BIOREMEDIATION OF DIESEL-POLLUTED SOIL AND GROUNDWATER UNDER DENITRIFYING CONDITIONS

摘要

Contamination of water and soil resources with petroleum hydrocarbons is not a rare phenomenon nowadays. Microbial biodegradation has been carried out successfully reducing harmful concentrations of these pollutants to acceptable levels. In cases where oxygen availability limits microbial activity, alternative electron acceptors such as nitrate could be employed by microorganisms in biodegradative processes. We examined the effectiveness of anaerobic nitrate respiration to remediate water saturated soil and groundwater contaminated with diesel fuel. Microcosm systems were prepared with soil and water samples obtained from diesel-contaminated sites in San Juan, PR and Vega Baja, PR respectively and amended with different concentrations of nitrate. All systems were incubated stationary in the dark at 25oC and examined for total petroleum hydrocarbons (TPH), pH, nitrate concentration, total heterotrophs and denitrifier population density by most probable number (MPN). Significant degradation was observed in all nitrate- amended systems. Nitrate analysis showed consumption in all biostimulated systems. Results suggest that biostimulation of indigenous microbial communities using alternate electron acceptors such as NO3, could be an efficient strategy for the in-situ anaerobic bioremediation of hydrocarbon polluted saturated soil and groundwater in tropical ecosystems.