Glossary Of Water Treatment Industry Terms . . ."S"
saline water- Water containing
an excessive amount of dissolved salts, usually over 5,000 mg/l.
salt- In chemistry, the term
is applied to a class of chemical compounds which can be formed by the
neutralization of an acid with a with a base; the common name for the
specific chemical compound sodium chloride used in the regeneration of
ion exchange water softeners.
salt splitting - The
process in which neutral salts in water are converted to their corresponding
acids or bases by ion exchange resins containing strongly acidic or strongly
basic functional groups.
saponification - The process
in which a fatty acid is neutralized with an alkali or base to form a
scale - A deposit of mineral
solids on the interior surfaces of water lines and containers, often formed
when water containing the carbonates or bicarbonates of calcium and magnesium
sedimentation- The process
in which solid suspended particles settle out of water, usually when the
water has little or no movement. Also called "settling".
semipermeable membrane -
Typically a thin, organic film which allows the passage of some ions
or materials while preventing the passage of others. Some membranes will
only allow the passage of cations. (See electrodialysis.) Some membranes
reject most dissolved substances, but allow the passage of water. (See
septic - A condition existing
during the digestion of organic matter, such as in sewage, by anaerobic
bacteria in the absence of air. A common process for the treatment of
household sewage in septic tanks, and in municipal sewage treatment in
specially designed digester.
sequestration - A chemical
reaction in which certain ions are bound into a stable, water soluble
compound, thus preventing undesirable action by the ions. (See chelate.)
sequestering agent- A
chemical compound sometimes fed into water to tie up undesirable ions,
keep them in solution, and eliminate or reduce the normal effects of the
ions. For example, polyphosphate can sequester hardness and prevent reactions
with soap. (See cheating agent.)
service run - That portion
of the operating cycle of a water conditioning unit in which treated water
is being delivered, as opposed to the period when the unit is being backwashed,
recharged or regenerated.
service unit - A term
sometimes applied to softeners or filters which are regenerated or backwashed
at a central point, then transported to the point of use for connection
to the water system. (See portable exchange.)
shielded - The separation
of metallic parts by an electrical nonconductor; insulated by other than
an air gap.
silica gel or siliceous gel
- A synthetic hydrated sodium aluminosilicate with ion exchange properties,
once widely used in ion exchange water softeners. (See zeolite, gel zeolite.)
sludge - The semi-fluid
solid matter collected at the bottom of a system tank or watercourse,
as a result of the sedimentation or settling of suspended solids or precipitates.
slug - An abnormally high
concentration of an undesirable substance which passes through a water
system, usually brief or intermittent in nature, and often related to
an upset of a system. For example, a slug of iron may occur during high
flow which disturbs and suspends previously deposited iron precipitates.
soap - One of a class of chemical
compounds which possesses cleansing properties; formed by the reaction
of a fatty acid with a base or alkali. Sodium and potassium soaps are
soluble and useful, but can be converted to insoluble calcium and magnesium
soaps (curd) by the presence of these hardness ions in water.
soda ash - the common name
for sodium carbonate, Na2CO3, a chemical compound
used as an alkalinity builder in some soap and detergent formulations
to neutralize acid water, and in the lime-soda water treatment process.
sodium - An ion found in
natural water supplies, and introduced to water in the ion exchange water
softening process. Sodium compounds are highly soluble, and do not react
with soaps or detergents.
sodium chloride - The chemical
name for common salt, widely used in the regeneration of ion exchange
sodium cycle - the cation
exchange process in which sodium on the ion exchange resin is exchanged
for hardness and other ions in water. Sodium chloride is the common regenerant
used in this process.
soft water- Any water which
contains less than 1.0 gpg (17.1 mg/l) of hardness minerals, expressed
as calcium carbonate.
softened water- Any water
that is treated to reduce hardness minerals to 1.0 gpg (17.1 mg/l) or
less, expressed as calcium carbonate.
solute - The substance which
is dissolved in and by a solvent. Dissolved solids, such as the minerals
found in water, are solutes.
solution feeder - A device,
such as a power driven pump or an eductor system, designed to feed a solution
of a water treatment chemical into the water system, usually in proportion
to flow. (See chemical feeder.)
solvent - The liquid, such
as water, in which other materials (solutes) are dissolved. (See solute.)
specific conductance -
The measure of the electrical conductance of water or a water solution
at a specific temperature, usually 25oC. (See resistance.)
specific gravity- The
ratio of the weight of a specific volume of a substance compared to the
weight of the same volume of pure water at 4oC.
specific resistance - The
measure of the electrical resistance of water or a water solution at a
specific temperature, usually 25oC. (See resistance.)
sphericity - A measure
of the roundness and wholeness of an ion exchange resin bead.
spore - In general, specialized
reproductive bodies or resting cells. In water bacterial "spores"
resist adverse conditions which would readily destroy the parent organism.
Standard Methods - The
abbreviation for the name of the reference book "Standard Methods
for the Examination of Water and Wastewater", widely used in water
and waste water testing and analysis.
static - Fixed in position,
resting, or without motion, as opposed to dynamic or moving.
static system - A system
or process in which the reactants are not flowing or moving. (See dynamic
sterilization - A process
in which all living organisms are destroyed. (See disinfection.)
strong base load factor z
- Is the total exchangeable anions. Thus it is the sum of total anions
(which equals the Y factor) plus silica, plus carbon dioxide (not carbonic
acid formed). 35 gpg is considered upper limit for DI applications.
sulfate - In the range
of 30 gpg, sulfate salts can cause laxative effects and medicinal taste.
In high concentration with high calcium hardness, a white insoluble compound
is formed that is difficult to remove.
- A group of bacteria which are capable of reducing sulfates in water
to hydrogen sulfide gas, thus producing obnoxious tastes and odors. These
bacteria have no sanitary significance, and are classed as nuisance organisms.
sulfonic acid- A specific
acidic group (SO3H) which gives certain cation exchange resins
their ion exchange capability.
sulfur - A yellowish solid
element. The term is also commonly used to refer to water containing hydrogen
superchlorination - The
addition of excess amounts of chlorine to a water supply to speed chemical
reactions or insure disinfection with short contact time. The chlorine
residual following superchlorination is high enough to be unpalatable,
and thus dechlorination is commonly employed before the water is used.
supernatant - The clear liquid
lying above a sediment or precipitate.
surface-active agent- The
material in a soap or detergent formulation which promotes the penetration
of the fabric by water, the loosening of the soil from surfaces, and the
suspension of many soils; the actual cleaning agent in soap and detergent
surface tension - The
result of attraction between molecules of a liquid which causes the surface
of the liquid to act as a thin elastic film under tension. Surface tension
causes water to form spherical drops, and to reduce penetration into fabrics.
Soaps, detergents and wetting agents reduce surface tension and increase
penetration by water.
surfactant - A contraction
of the term "surface-active agent".
suspended solids - Solid
particles in water which are not in solution.
swelling - In the water treatment
context, the expansion of certain ion exchange resins when converted into
specific ionic states.
syndet - A contraction of
the term "synthetic detergent".
synthetic detergent - A synthetic cleaning agent, such as linear alkyl sulfonate and alkyl benzene sulfonate. Synthetic detergents react with water hardness, but the products are soluble.