LIGHT HYDROCARBON RECOVERY USING A COMBINATION OF THERMAL AUGMENTATION AND BIOSLURPING

Transcription

1 LIGHT HYDROCARBON RECOVERY USING A COMBINATION OF THERMAL AUGMENTATION AND BIOSLURPING Presented at REMTECH 2004 Banff, Alberta October 14, 2004 By: In collaboration with:

2 TYPE OF SITE SUITABLE FOR THE DEVELOPMENT OF THE TECHNOLOGY GASOLINE LNAPL PLUME Extensive contamination Conventional P&T failed VER pilot study showed limited extraction rates

3 GENERAL OBJECTIVES Develop a soil heating technology Optimize the vacuum extraction technology in low permeability soils under soil heating conditions Study the effects of soil heating on bioremediation Control the migration of VOC under heating conditions in an urban environment

4 Application of the technology MASS OF HYDROCARBONS MASSE DE BTEX RÉCUPÉRÉE (KG) Total hydrocarbon recovery as a function of time MASSE CUMULATIVE D'HYDROCARBURES RÉCUPÉRÉS OBJECTIF REMEDIATION DE TRAITEMENT OBJECTIVE HEATING CONTRIBUTION VOLUME D'AIR POMPÉ (m 3 ) PUMPED VOLUMES

5 HEATING SYSTEM DESIGN OBJECTIVES Maximum temperature of the elements at around 250 o C; Control based on the temperature at the heating tubes Simple and robust design Rapid and easy installation and operation Low cost Can be operated under water level

6 Mechanisms of increase product recovery/destruction with heating vapor pressure increase exponentially Solubility and dissolution rate increase adsorption decreases diffusion rate increases viscosity decreases exponentially interfacial tension decreases biodegradation increases evaporation increases

7 Remediation mechanisms Increase of contaminant volatilization by soil heating combined with vapors extraction. Compound Boiling point o C Benzene 80 Toluene 111 Ethylbenzene 136 Xylenes 140 Vapor pressure (mm Hg) Benzene Toluene Ethylbenzene 0-Xylene m-xylene p-xylene Water Temperature (ºC)

8 Remediation mechanisms Increase of contaminant volatilization by soil heating combined with vapors extraction. Increase of biodegradation with temperature. Microbial activity rate multiplier The rate of microbial activity typically doubles for every 10ºC rise in temperature within the range of 10ºC to 45ºC Temperature (ºC)

9 In situ thermal techniques Electromagnetic methods Electrical resistance heating (3-phases or 6-phases) Radio frequency or microwave heating Hot fluid methods Hot air or water, steam Direct thermal methods Thermal conduction heating Electrical resistance heating (source: Radio frequency or microwave heating (source: _ chem /phc-15.asp)

10 In situ thermal techniques Electromagnetic methods Electrical resistance heating (3-phases or 6-phases) Radio frequency or microwave heating Hot fluid methods Hot air or water, steam (source:

11 In situ thermal techniques Electromagnetic methods Electrical resistance heating (3-phases or 6-phases) Radio frequency or microwave heating Hot fluid methods Hot air or water, steam Direct thermal methods Thermal conduction heating Heating element Contamination source Vapors and liquids extracted by VER Heating element

12 Thermal techniques Pros and cons Advantages Disadvantages Electric resistance Radio frequency or Microwave Steam, hot air, hot water Thermal conduction Simple and easy to use and to install; Allows a more uniform temperature increase in low permeability and heterogeneous soils; Steam is produced in-situ; Rapid soil heating. Rapid soil heating; Homogeneous dispersion of heat. Extensive know-how; Relatively inexpensive. Heating elements are simple and easy to operate; Generates even soil heating and is barely influenced by humidity changes; Wide heating range; Low cost; Safe method; Can be applied to a wide variety of soil types since there is no preferential heating pathways. Performance is moisture dependent; Requires continual input of water surrounding the electrodes; Potential geotechnical concerns in clay soils; Potential safety concerns. Requires expensive and sophisticated equipment for set-up and operation; Low efficiency in heterogeneous soils; Potential geotechnical concerns in clay soils. Limited by low permeability and non homogeneous soils; Low heating range. Heating is slower; Potential geotechnical concerns in clay soils.

13 Vapor extraction and monitoring are key elements in a soil heating process Compounds vaporized in heated zones condense on heated zones boundaries. Vapors must be collected promptly and effectively to avoid spread of contamination! To protect human health and safety. Vapors may penetrate underground utilities and buildings

14 PROJECT COSTS (CDN $) Partners Financial contribution Shell $ FPGSTE $ Golder Associates $ LTEE $ MCEBR $ Total $

15 Methodology Development ofthesoil heating system Laboratory tests In situ pilot tests Modeling Duration of the project: 3 years ( )

16 Hydrodynamic tests: Laboratory tests Tempe cells Permeability Low pressure retention tests

17 Laboratory test cell

18 Bench scale heating elements Length = 55 cm Watts, 240 Volts

19 MODELING OF THE HEATING AND BIOSLURPING PROCESS

20 Laboratory test results % de récupération de la masse totale % recovery of the total mass C2 : Essence, zone capillaire C3, C4 : Soltrol/toluène, zone capillaire C5, C6 : Essence, zone vadose intermédiaire C7 : Soltrol/toluène, zone vadose intermédiaire C9 : Essence + nutriments, zone capillaire 70ºC 50ºC 20ºC C2 C3 C4 C5 C6 C7 C9 Colonnes de bioaspiration Bioslurping columns

21 IN SITU TEST LOCATION

22 IN SITU TREATMENT UNIT

23

24

25

26

27 Installation of the heating elements (8m long; 3m heating; 1m under water table 0,15m dia, 5kW)

28

29 IN SITU PILOT TEST

30 IN SITU HEATING Temperatures at the elements Température (ºC) Élément /07/02 12/08/02 11/09/02 11/10/02 10/11/02 10/12/02 Time Temps

31 MODELING OF THE HEATING AND BIOSLURPING PROCESS Y (m) B CompFlow Simulation, Extraction à Chaleur, 130 jours 130 days A' Elev. (m) B' Elev. (m) y-distance (m) Temperature (degc) Section A-A' Section B-B' degc X (m) A x-distance (m)

32 Temperature in the soil at steady state ( o C) Set point temperature at the heating element Temperature in the soil as a function of temperature at heating elements

33 HYDROCARBON RECOVERY Mass Masse of hydrocarbons d'essence extraite extracted dans l'air in air (kg) (kg) Extraction without sans heating chauffage Y = 0,37x R 2 = 0, /04/02 18/06/02 07/08/02 26/09/02 15/11/02 Date (jj/mm/aa) Extraction avec withchauffage heating Y = 0,87x R 2 = 0,99

34 Results An average of 80ºC C was reached in the center of the cell after 5 months of heating at 200ºC; Hydrocarbons extraction rate increased by 135% with heating; Around 800 m 3 of soil were treated in 8 months.

35 PILOT TEST AT A FUEL OIL CONTAMINATED SITE UNDER A BUILDING

36 SITE DESCRIPTION UST leaked and free phase hydrocarbons were present in a small area underneath the building (300m²) Hydrocarbons are located in impermeable silty clay soils Previous pilot test using VER only showed that the free phase hydrocarbons were not mobile and it would take many years to remediate the site

37 PILOT TEST SCHEMATIC PS02-3 PS02-1 PO02-1 ECO2-1 ECO2-2 PS02-2 0,00 m Béton Point de suivi 0,20 m 0,40 m 0,50 m Remblai sable et gravier 0,70 m 0,95 m 1,00 m 1,10 m Argile silteuse 2,00 m

38 PILOT TEST RESULTS analyses chimiques d'eau brute et débit de liquides PILOT TEST TEMPÉRATURE ÉLÉMENT RESULTS 2 WATER DÉBIT D'EAU FLOW RATE BRUTE CUMULÉ C10-C50 (g) CUMULATIVE Débit WATER cumulé FLOW (L) RATE (L) START HEATING début chauffage faible débit liquides 13 juil 23 juil 02 août 12 août 22 août 01 sept 11 sept 21 sept 01 oct 11 oct TIME temps 1500 MASSE EXTRAITE CUMULÉE FREE PHASE HYDROCARBONS ANALYSES C10-C50 D'EAU BRUTE (mg/l) ET INTERPOLATION DISSOLVED PHASE HYDROCARBONS Température élément 2 (oc) Temperature

39 TCA remediation projet underneath a building SVE system already in place and operated since heating elements were installed to increase recovery and close the site 100 X increase in contaminant volatilization after 1,5 months of heating

40 Contaminants characteristics Contaminants Chemical Data Compound Boiling Point Vapour Pressure Aquous solubility ( C) (mm 20 C) (mg/l) 1,1,1-TCA ,1-DCA Acetone miscible DCE

41 TCA abiotic degradation half-life as a function of temperature Degradation half-life (days) Temperature ( o C)

42 Groundwater contaminant concentrations with time SVE ONLY SVE + HEATING Concentration (ppb) /24/1998 4/19/2001 1/14/ /10/2006 Date ACETONE 1,1-DCA 1,1,1-TCA

43 Groundwater contaminant concentrations with time SVE ONLY SVE + HEATING Concentration (ppb) /6/1999 4/19/2001 9/1/2002 1/14/2004 5/28/2005 Date ACETONE 1,1-DCA 1,1,1-TCA

44 Typical heating element Electrical junction box (XP) Vent To control panel Bolted top plate Welded steel flange Wires Liquid level Thermocouple Internal liquid level (adjustable) Electrical element (mobile) Contaminated zone Heat transfer oil 6" od. steel casing Welded steel plate

45 GENERAL OPERATING PARAMETERS Unique design of heating elements; rapid and easy installation at low cost. Electric equipment can be removed from the tubes to treat other portions of the site. The temperatures in the subsurface can reach 120 o C.

46 OPERATION PARAMETERS Temperature reached in the subsurface can exceed boiling points of the contaminants (e.g. benzene, TCE, TCA, DCA, etc.). Hydrocarbons in water will boil at a lower temperature than if there were as pure substances, and the negative pressures created by the VER will also decrease further the boiling point in the subsurface.

47 OPERATION PARAMETERS The increase in temperature will lower the viscosity and increase the mobility of the hydrocarbons under vacuum. The spread of heat in the subsurface is not dependent on soil permeability and this technology is appropriate for tight soils such as silts and clays 6-8 months are required to reach desired temperature in the subsurface and a typical remediation time frame is 6 to 18 months.

48 OPERATION PARAMETERS Typical heating elements are 3 to 5 KW. They cost approximately 4-8K$ including power supply, controls and installation in the ground (VER not included). Operational costs in electricity is approximately 55$/month/element. Heating elements are usually spaced 5 to 10 meters apart.

49 THANK YOU CHRISTIAN GOSSELIN GOLDER ASSOCIATES LTD. MONTREAL, QUEBEC Web: JILLIAN MITTON GOLDER ASSOCIATES LTD. CALGARY, ALBERTA Web: