Step-feeding reactor establishment for advanced nitrogen removal from mature landfill leachate via double anammox process with pure floc sludge.

To address the engineering challenges of high costs, NO sensitivity, and carrier dependency are associated with traditional nitrogen removal processes for treating mature landfill leachate (MLL), this study developed an innovative step-feeding double anammox process. By establishing a pure floc sludge system with gradient carbon source allocation strategy, the nitrogen removal mechanisms under several influent distribution ratios (1:1:1, 4:4:2, 5:3:2) were systematically investigated. The system achieved an anammox contribution of 91.