Tolerance and phytoremediation capacity of the Lemna minor in an aqueous medium contaminated by the Amoxicillin

This study aims to evaluate the behavior and the effectiveness of the aquatic plant Lemna minor as a phytoremediation potential about the antibiotic amoxicillin. Experiments were conducted through Central Composite Rotational Design (CCRD) and a kinetic study. The experiments taken by CCRD were performed in culture wells during a contact period of 5 days. The concentration of amoxicillin in the aqueous medium, the quantity of the plant mass, and the solution's pH were studied as independent variables. The dependent variables measured were the remaining amoxicillin in the solution, the plant's tolerance to mortality or fronds cloning and, for stress, chlorophyll-a/chlorophyll-b ratio. A kinetic study determined the rate of antibiotic removal in the aqueous medium. Because the only significant independent variable was the Amoxicillin concentration, the best experimental condition obtained through CCRD was considered the one with the higher level of Amoxicillin removal (92%) - the water medium with the drug concentration at 2.0 mg L-1 and pH 7.0. 5 g of wet mass from L. minor for each 10 mL of solution was chosen since this independent variable was not significant. There was no pH variation in the solution and the plant stress in the kinetics study. However, there was an amoxicillin removal of 80% after the seventh day. It is considered that, under conditions of low antibiotic load, the aquatic plant Lemna minor presents phytoremediation capacity to antibiotic amoxicillin.