Feasibility of using freshwater microalgae to remove triclosan from aqueous media

Abstract

Triclosan, [5-chloro-2-(2,4-dicholophenoxy)phenol] (TCS), a broad-spectrum antimicrobial agent found in many personal care products, has raised concerns due to its presence in the environment. TCS has been associated to harmful effects, including oxidative damage in golfish cells, increased lipid peroxidation in clams, and disruption of the hypothalamic-pituitary-gonadal axis in Catla fish, and its potential contribution to antimicrobial resistance. This study evaluates the feasibility of using two freshwater microalgae species to remove TCS from aqueous media by 1) determining the toxicity of TCS on algal cultures, 2) evaluating their potential to remove TCS, and 3) identifying the TCS degradation kinetics. The toxicity test assessed various concentrations of TCS (0.06, 0.10, 0.20, 0.30, 1 mg L⁻¹) on Chlorella vulgaris and Scenedesmus obliquus growth. Results showed that C. vulgaris was entirely inhibited by concentrations exceeding 0.10 mg L⁻¹. In comparison, S. obliquus tolerated up to 0.30 mg L⁻¹ after six days of lag phase, but 1 mg L⁻¹ was toxic for both species. The removal efficiency achieved by S. obliquus was between 79 % and 94 % across all concentrations tested, while C. vulgaris achieved 70–95 % removal only in concentrations lower than 0.10 mg L⁻¹. The degradation kinetics revealed that the TCS half-life in wastewater was 1.3 days when S. obliquus was present, highlighting its potential to enhance pollutant removal. This study provides insights into the use of S. obliquus for removing contaminants from natural environments, contributing to understanding TCS dynamics in ecosystems with the presence of microalgae.