Smoldering Remediation of Coal-Tar-Contaminated Soil: Pilot Field Tests of STAR

Transcription

1 Supporting Information for: Smoldering Remediation of Coal-Tar-Contaminated Soil: Pilot Field Tests of STAR Grant C. Scholes 1, Jason I. Gerhard 2*, Gavin P. Grant 1, David W. Major 1, John E. Vidumsky 3, Christine Switzer 4, Jose L. Torero 5 1 Savron, 130 Stone Road West, Suite 2, Guelph, ON, Canada, N1G 3Z2 2 Department of Civil and Environmental Engineering, The University of Western Ontario, London, ON, Canada N6A 5B9. 3 DuPont Corporate Remediation Group,, Chestnut Run Plaza Building 730, Wilmington, DE, Department of Civil and Environmental Engineering, University of Strathclyde, 75 Montrose Street, Glasgow G1 1XJ, United Kingdom 5 School of Civil Engineering, University of Queensland, Brisbane, 4072, Australia. *Corresponding Author. Jason I. Gerhard: Geoenvironmental Restoration Engineering Dept. of Civil and Environmental Engineering The University of Western Ontario Spencer Engineering Building, Rm London, Ontario, Canada N6A 5B9 Tel (519) Fax (519) jgerhard@uwo.ca 8 pages, 4 figures, 2 tables S1

2 Method to Estimate the Mass of Coal Tar Destroyed The mass of coal tar destroyed was estimated via an approximate carbon mass balance using the combustion gases CO 2 and CO extracted and by applying, as a surrogate for coal tar, the chemical composition of naphthalene, frequently one of the dominant compounds remaining in present day coal tars 1 : M CoalTar M Napthalene M CO2 MW MW C CO CO2 C Nathpalene R M MW MW C CO (1) where M is the equivalent mass of coal tar destroyed; M is the mass of naphthalene CoalTar Napthalene destroyed; M CO2 is the mass of carbon dioxide measured in the vapor stream (calculated as the product of the carbon dioxide concentration and the vapor flow rate); M CO is the mass of carbon monoxide measured in the vapor stream (calculated as the product of the carbon monoxide concentration and the vapor phase flow rate); MW C, MW, and MW are the molecular weights of carbon, net carbon dioxide (i.e., observed minus background), and carbon monoxide, CO 2 CO respectively; and C R Nathpalene is the mass ratio of carbon to the molecular weight of naphthalene (equal to 0.94). The mass ratio of carbon to molecular weight was calculated for each of 29 compounds in the standard semi-volatile organic compound analytical suite (EPA method 8270C) and had an average value of 0.92 (stdev= 0.053, coefficient of variation of 5.7%). Vapor flow rates were calculated by multiplying the measured vapor velocities by the extraction duct cross-sectional areas, and correcting to standard conditions using the ideal gas law. S2

3 Figure S1: Confidence contours of Kriged temperature values (Day 8) from the Shallow (a) and Deep (b) Tests. Confidence values were calculated at each grid location as the standard error at a given location (a function of Kriged values and distance from known locations) divided by the Kriged value at that location. Calculations were performed using R statistical software and contour plots were generated in Surfer. S3

4 Figure S2: Shallow Test combustion gas (CO 2 and CO) concentrations in collected exhaust vapours. Combustion gases are used for mass destroyed calculations. S4

5 Figure S3: Deep Test combustion gas (CO 2 and CO) concentrations in collected exhaust vapours. Combustion gases are used for mass destroyed calculations. S5

6 Figure S4: Photographs of soils from before and after STAR in: (a) laboratory column treatability test (performed on shallow fill materials); (b) shallow field test soil cores; and (c) deep field test soil cores. Before soils contain significant quantities of moisture and coal tar NAPL. Post STAR Soils from after laboratory and field testing appear visibly drier and remediated. Concentration reductions for shallow and deep tests were 99.4, and 97.8% respectively. S6

7 Table S1: Shallow Test - VOCs in Vapor and Reaction Efficiency Sample Location Raw Exhaust Sample Volatile Organic Compound (µg/m 3 ) 1 1,2,4-Trimethylbenzene ,3,5-Trimethylbenzene 760 1,3-Butadiene Butanone 1100 Benzene Carbon disulfide 1000 Chloromethane 810 Dichloromethane 800 Ethyl benzene 2300 Heptane 1400 Hexane 1500 m&p-xylenes 5300 Naphthalene Octane 1100 o-xylene 2300 Pentane 2100 Styrene 1700 Toluene 7400 Total Volatile Organic Compounds Extraction Flow Mass Loss by Volatilization 2549 (m 3 /h) (kg/h) Coincident Coal Tar Destruction Rate 36.0 (kg/h) 2 Reaction Efficiency 99.38% Notes: 1 - Detected compounds only 2 - Calculated as average of 4 hour period around sample interval S7

8 Table S2: Deep Test - VOCs in Vapour and Reaction Efficiency Sample Location Average of Raw Exhaust Samples (n=2) Volatile Organic Compound (µg/m 3 ) 1 1,2,4-Trimethylbenzene 1,800 1,3,5-Trimethylbenzene 935 1,3-Butadiene 13 4-Ethyltoluene 575 Acetone 1270 Benzene 9,350 Chloromethane 65.5 Cyclohexane 170 Ethyl benzene 2,750 Heptane 225 m&p-xylenes 9,200 n-hexane 205 o-xylene 2,900 Styrene 47 Toluene 18,000 Total Volatile Organic Compounds 47,505 Extraction Flow 2549 m 3 /h Mass Loss by Volatilization 0.12 kg/h Coincident Coal Tar Destruction Rate (kg/hr) 5.56 kg/h 2 Reaction Efficiency 97.8% Notes: 1 - Detected compounds only 2 - Calculated as average of 4 hour period around sample interval S8