CHARLESTOWN, Mass. — One end of Casella’s Charlestown zero-sort facility is a chaotic mess — piles of trash pushed around by big bulldozers.

The other end is all geometric order, row upon row of massive bales of cardboard boxes — or newspapers, or plastic bags or aluminum cans — crushed square and stacked to the ceiling, waiting to be trucked out to commodity buyers.

What happens in between the two is an industrial process that relies on technology, speed and a few people to transform tons of curbside waste into marketable commodities ready for manufacturing.

It’s what happens in the middle that matters to Lewiston residents right now.

The company is hoping to build a facility just like the one in Charlestown, but smaller, immediately south of Lewiston’s municipal landfill.

The Charlestown facility sorts 190,000 tons of recyclable material per year, bringing in trucks from around Massachusetts and Maine — including Lewiston.

The Lewiston facility, if it gets built, would process up to 45,000 tons of recycling per year at full capacity — all of it from Lewiston and other Maine communities. To start, the facility would process 20,000 tons of curbside recycling per year.

“We control 20,000 tons of recycling in the state of Maine right now that we don’t want to bring across state lines,” said Dan Emerson, manager of Casella subsidiary KTI Biofuels in Lewiston and the would-be manager of the Lewiston recycling facility.

“So right there, you can see there would be no recycling going across state lines, in or out, going to Lewiston,” Emerson said. “That means no out-of-state waste going into Lewiston, period. Ever. Put it in the contract; put it in the lease. We already have the tons of recycling we need in-state.”

City Administrator Ed Barrett said he and company officials are hammering out the details of the lease.

The rough outline, approved by city councilors at their Aug. 13 meeting, calls for a 30-year lease with the company taking over the current recycling transfer station to construct a 15,000-square-foot automated sorting facility. The company would pay the city to lease the land as well as property taxes, and would employ 25 people upon opening.

City staff is negotiating a lease contract with Casella, and a draft of the contract could go to councilors later this year.

Casella has two Material Recycling facilities in Massachusetts, a plant in Auburn, Mass., and the one in Charlestown. They all follow the same process, one the company has tried to copyright as “Zero-Sort.”

“That’s our brand, instead of ‘single stream,'” said Bob Cappadona, vice president of recycling. “From the beginning to the end, we design equipment, we have the expertise to process it. From beginning to end, we have that expertise that some don’t.”

The process starts at 3:30 a.m. daily. Trucks come throughout the day, dumping piles of recyclables at the mouth of the facility.

“Over the course of a day, they’ll bring in 750 tons,” Cappadona said. “That’s processed in two shifts and is all finished by 11:30 p.m., all 750 tons, every day.”

The materials come in unsorted, collected curbside from Boston, Cambridge and surrounding towns.

First, bulldozers push the piles of refuse onto a long conveyor belt. Heavy chains hung over the belt smooth the pile into a consistent height as it begins its way up the conveyor and into the machine.

The first step requires the most people on the line. They tear open bags and pull out anything that can’t be recycled or doesn’t belong there — including Styrofoam, light bulbs, insulation and large pieces of scrap metal and hard plastics. The metal and hard plastic are recycled by hand. Nonrecyclables are sent to a landfill.

“This is garbage,” Cappadona said. “It’s presorted, and our people have three jobs here. We want to get stuff that might damage our equipment, pick out the scrap metal and hard plastics.”

Cappadona said the presort stage accounts for much of the nonrecyclable waste that eventually makes its way to a landfill. The facility is able to successfully reclaim about 93 percent of the materials put out curbside.

“The rest, that 7 percent, this is a lot of it,” he said. “It’s something we try and fix with education, teaching people what can be recycled and what can’t.”

Next on the line, rows of rotating discs sort large chunks of cardboard from the rest. Cardboard goes one way, everything else continues down the line.

Glass bottles and jars are broken into 3-inch shards and sifted from the pile. Those bits collect on the floor near the front of the building, where they are scooped up and shipped off to a plant in Franklin, Mass. There, they’re sorted by color — clear, green and brown — crushed and sent to a third plant in Milford, Mass., for re-manufacturing.

“They’ll go through a process that ends up making new wine bottles,” Cappadona said.

The sorting line picks up speed at that point. The pile runs through a series of optical scanners, each looking for different kinds of plastic. When the system detects the right kind of plastic, it shoots a puff of air that lofts the plastic piece onto the proper conveyor.

Similarly, a magnetic eddy current at the end of one conveyor pops aluminum cans up and onto their own conveyor, while the remains continue down the line. Finally, a powerful magnet pulls metal cans out, leaving only paper on the conveyor.

Now sorted, the materials are compressed into 4-foot by 8-foot bales of like material, and stacked for storage until they can be sold on the commodities market.

“We are right around the corner from the shipyard here,” Cappadona said. “We can take it anywhere in the world if we have to, wherever we can get the best price.” The Charlestown plant employs 108 people in two shifts. The company plans to start the Lewiston plant with 25 employees on a single shift, most of them monitoring the line as the recycling winds its way along the plant’s conveyors.

“It’s an amazing process to see,” Cappadona said. “We are very proud of it and we like to show it off and show people that it really is happening, this material really is being recycled. It’s taken out of the waste stream and turned from something that was going into a landfill into something that really is useful.”

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Editor’s note: Staff Writer Scott Taylor and Chief Photographer Russ Dillingham traveled to Charlestown, Mass., on Aug. 16 to tour the Casella plant in the Bunker Hill Industrial Park for this report.