SEPTEMBER 2008

Municipalities shift attention to single-stream recycling collection
E-mail the author


Cities weigh advantages against disadvantages

As the head of the solid waste bureau in Baltimore, Valentina Ukwuoma is getting daily calls from other communities wanting to learn more about single-stream recycling, where all recyclables are mixed together in one collection container.

Baltimore, which started single-stream collection in January, is only one on a growing list of municipalities across the country to launch single-stream recycling.

“Single-stream is working better than most expected” in Baltimore, Ukwuoma says, noting that the tons recycled by the city have increased by 20 percent.

“The simplicity of single-stream recycling encourages more people to participate, increasing volumes, which increases the amount of material diverted from landfills.” 


Before single-stream recycling was introduced, residents in Baltimore had to separate their paper and cardboard from their bottles and cans. The city had two different collection days for recyclables, one for mixed paper and another for bottles and cans.

More municipalities, like Baltimore, are choosing single-stream over dual-stream recycling, which requires sorting of recyclable materials before collection, because single-stream not only increases recycling rates, it also reduces costs, says Jeremy O’Brien, director of applied research at the Solid Waste Association of North America.

“Conversion to single-stream allows the reduction of collection frequency, which can substantially reduce fuel usage” for the haulers O’Brien says, adding that the number of single-stream facilities has increased across the country from five in 1995 to 160 in 2006, with more than one municipality, generally, using each single-stream facility.

There are drawbacks to single-stream recycling. Using one collection truck to pick up all the recycled material has the potential to contaminate the waste stream. One of the most frequently cited examples is recycled glass contaminating recycled paper.

The quantity of the material remaining after the single-stream process, referred to as residuals, averages 7 to 10 percent, while residuals from the dual-stream method averages around 2 to 5 percent, says LaTisha Petteway, a spokesperson with the United States Environmental Protection Agency (EPA) in Washington, D.C.

But single-stream recycling often increases the recycled pounds-per-household, Petteway says, outweighing potential drawbacks. Petteway cites recycling rates in Denver, where a single-stream program introduced in 2005 yielded a 21 percent increase.

The environmental agency does not track the number of cities currently using single-stream recycling versus dual-stream recycling, but Petteway says anecdotal evidence indicates that the single-stream method is increasing in popularity.

Major metropolitan cities that have already started single-stream collection, or are planning to launch single-stream programs, include Chicago, Dallas, and Denver.

Philadelphia plans to expand its single-stream collection to once a week after introducing bi-weekly collection citywide in 2006. Since then, recycling has increased more than 35 percent, says Clarena Tolson, streets commissioner in Philadelphia.

The city collected 50,000 tons of recyclable material in 2007, the highest quantity collected in the history of the city’s recycling program and Philadelphia earned more than $1.9 million from the recyclable materials, achieving another record for the city.

“Single-stream recycling is a win-win situation,” Tolson says.

Philadelphia began collecting plastics and cardboard when it started single-stream recycling. Under the former system, the city did not collect plastics or cardboard because it was too inefficient, Tolson says. “Plastics and cardboard would fill the trucks quickly, causing numerous trips to the processing facility” and increasing collection costs.

The only drawback of single-stream recycling for Philadelphia is higher contamination rates, lowering the amount of revenue earned for the recycled material, Tolson says. Glass particles and other debris often get mixed in with the paper.

“This increases the costs to process and decreases the revenue to the city,” Tolson says, adding that the city is able to make up for the loss with increased tonnage.

Across the country in Los Angeles, single-stream recycling is nothing new. The city completed its rollout of single-stream in 1998. It has increased recycling by more than 50 percent, says Karen Coca, assistant division manager of the city’s sanitation bureau. The city also achieved a 25 percent reduction in collection staffing.
Los Angeles is now in the process of expanding single-stream service to the Los Angeles Unified School District and to all multi-family buildings across the city.
It is not just big metropolitan areas like Los Angeles that have embraced single-stream recycling. Redding, California, with a population of approximately 84,600, is an example of a smaller city in the Golden State that provides single-stream collection.

Gret Horisk, public works supervisor for the city, says Redding tried three different curbside programs before eventually switching to single-stream recycling.

“Single-stream works the best and is the most cost effective,” Horisk says. “Sorting at the curb was time consuming,” requiring manual labor, leading to more worker compensation claims, Horisk says. Single-stream collection is automated.

Out of 415 cities and counties that report to the California Integrated Waste Management Board, the state agency designated to oversee the state’s waste, 392 have some kind of curbside program, says Kyle Pogue, a manager in Sacramento.

While the agency does not keep track of the number of single-stream versus dual-stream programs, Pogue says single-stream collection is increasing in California.

“There has been a fairly significant trend toward single-stream,” Pogue says.

Pogue says cities and counties are turning to single-stream recycling because it is more popular with residents who no longer need to separate their recyclables. Pogue says recycling rates after switching increase anywhere from 50 to 100 percent.

Single-stream recycling also expands the acceptable material that is collected, says Steve SoRelle, another manager with the state agency. “Now there are more mixed papers and different plastics allowed. It makes it easier on people,” SoRelle says.

Before switching to single-stream recycling, however, municipalities need to have an understanding of what the community’s processing options are, says Scott Pasternak, a consultant with R.W. Beck, Inc. in Austin. While some cities process the material with city-owned facilities, others contract out the process to single-stream facilities.

Not every municipality has the needed equipment for single-stream recycling. “Therein lies a disadvantage of single-stream recycling,” Pasternak says. “Cities need to have more sophisticated equipment, often meaning more expensive equipment.”