Removal of 17β-estradiol from secondary wastewater treatment plant effluent using Fe3+-Saturated montmorillonite

Abstract

Estrogens are of environmental concern because disruptive effect on biological functions at levels as low as ng/L. Wastewater treatment plant effluent is a significant source of estrogens in aquatic environment. Ferric ions (Fe3+)-saturated montmorillonite has been shown to effectively remove 17β-estradiol (βE2), a common estrogen, from pure water by catalyzing formation of insoluble βE2 oligomers on mineral surfaces. We investigated the effects of reaction temperature, dissolved organic matter, pH, and common cations, on Fe3+-saturated montmorillonite-surface catalyzed βE2 polymerization, and the removal of this estrogen from three different secondary wastewater effluents with more complicated matrixes. Highest βE2 removal occurred at near neutral pH and it increased with increasing treatment temperatures. Presence of common cations in the water did not affect the reaction efficiency. Dissolved organic matter at 15 mg C/L slightly lowered the βE2 removal efficiency as compared to that in pure water. Regardless of the source of wastewater effluents, βE2 removal efficiency of ∼40% was achieved using the dosage of Fe3+-saturated montmorillonite similar to that tested for the aqueous phases with simpler matrix. Doubling this dosage resulted in removal of ∼80% of βE2 from a tested secondary wastewater effluent within 30 min reaction. For wastewater with complex matrixes at the commonly reported βE2 levels which are magnitudes lower than the tested concentration in our study, this dosage would provide sufficient available reaction sites for the surface-catalyzed βE2 polymerization. This study demonstrated that Fe3+-saturated montmorillonite is a promising material for effective removal of phenolic estrogen compounds from domestic wastewater effluents.