An integrated approach to enhance and maintain high anammox activity and abundance in an upflow anaerobic sludge blanket (UASB) treating low strength wastewater under moderate and low temperatures was developed. A quantitative PCR assay showed the abandance of anammox bacteria to be 1.68 +/- 0.08 x 10(9) copies/ml in mixed liquor when the temperature was 30 degrees C and was maintained at the level of 1.93 +/- 0.41 x 10(9) copies/ml in mixed liquor at 16 degrees C. A nitrogen removal rate (NRR) of up to 5.72 kg N/m(3)/d was achieved with a hydraulic retention time (HRT) of 0.12 h at 30 degrees C, while nitrite and ammonium removal efficiencies were 94.35% and 92.81%, respectively. NRR decreased with a decrease in temperature and was maintained at 2.28 kg N/m(3)/d with an HRT of 0.28 h when at 16 degrees C, while nitrite and ammonium removal efficiencies were 92.31% and 78.45%, respectively. The emission rate of the greenhouse gas N2O was below 0.006% of the NRR in the anammox UASB reactor treating low strength wastewater. (C) 2012 Elsevier Ltd. All rights reserved.