Page 70 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

Water Contaminants 25

measurements into and out of a wastewater treatment plant has first direct involvement of the federal government in drinking
been a traditional measure of performance. Also, BOD is an water standards—a dramatic break with the past, which was to
index of the impact on the oxygen resources of the ambient change the U.S. water industry.
receiving water. One factor in favor of adopting such a surrogate The passage of the Act was precipitated by an Environ-
is that its use has been institutionalized (e.g., standards have mental Protection Agency (EPA) report of trihalomethanes
been established, its laboratory protocol is well known, results of (THMs) in New Orleans drinking water and their link to the
monitoring are available for most plants, its interpretation in higher incidence of cancer. The 1986 amendments resulted in
terms of plant performance or of water quality is clear). another major change, i.e., that 83 substances were listed as
Table 2.2 lists examples of surrogates used in water treat- drinking water contaminants, with the provision that 25 con-
ment (both wastewater and potable water). Those that have taminants were to be added every 3 years. The new ethic of
emerged since about 1980 include TOC, TTHMFP, UV 254 , drinking water treatment was articulated by Abel Wolman in a
MPA, and online particle counts. Some surrogates have a luncheon speech at the 1985 annual conference of the Ameri-
history, e.g., TOC became instrumentally feasible in 1965 can Water Works Association with the phrase, ‘‘if in doubt,
through instrumentation developed by Beckman Instruments, take it out.’’ This phrase, coined by the icon in the field,
Inc., which converted organic carbon to carbon dioxide gas, encapsulated a paradigm shift toward articulated objectives
which then was measured by infrared absorbance. A host of in water treatment that had been occurring since the passage
other surrogates could be added. A laundry list, not inclusive, of the Safe Drinking Water Act. This shift was similar in
might include TDS (total dissolved solids), EC (specific character to the shift in water pollution control from the idea
electrical conductivity), hardness as CaCO 3 , alkalinity as of ‘‘assimilative capacity’’ toward the goal of ‘‘zero’’ pollutant
CaCO 3 , TKN (total Keldahl nitrogen), MLVSS (mixed liquor discharge (Box 2.2).
volatile suspended solids), etc.

2.2 FEDERAL LAWS
BOX 2.2 FEDERAL LAWS ON WATER
The formal break with the past for the United States with respect
POLLUTION CONTROL
to pollution control was in 1965. In 1962, Rachel Carson’sbook
Silent Spring (Carson, 1962) precipitated the environmental According to Dworsky (1967), water pollution was a
movement that articulated public concerns about the environ- major public concern to the nation’s 75 million people at
ment and spawned a host of laws through the 1970s. The the beginning of the twentieth century. Congress in
Environmental Movement, although historic in itself, was actu- 1912, however, made the decision to limit its interest
ally a part of a continuum of political events from the Public to research and technical assistance and to leave to the
Heath Movement initiated in the early nineteenth century in states the major role in controlling pollution. After the
England and the Conservation Movement of Gifford Pinchot World War II, Congress passed the Water Pollution
and Theodore Roosevelt in the early twentieth century. Control Act of 1948, PL80-845. The Act included finan-
For engineers, the Environmental Movement resulted in a cial and technical aid and provision for research and
basic shift in objectives for the design of wastewater treatment planning. The Act was amended in 1952, 1956, 1961,
plants. From about 1920 when wastewater treatment was 1965, and 1966. The 1956 amendment added a phrase,
underway, most statements of ambient water quality standards ‘‘to establish a national policy for the prevention, con-
were merely to eliminate sludge banks in streams, to prohibit trol, and abatement of water pollution.’’ The 1965 Act
floatables, and to maintain slightly aerobic conditions, i.e., provided for the establishment of water quality stand-
2mg=L dissolved oxygen concentration. The idea was to ards for interstate streams and other water bodies, giving
utilize the ‘‘assimilative capacity’’ of a given water body. the states the responsibility, but federal action could be
The main pollutants were BOD and suspended solids (SS). taken in the face of state inaction. The 1972 amend-
The new ethic, however, as suggested by the 1965 ments established the requirement for effluent standards
law and made explicit by the 1972 law, called the Clean and the National Pollution Discharge Elimination
Water Act, was to eliminate the discharge of pollu- System (NPDES) permit. In 1970, the Environmental
tants. In addition to the traditional pollutants, nutrients, Protection Agency (EPA) was established by President
i.e., phosphates and nitrates, became a concern along with Nixon to administer the environmental laws (with some
toxic pollutants. The alga blooms of Lake Erie symbolized exceptions). The Safe Drinking Water Act was enacted
the nutrient problem, and the term eutrophication,which in 1974 by PL93-523 and has had a similar sequence of
means nutrient-rich, became a household word. In addition, strengthening amendments.
the 1972 law required a NPDES permit to discharge pollu- The federal legislation culminated in the form of the
tants. The result was a fundamental transformation in the Comprehensive Environmental Response, Compensa-
modus operandi in design objectives for engineers and in tion, and Liability Act (Superfund) and was enacted in
the regulation of pollutants. 1980 by PL96-510, spawning an industry on cleanup of
In the field of drinking water, the U.S. Congress passed the hazardous waste sites.
Safe Drinking Water Act, PL93-523, in 1974. This was the