NEW PROCESSES “MINE” METALS FROM WATER, FUEL FROM SEWAGE

Nations are scrambling for ways to source more cobalt, lithium, nickel, oil, and other minerals without having to depend on foreign sources.

Now the U.S. energy department’s Pacific Northwest National Laboratory (PNNL) has an answer.

The lab is grabbing metals from wastewater by adding magnetized iron nanoparticles covered by a chemical shell that snags lithium and other metals.

The cargo-laden particles are drawn out of the wastewater with a magnet. A simple process separates the metal from the particles, which then can be recharged and sent back into the wastewater stream.

The process can take minutes, compared to the conventional technique of pumping the wastewater into open pits and waiting months for the water to vaporize, leaving solids behind that need to be sifted and sorted.

The method could be used to add a revenue stream to geothermal power plants, which produce brine, water pumped out of oil and gas wells, or could even draw metals out of plain seawater.

The lab also has validated a way to turn sewage sludge into biocrude fuel through a process called hydrothermal liquefaction, which breaks down a wet biomass by putting it under pressure.

The process separates out carbon-hydrogen compounds with a high enough energy density to be used as a fuel.

If U.S. city sewage plants processing at least five million gallons of wastewater per day applied the technique, they could process 79 percent of total untreated municipal sludge in the country annually and collect almost a billion gallons of biocrude, a PNNL study calculated.

That would provide a new source of municipal revenues from locally collected and processed fuel as well as reduce the nation’s dependence on imported fuel. 

PNNL is working with commercial partners to bring both technologies to market.

TRENDPOST: To meet their needs for carbon fuels and strategic metals, nations will need to go beyond conventional recycling. Technologies that recover these resources from unexpected sources—which we reported on in “Pilot Projects Extract Rare Earth Metals From Coal Waste” (8 Jun 2021) —will become essential to tomorrow’s industrial economy.