The first full-scale nitritation-anammox process using gel entrapment technology was evaluated for nitrogen removal. Ammonia plant effluents contained not only ammonium but also methanol, an anammox inhibitor. The nitrogen concentration and loading design were 690 mg/L and 400 kg-N/d, respectively. A nitritation reactor (170 m(3)) filled with nitrification gel carriers was started up on day 20, with a resulting nitrification efficiency of 58%. A stable nitritation performance was observed without significant nitrate production for >1 year. A nitrogen conversion rate of 3.2 kg-N/m(3)/d was observed on the anammox reactor (100 m3) filled with anammox gel carrier on day 69. The full-scale anammox reactor could be started up in approximately 2 months. Subsequently, stable nitrogen removal performance was observed for >1 year. The average nitrogen loading, nitrogen conversion rate, and total nitrogen removal on the anammox reactor were 3.6 kg-N/m(3)/d, 3.0 kg-N/m(3)/d and 330 kg-N/d, respectively. The nitrogen removal performance obtained in this study will facilitate further application of the anammox processes to many types of industrial wastewater treatment. (C) 2017 Elsevier B.V. All rights reserved.