Environmental impact comparison of four options to treat the cellulosic fraction of municipal solid waste (CF-MSW) in green megacities

•Environmental impacts of four different waste management methods for CF-MSW.•Category indicators used are the renewable energy used and greenhouse gas emissions.•Gasification (223%) and AD (195%) renewable energy were better for leaf waste.•AD (1454%) and Gasification (715%) GHG emissions were better for grass waste. Megacities are characterized by a high urban population density, and timely solid waste management is crucial for the wellbeing of its citizens. In this study, the cellulosic fraction of municipal solid waste is the target for management in Singapore (which has one of the highest population densities in the world) using four pertinent options – incineration, anaerobic digestion, gasification and composting. The energy sustainability and environmental impacts in the form of greenhouse gas emissions are considered for each scenario together with the status quo to achieve the most favorable recommendation, with a sensitivity analysis in the case that no bio-fertilizers are allowed for use locally. In terms of GWP and energy profile for grass waste, AD is the most environmentally friendly option (2 kilo tonnes of CO2-eq and 23.3 GWh respectively), while for leaf waste, gasification is the best, with AD a close second.