443
SLUDGE REDUCTION: Organic polymers are used to reduce the quantity of sludge. If a plant
produces a large volume of sludge, the sludge could be dewatered, thickened, or conditioned to
decrease the volume of sludge. Turbidity of source water, dosage, and type of coagulant used
are the most important factors which determine the amount of sludge produced in a treatment of
water.
SMALL WATER SYSTEM: 3,300 or fewer persons.
SOC: Synthetic organic chemical. A common way for a synthetic organic chemical such as
dioxin to be introduced to a surface water supply is from an industrial discharge, agricultural
drainage, or a spill.
SODA ASH: Chemical used to raise pH and total alkalinity (sodium carbonate).
SODIUM BICARBONATE: Commonly used to increase alkalinity of water and stabilize pH.
SODIUM BISULFATE: Chemical used to lower pH and total alkalinity (dry acid).
SODIUM HYDROXIDE: Also known as caustic soda, a by-product chlorine generation and often
used to raise pH.
SOFTENING WATER: When the water has a low alkalinity it is advantageous to use soda ash
instead of caustic soda for softening water.
SOFTENING: The process that removes the ions which cause hardness in water.
SOL: A suspension of solid particles in liquid. Artificial examples include sol-gels.
SOLAR DRYING BEDS OR LAGOONS: Are shallow, small-volume storage pond where sludge is
concentrated and stored for an extended periods.
SOLAR DRYING BEDS, CENTRIFUGES AND FILTER PRESSES: Are procedures used in the
dewatering of sludge.
SOLDER: A fusible alloy used to join metallic parts.
SOLID: One of the states of matter, where the molecules are packed close together, there is a
resistance of movement/deformation and volume change; see Young's modulus.
SOLID, LIQUID AND VAPOR: 3 forms of matter.
SOLUTE: The part of the solution that is mixed into the solvent (NaCl in saline water).
SOLUTION: Homogeneous mixture made up of multiple substances. It is made up of solutes and
solvents.
SOLVENT: The part of the solution that dissolves the solute (H2O in saline water).
SPADNS: The lab reagent called SPADNS solution is used in performing the Fluoride test.
SPECTROSCOPY: Study of radiation and matter, such as X:ray absorption and emission
spectroscopy.
SPEED OF LIGHT: The speed of anything that has zero rest mass (Energyrest = mc² where m is
the mass and c is the speed of light).
SPIRIT OF HARTSHORN: A colorless, pungent, suffocating, aqueous solution of about 28.5
percent ammonia gas: used chiefly as a detergent, for removing stains and extracting certain
vegetable coloring agents, and in the manufacture of ammonium salts.
SPLIT FLOW CONTROL SYSTEM: This type of control system is to control the flow to each filter
influent which is divided by a weir.
SPRAY BOTTLE OF AMMONIA: An operator should use ammonia to test for a chlorine leak
around a valve or pipe. You will see white smoke if there is a leak.
STANDARD CONDITIONS FOR TEMPERATURE AND PRESSURE or SATP : A standardization
used in order compare experimental results (25 °C and 100.000 kPa).
STANDPIPE: A water tank that is taller than it is wide. Should not be found in low point.
STATE OF MATTER: Matter having a homogeneous, macroscopic phase; gas, plasma, liquid,
and solid are the most well-known (in increasing concentration).
STERILIZED GLASSWARE: The only type of glassware that should be used in testing for
coliform bacteria.
STORAGE TANKS: Three types of water usage that determine the volume of a storage tank are
fire suppression storage, equalization storage, and emergency storage. Equalization storage is
the volume of water needed to supply the system for periods when demand exceeds supply.
Generally, a water storage tank’s interior coating (paint) protects the interior about 3-5 years.
SUBATOMIC PARTICLES: Particles that are smaller than an atom; examples are protons,
neutrons and electrons.
SUBLIMATION: A phase transition from solid to limewater fuel or gas.