Environmental assessment of municipal solid waste composting: comparing landfilling and incineration scenarios towards a sustainable approach

Driven by the high content of organic materials in municipal solid waste (MSW) of 70% in Iran and the growing demand for mineral fertilizer, refinement of composting technology is imperative. In the pursuit of environmental sustainability, further investigation into the life cycle assessment of the composting process and end-of-life waste management must be conducted. Hence, this study scrutinizes the environmental burdens of the composting plant operation from cradle to gate. Because 50% of raw MSW was not converted to compost, its final disposal was evaluated based on incineration, landfill, and integrated approaches. The results indicated marine and freshwater ecotoxicity of the composting process (>50.4 kg 1,4-DB eq). Heavy metal and gas emissions during the MSW decomposition were the pivotal parameters for most impact categories. Carbon dioxide emission intensified climate change by 3,523 kg CO2 eq; however, waste incineration led to emission savings of 98.75%. The environmental benefits of incineration were observed in 13 impact categories alongside a net-negative value for natural land transformation. Landfilling also induced savings in freshwater eutrophication and metal depletion by 98.67% and 99.08%, respectively. Unlike previous studies relying on generalized data, this study uses detailed plant-level operational data and scenario-based modeling from Sistan and Baluchistan province. This approach provides realistic impact estimates and decision-relevant insights.