Low-cost ceramic composite membranes for filtration of produced water
Abstract
A by-product of the extraction of oil and gas from underground rock formations, naturally occurring water known as 'produced water' is brought up to the surface. High in oil and salt concentrations that are expensive to remove, it is more financially feasible to dispose of produced water in underground injection wells than to treat and reuse, despite the long-term environmental effects. Meanwhile, more and more countries are being concerned about the decreasing global drinking water supply amid growing world population and rising temperatures due to global warming. A low-cost treatment method of produced water would not only provide financial incentive for treatment over disposal, eliminating the subsequent environmental side effects of disposal in underground injection wells, but also enhance the global water supply by generating non-potable water for agricultural and industrial use. With their robust thermal and chemical stability as well as long lifespans and environmentally-friendly materials, ceramic membranes are ideal for wastewater applications but traditionally have come at too high a cost to be used with produced water. In this study, a low-cost self-supporting ceramic composite membrane was developed using potassium-based geopolymer, clinoptilolite zeolite filler, and perforated aluminum support. The composition and processing methods for the membrane were optimized, and membrane microstructure was analyzed. Filtration performance of the geopolymer composite membranes was tested using two different filtration modes: end-flow and cross-flow filtration. While end-flow is typically used for lab-scale filtration testing, cross-flow filtration is more practical for industrial applications. Principles of each type of filtration mode are explained, and flux of produced water through the membrane was measured. Filtration results were analyzed for removal of particulate impurities and dissolved solids. Strategies for improving membrane design and performance, as well as next steps toward industrial application, are outlined and discussed.
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- OSU Theses [15752]