A pinboard by
Omkar Lokare

PhD Student, University of Pittsburgh


My research goal is to study the fundamentals of membrane processes by using membrane distillation

Membrane Distillation (MD) is a thermal separation process that is driven by the vapor pressure difference across a hydrophobic membrane. The principle of MD is the same as conventional distillation. However, MD employs hydrophobic membranes for its operation. MD has immense potential in the desalination of highly saline wastewaters where reverse osmosis is not feasible. Recent advances in membrane distillation (MD) have proven that the process can obtain almost pure water from the most challenging wastewaters. MD can also concentrate saline solutions up to saturation and can have very high water recovery. While many studies have been carried out on membrane distillation for recovery of pure water from saline waste waters, there are certain avenues where MD has not been studied in detail. The primary focus of my research is to study the fundamentals and energetics of direct contact membrane distillation when treating high salinity waste waters and apply them on plant-level MD systems.


Fouling in Direct Contact Membrane Distillation of Produced Water from Unconventional Gas Extraction

Abstract: Hydraulic fracturing used for natural gas extraction from unconventional onshore resources generates large quantities of produced water that needs to be managed efficiently and economically to ensure sustainable development of this industry. Membrane distillation can serve as a cost effective method to treat produced water due to its low energy requirements, especially if waste heat is utilized for its operation. This study evaluated the performance of commercially available hydrophobic microfiltration membranes in a direct contact membrane distillation system for treating very high salinity (i.e., up to 300,000 mg/L total dissolved solids) produced water. Polypropylene and polytetrafluoroethylene membranes yielded the highest permeate flux with membrane distillation coefficient of 5.6 l/m2/hr/kPa (LMH/kPa). All membranes showed excellent rejection of dissolved ions, including naturally occurring radioactive material (NORM), which is a significant environmental concern with this high salinity wastewater. Analysis of membranes after extended testing with actual produced waters revealed unevenly distributed inorganic deposits with significant iron content. A key finding of this study is that the iron oxide fouling layer had negligible effect on membrane performance over extended period of time despite its thickness of up to 12 μm. The results of this study highlight the potential for employing membrane distillation to treat high salinity wastewaters from unconventional gas extraction.

Pub.: 27 Nov '16, Pinned: 31 Jul '17