Glossary
A dictionary of desalination terms.
Cellulose acetate membrane.
The heating element in an evaporator consisting of vertical tubes which act as the heating surface.
A white, chalky substance which is the principle hardness and scale-causing compound in water. Chemical formula is CaCO3.
(mg/L as CaCO3) A convenient unit of exchange for expressing all ions in water by comparing them to calcium carbonate which has a molecular weight of 100 and an equivalent weight of 50; signifies that the concentration of a dissolved mineral is chemically equivalent to the stated concentration of calcium carbonate.
The portion of the total hardness attributed to calcium compounds.
See “hydrated lime”.
A white solid known as the mineral “anhydrite” with the chemical formula CaSO4, and gypsum with the formula CaSO4-2H2O.
The amount of heat required to raise the temperature of one gram of water one degree Celsius, also known as a “small calorie”. A “large calorie” or “kilocalorie” is the amount of heat required to raise the temperature of a kilogram of water by one degree Celsius.
An electrically regenerated electrosorption process capable of desalinating saline water.
A filter unit with cylindrical replaceable elements or cartridges.
A positively charged ion that migrates to the cathode when an electrical potential is applied to a solution.
The ion exchange process in which cations in solution are exchanged for other cations bound to an ion exchange resin or medium.
Calcium carbonate precipitation potential.
(CA) A plastic material used to make the cellulosic-type semipermeable reverse osmosis membranes.
(C) The SI temperature scale on which 0 degrees is the freezing point and 100 degrees is the boiling point of water. Often referred to as the “centigrade” scale.
Colloquial term for the Celsius scale of temperature measurement.
The volume of gas at constant pressure varies in direct proportion to the absolute temperature.
Disinfecting compounds containing nitrogen, chlorine and hydrogen formed by the reaction between hypochlorous acid and ammonia and/or organic amines in water. Also called “combined available chlorine”.
(1) The ionic form of the element chlorine where the atom has gained one electron, whose chemical symbol is Cl-.
(2) Any salt containing the Cl- anion.
An oxidant commonly used as a disinfectant in water and wastewater treatment. Chemical formula is Cl2.
The amount of chlorine remaining in water after application at some prior time; the difference between the total chlorine added and that consumed by oxidizable matter. See “free chlorine residual”.
See “clean-in-place”.
(CIP) A method of cleaning process equipment to restore its performance without removing it from the system.
A chemical added to initially destabilize, aggregate, and bind together colloids and emulsions to improve settleability, filterability or drainability.
See “cogeneration”.
A power system that simultaneously produces both electrical and thermal energy from the same source.
Suspended solid with a diameter less than one micron that can not be removed by sedimentation alone.
A gas turbine generator system where heat from turbine generator exhaust gases are recovered by a steam generating unit whose steam is used to drive a steam turbine generator.
A mechanical device used to increase the pressure of a gas or vapour.
The water containing the dissolved solids removed during desalination.
concentration (1) The amount of a substance dissolved or
suspended in a unit volume of solution. (2) The process of
increasing the amount of a substance per unit volume of
solution.
(1) A number indicating the number of times a solution has been concentrated from its initial condition.
(2) A number indicating the number of times a solution may be concentrated.
A phenomenon in which solutes form a dense, polarized layer next to a membrane surface which eventually restricts flow through the membrane.
Water obtained by evaporation and subsequent condensation.
The change in state from vapour to liquid; the opposite of evaporation.
A heat exchanger device used to cool steam and convert it from the vapour to liquid phase.
A turbine which expands steam into a condition which is below atmospheric pressure converting thermal energy into shaft rotation.
(1) A measure of a solution’s electrical conductivity that is equal to the reciprocal of the electrical resistance.
(2) A rapid method of estimating the dissolved-solids content of a water sample by determining the capacity of a water sample to carry an electrical current.
See “recovery”.
Water used, usually in a heat exchanger, to reduce the temperature of liquids or gases.
The combination of pressure and temperature at which point a gas and liquid become indistinguishable.
Common term for a forced circulation evaporator.
Cellulose triacetate.
(cc) A volume measurement equal in capacity to one millilitre (mL). One US quart is approximately 946 cubic centimetres.
(m³) A volume measurement equal to 1000 litres or 264. 2 US gallons. One cubic metre of water weighs one tonne.
(COC) The ratio of the total dissolved solids concentration in a recirculating water system to the total dissolved solids concentration of the makeup water.