The unconventional oil and gas boom, facilitated by technical advances in horizontal drilling and hydraulic fracturing, is bringing energy production activities closer to densely-populated areas and raising concerns about the potential contamination of drinking water resources. Potential shallow pathways that may result in groundwater contamination by fracturing fluids include surface spills and compromised well integrity. Peer-reviewed data on the fate and transport parameters of many hydraulic fracturing fluid organic compounds are limited, and possible co-contaminant interactions between the constituents in fracturing fluids or produced waters could influence their fate in the environment in the event of an accidental spill or release. Possible co-contaminant interactions include inhibition of biodegradation by biocides, which are commonly-used additives in fracturing fluids. The objective of our study was to assess the influence of the frequently-used biocide glutaraldehyde on the biodegradation of hydraulic fracturing fluid organic compounds under conditions relevant for shallow groundwater contamination. Five compounds were selected based on their frequent presence in fracturing fluids and their potential for transport in porous media: 2 butoxyethanol, isopropanol, ethylene glycol, 2-ethylhexanol, and propargyl alcohol. Biodegradation rates of the five compounds exposed to varying concentrations of glutaraldehyde were measured in aerobic and anaerobic groundwater microcosms containing a synthetic background groundwater and sandstone collected from the Arapahoe Formation in the Denver-Julesburg Basin. Flow-through column experiments were used to apply microcosm results to dynamic conditions representative of groundwater transport. Aerobic biodegradation of all five organic compounds was inhibited at glutaraldehyde concentrations as low as 5 mg L<sup>-1</sup>. The results of this study indicate that inhibition of biodegradation by biocides can influence the fate and transport of fracturing fluid organic constituents. Improved characterization of this co-contaminant interaction is necessary in order to estimate potential exposure in the event of an unintended release

Inhibition of biodegradation of hydraulic fracturing fluid organic compounds in groundwater by the biocide glutaraldehyde

251st National Meeting (2016)

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