A swim-bed reactor for partial nitritation with polymeric coagulant treatment and an UASB reactor for anammox were applied to the treatment of livestock manure digester liquor. The partial nitritation was maintained for 32 days under a 1.6 kg N/m(3)/d nitrogen loading rate (NLR) with an average conversion efficiency of 51%, and achieved 1.65 kg N/m(3)/d of the maximum nitrite production rate under 2.58 kg N/m(3)/d of NLR. Although 200 mg/L of TOC remained in the effluent of the partial nitritation reactor, the anammox nitrogen removal rate was not significantly decreased and a relatively high rate of 2.0 kg N/m(3)/d was obtained under a NLR of 2.2 kg N/m(3)/d. 16S rRNA gene analysis showed that Nitrosomonas and KSU-1 were dominant in the partial nitritation and anammox reactor, respectively. The results of this study demonstrated that the partial nitritation-anammox process has possibility of applying to the nitrogen removal of livestock manure digester liquor. (C) 2010 Elsevier Ltd. All rights reserved.