Objective:

Enhanced in situ bioremediation (EISB) is increasingly being used for the remediation of chlorinated solvents and recalcitrant chemicals (e.g., perchlorate, RDX) in groundwater. Often, the repeated addition of nutrients creates conditions within the injection well screen and the surrounding filter pack that favor microbial growth and biofilm formation, which in turn results in a loss of well efficiency. When well efficiency declines below an acceptable level, physical well rehabilitation coupled with aggressive chemical shock treatment is typically deployed. Well rehabilitation is labor-intensive and can diminish the feasibility of EISB compared to other technologies by significantly increasing operating costs. The objective of this project is to evaluate several biofouling control technologies that will minimize well efficiency losses and the need for well rehabilitation as well as improve the feasibility of EISB.

Technology Description:

Biofouling control technologies typically attempt to inhibit or inactivate biofilm-producing bacterial populations by applying oxidizing biocides or concentrated acids, displacing the biomass by physical means, or destabilizing the exopolysaccharides in the biofilm matrix using surfactants, dispersing agents, or chelating agents. In this project, five biofouling control agents will be tested in an in-situ field biostimulation system targeting either chlorinated ethenes or perchlorate at a Department of Defense (DoD) facility. Key project tasks include: (1) develop a White Paper reviewing the current state of biofouling control technologies, including the applicability of conventional biofouling controls for in-situ application, case studies, regulatory acceptance, and a comparative analysis of the relative advantages and disadvantages of each technology; (2) evaluate the field-scale performance and cost of multiple biofouling control technologies, including the possibility of adverse geochemical or microbiological interactions and inhibition of the desired biodegradation processes; and (3) develop design data and guidance to facilitate application of biofouling controls by DoD remedial project managers (RPM).

Expected Benefits:

This project will generate cost and performance data for multiple biofouling controls that may be readily implemented at DoD facilities with varying geochemical conditions and infrastructure. A Guidance Manual will be produced for use by DoD RPMs and EISB practitioners in selecting and deploying successful preventative biofouling control measures for EISB remediation systems, resulting in significant Operations and Maintenance (O&M) cost savings. Given that hundreds of perchlorate- and chlorinated solvent-impacted DoD and related sites are expected to employ EISB in upcoming years, the development of safe and reliable preventative biofouling controls that eliminate or minimize the need for well rehabilitation is expected to represent cost savings in the $10 millions to DoD. (Anticipated Project Completion - 2008)

Principal Investigator:
Mr. Evan Cox
GeoSyntec Consultants
130 Research Lane, Suite 2
Guelph, Ontario N1G 5G3
Telephone: (519) 822-2230
Fax: (519) 822-3151
E-mail: ecox@geosyntec.com