Veolia Water Technologies Ireland

Dublin Road 


Co. Kildare

Tel: + 353 1 630 3333
Fax: + 353 1 630 3344


Glossary of Terms

Find the definition of the most common terms used in the pharmaceutical water treatment.

Absorption - A process by which a substance is taken up chemically or physically in bulk by a material (absorbent) and held in pores or interstices in the interior.

Activated Carbon - A highly porous form of carbon used for sorption of organics and removal of free chlorine and chloramine.

Adsorption - Adherence of molecules, atoms and ionised species of gas or liquid to the surface of another substance (solid or liquid) as the result of a variety of weak attractions.

Anion Exchange Resin - An ion exchange resin with immobilised positively charged exchange sites, which can bind negatively charged ionised species, anions.

Azeotrope - A blend of two or more components with equilibrium vapour phase and liquid phase compositions that are the same at a given temperature and pressure.

Backwash - The upward flow of water through a resin or carbon bed to clean it, and in the case of a mixed bed, to separate anion and cation resins.

Bactericide - A chemical or physical agent that kills bacteria.

Biocide - A chemical or physical agent that kills micro-organisms.

Biofilm - A layer of micro-organisms enclosed in a glycoprotein polysaccharide matrix which are adherent to each other and/or to surfaces.

Calibration - A comparison of a measurement instrument to detect, correlate or eliminate by adjustment of any variation.

Carbon Fines - Very small particles of carbon that may wash out of an activated carbon bed.

Cartridge - A pre-packed disposable container for housing a water purification media or membrane.

Cation Exchange Resin - An ion exchange resin with immobilized immobilised negatively charged exchange sites, which can bind positively charged ionized ionised species, cations.

CFU/ml - Colony Forming Units per milliliter. A measure of viable microbial populations.

Channeling - Preferential flow of water through a resin/granular activated carbon bed effectively causing by-pass of ion exchange/activated carbon sites. Poor quality and capacity will result.

cGMP - current Good Manufacturing Practice.

Colloid - A stable dispersion of fine particles in water that have a typical size less than 0.1 µm. Colloids containing iron, aluminum, silica and organics are commonly found in natural and potable waters.

Color Change Resin - A resin that is dyed with a pH indicator so that it changes color upon exhaustion to indicate when the cartridge needs replacing.

Concentrate - The liquid containing dissolved and suspended matter that concentrates on the inlet side of a membrane and flows to drain.

Condenser - The stage of a distillation system that removes sufficient heat from a vapourised liquid to cause the vapour to change to a liquid phase.

Conductivity - Conductivity is the reciprocal of resistivity. For water purification systems, conductivity is usually reported as microsiemens per centimeter (μS/cm).

Contactor Membrane (DG) - A hydrophobic membrane used in removing dissolved gases (CO2 or O2) from water.

Continuous electrodeionization (CEDI) - Technology combining ion exchange resins and ion selective membranes with direct current to remove impurity ionised species from water without regeneration phase.

Deadleg/Dead Volume - A region or volume of stagnation in an apparatus or distribution system.

De-gassing - The removal of O2 and CO2 from water, usually by transfer across a hydrophobic membrane. CO2 is removed to increase ion exchange capacity and improve electrodeionisation efficiency.

Deionisation (DI) - Removal of impurity ions from water. Usually used to refer to ion exchange - see Ion Exchange

Deionisation Service - see Service Deionisation.

Distillation - A purification process that takes advantage of changing the phase of a substance from liquid to vapour and back to liquid usually at the boiling temperature of the substance, in order to separate it from other substances with higher or lower boiling points.

Endotoxin - A thermally stable lipopolysaccharide component from the cell wall of viable or nonviable Gram-negative micro-organisms. Can act as a pyrogen.

Endotoxin Units (IU/ml or EU/ml)
A quantification of endotoxin levels relative to a specific quantity of reference endotoxin. 1 IU/ml is approximately equal to 0.1 ng/ml.

Exotoxin - A toxic substance secreted by a bacterium, often causing disease, which can also act as a pyrogen.

FDA - United States Food and Drug Administration.

Feedwater - The water that is introduced into a purification process.

Filtration - A purification process in which the passage of fluid through a porous material results in the removal of impurities.

Fines - Particulates released from a bed of material such as ion exchange resins.

Fouling Index - see Silt Density Index.

GAMP - Good Automated Manufacturing Practice.

Gram-negative - refers to bacteria that do not absorb a violet stain originally described by Gram.

Gram-positive - refers to bacteria that absorb a violet stain originally described by Gram.

Hardness - The scale-forming and lather-inhibiting qualities of some water supplies, caused by high concentrations of calcium and magnesium. Temporary hardness, caused by the presence of magnesium or calcium bicarbonate, is so called because it may be removed by boiling the water to convert the bicarbonates to the insoluble carbonates. Calcium and magnesium sulfates and chlorides cause permanent hardness.

HPW - Highly Purified Water.

Ion - Any non-aggregated particle of less than colloidal size possessing either a positive or a negative electric charge.

Ion Exchange (IX) - The process of purifying water by removing ionized salts from solution, by replacing hydrogen ions for cation impurities and hydroxyl ions for anion impurities.

LAL - Limulus Amoebocyte Lysate, an extract from the horseshoe crab which forms a gel in the presence of sufficient endotoxin. Used as the basis for the LAL test for endotoxins.

Line Cell - An electrode assembly inserted into a water stream by which the conductivity or resistivity is measured.

Micro-organism - Any organism that is too small to be viewed by the unaided eye, such as bacteria, viruses, molds, yeast, protozoa, and some fungi and algae.

Nuclear Grade Resin - A high purity (analytical) grade of ion exchange resin originally developed for the nuclear energy industry.

Off-line - In water monitoring systems, referring to measurement devices that are not directly coupled to the water stream.

On-line - In water monitoring systems, referring to measurement devices directly coupled to the water stream.

Ozone - Ozone is used in the pharmaceutical industry as a sanitizing agent. O3 is a very strong oxidising agent, kill bacteria and reduce TOC in water.

Particulates - Discrete quantities of solid matter dispersed in water.

Permeate - The purified solution which has been produced by passage through a semi-permeable reverse osmosis membrane.

pH - A measure of the acidity or alkalinity of a solution equal to -log (H+).

PhEur - European Pharmacopoeia.

Photo-oxidation - See Ultra Violet (Photochemical) Oxidation.

Planktonic - Used to describe aquatic micro-organisms that float.

Point of Use - A dispense point from a purified water system from which water can be taken.

Polishing - The final treatment stage(s) of a water purification system.

Potable water - Water which meets regulations as suitable for ingestion by humans.

PPB - Parts per billion is a unit equal to microgramme per kilogram of water. Numerically ppb are equivalent to microgramme per litre in dilute aqueous solutions.

PPM - Parts per million is a unit equal to milligramme per kilogram of water. Numerically ppm are equivalent to milligrammes per litre in dilute aqueous solutions.

PPT - Parts per trillion is a unit equal to nanogramme per kilogram of water.

PSG - Pure Steam Generator.

Pyrogen - A category of substances, including bacterial endotoxins, which may cause a fever when injected or infused.

Qualification - The act of establishing with documented evidence that the process, equipment, and/or materials are designed, installed, operated and perform according to the pre-determined specifications.

Regeneration - The method by which exhausted ion exchange resins are reactivated by treatment with strong acid or alkali.

Resistivity - The electrical resistance between opposite faces of a one-centimetre cube of a given material at a specified temperature. Resistivity is the reciprocal of conductivity. For water analysis, resistivity is usually reported in megohm-centimetres(MΩ-cm).

Storage tank - In water purification systems, a container holding quantities of purified water.

Reverse osmosis (RO) - A process in which water is forced under pressure through a semi-permeable membrane leaving behind dissolved organic, dissolved ionic, and suspended impurities.

Sanitisation- Chemical and/or physical processes used to kill micro-organisms and reduce contamination from micro-organisms

Service Deionisation(SDI) - Deionisation service provided by exchanging cylinders containing ion exchange resins, which have been regenerated or replaced at a regeneration station.

Silt Density Index - also called the Fouling Index (FI) is a test used to estimate the potential of the water to block filters, derived from the rate of blockage of a 0.45 micron-filter under standard conditions.

SJP (JP)- The Society of Japanese Pharmacopoeia (SJP) is a non-profit foundationauthorised by the Ministry of Health, Labour and Welfare (MHLW).
It was established mainly to promote dissemination of the Japanese Pharmacopoeia (JP) for the purpose of maintenance and improvement in the efficacy, safety and quality of pharmaceutical drugs.

Softening - A water treatment process whereby cations, notably hardness-forming calcium and magnesium ions, are exchanged for sodium using cation exchange resins in the sodium form.

Stagnation - State of a liquid without current or circulation.

Sterilisation - Destruction or removal of all living micro-organisms.

Total Dissolved Solids (TDS) - A measure of the total of organic and inorganic salts dissolved in water, obtained by drying residue at 180ºC.

Total organic carbon (TOC) - Total concentration of carbon present in organic compounds.

Turbidity - The degree of cloudiness of water caused by the presence of suspended particles or colloidal material. Turbidity reduces the transmission of light and is measured in Nephelometric Turbidity Units (NTU).

Ultrafiltration - A process in which water is filtered through a polymeric membrane having a very fine pore structure.

Ultra-violet (Photochemical) Oxidation - A process using short wavelength light to kill micro-organisms and cleave or oxidise organic molecules.

USP - United States Pharmacopoeia The United States Pharmacopoeia (USP) is the official public standards-setting authority for all prescription and over-the-counter medicines, dietary supplements, and other healthcare products manufactured and sold in the United States. USP sets standards for the quality of these products and works with healthcare providers to help them reach the standards. USP's standards are also recognised and used in more than 130 countries.

Validation - Confirmation, through the provision of objective evidence, that requirements for a specific intended use or application have been fulfilled.

Verification - Confirmation, through the provision of objective evidence, that specified requirements have been fulfilled.

WFI - Water For Injection.

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