Wildfire-Derived Biomass as a Feedstock for Activated Carbon Production: Characterization, Heavy Metal Adsorption, and Preliminary Environmental and Economic Assessment

Wildfires burned an average of about 7 million acres per year in the United States between 2000 and 2025, more than twice the annual rate of the 1990s. The woody residue left behind is largely unmanaged. At the same time, heavy-metal contamination of drinking water by lead, cadmium, chromium, arsenic, and mercury remains a global health concern, and commercial activated carbon is too costly to address at scale in many affected regions. This work reviews the published literature on wildfire-derived biochar-based activated carbon (BAC) and adds pilot-scale characterization, process simulation, and a preliminary environmental and economic assessment. At a pilot plant in Louisville, Kentucky, activated carbon formulations derived from wildfire-affected biomass exhibited apparent BET surface areas ranging from 371 to 1805 m2 g−1, with char yields of 45 to 55% of the dry feed mass. Using the measured feedstock and product characterization, an Aspen Plus V14 simulation of the carbonization kiln gives a kiln heat duty of 10.36 MJ per kilogram of activated carbon. On this basis, the kiln fuel demand is 14.80 MJ per kilogram of activated carbon at 70% combined burner and wall efficiency, against 16.75 MJ per kilogram available from combustion of the process syngas and tar, a surplus of 1.95 MJ per kilogram, indicating that the kiln can be fired on its own volatiles without supplementary fuel. Using published cradle-to-gate emission factors, a mass-balance and global-warming-potential model gives a base-case fossil footprint of 3.02 kg CO2-eq per kg activated carbon (2.42 to 4.79, low to high), which is 64.9% lower than commercial wood-based activated carbon and 83.5% lower than coal-based activated carbon. Scaled from pilot-plant operating data, production costs of $0.45 to $1.20 per kg are comparable with those of commodity activated carbon. Under the stated recovery assumptions, a scenario analysis of NIFC regional burned-area data indicates that between 3.0 and 40.7 million dry tonnes of woody residue could be recoverable annually across the United States; the width of this range reflects the compounded uncertainty in the recovery assumptions, and it should not be read as a national recoverable inventory. Adsorption capacities of 100 to 400 mg g−1 for the priority metals are consistent with values reported in the literature for comparable biomass-derived carbons; no adsorption measurements were made on the carbons produced here.