Removal of Chromium (III) and Reduction in Toxicity in a Primary Tannery Effluent Using Two Floating Macrophytes.

Trivalent chromium (Cr(III)) is a contaminant with toxic activity. Its presence in waters and soils is usually related to industrial activities such as tanneries. The aim of this study was to compare the removal of Cr(III) in hydroponic solutions and tannery effluents using two floating macrophytes: and . First, to determine the chromium removal capacity in solution and the bioaccumulation factor (BAF) in tissues of each plant, experiments were set up with contaminated solutions with Cr(III) concentrations of 2, 5, 10, 20, and 40 mg/L. Subsequently, both plant species were exposed to a primary tannery effluent contaminated with 12 mg/L of Cr(III) in order to study the removal capacity of organic and inorganic matter, as well as the acute toxicity in the water flea () and genotoxicity in zebrafish (). Tests carried out on nutrient solutions revealed that both plants have a high capacity for removing Cr(III) in solution. The BAF in tissues was higher in compared to . In the experiments with a tannery effluent, both species presented low nutrient and organic matter removal efficiency, but they showed good Cr(III) removal capacity, with average reduction values of 57% for and 54% for after 72 h of exposure. contributed most to the reduction in acute toxicity in , while did not show a similar effect. However, both plant species managed to reduce the genotoxicity marker in when compared with the initial effluent and the control.