Three Upflow Anaerobic Sludge Blanket (UASB) reactors were compared for Anammox enrichment using synthetic wastewater with Spherical Plastic (SP) and Bamboo Charcoal (BC) addition, and without carrier (CK). After four months of operation, the Anammox activity occurred in all reactors allowing continuous removal of ammonium and nitrite. Ammonium and nitrite removal efficiencies were all higher than 98% in steady phase with the effluent concentrations below 1 mg L(-1). The start-up time could be shortened from 117 to 97 d in CK and SP reactor to 85 d in BC amendment reactor. Quantitative PCR (q-PCR) analyses indicated a significant increase in the number of Anammox bacteria in BC amended reactor as compared with CK and SP during the entire start-up periods. The copy numbers of Anammox of 16S rRNA gene in the reactor with BC amendment could reach up to 6×10(9)copies g(-1) Volatile Suspended Solids, around 22.5 times and 12.3 times greater than that in CK and SP reactor, respectively. BC addition could accelerate the start-up of Anammox and significantly increase the Anammox bacteria number.