Glossary

A dictionary of desalination terms.

EAR

Engineer-At-Risk

economy

In thermal desalination, the ratio of kilograms of distilled water produced per 2326 kJ of energy input.

ED

See “electrodialyis”.

EDI

See “electrodeionization”.

EDR

See “electrodialysis reversal”.

EDS

European Desalination Society.

effect

One of several units of an evaporator, each of which operates at successively lower pressures.

ejectocompressor

See “thermocompressor”.

electrodialysis

(ED) The separation of a solution’s ionic components through the use of semipermeable, ionselective membranes operating in a DC electric field.

electrodialysis-reversal

(EDR) A variation of the electrodialysis process using electrode polarity reversal to automatically clean membrane surfaces.

electrodeionization

(EDI) A water treatment process combining an electrodialysis membrane process with an ion exchange resin process to produce high purity, demineralized water.

electrolysis

The passage of electric current through an electrolyte resulting in chemical changes caused by migration of positive ions towards the cathode, and negative ions to the anode.

electronic-grade water

Water used in the production of microelectronic devices which meets ASTM D-19 standards for resistivity, silica concentration, particle count and other criteria.

element

1) One of the fundamental substances that consist of atoms of only one kind and that constitute all matter.

2) A common term for an individual flat sheet RO membrane rolled into a cylindrical shape around a permeate tube.

elutriator

An extension in an evaporator vapour body to thicken the solids slurry to minimize the loss of liquor.

energy recovery

The retrieval of waste energy for some beneficial use.

energy recovery turbine

(ERT) A device used to recover pressure energy from reverse osmosis brine streams.

enthalpy

The total heat content of a liquid, vapour, or body.

entrainment

(1) The incorporation of small organisms, including the eggs and larvae of fish and shellfish, into an intake system.

(2) The carryover of droplets of water with vapour produced during evaporation.

EPC

Engineer-Procure-Construct

ER

Energy recovery.

ERD

Energy recovery device.

ERT

See “energy recovery turbine”.

evaporation

The process in which water is converted to a vapour that can be condensed.

evaporation rate

The mass quantity of water evaporated from a specified water surface per unit of time.

evaporator

A device used to heat water to create a phase change from the liquid to the vapour phase.

exchange capacity An ion exchanger unit’s limited capacity

for storage of ions.

exhaustion

That condition that results when activated carbon, ion exchange resin, or other absorbents have depleted their capacity by using all available sites.

extraction turbine

A condensing turbine which has been designed to allow some steam to be removed for other uses after expansion to an intermediate pressure. Steam is removed at extraction points which are controlled at predetermined pressures.