Definitions:
A
absolute filter rating: Filter rating meaning
that 99.9% (or essentially all) of the particles larger than a
specific micron rating will be trapped on or within the filter.
absorption: The process of one substance actually
penetrating into the structure of another substance. This is different
from adsorption in which one substance adheres to the surface
of another.
accumulation tank: A vessel or tank, which receives
and stores product water for use on demand.
acid: A substance, which releases 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. An
acid is the opposite of an alkali, has a pH rating lower than
7.0, will turn litmus paper red and has a sour taste.
activated alumina: A medium made by treating
aluminum ore so that it becomes porous and highly adsorptive.
Activated alumina will remove several contaminants including fluoride,
arsenic and selenium. This medium requires periodic cleaning and
appropriate reagent such as alum, acid and or/caustic.
activated carbon: A water treatment medium,
found in block, granulated, or powder form, which is produced
by heating carbonaceous substances (bituminous coal or cellulose-based
substance such as wood or coconut shell) in the absence of air,
creating a highly porous adsorbent material.
adsorption: The physical process occurring when
liquids, gases or suspended matter adhere to the surface of, or
in the pores of, an adsorbent medium. Adsorption is a physical
process which occurs without chemical reaction.
aeration: The process whereby water is brought
into intimate contact with air by spraying or cascading, or air
is brought into intimate contact with water by an air aspirator
or by bubbling compressed air through the body of water. Both
pressure (closed) aerators and open (gravity) aerators are used.
Closed aeration is used chiefly for oxidation; open aeration for
degassing.
aerobic: An action or process conducted in the
presence of air, such as aerobic digestion of organic matter by
bacteria.
aesthetic contaminants: Characteristics of water
which affects its taste, odor, color and appearance (and may affect
the objects touched by the water) but which do not in themselves
have any adverse health effects in otherwise potable water.
algae: Single-celled or simple multi-celled
organisms, commonly found in surface water, which produce their
own food through photosynthesis. Excessive algae growth may cause
the water to have undesirable odors or tastes and decay of algae
can deplete the oxygen in the water.
alkali: A substance which creates a bitter taste
and a slippery feel when dissolved in water and will turn litmus
paper blue. An alkali has a pH greater than 7.0 and is the opposite
of an acid. Highly alkaline waters tend to cause drying of the
skin.
amoeba: A single celled protozoan that is widely
found in fresh and salt water. Some types of amoebas cause diseases
such as amoebic dysentery.
anaerobic: A condition in which there is no
air or no available free oxygen.
anaerobic organisms: An organism that can strive
in the absence of oxygen (air), such as bacteria in a septic tank.
anion: An ion with a negative charge.
aqueous: Containing water; watery.
aquifer: A natural water-bearing formation which
is found below the surface of the earth.
B
back pressure: Pressure which creates resistance
against a flow of water.
backflow: The flow of water in a pipe or line
in a direction opposite to the normal flow.
bacteria: Single-celled organisms (single form
= bacterium) which lack well-defined nuclear membranes and other
specialized functional cell parts and reproduce by cell division
or spores. Bacteria may be free-living organisms or parasites.
Bacteria (along with fungi) are decomposers that break down the
wastes and bodies of dead organisms making their components available
for reuse. Bacteria cells range from about 1 - 10 micron in length
and from .2 - 1.0 micron in width. They exist almost everywhere
on earth. Despite their small size, the total weight of all bacteria
in the world likely exceeds that of all other organisms combined.
Some bacteria are helpful others are harmful.
bactericide: Any substance or agent which kills
bacteria.
bacteriostatic: Having the ability to inhibit
the growth of bacteria without destroying the bacteria. For example:
silver-impregnated activated carbon will reduce bacterial colonization
but not eliminate it.
ballast: The power supply to activate and regulate
voltage in an ultraviolet (UV) lamp.
beaver fever: See Giardia
lamblia.
biocide: A chemical which can kill or inhibit
the growth of living organisms such as bacteria, fungi, molds
and slimes. Biocides can be harmful to humans.
biodegradables: Subject to degradation (break
down) into simple substances by biological action. For example:
the breakdown of detergents, sewage wastes and other organic matter
by bacteria.
bleach: A strong oxidizing agent and disinfectant
formulated to break down organic matter and destroy biological
organisms.
blinding: The reduction or shutting off of flow
due to filter medium or membrane fouling.
brackish water: Water containing dissolved solids
in the range > 1,000 to < 15,000 ppm .
breakthrough: The appearance in the product
water of an amount of the contaminant which exceeds the design
performance criteria.
brine: A strong solution of salt(s) with total
dissolved solid s concentrations. The waste solution in both automatic
water softeners and reverse osmosis systems.
C
CA: cellulose acetate.
calcium (CA): One of the principal elements
making up the earth's crust. Calcium compounds, when dissolved,
make hard water. The presence of calcium in water is a factor
contributing to the formation of scale and insoluble soap curds
which are a means of clearly identifying hard water.
capacity: See rated capacity.
capillary action: A phenomenon in which water
or other liquids will rise above the normal liquid level in a
tiny tube or capillary due to the attraction of the molecules
in the liquid for each other and for the walls of the tube.
carbon ( C ): An element which is found in almost
all living or formerly living matter including plants, proteins,
organics and hydrocarbons. Carbon combines readily with oxygen
to form carbon dioxide (CO2 ). The term "carbon" is
sometimes used as a short reference for activated carbon.
carbonaceous: Containing carbon and derived
from organic substances such as coal, coconut shells and wood.
carcinogens: A substance that can cause cancer.
cartridge: Any removable pre-formed or pre-packaged
component containing a filtering medium, ion exchanger, membrane
or other treatment material which fits inside a housing to make
up a cartridge filter.
cartridge filter: A device often used for single
faucet water treatment, made up of a housing and a removable cartridge
(element). In residential filtering systems, disposable elements
are used.
catalysis: The speeding up (usually) of a chemical
reaction by adding a specific substance, the catalyst. Although
the catalyst causes the speedup of the reaction, it (the catalyst)
is not changed chemically in any way.
cation: An ion carrying one or more positive
charges.
caustic: Any substance capable of burning or
destroying flesh or tissue. The term usually applies to strong
bases.
cellulose acetate (CA) and cellulose triacetate (CTA):
A cellulose ester obtained by introducing the acetyl radical (CH3CO-)
of acetic acid into cellulose (as cotton or wood fibers) to produce
a tough plastic material which is used to make the cellulosic
type of semipermeable reverse osmosis membranes.
centrigrade also known as celsius: A temperature
scale in which 100 degrees is the boiling point and zero degrees
the freezing point for water at sea level.
CFU: colony-forming-units.
channeling: The flow of water through a limited
number of passages in a filter.
charcoal: An adsorbent carbon product which
has about one-third the surface area of activated carbon.
check valve: A valve which will allow water
to pass in one direction but will close and prevent flow (backflow)
in the opposite direction.
chloramines: Chemical complexes formed from
the reaction between ammonia and chlorine being used to disinfect
many municipal water supplies. Unlike chlorine, chloramines do
not combine with organics in the water to form potentially dangerous
trihalomethanes (THMs). Water containing chloramines may not be
used for fish or for kidney dialysis applications.
chlorine (Cl2): A gas widely used in the disinfection
of water and as an oxidizing agent for organic matter . Chlorine
is known to react with organic matter in the water to form trihalomethanes
(THMs), a suspected carcinogen.
clear water iron: See ferrous iron.
Coliform bacteria: A particular group of bacteria
primarily found in human and animal intestines and wastes. These
bacteria are widely used as indicators organisms to show the presence
of such wastes in water and the possible presence of pathogenic
(disease producing) bacteria. Escherichia coli (E. coli) is one
of the fecal coliform bacteria widely used for this purpose.
color: A shade or tint which is imparted to
water by substances which are in true solution and thus cannot
be removed by mechanical filtration. Color is most commonly caused
by dissolved organic matter, but it may be produced by dissolved
mineral matter.
contact time: The time the water is allowed
to contain the disinfectant to assure potability. Contact time
may also be called retention time.
contaminant: Any undesirable physical, chemical
or microbiological substance or matter in a given water source
or supply. Anything in water which is not H2O may be considered
a contaminant.
cross contamination: The intermixing of two
water streams which results in unacceptable water quality for
a given purpose.
cryptosporidium: A waterborne protozoan that
forms cysts and causes acute gastrointestinal illness in humans,
Cryptosporidium is commonly found in unfiltered surface water
and is resistant to disinfectants such as chlorine and ultraviolet
light, but it can be removed by filters that capture all particles
of one micron and greater in size.
cyst: A capsule or protective sac produced about
themselves by many protozoans (as well as some bacteria and algae)
as preparation for entering a resting or a specialized reproductive
stage. Similar to spores, cysts tend to be more resistant to destruction
by disinfectant. Fortunately, protozoan cysts are typically 2-50
microns in diameter and can be removed from water by fine filtration.
D
depth filtration: A filtration process in which
water flows through progressively smaller pore spaces in a filter.
Depth filters are designed to entrap particles throughout the
mass of the filter media, as opposed to a surface filter where
only the surface layer does the actual filtering.
desalination: The removal of dissolved inorganic
solids (salts) from solution such as water to produce a liquid
which is free of dissolved salts. Desalination is typically accomplished
by distillation, reverse osmosis or electrodialysis.
dew point: The temperature to which air must
be cooled to cause condensation of the water vapor it contains.
disinfection: The treatment of water to inactivate,
destroy and /or remove pathogenic (disease producing) bacteria,
viruses, cysts, and other microorganisms for the purpose of making
the water microbiologically safe for human consumption. Disinfection
may involve the use of disinfecting chemicals such as chlorine,
iodine, ozone or peroxide; or it may involve physical processes
such as distillation, microfiltration, ultrafiltration, boiling
or ultraviolet radiation. Disinfection may also be called sterilization.
dissolved solids also known as total dissolved solids:
The weight of matter, including both organic and inorganic matter,
in true solution in a stated volume of water. The amount of dissolved
solids is usually determined by filtering water through a 0.45
pore-diameter micron filter and weighing the filtration residue
left after the evaporation of the water at 180 degree C.
distillate: The product water, which is mineral-free
and potable, from a distiller unit.
distillation: The process of separating the
water from the organic and inorganic contaminants through a combination
of evaporation (or vaporization), cooling and condensation.
distilled water: Water which has been cleansed
by passing through one or more evaporation-condensation cycles
until it contains a very low amount of dissolved solids (usually
less than 5.0 ppm TDS).
drain: A pipe or conduit which carries liquids
by gravity to waste.
drain line: A pipe line which is used to carry
water from the water treatment system to a waste system.
drinking water: A water treated or untreated
which is intended for human use and consumption and considered
to be free of harmful chemicals and disease-causing bacteria,
cysts, viruses or other microorganisms. See also potable water.
E
E. coli: See Escherichia coli
efficiency (media filtration): The percent of
contaminant reduction which occurs with a specified medium volume
and specified water contact time.
efficiency (membrane filtration): The figure
obtained (expressed as a percent) by dividing the volume gallons
pf product water produced by the total volume (gallons) of feed
water fed to the particular unit or system.
effluent: The outflow from any water processing
system or device. Sometimes used to mean the product water of
a given device or system.
ejection: The process of forcing something out,
expelling it.
enzyme: A chemical produced by living cells,
which can bring about the digestion (breakdown) of organic molecules
into smaller units that can be used by living cell tissues.
Escherichia coli (E coli): One of the members
of the coliform bacteria group normally found in human and animal
intestines and indicative of fecal contamination when found in
water. Determination of whether E. coli is present is often used
to measure the microbiological safety of drinking water supplies.
evaporation: The process by which a substance
is changed from the liquid to the vapor state.
evaporation chamber: The part of a distillation
system in which water is changed into vapor.
evaporite: A mineral precipitated
as a result of evaporation, such as the solids left behind in
the distillation process.
F
FAC: Free available chlorine.
facultative organisms: Microbes capable of adapting
to either aerobic or anaerobic environments.
fahrenheit: A temperature scale in which water
freezes at 32 degrees and boils at 212 degrees at atmospheric
pressure.
fecal matter: Matter (feces) containing or derived
from animal or human bodily wastes that are discharged through
the anus.
fecal coliform: Coliform bacteria found in
fecal matter.
feed pressure: The pressure at which water is
supplied to a water treatment device.
feedwater: The water to be treated that is fed
into a given water treatment system.
fermentation: The conversion/breakdown of organic
matter by anaerobic bacteria into carbon dioxide, methane and
similar compounds of low molecular weight.
ferric iron: Small solid iron particles containing
trivalent iron, which are suspended in water and visible as "rusty
water". Ferric iron can normally be removed by filtration.
Also known as precipitated iron.
ferrous iron: A divalent iron ion, usually as
ferrous bicarbonate which when dissolved in water produces a clear
solution. It is usually removed by cation exchange water softening.
Also called clear water iron.
filter: A device installed as part of the water
system through which water flows for the purpose of removing turbidity,
taste, color, iron or odor.
filter media: The selected materials in a filter
that form the barrier to the passage of filterable suspended solids
or dissolved molecules. Filter media are used to remove undesirable
materials, tastes and odors from a water supply.
filtrate: The effluent liquid from a filter
system; that part of the feed stream which has passed through
the filter.
filtration: The process of separating solids
from a liquid by means of a porous substance such as permeable
fabric or membrane or layers of inert media.
fines: Extremely small particles which are smaller
than the specified size (in millimeters) for the medium.
flow controller: An in-line device or orfice
fitting which regulate and control flow of water.
flow rate: The quantity of water which=h passes
a given point in a specified unit of time, offen expressed in
U.S. gpm (or L/min).
fluoridation: The addition of fluoride compound
to a potable water supply to produce the concentration desired
(about one PPM) for the purpose of the reduction of dental caries
(tooth decay).
fluoride: A natural occurring constituent of
some water supplies, an excess of which (over 2.0ppm) can cause
discolored teeth.
fouling: (filtration): The accumulation of undesirable
foreign matter in a filter causing clogging of pours coating of
surfaces and inhibiting or limiting the proper operation of the
treatment system.
fouling (reverse osmosis): A phenomenon in which
a reverse osmosis membrane adsorbs, interacts with or becomes
coated by solutes and or precipitates in the feed stream resulting
in a decrease in membrane performance by lowering the flux and
/or affecting the rejection solutes.
free available chlorine (FAC): The concentration
of residual chlorine present as dissolved gas, hypochlorous acid
or hypochlorite ion but not including that chlorine combined with
ammonia or other less readily available forms of chlorine.
fresh water: water having less than approximately
1,000 mg/L (ppm) of total dissolved solids (TDS).
fungi: (singular = fungus) Plantlike organisms
with cells that have distinct nuclei surrounded by nuclear membranes
as well as other specialized functional cell parts but that cannot
carry photosynthesis. Most fungi are decomposers of wastes and
dead bodies from other organisms; a few are parasites. Yeasts,
molds, mildew and mushrooms are all fungi.
G
Gallinea ferruginea: One of several types of
bacteria that use iron in their metabolism and are capable of
depositing gelatinous ferric hydroxide. Also known as iron bacteria.
germicidal ultraviolet: An ultraviolet light
that peaks at a 2,537 angstrom wavelength and is in a wavelength
that lies between 200 and 300 nanometers. This is known as the
germicidal or short-wave ultraviolet band.
giardia: A common waterborne protozoan that
forms cysts and is resistant to disinfectants such as chlorine
and ultraviolet light. Giardia can be removed by filters that
all particles of four microns and greater in size.
Giardia lamblia: A type of cyst found in the
intestines of mammals and in water contaminated by mammal droppings.
The giardia lamblia cyst, which is common and is frequently carried
by water, is capable of causing a contagious waterborne disease
characterized by acute diarrhea. This disease is referred to as
beaver fever, because beaver droppings can contain giardia lamblia.
groundwater: Water found beneath the surface
of the ground. Ground water is primarily water which has seeped
down from the surface by migrating through the interstitial spaces
in soils and geologic formations.
H
H20: The chemical formula for water (dihydrogen
oxide).
half -life: The time required for half of the
substance present at the beginning to dissipate or disintegrate.
halogens: A family group pf elements including
bromine, chlorine, fluorine, astatine and iodine.
hardness: A common quality of water which contains
dissolved compounds of calcium and magnesium and sometimes other
divalent and trivalent metallic elements.
health contaminant: Any substance or condition
that may have any adverse effect on human health.
heterotrophic plant count (HPC): A procedure
for estimating the total number of live non photosynthetic bacteria
in water. Colony forming units (CFU) are counted after spreading
the sample over a membrane or spread plate and incubating in an
amiable growth medium (agar) and at an amiable temperature. These
are generally not considered disease-causing bacteria.
hexametaphosphate: A chemical such as sodium
hexametaphosphate, added to water to increase the solubility of
certain ions and to deter precipitation of certain chemicals.
hydrostatic test: A pressure test procedure
in which a vessel or system is filled with water, purged of air,
sealed , subjected to water pressure and then observed and/or
tested for leaks, distortion and/or mechanical failure.
I
influent: The stream of water to be treated
as it flows into any kind of water treatment unit or device, such
as hard water into a water softener or turbid water into a filter.
inorganic matter: Chemical substances which
do arise from the process of living growth, are composed of matter
other than plant or animal matter. And don't contain hydrocarbons
of compounds basically carbon structure. Examples are minerals
and metals.
installation: The connecting or setting up and
start up operation of any water treatment system.
iodine (I): A nonmetallic element which is the
heaviest and least reactive of the naturally occurring halogens.
It may be use for disinfection. In both its liquid and vapor forms,
iodine is readily adsorbed by activated carbon.
ion exchange: A reversible chemical process
in which ions from an insoluble permanent solid medium (the "ion
exchanger" usually resin) are exchanged for ions in a solution
or fluid mixture surrounding the insoluble medium.
iron (Fe): A very common element often present
in groundwater in amounts ranging from 0.01 to 10.0 ppm (mg/L)
Iron can be found in three forms
1. Soluble form as in ferrous bicarbonate.
2. Bound with a soluble organic compound
3. As suspended ferric iron particles
iron bacteria: Bacteria which thrives on iron
and are able to actually use ferrous iron (as found in water or
steel pipes) in their metabolic processes, to incorporate ferric
iron in their cell structure, and to deposit gelatinous ferric
hydroxide iron compounds in their life processes.
iron fouling: The accumulation of iron on or
within an ion exchange resin bed or filter medium in such amounts
that the capacity of the medium is reduced.
J
jackson turbidity unit (JTU): A formerly used
measurement of the turbidity in a water sample. This has been
replaced by the nephelometric turbidity unit (NTU).
K
kinetics: the study of the relationships between
temperature and the motion and velocity of very small particles.
Kinetic relationships influence the rate of change in a chemical
or physical system.
L
leach: To dissolve out by the action of a percolating
liquid.
leach field: The area where the effluent from
a septic tank system is distributed by horizontal underground
piping designed to aid in the process of natural leaching and
percolation through the soil.
Legionella: Over 26 species of bacteria, such
as Legionella pneumophila, which can cause pneumonia-like illness
called "Legioella Disease" (after the American Legion
convention at which the disease first drew attention). These bacteria
are known to thrive at 100 degrees F and are believed to live
in infected humidifiers, cooling tower water and shower rooms.
Infection is by inhalation.
lime (CaO): A calcined chemical material, calcium
oxide.
lime scale: Hard water scale formed in pipes
and vessels (generally more severe on the hot water side) containing
a high percentage of calcium carbonate (CaCO3) or magnesium carbonate
MgCO3).
longitudinal flow: A flow pattern in which water
travels from the bottom to top (or vice versa) in either a cartridge
or loose media tank-type filtration system. The advantages are
greater contact time, higher unit capacity, more complete utilization
of medium and more uniform water quality. Also called axial flow.
loop: A plumbing connection used to bypass water
around a location designed for installation of a water treatment
system or used when the treatment system is out of service for
any reason.
M
magnesium (Mg): one of the elements that make
up the earth's crust as part of many rock-forming minerals such
as dolomite. Magnesium and calcium dissolved in water constitutes
hardness. The presence of magnesium in water contributes to the
formation of scale and insoluble soap which identify hard water.
manganese (Mn): An element sometimes found dissolved
in groundwater usually in combination with - but in lower concentrations
than iron. Manganese is noticeable because in concentrations above
0.05mg/L it causes black staining of laundry and plumbing fixtures.
mechanical filter: A pressure or gravity filter
designed to physically separate and remove suspended solids from
a liquid by mechanical (physical) means rather than by chemical
means.
media: A selected group of material used in
filters and filter devices to form barriers to the passage of
certain solids or molecules which are suspended or dissolved in
water.
membrane: A thin sheet or surface film, either
natural or man-made of microporous structure that performs as
an effluent filter of particles down to the size range of chemical
molecules and ions. Such membranes are termed "semipermeable"
because some substances will pass through but others will not.
mesh size: Mesh is the number of openings in
a square inch of a screen or sieve. It is equal to the square
of the number of strains of metal or plastic screening per lineal
inch.
methane: A colorless, odorless, flammable gas
consisting of the hydrocarbons (CH4) and resulting from the decay
of vegetable matter or manure due to the action of anaerobic bacteria
in swampy land, closed landfills or sewage disposal plants.
microbicide: A substance that destroys microorganisms.
microfiltration: The separation or removal from
a liquid of particles and microorganisms in the size range of
0.1 to 2.0 microns in diameter.
micrograms per liter: Considered as equal to
parts per billion (ppb). The common symbol for micrograms per
liter is ug/L.
micrometer: see micron.
micron: A metric unit of length equal to one
millionth of a meter or one thousandth of a millimeter or about
0.00003937 inches. The symbol for micron is the Greek letter u.
micron rating: A measurement applied to filters
or filter media to indicate the particle size at which suspended
solids above that size will be removed. As used in the water treatment
industry standards, this may be an absolute rating or a nominal
rating.
micronutrient: see trace element.
microorganism: A living organism invisible or
barely visible to the naked eye and generally observed only through
a microscope. Also called a microbe. Microorganisms are generally
considered to include algae, bacteria, fungi, protozoa and viruses.
microwatt-seconds per square centimeter: A unit
of measurement of intensity and retention or contact time in the
operation of ultraviolet systems.
mineral: An inorganic (non-living) substance
which occurs naturally in the earth and has a composition that
can be expressed as a chemical formula and a set of characteristics
(crystalline structure, hardness etc.) common to all minerals.
Examples of minerals are sulfur, salt and stone.
mineral free water: Water produced by either
distillation or deionization. This term is sometimes found on
labels of bottled water as a substitute term for distilled or
deionized water.
mineral water: Water which is naturally or artificially
impregnated with mineral salts or gases (carbon dioxide). The
term is also used to designate bottled water that contains no
less than 250 ppm total dissolved solids (TDS) and originates
from a protected ground water source.
mixed bed: The intermix of two or more filter
exchange products in the same vessel during a service run.
mixed media: The use of two or more media products
in a single filtration loose media bed where the products are
intermixed - rather than in stratisfied layers. For example the
intermix use of calcite and magnesia in pH modification.
module: The membrane element and its housing
in a reverse osmosis unit.
molecule: The smallest particle of an element
or compound that retains all of the characteristics of the element
or compound. A molecule is made up of one or more atoms.
monitoring light sensor: An indicator light,
electrically or electronically activated, which is positioned
in the effluent (product water) stream of a piece of water treatment
equipment to detect and signal changes in the water quality which
might malfunction of the equipment.
municipal water: Water that has been processed
at a central plant to make it potable or "safe to drink"
and which is then distributed to homes and businesses via water
mains. The term is a general one used to refer to the common source
of water in most urban and suburban areas - as opposed to water
obtained from separate proprietary sources such as private wells.
N
nanofiltration: A membrane treatment process
which falls between reverse osmosisand ultra filtration on the
filtration/separation spectrum.
naturally soft water: Ground surface, or rain
water sufficiently free of calcium and magnesium salts so that
no curd will form when soap is used and no calcium or magnesium
based scale will form when the water is heated.
natural sparking water: Carbonated water whose
carbon dioxide content is from the same source as the water itself.
neutral: (water chemistry) The midpoint (neutral)
reading of 7.0 on the pH scale, indicating that the solution (water)
producing the neutral reading will produce neither an acid nor
alkaline reaction. A 7.0 reading on the pH scale means that there
are an equal number of free hydrogen (acidic) ions and hydroxide
(basic) ions.
nitrate: A natural nitrogen compound sometimes
found in well or surface waters. In high concentrations, nitrates
can be harmful to young infants.
|
nominal filter rating: Filter rating indicating
the approximate size particle, the majority of which will not
pass through the filter. It is generally interpreted as meaning
that 85% of the particles of the size equal to the nominal filter
rating will be retained by the filter.
non degradable: Resistant to decomposition or
decay by biological means such as bacteria action or by chemical
means such as oxidation, heat, sunlight or solvents.
nonpathogenic: Not disease producing.
normal flow filtration: The flow of the entire
feed water stream in one direction directly through the filter
media.
not detectable: A term used in reporting test
results to mean that the substance being tested cannot be detected
by the equipment or method being used for this particular test.
This term implies that it is possible that trace amounts may be
present in quantities to small to be detected by the test equipment
or method.
NTU: nephelometric turbidity unit.
nucleus: The positively charges central part
of an atom containing nearly all of the atomic mass a consisting
of protons and neutrons (except in hydrogen which consist of one
proton only).
nutrients: Elements or compounds essential as
raw materials for organism growth and development.
O
operating pressure: The manufacture's specific
range of pressure expressed in pounds per square inch (psi) within
which a water processing device or water system is designed to
function. A range of 30 to 100 psi is often indicated. Also called
working pressure.
operating temperature: The manufacturer's recommended
feed water or inlet water temperature for a water treatment system.
organic: Having the characteristics of or being
derived from a living organism, plant and animal. Containing carbon
(although a few very simple carbon compounds such as carbon oxides,
the carbides, carbon disulfides and metallic carbonyls and carbonates
are considered inorganic).
organic matter: Substances consisting of or
derived from plant or animal matter, as opposed to inorganic matter
which is derived from rocks, ore and minerals. Organic matter
is characterized by its carbon hydrogen structure.
orfice: An opening, such as a hole or vent in
something.
osmosis: The natural tendency for water to spontaneously
pass through a semipermeable membrane separating two solutions
of different concentrations (strength). The water will naturally
pass from the weaker (less concentrated) solution containing fewer
particles of dissolved substance to the stronger (more concentrated)
solution containing more particles of a dissolved substance. Thus
natural osmosis causes the stronger solution to become more diluted
and tends to equalize the strength of the solution on both sides
of the membrane.
osmotic pressure: The pressure and potential
energy difference which exists between two solutions on either
side of a semipermeable membrane because of the tendency of water
to flow in osmosis.
oxidizing agent: A chemical substance that
gains electron (is reduced) and brings about the oxidation of
other substances in chemical oxidation and reduction (redox) reactions.
ozonation: The process of feeding ozone into
a water supply for the purpose of decolorization, deodorization,
disinfectant or oxidation.
ozone (03): A very strong oxidizing agent which
is unstable and must be generated on site. Ozone is a highly reactive
form of oxygen and can be produced by sending a high voltage electrical
discharge through air or oxygen (such as occurs in a lightening
storm). Ozone can also be produced by some types of ultra violet
lamps. Ozone is an excellent oxidizing agent and bactericide.
P
particle: A very tiny, separate subdivision
matter.
particle filtration: Filtration of particles
in the size range of 2 microns or larger in diameter. Particle
filtration is typically handled by cartridge filters and media
filters.
particle size: As used in water industry standards,
this term refers to the size expressed in microns, of a particle
suspended in water as determined by the smallest dimension.
parts per billion (ppb): A measure proportion
by weight which is equivalent to one unit weight of solute (dissolved
substance) per billion unit weights of the solution.
parts per million (ppm): A measure of proportion
by weight which is equivalent to one unit of weight of solute
(dissolved substance) per million weights of solution. Since one
liter of water weighs one million milligrams, one ppm is equal
to one milligram per liter (mg/L). PPM is the preferred unit of
measure in water or wastewater analysis.
pathogens: Any disease producing organism.
pathogenic: Capable of causing disease.
percent recovery: The percentage of the feed
water which becomes product water. Determined by the number of
gallons (or liters) of product water divided by the total gallons
(or liters) of feed water and multiplied by100. The percent recovery
is called recovery rate in reverse osmosis and ultra filtration.
percent rejection: (reverse osmosis/ultra filtration)
The percentage of TDS in the feed water that is prevented from
passing the membrane with the permeate. The formula used is: the
difference obtained from the TDS in permeate divided by TDS in
feed water; then multiply the answer obtained by 100 to obtain
a percentage.
permeate: That portion of the feed water which
passes through the membrane to become product water.
pH (potential of hydrogen): A measure of the
degree of the acidity or the alkalinity of a solution as measured
on a scale ("pH scale") of 0 to 14. The midpoint of
7.0 on pH scale represents neutrality, that is, a neutral solution
is neither acid nor alkaline. Numbers below 7.0 indicate acidity;
numbers above 7.0 indicate alkalinity. It is important to understand
that pH is a measure of intensity, not capacity. That is, pH indicates
the intensity of alkalinity in the same way temperature tells
how hot something is but not how much heat the substance carries.
phosphate: A salt of phosphoric acid. In the
water treatment industry, poly phosphates are used a sequestering
agents to control iron and hardness, and as a coating agent to
control corrosion by formation of a thin passivating film on metal
surfaces.
POE: Point of entry.
point of entry (POE) treatment: Full service
water treatment at the inlet to an entire building or facility
(outside faucets may be excepted from treatment).
point of use (POU) treatment: Water treatment
at a single outlet or limited number of water outlets in a building,
but for less than the whole building or facility. POU treatment
is often used to treat water for drinking and cooking only.
polishing filter: A filter installed for use
after the primary water treatment stage to remove any trace of
undesirable matter or to polish the water.
pollutant: A contaminant existing at a concentration
high enough to endangered the environment or the public health
or to be otherwise objectionable.
polyphosphate: A form of phosphate polymer consisting
of a series of condensed phosphoric acids containing more than
one atom of phosphorous. Polyphosphate is used as a sequestering
agent to control iron and hardness, and as a coating agent that
forms a thin passivating film on metal surfaces to control scale.
porous: Full of pores through which water, light
etc may pass.
porosity: A measure of the volume of pores in
a material. Porosity is calculated as a ration of the interstices
of material (e.g. the volume of spaces between the media particles
in a filter bed) to the volume of its mass, and is expressed as
a percentage.
potable (drinking) water: A water supply which
meets U.S. EPA and/or state water quality standards and is considered
safe and fit for human consumption.
potassium chloride (KCl): A colorless potassium
salt which can be used as a regenerant in cation exchange water
softeners.
POU: Point of use.
pounds per square inch (psi): unit of measure
for expressing pressure.
ppb: Parts per billion.
ppm: Parts per million.
ppt: Parts per trillion.
pretreatment: Any water treatment step performed
prior to the primary treatment process, such as filtration prior
to deionization.
pressure differential: The difference in the
pressure between two points is a water system. The difference
may be due to the difference in elevation and/or to pressure drop
resulting from water flow.
pressure drop: A decrease in the water pressure
(in psi) which occurs as the water flows. The difference between
the inlet and outlet water pressure during water flow through
a water treatment device.
process water: Water used in a manufacturing
or treatment process or in the actual product manufacture.
production rate: The amount (gallons or liters)
of product water the system produces per minute or (especially
for reverse osmosis) per 24 hour period.
product water: Water that has been through the
total treatment process and meets the quality standards required
for the use to which the water will be used.
prototype: an original water treatment equipment
unit on which a specific equipment line is modeled.
protozoa: Microscopic, usually single celled
microorganisms which live in water and are relatively larger in
comparison to other microbes. Protozoa are higher on the food
chain than the bacteria that they eat. Many protozoa are parasitic.
psi: Pounds per square inch.
pure water: This term has no real meaning unless
the word "pure" is defined by some standard such as
pharmaceutical grade water.
purified water: A USP grade water produced from
water meeting U.S. EPA standards for potable drinking water which
has microbiological content under control and is free from foreign
substances.
putrefaction: The decomposition (rotting) of
organic matter caused by microbes and oxidation.
pyrogens: Substances (often of unknown origin)
that produce fever when introduced into the human body. Being
chemically and physically stable, pyrogens are not necessarily
destroyed by conditions that kill bacteria
Q
qualification test: Test and verifications performed
to validate water treatment equipment conformance to a specific
standard.
quartz sleeve or quartz jacket: A clear, pure
fused quartz tube used to protect the high intensity ultraviolet
lamps in ultraviolet systems. It usually retards less than 10%
of the ultraviolet radiation dose.
R
radial flow: The flow pattern in which water
flows from the outside of a filter element to the center core.
radical: A group of atoms acting as a single
atom which go through chemical reactions without being changed.
radon (Rn): A colorless, odorless, short lived
radioactive gas which is produced by decay of the uranium/radium
series and is soluble in water. Radon is considered carcinogenic
when inhaled by humans. Radon can be removed from water by aeration
or activated carbon.
rated capacity (filtration or adsorption): The
manufacturer's statement regarding the expected number of days
the equipment will be in service or the expected number of gallons
of product water is delivered before backwash, rinse or replacement
is needed.
rated pressure drop: The expected pressure drop
in psi as stated by the equipment manufacturer or obtained under
test conditions.
rated flow rate: The specified maximum and minimum
flow rate at which a particular piece of water treatment equipment
will continuously produce the desired quality of water.
raw water: Water, usually from wells or surface
sources, which has had no previous treatment and is entering the
water processing system or device. The water at the inlet side
of any water treatment device.
redox: A shortened term for "oxidation-reduction".
Used in terms such as redox reactions and redox conditions.
regeneration (ion exchange, softening): The
use of a chemical solution (regenerant) to displace the contaminant
ions deposited on the ion exchange resin during the service run
and replace them with the kind of ions necessary to restore the
capacity of the exchange medium for reuse.
reject water: A term used in distillation, reverse
osmosis and ultra filtration to describe that portion of the incoming
feed water that has passed across the membrane but has not been
converted to product water and is being sent to drain.
rejection rate: In a reverse osmosis or ultra
filtration system, rejection rate is the quantity of feed water
that does not pass through the membrane expressed as a percent
of the total quantity of incoming fed water.
removable: capable of being taken away from
a water treatment equipment unit using only simple tools such
as a screw driver, pliers, or open ended wrench. Readily removable
indicates capable of being taken away from a water treatment unit
without the use of tools.
reservoir tank: Same as storage tank on a reverse
osmosis system.
residential equipment: The term sometimes used
to denote smaller sized water processing equipment which has been
designed primarily for home use.
residual: The amount of a specific material
which remains in the water after the water has been through water
treatment step.
residual chlorine: Chlorine allowed to remain
in a treated water after a specified period of contact time and
allowed to provide disinfection protection through out the distribution
system. The amount of residual chlorine is the difference between
the total chlorine added and that consumed by the oxidizable matter.
resin: As used in the water processing industry,
this term refers to ion exchange resin products which are usually
specifically-manufactured organic polymer beads used in softening
and other ion exchange processes to remove dissolved salts from
water.
retention: Contact time.
reverse osmosis (RO): A water treatment process
that removes undesirable materials from water by using pressure
to force the water molecules through a semipermeable membrane.
This process is called "reverse" osmosis because the
pressure forces the water to flow in the reverse direction (from
the concentrated solution to the dilute solution) to the flow
direction (from the dilute to the concentrated) in the process
of natural osmosis. RO removes ionized salts, colloids and organic
molecules down to a molecular weight of 100.
rust (ferric oxide): A reddish corrosion product
occasionally found in water. Rust is formed as a result of electrochemical
interaction between iron and atmospheric oxygen in the presence
of moisture.
S
safe water: see potable water.
saline: Consisting of, or containing salt.
salt water: The general term for all water over
1,000 ppm (mg/L) total dissolved solids.
sand filter: The oldest and most basic filtration
process, which generally uses two grades of sand (coarse and fine)
for turbidity removal or as a first stage roughing filter or pre-filter
in more complex processing systems.
scale: A coating or precipitate deposited on
surfaces such as kettles, water pipes or steam boilers that are
in contact with hard water. Waters that contain carbonates or
bicarbonates of calcium or magnesium are especially likely to
cause scale when heated.
scavenger: (water treatment) A polymer matrix
or ion exchanger that is used specifically to remove organic species
from the feed water before the water is to pass through the deionization.
screen size: SEE mesh size.
SDI: Silt density index.
selectivity: The tendency of an ion exchanger
to "prefer" (have more attraction for) certain kinds
of ions over others, as if the resin were ranking the types of
ions in order to be removed; most preferred ion, second most preferred,
etc..
septic: Producing or characterized by bacterial
decomposition.
serial filtration: The arrangement of two or
more filtering steps, one following the other, in order to remove
increasingly finer particles at each stage and provide for filtration
of all sizes of suspended solids.
service flow: The rate in U.S. gallons per minute
(gpm) or liters per minute (L/min) at which a given water processing
system can deliver product water. The rating may be intermittent
peak flow or constant flow.
shallow well: A well sunk in easily penetrated
ground to a point which is below the water table but usually less
than about 30 feet in depth.
silt density index (SDI): A test used to measure
the level of suspended solids in feed water for membrane filtration
systems.
single stage system: A filtering system that
uses only a single filtering cartridge.
slug: A temporary abnormally high concentration
of an undesirable substance which shows up in the product water.
slurry: A thin watery mixture of a very fine
insoluble substance.
soda water: water which has impregnated with
carbon dioxide (CO2)so that it will be effervescent when not under
pressure. Same as seltzer water.
sodium: (Na+): A metallic element found abundantly
in compounds in nature, but never existing alone.
sodium chloride (NaCl): The chemical name for
common table salt.
soft water: Any water which normally contains
less than 1.0 grain per gallon (17.1 mg/L or ppm) of total hardness
expressed as calcium carbonate equivalent.
softened water: Any water which has been processed
in some manner to reduce the total hardness to 17.1 mg/L or ppm
(1.0 grain per gallon) or less expressed as calcium carbonate
equivalent.
solids: The matter dissolved or suspended in
water or wastewater.
spiral wound: A very common construction configuration
for one style of reverse osmosis membrane and cartridge filter
element. In RO membranes, the membrane sheets are assembled in
layers around a perforated mandrel product water tube with coarse
mesh spacers screens between the layers, to form a complete module
element. In cartridge filter elements, the filtration material
such as fiber cord, is continually would around a perforated mandrel
core tube.
spore: A small reproductive body, often single
celled, capable of reproducing the organism under favorable conditions.
The spore is sometimes considered the resting stage of the organism.
Among the organisms that may produce spores are algae, bacteria
and certain protozoan. In water, most spores resist adverse conditions
which would readily destroy the parent organism.
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