RADIUM TRANSPORT FOLLOWING PRODUCED WATER DISCHARGES AND APPLICATIONS TO TREATMENT AND REUSE

Petroleum extraction in the United States annually generates approximately 3 trillion L of wastewater (produced water) that has the potential to be treated and reused, particularly in water-stressed regions. Currently, reuse and recycling of produced water accounts for approximately only six percent of annual U.S. produced water generated. Produced water can have extreme salinities (upwards of 400,000 mg/L total dissolved solids) and elevated radioactivity (e.g., radium) making beneficial reuse challenging. Produced water also contains commodities of interest that include lithium, bromide, and alkaline earth metals such as calcium and magnesium, yet the environmental fate and transport of radium during commodity recovery is not yet clear. Current work seeks to quantify radium fate and transport in two systems designed to sequester carbon from flue gas by utilizing alkaline earth metals from produced water to precipitate carbonate products. Many researchers have not considered the potential hazards associated with elevated concentrations of radium in produced water treated in engineered commodity extraction systems. From previous field studies of produced water discharges to surface water, it was determined that 1) the strontium to barium molar ratio of produced water impacts sulfate mineral incorporation of radium¹, 2) radium readily sorbs to iron and manganese hydrous oxide solids², and 3) radium can be incorporated into calcium carbonate minerals³. These three lessons learned can be applied to produced water commodity extraction and reuse research to minimize human and environmental exposure to radium.

References

1. McDevitt, B. et al. Maximum Removal Efficiency of Barium, Strontium, Radium, and Sulfate with Optimum AMD-Marcellus Flowback Mixing Ratios for Beneficial Use in the Northern Appalachian Basin. Environ. Sci. & Technol. 54, 4829–4839 (2020).
2. Van Sice, K. et al. Radium attenuation and mobilization in stream sediments following oil and gas wastewater disposal in western Pennsylvania. Appl. Geochemistry 98, 393–403 (2018).
3. McDevitt, B. et al. Emerging investigator series: radium accumulation in carbonate river sediments at oil and gas produced water discharges: implications for beneficial use as disposal management. Environ. Sci. Process. Impacts 21, 324–338 (2019).