Micellar　enhanced　ultrafiltration　is　a　promising　technology　for　removing　trace　amounts　of　organic　pollutants　in　wastewater,　but　membrane　fouling　caused　by　Gemini　micelles　is　a　significant　problem　restricting　its　industrial　application.　In　this　study,　a　flat　sheet　ultrafiltration　membrane　with　four　types　of　Gemini　surfactant　systems　and　various　feed　concentrations　was　used　to　treat　phenol　wastewater,　while　the　flux　behavior　and　fouling　mechanism　were　investigated.　The　optimal　permeate　flux　of　phenol　decreased　in　the　sequence　as　follows:　CG(12)　＞　CG(16)　＞　CG(12)　-　Brij35　＞　CG(16)　-　Brij35.　In　order　to　study　the　rate　of　membrane　fouling,　a　developed　liner　regression　method　was　utilized　to　help　determine　the　threshold　flux,　as　well　the　degree　of　concentration　polarization　and　membrane　fouling.　Furthermore,　limiting　flux　was　investigated　to　avoid　extensive　cake　layer　formation.　Threshold　flux　and　limiting　flux　strongly　depended　on　the　feed　concentration　and　the　type　of　micelles.　The　threshold　flux　reduced　gradually　with　feed　concentration,　due　to　the　increased　fouling　rate　and　presence　of　irreversible　fouling.　Owing　to　the　effect　of　charge　density　and　hydrophobicity　of　micelles,　CG(12)　exhibited　the　highest　threshold　flux　and　limiting　flux.　Flux-TMP　relation　was　divided　into　three　regions　for　analyzing　the　corresponding　changes　of　permeate　flux,　filtration　resistance　and　conceptual　particle　deposition　model.　Besides,　fouling　mechanism　of　MEUF　was　discussed.　This　study　provides　a　guideline　for　analyzing　membrane　fouling　and　seeking　an　optimum　operation　strategy　for　controlling　fouling　in　membrane　water　treatment.　(C)　2015　Elsevier　Ltd.　All　rights　reserved.