Environmental Engineering Reference
In-Depth Information
borne transmission of disease inspired Dr.William Budd's studies of typhoid
fever. Like Snow, Budd determined that typhoid was spread through water
supplies contaminated with human feces. 44 Of the possible water-borne
diseases that threatened American cities, typhoid fever was the worst. “The
disease means little to us today since it is no longer a threat to modern
cities,” stated the historian Michael P. McCarthy, “but it frightened the
urbanizing world of the late nineteenth century.” 45
The typhoid bacillus could be contracted by direct contact with a “car-
rier” or through contaminated food such as milk, raw fruits and vegetables
fertilzed with night soil, and shellfish found in polluted waters. Most
often it was spread when excreta from a victim entered the water supply
directly or as untreated sewage. Detecting the disease posed something of
a problem because the incubation period was approximately 14 days.
Typhoid fever produced vomiting and diarrhea leading to dehydration, and
was accompanied by high fevers. Children, in particular, were most sus-
ceptible to the disease. 46 Not only was the disease a threat to human life, but
it could severely damage the reputation of a city trying to attract new citi-
zens and new business enterprise. 47 It was a scourge to be avoided if at all
possible.
By the turn of the century, various approaches to ensuring a pure water
supply and limiting water-borne disease emerged from the bacteriological
and chemical laboratories supported by agencies such as the Massachusetts
Board of Health. But the first means of water purification readily available
to cities in the late nineteenth century—one that fit within the context of
the filth theory—was filtration through sand or gravel to improve the clar-
ity, odor, and color of the water.
As early as the ninth century, Venetians filtered water from cisterns
through beds of sand.The first filtering system for a public water supply, as
stated earlier, was likely established in Paisley, Scotland in 1804.The Chelsea
Water Works in London (1827) employed a “slow sand” (or English) filter,
which was the archetype for later models and which eventually found its
way to the United States. Berlin's water was filtered in 1856, and by 1865
several European cities followed its example. 48
In 1835, a noted American engineer, Samuel Storrow, was the first to rec-
ommend the use of filtration in the United States. “If the supply be origi-
nally taken from a river,” Storrow wrote in his topic on water works,“it will
be liable at some seasons of the year to be very much loaded with impuri-
ties, and it is important to have, in connection with the reservoirs, filtering
Search WWH ::




Custom Search