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Contaminated WasteWater

Published by the
Detroit Water and Sewerage Department

SUMMER 2011 / Vol. 10, No. 7

Inside the home of the Detroit Water and Sewerage
Department’s (DWSD) Industrial Waste Control Division
(IWCD), located in a nondescript brick building at 303 S.
Livernois in southwest Detroit, some of the most interesting —
and important — work of DWSD is performed. There, samples
of potentially hazardous or toxic wastewater from manufacturing
facilities are analyzed.
Industrial Waste Control is the agency responsible for making
sure that city and federal regulations pertaining to industrial
wastewater are followed.
Industrial and commercial operations produce huge amounts of
wastewater; wastewater that’s contaminated with toxic pollutants
that can potentially reach the sewer system. In order to prevent
the release of such pollutants into the nation’s drinking water
supply, Congress passed the Federal Water Pollution Control Act
Amendment, commonly known as the Clean Water Act, in 1972.
The act established regulations to control the discharge of
industrial pollutants into public sewer systems.
So how does IWCD come into play? “IWC enforces locally- and
federally-mandated regulatory controls on wastewater discharges
into the public sewer system throughout the service area of
DWSD,” said Yousef Ahmed, Industrial Waste Control Manager,
adding that the service area includes seventy seven cities and
communities in Wayne, Oakland, and Macomb counties.
Ahmed emphasized that waste or wastewater containing
pollutants that are prohibited from entering the sewer system
should be treated by the source facility — the
manufacturing/industrial firm — to remove or reduce the
pollutant concentration. “This is called pretreatment,” said
Ahmed. An acceptable alternative to pretreatment, he added, is
having the industrial waste hauled off site to private treatment
facilities or landfills designated for hazardous materials.
“These kinds of facilities are regulated by the state,” Ahmed said.
“For example, oily waste that’s generated by machining
industries is hauled to private treatment facilities for recycling
waste oil or for treating waste coolant.
Detroit’s Wastewater Treatment Plant (WWTP) receives between
600 and 700 million gallons of wastewater on a daily basis; of
that amount, approximately 40 percent is generated by industrial
or commercial operations, Ahmed said. IWCD ensures that
industrial wastewater meets standards mandated by the
Department’s National Pollutant Discharge Elimination System
(NPDES) permit. The permit is issued to DWSD by the
Michigan Department for Environmental Quality (MDEQ) for
discharging treated wastewater from the WWTP into the Detroit
and Rouge rivers. IWCD, in turn, issues special permits to
companies or facilities that generate industrial waste.
The WWTP employs both physical and chemical treatment
systems (for example, screening, settling, chemical
precipitation, biological treatment by bacterial decomposition,
and chlorination). Treated wastewater is discharged into the
river and recovered sludge is dewatered, incinerated and land
filled or land applied.

Materials commonly found in industrial or commercial waste include:
Metals, such as arsenic, cadmium, chromium, copper, iron, lead, nickel,
zinc, silver, and mercury.
Toxic pollutants like cyanide, PCB (polychlorinated bi-phenol), and
other phenolic substances.
Conventional pollutants, such as fat, oil, grease (commonly grouped
together as “FOG”), suspended solids, phosphorus, and a variety of
volatile and semi-volatile organic pollutants.
Detroit and 76 suburban customer communities send wastewater to the WWTP
through a network of thousands of miles of sewers. But is there a higher fee for
treating wastewater from heavy industry?
“No higher fee is charged for treating industrial wastewater; however, if the
concentration of certain conventional pollutants exceeds certain limits, we collect
an additional surcharge from the company that is discharging into the system,”
Ahmed said.
“Fat, oil and grease discharged by food service establishments have now become
a significant problem for the Wastewater Treatment Plant and the sewer system,”
Ahmed noted. “To address the problem, we’ve begun a community outreach
initiative to educate and motivate food service establishments to adopt grease
management programs. Industrial Waste Control Division staff members visit
food handling facilities to discuss techniques to prevent the release of grease into
the sewers,” added Ahmed.
In general, industrial waste is generated by industrial operations and manufacturing
processes, and may contain hazardous or toxic pollutants. It’s defined as “any
liquid, solid, or gaseous waste or form of energy, or combination thereof, resulting
from any processes of industry, manufacturing, business, trade or research,
including the development, recovery or processing of natural resources.”
Ahmed said that, in contrast, commercial waste is “generated by business
enterprises and does not involve chemical, physical and/or biological processes
that contain pollutants of concern.” Pollutants in commercial waste can be
removed by conventional treatment, so commercial waste is generally sent directly
to the Wastewater Treatment Plant. Domestic waste is classified as waste and
wastewater from humans or household operations. It is also sent to the WWTP
without pre-treatment.
“If wastewater discharged into the sewer system from any industrial or commercial
operations contains certain pollutants, such as metals, cyanide, PCB, or any other
toxic or hazardous material, a wastewater discharge permit is required from
IWCD,” said Ahmed. Again, such wastewater is pre-treated before entering the
sewer system or WWTP. IWCD also requires industrial facilities to prepare and
implement spill prevention plans.
“In addition to wastewater, industrial operations generate quantities of solid,
semisolid, gaseous waste, which are prohibited from being discharged into the
sewer system,” Ahmed said. Handling and disposal of those types of waste is
regulated by federal and state agencies, he added.
IWCD doesn’t only regulate the discharge of industrial wastewater; certain
volumes of other kinds of wastewater can exceed regulated threshold limits and
require a permit from IWCD. “For example, groundwater generated from
excavation work requires a wastewater discharge permit,” said Ahmed.

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