March 1, 2004 | General

Single Stream Vs. Source Separated Recycling

Dan Emerson
BioCycle March 2004, Vol. 45, No. 3, p. 22
What is the best way to collect recyclable material in residential neighborhoods? Most discussion and debate about respective merits and drawbacks of various collection methods, schedules and tools have been based on opinion and anecdotal evidence. Eureka Recycling – a nonprofit based in St. Paul, Minnesota – took an empirical approach to the question with a 14-month study to determine the best method for the city to increase recovery and improve efficiency. The study – done with the city of St. Paul through a grant from the Minnesota Office of Environmental Assistance – compared five recycling collection methods, which varied by frequency, type of containers used, types of materials collected, and how materials were separated.
The five collection scenarios, tested in five neighborhoods, were as follows:
1) The current source separated collection system where residents sort materials into seven categories (newspapers and inserts; mixed paper; corrugated cardboard; phone books, glass bottles and jars; metal cans; and clothes and linens). Residents set materials out in an 18-gallon blue recycling bin, cardboard boxes and/or paper bags. (This neighborhood served as the control.)
2) Two stream collection using two 18-gallon blue bins. Residents sorted materials into two categories – papers (including newspaper, cardboard, paper and mail) and containers (mix of cans, glass and plastic bottles). Collection occurred biweekly.
3) Biweekly two stream collection (same as above) but using 32-gallon rolling carts to collect and set out materials.
4) Two stream collection with 18-gallon blue bins and the collection of household organics (including food scraps and nonrecyclable papers like pizza boxes and paper plates) in a 32-gallon rolling cart. In this neighborhood, recycling and household organics were collected weekly.
5) Single stream collection using one 60-gallon rolling cart to collect recyclables. Materials (cans, glass, plastic bottles and papers) were commingled and collected biweekly.
At the end of the tests, residents went back to the regular recycling program and were asked to fill out a survey about their experiences with and opinions about the different methods.
For four months, Eureka collected data from approximately 2,000 households, tracking how much was recycled, what was recycled and how often individual households set out their recycling. To bridge gaps in information, Eureka staff researched similar programs around the country. Overall, Eureka concluded, the study demonstrated that by carefully implementing important changes in what and how St. Paul recycles, the recycler can control costs, improve convenience and divert 74 percent of the discards that households generate through composting and recycling. Eureka estimates that if the city implements the recommended changes – the two stream method with bins and weekly pick up – residents would recycle 26 percent more, or as much as 3,061 tons.
Eureka’s study also “discovered real potential” to add kitchen organic material to curbside service. Eureka’s final recommendation for St. Paul was to convert from the current, biweekly source separated system to a weekly two-stream commingled program using 18-gallon bins and to add plastic bottles to the city’s curbside collection. The study also found that collecting organics is feasible and recommended that St. Paul conduct additional research into curbside organics pickup.
Approximately 25 percent of what St. Paul residents throw away could be separated for composting. In the neighborhood where Eureka tested the collection of kitchen organics for composting, 75 percent of residents agreed to participate. For four weeks, Eureka weighed the recyclable materials, compostable materials and trash of a subgroup of these residents. It was found that by collecting kitchen organics for composting, an additional 21 percent of the waste stream could be captured. That left only 26 percent of the waste stream as garbage. The study concluded that, by collecting citywide at a rate of 254 pounds per household per year, St. Paul residents would increase useful materials recovered from the trash by 10,160 tons per year. This is half of what is currently being recycled in the city.
Another major finding was that residents want to recycle plastic bottles at the curb and are willing to pay for the service. In four of five neighborhoods, Eureka picked up #1 and #2 plastic bottles. In these areas, 78 percent of residents indicated that they were willing to pay for recycling plastic bottles at the curb, more than any other new service element. Eureka Recycling is reconsidering its strategy on recycling plastic bottles. In the past, Eureka Recycling and its predecessor, the NEC, opted not to collect plastic because of the increased cost to collect and process the material, the poor and volatile markets for it and the concern that collecting it legitimized the proliferation of single-use plastics. Some of those circumstances have changed. There are now better markets for plastic bottles, particularly #1 and #2 bottles, than ever before. Recyclers have worked to compete against the virgin plastic manufacturers by providing recycled materials for packaging, thus improving markets for recyclable plastic material. “However,” notes Dianna Kennedy, Eureka’s communications manager, “Eureka Recycling will only collect bottles that can be recycled and will continue to educate residents about the environmental problems of single use plastic containers.”
Based on the results of this study, Eureka recommended four main changes to improve the recycling program in St. Paul. While specific to this city, they may be valid in other communities as well, according to Eureka staff: 1) Implement a “two-stream” sorting system, in which all paper is collected together in one category and all containers in another category; 2) Start picking up #1 and #2 plastic bottles at the curb; 3) Provide weekly collection in 18-gallon recycling bins; and 4) Work toward adding organics collection to the curbside.
According to Rick Person, program administrator with the St. Paul Department of Public Works, the city is “implementing everything recommended in the study,” including changes in its recycling program, and financing about one-third of the $3 million cost of a renovated materials recycling facility for Eureka. Effective in 2004, the city plans to change its collection system from biweekly, source separated (newsprint, mixed paper, corrugated, cans and glass; plastic has been collected only at dropoff sites) to weekly, two stream collection. Also as recommended, the city plans to add organics collection in 2006 or 2007, after the collection system changes are in place.
Person says he agrees with Eureka’s finding that single stream is a cheaper collection method, but more expensive, due to higher processing costs, and contaminated material. He adds that city officials were not surprised by Eureka’s findings that, with the addition of plastic bottles, the city would save money by going to two streams, since they “were predicted by the consultant.” A major publicity campaign to launch the new system will include mailers sent to each household. “That in itself will probably increase participation,” Person notes.
Eureka, a community-based environmental organization, has had a partnership with the city of St. Paul since 1986 to manage all of the city’s recycling program, including education and advocacy services. In April 2003, Eureka began collecting and processing materials themselves, rather than subcontract for these services with other haulers and processors. This 10-year contract runs until 2013. Eureka is one of a relatively small group of nonprofits in the country involved in collecting and processing recyclables. The agency is engaged in “an entrepreneurial model to demonstrate that recycling works as a sustainable, cost-effective program, that you don’t have to subsidize recycling for it to work,” says Kennedy. Its new fleet of collection trucks, fueled with a B-20 blend of biodiesel – can accommodate both the current source separated program and the recommended tow stream program.
Eureka began considering getting involved in the collection side of the business about four-plus years ago, according to CEO Susan Hubbard. Local governments “have been looking at cutting recycling because of costs; we think those costs have been inflated by lack of competition,” Hubbard explains. “Finally, we decided we needed additional recycling capacity in the metro area because of consolidation among waste management companies. Since that discussion started, we have seen even more consolidation that has started impacting collection costs.”
Eureka has invested about $6 million to $7 million to get involved in collecting and processing, including purchasing a fleet of 15 trucks. Eureka has a 10-year lease on a converted warehouse in northeast Minneapolis. The 117,000 square foot sorting facility is designed to handle two stream, source separated material. While Eureka did not conduct the study with the goal of “refuting” the merits of single stream collection, results of the study indicated that “the basic assumptions some people make about single stream – that it costs less, and people recycle more – are not true,” Hubbard says. “You have to test those assumptions.” Although some communities have reported cost savings in switching to single stream, “what really happened is that collection went from weekly to biweekly.” She contends that there has been a lot of “twisting” of information to support arguments in favor of single stream.
Management, Inc. (WMI) built a $14 million single stream processing facility in the Twin Cities, which is “something of a battleground” over the issue, Hubbard says. “The assumption has been that if people don’t have to sort material they are going to love it and recycle more. In the end, we found we lost materials (with single stream).” The gains in the amount of material collected were negated by what had to be discarded due to damaging or contamination with broken glass. “Larger carts meant more compaction,” Hubbard explains. “When material had to be pulled apart, it became contaminated and damaged. In source separated recycling, separating glass by color gives it value. Single stream causes broken glass, and shards of glass are nearly impossible to sort. Optical sorting technology is one solution, but it’s too expensive, a huge capital investment.”
Hubbard also cited WMI’s practice of using single stream material contaminated with broken glass for daily cover or roadbed material. Respondents to the St. Paul survey said they don’t consider that recycling. “Our residents want glass bottles to go back to being glass bottles. Other communities may find that acceptable, but I haven’t found one yet.” In her view, Waste Management’s contention that single stream saves costs was based on “apples to oranges” comparisons made of various collection methods used in other cities.
Steve Dunn, Twin Cities district manager for WMI, contends some information Eureka gathered for its report accompanying the study results are not indicative of the “newer” single stream facilities, such as the WMI facility that came online in Minneapolis in January 2002. He says residue rates cited by Eureka are not characteristic of WMI’s single stream facilities, and that recovery rates for the new plant are in the 94 to 95 percent range. He disagrees that single stream “degrades the (paper) fiber product. We regularly sample our bales and sell our newsprint as number 8 grade. We have no quality issues. … Based on comments in our public forums, single stream collection was the method rated highest by participants – judged to be best. It had the highest increase in setout rates.”
Eureka’s Susan Hubbard notes that Dunn uses the term recovery, versus recycling. The high residual rates from the processing come from the loss of glass, due to extreme breakage in the single stream system, she says. “WMI uses this residue in landfill applications and calls it ‘recovered.’ They do not count it as a residual.” Hubbard points out that most of the material going through WMI’s MRF in Minneapolis is collected in two streams. “The residual rate is a reflection of that. If the material was collected ‘single stream’, with high compaction, there would be more residual, including much more glass breakage. The Minneapolis MRF does not currently provide a true reflection of the real residuals of single stream recycling,” Hubbard contends.
From an industry-wide perspective, George Elder, vice president of SP Recycling Corp. of Atlanta says “the consensus among consuming (paper) mills is that the additional contamination in fiber from single stream programs causes economic harm to the mills.” The challenge, he explains, is that there is no linkage between the savings on the collection/recyclables processing end and the added costs on the mill’s end. “The consuming mills are too far removed from the curbside collection,” says Elder. “The mills have to use more chemicals, do more processing, that’s the bottom line. Every ton of contaminants you buy and ship to mills is going to cost you $75 to $100 for shipping, cleaning, and then hauling the waste to a landfill and paying a tipping fee.”
The bottomline, notes Kennedy of Eureka, is that “there are a lot of assumptions out there” regarding the effectiveness and cost of various materials collection methods. The study represents “a unique opportunity to open the book and talk about the real cost of recycling before you add on whatever profit margin you need to make.”
Eureka also has filed a bid to handle recycling for the city of Minneapolis, with a decision expected soon. Waste Management is also vying for the contract. “For us, it’s a win-win situation,” Hubbard says. “The idea was to create competition; we’ve already done that. They (the commercial haulers) know we’re competing for the Minneapolis material and they know the pricing we’re going to put out there will be very competitive.”
Detailed data from Eureka Recycling’s collection pilot can be found at Dan Emrson is a contributing editor to BioCycle.

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