Robustness and microbial consortia succession of simultaneous partial nitrification, ANAMMOX and denitrification (SNAD) process for mature landfill leachate treatment under low temperature

Abstract

The purpose of this research was to assess the feasibility of simultaneous partial nitrification, ANAMMOX and denitrification (SNAD) for mature landfill leachate treatment under low temperature. To this end, bench-scale bioreactors receiving ammonium-rich wastewater were adapted to progressively reduced temperature after 370-day operation (Period I), and subsequently acclimatized to raw leachate for 86 days (Period II). Maximum nitrogen removal rates (NRR) of 218.9, 211.9, 201.1 and 146.9 g N m−3 d−1 were achieved at 30 °C, 20 °C, 15 °C and 10 °C respectively during Period I, mainly ascribing to partial nitritation/ANAMMOX. Furthermore, the SNAD bioreactor turned out to be feasible for prolonged treatment of mature landfill leachate under 15 °C (Period II), with simultaneous degradation of nitrogen (207.9 g N m−3 d−1) and bio-refractory organics (94.9 g COD m−3 d−1) respectively. High-throughput sequencing implied that better denitrogenation performance during Period II might be ascribed to reappearance of denitrifying bacteria (9.88%) and complete suppression of nitrite oxidation bacteria (NOB), although ammonium oxidation bacteria (AOB) and ANAMMOX bacteria (AMX) decreased by 6.05% and 4.56% respectively. Furthermore, the enriched bio-refractory organics degradation bacteria (24.38%) were conductive to the performance robustness. This research presents perspective for the application of efficient treatment of mature landfill leachate under low temperature.