NETL technology initially used for carbon capture applications can play a significant role in removing toxic metals that flow from thousands of abandoned and active mines across the nation to pollute streams, destroy aquatic life and contaminate water supplies.

Multi-functional Sorbent Technology (MUST) represents a game-changing, low-cost process to mitigate the devastating effects of acid mine drainage (AMD) on waterways, groundwater and fragile aquatic ecosystems.

AMD occurs when the iron sulfides unearthed by mining activity interact with water and air and oxidize. The process creates sulfuric acid, a highly corrosive acid capable of breaking down surrounding rocks, which can cause toxic metals to enter and eventually dissolve into the water.

More than 12,000 miles of stream have been affected by AMD in the United States. These streams are mostly located in regions with extensive mining activity, such as Appalachia. In Pennsylvania alone, there are more than 5,500 miles of streams with impaired water quality due to runoff from abandoned mines, according to the state Department of Environmental Protection.

“Working with a previous commercial partner and through our own internal research, we have demonstrated that MUST can remove metals from acid mine drainage, which improves access to clean water while creating a revenue stream to fund further environmental remediation efforts in communities where mining activities have contaminated streams and groundwater,” said NETL researcher McMahan Gray, who led the team that developed MUST to capture carbon dioxide from coal-burning power plants and adapted the technology for water treatment.

MUST comprises a suite of versatile and low-cost, regenerable sorbent materials that look like fine grains of sand. MUST strongly binds and removes selenium, lead, cadmium, chromium, arsenic, mercury and other heavy metals from AMD and other industrial effluents.

Because MUST is a particle sorbent with open pores, rapid transport of metals into and out of the sorbent provides quick adsorption-desorption cycling. NETL research has demonstrated that the adsorption capacity of MUST for some key metal contaminants is 50% higher than other commercial exchange methods.

In addition to removing unwanted elements, MUST can also extract beneficial critical minerals such as aluminum, nickel and rare earth elements (REE) from water. REEs and critical minerals (CMs) are used in the production of medical equipment, clean energy components, electric vehicles, electronics, military technology and a wide variety of consumer goods.

“This expands MUST’s application beyond toxic metals to valuable metals,” Gray said.

Using MUST, the nation can bolster its own sustainable supply of REEs and CMs, reducing the risk of supply disruption for essential domestic and military industries and creating materials for new high-tech, clean energy manufacturing jobs while restoring polluted water sources, waterways and environmentally scarred lands.

NETL’s MUST technology has been widely recognized as an important scientific breakthrough. In October 2021, MUST earned a prestigious R&D 100 Award. The competition annually recognizes 100 winning products and technologies as the disruptors that will change industries and make the world a better place in the coming years.

In April, MUST received a bronze medal in the Eco-Innovation category of the Edison Awards, an international competition.

The potential applications for MUST go beyond treating AMD. MUST could also be used to remove lead from municipal drinking water and radioactive species from nuclear wastewater. Gray noted new research is focused on using the sorbent-based technology to extract REEs and CMs from produced water, a byproduct of almost all oil and gas operations and hydraulic fracturing.

NETL is a U.S. Department of Energy national laboratory that drives innovation and delivers technological solutions for an environmentally sustainable and prosperous energy future. By leveraging its world-class talent and research facilities, NETL is ensuring affordable, abundant and reliable energy that drives a robust economy and national security, while developing technologies to manage carbon across the full life cycle, enabling environmental sustainability for all Americans.