A polyamide membrane.

(ppm) A common unit of measure used to express the number of parts of a substance contained within a million parts of a liquid, solid, or gas. Generally interchangeable with “milligrams per litre” in dilute solutions and water treatment calculations.

(ppt) A unit of measure used to express the number of parts of a substance contained within a thousand parts of a liquid, solid, or gas. Generally used to specify a water’s salinity and commonly indicated by the symbol “0/00”.

An impulse hydraulic turbine that may be used an energy recovery device in high head applications such as seawater reverse osmosis.

A unit of measurement used to characterize evaporator performance expressed as the mass of distillate produced per unit of energy consumed.

Hardness associated with sulphates, chlorides and nitrates of calcium and magnesium which remain after boiling.

The liquid that passes through a membrane.

See “semipermeable membrane”.

Membrane process to remove salt from solution where salt, rather than water, passes through the membrane.

The reciprocal of the logarithm of the hydrogen ion concentration in gram moles per litre. On the 0 to 14 pH scale, a value of 7 at 25°C (77°F) represents a neutral condition. Decreasing values indicate increasing hydrogen ion concentration (acidity), and increasing values indicate decreasing hydrogen ion concentration (alkalinity). Full form is “potential of hydrogen”.

See “USP-purified water”.

The state of a substance; solid, liquid or vapour.

A change in the state of a substance such as from liquid to vapour (evaporation) or solid to liquid (melting)

See “Silt Density Index”.

A molecular chain polymer made of amide linkages used in the construction of thin film composite reverse osmosis membranes.

A synthetic thermoplastic polymer used in the manufacture of ultrafiltration membranes and in thin film composite and charged polysulfone reverse osmosis membranes.

Addition of chlorine after completion of other treatment processes.

The treatment processes following desalination, usually employed to stabilize water and reduce its corrosivity and improve its taste.

See “drinking water”.

1) A parameter comparing electric power production to desalinated water production. 2) A parameter comparing electric power demand to desalinated water demand

See “parts per million”.

A solid that separates from a solution.

(PV) 1) A tank or chamber designed to contain a fluid at a different pressure from its surroundings. 2) The cylindrical vessel which contains one or more membrane elements.

Water that is used for, or comes in contact with an end product or the materials used in an end product.

Reverse osmosis process configuration where the product from one stage is used as feedwater on a subsequent stage to improve product water quality.

Water produced as a result of treatment or desalination processes.

The action exhibited by sea, brackish and other waters containing high concentrations of sodium that interferes with the normal behaviour of soap.

Power and water purchase agreement.