The objective of this paper deals with the preparation, characterization and application of novel hydrophilic coatings on commercial ultrafiltration polyethersulphone (PES) membranes. Coating was obtained by modifying commercial membrane surface increasing its smoothness, hydrophilicity and giving a high antimicrobial activity. Novel membranes with a great potential in wastewater treatment, and in particular in MBRs application , were, thus, obtained and tested. Preliminary characterization tests were directed to investigate: membrane morphology by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM), surface properties by contact angle measurements (CAM), antimicrobial activity and antifouling behavior. SEM analyses showed an interconnected structure of the coating made up of an interwoven network of polymeric channels alternated with cylindrical voids. From AFM analyses it was demonstrated the very smooth surface of the coating responsible (together with the relative high hydrophilic antimicrobial surface) of the antifouling property of the membrane. From CAM, commercial membranes presented a contact angle of about 68° while novel membranes showed a contact angle of about 47°. A reduction of about 30% in contact angle values was found. The higher degree of hydrophilicity resulted in better performances in terms of water permeability and foulant rejection. Antifouling activity of the coating was proved by using a model foulant compound such as humic acid (HA) for filtration tests. After 24h of filtration, with a subsequent backflushing, PES commercial membranes showed a clear tendency to be affected by fouling (it was observed by the deposition of a dark layer on membrane surface). On the contrary, modified novel membranes were less prone to fouling phenomenon especially towards the irreversible type. Finally, the prepared coated membranes were assembled in a module and they were applied in a submerged MBR where they were tested with model textile dye wastewater. Two different dyes, Acid Red and Remazol Brilliant Blue, were used and their rejection was determined. The novel coated membranes showed a dyes removal efficiency higher (around 20%) than the commercial ones. Furthermore, also the COD removal efficiency for the novel coated membranes was higher (more than 7%). Therefore, this novel coating, can be considered as a promising membrane surface modification technology for potential application in MBR process for wastewater treatment. Acknowledgement The work was funded by BioNexGen (grant agreement no. CP-FP- 246039-2) EU-FP7/project
Novel Hydrophilic and Antifouling Coatings for Membrane Bioreactor (MBR) Application
F Galiano;AFigoli;
2014
Abstract
The objective of this paper deals with the preparation, characterization and application of novel hydrophilic coatings on commercial ultrafiltration polyethersulphone (PES) membranes. Coating was obtained by modifying commercial membrane surface increasing its smoothness, hydrophilicity and giving a high antimicrobial activity. Novel membranes with a great potential in wastewater treatment, and in particular in MBRs application , were, thus, obtained and tested. Preliminary characterization tests were directed to investigate: membrane morphology by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM), surface properties by contact angle measurements (CAM), antimicrobial activity and antifouling behavior. SEM analyses showed an interconnected structure of the coating made up of an interwoven network of polymeric channels alternated with cylindrical voids. From AFM analyses it was demonstrated the very smooth surface of the coating responsible (together with the relative high hydrophilic antimicrobial surface) of the antifouling property of the membrane. From CAM, commercial membranes presented a contact angle of about 68° while novel membranes showed a contact angle of about 47°. A reduction of about 30% in contact angle values was found. The higher degree of hydrophilicity resulted in better performances in terms of water permeability and foulant rejection. Antifouling activity of the coating was proved by using a model foulant compound such as humic acid (HA) for filtration tests. After 24h of filtration, with a subsequent backflushing, PES commercial membranes showed a clear tendency to be affected by fouling (it was observed by the deposition of a dark layer on membrane surface). On the contrary, modified novel membranes were less prone to fouling phenomenon especially towards the irreversible type. Finally, the prepared coated membranes were assembled in a module and they were applied in a submerged MBR where they were tested with model textile dye wastewater. Two different dyes, Acid Red and Remazol Brilliant Blue, were used and their rejection was determined. The novel coated membranes showed a dyes removal efficiency higher (around 20%) than the commercial ones. Furthermore, also the COD removal efficiency for the novel coated membranes was higher (more than 7%). Therefore, this novel coating, can be considered as a promising membrane surface modification technology for potential application in MBR process for wastewater treatment. Acknowledgement The work was funded by BioNexGen (grant agreement no. CP-FP- 246039-2) EU-FP7/projectI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
