Abstract: To address the challenge of carbon emission reduction in putrescible waste treatment during urbanization, this study conducted Life Cycle Assessment (LCA) of three typical putrescible waste treatment plants in Hangzhou to quantify carbon emissions and comprehensive environmental impacts across the entire chain (pretreatment-anaerobic digestion-wastewater treatment). The results indicated that the carbon emissions per 1.00×104 t of putrescible waste treated ranged from -82.83 t to 150.29 t (in terms of carbon dioxide equivalent). Grid electricity consumption and wastewater discharge were identified as the main sources of carbon emissions, with grid electricity (primarily coal-based) contributing over 58% of the system’s total. The use of hydrochloric acid and methanol were the primary contributors to carbon emissions from wastewater discharge, with hydrochloric acid accounting for approximately 65% of the carbon emissions in the wastewater treatment stage at Plant A, and methanol contributing above 75% at Plant B. Grid-connected electricity from biogas power generation could offset 9% to 220% of carbon emissions, highlighting energy recovery efficiency was a crucial pathway for emission reduction. For the three plants, the main environmental risks were human carcinogenic toxicity, freshwater ecotoxicity, and marine ecotoxicity. The primary source of these risks was wastewater treatment for Plant A, and gutter oil treatment for Plant B. Grid electricity consumption was a notable contributor to the environmental impact across all three plants.

Key words: Life Cycle Assessment (LCA), putrescible waste, anaerobic digestion, carbon emissions, environmental impact