Science of Water : Concepts and Applications

Water Treatment 291
Dr. Snow, the obstetrician, became the fi rst effective practitioner of scientifi c epidemiology. His
creative use of logic, common sense, and scientifi c information enabled him to solve a major medical
mystery—to discern the means by which cholera was transmitted.
PUMP HANDLE REMOVAL—TO WATER TREATMENT (DISINFECTION)
Dr. John Snow’s major contribution to the medical profession, to society, and to humanity, in general,
can be summarized rather succinctly: He determined and proved that the deadly disease cholera is
a waterborne disease. (Dr. John Snow’s second medical accomplishment was that he was the fi rst
person to administer anesthesia during childbirth.)
What does all of this have to do with water treatment (disinfection)? Actually, Dr. Snow’s
discovery—his stripping of a mystery to its barest bones—has quite a lot to do with water treatment.
Combating any disease is rather diffi cult without a determination on how the disease is transmitted—
how it travels from vector or carrier to receiver. Dr. Snow established this connection, and from his
work, and the work of others, progress was made in understanding and combating many different
waterborne diseases.
Today, sanitation problems in developed countries (those with the luxury of adequate fi nancial
and technical resources) deal more with the consequences that arise from inadequate commercial
food preparation, and the results of bacteria becoming resistant to disinfection techniques and
antibiotics. We simply fl ush our toilets to rid ourselves of unwanted wastes, and turn on our taps to
take in high-quality drinking water supplies, from which we have all but eliminated cholera and
epidemic diarrheal diseases. This is generally the case in most developed countries today—but it
certainly wasn’t true in Dr. Snow’s time.
The progress in water treatment from that notable day in 1854 (when Snow made the “connection”
[actually the “disconnection” of handle from pump] between deadly cholera and its means
of transmission) to the present reads like a chronology of discovery leading to our modern water
treatment practices. This makes sense, of course, because with the passage of time, pivotal events
and discoveries occur—events that have a profound effect on how we live today. Let us take a look
at a few elements of the important chronological progression that evolved from the simple removal
of a pump handle to the advanced water treatment (disinfection) methods we employ today to treat
our water supplies.
After Snow’s discovery (that cholera is a waterborne disease emanating primarily from human
waste), events began to drive the water/wastewater treatment process. In 1859, 4 years after Snow’s
discovery, the British Parliament was suspended during the summer because the stench coming
from the Thames was unbearable. According to one account, the river began to “seethe and ferment
under a burning sun.” As was the case in many cities at this time, storm sewers carried a combination
of storm water, sewage, street debris, and other wastes to the nearest body of water. In the
1890s, Hamburg, Germany suffered a cholera epidemic. Detailed studies by Koch tied the outbreak
to the contaminated water supply. In response to the epidemic, Hamburg was among the fi rst cities
to use chlorine as part of a wastewater treatment regimen. About the same time, the town of
Brewster, New York became the fi rst U.S. city to disinfect its treated wastewater. Chlorination of
drinking water was used on a temporary basis in 1896, and its fi rst known continuous use for water
supply disinfection occurred in Lincoln, England and Chicago in 1905. Jersey City, New Jersey
became one of the fi rst routine users of chlorine in 1908.
Time marched on, and with it came an increased realization of the need to treat and disinfect
both water supplies and wastewater. Between 1910 and 1915, technological improvements in
gaseous and then solution feed of chlorine made the process more practical and effi cient. Disinfection
of water supplies and chlorination of treated wastewater for odor control increased over
the next several decades. In the United States, disinfection, in one form or another, is now being
used by more than 15,000 out of approximately 16,000 publicly owned treatment works (POTWs).