New insights into co-treatment of mature landfill leachate with municipal sewage via integrated partial nitrification, Anammox and denitratation

As a low consumption and high efficiency process, Partial Nitrification-Anammox/denitratation (PNAD) was applied to co-treat mature landfill leachate with municipal sewage for 300 days. Specifically, ammonia (670.2 +/- 63.7 mg N/L) contained in mature landfill leachate was firstly oxidized to nitrite (611.5 +/- 28.1 mg N/L) in sequence batch reactor (SBRPN); meanwhile, organic matter in municipal sewage was partially removed in another reactor (SBROMR); finally, nitrite produced (611.5 +/- 28.1 mg N/L) in SBRPN and ammonia (53.1 +/- 6.4 mg N/L) residing in pretreated municipal sewage were simultaneously degraded through combined Anammoxdenitratation process in an up-flow anaerobic sludge bed (UASBAD). A satisfactory effluent quality of 10.3 mg/L TN was obtained after long-term operation, with Anammox and denitrification contributing to 86.2% and 5.8% nitrogen removal efficiency, respectively. Mass balance confirmed 67.2% nitrate generated from Anammox could be reduced to nitrite and in-situ reused. Anammox bacteria genes and nitrate reductase/nitrite reductase ratio were highly detected, accelerating combined Anammox-denitratation. Further, Ca. Brocadia triumph among various Anammox bacteria groups, increasing from 1.2% (day 120) to 3.6% (day 280).

Automated summary

The study applied Partial Nitrification-Anammox/denitratation (PNAD) process to co-treat mature landfill leachate with municipal sewage for 300 days, achieving satisfactory effluent quality with Anammox and denitrification contributing to main nitrogen removal efficiency. The study also confirmed that nitrate generated during the process could be reduced to nitrite and reused, highlighting the potential for sustainable nitrogen removal.