Pawar, Ritesh Dinkar
(2023)
Fundamentals and scale-up of membrane distillation for treating produced waters from unconventional oil and gas reservoirs.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Hydraulic fracturing of shale oil and gas reservoirs poses significant environmental concerns related to water management. This process generates a large volume of produced water with high total dissolved solids (TDS). Membrane distillation (MD) can be a cost-effective solution for treating produced water, especially when waste heat is utilized. The objective of this study is to evaluate the feasibility of using membrane distillation for treating produced water from unconventional reservoirs with emphasis on fundamental developments and scale-up of the process.
Lab-scale tests were conducted on commercially available membranes, which showed excellent salt rejection but continuous increase in permeate conductivity due to the passage of volatile compounds and certain organic substances. Detailed organics analysis revealed passage of some organics like nonylphenol ethoxylates (NPEOs) and octylphenol ethoxylates (OPEOs) from feed to permeate but did not lead to wetting of the membranes. In an attempt to better understand the interaction between non-ionic surfactants and hydrophobic membrane, lab-scale studies were conducted with non-ionic surfactants like NPEOs and OPEOs with varying ethoxylate chain length and concentration. Alternative surfactants like linear alcohol ethoxylates (LAEs), branched secondary alcohol ethoxylates (BAEs), alkyl polyglycosides (APGs) were also examined due to concerns surrounding NPEOs in hydraulic fracturing.
To upscale the lab-scale findings, pilot-scale studies were conducted using an air gap MD system to treat produced water from the Permian Basin. Filtration-only pre-treatment resulted in precipitation of certain salts (SrSO4, NaCl, and Fe) when their solubility limits were exceeded. However, chemical pre-treatment involving pH adjustment, aeration, and barite precipitation allowed successful steady-state operation of the pilot system for 5 days, recovering 50% of the produced water as high-quality permeate. The pilot-scale studies were extended to test produced water from different shale gas plays across the United States. The pilot plant performance was evaluated to determine the cost of treating produced water, and the obtained permeate was assessed for beneficial reuse.
Drawing on the comprehensive understanding gained from lab and pilot-scale studies, this study offers insights into the potential use of MD as a cost-effective treatment option for high salinity wastewaters, yielding good quality water.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
14 September 2023 |
| Date Type: |
Publication |
| Defense Date: |
9 June 2023 |
| Approval Date: |
14 September 2023 |
| Submission Date: |
11 June 2023 |
| Access Restriction: |
1 year -- Restrict access to University of Pittsburgh for a period of 1 year. |
| Number of Pages: |
196 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Chemical and Petroleum Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Desalination, Membrane Distillation, Produced Water, Pilot-scale studies |
| Date Deposited: |
14 Sep 2023 13:35 |
| Last Modified: |
14 Sep 2023 13:35 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/44913 |
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