Biopile bioremediation of petroleum hydrocarbon contaminated soils from a sub-Arctic site

Petroleum contamination of several hundred sites in the northern arctic and sub-arctic regions of Canada has occurred as a result of petroleum oil exploration and use of petroleum fuels for heating, transportation and electricity generation. Petroleum contamination can persist in the ground for long periods of time and be a source of long-term environmental contamination. Bioremediation is a non-disruptive and often cost-effective technology for remediation of petroleum-contaminated sites that involves the microbial degradation of hydrocarbon compounds. Biopiles allow for rapid ex-situ treatment of petroleum-hydrocarbon contaminated soils. Two pilot scale biopiles (300 kg soil each) were construct using soils contaminated with approximately 1 500 mg/kg total petroleum hydrocarbons (TPH) from Norman Wells, North West Territories. Both systems were supplied with oxygen to stimulate aerobic conditions, and monitored in an enclosed room maintained at a temperature of 15oC, the ambient summer temperature in Norman Wells. One biopile was amended with ammonium nitrate at a ratio of 100:5:1 (C:N:P) to determine the effects of nutrients on TPH biodegradation. The research showed that biodegradation occurred within both biopile systems. Analysis of the hydrocarbon fractions, TPH chromatograms, and oxygen consumption and carbon dioxide production supported biodegradation versus volatilization. However, an absolute confirmation of whether these loses were due to biodegradation (or to what extent) are not possible to be reported here. Analysis of the inorganic nitrogen and aggregation of the soils helped provide insight into the process of biodegradation in both biopile systems. Overall 42% of the total petroleum hydrocarbons were removed from the nutrient amended biopile and 38 % in the control biopile. For the F2 (>C10-16) fraction, both systems had less than 200 mg/kg soil and for the F3 (>C16-34) fraction around 700 mg/kg soil.