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(Unpublished)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