Treatment of wastewater generated during hydraulic fracturing (produced water) is challenged by high salt and radionuclide concentrations, as well as organic content. Current management approaches for produced water include disposal via deep well injection and physical-chemical treatment for either reuse or surface disposal. Limitations to current approaches include induced seismicity, fouling of membranes, and high cost. The reuse of produced water has emerged as a desirable management option; however, this requires pretreatment to generate a water of usable quality and to limit microbial activity. Biological treatment is an underexplored area in produced water management and has the potential to remove organics and reduce overall costs by limiting fouling during physiochemical treatment and microbial activity during reuse. Suspended growth biological treatment is limited by salinity, motivating a more robust biofilm approach: ‘microbial mats’. Evaluation of the biodegradation performance of microbial mats in synthetic and real produced waters showed microbial activity at up to 100,000 mg/L TDS concentration (three times the salt concentration of the ocean). We observed up to 66% and 45% removal of guar gum, a common fracking fluid additive, at salt concentrations of 50,000 and 100,000 mg/L, respectively. On-going studies focus on the evaluation of the removal of potentially toxic, carcinogenic or persistent organic compounds. Additionally, I will discuss our work on the removal of inorganic contaminants of high concern in produced water including sulfate and radium-226 using microbial mats. Finally, I will discuss the effect of the biofilm growth conditions on biodegradation under various salt concentrations.

Biofilm treatment approach for produced water from hydraulic fracturing using engineered microbial mats

251st National Meeting (2016)

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