Applicability of an activated carbon felt strip on a NAPL FLUTE TM (FACT) for DNAPL characterization

Transcription

1 Applicability of an activated carbon felt strip on a NAPL FLUTE TM (FACT) for DNAPL characterization Monique Beyer 1, Gry S. Janniche 1, Carl Keller 2, Anders G. Christensen 3, Henriette Kerrn-Jespersen 4, and Mette M. Broholm 1 1 DTU Miljø, 2 Flexible Liner Underground Technologies, LLC, 3 Niras, 4 Region Hovedstaden

2 Outline FACT liner and expectations Sorption Processes on carbon felt Overview of experiments (analysis, handling of the FACT & interpretation of data) Fieldwork Results Summary Conclusion 2 DTU Miljø, Danmarks Tekniske Universitet

3 FACT liner & Expectations FACT = combination of: dye striped hydrophobic tubular covering - NAPL FLUTe Strip of activated carbon felt Expectation - high discreet samples, determining DNAPL presence - differenciate high aqueous conc. & DNAPL 3 DTU Miljø, Danmarks Tekniske Universitet

4 NAPL FLUTe Activated carbon felt Aluminum foil Water filling Sorption processes on carbon felt Unsaturated zone Free phase Pore air (Aqueous) Saturated zone Aqueous chlor. solvents DNAPL 4 DTU Miljø, Danmarks Tekniske Universitet

5 Overview of experiments Lab experiments Field work step Extraction/ Desorption Aim/results obtained extraction method(s), equilibrium times Information used for field work Analysis of carbon felt Adsorption Equilibrium times application time in field Discretization long and short samples Size of samples Staining Sorption in different phases 5 DTU Miljø, Danmarks Tekniske Universitet Different staining at Interpretation of field work different concentr. samples concentration range corresponding concentration in matrix

6 Analysis of carbon felt - Extraction Water vs pentane Water low recovery < 1% preservation Pentane good recovery ~ 100% analysis 6 DTU Miljø, Danmarks Tekniske Universitet

7 % of initial mass adsorbed Application/handling -adsorption 120 around 10 mg/l PCE, adsorption on big and small carbon strip time [h] ratio 3.6 PCE/felt ratio 3.0 PCE/felt application time of FACT in soil set to: >24h 7 DTU Miljø, Danmarks Tekniske Universitet

8 Interpretation of results Different phase exposure PCE saturated air ~45 mg/g on carbon felt a drop of PCE ~3 mg/g on carbon felt PCE saturated solution ~ 0.7 mg/g on felt Diffusion controlled sorption Staining DNAPL saturation 8 DTU Miljø, Danmarks Tekniske Universitet

9 Fieldwork 1. cut liner open & PID measurement 2. cut carbon strip in half, lay liner flat & observe staining 3. sampling accoring to PID, staining or geological data 4. samples in water (in field)+ pentane (in lab) 9 DTU Miljø, Danmarks Tekniske Universitet

10 Fieldwork 700 samples in chalk and clay till - Clay till: 24h, up to 8m FACT liners, 2 to 10cm discreet - Chalk: 48h, up to 13m, 2 to 10cm discreet not entirely sampled 10 DTU Miljø, Danmarks Tekniske Universitet

11 Results Clay till: high concentrations up to 120 mg/g on carbon felt, DNAPL staining Chalk: lower concentraions up to 5 mg/g on carbon felt, light staining Staining: different staining obvious (1) & light (0.5) 11 DTU Miljø, Danmarks Tekniske Universitet

12 Results & discretization + good correlation of PID, staining and concentration data + representative concentration results with less dicreet samples 12 DTU Miljø, Danmarks Tekniske Universitet

13 Summary Clay till unsaturated zone: high conc. on felt (up to 120 mg/g) & DNAPL staining Lab: highest PCE conc. (40 mg/g) in PCE saturated air Chalk saturated zone: lower concentrations (up to 5 mg/g), light staining Lab: medium concentration (3 mg/g) a drop of DNAPL Lab: in saturated PCE solution 0.7 mg/g PCE on carbon Diffusion controlled adsorption difference between unsaturated and saturated zone 13 DTU Miljø, Danmarks Tekniske Universitet

14 Conclusion + Combination PID, staining, carbon = very useful tool (discretization & interpretation) - no direct backcalculation to aquifer concentration + however: trends and range explainable due to diffusion controlled processes + simple sample handling ( conservation in water) + discreet method + good correlation also to soil data 14 DTU Miljø, Danmarks Tekniske Universitet

15 Thanks for your attention! Questions??? 15 DTU Miljø, Danmarks Tekniske Universitet