Dow Liquid Separations

DOWEX Exchange Resins and FILMTEC Membranes

Glossary of Terms and Acronyms Glossary of Terms and Acronyms

A B Bed warm-up: The step just prior to A-value: Membrane water B-value: Salt diffusion coefficient. regenerant injection where hot dilution water is added to the resin bed to heat permeability coefficient. Backwashing: The upward flow of the bed to the appropriate temperature. water through an resin Adapter: Cylindrical piece of plastic or This is to enhance polymerized silica bed to remove foreign material, metal that connects the product water removal. tube of the element to the permeate reclassify the bed after exhaustion and piping of the water distribution system. prior to regeneration in co-current Biofilm: Growth of bacteria, algae, fungi, viruses and higher organisms on Adsorption: The attachment of regenerated units. Also used to reduce compaction of the bed. the membrane surface resulting in a compounds to the chemically active film that is difficult to remove. groups on the surface and in the pores Backpressure: See permeate of an ion exchange resin. backpressure. Biofouling: Degradation of RO/NF system performance due to formation Bank: See RO train. Air mixing: The process of mixing two of biological deposits by organisms ion exchange materials of different exchange: The exchange of present in the feed to the RO/NF densities in a water slurry with air to cations between a solution and cation system or in the system itself. yield a homogeneous mixed bed. exchange resin. Boiler feed water: Water used in Alkalinity: Alkalinity may exist in three Batch operation: A method of steam boilers and some industrial forms: caustic (or hydroxide), utilizing ion exchange resins in which processes. Boiler feed water may carbonate and bicarbonate. Alkalinity the resin and the solution to be treated possibly be raw water, treated water, is commonly expressed as “P” and “M” are mixed in a vessel and the liquid is condensate or mixtures, depending on in parts per million (ppm) as calcium decanted or filtered off after the need. carbonate (CaCO3). “P” represents the equilibrium is attained. with a standard acid solution Booster pump: Pump installed Batch process: Discontinuous to a phenolphthalein end point. “M” between two stages of an RO system, processing of liquids, usually used for represents the titration to a methyl enabling to raise operating pressure for relatively small volumes. orange end point. These values are the subsequent array. used to calculate the caustic, Bead count: The evaluation of an ion Boundary layer: Layer adhering to the carbonate and bicarbonate alkalinities. exchange resin contained in a column membrane facing the feed/concentrate Standard practice assumes that (i) or operating unit. water. titration to a “P” end point determines Bed: The ion exchange resin Brackish water: (1) Water from a all caustic and one-half of carbonate contained in a column or vessel (see surface or ground water source with a alkalinity and, (ii) titration to an “M” end exchanger bed). salt content of less than 5,000-15,000 point measures the sum of Bed depth: The depth of ion ppm. (2) The ASTM definition is: water bicarbonate, carbonate and caustic exchange resin in a column or vessel. that contains dissolved matter at an alkalinity. Bed expansion: The separation and appropriate concentration range from Ammonia cycle: Cation exchange rise of ion exchange resin beads in a 1000 to 30000 mg/liter. resin operation in which the resin is column or vessel during backwashing. Breakthrough: That volume of effluent run past the ammonia break. Bed volume: The volume of ion where the concentration of the Antiscalant: See scale inhibitor. exchange material of specified ionic exchanging ion in the effluent reaches Anti-telescoping device (ATD): The form contained in a column or a predetermined limit. This point is ATD is a part of the end cap and operating unit, usually measured as usually the limit of the exhaustion cycle keeps the envelopes in place. This the backwashed, settled and drained and the beginning of the regeneration inhibits telescoping. volume. cycle. Array: The series and/or parallel Bed volume per hour: The measure Brine: (1) Water that contains arrangement of pressure vessels of the volume flow-rate through an ion dissolved matter at an approximate within a reverse osmosis or exchange material contained in a concentration of more than 30,000 nanofiltration system. column or operating unit, expressed ppm. (2) See concentrate. 3 3 3 Attrition: The breakage and abrasion as BV/hr, m /hr/m or gals/min/ft . Brine seal: Ring made from flexible of resin beads. plastic material placed on element end cap in order to prevent flow bypass around the outside of an element.

*Trademark of The Dow Chemical Company

2 C Colloidal fouling: Deposition of colloids Cross-linkage: Binding of the linear CADIX: Computer Aided Design of Ion on the membrane surface resulting in polymer chains in the matrix of an ion eXchange systems. A computer losses in system performance. exchange resin with a cross-linking software for designing ion exchange Colloids: Extremely small particles agent that produces a three- resin plants. which are not removed by normal dimensional, insoluble polymer. Capacity: The number of equivalents filtration. of exchangeable ion per unit volume, Color throw: The imparting of color D unit wet weight, or dry weight of an ion from an ion exchange resin to a liquid. Dalton (D): Alternative unit for the exchange material in specified ionic Column operation: The most common indication of the molecular weight of a form. method for employing ion exchange in compound. 1D = 1 g/mol. Carboxylic: A term describing the which the liquid to be treated passes Deaerator: See degasifier, vacuum. functionality of weak acid cation through a fixed bed of ion exchange exchange resins. resin. Dealkalization: A weak acid cation or alternatively an anion exchange Caustic soda: Also simply called Composite membrane: Membrane process for the removal or reduction of caustic. This is the chemical sodium obtained precipitating a thin alkalinity in a water supply. hydroxide (NaOH) which is used to desalinating layer an a porous carrier regenerate anion exchange resins. membrane. Decationization: The exchange of cations for hydrogen by a strong Channeling: The creation of isolated Concentrate: The residual portion of acid cation exchange material in the paths of lower resistance in an ion an aqueous solution applied to a hydrogen form (see salt splitting). exchange resin bed caused by the membrane, containing the retained introduction of air pockets, dirt or other salts. Also called retentate or brine. Decrosslinking: The alteration of the factors which result in uneven pressure ion exchange structure by degradation Concentration factor: CF is the ratio of the cross-linkage by aggressive gradients in the bed. Channeling of the feed quantity (or feed stream) prevents the liquid being processed chemical attack or heat. This causes over the concentrate quantity (or increased swelling of ion exchange from uniformly contacting the entire concentrate stream). resin bed. materials. Concentration polarization: The Degasifier, forced air: Also called a Chemical stability: The ability of an development of a concentration ion exchange resin to resist changes in decarbonator. Used to reduce carbon gradient of the retained components dioxide content of the effluent from its physical properties when in contact across the boundary layer near the with aggressive chemical solutions hydrogen cation exchangers. Reduces membrane surface. See also CO to about 5-10 ppm but saturates such as oxidizing agents. Also the concentration polarization ratio. 2 ability of an ion exchange resin to water with air. Condensate polisher: The use of a resist inherent degradation due to the Degasifier, vacuum: Actually a cation resin or mixed bed unit to chemical structure of the resin. deaerator. Reduces oxygen as well as remove impurities from condensate. Chloride anion dealkalization: An CO2 and all other gases to a very low Conductivity or specific anion exchange system that is level. Preferred as a means of CO2 conductance: The ability of a current regenerated with salt and caustic and reduction when demineralizing boiler to flow through water as a measure of exchanges chloride ions for water makeup. Eliminates water its ionic concentration, measured in bicarbonate and sulfate ions in the pollution and reduces micromhos/cm or microSiemens/cm. water being treated. problems when transferring water Configuration: See membrane through steel equipment. Use usually Classification: Obtained by configuration. results in longer anion exchange resin backwashing an ion exchange resin life. bed to obtain a bed which is graduated Contact time: The amount of time in resin bead size from coarse on the which the process liquid spends in the Degradation: The physical or chemical bottom to fine on the top. ion exchange bed, expressed in reduction of ion exchange properties minutes. Determined by dividing the due to type of service, solution Clumping: The formation of bed volume by the flow rate, using concentration used, heat or aggressive agglomerations in an ion exchange bed consistent units. operating conditions. Some effects are due to fouling or electrostatic charges. capacity loss, particle size reduction, Counter-current or Counter-flow Co-current or Co-flow operation: Ion excessive swelling, or any combination operation: An ion exchange operation exchange operation in which the of the above. in which the process liquid and process water and regenerant are regenerant flows are in opposite passed through the bed in the same directions. direction, normally downflow.

3 Deionization: The removal of Double pass RO system: RO System Exhaustion: The step in an ion ionizable (soluble) constituents and in which the permeate is further exchange cycle in which the undesirable silica from a solution by ion exchange desalinated by a subsequent RO ions are removed from the liquid being processing. Normally performed by System. processed. When the supply of ions on passing the solution through the DVB copolymer: A polymer containing the ion exchange resin being exchanged hydrogen form of cation exchange styrene (vinyl benzene) cross linked for the ions in the liquid being processed resin and through the hydroxide form with divinylbenzene. is almost depleted, the resin is said to of an anion exchange resin, either as a be exhausted. two-step operation or as an operation in which a single bed containing a E F mixture of the two resins is employed. Eductor: A device that, by flow of Fast rinse: That portion of the rinse Deionized water: When all of the ionic water through it creating a vacuum, which follows the slow rinse; usually constituents dissolved in water are draws a solution into the water stream. passed through the ion exchange bed removed by ion exchange, the water is Effective size: The particle size at the service flow rate. said to be deionized. Cation and anion expressed in millimeters which exchange resins, when properly used, represents 90 percent of the ion Feed: The liquid entering ion will deionize water. exchange material from a screen exchange or RO/NF system. Delamination: When the active layer analysis. Feed channel: Spacer filled channel peals off from the polyester support Efficiency: A measure of the quantity (see feed channel spacer) of about web as a consequence of mechanical of regenerant required to effect the 25-60 mil (0.6-1.5 mm) height that or chemical membrane damage. removal of a chemical equivalent allows the water to travel through the spiral wound RO element. Demineralization: See deionization. weight of contaminant in the influent water. For a sodium softener, this will Feed channel spacer: Web or screen Density: The weight of an ion usually be expressed as pounds of salt placed between two leaves of exchange material usually expressed per kilograin or kg salt per equivalent membrane that supports the membrane as g/l or lbs/ft3. of hardness removed. leaves and allows the water to pass Desalination: The removal of Effluent: The solution which emerges from the feed to the concentrate end of dissolved salts from a solution. from an ion exchange column or a spiral wound RO element. Diffusion: The process whereby ions, vessel. shell: Epoxy wrapping atoms, and molecules move in a mix. Electronegativity: A measurement of applied around envelope bundle The movement is random, with the net the relative attraction an atom has for supplying mechanical support. effect being movement from a higher electrons. Fibertape wrapping: Tape wrapping concentration zone to a lower applied around envelope bundle concentration zone until the zones Eluate: The solution resulting from an supplying mechanical support. have equalized. elution process. Film diffusion: The movement of ions Dissociate: The process of ionization Elution: The stripping of sorbed ions through the liquid film on the surface of of an electrolyte or a salt upon being from an ion exchange resin by passing an ion exchange particle. dissolved in water, forming cations and solutions containing other ions in anions. relatively high concentrations through Fines: Small particles of an ion the resin column. exchange resin which are undesirable. Distributor: The piping inside an ion exchange vessel which evenly Envelope: See membrane envelope. Flatten: To exhaust a resin bed (see distributes flow across the resin bed. Epoxy wrapping: See fiberglass shell. exhaustion). Divinylbenzene (DVB): A di-functional Exchange sites: The reactive groups Fouling: (1) In ion exchange, this monomer used to cross-link polymers. on an ion exchange resin. refers to any relatively insoluble deposit or film on an ion exchange Downflow: The operation of an ion Exchanger bed: Ion exchange resin material, which interferes with the ion exchange column in which the contained in a suitable vessel; and exchange process. (2) In RO and NF, regenerant enters the top of the ion supported by material, such as graded this refers to the deposition of foreign exchange column and is withdrawn gravel, screen wrapped pipe, or matter on the membrane surface from the bottom. This is the perforated plate, which also act as and/or in its pores, resulting in conventional direction of water flow in liquid distribution systems. changed element and/or system a co-current operated ion exchange performance. The different types of column. fouling are scaling, colloidal fouling, organic fouling and biofouling.

4 Fouling factor (FF): Ratio of permeate Glue line: Line at which two pieces of Hydrogen cycle: Cation exchange flow after substantial fouling has membrane leaf are glued together in resin operation in which the occurred to permeate flow at system order to form a membrane envelope. regenerated ionic form of the resin is start-up. When designing an RO Grains per gallon: The concentration the hydrogen form. system, the fouling factor enables of ions in solution usually expressed in Hydrometer: An instrument used for taking into account potential fouling terms of calcium carbonate measuring the relative density (specific processes. equivalents. One grain per gallon is gravity) of liquids. Fouling-resistant membrane equal to 17.1 ppm. Hydroxide cycle: An anion exchange element: Modified surface chemistry Greensands: Naturally occurring operation in which the regenerated and modified element design of this materials which possess ion exchange form of the ion exchange material is in membrane element type make it the properties. Greensand was the first ion the hydroxide form. optimum choice to cope with high exchange material used in softeners. fouling tendency waters. I Free mineral acidity (FMA): Free H mineral acidity is due to the presence Influent: The solution entering an ion of acids such as sulfuric, nitric, and Hardness, total: In conformity with exchange column or vessel. hydrochloric. current practice, total hardness is Inhibitor: Additive able to suppress defined as the sum of calcium and Freeboard: The space provided above biological and chemical processes. magnesium concentrations, both the resin bed in the vessel to Examples are scale inhibitors, growth expressed as calcium carbonate in accommodate the expansion of the inhibitors, corrosion inhibitors. milligrams per liter. resin particles during the backwashing Interconnector: Piece of plastic used operation. Head loss: The loss in liquid pressure to connect the product water tube of resulting from the passage of the FT30: Membrane chemistry upon various membrane elements within the solution through the bed of ion which most FILMTEC membrane same pressure vessel. exchange resin (also known as elements are based. Interstitial volume: The space pressure drop). Full-fit element: A full-fit element is a between the particles in an ion Hollow fiber (HF) element: This spiral-wound membrane element exchange resin bed. element type consists of a membrane designed to minimize or eliminate Ion exchange: The process by which that has been extruded into a hollow stagnant areas. Like all membrane ionic impurities in water are attached to tube with a bore of 0.05-0.2 mm (2-10 elements it has an outerwrap, but active groups on and in an ion mil) in its center. Hollow fiber elements rather than tape or fiberglass, a rigid exchange resin and more desirable offer highest surface area to volume polypropylene material gives the ions are discharged into water. ratio but are very prone to element structural support. deterioration by scaling and fouling. Ionic strength: The ionic strength is Fulvic acid: A high molecular weight defined as half of the sum of the Hot Zeolite softener: A sodium zeolite polycarboxylic acid often found in product of ion concentrations and the softener operated at a temperature of surface water supplies. It frequently square of their charges. 100-120¡C (215-250¡F). This unit will contributes to organic fouling of ion follow a hot lime softener. Ionization: The separation of part or exchange materials. all of the solute molecules into positive Humic acid: A high molecular weight Functional group: The atom or group (cationic) and negative (anionic) ions in polycarboxylic acid found in surface of atoms on an ion exchange resin a dissociating media such as water. water supplies which contributes to which give the resin its specific organic fouling in ion exchange Iron: Iron is often present in ground chemical characteristics. materials. waters in a reduced, soluble form (such as ferrous bicarbonate) in Hydraulic classification: The quantities usually ranging from 0.5 to G tendency of small resin particles to rise 10 ppm. Iron in solution is susceptible Gel: A term applied to the bead to the top of, and large resin particles to oxidation, precipitating as a reddish- structure of certain ion exchange resins to settle to the bottom of the resin bed brown floc when contacted by air which have a microporous matrix during a backwash operation. under normal well water conditions. structure with small pores generally Hydrogen cation exchanger: Term <10Å. Gel resins offer good operating used to describe a cation resin capacity and regeneration efficiency. regenerated with acid to exchange Porous gel resins also exhibit good hydrogen (H+) ions for metal cations. resistance to organic fouling.

5 L M Microfiltration: Pressure-driven Langelier Saturation Index (LSI): Macroporous: A term applied to the membrane process used to retain An index calculated from total dissolved bead structure of certain ion exchange particles with a minimum diameter of solids, calcium concentration, total resins which have a tough, rigid about 0.2 micron (8 mil). Frequently alkalinity, pH and solution temperature structure with large discrete pores. used as a pretreatment to RO that shows the tendency of a water The macroporous resins offer good systems. solution to precipitate or dissolve resistance to physical, thermal and Mixed bed: The use of a mixture of

CaCO3. Should be used for the low osmotic shock and chemical oxidation. cation and anion resins in the same TDS range, in the high TDS range, the Macroporous anion resins also exhibit column or vessel to produce water of Stiff & Davis saturation index (S&DSI) good resistance to organic fouling. extremely high quality. should be used. Macroreticular: See macroporous. Modified Fouling Index (MFI): Layered bed: Two ion exchange Membrane: A thin sheet separating Measure for the fouling potential of a materials with weak and strong different streams, which contains water. See also silt density index (SDI). functionality (e.g., weak and strong active groups that have a selectivity for Module: Pressure vessel containing anion resins) designed with sufficient anions or cations but not both. membrane element(s). difference in density and hydraulic Membrane configuration: (1)The Molality: The number of gram- characteristics to be layered in the same arrangement of individual elements molecules weight of a solute per kg of vessel, in place of two separate vessels. and/or pressure vessels in a RO or solvent. Leaf: See membrane leaf. nanofiltration plant. (2) Way in which Molarity: The number of gram- Leaf length: Length of a membrane the membrane sheet is arranged in a molecules weight of a solute per I of leaf in a spiral wound element. Should practical system. By far the most solution. be minimized in order to assure common RO configuration is the spiral Molecular weight cut-off (MWCO): homogeneous permeate flux wound element, other common Nominal measure of the separation distribution over membrane leaf. configurations involve plate-and-frame, potential of a membrane, defined as hollow fiber and tubular. Leakage (hardness, sodium, silica, the molecular weight, of which etc.): Caused by incomplete Membrane envelope: A membrane 90 percent of the molecules are regeneration of an ion exchange bed. envelope consists out of two sheets of retained by the membrane. Since complete regeneration is usually membrane separated by the permeate Monomeric silica: The simplest form inefficient, most ion exchange spacer. In a spiral wound element, the of silica (often described as SiO ) and processes operate at one half to one membrane envelope connects to the 2 referred to as dissolved or reactive third of the total capacity of the ion product water tube; all other ends are silica. exchanger. sealed off by a glue line. Nanofiltration (NF): Pressure-driven Low energy membrane element: Membrane leaf: (1) Alternatively for membrane process, similar to RO, but Membrane element designed to have membrane sheet. (2) Alternatively for with higher molecular weight cut-off lowest possible energy consumption membrane envelope. and lower operating pressure. and highest possible rejection. Membrane performance: The two Nonionic: Compounds that do not Lubrication: The application of main performance parameters for have a net positive or negative charge. grease-type materials to components spiral wound membrane elements are of an RO systems. The lubrication of rejection and flow. interconnectors (with silicone grease Membrane salt passage: SPM is O Dow Corning 111) supports the sealing the concentration of a compound in O-ring: Ring from flexible plastic functionality of the o-rings; lubrication the permeate related to its average material placed on the inner or outer of the pressure vessel (with glycerin) concentration an the feed/concentrate diameter of the interconnector in order supports smooth loading of membrane side. to seal the product water off from the elements into the vessel. Membrane sheet: Flat sheet of brine. membrane consisting of polyester Ohm: The unit of resistance of a support web, polysulfone interlayer solution, often related to the electrolytic and active polyamide barrier. concentration.

6 Operating capacity: The portion of the Permeate: The Portion of the feed Polar: A molecular property in which total exchange capacity of an ion which Passes through the membrane, the positive and negative electrical exchange resin bed which is utilized in also called product. charges are permanently separated. a practical ion exchange operation. Permeate backpressure: Pressure Polar molecules ionize in solution and Commonly expressed in kilograins per applied to the permeate side of an RO impart electrical conductivity. 3 cubic foot (kgr/ft ) or equivalents per system, either resulting from design of Polarity: A molecular property in liter (eq/l). permeate piping and permeate tank, or which the positive and negative Operating cycle: A complete ion applied by closing permeate valve in electrical charges are permanently exchange process consisting of a order to reduce net driving pressure in separated. backwash, regeneration, rinse, and first array. Polisher: A mixed bed ion exchange service run. Permeate channel: Spacer filled unit usually installed after a two bed Organic fouling: (1) In ion exchange, channel (see permeate channel deionizer system to remove the last the condition where a significant spacer) between two membrane traces of undesirable ions. amount of organic molecules remain in leaves that allows the permeate to Polymeric silica: The larger molecular the beads following a normal travel to the product water tube. weight silica compounds which are a regeneration. (2) In RO/NF systems, Permeate channel spacer: Web or result of the chemical polymerization of this refers to the deposition of organic screen placed between two leaves of monomeric silica. molecules on the membrane surface membrane that supports the Porosity: Used qualitatively to resulting in losses in system membrane leaves and allows the describe that property of an ion performance. product water to exit from the exchange resin which allows solutes to Organic matter: Organic matter is membrane leaves to the product water diffuse in and out of the resin particle. present in many ground and surface tube of a spiral wound element. It is usually used with regard to large waters. It may come from natural Permeate collector fabric: See ions and molecules such as organic sources such as swamps and be permeate channel spacer. acids. Porosity is directly related to the visible as color. Pollution by industrial Permeate flux: Permeate flow rate water content and inversely related to wastes and household detergents are per unit membrane area. the cross-linkage of a gel resin. other sources of organic matter. Permeate staged system: RO Potable water: Water meeting Health Osmosis: Phenomenon of solvent flow system where the permeate is Department standards for use as occurring between two cells containing subjected to more than one passes drinking water. These waters may be solutions with different solute through an RO membrane. hard, and may contain considerable concentration separated by a salts in solution. membrane that is permeable to the Permeate water carrier: See Pressure drop: (1) In membrane solvent and impermeable to the solute. permeate channel spacer. operations, the pressure drop pH: The negative logarithm (base 10) Osmotic shock: The expansion or (differential pressure) results from of the hydrogen ion concentration in contraction of resin beads due to frictional pressure losses when the water. volume changes imposed by repeated water flows through a membrane applications of dilute and concentrated Physical stability: The ability of an element, a stage, or the entire system. solutions. ion exchange resin to resist breakage (2) For ion exchange systems, see Osmotic stability: The ability of an ion caused by physical manipulation or by head loss. volume changes due to either osmotic exchange material to resist physical Pressure vessel: The vessel shock or iteration between two or more degradation due to osmotic shock. containing the individual elements. ionic forms. Pretreatment: Includes flocculation, Plant capacity: Production of P settling, filtration or any treatment permeate per unit time, expressed as water receives prior to an ion Particle diffusion: The movement of m3/day or m3/h (GPD, MGD). ions within the ion exchange material exchange or reverse osmosis system. Plate and frame configuration: In toward exchange sites. Process water: Any water mixed with a plate-and-frame configuration, the RO product, or becoming part of a product or Performance: See membrane or NF membrane is stacked between used to wash a product. These supplies performance. plates along with spacers that allow require various kind of treatment such as Permeability: The ability of an ion feed water in and permeate water out. clarification and filtration, and in many exchange membrane to pass ions cases ion exchange resins are used to under the influence of an electric soften, dealkalize or completely deionize current. the water.

7 Product water: See permeate. Rejection: The ability of an RO/NF Saturation level: The ion product of Product water tube: Perforated hollow membrane/system to hinder solutes dissolved material in a solvent to its tube around which the membrane from passing through the membrane. solubility. A material with a saturation leaves are wound spirally. Permeate Mathematically, it is the quantity of level higher than 100 percent tends to exits from the permeate channel solutes in the feed water subtracted precipitate and form deposits. spacer to the product water tube and is from the quantity of solutes passing Scale inhibitor: Chemical additive collected from there. through a semipermeable membrane, able to suppress the formation of which is then divided by the quantity of inorganic scales from supersaturated solutes in the feed water, typically solutions. Q expressed as a percentage. Scaling: Deposition of solids an the Quaternary ammonium: A term Retentate: See concentrate. membrane surface, due to exceeding describing the functionality of strong Reverse osmosis: A pressure-driven the solubility product of the salt in base anion exchange resins. membrane operation in which the question. solvent is transferred through the Scavenger: A polymer matrix or ion R membrane and the dissolved solutes exchange material used to specifically Raw water: Untreated water from are retained by the same membrane. remove organic species from the wells, surface sources or the sea. Rinse: The passage of water through process liquid before the solution is Reactive silica: See monomeric silica. an ion exchange resin bed to flush out deionized. excess regenerant. Recovery (Y): (1) The ratio of product Seawater: Water from oceans, quantity (or stream) over the feed ROSA: Reverse Osmosis System continental seas and nearby wells, with quantity (or stream), given as fraction Analysis, software program enabling to a TDS of about 25,000 to 60,000 ppm. or in percent. (2) Increasing the design reverse osmosis and Selectivity: The difference in concentration of precious solutes in a nanofiltration systems. attraction of one ion over another by solvent with membrane processes in RO train: One of two or more an ion exchange resin. order to recycle them. complete RO installations operating in Semipermeable membrane: A Regenerant: The chemical used to parallel. membrane that is permeable to certain convert an ion exchange resin to the Run length or run time: The time compounds and impermeable to other desired ionic form for reuse. between regenerations or the duration compounds. Most practically used RO Regeneration: The displacement from of the service cycle. membranes have a high permeability the ion exchange resin of the ions for water and a very low permeability for most solutes. removed from the process solution. S May be performed either co-currently Sheet: See membrane sheet. Salt rejection: The ability of an RO/NF or counter-currently. Lower ion membrane/system to hinder solutes Shimming: The placement of shims leakages are typically obtained with from passing through the membrane. on the adapter within the vessel counter-current regeneration at Mathematically, it is the quantity of minimizes movement of the individual comparable regenerant dosages. solutes in the feed water subtracted membrane elements. This reduces Regeneration efficiency: A measure from the quantity of solutes passing wear-out and mechanical abrasion and of the amount of capacity of an ion through a semi-permeable membrane, subsequent o-ring leakage. exchange resin compared to the which is then divided by the quantity of Silica: Silica is present in most water amount of regenerant applied. This is solutes in the feed water, typically supplies. Well waters usually contain expressed as a ratio of equivalents of expressed as a percentage. silica in solution while surface waters capacity to equivalents of regenerant Salt splitting: The conversion of salts may contain soluble, colloidal and and is therefore <100 percent. It is the to their corresponding acids or bases suspended silica. reciprocal of Stoichiometry. by passage through strong acid cation Silt Density Index (SDI): Measure for Regeneration level: (Regeneration or strong base anion exchange resins, the fouling potential of a water, Dosage) The amount of regenerant respectively. measured by filtering a water sample used per cycle. Commonly expressed Saturated: The maximum amount of a through a micron filter. In RO systems, in pounds per cubic foot of resin or substance that can be dissolved in a SDI should be maintained at or below 5. grams per liter of resin. solvent. Slow rinse: That portion of the rinse which follows the regenerant solution and is passed through the ion exchange material at the same flow rate as the regenerant.

8 Sluicing: A method of transporting Strong acid capacity: That part of the System salt passage: SPS is the resin from one tank to another with total cation exchange capacity that is concentration of a compound in the water. This is usually found in mixed capable of converting neutral salts to permeate related to its concentration in bed deionization systems with external their corresponding acids (also called the feed water; also called apparent regeneration systems. salt splitting capacity). salt passage. Sodium cation: Cation exchange Strong acid cation resin: Resins resin, regenerated with salt (NaCl). employed in softening and T Exchanges sodium ions (Na+) for the deionization systems. When Telescoping: (1) Length-wise metal cations (Mg++, Ca++, etc.), regenerated with salt, the sodium ions displacement of the membrane inside forming sodium salts (sulfates, on the resin will effectively exchange the RO element. (2) Central product carbonates, etc.). for divalent cations such as calcium water tube and membrane envelopes and magnesium. When regenerated Spacer: A sheet of woven fabric (also are pushed outwardly and unravel as a with sulfuric or hydrochloric acid the called web or screen) placed between consequence of high pressure drop resin will split neutral salts converting two leaves of membrane supporting and/or high cross-flow velocity. the membrane leaves and providing the salt to its corresponding acid. The Tertiary ammonium: A term grooves (channels) for water to travel resin usually receives its exchange describing the functionality of weak between the membrane sheets. See capacity from sulfonic groups. base anion exchange resins. also feed channel spacer and Strong base anion resin: Resins permeate channel spacer. employed in chloride anion Tertiary effluent: Waste water from municipal water treatment plant. Has Specific gravity: The picometric dealkalizers and deionization systems. undergone sedimentation, biological density of the resin material expressed When regenerated with salt, the treatment and advanced particle as grams per unit volume in a specific chloride ions will exchange for removal steps such as clarification and ionic form. bicarbonate and sulfate anions. When regenerated with caustic soda, the filtration. See also waste water. Sphericity: A measure of the amount resin will remove both strong and Throughput: The amount of product of ion exchange resin beads that are weak acids from cation exchange resin water generated during the service unbroken. effluent. The resin usually receives its cycle. Spiral wound (SW) element: exchange capacity from quaternary Total capacity: The maximum Configuration, in which the membrane ammonium groups. exchange ability of an ion exchange sheet is wound spirally around the Strong base capacity: That part of resin. product water tube, resulting in a the total anion exchange capacity configuration with very high surface Total dissolved solids (TDS): The capable of converting neutral salts to area per volume ratio and low fouling concentration of dissolved matter in their corresponding bases (also called tendency. water. salt splitting capacity). Stiff & Davis Saturation Index Train: A single ion exchange system STY/DVB copolymer: A polymer (S&DSI): Measure for the saturation of capable of producing the treated water containing styrene (vinyl benzene) CaCO in high salinity waters. Should desired, such as a strong acid cation 3 cross-linked with divinylbenzene. be used for waters with a TDS higher resin bed followed by a strong base than 10,000 ppm; in the low TDS Sulfonic: A term describing a specific anion resin bed, with multiple trains range, the Langelier saturation index group that imparts a strongly acidic being duplicates of the single system. (LSI) should be used. exchange ability to some cation resins. Tubular membrane element: A Stoichiometry: A measure of the Support media: A graded particle tubular element consists of a piece of quantity of regenerant required size, high density material such as membrane on the inside of a fiberglass compared to the resultant capacity of gravel, anthrafil, quartz, etc. Used to tube with internal diameter of about the ion exchange resin. This is support the resin bed. 0.5" (about 1 cm). expressed as a ratio of equivalents of Surface water: Water taken directly Turbidity: The reduction of regenerant to equivalents of capacity from surface sources such as rivers, transparency of a sample due to the and is therefore >100 percent. It is the lakes and seas. presence of particulate matter. reciprocal of Regeneration Efficiency. Stratified bed: See layered bed.

9 U Water retention: The amount of water, Ultrafiltration: Pressure-driven expressed as a percent of the wet membrane process used to retain weight, retained within a fully swollen macro solutes with a minimum and drained ion exchange material. molecular weight of 1000-1500 Dalton. Water softening: To exchange Frequently used as a pretreatment to sodium for the hardness in water by RO systems. ion exchange. Under drain: The piping inside an ion Weak acid cation resin: These resins exchange vessel which evenly collects are used in dealkalization and the treated water after it has passed desalination systems and in through the resin bed. conjunction with strongly acidic cation Uniformity coefficient: The volume resins for deionization. When or weight ratio of the 90 percent regenerated with acid, the resin will retention size (see effective size) and split alkaline salts converting the salt the 40 percent retention size in a to carbonic acid. This resin exhibits screen analysis. very high regeneration efficiency. It usually receives its exchange capacity Upflow: The operation of an ion from carboxylic groups. exchange column in which the regenerant enters the bottom of the ion Weak base anion resin: These resins exchange column and is withdrawn are employed for partial deionization from the top. Regeneration efficiency when silica removal is not required or and column leakage may be improved used in combination with strong base by this process. anions to provide high capacity and chemical efficiency in full deionization operation. When regenerated with V soda ash, ammonia or caustic soda, Valence: The number of positive or weak base resin will adsorb strong negative charges of an ion. acids such as hydrochloric and sulfuric Void volume: See interstitial volume. acids (FMA) from the cation bed effluent. The resin is usually Volume mean diameter: The particle functionalized with tertiary amine size expressed in microns or groups. millimeters at which 50 percent by volume of the ion exchange material Well water: Generally this type of from a screen analysis has passed. water refers to water from a ground water source that has been accessed via a well. When the well is close to a Waste water: Water discharged from a surface water, then significant portions process as a result of its formation or of the water obtained may be its use in that process. provenient from that water source. Water carrier: See spacer, feed channel spacer, permeate channel Z spacer. Zeolite: A mineral composed of Water hammer: Mechanical stress on hydrated of aluminum, and membrane element in pressure vessel sodium or calcium. The term is that occurs when feed flow and commonly used in connection with pressure are increased too sharply. water softening by ion exchange (i.e., May cause telescoping and cracking zeolite softener, hot lime zeolite, etc.). of element outer wrap.

10 Acronyms Common to Ion OF: organic fouling Exchange and Membranes OS: organic scavenger A&E: architect & engineer ppb: Unit of concentration, parts ASTM: American Society for Testing per billion, equal to 1µg/L and Materials ppm: Unit of concentration, parts ATD: Anti-telescoping device per million, equal to 1 mg/L AVT: all volatile treatment PSI: pounds per square inch BVH: Bed Volumes per Hour PSIG: pounds per square inch gauge BWR: boiling water reactor PWR: pressurized water reactor CAC: Combined Available Chlorine RO: reverse osmosis CIP: Cleaning-in-place SAC: strong acid cation CP: condensate polishing SBA: strong base anion CRC: Combined Residual Chlorine SBS: Sodium bisulfite D: Dalton SDI: Silt Density Index Degas: degasifier S&DSI: Stiff and Davis Saturation Index Demin: demineralization SHMP: DVB: divinylbenzene SMBS: Sodium meta bisulfite FAC: Free Available Chlorine Spec: specification FB: Free base SSC: salt splitting capacity FF: Fouling factor SW: Spiral wound or Sea Water FMA: Free Mineral Acidity TBC: Total Bacteria Count FRC: Free Residual Chlorine TDS: Total dissolved solids, usually GAC: Granular Activated Carbon expressed as mg/I or ppm GPM: gallons per minute (Parts per million) GrPG: grains per gallon TEC: total exchange capacity HF: Hollow fiber TOC: Total organic carbon IX: ion exchange TRC: Total Residual Chlorine Kgr: Kilograins TSS: Total suspended solids LSI: Langelier Saturation Index UPS: uniform particle size ME: microscopic examination UPW: ultra pure water MFI: Modified fouling index URC: Ultrasonic Resin Cleaned MWCO: Molecuar weight cut-off WAC: weak acid cation NF: Nanofiltration WBA: weak base anion OEM: original equipment WBC: weak base capacity manufacturer WRC: water retention capacity

11 Dow Liquid Separations Offices. For more information call Dow Liquid Separations:

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Warning: Oxidizing agents such as nitric acid attack organic ion exchange resins under certain conditions. This could lead to anything from slight resin degradation to a violent exothermic reaction (explosion). Before using strong oxidizing agents, consult sources knowledgeable in handling such materials. Notice: No freedom from any patent owned by Seller or others is to be inferred. Because use conditions and applicable laws may differ from one location to another and may change with time, Customer is responsible for determining whether products and the information in this document are appropriate for Customer’s use and for ensuring that Customer’s workplace and disposal practices are in compliance with applicable laws and other governmental enactments. Seller assumes no obligation or liability for the information in this document. NO WARRANTIES ARE GIVEN; ALL IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY EXCLUDED. Published August 2000.

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