Residents see how waste becomes compost

Anne Ludvik of Specialized Environmental Technologies explains the benefits of using compost to Minneapolis residents after a tour of the Rosemount composting facility on June 3. Photo by Nate Gotlieb

Several dozen Minneapolis residents saw firsthand on June 3 what happens to the city’s organic waste.

About 45 residents toured the site that receives the city’s organic waste, a Rosemount facility operated by the company Specialized Environmental Technologies. The company takes that waste and turns it into the compost used in lawns, gardens and more, a process that takes about six months to a year.

SET weighs the organic waste when it arrives and checks it for contaminants such as plastics, metal and glass. The company will accept waste with up to 10-percent contamination, according to Anne Ludvik, director of organics policy development, though it would like that rate to be 0 percent. Minneapolis’ contamination rate is 0.5 percent.

“We love material from the city of Minneapolis because it makes good compost for us,” Ludvik said.

A view of the Rosemount site the company Specialized Environmental Technologies uses to create compost.
A view of the Rosemount site the company Specialized Environmental Technologies uses to create compost.

SET combines the nitrogen-rich organic waste with carbon-rich yard waste. A giant mixer blends the wastes together, spinning slowly enough so that contaminants such as bottles won’t break apart. The company then uses a tractor to spread the mixture into long piles called windrows.

SET runs air under the windrows, providing oxygen that allows bacteria to decompose the waste material. The process generates a lot of heat, causing the windrows to heat up to as high as 160–170 degrees, even in the middle of winter.

SET monitors the temperature of the windrows daily to ensure they don’t become too hot and kill the good bacteria, Ludvik said.

State law requires the windrows to stay at least 131 degrees for seven straight days, a temperature and timeframe that will kill any pathogens and bacteria. SET keeps its windrows at 140–160 degrees for 45–60 days, Ludvik said.

The company then takes the windrows down and puts the compost mixture into curing piles, where it sits for about six months. It’s during that process that paper products break down, Ludvik said.

The curing piles get turned over several times, with the mixture gradually cooling. SET screens all of its compost after the curing process, testing each batch before it’s ready for market, Ludvik said. It makes the testing data available to its customers, should they want compost with a specific pH level.

A tractor spreads a mixture of yard waste and organic waste into a long pile called a windrow.
A tractor spreads a mixture of yard waste and organic waste into a long pile called a windrow.

The company will deliver its products anywhere in the Twin Cities metro area, Ludvik said. It gives more than 600 yards of free compost to Minneapolis for community gardens annually and also sells compost to community gardens at a 50-percent discount.

SET took in over 17,000 pounds of food waste last year and sold about 65,000 yards of material at several sites, Ludvik said. She said the company’s 37-acre site in Dakota County is ideal, even though it’s next to a dog park. The site doesn’t have much of an odor because of the oxygen pumped through the windrows, and the site hasn’t received a single odor complaint in the past eight years.

SET has been open since the 1980s, when Minnesota passed a ban on putting yard waste into landfills, and it began taking food waste in 1997. The company received a full solid-waste composting permit in 2001 and recently applied for a new tier of compost permitting. The permit would allow the site to double its capacity, Ludvik said.

SET contracts with Minneapolis, St. Louis Park, private companies and the general public for composting services.

Minneapolis began curbside collection of organics in fall 2015 and has reduced over 256,000 gallons of garbage volume over that stretch, according to Kellie Kish, the city’s recycling coordinator. About 45,000 households, or 42.6 percent of those in the city, have opted into the citywide program, which is a year old. Kish said that is an extremely high rate.

That participation has led to a decrease in garbage carts, Kish added.

She stressed that plastic-lined paper, such as ice cream containers, Chinese takeout containers and decorative paper plates cannot go into the organics bins. Neither can coffee cups, unless they say they are compostable.

Wedge resident Arin Sheahan said she though the tour was pretty cool and that it made her feel a renewed commitment to do the proper thing when it comes to organics recycling. Sheahan added that it gave her new ideas on how to participate, despite the fact that she doesn’t live in a house.

Visit for a complete list of acceptable organics and to opt into the program.