Characterisation of feed and membrane properties for industrial ultrafiltration management

The effective industrial management of ultrafiltration (UF) membranes requires an assessment of the impact of feed and membrane characteristics on fouling behaviour in complex feed scenarios. However, this assessment is limited by current understanding of (a) the utility of common foulant characterisation tools for the detection of organic fouling propensity, and (b) the impact of membrane modification and increasing chemical age on fouling behaviour. To assess commonly applied foulant characterisation methods, fluorescence excitation emission (FEEM) spectroscopy and liquid chromatography organic carbon detector (LC-OCD) were used to characterise proteins of distinct morphologies and protein-polysaccharide mixtures. The tools provided insights into protein fouling behaviour influenced by protein aggregation and protein-polysaccharide interactions, however, additional characterisation using zeta potential and contact angle was required to account for fouling mechanisms involving electrostatic and hydrophobic interactions. To assess the impact of membrane characteristics on fouling behaviour, three different polyvinylidene fluoride (PVDF) membranes with modified membrane pore size and surface roughness were compared. An optimal pore size was found to provide both low filtration resistance and low fouling by pore blocking, while low surface roughness could enhance physical fouling reversibility. When the three membranes were tested with accelerated sodium hypochlorite (NaOCl) ageing, all were found to display an aggravated fouling rate with increasing chemical exposure. The membrane with small original pore size and roughness presented lower degradation with chemical age and higher resistance to loss in membrane selectivity. Lastly, the combined assessment of feed and membrane characteristics was extended to a complex feed scenario. Advanced characterisation of extracellular organic matter (EOM) from four algae species was used to lend insights into the subsequent fouling behaviour of EOM with each of the three PVDF membranes. For two algae species, the fouling behaviour was primarily impacted by membrane pore size and roughness. For the other algae species, fouling was found to be dependent on complex biopolymeric interactions in the feedwater elucidated using advanced characterisation methods. This study revealed the limitations of common characterisation tools for the detection of fouling propensity and proposed advanced protein and carbohydrate characterisation to understand fouling mechanisms. Furthermore, the study demonstrated the value of tuning membrane pore size and roughness to optimise operation for both short-term filtration and long-term performance with chemical ageing in industry.

Grantor dc:publisher

UNSW, Sydney

Year dc:date

2022

Author dc:creator

• Mustafa, Zainab

• ultrafiltration
• organic characterisation
• fouling
• protein
• algal organic matter
• membrane ageing
• carbohydrate
• anzsrc-for: 400411 Water treatment processes
• anzsrc-for: 400409 Separation technologies

Statement dc:rights

• open access
• CC BY 4.0
• free_to_read

Licence

• https://purl.org/coar/access_right/c_abf2
• https://creativecommons.org/licenses/by/4.0/

Language dc:language

en

Identifier

https://doi.org/10.26190/unsworks/24133

OAI identifier oai:identifier

oai:unsworks.library.unsw.edu.au:1959.4/100426