Nitrogen removal from old landfill leachate with SNAP technology using biofix as a biomass carrier

Single-stage nitrogen removal using Anammox and partial nitritation (SNAP) is a novel technology developed in recent years for removing nitrogen. To evaluate the ability of SNAP technology to remove nitrogen in old landfill leachate under the conditions in Vietnam, we conducted a survey with 7 different nitrogen loading rates of 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4 kg-N/m3 day and a concentration from 100 to 700 mg-N/L. The operating conditions were as follows: DO at 1.0–5.3 mg/L, HRT at 12 h, and pH at 7.5–7.8. The biomass carrier was a biofix made from acrylic fiber. The maximum ammonium conversion and nitrogen removal efficiency were approximately 98% and 85%, respectively, at 1.2 kg-N/m3 day. In general, the nitrogen removal efficiency increased and stabilized at the end of each loading rate. The first step showed that SNAP could potentially be applied in real life for removing nitrogen from old landfill leachate.