Membrane filtration has been widely applied for water treatment, wastewater reclamation and seawater desalination. Although extensive research work has been conducted to better understand the fouling mechanism under various conditions, little has been known about the transparent exopolymer particles (TEP)-associated membrane fouling at different Na(+) concentrations. In this study, the influence of Na(+) concentration on the TEP formation as well as the filtration behaviors of alginate blocks was investigated. Results showed that increasing Na(+) concentration substantially reduced the TEP formation from all types of alginate blocks, thus preventing the cake layer development on the membrane surface. As a result, the TEP-associated membrane fouling was found to be kinetically slower and much less at higher Na(+) level. Furthermore, filtration tests of alginate blocks at freshwater and seawater conditions were also conducted, showing that TEP-associated fouling in freshwater is much server than that in seawater at the defined conditions. This study reveals that the TEP formation is significantly influenced by the chemistry condition of bulk solution and membrane fouling is profoundly affected by the TEP levels in feed water.