Lifecycle Process Model for Municipal Solid Waste Collection

Abstract

A process model was developed using a lifecycle approach to estimate the cost and energy use associated with municipal solid waste collection, which is the most fuel-intensive and often the most costly aspect of solid waste management. The model divides collection service areas into single-family residential, multi-family residential, and commercial sectors with sector-specific, user-defined characteristics, including population, waste generation, and waste composition. Waste is collected by a set of processes (e.g., residual waste, recyclables collection) defined by costs, collection activity parameters, and energy use. The model overpredicted fuel use by ~25% compared with data obtained from actual single-family residential collection routes and their average fuel efficiencies, but was within 10% when modal fuel efficiencies (e.g., driving, idling) were considered. Adding recyclables or yard waste collection to a mixed waste collection program increased fuel consumption by approximately 75% per metric ton (Mg) and doubled cost, whereas adding both services more than doubled fuel use and tripled cost. Increasing recyclables and residual collection frequency from biweekly to weekly resulted in a predicted 53% increase in fuel consumption and 39% increase in cost. Sensitivity analysis illustrated the relative impact of changing individual parameters (e.g., route to disposal facility distance, average time at each stop) and highlighted the need for a mechanistic model that is responsive to variations in input values.