Petrox and Methylnaphthalene Bioremediation Site Summary
Petrox microbes accelerated BTEX and methylnaphthalene bioremediation at a former fueling station in Florida. After a leaking tank underground storage tank (UST) was removed, the consultants injected Petrox micorbes into the groundwater. A temporary well showed high concentrations of BTEX, methylnaphthalene isomers, and total recoverable petroleum hydrocarbons (TRPH) in the former tank location. A permanent monitoring point replaced the temporary well. Since the contaminants were not detected outside of the UST cavity, the treatment focused on the cavity and its proximity. The consultant injected Petrox into the ground water through 12 direct-push injection points in and around the UST cavity. They used approximately 10 gallons of Petrox solution at each of the injection points in August 2001. After one injection of Petrox, petroleum hydrocarbons concentrations decreased below detection levels in the UST cavity. Please refer to the table below for the ground water monitoring results.
Persistence in Soil and Low Ground Water Concentrations
Methylnaphthalene and naphthalene persist in soil after other volatile components of fuels are gone. The persistence comes from to their relatively high affinity for adsorption to soil and relatively low water solubility. These factors account for the common rebound of ground water concentrations. Despite high concentrations of naphthalene and methylnaphthalene in soil near the ground water table, often the dissolved concentration in the ground water is very low. The accumulation of these compounds at the water table causes a problem for remediation. Frequently after ground water remediation, seasonal fluctuation of the water table through the contaminated vadose zone recharges the concentrations of these compounds. This results in seasonal fluctuation in the ground water concentrations.
The microbes in Petrox accelerate the remediation because they product an extracellular biosurfactant that desorbs the methylnaphthalene to make it available for extraction or for in situ bioremediation. At this site, the contaminated soil was removed to the water table, so concentrations did not rebound after the initial ground water remediation. At other sites where Petrox bioremediation addressed methylnaphthalene or naphthalene, the consultant combined bioremediation with extraction. The combined technologies removed the contamination flushed from the soil in addition to the bioremediation. Click here to view case studies from other sites.