A Life-Cycle Analysis of Alternatives for the Management of Waste Hot-Mix Asphalt, Commercial Food Waste, and Construction and Demolition Waste.

Abstract

Effective management of commercially generated food waste presents an opportunity for avoided global warming potential, renewable energy production, and renewable agrochemical production. The vast majority of food waste is landfilled, but source separated collection of the organic fraction of municipal waste is becoming more common. Currently in the US, food waste that is not buried in a landfill is aerobically composted and the end product has the potential to be used as a soil amendment that can replace mineral fertilizers or other agrochemicals. In Europe, anaerobic digestion (AD) of organic wastes is more common. AD facilities produce methane that can be used as an energy source. The residual from AD can also be used as a soil amendment similar to what is produced at composting facilities. An LCI was performed for food waste processed through several aerobic composting systems, an AD facility, and a landfill with and without energy recovery. The functional unit was one ton of food waste plus 0.6 tons of yard waste. The yard waste was considered because it is used as a bulking agent in food waste composting processes. The AD alternative was superior in every category due to the efficient collection of the methane generated and its conversion to energy. The two landfilling alternatives resulted in the highest GWP although the landfill with energy recovery alternative had the second lowest emissions and energy use. The composting alternatives were superior relative to the landfilling without energy recovery alternative. C&D waste is solid waste generated during the construction, renovation, or demolition of buildings and other structures. A life-cycle model was developed to evaluate two alternatives for the management of C&D waste; (1) recycling (2) and landfill disposal. The C&D waste LCI considered the recovery of ten materials present in a mixed C&D waste stream. All of the materials except for wallboard and miscellaneous materials are recovered for beneficial use. All of the recovered materials except for wood are assumed to replace virgin materials. Wood is assumed to be burned in a co-fired coal plant to produce electricity. The results of this analysis indicate that recovering mixed C&D leads to significant reductions in emissions, energy use, and GWP when compared to landfill disposal of mixed C&D waste.