In 2009, Americans threw away more than 3.8 million tons of disposable diapers in municipal waste streams. A Trenton, N.J., company is working on a way to keep some of those diapers out of landfills.

'Solving' for trash

Employees at TerraCycle's trendy Trenton headquarters talk about trash like it is an algebra problem. Their challenge is to "solve" for hard-to-recycle items such as Capri Sun drink pouches, cigarette butts, even chewing gum.

Now, they are targeting a seemingly unlikely candidate for recycling: dirty diapers.

At the company's factory-turned-office building, several large plastic bags full of dirty diapers sit in a corner, well removed from the employees there. According to Ernie Simpson, head of research and development at TerraCycle, the 10-gallon plastic zip-top bags, designed to be shipped via FedEx or UPS, solve the first part of the diaper-recycling equation: how to collect dirty diapers without exposing handlers to dangerous bacteria.

"The collection system is the first part," Simpson said. "And until you do the collection process very well, the end products will not be good."

Simpson said his company is one of the best in the recycling business at collections. Companies such as Frito-Lay and Kraft currently sponsor school groups and other organizations in their "brigade" system to gather and ship old chip bags and candy wrappers. TerraCycle, in turn, repurposes them.

Once the diapers land at a recycling facility, though, they will be more complicated than candy wrappers to clean, sort, and reuse. The second step in the process, and one that puts diapers in the "very hard to recycle" category, is figuring out what to do with all that poop.

"That's where the biocide comes in," Simpson said.

After chopping up the collected diapers, Simpson said, a chemical would be sprinkled on them.

"You put the biocide on the dirty diapers, killing all the bacteria, basically neutralizing any fecal matter," Simpson said. "Once that's done, the next step is to basically separate the several layers of the diaper."

For step three, the absorbent stuff--paper pulp and "super-absorber" polymers--would be separated from the diaper's plastic outer covering using an agitator and a series of screens. The plastic would be recycled into things such as paving tiles and fence posts, and the paper pulp would be collected to mix in with recycled plastics. The combination of the biocide and high processing temperatures should get rid of any lingering organic material in the plastic, Simpson said.

"You're not going to be standing out there by a fence post and it smells of poop," Simpson said, laughing.

Simpson's colleague acknowledged there might be a bit of a public relations hurdle to overcome when talking about reusing dirty diapers.

"It's not going to be a hazard," said TerraCycle's Bill Gillum. "Whether people have something else in their mind, possibly, is another matter."

Any possible PR battle is a way down the road. Simpson has tested parts of the process in small batches, and he is currently working with a recycling facility in northeastern Pennsylvania to see if the methods can be scaled up. The company has not yet done an environmental analysis to look at whether the energy it takes to ship, sterilize and repurpose the diapers will still make the process worth it.

Previous attempts abandoned

TerraCycle is not the first company to attempt diaper recycling. A small program in California backed by U.K.-based recycling company Knowaste went no further than the pilot, though the company is currently building a diaper-recycling facility in England. A pilot program in Seattle backed by Procter & Gamble Co. in the early 1990s was abandoned because it just wasn't efficient.

"While it might look intuitively like a good idea, once you put the facts and the science on the table, then it might look a little bit different," said Procter & Gamble's Ioannis Hatzopoulos.

The company abandoned the idea of recycling diapers and instead focused on using less material to produce them. TerraCycle said its model is different from previous attempts because it wouldn't use water to wash the diapers before they are recycled.

Philadelphia mom Tamara Sepe is in the small minority of parents who doesn't use disposable diapers, partly because of their environmental impact. She opts for cloth instead.

"We definitely get some eye-rolling from some family members," Sepe said. "Some are like 'Are you guys still doing that?'"

She said if diaper recycling came to Philadelphia, she might think about using disposables more often, but she would need more information on how green the process really is.

"I wouldn't rule it out," Sepe said. "Maybe I would consider using disposables during the day more."

TerraCycle hopes to have a small pilot program up and running before the end of the year.