Mitigating membrane fouling in an internal loop airlift membrane photobioreactor containing Spirulina platensis: effects of riser cross-sectional area and hydrophilic baffles.

Membrane photobioreactors (MPBRs) have gained significant attention due to their ability to support microalgae activities such as cultivation, harvesting, and production of beneficial products. Despite various efforts to mitigate membrane fouling, a fundamental issue in membrane processes, in these systems, a cost-effective and less energy-consuming method is still needed. This study examines the impact of the cross-sectional area of the riser and the baffle material on membrane fouling in an internal loop airlift MPBR. The use of hydrophilic polyester-polypropylene (PES-PP) baffles proves to be more effective than plexiglass baffles. Specifically, in configurations with d = 0.7 cm and d = 1.4 cm, R_C/R_T decreased by approximately 20% and 13%, respectively, compared to plexiglass baffles. As for the values of R_P/R_T at a distance of d = 0.7, nearly a 5% increase was observed, and at a distance of d = 1.4, an increase of approximately 11% was observed. This is due to the development of the cake layer on the matrix structure of the PES-PP baffles instead of the membrane itself. The most optimal outcomes were reached while working with PES-PP at a distance of 0.7 cm, as it prolonged the membrane fouling time to 46 h.