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ABS |
See Alkyl Benzene Sulfonate |
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Absorbent |
A material, usually a
porous solid, which takes another material into its interior. When rain
soaks into soil, the soil is an absorbent. |
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Absorption |
The process in which one
substance is taken into the body of an absorbent. |
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Acid |
A substance which increases
the concentration of hydrogen ions when dissolved in water. Most acids
will dissolve the common metals and will react with a base to form a
neutral salt and water. |
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Acidity |
The quantitative capacity
of water or a water solution to neutralize an alkali or base. It is
usually measured by titration with a standard solution of sodium hydroxide
and expressed in terms of its calcium carbonate equivalent. (See mineral
acidity, total acidity, carbon dioxide.) |
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Acre-Foot |
The volume of water which
would cover an area of one acre to a depth of one foot. It is equal to
43,560 cubic feet (1,233 cubic meters) or 325,851 gallons (1,233,L). |
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Action Level |
The level of lead or copper
which, if exceeded, triggers treatment or other requirements that a water
system must follow. |
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Activated Carbon |
A granular material usually
produced by roasting various grades of coal in the absence of air. It has
a very porous structure and it is used in water conditioning as an
adsorbent (see "adsorption") for organic matter and certain
dissolved gases. Sometimes called "activated charcoal". |
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Activated Silica |
A material usually formed
from the reaction of a dilute silicate solution with a dilute acid. It is
used as a coagulant aid. |
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Acute Health Effect |
An immediate (i.e. within
hours or days) effect that may result from exposure to certain drinking
water contaminants (e.g., pathogens). |
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Adsorbent |
A material, usually solid,
capable of holding gases, liquids and/or suspended matter at its surface
and in exposed pores. Activated carbon is a common adsorbent used in water
treatment. |
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Adsorption |
The process in which matter
adheres to the surface of an adsorbent. |
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Aeration |
The process in which air is
brought into intimate contact with water, often by spraying water through
air, or by bubbling air through water. Aeration may be used to add oxygen
to the water for the oxidation of matter such as iron, or to cause the
release of dissolved gases such as carbon dioxide or hydrogen sulfide from
the water. |
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Aerobic |
An action or process
conducted in the presence of air, such as aerobic digestion of organic
matter by bacteria. |
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Air Gap |
A clear vertical space
between a water or drain line and the flood level of a receptacle to
prevent back-flow or siphoning from the receptacle in the event of
negative pressure or vacuum. Most plumbing codes require the air gap to be
at least twice the diameter of the water or drain line, with a minimum of
1-1/2 inches (3.8 cm). (See vacuum breaker or back-flow presenter.) |
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Algae |
Small primitive plants
containing chlorophyll, commonly found in surface water. Excessive growths
may create taste and odor problems, and consume dissolved oxygen during
decay. |
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Alkali |
A group of water soluble
mineral compounds, usually considered to have moderate strengths as bases
(as opposed to the caustic or strongly basic hydroxides, although this
differentiation is not always made). In general, the term is applied to
bicarbonate and carbonate compounds when they are present in the water or
solution. (See alkali, base.) |
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Alkalinity |
The quantitative capacity
of a water or water solution to neutralize an acid. It is usually measured
by titration with a standard acid solution of sulfuric acid and is
expressed in terms of its calcium carbonate equivalent. (See alkali,
base.) |
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Alkyl Benzene Sulfonate |
A term applied to a family
of branched chain chemical compounds, formerly used as detergents,.
Sometimes called "hard" detergents, because of their resistance
to biological degradation, these compounds have been largely replaced with
linear alkyl sulfonate (LAS) which are more readily degraded to simpler
substances. (See detergent, linear alkyl sulfonate.) |
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Alum |
A common name for aluminum
sulfate, used as a coagulant. |
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Amoeba |
A small, single-celled
animal or protozoan. |
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Anaerobic |
An action or process
conducted in the absence of air, such as the anaerobic digestion of
organic matter by bacteria in a septic tank. |
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Angstrom Unit |
A unit of length equal to
one ten-billionth of a meter. |
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Anion |
A negatively charged ion in
solution, such as bicarbonate, chloride, nitrate or sulfate. |
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Anion Exchange |
An ion exchange process in
which anions in solution are exchanged for other anions from an ion
exchanger. In demineralization, for example, bicarbonate, chloride and
sulfate anions are removed from solution in exchange for a chemically
equivalent number of hydroxide anions from the anion exchange resin. (See
ion exchange, demineralization.) |
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Anode |
The positive pole of an
electrolytic system meter when oxidation occurs. Anodes made of magnesium
or zinc are sometimes installed in water heaters or other tanks to
deliberately establish galvanic cells to control corrosion of the tank
through the sacrifice of the anode. |
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Aquifer |
A natural underground
layer, often of sand or gravel, that contains water. |
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Arsenic |
A
natural element of the earth's crust, arsenic enters water supplies either
through natural deposition or agricultural and industrial pollution.
According to the Environmental Protection Agency (EPA), Office of Ground
Water and Drinking Water, health effects of arsenic include skin damage,
circulatory system problems and an increased risk of various cancers. |
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Asbestos |
A
fibrous mineral, asbestos can enter water naturally or through the decay
of asbestos cement in water mains. According to the Environmental
Protection Agency (EPA), Office of Ground Water and Drinking Water, this
contaminant may increase the risk of developing benign intestinal polyps
and has been linked to cancer. |
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Atom |
The smallest particle of an
element that can exist either alone or in combination. |
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Atrazine |
Atrazine is an herbicide
contaminant which has been in the news lately after, being upgrade from a
"possible" to a "likely" carcinogen. according to USA
Today, atrazine is the most commonly used herbicide. Atrazine enters water
supplies as runoff from farmers' fields. According to the EPA, atrazine
causes cardiovascular system problems and reproductive difficulties. |
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Attrition |
In water treatment, the
process in which solids are worn down or ground down by friction, often
between particles of the same material. Filter media and ion exchange
materials are subject to attrition during backwashing, regeneration and
service. |
