Ecotourism: In search of the Digester Eggs of Greenpoint


digester eggs

Visually striking, eight digester eggs loom over the Newtown Creek Wastewater Treatment Plant (Photo by NYC Department of Environmental Conservation)

By Len Maniace

Ecotourism usually conjures visions of rain forests and exotic fauna in Costa Rica and other distant locales. On Saturday I journeyed to Greenpoint, Brooklyn. Well, at least my subway trip produced less climate-changing carbon dioxide than a flight to Central America.

My destination was the site of eight gleaming stainless steel structures known as Digester Eggs, which dominate the Newtown Creek Wastewater Treatment Plant there. On most days, 340 million gallons of sewage are transmuted into clean… well let’s just say, cleaner water.

Sewage – that’s the liquid that comes intermittently from your kitchen sink and toilet. In a city of 8.3 million people, however, those intermittent flushes quickly join up to become swift-moving streams and eventually mighty rivers of sewage.

Where the flush goes

One-third of Manhattan’s sewage travels under the East River, one-fifth of Brooklyn’s sewage flows north, and one-seventh of Queens’ sewage flows south, all into the Newtown Creek Wastewater Treatment Plant, the largest of the city’s 14 such facilities.

digesters in a row

Each Digester Egg contains 3 million gallons of sewage sludge that is digested buy bacteria. (Photo by Len Maniace)

“And we are happy to receive it here,” Ali Zainool, the plant’s manager, told the audience at an 11 a.m. tour, the first of three that day. It’s an annual event known as the Valentine’s Day Digester Egg Tour, even though it came eight days early.

One has to admire the confidence of New York Department of Environmental Protection officials for picking a holiday dedicated to romance and risking jokes about perfume on tours at facility where olfactory is not necessarily the sense one wants to focus on. For the record, neither I nor other visitors I spoke to, noticed any unpleasant odors.

Standing in a plant’s visitors center classroom, the hum of giant compressors in the background, Zainool explained the operation: wastewater entering the plant first meets up with giants screens that filter out branches, toilet paper and other debris; then said sewage is digested by hungry bacteria, before it is treated with chlorine, and piped to the East River, a reasonable facsimile of water that’s clean enough to meet federal and state pollution codes.

If only that were the entire story, however. When skies over New York open, raining down on roofs, roads and parking lots, water rushes into the city’s 148,000 catch basins, racing down 7,400 miles of sewer lines toward sewage treatment plants, Zainool explained.

Wastewater treatment plants are built to handle some of this added storm water flow – an extra capacity equal to each plant’s usual flow. Larger rains, however, quickly overwhelm this added capacity. The overload is then shunted from underground sewer mains into the city’s waterways, releasing huge volumes of untreated sewage.

This is New York City biggest challenge when it comes to keeping its surrounding waterways clean. Newer cities and suburbs have solved this problem by building separate wastewater and storm water systems. New York City, however, is now looking for ways to keep much of the storm water out of treatment plants, or at least delaying it’s arrival.

Gray versus green

One method is the construction of huge underground tanks that temporarily hold this mix of rainwater and sewage, a project that comes under the heading of gray infrastructure. The other method is green infrastructure, working with nature to prevent runoff from ever reaching city sewers.
mapThese include green roofs, rain gardens and permeable pavement that allows rain and melting snow to penetrate sidewalks and parking lots into soil. Another tool is beginning to transform the streetscape in parts of the city, bioswales. They are street-side gardens surrounding trees that can divert up to 2,000 gallons of water from curbs into soil. Green infrastructure is an exciting innovation, but it’s a tale for another day.

There’s no missing the Digester Eggs at the Newtown Creek Wastewater Treatment Plant. They are 140 feet tall and connected at the top by enclosed glass walkways which not only enable workers to oversee the operations, but they also provide spectacular 360-degree views of the city.

Standing in a walkway atop one digester egg, deputy plant manager Kevin McCormick explained that engineering, not aesthetics, was behind the eggs’ design. The shape is ideal for mixing the digester’s contents, helping bacteria to break down the sewage.  The design is so efficient each Digester Egg needs only one 50-horsepower motor to churn 3 million gallons of sludge, resulting in a significant energy savings, McCormick said.

In an egg and the human gut

The breakdown of sewage by bacteria is a biological process similar to how food is digested in our intestines by bacteria. And as happens in the human process, this one also produces natural gas, or methane. But rather than allowing methane, a powerful greenhouse gas, to escape into the atmosphere, McCormick said the city uses the methane to heat the sludge to 98 degrees, the temperature at which the bacteria are most active, and also to heat water that’s occasionally added to the process, thereby saving energy and money.

The city has even bigger plans for tapping methane at the plant – a composting program that would breakdown food scraps much the way backyard compost piles work. A test project that composts scraps from a New York City elementary school is now underway at the site. If successful, the city would collect scraps from many more school cafeterias and then sell the methane to a local supplier.

Creek Vista

Newtown Creek Nature Walk was created as part of the modernization of the Newtown Creek Wastewater Treatment Plant. (Photo by Len Maniace)

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About lenmaniace

Award-winning writer and editor who has worked as a journalist and a corporate communications professional specializing in environmental sustainability and public health policy. Experience includes successful media outreach for a Manhattan publicity firm. Board member and president of a community-based nonprofit. Founder and leader of a series of successful park, art and environmental programs in Jackson Heights, Queens, one of the most diverse neighborhoods in the nation’s most diverse city. * Executive Editor at Elsevier, a leading scientific and medical publisher. * Publicist, Media Advisor, Social Media Manager (part-time) at Monteiro & Co., a book-marketing company that specializes in business management, economics and politics. * Reporter (part-time) at the New York Post, specializing in breaking news in the world’s most competitive media market. * Senior Writer and Editor at The Journal News/, Gannett’s daily news outlet in Westchester, Rockland and Putnam counties. Specialized in health policy and environmental sustainability issues * President the Jackson Heights Beautification Group, a volunteer nonprofit civic organization in Queens, N.Y. Leader of its innovative environmental sustainability programs, including the Green Agenda for Jackson Heights.
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5 Responses to Ecotourism: In search of the Digester Eggs of Greenpoint

  1. Barbara Mutnick says:

    Just wonderful, Len. Informatice, interesting. You are a terrific writer. Barbara

  2. alfredo says:

    thank you len: good news re: environment is rare..ur article shows otherwise….

  3. Tom Lowenhaupt says:

    For those who might want the creak view, the North Brooklyn Boat Club is the way to go. Very friendly folks. I was a member for a year of so. Kayaks and canoes trips down the Newtown Creek can be arranged.

  4. Pingback: Flushing: A bay by any name would smell as foul | Planet NYC

  5. Valeri Larko says:

    Great article Len! I did a couple of paintings of those Digester Eggs.

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