This　study　compared　the　removal　of　fifteen　trace　organic　contaminants　(TrOCs)　by　aerobic　and　anaerobic　membrane　bioreactors,　denoted　as　AeMBR　and　AnMBR,　respectively.　Results　show　that　the　removal　of　TrOCs　by　either　AeMBR　or　AnMBR　was　determined　largely　by　their　hydrophobicity.　Almost　all　hydrophobic　TrOCs　were　effectively　removed　(＞60%)　while　the　removal　of　hydrophilic　compounds　varied　(3.6%-98.7%).　AeMBR　was　more　effective　than　AnMBR　for　the　removal　of　all　TrOCs　investigated　with　a　few　exceptions.　Compared　to　AeMBR,　the　removal　of　compounds　containing　nitrogen　in　their　molecular　structures　(e.g.　amitriptyline,　carbamazepine,　and　atrazine)　was　higher　by　AnMBR.　Of　all　TrOCs　investigated,　considerable　accumulation　in　biosolids　only　occurred　to　amitriptyline,　4-tert-octyphenol　and　triclosan,　particularly　during　AnMBR　treatment.　Nevertheless,　biodegradation　and/or　biotransformation　was　the　main　mechanism　for　TrOC　removal　by　both　AeMBR　and　AnMBR.　Moreover,　removal　of　bulk　organic　matter　indicated　by　total　organic　carbon　and　nitrogen　was　comparable　for　these　two　systems.　(C)　2019　Elsevier　B.V.　All　rights　reserved.