Toxicology Issues & Groundwater Toxicology Issues & - - PowerPoint PPT Presentation

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Toxicology Issues & Groundwater Toxicology Issues & Groundwater Remediation from Fuel Leaks Remediation from Fuel Leaks

South Korean MTBE Clean Fuels Workshop South Korean MTBE Clean Fuels Workshop Grand Hilton Hotel Grand Hilton Hotel Seoul, South Korea Seoul, South Korea 3 November 2004 3 November 2004 John Kneiss John Kneiss Chief Consultant Chief Consultant Clean Transportation Advisory Council Clean Transportation Advisory Council

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Presentation Outline Presentation Outline

• Toxicology & Health Risk Issues

Toxicology & Health Risk Issues

• Petrol Constituents of Concern

Petrol Constituents of Concern

• Emissions

Emissions

• Exposure Scenarios

Exposure Scenarios

• Comparative Risk Analysis

Comparative Risk Analysis

• Groundwater Remediation from Fuel Leaks

Groundwater Remediation from Fuel Leaks

• Technologies/Processes for Removal

Technologies/Processes for Removal

• Drinking Water Treatment

Drinking Water Treatment

• Bioremediation & Natural Attenuation

Bioremediation & Natural Attenuation

• MTBE & U.S. Situation

MTBE & U.S. Situation

• Conclusions & Questions

Conclusions & Questions

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Some Background About Toxicology

• Toxicology defined as study of nature, effects and

Toxicology defined as study of nature, effects and detection of toxins and treatment of toxic exposures detection of toxins and treatment of toxic exposures

• “Dose Makes the Poison”

“Dose Makes the Poison”

• What Toxicology Studies Can’t Tell Us?

What Toxicology Studies Can’t Tell Us?

• Toxicology Studies

Toxicology Studies

• Animal Tests

Animal Tests

• Genetic Tests

Genetic Tests

• Human Volunteer Tests

Human Volunteer Tests

• Epidemiology

Epidemiology Studies Studies

• Exposure Studies

Exposure Studies

• “Risk Assessment” Process

“Risk Assessment” Process

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Toxicology – Often Misrepresented

• Advances in study methods have expanded our

Advances in study methods have expanded our understanding of how substances interact with living understanding of how substances interact with living systems systems

• “Dose Makes the Poison”

“Dose Makes the Poison”

• At HIGH enough exposure, anything can be “toxic”

At HIGH enough exposure, anything can be “toxic”

• Interactions (synergism) from exposure to complex

Interactions (synergism) from exposure to complex mixtures mixtures

• What Toxicology Studies Can’t Tell Us?

What Toxicology Studies Can’t Tell Us?

• Can’t prove something is “safe”

Can’t prove something is “safe”

• Can’t demonstrate individual risk

Can’t demonstrate individual risk

• Can show statistical correlation for effects

Can show statistical correlation for effects

• Can be poor predictors for potential human risk

Can be poor predictors for potential human risk

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Toxicological Studies – Animal Studies

• Laboratory tests using control (unexposed) and

Laboratory tests using control (unexposed) and exposed animal groups exposed animal groups

• Various exposure routes

Various exposure routes – – oral, dermal, inhalation

• ral, dermal, inhalation –

– to to best mimic human exposure potential best mimic human exposure potential

• Neurotoxicity

Neurotoxicity studies studies

• Reproductive and developmental studies

Reproductive and developmental studies

• Systemic effects studies

Systemic effects studies

• Genetic assays

Genetic assays

• Carcinogenicity

Carcinogenicity studies studies

• Pharmacokinetics

Pharmacokinetics – – How substances enter the body, How substances enter the body, get distributed to tissues, become metabolized and get distributed to tissues, become metabolized and then eliminated (or retained) then eliminated (or retained)

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Epidemiology Studies

• Human volunteer studies

Human volunteer studies

• Adapted from pharmaceutical methodology

Adapted from pharmaceutical methodology

• Rarely conducted for industrial materials

Rarely conducted for industrial materials

• Intended to help interpret findings from animal

Intended to help interpret findings from animal studies studies

• Epidemiological studies

Epidemiological studies – – investigations of effects in investigations of effects in human populations human populations

• Confounding factors complicate study designs & data

Confounding factors complicate study designs & data interpretations interpretations

• Sub

Sub-

• populations

populations – – unique exposure conditions unique exposure conditions

• Exposure studies

Exposure studies – – collection of monitoring data collection of monitoring data

• Macro

Macro-

• environments

environments

• Micro

Micro-

• environments

environments

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Risk Assessment Process

• Risk Assessment

Risk Assessment – – Estimation of potential risk of Estimation of potential risk of exposure AND management (mitigation) of that risk exposure AND management (mitigation) of that risk

• Hazard characterization

Hazard characterization – – classification schemes classification schemes

• Risk estimation

Risk estimation – – statistical methods to quantify statistical methods to quantify risk potential for particular exposures risk potential for particular exposures

• Risk management

Risk management – – defining and implementing defining and implementing appropriate control measures appropriate control measures

• Comparative Risk Assessment

Comparative Risk Assessment – – evaluations to set evaluations to set priorities for public health protection priorities for public health protection

• Should have comparable data sets

Should have comparable data sets

• Should be conducted without bias (objectivity)

Should be conducted without bias (objectivity)

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Petrol Constituents of Concern Petrol Constituents of Concern

• Petrol

Petrol – – Complex Mixture of Hundreds of HC Compounds Complex Mixture of Hundreds of HC Compounds

• Non

Non-

• soluble fraction

soluble fraction – – generally little concern generally little concern

• Aromatics

Aromatics – – especially benzene especially benzene

• Olefins

Olefins – – mainly air emissions from fuel combustion mainly air emissions from fuel combustion

• Oxygenates

Oxygenates

• Fuel

Fuel-

• Ethanol

Ethanol

• MTBE

MTBE

• Other Ethers

Other Ethers

• Additives, including octane enhancers, detergents, etc.

Additives, including octane enhancers, detergents, etc.

• Extensive Studies on Petrol mixture & emissions, but only

Extensive Studies on Petrol mixture & emissions, but only few individual compounds examined closely few individual compounds examined closely

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Petrol Petrol – – Toxicology/ Toxicology/Epidemiology Epidemiology Summary Summary

• Petrol

Petrol – – overall classification “Probable Carcinogen”

• verall classification “Probable Carcinogen”
• Based on epidemiological data (worker studies)

Based on epidemiological data (worker studies)

• Findings mainly associated with Benzene exposure levels

Findings mainly associated with Benzene exposure levels

• Emissions profile (1,3

Emissions profile (1,3-

• butadiene) may contribute to risk

butadiene) may contribute to risk

• General population unlikely to be at risk

General population unlikely to be at risk

• Certain sub

Certain sub-

• populations with prolonged, significant

populations with prolonged, significant exposures may have increased risks exposures may have increased risks

• Neurotoxicity

Neurotoxicity issues issues

• Due to aromatics levels

Due to aromatics levels

• Toluene/

Toluene/Ethylbenzene Ethylbenzene – – neurotoxicants neurotoxicants at high exposures at high exposures

• Extensive Studies on Mixture & Emissions

Extensive Studies on Mixture & Emissions – – over 3,000

• ver 3,000

citations in technical literature citations in technical literature

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Oxygenates Oxygenates -

• Fuel

Fuel-

• Ethanol

Ethanol

• Denatured Ethanol (fuel

Denatured Ethanol (fuel-

• ethanol)

ethanol) – – health risks uncertainty health risks uncertainty

• Limited toxicological study on ‘neat’ ethanol

Limited toxicological study on ‘neat’ ethanol

• Most data for ingestion (rather than inhalation)

Most data for ingestion (rather than inhalation)

• Studies on mixture with petrol lacking

Studies on mixture with petrol lacking

• Alcoholic Beverages & Consumption

Alcoholic Beverages & Consumption

• Broadly classified as Known Human Carcinogen

Broadly classified as Known Human Carcinogen

• Broadly classified as reproductive & developmental toxin

Broadly classified as reproductive & developmental toxin

• Effects to

Effects to immunological immunological system system

• Effects to endocrine/hormonal system

Effects to endocrine/hormonal system

• Ethyl Alcohol is single common ingredient to all alcoholic

Ethyl Alcohol is single common ingredient to all alcoholic beverages beverages

• Critical uncertainty to health risk is exposure levels

Critical uncertainty to health risk is exposure levels

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Oxygenates Oxygenates -

• MTBE

MTBE

• Methyl tertiary

Methyl tertiary-

• Butyl Ether (MTBE)

Butyl Ether (MTBE) – – extensively tested extensively tested and evaluated and evaluated

• Over 140 toxicological studies carried out

Over 140 toxicological studies carried out

• Over 20 hazard/risk assessments conducted

Over 20 hazard/risk assessments conducted

• Human exposure studies performed

Human exposure studies performed

• Epidemiological investigations made

Epidemiological investigations made

• MTBE is NOT classified as carcinogenic by international

MTBE is NOT classified as carcinogenic by international authoritative bodies authoritative bodies

• World Health Organisation

World Health Organisation – – IARC IARC

• European Union

European Union – – Existing Substances Program Existing Substances Program

• U.S. National Toxicology Program

U.S. National Toxicology Program

• California Scientific Advisory Board (Prop 65)

California Scientific Advisory Board (Prop 65)

• U.S. EPA has NOT conducted formal risk analysis

U.S. EPA has NOT conducted formal risk analysis

• Only California regulatory group (OEHHA) concluded

Only California regulatory group (OEHHA) concluded risk potential risk potential

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Oxygenates Oxygenates -

• MTBE

MTBE

• No impact to reproductive health or developmental

No impact to reproductive health or developmental effects effects

• As ether, MTBE is

As ether, MTBE is neuro neuro-

• active at very high exposures

active at very high exposures (CNS depression, but no lasting effects) (CNS depression, but no lasting effects)

• Acute symptoms (headache, etc.) not confirmed, but

Acute symptoms (headache, etc.) not confirmed, but may affect sensitive people may affect sensitive people

• Findings from animal cancer studies debated

Findings from animal cancer studies debated – – likely likely due to unique mechanisms in rodents due to unique mechanisms in rodents

• Extensive data via inhalation exposure route, more

Extensive data via inhalation exposure route, more limited for ingestion limited for ingestion

• Odor & taste properties may alter to exposure through

Odor & taste properties may alter to exposure through drinking water drinking water

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Oxygenates Oxygenates – – Other Ethers Other Ethers ETBE, TAME, DIPE ETBE, TAME, DIPE

• Generally limited data sets

Generally limited data sets – – although testing continues although testing continues in U.S. in U.S.

• Qualitatively similar to MTBE

Qualitatively similar to MTBE – – based on comparative based on comparative data and metabolism studies data and metabolism studies

• Formal risk assessments have not been conducted

Formal risk assessments have not been conducted

• Product blending to petrol in fewer markets

Product blending to petrol in fewer markets – – so less so less

• pportunity to collect data
• pportunity to collect data
• As with other components, quantitative

As with other components, quantitative Comparative Assessments have not been Comparative Assessments have not been carried out. carried out.

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Other Additives Other Additives

• Most performance additives

Most performance additives – – detergents, detergents, antioxidants, corrosion inhibitors antioxidants, corrosion inhibitors – – have have limited limited tox tox data sets data sets

• Exception is MMT

Exception is MMT – – methylcyclopentadienyl methylcyclopentadienyl-

• manganese

manganese

• U.S. EPA collecting baseline information for fuels

U.S. EPA collecting baseline information for fuels registration registration

• Proprietary nature of these products

Proprietary nature of these products – – tox tox data data developed by individual company developed by individual company

• Performance & emissions properties when blended in

Performance & emissions properties when blended in petrol petrol

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Emissions Factors Emissions Factors

• Extensive assessments of vehicle emissions based on

Extensive assessments of vehicle emissions based on varying petrol properties varying petrol properties

• Priority Air Pollutants

Priority Air Pollutants – – CO, Ozone, PM CO, Ozone, PM

• Air Toxics

Air Toxics – – Benzene, 1,3 Benzene, 1,3-

• butadiene, Aldehydes

butadiene, Aldehydes

• Direct Exposure (fuel vapors)

Direct Exposure (fuel vapors)

• Environmental releases

Environmental releases

• Surface water

Surface water

• Ground water

Ground water

• Drinking water

Drinking water

• Emissions types & characteristics in environment

Emissions types & characteristics in environment influence risk analysis influence risk analysis

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Exposures Factors Exposures Factors

• Exposure conditions

Exposure conditions – – route, duration, concentration route, duration, concentration – – significantly impact potential for health effects significantly impact potential for health effects

• Inhalation

Inhalation – – most common route of exposure most common route of exposure

• Production workers

Production workers

• Occupational setting (mechanics, taxi driver, etc.)

Occupational setting (mechanics, taxi driver, etc.)

• Consumers

Consumers

• Dermal

Dermal – – generally limited exposures generally limited exposures

• Ingestion

Ingestion – – least likely exposure route least likely exposure route

• Fuel release that reaches drinking water source

Fuel release that reaches drinking water source

• Concentration level depends on mass of release

Concentration level depends on mass of release

• Taste/odor properties

Taste/odor properties

• Exposure factors on risk analysis

Exposure factors on risk analysis – – multiple routes & multiple routes & multiple chemicals multiple chemicals

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Risk Analysis Risk Analysis

• Hazard

Hazard Characterisation Characterisation

• Determination made without exposure context

Determination made without exposure context

• Different health endpoints & classification schemes

Different health endpoints & classification schemes

• Risk Estimation

Risk Estimation

• Uses scientific weight

Uses scientific weight-

• of
• f-
• evidence approach

evidence approach

• Determination of risk factors

Determination of risk factors – – potency, exposure, potency, exposure, sensitivity sensitivity

• Uncertainty factors

Uncertainty factors – – extrapolation between data sets extrapolation between data sets

• Risk Management

Risk Management

• Government intervention & regulatory controls

Government intervention & regulatory controls

• Voluntary initiatives & industry standards

Voluntary initiatives & industry standards

• Comparative Risk Assessment

Comparative Risk Assessment

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Schematic of Multi-media Risk Assessment

Emissions Characterization: Environmental Fate: Air/Water/Soil Quality Scientific Risk Analysis Risk Management Health Effects Ecosystem Effects Exposures: : Humans/Biota Feedstocks, Fuel Production, Distribution, Use

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Health/Toxicology Summary Health/Toxicology Summary

• Petrol is hazardous mixture requiring proper

Petrol is hazardous mixture requiring proper handling, transport, storage, and use handling, transport, storage, and use

• Oxygenate blendstocks are no more, possibly

Oxygenate blendstocks are no more, possibly less, hazardous that petrol less, hazardous that petrol

• Health risks for general population from exposure

Health risks for general population from exposure to petrol & major components are minimal to petrol & major components are minimal

• Data available and quality vary significantly for

Data available and quality vary significantly for various petrol components various petrol components

• Risk analysis is highly complex process,

Risk analysis is highly complex process, encountering many uncertainties encountering many uncertainties

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Some References Some References

• Williams P. et al. (2003). Data available for evaluating the

Williams P. et al. (2003). Data available for evaluating the risks and benefits of MTBE and ethanol as alternative fuel risks and benefits of MTBE and ethanol as alternative fuel

• xygenates.
• xygenates. Risk Analysis

Risk Analysis, 23 (5), 1085 , 23 (5), 1085-

• 1115

1115

• European Commission, European Chemicals Bureau.

European Commission, European Chemicals Bureau. (2002). MTBE (2002). MTBE – – Summary Risk Assessment Report. Summary Risk Assessment Report. Publ Publ. .

• No. I.02.101
• No. I.02.101

http://ecb.jrc.it/DOCUMENTS/Existing http://ecb.jrc.it/DOCUMENTS/Existing-

• Chemicals/RISK_ASSESSMENT/SUMMARY/mtbesum313.pd

Chemicals/RISK_ASSESSMENT/SUMMARY/mtbesum313.pd f f

• Williams, P.R.D., and P. Sheehan. 2002. Overview of MTBE

Williams, P.R.D., and P. Sheehan. 2002. Overview of MTBE exposures and health risk in the U.S. exposures and health risk in the U.S. Soil Sediment and Soil Sediment and Groundwater Groundwater, MTBE Special Edition , MTBE Special Edition. .

• Williams P, et al. (2002). Comparative risk analysis of six

Williams P, et al. (2002). Comparative risk analysis of six volatile organic volatile organic coompounds coompounds in California drinking Water. in California drinking Water. Environ.

• Environ. Sci

Sci. . Technol Technol. . 36(22), 4721 36(22), 4721-

• 4728.

4728.

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Groundwater Remediation Groundwater Remediation

• Technologies & Processes for Removal

Technologies & Processes for Removal

• Ex

Ex-

• situ

situ & in & in-

• situ

situ processes processes

• Impacts of MTBE

Impacts of MTBE

• Site

Site characterisation characterisation & investigation & investigation

• Remediation impacts of BTEX

Remediation impacts of BTEX

• Drinking Water Treatment

Drinking Water Treatment

• Process alternatives

Process alternatives

• Cost factors

Cost factors

• Findings on operations & effectiveness

Findings on operations & effectiveness

• Bio

Bio-

• remediation & Natural Attenuation

remediation & Natural Attenuation

• Factors impact biological processes

Factors impact biological processes

• Research activities

Research activities

Soil & Groundwater Remediation Technology Matrix: Ex-Situ

• Groundwater Treatment

Groundwater Treatment

i iAir Stripping Air Stripping i iAdvanced Oxidation Advanced Oxidation i iActivated Carbon Activated Carbon i iBiological Processes Biological Processes

• Excavation

Excavation

i iVapor Extraction Vapor Extraction i iThermal Thermal Desorption Desorption i iChemical Treatment Chemical Treatment

Technology “Success”

Air Sparging

15 / 16

Pump and Treat

10 / 16

Natural Attenuation

9 / 13

Multiple-Phase Extraction

8 / 13

Biosparging

5 / 9

Bioreactor

0 / 3

Success Rate in Removing MTBE Success Rate in Removing MTBE Various Remediation Processes Various Remediation Processes

Source: Hitzig et al., 2000

Technology “Success”

Soil Vapor Extraction

14 / 15

Biodegradation

4 / 8

Excavation

4 / 4

Low Temperature Thermal Desorption

4 / 6

Oxygen Injection

0 / 1 Groundwater Groundwater Soil Soil

0 % < 2 0 % 2 0 -4 0 % 4 0 -6 0 % 6 0 - 8 0 % 2 4 6 8 1 0 1 2 1 4 1 6 1 8 2 0 Number of States 0 % < 2 0 % 2 0 -4 0 % 4 0 -6 0 % 6 0 - 8 0 % P e r c e n t o f L U S T S it e s W h e r e R e m e d ia tio n is D r iv e n b y M T B E C o n ta m in a tio n N o n - R F G S ta te R F G S ta te

0% < 20% 20-50% 50-100% > 100% 0% 10% 20% 30% 40% 50% 60% 70% Percentage of Sites 0% < 20% 20-50% 50-100% > 100% E stim ated C ost P ercentage Increase due to M TB E R em ediation N on-R FG State R FG State

Effects of MTBE on Remediation Effects of MTBE on Remediation

Source: Hitzig et al., 2000

Soil & Groundwater Soil & Groundwater -

• In

In-

• Situ Remediation

Situ Remediation Technology Matrix Technology Matrix

Phase Transfer Transformation/Removal

• Soil Vapor Extraction

Soil Vapor Extraction (SVE) (SVE)

• Soil Heating/SVE

Soil Heating/SVE

• Water Flushing

Water Flushing

• Air

Air Sparging Sparging/SVE /SVE

• In

In-

• well Aeration

well Aeration

• Steam Flushing

Steam Flushing

• Multiple Phase

Multiple Phase Vacuum Extraction Vacuum Extraction

• Aerobic Biodegradation

Aerobic Biodegradation

i i MTBE as primary substrate MTBE as primary substrate i i cometabolism cometabolism

• Chemical Oxidation

Chemical Oxidation

i i Hydroxyl Radicals Hydroxyl Radicals

• Thermal Oxidation

Thermal Oxidation

i i Hydrous Hydrous pyrolysis pyrolysis / /

• xidation
• xidation

MTBE and BTEX Site Characterization / MTBE and BTEX Site Characterization / Investigation Investigation

• Analytical method may change due to interference /

Analytical method may change due to interference / masking from hydrocarbons (false positives) masking from hydrocarbons (false positives)

• 3

3-

• dimensional plume characterization required in some

dimensional plume characterization required in some areas areas

• MTBE plume may be difficult to find or fully identify

MTBE plume may be difficult to find or fully identify

• Leading or lagging the BTEX plume

Leading or lagging the BTEX plume

• Preferential pathways

Preferential pathways

• Vertical gradients / recharge

Vertical gradients / recharge

• Presence of MTBE results in initial increase to

Presence of MTBE results in initial increase to characterization costs characterization costs

• Costs should decrease as experience with MTBE sites

Costs should decrease as experience with MTBE sites increases increases

Remediation of MTBE and BTEX Remediation of MTBE and BTEX Compounds Compounds

More Difficult More Difficult

• Slower intrinsic

Slower intrinsic biodegradation biodegradation

• Plume characterization

Plume characterization

• Minimal retardation on

Minimal retardation on soils soils

• Potential for detached

Potential for detached plume plume

• Perception of

Perception of complexity complexity Less Difficult Less Difficult

• Low

Low K Koc

• c
• High Solubility

High Solubility

• Shorter time required

Shorter time required for flushing for flushing

• High vapor pressure

High vapor pressure

Drinking Water Treatment Processes Drinking Water Treatment Processes

• Air Stripping

Air Stripping

• packed tower

packed tower

• bubble strippers

bubble strippers

• low profile

low profile strippers strippers

• aspiration

aspiration

• spray towers
• Advanced Oxidation

Advanced Oxidation

• UV/hydrogen peroxide

UV/hydrogen peroxide

• UV/ozone

UV/ozone

• H

H2

2O

O2

2/ozone

/ozone

• Adsorption

Adsorption

• granular activated

granular activated carbon (GAC) carbon (GAC)

• synthetic resins

synthetic resins

• Biologically Activated

Biologically Activated Filter spray towers Filter

Estimated Treatment Costs: Air Stripping Estimated Treatment Costs: Air Stripping (w/ Off (w/ Off-

• gas Treatment)

gas Treatment)

Total Amortized Costs (per 1000 gallons) for Comparative Treatment Technologies Flow Rate (gpm) Influent Conc. [ppb] Effluent Conc. [ppb] Packed Tower Low Profile Tray Stripping Packed Tower with Off-Gas Treatment 60 200 5 $0.37 $0.43 $0.43 600 200 5 $0.14 $0.34 $0.31 6000 200 5 $0.09 $0.38 $0.26 6000 20 5 $0.07 $0.14 $0.24

Source: MTBE Research Partnership, 1998

Estimated Treatment Costs: Activated Estimated Treatment Costs: Activated Carbon and Advanced Oxidation Carbon and Advanced Oxidation

Total Amortized Costs (per 1000 gallons) for Comparative Treatment Technologies Flow Rate (gpm) Influent Conc. [ppb] Effluent Conc. [ppb] Applied Process Tech. Calgon Oxidation Tech. Granular Activated Carbon 60 200 5 $2.40 $1.17 $1.50 600 200 5 $0.75 $0.52 $0.97 6000 200 5 $0.33 $0.28 $0.91 6000 20 5 $0.26 $0.13 $0.41

Source: MTBE Research Partnership, 1998

Remediation and Treatment: Conclusions Remediation and Treatment: Conclusions

• Removal of MTBE from soil and groundwater is

Removal of MTBE from soil and groundwater is no more difficult than removal of BTEX for most no more difficult than removal of BTEX for most processes (physical/chemical) processes (physical/chemical)

• Depending on release sequence, MTBE presence

Depending on release sequence, MTBE presence may require increase in characterization costs may require increase in characterization costs

• Treatment costs site specific

Treatment costs site specific -

• on average, less
• n average, less

than 20% increase than 20% increase

• Main problem

Main problem--

• -obtaining closure if MTBE
• btaining closure if MTBE

present present

• Limitations on natural attenuation

Limitations on natural attenuation

Remediation and Treatment: Conclusions Remediation and Treatment: Conclusions (cont.) (cont.)

• Existing water treatment technologies effectively remove

Existing water treatment technologies effectively remove MTBE under most conditions to levels below taste and odor MTBE under most conditions to levels below taste and odor threshold threshold

• Drinking water treatment costs for MTBE removal range

Drinking water treatment costs for MTBE removal range from $0.20 to $0.70 / 1,000 gallons from $0.20 to $0.70 / 1,000 gallons

• Watershed management strategies can mitigate threat of

Watershed management strategies can mitigate threat of contamination from petroleum releases to water resources contamination from petroleum releases to water resources

• Costs to remediate mixed BTEX/MTBE subsurface releases

Costs to remediate mixed BTEX/MTBE subsurface releases are highly site specific are highly site specific

• MTBE within BTEX; relative costs for active remediation

MTBE within BTEX; relative costs for active remediation somewhat higher somewhat higher

• MTBE outside of BTEX; costs may increase in proportion to

MTBE outside of BTEX; costs may increase in proportion to plume size plume size

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Bio Bio-

• Remediation (Bio

Remediation (Bio-

• Stimulation)

Stimulation)

• Factors limiting rate of biodegradation MTBE/TBA

Factors limiting rate of biodegradation MTBE/TBA

• low oxygen (< 2mg/L)

low oxygen (< 2mg/L)

• low biomass yield

low biomass yield

• competitive inhibition (e.g., presence of aromatics)

competitive inhibition (e.g., presence of aromatics)

• Cometabolism

Cometabolism

• Aerobic oxidation in the presence of alkanes (M. Hyman, NCSU)

Aerobic oxidation in the presence of alkanes (M. Hyman, NCSU)

• Aerobic oxidation in the presence of

Aerobic oxidation in the presence of propanol propanol ( (Steffan Steffan, , Envirogen Envirogen) )

• Bioenhancement

Bioenhancement

• Oxygen (e.g., air or slow release compounds)

Oxygen (e.g., air or slow release compounds)

• Nutrients (e.g., nitrogen, phosphorus)

Nutrients (e.g., nitrogen, phosphorus)

• Bioaugmentation

Bioaugmentation

• Addition of MTBE

Addition of MTBE-

• degrading microbes (J.

degrading microbes (J. Salanitro Salanitro, , Equilon Equilon Enterprises) Enterprises)

• Can be difficult due to in

Can be difficult due to in-

• situ competition

situ competition

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Bioremediation Research Bioremediation Research

• UC Davis

UC Davis -

• OFA supported field work on MTBE degrading

OFA supported field work on MTBE degrading microbes microbes

• Shell Oil (

Shell Oil (Salanitro Salanitro) ) -

• field studies at Port

field studies at Port Hueneme Hueneme using isolated using isolated microbes microbes

• North Carolina State Univ.

North Carolina State Univ. -

• API supported study of MTBE/UG

API supported study of MTBE/UG plume plume

• Rutgers Univ.

Rutgers Univ. -

• investigation of enhanced biotreatment technology

investigation of enhanced biotreatment technology

• Univ. Mass. Amherst
• Univ. Mass. Amherst –

– investigation anaerobic degradation of investigation anaerobic degradation of MTBE, BTEX MTBE, BTEX

• Univ. Notre Dame
• Univ. Notre Dame –

– using isolated microbe strains that degrade using isolated microbe strains that degrade MBE MBE

• Univ. Waterloo Canada
• Univ. Waterloo Canada –

– long long-

• term plume study of natural

term plume study of natural attenuation of MTBE attenuation of MTBE

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Biodegradation Conclusions Biodegradation Conclusions

• Presence of more easily biodegradable organics can

Presence of more easily biodegradable organics can inhibit MTBE biodegradation rates inhibit MTBE biodegradation rates

• Cellular yield for MTBE as sole carbon source can be

Cellular yield for MTBE as sole carbon source can be low low

• Metabolites of MTBE can inhibit cellular growth (e.g.,

Metabolites of MTBE can inhibit cellular growth (e.g., formaldehyde, TBA) formaldehyde, TBA)

• Rate of MTBE biodegradation is dependent on

Rate of MTBE biodegradation is dependent on

• xygen content for increased activity of natural
• xygen content for increased activity of natural
• rganisms
• rganisms
• Biodegradation of MTBE will occur

Biodegradation of MTBE will occur cometabolically cometabolically with alkanes or with MTBE as sole carbon or energy with alkanes or with MTBE as sole carbon or energy source source

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Toxicology Issues & Groundwater Toxicology Issues & Groundwater Remediation from Fuel Leaks Remediation from Fuel Leaks

QUESTIONS? QUESTIONS?