A single-stage partial nitrification-anammox (PN/A) reactor treating low-strength swage was operated for 288 days to investigate the recovery of nitrogen removal from nitrate accumulation. The reactor was quickly started up by inoculating anammox sludge. However, nitrite oxidizing bacteria (NOB) abundance gradually increased on day 25, leading to high effluent nitrate concentration. Two strategies were executed to control the effluent nitrate. In strategy I, dissolved oxygen (DO) concentration was kept low (0.17 +/- 0.08 mg/L), but nitrate production increased from 4.71 to 38.18 mg-N/L. In strategy II, intermittent aeration operation mode (aeration 7 min/anoxic 21 min) was adopted, which significantly lowered the nitrate concentration to 1.3 mg-N/L, indicating the NOB was inhibited. The high nitrogen removal rate of 73 mg-N/(L.d) was achieved. The evolution of bacterial activity and abundance verified the changes of the nitrogen removal performance and proved the intermittent aeration strategy could successfully solve the problem of nitrate build-up in the PN/A process. (C) 2016 Elsevier Ltd. All rights reserved.