The　mini-pilot　experiments　of　submerged　membrane　bioreactor　(sMBR)　for　the　drinking　water　treatment　from　a　slightly　polluted　surface　water　supply　was　conducted　for　more　than　110　days,　with　a　hydraulic　retention　time　of　0.5　h.　Perfect　ammonia　removal　(by　89.4%)　were　achieved　by　the　sMBR　through　the　biological　nitrification.　However,　the　capacity　of　the　sMBR　for　organic　matter　removal　was　demonstrated　to　be　low.　The　average　removal　efficiencies　for　TOC,　CODMn,　DOC,　UV254,　and　corresponding　THMFP　and　HAAFP　were　28.6%.　33.5%,　21.5%.　15.1%,　34.1%　and　24.7%,　respectively,　though　much　higher　removal　of　51.7%　and　54.9%　were　obtained　for　BDOC　and　AOC,　respectively.　A　sludge　layer　was　observed　on　the　OF　membrane　surface　in　the　sMBR.　The　sludge　layer　could　provide　additional　filtration　for　dissolved　organic　matter　(DOM)　in　the　mixed　liquor,　especially　for　organic　molecules　in　the　range　of　5000-500Da.　Fractionation　of　DOM　indicated　that　the　sludge　layer　together　with　the　OF　membrane　had　the　ability　to　reject　hydrophobic　neutrals,　hydrophobic　acids,　and　weakly　hydrophobic　acids　by　45.0%,　42.7%　and　48.1%,　respectively;　whereas　hydrophobic　bases　and　hydrophilic　organic　matter　were　separated　mainly　by　the　OF　membrane,　with　the　efficiencies　of　11.3%　and　14.6%.　respectively.　(C)　2008　Elsevier　B.V.　All　rights　reserved.