Oil & gas produced water retention ponds as potential passive treatment for radium removal and beneficial reuse

Abstract

Oil and gas extraction generates large volumes of produced water (PW) in regions that are water-stressed. PW can be passively treated in retention ponds prior to beneficial use. Oxic conditions lead to sequestration and lower bioavailability of Ra.

Freshwater Mussel Soft Tissue Incorporates Strontium Isotopic Signatures of Oil and Gas Produced Water

“…Indeed, multiple studies reported changes in both total Ra and 226 Ra/ 228 Ra in sediments in which O&G-produced water was either spilled 6,14,15 or released. 5,10,12,61,62 Pseudofeces samples collected separately from the high-dose tank mussel containers (n = 6) had high specific Ra activities with 226 Ra activity ranging from 130 to 651 Bq/kg and 226 Ra/ 228 Ra ratios ranging from 4.7 to 7.0, reflecting a high Ra ratio slightly lower than the original O&G-produced water fluid ratio of 8.86. Difficult-to-acquire SEM images and EDS mapping of two randomly selected pseudofeces samples yielded similar compositions dominated again by C and O, followed by Si (pseudofeces coated some sand particles), Fe, Ba, Al, Ca, S, K, and Cl with negligible amounts of Na, Mg, and P (Figure S7).…”

“…9,11 Additionally, Ra accumulates in sediments kilometers downstream of the outfalls, leading to sediment contamination. 10,12 In addition to the impacts on surface water quality and sediment, mutagenicity was observed in water samples collected near discharges. 13 Regions such as the Williston Basin in North Dakota have experienced vast numbers of brine spills associated with unconventional O&G development with 3900 spills reported to the North Dakota Department of Health between 2007 and 2015.…”

“…Oil and gas (O&G) extraction processes in the United States generate >3 trillion L of produced water annually . Produced water represents a complex fluid high in salinity [10–300 g of total dissolved solids (TDS) per liter], hydrocarbons, metals (Ba, Ca, and Sr), and radioactivity, namely, the two most persistent isotopes of radium (Ra): 226 Ra and 228 Ra. , Produced water is often treated at centralized waste treatment facilities and, in Pennsylvania, discharged to surface waters through National Pollutant Discharge Elimination System (NPDES) permits, leading to concerns regarding water quality downstream. − In some arid western U.S. states, such as Wyoming, produced water is discharged to surface waters and designated as beneficial reuse due to downstream agriculture. − The discharges occur after minimal treatment that specifically targets hydrocarbons rather than metals. The beneficial use disposal practice has come under scrutiny because observations downstream of discharges suggest the water may not be fit for its intended use.…”

“…The beneficial use disposal practice has come under scrutiny because observations downstream of discharges suggest the water may not be fit for its intended use. While the water may be acceptable at the point of discharge, evaporative losses may increase salinity to levels that are not suitable for cattle or irrigation. , Additionally, Ra accumulates in sediments kilometers downstream of the outfalls, leading to sediment contamination. , In addition to the impacts on surface water quality and sediment, mutagenicity was observed in water samples collected near discharges . Regions such as the Williston Basin in North Dakota have experienced vast numbers of brine spills associated with unconventional O&G development with 3900 spills reported to the North Dakota Department of Health between 2007 and 2015 .…”

Produced Water Treatment and Valorization: A Techno-Economical Review

“…Naturally occurring radioactive materials (NORM) are within the inorganic species found in FP [7] in addition to iron (Fe), magnesium (Mg), strontium (Sr), calcium (Ca) and several other metal and nonmetal monoatomic and/or polyatomic species [8][9][10][11]. Some studies have reported significant concentrations of radium isotopes [11,12] as well as trace levels of radionuclides of cesium, lead, plutonium, polonium, strontium, thorium and uranium in FP [13,14].…”