If you recycle at home, chances are you take advantage of a system called “single-stream” recycling: you mix all your bottles, newspapers, cans and containers together in a roll cart or dumpster, and a truck comes by once a week to pick them up.
But what happens next? Is that jumble of broken glass, paper, metal and plastic really getting recycled?
The short answer is ... mostly, yes. But the system is far from perfect, and some of what could have been recycled ends up in a landfill.
I followed the trail of single-stream recycling in St. Louis. Here's some of what I found out.
What can be recycled through the single-stream process?
- Probably more than you think!
- But it varies depending on where you live. In general you can recycle paper and cardboard; glass bottles and jars; aluminum packaging; steel cans; aseptic containers (like juice boxes); and plastic containers (except Styrofoam). St. Louis County can take hard #6 plastic packaging. St. Louis City cannot.
- There are some other differences, so it's a good idea to check your municipality's website for dos and don'ts.
How does single-stream recycling work?
- The details of the single-stream process vary by location.
- In St. Louis City, the same trucks that pick up garbage come by once a week to collect single-stream recycling from roll carts and alley dumpsters. The trucks dump their loads at one of two transfer stations. From there, 18-wheel trucks take the recycling to a Materials Recovery Facility or "MRF" (it rhymes with "smurf"). The city uses a MRF in Earth City owned by a company called Resource Management.
- In St. Louis County, recycling collection is handled either by private haulers or by individual municipalities. Some of the county's single-stream ends up at Resource Management's MRF, but most of it goes to a different MRF in Hazelwood, owned by Republic Services.
Does everyone in the St. Louis area have access to single-stream recycling?
- If you live in the city of St. Louis, you should either have a single-stream roll cart or alley dumpster, even if you live in a multi-family apartment building.
- In St. Louis County, only trash haulers serving one- or two-family residences are required to provide single-stream recycling service.
What is a MRF and what happens there?
- Single-stream recycling has become economically viable for two reasons: volume and technology. A typical MRF can process hundreds of tons of recycling in a single day and it runs 24/7. MRFs rely on machines to do most of the sorting.
- At both of the MRFs I visited, a multi-story network of conveyor belts transports the mixed recycling from the "tip floor," where it has been dumped by trucks, to a series of huge machines. The machines use vibrating screens, spinning disks and gravity to separate the paper from the glass and containers.
- At Republic Services' MRF in Hazelwood, a machine with a magnetic belt captures steel, and another machine uses spinning magnets to create an "eddy current" to repel aluminum. Different kinds of plastics are separated by optical sorting machines. Republic's recycling general manager Brent Batliner compares the optical sorter to a grocery store scanner. "It’s got infrared scanners that, as material passes underneath, it will read the chemical make-up of the bottle," Batliner said.
- Resource Management transports glass and containers from St. Louis to its main MRF in Chicago, where they undergo a similar mechanized sorting process. There, optical sorters are also used to separate different colors of glass.
VIDEO: This optical sorting machine at Republic Services' MRF in Hazelwood, Mo. is programmed to "see" HDPE or #2 plastic, like detergent bottles and milk jugs with its infrared scanner. Air jets propel the plastics off the conveyor belt into a bunker 25 ft. below. The sorting process isn't perfect, and some plastic bags, papers and other items also get blown off the belt. (Video by Emanuele Berry, St. Louis Public Radio)
Is everything at a MRF done by machine?
- No. Workers are still needed to pull trash off the conveyor belts, or to reroute any recyclables that have ended up in the wrong place. They also keep an eye on the machines to watch for any problems.
VIDEO: Workers sort recycling and remove trash at Republic Services' MRF in Hazelwood, Mo. (Video by Emanuele Berry, St. Louis Public Radio)
What causes the biggest problems for a MRF?
- Anything that can get stuck or wrapped around the plant's machinery, like plastic sheeting, wires, videotape, chains or cables. Resource Management's Gary Gilliam said one time, somebody put a hammock in with their recycling and it got wrapped around the works of one of the MRF's machines. "It was nylon," Gilliam said. "It heated and made a block of nylon. You couldn’t cut it. It took us hours to fix that."
- Moisture. Wet paper gets stuck to other recyclables or to the machines and doesn't make it through the sorting process. MRF workers will try to pull wet paper out of the recycling line, but it usually ends up at a landfill. Moisture is a particular problem in the parts of St. Louis City that use alley dumpsters for single-stream recycling, since they can't be closed to keep rain or snow from getting inside.
- Shredded paper. If it's loose, it can contaminate broken glass and often won't get recycled. It's best to put residential shredded paper in a sealed bag so that workers can retrieve it off a conveyor belt.
- MRFs can handle some contamination. You DO NOT need to remove lids from containers or wash them. As long as they're empty, that's good enough. Food and other wet waste can contaminate paper, however, if there's too much of it.
Where do residential single-stream recyclables end up?
- Newspaper (an umbrella term for any paper coming out of residential households) is baled and shipped to China, Vietnam or other developing-country markets.
- Everything else coming out of St. Louis-area MRFs stays in this country. Aluminum and steel get melted down and reused. The cleanest glass is turned back into bottles and jars; the rest may end up as fiberglass. Recycled plastic can be used in everything from carpeting to paint buckets — but it won't end up in your water bottle or any other food-grade packaging.
Besides single-stream, what other residential recycling options are out there?
- Dual-stream recycling. It's basically the same as single-stream, but paper is kept separate from everything else (see, for example, Emmet County's program in Michigan). Dual-stream reduces cross-contamination between paper and glass and doesn't need special trucks for pick-up — although it does require a little more effort on the part of residential recyclers.
- Beverage container deposit laws, or "bottle bills." These are mandated by states or municipalities. Retailers pay a deposit to beverage distributors for each container purchased. Consumers pay the deposit to the retailer when buying the beverage and get a refund when they return the empty container.
- Source separation. That's the waste management industry's term of art for recyclables that are already separated before they get to the recycling plant. As a curbside recycling strategy, source separation has not proved economically viable, in part because it requires haulers to invest in trucks with individual compartments, it demands a lot more time and physical labor on the part of the workers picking up the recycling, and too few residences participate.
So what's the bottom line — how well is single-stream recycling really working?
On average, about 8 to 10 percent of the residential single stream recycling that comes into a MRF ends up at a landfill.
But according to Susan Collins, the president of the Container Recycling Institute, a non-profit research and advocacy group, the total loss is closer to 25 percent, because materials leaving the MRF are still contaminated. The companies that buy them have to clean them up before they can be reused, and a lot of what could have been recycled gets lost along the way.
Glass — which should be 100 percent recyclable — fares particularly badly in the single-stream process. Bottles and jars end up crushed and contaminated with everything from pieces of ceramics to chicken bones. Collins estimates that only about 60 percent of the "glass" coming out of a MRF can be salvaged and reused.
“In terms of preserving the quality of materials so the maximum materials collected can actually be recycled, single-stream is one of the worst options," Collins said.
Still, single-stream has increased residential recycling in the St. Louis area, although participation varies widely by municipality.
On average, Republic Services' Brent Batliner said about 20 to 30 percent of St. Louis County's residential waste is being diverted from the landfill. "But you can go into some areas where you’re up to 50, 60 percent, for that particular neighborhood," Batliner said. "And you go into other areas where you may be as low as 5 or 10 percent."
In the city, the diversion rate has plateaued at about 10 percent for the past two years.
Republic Services has recycling plants in approximately 70 cities nationwide. Overall, Batliner said, the St. Louis region is "middle of the road" in terms of its success in keeping residential waste out of the landfill using single-stream recycling.
Follow Véronique LaCapra on Twitter: @KWMUScience