Retention of nine micropollutants covering a wide range of physical-chemical properties using polyelectrolyte multilayer hollow fiber NF membranes

• Published in: Separation and purification technology Vol. 338; p. 126495
• Main Authors: Granger-Delacroix, M., Albasi, C., Latapie, L., Vandenbossche, A., Nourrit, G., Causserand, C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 19.06.2024; Elsevier
• Subjects: Engineering Sciences; Environmental Sciences; LBL hollow fiber; Micropollutants; Nanofiltration; Wastewater; Water treatment; Nanofiltration; Water treatment; Micropollutants; Wastewater; LBL hollow fiber; LBL Hollow fiber; wastewater; water treatment; nanofiltration; micropollutants
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2024.126495

•NF using PEM membranes is efficient as tertiary treatment to retain MPs.•Organic matter in water matrix does not affect membrane performances.•Salts concentration in permeate is acceptable for reuse purpose.•Salts concentration in retentate is acceptable for further biological treatment.•Experimental design is used to correlate MPs properties to their retention. Our work investigates the efficiency of two polyelectrolyte multilayer hollow fiber nanofiltration (NF) membranes for the removal of nine micropollutants (MPs) from pre-treated wastewater. The Square Latin method was used to select the contaminants to study according to their molecular weight, hydrophilicity (log Kow), and charge at environmental pH. NF experiments were carried out in batch mode at 20 °C with a crossflow velocity of 1 m.s−1, and a transmembrane pressure of 3 bar. Retentions of MPs and salts were evaluated at various volume reduction ratios (1, 3 or 6), membrane molecular weight cut-off (400 or 800 Da) and fouling potential of the matrix (ultrapure water, synthetic water, or real pre-treated wastewater). Our study identified the 400 Da membrane as the best option as balance between MPs and salts retention was the most acceptable. With this membrane, two thirds of the investigated MPs showed a retention above 90 %, two MPs had a retention around 60 % and only one MP was retained less than 20 % while monovalent salts had a retention lower than 30 %. Our work identified size exclusion and electrostatic interactions as the main mechanisms involved in MPs retention by the negatively charged membrane. This membrane showed its efficiency to maintain high permeation flux during 24 h-filtration of stream with organic matter content comparable to secondary-treated wastewater to a volume reduction ratio up to 6. At this content, organic matter did not modify retention of micropollutants or salts. The selected membrane is an encouraging tool to produce MPs-free water from pre-treated wastewater without producing a highly saline retentate. In the future, permeate would possibly be employed for REUSE purposes.