November/December 2011
Contamination bedevils plastics recyclers, whether it’s coming from the collection process or a result of design without consideration for recycling. Here’s a look at some of their biggest problems and the impact they have on equipment, material quality, and profitability.
By Ellen Ryan
On a residential block in Rockville, Md., two dozen blue recycling bins sit at the curb. Mixed in with the glass, newspaper, and cans is an array of plastic. In one bin are yogurt containers with the foil still attached. In another are bottles that once held detergent and cola, now rinsed and crushed with the caps placed back on. In a third are neatly washed trays from frozen dinners stacked inside a plastic grocery bag. The bins’ owners think they’ve done right by their community and their ecosystem by recycling properly, but they’re mistaken. These bins contain plastics the municipal collection program does not accept, ones with nonplastic residues and other materials that make processing more difficult or expensive, or ones that can be recycled but don’t belong in the curbside recycling stream.
Recyclers say these contaminants in plastics collection have increased with the growth of single-stream residential recycling. But even more worrisome, they say, are contaminants coming out of the plastics manufacturing process: labels, glue, liners, chemical additives, and more. Some of the biggest companies in the United States seem to keep coming up with new ways to confound plastic scrap processing equipment. Whatever their source, contaminants can result in slower processing, a lower yield, or lower prices for the processed material. Here’s a look at some of recyclers’ biggest contaminant concerns from the end and the beginning of the plastic life cycle.
Collection Concerns
Plastics processors acknowledge that single-stream collection of curbside recyclables has reduced collection costs and made recycling more convenient for the public. That convenience, plus consumers’ growing “green” consciousness, seem to be increasing collection volume, bringing in more desirable material—and more not-so-desirable material, too. Envision Plastics (Reidsville, N.C.), which buys baled, sorted high-density polyethylene, estimates its yield losses have grown from 10 to 15 percent in the 1990s to 16 to 22 percent since its suppliers switched to single-stream collection, says Tamsin Ettefagh, the company’s vice president of sales and purchasing. Contributing to the problem, she says, is government belt-tightening: Budget cuts have done away with much of the funding for public education that once was part of contracts between municipalities and materials recovery facilities. That leaves community residents confused or uninformed about what belongs in the bin. Those budget dollars aren’t coming back anytime soon, Ettefagh says, and complaining to a MRF supplier often means the material gets landfilled or shipped to Asia instead of recycled domestically.
Recyclers describe two broad categories of contamination in residential recyclables: nonplastics and other plastics—anything other than what they’re set up to process. Nonplastics start with the gunk the plastic container once held. Organic surface contaminants, everything from oil to ketchup to peanut butter, create odor and attract vermin, says Ron Sherga of SherResults, a plastics recycling consulting firm in Arlington, Texas. To remove this material, recyclers need sophisticated cleaning equipment and permits to use and recover water. Though this is an added cost for the recycler, it’s probably the most efficient way to handle such contaminants, he says. “If everyone in America did a real wash with soap” of plastic containers they’re recycling, “they’d negate the green impact of recycling,” he points out. Further, “in Texas, with [this year’s] drought, that much water would be a huge problem.”
Waste often gets mixed in with the recyclables in the bag or bin. For example, “we have a PGA golf tournament here,” says Marty Davis, owner and president of Midland Davis Corp. (Moline, Ill.), which recycles commercial, industrial, and consumer plastics and other commodities. “The trash and recycling containers are side by side. When the trash container’s full, people don’t want to throw [their trash] on the ground, so they put it in the recycling container.” Or, when companies offer drop-off boxes for plastic grocery bags, occasionally someone puts a bag of trash in there by mistake.
Other recyclable commodities also can cause difficulty for plastics processors. In single-stream collection, all of a household’s recyclables officially get thrown together in one bin. (In prior collection systems, the joke goes, recyclables were only unofficially thrown together.) MRFs successfully separate many commodities from the commingled stream, sending the paper one way, the aluminum another, and so on, but some materials can go astray. When paper ends up in the plastic stream, it plugs screens and messes up the wash line, recyclers say. Glass and metal can wear out parts in plastics processing equipment not meant to deal with them. “A bolt in a bottle could get stuck in a grinder and destroy the blades,” says Patty Moore of Moore Recycling Associates, a Sonoma, Calif., consulting firm. Steel cans get stuck inside plastic bags and get into the machinery, says Sandy Rosen, CEO of Great Lakes Recycling (Roseville, Mich.). Even where the recyclables are source-separated, like those drop-off boxes for plastic bags, contamination can be an issue: People have a tendency to leave receipts or nonplastic food wrappers in the bags they recycle.
Problems From Other Plastics
Contamination from other plastics is a matter of perspective. Each processor has a system designed to handle certain materials, and other plastics are contaminants in that system. Most curbside recycling programs don’t accept plastic bags, for example, but consumers often throw them in the bin or use them as containers for their other recyclables. “They get tangled in presort, in the star screen,” Davis says. “It takes a lot of time and labor to fish them out for very little return in weight.”
Plastic bottle caps can be problematic when they’re made from a different resin than the bottle. The Association of Postconsumer Plastic Recyclers (Washington, D.C.) advocates leaving caps on bottles when recycling them, but it also strongly recommends that manufacturers follow the APR Design for Recyclability Guidelines, which call for polypropylene caps on PET and PP bottles and HDPE caps on HDPE bottles. “Too many [PP] caps on bottles is a contamination issue” in the HDPE bottle stream, says Scott Saunders, general manager of KW Plastics Recycling (Troy, Ala.), which produces custom postconsumer PP copolymer and HDPE resins. The industry has taken the position that it’s best to have consumers leave the caps on the bottles and let recyclers find mechanical ways to remove them “because we’re recovering more plastics” that way, Saunders says. At the same time, the industry is working to educate bottle designers of the APR guidelines. Recyclers who buy plastics from industrial and commercial sources must contend with contaminants as well. Clean shrink wrap is worth 15 cents a pound, for example, Davis says, and plastic strapping is worth 7 to 8 cents a pound, but when they’re mixed together, they’re only worth 2 cents a pound.
Incompatible plastics can look identical and have physical properties that are similar enough that recyclers have trouble sorting them for recycling. PET thermoforms—used for some microwave dinner trays, clamshell containers, and cups—are Exhibit A. “PET thermoforms can and are being recycled with [PET] bottles as well as being recycled separately,” says Michael Schedler, director of technology for the National Association for PET Container Resources (Sonoma, Calif.). Impeding wider acceptance of these products by recyclers, however, “is contamination from look-alike containers” made from polyvinyl chloride, polylactic acid, glycol-modified PET (PETG), and oriented polystyrene (OPS). Recyclers can’t easily remove these look-alikes during a manual reclamation process, Schedler says, though automated sorting systems can distinguish among them. (Labels are another impediment to thermoform recycling, but more about that in a moment.) With limited markets for thermoforms, whether PET or other resins, few MRFs want them in the recycling stream. In Rockville, “we don’t take them, but we’re looking into it,” says Tom Kusterer, recycling center manager for the Montgomery County Division of Solid Waste Services. The ones they receive go to a waste-to-energy facility. In Michigan, on the other hand, Great Lakes Recycling packs PET bottles and thermoforms together and sells them to buyers who will accept both.
With single-stream recycling becoming the predominant collection system across the country, MRFs and plastics processors are looking at how to best address collection-based contaminants. Residential collections face both educational and operational issues, says Jonathan Cohen, president of Generated Materials Recovery (Phoenix), which collects, processes, and markets more than 30 grades of recyclable plastics. Often there’s no communication between those who determine what materials get collected and the plastics processors and end users of the material. This creates an “education disconnect,” Cohen says. “Material is collected with little thought given to the economics of how those materials will ultimately be reprocessed.” In commercial recycling, he points out, the processor can often work directly with the material generator to educate it about what materials are “acceptable and economically viable to recycle.”
At the operational level, Cohen takes issue with MRF separation systems that do a negative sort—those that pick nonrecyclables off the conveyor and leave behind the recyclables. They tend to recover a higher percentage of recyclables, he says, but they also tend to have “more contaminants in the outbound, processed bales.” The problem is not just the overall contamination, he says, but the inconsistency of it. “The ‘clean,’ sorted bales may have a perpetually changing, wide range of contamination, making it very challenging and expensive for any final processor to build a system to handle those bales,” he says.
“Ultimately, I think the market will shift to [more] positive sorting operations,” Cohen says, “even if it means lower overall levels of recovery, because these bales not only command a premium but can be marketed with greater efficiency, as claims or rejections are less likely. These bales are more uniform [and] reliable, and as a result, there is more demand for them.”
For processors with enough volume to justify it, an optical sorter can help. With such equipment, Great Lakes Recycling has gone from processing 9 tons to 17 tons of single-stream recyclables an hour with the same number of employees, some of whom now focus on quality control instead of separation, Rosen says.
Another approach to reducing contamination in the collection of recyclables, though it has little momentum, is more use of deposit laws, which charge consumers a deposit on certain beverage containers and refund that deposit when they return the containers to a redemption center. “Deposit-grade material is the cleanest and is worth a little more,” says Tom Emmerich, president of Schupan Recycling, a division of Schupan & Sons (Kalamazoo, Mich.) that processes PET containers. And “it’s 50 percent faster to run than MRF material” through the company’s processing equipment, he says.
Contaminated by Design
Perhaps more frustrating to recyclers are contaminants that come from the packaging or product manufacturer. Companies change product packaging for many reasons, such as to reduce product spoilage, boost package visibility, or save money. The executives involved in such decisions don’t always consider how the change affects the product’s recyclability—they don’t design products for recycling. Again, recyclers’ concerns fall roughly into two categories: materials attached to the plastic container and those integrated within the resin.
Attachment issues begin with the glue that connects labels to bottles, which doesn’t necessarily wash off easily. Recyclers like KW Plastics’ Saunders learn what temperatures work to get rid of various glues, but “if a manufacturer changes to a glue that reacts at a different temperature, suddenly we’re not getting the glue off,” he points out. Unlike the paper labels on bottles, which often stay on with one small strip of glue, labels on thermoform plastics like deli containers tend to have stronger adhesives applied across their entire surface. The amount and type of adhesive has been another factor impeding PET thermoform recycling, Schedler says. The paper label contamination problem “would largely be addressed by the use of recycling-friendly adhesives,” he adds.
Plastic labels shrink-wrapped around the bottle are a more serious concern, however. “Full-wrap shrink labels are the worst thing we’re facing,” Schedler says. “MRFs and reclaimers with autosort equipment can’t read the PET resin behind the label,” which is most likely made of PETG, PVC, PLA, or OPS. All of those are “serious contaminants in PET and very difficult to remove” from the processing stream, he says. Whereas washing can loosen the glue on most other bottle labels, that doesn’t work with these labels. “This has caused PET reclaimers that are trying to make packaging-grade RPET to manually remove them, causing huge economic dislocation,” he says. At Schupan, Emmerich tells his workers to “pull the whole bottle out of the line” when they find a full-wrap label. Many recyclers sell bottles with shrink-wrapped labels as mixed plastic—at a substantially lower price.
If such bottles get into the plastics processing stream with the label intact, they can wreak havoc with processing equipment. Take PVC labels on PET bottles, for example. A float/sink separation process can’t separate the two materials, but PVC and PET melt at different temperatures. “When you melt PET, PVC—if it’s still around—will scorch, degrade, and create hydrochloric acid. It messes up the PET and the tooling,” explains David Cornell, technical director of APR.
One more problematic attachment is aluminum liners in plastic bottle caps. “Twenty years ago they were the biggest problem,” Emmerich says. Though they’re less common now, they still appear in the material stream, and “you have to train your people to look for that,” he says.
Deeper Problems
No amount of washing or grinding can address additives within the plastic, such as silica, mica, and calcium carbonate. Manufacturers use calcium carbonate, for instance, to stiffen a polymer and, it being cheaper than plastic, to reduce production costs. But these additives change the specific gravity of the product, again confounding the float/sink separation process. Sherga explains that PET sinks in water, while HDPE and PP float—but add enough calcium carbonate, and those, too, will sink. It doesn’t take much: Just 0.05 grams of calcium carbonate per cubic centimeter will make HDPE sink; slightly more will make other types of polyethylene sink, Cornell says. Colorants can contribute to the problem, he adds. On their own, colorants will not make HDPE sink, though they do have a density greater than 1. “Add some calcium carbonate, or mica, or so on” to colored HDPE, however, “and it’s easy for the plastic’s specific gravity to go over 1 and sink in water,” he says.
Colorants also can affect PET’s recyclability, processors say. PET’s selling points are its clarity and sparkle, so anything other than plain, colorless resin reduces the material’s value. Beverage manufacturers have been using colored PET bottles lately for ginger ale, tea, and beer. “A large number of amber bottles is a problem,” says Glenn Odom, vice president of raw material development in the material recycling division of Wellman Plastic Recycling (Johnsonville, S.C.), which processes PET, HDPE, PP, and low-density polyethylene. “We manage [the problem] by combining them with green bottles to make green or black fiber,” he says, which normally sells for a lower price than fiber produced from clear flake. APR’s Cornell adds there’s less demand for the colored fiber, and separating colored PET from clear PET creates additional processing costs.
At least those PET bottles are transparent. Opaque PET is “the top contaminant” Envision Plastics is facing, Ettefagh says, because until now, the vast majority of opaque plastic containers were HDPE. Using a brand of coffee creamer as an example, Moore describes the impact of this change at a MRF: “The people sorting see it as HDPE, which it used to be, rather than white PET, which it is now,” so it becomes a contaminant in the HDPE stream. Even if it were recognized as PET, it’s currently of no value to recyclers. “Opaque PET, even white, is not sought for recycling today,” Cornell says, because it’s such a small proportion of the market. “If there were a huge amount of it, someone would find a use for it. But now we have to pull it out and sell it at a big loss, or trash it.”
Manufacturers say they create opaque PET bottles to protect the container’s contents, but recyclers aren’t buying it. They think it’s all about marketing. For products such as shampoo and conditioner, an opaque bottle “gives a subliminal sense of being clean and shiny,” Ettefagh says. And an opaque bottle covers up product separation for everything from coffee creamer to orange juice, tea to yogurt drinks.
Barrier resins of a different color or polymer get added to plastic containers to prevent oxidation or spoilage of products such as orange juice. Some yogurt smoothie containers have a white outside, for example, but use a black interior layer. Of course, MRF workers can’t see the inside of the container when they’re sorting. “If we’re shooting for white resin, that ruins our batch,” Ettefagh says.
Color isn’t the only problem with barrier resins; two different polymers layered together create a product that most recyclers can’t process. If the outside is HDPE and the inside is EVOH, a copolymer of ethylene and vinyl alcohol, the whole package is a mixed resin. The number on the bottom should be a 7, Ettefagh says, but sometimes it’s not. Marking bottles with barrier resins as if they were a single resin “hurts our company,” Ettefagh says, “because our customers don’t want contaminated resin.” Manufacturers can test their multiple-resin bottles using APR protocols and ask the APR technical committee to review and accept the results. If it finds that “they still can be recycled with the base resin,” the company can seek permission to continue using the No. 2 code, she says.
Biodegradables are the one type of plastic additive that seems to raise the ire of plastics recyclers more than any other, however. They object on two fronts: First, they are skeptical of the manufacturers’ claims, pointing to scant evidence that the bottles degrade in landfills, commercial composting facilities, or home compost piles. In fact, in late October, the California attorney general filed a lawsuit against two bottled water companies and their bottle supplier, charging that bottles they label as biodegradable do not meet the state standard for degradability. From the recyclers’ perspective, biodegradable claims encourage eco-minded consumers to put plastic bottles in the trash, not the recycling bin, reducing their supply while not delivering the promised environmental benefits.
Recyclers’ second objection is what happens when these bottles do end up in the recycling stream. Wellman Plastic Recycling’s Odom says regular PET “has a different melt temperature than biodegradable PET made by Dow from a different process. Biodegradables melt and stick to the dryer, causing downtime” while the equipment is cleaned. That’s the short-term problem, but long-term, if these plastics degrade, the liability issues “could literally collapse the plastic recycling industry,” Moore says. “It’s scary.” She explains that “even after flake and wash and dry, degradable additives can’t be identified” or removed during the sorting and recycling process. If they’re present in sufficient quantities, the next product they go into won’t have the physical properties the manufacturer or user expects. Picture a bottle of bleach that springs a leak, or plastic strapping on a load of bricks that falls apart. Some major product manufacturers have touted their use of degradable plastics in carpet, produce bags, beverage bottles, and more.
Making Progress
Despite their many contamination issues, plastics processors say manufacturers are taking product end-of-life concerns into consideration more often than in the past. Industry associations are doing their part to increase awareness. ISRI’s Design for Recycling® initiative encourages manufacturers to consider end-of-life issues in the design of their products. APR uses the “NAG system,” Cornell says—that’s short for “Not APR Guidelines.” It notifies the manufacturer of a problematic product that “we’re willing to work with them so their containers won’t be disadvantaged in the recycling stream.” MRFs and recycling companies learn quickly when containers from a specific product or company are causing problems, he says. “That’s a message that takes a while to fade away, so companies want to cooperate” by improving their products’ recyclability.
Retailers are joining in the fight as well. Wal-Mart, for example, has created a sustainability assessment for its suppliers that takes into consideration their carbon footprint, sustainable sourcing of raw materials, and third-party environmental certifications—all areas in which a product’s recyclability might play a role. In Canada, the country’s five largest grocery store chains (one of which is Wal-Mart) have agreed to only purchase clamshell thermoform packages made from PET in an effort to increase the recycling of that type of packaging. The group also is working with APR and NAPCOR to eliminate glue and label contamination on thermoform clamshells. Making thermoform labels and adhesives compatible with the rest of the plastic will go a long way toward increasing these products’ recyclability, says NAPCOR’s Schedler, who helped broker the agreement among the grocery chains.
With plastics recyclers facing contamination concerns on so many fronts, making progress on this issue is difficult, but it is happening. “The industry’s improved significantly in [the past] 20 years,” Emmerich says, and “I think you’ll see continued improvement in the next five to 10.” With better technology, greater attention to design for recycling, more pressure on the right parties, and a problem-solving attitude, recyclers hope to find both greater yields and less contamination in years ahead.
Ellen Ryan is a Rockville, Md.-based writer.
Addressing a Painful Problem
Medical facilities have strict procedures for the disposal of sharps—any objects used to open the skin, such as scalpels and needles. Those who use such instruments at home are often told to put their used sharps into plastic jugs until they can dispose of them properly, but those plastic jugs sometimes end up in the trash or the recycling bin, creating a health hazard for workers who collect, sort, and otherwise handle them. The Association of Postconsumer Plastic Recyclers hears of fewer sharps-related incidents now than it did five years ago, says David Cornell, APR technical director. At Great Lakes Recycling, which processes more than 10,000 tons of residential recycling material a month, CEO Sandy Rosen estimates “there’s a poke less than once a year. But on rare occasions, a needle we never see slips through, and we get a complaint from the plastic facility we sell to.” Taking a proactive approach to the problem, GLR employee Mary Jo VanNatter worked with county health departments to design a poster showing proper disposal options and distribute it to pharmacies, health departments, and elsewhere to reach the 3 million people in the area the company serves. “We believe the message is working,” Rosen says. For more on sharps disposal and injuries, go to www.fda.gov/safesharpsdisposal.
Contamination bedevils plastics recyclers, whether it’s coming from the collection process or a result of design without consideration for recycling. Here’s a look at some of their biggest problems and the impact they have on equipment, material quality, and profitability.