Before digging into the argument of which method of recycling is more efficient, it is important to understand both methods thoroughly.
Included in both recycling methods are two categories of materials:
After these two categories, there are, of course, remaining materials that can be recycled at specialty recycling facilities. These materials often have designated drop off locations and require more complex processes.
Single stream refers to the process of recycling materials (Category 1 & 2) that are all mixed together, including glass, paper, plastic, and metal. In this process, everything is “commingled” in a slurry of recyclables and will need to be extensively sorted and processed before the materials eventually end up in the correct categories. For consumers, this means that when you are sorting your recycling from your trash you will toss all recycling into one big bin for pick up with less pickup time to boot!
Dual stream recycling, on the other hand, is where the consumer is doing more of the work before the recyclables reach the facility. The recyclables are sorted into (Category 1) paper/cardboard and (Category 2) metals/ glass/plastic by the consumer. Once the recyclables are received they are sorted for purity before being sent off to be refactored into the new products.
As you can imagine one of these is easier for the consumer while the other is easier for the recycler, however, they both face challenges.
Single stream challenges revolve around constantly trying to reduce contamination from all of the materials mixing. The biggest contamination comes from broken glass. Not only is glass extremely abrasive on the processing equipment, if the glass particles get embedded into the fiber, the value is diminished. In addition, when bottles, cans, and containers come into contact with the paper, the residual liquid that had been in those containers will then be absorbed by the paper products sharing the bin. Due to the lengthier sorting process, overall sorting costs may increase. The amount of material reclaimed and quality of material reclaimed is also at risk of diminishing within the single sort process.
Dual stream challenges are more likely to occur from user error. While single stream makes it easier for consumers to recycle dual stream is sometimes seen by consumers as more work. There is also a greater risk of contamination causing issues for dual stream due to the specific processes for each type of material. As with Single Stream’s higher processing costs, Dual Stream typically suffers from higher collection costs from the number of bins automatically doubling.
Of course, there are also benefits to each method here are a few of the reasons each method is used:
Customer convenience, the public not having to do the sorting themselves is, of course, a big draw for single stream. Less work means more are willing to recycle as it seems like less of a time commitment. More participation also leads to more materials being processed, ultimately providing recyclers with more product at the end of the day.
The somewhat pre-sorted material offers a less contaminated product, to begin with, allowing recyclers to benefit from more pure materials at the end of their process and higher reclamation rates in comparison to single-stream operations resorting in higher commodity prices for their finished materials.
The main argument has boiled down to which process is more cost-effective. Unfortunately, there is not a clear answer. While many claim that single stream is more costly because of the cost of equipment and lack of separation ability due to the extreme contamination from material intermingling, there are equally as many claims that Dual stream is costly due to the complicated collection process as more bins require a more specialized truck as well as longer pick up times.
Most areas have their own preference for a recycling process and it comes down to what works best for the community. As technology gets more advanced, each process becomes more viable. With the development of equipment such as the Rod Deck FINGER-SCREEN™, single-stream recyclers are seeing better separation and the ability to recover more commodities at the same time. On the flip side, dual stream is seeing better contamination handling with equipment like the FINGER-SCREEN™ 2.0. Both methods are continuing to displace tons of garbage from ending up in landfills with help from consumers that are committed to changing the way we think about recycling.
If you are looking for a way to improve your single or dual stream recycling system, contact me! With decades of experience in the recycling industry, our Resource Recovery specialists will work with you to innovate the recycling process.