A

ABS The abbreviation for Alkyl Benzene Sulfonate. A detergent compound.

Absolute (Filtration) Usually used with a term designating particle diameter and meaning that no particle larger than the specified diameter will pass the filter.

Absorption The process in which one substance is taken into the body of another substance, termed the absorbent. An example is the absorption of water into soil.

Acid A water soluble compound that will react with a base to form a salt which releases hydrogen ions; contains species able to give up a proton to a base. Typical acids: Hydrochloric (HCl), Sulfuric (H2SO4), Nitric ( HNO3), Acetic (CH2COOH).

Acidity The quantitative capacity of water or a water solution to neutralize an alkali or base. It is usually measured by titration with a standard solution of sodium hydroxide and expressed in terms of its calcium carbonate equivalent. (See Total Acidity, Carbon Dioxide.)

Activated Carbon A granular material usually produced by the roasting of cellulose base substances, such as wood or coconut shells in the absence of air. It has a very porous structure and is used in water conditioning as an adsorbent for organic matter and certain dissolved gases. Sometimes called activated charcoal.

Adsorbent A material, usually solid, capable of holding gases, liquids and suspended matter at its surface and in exposed pores. Activated carbon is a common adsorbent used in water treatment.

Adsorption The adhesion of a thin layer of molecules (as gases, solutes, or liquids) to the surfaces of solid bodies or liquids with which they are in contact.

Algae Small primitive plants containing chlorophyll, commonly found in surface water. Excessive growths may create taste and odor problems and consume dissolved oxygen during decay.

Alkalinity The quantitative capacity of water or a water solution to neutralize an acid. It is usually measured by titration with a standard acid solution of sulfuric acid and expressed in terms of its calcium carbonate equivalent. (See Base.)

Anion A negatively charged ion in solution, such as bicarbonate, chloride or sulfate. Example: Chloride (C1-)), Nitrate (NO3-), Fluoride (F-). In deionization the type of ion exchange resin which exchanges negative ions or anions.

Anion Exchange An ion exchange process in which anions in solution are exchanged for other anions from an ion exchanger. In demineralization, for example, bicarbonate, chloride and sulfate anions are removed from solution in exchage for a chemically equivalent number of hydroxide anions from the anion exchange resins. (See Ion Exchange, Demineralization.)

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B

Bacteria Typically one-celled microorganisms which have no chlorophyll, multiply by simple division, and can be seen only with a microscope. Occur in three main forms: spherical (cocci), rod-shaped (bacilli) and spiral (spirilla).

Backwash The process in which beds of filter or ion exchange media are subjected to flow opposite to the service flow direction to loosen the bed and to flush suspended matter, collected during the service run, to waste.

Base A substance which releases hydroxyl ions when dissolved in water. Bases react with acids to form a neutral salt and water. (Also Alkali)

Bed The ion exchanger or filter media in a column or other tank or operational vessel.

Bed Depth The height of the ion exchanger or filter media in the vessel after preparation for service.

Bed Expansion The increase in volume of a bed of ion exchanger or filter media during upflow operations such as backwashing, due to lifting and separation of the bed material. Usually expressed as the percent of increase of bed depth.

Brackish Water Water containing dissolved solids in the range of 1,000 to 10,000 mg/L.

Breakthrough The appearance in the effluent from a water conditioner of the material to be removed by the conditioner, such as hardness in the effluent of a softener or turbidity in the effluent of a mechanical filter - an indication that regeneration, backwashing or other treatment is necessary.

Brine A strong solution of salts, such as the sodium chloride brine used in the regeneration of ion exchange water softeners, but also applied to the mixed sodium, calcium and magnesium chloride waste solution from regeneration.

Buffer A chemical which causes a solution to resist changes in pH, or which to shift the pH to a specific value.

Bypass A connection or a valve system that allows untreated water to flow to a water system while a softener or filter is being regenerated, backwashed or serviced; also applies to a special water line installed to provide untreated water to a particular tap such as a sill cock.

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C

Calcium One of the principal elements making up the earth’s crust, the compounds of which when dissolved make the water hard. The presence of calcium in water is a factor contributing to the formation of scale and insoluble soap curds, which are means of clearly identifying hard water.

Calcium Carbonate Equivalent A common basis for expressing the concentration of hardness and other salts in chemically equivalent terms to simplify certain calculations; signifies that the concentration of a dissolved mineral is chemically equivalent to the stated concentration of calcium carbonate.

Calcium Hypochlorite A chemical compound (Ca(OCl)2), used as a bleach and a source of chlorine in water treatment; specifically useful because it is stable as a dry powder and can be formed into tablets.

Capacity An expression of the quantity of an undesirable material which can be removed by a water conditioner between servicing of the media, i.e., cleaning, regeneration or replacement, as determined under standard test conditions. For ion exchange water softeners, the capacity is expressed in grains of hardness removal between successive regenerations and is related to the pounds of salt used in regeneration. For filters, the capacity may be expressed in the length of time or total gallons delivered between servicing.

Carbon Dioxide A gas present in the atmosphere and formed by the decay of organic matter; the gas in carbonated beverages. In water it forms carbonic acid.

Cartridge Any removable, pre-formed or pre-packaged component containing a filtering media or ion exchanger.

Cation An ion with a positive electrical charge, such as calcium, magnesium and sodium. In deionization - the type of resin which exchanges positive ions.

Cation Exchange Ion exchange process in which cations in solution are exchanged for other cations from an ion exchanger.

Caustic Any substance capable of burning or destroying animal flesh or tissue. The term is usually applied to strong bases.

Caustic Soda The common name for sodium hydroxide.

Channeling The flow of water or other solution in a limited number of passages in a filter or ion exchanger bed, instead of distributed flow through all passages in the bed. May be due to fouling of the bed and plugging of many passages, poor distributor design, flow rates which are too low, faulty operational procedures or other causes.

Chemical Feeder A mechanical device designed to introduce chemicals into a water system, more or less accurately in proportion to water flow.

Chemical Stability Resistance to attack by chemical action, often applied to the resistance of ion exchange resins to breakdown due to contact with aggressive solutions.

Chlorine A gas, C12, widely used in the disinfection of water and an oxidizing agent for organic matter, iron, etc.

Chlorinator A mechanical device specifically designed to feed chlorine gas or solutions of its compounds, such as hypochlorites, into a water supply in proportion to the flow of water.

Chloramine General term for a class of amine compounds formed by the action of chlorine on various amines.

Chlorine Demand A measure of the amount of chlorine which will be consumed by orgainc matter and other oxidizable substances in a water before a chlorine residual will be found; the difference between the total chlorine fed and the chlorine residual.

Coliform Bacteria A group of organisms primarily found in human and animal intestines and wastes, and thus widely used as indicator organisms to show the presence of such wastes in water and the possible presence of pathogenic (disease producing) bacteria.

Concentrate Name given to the stream of liquid from a reverse osmosis unit which has not passed through the membrane as opposed to permeate which has passed through.

Collector A device or system designed to collect backwash water from a filter or ion exchange bed. May also be used as an upper distributor to spread the flow of water in downflow column operation. (See Distributor.)

Colloid Very finely divided solid particles which will not settle out of a solution, intermediate between a truely dissolved particle and a suspended solid which will settle out of solution. The removal of colloidal particles usually requires coagulation to form larger particles which may be removed by sedimentation and/or filtration, but can sometimes be addressed by ultrafiltration.

Color The shade or tint imparted to water by substances in true solution and thus not removed by mechanical filtration, most commonly caused by dissolved organic matter, but may be produced by dissolved mineral matter.

Combined Available Chlorine The chlorine present as chloramine or other derivatives in a water, but still available for disinfection and the oxidation of organic matter. The combined chlorine compounds are more stable than free chlorine forms, but are somewhat slower in action.

Contamination The addition of foreign matter to a substance which reduces the value of the substance or interferes with its intended use.

Cycle A series of events or steps which ultimately lead back to the starting point, such as the exhaustion-regeneration cycle of an ion exchange system; sometimes incorrectly used in reference to a single step of a complete cycle.

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D

Dechlorination The removal of excess chlorine residual, often after super-chlorination.

Deionization The removal of all ionzed minerals and salts (both organic and inorganic) from a solution by a two-phase ion exchange procedure. First, postively charged ions are removed by a cation exchange resin in exchange for a chemically equivalent amout of hydrogen ions. Second, negatively charged ions are removed by an anion exchange resin for a chemically equivalent amount of hydroxide. The hydrogen and hydroxide ions introduced in this process unite to form water molecules. The term is often used interchangeably with demineralization. (See Demineralization, Ion Exchange.)

Demineralization The removal of ionized inorganic minerals and salts (not organic materials) from a solution by a two-phase ion exchange procedure; similiar to deionization, and the two terms are often used interchangeably. (See Deionization, Ion Exchange.)

Density The mass of a substance per specified unit of volume; for example, pounds per cubic foot. True density is the mass per unit volume excluding pores. Apparent density is the mass per unit volume including pores.

Detergent Technically, any materials with cleansing powers, including soaps, the newer synthetic detergents, many alkaline materials and solvents and even abrasives. In popular usage the term is often used to mean the synthetic detergents such as ABS or LAS.

Differential Pressure The difference in pressures at two points in a water system. It may be due to differences in elevation or to friction losses or pressure drops due to resistance flow in pipes, softeners, filters or other devices.

Disinfection A process in which pathogens (disease producing bacteria) are killed in a machine or water system which has been treated to eliminate bacteria. Many involve disinfecting agents such as chlorine or physical processes such as heating where it may not necessarily be sterile.

Dissociation The separation of molecules into positively and negatively charged ions in water solutions.

Distillation The process in which a liquid, such as water, is converted into its vapor state by heating, and the vapor cooled and condensed to the liquid state and collected; used to remove solids and other impurities from water. Multiple distillations are required for extreme purity.

Distributor A device or system designed to produce even flow through all sections of an ion exchanger or filter bed and to retain the media in the tank or vessel; usually installed at the top and bottom of loose media systems. (See Collector.)

Downflow A term applied to designate the direction (down) in which water or a regenerant flows through an ion exchanger or filter during any phase of the operating cycle.

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E

Eductor, Ejector A device utilizing a nozzle and throat, installed in a stream of water to create a partial vaccum to draw air or liquid into the stream; commonly used to draw brine into a water line for the regeneration of an ion exchanger water softener.

Effluent The stream emerging from a unit, system or process, such as the softened water from an ion exchanger softener.

Endotoxin Any of a group of toxic substances found in certain disease producing bacteria and liberated by the disintegration of the bacterial cell wall.

Endpoint The point at which a process is stopped because a predetermined value of a measurable variable is reached. The endpoint of an ion exchanger water softener service run is the point at which the hardness of the softener effluent increases to a predefined concentration, often 1.0 grain per gallon. The endpoint of a filter service run may be the point at whch the pressure drop across the filter reaches a predetermined value. The endpoint of a titration is the point at which the titrant produces a predetermined color change, pH value or other measurable characteristic.

Exhaustion The state of an ion exchange material in which it is no longer capable of effective function due to the depletion of the initial supply of exchangeable ions. The exhaustion point may be defined in terms of a limiting concentration of matter in the effluent or in the case of demineralization, in terms of electrical conductivity. (See Ion Exchange, Endpoint.)

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F

Filter Specifically, a device or system for the removal of solid particles (suspended solids). In general, it includes mechanical, adsorptive, oxidizing and neutralizing filters.

Filter Area The effective area through which water approaches the filter media, often expressed in square feet.

Filter Media (See Media.)

Filtration The removal of suspended matter in water.

Fines Extremely small particles of filter media or ion exchange material formed either in the manufacturing process or as a result of breakdown; undesirable in most systems because of large pressure drops and the possible detrimental effects of such particles on research/manafactruing water use.

Flow Rate The quantity of water or regenerant which passes a given point in a specified unit of time, often expressed in gallons per minute.

Fouling The process in which undesirable foreign matter accumulates in a bed of filter media or ion exchange resin, clogging pores and coating surfaces and thus inhibiting or retarding the proper operation of the bed.

Freeboard The vertical distance between a bed of filter media or ion exchange material and the overflow or collector for backwash water, i.e., the height above the bed of granular media availabe for bed expanision during backwashing; may be expressed either as linear distance or a percentage of bed depth.

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G

GPM Gallons per minute.

GPH Gallons per hour.

GPD Gallons per day

GPG Grains per gallon. An expression of quantity of contaminate. A common basis for reporting water analysis in the United States and Canada. One grain per U.S. gallon equals 17.12 milligrams per liter (mg/L) or parts per million (ppm). One grain per British (Imperial) gallon equals 14.3 milligrams per liter or parts per million.

Grain A unit of weight equal to 1/7000th of a pound or 0.0648 gram.


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H

Hardness A characteristic of natural water due to the presence of dissolved calcium and magnesium. Water hardness is responsible for most scale formation in pipes and water heaters, and forms insoluble “curd” when it reacts with soaps. Hardness is usually expressed in grains per gallon, parts per million, or milligrams per liter, all as calcium carbonate equivalent.

Hard Water Water with a total hardness of one grain per gallon, or more, as calcium carbonate.

Head A measure of the pressure at a point in a water system, expressed in pounds per square inch, or in the height of a column of water which would produce the pressure.

Head Loss See pressure drop.

Hydration The chemical combination of water into a substance.

Hydraulic Referring to water or other fluids in motion

Hydrogen Cycle The cation exchange cycle in which the cation exchanger is regenerated with acid, and cations are remvoved from the solution being treated in exchange for hydrogen ions.

Hydrogen Ion Concentration The concentration of hydrogen ions in moles per liter of solution; often expressed as pH. (See pH.)

Hydrophobic Repelling water An example of a hydrophobic substance is teflon, which does not become wet or absorb water.

Hydrophyllic Attracting water Examples of hydrophyllic substances are sodium hydroxide and sulfuric acid, both of which attract and absorb water easily.

Hydrostatic Test A pressure test procedure in which a vessel or system is filled with water, purged of air, sealed, subjected to water pressure, and then examined for leaks, distortion and/or mechanical failure.

Hydroxide A chemical compound of an element or elements with the hydroxyl (OH) anion.

Hyprochlorite The “OCl” anion; calcium and sodium hypochlorites are commonly used as bleaches and disinfecting agents.


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I

Influent The stream entering a unit or process, such as the hard water entering an ion exchange water softener.

Inorganic Matter Matter which is not derived from living organisms and contains no organically produced carbon; includes rocks, minerals and metals.

Intermittent Flow The term usually applied to interrupted patterns of water usage; also used in reference to specific on-off flow patterns selected to test the performance of water conditioning equipment under standard conditions, which may or may not be similar to actual patterns of use of installed equipment.

Ion An atom or group of atoms which functions as a unit and has a positive or negative electrical charge due to the gain or loss of one or more electrons.

Ion Exchange A reversible process in which ions are released from an insoluble permanent material in exchange for other ions in a surrounding solution. The direction of the exchange depends upon the affinities of the ion exchanger for the ions present and the concentration of the ions in the solution.

Ion Exchanger A permanent, insoluble material which contains ions that will exchange reversibly with other ions in a surrounding solution. Both cation and anion exchangers are used in water conditioning. (See Anion, Cation and Ion.)

Iron An element often found dissolved in ground water (in the form of ferrous iron) in concentrations usually ranging from zero to 10 ppm (mg/L). It is objectionable in water supplies because of the staining caused after oxidation and precipitation (as ferric hydroxide), because of tastes, and because of unsightly colors produced when iron reacts with tannins in beverages such as coffee and tea.

Iron Bacteria Organisms which are capable of utilizing ferrous iron, extracted either from the water or from steel pipe in their metabolism and precipitating ferric hydroxide in their sheaths and gelatinous deposits. These organisms tend to collect in pipe lines and tanks during periods of low flow, and break loose in slugs of turbid water to create staining, taste and odor problems.


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K

Kilo A prefix used to indicate 1000 of the succeeding unit. (Kilo is also sometimes used as an abbreviation for kilogram).

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L

Laminar Flow The form of flow of a fluid in which the flow paths are in smooth, parallel lines with essentially no mixing and no turbulence.

Langelier’s Index A calculated number used to predict whether or not a water will precipitate, be in equilibruim with or dissolve calcium carbonate. It is sometimes erroneously assumed that any water which tends to dissolve calcium carbonate is automatically corrosive.

Leakage The presence of a consistent concentration of ions in the effluent of an ion exchange system due to incomplete removal of the ions; may be due to incomplete regeneration, excessive flow rates, low temperatures, the concentration or characteristics of the influent ions, or other factors.

Lime The common name for calcium oxide (CaO). Hydrated lime is calcium hydroxide, Ca(OH)2.

Lime Scale Hard water scale containing a high percentage of calcium carbonate.


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M

Macroreticular A term applied to ion exchange resins that have a rigid polymer porous network in which there exists a true pore structure even after drying. The pores are larger than atomic distances and are not a part of the gel structure.

Media The selected materials in a filter that form the barrier to the passage of certain suspended solids or dissolved molecules.

Membrane A soft, thin, pliable sheet or layer especially of plant or animal origin. In filtration and reverse osmosis - a synthetic material consisting of a thin or hollow fiber with specific desired properties.

Micron A linear measure equal to one millionth of a meter or 0.00003937 inch.

Micron Rating The term applied to a filter or filter medium to indicate the particle size above which all suspended solids will be removed throughout the rated capacity. As used in industry standards this is an “absolute” and not a “nominal” rating.

Microorganism A microscopic animal or vegtetative organism not visible to the human eye.


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N

Negative Head A condition of negative pressure or partial vacuum.

Negative Pressure A pressure below that of the surrounding atmospheric pressure at a specific point; a partial vacuum.

Neutralization In general, the addition of an acid or a base to a solution as required to produce a neutral pH solution. The use of alkaline or basic material to neutralize the acidity of some waters is a common practice in water conditioning.


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O

Organic Matter Substances of or derived from plant or animal matter, as opposed to inorganic matter derived from rocks and minerals.
Organic matter is characterized by its carbon-hydrogen structure.

Osmosis A process of diffusion of a solvent such as water through a semipermeable membrane which will transmit the solvent but impede most dissolved substances. The normal flow of solvent is from the dilute solution to the concentrated solution. (See Reverse Osmosis.)

Ozone An unstable form of oxygen (O3) which can be generated by an electrical discharge through air or pure oxygen. It is a strong oxidizing agent and has been used in water conditioning as a disinfectant.


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P

Permeate The stream of fluid which has passed through or permeated a reverse osmosis membrane; one of the three RO process streams - permeate, concentrate and feed.

PH The reciprocal of the logarithm of the hydrogen ionconcentration; the pH. The pH scale is from zero to 14 and 7.0 is the neutral point, indicating the presence of equal concentrations of free hydrogen and hydroxide ions. pH values below 7.0 indicate increasing acidity and pH values above 7.0 indicate increasing base concentrations.

PPB (Parts Per Billion) A fractional representation which relates an amount of a solute to an amount of solution. Example: One gram of solute per billion grams of solution equals a concentration of one ppb.

PPM (Parts Per Million) A common basis for reporting the results of water and wastewater analyses, indicating the number of parts by weight of a dissolved or suspended constituent per million parts by weight of water or other solvent. In dilute water solutions one part per million is practically equal to one milligram per liter, which is the preferred unit. 17.12 ppm equals one grain per U.S. gallon. Example: One gram of solute per one million grams of solution equals one ppm concentration.

Physical Stability A measure of the ability of an ion exchanger or filter media to resist breakdown by physical forces such as attrition, high temperatures and crushing to which it may be subjected in use.

Polisher In deionization, a column of resin which follows some form of prior treatment.

Polymer A chemical compound or mixture of compounds formed by linking large numbers of repeating structural units.

Porosity A measure of the volume of internal pores in ion exchangers and filter media, sometimes expressed as a ratio to the total volume of the medium.

Pyrogen A fragment of a gram-negative bacterial cell wall, consisting of a phospholipid combined with a polysaccharide.

Pressure Drop A decrease in water pressure during flow due to internal friction between molecules of water, and external friction due to irregularities or roughness in surfaces past which the water flows.

PSI Pounds of pressure per square inch


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R

Rated Softener Capacity A water softener capacity rating based on grains of hardness removed while producing soft water between successive regenerations, and related to the pounds of salt required for each regeneration, as determined under standard test conditions.

Regeneration In general, includes the backwash, brine and fresh water rinse steps necessary to prepare a water softener exchange bed for service after exhaustion. Specifically, the term may be applied to the “brine” step in which the sodium chloride solution is passed through the exchanger bed. The term may also be used for similar operations relating to demineralizers and certain filters.

Residual Chlorine Chlorine remaining in treated water after a specified period of contact time to provide protection throughout a distribution system; the difference between the total chlorine added and that consumed by oxidizable matter. (See Combined Available Chlorine)

Reverse Osmosis A process for the removal of dissolved ions from water in which pressure is used to force the water through a semipermeable membrane which will transmit the water but reject most other dissolved materials. (See Osmosis, Semipermeable Membrane)

Rinse That portion of the regeneration cycle of an ion exchanger in which fresh water is passed through the column to remove spent and excess regenerant, prior to placing the system in service.


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S

Salt Splitting The process in which neutral salts in water are converted to their corresponding acids or bases by ion exchange resins containing strongly acidic or strongly basic functional groups.

Scale A deposit of mineral solids on the interior surfaces of water lines and containers, often formed when water containing the carbonates or bicarbonates of calcium and magnesium is heated.

Sedimentation The process in which solid suspended particles settle out of water, usually when the water has little or no movement. Also called settling.

Semipermeable Membrane Usually a thin organic film which will allow the passage of some ions or materials while preventing the passage of others. Some membranes will only allow the passage of anions. Others will allow the passage of cations. Some membranes reject most dissolved substances but allow the passage of water. (See Reverse Osmosis.)

Single Bed Refers to the type of ion exchange system which uses separate beds of anion and cation resins.

Sodium An ion found in natural water supplies which is introduced to water in the ion exchange water softening process. Sodium compounds are highly soluble and do not react with soaps or detergents.

Sodium Chloride The chemical name for common salt, widely used in the regeneration of ion exchange water softeners.

Sodium Cycle The cation exchange process in which sodium in the ion exchange resin is exchanged for hardness and other ions in water.
Sodium chloride is the common regenerant used in this process.

Softened Water Any water that is treated to reduce hardness minerals to 1.0 gpg (17.1mg/L) or less, expressed as calcium carbonate.

Solute The substance which is dissolved in a solvent. Dissolved solids such as the minerals found in water are solutes.

Solution Feeder A mechanical device such as a power driven pump or an eductor system to feed a solution of a water treatment chemical into the water system, usually in proportion to flow. (See Chemical Feeder)

Stainless Steel 304 stainless steel is one formula of chromium and other metals used to make up stainless steel. Fairly non-corrosive, it is used where strength, beauty and reflectivity are required. High purity water tends to corrode 304 stainless steel. 316 stainless steel is one of the most corrosion resistant formulas of stainless steel. 316 stainless steel is recommended for most high purity water applications.

Sterilization A process in which all living organisms are destroyed. (See Disinfection.)

Strong Acid Resin Synthetic polymer material composed primarily of polystyrene which has ion exchange sites consisting of sulfonate (SO3) groups; regenerated with acid compound.

Strong Base Resin Synthetic polymer material composed primarily of polystyrene which has ion exchange sites consisting of an ammonium (NH4+) group; regenerated with base compound.

Suspended Solids Solid particles in water which are not in solution.


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T

Titration An analytical process in which a standard solution in a calibrated vessel is added to a measured volume of sample until an endpoint, such as a color change, is reached. From the volume of the sample and the volume of standard solution used, the concentration of a specific material may be calculated.

Total Acidity The total of all forms of acidity, including mineral acidity, carbon dioxide and acid salts. Total acidity is usually determined by titration with a standard base solution to the phenolphthalein endpoint (pH 8.3). (See Acidity)

Total Alkalinity The alkalinity of a water as determined by titration with standard acid solution to the methyl orange endpoint (pH approximately 4.5); sometimes abbreviated as “M alkalinity”. Total alkalinity includes many alkalinity components such as hydroxides, carbonates and bicarbonates. (See Alkalinity)

Total Chlorine The total concentration of chlorine in a water, including combined and free chlorine. (See Combined Available Chlorine)

Total Dissolved Solids The weight of matter in true solution in a stated volume of water; includes both inorganic and organic matter; usually determined by weighing the residue after evaporation of the water at 105°C or 180°C.

Total Hardness The sum of all hardness constituents in a water, expressed as their equivalent concentration of calcium carbonate;. primarily due to calcium and magnesium in solution, but may include small amounts of metals such as iron which can act like calcium and magnesium in certain reactions. (See Hardness)

Turbidity A measure of the amount of finely divided suspended matter in water which causes the scattering and absorption of light rays. Turbidity is usually reported in arbitrary units determined by measurements of light scattering.

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