The Treatment - The Ripple Effect: The Fate of Freshwater in the Twenty-First Century - page 46

is piped into the plant, passes through screens into grit chambers (these remove silt,
gravel, coffee grounds, and eggshells, which cause wear and tear on pumps), then on to
aeration (where microbes eat the “solids,” aka feces), and settling tanks (where fine air
bubbles mix the microorganisms, causing the oxidation of organic matter); finally, the
effluent is disinfected with sodium chloride and discharged.
The Newtown plant releases its effluent into a twelve-foot-wide, forty-eight-
hundred-foot-long outflow pipe that drops steeply underground and emerges under the
shipping channel in the East River. Out there, the current is fast; the treated sewage ef-
fluent passes through diffusers to spread the muck out, so no visible boils or slicks oc-
cur on the surface. The Hudson River and East River flow into New York Harbor, which
opens up to the Atlantic Ocean.
In the meantime, sludge (organic material) is skimmed away from the effluent and
“digested” inside the plant's giant eggs. Inside the digesters, bacteria, heat, and a lack of
oxygen break down the sludge; after fifteen days, what remains is water, carbon diox-
ide, methane gas (which is burned off), and digested sludge. The eggs' oval shape helps
to concentrate grit at the bottom of the tank, aids in mixing the sludge for improved
“digestion,” and helps to concentrate methane gas at the top of the tank. By using this
process, which avoids the traditional primary settling tanks, the city figures it will save
taxpayers about $2.5 billion.
Effluent from sewage plants is a big contributor of nitrogen to New York's waters, as is
the case with treatment plants across the country. A heavy nitrogen load leads to hyp-
oxia—a lack of dissolved oxygen—the death of fish, and the growth of algae. Nitrogen
is a growing threat to major bodies of water, such as Chesapeake Bay and the Gulf of
Mexico, and the EPA has placed New York under a nitrogen-reduction order.
The four wastewater treatment plants that sit along the East River, including the one
on Newtown Creek, discharge 482 million gallons of treated water into the river every
day; this water is 85 percent clean and accounts for about 50 percent of the nitrogen
load in Long Island Sound, according to the DEP.
The Clean Water Act of 1972 was designed in part to improve the nation's sewer con-
trols and protect human and environmental health. Yet, despite $60 billion in upgrades
to sewer systems in the 1970s and 1980s, CSOs continue to pose a major water pollution
concern for 40 million people in thirty-two states .