CRI 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 curbsite.

“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 report describes the evolution of single-stream recycling in the United States, the recent downturn in the scrap market for all recyclable materials, and explains factors affecting collection costs. 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.

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. 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.

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.

The historical focus of residential recycling (in the 1990’s) has been on keeping materials out of landfills. This led to creating systems that could collect the greatest volume of material, with less of a focus on final end-use of the materials.

In an effort to increase recycling volumes and reduce high recycling collection costs, the waste management sector created single stream recycling collection, which increases efficiencies by collecting more material with less labor and less distance traveled. Automated single stream collection can reduce the number of employees, improve route efficiency, and reduce workers compensation costs. Single stream can encourage residents to place more material in their recycling bin by giving them a larger bin and by simplifying the system.

Glass is the material most affected by the amount of breakage in each type of collection system.

In single-stream programs, it is virtually impossible to prevent glass from breaking as it goes to the curb, is dumped in the truck, gets compacted, gets dumped on the tipping floor of the MRF, is driven over by forklifts, and is dumped on conveyor belts to be processed by the MRF. 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.

Only 40 percent is recycled into containers and fiberglass. About one third of the non-recyclable glass is broken glass, too small to separate for recycling, some of which can be used for sandblasting base, aggregate material, or Alternative Daily Cover (ADC). These ―down-cycled uses do not have the same savings in terms of energy conservation and avoided emissions. In contrast, dual-stream systems have an average yield of 90 percent, and container-deposit systems yield 98 percent glass available for use in bottlemaking.

In general, the final commodities from single stream programs will be more contaminated than those that are collected in a dual-stream system or sorted at the curb. This contamination increase often results in the commodity being worth less than cleaner material, and can create problems at paper mills, leading to equipment failure, lost productivity and expensive repairs. In other words, the cost savings for a municipality from single-stream collection show up as cost increases for the processors and remanufacturers. The contaminants are thrown away by the paper mills. So an item, such as a plastic bottle that was recyclable when it was placed at the curb, becomes trash by the time it is sorted as a contaminant by the paper mill.

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 analyzed recovery rates for three single-stream and four dual-stream programs in that province. The study found that a drop in collection costs sees a commensurate rise in processing costs. In a recent article, Lantz concluded that the supposed benefits of single-stream systems over dual-stream do not outweigh their costs.

―In summary, with increased processing costs and lost revenues in total far exceeding collection savings in most instances (and zero under alternating-week collection), overall single-stream recycling does not show the cost advantage that was originally anticipated. As well, the expected increases in capture rate are also not apparent. Overall, dual-stream recycling still appears to be more advantageous.

In spite of these challenging conditions and their impact on the current demand for recyclables, recycling continues to be a vital component of a national strategy to conserve resources, supply the manufacturing base and reduce greenhouse gas emissions, toxics and waste going to landfills and incinerators.

Manufacturers of new glass, metal, plastic and fiber products continue to encourage clean collection so that they can use secondary feedstock instead of virgin material for remanufacturing. While manufacturers will continue to invest capital into their systems to increase recycled inputs, these investments will remain contingent upon a regular supply of clean material.

The upstream environmental benefit of remanufacturing materials is 10 to 20 times greater than downcycled or disposal options.

More simply put, when a product is made from recycled material, the use of virgin materials is not required. Therefore, all the upstream energy and associated environmental impacts from the extraction, transport and processing of those virgin materials are not required, or ―avoided.