Abstract
In the process named SNAP (Single-stage Nitrogen removal using Anammox and Partial Nitritation), influent ammonium was removed as nitrogen gas by the combination of two autotrophic steps, partial nitritation and anammox, in one unit process. The reactors were packed with acryl-resin fiber biomass carriers and gently aerated. The synthetic influent, simulating secondary-treated landfill leachate, contained ammonium concentrations of 240 mg-N/l and 500 mg-N/l for reactors named SN-2 and SN-3, respectively. Data from 300 days of SNAP operation using reactor SN-2 showed ammonium conversions of 47.7∼88.1% with nitrogen removal rates of 0.31∼0.45 kg-N/m3/d under various operational conditions. The best performance with loading rate of 0.6 kg-N/m3/d was obtained at 35°C, pH 7.8, and aeration rate of 0.10 vvm (volume per volume per minute), with 88.1% ammonium conversion and 78.5% nitrogen removal. The results of about 100 days of operation for reactor SN-3 confirmed the treatment capability of SNAP process, with about 80% nitrogen removal with loading rates up to 1.0 kg-N/m3/d. Some important characteristics of the SNAP process are discussed.
