Elemental sulfur-driven autotrophic denitrification for advanced nitrogen removal from mature landfill leachate after PN/A pretreatment

Elemental sulfur-driven autotrophic denitrification (S0dAD) was applied in a packed-bed reactor to remove residual nitrogen from raw mature landfill leachate after partial nitritation and anaerobic ammonium oxidation (anammox) (PN/A) pretreatment. The performance stability of S0dAD were evaluated with different NOx? (nitrate nitrite) loadings hydraulic retention time (HRT) at 15–28 °C over an operational period 240 days. Stable high removal efficiency (NRE) 96.6 ± 1.9% determined under stepwise decrease HRT (from 9 h 2 h), resulting low total concentrations 24.0 3.9 mg-N/L the effluent. circumneutral pH, associated efficient elemental sulfur supply, facilitated maintain NRE S0dAD, which contributed 86.3% reactor. Biomass highly enriched sulfur-oxidizing bacteria (SOB) (58.4%), including predominant genus Thiobacillus (47.7%) two less-abundant genera Sulfurimonas (4.5%) Sulfurovum (5.5%). This study highlights potential implementation coupled PN/A process for advanced carbon-deficient ammonium-laden wastewater, particularly leachate.