From flush to fertilizer: City farms recycle waste
While most Americans don’t farm, they do contribute to agriculture by buying food at stores and restaurants. And about half of us make an additional donation in the form of fertilizer. With spring at hand, farmers are getting ready for planting. That means enriching the soil and that may just involve you.
Farmers all over the Midwest know that fertilizer is an expensive input. Faced with millions of tons of sewage to dispose of, Kansas City, Mo., is killing two birds with one stone – using that sewage by land-applying treated human waste as fertilizer on a city-owned farm. The city can actually use some of its waste to make money on the farm instead of burning money burning solid waste. For a Midwestern city nestled in farm country, it’s almost a no-brainer.
On a normal day, Kansas City processes more than 70 million gallons of raw sewage. The city runs much of the heavier goop through a process called anaerobic digestion, and then pipes it out to its own 1,350-acre farm on the north side of the Missouri River, near the Ameristar Casino.
Tim Walters is the chief agronomist for Kansas City – the municipal farmer, so to speak. He has the farm plumbed with what could be mistaken for sewer mains, except the pipes don’t collect smelly stuff, they disperse it. A couple of times a year thick jets of processed sewage arc out 30 or 40 feet from giant, moving spreaders.
“It’s black, black gold,” Walters said. “Looks like grease. Doesn’t smell like grease, but it looks like grease, and when you get it on you it’s hard to get off.”
It’s also packed with nutrients good for the corn and soybeans Walters grows, generating almost half a million dollars in profits for the city each year. Walters figures the free fertilizer is worth about $175,000 a year in last year’s prices. And it’s in short supply.
“Every year we typically run out,” Walters said. “They can’t digest enough, they can’t get enough down to us.”
The city’s two digesters run all the time but can’t keep up with Walters demand, let alone the city’s supply. Still, more than half the processed sludge, or “biosolids,” is put to use, which makes Kansas City just about average for the U.S., according to Ned Beecher, who directs the North East Biosolids and Residuals Association.
“It’s actually been a pretty routine practice in a lot of places,” Beecher said. “In the U.S. about 55 percent of the sewage sludge that’s produced at waste water treatment plants is recycled as biosolids.”
Beecher said cities across the country, from Boston to Chicago to LA, sell or use most, if not all, of their human waste to fertilize plants.
“Hay and corn for dairy cows and such, but it’s also used on soybeans, on wheat, on hops for beer, grapes, wine making,” Beecher said.
There’s nothing new about using human waste for fertilizer. Jamie Staufenbeil markets a product called Milorganite, a lawn and garden fertilizer made from sewage collected in Milwaukee, Wis. Staufenbeil said the city refines this stuff so much that it’s safe for any kind of use.
“We just reached 9 billion pounds of Milorgonite sold into the marketplace,” Staufenbeil boasted.
Profits from the sale of Milorganite off-set sewer fees for Milwaukee residents and lots of cities sell similar products. Amarillo, Texas calls theirs Dillo-Dirt and Seattle offers Loop, for instance. Hundreds of waste water treatment plants collect methane and burn it for energy.
Some waste still wasted
But even with all the well-established, beneficial, and even lucrative ways to dispose of solid waste, a lot of it still ends up in landfills or being processed at big industrial incinerators.
Shaun O’Kelley, runs the incineration facility in Kansas City, burning human waste down to a fine ash – and using lots of natural gas, electricity and manpower to do it. The incinerator no longer runs all the time, but O’Kelley is about to fire it up again because for now, in Kansas City, burning some human waste is cheaper than recycling all of it.
“Land application has its challenges too,” O’Kelley said. “The USDA, the EPA with regulations – plus you have to have the land available and the capital. It’s always economics, it’s always money.”
And biosolids, as well as biogas, are corrosive, according to Walters. Plus, well, there’s the smell; residents aren’t always pleased to have an expanding “biosolids” application program in their back yard.
So, the drive to make good use of human waste has been largely stalled for years and despite a steady stream of innovations, almost half of it is still wasted.
Kansas City Doesn't Waste Its Waste - See how Kansas City uses some of its human waste to fertilize the fields of its city-owned corn and soybean farm.