Cometabolic Bioremediation using Gas Infusion Technology

Transcription

1 Cometabolic Bioremediation using Gas Infusion Technology

2 Page 2 Cometabolism Fortuitous degradation o Bugs derive no energy o Contaminants are not carbon source Focus o 1,4-Dioxane o NDMA (N-Nitrosodimethylamine) o Chlorinated compounds

3 Page 3 Cometabolic Bioremediation Benefits Reduces amendment costs Applicable to low contaminant concentrations Achieve site closure

4 Page 4 Aerobic Cometabolism of Chlorinated Ethenes Three key factors must be present or supplied: A primary (growth supporting) substrate Oxygen Bacteria capable of producing nonspecific monooxygenases

5 Page 5 Degradation Pathways Anaerobic Reductive Dechlorination PCE TCE DCEs VC ETH Aerobic Cometabolic TCE TCE epoxide CO 2, CL DCE DCE epoxide CO 2, CL VC VC epoxide CO 2, CL

6 Page 6 Cometabolism Target Code Contaminant Environmental Relevance Propane Monooxygenase Toluene Dioxygenase qppo TCE, DCE, VC Propane can be added as a primary substrate to promote cometabolic oxidation of TCE qtod TCE, DCE, VC Applicable at mixed waste sites where BTEX and TCE are co-contaminants Capable of cometabolism of TCE Ring-Hydroxylating Toluene Monooxygenase qrmo TCE, DCE, VC Applicable at mixed waste sites where BTEX and TCE are co-contaminants Capable of cometabolism of TCE Source: Dora Ogles, Microbial Insights, Inc.,. Rockford, TN

7 Page 7 Dioxane Co-contaminants 1,4-Dioxane is widely used as a stabilizer for chlorinated solvents Dioxane is found commingled with 1,1,1-TCA and its degradation product, 1,1-dichloroethane Dioxane plumes expand faster than chlorinated solvent plumes Mahendra (2011)

8 Page 8 Dioxane, Not Dioxin 1,4-Dioxane

9 Two Biodegradation Processes Mahendra and Alvarez-Cohen (2006)

10 1,4-Dioxane Degradation Pathway Complete conversion to CO 2 No accumulation of toxic intermediates Initial step is energy consuming and rate limiting; subsequent reactions are fast making it difficult to detect intermediates Same pathway for growth supporting and non-growth supporting processes Monooxygenaseenzymes are responsible for degradation in both processes Mahendra et al. (ES&T 2007)

11 Metabolic & Cometabolic Degradation of 1,4-Dioxane

12 Page 12 1,1,1-TCA Inhibits Dioxane Biodegradation (Mahendra & Alvarez-Cohen, in revision)

13 Page 13 Treatability Studies for In-Situ Bioremediation Sandra Dworatzek 2 May 2012

14 Biotreatability Study Design Features Sterile Control autoclaved and poisoned to inhibit microbes measure possible abiotic losses Active Control unamended Biostimulation addition of organic electron donors Bioaugmentation +Biostimulation addition of known degrading populations e.g., KB-1 Biotreatability studies are custom designed for each site Gas Addition H 2 /O 2 addition etc. To measure impact of gas infusion /cometabolic processes e.g. propane addition

15 What results will I get? Rates donor/acceptor/cometabolite consumption contaminant degradation (half lives) degradation intermediate appearance and destruction Lag times Effect of controlling variables (e.g., ph, donor addition, inhibitory effects) Benefits of bioaugmentation

16 How do Biotreatability Studies Improve Remedial Planning? Biotreatability studies allow testing of multiple remedial options in a cost effective manner Studies are flexible allowing changes on the fly during the study without field logistics challenges Incremental risk taking between biotreatability study, field pilot and full-scale remediation is manageable with several jumping off points if required Reassures stakeholders remediation approach is feasible

17 Conclusions Laboratory Biotreatability tests provide: Inexpensive way to evaluate remedial options Site specific contaminant degradation information Adaptable and flexible design

18 Oxygen and Cosubstrate Delivery

19 Page 19 Gas infusion isoc Technology Microporous Hollow Fiber Mass transfer device Supersaturates treatment well without sparging Bioremediation stimulated by delivery of substrates isoc

20 Page 20 isoc Area of Influence isoc Gas Infusion Air Sparging

21 Page 21 Dissolved Gas Concentrations Gas Type Water Column Depth in Feet (Dissolved Gas in ppm) Oxygen Methane Propane Hydrogen Ethane Carbon Dioxide 1,660 1,875 2,090 2,300 3,590

22 Page 22 Gas Management System Oxygen Gas Supply Gas infusion Wells Alkane Gas Supply Nitrogen Connection Groundwater Flow Filter Contaminated Groundwater Treatment Zone isoc Unit

23 Page 23 Installation Photos

24 Page 24 Ground Vault Installation

25 Pacific Northwest 1,4-Dioxane

26

27 Vinyl Chloride Case Study

28 Page 28 Vinyl Chloride Case Study Old gravel pit site PCE release stalled at VC Plume 3000 x 400 x 30 Maximum VC: 30 ppb Anoxic groundwater High iron & sulfate (Mapped Plume 2002 > 3000 feet long)

29 Page 29 Proof of Concept Microcosm O 2, ethene and nutrients 1 um methane = 16 ppb; 1 um ethene = 28 ppb; 1 um VC = 62.5 ppb

30 Copyright 2011 Tersus Environmental, LLC. All Rights Reserved.

31 RB-58 isoc Biobarrier with 20 Treatment Wells (under construction) isoc Treatment Well Line HST-2 Copyright 2011 Tersus Environmental, LLC. All Rights Reserved. 31

32 Page 32 Performance Data (mid-plume) +

33 Page 33 Performance Data (downgradient)

34 Chlorinated Solvent Site Case Study

35 Page 35 Former Industrial Facility

36 Page 36 System Design Two isoc units Industrial grade oxygen and propane Housed separately in portable garden sheds

37 Page 37 cis-1,2-dichloroethylene

38 Page 38 Chlorobenzene

39 Page 39 1,2 Dichloroethane

40 Page 40 Results DO increased 35 feet north and 50 feet west DAP successfully supplied depleted nutrients Effectively distributed dissolved propane

41 Page 41 Conclusions Reduced COCs Allowing approval of MNA and monitoring Gained closure for groundwater

42 Page 42 Thank You What Questions do you have? Gary M. Birk, P.E. Tersus Environmental Tel x 2001 Cell gary.birk@