BENEFICIAL REUSE: THE FUTURE OF WASTEWATER GENERATED DURING ACTIVE AND LEGACY ENERGY DEVELOPMENT (Invited Presentation)

Oil and gas wastewater reuse and commodity recovery are timely research topics as operators seek alternative means of disposal, as agricultural communities require stable water supplies, and as policy makers seek to rehabilitate abandoned mine lands and strengthen domestic critical mineral supply chains. Petroleum development in the United States annually generates approximately 3 trillion liters (L) of wastewater (produced water), often in water-stressed regions. The majority of U.S. produced water is re-injected into subsurface geologic formations for disposal or hydraulic fracturing. However, there are opportunities for beneficial reuse of these fluids, which in the United States, have typically included road maintenance (e.g., de-icing and dust suppression), agriculture (e.g., crop irrigation and livestock drinking water), and wildlife propagation through stream augmentation. Few studies have conducted large field-scale environmental assessments of the beneficial reuse of produced water, despite increasing interest and potential impacts. Produced water can have extreme salinities (upwards of 400,000 mg/L total dissolved solids) and elevated radioactivity (e.g., radium) making beneficial reuse challenging. Produced water also contains commodities of interest that include lithium, bromide, and alkaline earth metals such as calcium and magnesium. Our on-going work seeks to quantify radium fate and transport in a system designed to recover critical minerals from produced water and another system designed to sequester carbon from flue gas utilizing produced water alkaline earth metals.

Coal-derived abandoned mine drainage (AMD) is another significant, domestic, energy-derived waste stream with both potentially environmentally harmful compositions (e.g., high acidity and elevated concentrations of iron, aluminum, and manganese) and recoverable commodities (e.g., critical minerals including rare earth elements). Many AMD discharge sites remain untreated while some have active and/or passive treatment systems in place that are intended to simultaneously sequester both precipitated metal oxide solids and critical minerals. On-going research characterizes treatment solids for critical minerals and possible radium associations to avoid human health impacts upon extraction.