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 (SBR); meanwhile, organic matter in municipal sewage was partially removed in another reactor (SBR); finally, nitrite produced (611.5 ± 28.1 mg N/L) in SBR and ammonia (53.1 ± 6.4 mg N/L) residing in pretreated municipal sewage were simultaneously degraded through combined Anammox-denitratation process in an up-flow anaerobic sludge bed (UASB). 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).