See “hydrogen sulfide”.

Alkaline water containing dissolved salts that interfere with some industrial processes and prevent soap from sudsing. Moderately hard water has a “hardness” of 75 to 150 mg/L and hard water has a “hardness” above 150 mg/L.

The total concentration of calcium and magnesium ions in water expressed as calcium carbonate.

An accounting of the distribution of a system’s heat loss and heat gain.

The amount of heat released when a vapour changes state to a liquid.

The amount of heat required to change a volume of liquid to a vapour.

(HRSG) A boiler device most typically installed on a gas turbine to recover heat and make steam using the hot exhaust gases.

Type of reverse osmosis and ultrafiltration membranes formed into small diameter tubes.

See “heat recovery steam generator”.

A system incorporating multiple processes or technologies; for example, a desalination facility incorporating both thermal and membrane processes. Generally the technologies should at least be partially integrated for some process benefit to qualify as hybrid.

A toxic gas formed by the anaerobic decomposition of organic matter containing sulfur. Chemical formula is H₂S.

The natural cycle of continuous evaporation and condensation.

A chemical change or decomposition of matter produced by combination with water.

Having an affinity for water.

Having an aversion to water.

A negatively charged ion consisting of a hydrogen atom and an oxygen atom. Chemical formula is OH.

Filtration using a dense membrane that is often used synonymously with “reverse osmosis”.