Waste or Resource: Produced Water Characterization and Potential for Beneficial Reuse in Agriculture

Abstract:

Water supplies are under increasing pressure as a result of population and economic growth, industrialization, and impacts of climate change. The current drought across much of the western U.S. has exacerbated this situation, while at the same time, much of the region is also experiencing a host of energy generation activities, including oil and gas exploration and production. Produced water (PW) from unconventional oil and gas operations has been utilized in dry regions for irrigation purposes and potentially presents a new water source for irrigation in areas of increasing water scarcity. However, there is a potential for both geogenic chemicals and chemicals associated with hydraulic fracturing present in the water to accumulate in irrigated food crops. Previous work sought to characterize hydraulic fracturing wastewater throughout the fracturing process using under-utilized approaches to address the issues created by the complex matrices inherent to flowback and produced water.

Then, we assessed how water treatment technologies targeted at removal of salinity and organic content from PW to agricultural irrigation standards might decrease the impact of PW on two salt-tolerant food crops, sunflower and wheat. Controlled greenhouse experiments utilized PW sourced from a hydraulically fractured well in Colorado. As compared to raw PW diluted to reduce salinity, biologically active filtration followed by ultrafiltration (BAF-UF) was selected as the primary PW treatment for its ability to remove both turbidity and large organics. Electrodialysis (ED) was selected to further treat the BAF-UF treated PW to remove salts while also treating organic constituents present in the BAF-UF treated water. Water quality, soil quality, and plant tissues were analyzed for elemental composition primarily using Inductively Coupled Plasma (ICP) Atomic Emission Spectroscopy (AES) and Mass Spectroscopy (MS). Morphological observations of plant growth, soil condition assessment, and physiological investigation through characterization of uptake patterns via ICP-MS were used to evaluate the translocation and accumulation of metals, salts and micronutrients. Finally, data collected were used to calculate bioaccumulation factors upon plant maturity to assess how PW influences bioavailability.