use, and
• Evaluating the need for a leachate collection system for
a landfarm (along with a leachate treatment system) to
fully preserve the quality of downgradient soil and
groundwater.
Land disturbance during bioremediation construction,
particularly at sites involving ex situ techniques, can be
reduced through practices such as:
• Maintaining specific areas for different activities such as
materials mixing or waste sorting, which will also avoid
cross-contamination
• Covering ground surfaces of work areas with mulch to
prevent soil compaction caused by activities such as
front-loader application of soil amendments
• Establishing well-defined traffic patterns for onsite
activities, and
• Employing rumble grates with a closed-loop graywater
washing system (or an advanced, self-contained wheel-
washing system) to minimize onsite and offsite trackout
by delivery vehicles.
Emission of greenhouse gas (GHG) and particulate matter
from mobile sources can be reduced through BMPs such
as reducing engine idling, fueling heavy machinery with
ultra low-sulfur diesel fuel, and retrofitting equipment with
diesel oxidation catalysts or other advanced diesel
technology. More practices are outlined in Green
Remediation Best Management Practices: Clean Fuel &
Emission Technologies for Site Cleanup.4"1
Contributors to the Bioremediation Footprint at
Romic East Palo Alto
Energy
Potable water
CO2 equivalent
Sulfur oxides
Particulate matter
Air toxics
Total Estimated
Footprint
23,000 million Btu
6,800,000 gallons
5,000,000 pounds
22,000 pounds
800 pounds
200 pounds
Attributed to
O&M
1 00%
O&M activities account for much of the environmental
footprint of bioremediation recently initiated at the Romic
RCRA site in East Palo Alto, CA. Site investigation, remedy
construction, and future decommissioning also contribute
but to a lesser extent. Although onsite contributors are
relatively small in comparison to offsite factors such as
"upstream" materials manufacturing, they may hold
greater importance to the local community.
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Operating and Monitoring a System
Energy consumption and associated emissions during
bioremediation O&M can be reduced by:
• Introducing biostimulation or bioaugmentation
amendments to the subsurface via gravity feed in
existing wells, when high-pressure injection is
unnecessary to assure proper distribution in certain
geologic units
• Evaluating feasibility of using pulsed rather than
continuous injections when delivering air, to increase
energy efficiency
• Employing portable units or trailers equipped with
photovoltaic panels to generate electricity or direct
power for equipment such as air blowers, and
• Investigating delivery of industrial byproducts needed in
high volumes by way of rail rather than trucks.
Environmentally preferable purchasing in the context of
bioremediation includes products such as:
• Tarps with recycled or biobased contents instead of
virgin petroleum-based contents, for protection of
ground surfaces in staging areas and coverage of soil
undergoing ex situ treatment
• Soil nutrients and other treatment-related materials
available in bulk quantities and packed in recyclable
containers and drums, to reduce packaging waste
• Treatment liquids in concentrated form if a product is
locally unavailable (and the concentration process does
not involve additional energy consumption), to reduce
long-distance shipping volumes and frequencies, and
• Biodegradable cleaning products effective in cold water
applications, to conserve energy while avoiding
introduction of toxic chemicals in environmental media.
Composting of mining waste-contaminated soil and
sediment with municipal hiosolids and lime along the
Upper Arkansas River in Colorado resulted in 100%
vegetative cover in most previously denuded areas
within ten years, due to increased microbial functions
combined with phytoremediation and reduced leachate.
Green remediation relies on continually improving a
project's natural resource efficiencies and scouting for
novel approaches. At the Distler Brickyard Superfund site
in Kentucky, for example, chitin (a natural biopolymer
derived from shrimp and crab shells) was injected into an
aquifer as a source of volatile fatty acids to promote VOC
degradation. Another example is provided at the Naval
Amphibious Base Little Creek in Virginia, where
bioremediation involved injection of diluted cyclodextrin (a
simple sugar) that could be recycled. Information on
reagent options and evaluation of related factors is
provided in various demonstration reports compiled by the
Environmental Security Technology Certification Program
(ESTCP).5
Opportunities to reduce the environmental footprint of
long-term actions can be further reduced through
optimization of the monitoring program. Periodic
reevaluation can help identify potential monitoring
changes such as reduced sampling frequency, fewer
sampling locations, or routine sampling of a smaller well
network as a contaminant plume collapses over time.6
Green Remediation: A Sampling of Success Measures
for a Bioremediation System
" Reduced fuel consumption due to transport of high-bulk
reagents via rail rather than trucks
* Reduced GHG emissions as a result of using gravity-fed
injection systems rather than fuel-fed pumping
* Protection of nearby and downstream surface water
through construction of bermed retention ponds that
capture and treat contaminated stormwater runoff
* Beneficial use of industrial waste or surplus byproducts as
bioremediation reagents
• Reduced soil compaction during system construction as a
result of using well-defined work areas
References [Web accessed: 2010, February 28]
1 U.S. EPA; Principles for Greener C/eonups; August 27, 2009;
http://www.epa.gov/oswer/greencleanups
2 U.S. EPA; Green Remediation: Incorporating Sustainable Environmental
Practices into Remediation of Contaminated Sites; EPA 542-R-08-002,
April 2008
3 Interstate Technology and Regulatory Council; In Situ Bioremediation of
Chlorinated Ethene: DNAPL Source Zones; June 2008
4 U.S. EPA; Green Remediation Best Management Practices:
"Site Investigation; EPA 542-F-09-004, December 2009
b Excavation and Surface Restoration; EPA 542-F-08-012, December
2008
c Pump and Treat Technologies; EPA 542-F-09-005, December 2009
dSoi/ Vapor Extraction & Air Sparging; EPA 542-F-l 0-007, March 2010
"Clean Fuel & Emission Technologies for Site Cleanup; EPA 542-F-l 0-
008, April 2010
5 ESTCP Environmental Restoration Projects and Related Efforts;
http://www.estcp.org/Technology/ER-Chlorinated-Solvents.cfm
6 U.S. EPA and U.S. Army Corps of Engineers; Roadmap to Long-Jerm
Monitoring Optimization; May 2005, EPA 542-R-05-003
Visit Green Remediation Focus online:
http://cluin.org/gresnremediation
For more information, contact:
Carlos Pachon, OSWER/OSRTI (pachon.carlos@epa.gov)
U.S. Environmental Protection Agency
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