Bioremediation of Oil- Contaminated · PDF filehydrocarbon-impacted sites by bioremediation:...

Bioremediation of Oil-Bioremediation of Oil-Contaminated SitesContaminated Sites

Case Studies Involving Light and HeavyCase Studies Involving Light and HeavyPetroleum HydrocarbonsPetroleum Hydrocarbons

Talaat Balba, M.S.C., Ph.D.

Conestoga-Rovers & Associates

Presentation ContentPresentation Content

� Introduction to Petroleum Hydrocarbons

� Characteristics of Petroleum Hydrocarbons

� Problems with Oil Spills

� Treatment Techniques

� Discussion on Bioremediation

� Case Studies

Petroleum HydrocarbonsPetroleum Hydrocarbons

� Manufactured from crude oil

� Made mainly from hydrogen and carbon

� Found in crude oil, gasoline, kerosene,heating fuel oil, and asphalt

� Stored and transported in large volumes byship, rail, truck, and pipelines

� One of most prevalent contaminants insubsurface

Petroleum HydrocarbonsPetroleum Hydrocarbons

Oil Chemical CompositionOil Chemical Composition

� Four main groups of constituents:• saturates (or alkanes);

• aromatics, including such compounds as BTEXand PAHs;

• resins, consisting of compounds containingnitrogen, sulphur, and oxygen, that are dissolvedin oil; and

• asphaltenes, which are large and complexmolecules that are colloidally dispersed in oil

Petroleum HydrocarbonPetroleum HydrocarbonCharacteristicsCharacteristics

Potential Problems AssociatedPotential Problems Associatedwith Oil Spillswith Oil Spills

� Oil migrates down through soils, adsorbing tosoil particles until it reaches groundwater,where oil constituents will dissolve in water,float on water surface (light-end fraction) orsink to bottom of water aquifer (heavyheating fuel oil)

� Any constituent that dissolves in water willtravel with flowing groundwater

Treatment TechniquesTreatment Techniques� Conventional Methods:

• Free product removal by pump and treat ofgroundwater

• Excavation and off-site disposal of impacted soil

• Vapor extraction

� Innovative cost-effective alternative:• Bioremediation

What is Bioremediation?What is Bioremediation?

� Treatment process whereby contaminants aremetabolized into less toxic or nontoxiccompounds by naturally occurringmicroorganisms. The microorganisms canutilize many of the oil constituents as asource of carbon and energy. The by-products are mainly carbon dioxide andwater.

Oil-Eating BacteriaOil-Eating Bacteria

Bioremediation contBioremediation cont’’d...d...

� The microbial population becomes dormantor dies out once all of the contaminantshave been consumed

� Can take place under aerobic or anaerobicconditions in presence of other suitableelectron acceptors such as nitrate, sulfate,or carbonate

� Can be applied in situ or ex situ to treatboth soil and groundwater

Key Biochemical ElectronKey Biochemical ElectronAcceptorsAcceptors

Electron Acceptor Condition Microorganisms

Oxygen Aerobic Aerobes

Nitrate Anaerobic Facultative Anaerobes/Denitrifiers

Sulfate Anaerobic Sulfate Reducers

CO2 Anaerobic Methanogens

Bioremediation contBioremediation cont’’d...d...

� Effective in treating wide range of chemicalsincluding petroleum hydrocarbons

� Two basic ways to treat petroleumhydrocarbon-impacted sites bybioremediation: in situ treatment andtreatment of impacted soil after excavation

Key Environmental FactorsKey Environmental FactorsInfluencing Oil BioremediationInfluencing Oil Bioremediation� Nutritional factors

� Electron acceptors

� Microbes (degraders) in high numbers

� Soil-water content

� Soil structure and organic content

� Temperature

� Toxic compounds

� Solubility of pollutants

Ex Situ MethodsEx Situ Methods

� Landfarming

� Composting piles

� Bioventing

� Phytoremediation

LandfarmingLandfarming

Composting PilesComposting Piles

BioventingBioventing

PhytoremediationPhytoremediation

Ways to EnhanceWays to EnhanceBioremediationBioremediation� Supplement with suitable sources of nitrogen

and phosphorus to enhance biodegradation ofSite contaminants by indigenous microbialpopulation

� Injection or infusion of air or oxygen

� Injection of oxygen release compounds(ORC) to optimize aerobic conditions (oilbiodegrades much faster under aerobicconditions)

More Ways to EnhanceMore Ways to EnhanceBioremediationBioremediation

� Microbubbles

� Oxygen infusion through microporousmembranes

� Application of surfactants to enhancebioavailability of heavy oil hydrocarbons andPAHs

� Bioaugmentation

In situ Biological TreatmentIn situ Biological TreatmentSchemeScheme

Case Study #1 - BioremediationCase Study #1 - Bioremediationof Heavy Oils in Soilof Heavy Oils in Soil

� Locomotive maintenance yard in CA

� Soils contaminated with long chain alkanes inC22+ range

� In some areas, levels of contamination werenear soil saturation level

Oil ChromatographOil Chromatograph

Site SummarySite Summary

� Major Railroad Yard in CA

� 30,000 Tons of Oil-Contaminated Soil(Up to 10%)

� Six other similar sites in CA

� Program Included:• Lab Treatability Study

• Site Demonstration

Site LayoutSite Layout

Project SummaryProject Summary

� Cost-effective biological treatment wasdeveloped and field-demonstrated at the site

� Multi-step laboratory treatability studyfollowed by a field demonstration

� Laboratory results showed up to 94 percentremoval of TPH in less than 16 weeks

Field Demonstration ResultsField Demonstration Results

� Soils contained over 100,000 mg/Kg drysoil of TPH

� Soils were bioaugmented with mixture ofmicrobial inocula and organic and inorganicfertilizers

� More than 85 percent degradation wasachieved in less than 28 weeks

Bioremediation of HeavyBioremediation of HeavyPetroleum Oil in SoilPetroleum Oil in Soil

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Time (weeks)

Case Study #2 - BioremediationCase Study #2 - Bioremediationof Light Oils in Soilof Light Oils in Soil

� Oil refinery in Germany

� Subsurface soils (up to 20 feet below groundsurface) and groundwater were impacted bynaphthene

Field DemonstrationField Demonstration

� Dual treatment process was designed andfield demonstrated at the site

� In situ and ex situ aerobic bioremediation

� Treatments involved application of surface-active agent along with nutrients andmicrobes

Description of Dual TreatmentsDescription of Dual Treatments

� Highly contaminated shallow soils (withconcentrations as high as 12,800 mg/Kg)were excavated and treated by landfarming

� Less contaminated soils (highestconcentrations of 180 mg/Kg) were treatedin situ

Ex situ TreatmentEx situ Treatment

In situ TreatmentIn situ Treatment

ResultsResults

� Oil hydrocarbon concentrations in ex situtreatment were reduced to less than2,000 mg/Kg within 24 weeks (an 84 percentreduction)

� In situ treatment results were similar(86 percent reduction to 26 mg/Kg within15 weeks)

In situ Treatment ResultsIn situ Treatment Results

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Case Study #3 - BioremediationCase Study #3 - Bioremediationof Oil-Contaminated Desert Soilof Oil-Contaminated Desert Soil

� Over 49 Km2 of Kuwait's desert soil werecontaminated as result of exploding oil wellsduring Iraqi invasion and occupation of 1990

Scope of ProblemScope of Problem

� Over 700 ignited oil wells extinguished andcapped

� Additional areas covered with oil and sootaerosols/heavy contamination

� Remediation required to:• restore ecosystems

• avoid underground water contamination

• protect human health

TreatmentTreatment

� Bioremediation selected as alternativeremedial option

� Three methods were field-demonstrated atlarge scale: landfarming, composting piles,and bioventing soil piles (with irrigation andbioventing)

Correlation of C18:phytane ratiowith TPH degradation

C18

:phytane ratio TPH concentration (mg/Kg) TPH reduction

Treatment T0

T6

T12

T0

T6

T12

%

Landfarming 2.4 0.3 ND (0.3) 39400 14000 7200 81.7

Control test 2.4 2.3 2.2 39400 35500 31700 19.5

Windrow piles 2.4 0.4 ND (0.3) 34700 19400 9500 72.6

Control test 2.4 2.4 2.2 35900 39800 30600 14.8

Static piles 1.7 0.5 ND (0.3) 14400 8500 4600 68.1

Control test 1.7 1.6 1.4 14100 13600 12200 13.5

ResultsResults

� Landfarming treatment reduced lightlycontaminated soils by 80 percent within6 months and heavily contaminated soils by80 percent within 12 months

� Results confirm that reduction in TPHconcentration was caused primarily bymicrobial biodegradation and notvolatilization

Phytoremediation for PolishingPhytoremediation for Polishing

� Phytoremediation was used as polishingmethod to further reduce residual level ofTPH and to assess phytotoxicity of residualTPH on growth and performance of widerange of domestic and ornamental plantspecies

� Alfalfa vegetation resulted in much cleanersoil as evident from analysis of TPH, totalextractable matter (TEM), and PAHs

PhytoremediationPhytoremediation

Phytoremediation ResultsPhytoremediation Results

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TEM TPH PAHs

With Cultivation

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ConclusionsConclusions

� Bioremediation is promising technology fortreatment of wide range of contaminants insoil and groundwater, particularly oilcontamination

� Bioremediation is site-specific; therefore,treatability studies are highly recommendedbefore full-scale remediation is considered

Conclusions (contConclusions (cont’’d)d)

� Degradation rate of hydrocarbons isdependent on type of contaminants, metaboliccapabilities of indigenous microbialpopulation, and also on predominantenvironmental factors

� Effectiveness depends to great extent onsuccess in identifying rate–limiting factorsand optimizing them during feasibility studies

Conclusions (contConclusions (cont’’d)d)

� Important to define limitations to the process;both with respect to range of contaminantsthat can be treated and residualconcentrations that can be achieved within anappropriate time frame