Investing in improvements

The Recology Sonoma Marin business unit of San Francisco-based Recology began commissioning its new material recovery facility (MRF) in late 2023. With the system’s installation, the company sought to increase its processing capacity, upgrade to new technology and improve bale quality, according to Logan Harvey, Recology senior general manager.

Harvey spoke during Recycling Today’s MRF Operations Forum this past October in Chicago about the investment, what has worked well and what he would do differently in hindsight.

New MRF, existing building

The new processing system in Santa Rosa, California, was installed in a building that housed Recology Sonoma Marin’s previous processing system, which the company acquired in 2017 when it purchased North Bay Corp. from the Ratto Group.

Recology Sonoma Marin’s 460 local employee-owners serve 155,000 customers in the communities of Santa Rosa, Rohnert Park, Petaluma, Cotati, Bolinas, Cloverdale, Healdsburg, unincorporated Sonoma County, Novato, Stinson Beach, and West Marin, Logan said. It provides recycling, compost, garbage and construction and demolition collection services; street sweeping; and recycling processing services.

He added that the decision to retain the existing 85,000-square-foot building came with challenges given its low ceilings. This meant tolerances for the new line were as little as a half an inch in some locations throughout the MRF, which was designed and supplied by Machinex, headquartered in Plessisville, Quebec, with North American operations based in High Point, North Carolina.

The firm also had a tight timeline for the project, completing it in 10 months.

“This MRF came in 100 different pieces on 18-wheel trucks, and they were able to put it all in in a very short timeline,” Harvey said.

The $35 million investment included 109 conveyor belts, according to Recology, with their combined length totaling 1.58 miles; seven optical sorters to recover plastics of various types; a magnet to recover steel cans; and an eddy-current separator to recover aluminum cans.

“It’s a really strong system. It really provides peace of mind to our community that the material’s being recycled.” — Logan Harvey of Recology

The system

The MRF receives 300-350 tons per day of what Harvey described as a fairly even mix of residential and commercial material, with contamination ranging from 10-15 percent.

He added that the old MRF could process only a quarter of the incoming material, or about 120 tons. “We had about 200 tons per day of material that we were shipping out to other facilities, paying for that transfer, paying for that haul, and not recovering the material.”

Building a new MRF with more processing capacity would allow Recology Sonoma Marin to internalize processing of all the recyclables it collected, invest in the local community and become more of a regional MRF, Harvey said.

The MRF features two infeed hoppers that go to a manual presort area as the building’s size and space limitations did not allow for the use of auger screens, Harvey said. Recology works to ensure the presort is fully staffed to pull off material that could damage the system if it were to continue.

Next, the material is presented to the old corrugated containers (OCC) screen, which separates it into three fractions based on size.

“We have a small cut, a medium cut and a large cut,” he said. “I like to describe it when I’m giving tours as your tomato paste can, your tomato sauce can and then your big cans of whole tomatoes.”

The small material goes to the glass-cleaning system before being presented to a ballistic separator that separates 2D material from 3D material. The medium-sized fraction also is processed by a ballistic separator, with the paper then going to an optical sorter that removes residual contaminants.

The recovered paper is cleaned by hand, with Harvey saying, “The opticals do such a good job, we don’t really have to staff that super strong. We had four people starting there. We brought that down to two. And when we’re really short-staffed, we can pretty much run it without folks there.”

He said the containers are combined after they go through the ballistic separation and optically sorted to remove OCC. “When we first started, we were just pulling out cardboard,” Harvey said. “But we updated that optical to start firing on [aseptic containers], as well, because we talked to end-market producers, and they were able to handle it.”

The containers are presented to a second optical sorter that recovers polyethylene terephthalate (PET) and high-density polyethylene (HDPE).

“We do a positive sort on all bottles and let the thermoforms run through,” Harvey said of the PET. “We’re able to get a PET A grade and CRV [California Redemption Value] return on the bottles from positive sorting.”

The HDPE goes through another optical, he said, with any remaining contamination being removed by hand.

Polypropylene (PP) and the rest of the containers are presented to another optical sorter that Harvey said is split down the middle. The PP comes out with all other plastics, and then the rest of the material, which should be mostly metal at this point, continues on the line.

While Harvey said Recology incorporated second chances for recovery throughout the system, it didn’t do the same for aluminum, which he acknowledged was a mistake.

“We gave everything a second chance, except for aluminum, which is kind of a bad idea, so we’re seeing quite a bit of it on a residual stream, and that’s where we’re going to be making investments in the future,” he says.

“We’re still largely manual from a sortation standpoint, but we do get a very good bale quality at the end of the day.”

Insights gleaned from operating at scale

Recology Sonoma Marin bales its residual material using a compactor from SSI Shredding Systems Inc., Wilsonville, Oregon, with excess material being top-fed into a possum belly container. However, Harvey said the MRF would benefit from a second residual compactor. “If this goes down or we want to service it, there’s a significant issue. We produce so much material, we’d have to pull that possum belly, every 15-20 minutes.”

He said the MRF also could benefit from adding a third baler to process outbound commodities.

One thing that Harvey said he’d do differently the next time he has to design a MRF is to ensure the motors and gearboxes used throughout the system are as similar as possible, explaining, “You want to have as much redundancy as possible so that you can keep a backlog of equipment and be able to replace it quickly. That’s one of the issues that we have. We can’t stock every single motor in our MRF because we have so many different ones.”

He said the speed at which this project was completed was a factor that worked against ensuring that consistency.

Following the MRF rebuild, Recology added technology from San Francisco-based Glacier on its residual line. The artificial intelligence-enabled camera provides transparency into the recyclables being lost to the MRF’s residuals. “We’ll be investing in either robotics or a small optical system or putting human beings on that residual stream to really capture that material and bring it back in.”

The results

The new MRF improved Recology Sonoma Marin’s processing capacity from 120 tons per day to 300-350 tons per day over one-and-a-half shifts, Harvey said, while its recovery rate increased from 75 percent to 85 percent.

Once the company invests to recover recyclables from its residual line, he expects that recovery rate will climb further.

Recology Sonoma Marin is seeking additional tons to process at the MRF as well. “Our goals right now are to increase the tonnage that we’re allowed to bring into the MRF so that we can go to two full shifts,” Harvey said.

“It’s a really strong system. It really provides peace of mind to our community that the material’s being recycled.”

The author is editorial director of the Recycling Today Media Group and can be contacted at dtoto@gie.net.