- Activated
Carbon
- A granular material
usually produced by the roasting of cellulose base substances, such
as wood or coconut shells, in the absence of air. It has a very porous
structure and is used in water conditioning as an adsorbent of organic
matter and certain dissolved gases. Sometimes called "activated
charcoal".
- 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 for oxidation of matter such as iron, or to cause the release of
dissolved gases such as carbon dioxide from the water.
- Anion
Exchange
- An ion exchange
process in which anions in solution are exchanged for other anions.
Demineralization is an example.
- Backwash
- The process in
which beds of tiler or ion exchange media are subjected to a flow in
the opposite direction to loosen the bed and to flush suspended matter
collected on the media.
- Bacteria
- Unicellular microorganisms
which typically reproduce by cell division. Although usually classified
as plants, bacteria contain no chlorophyll.
- Bacteriostatic
- A feature of a
carbon filter that is supposed to inhibit the growth of bacteria within
the filter - usually by the addition of silver.
- Bed
- The ion exchange
or filter media in a column in a tank or operational vessel.
- Brackish
Water
- Water containing
more than 1000 mg/L of dissolved solids is generally considered to be
brackish.
- Brine
(RO)
- Same as reject
water. One of two streams of fluids generated by a reverse osmosis unit.
It contains the impurities removed from the feed water.
- Brine
(Softening)
- A strong solution
of salt(s), such as sodium chloride, and water used in the regeneration
of ion exchange water softeners but also applied to the mixed sodium,
calcium and magnesium chloride waste solution from regeneration.
- Capacity
- An expression of
the quantity of an undesirable material which can be removed by a water
conditioner between servicing of the media (ie. cleaning, regeneration
or replacement) as determined under standard test conditions. For ion
exchange water softeners, the capacity is expressed in grains of hardness
removal between successive regenerations and is related to the pounds
of salt used in regeneration. For filters, the capacity may be expressed
in the length of time or total gallons delivered between servicing.
- Cation
Exchange
- Ion exchange process
in which cations in solution are exchanged for other cations from an
ion exchanger.
- Coagulant
- A material, such
as alum, which will form a gelatinous precipitate in water and cause
the agglomeration of finely divided particles into larger particles
which can then be removed by settling and/or filtration.
- Coliform
Bacteria
- Coliforms are a
group of bacteria that are used as indicators of the potential presence
of pathogens, viruses or parasites in a sample. These microbes are defined
as a group of bacteria having specific properties including the ability
to grow at 35°C, in the presence of bile salts and able to ferment
lactose. Coliform bacteria are divided into two types: Total
& Fecal.
- Colloid
- Very finely divided
solid particles which will not settle out of a solution; intermediate
between a true dissolved particle and a suspended solid which will settle
out of solution. The removal of colloidal particles usually requires
coagulation to form larger particles which may be removed by sedimentation
and/or filtration.
- Contact
Time
- The length of time
water is in direct contact with activated carbon (RO) or chlorine. This
is a major factor in determining how effectively impurities will be
removed.
- Corrosion
- The destructive
disintegration of a metal by electrochemical means.
- Cycle
Time
- The amount of time
in seconds elapsed between pump start and pump shut-down.
- Dechlorination
- The removal of
excess chlorine residual, often after super-chlorination.
- Deionization
(DI)
- The removal of
all ionized minerals and salts (both organic and inorganic) from a solution
by a two-phase ion exchange procedure. First, positively charged ions
are exchanged from a chemically equivalent amount of hydrogen ions.
Second, negatively charged ions are removed by an anion exchange resin
for a chemically equivalent amount of hydrogen ions. The hydrogen and
hydroxide ions introduced in this process unite to form water molecules.
The term is often used interchangeably with demineralization.
- Disinfection
- A process in which
pathogenic, disease producing bacteria are killed. May involve disinfecting
agents such as chlorine or physical process such as heating.
- Dissolved
Solids
- The weight of matter
in true solution in a stated volume of water. Includes both inorganic
and organic matter and is usually determined by weighing the residue
after evaporation of the water at 105 °F or 180 °C.
- Distillation
- The process in
which a liquid, such as water, is converted into its vapour state by
heating and the vapour cooled and condensed to the liquid state and
collected. Used to remove solids and other impurities from water. Multiple
distillations are required for extreme purity.
- Fecal
Coliform
- Fecal coliforms
are bacteria that are a normal part of feces of warm-blooded animals
and their presence would indicate an extreme risk that the water supply
could become (or is) contaminated with a pathogen such as an enteric
virus or parasite.
- Feed
Pressure
- The pressure at
which water is supplied to the RO module.
- Feed
Water
- Refers to the water
supply that is put into a water treatment system for processing.
- Flocculation
- The agglomeration
of finely divided suspended solids into larger, usually gelatinous,
particles. The development of a "floc" after treatment with
a coagulant by gentle stirring or mixing.
- Flow
Control
- A device designed
to limit the flow of water or regenerant to a predetermined value over
a broad range of inlet water pressures.
- Flow
Rate
- The quantity of
water or regenerant which passes a given point in a specific unit of
time, often expressed in gallons per minute.
- Flux
- The flow rate of
water through reverse osmosis membranes, per square foot of surface.
- Fouling
- The process in
which undesirable foreign matter accumulates in a bed of filter media
or ion exchanger, clogging pores and coating surfaces and thus inhibiting
or retarding the proper operation of the bed.
- Grains
per Gallon (gpg)
- A common basis
for reporting water analyses in the US and Canada. One grain per US
gallon equals 17.12 milligrams per liter (mg/L) or parts per million
(ppm).
- Greensand
- A natural mineral,
primarily composed of complex silicates, which can be coated with manganese
oxide to form a catalytic absorptive surface. This surface is used to
attract ferrous iron and manganese as well as to adsorb dissolved oxygen
which is used to oxidize iron, manganese or hydrogen sulfide.
- Hardness
- A characteristic
of natural water due to the presence of dissolved calcium and magnesium.
Water hardness is responsible for most scale formation in pipes and
water heaters and forms insoluble "curd" when it reacts with
soap. Hardness is usually expressed in grains per gallon (gpg).
- Hydrolysis
- The chemical degradation
of an RO membrane in water due to certain conditions such as high pH.
Cellulose based membranes are quite susceptible to hydrolysis while
the TFC type are virtually immune.
- Ion
- An atom, or group
of atoms, which function as a unit and have a positive or negative electrical
charge due to the gain or lose of one or more electrons.
- Ion
Exchange
- A reversible process
in which ions are released from an insoluble permanent material in exchange
for other ions in a surrounding solution; the direction of the exchange
depends upon the affinities of the ion exchanger for the ions present
and the concentrations of the ions in the solution.
- Iron
Bacteria
- Organisms which
are capable of utilizing ferrous iron, either from the water or from
steel pipe, in their metabolism and precipitating ferric hydroxide in
their sheaths and gelatinous deposits. These organisms tend to collect
in pipelines and tanks during periods of low flow and to break loose
in slugs of turbid water to create staining, taste and odour problems.
- Lactose
Fermentors - see Total Non-Coliforms
- Manganese
Greensand
- Greensand which
has been processed in incorporate in its pores and on its surface the
higher oxides of manganese. The product has a mild oxidizing power and
is often used in the oxidization and precipitation of iron manganese,
and/or hydrogen sulfide and their removal from water.
- Mechanical
Filtration
- The process of
removing suspended particles from water by a straining action. The finest
mechanical filters can remove bacteria as small as 0.2 microns.
- Milligrams
per Liter (mg/L)
- A unit of concentration
of matter used in reporting the results of water analyses. The preferred
unit of measure.
- Micron
- A micron (m)
is a metric unit of length equal to a millionth of a meter, or 0.00003937
inch. A human hair is approximately 75 m in diameter. The smallest
particle that can be seen with the naked eye is 40 m across The
smallest bacteria is about 0.22 m while a virus is even smaller
at 0.01 m.
- Micron
Rating
- The term applied
to a filter or filter medium to indicate the particle size above which
all suspended solids will be removed throughout the rate capacity.
- Osmosis
- A process of diffusion
of water through a semi-permeable membrane, which will transmit the
water, but impede most dissolved substances. The normal flow of water
is from the dilute solution to the concentrated solution.
- Osmotic
Pressure
- The pressure created
by the tendency of water to flow in osmosis. Every 100 PPM of TDS generates
about 1 psi of osmotic pressure. This osmotic pressure must first be
overcome by the water pressure for the reverse osmosis membrane to be
effective.
- Oxidation
- A chemical process
in which electrons are removed from an atom, ion or compound.
- Parts
per Million (PPM)
- Indicates the number
of parts by weight of a dissolved or suspended constituent, by weight
of water or other solvent. In dilute water, one PPM is practically equal
to one mg/L.
- pH
- A measure of the
intensity of the acidity or alkalinity of water on a scale from 0 to
14, with 7 being neutral.
- Precipitate
- To cause a dissolved
substance to form a solid particle which can be removed by settling
or filtering such as in the removal of dissolved iron by oxidation,
precipitation and filtration. The term is also used to refer to the
solid formed and the condensation of water in the atmosphere to form
rain or snow.
- Pre-treatment
- Alterations of
the raw feed water are required to prevent damage to the reverse osmosis
membrane.
- Product
Water
- The pure water
that has been separated from the feed water stream by the reverse osmosis
membrane.
- Recovery
- The amount of product
water as compared with the total amount of feed water. This will give
a measure of the efficiency of operation.
- Regenerant
- A solution of a
chemical used to restore the capacity of an ion exchange or oxidation
system.
- Regeneration
- Includes backwash,
brine and fresh water rinse steps necessary to prepare a water softener
exchange bed for service after exhaustion.
- Rejection
- The percentage
of TDS removed from the feed water. Typically greater than 90% rejection
is achieved with reverse osmosis.
- Residual
Chlorine
- Chlorine remaining
in treated water after a specified period of contact time to provide
protection throughout a distribution system.
- Resin
- Synthetic organic
ion exchange material such as the high capacity cation exchange resin
widely used in water softeners.
- Reverse
Osmosis (RO)
- A process that
reverses, by the application of pressure, the flow of water in the process
of osmosis so that the water passes from the more concentrated to the
more dilute solution through a semi-permeable membrane.
- Sediment
- The sum of particles
of dirt, clay, silt and vegetation which float or are suspended in water
and can be removed by mechanical filtration.
- Semi-permeable
- A term which applies
to special materials, both natural and synthetic, which allow certain
substances, such as water, to pass through (to permeate) while blocking
or rejecting the passage of other substances.
- Service
(Peak) Flow Rate
- The greatest amount
of water, in gallons per minute, that a particular filter can effectively
process.
- Soda
Ash
- The common name
for sodium carbonate, a chemical compound used in the lime soda ash
water conditioning process.
- Spiral
Wound
- The most common
practical configuration for a reverse osmosis membrane in which sheets
with large surface area are wrapped in a spiral fashion to fit in a
small space.
- Tannins
- A substance resulting
from the decomposition of lignin in vegetable matter.
- Total
Coliform
- Total coliforms
are bacteria that require complex organic nutrition and grow at elevated
temperatures. They are part of the microbial flora that makes a septic
field work or they may be found in environments with high biological
activity such as decomposing leaf-litter. Total coliform bacteria in
a water supply suggests that the supply is at significant risk for pathogen
or parasite contamination.
- Total
Dissolved Solids (TDS)
- The weight of solids
per unit volume of water which are in true solution.
- Total
Non-Coliforms or Lactose Fermentors
- Total non-coliforms
are bacteria that grow under the same restrictive conditions as the
coliform bacteria, but do not conform to the narrow definition of coliforms.
Elevated numbers of these organisms in a water supply (greater than
1.0 colony/milliliter in treated water or greater than 2.0 colony/milliliter
in raw water) are considered an unacceptable risk. These organisms are
bacteria capable of growing at body temperature and inhabit environments
with complex organic material. This group frequently contains enteric
bacterial pathogens.
- Total
Plate Count
- Is a measure of
the biological activity in a water sample. This a count of all (heterotrophic)
bacteria, fungi (molds) and yeast that will grow in aerobic or microaerophilic
conditions. This test is usually done at 35°C to estimate population
levels that are able to survive in or on humans.
- Trihalomethans
(THM's)
- A group of suspected
carcinogenic organic chemicals formed in water when chlorine reacts
with naturally occurring organic matter. One of the most common THM's
is chloroform.
- Turbidity
- Suspended biological,
inorganic and organic particles in water which may be in sufficient
amount to make the water seem cloudy.
- Water
Softening
- The removal of
calcium and magnesium, the ions which are the principal cause of hardness,
from water.
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