Recycling's real purpose is remanufacturing and end use. Most lay people, and perhaps most local officials, assume that all recycled items go to their best use. They are shocked to learn that the materials they dutifully put in a recycling bin may in fact wind up in a landfill. Unfortunately single stream recycling decreases the chances of the recycled materials being remanufactured.
The key to achieving the environmental and economic benefits of recycling is to keep the material circulating for as many product lives as possible. This is the closed loop that reduces the need for virgin materials, thus avoiding the energy consumption and greenhouse gas emissions associated with primary materials extraction, transportation and processing.
The case supporting Double Stream recycling is outlined below in excerpts from an article in American Recycler:
Container Recycling Institute releases study on impact of single stream recycling
The Container Recycling Institute (CRI) has undertaken a study of the impact of single stream collection of residential recyclables. CRI selected Clarissa Morawski, principal of CM Consulting, to research the issue. Morawski reviewed 60 previously published studies, reports and articles in trade publications. The report finds that there are many negative downstream impacts of contaminated stock due to the mixing of the materials at curbside.
“Basically, the report confirms that you can’t unscramble an egg,” explained CRI executive director Susan Collins. “Once the materials are mixed together in a single-stream recycling system, there will be cross contamination of materials and glass breakage. These issues then result in increased costs for the secondary processors.”
The real purpose of the study, however, is to examine the impacts of single stream recycling, as compared to other methods, on every step of the recycling process, including:
- Initial ease of collection and collection costs;
- Contamination rates and overall material yield at material recovery facilities (MRFs);
- Impacts on material yield at paper mills;
- Impacts on yield at plastics processors;
- Impacts on paper mills, on quality, quantity, equipment maintenance and costs;
- Impacts on aluminum processors on contamination levels, resulting equipment shutdowns, and profit losses;
- Impacts on glass, including color mixing, suitability for certain end-uses, and increased operating costs; and,
- Impacts on plastic quality and costs.
Ensuring that secondary recovered recyclables are utilized for the highest possible end-use is a critical part of successful diversion. For plastic, high-end uses can have ten to twenty times the environmental benefit in terms of the replacement of virgin materials and those avoided upstream impacts. Using glass to make containers saves much more energy than using recycled glass for other purposes.
On average, 40 percent of glass from single-stream collection winds up in landfills, while 20 percent is small broken glass used for low-end applications. In contrast, dual-stream systems have an average yield of 90 percent, and container-deposit systems yield 98 percent glass available for use in bottle making.
A study conducted in 2002 by Eureka Recycling (of St. Paul, Minnesota) compared five different collection methods, and found that single-stream collected 21 percent more material than the baseline method. However, the study did not ultimately recommend a single-stream system, because the lower collection costs were outweighed by higher processing costs and lower material revenues.
In another study, Daniel Lantz of Ontario, Canada-based Metro Waste Paper Recovery concluded that the supposed benefits of single-stream systems over dual-stream do not outweigh their costs.
?In summary, in most cases, increased processing costs and lost revenues far exceed collection savings.