In Situ Remediation of Complex Halo-Organic Mixtures in Source Zones

Transcription

1 In Situ Remediation of Complex Halo-Organic Mixtures in Source Zones..no simple matter Neal Durant, Ph.D. Geosyntec Consultants Columbia, Maryland, USA

2 presentation outline 1. Research history of complex mixtures 2. Effects of mixtures on biodegradation Behavior in example mixtures 3. Case studies example technologies for complex mixture systems Co-solvents Surfactant-enhanced flushing Electrical conductivity heating 4. Some research questions

3 a brief history of time: research timeline for complex mixtures s Present: Biodegradation/substrate interactions in two component systems Competitive inhibition Cometabolism 2. Late 1980s/early 1990s: physical behavior Dissolution of multiple components (Raoult s Law constraints) Solubilization via co-solvents and surfactants 3. Early 1990s Present: Brute force technologies that remediate indiscriminately, tackle whole organic mixture Thermal remediation Chemical oxidation

4 a brief history of time: research timeline for complex mixtures Present: Bioaugmentation for complex chlorinated solvent mixtures 5. Today: bioremediation as a stand-alone technology for mixtures still limited, because: Many mixtures not particularly common. Can t dedicate significant research to unique problem Majority of research has focused on technologies for a single class of contaminants: Chloroethenes Conducting research on multiple component systems difficult because of inherent need for cause & effect controls 6. Today: Application of sequenced technologies becoming more common One size (technology) does not fit all

5 a brief history of time: research timeline for complex mixtures 7. Today: In the U.S., increasingly, sites that haven t been remediated yet are those containing complex mixtures most challenging to solve

6 Mixture Effects on Biodegradation

7 some effects of mixtures on biodegradation 1. Toxic inhibition a. intrinsic toxicity b. concentration toxicity 2. Antagonistic interactions a. Enzymatic competitive inhibition (substitutable substrates) b. Thermodynamic competitive inhibition 3. Synergistic interactions a. Co-metabolism b. Complementary (e.g., donor + acceptor)

8 This study clearly showed that the interaction pattern among the aromatic hydrocarbons is not simple despite the similarities in chemical structure. Much more research is needed to further clarify the interaction effects.

9 Concentration Toxicity in DNAPL Source Areas?

10 Laboratory Studies DNAPL Source Treatment Study Parent Max. Conc. Half-life Compound (% aq. solubility) (days) DiStefano et al. (1991) PCE 91 mg/l (60%) 0.2 Isalou et al. (1998) PCE 100 mg/l (66%) 0.05 Nielsen & Keasling (1999) PCE DNAPL 2-3 Yang & McCarty (2000) PCE DNAPL 5-10 Carr et al. (2000) PCE DNAPL 0.16 Harkness et al. (1999) TCE 170 mg/l (15%) 0.15 Yang & McCarty (2000) TCE 300 mg/l (27%) 3-5

11 Dehalococcoides thrives in presence of chloroethene DNAPL ( > 99% destroyed in 12 months) Baseline Biostimulation Bioaugmentation Concentration (mm) TCE 350 mg/l TCE cis-1,2-dce VC Ethene Total Ethenes Ethene 92 mg/l Aug-02 6-Oct-02 5-Dec-02 3-Feb-03 4-Apr-03 3-Jun-03 2-Aug-03 1-Oct-03 Field data from NASA Launch Complex 34 (Battelle/USEPA, 2004)

12 Mixture System 1: Chloroethenes + Chloroethanes

13 energetics and inhibition of reductive dechlorination: take a look at oxygen Electrons flow to O 2 rather than PCE or TCE, partly because O 2 has a higher energy yield TCE/DCE H + /H 2 (ph = 7) CO 2 /acetate CO 2 /CH 4 SO 4 2- /H 2 S DCE/VC NO 3- /NO - 2 VC/Ethene PCE/TCE Low Energy Yield (mv) O 2 /H 2 O High

14 energetics and inhibition of reductive dechlorination: competition by 1,1,1-TCA Low High Energy Yield (mv) H + /H 2 (ph = 7) CO 2 /acetate CO 2 /CH 4 SO 4 2- /H 2 S DCE/VC VC/Ethene TCA/11-DCA Electrons flow to TCA rather than cdce or VC, partly because TCA has a higher energy yield

15 dechlorination of TCE and cdce by Dehalococcoides (Dhc), absent 1,1,1-TCA Concentration ( µmol per bottle) TCE TCE: 10 mg/l cdce VC Time (Days) Ethene

16 effect of 1,1,1-TCA on dechlorination of TCE by Dhc, absent Dehalobacter (Dhb) Concentration ( µmol per bottle) TCA and TCE: each ~ 10 mg/l TCE TCA cdce Ethene Time (Days) VC Duhamel et al Grostern and Edwards 2006; Grostern et al. 2007

17 bioaugmentation with mixed Dhc/Dhb culture (KB-1 Plus) for mixed TCA/TCE Concentration ( µmol per bottle) TCA TCA and TCE: each 10 mg/l cdce TCE VC DCA Time (days) Ethene CA Grostern and Edwards 2006; Grostern et al. 2007

18 bioaugmentation with KB-1 Plus for mixed TCA/TCE Source Areas: Denmark Case 1, bench test (2008) 0.01 TCE Bioaugmentation CA Concentration (mmoles/bottle) TCA cdce VC Ethene ,1-DCA 1,1-DCA Time (Days)

19 concentration (um) Concentration (um) Clay Till, 5 ppm TCA, no Added TCE, Stimulated TCA DCA 80 CA 60 Ethane PCE TCE 200 Cis-DCE 150 trans-dce DCE VC 50 Ethene Denmark Case 2: mixed TCA/TCE - Vasbyvej bench test TCE completely dechlorinated without evident inhibition Bioaugmentation with Dhc not necessary at Vasbyvej TCA dechlorinated slowly, stalled at 1,1-DCA BATCH 6 days

20 concentration (um) Clay Till, 5 ppm TCA, no Added TCE, Bioaugmented TCA 1.1-DCA CA Ethane Denmark Case 2: bioaugmentation with KB-1 Plus for mixed TCA/TCE - Vasbyvej bench test concentration (um) BATCH 11 days PCE TCE Cis-DCE trans-dce 1.1-DCE VC Ethene

21 Mixture System 2: Chlorinated Solvents + Sulfonamides, Semi-volatiles, and Barbiturates

22 Kærgård Plantage

23 Kærgård Plantage, Jutland, Denmark Scale of Problem: 7.5 million gallons of waste water released containing: SVOCs VOCs Sulfonamides Barbiturates Hydrocarbons Lithium 60,000 metric tons of salts, and organic contaminants Today, contaminant discharge to North Sea is estimated at 50 metric tons/yr Waste pits (grubes)

24 west odor issues waste pits east DNAPL residual

25 North Sea Sulfonamides in Groundwater (mg/l)

26 North Sea Chlorinated solvents in groundwater (µg/l)

27 Antimicrobial aspect of sulfonamides sulfonamides act as structural analogues of the substrate p-aminobenzoic acid (paba); block pathway for bacterial folic acid synthesis and ultimately, DNA synthesis

28 Bench Biotreatability (ERD) at Kærgård: inhibition by Sulfonamides in source area? Chlorinated VOCs 3,500 30,000 3,000 25,000 Concentration (µg/l) 2,500 2,000 1,500 1, ,000 15,000 10,000 5,000 Concentration (µg/l) Tetrachloroethene Methylene Chloride and weeks Chloroform Trichloroethene Tetrachloroethene cis-1,2-dce M ethylene Chloride

29 Bench Biotreatability (ERD) at Kærgård: inhibition less apparent in downgradient plume (sulfonamide concentration 10 x lower than source area) Chlorinated VOCs 10,000 74,000 Concentration (µg/l) 8,000 6,000 4,000 2,000 72,000 70,000 68,000 66,000 64,000 cis-1,2-dce Concentration (µg/l) 0 62, weeks Chloroform Methylene Chloride Vinyl Chloride Trichloroethene trans-1,2-dce cis-1,2-dce

30 Kærgård Source Area: A Job for ISCO Using Fenton s Reagent? (one reagent indiscriminately destroys everything)

31 Mixture System 3: Chloroethenes, Chloroethanes, and CFC-113

32 CFC-113 is a potent inhibitor for chloroethene dechlorination by certain (but not all) dehalorespiring cultures F F Cl C C F Cl Cl 1,1,2-trichloro-1,2,2-trifluoroethane Bagley et al. 2004

33 Example bench test results involving TCE, 111-TCA, and CFC-113 Day 48: Bioaugmented with KB-1 Plus 0.14 Day 77: Augmented with KB-1 Plus Day 139:Purged and spiked with TCE and 1,1,1-TCA and amended with EL and bioaugmented with ACT ,1,1-TCA ,1-DCA Chlorinated Ethanes, Ethane and Freon 113 (mmoles/bottle) Chlorinated Ethenes and Ethene (mmoles/bottle) CA Ethane Freon-113 PCE TCE cdce 1,1-DCE VC 0 0 Ethene Time (days)

34 Example bench test results involving TCE, 111-TCA, and CFC-113 Day 48: Bioaugmented with KB-1 Plus 0.14 Day 77: Rebioaugmented with KB-1 Plus Day 139: Bioaugmented with WBC-2 TM 0.6 1,1,1-TCA Chlorinated Ethanes, Ethane and Freon 113 (mmoles/bottle) Chlorinated Ethenes and Ethene (mmoles/bottle) 1,1-DCA CA Ethane Freon-113 PCE TCE cdce 1,1-DCE VC Time (days) 0 Ethene

35 Occurrence of CFC-113 in Scandinavia Groundwater? 1,1,1-TCA PCE TCE

36 Technology Example A: Surfactant-Enhanced Aquifer Remediation (SEAR)

37 Aqueous Solubility Enhancement Solubility of Organic Compound Organic Surfactant Monomer Critical Micelle Concentration Micelle Containing Solubilized Organic Surfactant Concentration

38 SEAR Technology Overview Surfactant micelles can dramatically increase aqueous solubility Injection of surfactant solution and / or Surfactants can reduce interfacial tension, increasing the mobility of the organic liquid Recovery of solubilized and/or mobilized organic

39 TCE Solubilization: 4% Tween 80 Time: Time: Initial min min min Volume: Volume: ml ml Source: Kurt Pennell, Georgia Tech.

40 Mathematical Modeling of Source Longevity: Potential Benefits of Combined Remedies % Mass Remaining SEAR + Bio Biostimulation Natural gradient Time (d) Christ, J.A., C.A. Ramsburg, L.M. Abriola, K.D. Pennell, and F.E. Löffler (2005). Coupling aggressive mass removal with microbial reductive dechlorination for remediation of DNAPL source zones: A review and assessment. Environ. Health Perspectives, 113:

41 Case Study: Bachman Road Site Oscoda, MI Abriola, L.M., C.D. Drummond, E.J. Hahn, K.F. Hayes, T.C.G. Kibbey, L.D. Lemke, K.D. Pennell, E.A. Petrovkis, C.A. Ramsburg and K.M. Rathfelder A pilot-scale demonstration of surfactant enhanced PCE solubilization at the bachman road site: 1. Site characterization and test design. Environmental Science and Technology, 39:

42 SEAR Process Flow

43 Aqueous Phase PCE Concentration (mg/l) SEAR Performance Tween 80 Cumulative Tween 80 Recovery PCE Time (days after start of SEAR) Aqueous Phase Tween 80 Concentration (g/l) Tween 80 Cumulative Mass Recovery (%) 19 liters of PCE were recovered Source zone concentrations reduced by 100 x No rebound after 4 years Bioactive zone created to treat residual

44 Technology Example B: Co-Solvent Flushing With Biodegradable Cosolvent

45 TCE in Bedrock Ethyl Tennessee Lactate Site An effective cosolvent for chlorinated NAPL An electron donor - hydrolyzed to ethanol and lactate Bench studies and field applications Lee et al. (2006) : residual levels following typical EL CSF could support reductive dechlorination

46 TCE in Bedrock Tennessee Site

47 TCE in Bedrock Tennessee Site

48 Technology Example C: In Situ Thermal Desorption via Conductivity Heating

49 Massachusetts Site VOC concentrations in Groundwater Spring 2005

50 Contaminants Chlorobenzenes (CB, 1,2-DCB, 1,4- DCB, 1,2,4-TCB) Naphthalene 1,1,2,2-Tetrachloroethane Toluene Ethylbenzene Xylene (o-, m-, & p-)

51 Conceptual Layout of ISTD System

52 Construction Complete

53 ISTD Coupled with Groundwater Treatment Multiphase extraction and treatment system installed to: mitigate potential migration of contaminated groundwater from beneath the treatment zone. maintain unsaturated conditions in a majority of the treatment zone intercept NAPL mobilized laterally down gradient

54 Pre- and Post-Treatment Soil Concentrations Starting mg/kg Avg. Sat. 100 C Avg. Unsat. 150 C Total TCB Total DCB MCB Naphthalene Toluene

55 The Unforeseen NAPL recovery increased substantially with increasing subsurface temperatures Increased system volumes for storage and residence time Fluid entrainment ( slurping ) was not the appropriate extraction mechanism at elevated temperatures preferentially strips out more volatile components Groundwater got much hotter (140 F) than anticipated. health and safety Cooled NAPL formed thick (> 2 m) solid, fouling many pumps

56 Mass Removal Estimates ISTD Unsaturated Zone Treatment An estimated 6,600 kg of VOC mass removed Groundwater Extraction An estimated 155 to 240 kg of VOC mass removed NAPL Extraction Approximately 2,600 gallons of NAPL extracted In total 16,000 to 19,000 kg of contaminant mass removed from subsurface 18 to 21 tons of mass removed in one year. BUT Significant mass remained post-treatment because prior characterization failed to delineate DNAPL distribution

57 Parting thoughts/research Considerations 1,4-dioxane is a co-contaminant in 1,1,1-TCA source areas Occurrence in Scandinavian groundwater? Toxicity? Mixture interference with 1,4-dioxane degradation? Consequence of incomplete biotransformation => overall toxicity reduction? Is accumulation of chloroethane a problem if overall toxicity is significantly reduced? Cost of brute force technologies (thermal) vs. slower performing technologies Sequencing treatment technologies increasingly selected over single technologies for complex source areas Sustainable remediation: carbon footprint of different technologies

58 Parting thoughts/research Considerations There is no silver bullet Complex mixtures in source areas are not easily solved each technology has its limitations

59 Questions?