Parameter-sensitive life cycle assessment of sludge incineration technologies integrating energy balance model

Incineration is vital for safe sewage sludge treatment and resource recovery in China, using methods like mono-incineration (INC), and co-incineration in coal plant (CINP), cement kiln (CINC), and municipal solid waste incineration plant (CINM). Existing studies suffer from poor inventory quality and inaccurate quantification. To overcome these challenges, this study integrates the energy balance model with life cycle assessment to evaluate key system parameters, quantify co-incineration disturbances, and assess environmental impacts. Findings indicate critical moisture content for combustion as 70 %, 60 %, 50 %, and 80 % for the four methods, respectively, with INC exhibiting the highest environmental impact, followed by CINM. CINP and CINC yield environmental benefits by replacing coal or raw materials, achieving negative carbon effects of 34.8 % and 78.8 %, and avoiding 66.4 % and 76.1 % of environmental impacts, respectively. When sludge moisture surpasses 75 %, co-incineration results in higher carbon emissions than INC, with lower dry calorific values potentially increasing emissions up to fourfold. The study positions CINP and CINC as transitional solutions, with CINM as the future trend, while INC suits cities with high sludge output and strong economies. This research offers a basis for developing inventories for solid waste co-incineration in industrial kilns and optimizing the selection of sludge incineration technologies.