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Control of Naturally Occurring Radioactive Material (NORM) in Produced Water by Inorganic Sorbents

Gusa, Alen (2020) Control of Naturally Occurring Radioactive Material (NORM) in Produced Water by Inorganic Sorbents. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Abstract

Produced water generated during unconventional gas extraction is characterized by high total dissolved solids (TDS) and high concentration (i.e., up to 4,000 times higher than the drinking water standard) of naturally occurring radioactive material (NORM). The goal of this study was to evaluate options for the control of major components of NORM in produced water, Ra-226 and Ra-228, and mitigate potential adverse health and environmental impacts.
Radium removal capacity of barite (BaSO4), one of the most cost-effective solids for radium separation, was affected by monovalent and divalent cations in solution due to competition and impact on barite zeta potential. Molecular dynamics simulations showed a reasonable agreement with experimental results. The main discrepancy was due to dissolution-recrystallization reactions at barite surface that are not included in theoretical calculations. This dissertation research provided key fundamental insights into radium removal by barite and enabled accurate estimate of the effect of different cations on radium uptake.
In an attempt to sequester NORM underground and prevent its accumulation in surface impoundments, a novel coated hydraulic fracturing proppant was developed in this dissertation. Proppant sand impregnated with celestite (SrSO4) and barite using heterogeneous precipitation showed remarkable capacity for Ra-226. These novel proppants, with fairly small amount of impregnate (i.e., 10-30 mg/g), exhibited sufficient capacity for Ra-226 even at high ionic strength and elevated solution temperatures. It is also estimated that this method can control Ra-226 during the lifetime of the well (i.e., 20 years).
If Ra-226 is brought to the surface, co-precipitation as Ba-Ra-SO4 is the best way to remove it prior to salt recovery or to prevent accumulation in surface impoundments. Produced water with high Sr/Ba concentration ratios is challenging due to the interference of Sr with this process. Optimization of the treatment process to achieve requisite effluent quality while minimizing the total amount of radioactive sludge involved adjustment of Sr/Ba ratio and addition of barite “seed”.
Based on the improved understanding of radium removal by barite adsorption/co-precipitation, this study offers options for the control of NORM in produced water by either sequestering it in the subsurface or by treating produced water above ground.


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Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Gusa, AlenALG197@pitt.eduALG1970000-0002-5901-551X
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairVidic, Radisavvidic@pitt.edu
Committee MemberGilbertson, Leannelmg110@pitt.edu
Committee MemberNg, Carlacarla.ng@pitt.edu
Committee MemberFlora, Josephflora@cec.sc.edu
Date: 29 January 2020
Date Type: Publication
Defense Date: 18 November 2019
Approval Date: 29 January 2020
Submission Date: 20 November 2019
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 141
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Civil and Environmental Engineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: NORM, Hydraulic Fracturing, Produced Water, Barite, Celestite, Radium
Date Deposited: 29 Jan 2020 15:26
Last Modified: 29 Jan 2020 15:26
URI: http://d-scholarship.pitt.edu/id/eprint/37841

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