Million acre feet.

Fluid introduced in a recirculating stream to maintain an equilibrium of temperature, solids concentration or other parameter(s).

Additional unit of water for further treatment, which is economically questionable.

Multiple effect. See “multiple effect distillation”.

Multiple effect boiling. See “multiple effect distillation”.

See “multiple effect distillation”.

(ML) A unit of volume equal to 1 million litres.

A thin barrier that permits passage of particles of a certain size or of particular physical or chemical properties.

Processes including reverse osmosis, electrodialysis, and ultrafiltration that use membranes to remove dissolved material or fine solids.

A water softening process that utilizes semi-permeable nanofiltration or reverse osmosis membranes to remove hardness constituents such as calcium and magnesium from water.

The basic SI unit of length equivalent to approximately 39.37 inches, or the distance travelled by light in a vacuum in 1/299,792,458 seconds.

A unit of mass equal to 1000 kilograms or approximately 2204 pounds. Also called “tonne”.

See “microfiltration”.

Million gallons (US) per day.

Million gallons (Imperial) per day.

See “electronic-grade water”.

A unit measure of conductivity equal to one millionth of a mho.

(µ) A unit of length equal to one-millionth of a metre. Also called “micrometre”.

(mg) A unit of mass equal to one-thousandth of a gram.

(mg/L) A common unit of measurement of the concentration of a material in solution.

(mL) A unit of volume equal to one cubic centimetre.

A device used to remove entrained droplets of water from a vapour stream produced during evaporation.

Ion exchange demineralizer containing strong-acid and strong-base resins in a single vessel.

The concentrated solution that remains after evaporation or crystallization. See also “bittern”.

High pressure steam which is used to operate a steam-jet ejector or thermocompressor.

See “multistage flash evaporation”.

Multistage flash evaporation, brine recirculation.

Multistage flash evaporation, once-through.

(MED) A thin film evaporation process where the vapour formed in a chamber, or effect, condenses in the next, providing a heat source for further evaporation.

(MSF) A desalination process where a stream of brine flows through the bottom of chambers, or stages, each operating at a successively lower pressure, and a proportion of it flashes into steam and is then condensed.

Mechanical vapour compression. See “vapour compression evaporation”.

Mechanical vapour recompression. See “vapour compression evaporation”.