Lokare, Omkar
(2019)
Direct Contact Membrane Distillation for Desalination of High Salinity Brines: Fundamentals and Application.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
This is the latest version of this item.
Abstract
Membrane distillation is a cost effective solution for the treatment of high salinity wastewater where reverse osmosis is not feasible, especially if waste heat is utilized for its operation. One such example of high salinity wastewater is produced water generated as a consequence of hydraulic fracturing used for natural gas extraction from unconventional onshore resources. The objective of this study was to evaluate the feasibility of treating such high salinity wastewaters by employing membrane distillation while using waste heat as a source of energy to drive the process and by using produced water as an example wastewater. When commercially available membranes were tested in a direct contact membrane distillation (DCMD) system, the membranes exhibited excellent rejections of ions with no flux degradation due to fouling. However, it was found that concentration polarization (CP) was significantly higher when treating high salinity feed water and the CP effect could not be accurately estimated using current methods of calculation. Based on lab scale studies, an ASPEN Plus simulation was developed to simulate the operation of large scale systems and estimate energy requirements of the DCMD process to treat produced water in the state of Pennsylvania by using exhaust stream of Natural Gas Compressor Station (NG CS) as the waste heat source. The results from this study suggested that the waste heat available from NG CS is sufficient to treat all the produced water generated in Pennsylvania regardless of its initial salinity.
In an attempt to study the effect of concentration polarization that was found to be significant during DCMD tests with produced water, and has been neglected in most membrane distillation studies, a novel spatially resolved non-intrusive spectrophotometric method was developed to measure the concentration profile of solute near the membrane surface in a direct contact membrane distillation system. The objective was to probe the concentration profile of solute and analyze the impact of operating parameters, such as feed concentration, hydrodynamic conditions and feed temperature, on the solute concentration profile in the boundary layer. A key finding of this study is that the conventional approach of estimating the effect of concentration polarization severely under predicts the boundary layer thickness (BLT) and concentration polarization coefficient (CPC). The results of this study highlight the need to develop new methods to estimate the BLT and CPC as the conventional approach of mass transfer analogy of heat transfer does not agree with experimental observations obtained for a membrane distillation system.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
24 January 2019 |
| Date Type: |
Publication |
| Defense Date: |
27 August 2018 |
| Approval Date: |
24 January 2019 |
| Submission Date: |
8 October 2018 |
| Access Restriction: |
1 year -- Restrict access to University of Pittsburgh for a period of 1 year. |
| Number of Pages: |
165 |
| 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: |
direct contact membrane distillation; produced water; fouling; membrane properties; concentration polarization; waste heat utilization; natural gas compressor stations; membrane distillation; recycle ratio; energy consumption; single pass water recovery; Concentration polarization; experimental analysis; model evaluation; spectrophotometric technique; nickel chloride; |
| Date Deposited: |
24 Jan 2019 15:24 |
| Last Modified: |
24 Jan 2020 06:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/35489 |
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Direct Contact Membrane Distillation for Desalination of High Salinity Brines: Fundamentals and Application. (deposited 24 Jan 2019 15:24)
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