Glossary of Terms

Glossary of Terms - C

A :B :C :D :E :F :G :H :I :J :K :L :M :N :O :P :Q :R :S :T :U :V :W :X :Y :Z :


Cellulose acetate
Carcinogen Assessment Group
A structure or chamber in water well construction which is usually sunk or lowered by digging from the inside. Used to gain access to the bottom of a stream or other body of water.
1. Calcium carbonate (CaCO3). 2. A trade name for finely ground grades of marble or limestone, very high in calcium carbonate, which are used to raise the pH reading (reduce the acidity) of low pH (acidic) water or to filter out sediment. See Also: Hardness as Calcium Carbonate Calcium Carbonate Carbonate Hardness Bicarbonate Hardness Hardness Hardness as Calcium Carbonate Plastic Pipe Calcium Carbonate Total Hardness (TH) Soda Ash
One of the principal elements (Ca) 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 a means of clearly identifying hard water.
[CaCO3] A chemical compound found in nature as calcite (in limestone, marble, and chalk) and aragonite (in pearls) and in plant ashes, bones, and many shells. See Also: Calcite Hardness as Calcium Carbonate Calcite Carbonate Hardness Bicarbonate Hardness Hardness Hardness as Calcium Carbonate Plastic Pipe Total Hardness (TH) Soda Ash Hardness as Calcium Carbonate
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.
[CaCl2] A soluble salt, some uses of which are similar to those of sodium chloride. Since its most striking property is its ability to draw moisture from the air and so dissolve itself, it is often used as an air dryer and as a de-icing salt.
SEE hydrated lime
Hydrated lime
A chemical compound, [Ca(CLO)24H2O]; 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.
SEE lime
A procedure which checks or adjusts an instrument's accuracy by comparison with a standard or reference.
The amount of heat required to raise the temperature of one gram of water one degree Celsius (Centigrade).
SEE lime
A disease characterized by the rapid and uncontrolled growth of aberrant cells into malignant tumors.
Water which meets standards established by the College of American Pathologists. The standards cover three types of laboratory grade water: clinical, cell or tissue, and cultural.
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
As relates to ion exchange, a graph of the ion exchange capacity vs. regenerant levels for an ion exchange unit or system.
A phenomenon in which water or other liquids will rise above the normal liquid level in a tiny tube or capillary due to the attraction of the molecules in the liquid for each other and for the walls of the tube.
The molecular forces which cause the movement of water through very small spaces.
The porous material just above the water table which may hold water by capillarity (a property of surface tension that draws water upwards) in the smaller void spaces.
Costs (usually long-term debt) of financing construction and equipment. Capital costs are usually fixed, one-time expenses which are independent of the amount of water produced.
An element which is found in almost all living or formerly living matter including plants, proteins, organics, and hydrocarbons. Carbon combines readily with oxygen to form carbon dioxide (CO2). In water treatment applications, the term "carbon" is sometimes used as a short reference for activated carbon.
SEE Activated Carbon Block Filter
A measure of the organic matter in a water. To get this mearsurement, the matter adsorbed from the water by activated carbon is extracted from the carbon by using a specific standardized procedure involving chloroform.
A gas (CO2) present in the atmosphere and formed by the decay of organic matter; the gas in carbonated beverages; in water, it forms carbonic acid.
Containing carbon and derived from organic substances such as coal, coconut shells, and wood.
Cation ion exchangers of limited capacity, prepared by the sulfonation of coal, lignite, or peat. Often contain both strong acid and weak acid groups.
The CO3 ion.
Alkalinity (CO3) due to the presence of the carbonate ion.
Hardness due to the presence of calcium and magnesium bicarbonates and carbonates in water; the smaller of the total hardness and the total alkalinity.
SEE Soda Water
A specific acidic group having a chemical formula that contributes cation exchange ability to some resins. Sometimes called weak acid cation exchangers.
A material substance that induces excessive or abnormal cellular growth cancer in an organism.
Cancer-producing.
SEE Entrainment
Any removable, preformed, or prepackaged component containing a filtering media or ion exchanger. Also referred to as "element".
A device often used for single faucet water treatment, made up of a housing and a removable cartridge (element). In high flow rate commercial applications, the elements are clustered in a large housing, and the elements are cleanable and reusable. In residential use, disposable elements are used.
A number assigned by the Chemical Abstracts Service to identify a chemical.
A substance that increases the rate or yield of a chemical reaction without being consumed itself.
Those filter media which can cause certain reactions to occur in water treatment, such as activated carbon, calcite, manganese greensand, magnesium oxides, and dissimilar metal alloys.
A class of media bed filters which contain manganese treated greensand, zeolites, or pumicites.
Activated carbon with modified surface properties that enhance the functionality of the activated carbon in converting the oxidation state of various elements. For example, with hydrogen sulfide (H2S), the sulfide ion (S-) is adsorbed and then converted on the catalytic carbon to elemental sulfur (S0) and sulfate ion (SO4 --). Once the sulfide is adsorbed and converted, it is desorbed and the site is restored. For these reactions to occur, excess dissolved oxygen is required in the water and a minimum empty bed contact time (EBCT) of five minutes may be necessary.
A type of ozone destruction unit that uses a catalyst to enhance the performance of the off-gas treatment system.
To act as a catalyst. Or, to speed up a chemical reaction.
To be acted upon by a catalyst
Enhancement of chemical or biological oxidation by the addition of catalytic agents that promote higher rates of reaction.
The negative pole of an elecrolytic system; an electrode where reduction occurs.
A corrosion control system in which the metal to be protected is made to serve as a cathode either by the deliberate establishment of a galvanic cell or by impressed current.
An ion with a positive electrical charge, such as calcium, magnesium, sodium, iron, lead, and manganese.
Ion exchange process in which cations in solution are exchanged for other cations from an ion exchanger.
An ion exchange material possessing reverse exchange ability for cations.
An equipment unit capable of reducing water hardness by the cation exchange process.
SEE cation exchange resin
SEE Ion Exchange Membrane
A polyelectrolyte with a net positive electrical charge.
A polymer having positively charged groups of ions; often used as a coagulant aid.
Any substance capable of burning or destroying animal flesh or tissue. The term is usually applied to strong bases such as lye.
SEE Hydrated Lime
The common name for sodium hydroxide, (NaOH).
The formation and collapse of a gas pocket or bubble on the blade of an impeller or the gate of a valve. The collapse of this gas pocket or bubble drives water into the impeller or gate with a terrific force that can cause pitting on the impeller or gate surface. Cavitation is accompanied by loud noises that sound like someone is pounding on the impeller or gate with a hammer.
Cellulose-based products which have been cross-linked and then modified with either anion or cation groups capable of selective ion exchange. Cellulose materials have some natural weak acid functionality.
SEE Cellulose Acetate
SEE Centigrade
A temperature scale in which 100 degrees is the boiling point and zero degrees the freezing point for water at sea level.
One one-hundredth (1/100) of a meter (m).
Portion of the nervous system which consists of the brain and spinal cord; CNS.
The water leaving a centrifuge after most of the solids have been removed.
A pump containing a rotating impeller or rotating vanes mounted on a shaft in a casing and turned by a power source. The rotating impeller uses centrifugal force to deliver water in a steady stream (without pulsations) to the point-of-use.
A mechanical device that uses centrifugal or rotational forces to separate solids from liquids.
1. As used in relation to WQA equipment performance testing, the determination that a representative sample of the equipment model to be certified has met the requirements of the respective test standard. 2. As used in relation to WQA educational services, the granting of certified status (Certified Water Specialist; Certified Sales Representative; Certified Installer) to individuals who have passed the WQA certification examinations.
colony-forming units
Water specifically prepared for testing the performance of water treatment equipment products. Challenge water for each type of equipment is specifically defined in the individual equipment testing standards such as those established by the Water Quality Association and the National Sanitation Foundation International.
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.
An adsorbent carbon product which has about one-third the surface area of activated carbon.
Normal (uncharged) polysulfone (PS) membranes contain physical pores that can pass salts; they are used in ultrafiltration water treatment. Charged PS membranes have been chemically sulfonated to create the ability to reject dissolved salts. The sulfonation process permanently affixes sulfonate (SO3-) groups on the membrane surface, in a process similar to that used to give cation exchange resins their charge characteristics. These negatively charged sites repel anions, and indirectly repel the cations also due to the cations' attraction to anions in the concentrate solution. Charged PS membranes have salt rejection and chlorine tolerance characteristics similar to cellulosic membranes, and offer a permeate flux rate comparable to thin-film composite membranes. However, charged PS membranes are more easily fouled by any divalent or trivalent cations, such as calcium, magnesium, or iron existing in the feedwater. See Also: Polyamide Polysulfone Electrodialysis Reverse Osmosis Polysulfone Reverse Osmosis Thin-Film Composite Membrane
A valve which will allow water to pass in one direction but will close and prevent flow (backflow) in the opposite direction.
To form a complex chemical compound in which an ion, usually metallic, is bound into a stable ring structure.
A chemical compound sometimes fed to water to tie up undesirable metal ions, keep them in solution, and eliminate or reduce the normal effects of the solution.
The process of forming complex chemical compounds in which certain metal ions are bound into stable ring structures, keeping the ions in solution and eliminating or reducing normal (and often undesirable) effects of the ions. Similar to the process of sequestration. See Also: Chelating Agent Organic Iron Humic Substances Chelating Agent Organic Iron Humic Substances Free Acid Form Weak Acid Cation Exchangers Total Acidity Strong Acid Cation Exchanger Chelating Agent Organic Iron Trihalomethanes (THMs) Humic Acid Humic Substances Humin Fulvic Acid Tannin Chelating Agent Organic Iron Trihalomethanes (THMs) Humic Acid Humin Fulvic Acid Tannin
A mechanical device designed to introduce chemicals into a water system, more or less accurately in proportion to water flow.
SEE calcium oxide; lime
An indirect measure of the amount of oxygen used by inorganic and organic matter in water. The measure is a laboratory test based on a chemical oxidant and, therefore, does not necessarily correlate with biochemical oxygen demand.
SEE lime softening; lime-soda ash softening
Resistance to attack by chemical action. This term is often applied to the resistance of ion exchange resins to breakdown due to contact with aggressive solutions.
Those granular or bead form materials used in filtration processes which can react chemically with constituents in the water and serve to modify the water quality, such as calcite, in pH modification; or as a catalyst to initiate chemical reactions such as manganese greensand, pyrolusite, activated carbon, and dissimilar metal alloy products.
A process related to adsorption in which atoms or molecules of reacting substances are held to the surface atoms of a catalyst by electrostatic forces having about the same strength as chemical bonds. Chemisorption differs from physical adsorption chiefly in the strength of bonding, which is much greater in chemisorption than in adsorption. See Also: Absorption
A component (generally a heat exchanger) designed to remove heat from a gas or liquid stream.
Cropland preparation by a special implement (chisel) that avoids complete inversion of the soil (as occurs with conventional moldboard plowing). Chisel plowing can leave a protective cover of crop residues on the soil surface that helps prevent erosion and improve infiltration.
Chemical complexes formed from the reaction between ammonia and chlorine being used to disinfect many municipal water supplies. Unlike chlorine, chloramines do not combine with organics in the water to form potentially dangerous trihalomethanes (THMs). Chloramines can exist in three forms: 1. monochloramine (NH2Cl) 2. dichloramine (NHCl2) 3. nitrogen trichloride (NCl3). The proportions of the chloramines depend on the physical and chemical properties of the water. Water containing chloramines may not be used for fish or for kidney dialysis applications.
A rigid, high-strength thermo-plastic polymer (polyvinyl dichloride) that is practically inert toward water, inorganic reagents, hydrocarbons, and alcohols over a broad temperature range, used for pipe and pipe fittings. See Also: Plastic Pipe Polybutylene (PB) Polycarbonate Polyethylene Polypropylene Polyvinyl Chloride (PVC) Polybutylene (PB) Polycarbonate Polyethylene Polypropylene Polyvinyl Chloride (PVC)
The treatment process in which chlorine gas or a chlorine solution is added to water for disinfection and control of microorganisms. Chlorination is also used in the oxidation of dissolved iron, manganese, and hydrogen sulfide impurities.
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.
A gas (Cl2) widely used in the disinfection of water and an oxidizing agent for organic matter, iron, etc.
That part of a water treatment plant where effluent is disinfected by chlorine.
A measure of the amount of chlorine which will be consumed by organic 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.
The amount of chlorine which is needed for a particular purpose. Some reasons for adding chlorine are reducing the number of coliform bacteria (Most Probable Number), obtaining a particular chlorine residual, or oxidizing some substance in the water. In each case, a definite dosage of chlorine will be necessary. This dosage is the chlorine requirement.
SEE residual chlorine; total chlorine residual
SEE combined available residual chlorine
SEE free available residual chlorine
A class of herbisides that may be found in domestic water supplies and cause adverse health effects. Two widely used chlorophenoxy herbisides are 2,4-D (2,4-Dichlorophenoxy acetic acid) and 2,4,5-TP (2,4,5-Trichlorophenoxy propionic acid (silvex)).
Organic compounds combined with chlorine. These compounds generally originate from, or are associated with, life processes such as those of algae in water.
A chemical analytical technique which utilizes a process of separating gases, liquids, or solids from mixtures or solutions by selective adsorption. Chromatography involves the flow of the gas or liquid sample, which is often dissolved in a carrier solvent (termed the mobile phase), over a solid or liquid adsorbent medium (e.g., silica gel, glass beads, polystyrene gel, alumina, or ion exchange resin), which is often packed in a column and is called the stationary phase. As the mixture flows over the adsorbent medium, each substance adsorbs and desorbs through the medium at different rates, producing distinct bands that can be individually detected and identified. See Also: Gas Chromatograph (GC) Gas Chromatography (GC) Mass Spectrometry (MS) Liquid Chromatography Gas Chromatograph (GC) Gas Chromatography (GC) High Performance Liquid Chromatography (HPLC) Mass Spectrometry (MS) Liquid Chromatography High Performance Liquid Chromatography (HPLC) Liquid Chromatography Gas Chromatograph (GC) Gas Chromatography (GC) High Performance Liquid Chromatography (HPLC) Mass Spectrometry (MS)
Occurring over a long period of time, either continuously or intermittently; used to describe ongoing
Long-term, low-level exposure to a toxic chemical.
The circular outer edge of a depression produced in the water table by the pumping of water from a well. See Also: Cone of Depression Cone of Influence Lime (CaO) Lime Softening Cone of Depression Cone of Influence Blowdown Lime Soap Burnt Lime (CaO) Ion Exchange Hydrated Lime Hot-Lime Softening Hot Lime-Soda Softening Hot Process Softening Municipal Softening Permutit Process Phosphate Rated Capacity Water Softening Water Table Sessile Soda Ash Sodium Carbonate Softened Water Rated Capacity Cone of Influence Cone of Depression Cone of Influence Lime (CaO) Lime Softening Cone of Depression Cone of Influence Blowdown Lime Soap Burnt Lime (CaO) Ion Exchange Hydrated Lime Hot-Lime Softening Hot Lime-Soda Softening Hot Process Softening Municipal Softening Permutit Process Phosphate Rated Capacity Water Softening Water Table Sessile Soda Ash Sodium Carbonate Softened Water Rated Capacity Cone of Depression Cone of Influence
The complete path of an electric current, including the generating apparatus or other source; or, a specific segment or section of the complete path.
A safety device in an electrical circuit that automatically shuts off the circuit when it becomes overloaded. The device can be manually reset.
A small tank (usually covered) or a storage facility used to store water for a home or farm. Often used to store rainwater.
The removal of small quantities (<2%) of fine particulate matter (solids) from a liquid (water) to improve the product liquid. Generally, clarifiers will remove particles from 2 to 100 micrometers in size. Clarification methods include filtration, gravity and centrifugal sedimentation, and magnetic separation.
A large circular or rectangular tank or basin in which water is held for a period of time, during which the heavier suspended solids settle to the bottom. Clarifiers are also called settling basins and sedimentation basins.
The working pressure rating of a specific pipe for use in water distribution systems which includes allowances for surges. This term is used for cast iron, ductile iron, asbestos cement, and some plastic pipe.
SEE hydraulic classification
A type of naturally-occurring hydrated aluminum silicate (Al2O3SiO2 x H2O) soil. Natural clay is activated and used as a coagulant adsorbent filter aid. Clay particles can have a diameter of less than five microns.
A soil containing more than 40 percent clay, but less than 45 percent sand, and less than 40 percent silt.
Cyanobacteria-like bodies
SEE ferrous iron
A reservoir for the storage of filtered water of sufficient capacity to prevent the need to vary the filtration rate with variations in demand. Also used to provide chlorine contact time for disinfection.
Studies of humans suffering from symptoms induced by chemical exposure.
Soda water to which additional mineral salts have been added. See Also: Lime Softening Hot Lime-Soda Softening Hot Process Softening Municipal Softening Water Softening Soda Ash Soda Water Sodium Carbonate Community Water System Zone of Saturation Bottled Artesian Water Bottled Distilled Water Bottled Fluoridated Water Bottled Mineral Water Bottled Natural Water Lime Soap Bottled Spring Water Brackish Water Brine Internal Water Treatment Ion Exchange Aesthetic Contaminants Health Contaminant Drainage Basin Drinking Water Drinking Water Standards Municipal Water Permutit Process Phosphate Potable (Drinking) Water Etching External Water Treatment United States Pharmacopeia (USP) Water Softening WFI Sulfur (S) Safe Drinking Water Act (SDWA) Safe Water Sewage Silica Sodium Carbonate Softened Water Soft Water
The formation of media agglomerations or resin clumps within an operating filter or ion exchange bed due to organic fouling or electrostatic charges.
(See Downflow)
A material such as alum, which will form a gelatinous precipitate in water and cause the agglomeration of finely divided particles into larger particles which can then be removed by settling and/or filtration.
A material which is not a coagulant but which improves the effectiveness of a coagulant often by forming larger or heavier particles, speeding the reactions, or by permitting reduced coagulant dosage.
The process in which very small, finely divided solid particles, often colloidal in nature, are agglomerated into larger particles.
The union or growing together of colloidal particles into a group or larger unit as a result of molecular attraction on the surfaces of the particles.
Chemical oxygen demand
Molecular attraction which holds two particles together
The use of submicron filtration to screen out bacteria from a water or fluid.
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.
See colloids
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.
Very finely divided solid particles which will not settle out of a solution; intermediate between a true 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 my be removed by sedimentation and/or filtration.
The shade of 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 water.
The discharge of color to the effluent of a filter or ion exchange system by any componeent. It usually occurs after a period of standing which allows slowly soluble colored matter to accumulate in the system.
A means of measuring unknown chemical concentrations in water by measuring a sample's color intensity. The specific color of the sample, developed by addition of chemical reagents, is measured with a photoelectric colorimeter or is compared with "color standards" using, or corresponding with, known concentrations of the chemical.
A vessel, usually a cylindrical and vertical tank, with an inlet at one end and an outlet at the other end, with some means of holding the medium in place so that a stream of water passing through it is processed. Also known as a bed of filter or catalyst medium, or ion exchange resin.
The process in which the solution to be treated is passed through a vessel containing a bed of filter media or ion exchange; may be either upflow or downflow.
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.
The application of chlorine to water to produce combined available residual chlorine. This residual can be made up of monochloramines, dichloramines, and nitrogen trichloride.
A sewer that transports surface runoff and human domestic wastes (sewage), and sometimes industrial wastes. Waste water and runoff in a combined sewer may occur in excess of the sewer capacity and cannot be treated immediately. The excess is frequently discharged directly to a receiving stream without treatment, or to a holding basin for subsequent treatment and disposal.
Water treatment equipment designed for connection to the water system with conventional plumbing fittings of greater than one inch internal pipe size (IPS) and designed for commercial or light industrial uses.
Sodium chloride (NaCl). A white or colorless crystalline compound that occurs abundantly in nature (present as 2.6 percent of seawater) and in animal fluids. Sodium chloride is used in water treatment to regenerate cation exchange water softeners and some dealkalizer systems. Also called table salt or common table salt. See Also: Brackish Water Brine Dry-Salt Saturator Tank Wet-Salt Saturator Tank Salt Sodium Chloride (NaCl)
A public water system which serves at least 15 service connections used by year-round residents or regularly serves at least 25 year-round residents. See Also: Club Soda Zone of Saturation Bottled Artesian Water Bottled Distilled Water Bottled Fluoridated Water Bottled Mineral Water Bottled Natural Water Lime Soap Bottled Spring Water Brackish Water Brine Internal Water Treatment Ion Exchange Aesthetic Contaminants Health Contaminant Drainage Basin Drinking Water Drinking Water Standards Municipal Water Permutit Process Phosphate Potable (Drinking) Water Etching External Water Treatment United States Pharmacopeia (USP) Water Softening WFI Sulfur (S) Safe Drinking Water Act (SDWA) Safe Water Sewage Silica Sodium Carbonate Softened Water Soft Water Municipal Water Septic Tank Club Soda Zone of Saturation Bottled Artesian Water Bottled Distilled Water Bottled Fluoridated Water Bottled Mineral Water Bottled Natural Water Lime Soap Bottled Spring Water Brackish Water Brine Internal Water Treatment Ion Exchange Aesthetic Contaminants Health Contaminant Drainage Basin Drinking Water Drinking Water Standards Municipal Water Permutit Process Phosphate Potable (Drinking) Water Etching External Water Treatment United States Pharmacopeia (USP) Water Softening WFI Sulfur (S) Safe Drinking Water Act (SDWA) Safe Water Sewage Silica Sodium Carbonate Softened Water Soft Water Municipal Water Septic Tank Club Soda Zone of Saturation Bottled Artesian Water Bottled Distilled Water Bottled Fluoridated Water Bottled Mineral Water Bottled Natural Water Lime Soap Bottled Spring Water Brackish Water Brine Internal Water Treatment Ion Exchange Aesthetic Contaminants Health Contaminant Drainage Basin Drinking Water Drinking Water Standards Municipal Water Permutit Process Phosphate Potable (Drinking) Water Etching External Water Treatment United States Pharmacopeia (USP) Water Softening WFI Sulfur (S) Safe Drinking Water Act (SDWA) Safe Water Sewage Silica Sodium Carbonate Softened Water Soft Water Municipal Water Septic Tank
A calculated value based upon the total hardness, the magnesium-to-calcium ratio, and the sodium, iron, and manganese concentrations in a water. This value is used to correct for the reduction in hardness removal capacity of a cation exchange water softener which is caused by the presence of these substances. No single method of calculation has been uniformly accurate.
In municipal water treatment, a method of treating water which consists of the addition of coagulant chemicals, flash mixing, coagulation - flocculation, sedimentation, and filtration. Also called conventional filtration.
The nine-year calendar year cycle during which public water systems must monitor for regulated drinking water contaminants. Each compliance cycle consists of three three-year compliance periods. The first calendar year cycle begins January 1, 1993 and ends December 31, 2001; the second begins January 1, 2002 and ends December 31, 2010; the third from January 1, 2011 to December 31, 2019, etc.
A three-year calendar period within a compliance cycle. Each compliance cycle has three three-year compliance periods. Within the first compliance cycle, the first compliance period runs from January 1, 1993 to December 31, 1995; the second from January 1, 1996 to December 31, 1998; the third from January 1, 1999 to December 31, 2001.
A mixture of a number of single or "grab" samples intended to produce a typical or average sample when wide variations in quality or characteristics may occur; may be made up of equal volumes of individual samples or of single samples proportioned to variations in flow or usage.
A controlled microbial degradation of organic waste that yields an environmentally sound, nuisance-free product of potential value as a soil conditioner.
A substance composed of two or more elements whose composition is constant. For example, table salt (sodium chloride - NaCl) is a compound.
In reverse osmosis and electrodialysis applications, a technique for increasing the amount of product water by recycling a fraction of the concentrate stream back through the membrane or membrane stack.
In reverse osmosis applications, the stream into which rejected ions and materials are concentrated.
A solution which contains a relatively high quantity of the solute.
1. The process of increasing the dissolved solids per unit volume of solution, usually by evaporation of the liquid or separation of the liquid by passage through a semipermeable membrane. 2. The amount of the material dissolved in a unit volume of a solution.
1. The ratio of the salt concentration in the membrane boundary layer to the salt concentration in the bulk stream. The most common and serious problem resulting from concentration polarization is the increasing tendency for precipitation of sparingly soluble salts and the deposition of particulate matter on the membrane surface. 2. Used in corrosion studies to indicate a depletion of ions near an electrode. 3. The basis for chemical analysis by a polarograph.
Water obtained by condensation of steam or water vapor.
Any water which has been treated by one or more processes (adsorption, deionization, filtration, softening, reverse osmosis, etc.) to improve the water's usefulness and/or aesthetic quality by reducing undesirable substances (iron, hardness etc.) or undesirable conditions (color, taste, odor, etc.).
A measure of the ability of a solution to allow an electric current to flow through it; the reciprocal of resistance. The unit of measure for conductance is the siemens (formerly called mho), which is the reciprocal of the ohm (the unit of measure for resistance). In electrolytic or ionic solutions, the current is carried by ions; liquids such as pure water, glass, and high polymers (such as rubber and cellulose) exhibit poor conductance. See Also: Conductivity Electrical Conductivity Specific Conductance
The property of a substance to conduct (carry) heat or electricity; the unit of measure is the siemens (formerly called mho), which is the reciprocal of resistivity (1 divided by resistivity). See Also: Electrical Conductivity Specific Resistance Specific Conductance Conductance Electrical Conductivity Specific Conductance
A substance, body, device, or wire that readily conducts or carries electrical current.
The depression, roughly conical in shape, produced in the water table by the pumping of water from a well. See Also: Cone of Influence Lime (CaO) Lime Softening Circle of Influence Cone of Influence Blowdown Lime Soap Burnt Lime (CaO) Ion Exchange Hydrated Lime Hot-Lime Softening Hot Lime-Soda Softening Hot Process Softening Municipal Softening Permutit Process Phosphate Rated Capacity Water Softening Water Table Sessile Soda Ash Sodium Carbonate Softened Water Rated Capacity Circle of Influence Cone of Influence Circle of Influence Cone of Influence Lime (CaO) Lime Softening Circle of Influence Cone of Influence Blowdown Lime Soap Burnt Lime (CaO) Ion Exchange Hydrated Lime Hot-Lime Softening Hot Lime-Soda Softening Hot Process Softening Municipal Softening Permutit Process Phosphate Rated Capacity Water Softening Water Table Sessile Soda Ash Sodium Carbonate Softened Water Rated Capacity Circle of Influence Cone of Influence
The depression, roughly conical in shape, produced in the water table by the pumping of water from a well. See Also: Cone of Depression Lime (CaO) Lime Softening Circle of Influence Cone of Depression Blowdown Lime Soap Burnt Lime (CaO) Ion Exchange Hydrated Lime Hot-Lime Softening Hot Lime-Soda Softening Hot Process Softening Municipal Softening Permutit Process Phosphate Rated Capacity Water Softening Water Table Sessile Soda Ash Sodium Carbonate Softened Water Rated Capacity Circle of Influence Cone of Depression Circle of Influence Cone of Depression Lime (CaO) Lime Softening Circle of Influence Cone of Depression Blowdown Lime Soap Burnt Lime (CaO) Ion Exchange Hydrated Lime Hot-Lime Softening Hot Lime-Soda Softening Hot Process Softening Municipal Softening Permutit Process Phosphate Rated Capacity Water Softening Water Table Sessile Soda Ash Sodium Carbonate Softened Water Rated Capacity Circle of Influence
An aquifer in which groundwater is confined under pressure which is significantly greater than atmospheric pressure. See Also: Artesian
A continuous bacterial growth covering the entire filtration area of a membrane filter, or a portion thereof, in which bacterial colonies are not discrete.
Variables other than controlled exposure level which can affect the incidence or degree of a parameter being measured.
Water which was deposited, by geological means, simultaneously with the surrounding rock formations and held without flow. Usually this water occurs in the earth and is high in minerals due to long contact with the rock.
Water removed from available supplies without direct return to a water resource system for uses such as manufacturing, agriculture, and food preparation.
1. The time in minutes the water is in contact with an ion exchange medium or filter medium. 2. The time the brine or other ion exchange regenerant is in intimate contact with the resin. 3. As relates to disinfection, the time the water is allowed to contain the disinfectant to assure potability. Contact time may also be called retention time.
1. An electrical switch, usually magnetically operated. 2. Equipment (e.g., an injector and vessel) used to promote contact and mass transfer between treatment materials and the water and other substances to be treated; hydraulic or mechanical mixing to ensure thorough distribution may be provided. See Also: Gas Chromatography (GC)
1. Any undesirable physical, chemical, or microbiological substance or matter in a given water source or supply. Anything in water which is not H2O may be considered a contaminant. 2. Any foreign component present in another substance.
The addition of foreign matter to a substance which reduces the value of the substance or interferes with its intended use.
The process wherein a continuous and steady flow of water is processed for treatment through the media (as compared to intermittent flow operation). See Also: Back Siphonage Backwash Cross Connection Intermittent Flow Normal Flow Filtration Venturi Cross flow filtration
A flow of water from a particular place in a plant to the location where the sample are collected for testing. This continuous stream may be used to obtain grab or composite samples. frequently, several taps (faucets) will flow continuously in the laboratory to provide test samples from various places in a water treatment plant.
A conservation-based method of farming in which all farming operations (for example, tillage and planting) are performed across (rather than up and down) the slope. Ideally, each crop row is planted at right angles to the ground slope.
A kind of contour farming in which row crops are planted in strips, between alternating strips of close-growing, erosion resistant forage (grass, grain, or hay) crops.
The path through the control system between the sensor, which measures a process variable, and the controller, which controls or adjusts the process variable.
A system which senses and controls its own operation on a close, continuous basis in what is called proportional (or modulating) control.
A device which controls the starting, stopping, or operation of a device or piece of equipment.
In physics, mass motions within a fluid resulting in transport and mixing of the properties of that fluid caused by the force of gravity and by differences in density due to nonuniform temperature.
In municipal water treatment, a method of treating water to remove particulates. The method consists of the addition of coagulant chemicals, flash mixing, coagulation - flocculation, sedimentation, and filtration. Also called complete treatment. See Also: In-line Filtration In-line Filtration Direct Filtration Normal Flow Filtration Cross flow filtration Direct Filtration In-line Filtration Direct Filtration Normal Flow Filtration Cross flow filtration
In municipal water treatment, a series of processes including coagulation, flocculation, sedimentation, and filtration resulting in substantial particulate removal.
The traditional method of farming in which soil is prepared for planting by completely inverting it with a moldboard plow. Subsequent working of the soil with other implements is usually performed to smooth the soil surface. Bare soil is exposed to the weather for some varying length of time depending on soil and climatic conditions.
Water lost in conveyance (pipe, channel, conduit, ditch) by leakage or evaporation.
1. Water which is used to remove heat from air conditioning coils in commercial buildings. For example, by use of cascading cooling towers. 2. Water used in the condensation step of a distillation system.
A boiler treatment process using phosphate buffers to avoid the presence of hydroxyl alkalinity.
A sample of the medium obtained to represent the entire bed depth when the bed is being analyzed for capacity or usefulness. A hollow tube is sent down through the bed to extract the sample.
An electrical discharge effect which causes ionization of oxygen and the formation of ozone.
The discharge of electricity causing a faint glow adjacent to the surface of an electrical conductor and, similarly, adjacent to the dielectrics in an ozone generator during ozone production. Corona discharge results from electrical discharge and indicates ionization of oxygen and the formation of ozone in the surrounding air. The corona discharge is a violet-blue color with air, but colorless with high purity oxygen.
A water service shutoff valve located at a street water main. This valve cannot be operated from the ground surface because it is buried and there is no valve box. Also called a corporation cock.
The destructive disintegration of a metal by electrochemical means.
A substance that slows the rate of corrosion of metal plumbing materials by water, especially lead and copper materials, by forming a protective film on the interior surface of those materials.
A material which resists corrosion after prolonged placement in the environment in which the material was intended to be used. Corrosion-resistant materials do not contribute unacceptable amounts of corroded material into the processed water.
An indication of the corrosiveness of a water. The corrosiveness of a water is described by the water's pH, alkalinity, temperature, total dissolved solids, dissolved oxygen concentration, and the Langelier Index.
A quantitative evaluation of the costs which would be incurred versus the overall benefits to society of a proposed action such as the establishment of an acceptable dose of a toxic chemical.
A publicly financed program through which society, as the beneficiary of environment protection, shares part of the cost of pollution control with those who must actually install the controls.
A measurement of the amount of electrical charge conveyed in one second by an electric current of one ampere. One coulomb equals about 6.25 X 1018 electrons (6,250,000,000,000,000,000 electrons)
(See Upflow)
A steel specimen inserted into water to measure the corrosiveness of water. The rate of corrosion is measured as the loss of weight of the coupon (in milligrams) per surface area (in square decimeters) exposed to the water per day. 10 decimeters = 1 meter = 100 centimeters.
A crop that provides temporary protection for delicate seedlings and/or provides a canopy for seasonal soil protection and improvement between normal crop production periods. Except in orchards where permanent vegetative cover is maintained, cover crops usually are grown for one year or less. When plowed under and incorporated into the soil, cover crops are also referred to as green manure crops.
A genus of filamentous (iron) bacteria which utilize iron in their metabolism and cause staining, plugging, and taste and odor problems in water systems.
The minimum pressure necessary to liquify a gas which is at critical temperature.
The temperature above which a gas cannot be liquefied solely by an increase in pressure.
A system of farming in which a regular succession of different crops are planted on the same land area, as opposed to growing the same crop time after time (monoculture).
A direct link between a potable water system and a nonpotable water system which would permit undesirable substances to be drawn into the potable water.
1. Contamination which occurs in a mixed bed deionizer unit when anion and cation resins are mixed together after regeneration due to the malfunction of the system. 2. The intermixing of two water streams which results in unacceptable water quality for a given purpose.
A type of filtration that uses the shear force of tangential flow across the membrane surface (during suspension recirculation) to keep the particle buildup to a minimum. Particle boudary layers cannot be completely eliminated by cross flow, however, due to low fluid velocity that exists at the membrane surface. Ultrafiltration and reverse osmosis are examples of cross flow filtration. Cross flow filtration is also called tangential flow filtration. See Also: Back Siphonage Backwash Continous Flow Operation Cross Connection Intermittent Flow Normal Flow Filtration Venturi Conventional Filtration In-line Filtration Direct Filtration Normal Flow Filtration
Water leakage between the demineralized and the concentrate streams in the membrane stack used in the electrodialysis process.
Polyethylene that, by cross-linking via irradiation of linear polyethylene with an electron beam or gamma radiation, or with a chemical cross-linking agent, such as benzoly peroxide, is made to be a non-toxic thermosetting (remaines solid upon heating) white solid with superior strength and durability, high temperature and pressure resistance, and inertness toward chemical attack and corrosion. Cross-linked polyethylene pipe and tubing is accepted by many plumbing codes for potable water distribution with buildings. It is flexible (bend radii of six times or greater the outside pipe/tubing diameter) and can be used in place of polybutylene (PB) water pipe. See Also: XPLE or PEX XPLE or PEX Plastic Pipe Polyethylene Polypropylene
cross-linking: 1. A comparatively short connection composed of either an element, a chemical group, or a compound that bridges between neighboring chains of atoms in a complex chemical molecule (especially a polymer). Cross-linking changes a plastic from thermoplastic to thermosetting, and it increases strength, durability, heat and electrical resistance, and resistance to solvents and other chemicals. Examples are: a) vulcanization of rubber with sulfur or organic peroxides, b) cross-linking of polystyrene with divinylbenzene (see 2. in this definition), and c) cross-linking of polyethylene by means of high-energy radiation or with an organic peroxide (see cross-linked polyethylene (XLPE or PEX). 2. The bonding of linear polymers into a resinous product with a material such as divinylbenzene (DVB) producing a tridimensional exchanger product. The cross-links give the resin structure its strength, insolubility, and resistance to melting and distorting over a range of temperatures. Cross-linking also determines the tightness or porosity of the resin structure, and the degree of cross-linking is a factor of the resin's ability to withstand chemical oxidation. Standard softening resin is usually 8 percent cross-linked with divinylbenzene or 8 percent DVB. Anion resins can be from 2 percent to 8 percent cross-linked. Acrylics can also be used instead of DVB for cross-linking..
The area of a plane at a right angle to the direction of flow through a tank or vessel; often expressed in square feet and related to the flow rate (Example: 5 gallons per minute per square foot of ion exchanger bed area).
(crip-toe-spor-ID-ee-OH-sis): The illness produced by infection with Cryptosporidium. The most common symptoms of this disease including fever, headache, nausea, vomiting, anorexia, abdominal cramping, and watery diarrhea. These symptoms usually begin two to ten days after infection and generally last two weeks or less. Cryptosporidiosis in individuals with weakened immune systems is a more severe disease. The most common symptoms of this disease including fever, headache, nausea, vomiting, anorexia, abdominal cramping, and watery diarrhea. These symptoms usually begin two to 10 days after infection and generally last two weeks or less. Cryptosporidiosis in individuals with weakened immune systems is a more severe disease. See Also: Cyst Oocyst
(crip-toe-spor-ID-ee-um) A waterbourne protozoan that forms oocysts and causes acute gastrointestinal illness in humans. Several species of cryptosporidium exist, but only one, C. parvum, is known to be infective to humans. In the environment, the organism's fertilized eggs are protected by an outer shell form called an oocyst (OH-oh-cist). Once injested, the organism emerges from the shell and infects the lining of the small intestines. Cryptosporidium is commonly found in unfiltered surface water and is resistant to disinfectants such as chlorine and ultraviolet light, but C. parvum oocysts, generally being three to five microns in diameter, can be removed by filters that capture all particles of one micron and greater in size. See Also: Cyclospora Cyclospora Cyst
The product of "residual disinfectant concentration" (C) in mg/L determined before or at the first customer, and the corresponding "disinfectant contact time" (T) in minutes, i.e., "C" X "T". If a public water system applies disinfectants at more than one point prior to the first customer, it must determine the CT of each disinfectant sequence before or at the first customer to determine the total percent inactivation or "total inactivation ratio." In determining the total inactivation ratio, the public water system must determine the residual disinfectant concentration of each disinfection sequence and corresponding contact time before any subsequent disinfection application point(s). "CT99.9" is the CT value required for 99.9 percent (3-log) inactivation of Giardia lamblia cysts. CT99.9 values for a variety of disinfectants and conditions appear in Tables 1.1-1.6, 2.1, and 3.1 of section 141.74(b)(3) in the code of Federal Regulations.
The inactivation ratio. The sum of the inactivation ratios, or total inactivation ratio shown as ä = (CTcalc) / (CT99.9) is calculated by adding together the inactivation ratio for each disinfection sequence. A total inactivation ratio equal to or greater than 1.0 is assumed to provide a 3-log inactivation of Giardia lamblia cysts.
A slang expression sometimes used to mean a cubic foot of ion exchanger or filter media.
The common basis for the measurement of the volume of ion exchangers or loose filter media. The measurement is made after a specific process including backwashing and settling of the bed and draining excess water from above the bed. A cubic foot equals 28.3 liters.
The summation of exposures of an organism to a chemical over a period of time.
A water service shutoff valve located in a water service pipe near the curb and between the water main and the building. This valve is usually operated by a wrench or valve key and is used to start or stop flows in the water service line to a building. Also called a "curb cock."
The term used to describe the rate of radioactive decay. A curie = 3.7 X 10E+10 disintegrations per second, and a curie = 3.7 X 10E+10 becquerels (Bqs). See Also: Picocurie (pCi)
A movement or flow of electricity. Water flowing in a pipe is measured in gallons per second past a certain point, not by the number of water molecules going past a point. Electric current is measured by the number of coulombs per second flowing past a certain point in a conductor. A coulomb is equal to about 6.25 X 10E+18 electrons (6,250,000,000,000,000,000 electrons). A flow of one coulomb per second is called one ampere, the unit of the rate of flow of current.
Single-celled organisms (singular = cyanobacterium) similar to bacteria, except cyanobacteria contain the green pigment chlorophyll (as well as other pigments), which traps the energy of sunlight and enables these organisms to carry on photosynthesis. Cyanobacteria are autotrophic producers of their own food from simple raw materials, whereas bacteria are heterotrophic decomposers of the wastes and bodies of other organisms. Cyanobacteria were formerly known as blue-green algae. Blooms or population explosions of cyanobacteria cause water pollution. Some cyanobacteria-like bodies (CLBs) have been associated with causing waterborne diarrheal illnesses.
Organisms that, upon analysis, appear to be cyanobacteria i.e., 8-10 micrometers in size, staining red with modified acid fast stains, and autofluorescing under ultraviolet (UV) light. Cyclospora oocysts have been sometimes confused for cyanobacteria-like bodies in microorganism analyses. See Also: Cyclospora Cyst Oocyst
A dusky bluish or purplish discoloration of the skin or mucous membranes due to insufficient oxygen in the blood as could be caused by excessive nitrates in drinking water and methemoglobinemia in infants. See Also: Nitrate
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.
A cycle related to the changing ratio of solids and water volume in any vessel from which water evaporates, such as a still, a swimming pool, a steam boiler, or a cooling tower. As the water evaporates, the formerly dissolved solids remain behind. The new water which is added (to replace the evaporated water) also contains dissolved solids, so the concentration ratio of solids to water increases proportionately. For example: assume a boiler system holds a total 1,000 gallons of water. When the first 1,000 gallons evaporates, the solids are left behind. Then an additional 1,000 gallons of makeup water is added (to replace the evaporated water) and the makeup water also contains a quantity of solids. The system still holds only 1,000 gallons but the amount of solids has now doubled and the system now holds two concentrations of solids. The concentration is now two (solids) to one (volume of water). If 3,000 gallons of makeup water are added, the concentration becomes four (solids) to one (volume of water). These calculations of concentration ratios are used to determine when blowdown is needed in boiler or cooling tower operation.
A genus of protozoa parasites belonging to the order Coccidia and the phylum Apicomplexa. Cyclospora cayetanensis species are pathogenic to humans causing disease symptoms similar to those caused by Cryptosporidium, except cyclosporiasis does appear responsive to treatment with medicine such as trimethoprim-sulfamethoxazole (TMP-SMX). Cyclospora reproduce with environmentally resistant oocysts (about 8-10 micrometers in size) that can be carried viably in unfiltered water supplies. See Also: Cryptosporidium Cyst Oocyst Cryptosporidium Cyst Cryptosporidium
(See Spore)