As ubiquitous overflowing blue bins show, Philadelphia recycles a lot. According to the Streets Department, the city collected just over 100,000 tons of curbside waste, or 17.3 percent of the total curbside trash it collected, in 2018.

Unfortunately, the good intentions don’t always amount to much — as a recent Inquirer article reported, at least half of the material collected in Philadelphia gets incinerated at a waste-to-energy plant rather than recycled. The situation should be remedied by spring, according to Streets Department recycling director Kyle Lewis.

But even before that happens, Philadelphians can take action: Better recycling starts in the bin, not on the truck.

“We’re having a major issue around contamination," Lewis said. “Trash in all forms is infiltrating the recycling bins. That can cause an entire truck load to be rejected once it shows up to the processing plant.” And that means the material gets sent straight to a landfill.

Want to improve your recycling habits? Lewis and other experts shared the most common mistakes and how to address them.

Mistake No. 1: Recycling everything

The best thing Philadelphians can do to recycle better is to know what the city does and does not recycle.

“Just because a container has that triangular ‘chasing arrows’ symbol on it doesn’t mean you can recycle it,” said Kevin Cannon, a professor of chemistry leading a free Recycling Realities course with the Wagner Free Institute of Science this spring.

Cannon explained that while there are lots of items that can be recycled, “there are only so many of those that are actually marketable — meaning, someone out there is willing to purchase the material. This dictates what the city actually accepts.”

The Streets Department outlines what it accepts in a helpful list online (philadelphiastreets.com/recycling/how-to-recycle). Cannon suggests hanging a copy on your refrigerator.

Most plastic containers qualify — think peanut butter jars, soap dispensers, shampoo bottles, etc. — but hold off on takeout containers, Styrofoam of any kind, and disposable plates and cups (red Solo and otherwise). They’re all prohibited. The same goes for plastic-coated cardboard, the type used for ice cream cartons, frozen-dinner boxes, and heat-resistant cups.

Newspapers, magazines, and greeting cards can be recycled, but tissues, paper towels, and napkins can’t. Paper-towel rolls and egg cartons are OK; greasy pizza boxes are not — unless you toss the grease-soaked bottom in the trash. Clean aluminum foil, bottle caps, glass jars (and their lids) are fine, but leave out batteries and lightbulbs. Especially avoid anything that can be tied into a knot, like hoses, clothing, cords, and wires.

Lewis advises a “when in doubt, throw it out” policy: If you’re unsure about an item, it’s better to pitch it in the trash.

Mistake No. 2: Putting plastic bags in the recycling — or the recycling in plastic bags

Technically recyclable themselves, plastic bags are in fact a frequent nemesis of recycling plants. “They create major problems for the sorting machinery,” Cannon explained. “Since they’re so light, they act like sheets that wrap around the moving parts and clog everything up.”

Likewise, you should never use a plastic trash bag to contain your recycling. “You can have the cleanest collection of plastic and metal containers, but the minute you put it in a plastic bag, it becomes trash,” Lewis said.

Instead of using a garbage bag, apply online for one of Philadelphia’s free blue recycling bins. (Residents without internet access can register in person at a Sanitation Convenience Center.) Or create your own bin — any hard-sided container will work, as long as you stick a “recycling” label on it. Recycling stored in cardboard boxes and paper bags will likely, though not always, get picked up, but if it rains, those instantly become trash. Inclement weather can affect items in plastic bins as well, so be sure to use a lid or wait until the last possible moment to take recycling to the curb.

Mistake No. 3: Leaving liquid and food in containers

When you empty out your fridge on trash day, be mindful: One dirty yogurt tub can ruin an otherwise clean batch of recycling.

Consider another example. “Let’s say you toss out a jar of expired jelly," Lewis said. "It’ll be picked up in a compactor truck and smashed on top of everyone else’s waste in the neighborhood. That jelly will then spread all over the paper, degrade its integrity, and turn a good portion of what’s in that recycling truck into trash.”

Containers need to be emptied and rinsed before being recycled. They needn’t be scrubbed spotless and soap isn’t necessary, but try to use cold water. Otherwise, "you lose the value of the carbon footprint you’re saving, because hot water takes energy,” Cannon said.

Mistake No. 4: Repurposing containers the wrong way

Reusing that old hummus container is an excellent way to recycle on your own. But be sure to fill the container with something similar to what it previously stored.

“In an effort to be green, people will use an empty apple juice bottle for their lawn-mower gasoline,” Cannon said. “That alters the plastic and contaminates it in a way that it becomes no longer usable by the recycling facilities.”

When storing chemicals or gasoline, Cannon advises using glass, which is impermeable to both. (The American Petroleum Institute advises only storing gasoline in federal- or state-approved containers.)

Mistake No. 5: Forgetting to reduce and reuse

The next level of recycling is to become a conscious consumer, said Maurice Sampson, the city’s first recycling coordinator and a current member of its Solid Waste and Recycling Advisory Committee.

″If you recycle all of your bottles and cans and all of your food-rinsed plastic, the next question really becomes, ‘How do I make less of all of that?' ” Sampson said.

Changes as simple as drinking from a reusable water bottle or shopping with a reusable grocery bag can make a big impact. Other swaps — like cloth bags for plastic bags and dish towels for paper towels — decrease the risk of contaminating the recycling stream and lessen your impact on landfills.

It’s particularly important to stay mindful at the grocery store. Food waste accounts for the single largest factor in municipal solid waste, Sampson said. When it ends up in the landfill, it generates methane — calculated to be 30 times more potent at trapping heat than carbon dioxide.

“Before even focusing on recycling, we should be focusing on waste reduction,” said Sampson.

Interested in learning more about recycling? Enroll in Kevin Cannon’s free six-week course through the Wagner Free Institute of Science. Classes meet Mondays from March 4 to April 8 at the Falls of Schuylkill Free Library, 3501 Midvale Ave. 215-763-6529, wagnerfreeinstitute.org