Chemical analysis The use of a standard chemical analytical procedures to determine the concentration of a specific analyte in a sample, or qualitatively or
quantitatively measure a specific parameter of a sample.
Chemical oxygen demand (COD) An environmental chemical test used to measure indirectly organic compounds in water or wastewater.
Childproofing Making the physical environment safe for the children in your care
to reduce the risks of injury.
Chlorination (a) The application of chlorine to water or wastewater, generally for
the purpose of disinfection, but frequently for accomplishing other biological or
chemical results, and (b) one of disinfection processes involving the use of
chlorine gas. Disinfection with chlorine is accomplished by adding chlorine gas
to the water or wastewater. Sometimes application of sodium hypochlorite
(liquid) for disinfection is also called chlorination. Academically disinfection
using sodium hypochlorite should be called hypochlorination.
Chlorine demand Chlorine demand is the difference between the amount of
chorine added to wastewater and the amount of residual chlorine remaining
after a given contact time. Chlorine demand may change with dosage, time,
temperature, pH, or nature or amount of the impurities in the water. Chlorine
demand, mg/L ¼ chlorine applied, mg/L – chlorine residual, mg/L
Chlorine requirement The amount of chlorine that is needed for a particular
purpose. Some reasons for adding chlorine are reducing the number of coliform
bacteria (Most Probable Number), obtaining a particular chlorine residual, or
oxidizing some substance in the water. In each case, a definite dosage of chlorine
will be necessary. This dosage is the chlorine requirement.
Chlorine sponge Incomplete nitrification resulting in excess nitrite levels that react
with chlorine. Also known as “Nitrite Lock.”
Chlorofluorocarbons Gases covered under the 1987 Montreal Protocol and used
for refrigeration, air conditioning, packaging, insulation, solvents, or aerosol
propellants. Since they are not destroyed in the lower atmosphere, CFCs drift
into the upper atmosphere where, given suitable conditions, they break down
ozone. These gases are being replaced by other compounds:
hydrochlorofluorocarbons, an interim replacement for CFCs that are also covered
under the Montreal Protocol, and hydrofluorocarbons, which are covered under
the Kyoto Protocol. All these substances are also greenhouse gases.
Chloroform It is a colorless, volatile, sweet-smelling liquid (CHCl 3 ) used as an
organic solvent in an analytical procedure and formerly as a general anesthetic in
a medical procedure.
Civil engineering It is a professional engineering discipline that deals with the
design, construction, and maintenance of the physical and naturally built environment, including public works such as roads, bridges, canals, dams, airports,
sewerage systems, pipelines, structural components of buildings, and railways.
Civil engineering is traditionally broken into a number of subdisciplines. It is
considered the second-oldest engineering discipline after military engineering,
and it is defined to distinguish nonmilitary engineering from military engineering.
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435
quantitatively measure a specific parameter of a sample.
Chemical oxygen demand (COD) An environmental chemical test used to measure indirectly organic compounds in water or wastewater.
Childproofing Making the physical environment safe for the children in your care
to reduce the risks of injury.
Chlorination (a) The application of chlorine to water or wastewater, generally for
the purpose of disinfection, but frequently for accomplishing other biological or
chemical results, and (b) one of disinfection processes involving the use of
chlorine gas. Disinfection with chlorine is accomplished by adding chlorine gas
to the water or wastewater. Sometimes application of sodium hypochlorite
(liquid) for disinfection is also called chlorination. Academically disinfection
using sodium hypochlorite should be called hypochlorination.
Chlorine demand Chlorine demand is the difference between the amount of
chorine added to wastewater and the amount of residual chlorine remaining
after a given contact time. Chlorine demand may change with dosage, time,
temperature, pH, or nature or amount of the impurities in the water. Chlorine
demand, mg/L ¼ chlorine applied, mg/L – chlorine residual, mg/L
Chlorine requirement The amount of chlorine that is needed for a particular
purpose. Some reasons for adding chlorine are reducing the number of coliform
bacteria (Most Probable Number), obtaining a particular chlorine residual, or
oxidizing some substance in the water. In each case, a definite dosage of chlorine
will be necessary. This dosage is the chlorine requirement.
Chlorine sponge Incomplete nitrification resulting in excess nitrite levels that react
with chlorine. Also known as “Nitrite Lock.”
Chlorofluorocarbons Gases covered under the 1987 Montreal Protocol and used
for refrigeration, air conditioning, packaging, insulation, solvents, or aerosol
propellants. Since they are not destroyed in the lower atmosphere, CFCs drift
into the upper atmosphere where, given suitable conditions, they break down
ozone. These gases are being replaced by other compounds:
hydrochlorofluorocarbons, an interim replacement for CFCs that are also covered
under the Montreal Protocol, and hydrofluorocarbons, which are covered under
the Kyoto Protocol. All these substances are also greenhouse gases.
Chloroform It is a colorless, volatile, sweet-smelling liquid (CHCl 3 ) used as an
organic solvent in an analytical procedure and formerly as a general anesthetic in
a medical procedure.
Civil engineering It is a professional engineering discipline that deals with the
design, construction, and maintenance of the physical and naturally built environment, including public works such as roads, bridges, canals, dams, airports,
sewerage systems, pipelines, structural components of buildings, and railways.
Civil engineering is traditionally broken into a number of subdisciplines. It is
considered the second-oldest engineering discipline after military engineering,
and it is defined to distinguish nonmilitary engineering from military engineering.
12 Glossary of Natural Resources and Environmental Pollution Control
435