Comparative Study of Conventional and Ultrafiltration Pretreatment Methods in Desalination Plants: Case of Beni Saf and El Mactaa Stations, Algeria

Pretreatment is a critical phase in the reverse osmosis desalination process, ensuring the compatibility of feed water with membrane specifications and preventing fouling caused by suspended solids, microorganisms, or scaling. This study presents a comparative analysis between conventional pretreatment using sand, anthracite, and cartridge filters and ultrafiltration-based membrane pretreatment, with a specific focus on the Silt Density Index (SDI) as an indicator of performance. The findings reveal that while ultrafiltration provides higher unit availability, conventional treatment offers more stable SDI values and reduced operational complexity. These insights are based on data collected from two large desalination plants in Algeria: Beni Saf and El Mactaa. Ultimately, the results suggest that conventional pretreatment remains more effective under variable raw water conditions common in Algerian coastal regions.