In Situ and Ex Situ Bioremediation Technologies for Groundwater Contaminated with Chlorinated Solvents

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In Situ

and

Ex Situ

_{Ex Situ}

Bioremediation

Technologies for Groundwater

Contaminated with Chlorinated Solvents

Michelle M. Lorah, U.S. Geological Survey

Emily Majcher , Duane Graves, Geosyntec Consultants John Wrobel, Aberdeen Proving Ground

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East Branch Plume

East Branch Plume West Branch Plumes

In situ test area, Seep 3-4W

Canal Creek Groundwater Treatment Plant- Ex situ test Canal Creek Area, Aberdeen

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Chlorinated VOCs at West Branch Canal Creek and

their anaerobic degradation pathways Ethane 112TCA 12DCA CA 1122 1122- -TeCA TeCA TCE TCE 12DCE VC Ethene PCE PCE CT CT CF MeCl Methane CO₂ HCA HCA PtCA PtCA Ethane 112TCA 12DCA CA 1122 1122- -TeCA TeCA TCE TCE 12DCE VC Ethene PCE PCE CT CT CF MeCl Methane CO₂ HCA HCA

Parent VOCs in orange

Chlorinated ethanes: HCA= hexachloroethane PtCA= pentachloroethane 1122TeCA= 1,1,2,2-tetrachloroethane Chlorinated ethenes: PCE= tetrachloroethene TCE= trichloroethene Chlorinated methanes: CT= carbon tetrachloride CF= chloroform

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Development of WBC

-

2

2 Microbial Consortium

Microbial Consortium

WB2+TeCAWB23+TeCA

WB30+TeCAWB23+TeCA+ TeCA+ TCA VC+acetate+ TCA+ DCE+DCE+ VCV+ TeCAOne month incubation:1)pre-exposure2) reductionV+H DCE2acetateand H+TCA2acetateand H+ DCE2acetateand H+West Branch Consortium15VCethene12522

WB2+TeCAWB23+TeCA

8 liter

20 liter

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WBC-2 Substrate Range

Chlorinated Ethanes, Ethenes, Methanes

y 0 0.1 0.2 0.3 0.4 0.5 0.6 0 2 4 6 8 10 12 14 Days C onc ent rat ion ( m m ol es) 1,1,2,2-TECA 1,1,2-TCA cis-1,2-DCE trans-1,2-DCE VC Ethene TCE 0 0.02 0.04 0.06 0.08 0 5 10 15 20 25 30 Days Ch lor inat ed M et hanes ( m m oles ) 0 1 2 3 4 5 M e thane ( m m o le s) CTC CF DCM CM Methane

►Sediment-free culture with consistent dechlorination ability ►Regularly fed 5 mg/L TeCA, 112TCA, cis12DCE, and lactate

and ethanol (e- _donors)

►Degrades carbon tetrachloride and chloroethene/ethane degradation unaffected

►WBC-2 degradation stable since 2003

ethene

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WBC-2 Microbial Composition

Acidaminococcaceae (putative) No match Dehalococcoides sp. CBDB1 No match Dehalococcoides ethenogenes 195 Dehalococcoides sp. CBDB1 No match Syntrophus Trichlorobacter Dehalobacter Spirochete

Dehalococcoides Desulfovibrio

►Contains at least 17 and 21 distinct Bacteria

phylotypes based on DGGE and clone library analysis, respectively ►Acetobacterium (40%), Dehalobacter (19%), and Acidaminococcacea (9%) most prominent; Dehalococcodies 5% ►Diversity thought to

support substrate range

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Pilot

-

Test Area 3

-

4W

Chloroform

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Reactive Mat Design and Monitoring

Single-hole multilevel diffusion samplers and multilevel wells

Hydraulic Gradient (Artesian) Re-amendment System Aquifer (~40 ft thick) Geotextile

Wetland Sediment (10-15 ft thick) Sand, Peat, Compost, ZVI (option for CT)

Sand, Peat, Compost, Chitin, WBC2 Pea Gravel NOT TO SCALE Seep Area Below surface microwells Passive diffusion bags

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Flow

-

Through Column Tests

-

Biomat

Simulate biomat layers

• Continuous upflow columns • Establish similar discharge

rates/concentrations to field • Evaluate sediment only,

compost/peat mix, and iron layer before compost/peat mix

• Measure VOCs, redox, culture behavior, hydraulic properties

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Degradation of VOCs by WBC

-

_-

2 ₂

seeded sediment in columns

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Bioreactive Mat Construction

Sprayed WBC2 between each wheelbarrow

load of material

Bioreactive Mat Construction

Sprayed WBC2 between each wheelbarrow

load of material

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Reactive Mat Location and

Monitoring Network

Top layer diffusion sampling grid

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-1 1 3 5 7 9 11 13 0 2 uM Concentration4 6 8 D ep th ( F T B LS ) VC cDCE TCE PCE TeCA PCA HCA ETHENE ETHANE -1 1 3 5 7 9 11 13 0 50 100 150 uM Concentration D ept h ( F T B LS ) MeCl CF CT

Reactive Mat

–

VOC Removal

• Consistent vertical profiles of VOC reduction through mat, increased ethene/ethane • 95 to 99% mass removal

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Sustainability of Degradation

(A) Consistent upward flow of VOC to mat over 1 year monitoring period

(B) Consistent VOC degradation within reactive mat over 1 year monitoring period

October 2008 sampling- still effective 4 years after emplacement.

(B) (A)

September 2008→ VOCs non-detect

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Application of WBC-2

in an Anaerobic

Bioreactor for the Canal Creek

Groundwater Treatment Plant

Application of WBC-2

in an Anaerobic

Bioreactor for the Canal Creek

Groundwater Treatment Plant

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Advantages of Fixed Film Anaerobic

Bioreactor System

• Mechanically simple with low energy costs and maintenance

• Very low production of waste solids (sludge)

• Highly resistant to upsets and toxic shock

• Insignificant pretreatment of water (no bag filters needed)

An anaerobic culture is available that can degrade the suite of chlorinated VOCs in the treatment plant influent

WBC-2 has been grown previously on a common

bioreactor support medium in a static batch, where it retained its full dechlorinating ability

Extensive testing of WBC-2 in lab and field has shown its robustness and ability to obtain high rates of degradation

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Treatment Plant Influent

Contaminant (μg/L) (μM) 1,1,2,2-tetrachloroethane (TeCA) 190 1.13 1,1,2-trichloroethane (112TCA) 4.7 0.04 1,,2-dichloroethane (12DCA) 4.2 0.04 Carbon tetrachloride (CT) 15 0.10 Chloroform (CF) 5.6 0.05 Tetrachloroethene (PCE) 2.8 0.02 Trichloroethene (TCE) 130 0.99 Vinyl chloride (VC) 71 1.14

cis- and trans-1,2-Dichloroethene (12DCE) 167 1.72 Total VOCs 590 4.5

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Degradation rates in mat columns

-

-Rates for initial VOC= 40

Rates for initial VOC= 40

μ

M

Contaminant Mean rate Constant (day-1₎ Half-Life (hour) Rate (μM/day) 1,1,2,2-tetrachloroethane (TeCA) 3.43 4.85 140 Chloroform (CF) 2.31 7.20 92 Carbon tetrachloride (CT) 2.83 5.88 113 Tetrachloroethene (PCE) 1.40 11.9 56 Trichloroethene (TCE) 3.04 5.47 122

More than 4 times the

degradation rate in

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WBC-2 20L Vessel Filled with EXCEED Polyurethane Foam 0.0 0.5 1.0 1.5 2.0 2.5 0 5 10 15 20 25 30 35 40 45 50 55 60 Days VOC s mmo les 0 5 10 15 20 25 30 35 40 45 Methane mm oles

TCE cis-12DCE trans-12DCE VC Ethene TeCA 1,1,2-TCA 1,2-DCA Ethane Methane VOCs Spiked: 5 mg/LTeCA, 112-TCA, cisDCE VOCs VOCs VOCs Methane Ethene

WBC-2 has been grown previously on a common bioreactor support medium in a static batch, where it retained its full dechlorinating ability

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Bioreactor Study Objectives

Conduct pre-design testing necessary to evaluate the

effectiveness of WBC-2 for treating chlorinated

VOCs in a bioreactor application

• optimal hydraulic retention time to achieve efficient VOC degradation and meet discharge criteria

• optimal electron donor

• nutrient and electron donor utilization rates

• oxygen consumption rate and design constraints to maintain anaerobic conditions in the bioreactor

• typical equilibration/growth rate for WBC-2 following a change in flow or upset to the system

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in te rn a l i nf o : p a th , d a te re vi se d, a uth o r Figure

KNOXVILLE, TENNESSEE 7 April 2009

Bioreactor Vessel 1 Bioreactor _Vessel 2 Bioreactor Vessel 3 Argon Nutrient Stock Solution Bicarbonate Stock Solution ORP Electrode Clarified Effluent Sludge Separation Peristaltic Pump Groundwater Equalization Tank Peristaltic Pump

Schematic Diagram of the Bioreactor System Electron Donor Solution Samp ling Port s Clarified Effluent Settled Sludge 4.1

• equalization vessel to mix influent with nutrients and donor

• 1-L pretreatment fixed film bioreactor

• Two 1-L fixed film bioreactors for VOC removal

• a 1-L separatory funnel for solids separation

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Bioreactor Bench Test Results

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Bioreactor Bench Test Results

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Bioreactor: Donor Testing

• Microcosms show dissolvable packing

peanuts (corn starch) and corn syrup

are inexpensive possibilities

• Currently testing a lower grade lactate

• Small-scale hydrogen generators

(electrolysis cells) have been made and

will be placed in-line in one of the

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Conclusion:

in situ

bioremediation application of

WBC-2 was successful and preliminary results

show promise for

ex situ

application in bioreactors

USGS Other Current Studies:

• WBC-2 application for RDX and perchlorate

bioremediation, White Sands Missile Range, New Mexico

• WBC-2 application for chlorobenzenes

bioremediation in wetland area, Standard Chlorine Superfund site, Delaware

Cooperative Research and Development Agreement (CRADA) between USGS and GeoSyntec.

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APG - Installation Restoration Program