Recyclable materials zip along a conveyor belt in Shakopee as workers scramble to grab what doesn’t belong: Plastic bags, shredded paper, clothes hangers, a giant poster of Garfield.

It’s all evidence of “wish-cycling,” the well-intended pitching of trash into the big blue single-sort recycling bins in hopes that it can, somehow, be recycled. But those unwanted items are a headache for recyclers, who are left with gummed-up sorting machines, less valuable recyclables and a pile of trash.

A group of recyclers, waste haulers, and city, county and state officials has been meeting for the past year to develop clearer and more consistent guidelines for the public about what’s acceptable to toss in curbside recycling bins — and what’s not.

“People want to do the right thing,” said Julie Moore, who leads a local group representing city recycling managers. “And we need to make it easy for them to do that.”

Part of the confusion stems from the patchwork of recycling practices that vary by city and their chosen hauler. Jocelyn Cronin of Mendota Heights said it feels like the message is “recycle everything” followed by a long list of caveats. And she doesn’t want to miss an opportunity to recycle something that is recyclable.

“I err on the side of I would rather give it to them, and even if it’s not recyclable, think they’ll take care of it,” said Cronin, who stopped by a recycling information booth at a local park event.

Residents’ hopeful habits mean 6 to 8 percent of the material at typical local recycling facilities is “residual” — trash destined for landfills or incinerators. State law says recyclers must pay a tax penalty if that residual amount rises above 15 percent.

Cities have also pushed haulers to accept more materials, unaware of what happens down the line, to boost the collection amounts that determine county funding for their programs. Haulers competing for contracts agreed to take materials that cause problems or have limited markets to be made into new products.

Not all plastics Minnesotans dispose of can be recycled, for example, but some haulers will accept all plastics no matter the number. The result? Some non-recyclable Solo cups end up going from the recycling facility to the landfill.

“There was an arms race going on of, ‘The more, the better,’ ” said Bill Keegan, president of Dem-Con Companies, a Shakopee-based recycler helping lead the effort to better coordinate recycling education.

No plastic bags

The group plans to finalize the list of priority items to recycle and the top items to avoid by next month. The hope is that cities, counties and haulers incorporate it into their education.

“You’re not just training the adults,” said Mark Stoltman, general manager of Randy’s Sanitation, one of the largest haulers in the state. “You’re training the kids in the schools. You’re training people that you hope in the next 10, 15, 20 years all learn the same things.”

So what kind of things are being considered?

One of the top problems for sorting facilities is plastic bags, which get tangled around the spinning machines that separate recyclable items of different shapes. People working at processing facilities typically have to stop several times a day to cut those bags off. Hoses and extension cords pose similar challenges.

Instead, plastic bags should be recycled separately at the grocery store. (Find the nearest location at plasticfilmrecycling.org.)

Recyclers also don’t want needles, diapers or hazardous waste.

“People forget that human beings sort through this material once you put it in your cart,” said Lynn Hoffman, co-president of Eureka Recycling, which handles waste for Minneapolis and St. Paul.

And then there are tiny items.

Glass recycling relies on small shards of broken bottles falling to the bottom of the machine that sorts recyclables. But anything smaller than 2 square inches usually falls with it, contaminating the pile. At Dem-Con recently, the glass was hard to spot in a pile of plastic bottle caps, shredded paper, pulltabs, even a domino and a shotgun shell.

Not everyone agrees on what’s in and out of the curbside bin, however.

“Above all else, keep shredded paper out,” Keegan said.

Even if it’s bagged, he said; many bags explode in the truck and ultimately litter the glass pile with tiny shreds that then can’t be recycled. Contamination cuts into recyclers’ bottom lines, lowering the price they can get when they resell materials.

Yet Eureka accepts shredded paper that’s been bagged and has invested in special equipment to keep as much of it out of the glass as possible.

Complicated rules

Recycling decisions are even more difficult as consumers grapple with more complex packaging.

For instance, food pouches often can’t be recycled because they are made of several materials, but they are flat enough to fool sorting machines into thinking they are paper.

At the Mendota Heights park event, Debbie Johnson peppered the Dem-Con staff at the recycling booth with questions about soiled pizza boxes, sour cream containers and bottle caps.

“Would this be recyclable?” Johnson asked, pointing to a cylindrical oatmeal box with a plastic coating.

“That one’s not, because it’s got multiple materials that are adhered to each other,” replied Erin Chamberlain, who leads the company’s marketing and outreach efforts.

It can be difficult to keep it all straight.

Moore, of the recycling managers group, recalled attending a recent wedding brunch where the mother of the bride was proud she had purchased all plastic plates and cups, with the intent of recycling them. But someone pointed out they were No. 6 plastic, which the local hauler did not accept.

“She was just so upset because she had tried so hard,” Moore said.

A Minnesota Pollution Control Agency (MPCA) survey of several hundred cities across the state several years ago found wide variations in what haulers accept. On the topic of plastics, there were nine variations and conflicting advice about whether to leave caps on bottles.

“I wish recycling was one of those things where we could just say, ‘Here’s a magic bullet. Here’s how you do it everywhere, every time,’ ” said Mark Rust, supervisor of the MPCA’s Sustainable Materials Management Unit. “But it’s not always the case because there’s different markets, there’s different service providers.”

He added: “That doesn’t mean that we can’t do a better job at trying to get some common understanding and hopefully some collaborative education.”