Abstract
Single stream recycling (SSR) is the process by which accepted recyclable materials including paper, plastics, glass, and metals are collected in a single container. SSR has become popular compared to other curbside recycling programs within the U.S. due to its advantages, such as reduced collection cost and increased public participation in recycling programs. Despite these advantages, SSR programs suffer from an increased risk of cross contamination due to the mixing of recyclable and non-recyclable materials together in a single collection bin. High levels of contamination affect the quality of the inbound recyclable materials, and subsequently increase the time it takes material recovery facilities (MRFs) to separate recyclable and non-recyclable materials, raising the overall operational cost. In this dissertation, the impact of SSR on the inbound contamination (IC) rate was investigated to compare the mean IC rate between SSR and Dual Stream Recycling (DSR) across multiple counties in the South and Southeast of the U.S. Utilizing a one-way ANOVA test, a statistically significant difference was observed in the mean IC rate, and SSR was observed to yield a higher IC rate when compared to that of DSR. SSR was further investigated for the statistical significance of the difference between the mean IC rates of the counties that implemented SSR. To further understand the difference in the contamination rate between counties, the relation between contamination and the demographics of these counties was analyzed to identify which demographics were associated with increasing the contamination rate. Regression analyses were employed to investigate the relationship between key demographics—such as poverty rate, population size, median age, median household income, and proportions of different ethnicities—and the IC rate. The results indicated that population, poverty rate, median household income and proportion of African American residents are associated with increasing the IC rate in the considered geographic region. The most significant factor impacting the IC rate was the poverty rate. These demographic findings can aid in the selection of specific areas for educational practices aimed at reducing the IC and increasing processing efficiency in SSR, which could be particularly effective when the most significant factor is considered.