Environmental Engineering Reference
In-Depth Information
and radionuclide parameters and is delivered to a treatment works for pro-
cessing and disinfecting. Such a treatment works must be properly designed,
constructed, and operated. Drinking water must be delivered to the con-
sumer in sufficient quantity and pressure and must meet stringent quality
standards. It must be palatable, be within reasonable temperature limits, and
have the complete confidence of the consumer.
The bottom line is that drinking water is a substance available to the con-
sumer at the household tap that can perform one essential function: It can
satisfy thirst without threatening life and health.
Definitions
Absorption
—A process where one substance penetrates the interior of
another substance.
Acid rain—
Precipitation with higher than normal acidity, caused pri-
marily by sulfur and nitrogen dioxide air pollution.
Activated carbon—
A very porous material that can be used to adsorb
pollutants from water after the material has been subjected to intense
heat to drive off impurities.
Adsorption—
The process by which one substance is attracted to and
adheres to the surface of another substance, without actually pen-
etrating its internal structure.
Aeration—
A physical treatment method that promotes biological deg-
radation of organic matter. The process may be passive (when waste
is exposed to air) or active (when a mixing or bubbling device intro-
duces air).
Aerobic bacteria—
A type of bacteria that requires free oxygen to carry
out metabolic function.
Biochemical oxygen demand (BOD)—
The amount of oxygen required
by bacteria to stabilize decomposable organic matter under aerobic
conditions.
Biological treatment—
A process that uses living organisms to bring
about chemical changes.
Breakpoint chlorination—
The addition of chlorine to water until the chlo-
rine demand has been satisfied and free chlorine residual is avail-
able for disinfection.
Chemical treatment—
A process that results in the formation of a new
substance or substances. The most common chemical water treat-
ment processes include coagulation, disinfection, water softening,
and filtration.
Chlorination—
The process of adding chlorine to water to kill disease-
causing organisms or to act as an oxidizing agent.
