| Word | Description |
|---|---|
| AAMI Grade Water | Water meeting quality standards established by the Association for the Advancement of Medical Instrumentation and used mainly for hemodialysis systems. |
| Absolute (Absolute Filter Rating) | The micron rating of a filter, it indicates that 99.9 percent of particles larger than a specific size will be trapped within the filter. |
| Absorbent | A substance (whether a solid or a liquid) that allows another substance (a liquid or a gas) to permeate it. |
| Absorption | The process in which one substance penetrates into the body of another substance, termed the absorbent, as noted above. An example is the absorption of water into soil. This also describes the passage of one substance into or through another; e.g., an operation in which one or more soluble components of a gas mixture are dissolved in a liquid. |
| Acclimatization | The adjustments (both physiological and behavioral) of an organism to changes in its environment. |
| Acid | A substance that releases hydrogen ions when dissolved in water. Most acids will dissolve common metals and will react with a base to form a neutral salt and water. The opposite of an alkali, an acid has a pH rating lower than 7.0, will turn litmus paper red and has a sour taste. |
| Acid aerosol | Liquid or solid particles that are acidic and are small enough to become airborne. |
| Acid deposition/acid rain | A complex chemical and atmospheric phenomenon that occurs when emissions of sulfur (e.g. sulphuric oxide) and nitrogen compounds and other substances are transformed by chemical processes in the atmosphere, often far from the original sources and then deposited on earth in either a wet or dry form. The wet forms popularly called ?acid rain? and have a low pH. This can fall as rain, snow, or fog. The dry forms are acidic gases or particulates. |
| Acidity | The quantitative capacity of a substance (a water or a solution) to neutralize a base, expressed in ppm or mg/L calcium carbonate equivalent. Acidity is determined by the number of hydrogen atoms present. Usually measured by titration with a standard solution of sodium hydroxide. |
| Acid neutralizing capacity | Measure of the buffering capacity of water; the ability of water to resist changes in pH. |
| Action level | The level of lead or copper that, if exceeded, triggers treatment or other requirements that a water system must follow. |
| Activated alumina | A medium, activated alumina will remove several contaminants including fluoride, arsenic and selenium. It requires periodic cleaning with a regenerant such as alum, acid and/or caustic. It ismade by treating aluminum ore so that it becomes porous and highly adsorptive. |
| Activated carbon | A solid adsorbent material that is used to remove organic pollutants from liquid or gas streams. This is the most commonly used adsorption medium. It is found in block, granulated, or powdered form, activated carbon is produced by heating carbonaceous materials, such as coal, wood, or coconut shells, in the absence of air to create a char which is then activated with oxidizing gases to form pores. Used for dechlorination, the reduction of organic chemicals and radon, it is recognized by the US EPA as the best available technology for reduction of organic chemicals from drinking water. It is sometimes called activated charcoal. |
| Acute health effect | An immediate (i.e. within hours or days) effect that may result from exposure to certain drinking water contaminants (e.g., pathogens). |
| Activated silica | A colloidal substance generally formed by combining a dilute sodium silicate solution with a dilute acidic solution (or other activant). A negatively charged substance generally used as a coagulant aid. |
| Activated sludge | Oxygen dependent biological process that converts soluble organic matter to solid biomass, that is removable by gravity or filtration; the flocculent mass of microorganisms, mainly bacteria, that develops when sewage or liquid effluent is aerated. This is a continuous process in which a liquid effluent is aerated in a tank to reduce the BOD and ammoniacal nitrogen |
| Active groups | Really fixed ions bolted on to the matrix of an ion exchanger. Each active group must always have a counter-ion of opposite charge near itself. |
| Adhesion | Molecular attraction that holds the surfaces of two substances in contact. |
| Adsorbate | Any substance that is, or can be, adsorbed. The liquid, gas or solid substance that is adsorbed as molecules, atoms, or ions. |
| Adsorbent | A substance, usually porous, that allows the molecules of a gas or liquid to adhere to its large surface area. Adsorbent water treatment mediums are usually solid (activated alumina and activated carbon, for example) and are capable of the adsorption of liquids, gases and/or suspended matter. |
| Adsorption | Separation of liquids, gases, colloids or suspended matter from a medium by adherence to the surface or pores of a solid. The physical process occurring when liquids, gases, or suspended matters adhere to the surfaces or in the pores of an adsorbent media such as activated carbon. This is a physical process (there is no chemical reaction). In wastewater treatment, adsorption is an advanced method of treating wastes in which activated carbon removes organic matter from wastewater. |
| Advanced oxidation process | An advanced chemical oxidation process is one of several combination oxidation processes that use (chemical) oxidants to reduce COD/BOD levels and remove organic and oxidizable inorganic components. The processes can completely oxidize organic materials to carbon dioxide and water, although it is rarely necessary to do so. Other combination oxidation processes include chemical oxidation process, which can use hydrogen peroxide, ozone, a combination of ozone and peroxide, hypochlorite, Fenton's reagent, etc.; ultraviolet (UV) enhanced oxidation such as UV/ ozone, UV/hydrogen, UV/air; and wet air and/or catalytic wet air oxidation (where air is used as the oxidant). |
| Advanced water treatment | The level of water treatment that requires an 85-percent reduction in pollutant concentration, also known as tertiary treatment. |
| Advanced wastewater treatment | Any treatment of sewage water that includes the removal of nutrients such as phosphorus and nitrogen and a high percentage of suspended solids. |
| Aerated lagoon | A water treatment pond that speeds up the biological decomposition of organic waste by stimulating the growth and activity of bacteria responsible for the degradation. |
| Aeration | A water treatment technique that demands oxygen supply, commonly known as aerobic biological water purification. Either water is brought into contact with water droplets by spraying, or air is brought into contact with water by means of aeration facilities. Air is pressed through a body of water by bubbling and the water is supplied with oxygen. Aeration may be used to add oxygen to the water for the oxidation of matter such as iron, or to cause the release of dissolved gases such as carbon dioxide or hydrogen sulfide from the water. The process of aeration may be passive (as when waste is exposed to air), or active (as when a mixing or bubbling device introduces the air). |
| Aeration tank | A tank or chamber that is used to inject air into water. |
| Aerator | A mechanical device that transfers oxygen from air into solution |
| Aerobic | In the presence of oxygen, such as the digestion of organic matter by bacteria in an oxidation pond. Aerobic microorganisms require oxygen for their respiratory processes; an aerobic environment is one in which oxygen is available. |
| Aerosol | Very small liquid or solid particles dispersed in air; for example, a mist or fume; an aerosol may be formed by blowing liquid through a nozzle. |
| Affinity | The keenness or eagerness with which an ion exchanger takes up and holds on to a counter-ion. The concentration of the electrolyte surrounding the ion exchanger significantly affects affinities. |
| Agglomeration | In all industries, the process of bringing smaller particles together to form a larger mass. In water treatment, the process by which precipitation particles grow larger by collision or contact with cloud particles or other precipitation particles. |
| Aggressive water | Water that is soft and acidic that can corrode plumbing, pipes and appliances. The term is usually applied to waters containing acid or oxygen that hasten corrosion (rusting). |
| Air check | A device that allows water, but not air, to pass through it, an air check is a typical component of a treatment system using a regenerant educator. |
| Air flotation | The separation of solids and oils from liquid effluents by way of their attachment to very small air bubbles, which float the material to the surface |
| Air gap | A clear vertical space through the free atmosphere between the lowest opening of any pipe or faucet conveying water or waste to a tank, plumbing fixture receptor, or other device and the flood level rim of the receptacle. An air gap prevents cross connection between a water treatment device and a possible source of wastewater, so as to prevent a reverse flow of water from the sewer into the water supply system. Otherwise, a reverse flow could occur when negative pressure is created in the water supply line, or from an increase in the pressure in the sewer system. Local plumbing codes usually require the air gap to be twice the diameter of the inlet, with a minimum width of 1.5 inches. |
| Algae | Single- or multi-celled organisms that are commonly found in surface water, such as duckweed, are simple, rootless plants that produce their own food through photosynthesis. The algae population is divided up into green algae and blue algae; both are food for fish and small aquatic animals but the blue algae are very damageable to human health. Excessive algae growth may cause water to have undesirable odors or tastes. Decay of algae diminishes oxygen supplies in water. In ponds, it may be controlled by the addition of potassium permanganate. In a water supply system, chlorination (followed by dechlorination) is often used to eliminate algae. |
| Algal blooms | Periods of enlarged algal growths that affect water quality, algal blooms indicate potentially hazardous changes in the chemistry of water. |
| Aliquot | A measured portion (of no specific size) of a sample taken for analysis; one or more aliquots make up a sample. |
| Alkali | The opposite of an acid, an alkali substance creates a bitter taste and slippery feel when dissolved in water and will turn red litmus paper blue. An alkali has a pH greater than seven; when used for bathing, highly alkaline waters cause drying of the skin. Alkalis may include the soluble hydroxide, carbonate and bicarbonate salts of calcium, magnesium, potassium and sodium. A hydroxide alkali may also be called a base. |
| Alkalinity | Alkalinity means the buffering capacity of water; the capacity of the water to neutralize itself. It prevents the water pH levels from becoming too basic or acid. It also adds carbon to water. Alkalinity stabilizes water at pH levels around seven; however, when the acidity is high in water, the alkalinity decreases, which can harm aquatic life. In water chemistry, alkalinity is expressed in ppm or mg/L of equivalent calcium carbonate. The total alkalinity of water is the sum of all three sorts of alkalinity; carbonate, bicarbonate and hydroxide alkalinity. |
| Alluvium | The sediments along streams deposited by erosion processes. |
| Alternating system | As in the pressure in the sewer system or the creation of a negative pressure in the water supply line. |
| Alum | The common name for aluminum sulfate [Al2 (SO4) x 14H2 O], often used as a coagulant in water treatment. |
| Ammoniacal nitrogen | Nitrogen combined with hydrogen in the form of ammonia (NH3) or the ammonium ion (NH4+); present in sewage, it is toxic to fish and restricted in discharges. |
| Amoeba | A single-celled protozoan widely found in fresh and salt water. Some types of amoebas cause diseases, such as amoebic dysentery. |
| Anaerobic | A process that takes place in (or is not destroyed by) the absence of oxygen, such as the digestion of organic matter by bacteria within a reactor. |
| Anaerobic digester | A tank or vessel which excludes oxygen, in which a sludge or liquid is modified by the action of anaerobic bacteria. |
| Anaerobic organism | An organism that can thrive in the absence of oxygen (air), such as bacteria in a septic tank. |
| Angstrom unit | A unit of wavelength of light equal to .00001 millimeter or .0001 microns. |
| Anion | A negatively charged ion that results from the dissociation of a salt, acid or alkali in solution, such as bicarbonate, chloride, or sulfate. |
| Anion exchange | In this process, anions in solution are exchanged for other anions from an ion exchanger. In demineralization, for example, bicarbonate, chloride and sulfate anions are removed from solution in exchange for a chemically equivalent number of hydroxide anions from the anion exchange resin. |
| Anode | The positive pole of an electrolytic system. Anodes of metals such as magnesium and zinc are sometimes installed in water heaters or other tanks to deliberately establish galvanic cells to control corrosion of the tank through the sacrifice of the anode, hence the term ?sacrificial anode?. In electrolysis, the site where metal goes into solution as a cation, leaving behind an equivalent number of electrons to be transferred to an opposite electrode, called a cathode. |
| Anoxic | Describes a condition in which a liquid has become devoid of oxygen and in which certain microorganisms can obtain oxygen from nitrate or nitrite ions |
| ANSI | Acronym for the American National Standards Institute. |
| Aquatic | Growing or living in water; frequenting or adapted to water. |
| Aqueous | Containing water; watery, or made of water. |
| Aqueous solubility | The maximum concentration of a chemical that dissolves in a given amount of water. |
| Aquifer | Natural underground reservoirs of porous layers of sand, rock or gravel; the layer in the soil that is capable of transporting a significant volume of groundwater. |
| Aromatics | A type of hydrocarbon containing a ring structure, such as benzene and toluene. |
| Artesian | Describes underground water trapped under pressure between layers of impermeable rock. An artesian well is one that taps artesian water and is therefore free flowing. |
| ASME | Acronym for the American Society of Mechanical Engineers. |
| Assimilation | The ability of water to purify itself of pollutants. |
| Assimilative capacity | The capacity of natural water to receive wastewaters or toxic materials without negative effects and without damage to aquatic life or humans who consume the water. |
| Atom | The smallest unit of matter that is unique to a particular element, atoms are the building blocks for all matter. |
| Atomic number | A specific number different for each element, equal to the number of protons in the nucleus of each of its atoms. |
| Attenuation | The process of reduction of a compound's concentration over time by any of an assortment of methods (absorption, adsorption, degradation, dilution or transformation). |
| Attrition | The action of one particle rubbing against the other (friction) in a filter media or ion exchange bed that can, over time, cause breakdown of the particles. In ion exchange, attrition is the gradual lessening of capacity or effectiveness of the media due to either friction, contaminant saturation, chemical attack or sacrificial properties. |
| Attrition scrubbing | A process that grinds soil particles together in the presence of a liquid to remove surface contamination. |
| Automatic water softener (or Automatic filter) | A water softener (or filter) equipped with a timing device that automatically initiates the backwash and/or regeneration process at preset intervals. In an automatic water softener, all operations are performed without intervention by the user ( bypass of treated or untreated water, backwashing, brining, rinsing and returning the unit to service). |
| Autothermal | This describes the combustion or digestion of a material of sufficient calorific value (or effectiveness in heat recovery) so that little or no additional fuel is needed after the initiation stage. |
| Available chlorine | A measure of the amount of chlorine available in chlorinated lime, hypochlorite compounds, and other materials. |
| AWWA | The acronym for the American Water Works Association. |
| Backflow | The flow of water in a medium in a direction opposite to normal flow. Flow is often returned into the system by backflow if the wastewater in a purification system is severely contaminated. Flow of water in a pipe or line in a direction opposite to the normal flow; often associated with back siphonage, or the flow of possibly contaminated water into a potable water system. |
| Back pressure | Pressure that can cause water to backflow into the water supply when a user's wastewater system is at a higher pressure than the public system; pressure which creates resistance against the flow of water. |
| Backflow preventor | A device (or system) installed in a water line to stop backflow (from a non-potable source). |
| Back siphonage | The reverse seepage of water in a distribution system. |
| Backwash | The upflow or counter-current flow of water through a filter or ion-exchange medium, A counter-current or upwards flow of water used to lift and flush the ion exchange media in a system, thereby flushing away (to the drain) particles of foreign matter that have been accumulated during the service cycle. |
| Backwashing | Reversing the flow of water back through the filter media to remove entrapped solids. |
| Bacteria | Microscopically small single-cell organisms that reproduce by fission of spores (cell division). Although usually classed as plants, bacteria contain no chlorophyll. Many different types of bacterial organisms are often found in drinking water. (Singular: bacterium.) Some of these microscopic living organisms can aid in pollution control by consuming or breaking down organic matter in sewage, or by similarly acting on oil spills or other water pollutants. Bacteria in soil, water or air can also cause human, animal and plant health problems. |
| Bacterial water contamination | The introduction of unwanted bacteria into a water body. |
| Bacteriastatic | Having the ability to inhibit the growth of bacteria without destroying them. For example, silver impregnated activated carbon will limit bacterial colonization, but not eliminate it. |
| Bactericide | A substance or agent that kills bacteria. |
| Baghouse filter | Large fabric bag, usually made of glass fibers, used to eliminate intermediate and large (greater than 20 microns in diameter) particles. This device operates much like the bag of an electric vacuum cleaner, allowing air and smaller particulate matter to pass through but entrapping larger particulates. |
| Bag filter | Textile or sintered polymer filters most commonly used to remove dust and fume particles from gas streams, they are also used in wastewater treatment to provide a final polish or remove floc particles. |
| Balancing tank | A chamber that provides sufficient storage volume to permit a non-uniform flow of wastewater to be collected, mixed and pumped forward (to a treatment system) at a uniform rate. |
| Bar | A unit of pressure. One bar equals 14.5 pounds per square inch (psi), or about 0.987 standard atmospheres. |
| Bar screen | In wastewater treatment, a device used to remove large solids. |
| Barrier layer | The active layer of membrane material that actually separates the impurities from the product stream or permeate. |
| Base | An alkaline substance, with a pH over 7.5, that releases hydroxyl ions when dissolved in water. Bases reset with acids to form a neutral salt and water. Generally, they taste bitter and feel slippery. |
| Batch operation | The utilization of ion exchange resins to treat a solution in a container wherein the removal of ions is accomplished by agitation of the solution and subsequent decanting of the treated liquid. |
| Bed | The resin or filter media in a column or other tank or operational vessel. Water passes through the bed during treatment. |
| Bed depth | The height of the ion exchange resin or filter media in the vessel after preparation for service, normally expressed in inches and excluding any supporting bed. |
| Bed expansion | During backwashing, resin particles become separated and rise in the column; this expansion may be controlled by regulating backwash flow. |
| Bed load | Sediment particles resting on or near the channel bottom that are pushed or rolled along by the flow of water. |
| Bed volume | The term expressing the measurement of incoming water (gallons or liters) equal to the volume of resin or filter media in a tank, including voids. |
| Belt press | A device in which waste sludge is compressed between two moving belts, to thicken and dewater it. |
| Benthic zone | The lower region of a body of water including the bottom. |
| Best available technology | The water treatment(s) that US EPA certifies to be the most effective for removing a particular contaminant. |
| Bicarbonate alkalinity | The presence (in a solution) of hydroxyl (OH-) ions resulting from the hydrolysis of carbonates or bicarbonates. When these salts react with water, a strong base and a weak acid are produced and the solution is alkaline. |
| Bicarbonates | Salts that contain the anion HCO3. When acid is added, this ion breaks into H2O and CO2 and acts as a buffer. |
| Binder | Chemicals that hold short fibers together in a cartridge filter. |
| Bioaccumulantion | The increase in concentration of a substance in living organisms, as they take in contaminated air, water, or food, due to slow metabolization and excretion. |
| Biochemical oxygen demand (BOD) | The amount of oxygen (measured in mg/L) required for the decomposition of organic matter by single-cell organisms under test conditions. The greater the BOD, the greater the degree of pollution. In wastewater treatment, the amount of oxygen (in mg) required by aerobic bacteria to decompose the biodegradable organic material in 1 liter of an effluent |
| Biocide | A chemical that is toxic to microorganisms; biocides are often used to eliminate bacteria and other single-cell organisms from water. Pesticides, herbicides and fungicides are all biocides and can be harmful to humans. |
| Biodegradable | The ability to break down or decompose rapidly under natural conditions and processes. |
| Biofilm | A population of various micro organisms, in a layer of slime and excretion products, attached to a surface such as that inside a water storage vessel. Also known as biological film or microbial film, the construction of the layer may offer protection to bacteria within the film against the action of sanitizers and disinfectants. |
| Biological contaminants | Living organisms (such as viruses, bacteria and fungi) and mammal and bird antigens that can cause harmful health effects to humans. |
| Biological control | In pest control, the use of animals and organisms that eat, kill or out-compete pests. |
| Biological filter | A packaged treatment system that removes BOD and suspended solids from relatively small flows of sewage or industrial wastewater by passing the effluent over plastic media on which aerobic biofilm develops. |
| Biologically activated carbon | Activated carbon that supports active microbial growth in order to aid in organics? degradation. |
| Biological oxidation | The decomposition of complex organic materials by micro organisms through oxidation. |
| Biomass | The amount of organic material of biological origin in a given area or volume. |
| Biomonitoring | The use of living organisms to test the suitability of effluents for discharge into receiving waters and to test the quality of such waters downstream from the discharge. |
| Bioremediation | Using naturally occurring or cultured microorganisms to degrade organic pollutants. |
| Biota | All living organisms in a region or ecosystem. |
| Biotower | An above ground structure containing plastic media covered in microbial film that reduces the BOD/COD/Ammonia of industrial liquid effluent flowing over it |
| Biotransformation | Conversion of a substance into other compounds by organisms; including biodegradation. |
| Birm | The tradename for a manganese dioxide coated aluminum silicate used as an oxidizing catalyst filter medium for iron and manganese reduction. |
| Black water | Water that contains the waste of humans, animals or food. |
| Bleed-off | Also known as blowdown, the draining off of water from a cooling tower reservoir or boiler to avoid tds build-up. |
| Blind spots | Any place on a filter medium where fluids cannot flow through. |
| Blinding | A build-up of particles in a filter medium, that prevents fluids from flowing through. |
| Blowdown | Also known as Bleed-off, the withdrawal of water containing a high concentration of solids or dissolved solids or maintain a specified solids-to-water concentration ratio |
| BOD5 | The amount of dissolved oxygen consumed in five days by bacteria that perform biological degradation of organic matter. |
| Boiling point | The temperature at which the vapor pressure of a liquid equals the pressure of its surface. If the pressure of the liquid varies, the actual boiling point varies. Water?s boiling point is 100 degrees Celsius. |
| Bone char | A black pigment substance with a carbon content of about 10 percent, it is used as a selective anion exchanger for fluoride and arsenic reduction. It is named for the process by which it is created: it is made by carbonizing animal bones. |
| Bottled water | Usually refers to potable water that is sold individual containers for drinking. |
| Boundary layer | A very thin liquid layer immediately adjacent to the rejecting surface of membranes in which the concentration of suspended or dissolved solids is higher than it is in the main body of the water being processed. Also known as the gel layer. |
| Brackish water | Water that is neither salt water nor fresh water that is at midpoint between either one of those categories. Brackish water ranges from about 1,000 ppm total dissolved solids to an arbitary seawater concentration; in many cases, this upper level is defined as 25,000 ppm. |
| Breakpoint chlorination | The addition of chlorine to water until there is enough chlorine present for disinfection of water. |
| Breakthrough | The first appearance in the solution flowing from an ion exchange unit of unabsorbed ions exceeding the performance criteria. Breakthrough is an indication that regeneration of the resin is necessary. |
| Brine | A strong solution of salt(s), such as the sodium chloride or potassium brine used in the regeneration of ion exchange water softeners, but also applied to the mixed sodium, calcium and magnesium chloride waste solution from regeneration. |
| Brine ejector (eductor) | A device used to draw a solution such as brine from a storage tank and force it into a cation or anion water treatment unit. |
| Brine seal | A truncated cone of synthetic rubber attached to the upstream end of a spiral wound membrane element. Under water pressure, it forms a seal with the inner surface of the pressure vessel in which the element is placed to prevent water from bypassing around the outside of the element. |
| Brine tank | A tank located next to a softening unit that acts as a salt storage and brine supply. |
| Buffer | A chemical which causes a solution to resist changes in pH, or is used to shift the pH to a specific value by reacting with hydrogen or hydroxyl ions in the solution. |
| Bund | An outer wall or tank designed to retain the contents of an inner tank in the event of leakage or spillage |
| Bypass | A connection or a valve system that lets untreated water flow to a water system while a softener or filter is being regenerated, backwashed or serviced; the term is also applied to a special water line installed to provide untreated water to a particular tap, such as a sill cock. |
| Cadmium | A toxic heavy metal element that accumulates in the environment. |
| Cake | The solid dewatered residue on a filter media after filtration. |
| Calcite | A tradename for finely ground limestone, very high in calcium carbonate (CaCO3), used to raise the pH of acidic waters. |
| Calcium (Ca) | Commonly found in water as a dissolved solid, calcium is one of the primary elements of the earth's crust. Its presence in water contributes to the formation of scale and insoluble soap curds. It is sometimes referred to as lime. |
| Calcium carbonate equivalent | So that minerals of varying weight can be expressed in chemically equivalent terms, all forms of water hardness and other salts are commonly expressed in terms of calcium carbonate equivalents. |
| Calcium hypochlorite | Commonly used for water disinfection in swimming pools, this chemical a stable dry powder and can be made into tablets. |
| Candle filter | A relatively coarse aperture filter, designed to retain a coat of filter medium on an extended surface. |
| Capacity | In a softener or deionizer it is the adsorption activity possessed in varying degree by ion exchange materials. This quality may be expressed as kilograins per cubic foot, gram-milliequivalents per gram, pound-equivalents per pound, gram-milliequivalents per milliliter, etc.. It can also refer to the ability of any media to take up a specific contaminant; that is expressed as time over gallons. When used as to flow rates, it is the maximum or minimum flow obtainable under given conditions of media, temperature, pressure, velocity, etc. For ion exchange water softeners, the capacity is expressed in grains of hardness removal between successive regenerations and is related to the pound of salt used in regeneration. For filters, the capacity may be expressed in the length of time or total gallons delivered between servicing. |
| Capillary action | Water that at some point rises higher than that portion of its surface, not in contact with the solid surface. This is due to adhesion, cohesion and surface tension. |
| Capillary membranes | Membranes about the thickness of a human hair, used for reverse osmosis, nanofiltration, ultrafiltration and microfiltrtion. |
| Carbonaceous exchangers | Ion exchange materials of limited capacity prepared by the sulfonation of coal, lignite, peat, etc. |
| Carbonates | Chemical compounds related to carbon dioxide. |
| Carbonate hardness | Hardness caused by carbonate and bicarbonate byproducts of calcium and magnesium. |
| Carbon dioxide | Water with a low pH value usually contains free carbon dioxide, generally caused by absorption of carbon dioxide (CO2) from the air as water falls as rain, or by decay of organic matter in the earth. Well water containing substantial quantities of CO2 has a resultant low pH and corrosive qualities. Carbon dioxide in water forms a weak carbonic acid. |
| Carcinogen | Any substance that can cause or contribute to the production of cancer. |
| Cartridge filter | Cartridge filters are widely used for water treatment and have been for many decades. These filters are disposable devices with a range of 0.1 to 100 microns. Typical prefiltration requirements for reverse osmosis systems are around five microns. |
| Catalyst | A substance that increases the rate of a chemical reaction without being consumed in the reaction |
| Catch basin | A sedimentation area designed to remove pollutants from runoff before it is discharged into a stream or pond. |
| Cathode | A site in electrolysis where cations in solution are neutralized by electrons that plate out on the surface or produce a secondary reaction with water. |
| Cathodic protection | The control of the electrolytic corrosion of an underground or underwater metallic structure by the application of an electric current is such a way that the structure is made to act as the cathode instead of anode of an electrolytic cell. |
| Cation | A positively charged particle or ion, such as calcium, magnesium and sodium. |
| Cation exchange | The process formerly called base exchange, in which cations in solution are exchanged for other cations via ion exchange. |
| Caustic | Any substance capable of burning or destroying animal flesh or tissue. |
| Caustic soda | The common name for sodium hydroxide, often used as a regenerant of anion resin in deionization systems. It is also used as the cleaning agent in some detergents. |
| Centrifugation | Using the action of centrifugal force to promote accelerated settling of particles in a solid-liquid mixture. |
| Centrifuge | A device that separates solid material, sludges or oil from liquid effluents by rapid rotation |
| CFU | The acronym for colony forming units, a measure indicating the number of micro organisms in water. |
| Channel | The opening or spacing between membrane layers, such as inside diameters of tubular or hollow fibers, or that resulting from netting in spirals, etc. Also known as bore. |
| Channeling | The flow of water or regenerant taking the line of least resistance through a media bed, rather than the usual distributed flow through all passages of that bed. Channeling may be due to fouling of the bed, poor distribution design, low flow rates, or insufficient backwash and various other factors. |
| Check valve | This valve allows water to stream in one direction and then closes to prevent development of a back-flow. |
| Chelate | To form a complex chemical compound in which an ion, usually metallic, is bound into a stable ring structure. |
| Chelating agents | Organic compounds that have the ability to draw ions from their water solutions into soluble complexes. |
| Chemical feeder | A mechanical device that introduces chemicals into a water system at a measured proportional rate. |
| Chemical Oxygen Demand (COD) | The amount of oxygen (measured in mg/L) consumed in the oxidation of organic and oxidizable inorganic matter under test conditions. It is used to measure the total amount of organic and inorganic pollution in wastewater. Contrary to BOD, with COD practically all compounds are fully oxidized. |
| Chemical stability | The resistance to chemical change which ion exchange resins must possess despite contact with aggressive solutions. |
| Chloramines | A chemical complex consisting of chlorine and ammonia used as a water disinfectant in municipal supplies in place of chlorine (because chlorine can combine with organics to form dangerous reaction products). |
| Chlorinated hydrocarbons | Hydrocarbons that contain chlorine. These include a class of persistent insecticides that accumulate in the aquatic food chain. Among them are DDT, aldrin, dieldrin, heptachlor, chlordane, lindane, endrin, hexachloride and toxaphene. |
| Chlorination | The application of chlorine to drinking water, sewage, or industrial waste to disinfect or to oxidize undesirable compounds. |
| Chlorinator | A device that adds chlorine, in gas or liquid form, to water or sewage to kill infectious bacteria, in proportion to flow. |
| Chlorine | Available as a gas, as a liquid in sodium, hypochlorite, or as a solid in calcium hypochlorite, chlorine is widely used in the disinfection of water and as an oxidizing agent for organic matter, iron, hydrogen sulfide, etc. It is. Chlorine reacts with organics in water to form trihalomethanes (THM) that can cause cancer. |
| Chlorine-contact chamber | The part of a water treatment plant where effluent is disinfected by chlorine. |
| Chlorine demand | A measure of the amount of chlorine that will be consumed by organic matter in water before chlorine residual will be found. |
| Chromium | A toxic heavy metal that may contaminate groundwater; stringent environmental discharge limits apply. |
| Chronic health effect | The possible result of long-term exposure to a drinking water contaminant at levels above its MCL. |
| Clarity | The clearness of a liquid. |
| Climate factor | Evapotranspiration minus precipation (a calculation made when determining landscape water usage.) |
| Coagulant | A material, such as alum, which will form a gelatinous precipitate in water, and cause the agglomeration of finely divided particles into larger particles that can then be removed by settling and / or filtration. A material such as alum, which will form a gelatinous precipitate in water, and gather finely divided particles into larger ones that can then be removed by settling and/or filtration. |
| Coagulation | A process that alters the surface charge on dispersed colloidal particles in a liquid so that they are able to agglomerate; in wastewater treatment, the first stage in floc formation is coagulation, the clumping of particles to settle out impurities. Coagulation is often induced by chemicals (commonly lime, alum or iron salts). |
| Coalescence | Liquid particles in suspension, which unite to create particles of a greater volume. |
| Coastal zone | Lands and waters near the coast, whose uses and ecology are affected by the sea. |
| Coliform bacteria | Usually found in the intestinal tract of humans and other warm-blooded animals, these bacteria serve as indicators of fecal pollution and pathogens when found in water. |
| Coliform index | A rating of the purity of water based on a count of coliform bacteria present therein. |
| Collector sewers | The pipes that collect and carry wastewater from individual sources to an interceptor sewer that will carry it to a treatment facility. |
| Colloids | Matter of very small particle size, in the range of 0.1 and 0.001 microns in diameter. They are larger than molecules, but small enough that they will not settle out of a solution; they cannot be removed by conventional filtration and instead require coagulation (to form larger particles via agglomeration) that can then be removed by conventional means. |
| Color throw | Discoloration of the liquid passing through a filtration or ion exchange media. It may be flushing from the media interstices of traces of colored organic reaction intermediates; or it could indicate the presence of metallic ions, humus, tannins, or industrial wastes. May also be produced by extended ?standing?, during which slowly soluble colored matter accumulates in the water. New ion exchange resin may have some initial color throw. |
| Combined heat and power (CHP) | A system designed to use the heat produced during the generation of electricity; CHP can be coupled to the incineration of solid waste. |
| Combined sewer | A sewer system that carries both sewage and storm water runoff. |
| Community water system | A water system which supplies drinking water to 25 or more of the same people year-round in their residences or one that has at least 15 service connections used by year-round residents. |
| Compensated hardness | A calculated value based on the magnesium to calcium ratio, the hardness and the sodium concentration of water. It is used to calculate the reduction in hardness removal capacity of a softener. No single method of calculation has been widely accepted or uniformly accurate. |
| Composite sample | A series of water samples taken over a given period of time and weighted by flow rate. |
| Compound meter | A meter for dual measuring chambers (a turbine for high flows and a positive displacement for low flows). |
| Compounds | Two or more different elements held together in fixed proportions by attractive forces called chemical bonds. Table salt (sodium chloride) is a compound. |
| Concentrate | Also known as reject water. The stream exiting the membrane element that has not passed through the membrane and, ideally, contains all the contaminants removed by the membrane. Concentrate or reject water can also be referred to as brine, retentate, reject, effluent and waste. |
| Concentration | The amount of material dissolved in a unit of solution, expressed in mg/L. |
| Concentration factor (CF) | Also abbreviated as VCF and VCR, this is the term that quantifies the effect of system recovery on the concentration of the rejected contaminants in a membrane element or operating system. It is mathematically related to recovery by the formula: This equation results from a mass balance based on the assumption that the membrane provides complete rejection of the contaminant in question. |
| Concentration polarization | The formation of a more concentrated gradient of rejected material near the surface of the membrane (in the boundary layer) causing either increased resistance to solvent transport or an increase in local osmotic pressure and possibly a change in rejection characteristics of the membrane (i.e., the salt concentration in the membrane boundary to the salt concentration in the bulk stream). |
| Concentration process | The process of increasing the number of particles per unit volume of a solution, usually by evaporating the liquid. |
| Condensate | Water obtained by condensation of water vapor or which has liquefied from steam. |
| Condensation | The change of state from a gas to a liquid. |
| Condenser | A device that removes high concentrations of solvent vapors from gas streams by cooling, allowing both the liquid solvent fraction and the gas to be recycled (or otherwise treated). |
| Conductance | A measure of the ability of a solution to carry electricity; the reciprocal of the electrical resistance. The unit of measuring this conductance is the Siemens (the reciprocal of the ohm, formerly called mho). |
| Conductivity | The quality or power to carry electricity or heat. In water, the conductivity is related to the concentration of ions capable of carrying electrical current. |
| Conduit | In water treatment, a natural or artificial channel through which fluids may be transported. |
| Consumptive water use | Water used in manufacturing, agriculture and/or food preparation that has been removed from available supplies without direct return to a water resource system. |
| Contact stabilization | An activated sludge process where separated sludge is aerated vigorously before it contacts and stabilizes raw sewage; the technique produces less surplus sludge. |
| Contact time | The actual time which water remains in contact with an oxidizer, regenerant, or water conditioning media within a water treatment system. The amount of contact time determines the effectiveness of the system. Also called retention time. |
| Contaminant | Any foreign component in any substance; anything found in water (including microorganisms, minerals, chemicals, radionuclides, etc.) that is something other than water. |
| Contamination | The addition of any physical, chemical, biological or radiological substance to water that interferes with its intended use. |
| Conventional sewer systems | Systems that collect municipal wastewater in gravity sewers and convey it to a central primary or secondary treatment plant before discharge. |
| Conveyance loss | Water loss in pipes and channels by leakage or evaporation. |
| Coolant | A liquid or gas used to reduce heat. |
| Cooling tower | A structure that helps remove heat from water used as a coolant; e.g., in electric power generating plants. Commonly, a large tower (or cascading towers) used to transfer the heat in cooling water to the atmosphere either by direct evaporation or by convection and conduction. |
| Corporation cock | A stopcock screwed into the street water main to provide a residential service connection. |
| Corrosion | The dissolving and wearing away of metal caused by a chemical reaction, such as between water and the pipes it contacts, or chemicals touching a metal surface, or contact between two metals. In iron and steel, corrosion is commonly called rusting. |
| Corrosivity | Ability of water to dissolve or break down certain substances, particularly metals. The corrosiveness of water can be determined by its pH, alkalinity and TDS. |
| Critical bed depth | The minimum depth of any adsorbent bed required to contain the mass transfer zone. |
| Cross connection | Any physical connection between two otherwise separated piping systems, one of which contains potable water and the other of unknown or questionable safety, whereby flow may occur from one system to the other depending on the pressure differential between the two. |
| Crossflow | Flow of solution parallel to the surface of the membrane. This contrasts with dead-end flow, in which the liquid flows perpendicular to the surface of the filter. In crossflow, only a fraction of the crossflow solution passes through the membrane. Reverse osmosis is an example of crossflow filtration: separation of the components of water is accomplished by a semi-permeable membrane through the application of press and parallel flow, which also minimizes particle build-up. Ultrafiltration, nanofiltration and microfiltration are crossflow filtration processes. |
| Cross linkage | The bonding of linear polymers into a resinous product with a material such as divenylbenzene (DVB) to produce a tridimensional exchanger product. The degree of crosslinking is a factor of a resin's ability to withstand chemical oxidation and it determines the tightness or porosity of the resin structure. Softening resin is usually eight-percent crosslinked, but can range from six to 10 percent. |
| Cryptosporidium | A waterborne protozoan that forms cysts and causes acute illness in humans, it is resistant to chlorine and ultraviolet light but can be removed by one micron filtration. |
| CTA | Acronym for cellulose triacetate, a cellulose ester used to manufacture reverse osmosis membranes. |
| Cubic feet per minute (CFM) | A measure of the volume of a substance flowing through air within a fixed period of time. With regard to indoor air, refers to the amount of air, in cubic feet, that is exchanged with indoor air in a minute's time, or an air exchange rate. |
| Cultural eutrophication | A decline of the oxygen level in water caused by humans, which has serious consequences for aquatic life. |
| Current | A flow of water, air or electricity. In electricity, the rate of flow between two points, generally expressed in amperes. In water systems, the flow ingallons per second past a certain point. |
| Cycle | A complete course of operation. For instance, the cycle of cation exchange: regeneration of the resin, rinse to remove excess regenerant, exhaustion, backwash and regeneration again. In municipal filtration processes, the length of time a filter can be used before it needs cleaning, usually including cleaning time. |
| Cyanides | Toxic inorganic chemical compounds containing cyanide (-CN) groups, classed as special waste. |
| Cyclone | A device in which coarse grit and dust particles are thrown outwards to the cyclone wall (by the use of a spun gas stream) where they are guided into a hopper. |
| Dealkalinization | Any process for the reduction of alkalinity in a water supply. It is generally accomplished by a chemical feed processor via combined cation and anion exchange systems. |
| Deashing | The removal (from solution) of inorganic salts by means of adsorption by ion exchange resins of both the cations and the anions comprising those salts. |
| Decant | To draw off the upper layer of liquid after a heavier material (a solid or another liquid) has settled. |
| Decarbonation | The process of removing carbon dioxide from water, commonly by using contact towers or air scrubbers. |
| Dechlorination | The partial or complete removal of excess, free or residual chlorine from a water supply. |
| Decomposition | The breakdown of organic matter by bacteria and fungi, causing a change the chemical structure and physical appearance of that matter. |
| Decrosslinkage | When aggressively attacked by chlorine, ozone, hydrogen peroxide or heat, the crosslink polymer structure of ion exchange resin is destroyed. This results in increased moisture content in the resin and in physical swelling of the beads. |
| Defluoridation | The removal of fluoride from drinking water so as to prevent tooth damage. |
| Defoaming agents | Chemicals added to wastewater discharges to prevent the water from foaming when it is discharged into a receiving water body. |
| Degasification | The process of removing dissolved gasses from water, using vacuum or heat. |
| Deionization | Process that serves to remove all ionized substances from a solution. Most common is the exchange process where cations and anions are removed independently of each other: first, positively charged ions are removed by a cation exchange resin in exchange for a chemically equivalent amount of hydrogen ions; next, negatively charged ions are removed by an anion exchange resin for a chemically equivalent amount of hydroxide ions. The hydrogen and hydroxide ions introduced in this process unite to form water molecules. The term is often used interchangeably with demineralization. The cation resin is regenerated with an acid and the anion resin is regenerated with sodium hydroxide (caustic soda). |
| Delta P | The pressure drop (or loss in psi) between the inlet and the outlet of a water conditioner as the water flows. |
| Density, apparent (Density, true) | The ratio of the mass of an object (or substance) to its volume. The density of water is 1.0 gram per cubic centimeter. Apparent density is the mass per unit volume of a solid sorbent including its pore volume and inter-particle voids; true density is the mass per unit volume excluding pores. |
| Demineralization | The removal minerals from water, usually the term is restricted to ion exchange processes. The two terms are often used interchangeably. |
| Demineralized water | Water that has been treated to be contaminant-, mineral- and salt-free. |
| Denitrification | Removal of nitrate and nitrate product(s) from water to produce a quality that meets common water standards. |
| Depression storage | The storage of water in low areas, such as ponds, and wetlands. |
| Depth filtration | Treatment process in which the entire filter bed is used to trap insoluble and suspended particles in its voids as water flows through it. Methods include a multi-layered bed, multimedia filtration or string-wound fiber cartridge elements. |
| Desalination | Most often refers to the removal of salt from brackish or ocean water to produce drinking water, using various techniques. Generally speaking, desalination is the removal of dissolved inorganic solids (salts) from any solution (including water) to make it free of dissolved salts via reverse osmosis, distillation, or electrodialysis. |
| Desorption | The opposite of adsorption; the release of matter from the adsorption medium, usually to recover material. |
| Desulphurization | The removal of sulphur compounds. |
| Detention time | The actual time that a small amount of water is in a settling basin or flocculating basin. In storage reservoirs, it means the length of time water will be stored prior to use. Also refers to the calculated time required for a small amount of water, at a given rate of flow, to pass through a tank. |
| Detergent | A water-soluble cleansing agent, other than soap, detergent usually refers to a synthetic, but can be any material with cleansing abilities. Synthetic detergents are known as surfactants (they foam and act like soap, but are not made from fatty acids and lye). |
| Dewater | To separate water from sludge, producing a solid cake. |
| D.I. or DI | Abbreviation or acronym for deionization. |
| Diafiltration | A crossflow filtration process allowing for the transfer of low molecular weight species, water and/or solvents through a membrane without changing the solution volume, accomplished by adding solvent (usually water) back into the feed. |
| Dialysis | Both in medicine (kidney dialysis) and in other applications, dialysis is the separation of components of a solution by diffusion through a semi-permeable membrane capable of passing certain ions or molecules while rejecting others. |
| Diffuser | A component of an ozone contacting system within an ozone generator that allows diffusion of an ozone-containing gas. May also refer to the distributor in an ion exchanger or filter media bed, which produces even flow through all sections and retains media in the tank. |
| Diffusion | The process of dispersion of dissolved or suspended particles in a process that tends to distribute them uniformly throughout the available volume from an original state that varied in concentration. |
| Digester | A closed tank for wastewater treatment, in which bacterial action is induced to break down organic matter. In solid waste conversion, a unit in which bacterial action is induced and accelerated in order to break down organic matter and establish the proper carbon-to-nitrogen ratio. |
| Digestion | The enzymatic breakdown of large insoluble organic molecules into small soluble organic molecules that can be absorbed and used by either aerobic or anaerobic micro organisms. The biochemical decomposition of organic matter, resulting in partial gasification, liquefaction, and mineralization of pollutants. |
| Diluting water | Distilled water that has been stabilized, buffered and aerated. |
| Dioxins | A group of toxic organic substances, containing carbon, hydrogen, oxygen and chlorine, resistant to biodegradation, produced when organic material is incinerated at low temperatures. |
| Direct runoff | Water that goes directly into streams, rivers, and lakes from flows over the ground surface. |
| Discharge | Flow of surface water in a stream or canal. |
| Disinfectant(s) | A chemical or physical process that kills of inactivates pathogenic organisms in water at a level of 99.9 to 99.9999 percent under controlled conditions. Chlorine, chloramine, ozone and ultraviolet light are common disinfectants. |
| Disinfection | The decontamination of fluids and surfaces. In water treatment, the destruction or removal of pathogenic microorganisms (bacteria, viruses, cysts, etc.) to make it safe for human consumption. Water disinfection should reduce the population of microorganisms by 99.9 to 99.9999 percent. |
| Dispersant | A chemical agent used to break up concentrations of organic material such as spilled oil. |
| Disposal | Final placement or destruction of toxic, radioactive, or other wastes; surplus or banned pesticides or other chemicals; polluted soils; and drums containing hazardous materials from removal actions or accidental releases. Disposal may be accomplished through use of approved secure landfills, surface impoundments, land farming, deep well injection, ocean dumping, or incineration. |
| Dissolve | When solid particles mix molecule by molecule with a liquid and appear to become part of the liquid. |
| Dissolved air flotation (DAF) | A method of dissolving pressurized air into a liquid to form small bubbles (or micro bubbles of from 40-70 microns) that will float material to the surface. |
| Dissolved oxygen | The amount of oxygen dissolved in water (freely available) at a certain time, expressed in ppm mg/L. Traditionally, the level of dissolved oxygen has been accepted as the single most important indicator of a water body?s ability to support desirable aquatic life. |
| Dissolved solids | Solids materials (organic and inorganic) that have totally dissolved in water and are now in true solution in a stated volume of water; they can be removed via filtration. |
| Distillation | In this treatment method, water is boiled to steam and condensed in a separate reservoir. Contaminants with higher boiling points than water do not vaporize and remain in the boiling chamber. |
| Distribution System | The network of pipes leading from a treatment plant to customers' plumbing systems. |
| Dolomite | A carbonate mineral of calcium and magnesium {CaMg (CO3 ) 2} naturally occurring in extensive beds. |
| Drag-out bath | The vat or tub of water used for rinsing metal plated objects to remove excess plating solution. |
| Drainfield | The long, underground, perforated pipes or tiles connected to a septic tank, usually laid in gravel-filled trenches (two to three feet wide) or beds (over three feet wide) in the soil. Liquid waste (effluent) flows out of the tank and is evenly distributed into the soil through this piping system. The soil below the drainfield provides the final treatment and disposal of the septic tank effluent. After the effluent has passed into the soil, most of it percolates downward and outward, eventually entering the groundwater. A small percentage is taken up by plants through their roots, or evaporates from the soil. |
| Drain line | A pipe or conduit from a water conditioning unit used to carry backwash water, regeneration wastes and/or rinse water to a drain or waste system by gravity. |
| Dredging | The cleaning, deepening, or widening of a waterway, using a machine (dredge) that removes materials by means of either a scoop or a suction device. |
| Drinking water standards | The National Primary Drinking Water Standards established by the US Environmental Protection Agency (EPA) are health related and set the maximum contaminant levels (MCLs) for regulated substances in drinking water. An MCL is the highest permissible level of a contaminant allowed in water delivered to the consumer's tap. These standards relate to public water systems. National Secondary Drinking Water Standards are also issued by the US EPA; these pertain to the aesthetic characteristics of water and are recommended only. |
| Drought | Significantly less-than-average precipitation over a certain period of time. |
| Duplicates | Two separate samples with separate containers taken at the same time and at the same place. |
| Dust | Solid particles about 1-10µm in size |
| DWV | Acronym for Drainage, Waste and Vent. A name for copper or plastic tubing used for drain, waste, or venting pipes. |
| Dystrophic lakes | Acidic bodies of water that contain many plants but few fish, due to the presence of great amounts of organic matter. |
| Ecology | The study of the relationship of living things to one another and their environment. |
| Eductor | A Venturi with an opening at the throat used to educt (suck in) air or liquid. |
| Efficiency | The effectiveness of an ion exchanger?s optimum performance, efficiency in the adsorption of ions is expressed as the quantity of regenerant required to effect the removal of a specified unit weight of adsorbed material, e.g., pounds of acid per kilogram of salt removed. |
| Efficiency standard | A criteria establishing target levels of water use for a particular application or activity. |
| Effluent | The outlet or outflow of any system that deals with water flows or the product water of the given system. It may specifically indicate (1) a flow containing polluting material; (2) liquid waste from sewage treatment, industry, agriculture; (3) the outflow of a water treatment device. Generally refers to wastes discharged into surface waters. |
| Ejector | A device used to inject a chemical solution into water or wastewater during treatment. |
| Electrical charge | The charge on an ion, declared by its number of electrons. A Cl ion is in fact a Cl atom that has acquired an electron; and a Ca++ ion is a Ca atom, which has lost two electrons. |
| Electrochemical cell | A device that removes metals from aqueous solutions by plating them as solid metal on the cathode or oxidizes organic pollutants at the anode. |
| Electrodialysis | A process that uses electrical currents, applied to permeable or semi-permeable membranes, to remove minerals from water. |
| Electrokinetic decontamination | A method of removing metals and other inorganic pollutants from contaminated soils using electrodes |
| Electrolysis | A chemical change brought about by the passage of an electric current through a liquid; used in plating of metals, oxidation of cyanide. |
| Electrolyte | A substance that dissociates or ionizes when it dissolves in water, producing a solution that will conduct an electric current. Could be an acid, base, or salt. |
| Electronic water disinfection | Commonly used in the UK, a method of sterilizing water via the introduction of precise amounts of copper and silver, most often in cooling towers and other non-potable applications. |
| Electrons | Negatively charged building blocks of an atom that circle around the nucleus. |
| Electrostatic precipitator | Water treatment equipment in which particles are passed through ionizers and become charged, facilitating their subsequent removal. |
| Elements | The distinctive building blocks of matter that make up every material substance. |
| Elution | Specifically, to wash out or remove by use of a solvent. In water treatment, the stripping of adsorbed ions from an ion exchange material by the use of solutions containing other ions in concentrations higher than those of the ions to be stripped. |
| Elutriation | To purify by washing, straining or decanting. In wastewater treatment, freeing sludge of its mother liquor by washing it with water. |
| Emulsifier | A chemical that helps suspend one liquid in another. |
| Emulsion | Dispersion of one (or more) liquid(s) into another liquid, occurs when a liquid in insoluble. |
| End-of-pipe techniques | Techniques normally implemented at the last stage of the treatment process before the water is delivered or released. |
| End-point | The end point is that point in the exhaustion run of a water conditioner, such as a softener or deionizer, at which the water quality has dropped below an acceptable level. |
| Enrichment | When the addition of nutrients, such as nitrogen and phosphorus, from sewage effluent or agricultural runoff to surface water, greatly increases algal growth. |
| Equivalent per million | A unit of concentration used in chemical calculations, calculated by dividing the concentration in ppm or mg/1 by the equivalent weight. |
| Erosion | The wearing away of land surface by wind, water, ice or other geological agents. Erosion occurs naturally from weather or runoff, but is often intensified by human land use practices. |
| Eschericha coli (E. coli) | Coliform bacterium found in human and animal intestines and discharged in their wastes. It is used by health departments and private laboratories to measure the purity of water. |
| Estuary | Interaction region between rivers and near-shore ocean waters, where tidal action and river flow mix fresh and salt water; therefore, estuaries mainly consist of brackish water. |
| Eutrophic | Referring to water that is rich in nutrients such as nitrogen and phosphorous creating productive conditions for aquatic life. |
| Eutrophication | The aging process of a body of water caused by the depletion of available oxygen. The process is characterized by development of an environment rich in nutrients and consequent proliferous plant production. Manmade eutrophication of inland water courses and shallow coastal waters is caused by excessive discharge of nutrients, especially phosphorus (P) and nitrogen (N) in the form of PO4 and NO3. Barn yard runoff and fertilizers accelerate eutrophication. |
| Evaporation | The process of the passage of a substance from a liquid to a vapor. |
| Evaporation ponds | Areas where sewage sludge is dumped and dried. |
| Evapotranspiration | The loss of water from the soil through vaporizing, both by direct evaporation and by transpiration from plants. |
| Exchange sites | Locations on ion exchange resin beads that hold mobile ions available for exchange with other ions in a solution passing through the bed. These sites are also called functional groups. |
| Exchange velocity | In an ion exchanger, the rate with which one ion is displaced in favor of another. |
| Exhaustion | The state of the adsorbent (such as activated carbon), a water softener, or a deionizer that is no longer capable of the removal of a specific pollutant or of useful ion exchange. The exhaustion point is determined arbitrarily in terms of: (a) the presence or increase of an adsorbent contaminant as chlorine; (b) a value in parts per million of ions in the effluent solution; (c) the reduction in quality of the effluent water determined by a conductivity bridge which measures the resistance of the water to the flow of an electric current. |
| Facultative bacteria | Bacteria that can live under aerobic or anaerobic conditions due to their ability to use either molecular (dissolved) oxygen or oxygen obtained from nutritive sources. |
| Fast rinse | In a water softener, a rapid rinse process at the end of brine regeneration to remove final traces of chlorides and reduce regeneration time. |
| Fecal coliform | The coliform bacteria group present in the intestinal tracts of warm blooded animals including humans. Potable water with fecal coliform can cause illness. |
| Feed water | This refers to the incoming water of a water treatment system that has not yet been treated. Also called raw water or source water. |
| Fermentation | The conversion of organic matter to methane, carbon dioxide and other molecules by anaerobic bacteria. |
| Ferric chloride/ ferric sulphate | Iron-containing substances that are used to coagulate and flocculate in various effluent treatment processes. |
| Ferric iron | The cause of ?rusty? water, this type of iron consists of small, solid particles containing trivalent iron, usually as gelatinous ferric hydroxide or ferric oxide (Fe2O3). Ferrous iron in solution is readily converted to ferric iron by exposure to oxygen. Filtraton removes ferric iron, which is also known as precipitated iron. It cannot be removed by ion exchange. |
| Ferrous iron | Usually ferrous hydroxide, which, when dissolved in water, produces a clear solution ? the basis of its other name, clear water iron. It can be removed by ion-exchange. |
| Filox-R | A naturally occurring ore used as a catalytic filter media in the removal of iron, hydrogen sulfide and manganese. While it normally requires only backwashing, the use of oxidizers (such as chlorine or potassium permanganate) enhances its action. |
| Filter | A device for separating solid particles or impurities from water by passing it through a porous substance. Filters are used remove iron, silt, taste, odor, color, etc., from water before it is fed into the softener or supply lines of the consumer. There are mechanical, adsorptive, oxidizing and neutralizing filters, available as media beds in tanks, or as cartridge-type devices. |
| Filter-Ag | Trade name for an aluminum silicate (pumicite) granular product that is used as a general purpose filter medium. Lighter in weight, it requires a lower backwash rate. Typically removed suspended solids down to the 20-40 micron range. |
| Filter medium | The permeable material that separates solids from liquids passing through it. |
| Filter press | A device that dewaters sludge by compressing it between membranes or cloth-lined plates to produce a cake. |
| Filtrate | A liquid that has passed through the filter medium; the effluent from a filtration system. |
| Filtration | The process of passing water through a porous substance to remove solids in suspension. |
| Fine bubble diffuser | An aeration device in which air is blown through a porous ceramic or synthetic membrane, creating small bubbles in a liquid effluent |
| Fines | Smaller-than-the-specified-size (or particles of) ion exchange or filtration materials. An excess of fines can create undesirable pressure drop in the system. |
| First draw | The water that comes out when a tap is first opened, likely to possess the highest level of lead contamination from weathering of pipelines. |
| Fission | Reproduction of micro organisms by means of cell division. |
| Fixture count | A determination of the total number of plumbing fixtures in a building, used to estimate peak flow rates and to correctly size equipment in industrial and commercial buildings. |
| Fixture unit | An arbitrary unit assigned to different type of plumbing fixtures used to estimate flow rate and drain capacity requirements. |
| Flash distillation | A process in which hot water is introduced into a low pressure chamber, which causes some of the water to ?flash? or quickly turn into steam. |
| Floc | A clump of solids formed in sewage by biological or chemical action, a flocculent mass (floc) is formed in the accumulation of suspended particles. Although it can occur naturally, floc is usually induced in order to be able to remove certain particles from wastewater. |
| Flocculants | Materials added to water that cause gelatinous clouds of precipitate to enclose fine particles of foreign material in order to settle or filter them (from the water). |
| Flocculation | Flocculation is the agglomeration of coagulated particles to form a floc that can settle or float. |
| Floodplain | The land along a waterway that is covered by water during a flood, usually flat or very nearly so. |
| Flotation | A solids-liquid or liquid-liquid separation procedure, applied to particles of which the density is lower than that of the liquid they are in. Flotation may be either natural, aided or induced. |
| Flow | The discharge rate of a resource, expressed in volume during a certain period of time. |
| Flow augmentation | The addition of water to meet flow needs. |
| Flow controller | An in-line device (or orifice fitting) that regulates and controls to a predetermined value the flow of water or regenerant through a water conditioner over a broad range of inlet water pressures. |
| Flowmeter | A gauge that shows the speed of wastewater moving through a treatment plant. Also used to measure the speed of liquids moving through various industrial processes. |
| Flow rate | The volume of solution which passes through a given quantity of resin within a given time, usually expressed in terms of gallons per minute per cubic foot of resin, or as milliliters per minute per milliliter of resin. If the flow rate is greater than it should be, the water will not be completely softened or filtered. |
| Fluidized bed | A body of solid particles through which gas or liquid is blown or pumped upwards causing separation and movement; a means of increasing reaction rates |
| Fluidized bed scrubber | A device that removes pollutant particles or trace gases from a gas stream, in which plastic spheres are wetted by a scrubbing liquor and fluidized by the contaminated gas stream. |
| Fluoridation | The addition of a fluoride compound to a water supply to produce the concentration desired for the reduction in incidence of dental caries. |
| Fluorides | Gaseous, solid, or dissolved compounds containing fluorine that result from industrial processes. Excessive amounts in food can lead to fluorosis, which causes brown mottled stains on teeth. |
| Fluorocarbon (FCs) | Any of a number of organic compounds analogous to hydrocarbons in which one or more hydrogen atoms are replaced by fluorine. Primarily used in coolants and some industrial processes. FCs containing chlorine are called chlorofluorocarbons (CFCs). They are believed to be modifying the ozone layer in the stratosphere, thereby allowing more harmful solar radiation to reach the Earth?s surface. |
| Flush valve (Flushometer) | A self-closing valve used for flushing urinals and toilets. This type of valve allows flow rates of 15-20 gpm for up to 10 seconds. |
| Flux | The quantity of solution that passes through a unit of membrane area in a given amount of time. For example, a membrane element might have a flux of 10 liters per minute per square meter (volume unit per time per membrane area). In crossflow filtration, it is the product flow rate through a reverse osmosis, electrodialysis or ultrafiltration membrane. |
| FOG | Acronym for fats, oils and grease, the common wastewater components from food preparation, animal and/or vegetable processing. They are largely insoluble in water and likely to float |
| Formaldehyde | A colorless, pungent, irritating gas, CH20, used chiefly as a disinfectant and preservative and in synthesizing other compounds and resins. Commercial grades are called formalin. |
| Fouling | In membrane filtration applications, the deposition of organic matter on the membrane surface, which causes inefficiencies. In ion exchange, the accumulation of undesirable foreign matter in a bed of filter media which clogs pores and coats surfaces, thereby inhibiting or retarding proper operation of the bed. |
| Fragmentation | The subdivision of a solid in fragments. The fragments will then adhere to the nearest surface. |
| Freeboard | The vertical distance between a bed of filter media or ion exchange material and the overflow or collector for backwash water; the height above the bed of granular media available for bed expansion during backwashing. It may be expressed either as a linear distance or a percentage of bed depth. |
| Freezing | The change of a liquid into a solid as temperature decreases. For water, the freezing point is 0 degrees Celsius, 32 degrees Fahrenheit. |
| Freshwater | Water containing less than 1 mg/l of dissolved solids of any type. Water containing less than 500 parts per million (ppm) solids. Water above 1,000 ppm is not recommended to be used for human consumption. |
| Fume | solid particles smaller than 1µm in a gaseous emission |
| Fungi (Singular, Fungus) | Molds, mildews, yeasts, mushrooms, and puff-balls, a group organisms that lack chlorophyll (i.e., are not photosynthetic) and which are usually non-mobile, filamentous, and multicellular. Some grow in the ground, others attach themselves to decaying trees and other plants, getting their nutrition from decomposing organic matter. Some cause disease; others stabilize sewage and break down solid wastes in composting. Fungicide: Pesticides that are used to control, prevent, or destroy fungi. |
| GAC | Granular activated carbon. |
| Gallon | A unit that is now almost entirely out of date. It is equivalent to 3.785 liters. A common unit of liquid volume; the US gallon has a volume of 231 cubic inches or 3.78533 liters; the British (Imperial) gallon has a volume of 277.418 cubic inches or 4.54596 liters |
| Galvanic action | A form of corrosion that occurs when dissimilar metals in contact with each other and with an electrolyte causes on e of the metals to dissolve and go into solution. An example would be the result of connection copper to steel without an insulating (plastic) coupling or union. The anode metal with the higher electrode potential corrodes and the cathode is protected. |
| Germicide | A compound that kills disease-causing microorganisms. |
| Giardia | A micro organism that is commonly found in untreated surface water and can be removed by filtration. It is resistant to disinfectants such as chlorine. |
| Giardia lamblia | A common protozoan found in water and is derived from animal droppings. It can cause contagious waterborne disease characterized by acute diarrhea. It is resistant to disinfectants such as chlorine, iodine, or ultraviolet light. Giardia can be removed by filters of four micron rating. |
| Grain (gr) | A unit of weight equal to 1/7000th of a pound or 0.0648 gram. |
| Grains per gallon (GPG) | An expression of concentration of material in solution. One grain per gallon is equivalent to 17.1 parts per million. This is the common reference for hardness of water. A common basis for reporting water analyses in the United States and Canada; one grain per U.S. gallon equals 17.12 milligrams per liter (mg/1) or parts per million (ppm). |
| Gram (g) | The basic unit of weight (mass) of the metric system originally intended to be the weight of 1 cubic centimeter of water a 4 degree C. |
| Granular activated carbon | The heating of carbon to encourage active sites to absorb pollutants. |
| Granular activated carbon treatment | A filtering system often used in small water systems and individual homes to remove organics. GAC can be highly effective in removing elevated levels of radon from water. |
| Gravel support bed | A layer or layers of graded gravel and course sand placed around and above the underdrain metalwork of a water treatment system. It facilitates even distribution and collection of both product water and backwash flow. |
| Gray water | Untreated domestic wastewater composed of wash water from kitchen, bathroom, and laundry sinks and from tubs, and washers. |
| Greenhouse effect | The warming of the Earth?s atmosphere caused by a build-up of carbon dioxide or other trace gases; it is believed by many scientists that this build-up allows light from the sun?s rays to heat the Earth but prevents a counterbalancing loss of heat. |
| Greensand | A natural mineral primarily composed of complex silicates, which possess ion exchange properties. Greensand was the original material used in domestic and commercial water softeners and is the base product in the production of manganese greensand. |
| Groundwater | Water that can be found in the saturated zone of the soil; a zone that consists merely of water. It slowly moves from places with high elevation and pressure to places with low elevation and pressure, such as rivers and lakes. The term describing all subsurface water and the source of well water. It can be found in aquifers as deep as several miles. The water that systems pump and treat from aquifers (natural reservoirs below the earth's surface). The term describing all subsurface water and the source of well water. It can be found in aquifers as deep as several miles. |
| Groundwater discharge | Ground water entering coastal waters, which has been contaminated by land-fill leachates, deep well injection of hazardous wastes and septic tanks. |
| Groundwater hydrology | The branch of hydrology that deals with the occurrence, movements, replenishment and depletion, properties and methods of investigation and utilisation of groundwater. |
| Gully | A deeply eroded channel created by the concentrated flow of water. |
| Gypsum | A moderately insoluble calcium sulfate containing 20.9 percent water. It is often used to build soil structure and permeability. |
| Half-life | The time required for a pollutant to lose one-half of its original concentration. |
| Halite | A geological term for rock salt, a mineral that is more than 95 percent sodium chloride. Also known as native or fossil salt. |
| Halogenated hydrocarbons | organic compounds containing carbon, hydrogen and halogen atoms (fluorine, chlorine, bromine and iodine); implicated in stratospheric ozone loss |
| Halogens | A family of elements that includes bromine, chlorine, fluorine, astatine, and iodine. They are very active chemically. They are commonly found as the ionic component in compounds with various other elements. |
| Hardness | A characteristic of natural water due to the presence of dissolved calcium and magnesium; water hardness is responsible for most scale formation in pipes and water heaters, and forms insoluble "curd" when it reacts with soaps. Hardness is usually expressed in grains per gallon, parts per million, or milligrams per liter, all as calcium carbonate equivalent. Temporary hardness, caused by the presence of magnesium of calcium bicarbonate, is so called because it may be removed by boiling the water to convert the bicarbonates to the insoluble carbonates. Calcium sulfate, magnesium sulfate, and the chlorides of these two metals cause permanent hardness. |
| Hardness leakage | The presence in the effluent of the type of ions present in the water being treated. Leakage may be caused by incomplete regeneration, channeling, excessive service water, low temperature, and high concentrations of sodium or interfering TDS in the feedwater. |
| Hard water | Water that contains a great number of positive ions. The hardness is determined by the number of calcium and magnesium atoms present. Soap usually dissolves badly in hard water. Water with a total hardness of one grain per gallon or more, as calcium carbonate equivalent. |
| Hazardous waste | Waste that originates from a specified waste stream or has hazardous properties or contains hazardous substances as defined in the Hazardous Waste Directive |
| Header | A central piping system with two or more side outlets located at the bottom of a water conditioning system. Its purpose is to both collect product water as well as to distribute backwash water. |
| Head loss | The reduction on liquid pressure associated with the passage of a solution through a bed of exchange material; a measure of the resistance of a resin bed to the glow of the liquid passing through it. |
| Heat exchanger | A component that is utilized to remove heat from or ad heat to a liquid. |
| Heavy metals | certain metals, used industrially and harmful to living organisms, for which discharge and emission standards are set; including cadmium, chromium, copper, lead, mercury, nickel and zinc. Metallic elements with high atomic weights, e.g.. mercury, chromium, cadmium, arsenic and lead. They can damage living things at low concentrations and tend to accumulate in the food chain. |
| Heavy water | Water in which all the hydrogen atoms have been replaced by deuterium. |
| Heme iron | Organically bound iron that can give water a pinkish cast. It is found only in groundwater supplies and cannot be removed by filtration. Like soluble iron, heme iron stains fixtures with a rust or orange coloring. It may draw clear and turn yellow or pink when exposed to oxygen. Call Toll Free 877-262-5191, International 316-262-5191 for a product solution. |
| Hemodialysis | The process of purifying a kidney patients blood by means of a dialysis membrane. In this process bodily waste is transferred from the blood into a hemodialysis grade water that is beyond the membrane. |
| Henry's Law | A way of calculating the solubility of a gas in a liquid, based on temperature and partial pressure, by means of constants. |
| Heterotrophic | Non-disease causing bacteria |
| Hexametaphosphate | A chemical, such as sodium hexametaphosphate, added to water to increase the solubility of certain ions and to inhibit precipitation of certain chemicals. Known as a sequestering agent, it forms a thin film that protects metals from corrosion. |
| High performance filter | a device that separates particles 2-500 µm in size from relatively clean liquid streams |
| Holding pond | A pond or reservoir, usually made of earth, built to store polluted runoff. |
| Homeowner water system | A water system that supplies piped water to a single residence. |
| Hot lime (soda softening) | Partially softens water by adding lime and soda ash at a water temperature of about 212 degrees Fahrenheit. It chemically precipitates calcium, magnesium, iron, and silica. It also drives away carbon dioxide. |
| Humidification | The addition of water vapor to air. |
| Hydraulic classification | The rearrangement of resin particles in an ion exchange unit. As the backwash water flows up through the resin bed, the particles are placed in a mobile condition wherein the larger particles settle and the smaller particles rise to the top of the bed. |
| Hydraulic conductivity | The rate at which water can move through a permeable medium. |
| Hydraulic gradient | In general, the direction of groundwater flow due to changes in the depth of the water table. |
| Hydrocarbon | Organic compounds that are built of carbon and hydrogen atoms and are often used in petroleum industries. |
| Hydrocyclone | A device that separates sand, silt and suspended solid particles from a liquid using centrifugal forces generated by the liquid flow |
| Hydroelectric power water use | The use of water in the generation of electricity at plants where the turbine generators are driven by falling water. |
| Hydrogen cycle | A complete course of cation exchange operation in which the cation medium is regenerated with acid and them all cations in the water are removed by exchange with hydrogen ions. |
| Hydrogen sulfide (H2S) | A foul smelling gas, which strongly smells like rotten eggs, and is a product of the reduction of organic sulphur by anaerobic organisms. Also a corrosive and flammable gas produced from decaying organic matter and emitted during organic decomposition by a select group of bacteria. Commonly known as "sulfur". |
| Hydrogeology | The science of chemistry and movement of groundwater. |
| Hydrograph | A chart that measures the amount of water flowing past a point as a function of time. |
| Hydrologic cycle | The water cycle, including precipitation of water from the atmosphere as rain or snow, flow of water over or through the earth, and evaporation or transpiration to water vapor in the atmosphere. It is nature?s great water conditioner since all contaminants are left behind on the earth. The natural cycle of water passing through the environment, including evaporation, condensation, retention and run-off. The water cycle, including precipitation of water from the atmosphere as rain or snow, flow of water over or through the earth, and evaporation or transpiration to water vapor in the atmosphere. (See Transpiration) |
| Hydrolysis | The decomposition of organic compounds by interaction with water. |
| Hydrophilic | Having an affinity for water. |
| Hydrophobic | Having an aversion for water. |
| Hydrosphere | Region that includes all the earth's liquid water, frozen water, floating ice, frozen upper layer of soil, and the small amounts of water vapor in the atmosphere. |
| Hydro static pressure | A measurement of structural strength and ability to hold water pressure. Hydrostatic pressure is more challenging to a system than air pressure because air will compress and absorb impact, whereas water will not. |
| Hydroxyl | The term used to describe the anionic hydroxide radical (OH-) that is responsible for the alkalinity of a solution. |
| Hypo chlorite | An anion that forms products such as calcium and sodium hypochlorite. These products are often used for disinfection and bleaching. |
| Hypoxic waters | Waters with dissolved oxygen concentrations of less than 2 mg/L, the level generally accepted as the minimum required for life and reproduction of aquatic organisms. |
| Ice | The solid form of water. |
| Imhoff cone | A clear, cone-shaped container used to measure the volume of settle able solids in a specific volume of water. |
| Immiscibility | The inability of two or more solids or liquids to readily dissolve into one another. |
| Impermeable | Not easily penetrated by water. |
| Impurities | Particles or other objects that cause water to be unclear. |
| Incineration | The controlled burning of municipal, clinical and chemical waste material and sewage sludge, commonly in two stages, to produce minimum amounts of gas and ash |
| Indicator | Any biological entity or process, or community whose characteristics show the presence of specific environmental conditions or pollutants. |
| Indicator organisms | Micro organisms, such as coliforms, whose presence is indicative for pollution or for the presence more harmful micro organisms. |
| Indicator tests | Tests for a specific contaminant, group of contaminants, or constituent that signals the presence of something else. |
| Indirect discharge | Introduction of pollutants from a non-domestic source into a publicly owned wastewater treatment system. Indirect dischargers can be commercial or industrial facilities whose wastes enter local sewers. |
| Industrial user | Primarily manufacturers or processors or materials using water within those processes. |
| Infiltration | Penetration of water into a medium, for instance the soil. 1. The penetration of water through the ground surface into sub-surface soil or the penetration of water from the soil into sewer or other pipes through defective joints, connections, or manhole walls. 2. A land application technique where large volumes of waste water are applied to land, allowed to penetrate the surface and percolate through the underlying soil. (See: percolation |
| Inflow | Entry of extraneous rain water into a sewer system from sources other than infiltration, such as basement drains, manholes, storm drains, and street washing. |
| Influent | The stream of water that enters any system or treatment unit. Water, wastewater, or other liquid flowing into a reservoir, basin, or treatment plant. See Feed. |
| Inhibitor | Chemical that interferes with a chemical reaction, such as precipitation. |
| Injection | The introduction of a chemical or medium into the process water to alter its chemistry or filter specific compounds. |
| Inorganic | Substances such as sand, clay and metals whose molecular structures do not contain carbon-hydrogen (C-H) bonds except as carbonates and similar; Matter which is not derived from living organisms and contains no organically produced carbon; includes rocks, minerals and metals. Inorganic chemicals are chemical substances of mineral origin, not of basically carbon structure. Mineral-based compounds such as metals, nitrates, and asbestos. These contaminants are naturally-occurring in some water, but can also get into water through farming, chemical manufacturing, and other human activities. EPA has set legal limits on 15 inorganic contaminants. |
| Inorganic matter | Matter that is not derived from living organisms and contains no organically produced carbon; includes rocks, minerals and metals. |
| In-parallel flow | A piping arrangement that directs separate streams through two or more water treatment units in a balanced manner, providing equal flow to each device. The inlets of two or more units are connected together and the outlets are connected together such that water will flow through the units simultaneously. |
| Insecticide | A pesticide compound specifically used to kill or control the growth of insects. |
| In-series flow | A piping system in which all of the effluent flow of one unit in a water treatment system is fed to a second and succeeding unit. This arrangement achieves a greater reduction of contaminants than can be obtained by the passage through a single unit. |
| Iodine number | A measure of the ability of activated carbon to adsorb substances with low molecular weights. It is the milligrams of iodine that can be adsorbed on one gram of activated carbon. |
| Ion | An atom in a solution that is charged, either positively (cations) or negatively (anions). An atom, or group of atoms in a solution which function as a unit, and has a positive or negative electrical charge, due to the gain or loss of one or more electrons. It is smaller than a colloid. An electrically charged atom or group of atoms that can be drawn from waste water during the electrodialysis process. |
| Ion exchange | The replacement of undesirable ions with a certain charge by desirable ions of the same charge in a solution, by an ion-permeable absorbent. A reversible process in which ions are released from an insoluble permanent material in exchange for other ions in a surrounding solution; the direction of the exchange depends upon the affinities of the ion exchanger for the ions present and the concentration of the ions in the solution. The ion exchanger media is an insoluble permanent solid medium. |
| Ion exchange treatment | A common water softening method often found on a large scale at water purification plants that remove some organics and radium by adding calcium oxide or calcium hydroxide to increase the ph to a level where the metals will precipitate out. |
| Ion exchanger | A permanent, insoluble material that contains ions that will exchange reversibly with other ions in a surrounding solution. Both Cation and anion exchangers are used in water conditioning. |
| Ionization | The process in which atoms gain or lose electrons and thus become ions with positive or negative charges; sometimes used as synonymous with dissociation, the separation of molecules into charged ions in solution. The dissociation of molecules into simpler, electronically charged particles. It is related to the gaining or losing of electrons causing the atoms to become electronically charged. |
| Iron | An element often found dissolved in ground water (in the form of ferrous iron) in concentrations usually ranging from zero to 10 ppm (mg/l). It is objectionable in water supplies because of the staining caused after oxidation and precipitation (as ferric hydroxide), because of tastes, and because of unsightly colors produced when iron reacts with tannins in beverages such as coffee and tea. As little as 0.3 ppm of iron can cause staining. (See also ferrous iron, ferric iron, and heme iron). |
| Iron bacteria | Organisms that are capable of utilizing ferrous iron, either from the water or from steel pipe, in their metabolism, and precipitating ferric hydroxide in their sheaths and gelatinous deposits. These organisms tend to collect in pipe lines and tanks during periods of low flow, and to break loose in slugs of turbid water to create staining, taste and odor problems. |
| Iron fouling | The accumulation of iron on and within an ion exchange resin or filter bed resulting in a reduced capacity of the media. |
| Irrigation | Applying water or wastewater to land areas to supply the water and nutrient needs of plants. |
| Jackson Turbidity Unit (JTU) | An arbitrary unit of turbidity originally based on a suspension of specific type of silica with the turbidity measured in a Jackson Candle Turbidimeter. This has been replaced by the nephelometric turbidity unit (NTU). |
| Jar test | A laboratory test procedure with differing chemical doses, mix speeds, and settling times, to estimate the minimum or ideal coagulant dose required to achieve water quality goals. |
| KDF | A water treatment media employing copper and zinc alloy particulates that have a redox potential. KDF does not support the growth of bacteria and lasts up to twenty times longer than activated carbon. KDF 55 granules are effective in removing chlorine and other water-soluble heavy metals such as lead. KDF 85 is the choice for removing iron and hydrogen sulfide. |
| Kilograin | A unit of weight; one thousand grains, 17100 ppm, or 0.1429 pounds. |
| Kinetic Energy | Energy possessed by moving water. |
| Kinetic rate coefficient | A number that describes the rate at which a water constituent such as a biochemical oxygen demand or dissolved oxygen rises or falls. |
| Kinetics | The study of the relationships between temperature, motion, and the velocity of very small particles. It is used to describe the rate of ion exchange reactions. |
| Laboratory water | Purified water used in the laboratory as a basis to create solutions or making dilutions. It contains no interfering substances. |
| Lagoon | A shallow pond where sunlight, bacterial action, and oxygen work to purify wastewater. (1) A shallow pond where sunlight, bacterial action, and oxygen work to purify wastewater; also used to storage of wastewaters or spent nuclear fuel rods. (2) Shallow body of water, often separated from the sea by coral reefs or sandbars. |
| Lake | An inland body of water, usually fresh water, formed by glaciers, river drainage, etc. It is usually larger than a pool or pond. |
| Laminar flow | A flow in which rapid fluctuations are absent. |
| Langelier index (LI) | An index reflecting the equilibrium pH of a water with respect to calcium and alkalinity; used in stabilizing water to control both corrosion and scale deposition. A calculated number that gives and indication of the tendency of water to form a protective film of calcium carbonate scale, to dissolve it or be in equilibrium with it. It does not take into account the quantities of film formed, the effect of velocities, oxygen, carbon dioxide, ammonia, silicon or natural inhibitors in the water. Therefore, it is sometimes erroneously assumed that any water that tends to dissolve calcium carbonate is automatically corrosive. A calculated number used to predict whether or not a water will precipitate, be in equilibrium with, or dissolved calcium carbonate. It is sometimes erroneously assumed that any water that tends to dissolve calcium carbonate is automatically corrosive. |
| Land application | Discharge of wastewater onto the ground for treatment or reuse. |
| Large water system | A water system that services more than 50,000 customers. |
| Leachate | liquid that has percolated through a solid mass; soil leachate may be high in nitrate; landfill leachate may be high in BOD, ammonia, salinity and toxic substances. A liquid that results from water collecting contaminants as it trickles through wastes, agricultural pesticides or fertilizers. Leaching may occur in fanning areas, feedlots, and landfills, and may result in hazardous substances entering surface water, ground water, or soil. |
| Leachate collection system | A system that gathers leachate and pumps it to the surface for treatment. |
| Leach field | Area where septic tank effluent is distributed by underground piping for natural leaching and percolation through the soil. |
| Leaching | The process by which soluble constituents are dissolved and filtered through the soil by a percolating fluid. |
| Leakage | A species of ions in the feed of an ion exchanger present in the effluent. The phenomenon in which some of the influent ions are not adsorbed and appear in the effluent. It is usually caused by an under-regenerated exchange resin bed or by excessive flow rate. |
| Leak correlator | A device used to determine the location of a leak in a water system by means of probes attached to the exposed portions of that system. |
| Legionella pneumophila | A water-borne pathogenic bacterium which causes Legionnaires' Disease; may be present in cooling systems and spread by droplets; controlled by chlorination, ozone, silver-copper, ultraviolet light. A series of bacteria, including Legionella pneumophila, which can cause pneumonia-like illness called Legionnaires disease after the American Legion convention in Philadelphia where the disease first drew attention. These bacteria have been found growing in hard water scale and thrive below 140 degrees Fahrenheit in water heaters, showers, humidifiers, etc. Infection is obtained by inhalation. |
| Light absorption | The amount of light a certain amount of water can absorb over time. |
| Lime | The common name for calcium oxide (CaO); hydrated lime is calcium hydroxide, Ca (OH)2. Common water treatment chemical. Lime can be deposed on walls of showers and bathrooms, after lime has reacted with calcium to form limestone. |
| Lime scale | Hard water scale containing a high percentage of calcium carbonate. Insoluble scale is commonly formed when water containing calcium carbonate is heated. It also forms in cold water but precipitates at a higher pH. |
| Lime softening | Often used by municipalities for partial reduction of water hardness. After the addition of baked lime, soda ash is added to form an insoluble precipitate that is filtered from the water. This method leaves five or more grains of hardness |
| Limnology | The study of the physical, chemical, hydrological, and biological aspects of fresh water. |
| Liquid | A state of matter, neither gas nor solid, that flows and takes the shape of its container. |
| Macroporous resin | Ion exchange resins produced in both cation and anion versions with 12 percent or higher cross-linkage. They offer a higher resistance to oxidation and organic fouling. |
| Magnesium | One of the elements making up the earth's crust, the compounds of which when dissolved in water make the water hard. The presence of magnesium in water is a factor contributing to the formation of scale and insoluble soap curds. |
| Manganese (Mn) | A element sometimes found dissolved in ground water, usually with dissolved iron but in lower concentrations. It causes black stains in laundry and plumbing fixtures at concentrations higher than 0.05 mg/l. It is removed the same way as iron, by ion-exchange or oxidation and filtration. |
| Manganese greensand | Greensand that has been processed to incorporate in its pores and on its surface the higher oxides of manganese. The product has a mild oxidizing power, and is often used in the oxidation and precipitation of iron, manganese and/or hydrogen sulfide, and their removal from water. It is regenerated by the use of two to four ounces of a weak solution of potassium permanganate per cubic foot of manganese greensand. |
| Makeup water | The fresh water added into a cooling tower to replace blowdown and/or evaporation losses. |
| Maximum Contaminant Level (MCL) | The maximum level of a contaminant allowed in water by federal law. Based on health effects and currently available treatment methods. A drinking water standard. The maximum amount of a contaminant allowed in drinking water. The highest level of a contaminant that EPA allows in drinking water. MCLs ensure that drinking water does not pose either a short-term or long-term health risk. EPA sets MCLs at levels that are economically and technologically feasible. |
| MCLG | Maximum Contaminant Level Goal. The goal set for the maximum amount of a contaminant to be allowed in drinking water. Has not been approved to become the MCL. The level of a contaminant at which there would be no risk to human health. This goal is not always economically or technologically feasible, and the goal is not legally enforceable. |
| Mechanical aeration | Use of mechanical energy to inject air into water to cause a waste stream to absorb oxygen. |
| Mechanical filter | A filter primarily designed for the removal of suspended solid particles, as opposed to filters that remove contaminants by chemical means. |
| Mechanical flotation | A term used in the mineral industry to describe the use of dispersed air to produce bubbles that measure 0.2 to 2 mm in diameter. |
| Mechanical turbulence | Random irregularities of fluid motion in air caused by buildings or mechanical, non-thermal, processes. |
| Media | Materials that form a barrier to the passage of certain suspended solids or dissolved liquids in filters. Media stones, pebbles or plastic that provides a substrate for the growth of a film of microorganisms in wastewater treatment; plastic, ceramic or metal shapes or surfaces that improve gas-liquid contact in gas scrubbing. Also called depth filters. A variety of media types may be employed in this type of filtration device, depending on the objective of this part of the water treatment system. Sand has been employed in this type of filter for many decades. Media type filters are recommended for applications where large quantities of suspended particles need to be removed economically. Usually the media is permanent, so maintenance costs are very low. The device is typically designed with graded media beds, arranged according to size. The spaces between the particles of sand or other media determine the size of particles that will be removed. The depth of the filter base is also a critical design criteria. Water flows downward through a distributor, through the graded media beds, and is collected by another set of distributors installed in the bottom of the tank. The particles are left behind in the media beds. Cleaning is accomplished by backwashing, or reversing the flow. This flow lifts the media beds and dislodges the particles trapped there. These are then washed away with the backwash fluid and discharged. Media filters are often employed as one of the first parts of the pretreatment system in membrane type water treatment systems. Usually, additional filtration afterwards is also required, as the particle size removed by media filters is not small enough to provide good membrane protection. |
| Medium-size water system | A water system that serves 3,300 to 50,000 customers. |
| Melting | The change of a solid into a liquid. |
| Membrane | A thin barrier that allows some compounds or liquids to pass through, and troubles others. It is a semi-permeable skin of which the pass-through is determined by size or special nature of the particles. Membranes are commonly used to separate substances. The term membrane generally refers, not only to the barrier layer described above that is technically the membrane, but also to the entire engineered membrane separation device, including the micro-porous support, the non-woven support material, the carriers, product tube, anti-telescoping device, and the construction of the element. The most commonly used membrane element type is a spiral wound membrane element. |
| Membrane element | The package containing the membrane and equipped with the necessary fittings to allow the feed stream to enter, and the permeate and concentrate streams to exit. The membrane element enables the membrane to effect separation. Synonyms are ?membrane device? and ?membrane module?. The general categories of membrane element configuration are: ?spiral wound?, ?capillary (hollow) fiber?, ?tubular? and ?plate and frame? |
| Mercury | A heavy metal that can accumulate in the environment and is highly toxic if breathed or swallowed. (See: heavy metals.) |
| Mesotrophic | Reservoirs and lakes that contain moderate quantities of nutrients and are moderately productive in terms of aquatic animal and plant life. |
| Metabolise | Conversion of food, for instance soluble organic matter, to cellular matter and gaseous by-products through a biological process. |
| Methane (CH4) | Highly calorific gas; 60 percent of biogas; produced during anaerobic biological processes; may contribute to global warming A colorless, nonpoisonous, flammable gas created by anaerobic decomposition of organic compounds. |
| MFS | Micro Filtration System, it serves full automatic solid/ liquid separation. |
| Microbial growth | The multiplication of micro organisms such as bacteria, algae, diatoms, plankton, and fungi. |
| Microfiltration | The use of microporous filters operating under pressure to remove particles or microorganisms of 0·1-5·0 µm size from process and effluent liquids a membrane based fluid treatment technology, employing all the parameters of other membrane technologies, but with a larger pore size. Operating parameters are similar to those for U/F, but pore sizes are larger. |
| Microgram per Liter | Also known as parts per billion (ppb). The common symbol for microgram per liter is µg/L. |
| Microhm | One millionth of an ohm. A unit of measurement used to test the electrical resistance of water to determine its purity. The purer the water, the greater its resistance to conducting an electrical current. Water of absolute purity has a resistance of eighteen million ohms across one centimeter at a temperature of twenty-five degrees Celsius. |
| Micromho | One millionth of a mho. Used to measure the conductivity and the approximate TDS content of water. Absolute pure water has a conductivity of 0.055 micromhos per centimeter at 25 degrees Celsius. Also known as micro Siemens. The specific conductance is the reciprocal of resistance, therefore MHO is OHM spelled backwards. |
| Micron | A unit to describe a measure of length, equal to one millionth of a meter. A linear measure equal to one millionth of a meter, or .00003937 inch. The symbol for the micron is the Greek letter "µ". The smallest particle visible to the human eye is 40 microns. Most types of bacteria range from 0.05 to 10.0 microns in size. |
| Micron rating | The term applied to a filter or filter medium to indicate the particle size above which all suspended solids will be removed, throughout the rated capacity. As used in industry standards, this is an "absolute", not "nominal" rating. |
| Micro organisms | Organisms that are so small that they can only be observed through a microscope, for instance bacteria, fungi or yeasts; protozoa and algae. |
| Microwave disinfection unit | Equipment that shreds clinical waste and disinfects it with steam and microwave radiation |
| Milligram per Liter | (mg/L) A unit concentration of matter used in reporting the results of water and wastewater analyses. In dilute water solutions, it is practically equal to the part per million, but varies from the ppm in concentrated solutions such as brine. As most analyses are performed on measured volumes of water, the mg/l is a more accurate expression of the concentration, and is the preferred unit of measure. |
| Mineral | A term applied to inorganic substances, such as rocks and similar matter found in the earth's strata, as opposed to organic substances such as plant and animal matter. Minerals normally have definite chemical composition and crystal structure. The term is also applied to matter derived from minerals, such as the inorganic ions found in water. The term has been incorrectly applied to ion exchangers, even though most of the modern materials are organic ion exchange resins. |
| Mineral water | Contains large amounts of dissolved minerals such as calcium, sodium, magnesium, and iron. Some tap waters contain as many or more minerals than some commercial mineral waters. There is no scientific evidence that either high or low mineral content water is beneficial to humans. |
| Miscibility | The ability of two liquids to mix. |
| Mist | Liquid particles measuring 40 to 500 micrometers, are formed by condensation of vapor. By comparison, fog particles are smaller than 40 micrometers; very small droplets of liquid suspended in a gas |
| Mist eliminator | Unit that separates small droplets of liquid (mist) from gas streams by impingement on a mesh or plate surface; part of a wet scrubber |
| Mixture | Various elements, compounds or both, that are mixed. |
| Molecular weight cutoff (MWCO) | Referred to as the molecular weight above which a certain percentage (e.g., >90 percent) of the solute in the feed solution is rejected by the membrane. It is typically expressed in units of Daltons and used as an indication of the pore size of ultrafiltration and nanofiltration membranes. |
| Molecules | Combinations of two or more atoms of the same or different elements held together by chemical bonds. The simplest combination of atoms that will form a specific chemical compound; the smallest particle of a substance which will still retain the essential composition and properties of that substance, and which can be broken down only into atoms and simpler substances. |
| Municipal discharge | Discharge of effluent from wastewater treatment plants, which receive wastewater from households, commercial establishments, and industries in the coastal drainage basin. |
| Municipal sewage | Liquid wastes, originating from a community. They may have been composed of domestic wastewaters or industrial discharges. |
| Municipal sludge | Semi liquid residue that remains from the treatment of municipal water and wastewater. |
| Nanofiltration | A membrane process that treats water between reverse osmosis and ultrafiltration the filtration/separation spectrum. It can remove particles in the 300 to 1,000 molecular weight range such as humic acid and organic color found in water. Nanofiltration may |
| Negative charge | The electrical charge on an electrode or ion in solution, due to the presence of and excess of electrons. |
| Nephelometric Turbidity Unit (NTU) | The standard unit of measurement used to measure turbidity in water. It makes use of a light scattering effect of fine suspended particles in a light beam. The NTU has replaced the Jackson Turbidity Unit (JTU) as the standard of measurement. |
| Net driving pressure | Applied (pump) pressure minus the sum of all back pressures [osmotic pressure, pipe pressure losses, head (elevation) losses, etc.] |
| Neutralization | The addition of substances to neutralize water, so that it is neither acid, nor basic. Neutralization does not specifically mean a pH of 7.0; it just means the equivalent point of an acid-base reaction. |
| Neutralizer | A common designation for alkaline materials such as calcite (calcium carbonate) or magnesia (magnesium oxide) used in the neutralization of acid waters. Alkaline water can also be neutralized by the addition of an acid. The neutral point of the pH scale i |
| Neutrons | Uncharged building blocks of an atom that play a part in radioactivity. They can be found in the nucleus. |
| Nitrate (NO3-) | the most oxidised form of nitrogen; formed from the oxidation of ammonia by aerobic bacteria; present in fertilizer; the preferred form of nitrogen in discharges to rivers. A compound containing nitrogen which can exist in the atmosphere or as a dissolved |
| Nitrate sensitive area | a defined area, designated by statutory order, within which measures are taken to minimize the leaching of nitrates from agriculture into groundwater |
| Nitrification | A biological process, during which nitrifying bacteria convert toxic ammonia to less harmful nitrate. It is commonly used to remove nitrogen substances from wastewater, but in lakes and ponds it occurs naturally. |
| Nitrifying bacteria | Aerobic bacteria that convert ammonia (NH3) into nitrate (NO3-) |
| Noncarbonate hardness | Water hardness due to the presence of compounds such as calcium and magnesium chlorides sulfates or nitrates; the excess of fatal hardness over total alkalinity. |
| Non-point sources | Diffuse water pollution sources without a specific point of origin. The pollutants are generally carried off the land by storm water. Common non-point sources are agriculture and atmospheric disposal. |
| Non-potable | Water that is unsafe or unpalatable to drink because it contains pollutants, contaminants, minerals or infective agents. |
| Normalization | The calculations that allow performance data to be compared on a uniform basis. For example, flux should be corrected to a temperature of 25§C (77§F) and a constant pressure. |
| NSF | Abbreviation for National Sanitation Foundation Testing Laboratory |
| Nucleus | The center of an atom, that contains protons and neutrons and carries a positive charge. |
| Nuisance contaminant | Constituents in water, which are not normally harmful to health but may cause offensive taste, odor, color, corrosion, foaming, or staining. |
| Nutrient pollution | Contamination of water resources by excessive inputs of nutrients. In surface waters, excess algal production is a major concern. |
| Ohm | A unit of measure determining the resistance to passage of an electrical current. In a solution, it is related to the electrolyte concentration in the solution. |
| Oil interceptor | Used to intercept rainwater or spillages contaminated with oil and to retain the liquid for subsequent separation. |
| Oligotrophic lakes | Deep clear lakes with few nutrients, little organic matter and a high dissolved-oxygen level. |
| Oocysts | Persistent reproductive spores of Cryptosporidium; excreted by infected animals and spread in unfiltered water; highly resistant to chlorine but destroyed by heat or ozone |
| Operating pressure (Operation pressure) | The range of pressure, usually expressed in pounds per square inch, over which a water conditioning device or water system is designed to function. Usually 30-100 psi. |
| Operation and maintenance | 1. Activities conducted at a site after a Super-fund site action is completed to ensure that the action is effective and operating properly. 2. Actions taken after construction to assure that facilities constructed to treat waste water will be properly o |
| Organic | Having the characteristics of or being derived from plant or animal matter, as opposed to inorganic matter derived from rocks and minerals. Organic matter is characterized by its carbon-hydrogen structure. 1. Referring to or derived from living organisms. |
| Organic contaminants | Carbon-based chemicals, such as solvents and pesticides, which can get into water through runoff from cropland or discharge from factories. EPA has set legal limits on 56 organic contaminants. |
| Organic chemicals/compounds | Animal or plant-produced substances containing mainly carbon, hydrogen, and oxygen. |
| Organic matter | Substances of (dead) plant or animal matter, with a carbon-hydrogen structure, such as proteins, sugars, wood and plastics with molecular structures containing carbon-hydrogen (C-H) bonds |
| Organics ( i.e., organic chemicals) | Term used to describe any or all of the compounds with chemical structures based on carbon. Examples are hydrocarbons, wood, sugars, proteins, methane, petroleum-based compounds, solvents, pesticides, herbicides, trihalomethane (THM) and trichloroethylene |
| Organism | Any living thing. |
| Organophosphates | Pesticide chemicals that contain phosphorus; used to control insects. They are short-lived, but some can be toxic when first applied. |
| Osmosis | Water molecules passing through membranes naturally, to the side with the highest concentration of dissolved impurities. The process of diffusion of a solvent such as water through a semi-permeable membrane that will transmit the solvent but impede most d |
| Osmotic pressure | The pressure and potential energy difference that exists between solutions on either side of a semi-permeable membrane. This pressure is caused by the tendency of water to flow in osmosis. Every 100 ppm (mg/L) of TDS produces about one pound per square in |
| Outfall | The place where a wastewater treatment plant discharges treated water into the environment. |
| Overflow rate | One of the guidelines for design of the settling tanks and clarifiers in a treatment plant to determine if tanks and clarifiers are used enough. |
| Overturn | The period of mixing (turnover), by top to bottom circulation, of previously stratified water masses. This phenomenon may occur in spring and/or fall, or after storms. It results in a uniformity of chemical and physical properties of the water at all dept |
| Oxalic acid | Can be used for the removal of iron stains from most washable fabrics. Oxalic acid crystals can be obtained at most drug stores. It is poisonous and a skin irritant, therefore precautions must be used. |
| Oxidant | A substance containing oxygen that reacts chemically in air to produce a new substance. The primary ingredient of photochemical smog. |
| Oxidation | A chemical reaction in which ions are transferring electrons, to increase positive valence; the chemical or biochemical change that occurs when a substance combines with oxygen, for example during combustion and respiration; the release of carbon dioxide |
| Oxidation pond | A man-made body of water in which waste is consumed by bacteria. It is used most frequently with other waste-treatment processes. An oxidation pond is basically the same as a sewage lagoon. |
| Oxidation-reduction potential | The electric potential required to transfer electrons from the oxidant to the reductant, used as a qualitative measure of the state of oxidation in water treatment systems. |
| Oxidizing agent | A chemical substance that brings about the oxidation of other substances in chemical oxidation and reduction reactions. Examples of oxidizing agents include oxygen, ozone, chlorine and peroxide. |
| Oxidizing filter | A type of filter used to change the valence state of dissolved molecules, making them insoluble and therefore filterable. For example, a filter that oxidizes ferrous iron, manganous manganese, and/or anionic sulfur by use of a catalytic media such as mang |
| Oxygen depletion | The reduction of the dissolved oxygen level in a water body. |
| Oxygen system | Injects oxygen into liquid effluent; increases aerobic microbial activity and the rate of removal of BOD, COD and ammoniacal nitrogen |
| Ozonator | A device that adds ozone to water. |
| Ozone | An unstable oxidizing agent, that consists of three oxygen atoms and can be found in the ozone layer in the atmosphere. It is produced by electrical discharge through oxygen or by specifically designed UV-lamps. O3 is a naturally occurring unstable form |
| Ozone depletion | Destruction of the stratospheric ozone layer that shields the earth from ultraviolet radiation harmful to biological life. This destruction of ozone is caused by the breakdown of certain chlorine and/or-bromine containing compounds (chlorofluorocarbons or |
| Ozone generator | A device that generates ozone by passing a voltage through a chamber that contains oxygen. It is often used as a disinfection system. More info on ozone and ozone generators |
| Ozonizer | Equipment that generates ozone from oxygen or air by electrical discharge; used in the treatment and disinfection of water and wastewater |
| Packed tower | A pollution control device that forces dirty air through a tower packed with crushed rock or wood chips while liquid is sprayed over the packing material. The pollutants in the air stream either dissolve or chemically react with the liquid. |
| Packed tower scrubber | Cleans gases with a scrubbing liquor as they pass through inert media; removes soluble and noxious gases and mist droplets larger than 5 æm. |
| Parameter | A variable, measurable property whose value is a determinant of the characteristics of a system such as water. Temperature, pressure, and density are examples of parameters. |
| Partial pressure | That pressure of a gas in a liquid, which is in equilibrium with the solution. In a mixture of gases, the partial pressure of any one gas is the total pressure times the fraction of the gas in the mixture (by volume or number of molecules). |
| Particle size | The sizes of a particle, determined by the smallest dimension, for instance a diameter. It is usually expressed in micron measurements. |
| Particulate | A term used to describe visible sediment particles, used as both singular and plural. |
| Particulate loading | The mass of particulates per unit volume of water. |
| Parts per billion | Expressed as ppb; a unit of concentration equivalent to the æg/l. A basis for reporting the results of water and wastewater analysis, indicating the number of parts by weight of a dissolved or suspended constituent, per billion parts by weight of water or |
| Parts per million | Expressed as ppm; a measure of concentration. One ppm is one unit weight of solute per million unit weights of solution. In water analysis the ppm is equivalent to mg/l. A common basis for reporting the results of water and wastewater analysis, indicating |
| Pasteurization | The elimination of micro organisms by heat applies for a certain period of time. |
| Pathogens | Disease-producing micro organisms. Micro organisms that can cause disease in other organisms or in humans, animals and plants. They may be bacteria, viruses, or parasites and are found in sewage, in runoff from animal farms or rural areas populated with d |
| Polychlorinated biphenyls (PCBs) | Very persistent, toxic substances, stored in fatty tissue; previously widely used as fire-resistant dielectric fluids in transformers and capacitors; now prohibited |
| Pentachlorophenol (PCP) | A powerful biocide, used to preserve cotton and wood; toxic and persistent; release to the environment now heavily restricted |
| Percent saturation | The amount of a substance that is dissolved in a solution compared to the amount that could be dissolved in it. |
| Percolating water | Water that passes through rocks or soil under the force of gravity. |
| Percolation | The movement of water downward and radially through the sub-surface soil layers, usually continuing downward to the ground water. |
| Periodic chart | Arrangement of elements in order of increasing atomic numbers, created by a scientist called Mendelejef. |
| Permeability | The ability of a medium to pass a fluid under pressure. The rate at which liquids pass through soil or other materials in a specified direction. |
| Permeate | This is a term used to refer to the water produced by a membrane process. The permeate is the water that permeates or penetrates through the membrane as product water. |
| Persistence | Refers to the length of time a compound stays in the environment, once introduced. |
| pH (potential of Hydrogen) | The value that determines if a substance is acid, neutral or basic, calculated from the number of hydrogen ions present. It is measured on a scale from 0 to 14, on which 7 means the substance is neutral. pH values below 7 indicate that a substance is acid |
| Pharmaceutical grade water | The definition of six grades of water by the U.S. Pharmacopoeia is as follows: 1.) Purified water 2.) Water for injection 3.) Bacteriostatic water for injection 4.) Sterile water for inhalation 5.) Sterile water for injection 6.) Sterile water for irrigat |
| Phase | A state of matter. This can be solid, liquid or gaseous. |
| Phenolphthalein | An acid-base indicator that produces no color in an acid solution but turns pink or red in an alkaline solution. |
| Photosynthesis | The process of conversion of water and carbon dioxide to carbohydrates. It takes place in the presence of chlorophyll and is activated by sunlight. During the process oxygen is released. Only plants and a limited number of micro organisms can perform phot |
| Physical adsorption (Van der Waals adsorption) | Binding of adsorbate to the surface of a solid by forces whose energy levels approximate those of condensation. |
| Physical and chemical treatment | Processes generally used in wastewater treatment facilities. Physical processes are for instance filtration. Chemical treatment can be coagulation, chlorination, or ozone treatment. |
| Physical Stability | The quality which an ion exchange resin must possess to resist changes that might be caused by attrition, high temperatures, and other physical conditions |
| Physical weathering | Breaking down of rock into bits and pieces by exposure to temperature and changes and the physical action of moving ice and water, growing roots, and human activities such as farming and construction. |
| Phytoplankton | Free-floating, mostly microscopic aquatic plants. |
| Pilot tests | The testing of a cleanup technology under actual site conditions in a laboratory in order to identify potential problems before implementation. |
| Plankton | Tiny plants and animals that live in water. |
| Plate scrubbers | Remove dust, noxious gases and odors from gaseous emissions by passing them through perforated plates flooded with scrubbing liquor |
| POE treatment | Point-Of-Entry treatment. Total water treatment at the inlet to an entire building or facility. A water treatment device that installs at the main inlet to a building and acts as centralized treatment. |
| Pollutant | A contaminant at a concentration high enough to endanger the life of organisms. |
| Pollution | Generally, the presence of matter or energy whose nature, location or quantity produces undesired environmental effects. Under the Clean Water Act, for example, the term is defined as the man-made or man-induced alteration of the physical, biological, and |
| Polyelectrolytes | Natural or synthetic water-soluble macromolecules that assist in the flocculation of dispersed solids. Synthetic chemicals that help solids to clump during sewage treatment. |
| Polymer | Basic molecular ingredients in plastic. |
| Polyphosphate | A sequestering agent used to tie up hardness and iron in solution. As a coating agent, it forms a thin passivating film on metal surfaces to control corrosion. |
| Polyvinyl chloride (PVC) | A tough, environmentally indestructible plastic that releases hydrochloric acid when burned. |
| Point source | A stationary location from which pollutants are discharged. It is a single identifiable source of pollution, such as a pipeline or a factory. |
| Polar substance | A substance that carries a positive or negative charge, for instance water. |
| POPs | Persistent Organic Pollutants, complex compounds that are very persistent and difficultly biologically degradable. |
| Pore | An opening in a membrane or medium that allows water to pass through. |
| Pores | The complex network of channels in the interior of a particle of a sorbent. |
| Portable exchange | Water softeners, deionizers, and filters that are designed for removal from its point of application for transport to a central station or plant for regeneration or servicing. |
| Positive charge | The electrical potential acquired by an atom that has lost one or more electrons; a characteristic of a cation. |
| Potable water | Water that is safe for drinking and cooking; water of a quality suitable for drinking Water which is considered safe and fit for human consumption, culinary and domestic purposes and meets the requirements of the health authority having jurisdiction. |
| Potentiation | The ability of one chemical to increase the effect of another chemical. |
| Potentiometric surface | The surface to which water in an aquifer can rise by hydrostatic pressure. |
| POU treatment | A water treatment system designed to connect at the actual point-of-use for water; countertop or undersink treatment systems. Point-Of-Use treatment. Water treatment at a limited number of outlets in a building, for less than the whole building. |
| Powdered activated carbon | Activated carbon in particle sizes predominantly smaller than 80 mesh. |
| PPB | The abbreviation for "parts per billion." Parts per per billion, a way of expressing tiny concentrations of pollutants in air, water, soil, human tissue, food, or other products. This measurement is a means of specifying the concentration of any constitue |
| PPM | The abbreviation for "parts per million". Parts per million, a way of expressing tiny concentrations of pollutants in air, water, soil, human tissue, food, or other products. This measurement is a means of specifying the concentration of any constituent |
| Precipitate | To cause a dissolved substance to form a solid particle that can be removed by settling or filtering. The term also refers to the solid thus formed. |
| Precipitation process | The altering of dissolved compounds to insoluble or badly soluble compounds, in order to be able to remove the compounds by means of filtration. Removal of solids from liquid waste so that the hazardous solid portion can be disposed of safely; removal of |
| Pre-chlorination | The application of chlorine to water prior to other water treatment processes. |
| Precipitators | Air pollution control devices that collect particles from an emission. |
| Preferential adsorption | Adsorption in which a certain component or certain components are adsorbed to a much greater extent than others. |
| Pressure drop | A decrease in water pressure during its flow due to internal friction between molecules of water, and external friction due to irregularities or roughness in surfaces past that the water flows. |
| Pressure loss | The friction of water against the inside diameter or pipes and components reduces water pressure. |
| Pressure sewers | A system of pipes in which water, wastewater, or other liquid is pumped to a higher elevation. |
| Pressure vessel | Membrane elements must be installed in a pressure vessel to provide the means to supply feed water, remove the reject or concentrate stream, delivery product water, and contain the pressure at which membrane systems much operate. |
| Pre-treatment | Processes used to reduce or eliminate wastewater pollutants from before they are discharged into publicly owned treatment works. Membrane type water treatment systems require good pretreatment to ensure optimum system performance and acceptable membrane l |
| Primary wastewater treatment | The removal of suspended, floating and precipitated solids from untreated wastewater. First steps in wastewater treatment; screens and sedimentation tanks are used to remove most materials that float or will settle. Primary treatment results in the remova |
| Process water | Water that serves in any level of the manufacturing process of certain products. |
| Product water | Water that has passed through a water treatment plant and is ready to be delivered to consumers. This is the term used to describe the treated or purified water produced by a water treatment system, including reverse osmosis systems and others. Also know |
| Protons | Positively charged building blocks of an atom that are centered in the nucleus. |
| Protozoa | Large micro organisms that consume bacteria. Any of a large group of mostly microscopic, one celled animals living chiefly in water. Many protozoa's are parasitic and are higher on the food chain than the bacteria they eat. |
| Public water system | A system that provides piped water for human consumption to at least 15 service connections or regularly serves 25 individuals. |
| Pumicite | A natural, glassy aluminum silicate mineral from volcanic ash that is used as a water treatment filtration media. Call Toll Free 877-262-5191, International 316-262-5191 for a product solution. |
| Purification | The removal of undesirable matter from water or wastewater. It is the disinfection of water by the killing of microbial contaminants, such as coli form bacteria. A strict definition means the removal from water of all contaminants. |
| Putrefaction | Biological decomposition of organic matter; associated with anaerobic conditions. Biological decomposition of organic matter by microbes with the production of ill smelling products. Usually takes place when there is a deficiency of oxygen. |
| Pyrogen | Substance that is produces by bacteria and it fairly stable. It causes fever in mammals. Substances that produce fever when introduced into humans. Being chemically stable, pyrogens are not necessarily destroyed by conditions that kill bacteria. Pyrogenic |
| Pyrolox | A super oxidation media serving as a catalyst in the removal of iron, hydrogen sulfide and manganese. It works best at or above a pH of 6.5 and requires no regeneration. Adequate backwashing is necessary to provide at least 20 per cent bed expansion of th |
| Qualitative water assessment | Analyses of water used to describe the visible or aesthetic characteristics of water. |
| Quantitative water assessment | Use of analyses of water properties and concentrations of compounds and contaminants in order to define water quality. |
| Quartz sleeve | Also called a quartz jacket, it is a clear, pure quartz sleeve that is installed around the high intensity ultraviolet lamp in an ultraviolet system. It retards less than 10 percent of the radiation dosage in contrast to the poorer results offered by glas |
| Quicksilver water | A solution of mercury nitrate used in gilding. |
| Radioactive | Having the property of releasing radiation. |
| Radionuclides | Any man-made or natural element that emits radiation and that may cause cancer after many years of exposure through drinking water. |
| Radium | Naturally occurring radioactive elements such as radium 226 and radium 228 created in the decay of the uranium and thorium series. It can be removed from water by cation exchange softening. |
| Radon | A short-lived radioactive gas produced from decaying uranium that is soluble in water. Can be effectively removed by activated carbon filtration or serration. Radon is considered carcinogenic when inhaled by humans. |
| Raw sewage | Untreated wastewater and its contents. |
| Raw water | Intake water before any treatment or use. Untreated water from wells or from surface sources or any water before it reaches a water treatment device or process. |
| Reactivation (Revivification) | Oxidation processes for restoring the adsorptive properties of a spent sorbent such as activated carbon. |
| Reaeration | Renewing air supplies in the lower layers of a reservoir in order to raise oxygen levels. |
| Recarbonization | Process in which carbon dioxide is bubbled into treatment water in order to lower the pH. |
| Receiving waters | A river, lake, ocean, stream or other watercourse into which wastewater or treated effluent is discharged. |
| Recharge | The process by which water is added to a zone of saturation, usually by percolation from the soil surface, e.g., the recharge of an aquifer. |
| Recharge Area | An area where rainwater soaks through the ground to reach an aquifer. |
| Recirculation | Recycling water after it is used. Often it has to pass a wastewater purification system before it can be reused. |
| Recovery | That percentage of the feed flow rate that passes through the membrane and becomes the permeate stream. |
| Redox | Shortened term for reduction/ oxidation reactions. Redox reactions are a series of reactions of substances in which electron transfer takes place. The substance that gains electrons is called oxidizing agent. A reaction where electrons are gained or lost |
| Reduction | A chemical reaction in which ions gain electrons to reduce their positive valence. |
| Reed Bed | Managed wetlands used for the treatment of wastewaters; commonly planted with phragmites australis and other species to facilitate BOD removal below soil surface |
| Red List | A list used in the UK that identifies the most persistent and toxic substances so that their discharge to water and accumulation in living organisms may be strictly controlled |
| Regenerant | The solution used to restore the activity of an ion exchanger. Acids are employed to restore a cation exchanger to its sodium form. The anion exchanger may be rejuvenated by treatment with an alkaline solution. Potassium permanganate is used to regenerate |
| Regeneration | Putting the desired counter-ion back on the ion exchanger, by displacing an ion of higher affinity with one of lower affinity. The process of returning the sodium ions to the mineral after it has exchanged all its sodium ions for calcium and magnesium fro |
| Reject | The reject stream is the water that does not pass through the membrane. Since minerals are left behind from the departed permeate or product water, the reject stream is more concentrated than the source or feed water. Hence it is also called the concentra |
| Rejection | In cross flow membrane filtration and deionization, it is the ability of the membrane to reject the passage of dissolved solids and other contaminants into the product water. |
| Rejection rate | This figure, typically 80% to 99.5%, indicates the percentage of dissolved solids that will be rejected, or prevented from passing through with the product water, using the reverse osmosis drinking water systems. When pressure is applied to water in conta |
| Reserve capacity | Extra treatment capacity built into wastewater treatment plants and sewers to be able to catch up with future flow increases due to population growth. |
| Reservoir | A natural or artificial holding area used to store water. |
| Residual | The amount of a specific material remaining in the water following a water treatment process. It may refer to material remaining as the result of incomplete removal such as hardness leakage, or to a substance meant to remain in the treated water such as r |
| Residue | The dry solids remaining after the evaporation of a sample of water or sludge. |
| Resin | Synthetic organic ion exchange material, such as the high capacity cation exchange resin widely used in water softeners. Technical name- sulfonated co-polymer of styrene and divinyl benzene. |
| Resistance | For plants and animals, the ability to withstand poor environmental conditions and/or attacks by chemicals or disease. The ability may be inborn or developed. |
| Resolution | The breaking of an emulsion into its individual components. |
| Retentate | See concentrate. |
| Retentivity | The ability of an adsorbent to resist desorption of an adsorbate. |
| Reverse deionization | The use of an anion exchange unit ahead of a cation exchange unit- in that order- in a deionization system. |
| Reverse Osmosis process | The Reversed Osmosis (RO) process uses a semi-permeable membrane to separate and remove dissolved solids, organics, pyrogens, submicron colloidal matter, viruses, and bacteria from water. The process is called 'reverse' osmosis since it requires pressure |
| R.O. or RO | The abbreviation for 'reverse osmosis' |
| Rotary scrubber | A device that separates particulate contamination from a gas stream by impaction onto a wet rotor or into a fine spray of scrubbing liquor |
| Rotating biological contactor | An aerobic treatment system that rotates plastic media with fixed microbial film alternately through liquid effluent and air to reduce the BOD value |
| Run-off | The part of precipitation water that runs off the land into streams or other surface water. |
| Rust (ferric oxide) | A reddish product of corrosion sometimes found in water. Rust is formed as a result of electrochemical interaction between iron and oxygen in the presence of moisture. |
| Sacrificial anode | An anode constructed of magnesium or other suitable material and placed in a water heater tank to accept the electrolytic activity and to protect the tank from corrosion. |
| Safe water | Water that does not contain harmful bacteria, toxic materials, or chemicals, and is considered safe for drinking. |
| Safe yield | The annual amount of water that can be taken from a source of supply over a period of years without depleting that source beyond its ability to be naturally refilled. |
| Saline water | Water containing an excessive amount of dissolved salts, usually over 10,000 mg/1. |
| Salinity | The presence of soluble minerals in water. |
| Salt | The common name for the specific chemical compound sodium chloride (NaCl), used in the regeneration of ion exchange water softeners. In chemistry, the term is applied to a class of chemical compounds that can be formed by the neutralization of an acid wit |
| Salt water intrusion | The invasion of fresh surface or ground water by salt water. If the salt water comes from the ocean it may be called seawater intrusion. |
| Sand filter | Separates suspended solids and associated BOD/COD from liquids by passing the liquid through a bed of sand A treatment device or structure for removing solid or colloidal material of a type that cannot be removed by sedimentation. Such filters can be grav |
| Sand filters | Devices that remove some suspended solids from sewage. Air and bacteria decompose additional wastes filtering through the sand so that cleaner water drains from the bed. |
| Sand filtration | Sand filtration is a frequently used and very robust method to remove suspended solids from water. The filtration medium consists of a multiple layer of sand with a variety in size and specific gravity. Sand filters can be supplied in different sizes and |
| Saturated solution | A solution containing the maximum amount of the dissolved substance that such a solution can hold at this temperature. |
| Saturated zone | The area below the water table where all open spaces are filled with water. |
| Saturation | The condition of a liquid when it has taken into solution the maximum possible quantity of a given substance. |
| Scale | The precipitate that forms on surfaces in contact with water as the result of a physical or chemical change. |
| Scavenger | A polymer matrix or ion exchanger used to remove organics from feedwater prior to a deionization process. |
| Screen(s) | Equipment that separates solid material from liquid by allowing the liquid to pass through constrictions (the screen) of chosen size |
| Screening | Use of screens to remove coarse floating and suspended solids from sewage. |
| Seawater | Concentrations of dissolved solids in oceans and seas vary around the world. Typically, a level of 35,000-ppm total dissolved solids is considered average. |
| Secondary treatment | The second step in treating wastewater to remove suspended and dissolved solids and biochemical oxygen (BOD) after the initial primary treatment. The removal or reduction of contaminants and BOD of effluent from primary wastewater treatment. |
| Sedimentation | Settling of solid particles in a liquid system due to gravity. |
| Sediments | Soil, sand, and minerals washed from land into water, usually after rain. Soil, sand, and minerals washed from land into water usually after rain. They pile up in reservoirs, rivers and harbors, destroying fish-nesting areas and holes of water animals, an |
| Selective ion exchange | The use of a selective ion exchange medium with the property of removing specific ions from a solution. |
| Semi-confined aquifer | An aquifer partially confined by soil layers of low permeability through which recharge and discharge can still occur. |
| Semipermeable | A medium that allows water to pass through, but rejects dissolved solids, so that it can be used to separate solids from water. |
| Separate sewer | A sewer system that carries only sanitary sewage; no storm-water runoff. When a sewer is constructed this way, wastewater treatment plants can be sized to treat sanitary wastes only and all of the water entering the plant receives complete treatment at al |
| Separation | The isolation of the various compounds in a mixture. |
| Septic tank | An underground storage tank for wastes from homes not connected to a sewer line. Waste goes directly from the home to the tank. A container that receives untreated sewage, holds back floating scum and retains and digests heavy solids but allows clarified |
| Sequester | A chemical reaction in which certain ions are bound into a stable, water soluble compound, thus preventing undesirable action by the ions. For example, polyphosphates can sequester hardness and prevent reactions with soap. |
| Sequestering agent | A chemical compound sometimes fed into water to tie up undesirable ions, keep them in solution, and eliminate or reduce the normal effects of the ions. For example, polyphosphates can sequester hardness and prevent reaction with soap. |
| Service run | That portion of the operating cycle of a water conditioning unit during which treated water is being delivered, as opposed to the period when the unit is being backwashed, recharged or regenerated. |
| Settleable solids | Those suspended solids in wastewater that will settle over a certain period of time and are removed in that way. |
| Settling | The process of sinking of a substance sinking in water. This occurs when the substance does not dissolve in water and its density is larger than that of water. |
| Settlement tank | container that allows sufficient retention time for the separation of organic and inorganic solids from liquid and produces sludge and clarified liquor both of which may receive further treatment |
| Sewage | Waste fluid in a sewer system; liquid effluent from domestic and industrial activity |
| Sewage contamination | The introduction of untreated sewage into a water body. |
| Sewage sludge | Sludge produced in a public sewer. |
| Sewerage | The entire system of sewage collection, treatment, and disposal. |
| Siliceous gel zeolite | A synthetic, inorganic exchanger produced by the aqueous reaction of alkali with aluminum salts. |
| Silt | Fine particles of sand or rock that can be picked up by the air or water and deposited as sediment. |
| Slow sand filtration | Treatment process involving passage of raw water through a bed of sand at low velocity that results in the substantial removal of chemical and biological contaminants, |
| Sludge | A semi-solid residue, containing micro organisms and their products, from any water treatment process; the wet solids that can be settled from an untreated liquid effluent (primary sludge); or from aerobically treated effluent (secondary sludge) |
| Slurry | Mixture of urine, feces and wash water from cattle or pig rearing |
| Soda ash | The common name for sodium carbonate, a chemical compound used as an alkaline builder in some soap and detergent formulations, to neutralize acid water, and in the lime- soda ash water treatment process. |
| Sodium | An ion found in natural water supplies, and introduced to water in the ion exchange water softening process. Sodium compounds are highly soluble, and do not react with soaps or detergents. |
| Sodium chloride | The chemical name for common salt, widely used in the regeneration of ion exchange water softeners. |
| Sodium hydrosulfite | A strong reducing agent used as the main ingredient of several resin cleaners used to clean iron fouled in ion exchange resin beds. |
| Soft detergents | Cleaning agents that break down in nature. |
| Softened water | Any water that is treated to reduce hardness minerals to <1.0 GPG (<17.1 mg/L), expressed as calcium carbonate. |
| Softening | The reduction of calcium and magnesium from water to lower total hardness. |
| Soft water | Any water containing less than one grain (<1.0 GPG/ <17.1 mg/L) of total hardness ions. |
| Soil washing | Water-based volume reduction process in which contaminated soil or dredgings are separated into a small contaminated fraction, for further treatment or disposal, and a larger cleaned fraction |
| Sole Source aquifer | An aquifer that supplies 50 percent or more of the drinking water of an area. |
| Solidification | Removal of wastewater from a waste or changing it chemically to make it less permeable and susceptible to transport by water. |
| Solubility | The amount of mass of a compound that will dissolve in a unit volume of water. |
| Solute | Matter dissolved in a liquid, such as water. |
| Solvent | Substance (usually liquid) capable of dissolving one or more other substances. The liquid, such as water, in which other materials (solutes) are dissolved. |
| Soot | Carbon dust formed by incomplete combustion. |
| Sorption | The action of soaking up or attracting substances. A process used in many pollution control systems. |
| Source Water | Water in its natural state, prior to any treatment for drinking. |
| Sparger | A device that introduces compressed air into a liquid. |
| Sparging | Injection of air below the water table to strip dissolved volatile organic compounds and to facilitate aerobic biodegradation of organic compounds. |
| Special waste | Waste that contains substances considered to be dangerous to life as listed in the Control of Pollution (Special Waste) Regulations 1980; applies within the UK |
| Specific conductance | Method to estimate the dissolved solid content of a water supply by testing its conductivity. |
| Specific flux | Flux rate divided by net driving pressure. |
| Specific gravity | The ratio of the weight of a specific volume of a substance compared to the weight of the same volume of pure water at 40C. |
| Spring | Ground water seeping out of the earth where the water table exceeds the ground surface. |
| Static tubular aerator | A system in which air is blown into vertical tubes submerged in a liquid, promoting mixing and oxygen transfer |
| Sterilization | 1. In pest control, the use of radiation and chemicals to damage body cells needed for reproduction. 2. The destruction of all living organisms in water or on the surface of various materials. In contrast, disinfection is the destruction of most living o |
| Stoke's Law | A method to calculate the rate of fall of particles through a fluid, based on density, viscosity and particle size. |
| Sublimation | The transitions of water directly from the solid state to the gaseous state, without passing through the liquid state. |
| Submerged aerated filter | A device in which highly aerated effluent flows through inert media that is completely submerged; fixed microbial film reduces the BOD and ammoniacal content of the effluent |
| Submerged biological contactor | An aerobic treatment system in which plastic media that is largely submerged in effluent is rotated by rising air, the fixed microbial film on the media reducing the BOD value |
| Submicron particles | Particles of less than 1æm in size, present in smoke and fumes |
| Sub-micronic filtration | Sub-micronic filtration technology is usually applied using more conventional filtration media, but with very small pore sizes. Membranes are usually not used for this technology. Rather, cartridge filters are employed. |
| Sulfate-reducing bacteria | A group of bacteria that are capable of reducing sulfates in water to hydrogen sulfide gas, thus producing obnoxious tastes and odors. These bacteria have no sanitary significance, and are classed as nuisance organisms. |
| Sulfur | A yellowish solid chemical element. The term is also used as a slang expression to refer to water containing hydrogen sulfide gas (H2 S). |
| Sulphur dioxide (SO2) | Toxic gas produced during the combustion of sulphur compounds in fossil fuels; component of acid rain |
| Surface aerator | Equipment in which blades or vanes rotate about a vertical or horizontal shaft and entrain air to mix and aerate wastewater |
| Surface tension | The elastic-like force in a body, especially a liquid, tending to minimize, or constrict, the area of the surface. |
| Surface water | All water naturally open to the atmosphere, concerning rivers, lakes, reservoirs, ponds, streams, impoundments, seas, estuaries and wetlands. |
| Surfactant | A surface-active agent used in detergents to cause lathering. |
| Suspended solids | Solid organic or inorganic particles that are held in suspension in a solution. Solids of organic and inorganic origin present in liquid effluents; concentration in (mg/l) measured by filtration followed by drying at 105 C . Small particles of solid pollu |
| Swelling | The expansion of an ion exchange bed that occurs when the reactive groups on the resin are converted from one form to another. This property is reversible and indeed, some resins shrink in the exhausted state. |
| Synergism | The combined action of several chemicals, which produces a total effect greater than the effects of the chemicals separately. |
| Parallel flow filtration (PFF) | Filtration in which liquid flows parallel to (along) the surface of the membrane. Synonymous with the term 'cross flow'. The sweeping action of fluid helps to minimize gel layer formation and surface fouling. Contrast with 'dead-end' filtration. |
| Tannin | A naturally occurring substance in wood, grape skins, seeds and stems. Is primarily responsible for the basic "bitter" component in wines. Acts as a natural preservative, helping the development and, in the right proportion, balance of the wine. Considere |
| TCE (Trichloroethylene) | A toxic volatile organic chemical typically used as an industrial solvent. |
| TDS | The abbreviation for "total dissolved solids." Total Dissolved Solids. The weight per unit volume of water of suspended solids in a filter media after filtration or evaporation. This is a measure, usually given in PPM (Parts Per Million) or in milligrams |
| Tertiary treatment | Advanced cleaning of wastewater that goes beyond the secondary or biological stage, removing nutrients such as phosphorus, nitrogen and most BOD and suspended solids. The third stage in the treatment of sewage that in a high degree of conditioning followi |
| TH | Total Hardness. The sum of calcium and magnesium hardness, expressed as a calcium carbonate equivalent. |
| Thermal oxidation | High temperature incineration of pollutants such as VOCs and odors in gas. streams |
| Thermal pollution | Discharge of heated water from industrial processes in receiving surface water, causing death or injury of aquatic organisms. |
| Thin-film composite membrane (TFC) | Reverse osmosis membrane produced with polyamide-based polymer. It is resistant to bacteria and can withstand a wide pH range. However, it cannot tolerate chlorine. |
| THM | Trihalomethanes. Toxic chemical substances that consist of a methane molecule and one of the halogen elements fluorine, bromine, chlorine and iodine attached to three positions of the molecule. They usually have carcinogenic properties. |
| Throughput volume | The amount of solution passed through an exchange bed before exhaustion of the resin is reached. |
| Titration | An analytical technique to determine how much of a substance is present in a water sample by adding another substance and measuring how much of that substance must be added to produce a reaction. |
| Total acidity | The total of all forms of acidity, including mineral acidity, carbon dioxide, and acid salts. Total acidity is usually determined by titration with a standard base solution to the phenolphthalein endpoint (pH 8.3). |
| Total alkalinity | The alkalinity of a water as determined by titration with standard acid solution to the methyl orange endpoint (pH approximately 4.5); sometimes abbreviated as "M alkalinity". Total alkalinity includes many alkalinity components, such as hydroxides, carbo |
| Total chlorine | The total amount of chlorine is a solution, which includes the combined chlorine as well as the free available chlorine. |
| Total dissolved solids (TDS) | The weight of solids per unit volume of water that are in true solution, usually determined by the evaporation of a measured volume of filtered water, and determination of the residue weight. TDS is expressed as ppm per unit volume of water. An electrical |
| Total hardness | The sum of all hardness components in water, expressed as their equivalent concentration of calcium carbonate. Primarily due to calcium and magnesium in solution, but may include small amounts of metals such as iron which can act like calcium and magnesiu |
| Total organic carbon (TOC) | The measurement of carbon dioxide produced from organics when a water sample is atomized into a combustion chamber. The amount of carbon covalently bound in organic compounds in a water sample. |
| Total solids (TS) | All the solids in wastewater or sewage water, including suspended solids and filterable solids. The weight of all solids, dissolved and suspended, organic and inorganic, per unit volume of water; usually determined by the evaporation of a measured volume |
| Total suspended solids (TSS) | A measure of the suspended solids in wastewater, effluent, or water bodies, determined by using tests for "total suspended non-filterable solids." (See: suspended solids.) |
| Treatment | A required process intended to reduce the level of a contaminant in drinking water. (Click for information about filters, softeners or reverse osmosis. |
| Trickling filter | A wastewater treatment unit that contains medium material with bacteria. The stream of wastewater is trickled over the medium and the bacteria break down the organic wastes. Bacteria are collected on the filter medium. A bed of gravel or pebble media thro |
| Trihalomethanes (THMs) | A group of organic chemicals to known to be carcinogenic in more than trace amounts that are produced from chlorination. They reduce the germicidal activity of chlorine in alkaline water. |
| Toxic water pollutants | Compounds that are not naturally found in water at the given concentrations and that cause death, disease, or birth defects in organisms that ingest or absorb them. |
| Transmembrane pressure (TMP) | The force that drives liquid flow through a cross flow membrane. In cross flow devices, the TMP is calculated as an average related to the pressures of the inlet, outlet and permeate ports. The TMP can be expressed as: Where: Pf = Feed pressure Pc = C |
| Transmission lines | Pipelines that transport raw water from its source to a water treatment plant. |
| Transmissivity | The ability of an aquifer to transmit water. |
| Transpiration | The process by which water vapor is released into the atmosphere after transpiring of living plants. |
| Treatment plant | A structure built to treat wastewater before discharging it into the environment. |
| Tube settler | Device using bundles of tubes to let solids in water settle to the bottom for removal by sludge. |
| Turbidity | A measure of non-transparency of water due to the presence of suspended matter. A measure of the cloudiness of a liquid that is caused by the presence of fine suspended solids; A measure of the amount of finely divided suspended matter in water, which ca |
| Turbulent flow | A flow that contains may rapid fluctuations. |
| Ultrafiltration | The separation from a liquid of particles of 0ú005-0ú1 æm in size by pumping the liquid through a synthetic membrane at high pressure; a membrane type system that removes small colloids and large molecules from solutions. Ultrafiltration removes particles |
| Ultrapure water | Water from which most other materials have been removed, producing a resistivity of at least 18 M-cm, and making it sufficiently pure for the most exacting microelectronic, pharmaceutical and medical uses; No standards exist describing ultrapure water tho |
| Ultraviolet (UV) | Pertaining to ultraviolet light. |
| Ultraviolet (UV) light | Radiation (light) having a wavelength shorter than 3900 angstroms the wavelengths of visible light, and longer than 100 angstroms, the wavelengths of x-ray's. This wavelength puts ultraviolet light at the invisible violet end of the light spectrum. Ultrav |
| Ultraviolet absorber | Substances that absorb ultraviolet radiation (light). ultraviolet absorbers are added to plastic (such as used in plastic tanks and fittings) and rubber products to make them less likely to decay as the result of absorbing ultraviolet rays. |
| Ultraviolet chamber | The area where the water is irradiated with ultraviolet rays. |
| Ultraviolet demand | The amount of ultraviolet rays required to inactivate certain microorganisms. |
| Ultraviolet dosage | The amount of disinfectant ultraviolet rays delivered to the organisms in the water being disinfected. Dosage is a combination of UV intensity times the contact time and is measured in watt-seconds per square centimeter. |
| Ultraviolet light system | A disinfection system in which light of 254 nm, produced by mercury lamps, damages microorganisms by disrupting their genetic material . Radiation having a wave length shorter than 4000 angstroms (visible light) down to 100 angstroms on the border of the |
| Ultraviolet oxidation | A process using extremely short wave-length light that can kill micro-organisms (disinfection) or cleave organic molecules (photo oxidation) rendering them polarized or ionized and thus more easily removed from the water. |
| UV ozone | A powerful wastewater treatment process employing ozone in solution and ultraviolet light; oxidizes COD and toxic substances, removes color and disinfects |
| Ultraviolet rays | Radiation from the sun that can be useful or potentially harmful. UV rays from one part of the spectrum enhance plant life and are useful in some medical and dental procedures; UV rays from other parts of the spectrum to which humans are exposed (e.g., wh |
| Uniformity coefficient | The measure of the variation in particle sizes of filter and ion exchange media. The uniformity coefficient is defined as the ratio of the sieve size that will permit passage of 60 percent of the media material by weight to the sieve size that will permit |
| Univalent | Having a valence of one. Also called monovalent. |
| Unloading | The release of the contaminant that was captured by a filter medium. |
| Unsaturated zone | The area above the water table where soil pores are not fully saturated with water. |
| Upflow (Up-Flow) | An upward flow of water. The operation of an ion exchange unit in which solutions are passed in at the bottom and out at the top of the container. - A pattern of water flow in which a solution (water or regenerant usually) enters at the bottom of the vess |
| Upflow softening | A pattern of water flow used in softeners in which the service water flows upward through the ion exchange bed; the media is restricted in movement, usually because of a packed bed. The regeneration brine usually flows downward in such systems. Upflow sof |
| Upper distributor | The piping arrangement inside and at the top of softeners and filters to more uniformly distribute the incoming water over the resin or filter media bed. In small domestic units, this distributor also distributes the brine for regeneration. |
| UP (Ultra pure) water | Ultra pure water creation demands a specialized way of working. A number of techniques are used amongst others; membrane filtration, ion exchanges, sub micron filters, ultraviolet and ozone systems. The produced water is extremely pure and contains none t |
| Uranium | A radioactive metallic element found naturally in combination with other materials. Uranium 238 is the most common form. A radioactive metallic element found naturally only in combination with other substances. Uranium 238 (U-238) is the most common form, |
| Urban runoff | Water from city streets and domestic properties that carries pollutants into the sewer systems and receiving waters. |
| UV | Ultraviolet. Radiation that has a wavelength shorter than visible light. It is often used to kill bacteria and destroy ozone. |
| Vacuum breaker | A mechanical device that automatically vents a water line to the atmosphere when subject to a partial vacuum, thus preventing back siphonage. |
| Validation | 1. (water treatment industry) Determination upon testing that a representative sample of a water treatment equipment model has met the requirements of a specified standard. 2. (pharmaceutical industry) The requirement of certain quality control testing an |
| Vapor (Vapour) | The gaseous phase of substances such as water. |
| Vapor (Vapour) extraction | A technique that makes use of a partial vacuum to remove volatile and semi-volatile contamination, such as hydrocarbons, from soils |
| Vaporize | Conversion of a liquid into vapor (vapour). |
| Venturi | A channel that serves the measurement of water flows. A tube with a tapered throat which causes an increase in velocity thus a decrease in pressure of the fluid passing through it. It is the common item used to educt or suck a regenerant into a water cond |
| Venturi aerator | A submerged jet aeration device in which the liquid to be aerated is pumped through a nozzle within a larger diameter tube, causing air entrainment and vigorous liquid mixing |
| Venturi scrubber | A device that removes submicron particles and reactive trace gases from gas streams by passing the gas at high velocity through the scrubbing liquor ensuring vigorous mixing |
| Virus | The smallest form of life known to be capable of producing disease or infection, usually considered to be of large molecular size. They multiply by assembly of component fragments in living cells, rather than be cell division, as do most bacteria. Being p |
| Viruses | The smallest life forms known, which are not cellular in nature. They live inside the cells of animals, plants and bacteria and often cause disease. They are made up of a chromosome surrounded by a protein shell. |
| Viscosity | The syrupiness of water and it determines the mobility of the water. When the temperature rises, the viscosity degrades; this means that water will be more mobile at higher temperatures. The tendency of a fluid to resist flowing due to internal forces suc |
| Void area | The space between the resin beads in an ion exchange bed or the space between the particles of filter media bed. Also can be defined as the space between the chunks of salt in a brine tank. |
| Void volume | The volume occupied by the interstitial spaces between the particles of ion exchangers, filter media, or other granular materials in a bed or column. Often expressed as percent of the total volume occupied by the medium bed. |
| Volatile | Capable of becoming vapor at relatively low temperatures. |
| Volatile organic chemicals (VOCs) | Organic chemicals that turn into vapor at relatively low temperatures. |
| Volatile organic compound (VOC) | Any organic compound which participates in atmospheric photochemical reactions except for those designated by the EPA Administrator as having negligible photochemical reactivity. Synthetic organic compounds which easily vaporize and are often carcinogenic |
| Waste incineration | Incineration of waste at high temperatures in two stages to promote efficient combustion to an ash and carbon dioxide |
| Waste minimization | The analysis and revision of the use of materials, processes, equipment and procedures in order to reduce the unnecessary use of energy and resources, to reduce the generation of effluents and wastes and to recycle where practical |
| Waste treatment plant | A facility containing a series of tanks, screens, filters and other processes by which pollutants are removed from water. |
| Waste treatment stream | The continuous movement of waste from generator to treater and disposer. |
| Wastewater | The spent or used water from a home, community, farm, or industry that contains dissolved or suspended matter. Water that has been used. 1. (RO, ultrafiltration, electrodialysis) The stream of water (not product water) created as the result of processing |
| Wastewater infrastructure | The plan or network for the collection, treatment, and disposal of sewage in a community. |
| Water (H2O) | An odorless, colorless, tasteless liquid that exists as ice in solid form (phase) and steam in vapor form (phase). It freezes at 32øF (0øC) and boils at 212øF (100øC). Water is a polar squid with high dielectric constant that accounts for its solvent powe |
| Water conditioning | Virtually any form of water treatment designed to improve the quality of water, by neutralization, inhibition or removal of undesirable substances. |
| Water hammer | The shock wave produced by the abrupt change of water flow through a piping system. Water hammer produces an instantaneous multiple increase in the pressure normal to the system. The installation of a water hammer arrestor will absorb these shock waves. |
| Water monitoring | The process of constant control of a body of water by means of sampling and analyses. |
| Water pollution | The presence in water of enough harmful or objectionable material to damage water quality. |
| Water retention | The amount of water, expressed as a percent of the wet weight of an ion exchanger, retained within the resin bead and on the surface of fully swollen and drained ion exchange media. Also called water regain. |
| Water quality | The condition of water with respect to the amount of impurities in it. |
| Water recycling | Using water again for the same or another process step, after a small form of purification is applied. |
| Watershed | A land area from which water drains to a particular water body. |
| Water softening | The reduction/removal of calcium and magnesium ions, which are the principal cause of hardness in water. The cation exchange resin method is most commonly used for residential and commercial water treatment. In municipal and industrial water treatment, th |
| Water softener (chemical) | A compound which, when introduced into water used for cleaning or washing, will counteract the effects of the hard water minerals (calcium and magnesium) and produce the effect of softened water. For example, detergent additives and polyphosphates. |
| Water softener (mechanical) | A pressurized water treatment device in which hard water is passed through a bed of cation exchange media (either inorganic or synthetic organic) for the purpose of exchanging calcium and magnesium ions for sodium or potassium ions, thus producing a softe |
| Water softener salt | Salt suitable for regenerating residential and commercial cation exchange water softeners. Most commonly used for this purpose is sodium chloride (NaCl) in crystal or pelletized form. Rock grade salt should be 96-99 percent NaCl; evaporated salt should be |
| Water solubility | The maximum possible concentration of a chemical compound dissolved in water. |
| Water storage pond | An impound for liquid wastes designed to accomplish some degree of biochemical treatment. |
| Water supply system | The collection, treatment, storage, and distribution of water from source to consumer. |
| Water system | A river and all its branches. |
| Water treatment device | Any point-of-use or point-of-entry instrument or contrivance sold or offered for rental or lease for residential use, and designed to be added to the plumbing system, or used without being connected to the plumbing of a water supply intended for human con |
| Water table | The surface of groundwater in the soil. |
| WBA | Weak base anion exchanger. |
| Weak acid cation exchangers | Those cation exchange products with functional groups that, in the hydrogen form, are not capable of splitting neutral salts to form their corresponding free acids. Weak acid cation exchange resins have a much higher (three to four times higher) regenerat |
| Weir | A spill over device used to measure or control water flows. 1. A dam-like wall or plate placed in an open channel and used to measure the flow of water. The depth of the flow over the weir can be used to calculate the flow rate, or a chart or conversion t |
| Well | A deep hole with the purpose to reach underground water supplies. |
| Wellhead protection area | The area surrounding a drinking water well or well field which is protected to prevent contamination of the well(s). |
| Wet air oxidation | A process that treats wastewater containing high strength or hazardous organic chemicals by a combination of high temperature and pressure that creates highly reactive hydroxyl radicals |
| Wetland | An area that is saturated by surface water or groundwater, with vegetation adapted for life under those soil conditions. |
| Wettability | The relative degree to which a fluid will spread into solid surface in the presence of other immiscible fluids. |
| WFI | Water for Injection. |
| WHO | World Health Organization. |
| WQA | Water Quality Association. Many participants in the POU and POE water conditioning industry are members of this association. |
| Xenobiotic | Any biological substance, displaced from its normal habitat; a chemical foreign to a biological system. |
| Xylene | A volatile organic chemical (VOC) commonly used in industry as a solvent. |
| Yield | The rate of production of cake from a dewatering device. l. The amount of product water produced by a water treatment process. 2. The quantity of water (expressed as a rate of flow--gpm, gph, gpd, or total quantity per year) that can be collected for a given use from surface or groundwater sources. The yield may vary with the use proposed, with the plan of development and also with economic considerations. |
| Zeolite(s) | Naturally occurring or synthetic hydrated sodium alumina silicate with ion exchange properties. Zeolites have been largely replaced with synthetic organic cation ion exchange resins. Modified Zeolites can be selectively charged with exchange minerals such |
| Zeolite Softening | A term formerly used for the removal of calcium and magnesium hardness from water by base exchange using natural or synthetic zeolites. Since the introduction of synthetic organic cation exchange resins, the more correct term is cation exchange softening. |
| Zero discharge water | The principle of ?zero discharge? is recycling of all industrial wastewater. This means that wastewater will be treated and used again in the process. Because of the water reuse wastewater will not be released on the sewer system or surface water. A disch |
| Zero soft water | Water produced by the cation exchange process and measuring less than 1.0 grain per U.S. gallon (17. 1 ppm or 17. 1 mg/L) as calcium carbonate. |
| Zeta potential | The electrical potential that exists across the interface of all solids and liquids. The potential represents the difference in voltage between the surface of the diffuse layer surrounding a colloidal particle and the bulk liquid beyond. Also known as ele |
| Zone of aeration | The comparatively dry soil or rock located between the ground surface and the top of the water table. |
| Zone of saturation | The space in the soil below the water table in which all the pores are filled with water. The water in the zone of saturation is groundwater. The layer in the ground in which all available interstitial voids (cracks, crevices, holes) are filled with water |
| Zero soft | Water with a total hardness less than 1.0 grain per US Gallon (17.1 ppm), as calcium carbonate. |
| Zooplankton | Tiny aquatic animals eaten by fish. Small, usually microscopic animals (such as protozoans), found in lakes and reservoirs. |
| Zwitter ions | Act as cations or as anions according to the environment in which they find themselves. In water technology they are usually organic macromolecules. |
| Nutrient | Nutrient - Need Description... |
