Environmental Engineering Reference
In-Depth Information
Synthetic organic chemicals (SOCs) —Generally applied to manufactured
chemicals that are not as volatile as volatile organic chemicals.
Included are herbicides, pesticides, and chemicals widely used in
industries.
Total suspended solids (TSS) —Solids present in wastewater.
Trihalomethanes (THMs) —A group of compounds formed when natu-
ral organic compounds from decaying vegetation and soil (such as
humic and fulvic acids) react with chlorine.
Turbidity— A measure of the cloudiness of water caused by the presence
of suspended matter, which shelters harmful microorganisms and
reduces the effectiveness of disinfecting compounds.
Vehicle of disease transmission —Any nonliving object or substance con-
taminated with pathogens.
Wastewater— The spent or used water from individual homes, a com-
munity, a farm, or an industry that contains dissolved or suspended
matter.
Waterborne disease —Water is a potential vehicle of disease transmission,
and waterborne disease is possibly one of the most preventable types
of communicable illness. The application of basic sanitary prin-
ciples and technology has virtually eliminated serious outbreaks
of waterborne diseases in developed countries. The most prevalent
waterborne diseases include typhoid fever , dysentery , cholera , infectious
hepatitis , and gastroenteritis .
Note: Waterborne diseases are also called intestinal diseases , because they
affect the human intestinal tract. If pathogens excreted in the feces of
infected people are inadvertently ingested by others (in contaminated
water, for example), the cycle of disease can continue, possibly in epidemic
proportions. Symptoms of intestinal disease include diarrhea, vomiting,
nausea, and fever. Intestinal diseases can incapacitate large numbers
of people in an epidemic and sometimes result in the deaths of many
infected individuals. Water contaminated with untreated sewage is gen-
erally the most common cause of this type of disease (Nathanson, 1997).
In practice, “hazard identification in the case of pathogens is complicated
because several outcomes—from asymptomatic infections to death—
are possible, and their outcomes depend upon the complex integration
between the agent and the host. This interaction, in turn, depends on
the characteristics of the host as well as the nature of the pathogen. Host
factors, for example, include preexisting immunity, age, nutrition, ability
to mount an immune response, and other nonspecific host factors. Agent
factors include types and strains of the organism as well as its capacity to
elicit an immune response” (Gerba, 1996, pp. 357-358).
 
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