The novel microbial process such as anaerobic ammonium oxidation (Anammox) and completely autotrophic nitrogen removal over nitrite (Canon) processes is promising biotechnology to remove nitrogen from ammonium-rich wastewater like anaerobic sludge liquid. In this research, a new Canon-type nitrogen removal process adopting upflow granular sludge bed configuration was investigated on its feasibility and process performance, using synthetic wastewater and sludge digester liquids. Air as an oxygen source was provided in an external aeration chamber with flow recirculation. In the first experiment using the synthetic wastewater (up to 110 mg NH4-N L-1), the ammonium removal was about 95% (92% for T-N) at HRT for 5 days. In the second experiment using the sludge digester liquids (438 +/- 26 mg NH4-N L-1), the total nitrogen removal was 94 +/- 1.7% at HRT for 7 days and 76 +/- 1.5% at HRT for 5 days, respectively. Little nitrite and nitrate were observed in the effluent of both experiments. The process revealed quite lower oxygen (0.29-0.59 g O-2 g(-1) N) and less alkalinity (3.1-3.4 g CaCO3 g(-1) N) consumption as compared to other new technology in microbial nitrogen removal. The process also offers the economical compact reactor configuration with excellent biomass retention, resulting in lower cost for investment and maintenance. (c) 2006 Elsevier Ltd. All rights reserved.