The aim of this study was to investigate the coagulation performances in different algal systems, and effects of algal morphology and composition of extracellular organic matter (EOM) on membrane flux were also investigated. The results indicated that Al-13 generated the largest flocs, and strength factor and recovery factor were also largest. The results of ultrafiltration experiments also showed that the floc size and the concentration of Soluble Microbial Products (SMP) may be the main decision factors in the membrane fouling process. Al species distribution was important in removing EOM in the coagulation process. SMP in EOM could be effectively removed by Al-13 and Al-30, so the membrane fouling could be alleviated due to the larger removal efficiency of SMP. The roughness of the sediment layer formed by Al-13 was largest, and the sediment layer would adsorb and intercept more algae organic matter. (C) 2017 Elsevier B.V. All rights reserved.