Monitoring enhanced anaerobic bioremediation at contaminated sites in the Netherlands

Transcription

1 Monitoring enhanced anaerobic bioremediation at contaminated sites in the Netherlands The use of specific monitoring tools Alette Langenhoff

2 Contents Objectives Field characterisation Enhanced bioremediation system Field results Conclusions?? 2

3 Objectives Treatment of contaminated area Focus on source zone, plume will be treated afterwards Use of specific monitoring tools to demonstrate Enhanced Natural Attenuation ydrogen measurements at the site Compound Specific Stable Isotope Analyses Molecular analyses (DNA) 3

4 Field characterisation Former dry cleaning in the city of the ague, the Netherlands Contamination with PCE from , due to leaking sewage system At present; mainly DCE and VC PER PCE TCE TRI DCE CIS VC Ethylene Etheen

5 Top view W. Royaardsplein the ague 2-6 m bgs m bgs 6-10 m bgs m bgs cis-dce and VC contours 5

6 Field characterisation Groundwater table 2 V gw 20 m bgs 6

7 Field characterisation Source zone Max. concentrations DCE 8,000 µg/l VC 5,700 µg/l Contaminated soil volume 35,000 m 3 Boundary conditions Decrease in groundwater table max 0.3 m NAP (draught damage) Reach target value of 2.5 µg/l VC within 10 years 7

8 Enhanced bioremediation system Pump & Treat Unit 1 Extraction Extraction Unit 2 8

9 Enhanced bioremediation system Infiltration Pump & Treat Unit 1 Extraction Extraction Unit 2 9

10 Enhanced bioremediation system 10

11 Enhanced bioremediation system 11

12 Enhanced bioremediation system; installation 12

13 Enhanced bioremediation system; installation Unit 1; Infiltration Unit 2; Air stripper 13

14 Enhanced bioremediation system; installation Unit 1; Infiltration Unit 1 Unit 2; Air stripper 14 Unit 2

15 Enhanced bioremediation system Combination of Pump & Treat, and Infiltration Source zone Reductive dechlorination by addition of electron donor Acetic acid Lactic acid PER PCE TCE TRI DCE CIS VC Ethylene Etheen

16 Field results, source zone 22,500 m 3 of groundwater infiltrated during 6 months; 19 ton of electron donor added; mix of lactate and acetate (4,500 kg DOC, 185 mg/l) 16

17 Field results, source zone Concentrations in monitoring well Estimate Cis Estimate VC Target value VC Cis real VC real Concentration (µg/l) Remediation in line with expectations Remediation stagnates Time (days) 1 17

18 Field results, source well 35 concentration (µg/l) cis-dce VC Ethene time (days) 18

19 Field results, plume well 48 concentration (µg/l) cis-dce VC Ethene time (days) 19

20 Field results, percentage of dechlorination Good indication for dechlorination process Based on the ratio between parent and daughter compound To be calculated as follows (PCE as parent compound) [TCE]+2[DCE]+3[VC]+4[Ethylene]+4[Ethane].. 4 ([PCE]+[TCE]+[DCE]+[VC]+[Ethylene]+[Ethane] 100% 20

21 Field results, percentage of dechlorination 100 Percentage of dechlorination well 35 well time (days) [TCE]+2[DCE]+3[VC]+4[Ethylene]+4[Ethane].. 4 ([PCE]+[TCE]+[DCE]+[VC]+[Ethylene]+[Ethane] 100% 21

22 Field results, ydrogen ( 2 ) Conditions suitable for dechlorination? Electron Acceptor Process methanogenesis? SO 4 2- reduction DCE/VC reduction? PCE/TCE reduction Fe 3+ reduction NO 3- reduction O 2 reduction concentration (nm) 22

23 Field results, ydrogen ( 2 ) < 0.1 Nitrate reduction 0,2 to 0,8 Fe(III)-reduction 1 to 4 Sulphate reduction 1 Reductive dechlorination 5 to 20 Methanogeneses 5,0 4,0 well 35 well 48 2 (nm) 3,0 2,0 1,0 0, time (days) 23

24 Compound specific stable isotope analyses Which isotopes? Mainly 12 C/ 13 C and 37 / 35 Other elements: S, O Why? Biological degradation; light isotope faster Enrichment of 13 C -isotopes in residual parent compound (decrease in δ 13 C) Dilution, adsorption and transport; no preference 24

25 Compound specific stable isotope analyses Biological degradation; light isotope faster Volatilisation; light isotope faster Dilution, adsorption & transport; no effect 25

26 Field results, Stable isotope analyses 10 well well C/ 12 C (promille) ,2-DCE VC 13 C/ 12 C (promille) ,2-DCE VC time (days) time (days) 26

27 Field results, DNA analyses (molecular detection) Detection on molecular level (e.g. DNA or RNA) Detection based on specific genes Gene: part of DNA with information of a specific capacity e.g. an enzyme or a type of bacteria Bacteria Gene DNA 27

28 Field results, DNA analyses Dehalococcoides ethenogenes numbers w ell 35 w ell time (days) 28

29 Field results, source concentration (µg/l) well 35 cis-dce VC Ethene 2 (nm) 5,0 4,0 3,0 2,0 1,0 well 35 well time (days) 0, time (days) 13 C/ 12 C (promille) well 35 1,2-DCE VC numbers well 35 well time (days) time (days) 29

30 Field results, plume concentration (µg/l) well 48 cis-dce VC Ethene 2 (nm) 5,0 4,0 3,0 2,0 1,0 well 35 well time (days) 0, time (days) 13 C/ 12 C (promille) well 48 1,2-DCE VC numbers well 35 well time (days) time (days) 30

31 Conclusions System operation: Successful infiltration of substrate without clogging (22,500 m 3, 4,500 kg DOC, 185 mg/l) Adapted extraction regime, due to restricted groundwater levels and other groundwater extractions in the area; Flexible infiltration/extraction regime needed; Spreading of electron donor in source zone, except deeper layer in plume. 31

32 Conclusions Dechlorination takes place in source zone: Significant decreases in concentrations of cis-dce (1,485 to 98 µg/l) and VC (3,021 to 55 µg/l); Suitable conditions for dechlorination (0.9 < 2 < 10.2 nm and DOC 126 to 170 mg/l); Fractionation of cis-dce and VC, 20 and 15 promille; Increase of Dehalococcoides ethenogenes (> 10 6 ). 32

33 Conclusions Dechlorination less profound in plume Initially pump and treat, followed by dechlorination Concentrations decrease slightly; Major concentrations in deeper aquifer (> 8 m bgs); Minor increase of 2 concentrations (1.1 nm); Initial fractionation of cis-dce and VC; but no further fractionation between day Decrease of Dehalococcoides ethenogenes since start (< 10 3 ). 33

34 Acknowledgement Willem avermans Gerard Borggreve Municipality The ague Michiel Pluim Sjef Staps arry Veld Andre Cinjee ans Brouwer Alette Langenhoff 34