How mixing trash and recycling can work

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Roughly two-thirds of the cost of recycling comes from the time- and labor-intensive collection phase, when fleets of trucks gather the recyclables from thousands of curbsides, then bring them to the local materials recovery facility (MRF) for sorting. But this phase also accounts for some of recycling’s worst headaches (see Recycling meets reality), mainly because consumers keep filling their bins with dirty diapers, spoiled food and other rubbish that shouldn’t be there.

In fairness, many consumers find the list of what should and shouldn’t go into the bin to be arbitrary, confusing and hard to keep track of. Witness the plastic take-out container that’s recyclable in Palo Alto, California, but not in Mountain View, the next town over. (Or is it the other way around?) Ultimately, however, the list is determined by what items can and can’t be sorted at the local MRF – which is why innovators are constantly trying to ease the collection problem by expanding what the MRFs can do.

Take the example of flexible plastics, an exasperating category that includes filmy shopping bags, bubble wrap, microwavable food pouches, chip bags and much more, all of which are supposed to go into the garbage and not the blue bin. The bags, at least, can be recycled separately if you take them back to the grocery store for collection. But flexible plastics tossed into the blue bin are among the first items that the workers in any MRF will pull out and send to the landfill. Otherwise, the things would either get tangled in the sorting machines, or become contaminants in the paper stream.

Newer machines equipped with anti-tangling technology can help. But last year a working MRF in Berks County, Pennsylvania, demonstrated a more fundamental solution: It asked the consumers in its area to toss their flexible plastics into the blue bin along with all the rest. Then, with funding from an industry group, the American Chemistry Council, it showed that it could still sort everything into clean bales through the use of anti-tangling screens coupled with advanced optical sorters to separate flexible plastics from paper. So when and if this new sorting technology is more widely deployed — a big question mark during the current economic crisis — the industry could end up recycling (and earning money on) several hundred million tons of plastic per year that are now lost.

Meanwhile, other innovators hope to take this same logic to its ultimate conclusion, which is to quit fighting contamination and embrace it. Tell consumers to ditch the blue bin and instead toss their recyclables in with the garbage. Then take the stuff to a mixed-waste processing facility that can sort it all — bales for recycling over here, food and other organics for composting over there, and a couple of (hopefully smaller) piles off to the side for landfills and waste-to-energy incinerators.

This is not a new idea. Chicago, for example, is still operating the three mixed-waste plants that it opened in 1992, while several dozen more are operating elsewhere in the United States. And it’s true that the mixed-waste approach can cut collection costs: one truck, one trip. Better still, it can boost recycling rates. Currently, single-stream recycling has stalled out at roughly 20 percent of all municipal solid waste, largely because it doesn’t work well in apartment buildings or offices. Mixed-waste processing can potentially get that figure up to something like 50 percent, and capture the large fraction of recyclable materials that still end up in landfills.

So why isn’t everyone doing this? “It’s a dirty business,” says Republic Services vice president Pete Keller, whose Arizona-based company runs several mixed-waste facilities — or, as they’re commonly known in the business, “dirty MRFs.” Imagine the contents of your kitchen trash can, with coffee grounds, spoiled leftovers, chicken bones, greasy pizza boxes and all the rest. And now imagine scaling that up to a thousand tons per day.

To get the kind of high-quality, clean bales of plastic, metal and glass that today’s market demands, says Keller, you’ve first got to rinse off all the food and such into an organic fraction, which can either be composted or run through an anaerobic digester that turns it into synthetic natural gas. But the process also turns a lot of the paper and cardboard into a pulpy mess that has to be separated and dried. This kind of thing is why the economics of mixed-waste processing is iffy, says Keller: “It’s hard to extract value.”

And yet, the technology for mixed-waste processing keeps improving, and people keep trying. Both the promise and the pitfalls are exemplified by a plant that Coastal Resources of Maine opened with great fanfare in April 2019, in the town of Hampden outside Bangor. The closely watched project was the first commercial demonstration of an integrated, highly automated mixed-waste system developed by the Maryland-based firm Fiberight. And although the specifics of Fiberight’s system are proprietary, the technology did seem to work as advertised. The plant took in raw trash; pulled out all the toaster ovens and other big pieces; separated the rest into clean streams of plastics, metals, organics and marketable pulp paper; recycled the wash water; and powered the whole operation with synthetic natural gas produced on-site from material that would otherwise be destined for a landfill. Outside observers were impressed. “They’re able to do 50 percent recovery of material, maybe up to 70 percent,” said Bradley Kelley, an engineer with the waste management consulting firm Gershman, Brickner & Bratton, Inc. in McLean, Virginia. “It’s a real paradigm shift.”

But that was before May 2020, when economic reality hit. Unable to pay its bills in the face of permitting delays, higher-than-expected startup costs and the post-National Sword fall in commodity prices, the Hampden plant was forced to cease operation and go into receivership. The only good news was that none of the problems invalidated the technology — which may be why in July, at least four companies had expressed interest in buying the plant and restarting it. So the story may not be over yet.



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