The nation’s largest wastewater system is seeking an answer to a nauseating question: What do we do with the half-million tons of human excrement and solid waste that pours into the city’s sewers every year?
New York City’s Department of Environment Protection on Wednesday put out a notice requesting ideas on how to divert all the excrement that goes down drains from ending up in landfills. The city aims to stop putting any of that waste into landfills by 2030, and wants to make the entire process emissions-free by 2050.
It’s a big job.
The DEP reports the city’s wastewater treatment plants process 480,000 “wet tons” of waste annually, which is more than twice the weight of the Chrysler Building. The ultimate goal is to create a program that gives a sustainable second life to every ounce of excrement and food that goes down drains across the five boroughs.
But first, the city wants more information about who can take the stuff and potentially put it to good use.
“The information gathered will be used to identify regional partners that demonstrate the capability to receive and process New York City’s biosolids for beneficial reuse strategies that align with DEP’s climate and policy goals,” the agency writes.
The notice provides a step-by-step rundown of how more than a billion gallons of wastewater and storm water get treated in the city every day.
Solids from that sewage is “thickened” and “stabilized” in a process meant to reduce odors and bacteria. That produces “nutrient rich digestate,” which is then transported to one of six “dewatering facilities” in the city, or a facility in Newark, N.J. The gunk is put into centrifuges that further separate liquids and solids. All told, the city produces “1,300 wet tons of dewatered solids per day on average,” according to the notice.
Currently, nearly half of the sewer sludge is treated and reused for fertilizer for agricultural purposes, according to the city data. But remaining material is taken to landfills, mostly by diesel trucks and trains.
Carrying all that waste takes an environmental toll. The daily trucking haul to the Seneca Meadows landfill, which is about 300 miles upstate, can put roughly 35 tons of carbon dioxide into the atmosphere, according to a data tool from the Environmental Defense Fund.
The DEP wants to reuse as much of that waste as possible to help meet the city’s climate goals. Diversion from landfills reduces methane, a greenhouse gas that’s 80 times more potent than carbon dioxide.
According to the DEP’s annual emissions inventory report, the agency reduced its carbon emissions produced by wastewater treatment operations by 40% from 2006 to 2022.
The city has previously proposed other steps to divert organic waste from landfills, including converting much of it — including compost — into “biogas,” which is also referred to as renewable natural gas. But that isn’t the most sustainable solution either, as that gas produces a similar amount of carbon pollution as standard natural gas.
According to the EPA, the most effective method of dealing with waste is “to generate less in the first place.” But that may be difficult when it comes to reducing what New Yorkers flush down their toilets.
The DEP set a deadline of May 15 for experts and partners to submit their strategies to address the issue.