Formatted Title
Use of Cutting-Edge Molecular Microbial Technologies to Drive a Successful, Novel, Anaerobic EISB Bioremediation
Background/Objectives
Background/Objectives. A comprehensive biogeochemical assessment was performed at a historical refinery that had produced liquefied petroleum gas, gasoline, fuel oil, and asphalt over the past century before transitioning to its current role as a petroleum products terminal. The primary objective was to determine if enhanced in situ bioremediation (EISB) would be successful at reducing benzene concentrations under the anaerobic conditions at the site, and if so, how to maximize its effectiveness. This biogeochemical assessment merged traditional geochemical parameters with a unique consortium of innovative molecular biological tools.
This project is significant for two reasons. First, it demonstrates a modern method to evaluate EISB at a site impacted by multiple constituents of concern (COCs) including legacy benzene, a compound that is generating a resurgence in concern as the primary regulatory driver in many areas across the USA. Second, the information gleaned from these assessments was then used to establish a successful field-scale EISB pilot study that was the first of its kind, globally.
Approach/Activities
Approach/Activities. In addition to examining a traditional suite of site geochemistry and COC data, stable isotope analyses were used to confirm and track benzene biodegradation. Furthermore, a series of next-generation molecular sequencing arrays were performed to directly monitor the entire indigenous microbial population as well as the full suite of metabolic functions being performed by this community. Finally, a series of investigations into the indigenous Deltaproteobacterium sp. ORM-2 population were conducted. ORM-2 is a microbe that has been recently identified as critical for successful benzene biodegradation under highly anoxic conditions. Together, these laboratory studies resulted in a site-specific profile of the current status of indigenous benzene biodegradation. Information from these studies was used to then develop the first known EISB pilot study using the in situ enhancement of a specific benzene-biodegrading microbial population at a highly anaerobic location such as this.
Results/Lessons Learned
Results/Lessons Learned. Benzene concentrations have decreased by up to 99% as a result of the novel EISB injections. This project dramatically underscores the benefit of performing often-neglected efforts during the planning stages of an EISB field-scale pilot test. Traditionally, a pilot study bases its approach on bioremediation estimates and assumptions taken from other locations. If these presumptions do not match actual site conditions, however, a pilot study can easily fail. However, this project demonstrates that the strategic combination of traditional site monitoring methods and cutting-edge molecular technologies can provide invaluable information about indigenous microbial activities, maximizing the potential for successful EISB of targeted and recalcitrant COCs. This presentation will outline this process, as well as results of the unique field-scale bioaugmentation pilot-study that reduced legacy contaminants at a historical site by up to 99%.