A conveyer belt extends from Missoula’s wastewater treatment plant near Mullan Road, reaches over the fence to EKO Compost and continually drops its load into a big brown pile.
“As you can see right here, this is where the biosolids come from the sewer plant,” says plant manager Terry Munnerlyn. “That’s digested sludge, so you can see it’s kind of in a cake form.”
Follow that fecal cake over months, through closely monitored aerobic decomposition with Missoula’s discarded leaves and limbs, and it ultimately ends up in many a backyard garden. But as Missoulians get their hands dirty during spring planting season, few seem to know the origins of their compost soil.
“I think we’re overlooked a lot of the time,” says Munnerlyn, “because we’ve been here for so long that nobody’s done without us to find out where it would (otherwise) go.”
Since 1977, this conveyer belt has delivered almost all of Missoula’s dewatered sewer sludge to EKO Compost for recycling. About 120 cubic yards of human waste arrive here each day, six days a week, totaling more than 2,000 dry tons per year. And more gets trucked in from Idaho cities Post Falls and Hayden Lake.
“It gives me a form of nitrogen to start the composting process, and it keeps it away from the landfill and land applications, too,” Munnerlyn says. “We’re a full-cycle recycle operation here. What we do is take this from the city, and we take for free leaves, limbs, lawn clipping and brush from the city and the public” (including about 10,000 Christmas trees last year).
After the concoction is “cooked” for 90 days by the 155-degree-plus heat produced by microorganisms, it’s aged, sorted and sifted. The mix then comes out the other end—to specifications set by the Environmental Protection Agency (EPA) and Montana’s Department of Environmental Quality—as a marketable product perfect for enriching soil, Munnerlyn explains.
“It’s safe for the environment, it’s safe for people, it’s safe for gardens,” he says. “It’s just totally safe.”
Missoula’s EKO Compost, employing 14 people full-time, sells about 50,000 yards of compost each year in bulk or in bags. Its biggest buyer is Home Depot, which sells it in stores as far away as Utah. EKO Compost varieties are also available at Marchie’s, Pink Grizzly and Caras nurseries, as well as at Ace Hardware in Tremper’s Shopping Center.
Of the country’s roughly 7.2 million dry tons of biosolids produced each year, about 55 percent is reused. The majority is applied to agriculture lands as fertilizer—as was done with Missoula’s biosolids prior to 1977. About a quarter is broken down into higher-grade products like compost and heat-dried pellet fertilizer. In 2007, there were an estimated 200 sewage sludge composting sites around the country, together producing about 417,000 tons of compost, according to a North East Biosolids and Residuals Association report. Five biosolids composting facilities currently operate in Montana.
The reuse of sewage sludge has its critics. Some say human illnesses and livestock deaths can be attributed to pathogens found in the millions of tons of sludge applied to farm fields. Fewer question the potential health hazards of composting the waste. And there are those—including some Missoula residents living near EKO Compost and the wastewater plant—who complain of odors.
But Eugene DeMichele of the National Biosolids Partnership thinks most concerns are unfounded, the product of some instinctive poop aversion.
“There’s this whole human reaction to anything that looks or sounds like the use of human waste and toilet waste for anything that might be beneficial,” he says. “There are probably 10 or 15 people in the U.S. who have taken it upon themselves to be active opponents to the use of municipal solids for anything at all. They would prefer having it shipped to some other country, or maybe put someplace where no one had to see it or look at it or mention it again. We’re not in that kind of an environment. You have to deal with things the way they are.”
Recently, though, the prevalence of chemicals in sewage sludge has become a growing concern. A January 2009 EPA report summarized the findings of its recent national sewage sludge survey. Samples from 74 wastewater treatments facilities found 145 chemicals, including pharmaceuticals, steroids, hormones, metals and flame retardants. Three pharmaceuticals and three steroids were found in every sample taken. It’s findings like these that led the Sierra Club to recommend not using sewage sludge products on home vegetable gardens.
In Missoula, the wastewater plant tests its sludge for metals (the levels are well below the limits set by the EPA), says pretreatment supervisor Sherri Kenyon, but not for pharmaceuticals. She explains that the composting process’s ability to break down such chemicals remains unclear and the subject of ongoing research.
“To me, it seems there’s a high probability that if there are any [chemicals] coming from our dewatered sludge, that they could be further removed from the composting process at EKO Compost.”
In any case, Missoulians will keep pooping, and EKO Compost, as it has for 32 years, will keep turning it into something many of us, as we tend to our gardens, will actually pay money for.
“It’s been a hard journey,” Munnerlyn says, standing amid mounds of warm, earthy compost. “But now people are understanding it more, and we’re accepted as being the biosolids compost.”