Use of a Bioreactor with an Indigenous Microbial Population to Remediate Hydrocarbons – Pilot Scale Test Conducted at Former Oilfield Landfill

+ Author to whom correspondence should be directed. Residual hydrocarbons adsorbed to the soil present challenges for remediation due to the difficulty in physically removing the residual product and the associated time and cost requirements to do so. In addition, site conditions of fractured bedrock limit both the technical and the cost effectiveness of traditional technologies, such as pump and treat, to address the issue due to difficulties in defining specific flow pathways and potentially significant volume of waters to be treated. The pilot-scale project tests the assumption that enhanced microbially mediated hydrocarbon degradation will be effective in remediating the Site. Ex-situ growth of a super-concentrated population of microbes indigenous to the pilot location was followed by injection into the subsurface. The effectiveness of the microbes in remediating the hydrocarbons was monitored. Once the microbial/nutrient plume has moved past downgradient monitoring points, groundwater from the nutrient/microbial plume will be collected and placed in a tank to be used as inoculum for growth of a higher concentration of microbes. Since the population has already been enhanced in numbers and acclimatized to the in-situ conditions, it is anticipated that the inoculum will result in a larger and more rapid growth of microbes to be re-injected into the ground. The effectiveness of the microbes in remediating the hydrocarbons and the type of microbial response will be monitored throughout the pilot scale