Bioremediation of gasoline‐contaminated soil using poultry litter

Abstract

Contaminated soil, excavated from around a leaking underground gasoline storage tank, is commonly subjected to thermal degradation to remove the gasoline. Bioremediation as an alternative treatment technology is now becoming popular. The important hydrocarbon‐degrading bacteria include Pseudomonas, Arthrobacter, and Flavobacterium. Poultry litter contains a large number of microorganisms, including Pseudomonas, as well as many inorganic nutrients and organic biomass that may assist in biodegrading gasoline in contaminated soil. During bioremediation of contaminated soil, microbial densities are known to increase by 2–3 orders of magnitude. However, bioremediation may result in an increase in the toxic characteristics of the soil due to the production of potentially toxic degradation intermediates. The objective of this research was to study the influence of the addition of poultry litter on the bioremediation of gasoline‐contaminated soil by quantifying the changes in the densities of microorganisms and by monitoring the toxi‐city of the degradation products. To differentiate between the effects of microorganisms, organic matter, and nutrients, the soil/gasoline mixture was treated with gamma‐radiated litter, water extract of the radiated litter, or untreated litter. There was an 80% increase in the number of bacteria upon the addition of untreated litter compared to the number of bacteria in the soil/gasoline mixture alone. This indicates that poultry litter may serve as a useful inoculum for bioremediation. The toxicity of the mixture to Photabactcrium phosphareum ("Microtox") did not change, indicating that toxic by‐products were not produced.