The more, the dirtier. That's the cynical take on curbside recycling. But letting community residents toss aluminum cans, glass bottles, discarded catalogs and plastic milk jugs into a single bin does accomplish the task of capturing more recyclables and extending the life of landfills. Often, "single stream" also is cheaper to collect for a municipality or private hauler.
The trend has stirred anxiety among aluminum recyclers, paranoid about plastic residue, and papermakers leery of bits of glass.
"The movement toward single stream has allowed for larger quantities and a greater variety of recyclables to be picked up. They're not only taking newspaper but corrugated cardboard, magazines, office-grade paper and junk mail," said Lori Scozzafava, deputy executive director of the Solid Waste Association of North America. As for plastics, "communities are expanding to narrow-neck containers and we're even seeing some moving into yogurt cups and deli containers."
The result is a heavier burden on materials recovery facilities (MRFs). They do the separating and cleaning that turns the stuff into usable—and usually saleable—commodity streams. The strategies and investment choices of MRFs determine whether single-stream product matches the quality standards of dual-stream facilities.
Two factors have made single stream increasingly common, according to Lisa Skumatz, principal and founder of Skumatz Economic Research Associates Inc., Superior, Colo. One is support for that approach from sophisticated MRF owners with deep pockets. Another is the significant cost savings from more-efficient collection.
"Dual-stream facilities tend to be older and some have aging capital equipment and technology. Some dual-stream facilities that have been retrofitted to single stream report lower contamination, partly because the retrofit provided an opportunity to upgrade old-tech container sorting lines. Concerns about declining product quality and contamination have been an industry issue and some have associated it with single-stream," according to a study by Skumatz's consulting firm. "Generally, if retrofitted with similar equipment, then contamination at new dual-stream facilities might be lower than those achieved at new single-stream facilities, but the lesson has been that contamination is not clearly a single-stream, dual-stream issue; quality is related to equipment, cost and management attention."
For single stream, "the real growth started in 2000," Skumatz said. "Waste Management made a corporate commitment—it was going to go single stream. A lot of the counties went to single stream because there was pressure for collection efficiencies."
Picking up two or even three types of recyclables in separate bags or containers requires greater effort and more specialized equipment. If a double-stream system uses bins, they generally are smaller than for single stream and might fill up before collection day. And according to one comparison cited by Scozzafava, an automated single-stream truck can stop at 171 households an hour vs. just 130 for a dual-stream configuration.
For a sense of single stream's complexities, one can look at the transition in Boulder County, Colo., where EcoCycle, a nonprofit company running Boulder's MRF, has been handling the outreach. Part of its message to the public is that "one of the challenges to single-stream recycling is the increase in contamination. Folks tend to get a little recycling happy, tossing additional items into the bin. But sending us non-recyclable materials jeopardizes the success of the whole program."
How prevalent is single stream in the United States right now? "Our estimate is that it covers approximately 15 percent of the U.S. population," Skumatz said. She doesn't expect single stream to displace dual stream across the board, given that dual stream is less capital intensive and more labor intensive. "It's a very local issue. If we're talking about small, isolated communities in Colorado, for example, it's very possible it would stay a mom-and-pop, lower-tech and lower-capital-cost operation. "
The past few years created unrealistic expectations about the profitability of recycling curbside materials, Scozzafava said, and that has led to exaggerated disillusionment about falling prices among counties and municipalities with short memories.
"We experienced tremendously positive markets. Obviously it's better if you get revenue for it. But it's not that long ago that many communities were paying their MRFs" to take recyclable materials," she said, adding that municipal recycling traditionally has been a method for keeping landfill costs low and attaining public policy goals. Expecting revenue every year from every recycling stream is unrealistic.
For an MRF's marketed bales to satisfy mills and end consumers on quality requires attention to several variables, Skumatz said. "Line speed is one. Management care and attention is another. In some cases you need one extra step at the end, to do one more cleaning. The third is more education for households on what is acceptable."
Skumatz thinks scrap consumers were timid about letting quality scores influence their pricing and acceptance decisions. When demand was high, product was needed and MRFs were treated alike, particularly if there wasn't a long-term contract with the company receiving the can scrap or waste paper.
"Now, when there's not so much demand, is the time that the people who have been cleaning up the material have been waiting for, because buyers can be choosier," she said. In the long run, if product quality is a priority, users of scrap need to create stronger market incentives for clean, well-sorted shipments. PAUL SCHAFFER