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Fixed-bed performance of a waste-derived granular activated carbon for the removal of micropollutants from municipal wastewater

Jaria, Guilaine, Calisto, Vânia, Silva, Carla Patrícia, Gil, María Victoria, Otero, Marta, Esteves, Valdemar I.
The Science of the total environment 2019 v.683 pp. 699-708
activated carbon, adsorption, drugs, electrostatic interactions, municipal wastewater, pH, pollutants, pollution control, pulp and paper mills, sulfamethoxazole, surface area, viability
This work aimed to assess the fixed-bed adsorptive performance of a primary paper mill sludge-based granular activated carbon (PSA-PA) for the removal of pharmaceuticals, namely carbamazepine (CBZ), sulfamethoxazole (SMX) and paroxetine (PAR), from water. The breakthrough curves corresponding to the adsorption of CBZ at different flow rates and in two different matrices (distilled and municipal wastewater) were firstly determined, which allowed to select the most favorable flow rate for the subsequent experiments. The fixed-bed adsorption of CBZ, SMX and PAR from single and ternary solutions in wastewater showed that the performance of PSA-PA was different for each pharmaceutical. According to the obtained breakthrough curves, the poorest bed adsorption capacity, either from single or ternary solution, was observed for SMX, which may be related with electrostatic repulsion at the pH of the wastewater used (pH ~ 7.3–7.7). Also, the bed adsorption capacity of PSA-PA for SMX, in the ternary solution, was notoriously lower compared to the single solution, while it slightly decreased for CBZ and even increased for PAR. The regeneration studies showed that the CBZ adsorption capacity of the PSA-PA bed decreased about 38 and 71% after the first and the second thermal regeneration stages, respectively. This decline was comparatively larger than the corresponding reduction of the PSA-PA specific surface area (SBET), which decreased only 5 and 25% for the first and second regeneration stages, respectively, and pointed to the lack of viability of more than one regeneration stage.