Today, curbside recycling programs are a well-established fixture in the vast majority of communities all across the US. But while few municipalities would disagree with the idea that recycling is an extremely important service, the question of which recycling method is best can be a surprisingly divisive issue. To understand why municipalities, recycling companies, and consumers alike tend to be split on the relative merits of single versus dual stream recycling, read on for answers to some frequently asked questions about these two common recycling methods.
What’s the difference between single and dual stream recycling?
As its name implies, single stream recycling allows all recyclables—including glass, metal, paper, cardboard, and plastic—to be mixed together. Typically, with single stream collection, consumers are provided with just one bin into which they put all their recyclable items and materials. The bin is then collected and taken to a recycling facility, where the items are sorted and separated for processing.
Dual stream recycling, on the other hand, requires consumers to do some of the initial separation of recyclables themselves. Specifically, dual stream recycling (also known as source separation) involves keeping the fiber component separate from the other materials. Consumers therefore have two different bins: one for paper and cardboard products, and one for glass, metal, and plastic containers and cans. The collection process is performed by trucks with multiple compartments, so that the different forms of recyclables can be picked up and transported while remaining totally separate.
It’s worth noting here that dual stream recycling evolved from multi-stream recycling, one of the earliest forms of curbside recycling, which involved separating all recyclables by material type rather than simply separating paper products from other items.
What are the pros and cons of each method?
One of the main reasons why there is no obvious winner in the contest of single versus dual stream recycling is that each method has a fairly equally balanced set of advantages and disadvantages.
Advantages of single stream recycling
One of the most cited benefits of single stream recycling is the convenience that it offers to the consumer. Proponents of single stream recycling argue that consumers are much more likely to participate in recycling programs if it requires a minimal amount of work on their part. One of the many examples supporting this point comes from the city of Madison, Wisconsin, where a switch from source separation to single stream recycling in 2005 boosted recycling participation by 25%. In addition, because single stream recycling does not require more expensive, multi-compartment collection trucks, pickup costs for collectors are lower.
Disadvantages of single stream recycling
Mixing all recyclable materials together in one bin may be easier for the consumer, but it makes the sorting and separation process at the recycling facility much more complicated and expensive. Aluminum, plastic, and glass containers can all cross-contaminate each other, and paper loads are especially vulnerable to contamination by glass shards and plastic scraps, which can cause major issues when fiber products are processed in paper mills. All this contamination potential, and the difficulties of properly separating multiple different types of recyclable materials, means that the quality of scrap material produced at single stream recycling facilities is much lower, resulting in lost revenue for recycling companies.
Advantages of dual stream recycling
Dual stream recycling addresses the problem of cross-contamination by keeping materials separated right from the beginning of the recycling process. This not only helps produce better quality, and thus higher-revenue, scrap material—it also decreases processing costs as less sorting needs to be done at the recycling facility. In addition, because dual stream collection relies on multi-compartment trucks, there is the possibility of using additional compartments to pick up items like batteries or lightbulbs, which consumers might be less likely to recycle on their own.
Disadvantages of dual stream recycling
There’s no question that dual stream recycling places a higher burden on consumers. Having to go through the extra step of separating materials rather than simply tossing them in one bin could discourage some consumers from recycling altogether. A multi-bin system is also more vulnerable to incorrect sorting and separating on the part of consumers, creating contamination problems that dual stream facilities may be less prepared to handle. Dual stream collection is also more costly, as the trucks needed are more specialized and the collection process itself takes longer when multiple bins are being picked up.
What factors should municipalities consider in deciding which method to adopt?
Ultimately, the choice between single and dual stream recycling is greatly influenced by the particular needs and barriers of each individual municipality. Factors that companies and communities need to consider when implementing, upgrading, or changing a curbside recycling program include current recovery rates and collection volumes, the availability of different processing facilities, available technologies, and labor costs. Different methods will suit municipalities for different reasons; the most important thing is to clearly understand the pros and cons of each method and know how each is likely to impact a particular community.