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Science

Altered Habitats

Massachusetts food waste will be composted, fed to microbes

Students at Andover High School searched through bags of cafeteria trash as they sorted items for composting, recycling, and trash as part of a waste audit of their school in 2013.

Joanne Rathe The Boston Globe

Students at Andover High School searched through bags of cafeteria trash as they sorted items for composting, recycling, and trash as part of a waste audit of their school in 2013.

When Torontonians push back from the dinner table, they give their food scraps to the bugs.

They scrape leftovers into a special green bin, which is collected each week by the city, and eventually poured into a vat with microbes that eat it, producing useable biogas.

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Bostonians are not being asked to do that, yet. Massachusetts is taking a different approach: Starting Oct. 1, food waste from large institutions and supermarkets — not residents — will be collected. And only some of that will go to bugs.

“It’s an opposite approach. But I wouldn’t say it should be either/or. Both are needed,” said Franz Hartmann, head of the Toronto Environmental Alliance, which has watched the program there work for 12 years.

Massachusetts’ new food waste ban, which was a decade in the making, puts the commonwealth among leaders in the United States in addressing an indulgence that is unique to our modern existence: throwing away large quantities of food. But the US is behind cities in Canada and Europe, where such organic waste already is collected and converted to good use. In Germany alone, there are 6,800 food waste processing plants.

“We want to find alternatives, and disposing of solid waste is expensive,” said Greg Cooper, who is head of commercial recycling for the Massachusetts Department of Environmental Protection. “We are starting to see a shift from throwing everything away.”

Cooper sees the ban, which applies only to businesses or institutions with more than one ton of waste per week, as discouraging waste in several ways.

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“We want to look at the full menu: Are you ordering the right amount of food? Can you reduce the amount you buy to ensure less ends up going in the trash?” Secondly, he said, he expects more supermarkets and institutions will donate edible food to soup kitchens and food banks. And some businesses will build facilities to handle the waste on-site: Stop & Shop is doing that in Freetown, which will handle the unbought returns from 213 of its stores.

Much of the remainder will be made into compost. WeCare Environmental composts trash, sludge, and food waste in Marlborough and sells the result to farmers, sand and gravel mixers, and other users.

Drying out the mixture, with wood-chip filters designed to cut odors, can be tricky, noted Philip McCarthy, president of the company. “Pure waste is mostly water. You have to balance it out,” he said. And straight composting does not capture the methane gas produced in decomposition, a potent greenhouse gas.

The more complete solution, according to many environmentalists and an increasing number of businesspersons, is using bacteria in anaerobic digestion. Food scraps and all sorts of other organic waste — from pet poop to coffee grounds — can be fed to microbes in a heated tank without oxygen. In about a month or less, the microbes will consume most of the material, converting it to a biogas — mostly methane -- that can be captured and used to generate electricity.

That digestion happens in cow stomachs, and stock farmers around the country have been installing anaerobic digesters to handle animal waste. There are three such farms in Massachusetts, which will gladly be accepting food waste under the new regulations. About six wastewater treatment plants in the state also use the process to reduce the volume of sludge. The egg-shaped buildings visible on Deer Island in the Boston Harbor do that to make power for the sewage treatment process. The state is offering $3 million in low-interest loans to encourage new facilities.

But when Anton Finelli and his partners, who run a composting-to-biogas power generating station at the New Bedford landfill, began thinking about enlisting microbes in their business, “we were shocked to discover you could count on one hand the anaerobic digestion projects in North America designed specifically to take and process municipal organic waste,” Finelli said.

His company, CommonWealth Resource Management Corp., is building a pilot plant at the landfill site in Dartmouth, and hopes to expand if it works well and attracts customers. “We’re taking a ‘build-it-and-they-will-come’ approach,” he said.

Cooper agrees. He thinks the new ban will spur construction of more anaerobic digestion and other solutions to organic waste. Businesses will see those solutions are cheaper than paying to haul away waste, and microbes can make more renewable electricity for the grid. Eventually, he said, residential customers may see the benefits of using a separate pail to collect their food.

“Right now, we are just focused on these larger commercial structures first, in hopes that vibrant infrastructure will be developed,” Cooper said. Reaction from the business community has been good, he said. “We’re getting no blowback at all.”

Toronto’s residential program also has been popular. “By and large, it’s worked very well here,” said Hartmann, and nearly 90 percent of households in Toronto’s 460,000 single-family dwellings use the green bins. “When we understand the stuff going out the door is actually a valuable resource, we start to treat it differently,” he said. “Organics are way, way too precious to dispose of.”

Doug Struck has been a journalist for 35 years and reports on environmental matters from Boston. He can be reached at doug@dougstruck.com.

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