Wednesday is garbage day where I live. You can tell from the bins all neatly lined up along the curb; one blue for trash and one green for recycling. Our office is a bit of a different story. Although many of us haven’t been to the office for quite some time, garbage and recycling have a more complex system at the CET office. At home, all of my recyclables go in the same bin, but at the CET office we have two bins for recycling, one for paper, and one for bottles and cans. Separating my recyclables at work is not so difficult, we have clear signage and the bins are right next to each other, but why do we separate recyclables in some places and not others, and what are the differences between these two systems?

My at home, throw-everything-in-the-same-bin, recycling system is called “single stream recycling”, while the separation system at work is called “dual stream recycling”. The typical debate between the two systems centers around two components, participation and contamination. The single-streamers tout that having one recycling bin for all recyclables increases participation in recycling programs. They do acknowledge that single stream systems have a higher contamination rate (which leads to more of the recycling stream being sent to the trash), but they believe that the recycling gained from the participation increase outweighs the recycling lost due to contamination. Dual streamers argue the opposite. They acknowledge that dual stream systems don’t garner as much participation, but they think that lower contamination rates cancel out the lower participation and allow for more recycling to actually be recycled.

Which Recycling System is Better?

So which systems is better, and how do different places determine which system to use? Unfortunately, there isn’t a lot of publicly available data on the topic, but a 2002 studyopens PDF file of recycling collection in St. Paul, Minnesota gives us some insight into the validity of the rival claims. The study compared participation and recycling rates of single and dual stream systems, and concluded that although the single stream system increased participation by 20.8%, the high levels of contamination in the stream resulted in 12.2% less material actually being recycled. These results have been echoed by a few subsequent studies (including a 2004 reportopens PDF file by the American Forest and Paper Association), and to make matters worse for single-streamers, the National Waste and Recycling Association has reported that around 25% of the material in our recycling bins end up in the landfill because of contamination.

A woman sorts recyclingopens IMAGE file

Single stream recycling programs often lead to more contamination in the recycling stream which makes things difficult for materials recovery facilities, where recycling is sorted.

If single stream recycling leads to less material actually being recycled, why do so many cities, towns, schools, and office buildings use the system? One reason is undoubtedly the aforementioned lack of data. I only managed to find these studies after scraping around the internet for a few hours, and none of them were written for a large audience. This lack of good information on the topic makes it easy to fall back on the theoretical assumption that more participation is better than less contamination.

China’s National Sword Policy

The other reasons why we mostly use single stream recycling are a bit more complex. While single stream recycling is easily contaminated and often ends up in the trash, it has actually been cheaper and more convenient for waste conglomerates to collect single stream recycling than other dual stream options. A big reason for single stream’s historical low costs has been recycling exports. Starting in the 1990s, a rapidly industrializing China started buying up recycling and other waste from around the world in order to acquire more raw materials for its booming industrial sector.

Back then, China did not have strict policies about the waste that it purchased and many U.S. waste companies took advantage by selling bales of contaminated single stream recycling to a China that was not carefully processing the waste shipments. Much of the recycling that was sent across the pacific during this time period ended up in the trash or the ocean.

Bales of recyclingopens IMAGE file

Bales of recyclables were often shipped to China for processing during a period lasting from the early 1990’s to 2018.

This period also coincided with the growing “popularity” of single stream recycling programs in the U.S. In 2005 around 29% of U.S. recycling programs were single stream, and that number climbed all the way up to 80% by 2014. I think it is fair to say that our habit of shipping contaminated recycling to China has been a major reason why much of the U.S. now uses single stream recycling. But our dependence on China for waste disposal was bound to end, and it did in 2018 with the enactment of China’s National Sword policy.

The policy aimed to curb pollution in China by banning contaminated waste imports, leaving few places for U.S. cities and towns to process their contaminated single stream recycling. This change in policy has led to a bit of a recycling crisis in the U.S., with some cities and towns scaling down their recycling programs and even sending excess recyclables to the trash.


While this new policy has disrupted our recycling system and brought to light the issues with single stream recycling, most of us are stuck with the same recycling systems that we’ve been using for years. New, dual stream systems would probably be better for the planet, but entrenched recycling collection and processing systems are difficult to change. There are, however, many things that can be done to improve our current recycling system.

For example, we could start to standardize recycling and garbage labeling at political and organizational levels. This solution—highly touted by Recycle Across America—has been effective where implemented (it increased recycling rates at a U.S. football stadium from 20% to 83% while also decreasing contamination) but it is also important to work on solutions at the individual level. Here are some things that you can do to contribute to a good, sound recycling system.

Avoid Wishcycling

Recycling streams often end up contaminated because consumers aren’t well educated about how and what to recycle. A big issue in the industry is “Wishcycling” or “aspirational recycling,” when people aren’t sure if something is recyclable, but throw it in the recycling bin anyway. Wishcyclers often have good intentions, but recycling non-recyclables is actually counterproductive as it leads to more contamination.

Recycling Education

It is therefore very important for consumers to be educated about what can and can’t be recycled in order to prevent contamination. Luckily there are many great consumer education resources out there. What can and can’t be recycled varies a lot state by state and city by city (you can check with your local waste management organization or municipality to learn more) but for Massachusetts residents a great resource is Recycle Smart MA. Recycle Smart has a website full of resources on how to recycle and what to recycle, including a “Recyclopedia” where you can search for an item and find out if it belongs in the recycling, the trash, or the compost. Recycle Smart MA also offers a downloadable “smart recycling guide” as well as informative presentations, videos, social media resources and signage to help educate the public about proper recycling practices.

A composter, a wheelbarrow full of garden scraps, and other composting tools and materialsopens IMAGE file

A great way to reduce contamination in your recycling stream is to start composting! Food scraps should not be recycled, and will turn into a nutrient rich soil conditioner when composted properly!

Start Composting

Another good option for decreasing contamination in the recycling stream is to start composting either at home or through a composting service. Organic materials like food scraps are not recyclable. They often contaminate the recycling stream and have to be sorted out at recycling facilities. If food scraps are properly composted, they can be turned into a nutrient-rich soil conditioner. CET also has some great resources on our website and in our blog for getting started with composting at home, but you can also check with your local municipality to see if they have a compost pick up service.