Municipalities shift attention to single-stream recycling collection
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
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
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
“Single-stream recycling is a win-win situation,”
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
“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
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,”
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
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.”