Empirical Models Estimating Carbon Dioxide Accumulation in Two Petroleum Hydrocarbon–Contaminated Soils

ABSTRACT

Bioremediation is a popular method in degrading diesel fuel contaminants from soil. Bioremediation can be enhanced by estimating the effect of important environmental parameters on microbial activity. Respirometry was used to develop empirical models describing the effects of temperature, moisture, nitrogen, and phosphorus concentration on microbial activity in a diesel-contaminated soil from Wyoming. Carbon dioxide (CO₂) data were analyzed using a base equation where its coefficient values were functions of each parameter. Two physiologically different groups of microorganisms were identified from the results under different operating temperatures. The empirical correlations were combined into one model and this model was tested against a hydrocarbon-contaminated soil collected from a site in Egypt with similar history of contamination. The predicted CO₂ evolution agreed well with the actual data obtained from the Egyptian soil samples, showing a sound predicting power of the empirical model for petroleum hydrocarbon biodegradation. Overall, the empirical correlations developed from the respirometric data provide a method to describe microbial activity in diesel-contaminated soils.

KEYWORDS:

• CO₂ efflux
• diesel biodegradation
• modeling
• petroleum spill
• respirometry

ACKNOWLEDGMENTS

Primary Financial support for this research was provided by the United States Department of Energy (DoE) through Western Research Institute's (WRI's) Cooperative Agreement No. DE-FC26-98FT40322 with DoE. Any opinions, findings, conclusions, or recommendations expressed herein are those solely of the authors.