Separation and Energy Use Performance of Material Recycling Systems

URL to conference websiteThis paper outlines current research on the performance of recycling processes and systems. Several aspects of performance are explored, including the separation performance and energy use of recycling processes. Descriptive terminology for separation performance is presented. The goal of this project is to develop a basic understanding of the factors affecting the separation and energy performance of recycling systems, with the eventual ambition of developing techniques for predictive analysis of these systems. These analysis techniques will allow us to evaluate the economic, ecological, and energy impact of recycling systems. This increased understanding will help guide the design of products and recycling systems.National Science Foundation (U.S.) (# 0423484

Tracking trash

Using active self reporting tags we were able to follow the journey of 2,000 objects through the waste management system of Seattle. We used this data to define measures of efficiency for what could be called the ‘removal chain’. We found that over 95% of the traces reached a compliant end destination. However, there were concerns with special categories of waste (cellphones, e-waste, and household hazardous waste) and specific geographic locations (trash from Bellevue and Redmond in particular did not follow the recommended best practices). We believe that similar studies may increase knowledge and systemic performance of waste management systems and, at a personal level, reduce the ‘out of sight out of mind’ attitude to trash

Modeling and Design of Multi-stage Separation Systems

Interest in recycling has surged in recent years due to shifting material costs, environmental concerns over material production and disposal, and laws in many countries designed to improve material recycling rates. In response, recycling systems are becoming more complex as increasing material recovery is required from products with complicated material mixtures such as WEEE (Waste Electric and Electronic Equipment). One common approach to increasing system separation performance is the use of multi-stage separation systems. The problem of estimating the performance and designing multi-stage separation processes has rarely been tackled from a system engineering perspective, resulting in poor integration and sub-optimal configuration of industrial multi-stage separation systems. This paper presents a systematic approach to modeling and analyzing multi-stage separation processes. Individual separation processes modeled as Bayesian binary separation steps are incorporated into network models through mass flow rate equations. The model can be used to evaluate the performance of these multi-stage separations under varying conditions, informing decisions about system configuration and process performance. Several basic examples demonstrate the utility of this model for design decisions. The industrial value is demonstrated through a real case study featuring PET plastic and aluminum flake separation in the beverage container recycling industry

Putting matter in place: measuring tradeoffs in waste disposal and recycling

Reliable information on trash disposal is crucial but becomes difficult as waste removal chains grow increasingly complex. Lack of firm data on the spatial behavior of waste hampers effective recycling strategy design. In particular, the environmental impact of electronic and household hazardous waste is poorly understood. Our study investigates waste processing in an environmental, economic, and geographic context, using novel methods to track municipal solid waste in the city of Seattle (WA). We observed the movement of 2,000 discarded items using attached active GPS sensors, recording an unprecedented spatial dataset of waste trajectories. We both qualitatively identified facilities visited along each item's trajectory, then statistical modeled characteristic transportation distance and the likelihood of ending up at a specific type of facility by product categories, place of disposal, and collection mechanism. We show that a) electronic and household hazardous waste items travel significantly longer and have more arbitrary trajectories than other types of waste and b) that existing models for waste emissions may underestimate the environmental impact of transportation by not accounting for very long trajectories