Fahimeh Rahimi - Department of Environmental Management, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran.
Farideh Atabi - Department of Environmental Engineering, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran.
Jafar Nouri - Department of Environmental Management, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran.
Ghasem Ali Omrani - Department of Environmental Engineering, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran.

Introduction: In Tehran with a population of ۹ million currently, about ۲.۵ million tons municipal solid waste have been producing annually. Materials and Models: In this study by using Life Cycle Assessment (LCA) model an optimal system of waste management of Tehran was recommended. Based on the quantity and quality of waste in Tehran in ۲۰۱۳ and facilities, three scenarios were selected. First, current status (۱۵% compost, ۵% recycling and ۸۰% landfill), second, the maximum use of the capabilities of waste of Tehran (۷۰% compost, ۲۰% recycled and ۱۰% landfill ) and third, the optimal scenario according to conditions of Tehran (۵۵% compost, ۱۰% recycling, ۵% energy recovery and ۳۰% landfill). The IWM model and WRATE model was used for Phase II and Phase III, respectively. Results: Results of the conducting second Phase showed in compared to the first scenario by the second and third scenario, the amount of emissions was decreased ۶۴% and ۷۲%, respectively. The third phase results showed the third scenario has the lowest environmental impact in chosen six impact groups. Conclusion: Considering the quality and quantity of wastes in Tehran and also the current facilities, conducting the third scenario could be useful for reducing emissions, the external costs and environmental impacts.

Life Cycle Assessment, Waste Management, Greenhouse Gas, Environmental Impact, Landfill.