Advancements in ISS Technology: Long-Term Anaerobic Bioremediation of Contaminants at a MGP Site by Sulfate-Reducing Bacteria Following Combined ISCO/ISS Treatment

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Advancements in ISS Technology: Long-Term Anaerobic Bioremediation of Contaminants at a MGP Site by Sulfate-Reducing Bacteria Following Combined ISCO/ISS Treatment

Authors:
Daniel P. Cassidy (Western Michigan University)
Frank Dombrowski (WEC Energy Group)
Vipul Srivastava (EcoLogic & Sustainable Strategies)

Presenter:

Daniel P. Cassidy

Western Michigan University

Speaker Bio:

Daniel Cassidy is an Associate Professor in the Department of Geosciences at Western Michigan University and President of Perivallon, Inc. specializing in bench-scale treatability studies and trouble-shooting to support site remediation efforts. He received a Ph.D. in Civil Engineering from the University of Notre Dame. His educational background and work experience are in the areas of Environmental Engineering and Hydrogeology. With 37 peer-reviewed publications to his name, he has conducted over 400 bench-scale treatability studies and has been conducting applied research on Chemical Oxidation, Chemical Reduction, Stabilization/Solidification, and Bioremediation of Soils and Sediments and Groundwater for over 20 years.

Abstract:

Studies were done to investigate a novel remedy combining in situ chemical oxidation (ISCO), in situ stabilization/solidification (ISS), and anaerobic bioremediation in a single application. The primary purpose of these studies was to investigate the ability of native sulfate-reducing bacteria (SRB) to survive exposure to the highly oxidizing conditions associated with high doses of persulfate activated with ISS amendments. Subunits A and B of the dissimilatory sulfite reductase gene (dsrA and dsrB) were used to monitor the abundance of native SRB. Because microorganisms can be abundant in soil without being active, concentrations of products of contaminant degradation by SBR were also monitored. Sulfide, generated by use of sulfate as an electron acceptor by SRB, was measured in aqueous samples. The production of 2-naphthoic acid, a specific indicator of naphthalene degradation by SRB and other anaerobes, was also quantified and monitored over time. The results showed that the abundance of the native SRB decreased dramatically during the first week of treatment, due to the oxidizing conditions and high pH resulting from the ISCO/ISS treatment. However, the abundance of SRB recovered completely within approximately 20 weeks, exceeding background values. Sulfide concentrations increased temporarily, but were then reduced by precipitation with iron and other metals. Concentrations of 2-naphthoic acid increased steadily during the first 32 weeks after ISCO/ISS treatment, demonstrating that SRB degraded naphthalene. Concentrations of PAHs and BTEX were monitored over a three-year period, and clearly showed significant degradation by SRB. The results show that activating persulfate with common ISS amendments in a single application synergistically combined ISCO, ISS, and anaerobic bioremediation, and that native SRB can provide long-term biological polishing of residual contaminants after ISCO/ISS treatment of soils.

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http://mgpsymposium.com/agenda/

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