Solid Waste Management: A Comparative Carbon Footprint and Cost Analysi

As the world's urban population continues to grow, the need to efficiently manage the resulting solid waste generation will become increasingly important. Currently, most of the world's solid waste is landfilled or disposed of in open dumps. Landfilling organic solid waste leads to the production of methane, which is a strong greenhouse gas (GHG). In addition, urban areas with high densities and limited open land may find it hard to accommodate large landfill footprints. Thus, increased awareness of climate change and landfill diversion has prompted many municipalities and solid waste planners to find synergistic waste management alternatives to landfilling. However, waste management strategies vary from region to region, so site-specific data and analysis are often required to determine appropriate waste management options. A carbon footprint study using life cycle analysis (LCA) was conducted to compare multiple scenarios of organic waste management strategies for two cities: Fort Collins, Colorado, USA and Todos Santos, Baja California Sur, Mexico. Fort Collins is a progressive city within the developed world, and has a strong green ethic, whereas Todos Santos is considered to be in the developing world, where resources are not as abundant and financial limitations exist. LCA is a cradle-to-grave analysis tool designed to assess the environmental impacts of a process. A side-by-side comparison of GHG emissions associated with site-specific organic waste management options was conducted for each city. Along with the environmental impacts, the economic aspects of waste management are important in any city, especially Todos Santos. Thus, a cost analysis of compost facilities and recycling was conducted for Todos Santos.;In Fort Collins, four scenarios were compared to the status quo of landfilling organic waste, deemed the No-Action Scenario. The four scenario were: Scenario AD 1 - anaerobic digestion of commercial food waste, and the remainder of organic waste being composted regionally using a transfer station; Scenario AD 2 - anaerobic digestion of commercial food waste with co-generation, with the remainder of organic waste being composted regionally without using a transfer station; Scenario Regional Compost with TS - Regional compost of all organic waste using a transfer station; and Scenario Regional Compost without TS - Regional compost of all organic waste without using a transfer station. The functional unit was one metric ton (Mg) of organic waste diverted from the landfill. The only environmental impact category analyzed was GHG emissions expressed as kg CO2 equivalents; thus, this study is referred to as carbon footprint, instead of a full ISO standard LCA. Scenario AD 1 was found to produce the least GHG emissions (130.7 kg CO2 equivalents/functional unit), followed by Scenario AD 2 (168.8 kg CO 2 equivalents/functional unit), Scenario Regional Compost with TS (197.1 kg CO2 equivalents/functional unit), Scenario Regional Compost without TS (249.8 kg CO2 equivalents/functional unit), and finally the No-Action Scenario produced the most GHG emissions (780.4 197.1 kg CO 2 equivalents/functional unit).;Todos Santos does not have an engineered landfill. Solid waste is collected and transported to an open dump on the outskirts of the city. Two different scenarios were compared to the status quo, or No-Action Scenario, of landfilling organic waste. The scenarios were: Scenario Local WC - Organic waste is composted locally at the current landfill using windrow composting); and Scenario Local SAC - Organic waste is composted locally using static aeration composting. The functional unit and environmental impact categories were the same as the Fort Collins analysis. Scenario Local WC produced the lowest GHG emissions (101.5 kg CO2 equivalents/functional unit), followed by Scenario Local SAC (153.9 kg CO2 equivalents/functional unit), and finally the No-Action Scenario produced the most GHG emissions (1,487.9 kg CO 2 equivalents/functional unit). The lack of LFG capture at the current landfill explains the high GHG emissions.;This study found that landfilling without LFG capture produced the most GHG emissions in both a developed, environmentally progressive city, and a city in a developing country with economic and cultural restraints surrounding sustainable waste management. Furthermore, this study highlighted the need for site-specific analysis when assessing waste management improvements for a city or municipality. Transfer stations and efficient waste collection will vary by location, but are important to quantify as transportation plays a key role in waste management. In addition, selecting feasible alternatives to the status quo will require conversations with stakeholders and assessment of site-specific data, ideally before any assessment is conducted. (Abstract shortened by ProQuest.).