Biofilm bags not the cause of Madison’s compost problem, but use still discouraged

October 29, 2017 GMT

When the city asked participants in Madison’s organic waste pilot program in June to stop using compostable bags, the problem appeared to be that the thin “biofilm” bags often used to contain the waste weren’t breaking down as they should have.

It turns out the problem wasn’t the bags, but what people were putting in them.

Recycling coordinator Bryan Johnson said plastic, metal and glass have appeared inside the compostable bags, which can contaminate an entire day’s collection when thrown into the organic mix.

“That’s crippling the system, and we’ve got to stop it,” Johnson said.

The problem got so bad the city’s composting partner, Blue Ribbon Organics, dropped out of the program this summer. The city continued collecting the food waste and piling it up in a transfer station but, well, nature took its course and “we’ve had to landfill it a few times,” Johnson said.

Johnson said he was hopeful the city will soon be able to find another partner to take the waste and market the compost.

The compost program, which began in 2011 and now includes more than 1,100 households and 40 businesses, collects organic waste including fruit, vegetables, soiled paper products, grease and other food waste. For years, the program has been plagued with participants who haven’t carefully sorted out the non-organic trash.

The path from kitchen to compost typically begins with a small household container provided by the city, which is then dumped in a large black bin to be emptied curbside along with the bins used for trash or recyclables.

While participants take pride in knowing they are diverting food waste from landfills, the process — especially inside the house — can be messy. One popular solution was the biofilm container liners, which feel like plastic but are made of corn or other plant-based material.

“The bags are helpful, but at the same time, the bags lead to problems because they conceal issues,” Johnson said.

Drivers can see what items are being collected through cameras mounted inside the collection trucks. When non-compostable material gets mixed in, it’s often too late. Workers will sometimes use pitchforks to remove the offending items, but non-organic trash isn’t always obvious or even accessible. Just one bag of diapers can ruin an entire day’s collection; one plastic bottle, if it makes its way through the composting shredder, can become hundreds of small pieces that contaminate yards of material.

Consumers may also be confused about what kind of bags are allowable: compostable or biodegradable. Truly compostable bags are intended to break down in 30 to 60 days, while bags marketed as biodegradable can take up to five years to disintegrate.

“Anything’s biodegradable if you wait long enough,” Johnson said.

Despite the problems, Johnson said, the city is not banning the compostable bags but rather asking — very nicely — that participants try going bagless or use some version of a paper bag, like a grocery sack or a bag made of folded newspaper.

“We’re trying to be accommodating; we’re trying to keep people where they are,” Johnson said. “If it’s make or break … well, OK, all right. But please use the right ones, and please use paper bags first.”

Participants who consistently dump prohibited items may get a sticker put on their cart or a letter reminding them of the rules.

It’s not a perfect process, Johnson admitted. In one case, a letter was sent after a driver detected what appeared to be styrofoam egg cartons. The homeowner was able to show the cartons were made of compostable paper.

But those problems are solvable, Johnson said. Just four households have had their carts removed after consistently failing to comply with the rules.

“We’re not going to swoop in and take the cart away without asking questions first,” he said.