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Many companies have converted to single-stream processing of recyclables to respond to market demands and improve return on investment. When planned and implemented effectively, single-stream recycling can make a material recovery facility (MRF) more profitable. It can also better protect the environment than curb sorting or dual-stream recycling can by making it easier for the public to make more recyclable material available. According to a study conducted in 2005 by the American Forest and Paper Association (AF&PA), about 27% of the US population with curbside collection had access to a single-stream collection program in 2005 compared with 10% in 2000. The impetus for this increase has been market forces (i.e., greater collection efficiency than curbside sorting or dual-stream collection can provide). MSW companies have responded to these market forces by investing in single-stream separation equipment that gives them more control over variable costs in their endpoint or transfer station MRFs than they have on the curbside. However, the key factor in making a single-stream MRF more profitable is the design and engineering of the facility. Several experts recently discussed several factors to consider in making the conversion to single-stream separation a profitable one. Cost Control Close to Home Reducing collection costs is the main incentive for adopting a single-stream process, says Nat Egosi, president of Melville, NY–based RRT Design & Construction, which provides processing-technology implementation for the solid waste, paper, and recycling industries. “It depends on the program, but in most cases ... they do get an increase in recovery rates. But that’s not the main reason why they would change,” Egosi says. “It would be to reduce the cost of collection. The driver can do many more stops, and, therefore, fewer vehicles are required to serve a geographic area because he can do more homes, assuming there’s no growth.” Drivers’ collection efficiency can more than double under single-stream collection. This process involves only one trip to and from the curbside—or no trip at all if the truck and bins are equipped for automated pickup and emptying—to empty a bin holding paper and commingled glass, metal, and plastic containers. In dual-stream collection, the driver must make two trips back and forth to the truck to empty one bin holding papers and another holding commingled containers. Curbside sorting is even less efficient due to the time spent separating material at each stop. John Pausma is recycling manager at Diversified Recycling, a division of Homewood Disposal Service Inc. in Homewood, IL. The company converted to single-stream collection in July 2000 following a transition from curbside sorting to dual-stream collection shortly before that. He argues that converting away from curb sorting and dual-stream collection is motivated by a need to do what is necessary to reduce high collection costs. “Collection costs in a curb-sort program are ridiculously high,” he points out. “In general, I think, haulers have wanted to collect single-stream since the inception of recycling. The limiting factor was always the lack of processing facilities to handle single-stream material in an effective manner. “Another benefit from the hauler’s perspective is increased diversion,” Pausma continues. “Every additional ton of recycling that can be captured results in reduced landfill tipping fees. Studies have clearly shown that most communities see a significant increase in recycling participation.” Public service announcements informing the public that all recyclables can be commingled increase diversion rates, Pausma adds, as do the larger containers afforded by single-stream collection. “Going with a 65-gallon-cart or preferably a 90-gallon-cart system allows for significantly more capacity than most bin programs and generally results in a much higher recycling tonnage,” he notes. Bob Cordell, facility manager at Groot Industries in Elk Grove Village, IL, says single-stream collection has yielded labor cost savings in two areas since the company converted from dual-stream collection in 2003. “It went from picking up bins and putting them on a recycling truck with two compartments—separated paper and commingled plastics and bottles—to allowing us to use a regular garbage truck, which holds almost twice the value as a recycling truck,” he says. “So there are labor savings on the street and there are labor savings in the process—we find it to be a lot more efficient.” Where the Costs Shift Collection costs certainly should be lower with single-stream collection. However, new costs can emerge further downstream in processing. “When residents are told to put everything together into one stream, we typically see a significant increase in the amount of non-recyclables, where residents just put a lot of things into their containers in conjunction with their recyclables. So the design of the plant now has to accommodate a larger amount of non-recyclable material going through the facility,” Egosi argues. “The second thing we see is that there tends to be a higher level of participation and a higher quantity of material in general, because when you convert to single-stream, the residents are given larger containers. When they’re given larger containers, there’s more room for them to put in material that otherwise would not go into the recycling container. “For example, I think under general circumstances, a person would know that the solar cover on a swimming pool, although it’s plastic, is not something that’s part of a recycling program,” Egosi continues. “A Christmas tree that’s plastic and artificial is probably not something that’s part of a recycling program—these are things that are pretty obvious to most people who are part of a recycling program, but there are people who don’t get it.” Separating trash from recyclables invariably requires manual labor because many pieces of trash and recyclables share similar shapes. This added labor requirement in the processing stage of single-stream recycling cuts into the increased profit margins attained in collection; the extent is determined by how efficiently the processing facility is designed and engineered to sort the recyclables. Cordell notes that since Groot Industries converted to single-stream collection, it has been using trash haulers instead of recycling trucks. The trash haulers’ higher capacity increases Groot’s return on investment because fewer trucks are required for collection. “We went through a learning curve with citizens and communities seeing a garbage truck picking up their recycling,” Cordell says. “They’d ask, ‘What are you doing, taking it to the landfill?’ No, we’re just picking up recycling that way now. There was a bit of a perception issue at first, but that’s gone away now.” Single-stream collection has raised some concerns about recycled-paper quality, with some studies indicating that newsprint recycled with single-stream processing results in greater contamination by such material as plastic film and glass. “It is a particular issue with single-stream processing; it’s also an issue with any type of recycling program,” says Egosi. “Some paper mills are better suited to handle some glass than others, but in all cases, any amount of glass in paper is not a good thing. It’s an expense to the paper mill, and therefore the paper mill, by incurring that expense, devalues the paper it receives. That ultimately means the MRF is penalized [in the form of a lower newsprint price] for providing a lower-quality paper to the mill, and in some cases mills are so uninterested in having this lower-quality material that they don’t even want the material at all.” The reputation that single-stream systems have for higher contamination rates is not universal, though. “That was probably true in the earlier systems. I don’t see it to be true anymore because, for example, there are newspaper mills that process curbside material that have gone to single-stream systems,” says Cordell. “That ought to tell you something right there. We deal with some pretty picky mills, and we’ve never had complaints.” “The nature of processing single-stream material is complex and, if not done correctly, has the potential to result in contaminated products,” Pausma notes, adding that some dual-stream systems have also produced a fair amount of contaminated material. “Does that mean we should paint all single-stream MRFs with a broad brush? I hope not. Many single-stream MRFs have produced and are producing quality products.” When all is said and done, Pausma believes single-stream processing is a superior alternative from a profitability standpoint. “As a processor, we made the transition to single-stream because we recognized the desire of the haulers to move in this direction, and the equipment technology was finally available to make this move make economic sense,” he points out. “Everyone would like to collect single-stream—it’s quicker and easier, and it can use the existing fleet of garbage trucks—and it has automation potential,” Pausma continues. The question becomes one of economics for the hauler. Do the cost savings on the collection side outweigh the reduction in recycling payback value [due to MRFs’ higher processing prices]? In most cases the answer is yes. “We’re extremely happy with it,” Cordell says of Groot’s separation system. “It can be a little maintenance-intensive because you have to change the disks so often, but it’s definitely an economic trade-off that we realize with labor savings.”
Facility Design Is Crucial “If you have a facility that was not engineered or designed correctly because it was an existing facility that you converted to single-stream and you don’t have the physical room to deal with these items, then you’re going to be in trouble,” says Egosi. “But if you have a brand-new facility, it’s very easy to engineer and design the facility to accommodate these issues. [Retrofitting] is more difficult if the people who are doing the retrofitting do not engineer and design the facility to take this into consideration. “For example, when you have more of this material, that means you have more material that’s not going to go to a recycling market; it’s going to go to a landfill,” Egosi continues. “So if your facility, your site, and the way you’re handling this trash material is such that you’re anticipating only 4% or 5% of that material and now it ends up being maybe 10%, 15%, or 20%, there’s a lot more volume of material that needs to be handled. If you don’t have the physical space to handle it, accumulate it, densify it, and then have it removed from the site in a timely fashion, it can become a bottleneck.” Cordell and Groot Industries did manage to retrofit their existing facility in a large industrial park near Chicago without falling behind in processing an increased recycling volume of about 20%. Due to space restrictions, it was necessary to construct part of the sorting system on the tipping floor. In the redesigned facility, haulers pull up to the tipping area and dump their loads. The material is processed by a series of screens consisting of multiple rubber disks attached to horizontal shafts. The disks are shaped somewhat like saw blades, except that the teeth are much larger and fewer in number. The spacing of the disks on these screens can be adjusted, as can the upward angle of the screens according to the material being separated. As the shafts turn, the disks on the first screen separate cardboard from the remainder of the material by carrying the cardboard to the end of the screen while the other material falls to conveyors feeding subsequent screens. A second screen sorts newsprint, and a third sorts commingled containers. A fourth screen polishes the containers of contaminants. Finally, four quality-control workers inspect and sort the newsprint, compared with the 18–25 who were required previously, according to Cordell. “It’s about a 98% sort rate on the newspaper,” he estimates of the automated system. From there, the different recyclables are packaged by balers and sold. When asked if the increase in material resulting from the transition to single-stream separation has caused any adverse issues in terms of material staging, Cordell says no. “The throughput of the single-stream system is much higher than what it used to be on the old sorting system,” he says. “What used to take us about 20 hours to process we can now process in about 10—really what it did was increase our capacity.”
Besides the improved efficiency that can result from implementing single-stream separation, facilities can count on increased diversion rates and consistent processing over the long haul, Egosi points out. “Today, there’s a lot of history—people know how much material is generated in their community and the seasonality of it, they have much better data, and they can much better size the plant to be able to process the amount of material,” he says. Although more material needs processing over the long term, a tipping floor is still necessary in a single-stream facility because workflow might be sporadic in a given day. “You could have five trucks in an hour, and in the next hour you could have one, and in the next hour you could have eight.” In addition, managers often consider changes in baling equipment when re-engineering a facility for single-stream separation, Egosi says. “Because these facilities are getting larger as a result of single-stream and because there’s more material that’s coming through the facility, the balers need to be higher capacity, they need to be very reliable, and they need to be able to perform for the particular material that is intended to be baled. That’s why we’re starting to see more facilities putting in two balers instead of one on a regular, systematic basis—one geared for paper and one geared for containers,” he says. “In several cases, because of the higher residue or trash level, there’s been an interest in just bailing that trash, whereas before, a lot of that trash would just go into a rolloff box. There was a small amount of material and you didn’t worry about it. Then people would put it into a compactor, and they would have to empty that compactor box maybe once a day. Now, with all of that extra trash, the compactor is going to fill up every couple of hours, and you can’t keep switching this compactor out all the time. So at the larger plants, there is definitely a movement toward baling the garbage.” Don Talend is a business-to-business communications specialist based in West Dundee, IL MSW - July/August 2007
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