Constant adjustment

The changing material stream and a desire to increase recovered paper quality prompted Eureka Recycling, Minneapolis, to upgrade its MRF.

Material recovery facility (MRF) operators have little control over their incoming material, yet they are expected to produce specification-quality secondary commodities for use by reprocessors and manufacturers. Doing so requires constant reassessment of their operations because the incoming material stream can change from season to season and even from day to day, says Miriam Holsinger, vice president of operations and business intelligence for Eureka Recycling, Minneapolis.

Eureka, a nonprofit MRF operator that offers programs designed to help individuals, organizations and communities reach their zero waste goals, recognized that the residential recycling stream has evolved over time to include more containers and less paper, she says. For this reason, the company embarked on its most recent upgrade, adding a second optical sorter to improve polyethylene terephthalate (PET) container recovery and further clean up its recovered paper quality. This upgrade followed a 2016 retrofit that was designed to increase volume while also improving Eureka’s fiber quality.

Quality concerns

Eureka converted from a dual-stream processing system to a single-stream system that was supplied by Machinex, Plessisville, Quebec, in 2014. Holsinger says the change was prompted by increasing interest in single-stream recycling from the cities in Eureka’s service area. “We wanted to move where the industry was moving and really dig into it,” she says of Eureka’s decision to convert to single-stream processing and collection.

“We definitely saw residue increase,” Holsinger says. “We were around 1 to 2 percent with dual stream. When we switched, we saw that double in the first year, and now we are between 6 and 8 percent.”

She adds that it is important for Eureka to educate its customers on the material the nonprofit receives for recycling and what is truly recyclable. “Communication is key. We educate at the curb or go back to our customers.”

One-third of the material Eureka’s MRF processes is from communities it collects recyclables from; the rest is third-party-collected material.

Eureka’s initial retrofit in 2016 occurred when the MRF operator bid on the city of Minneapolis’ recycling contract. “We wanted to increase our processing speed and volume and were not quite happy with our quality,” she says. “No one was complaining about our paper quality, but we weren’t satisfied.”

To address Eureka’s concerns, Machinex suggested the addition of a scalping screen, a second ballistic separator and a second eddy current separator. Eureka also added a steel conveyor belt on its presort line because the belting material it had been using was getting destroyed by the scrap metals contained in the incoming material, Holsinger says.

The scalping screen was installed after the old corrugated containers (OCC) line and before two old newspaper (ONP) screens to remove 5-inch-minus materials. This material is then directed to the second ballistic separator.

In addition to adding the second eddy current separator, the nonprofit installed a wider unit to improve aluminum recovery.

These changes allowed Eureka to recover 90 percent of the aluminum in its incoming material stream using its first, larger eddy current and to clean up its paper quality, she says. “When we separated the smaller stuff and sent it to its own ballistic separator, the system performed better,” Holsinger adds.

However, she says there is “no perfect setting” for single-stream material, as its composition can vary widely based on the time of the year or the day. “We need our quality control staff to do that extra little bit.”

Regarding Eureka’s original equipment upgrade, she adds, “I think it was just remarkable to me how much we were able to clean up our paper. If you can focus on making sure you have the right equipment and it’s running optimally, you don’t need to slow down the equipment or add [manual] sorters.”

Additional optics

With the composition of the recycling stream evolving to include more containers, Holsinger says Eureka’s original optical sorter was “getting overworked a bit.” For this reason, the MRF operator installed a second optical sorter this year.

Eureka relocated its first eddy current and its magnet further back in the processing system to install the second optical sorter, which is positively sorting PET containers. Holsinger says PET accounts for 4 percent of the material Eureka recovers and markets.

The nonprofit repurposed its original optical sorter to sort paper and polypropylene (PP), also known as No. 5 plastic.

The addition of the second optical allowed Eureka to change the settings on its ballistic separator to allow more paper to flow with its containers, Holsinger says, because she is less worried about overwhelming the other optical sorter now.

“We were excited at the opportunity to clean up our containers,” she says. “We [also] removed more bottles and cans that ended up in our paper.”

Additionally, Eureka “more than tripled” the amount of tubs and lids it recovers for recycling, Holsinger says, though she adds, “increasing PP doesn’t bring in a lot of revenue.”

She says the burden on Eureka’s quality control sorters has been reduced as well because of the addition of the second optical sorter. The nonprofit employs up to 22 sorters per shift.

The MRF operator also was able to increase its overall processing speed with the addition of the second optical sorter. Holsinger says the nonprofit went from processing 350 to 375 tons per day prior to its most recent upgrade to 400 tons per day.

Taking downtime

Eureka runs a shift and a half five days per week. To prepare for the installation of the second optical sorter, the company ran the weekend before the installation was scheduled to start so it could clear its tipping floor, she says. The installation took six operating days and nine days overall, including weekends.

“We have contracts and have to keep accepting material,” Holsinger says, which meant that Eureka stockpiled incoming material throughout the installation process. She adds that the nonprofit could have sent material to other area MRFs for processing had it run out of storage space. However, she adds that this is an expensive solution.

Keeping material moving

Among the recyclables Eureka produces and markets today are PET, colored and natural high-density polyethylene (which is sorted by hand), PP, mixed paper, sorted residential paper and news (SRPN), OCC, carrier stock, glass and UBCs.

Eureka uses a blend of spot-market and contracted sales, with 80 percent of the material that it recovers remaining in Minnesota, Holsinger says, while just under 90 percent remains in the Upper Midwest. While Holsinger says Eureka is “not adverse” to selling material overseas, the company prefers to sell locally for the immediate feedback.

“If there are any issues, they can let us know, and we’ll work to address them. We can get that feedback sooner with local markets. We focus on local markets for that reason and for the environmental impact,” she says, citing a desire to preserve the reduced environmental impacts of recycling.

Because of Eureka’s focus on and relationships with local end markets, the fallout from China’s National Sword and Blue Sky policies has had less of an impact on the nonprofit. She says Eureka is still selling its mixed paper. “We have agreements that allow us to still get paid for that material,” she adds. “We know we are in a fortunate position.”

However, the nonprofit has not been able to escape the broader decline in material value that has resulted from China’s reduced buying and the glut of material available in the North American market. “The largest impact has been on the financials because the material is worth so much less than it was a year ago,” Holsinger says.

The situation has prompted Eureka to find efficiencies wherever it can in its operations, she adds.

The nonprofit directs a good deal of its profits to community education and outreach, Holsinger says, which has had to be scaled back as a result of market weakness.

Current market conditions have not altered Holsinger and Eureka’s future planning, however. “We are always looking at stuff and evaluating the composition of material and how our equipment is doing and if it is still the right equipment for the job,” she says.

For these reasons, Eureka Recycling will likely continue to make system upgrades in the years to come as technology evolves to address the issues it and other MRF operators encounter as the material stream changes.

This article originally ran in the July issue of Recycling Today, a sister publication of Waste Today. The author is the editor of Recycling Today and can be contacted at

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