(102b) Multi-Functional Sorbent Technology (MUST) for the Recovery/Removal of Critical/Heavy Metals from Fossil-Related Wastewaters

Ever-increasing contamination of Earth’s precious water systems with heavy and critical metals brings both a tremendous environmental burden to eliminate the toxic species and a golden opportunity to recover the most valuable elements. Fossil-related wastewaters like acid mine drainage (AMD), effluents from hydraulic fracturing processes (produced water), and flue gas desulfurization (FGD) wastewater from coal-fired powerplants contribute significantly to stream and groundwater pollution. A collection of remediation and recovery technologies like those predicated on photocatalytic-, electric-, chemical-, membrane-, and adsorptive-based processes currently exists in different stages of development or deployment between these methods of water management. Among these technologies, solid sorbent processes embody an optimal balance between cost-effectiveness, environmental friendliness, and technological maturity. The U.S. Department of Energy’s National Energy Technology Laboratory developed a suit of cross-linked, functionalized silica sorbents tailored to eliminate the most toxic metals regulated by the U.S. Environmental Protection Agency (EPA); critical metals identified by the U.S. Geological Survey (USGS); and harmful organics like the infamous perfluoroalkyl and polyfluoroalkyl substances (PFAS). An array of laboratory and field tests proved that the MUST sorbents removed ppb-level lead from drinking water, selenium from FGD wastewater below EPA limits, aqueous dyes and PFAS; and fractionated low ppm-level critical metals (CM) from AMD and simulated produced water. Proof-of-concept for commercial CM recovery was verified through obtaining milligram-quantities of purified Al solids from a sorbent multi-bed AMD field-site test. Commercial efficacy was further supported by achieving purified fractions of adsorbed Mn upon treating both the AMD and synthetic produced water with the laboratory multi-bed test unit.