Integrated solid waste management alternatives in consideration of economic and environmental factors: A mathematical model development and evaluation

Integrated management of municipal solid waste (MSW), potentially generated by multiple sectors with varying waste compositions, can be a complex task when considering a wide range of options for waste collection, transfer, sorting for material recovery, treatment (e.g., anaerobic digestion, composting, and combustion), and disposal. Also, increasing environmental awareness is calling for environmentally more benign strategies that include recycling and/or other beneficial use of MSW. Given the large number of combinations of unit processes and the mass flows among them, identification of a cost-effective strategy to meet these demanding MSW management goals is becoming exceedingly challenging.; The primary objective of this dissertation is to develop a quantitative framework to aid in decision making for integrated MSW management. The core of this framework consists of a large linear programming (LP) model whose decision variables represent the choice of unit processes and the mass flow of each waste item through them. This integrated solid waste management (ISWM) model also allows a flexible framework to represent many site-specific issues and considerations. Both cost and environmental objectives are incorporated. The environmental objectives are defined in terms of life cycle inventories of energy and emissions (of CO, fossil and biomass derived CO₂, NO_x, SO_x particulate matter, PM₁₀, and greenhouse gases) associated with MSW management strategies. These are characterized in individual unit process models by relating the quantity and composition of waste entering a unit process to the cost, energy consumption and environmental emissions for that process. The net savings in environmental releases realized at the manufacturing facilities that use recycled material instead of virgin materials are also included. These savings are represented as the difference in energy and emissions between the recycle-based manufacturing process and the production process utilizing virgin material. Similarly, the savings in environmental releases associated with energy recovery from some unit processes (e.g., from waste combustion and beneficial use of landfill gas) and the avoidance of generation of an equivalent amount of energy generated from fossil fuels are included.; The application of this ISWM model is demonstrated through hypothetical, but realistic case studies. Several MSW management scenarios that are typically of interest to municipalities in the US are studied. Through these illustrative applications, the flexibility and capabilities of the ISWM model are demonstrated.