The Treatment - The Ripple Effect: The Fate of Freshwater in the Twenty-First Century - page 44

Long Island Sound and forced the closing of most city beaches. The lack of functioning
generators and the discharge of sewage violated both federal and state laws. To avoid
prosecution, the city had to admit it erred and was put under court supervision. City
officials said that workers had repeatedly tried to have the generators repaired, but the
job was never accomplished.
New Yorkers questioned whether they had been unfairly singled out, noting that
a plant in Cleveland discharged at least 60 million gallons of raw sewage into the
Cuyahoga River, Lake Erie, and other waterways during the blackout, while in Detroit,
citizens were advised to boil their water after the city's sewer plants lost power. Neither
of those cities faced prosecution. (Regulators ignored the protest.)
New York's sewer system is designed to accommodate a so-called five-year storm—a
rainstorm so severe that it is predicted to fall only twice a decade. But lately weather
patterns have been shifting. In 2007 alone, the city experienced three intense twenty-
five-year rainstorms—storms so extreme they are predicted to occur only four times per
century—which flooded subways and highways and threatened to shut down the city.
At a time when national attention was beginning to focus on the long-term effects
of climate change—greater heat, more frequent and intense hurricanes, rising
seas—sewage experts viewed the storms of 2007 as a wake-up call.
THE SECRETS OF SEWAGE
Sewagetreatmentis the generic term for the removal of contaminants from runoff and
domestic wastewater via chemical, biological, and physical processes. The result is a
waste stream of treated effluent and solid waste, or sludge,which is often filled with con-
taminants and toxic compounds of an almost unimaginable variety. The main objective
of sewage treatment is to clean water to the point that it can be discharged back into the
environment. Americans produce about 18 million tons of feces a year , and treatment
plants process about 34 billion gallons of wastewater per day, according to the EPA.
Treatment in sewage plants mimics natural cleansing processes: typically, bacteria
consume organic contaminants, and sunlight helps break down pollutants; when
wastewater is mixed with large volumes of freshwater, it is diluted. Similarly, most pol-
lution control plants in the United States use three stages of treatment: primary (sewage
is held in tanks, where heavy solids settle to the bottom while lighter solids and oil float
to the surface and are removed), secondary (the removal of dissolved or suspended bio-
logical matter, a job often performed by microorganisms), and tertiary (the disinfection
of treated water by chemicals such as chlorine by ultraviolet light, or by microfiltration).
By the end of this “treatment train,” water is usually clean enough to be discharged back