Fixed-bed adsorption of antibiotics using a brewery residue-derived biosorbent: Matrix effects, regeneration, and environmental assessment

This study investigated the production, characterization, and performance evaluation of biochar derived from microwave-pyrolysis of spent brewery grains (BC-SBG) for the adsorption of sulfamethoxazole (SMX), trimethoprim (TMP), and ciprofloxacin (CIP) from water, with especial focus in continuous fixed-bed application. The most favorable flow rate was identified and adsorption removal in buffered distilled water and real wastewater, for single and mixed antibiotic solutions, was evaluated. Adsorption efficiencies were higher in buffered distilled water for single solutions compared to wastewater and mixed antibiotic solutions, due to the competitive effects of dissolved organic matter in wastewater and interactions between antibiotics. Thermal regeneration of BC-SBG through microwave pyrolysis increased its specific surface area (starting at 281 m 2 g −1 in cycle 1, up to 462 m 2 g −1 in cycle 3), enhancing the TMP adsorption capacity of BC-SBG by 45 % from cycle 1 to 2 and 79 % from cycle 1 to 3. Life cycle assessment provided valuable information, identifying the BC-SBG production steps with the greatest environmental impact, highlighting areas for potential optimization. • Biochar (BC-SBG) was obtained by microwave pyrolysis of spent brewery grains. • BC-SBG was tested for fixed-bed adsorption of 3 antibiotics. • Flow rate and matrix effects influenced the antibiotics adsorption. • Microwave regeneration increased trimetoprim adsorption by 79 %. • Life cycle assessment identified environmental hotspots of BC-SBG production.