Removal of Estradiol, Diclofenac, and Triclosan by Naturally Occurring Microalgal Consortium Obtained from Wastewater

Abstract

The occurrence of emerging contaminants like pharmaceutical drugs and personal care products in aquatic systems is now being identified as a potential risk to human health. Since conventional wastewater treatment systems are unable to remove them sufficiently, high concentrations of some of the commonly used drugs are reported to be occurring in many effluents. Microalgae-based systems have been investigated in recent years as an environmentally safe alternative to chemical oxidation methods for elimination of these emerging contaminants. Therefore, a process utilizing the microalgal consortium was assessed for its potential to tolerate environmentally high concentrations of pharmaceutical drugs and also to simultaneously remove the synthetic hormone estradiol, anti-inflammatory drug diclofenac, and antibacterial agent triclosan. The effective concentration with 50% mortality for the consortium was determined for each contaminant as 16, 8, and 8 mg L−1 for estradiol, diclofenac, and triclosan, respectively. These three drugs were then spiked separately in algal growth media at effective concentration with 50% mortality, and the microalgal growth in presence of these drugs and the drug removal was monitored in shake-flask setup. The study shows substantial removal of estradiol 91.73% ± 0.0175, diclofenac 74.68% ± 0.0092, and triclosan 78.47% ± 0.015 by the microalgal consortium during their growth phase. Further, it was observed that degradation of the drugs by microalgae was the prominent removal mechanism and not adsorption. Estradiol and diclofenac did not show any immediate negative impacts on the microalgal growth as seen from the biomass and chlorophyll content measurements. However, triclosan proved detrimental to the microalgal growth as the consortium did not survive beyond 5 days after spiking. Promising results for emerging contaminants removal was obtained, and a treatment system can be designed to remove different drugs from wastewater by using the naturally occurring microalgal consortium.