Coupling electrochemical with biological oxidation of 1,4-dioxane:

Transcription

1 March 06, 2018 Coupling electrochemical with biological oxidation of 1,4-dioxane: Impacts on degradation rates, co-contaminant removal, and disinfection by-product formation Nasim E. Pica 1, Nicholas W. Johnson 2, Yu Miao 2, Shaily Mahendra 2, Jens Blotevogel 1 1 Colorado State University, 2 UCLA

2 Electrochemical Treatment DC Power Supply Anodic (+) reactions: Organic compound oxidation O 2 production Cl - oxidation cathode (reduction) H 2 O 2 anode (oxidation) Cathodic (-) reactions: Reductive dechlorination H 2 production R-Cl R-H ph ~8-10 ph ~2-4 C org CO 2

3 Electrolytic barriers (e-barriers) 1 cm Ti/IrO2-Ta2O5

4 Biodegradation of 1,4-Dioxane Pseudonocardia dioxanivorans CB1190 can aerobically metabolize 1,4-dioxane. Ø microaerophilic, ph 5-8 Ø inhibited by co-occurring chlorinated solvents Mahendra, S. et al., Chemosphere 2013, 91, 88. Parales R.E. et al., Appl. Environ. Microbiol. 1994, 60, Zhang, S. et al., Environmental Science and Technology 2016, 50, 9599.

5 Research Hypotheses (Solar) DC Power biodegradation downstream in milder conditions transformation of persistent parent to biodegradable intermediates Cl - CO 2 CO 2 O2! e - -acceptor for aerobic 1,4-D biodegradation GW flow electrolytic removal of inhibiting co-contaminants

6 1 st Gen. Bioelectrochemical Reactor Jasmann, Jeramy R., et al. "Synergistic Treatment of Mixed 1,4-Dioxane and Chlorinated Solvent Contaminations by Coupling Electrochemical Oxidation with Aerobic Biodegradation." Environmental Science & Technology 51 (2017):

7 Electrolysis removes inhibiting cocontaminants. Degradation of 1,4-Dioxane (mg h- 1 m -2 ) % 27% 0% 62% 41% % TCE Degraded Absence of TCE Presence of TCE Jasmann, Jeramy R., et al. "Synergistic Treatment of Mixed 1, 4-Dioxane and Chlorinated Solvent Contaminations by Coupling Electrochemical Oxidation with Aerobic Biodegradation." Environmental Science & Technology 51 (2017):

8 qpcr reveals sweet spot of microbial abundance downstream of electrodes. CB1190 Abundance (cells/ml) 1.E E+08 1.E E+06 1.E E+04 1.E E+02 1.E+01 Flow 1,4-Dioxane Feedstock without TCE ph PLANKTONIC E CB1190 Initial CB V CB V CB V LOD CB1190 Abundance (cells/ml) 1.E E+08 1.E E+06 1.E E+04 1.E E+02 1.E+01 1,4-Dioxane Feedstock with TCE + Flow LOD PLANKTONIC 10 1.E Distance 2.5 from anode 12.5 (cm) CB1190 Initial CB V CB V CB V Jasmann, Jeramy R., et al. "Synergistic Treatment of Mixed 1,4-Dioxane and Chlorinated Solvent Contaminations by Coupling Electrochemical Oxidation with Aerobic Biodegradation." Environmental Science & Technology 51 (2017):

9 2 nd Gen. Bioelectrochemical Reactor Material O 2 evolution potential (V) Ti/SnO 2 -x 1.9 Ti/IrO 2 -Ta 2 O 5 1.5

10 Higher potential needed for electrochemical 1,4- D oxidation. 1,4-Dioxane (C 0 = 83 mg/l)

11 1,1-DCE is removed even at low potentials. 1,1-DCE (C 0 = 5 mg/l)

12 3 V is sufficient for O 2 generation.

13 Bulk ph remains within growth optimum.

14 No DBPs observed at 3 V. 3 Volts Organic DBPs below LOD.

15 Higher voltage causes DBP production. 6 Volts Organic DBPs below LOD.

16 Summary Advantages Disadvantages Removal of 1,1-DCE 3 Volts O 2 generation No removal of 1,4-Dioxane no DBPs Removal of 1,4-Dioxane 6 Volts Removal of 1,1-DCE DBP formation O 2 generation

17 Future Studies 1,4 Dioxane Conduct biotic electrochemical oxidation of 1,4- dioxane in presence/absence of co-contaminants Per- and polyfluoroalkyl substances (PFAS) Investigate synergistic treatment of PFAS by integrating electrolytic and fungal oxidation F - DC Power CO 2 Ņ CO 2 H 2 Ņ O Anoxic Groundwater Phanerochaete chrysosporium Tseng et al., Environ. Sci. Technol. 2014, 48, 4012Þ4020

18 Thank you!

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20 High voltage increases O 2 generation. CB1190 Abundance (cells/ml) 1.E E E+07 1.E E E E E E Flow DO (mg/l) PLANKTONIC 1.E ,4-dioxane only LOD CB1190 Abundance (cells/ml) 1.E E E+07 1.E E E E E E Flow + ORP (V) PLANKTONIC 1.E LOD CB1190 Initial CB V CB V CB V CB1190 Initial CB V Distance from anode (cm) CB1190 Initial CB V CB V CB V CB1190 Initial CB V Jasmann, Jeramy R., et al. "Synergistic Treatment of Mixed 1, 4-Dioxane and Chlorinated Solvent Contaminations by Coupling Electrochemical Oxidation with Aerobic Biodegradation." Environmental science & technology (2017):

21 Dimensionally stable anodes (DSAs) active vs. non-active Material O 2 evolution potential (V) Ti/SnO 2 -x 1.9 Ti/IrO 2 -Ta 2 O Ti/SnO2-X C. Comninellis, Electrochem. Acta 1994, 39,

22 1,4-Dioxane Stabilizer for chlorinated solvents Low sorption & volatilization Probable human carcinogen Sub-ppb groundwater quality standards in U.S. Adamson, David T., et al. "1, 4-Dioxane drinking water occurrence data from the third unregulated contaminant monitoring rule." Science of the Total Environment 596 (2017):