Transcript An Introduction to Bioremediation

Web-based Class Project
on Geoenvironmental Remediation
BIOREMEDIATION
Prepared by:
Sophia Alliota
Josh Colley
With the Support of:
Report prepared as part of course
CEE 549: Geoenvironmental Engineering
Winter 2013 Semester
Instructor: Professor Dimitrios Zekkos
Department of Civil and Environmental Engineering
University of Michigan
What is Bioremediation?
• Bioremediation refers to a number of
technologies that treat contaminated soil and
groundwater by using microorganisms
Applicability
• To contaminants:
– Organic
• Excellent for biodegrading organic contaminants e.g.
petroleum hydrocarbons, chlorinated and non
chlorinated compounds, wood treating agents
– Inorganic
• Metal sulphides such as those found in Acid Mine
Drainage (AMD) can be treated easily using passive
anaerobic wetlands
• Heavy metals can also be immobilized
• To ground conditions:
– Soil treatment
• Almost all soils can be treated using bioremediation as
long as the moisture content is adequate to support
microorganisms
• Low permeability soils can be hard to treat when trying
to permeate amendments through the soil mass
– Groundwater treatment
• Soils of k=10-4 cm/s or greater are treatable
• Again, soils with low k are hard to treat
Common Contaminants
• Organic contaminants include:
– Polycyclic Aromatic Hydrocarbons (PAHs)
• E.g. benzene, toluene
– Polychlorinated Biphenyls (PCBs)
– Pesticides and herbicides
– Chlorinated solvents
• E.g. perchloroethene, trichloroethene
• Inorganic:
– Heavy metals
– AMD effluent containing metal sulphides
Common Sources of Contamination
• Underground Storage Tanks (USTs)
– Leakage of fuels e.g. petroleum
• Wood treating facilities
– Preservatives such as creosote common
• Arsenals
• Chemical manufacturing
plants
Theory
• Fundamentally bioremediation uses
microorganisms (e.g. bacteria, yeast and fungi) to
break down harmful contaminants
• This can be facilitated by using native indigenous
microbes or by adding foreign exogenous ones to
populate the soil
• Different types of microorganisms function well
in different conditions:
– Oligotrophs function well in low carbon environments
– Eutrophs function well in high carbon environments
(USEPA, 2012)
• Microorganisms can break down
contaminants:
– Under aerobic (oxygen present) conditions:
– Under anaerobic (oxygen not present) conditions:
• E.g. fermentation, denitrification
• Sulfate reduction in anaerobic wetlands
• Conditions must be suitable to promote
microbial activity
– Temperature 15-45°C
– pH ~7
– Moisture content 40-80% of field capacity
– Oxygen >2mg/l (aerobic) or <2mg/l (anaerobic)
– Nitrogen, Carbon, Phosphorous etc
• Conditions can be improved be adding
amendments
– Oxygen Releasing Compounds, Nitrogen,
Phosphorous
Flexible methods
• Treatment methods can be:
– In-situ (i.e. in the ground)
• E.g. injection of amendments
– Ex-situ (i.e. out of the ground)
• E.g. composting, land farming
– Aerobic or anaerobic
Landfarming (ETec, 2013)
• An example of an in-situ aerobic method for
treating soil and groundwater
(USEPA, 2001)
Advantages
• Organic contaminants can be broken down into
other nontoxic chemicals
• Minimal equipment requirements
• Can be used in-situ or ex-situ
• Can treat wide range of contaminants
• Low cost
– $30-750 per cubic yard of soil
– $33-200 per 1000 gallons of water
• Good public perception since ‘natural’ process
Disadvantages
• Contaminants may only be partially broken
down creating toxic by-products
• Sensitive to ground conditions
• Monitoring to accurately track degradation
• In ex-situ processes VOCs need to be
controlled
Field Setup: In-situ Bioremediation
(Tlusty, 1999)
Field Setup: Ex-situ Bioremediation
(USEPA, 1995a)
Field Setup: Land Farming
(ETec, 2013)
Field Setup: Windrow
(Proper, 2013)
Case Study: French Limited Superfund Site
• French Limited in Crosby, Harris County, Texas
(EPA Region 6) was a 25-acre sand mining site
from 1950-1965
• The primary contaminants in this waste were
benzo(a)pyrene, vinyl chloride, and benzene
• In 1987, the EPA decided to try
bioremediation, which was the first time that
technology was used at a Superfund site
Case Study: French Limited Superfund Site
(EPA, 1993)
Case Study: French Limited Superfund Site
• Bioremediation was chosen because it offered
a less expensive option to destroy the same
amount of waste as an incinerator in the same
amount of time
• In-situ slurry-phase bioremediation was
conducted to remedy the site
Case Study: French Limited Superfund Site
(EPA, 1993)
Case Study: French Limited Superfund Site
• Treatment process took 11 months to treat
300,000 tons of soil and sludge
• Post-treatment benzene concentrations 7-43
mg/kg
• After initial remediation, the French Limited
site has been revisited several times to
mitigate contamination from floods
References
• ETec Environmental Technologies LLC (2013). "Landfarming". ETec LLC.
http://www.etecllc.com/landfarming-bioremediation.asp (March 13th
2013)
• Tlusty, B. (1999) "In Situ Bioremediation of Tricholoroethylene". Resoration
and Reclamation Review, Student Online Journal - Department of
Horticultural Science, University of Minnesota, Vol 5, Number 2, 1-8.
• Proper (2013). "PROPER Gallery - Bioremediation Gallery". Proper.
http://proper.menlh.go.id/proper%20baru/html/menu%205/proper%20ga
lery/biore%20galery.htm (March 13th 2013).
• USEPA. (1993). "Superfund at Work: Hazardous Waste Cleanup Efforts
Nationwide". USEPA.
• USEPA. (2001a, September). "Use of Bioremediation at Superfund
Sites". EPA 542-R-01-019 .
• USEPA. (2012, September). "A Citizen's Guide to Bioremediation". EPA
542-F-12-003 .
More Information
More detailed technical information on this project can be found at:
http://www.geoengineer.org/education/web-based-classprojects/geoenvironmental-remediation-technologies