Pharmaceutical compound removal using down-flow fixed bed filters with powder activated carbon: A novel configuration

Abstract

Emerging contaminants (ECs) are generating concern among the population, as they can cause adverse effects in aquatic biota. Based on new information for ECs and their potential impact on ecosystems, measures are being promoted among wastewater quality regulatory entities. Thus, the objective of this research was to develop an efficient technology to remove two recalcitrant pollutants, carbamazepine (Cbz) and sildenafil (Sil). A fixed bed adsorption column with powder activated carbon (PAC) uniformly distributed among sand at a ratio of 1:50 was designed to generate porosity and stability for the adsorbent material. This design was initially studied at laboratory to evaluate its operational capacity and the behavior of the compounds. It was determined that the Sil was efficiently removed, while the Cbz reached saturation after 25 days of continuous operation, defining it as the limiting pollutant. Then a pilot plant was evaluated, with a total bed height, PAC mass, contact time, surface rate and working flow of 20 cm, 40 g, 40 min, 0.4 cm3/(cm2.min) and 30 mL/min, respectively; in which removal efficiencies greater than 90% were achieved. The useful life, capacity and speed adsorption of the column were determined by simulating and analyzing the breakdown curves. It was concluded that using this technology, the adverse effects produced by these pollutants on water resources, can be mitigated. This is the first work wherein a downflow fixed bed column with PAC has been operated under continuous flow. The system can be operated without the need to incorporate additional procedures to separate PAC.