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R. O. |
The abbreviation for
"reverse osmosis". |
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Radionuclides |
Elements that undergo a
process of natural decay. As radionuclides decay, they emit radiation in
the form of alpha or beta particles and gamma photons. Radiation can cause
adverse health effects, such as cancer, so limits are placed on
radionuclide concentrations in drinking water. |
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Rated Capacity |
The basis for calculating
the period of time, or number of gallons delivered by a water softener,
filter, or deionizer, between regenerations or servicing, as determined
under specific test conditions. (See rated in-service life, rated softener
capacity.) |
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Rated In-Service Life |
The length of time or total
gallons delivered between servicing of the media in a filter as determined
under standard test conditions. |
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Rated Pressure Drop |
The pressure drop of a
water softener or filter at the rated service flow, with clean water at a
temperature of 60oF, with a freshly regenerated and/or backwashed softener
or filter, as determined under standard test conditions. |
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Rated Service Flow |
The manufacturer's
specified maximum flow rate at which a water softener will deliver soft
water, or a filter will deliver quality water as specified for its type,
as determined under standard test conditions. A manufacturer may also
specify a minimum flow rate or a range of service flows. |
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Rated Softener Capacity |
A water softener capacity
rating based on grains of hardness removed while producing soft water
between successive regenerations, and related to the pounds of salt
required for each regeneration, as determined under standard test
conditions. |
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Raw Water |
Untreated water, or any
water before it reaches a specific water treatment device or process. |
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Raw Water |
Water in its natural state,
prior to any treatment for drinking. |
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Recovery |
In reverse osmosis
processes, indicates the amount of product water taken from the feed water
stream; expressed as a percentage of product water flow rate to feed water
flow rate. (See concentration factor.) |
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Red Water |
Water which has a reddish
or brownish appearance due to the presence of precipitated iron and/or
iron bacteria. |
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Reduction |
A chemical process in which
electrons are added to an atom, ion or compound, causing the substance's
valence to decrease. Whenever reduction occurs, an off-setting oxidation
reaction must occur. (See oxidation.) |
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Regenerant |
A solution of a chemical
compound used to restore the capacity of an ion exchange system. Sodium
chloride brine is used as a regenerant for ion exchange water softeners,
and acids and bases are used as regenerants for the cation and anion
resins used in demineralization. |
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Regeneration |
The process of restoring an
ion exchange medium to a usable state after exhaustion. In general, it
includes the backwash, regenerant introduction and fresh water rinse steps
necessary to prepare a water softener exchange bed for service.
Specifically, the term may be applied to the step in which the regenerant
solution is passed through the exchanger bed (salt brine for softeners,
acid and bases for deionizers. |
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Regeneration Level |
The quantity of regenerant
used in the regeneration of an ion exchange unit or system, usually
expressed in pounds per regeneration and/or pounds per regeneration per
cubic foot of ion exchanger. |
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Rejection |
In reverse osmosis
processes, the degree of removal of dissolved salts from the feed water as
it passed through a semipermeable membrane (also called "salt
rejection"); expressed as a percentage of the feed water TDS. (See
total dissolved solids.) |
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Residual |
The amount of a specific
material remaining in the water following a water treatment process; may
refer to material remaining as a result of incomplete removal (see
leakage), or to material meant to remain in the treated water. (See
residual chlorine.) |
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Residual Chlorine |
Chlorine remaining in a
treated water after a specified period of contact time to provide
continuing protection throughout a distribution system; the difference
between the total chlorine added, and that consumed by oxidizable matter.
(See combined available chlorine, free available chlorine.) |
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Resin |
Synthetic organic ion
exchange material, such as the high capacity cation exchange resin widely
used in water softeners. |
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Resistance |
In water conditioning, the
opposition offered by water to the flow of electricity through it; the
reciprocal of electrical conductance. The unit of measurement for
electrical resistance is the Ohm. Electrical resistance can be used to
approximate the mineral content, or lack of it, in high quality water.
(See conductance.) |
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Resistivity |
A capacity for resisting
the flow of electricity. (See resistance.) |
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Reverse Deionization |
The use of the anion
exchange resin ahead of the cation exchange resin (the reverse of the
usual order), in a deionization system. |
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Reverse Osmosis |
(R.O.) A process that
reverses, by the application of pressure, the natural process of osmosis
so that water passed from the more concentrated to the more dilute
solution through a semipermeable membrane, thus producing a stream of
water up to 98% free of dissolved solids. |
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Rinse |
That portion of the
regeneration cycle of an ion exchanger in which fresh water is passed
through the column to remove spent and excess regenerant, prior to placing
the system in service. |
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Risk |
The
potential for harm to people exposed to chemicals. In order for there to
be risk, there must be hazard and there must be exposure. |
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