Biodegradation of petroleum compounds in soil by a solid-phase circulating bioreactor with poultry manure amendments

Petroleum compounds account for the vast majority of contaminants in soils. Bioremediation is a widely accepted strategy in degrading these contaminants. This study demonstrates the effectiveness of nitrogenous nutrient (nitrogen) amendments in enhancing biodegradation of petroleum contaminants in soil by using a solid-phase circulating bioreactor (SCB). In a bench-scale SCB, total petroleum hydrocarbon (TPH) concentration (~5000 mg kg(-1)) in soil decreased 92% within 15 days. In a scaled-up SCB system containing approximately 120 kg petroleum-contaminated soil (TPH at approximately 125,000 mg kg(-1)), a degradation rate of 635 mg kg(-1)d(-1) was obtained from the poultry manure-amended treatment during a 200-day period of operation. Treatments with the same amount of nitrogen (as ammonium nitrate) attained a TPH degradation rate of 469 mg kg(-1)d(-1) during the same period. Control SCB unit, which was maintained under the same aerobic conditions but not amended with nitrogen, had a TPH degradation rate of 273 mg kg(-1)d(-1). Results from this study indicate that SCB can achieve significantly higher degradative rates than conventional landfarming (reported rates < 150 mg kg(-1)d(-1)) and poultry manure appears to be a preferred nitrogen amendment that can further enhance the biodegradation of petroleum contaminants in soils.