Microalgal consortium tolerance to bisphenol A and triclosan in wastewater and their effects on growth, biomolecule content and nutrient removal

Amongst the many treatments available for the removal of emerging contaminants in wastewater, microalgal cultures have been shown to be effective. However, the effectiveness of exposure of a native microalgal consortium to emerging contaminants such as bisphenol-A (BPA) and triclosan (TCS) to determine the half-maximum effective concentrations (EC50) has not yet been determined. The effect on growth and nutrient removal of such a treatment as well as on the production of biomolecules such as carbohydrates, lipids, and proteins are, at present, unknown. In this study, the EC50 of BPA and TCS (96-hour experiments) was determined using a consortium of native microalgae (Scenedesmus obliquus and Desmodesmus sp.) to define the maximum tolerance to these contaminants. The effect of BPA and TCS in synthetic wastewater (SWW) was investigated in terms of microalgal growth, chlorophyll a (Chl-a), carbohydrate, lipid, and protein content, as well as nutrient removal. Assays were performed in heterotrophic conditions (12/12 light/dark cycles). EC50-96 h values of 17 mg/L and 325 µg/L for BPA and TCS, respectively, were found at 72 h. For an initial microalgal inoculum of ≈ 300 mg TSS/L (total suspended solids per litre), growth increased by 16.1% when exposed to BPA and 17.78% for TCS. At ≈ 500 mg TSS/L, growth increased by 8.25% with BPA and 9.92% with TCS, respectively. At the EC50-96 h concentrations determined in the study, BPA and TCS did not limit the growth of microalgae in wastewater. Moreover, they were found to stimulate the content of Chl-a, carbohydrates, lipids, proteins, and enhance nutrient removal. Availability of data and material: Data sharing not applicable to this article as no datasets were generated or analysed during the present study.