Removal of pharmaceutically active compounds by using low-pressure membrane processes

[EN] The increasing demand on water resources throughout the world has motivated researchers to seek new ways to obtain quality water increasing their interest in water reclamation. However, the presence of harmful organic chemicals such as pharmaceutically active compounds (PhACs) is a serious environmental concern. The objective of this study was to investigate the influence of the pH on the rejection of seven target PhACs (acetaminophen, caffeine, erythromycin, ibuprofen, naproxen, sulfamethoxazole, and trimethoprim) by different low-pressure membranes within the fine ultrafiltration (UF) and loose nanofiltration (NF) range. For this purpose, three ceramic membranes and a polyamide membrane were used for UF and NF experiments, respectively. Experimental results indicated that PhACs with negative charge were effectively rejected at basic conditions (< 75% for UF, < 90% for NF), improving both their hydrophilicity and solubility with increasing pH. Furthermore, high soluble PhACs with high pKa values showed low rejection values (similar to 15% for UF, similar to 30% for NF) and a pH-independent behaviour during low-pressure filtration experiments. Therefore, the use of low-pressure membranes could be considered as an appropriate and sustainable supplemental technique to remove PhACs in a wastewater treatment plant.
The authors of this work wish to gratefully acknowledge the financial support from the Spanish Ministry of Economy and Competitiveness through the project CTM2013-42342-P.