Analysis of material recovery facilities for use in life-cycle assessment. (January 2015)

• Record Type: Journal Article
• Authors: Pressley, Phillip N.; Levis, James W.; Damgaard, Anders; Barlaz, Morton A.; DeCarolis, Joseph F.
• Is Part Of: Waste management. Volume 35(2015)
• Page Start: 307
• Page End: 317
• Publication Date: 2015-01
• Subjects: Recycling -- Material recovery facility -- Life-cycle assessment -- Municipal solid waste; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2014.09.012
• Languages: English
• ISSNs: 0956-053X

Abstract

Highlights: Life-cycle assessment of solid waste management relies on accurate process models. Material recovery facility (MRF) processes were modeled with new primary data. Single stream, dual stream, pre-sorted, and mixed waste MRFs were considered. MRF electricity consumption ranges from 4.7 to 7.8 kW h per Mg input. Total cost ranges from $19.8 to $24.9 per Mg input. Abstract: Insights derived from life-cycle assessment of solid waste management strategies depend critically on assumptions, data, and modeling at the unit process level. Based on new primary data, a process model was developed to estimate the cost and energy use associated with material recovery facilities (MRFs), which are responsible for sorting recyclables into saleable streams and as such represent a key piece of recycling infrastructure. The model includes four modules, each with a different process flow, for separation of single-stream, dual-stream, pre-sorted recyclables, and mixed-waste. Each MRF type has a distinct combination of equipment and default input waste composition. Model results for total amortized costs from each MRF type ranged from $19.8 to $24.9 per Mg (1 Mg = 1 metric ton) of waste input. Electricity use ranged from 4.7 to 7.8 kW h per Mg of waste input. In a single-stream MRF, equipment required for glass separation consumes 28% of total facility electricity consumption, while all other pieces of material recovery equipment consume less than 10% of total electricity. The dual-stream and mixed-waste MRFs have similar electricity consumption to a single-stream MRF. Glass separation contributes a much larger fraction of electricity consumption in a pre-sorted MRF, due to lower overall facility electricity consumption. Parametric analysis revealed that reducing separation efficiency for each piece of equipment by 25% altered total facility electricity consumption by less than 4% in each case. When model results were compared with actual data for an existing single-stream MRF, the model estimated the facility's electricity consumption within 2%. The results from this study can be integrated into LCAs of solid waste management with system boundaries that extend from the curb through final disposal.