Removals of estrone and 17β-estradiol by microalgae cultivation: kinetics and removal mechanisms

Occurrence of estrone (E1) and 17β-estradiol (E2) in the environment has attracted the public attention since E1 and E2 cause estrogenicity in aquatic microorganisms. Microalgae cultivation in wastewater is considered as an economical practice since microalgae can be used for not only pollutant removals, but also as energy resources. This research aims to investigate the removals of E1 and E2 in synthetic wastewater by microalgae (i.e. Chlorella vulgaris and Scenedesmus obliquus). At the steady state, S. obliquus removed E1 and E2 by 91% and 99%, respectively. C. vulgaris removed E1 and E2 by 52% and 99%, respectively. Interestingly, the occurrence of E1 was observed when E2 was degraded by microalgae. The predominant mechanism for E1 and E2 removals was biodegradation, followed by adsorption. The adsorption kinetic and isotherm for both E1 and E2 can be described by the pseudo-second-order and Freundlich model. The addition of E1 and E2 resulted in a higher lipid content of microalgae by 1-9%.