Adaptation of pilot-scale one-stage partial nitritation and anammox process to kitchen waste digestion liquid and mature landfill leachate

This study, for the first time at pilot scale, demonstrated efficient nitrogen removal from kitchen waste digestion liquid (KWDL), mature landfill leachate (MLL), and their mixtures using a one-stage partial nitrification/anammox (PN/A) process. Nitrite-oxidizing bacteria (NOB) were effectively suppressed under low dissolved oxygen (DO) and in-situ generated high free ammonia. During KWDL treatment, the PN/A system achieved ∼ 90 % total nitrogen (TN) and 70 % chemical oxygen demand removal. However, MLL toxicity and elevated DO (due to equipment issues) inhibited anammox activity, enabling NOB resurgence and lowering TN removal. By reducing DO and MLL flow, anammox activity was restored, with TN removal recovering to ∼ 85 %. Over 80 % TN was consistently removed from KWDL-MLL mixtures at 1:1 and 3:1 ratios. Microbial analysis revealed major community shifts under long-term KWDL and MLL exposure. Overall, the study highlights the flexibility and promise of anammox-based nitrogen removal for diverse wastewaters.