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.
The quantitative capacity of a water or water solution to neutralize an alkali or base. It is usually measured by titration 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 adsorptive. 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.
A water treatment medium, found in block, granulated, or powdered form, which is produced by heating carbonaceous materials, such as coal, wood, or coconut shells, in the absence of air, creating a highly porous adsorbent material. Activated carbon is commonly used for dechlorination, organic chemical reduction and radon reduction, and is recognized by the US EPA as the best available technology for reduction of organic chemicals from drinking water.
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.
A water treatment medium, usually solid, capable of the adsorption of liquids, gasses, and/or suspended matter. Activated alumina and activated carbon are common adsorbents used in water processing.
The physical process occurs when liquids, gasses, or suspended matter 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.
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. 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.
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 alkalinities present in water.
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.
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 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.
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.
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 backwashing, 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), backwashing, brining, rinsing, and returning the unit to service are performed automatically.
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.
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.
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.
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.
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 backwashing: 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.
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 used 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.
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 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.
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.
In a softener or deionizer it is the adsorption activity possessed in varying degrees 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.
Carbonaceous Exchangers
Ion exchange materials of limited capacity prepared by the sulfonation of coal, lignite, peat, 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.
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.
The flow of water or regenerant taking the line of least resistance through a media bed, as opposed to the usual distributed flow through all passages of the bed. Channeling may be due to fouling of the bed, poor distribution design, low flow rates, or insufficient backwash.
The amount of matter, both organic and inorganic, in a water or wastewater which can be oxidized by boiling with a strong oxidizing acid, and expressed as the equivalent amount of oxygen. Often used as a membrane of the strength of sewage.
Chemical complexes formed from the reaction between ammonia and chlorine being used to disinfect many municipal water supplies. Does not combine with organics to form trihalomethanes.
A mechanical device specifically designed to feed chlorine gas or pellets, or solutions such as hypochlorites, into a water supply in proportion to the flow of water.
Widely used in the disinfection of water and as an oxidizing agent for organic matter, iron, hydrogen sulfide, etc. It is available as a gas, as a liquid in sodium, hypochlorite, or as a solid in calcium hypochlorite. In water chlorine reacts with organics to form trihalomethanes (THM) which can cause cancer.
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.
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.
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.
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 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.
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.
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 divinylbenzene (DVB). The degree of crosslinking is a factor of the resin's ability to withstand chemical oxidation. Softening resin is usually 8 percent crosslinked, but can range from 6 percent to 10 percent which is used in hot water applications.
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 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.
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 degradation of an ion exchange resin structure by destruction of the cross linked 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 be 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).
The removal of dissolved inorganic solids (salts) from a solution such as water to make it free of dissolved salts. Typically accomplished by reverse osmosis, distillation, or electrodialysis.
Usually refers to synthetic detergent, but can be any material with cleansing powers such as soap, alkaline materials, synthetic detergents, solvents, and abrasives. Synthetic detergents are known as surfactants which foam and act like soap but are not made from fatty acids and lye.
The separation of components of a solution by diffusion through a semipermeable membrane which is capable of passing certain ions or molecules while rejecting others.
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.
National Primary Drinking Water Standards established by the U.S. Environmental Protection Agency (EPA) are health related and establish the maximum contaminant levels (MCL's) for regulated substances in drinking water. A 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 EPA and pertain to aesthetic characteristics of water and are recommended only. Drinking Water Standards
The effectiveness of the operational performance of an ion exchanger. 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.
A chemical compound which dissociates or ionizes in water to produce a solution which will conduct an electric current. Could be an acid, base, or salt.
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. The process of washing out adsorbed material, especially by use of a solvent.
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
The aging process of a body of water caused by the depletion of available oxygen. It can be accelerated by human activities that add too many nutrients to the water such as barnyard runoff of fertilizers.
Locations on ion exchange resin beads which hold mobile ions that are available for exchange with other ions in a solution passing through the bed. These sites are also called functional groups.
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.
Small solid iron particles containing trivalent iron, usually as gelatinous ferric hydroxide or ferric oxide (Fe2O3), which are suspended in water and visible as "rusty" water. Ferrous (iron in solution) is readily converted to ferric iron by exposure to oxygen found both in water and air. Ferric iron can be removed by filtration, but not by ion-exchange.
A naturally occurring ore which serves as a catalytic filter media in the removal of iron, hydrogen sulfide and manganese. It normally requires only backwashing, but the use of oxidizers such as chlorine or potassium permanganate enhances its action.
A device used to clean water by removing iron, silt, taste, odor, color, etc., before it is fed into the softener or supply lines of the consumer. Includes mechanical, adsorptive, oxidizing and neutralizing filters. Available as media beds in tanks or as cartridge type devices
The trade name for aluminum silicate (pumicite) granular product 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.
Smaller than the specified size or particles of ion exchange or filtration materials. An excess of fines can create undesirable pressure drops in the system.
A count of the total number of plumbing fixtures in a building to estimate peak flow rates and the sizing of equipment, especially for commercial buildings.
Materials added to water which can cause gelatinous clouds of precipitate to enclose fine particles of foreign material in order to settle or filter them from the water.
The volume of solution which passes through a given quantity of resin within a given time. Flow rate is 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.
In crossflow filtration, it is the product flow rate through a reverse osmosis, electrodialysis or ultrafiltration membrane. It is usually given in terms of volume unit per time per membrane area.
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.
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.
A form of corrosion which occurs when dissimilar metals in contact with each other and with an electrolyte causes one of the metals to dissolve and go into solution. An example would be the result of connecting copper to steel without an insulating (plastic) coupling or union. The anode metal with the higher electrode potential corrodes and the cathode is protected.
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.
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 the hardness of water.
A layer or layers of graded gravel and coarse 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.
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.
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.
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.
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, high concentrations of sodium or interfering TDS in the feedwater.
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.
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.
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.
The process of purifying a kidney patient's blood by means of a dialysis membrane. In this process bodily waste is transferred from the blood into a hemodialysis grade water which is beyond the membrane.
A chemical, such as sodium hexametaphosphate, is 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.
Partially softens water by adding lime and soda ash at a water temperature of about 212 degrees Fahrenheit. It chemically precipitated calcium, magnesium, iron, and silica. It also drives away carbon dioxide.
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.
A complete course of cation exchange operation in which the cation medium is regenerated with acid and then all cations in the water are removed by exchange with hydrogen ions.
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.
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.
A piping arrangement which 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.
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.
An atom, or group of atoms in a solution which functions 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.
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. for a product offering.
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.
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.
An element often found dissolved in groundwater (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).
Organisms which 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.
An arbitrary unit of turbidity originally based on a suspension of a specific type of silica with the turbidity measured in a Jackson Candle Turbidimeter. This has been replaced by the nephelometric turbidity unit (NTU).
A water treatment media employing copper and zinc alloy particles which 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.
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.
A calculated number that gives an 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.
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.
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 scales and thrive below 140 degrees Fahrenheit in water heaters, showers, humidifiers, etc. Infection is obtained by inhalation.
Hard water scales contain a high percentage of calcium carbonate. Insoluble scales are commonly formed when water containing calcium carbonate is heated. It also forms in cold water but precipitates at a higher pH.
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 which is filtered from the water. This method leaves five or more grains of hardness.
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.
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.
An element sometimes found dissolved in groundwater, 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.
Greensand which 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.
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.
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.
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.
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.
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..
(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.
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.
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.
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 be used for selective removal of hardness ions.
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.
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 is 7.0, indicating the presence of equal numbers of free hydrogen and hydroxide ions.
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.
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.
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.
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 (TCE).
A process of diffusion of a solvent such as water through a semipermeable membrane which will transmit the solvent but impede most dissolved substances. The normal flow of solvent is from the dilute solution to the concentrated solution. Osmosis causes the stronger solution to become more diluted and tends to equalize the opposing solutions.
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 inch of osmotic pressure. Osmotic pressure must first be overcome by water pressure in the reverse osmosis process.
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.
A chemical process in which electrons are removed from an atom, ion or compound. The addition of oxygen is a specification of oxidation. Combustion is an extremely rapid form of oxidation, while the rusting of iron is a slow form. Oxidation never occurs alone but always as a part of the oxidation-reduction (redox) reaction.
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.
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 manganese oxide and then filters the oxidized precipitant out of the water.
An unstable form of oxygen (03), which can be generated by sending a high voltage electrical discharge through air or regular oxygen. It is a strong oxidizing agent and has been used in water conditioning as a disinfectant. It can also be produced by some types of ultraviolet lamps and during lightning storms.
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 other solvent. One part per billion is equal to one microgram per liter, the preferred unit.
A common basis for reporting the results of water and wastewater analysis, indicating the number of parts by weight of water or other solvent. In dilute water solutions, one part per million is practically equal to one milligram per liter, which is the preferred unit. 17.l ppm equals one grain per US gallon. One ppm equals one pound per million pounds of water.
An expression of the acidity of a solution; the negative logarithm of the hydrogen ion concentration (pH 1 very acidic; pH 14, very basic; pH 7, neutral). e.g., pH 5 is 10 times the acidity of 6 and 100 times the acidity of 7. pH is a measure of intensity and not capacity. It is the logarithm of the reciprocal of the hydrogen ion concentration of a solution. The neutral point of 7 indicates the presence of equal concentrations of free hydrogen and free hydroxide ions.
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 irrigation.
The quality which an ion exchange resin must possess to resist changes that might be caused by attrition, high temperatures, and other physical conditions.
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.
Water softeners, deionizers, and filters which are designed for removal from its point of application for transport to a central station or plant for regeneration or servicing.
Water which is considered safe and fit for human consumption, culinary and domestic purposes and meets the requirements of the health authority having jurisdiction.
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 which the water flows.
Any of a large group of mostly microscopic, one celled animals living chiefly in water. Many protozoans are parasitic and are higher on the food chain than the bacteria they eat.
The removal of undesirable matter from water or wastewater. It is the disinfection of water by the killing of microbial contaminants, such as coliform bacteria. A strict definition means the removal from water of all contaminants.
Biological decomposition of organic matter by microbes with the production of ill smelling products. Usually takes place when there is a deficiency of oxygen.
Substances which produce fever when introduced into humans. Being chemically stable, pyrogens are not necessarily destroyed by conditions that kill bacteria. Pyrogenic means to cause heat.
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 this 120 lb. per cubic foot media.
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 glass.
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.
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.
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 a manganese greensand iron and manganese iron and manganese removal filter.
The process of returning the sodium ions to the mineral after it has exchanged all its sodium ions for calcium and magnesium from hard water. This is accomplished by first back-washing the mineral bed to free it of all foreign matter, them passing salt brine through the mineral. The sodium ions attach themselves to the mineral, and the calcium and magnesium combine with the chloride from the brine to form calcium and magnesium chlorides, which are rinsed down the drain. All water softeners using the ion-exchange process are regenerated with these basic steps. In similar fashion cation and anion components of a demineralizer as well as manganese greensand are recharged with comparable sequences.
In crossflow 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.
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 residual chlorine.
Synthetic organic ion exchange material, such as the high capacity cation exchange resin widely used in water softeners. Technical name- sulfonated copolymer of styrene and divinylbenzene.
A process for the removal of dissolved ions from water, in which pressure is used to force the water through a semipermeable membrane, which will transmit the water but reject most other suspended and dissolved materials. It is called reverse osmosis because mechanical pressure is used to force the water to flow in the direction that is the reverse of natural osmosis, namely from the dilute to the concentrated solution.
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.
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.
A treatment device or structure for removing solid or colloidal material of a type that cannot be removed by sedimentation. Such filters can be gravity rapid-rate or enclosed pressure type.
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 which can be formed by the neutralization of an acid with a base.
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.
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.
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.
The expansion of an ion exchange bed which 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.
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. Considered a pollutant when present in excess.
The third stage in the treatment of sewage is a high degree of conditioning following the reduction of pollutants accomplished by the primary and secondary stages of treatment.
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.
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).
The alkalinity of a water is determined by titration with standard acid solution to the methyl orange endpoint (pH approximately 4.5); sometimes abbreviated as "M alkalinity". Total alkalinity includes many alkalinity components, such as hydroxides, carbonates, and bicarbonates.
The weight of solids per unit volume of water which 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 conductivity test provides only an estimate of the TDS since non-conductive substances cannot be measured by electrical means.
The sum of all hardness components in a water, expressed as their equivalent concentration of calcium carbonate. Primarily due to calcium and magnesium in solution, but may include small amounts of metals such as iron which can act like calcium and magnesium in certain reactions. These minerals are scale forming, affect taste and color of certain foods and react with soap to form insoluble soap curds.
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.
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 of water at 105 degrees Celsius in a pre-weighed dish.
A group of organic chemicals known to be carcinogenic in more than trace amounts which are produced from chlorination. They reduce the germicidal activity of chlorine in alkaline water.
A measure of the amount of finely divided suspended matter in water, which causes the scattering and absorption of light rays. Turbidity is usually reported in arbitrary nephelometric turbidity units (NTU) determined by measurements of light scattering. NTU should not exceed 0.5 in potable water. Turbidity can protect bacteria from sterilization.
A membrane type system that removes small colloids and large molecules from solutions. Ultrafiltration removes particles in a size range between 0.002 to 0.1 micron range. The process falls between reverse osmosis and microfiltration as far as the size of particles removed is concerned.
No standards exist describing ultrapure water though it is not considered to be sterile. It is water that has been deionized and provides high resistivity and contains no organics.
Radiation having a wavelength shorter than 4000 angstroms (visible light) down to 100 angstroms on the border of the x-ray region. Ultraviolet light is used as a disinfectant.
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 conditioning system.
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 parasitic infectious microbes, they are much smaller than bacteria.
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.
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.
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 as potassium and used to remove undesirable elements such as iron, hydrogen, sulfide, and manganese.
