Filter rating meaning that 99.9 % (or essentially all) of the particles larger than a specified micron rating will be trapped on or within the filter.
The process in which one substance penetrates into the body of another substance, termed the absorbent. An example is the absorption of water into soil.
A substance which releases hydrogen ions when dissolved in water. Most acids will dissolve the common metals and will react with a base to form a neutral salt and water. An acid is the opposite of an alkali, has a pH rating lower than 7.0, will turn litmus paper red, and has a sour taste.
A measure of the amount of acid required to reduce pH to a predetermined level. This can be accomplished by use of an acid filtration procedure (Acid Demand Test).
The quantitative capacity of a water or water solution to neutralize an alkali or base. It is usually measured by tit-ration with a standard solution of sodium hydroxide, and expressed in ppm or mg/L of its calcium carbonate equivalent.
A medium made by treating aluminum ore so that it becomes porous and highly absorptive. 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.
Granulated active carbon used to remove tastes, odor, chlorine, chloramines and some organics from water. Carbon is the preferred treatment for a large percentage of water contaminants.
A negatively charged colloidal substance generally formed by combining a dilute sodium silicate solution with a dilute acidic solution (or other activant). Generally used as a coagulant aid.
The process by which molecules or colloids physically adhere to the surfaces of solids. Filter carbon adsorbs organic chemical.
Any substance that is or can be adsorbed. The liquid, gas or solid substance which is adsorbed as molecules, atoms, or ions.
As in the pressure in the sewer system or the creation of a negative pressure in the water supply line. Local plumbing codes usually require the air gap to be twice the diameter of the inlet with a minimum width of 1 1/2 inches.
The common name for aluminum sulfate [Al2 (SO4) x 14H2 O] which is often used as a coagulant in water treatment.
A single celled protozoan that is widely found in fresh and salt water. Some types of amoebas cause diseases such as amoebic dysentery.
An organism that can thrive in the absence of oxygen (air), such as bacteria in a septic tank.
A unit of wavelength of light equal to .00001 millimeter or .0001 microns.
A negatively charged ion in solution, such as bicarbonate, chloride, or sulfate. An anion [such as chloride (Cl-)] may result from the dissociation of a salt, acid, or alkali.
An ion exchange process in which anions in solution are exchanged for other anions from an ion exchange. In de-mineralization, 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.
The positive pole of an electrolytic system. The metal which goes into solution in a galvanic cell. 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.
Abbreviation for American National Standards Institute.
Containing water; watery.
A water treatment medium, usually solid, capable of the adsorption of liquids, gases, and/or suspended matter. Activated alumina and activated carbon are common adsorbents used in water processing.
The physical process occurring when liquids, gases, or suspended matters adhere to the surfaces of, or in the pores of, an adsorbent media such as activated carbon. Adsorption is a physical process which occurs without chemical reaction.
The process in which air is brought into intimate contact with water, often by spraying water through air, or by bubbling air through water. 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.
An action or process conducted in the presence of air, such as aerobic digestion of organic matter by bacteria.
A term usually applied to waters containing acid or oxygen which hasten corrosion (rusting).
A device which allows water, but not air, to pass through it. An air check is a typical component of a treatment system using a regenerant eductor.
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 is used to prevent cross connection between a water treatment device and a possible source of wastewater thereby preventing a reverse flow of water from the sewer into the water supply system. Without an air gap, such reverse flow could occur due to an increase in the pressure in the sewer system or the creation of a negative pressure in the water supply line. Local plumbing codes usually require the air gap to be twice the diameter of the inlet with a minimum width of 1 1/2 inches.
Plant life (green scum) containing chlorophyll is usually found in stagnant surface water. Excessive growths may create taste and odor problems, and consume dissolved oxygen during decay. Sometimes it may be controlled in a pond by the addition of Potassium Permanganate. In a water supply system, chlorination followed by dechlorination is often used.
A substance which creates a bitter taste and a slippery feel when dissolved in water and will turn red litmus paper blue. An alkali has a pH greater than seven and is the opposite of an acid. Highly alkaline waters tend to cause drying of the skin. Alkalies may include the soluble hydroxide, carbonate, and bicarbonate salts of calcium, magnesium, potassium, and sodium. A hydroxide alkali may also be called a base.
The quantitative capacity of water to neutralize an acid; that is, the measure of how much acid can be added to a liquid without causing a significant change in pH. Alkalinity is not the same as pH because water does not have to be strongly basic (high pH) to have high alkalinity. In the water industry, alkalinity is expressed in mg/l of equivalent calcium carbonate. There are three kinds of alkalinity: carbonate, bicarbonate, and hydroxide alkalinity. Total alkalinity is the sum of all three kinds of alkalinity. Different tests are used to determine the quantity of the different kinds of alkalinity present in water.
Natural underground reservoirs of porous layers of sand, rock or gravel.
Describes underground water trapped under pressure between layers of impermeable rock. An artesian well is one that taps artesian water.
American Society of Mechanical Engineers.
The process in which solids are worn down by friction, often between particles of the same material. Filter media and ion exchange materials are subject to attrition during back washing, regeneration and service.
A water softener (or filter) that is equipped with a clock timer, meter, or sensor which automatically initiates the backwash and/or regeneration process at the preset intervals of time. A predetermined number of gallons of water usage or as determined by a sensor. All operations, including bypass of treated or untreated water (depending upon design), back washing, brining, rinsing, and returning the unit to service are performed automatically.
American Water Works Association. Most municipal water treatment plants hold membership in this association.
Pressure which creates resistance against the flow of water.
Flow of water in a pipe or line in a direction opposite to the normal flow; often associated with back siphon-age or the flow of possibly contaminated water into a potable water system.
A device or system installed in a water line to stop backflow from a non-potable source.
The upflow or counter-current flow of water through a filter or ion-exchange medium, lifting the mineral bed and flushing away to the drain the particles of foreign matter that have been filtered from the water supply during the service cycle.
Unicellular microorganisms which typically reproduce by cell division. Although usually classed as plants, bacteria contain no chlorophyll. Many different types of bacterial organisms are often found in drinking water. Most municipally treated water is essentially bacteria free due to the addition of chlorine. Some forms of cyst type viruses have a degree of immunity to chlorine due to the cocoon-like shell around the virus. These types of organisms such as Giardia Cyst, Giardia Lamblia, and Cryptosporidium have a physical size of three to seven microns and can be effectively removed by sub-micron filtration. Some bacteria are helpful to man, others harmful.
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.
Any substance or agent which kills bacteria.
Water that is neither corrosive nor scaling (in relation to pH, total alkalinity, calcium hardness, and temperature factors). The Langelier Index for perfectly balanced water equals zero.
A unit of pressure. One bar equals 14.5 pounds per square inch (psi) or about 0.987 standard atmospheres.
An alkali that releases hydroxyl ions when dissolved in water. Bases reset with acids to form a neutral salt and water. In general they taste bitter rather than sour, and feel slippery and reverse the color changes produced by acids in indicators. For example, they turn litmus paper blue.
A measure of the amount of alkali material required to raise pH to a predetermined level. This can be accomplished by use of a base titration procedure (Base Demand Test).
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.
A mass of ion exchange resin particles or filter media contained in a column.
The height of the resin or filter media in the column after it has been properly conditioned for effective operation, usually expressed in inches. This depth excludes any supporting bed.
The effect produced during back washing: the resin particles become separated and rise in the column. The expansion of the bed due to the increase of the space between resin particles may be controlled by regulating backwash flow.
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 procured, and the solution is alkaline.
When used in reference to cartridge filters, refer to chemicals used to hold, or bind, short fibers together in a filter.
A chemical which can kill or inhibit the growth of lining organisms such as bacteria, fungi, molds, and slime. Biocides can be harmful to humans.
Subject to degradation into similar substances by biological action . Examples include detergents, sewage, and other organic matter by bacteria.
The trade name for a manganese dioxide coated aluminum silicate used as an oxidizing catalyst filter medium for iron and manganese reduction.
The fouling or plugging of pores in a membrane, usually a gel-like substance.
The withdrawal of water containing a high concentration of solids or dissolved solids or maintain a specified solids-to-water concentration ratio.
Abbreviation for Biochemical Oxygen Demand. The amount of oxygen consumed in the oxidation of organic matter by biological action under specific standard test conditions. Widely uses as a measure of the strength of sewage and wastewater.
A black pigment substance with a carbon content of about 10 percent, made by carbonizing animal bones. It is used as a selective anion exchanger for fluoride and arsenic reduction.
Water containing bacteria between 1.000 and 15,000 ppm of dissolved solids.
The first appearance in the solution flowing from an ion exchange unit of unabsorbed ions similar to those which are depleting the activity of the resin bed. Breakthrough is an indication that regeneration of the resin is necessary.
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.
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.
A tank which sits beside the softening unit and acts as a salt storage and brine supply.
Chemical sanitizer that kills bacteria and algae.
A chemical which causes a solution to resist changes in pH, or to shift the pH to a specific value.
A connection or a valve system that allows untreated water to flow to a water system while a softener or filter is being regenerated, backwashed or serviced; also applied to a special water line installed to provide untreated water to a particular tap, such as a sill cock.
The quality or power to carry electrical current; in water, the conductivity is related to the concentration of ions capable of carrying electrical current. The unit of measure is the mho, which is the reciprocal of resistivity which is the microhm.
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.
Object that is a source of contamination.
The addition of any physical, chemical, biological or radiological substance to water which reduces the value of the water, or interferes with its intended use.
A stopcock screwed into the street water main to provide the house service connection.
The destructive disintegration of metals by electromagnetically means. Corrosion of iron and steel is commonly called rusting.
The minimum depth of an adsorbent bed requited to contain the mass transfer zone.
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 systems.
The bonding of linear polymers into a resinous product with a material such as divenylbenzene (DVB). The degree of cross linking is a factor of the resin’s ability to withstand chemical oxidation. Softening resin is usually 8 percent cross linked, but can range from 6 percent to 10 percent which is used in hot water applications.
A precise separation of the components of a fluid by semi-permeable membrane through the application of pressure and flow.
A waterborne protozoan that forms cysts and causes acute illness in humans. This type of organism is resistant to chlorine and ultraviolet light but can be removed by one micron filtration.
Cellulose triacetate. Used to manufacture reverse osmosis membranes.
Chemical used to prevent the decomposition of chlorine by ultra-violet (UV) light.
A complete course of ion exchange operation. For instance, a complete cycle of cation exchange would involve: regeneration of the resin, rinse to remove excess regenerant, exhaustion, backwash, and finally regeneration again.
A process for the reduction of alkalinity in a water supply. It is generally accomplished by a chemical feed processor combined cation and anion exchange systems.
The removal from solution of inorganic salts by means of adsorption by ion exchange resins of both the cations and the anions that comprise the salts.
The removal of excess or free chlorine from a water supply by adsorption with activated carbon or by catalytic type filter media.
The degradation of an ion exchange resin structure by destruction of the crosslink polymer as the result of aggressive attack by chlorine, ozone, hydrogen peroxide, or heat. Decrosslinking causes increased moisture content in an ion exchange resin and the physical swelling of the beads.
The removal of dissolved gasses from water such as carbon dioxide, methane, hydrogen sulfide, and oxygen. This can by done by subjecting the water to below atmospheric pressure, or by passing air through the water at atmospheric pressure.
The removal of the ionized minerals and salts (both organic and inorganic) from a solution by a two-phase ion exchange procedure. First, positively charged ions are removed by a cation exchange resin in exchange for a chemically equivalent amount of hydrogen ions. Second, 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).
Calcium carbonate (CaCO3). A trade name for finely ground limestone, very high in calcium carbonate, which is used to raise the pH of acidic water.
One of the primary elements of the earth’s crust commonly found in water as a dissolved solid. The presence of calcium in water is a factor contributing to the formation of scale and insoluble soap curds which are means of clearly identifying hard water. It is sometimes referred to as lime.
All forms of water hardness and other salts are commonly expressed in terms of calcium carbonate equivalents. This is necessary so that minerals of varying weight can be expressed in chemically equivalent terms.
A measure of the calcium salts dissolved in water.
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., where the of these ratios represent the weight of the ions adsorbed and the denominators, the weight or volume of the adsorbent. It can also refer to the ability of any media to take up a specific contaminant and is rated by time over gallons. As to flow rates, it is the maximum or minimum flow obtainable under given conditions of media, temperature, pressure, velocity, etc.
Water with a low pH value usually contains free carbon dioxide. Its presence is caused generally 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.
Ion exchange materials of limited capacity prepared by the sulfonation of coal, lignite, peat, etc.
A substance that can cause cancer.
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.
A positively charged particle or ion.Sodium and calcium are prominent cations in water.
The common name for sodium hydroxide [NaOH]. Caustic soda is used in most water-base muds to increase and maintain pH and alkalinity. It is a hazardous material to handle because it is very caustic and gives off heat when dissolved in water. Proper training and equipment are needed to handle it safely.
Chlorine available to kill bacteria or algae. Chlorine that has not combined with other substances in water.
A material such as alum, which will form a gelatinous precipitate in water, and gather finely divided particles into larger ones which can then be removed by settling and/or filtration.
Those regulations which the department having jurisdiction may lawfully adopt.
A group of organisms primarily found in human and animal intestines and wastes, and thus widely used as indicator organisms to show the presence of such wastes in water and the possible presence of pathogenic (disease producing) bacteria.
Very finely divided solid particles larger than molecules but small enough that they will not settle out of a solution; intermediate between a dissolved particle and a suspended solid which will settle out of solution. Typically between 0.1 and 0.001 microns in diameter, it usually requires coagulation prior to filtration. colloidal (heme) iron may be removed by special anion resin.
A gelatinous or mucinous substance suspended in water that can pass through even the finest sediment filter.
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. It could indicate the presence of metallic ions, humus, tannins, or industrial wastes.
Decline in flux as a result of applied pressure compressing a reverse osmosis or ultrafiltration membrane.
A calculated value based on the hardness, the magnesium to calcium ratio, and the sodium concentration of a water. It is used to calculate the reduction in hardness removal capacity of a softener caused by these factors. No single method of calculation has been widely accepted.
The portion of a feed stream that retains the ions, organics and suspended particles that were rejected during the crossflow filtration process. (In other words, the rinse water from a reverse osmosis unit.)
The pressure drop or loss in psi between the inlet and the outlet of a water conditioner as the water flows.
The process of removing minerals from water, e.g. deionization, reverse osmosis and distillation.