Topic Area: 7a. Tools for Site Assessment and Bioremediation Monitoring

Formatted Title:

Benefit of the Integrated Molecular-Isotopic Approach in Environmental Remediation Processes

Background/Objectives:

The case studies discussed show the strength of applying the integrated molecular (Biological Molecular Tools [BMTs]) - isotope (Compound Specific Isotope Analysis [CSIA]) approach to the various stages of an environmental bioremediation process, i.e. i) characterization of the biodegradative potential, ii) laboratory-scale tests, iii) pilot-scale tests and iv) monitoring of enhanced natural attenuation (ENA), as an aquifer restoration intervention, if foreseen by the remediation plan of the site. Integration makes it possible to reduce experimental uncertainties in all the phases just described and to contain times and costs of the remediation process.

Approach/Activities:

As stated, to gain the last two goals indicated it is necessary to go through the four phases previously detailed. The main experimental evidence (i.e., analysis of ¹³C-CSIA and ³⁷Cl-CSIA of the target compounds and quantification of degrading genes [qPCR: quantitative Polymerase Chain Reaction] and microbial populations [Next Generation Sequencing and qPCR]) belonging to each of these remedial process phases will be presented in detail, through the discussion of at least one case study:

1) characterization of the biodegradative potential sites contaminated by ethylenes and/or co-presence of ethylenes and ethanes – anaerobic conditions;

2) laboratory-scale study a) testing of various possible soil amendments (i.e., molasses selected following the characterization of the bacterial community structure vs. sodium lactate) to evaluate the most effective for an ENA treatment of a site mainly contaminated by ethylenes b) use of a hybrid ISCR (In Situ Chemical Reduction) and ENA approach in a site contaminated by ethylenes and 1,2-dichloroethane (1,2-DCA) – anaerobic conditions;

3) lessons learned following the application of a pilot-scale ENA test in a site contaminated by benzene, monochlorobenzene and nitrochlorobenzenes -aerobic conditions;

4) application of the integrated approach to all the four phases, up to the full remedial plan, to a site mainly contaminated by 1,2-DCA. Two years after the conclusion of the remediation, the integrated approach was also used to verify the persistence of the stimulated conditions.

Sergio Gil-Villalba

Affiliation

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(Group 1, Poster Board #51) Benefit of the integrated molecular-isotopic approach in environmental remediation processes