Glossary of Terms - L
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The form of flow of a fluid in which the flow paths are in smooth, parallel lines with essentially no mixing and no turbulence.
Facility in which solid waste from municipal and/or industrial sources is disposed; sanitary landfills are those that are operated in accordance with environmental protection standards.
A calculated number used to predict the calcium carbonate (CaCO3) stability of a water; that is, whether a water will precipitate, dissolve, or be in equilibrium with, calcium carbonate.
It is sometimes erroneously assumed that any water that tends to dissolve CaCO3 is automatically corrosive.
Langelier saturation index = pH - pHs where pH = actual pH of the water, and pHs = pH at which the water having the same alkalinity and calcium content is just saturated with calcium carbonate.
See Also: Saturation Index Rzynar Index Saturation Index
A calculated number used to predict whether or not a water will precipitate, be in equilibrium with, or dissolve calcium carbonate. It is sometimes erroneously assumed that any water which tends to dissolve calcium carbonate is automatically corrosive.
A public water system that serves more than 50,000 persons.
linear alkylate sulfonate.
Time from the first exposure to a chemical until the appearance of a toxic effect.
The amount of heat released or absorbed when a substance changes its physical phase with no change in temperature.
For example, the heat absorbed from surroundings when ice melts into liquid water at the freezing point or the heat released when a gas (steam) condenses into liquid water.
The loss or gain of latent heat is not reflected in the temperature of the melting ice or the condensing water.
Sedmintation basin overflow weir. A plate with V-notches along the top to assure a uniform flow rate and avoid short-circuiting.
Sedimentation basin and filter discharge channels, consisting of overflow weir plates (in sedimentation basins) and conveying troughs.
A product containing a surfactant and other ingredients, formulated to clean and care for the many different fabrics in the family wash.
Next to the surfactant, a builder is an important ingredient in formulated laundry detergents. Builders have a number of functions, principally inactivation of water hardness, which interferes with good cleaning. Built detergent types include granules and liquids.
Some liquid detergents are unbuilt, containing surfactants that are relatively insensitive to water hardness.
Other customary ingredients of laundry detergents include antiredeposition agents, corrosion inhibitors, fluorescent whitening agents, colorants, fragrance, and processing aids.
Optional ingredients include suds control agents, bleach, borax, enzymes, bluing, fabric softener, and soil release agent.
Some laundry detergents are denser or more concentrated than others. Density or concentration influences the amount of product recommended for the wash. Detergents also vary in sudsing characteristics, ranging from high to low suds levels.
Different suds levels are provided for reasons of compatibility with machine design and to satisfy consumer preferences.
Depending on the presence of other ingredients in the laundry detergent formulation, some products offer special benefits in addition to the expected cleaning. Thus, certain laundry detergents are especially effective at lower washing temperatures; others provide additional fabric care benefits, such as softening, static control, and wrinkle reduction.
As relates to filtration, a multimedia filter bed containing, in the same vessel, several different filter media (such as anthracite, sand, and garnet) with specific gravities which differ enough to maintain different layers even after backwashing. layered bed
In ion exchange, a single exchange bed made up of two or more resins which have bead sizes and densities different enough to maintain layers after backwashing and which can be regenerated with the same regenerant. For example, a layered bed may have a mixed bed of anion resin on top and cation resin below that is regenerated by salt brine solution.
The concentration of a chemical in air or water which is expected to cause death in 50 percent of test animals living in the air or water.
The dose of a chemical taken by mouth or absorbed by the skin which is expected to cause death in 50 percent of the test animals so treated.
To dissolve out by the action of a percolating liquid.
The area where the effluent from a septic tank system is distributed by horizontal underground piping designed to aid in the process of natural leaching and percolation through the soil.
Water which has percolated or filtered through soil, a filter medium, or other substance containing soluble substances so that it now contains certain amounts of these substances in solution.
The process by which soluble substances are dissolved and transported down through the soil by recharge.
A heavy metal that is hazardous to health if breathed or swallowed. Its use in gasoline, paints, and plumbing compounds has been sharply restricted or eliminated by federal laws and regulations.
See Also: Inorganic Matter
A service line made of lead which connects the water main to the building inlet and any lead pigtail, gooseneck, or other fitting which is connected to such lead line.
As relates to ion exchange, the presence in the effluent of the type of ions, present in the feedwater to be treated, which the ion exchange process was supposed to remove.
Incomplete removal of the ions may be caused by incomplete regeneration, excessive service rates, low temperatures, high concentrations of sodium, or interfering TDS in the water being treated, and other factors.
Leakage is also referred to as slippage.
Over 26 species of bacteria, such as Legionella pneumophila, which can cause the pneumonia-like illness called "Legionnaires' Disease" (after the American Legion convention at which the disease first drew attention).
These bacteria are known to thrive at about 100 degrees F and are believed to live in infected humidifiers, cooling tower water, and shower rooms.
Infection is by inhalation.
A pathological or traumatic discontinuity of tissue or loss of function of a part.
A float device (or pressure switch) which senses changes in a measured variable and opens or closes a switch in response to that change.
In its simplest form, this control might be a floating ball connected mechanically to a switch or valve such as is used to stop water flow into a toilet when the tank is full.
Total amount of exposure to a substance that a human would receive in a lifetime (usually assumed to be 70 years).
A master control valve for operating and manually regenerating softeners and filters.
The common name for calcium oxide (CaO): hydrated lime is calcium hydroxide, Ca(OH)2.
Hard water scale containing a high percentage of calcium carbonate.
The insoluble calcium and magnesium salts formed from the fatty acid portion of soap when it combines with minerals in hard water; it is commonly referred to as soap curd.
The use of the word lime in this term may come from the fact that limestone areas generally foster hard water, or from the fact that the words lime and calcium are closely associated. Calcium and magnesium fatty acid salts are highly insoluble and precipitate immediately on formation. Since they tend to agglomerate (cluster together), they form curd-like masses. They also tend to adhere to surfaces, thus causing filming or deposits, such as bathtub ring.
The problems lime soap causes spurred the development of mechanical water softeners, packaged water softeners, and the technology leading to new surfactants and builders and detergent products based on them.
See Also: Carbonate Hardness Bicarbonate Hardness Hardness Hard Water Total Hardness (TH) Soap Curd Soap Soap Curd Soap Club Soda Community Water System Zone of Saturation Bottled Artesian Water Bottled Distilled Water Bottled Fluoridated Water Bottled Mineral Water Bottled Natural Water Bottled Spring Water Brackish Water Brine Internal Water Treatment Ion Exchange Aesthetic Contaminants Health Contaminant Drainage Basin Drinking Water Drinking Water Standards Municipal Water Permutit Process Phosphate Potable (Drinking) Water Etching External Water Treatment United States Pharmacopeia (USP) Water Softening WFI Sulfur (S) Safe Drinking Water Act (SDWA) Safe Water Sewage Silica Sodium Carbonate Softened Water Soft Water Permutit Process Phosphate Water Softening Sodium Carbonate
A water treatment which makes use of lime softening followed by the reduction of noncarbonate hardness by addition of soda ash (Na2CO3) to form an insoluble precipitate which is removed by filtration.
This method of removing hardness by filtration is sometimes used by municipalities, but it will leave five or more grains per gallon of residual hardness.
A water treatment, often used by municipalities, for partial reduction of water hardness. Controlled amounts of slaked lime [Ca(OH)2] are added to a hard water supply to remove the carbonate hardness by precipitation after which the precipitate is filtered out.
See Also: Hot-Lime Softening Hot Lime-Soda Softening Hot Process Softening Lime (CaO) Burnt Lime (CaO) Hydrated Lime Hot-Lime Softening Hot Lime-Soda Softening Hot Process Softening Municipal Softening Quicklime Water Softening Salinometer Slake Soap Soda Ash Soap Curd Lime (CaO) Burnt Lime (CaO) Ion Exchange Hydrated Lime Hot-Lime Softening Hot Lime-Soda Softening Hot Process Softening Municipal Softening Rated Capacity Water Softening Soda Ash Rated Capacity Hot Lime-Soda Softening Hot Process Softening Municipal Softening Soda Ash Hot Lime-Soda Softening Detergent Municipal Softening Water Softening Soda Ash Sodium Carbonate Lime (CaO) Burnt Lime (CaO) Ion Exchange Hydrated Lime Hot-Lime Softening Hot Lime-Soda Softening Hot Process Softening Municipal Softening Rated Capacity Water Softening Soda Ash Rated Capacity
A sedimentary rock, largely calium carbonate (CaCO3), usually containing significant amounts of magnesium carbonate. The calcite grade is used in filtration and for pH modification.
Several types of diaphragm valves which have adjustments used to control flow rates during various processes (backwash, fast rinse, or brine dilution) when brine is pumped in during batch regeneration of resin for portable ion exchange tanks.
The area of open water in a fresh water lake providing the habitat for fish, phytoplankton, and zooplankton.
The scientific study of conditions in freshwater lakes, ponds, and streams.
A pesticide that causes adverse health effects in domestic water supplies and also is toxic to freshwater and marine aquatic life.
Readily biodegradable form of alkylbenzene sulfonate surfactant.
This is the workhorse of the detergent industry, with sodium dodecylbenzene sulfonate being the most important single type. It is distinguished from an earlier form of alkylbenzene sulfonate, termed ABS, but is a linear (straight chain) structure, which provides its good biodegradation properties.
All LAS surfactants are anionic and high sudsing, but their sudsing may be controlled by formulation.
See Also: Atomic Absorption Spectroscopy Induced Infiltration Spectroscopy Adsorption Dose Emission Spectroscopy Alkylaryl Sulfonate Alkylaryl Sulfonate Alkylbenzene Sulfonate (ABS)
How closely an instrument measures actual values of a variable through its effective range; a measure used to determine the accuracy of an instrument.
Derivation of the multistage model, where the data are assumed to be linear at low doses.
The transformation to the liquid state. This term is more commonly used to refer to the changing of gases to liquids than to refer to the melting of solids to liquids.
Chromatography in which the mobile phase is a liquid (i.e., the sample is introduced into a liquid solvent which then flows through a fractionating column and to a detector). Separation of the sample components is accomplished via three different modes: 1. liquid/ liquid, in which the relative solubilities of sample components in two immiscible fluids (one of which is usually water) create separation; 2. liquid/solid, in which the relative adsorption of sample components on a solid adsorptive medium surface creates separation; and 3. molecular-size, in which separations are created because of the variations in effective molecular dimensions of the sample components in solution.
See Also: Chromatography Gas Chromatograph (GC) Gas Chromatography (GC) High Performance Liquid Chromatography (HPLC) Mass Spectrometry (MS) Chromatography High Performance Liquid Chromatography (HPLC) Chromatography Gas Chromatograph (GC) Gas Chromatography (GC) High Performance Liquid Chromatography (HPLC) Mass Spectrometry (MS)
A solution of one or more chemical substances (gas, solid, or liquid) in water.
The basic international metric unit of volume measure.
One liter equals 33.82 fluid ounces; 3.785 liters equals one U.S. gallon. One liter of water weighs 1,000 grams at 4 degrees Celsius at standard atmospheric pressure.
1. That portion of a body of fresh water extending from the shoreline lakeward to the limit of occupancy of rooted plants. 2. The strip of land along the shoreline between the high and low water levels.
The quantity of a substance entering the environment (soil, water, or air).
Lowest-observed-adverse-effect level; the lowest dose in an experiment which produced an observable adverse effect.
The exponent that indicates the power to which a number must be raised to produce a given number.
Also abbreviated to "log."
A flow pattern in which water travels from the bottom to top (or vice versa) in either a cartridge-type or loose media tank-type filtration system.
The advantages are greater contact time, higher unit capacity, more complete utilization of medium, and more uniform water quality.
Also called axial flow.
1. The plumbing network designed to continuously circulate ultrapure grade water in high purity water systems between storage and disinfection modes to maintain microbiological cleanliness. 2. A plumbing connection used to bypass water around a location designed for installation of a water treatment system or used when the treatment system is out of service for any reason.
Those filter units which have medium products positioned in a filter bed such that the individual medium grains or particles can be repositioned or lifted relative to each other with the flow of water or backwash water; as compared to permanently fixed bed media filter or a fixed solid block of filter media.
Filter or ion exchange media (in a tank or bed) which can be expanded during backwashing and rinsing. "Loose" is used to differentiate froma contained or "fixed medium" in a tank or the fixed or compressed media layer in a cartridge filter.
To undergo lysis
See Also: Ion Exchange Membrane Hemodialysis Dialysis Electrodialysis
A device for measuring the percolation and drainage of water through soils.
A process of disintegration or destruction of bacteria or microbiological cells by chemically breaking them down into their component parts.