Advanced nitrogen removal from landfill leachate via a two-stage combined process of partial nitrification-Anammox (PNA) and partial denitrification-Anammox (PDA)

In this study, a two-stage combined process of partial nitrification-Anammox (PNA) and partial denitrification-Anammox (PDA) was established achieving advanced nitrogen removal from landfill leachate. The PNA sludge used to treat reject water adapted to the leachate in 37 days, resulting in fast start-up of the PNA process with a nitrogen removal rate (NRR) of 022 kgN/(m(3)-d). Partial denitrification (PD) was induced using sodium acetate and proceeded in a stepwise manner using sludge fermentation liquid (SFL), achieving a NO3--N to NO2--N transformation ratio (NTR) of 52.1 +/- 1.1% within 16 days. PDA was established via the addition of mature Anammox biofilms. The nitrogen removal efficiency (NRE) of this system was 97.6 +/- 1.5%, of which PNA and PDA contributed 74.8 +/- 4.0% and 18.7 +/- 4.1%, respectively. Nitrosomonas (2.6% in PNA), Thauera (16.0% in PDA) and Candidatus Brocadia (23.0% in PNA, 1.4% in PDA) were dominant in the two-stage system. This study provides valuable and novel insights, supporting the practical application of PNA-PDA processes in landfill sites. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study established a two-stage combined process of partial nitrification-Anammox (PNA) and partial denitrification-Anammox (PDA) for advanced nitrogen removal from landfill leachate. The system achieved high nitrogen removal efficiency (NRE), with PNA and PDA contributing significantly. The study provides valuable insights for the practical application of PNA-PDA processes in landfill sites.