Using Sensors to Monitor Biodegradation in the subsurface

Transcription

1 Using Sensors to Monitor Biodegradation in the subsurface Dong Li Chevron Energy Technology Company September 19, 28 Chevron 25 DOC ID

2 Why Use Sensors? Diurnal Changes in Pressure and Concentration Concentration (ppm) Pressure (.1" H2O) Combustable gas concentration near surface Differential pressure between - 4 fbg Time (day) Chevron 27 Sensors 2

3 What is the Problem? Hydrocarbons degrade readily in most environment Aeration CO 2 O 2 Aerobic Screen O 2 CO 2 Groundwater HC Anaerobic Chevron 27 Sensors 3

4 Why Monitor Biodegradation? Hydrocarbon biodegradation process is normally not visible There is no easy way to determine: Is it working? How long will it take? Any Process adjustment? aeration rate, water, nutrients, When can we stop? Monitoring is the key to bioremediation success Chevron 27 Sensors 4

5 What to Measure? Physical Parameters: Temperature, Pressure, Flowrate, Groundwater Level,... Chemical Parameters (for Petroleum HC): TPH, BTEX, VOC, ph, O 2, CO 2,... Biological Parameters: Nature and population of microorganisms, Biological activity indicators (O 2, CO 2,...) Chevron 27 Sensors 5

6 Parameters in Biodegradation of Petroleum Hydrocarbons O2 + HnCm CO2 + H2O Chevron 27 Sensors 6

7 How to Measure? Soil gas sampling and analysis Soil Probe Sensor in-well measurement Soil Gas Sensor Sensor in-soil measurement Chevron 27 Sensors 7

8 Hydrocarbon Sensors in Monitoring Well HC Concentration (ppm) Figaro 813 Adsistor Time (day) Chevron 27 Sensors 8

9 Soil Gas Concentration vs. Depth Profiles O2 (%), CO2 (ppm) Benzene (ppm) Oxygen (%) Carbon Dioxide (%) Benzene (ppm) Hydrogen (ppm) H2 (ppm) Depth (ft) Chevron 27 Sensors 9

10 Diurnal Changes in Oxygen Concentration 2 Oxygen (%) ft 3 ft 35 ft 4 ft 9/1/95 9/3/95 9/5/95 9/7/95 9/9/95 9/11/95 Time Chevron 27 Sensors 1

11 Hydrocarbon Concentration Measurements During Vapor Extraction HC Concentration (ppm) Adsistor-1 Adsistor-2 Probe-1 Probe Time of Aeration (day) * Li, D.X., Soil Bioremediation Monitoring Using Chemical Sensors, Proceedings on Field Analytical Methods for Hazardous Wastes and Toxic Chemicals, pp , January 29-31, 1997, Las Vegas, NV Chevron 27 Sensors 11

12 Biodegradation of Petroleum Hydrocarbons O2 + HnCm CO2 + H2O HC degradation rate can also be measured by the rate of oxygen consumption and carbon dioxide production. Chevron 27 Sensors 12

13 In-Situ Respiration Test Using Oxygen Sensors at Air Injection Rate of 8 CFM Oxygen Concentration (%) : 18: : 6: 12: 18: : 6: 12: 18: : Time of Day (hour) Oxygen 5 ft Oxygen 1 ft Oxygen 2 ft Chevron 27 Sensors 13

14 In-Situ Respiration Test Using Carbon Dioxide Sensor at Air Injection Rate of 3 CFM * O2 Readings (%) Pump on Pump off O2 Sensor CO2 Sensor CO2 Readings (ppm) 1: 11: 12: 13: 14: 15: 16: 17: 18: Time * Li, D.X. "In Situ Respiration Measurement Using A Subsurface Carbon Dioxide Sensor," Air & Waste Management Association, 96-FA158.2, Nashville, TN (1996) Chevron 27 Sensors 14

15 Biodegradation of Petroleum Hydrocarbons HC degradation rate can also be measured by the rate of heat generation O2 + HnCm CO2 + H2O Chevron 27 Sensors 15

16 Schematics of Sensor Installation T-3 Datalogger T-2 T-1 SVE inch Geoprobe HC Sensor 4 Sand Pack 6 8 Oxygen Sensor Temperature sensor 6 inch HS Chevron 27 Sensors 16

17 Temperature, Oxygen, and HC at T1 5 O2-2 ft O2-3 ft 4 4 O2-6 ft O2-7 ft T - 2 ft 3 O2 (%) / T (C) HC - 2 ft 25 2 HC /1 11/3 11/5 11/7 11/9 11/11 11/13 11/15 11/17 11/19 11/21 Chevron 27 Sensors 17 Time

18 Oxygen and Temperature at T2 T 18 ft 14 T 28 ft 8 13 T 38 ft T 5 ft 7 12 T 6 ft 6 Temperature (F) T 8 ft O2 4 ft O2 7 ft O /2/7 12/7/7 12/12/7 12/17/7 12/22/7 12/27/7 1/1/8 1/6/8 1/11/8 1/16/8 1/21/8 Time Chevron 27 Sensors 18

19 What is the Opportunities and Challenges? Sensors are available, reliable, and cheap. Installation and data collection are expensive. A large potential user base exist. Innovation is slow in a mature industry and a regulatory driven world. Chevron 27 Sensors 19