In this study, a pilot-scale anaerobic dynamic membrane bioreactor was operated for 142 days for treating landfill leachate. Under stable operation, average COD removal efficiency of 62.2% was achieved when the reactor was fed with the raw leachate containing total ammonium concentration above 3000 mg/L and COD above 13,000 mg/L. The methane content in the biogas was in the range of 70-90%, and the average methane yield was 0.34 L/g CODremoved at the organic loading rate of 4.87 kg COD/(m(3) d). Pyrosequencing analyses indicated that during the operation the archaeal community was relatively stable while obvious changes took place in the bacterial community. Alkaliphilus, Petrimonas, Fastidiosipila and vadinBC27 were the abundant fermentation bacteria in bacterial communities. Moreover, phylum TM6 gradually became the most dominant bacterial community and reached the highest relative abundance of 32.9% as the operation elapsed. In archaeal communities, genus Methanosarcina was identified as the dominant methanogen. (C) 2014 Elsevier Ltd. All rights reserved.