L.E. Katz, M.R. Landsman, B.D. Freeman, A.F. Seibert
University of Texas at Austin,
United States
Keywords: produced water, membrane treatment, wastewater reuse
Summary:
The United Nations 2024 World Water Development Report* indicated that about half of the global population faced water scarcity for some portion of 2022. In some areas, over 80% of the annual renewable freshwater supply was used to meet existing needs, indicating extremely high levels of water stress. Climate change is expected to exasperate this situation, and increases in the occurrence of extreme and prolonged droughts will also stress ecosystems. The continued stress on fresh water supplies has motivated the use of nontraditional source waters for energy, agriculture, industry, and domestic needs. While brackish water and seawater are often considered ideal nontraditional source alternatives to freshwater, treated wastewater from each of these sectors can also increase water availability either within the sector from which the wastewater was generated (i.e., internal reuse) or for another sector. The specific treatment goals required are dependent on the initial source water or wastewater quality and the designated end use of the treated water; this notion is commonly referred to as fit-for-purpose treatment. In most cases, the development of integrated treatment systems for these complex waters requires an approach that holistically identifies technologies that can remove the suite of contaminants required to meet the particular end use, examines the pre- and post-treatment requirements and integration of each process, and considers the disposal and/or resource recovery options available for treatment residuals. Membrane technology has emerged as a promising approach for integrated treatment of the complex waste streams generated from energy, agriculture and industry due to their modularity, potential for lower energy requirements than other suitable technologies, and ability to perform precise separations. For example, produced water from U.S. oil and gas operations is one of the largest man-made wastewater streams. More than 90% of this water is reinjected into the subsurface, in large part because it is often highly impaired, containing elevated concentrations of organic and inorganic components. Decontamination of this highly complex wastewater can provide water for agricultural, industrial, and energy applications. Depending on the end-use, treatment trains may include removal of particulate solids, residual oil, salinity, bulk organics, trace organic contaminants, metals, and nutrients. Produced water also contains high concentrations of recoverable resources, such as residual oil and lithium. In this presentation, we will demonstrate the potential application of membrane technologies for particulate solids, residual oil, bulk and trace organics, and nutrients. In addition, we will present results for selective removal of boron for reuse of the produced water in the agricultural sector and recovery of lithium for use in the energy sector. The membrane processes that will be highlighted include electrodialysis (ED), ultrafiltration (UF), microfiltration (MF), reverse osmosis (RO) and membrane bioreactor treatment (MBR). Moreover, the presentation will highlight the opportunities and challenges associated with integration of various membrane processes to provide high selectivity, high permeability and reduced fouling. *United Nations, The United Nations World Water Development Report 2024: Water for Prosperity and Peace. UNESCO, Paris