MANOWNROSM
APPENDIX
US Filter
33
7. 0
APPENDIX
GLOSSARY OF TERMS
The terms commonly used in reverse osmosis are defined below:
ANION
- Negatively charged ion, such as CO
3
--
, SO
4
--
, HCO
3
--
, Cl
-
, NO
3
-
, etc.
CATION
- Positively charged ion, such as Ca
++
, Mg
++
, Fe
++
, Na
+
, K
+
, etc.
CONCENTRATE
(
REJECT
) - Concentrated portion of the feed remaining outside the
membrane which is discarded.
CONDUCTIVITY
- A measure of salt concentration due to the ability of dissolved solids (ions) to
conduct electricity, usually expressed as micromhos/cm.
CONVERSION
- Percent of feedwater converted into permeate.
FEED
- The feedwater pumped into a permeator under high pressure.
OSMOSIS
- Osmosis is the diffusion of a solvent (such as pure water) from a dilute saline
solution into a more concentrated saline solution through a semipermeable membrane
separating the two solutions.
OSMOTIC EQUALIZATION
- Osmotic equalization is reached when no further water transport
takes place due to equalization of the solute concentration on both sides of the membrane.
OSMOTIC HEAD
- Osmotic head (pressure) is the change in head resulting from water
transport through the semipermeable membrane separating two saline solutions of different
concentrations.
PASSAGE
- Ratio of permeate to feed concentration of a particular dissolved material,
expressed in percent.
PERMEATE (PRODUCT)
- The purified portion of the feed passing through the membrane.
REVERSE OSMOSIS (RO)
- The process by which incoming fluid (feed) is forced under high
pressure through a RO membrane. A portion of the fluid with concentrated ionic materials
(concentrate) remains upstream of the membrane and is discarded (unless it is of interest in a
particular application). The highly purified portion (permeate) which passed through the
membrane would then be collected for use (as in a water purification application).
REVERSE OSMOSIS (RO) MEMBRANE
- An RO membrane is a semipermeable membrane
generally in sheet or hollow fiber form which rejects not only dissolved materials, but also
organics, submicron size colloidal materials and bacteria which may contaminate a high purity
water system. The process is not absolute and therefore most RO membranes are defined by
their rejection characteristics.
SOLUTE
- Material (salts) dissolved by solvent (water).
TOTAL DISSOLVED SOLIDS
- Total dissolved inorganic salts present in the permeator
streams.
