LAUSR

Abstract Fouling mechanisms inside polyethersulfone hollow fiber membranes during mini-plant filtration tests using microalgae-loaded feed water were modeled. Multiple filtration cycles tests were conducted in dead-end mode at conditions analogous to full-scale operation conditions using four microalgae species, individually employed in intact and lysed conditions, without prior separation of algae cells, cell debris and algal organic matter (AOM). Fouling mechanisms’ contributions, fouling rates and fouling resistances per one cycle were statistically quantified employing classical pore blocking filtration and resistance-in-series models via special algorithm. The results were reliably correlated to main microalgae feeds’ characteristics (i.e., AOM composition, average size distribution, conformation), retention of AOM substances, besides morphology and nature of the formed fouling layer. Standard blocking and intermediate blocking mechanisms resulted rather in irreversible fouling. Nature of intermediate fouling mechanism was interestingly altered based on microalgae characteristics, and consequently, influencing fouling reversibility and overall membrane performance. Helical microalgae cells tended to block membranes’ pores causing strong fouling, while rectangular and cylindrical microalgae cells showed a combined fouling phenomenon (competitive blocking of membrane pores and fouling layer voids). Moreover, cake filtration mechanism rather contributed into better fouling reversibility; however, microalgae feeds having high hydrophobic organic carbon and biopolymers contents, strong irreversible fouling was revealed, irrespective of cake filtration mechanism contribution.