Paying dividends

Casella Waste Systems’ recent $20 million investment in its Willimantic, Connecticut, material recovery facility (MRF) has doubled throughput to 25-30 tons per hour, reduced processing time from 21 hours per day to only eight hours and reduced energy consumption by about 46 percent per ton of material processed, according to company officials.

The Willimantic facility has gone from processing about 60,000 tons of recyclables annually before the upgrade to having the capacity to process up to 165,000 tons of material, the Rutland, Vermont-based company adds.

The investment was considerable, but when Casella bought the MRF in 2021, it knew an upgrade soon would be necessary as the existing single-stream sorting equipment had been installed decades earlier.

“We came into this acquisition knowing that we were inheriting a 2008-installed piece of equipment,” Michael Crowell, Casella market area manager, says.

From old to new

Casella discovered that the existing equipment, which originally was designed to process 20 tons per hour, could only process 15 tons per hour as it aged. During the years leading up to Casella’s purchase of the MRF, it had been running 21-22 hours every day to process the material coming into the facility.

“The typical life of processing equipment, from a MRF standpoint, is 10 years,” says Bob Cappadona, vice president of resource solutions. “If it was installed in 2008, and it was 2024 when we replaced it, it was well past its life.”

The new equipment includes modern optical sorters that have reduced the amount of plastics and other contaminants that make their way into OCC (old corrugated containers), sorted residential paper and newspaper bales at the end of the line.

Casella began designing the improvements in spring 2022. In July 2024, the company received approval from the Connecticut Department of Energy and Environmental Protection to deconstruct the old system and upgrade the facility. During the closure, most materials were diverted to other locations, but metals and mattresses continued to be processed on-site.

The upgraded MRF opened in February of this year, and Casella unveiled it to the public in May. The sorting system incorporates cutting-edge technology:

• four optical sorters for cleaning fiber;
• one ballistic separator in the finishing position;
• two optical sorters on the commingled material line that target plastics;
• aspiration points for plastic film removal; and
• a glass processing system.

Since the upgrade, the optical sorters incorporated in the line are more numerous and larger, going from 3-feet wide to 10-feet wide, Crowell says.

“We went from older, inefficient technology to a greatly enhanced, superior technology that has totally changed our sorting capabilities.”

Goodbye disc screens

What might have been the most significant technological upgrade involved using optical sorters to separate containers, like detergent and soda bottles, from fiber, like paper and OCC, Cappadona says. Disc screens previously performed this 2D from 3D material separation.

“Having over 25 years in the industry, I was skeptical of the optical sorting from a fiber standpoint,” Cappadona says. “I will tell you it works fantastically. Machinex has tremendous opticals, not only to capture a detergent bottle from a soda bottle from a milk jug but also to kick out fiber by itself, which traditionally was done with disc screens.”

Machinex optical sorters use near-infrared (NIR) spectroscopy and visible spectrum cameras to identify materials based on their spectral signatures and other attributes. These technologies allow the system to distinguish different types of plastics, such as high-density polyethylene, polyethylene terephthalate (PET) and polypropylene, and fibers by analyzing how they reflect light. Once identified, materials are separated using precision air jets that direct them to the appropriate stream.

The system also removes low-density polyethylene film, for which there is currently no recycling market, from the material stream. Its removal early in the sorting process prevents contamination and mechanical issues caused by the film wrapping around the system’s articulating and oscillating components.

“Notably, the film capture system is designed to be retrofitted in the future to divert captured film from the residue bunker to a potential end market,” Jeff Weld, vice president of communications at Casella, says.

Optical evolution

Over the years, Plessisville, Quebec-based Machinex has refined its existing optical sorting technology to be more accurate when separating paper and OCC from plastics, Sébastien Roy, sales project director at Machinex, says. “Over the years, we went through several iterations of different lighting systems, which improved the recognition of fiber.”

While declining to go into details because of its proprietary technology, Machinex uses different types of lighting systems depending on the application.

The improved optical sorting means that Machinex “doesn’t really use mechanical screens anymore for large paper sorting,” Roy says. Its customers need fewer sorting personnel and end up with higher material quality as results.

Machinex says it chose to work with hyperspectral NIR cameras because of their ability to provide a broader and more detailed spectrum, resulting in better accuracy for fiber and plastics sorting.

Impressive results

The results of the upgraded sorting system at Willimantic have been impressive not only because of the increased throughput and the reduced hours of operation but also because of significantly reduced contamination in the bales of fiber. Using the old system, anywhere from 6-10 percent of the material in the paper and OCC bales would be contamination, such as PET bottles or aluminum cans. With the new system, only about 1 percent of the material in fiber bales shouldn’t be there, Crowell says.

In addition, uptime has improved with the new processing equipment, which is operating about 84 percent of the time the MRF is open, he says. That includes idle times when employees are on breaks.

“To be that high, in the mid to high 80s … it’s been fantastic,” Crowell adds.

While the throughput increased and the number of hours of operation decreased, no Casella employees lost their jobs due to the company’s ability to transfer workers to other areas, Crowell said.

Casella and Machinex previously worked together on other projects, including a major retrofit in 2023 at an even larger MRF Casella operates in Boston.

The upgrade at the Willimantic MRF was very smooth, according to Crowell.

“At the time that we pushed the button [to start the sorting line], I had been doing this for 28-plus years and had gone through dozens of sometimes great, sometimes painful installs and upgrades and renovations,” he says. “This thing is just what I’ve been waiting for my whole recycling career. It’s just amazing at sorting and separating. It actually does what you were told it was going to do, and the quality recovery is absolutely amazing.”

“We went from older, inefficient technology to a greatly enhanced, superior technology that has totally changed our sorting capabilities.” — Michael Crowell, Casella Waste Systems market area manager

Improving energy efficiency

In addition to working with Machinex on the new sorting equipment, Casella turned to the local utility company Eversource for help identifying ways to upgrade the facility’s electric system and reduce energy consumption.

“We needed a completely new power level to get this system going,” Crowell says. “We needed to replace the entire 1,600-volt system because we needed a 3,200-volt system to run this equipment.”

To conserve energy, Casella installed high-efficiency variable frequency drive motors, energy-efficient air compressors/dryers and real-time energy monitoring.

“These improvements have led to about a 46 percent reduction in energy use per ton of material going through the system,” Crowell says. “It’s been a wonderful partnership with Eversource. We actually had some financial incentives from them because of all the upgrades that we implemented as a company.”

Other upgrades included new lighting, a replacement tipping floor and an enhanced fire suppression system.

Throughout the entire building, mercury vapor lights were replaced with LED lighting. “It was definitely antiquated,” Crowell says of the old lighting system.

Not all the improvements involved upgrading technology. Casella installed a new tipping floor that will make it easier for skid-steer operators

“From an operator standpoint, you’re not running over cement that has been there forever and a day,” Crowell says. “A professional company came in, and it’s 10 inches thick. It’s got rebar, and it’s all tied together. You know you’re investing right. It’s smooth. There are no bumps. You’re going to get greater wear-and-tear life out of all the skid-steer or pay-loader tires. There are no ups and downs with the trucks backing in.”

All these improvements add up to equal operational efficiencies at Casella’s Willimantic MRF.

The author is a Cleveland-area-based freelancer and can be contacted at bgeiselman@gmail.com.