More Like this

1. Raw material recovery from hydraulic fracturing residual solid waste with implications for sustainability and radioactive waste disposal

   https://doi.org/10.1039/C8EM00248G  

   Ajemigbitse, Moses A.; Cannon, Fred S.; Klima, Mark S.; Furness, James C.; Wunz, Chris; Warner, Nathaniel R. (February 2019, Environmental Science: Processes & Impacts)

   Unconventional oil and gas residual solid wastes are generally disposed in municipal waste landfills (RCRA Subtitle D), but they contain valuable raw materials such as proppant sands. A novel process for recovering raw materials from hydraulic fracturing residual waste is presented. Specifically, a novel hydroacoustic cavitation system, combined with physical separation devices, can create a distinct stream of highly concentrated sand, and another distinct stream of clay from the residual solid waste by the dispersive energy of cavitation conjoined with ultrasonics, ozone and hydrogen peroxide. This combination cleaned the sand grains, by removing previously aggregated clays and residues from the sand surfaces. When these unit operations were followed by a hydrocyclone and spiral, the solids could be separated by particle size, yielding primarily cleaned sand in one flow stream; clays and fine particles in another; and silts in yet a third stream. Consequently, the separation of particle sizes also affected radium distribution – the sand grains had low radium activities, as lows as 0.207 Bq g −1 (5.6 pCi g −1 ). In contrast, the clays had elevated radium activities, as high as 1.85–3.7 Bq g −1 (50–100 pCi g −1 ) – and much of this radium was affiliated with organics and salts that could be separated from the clays. We propose that the reclaimed sand could be reused as hydraulic fracturing proppant. The separation of sand from silt and clay could reduce the volume and radium masses of wastes that are disposed in landfills. This could represent a significant savings to facilities handling oil and gas waste, as much as $100 000–300 000 per year. Disposing the radium-enriched salts and organics downhole will mitigate radium release to the surface. Additionally, the reclaimed sand could have market value, and this could represent as much as a third of the cost savings. Tests that employed the toxicity characteristic leaching protocol (TCLP) on these separated solids streams determined that this novel treatment diminished the risk of radium mobility for the reclaimed sand, clays or disposed material, rendering them better suited for landfilling. 

   more » « less
2. Geochemical and isotope analysis of produced water from the Utica/Point Pleasant Shale, Appalachian Basin

   https://doi.org/10.1039/D0EM00066C  

   Tasker, T. L.; Warner, N. R.; Burgos, W. D. (May 2020, Environmental Science: Processes & Impacts)

   While development of the Utica/Point Pleasant Shale (UPP) is extensive in Ohio (U.S.) and increasing in Pennsylvania and West Virginia, few studies report the chemistry of produced waters from UPP wells. These data have important implications for developing best management practices for handling and waste disposal, or identifying the fluid in the event of accidental spill events. Here, we evaluated the elemental and isotope chemistry of UPP produced waters from 26 wells throughout Ohio, Pennsylvania, and West Virginia to determine any unique fluid chemistries that could be used for forensic studies. Compared to the Marcellus, UPP produced waters contain higher activities of total radium ( 226 Ra + 228 Ra) and higher 228 Ra/ 226 Ra ratios. As with the Marcellus Shale, elemental ratios (Sr/Ca) and isotope ratios ( 87 Sr/ 86 Sr) can distinguish UPP produced waters from many conventional oil and gas formations. Sr/Ca and 87 Sr/ 86 Sr ratios can fingerprint small fractions (∼0.1%) of UPP produced water in freshwater. However, because Marcellus and UPP produced waters display similar major elemental chemistry ( i.e. , Na, Ca, and Cl) and overlapping ratios of Sr/Ca and 87 Sr/ 86 Sr, 228 Ra/ 226 Ra ratios may be the best tracer to distinguish these waters. 

   more » « less
3. Controls on Dissolved Barium and Radium‐226 Distributions in the Pacific Ocean Along GEOTRACES GP15

   https://doi.org/10.1029/2023GB008005  

   Le_Roy, Emilie; Charette, Matthew A; Henderson, Paul B; Shiller, Alan M; Moore, Willard S; Kemnitz, Nathaniel; Hammond, Douglas E; Horner, Tristan J (June 2024, Global Biogeochemical Cycles)

   Abstract Radium‐226(²²⁶Ra) and barium (Ba) exhibit similar chemical behaviors and distributions in the marine environment, serving as valuable tracers of water masses, ocean mixing, and productivity. Despite their similar distributions, these elements originate from distinct sources and undergo disparate biogeochemical cycles, which might complicate the use of these tracers. In this study, we investigate these processes by analyzing a full‐depth ocean section of²²⁶Ra activities (T_1/2 = 1,600 years) and barium concentrations obtained from samples collected along the US GEOTRACES GP15 Pacific Meridional Transect during September–November 2018, spanning from Alaska to Tahiti. We find that surface waters possess low levels of²²⁶Ra and Ba due to export of sinking particulates, surpassing inputs from the continental margins. In contrast, deep waters have higher²²⁶Ra activities and Ba concentrations due to inputs from particle regeneration and sedimentary sources, with²²⁶Ra inputs primarily resulting from the decay of²³⁰Th in sediments. Further, dissolved²²⁶Ra and Ba exhibit a strong correlation along the GP15 section. To elucidate the drivers of the correlation, we used a water mass analysis, enabling us to quantify the influence of water mass mixing relative to non‐conservative processes. While a significant fraction of each element's distribution can be explained by conservative mixing, a considerable fraction cannot. The balance is driven using non‐conservative processes, such as sedimentary, rivers, or hydrothermal inputs, uptake and export by particles, and particle remineralization. Our study demonstrates the utility of²²⁶Ra and Ba as valuable biogeochemical tracers for understanding ocean processes, while shedding light on conservative and myriad non‐conservative processes that shape their respective distributions. 

   more » « less
4. SARS-CoV-2 RNA is enriched by orders of magnitude in primary settled solids relative to liquid wastewater at publicly owned treatment works

   https://doi.org/10.1039/d1ew00826a  

   Kim, Sooyeol; Kennedy, Lauren C.; Wolfe, Marlene K.; Criddle, Craig S.; Duong, Dorothea H.; Topol, Aaron; White, Bradley J.; Kantor, Rose S.; Nelson, Kara L.; Steele, Joshua A.; et al (February 2022, Environmental Science: Water Research & Technology)

   Wastewater-based epidemiology has gained attention throughout the world for detection of SARS-CoV-2 RNA in wastewater to supplement clinical testing. Raw wastewater consists of small particles, or solids, suspended in liquid. Methods have been developed to measure SARS-CoV-2 RNA in the liquid and the solid fraction of wastewater, with some studies reporting higher concentrations in the solid fraction. To investigate this relationship further, six laboratories collaborated to conduct a study across five publicly owned treatment works (POTWs) where both primary settled solids obtained from primary clarifiers and raw wastewater influent samples were collected and quantified for SARS-CoV-2 RNA. Settled solids and influent samples were processed by participating laboratories using their respective methods and retrospectively paired based on date of collection. SARS-CoV-2 RNA concentrations, on a mass equivalent basis, were higher in settled solids than in influent by approximately three orders of magnitude. Concentrations in matched settled solids and influent were positively and significantly correlated at all five POTWs. RNA concentrations in both settled solids and influent were correlated to COVID-19 incidence rates in the sewersheds and thus representative of disease occurrence; the settled solids methods appeared to produce a comparable relationship between SARS-CoV-2 RNA concentration measurements and incidence rates across all POTWs. Settled solids and influent methods showed comparable sensitivity, N gene detection frequency, and calculated empirical incidence rate lower limits. Analysis of settled solids for SARS-CoV-2 RNA has the advantage of using less sample volume to achieve similar sensitivity to influent methods. 

   more » « less
5. Oil & gas produced water retention ponds as potential passive treatment for radium removal and beneficial reuse

   https://doi.org/10.1039/D0EM00413H  

   McDevitt, Bonnie; McLaughlin, Molly C.; Blotevogel, Jens; Borch, Thomas; Warner, Nathaniel R. (April 2021, Environmental Science: Processes & Impacts)

   Oil and gas (O&G) extraction generates large volumes of produced water (PW) in regions that are often water-stressed. In Wyoming, generators are permitted under the National Pollutant Discharge Elimination System (NPDES) program to discharge O&G PW for beneficial use. In one Wyoming study region, downstream of the NPDES facilities exist naturally occurring wetlands referred to herein as produced water retention ponds (PWRPs). Previously, it was found that dissolved radium (Ra) and organic contaminants are removed within 30 km of the discharges and higher-resolution sampling was required to understand contaminant attenuation mechanisms. In this study, we sampled three NPDES discharge facilities, five PWRPs, and a reference background wetland not impacted by O&G PW disposal. Water samples, grab sediments, sediment cores and vegetation were collected. No inorganic PW constituents were abated through the PWRP series but Ra was shown to accumulate within PWRP grab sediments, upwards of 2721 Bq kg −1 , compared to downstream sites. Ra mineral association with depth in the sediment profile is likely controlled by the S cycle under varying microbial communities and redox conditions. Under anoxic conditions, common in wetlands, Ra was available as an exchangeable ion, similar to Ca, Ba and Sr, and S was mostly water-soluble. 226 Ra concentration ratios in vegetation samples, normalizing vegetation Ra to sediment Ra, indicated that ratios were highest in sediments containing less exchangeable 226 Ra. Sequential leaching data paired with redox potentials suggest that oxic conditions are necessary to contain Ra in recalcitrant sediment minerals and prevent mobility and bioavailability. 

   more » « less