Workshop SA4.

Clean it up with bacteria – Bioremediation and monitored natural attenuation (MNA) of chlorinated solvents: from source areas to dilute plumes

Sunday, 8 September, 2019

Instructors: Heather Rectanus, Chuck Newell, Ryan Wymore

Summary

In situ bioremediation (ISB) has been applied at hundreds to thousands of sites contaminated with chlorinated solvents, including many applications in DNAPL source areas in the past two decades.  ISB has several advantages compared to other technologies when applied in source areas because of two primary factors: 1) enhanced dissolution and/or desorption of nonaqueous- and/or sorbed-phase contaminant mass and 2) biological degradation to nontoxic end products. The ability of ISB to enhance the dissolution and desorption of nonaqueous-phase contaminants to the aqueous phase, where they can be degraded by the microbial population, is what makes the ISB technology applicable to DNAPL source zones. This can result in faster remediation compared to traditional technologies that are limited by the NAPL dissolution rate (i.e., groundwater extraction).

Another challenge at chlorinated solvent sites is the remediation of the large, dilute plumes that can emanate from source areas. It is often not practical or even possible to actively treat these plumes using the aggressive ISB approaches that are necessary for source areas.  Because of this, other treatment strategies are often needed.  These can include passive treatment using strategically placed “biobarriers” and/or implementation of monitored natural attenuation (MNA).  The emergence and increased regulatory acceptance of advanced monitoring tools has resulted in the ability to document the occurrence of multiple MNA mechanisms.

This training course will summarize the basic mechanisms that allow for ISB to be applied in DNAPL source areas.  It will also provide information that represents the state of the practice for ISB of chlorinated solvents in both source areas and dilute plume applications (i.e. biobarriers).  Using data mining and research tank experiments, the expected performance of bioremediation and MNA projects will be presented. Finally, the ability for bioremediation to control low-strength matrix diffusion sources of contamination via a “sustained treatment” process will be explained and demonstrated with long-term performance data from actual sites.

Who should attend?

Environmental consultants, site owners, and environmental regulators involved with sites where ISB is being considered or has been implemented will benefit from this course.

Detailed Course Outline & Schedule