Rejection of pharmaceutical compounds from surface water by nanofiltration and reverse osmosis

Abstract

This study investigated the performances of nanofiltration (NF—NF 90, NF 270, MPF34, DK and Duracid) and reverse osmosis (RO—BW30 and SG) as surface water treatments to reject pharmaceutical compounds at very low concentrations, on water permeability and on their desalting ability. The Doce river in Brazil was chosen as the background matrix for this study (geographical coordinates 18°51′50.45″S and 41°56′46.86″ W), this river is a source of drinking water and used for sewage disposal without previous treatment. Five pharmaceutically active compounds (PhACs) were detected recurrently and were investigated in this study: Betamethasone, Fluconazole, Phenylbutazone, Prednisone and Metformin. The results obtained suggest that NF may be the better option. The NF rejection efficiencies are very close to those achieved by RO membranes. Among the evaluated NF membranes, the DK membrane was selected as being the most suitable since it showed high desalting ability and PhAC rejection associated with high permeate flux, low fouling potential and specific energy consumption. The flux decline was dependent on the surface water composition but generally occurred due to concentration polarization. DK membrane showed high rejection of the charge of hydrophilic neutral PhAC evaluated, but limited rejection of Betamethasone, a more hydrophobic neutral compound. The rejection of this hydrophobic neutral compound was affected by water composition and membrane fouling.