biogas

Two Maine Towns Test Food Waste Strategies in Pilot Project

Two Maine communities are engaged in a pilot curbside collections program through which food waste is separated and passed on to an anaerobic digester for processing.

Maine residents, like many throughout the U.S., tend to dump their food waste in the trash. Overall, it’s estimated that 28 percent of what gets tossed out by weight in that state is food. With a statewide goal of 50 percent diversion of all trash by 2021, food waste is a prime target for reduction.

That’s why ecomaine, a nonprofit waste management company, is engaging two Maine communities in a pilot curbside collections program through which food waste is separated and passed on to an anaerobic digester for processing.

As part of the program, residents put food waste in plastic bags in countertop bins or lined containers. It is collected by local haulers and delivered to ecomaine, a nonprofit waste management company, where it is consolidated. From there it is transported to Agri-Cycle, who using a depackaging machine, separates the bags from the garbage. The depackager can even separate expired or damaged packaged food from plastic, metal, polystyrene, or cardboard containers. The food then moves on to an anaerobic digester run by a sister company, Exter Agri-Energy.The plastic bags used for collection are sent back to ecomaine for burning with the rest of the trash the group collects, to produce electricity sold on the grid.

“We needed to address our food waste, and learned there were enough processors across the state to partner with one rather than deal with processing it ourselves,” says Lisa Wolff, communications manager for ecomaine. “But we had to address the ‘ick’ factor, which meant finding a company who would recycle food and deal with contamination effectively,”

Agri-Cycle, which manages the transportation and depackaging, and Exter Agri-Energy which runs the digester, have worked together before in processing food waste from large generators like universities, hospitals, grocers and restaurants.

There are some differences. When dealing with its business clients, the firms do the work of separating food waste from its packaging (expired or damaged strawberries in containers for instance). Plastic, metal, polystyrene or cardboard collected from generators are all recycled. The remaining food waste is pumped into anaerobic digesters to produce biogas, which is burned to produce renewable energy.

With the residential pilot projects, residents are being asked to dispose of minimal packaging in the plastic bags they are tossing food waste into. Things like tea bags and coffee filters are OK, as long as the majority of what’s in the bags is digestible scraps.

Scarborough is one of the two municipalities participating in the pilot. (The other is South Portland.) It’s running the program for eight months through January 2018. It has included food pickups at 251 homes.

For the Scarborough Food Waste Pilot, the hauler is Pine Tree Waste (a Casella subsidiary), and for the South Portland Food Waste Pilot, Garbage to Garden hauls the material.

At Scarborough, trash and recycling pickups are alternated, with food scraps picked up weekly and recycling and trash picked up alternate weeks. South Portland has added weekly food scrap collection in addition to the existing weekly trash/recycling pickup.

Getting residents to participate has gone smoothly so far, according to city officials.

“The depackager has been terrific for us. The feedback we get from residents is that this limits the ick factor, and it’s easy,” says Kerry Grantham, sustainability coordinator for the town of Scarborough.

This system “reduces the waste we haul away. It effectively separates from municipal solid waste. We are giving those bags a second life, and their remains are eventually incinerated to make energy,” she says.

The company providing the service evolved into a partnership to be able to manage collection, an offering it did not provide when the anaerobic digester opened.

“Originally, Exeter Agri was the only company in play. We naively thought that if an anaerobic digester were built, folks would willingly bring their waste to us,” says Sarah Wintle, operations manager for Agri-Cycle. “As it turned out, we had to work a bit harder at securing a regular waste stream, which is when Agri-Cycle was created. Further, as we’ve learned, the waste industry is about transportation and disposal. This partnership covers both,”

In 2016, the company diverted and processed 25,000 tons of solid food waste and 15,000 tons of liquid throughout New England. The material is separated into solid and liquid after it’s run through the digester. The solid material is used as bedding for dairy cows at a local farm and the liquid serves as fertilizer.

Managing the variety of materials has been challenging.

“Some is quite wet while other materials are very dry,” Wintle says. “Getting the right mixture to create an appropriate consistency and the right amount of energy to feed the digester is very much a science. The burden … has fallen on the operators, which they’ve done a great job at managing.”

Meanwhile, ecomaine was sold largely on the concept of being able to address its streams along a waste hierarchy.

“It’s reduce, reuse, recycle, and compost or digest,” Wolff says. “We hit all those rungs, from the lower rung of composting all the way to the higher rung of reuse.” In doing so “we are able to pull resources from the stream, so much less goes to waste to energy or landfill.”

Correction: August 14, 2017
Additional details were incorporated into the third paragraph and more information was inserted in the story regarding the collection cycles in each town.
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