Removal of a mixture of veterinary medicinal products by adsorption onto a Scenedesmus almeriensis microalgae-bacteria consortium

The adsorption of the veterinary medicinal products (VMP) tetracycline (TET), ciprofloxacin (CIP), sulfadiazine \n(SDZ) and sulfamethoxazole (SMX) onto a dried Scenedesmus almeriensis microalgae-bacteria consortium was \nstudied at several equilibrium concentrations (20 to 1000 μg/L). Scanning electron microscopy (SEM) and \nFourier-transform infrared spectroscopy (FTIR) analysis were performed to investigate the surface morphology of \nthe microalgae and to identify the effect of the antibiotics´functional groups on the surface of the consortium of \nS. almeriensis and bacteria. Ultra-high performance liquid chromatography tandem mass spectrometry (UHPLCMS/MS) was used to determine the feasibility of this consortium for the removal of antibiotics via biosorption. \nFreundlich and Langmuir adsorption models were used for the mathematical description of the adsorption \nequilibrium. Pseudo-first order and pseudo-second order kinetic models were applied to fit the biosorption \nexperimental data. Relative antibiotic removal was higher at low equilibrium concentrations. In the range of the \ninitial VMP concentration studied, ciprofloxacin and tetracycline exhibited the highest removal efficiency of \n43–100% and 75–82%, respectively. Likewise, ciprofloxacin and tetraciclyne presented the highest adsorption \nrates of 0.11–26.66 and 1.78–27.09 mg⋅μg− 1 \n⋅h− 1 \n, respectively. This study revealed that the S. almeriensis-bacteria \nconsortium has a high biosorption power and proved that biosorption is an important mechanism in the removal \nof ciprofloxacin and tetraciclyne using a microalgae-based water treatment process. However, sulfadiazine and \nsulfamethoxazole removals did not exceed 32%.