Page 81 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

36 Fundamentals of Water Treatment Unit Processes: Physical, Chemical, and Biological

matter that finds its way into ambient waters after rainfall, and
of the decay of organic matter within a water body.
activated carbon and filtration), 83.9 mg=L; and (6)
NOM causes the water to exhibit ‘‘color,’’ measured in
finished water after a final chlorination, 94.0 mg=L.
terms of ‘‘standard color units’’ (SCU). Color, per se, has no
In early 1974, the EPA drinking water group pondered
health significance, but it does cause concern as it affects
what to do about Bellar’s findings. Since the oral lethal
palatability of a drinking water. Since there is no health
dose was 120 mg=L, the issue seemed not an acute prob-
significance to color, it was assigned the status of a ‘‘second-
lem. In June 1974, however, an article in Consumer
ary standard’’ in the 1973 Safe Drinking Water Act
Reports reviewed the problem of organics in drinking
(PL93-523). Color has been considered as a parameter of
water. The article was based partly on a 1972 report by
drinking water quality since about the 1920s, and its reduction
USEPA and was to have strong influence on future events.
has been a traditional objective of water treatment (achieved
The article was an indictment of the water quality of the
by coagulation, and as measured by the ‘‘jar’’ test).
Lower Mississippi River and stimulated public interest in
In the early 1970s, chlorinated organics were identified as
the problem of organics in drinking water. James Symons
carcinogens (Box 2.A.2) based on reports of higher levels of
returned to Europe in August 1974, and Rook described
THMs in New Orleans drinking water, which precipitated
his theorythatNOM,asmeasuredbycolor, was a precur-
the 1974 Safe Drinking Water Act (SDWA)—the first
sor to THM formation; his data showed a correlation
between TTHM in mg=L and color in Pt–Co units, and
other possible precursors were eliminated by experiment
BOX 2.A.2 DISINFECTION BY-PRODUCTS
and deduction. At that time, the structure of humic
AS A NATIONAL ISSUE
substances were not well defined. This meeting with
A review of how disinfection by-products (DBPs) Rook, and his evidence that color was a likely precursor
became a national issue was reviewed by James M. to THMs, had a strong influence on Symons relative to the
Symons (2001a,b), who, in the1970s, was Chief of the possible extent of the problem of THM’s in drinking
Physical and Chemical Contaminants Removal Branch, water. Further stops in Europe, e.g., at the Swiss Federal
Drinking Water Research Division, USEPA, Cincinnati. Institute of Technology and at Karlsruhe, led to the deci-
This position provided the vantage point of both per- sion at EPA that the THM issue was indeed important.
spective and responsibility to provide initiative. Then, the National Organics Reconnaissance Survey was
Johannes Rook, a chemist with the Rotterdam Water started to ascertain how widespread the problem of
Works, discovered chloroform in Rotterdam’sdrinking THMs was in the United States. Following this, in
water in 1971 while looking for sources of taste and November 1974, the Environmental Defense Fund
odor, based on a ‘‘head-space’’ sampling=analysis tech- released an epidemiological study showing that disease
nique he developed. Although he took special note of the rates for persons drinking New Orleans water were higher
chloroform as one among a score of micropollutants, than those persons living in surrounding communities and
there was not any special alarm, especially since the drinking water from sources other than the Mississippi
health officer mentioned that chloroform was a constitu- River. At the same time, a medical faculty member at the
ent of cough syrup and was not know as a toxin. University of New Orleans stated that he had found halo-
Also in 1971, Thomas Bellar, a chemist with EPA, was gen-substituted organic compounds in the blood of New
given an assignment to develop an adequate method to Orleans residents. He also stated on national television
measure VOC contaminants in wastewater. The method that the water quality (i.e., with respect to chloroform)
developed was called by Bellar the ‘‘purge and trap’’ from the Mississippi River was of considerably better
technique, which was an adjunct to gas chromatography. quality than the water produced by the water treatment
This was an analytical ‘‘breakthrough,’’ which opened the plant. In December 1974, with an atmosphere that caused
door for detecting and measuring organic contaminants at a lessening of public confidence in the drinking water
the mg=L level. In measuring contaminants in samples of industry, the Safe Drinking Water Act (PL93-523) was
tap water, Bellar found chloroform but attributed the signed by President Ford.
finding to laboratory contamination. In mid-1973, con- The national publicity led to pointed criticisms of the
tinuing to find chloroform, he decided to sample other drinking water industry. Further, many in the industry
drinking water sources. In sampling at several points in could not believe that the trace concentrations of chem-
the water treatment train for the City of Cincinnati, he icals could be hazardous to public health. (As an edi-
found that DBPs were related to the points of chlorination. torial aside, the THM issue and the later Giardia issue,
For example, chloroform concentrations were (1) Ohio which emerged in 1978, were combined stimuli that
River, 0.9 mg=L; (2) 80 min after chlorination and alum caused a major change in the culture of the U.S. water
coagulation, 22.1 mg=L; (3) 3 day settled water, 60.8 industry. The drinking water industry became energized
mg=L; (4) treatment plant settled water following chlorin- and perhaps one might say the ‘‘glamour’’ field, which,
ation, 127 mg=L; (5) filter effluent (after powdered during the 1960s, was in wastewater treatment.)