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A
method of crossflow filtration (similar
to reverse osmosis but using lower pressures)
which uses a membrane to separate small
colloids and large molecules from water
and other liquids. The ultrafiltration
process falls between reverse osmosis
and microfiltration in terms of the
size of particles removed, with ultrafiltration
removing particles in the 0.002 to 0.1
micron range, and typically rejecting
organics over 1,000 molecular weight
while passing ions and smaller organics. |
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ULTRAPURE
WATER : |
Highly-treated
water that is deionized and mineral-free
with high resistivity and no organics;
it is usually used in the semiconductor
and pharmaceutical industries. Ultrapure
water is NOT considered biologically
pure (potable) or sterile. There is
no set numerical standard to determine
exactly what "ultrapure" water
is or should be. |
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ULTRAVIOLET
(UV) : |
Pertaining
to ultraviolet light. |
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ULTRAVIOLET
(UV) LIGHT : |
Radiation
(light) having a wavelength shorter
than 3900 angstroms the wavelengths
of visible light, and longer than 100
angstroms, the wavelengths of x-ray's.
This wavelength puts ultraviolet light
at the invisible violet end of the light
spectrum. Ultraviolet light is used
as a disinfectant. |
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ULTRAVIOLET
ABSORBER : |
Substances
which absorb ultraviolet radiation (light).
ultraviolet absorbers are added to plastic
(such as used in plastic tanks and fittings)
and rubber products to make them less
likely to decay as the result of absorbing
ultraviolet rays. |
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ULTRAVIOLET
CHAMBER : |
The
area where the water is irradiated with
ultraviolet rays. |
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ULTRAVIOLET
DEMAND : |
The
amount of ultraviolet rays required
to inactivate certain microorganisms. |
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ULTRAVIOLET
DOSAGE : |
The
amount of disinfectant ultraviolet rays
delivered to the organisms in the water
being disinfected. Dosage is a combination
of UV intensity times the contact time
and is measured in watt-seconds per
square centimeter. |
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Ultraviolet
Rays : |
Radiation
from the sun that can be useful or potentially
harmful. UV rays from one part of the
spectrum enhance plant life and are
useful in some medical and dental procedures;
UV rays from other parts of the spectrum
to which humans are exposed (e.g., while
getting a sun tan) can cause skin cancer
or other tissue damage. The ozone layer
in the atmosphere provides a protective
shield that limits the amount of ultraviolet
rays that reach the Earth’s surface. |
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UNIFORMITY
COEFFICIENT : |
The
measure of the variation in particle
sizes of filter and ion exchange media.
The uniformity coefficient is defined
as the ratio of the sieve size that
will permit passage of 60 percent of
the media material by weight to the
sieve size that will permit passage
of 10 percent of the media material
by weight. A uniformity coefficient
of 1.00 denotes a material having particle
grains all the same size; numbers increasingly
greater than one denote increasingly
less uniformity. |
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UNIVALENT
: |
Having
a valence of one. Also called monovalent. |
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UPFLOW
: |
-
A pattern of water flow in which a solution
(water or regenerant usually) enters
at the bottom of the vessel or column
and flows out at the top of the vessel
or column during any phase of the treatment
unit’s operating cycle. The term
is used to describe ion exchange system
flow patterns or water flow through
filter media. A system can have upflow
during the treatment cycle and downflow
during regeneration. Upflow is also
called countercurrent flow. Countercurrent
flow means regeneration flows and service
flows are in the opposite directions.
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UPFLOW
SOFTENING : |
A
pattern of water flow used in softeners
in which the service water flows upward
through the ion exchange bed; the media
is restricted in movement, usually because
of a packed bed. The regeneration brine
usually flows downward in such systems.
Upflow softening is normally used to
achieve higher operating efficiency. |
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UPPER
DISTRIBUTIOR : |
The
piping arrangement inside and at the
top of softeners and filters to more
uniformly distribute the incoming water
over the resin or filter media bed.
In small domestic units, this distributor
also distributes the brine for regeneration. |
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URANIUM
(U) : |
A
radioactive metallic element found naturally
only in combination with other substances.
Uranium 238 (U-238) is the most common
form, but about 0.7 percent of natural
uranium is present as U-235, which is
the important fissionable component
in work with atomic enemy. Uranium in
natural water exists as anionic complexes
UO2(CO3)22- and UO2(CO3)34-. |
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-
A mechanical device which automatically
vents a water line to the atmosphere
when subject to a partial vacuum, thus
preventing back siphonage. |
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VALIDATION
: |
1.
(water treatment industry) Determination
upon testing that a representative sample
of a water treatment equipment model
has met the requirements of a specified
standard. |
2.
(pharmaceutical industry) The requirement
of certain quality control testing and
record keeping procedures to ensure
compliance not only with a specific
quality but also with a specific means
to achieve and encore that quality. |
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VIRUS
: |
A
parasitic infectious microbe, composed
almost entirely of protein and nucleic
acids, which can cause disease(s) in
humans. Viruses can reproduce only within
living cells. They are 0.004 to 0.1
microns in size, and about 100 times
smaller than bacteria. |
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VISCOSITY
: |
The
tendency of a fluid to resist flowing
due to internal forces such as the attraction
of the molecules for each other (cohesion)
or the friction of the molecules during
flow. Viscosity varies with water temperature. |
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VOCs
: |
volatile
organic chemicals. |
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VOID
VOLUME : |
The
volume occupied by the interstitial
spaces between the particles of ion
exchangers, filter media, or other granular
materials in a bed or column. Often
expressed as percent of the total volume
occupied by the medium bed. |
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VOLATILE
: |
Capable
of becoming vapor at relatively low
temperatures. |
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VOLATILE
ORGANIC CHEMICALS (VOCs) : |
Organic
chemicals that turn into vapor at relatively
low temperatures. |
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Volatile
Organic Compound (VOC) : |
Any
organic compound which participates
in atmospheric photochemical reactions
except for those designated by the EPA
Administrator as having negligible photochemical
reactivity. |
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A
facility containing a series of tanks,
screens, filters and other processes
by which pollutants are removed from
water. |
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Waste
Treatment Stream : |
The
continuous movement of waste from generator
to treater and disposer. |
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WASTE
WATER : |
Water
that has been used. 1. (RO, ultrafiltration,
electrodialysis) The stream of water
(not product water) created as the result
of processing water-the reject water
or concentrate. 2. (ion exchange and
filtration) The spent water used in
the total backwash and/or regeneration
cycle. 3. The used water and solids
from a residence or a community (including
used water from industrial processes)
that flow to a septic system or a treatment
plant. Storm water, surface water, and
groundwater infiltration also may be
included in the waste water that enters
a waste water treatment plant. The term
sewage usually refers to household wastes,
but this word is being replaced by the
term waste water. |
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WATER
(H2O) : |
An
odorless, colorless, tasteless liquid
which exists as ice in solid form (phase)
and steam in vapor form (phase). It
freezes at 32°F (0°C) and boils
at 212°F (100°C). Water is a
polar squid with high dielectric constant
which accounts for its solvent power,
it is called the universal solvent.
It is a weak electrolyte; in pure water,
only about two molecules in every 1,100,000,000
separate into H3O+ and OH- ions. Water
is only slightly compressible. It is
the liquid that descends from the clouds
as rain and forms lakes, streams, and
seas (oceans). Water is a major constituent
of all living matter. Also referred
to as H2O (dihydrogen oxide) and HOH
(hydrogen hydroxide). |
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WATER
RETENTION : |
The
amount of water, expressed as a percent
of the wet weight of an ion exchanger,
retained within the resin bead and on
the surface of fully swollen and drained
ion exchange media. Also called water
regain. |
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WATER
SOFTENER (CHEMICAL) : |
A
compound which, when introduced into
water used for cleaning or washing,
will counteract the effects of the hard
water minerals (calcium and magnesium)
and produce the effect of softened water.
For example, detergent additives and
polyphosphates. |
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WATER
SOFTENER (MECHANICAL) : |
A
pressurized water treatment device in
which hard water is passed through a
bed of cation exchange media (either
inorganic or synthetic organic) for
the purpose of exchanging calcium and
magnesium ions for sodium or potassium
ions, thus producing a softened water
which is more desirable for laundering,
bathing, and dishwashing. This cation
exchange process was originally called
zeolite water softening or the Permutit
Process. Most modern water softeners
use a sulfonated bead form of styrene/divinylbenzene
(DVB) cation resin. |
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WATER
SOFTENER SALT : |
Salt
suitable for regenerating residential
and commercial cation exchange water
softeners. Most commonly used for this
purpose is sodium chloride (NaCl) in
crystal or pelletized form. Rock grade
salt should be 96-99 percent NaCl; evaporated
salt should be 99+ percent NaCl. Potassium
chloride (KCl) may also be used for
the regeneration cycle in the cation
exchange process, thus minimizing the
amount of sodium added to both the softened
water and the spent regenerant water
going to the drain. |
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WATER
SOFTENING : |
The
reduction/removal of calcium and magnesium
ions, which are the principal cause
of hardness In water. The cation exchange
resin method is most commonly used for
residential and commercial water treatment.
In municipal and industrial water treatment,
the process can be lime softening or
lime-soda softening. |
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WATER
TREATMENT DEVICE : |
Any
point-of-use or point-of-entry instrument
or contrivance sold or offered for rental
or lease for residential use, and designed
to be added to the plumbing system,
or used without being connected to the
plumbing of a water supply intended
for human consumption in order to improve
the water supply by any means, including,
but not limited to, filtration, distillation,
adsorption, ion exchange, reverse osmosis,
or other treatment. |
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WBA
: |
Weak
base anion exchanger. |
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WEAK
ACID CATION EXCHANGERS : |
Those
cation exchange products with functional
groups which, in the hydrogen form,
are not capable of splitting neutral
salts to form their corresponding free
acids. Weak acid cation exchange resins
have a much higher (three to four times
higher) regeneration efficiency than
their strong acid counterparts, but
in the hydrogen form can only exchange
cations that are associated with alkalinity.
The cations associated with sulfates,
chlorides, and nitrates, for example,
cannot be removed with weak acid cation
exchanger in the hydrogen form. Hydrogen
form weak acid cation exchangers that
have been neutralized with sodium hydroxide
to the sodium form, however, can effectively
remove both carbonate and noncarbonate
water hardness cations; thus weak acid
cation resins can be used to soften
wafers that, because of high total dissolved
solids, are not possible or practical
to treat with strong acid cation resins. |
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WEAK
BASE ANION EXCHANGERS : |
Those
anion exchange products with functional
groups which are not capable of splitting
neutral salts to form corresponding
free bases, Weak base anion exchange
resins have a much higher (three to
four times higher) regeneration efficiency
than their strong base counterparts,
but can only exchange mineral acid anions
such as sulfate, chloride, and nitrate.
The anions associated with weak acids,
such as carbonates, bicarbonates, silicates,
and organic acids, for example, cannot
be removed with weak base anion exchange.
SEE ALSO free base form. |
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WEIR
: |
1.
A dam-like wall or plate placed in an
open channel and used to measure the
flow of water. The depth of the flow
over the weir can be used to calculate
the flow rate, or a chart or conversion
table may be used. |
2.
A wall or obstruction used to control
flow (from settling tanks and clarifiers)
to assure uniform flow rate and avoid
short-circuiting. |
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WFI
: |
Water
for Injection. |
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WHO
: |
World
Health Organization. |
|
|
l.
The amount of product water produced
by a water treatment process. |
2.
The quantity of water (expressed as
a rate of flow-GPM, GPH, GPD, or total
quantity per year) that can be collected
for a given use from surface or groundwater
sources. The yield may vary with the
use proposed, with the plan of development,
and also with economic considerations. |
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A
term formerly used for the removal of
calcium and magnesium hardness from
water by base exchange using natural
or synthetic zeolites. Since the introduction
of synthetic organic cation exchange
resins, the more correct term is cation
exchange softening. Zeolite softening
was also called base exchange. |
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ZEOLITES
: |
Hydrated
sodium alumina silicates, either naturally-occurring
mined products or synthetic products,
with ion exchange properties. Zeolites
were formerly used extensively for residential
and commercial water softening but have
been largely replaced by synthetic organic
cation resin ion exchangers of polystyrene
divinylbenzene substrate. Modified zeolites
such as manganese greensand and synthetic
manganese zeolites are still used as
catalyst/oxidizing filters for the removal
of iron, hydrogen sulfide, and manganese. |
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ZERO
DISCHARGE WATER : |
A
discharge limit applied to manufacturing
and commercial establishments in which
only normal human sanitary waste waters
may be discharged to the municipal sewerage
system. All other types of waste water,
such as that water used in manufacturing
processes, are not included in zero
discharge water; but they must be recycled,
and the resulting waste product from
such water must be taken to an alternate
and approved disposal facility. |
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ZERO
SOFT WATE : |
water
produced by the cation exchange process
and measuring less than 1.0 grain per
U.S. gallon (17. 1 ppm or 17. 1 mg/L)
as calcium carbonate. zeta potential-The
electrical potential which exists across
the interface of all solids and liquids.
The potential represents the difference
in voltage between the surface of the
diffuse layer surrounding a colloidal
particle and the bulk liquid beyond.
Also known as electrokinetic potential. |
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ZONE
OF AERATION : |
The
comparatively dry soil or rock located
between the ground surface and the top
of the water table. |
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ZONE
OF SATURATION : |
The
layer in the ground in which all available
interstitial voids (cracks, crevices,
holes) are filled with water. The level
of the top of this zone is the water
table. SEE ALSO water table. |
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ZOOPLANKTON
: |
Small,
usually microscopic animals (such as
protozoans), found in lakes and reservoirs. |
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Zooplankton
: |
Tiny
aquatic animals eaten by fish. |
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