Removal of pharmaceutically active compounds from water sources using nanofiltration and reverse osmosis membranes: Comparison of removal efficiencies and in-depth analysis of rejection mechanisms

Trace organic compounds from effluent streams are not completely removed by conventional purification techniques and hence, contaminating groundwater sources. Herein, we report the removal efficiency and rejection mechanisms of three common pharmaceutically active compounds (PhACs); caffeine (CFN),...

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Bibliographic Details
Published in:Journal of environmental management 2023-07, Vol.338, p.117682-117682, Article 117682
Main Authors: Matin, Asif, Jillani, Shehzada Muhammad Sajid, Baig, Umair, Ihsanullah, I., Alhooshani, Khalid
Format: Article
Language:English
Subjects:
Filtration - methods
Membrane fouling
Membranes, Artificial
Nanofiltration
Organic micropollutants
Osmosis
Rejection mechanism
Size exclusion
Water
Water Purification - methods
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Summary:Trace organic compounds from effluent streams are not completely removed by conventional purification techniques and hence, contaminating groundwater sources. Herein, we report the removal efficiency and rejection mechanisms of three common pharmaceutically active compounds (PhACs); caffeine (CFN), omeprazole (OMZ), and sulfamethoxazole (SMX), using commercial nanofiltration (NF) and reverse osmosis (RO) membranes with different surface characteristics. The RO membranes showed near-complete removal of all PhACs with rejection rates >99%. On the other hand, retention capabilities for the NF membranes varied and were influenced by the characteristics of the PhACs, membranes, and the feed solution. In general, during long-term testing, the rejection did not show much variation and followed a trend compatible with the size exclusion (steric hindrance) mechanism. When a real matrix was used, the rejection of CFN by the more tight NF membranes, HL TFC and NFW decreased by ∼10%, whereas the removal of SMX by the loose NF membrane, XN45, increased by the same ratio. In short-term testing, the rejection of negatively charged SMX increased significantly (∼20–40%) at a higher pH of ∼8 and in the presence of salts. Fouling by the PhACs was more severe on the high-flux NF membranes, HL TFC and XN45, as witnessed by the significant change in Contact angle (CA) values (∼25–50°) as well as the flux decline (∼15%) during long-term testing. To summarize, the removal of PhACs by membranes is a complex phenomenon and depends upon a combination of several factors. •Removal efficiency of PhACs by RO membranes >99%.•For NF membranes, rejection varies from ∼40% to 95%.•Size exclusion is dominant mechanism in short- and long-term testing.•In real matrix, the changes in rejection for CFN and SMX by XN45 are opposite.•Feed pH and chemistry has most influence on SMX rejection.
ISSN:0301-4797
1095-8630
DOI:10.1016/j.jenvman.2023.117682