Fate and transport of endocrine disrupting compounds on nanofiltration and reverse osmosis processes

Abstract

Endocrine disrupting compounds (EDCs) can enter the environment, disperse, and persist at trace levels that can cause adverse health effects on humans and wildlife. The key factors affecting EDC rejection in municipal secondary effluent—size exclusion, charge interactions, and physicochemical interactions—are discussed.

Increase of the contact angle and roughness indicates that the hydrophobic EDCs have sorbed onto the membrane. The measurements are at best qualitative indicators as the actual amount of EDC sorbed are unknown. For 4-n-NP and 4-t-OP, the pH vs sorption curve sags around pH 5.3, suggesting that it is an optimal pH to reduce adsorption. However, the sagging effect is only evident for samples with ionic strength of 100 mM. Based on the results, the adsorption of DEHP seems to be dominated by its hydrophobicity. The adsorption of DMP is governed by sorption-diffusion because of its relatively small size. DEHP and DMP were also found to be more affected by pore size as compared to 4-n-NP and 4-t-OP.

Further research could focus on the factors investigated, particularly pH and ionic strength. Filtration experiments may also be conducted to better understand the rejection of the EDCs.