442SCADA: A remote method of monitoring pumps and equipment. 130 degrees F is the maximum
temperature that transmitting equipment is able to with stand. If the level controller may be set
with too close a tolerance 45 could be the cause of a control system that is frequently turning a
pump on and off.
SCALE: Crust of calcium carbonate, the result of unbalanced water. Hard insoluble minerals
deposited (usually calcium bicarbonate) which forms on pool and spa surfaces and clog filters,
heaters and pumps. Scale is caused by high calcium hardness and/or high pH. The regular use of
stain prevention chemicals can prevent scale.
SCHMUTZDECKE: German, "grime or filth cover", sometimes spelt schmutzedecke) is a
complex biological layer formed on the surface of a slow sand filter. The schmutzdecke is the
layer that provides the effective purification in potable water treatment, the underlying sand
providing the support medium for this biological treatment layer. The composition of any
particular schmutzdecke varies, but will typically consist of a gelatinous biofilm matrix of bacteria,
fungi, protozoa, rotifera and a range of aquatic insect larvae. As a schmutzdecke ages, more
algae tend to develop, and larger aquatic organisms may be present including some bryozoan,
snails and annelid worms.
SCHRODINGER EQUATION: Quantum state equation which represents the behavior of an
election around an atom.
SCROLL AND BASKET: The two basic types of centrifuges used in water treatment.
SEAL: For wells: to abandon a well by filling up the well with approved seal material including
cementing with grout from a required depth to the land surface.
SECONDARY DRINKING WATER STANDARDS: Non-enforceable federal guidelines regarding
cosmetic effects (such as tooth or skin discoloration) or aesthetic effects (such as taste, odor, or
color) of drinking water.
SECTIONAL MAP: The name of a map that provides detailed drawings of the distribution
system’s zones. Sometimes we call these quarter-sections.
Sediment: Grains of soil, sand, gravel, or rock deposited by and generated by water movement.
SEDIMENTATION BASIN: Where the thickest and greatest concentration of sludge will be found.
Twice a year sedimentation tanks should be drained and cleaned if the sludge buildup interferes
with the treatment process.
SEDIMENTATION: The process of suspended solid particles settling out (going to the bottom of
the vessel) in water.
SEMICONDUCTOR: An electrically conductive solid that is between a conductor and an
insulator.
SENSOR: A float and cable system are commonly found instruments that may be used as a
sensor to control the level of liquid in a tank or basin.
SESSILE: Botany. attached by the base, or without any distinct projecting support, as a leaf
issuing directly from the stem. Zoology. permanently attached; not freely moving.
SETTLED SOLIDS: Solids that have been removed from the raw water by the coagulation and
settling processes.
SHOCK: Also known as superchlorination or break point chlorination. Ridding a water of organic
waste through oxidization by the addition of significant quantities of a halogen.
SHORT-CIRCUITING: Short Circuiting is a condition that occurs in tanks or basins when some of
the water travels faster than the rest of the flowing water. This is usually undesirable since it may
result in shorter contact, reaction or settling times in comparison with the presumed detention
times.
SINGLE BOND: Sharing of one pair of electrons.
SINGLE PHASE POWER: The type of power used for lighting systems, small motors, appliances,
portable power tools and in homes.
SINUSOID: A curve described by the equation y = a sin x, the ordinate being proportional to the
sine of the abscissa.
SINUSOIDAL: Mathematics. Of or pertaining to a sinusoid. Having a magnitude that varies as
the sine of an independent variable: a sinusoidal current.
SLUDGE BASINS: After cleaning sludge basins and before returning the tanks into service the
tanks should be inspected, repaired if necessary, and disinfected.