In　this　paper,　a　submerged　membrane　adsorption　bioreactor　(MABR)　was　evaluated　for　drinking　water　treatment　at　a　hydraulic　retention　time　(HRT)　as　short　as　0.5　h.　As　powdered　activated　carbon　(PAC)　was　added　to　the　bioreactor　at　8　mg/L　raw　water,　the　MAR　achieved　much　higher　removal　efficiency　for　organic　matter　in　the　raw　water　than　the　parallel-operated　membrane　bioreactor　(MBR).　Moreover,　the　trans-membrane　pressure　(TMP)　of　MABR　developed　much　lower　than　that　of　MBR,　demonstrating　PAC　in　MABR　could　mitigate　membrane　fouling.　It　was　also　identified　here　that　the　removal　of　dissolved　organic　matter　(DOM)　in　MABR　was　accomplished　through　the　combination　of　three　unit　effects:　rejection　by　ultrafiltration　(UF)　membrane,　biodegradation　by　microorganism,　and　adsorption　by　PAC;　the　last　was　of　great　importance.　A　sludge　layer　was　observed　on　the　membranes　surface　in　both　MABR　and　MBR　and　PAC　particles　themselves　constituted　a　part　of　the　cake　layer　and　helped　to　intercept　DOM　in　the　mixed　liquor　by　adsorption　in　MABR,　especially　for　organic　molecules　of　5000-500　Da.　The　OF　membrane　together　with　the　sludge　layer　and　PAC　layer　in　the　MABR　was　able　to　reject　hydrophobic　bases　(HoBs),　hydrophobic　neutrals,　hydrophobic　acids　(HoAs),　weakly　hydrophobic　acids　(WHoAs)　and　hydrophilic　matter　(HiM)　in　the　mixed　liquor　by　40.0%,　43.9%,　71.8%,　56.6%　and　35.9%,　respectively.　(C)　2008　Elsevier　B.V.　All　rights　reserved.