In the present study, short-term effects of zinc on anammox activities and long-term effect of zinc on the performance of simultaneous partial nitrification, anammox and denitrification (SNAD) process were evaluated. The anammox activity decreased with increasing zinc concentration and exposure time in short-term tests. The IC50 value of zinc was found to be 6.9 mg/L. However, the presence of zinc (<10 mg/L) in wastewater stimulated the microbial activities and nitrogen removal performance of SNAD process in sequencing batch biofilm reactor (SBBR). At first, inhibition of SNAD process was observed when influent zinc concentration increased to 20 mg/L. The system recovered immediately, suggesting the acclimatization of microbial communities of SNAD process. The results showed that SBBR was well acclimatized under high zinc concentration (50-100 mg/L) achieving 98% NH4+-N, 96% TN and 87% COD removal efficiencies. (C) 2014 Elsevier Ltd. All rights reserved.