Comparison of Various Extraction Methods for Petroleum Hydrocarbons (PHC) in Soils and in Drilling Waste

Transcription

1 Comparison of Various Extraction Methods for Petroleum Hydrocarbons (PHC) in Soils and in Drilling Waste John Ashworth 1 & Ron Minks 2 1. Director, Soil Science; ETL 2. Director of Calgary Operations; ETL

2 Alberta s drilling waste disposal guidelines (G-50, 1996) are currently being revised After drilling waste disposal, parameters must fall within scientifically determined, risk-based end-point soil quality values The end-points for petroleum hydrocarbons (PHCs) are geared to the Canada-Wide Standard Method of soil analysis (CCME)

3 Upstream Petroleum Guidelines (Hydrocarbons) CCME method. Fine, surface, agricultural soil Fraction % 260 mg/kg C6-C10 Fraction % 900 mg/kg C10-C16 Fraction % 800 mg/kg C16-C34 Fraction % 4,000 mg/kg C34-C50

4

5 Treatability Test #2 (Fertilized) - Results to Feb ,000 1,800 1,600 1,400 Concentration (mg/kg) 1,200 1, PHC F2 (mg/kg) PHC F3 (mg/kg) PHC F4 (mg/kg) Months

6 Soils Used in the CCME Validation Study Soil % sand % clay % moisture texture organic matter A clay loam 1 % B sand 2 % approx. C loam 12 % approx. D clay loam 9 % D clay loam 9 %

7 Two Extraction Studies CCME CWS PHC extraction of soils 5 methods 5 soil types 7 spikes each = a lot of data!

8 Two Extraction Studies Drilling waste comparison using CCME benchmark extraction vs cold shake extraction Use shake method to pre-determine hydrocarbon loading for G-50 purposes

9 Soil Extraction Techniques: Soxhlet Soxtec Cold shake Tumbler Sonic bath

10 Soxhlet - EPA 3540 CCME PHC benchmark Named after Franz Soxhlet ( ), a German food analyst Series of distillations/cycles Total extraction time: hours

11 Soxtec - EPA 3541 Rapid extraction by Soxtec is the 21st century, automated version of Soxhlet extraction Total extraction time: 1-2 hours

12 Cold Shake Wrist-action shaker Total extraction time: 1 hour

13 Tumbler TCLP-type extraction (EPA 1331) using solvent End-over-end rotation/tumble Total extraction time: 2 hours

14 Sonic Bath - EPA 3550 Extract with ultrasonic waves in a water bath Total extraction time: 10 minutes

15 GC/FID System Carrier gas flows into the injector, through the column and then into the detector Sample extract is injected into the heated injection port and vaporized Hydrocarbons are separated through a column based upon boiling points Each compound is detected by the FID

16 Comparison to Benchmark Soxhlet defined as benchmark extraction for CCME PHCs Each soil type spiked with diesel and SAE 30 motor oil - 7 replicates Recoveries measured are relative to Soxhlet

17 F2 (C10-C16) % Recovery Soxhlet Soxtec Shake Tumble Sonic bath 20 0 Clay Loam, 9%OM Clay Loam, 9% OM 20% H2O Clay Loam, < 2 %OM Sand Loam

18 F3 (C16-C34) % Recovery Soxhlet Soxtec Shake Tumble Sonic bath 20 0 Clay Loam, 9%OM Clay Loam, 9%OM 20% H2O Clay Loam, < 2 %OM Sand Loam

19 F4 (C34-C50) % Recovery Soxhlet Soxtec Shake Tumble Sonic bath 20 0 Clay Loam, 9%OM Clay Loam, 9%OM 20% H2O Clay Loam, < 2 %OM Sand Loam

20 Recovery Summary - Compared to Soxhlet Recovery Soxtec within 10% Cold shake method recovery ranges from 42%-111% Tumble method recovery ranges from 66%-107% Sonic bath method recovery ranges from 56%-100% No data available for ASE or microwave

21 Bio-availability (aging; sequestration) Effect of organic matter (a form of partitioning) Effect of texture, especially sorption on clays Other suggested factors: encapsulation in precipitates; ph; temperature

22 Comparison Using Real-World Samples Random sample selection (approx. 200) Extract duplicate sample using Soxhlet and Soxtec Regression of data onto chart (Lloyd Hodgins)

23 F2 (C10 to C16) Soxhlet y = x R 2 = Soxtec

24 F3 (C16 to C34) Soxhlet y = 0.912x R 2 = Soxtec

25 F4 (C34-C50) Soxhlet y = x R 2 = Soxtec

26 We also analyzed two drilling wastes for total extractable hydrocarbons (TEH) using the cold shake method and compared recoveries to the CCME benchmark method Drilling Waste % Moisture DWA 28% DWB 58% Diesel spike ranged from 2,000 4,000 mg/kg

27 % TEH Recovery % Recovery 140% 120% 100% 80% 60% 40% 20% 0% CCME PHC Cold shake w/ hexane/acetone Cold shake w/ hexane DW-A DW-B

28 Summary - Soils Soxtec is equivalent to CCME benchmark Soxhlet method Other alternative methods have various challenges to meet equivalency Bioavailability of PHCs in soil an issue for recovery Ensure ongoing equivalency using PT samples (CAEAL) and real-world samples

29 Summary - Drilling Wastes Cold shake extraction works well for drilling wastes compared to CCME benchmark soxhlet method Hexane alone works well Drilling wastes do not display the bioavailabiltiy issues found in soils Receiving soils will require CCME PHC method

30 Thank you!