The digester eggs on Newtown Creek in New York City. [Image credit: Wikimedia Commons | public domain]
Dany Nelson of the Bronx is a big guy. When he went vegan a few years back, he ate dozens of bananas a day to make up for the animal products he’d cut from his diet. But where to put the peels?
Nelson had heard that food waste shouldn’t be sent to a landfill. Like most New Yorkers, he didn’t have a garbage disposal, but he did have a community garden next door. So he started throwing his peels out the window. “To me, composting meant just throw it on the ground and the Earth will eat up,” he says. But composting is actually a more complicated process. Though his intentions were pure, Nelson was littering.
Vermin attracted to all those banana peels soon overran the garden and the head of the Bronx Botanic Garden was sent to investigate. She caught Nelson, but instead of pursuing more punitive measures, she extended an invitation to join the borough’s master composting program and learn to do it right.
But there may have been another, faster way: using a kitchen grinder, also known as a garbage disposal or simply an InSinkErator, which is one of the most popular brand names. Ranging anywhere from a $100 self-installation to $600 for professional help, Nelson could have pulped his waste and sent it swirling to one of the city’s new energy-generating wastewater facilities.
What’s more, if the city came together and installed garbage disposals in Nelson’s and every other New Yorker’s apartment, the city could meet its stated goal of zero waste by 2030 and create plenty of renewable energy in the process. Or at least that’s the belief of Kendall Christiansen, a stalwart in New York City’s vibrant trash management community and environmental consultant for InSinkErator.
“It goes down the same sewer that your toilets and your washing machine and shower goes,” Christiansen says. “Modern wastewater treatment has really shifted from thinking of wastewater as a problem to thinking of it actually as a resource.”
Cities from Washington, D.C. to Philadelphia and Milwaukee to Seattle, have adopted kitchen grinders and the secondary wastewater treatment systems that allow them to turn their waste into energy. But New York City has remained reluctant, even though kitchen grinders have been legal here for almost 20 years. Industry experts say the city’s resistance on kitchen grinders is a combination of old myths about the dangers of disposals and an over-reliance on hauling, where garbage is picked up in a truck and sent to outer boroughs or other states for processing and, often, burial in a landfill.
As far as most New Yorkers are concerned, when they flush, their waste disappears. But the work is only just beginning for those on the receiving end.
A growing portion of the city’s wastewater pours into the eight gleaming silver digesters at the futuristic Newtown Creek wastewater and biogas facility in Green Point, Brooklyn, the largest of the city’s 14 water treatment plants. Organic matter, mostly human feces, is separated from the water it flowed in with. The water is then cleaned and sanitized so it can be released into rivers and streams.
But much of the poop is sent to the egg-like digesters. There, the organic waste is heated to encourage microbial activity and deprived of oxygen for days. Eventually, most of the feces and food waste turn into gas, including carbon dioxide and methane. These biogases are then burned to power the plant, with any leftover energy sold back into the electrical grid to power nearby homes and businesses. The remaining sludge, now odorless and largely free of pathogens, is dried and used as fertilizer. But the super-eggs at Newtown Creek, parts of which first began running in 2008, can handle a lot more than poop.
The eggs can also take in food waste, like Dany Nelson’s bananas, if the leftovers are properly pulverized by a kitchen grinder. And those leftovers can be turned into power.
But resistance remains, mainly from landlords who continue to believe old myths about the potential for clogged pipes, says Terence O’Brien of the Plumbing Foundation, a non-profit that advocates for the interests of the city’s plumbers. Plumbers are quite certain that grinders don’t cause a problem, he says. In fact, many new apartment complexes have installed grinders — listing them as luxury amenities along with in-building gyms and outdoor patios. But most New Yorkers still live in older buildings where grinders don’t exist and are actively discouraged. Even in co-ops and condos, where the units are owned by the tenant, many residents are not allowed to install kitchen grinders without board approval, as the ownership of the plumbing system is said to be shared among all residents, O’Brien says.
The only cooking byproducts that really cause problems in plumbing are oil, fat and grease, says Lauren Fillmore of the Water Environment Research Foundation, a non-profit organization that studies wastewater and its many uses. While it’s true New York City experiences an “epidemic of oil-clogged pipes” — or two — each year, she says these greasy nightmares aren’t the fault of garbage disposals at all. Rather, urban arteries are clogged when restaurants drain grease in a conventional sink (restaurant owners are actually barred from having sinks equipped with garbage disposals altogether) instead of bottling used oil and throwing it in the garbage.
It may seem strange that garbage disposals remain illegal in New York City restaurants — but they were only legalized in private homes quite recently. Developed in the 1920s, kitchen grinders were banned in New York City for almost 60 years due to a variety of concerns about their effect on sewage. (Though, as Joan Didion wrote in The New York Review of Books in 1991, there were more interesting fears at play, too, including those of a New York City employee who worried adopting disposers would encourage people to “put their babies down them.”)
The anti-disposal law finally changed in 1997, when the City Council legalized the grinders for non-commercial use, but many people’s attitudes have remained the same. This resistance to change is evident in the paltry uptake of the bladed device. Back in the 1990s, Christiansen says, the city anticipated they could handle a one percent uptick in the number of homes with grinders each year, or about 30,000 grinders annually. Though the city does not track the actual number of installations, experts including Christiansen estimate that fewer than 10,000 units are actually installed each year.
Fillmore thinks this may come from the way the city has historically sent its waste far and wide for processing. “New York… has a very unique way of managing solid waste,” she says. “They have a lot of contracts with these waste haulers who are private haulers.” But wastewater can’t be “hauled” anywhere, while solid food waste can be trucked to a landfill or to a composting facility. Moving to a kitchen grinder-based system could disrupt the whole of the New York City waste management industry, which runs up $400 million in annual disposal costs for residents and non-profits alone. It could also mean many haulers would lose out.
Turning everything into a slurry would also make it difficult for the city to measure the amount of waste it’s diverting. When food waste is composted, it’s weighed in the truck and counted toward the city’s zero waste goal. But when it’s pulped, it all but disappears. This may seem trivial to an average citizen, but for the city, it matters. The ability to measure its diversion impacts its budget, marketing and reputation with other branches of government.
Paul Kohl, who manages Philadelphia’s wastewater treatment agency, says his city’s success with garbage disposals is bolstered by its administrative design. In New York City, food waste is under the purview of the Department of Sanitation, whereas wastewater is a job for the entirely separate Department of Environmental Protection. But because 40 percent of Philadelphia residents grind their food, Kohl’s single agency must play a role in managing both food waste and wastewater.
A big push for kitchen grinders in New York City, Kohl says, would require that the Department of Sanitation take some control from Environmental Protection, or vice versa. It would also mean that someone would get stuck with a big bill. If Environmental Protection took over food waste, for example, it would have to assume the cost of processing it and would likely struggle to convince the mayor to shift funds from one agency to the other.
What’s more, Pam Elardo, head of New York City’s bureau of wastewater, has said she’s uncertain that the city’s biodigesters, in their current incarnation, could handle the amount of food waste that would inevitably pour in should locals wholeheartedly embrace in-sink disposal. Elardo’s wastewater department is currently testing this potential but hasn’t released its final assessment.
Still, the success of other cities suggests there’s a path forward for New York City, one laden with both wastewater slurry and rich composted soil. Kohl says what made the difference for Philadelphia was the realization that it’s not really a matter of choosing one solution over another. Rather, it’s about integrating both wastewater and composting as seamlessly as possible to combat food waste. “I am pro-disposer, but I am not opposed to composting,” Kohl says. “There’s plenty of food to go around.”