Addressing Europe’s new hunger for sustainable activated carbon in wastewater treatment: Micropollutant removal with residual wood-based adsorbents using different activation strategies

Abstract

To meet the recast EU Urban Wastewater Treatment Directive, the EU and Austria will require approx. 270 and 10 kt a⁻¹ of activated carbon, respectively. This study explores the potential of using non-fossil activated carbon derived from residual woody biomass to fulfil this demand using experimental adsorption data. We compared a commercial activated carbon (COM-AC) with three activated carbons produced from local residual wood (ZINC-AC, G-AC, CO2-AC) using various activation strategies. ZINC-AC was produced through one-step chemical impregnation with ZnCl₂ of waste wood. G-AC was a by-product of gasifying forestry residue biomass, and CO2-AC is the CO₂-activated version of G-AC. Adsorption experiments were performed with a mix of six micropollutants in different water matrices. ZINC-AC exhibited the highest surface area (S_BET 1946 m² g⁻¹) and the second highest micropollutant capacity in tap water (257.4 mg g⁻¹), after COM-AC (297.6 mg g⁻¹). ZINC-AC's capacity remained stable in wastewater. G-AC showed a low capacity (34.6 mg g⁻¹), which could be increased to 105.1 mg g⁻¹ by CO₂-activation. The predominant removal mechanisms are identified as hydrophobic and π-interactions. The study suggests that these activated carbons from residual woods could be a viable alternative for wastewater treatment, though production yield (35 % vs. 3.5 % for the most promising methods) and quality will be crucial for assessing Europe’s activated carbon production potential from woody biomasses.