Glossary of Terms

Glossary of Terms - P

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Pascal.
A bed of filter or ion exchange medium which is completely retained so that no bed expansion can occur and no backwash step is used to reclassify the filter or resin.

Packed beds are usually part of the design features in ion exchange water softeners used to obtain high capacity and increased regeneration efficiency.

A method of treating water to remove volatile organic chemical (VOCs) contaminants.

As water is mixed with air, VOCs move from water to air which then passes through carbon filters to trap the contaminants.

Water at a desirable temperature that is free from objectionable tastes, odors, colors, and turbidity. Pleasing to the senses.
A device used to measure the flow in an open channel.

The flume narrows to a throat of fixed dimensions and then expands again. The rate of flow can be calculated by measuring the difference in head (pressure) before and at the throat of the flume.

A very tiny, separate subdivision of matter.
The results of a microscopic examination of treated water with a special "particle counter" which classifies suspended particles by number and size.
The results of a microscopic examination of treated water with a special "particle counter" which classifies suspended particles by number and size.
As used in industry standards, the size of a particle suspended in water as determined by its smallest dimension, usually expressed in microns.
A very small solid suspended in water which can vary widely in size, shape, density, and electrical charge.

Colloidal and dispersed particulates are artificially gathered together by the processes of coagulation and flocculation.

A measure of the extent to which a pesticide is divided between the soil and water phases.
A measure of proportion by weight which is equivalent to one unit weight of solute (dissolved substance) per billion unit weights of the solution.

This measurement is often used as a measure of concentration when analyzing water for contaminants. Since one liter of water weighs one billion micrograms, one ppb is the equivalent of one microgram per liter when used in water analysis.

A common basis for reporting the results of water and wastewater analyses, indicating the number of parts by weight of a dissolved or suspended constituent, per million 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. 17.12 ppm equals one grain per U.S. Gallon.
A unit of pressure equal to one newton of force per square meter.

One thousand pascals equal one kilopascal (KPa); a kilopascal equals 0.145 pounds per square inch.

1 psi = 6895 Pa = 6.895 kN/sq.m = 0.0703 kg/sq.cm

A process for the partial sterilization (disinfection) of a substance, usually a liquid, by heating it to a critical temperature for a specified period of time.

Pasteurization does not greatly change the chemical composition of the sterilized substance.

An organism which may cause disease.
Capable of causing disease.
Organisms, including bacteria, viruses, or cysts, capable of causing diseases (typhoid, cholera, dysentery) in a host (such as a person).

There are many types of organisms which do NOT cause disease. These organisms are called nonpathogenic.

The study of disease.
The maximum rate of flow under which a treatment unit is designed to properly function and produce a certain quality product water.
(CH3COOOH) A strong oxidizing liquid used in a proprietary one percent solution with hydrogen peroxide as an effective sanitizer and disinfectant for both cellulosic and thin-film composite reverse osmosis membranes.

Can be made by reaction of acetic acid (vinegar, CH3COOH) and hydrogen peroxide (H2O2-) with a sulfuric acid catalyst.

The percentage of the feedwater which becomes product water.

Determined by the number of gallons (or liters) of product water divided by the total gallons (or liters) of feedwater and multiplied by 100.

The percent recovery is called recovery rate in reverse osmosis and ultrafiltration.

(reverse osmosis/ultrafiltration) The percentage of TDS in the feedwater that is prevented from passing the membrane with the permeate.

The formula used is: the difference obtained from the TDS in feedwater minus TDS in permeate divided by TDS in feedwater; then multiply the answer obtained by 100 to obtain a percent.

The amount of a substance that is dissolved in a solution compared with the amount that could be dissolved in the solution, expressed as a percent.

Amount of substance that is dissolved divided by the amount that could be dissolved in solution X 100 percent.

Water that passes through soil or rocks under the force of gravity.
1. The slow seepage of water into and through the ground.

2. The slow passage of water through a filter medium.

Water hardness due to the presence of the chlorides and sulfates of calcium and magnesium which will not be precipitated by boiling. This term is largely replaced by "noncarbonate hardness."
The reciprocal of the logarithm of the hydrogen ion concentration. The pH scale is from 0 to 14, and 7.0 is the neutral point, indicating the presence of equal concentrations of free hydrogen and hydroxide ions. pH values below 7.0 indicate increasing acidity, and pH values above 7.0 indicate increasing base concentrations.
A salt of phosphoric acid.

In the water industry, polyphosphates are used as sequestering agents to control iron and hardness, and as coating agents to control corrosion by formation of a thin passivating film on metal surfaces.

The complex phosphates also are a group of sequestering agents widely used in detergent formulations (except where phosphates are banned by law) because of their superiority in chemical water softening, sequestering, and other builder functions.

Sodium tripolyphosphate was the original builder upon which modern laundry detergent technology developed, and is used in laundry granules, automatic dishwasher detergents, and cleansers. It is adaptable to the spray drying process by which granules are made.

Tetrasodium pyrophosphate is also used in detergent granules, but since it does not rank as high in overall performance as sodium tripolyphosphate, its application is more limited.

Highly soluble tetrapotassium pyrophosphate is used in liquid laundry detergents and in hard surface cleaners, where it serves as a builder, water softener, and source of alkalinity.

Another complex phosphate, sodium metaphosphate, is marketed as a packaged water softener. The most widely used sodium metaphosphate is sodium hexametaphosphate (SHMP), which softens by sequestering.

The orthophosphate form of phosphates, trisodium phosphate (also called sodium orthophosphate), is a water softener that inactivates hardness minerals by precipitation. It is used to a limited extent in soap and detergent formulations as a builder, as a source of alkalinity, and for its water-softening properties. It is also used in powdered hard surface cleaners and cleansers to supply alkaline cleaning power.

Chlorinated trisodium phosphate is a dry chlorine bleach which, in water, acts much like sodium hypochlorite (liquid chlorine bleach). It provides a means of incorporating chlorine bleach effectively in dry products, and for this reason is used in cleansers and automatic dishwasher detergents. It also provides alkalinity that aids in cleaning.

See Also: Base Alkali Alkalinity Alkalinity Tests Hydroxide Alkalinity Detergent Methyl Orange Methyl Orange Alkalinity Phenolphthalein Soap Detergent Sodium Carbonate Chelating Agent Polyphosphate Chelating Agent Polyphosphate Surfactant Sequestering Agent Club Soda Community Water System Zone of Saturation Bottled Artesian Water Bottled Distilled Water Bottled Fluoridated Water Bottled Mineral Water Bottled Natural Water Lime Soap Bottled Spring Water Brackish Water Brine Internal Water Treatment Ion Exchange Aesthetic Contaminants Health Contaminant Drainage Basin Drinking Water Drinking Water Standards Municipal Water Permutit Process 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 Lime Soap Permutit Process Water Softening Sodium Carbonate

A nonmetallic element which is essential to life.

However, too much phosphorus in a body of water can cause excessive growth of plant life, which can create a lack of oxygen as the plants die and decay.

The chemical process by which green plants make carbohydrates (which the plants use as food) from carbon dioxide and water in the presence of sunlight and chlorophyll.

Oxygen is released as a byproduct of photosynthesis.

A type of plant with very long roots and extensive root systems which draws its water from the water table or other permanent groundwater supplies.

Examples of phreatophytes are willow and salt cedar. Excessive growths of phreatophytes are undesirable in areas where water is scarce since they can consume large quantities of water.

A measure of the ability of an ion exchanger or a filter medium to resist breakdown caused by the physical forces such as crushing, attrition, or high temperatures to which it is subjected during use.
Small, usually microscopic plants (such as algae), found in lakes, reservoirs, and other bodies of water.
A prefix used in the metric system to mean one-trillionth or 10-12 or 0.000000000001.
Pilot testing usually refers to a pilot plant which is a trial intermediate between laboratory bench testing and full scale-operation in the field. Pilot testing is often conducted on-site in the field with a scaled down replica of the full scale treatment plant.
A measure of the completeness of an incomplete chemical reaction, using a logarithmic scale. Also used to express the extent of dissociation of weak acids and complex ions. The weaker the electrolyte, the larger is its pK. The strengths of different acids may be compared by using pK values. Mathematically speaking, pK is the negative of the logarithm of the ionization (dissociation) constant (pKeq) of a chemical compound.
A diagram or photo showing a facility as it would appear when looking down on top of it.
Tubing or pipe made from unreinforced thermoplastic polymers such as polyethylene, polybutylene, polyvinyl chloride, chlorinated polyvinyl chloride, and polypropylenes, and from reinforced thermosetting polymers such as epoxides and polyesters with glass fibers as reinforcing to increase strength.

Plastic pipe is characteristically flexible to rigid, lightweight, and strong; it resists attack by chemicals, corrosion, and weathering.

See Also: Chlorinated Polyvinyl Chloride (CPVC) Polybutylene (PB) Polycarbonate Polyethylene Polypropylene Polyvinyl Chloride (PVC) XPLE or PEX Polyethylene Polypropylene Cross-linked Polyethylene (XLPE or PEX) Polyvinyl Chloride (PVC) Polyvinyl Chloride (PVC)

A flow pattern in which the water being processed passes through the medium (such as a granular filter or an ion exchange bed) in a "piston-like" fashion instead of in turbulent or mixed flow patterns such as are found in other processes like ultraviolet light disinfection and electrodialysis.
The way polluted water extends downstream from the pollution source (analogous to smoke from a smokestack as it drifts downwind in the atmosphere).
Powered or moved by air pressure or compressed air.
A pressurized holding tank which is part of a closed water system (such as for a household well system) and is used to create a steady flow of water and avoid water surges created by the pump kicking on and off.
Point of entry.
The reciprocal of the logarithm of the hydrogen ion concentration. The pOH is related to pH by the expressions: pH + pOH = 14
A stationary location or fixed facility from which pollutants are discharged or emitted.

Also, any single identifiable source of pollution, e.g., a pipe, ditch, ship, ore pit, factory smokestack.

Full service water treatment applied to the water entering a house or building for the purpose of reducing contaminants in the water distributed throughout the house or building (outside faucets may be excepted from treatment).
As relates to electricity and corrosion control, to disrupt the corrosion process by developing a barrier on an anodic or cathodic surface.
A copper bar circling the laminated iron core inside the coil of a magnetic starter.
A treatment stage placed at the end of other treatment to bring the water to a more highly conditioned and more perfect state. For example, a mixed bed of ion exchange media installed as the final treatment step in the deionization process to remove last traces of undesirable ions.
A filter installed for use after the primary water treatment stage to remove any traces of undesirable matter or to polish the water.
A contaminant existing at a concentration high enough to endanger the environment or the public health or to be otherwise objectionable.
"Pollution is an impairment of quality such that it interferes with the intended usages." (House Report 2021)
A molecular chain polymer made of amide (-CONH-) linkages.

Proteins of plants such as soybeans, peanuts, and corn are natural polyamides. Nylon is example of a synthetic polyamide.

Thin-film composite reverse osmosis membranes are constructed of a thin layer of an aromatic polyamide extruded onto a less dense polysufone substrate.

See Also: Polysulfone Reverse Osmosis Polysulfone Reverse Osmosis Charged Polysulfone Membrane Polysulfone Electrodialysis Reverse Osmosis

A thermoplastic polymer, such as butyl rubber, of a butylene liquefied petroleum gas -- isobutene, butene-1, or butene-2; manufactured in various degrees of elasticity, strength, and stability. Used for films, coatings, pipes, tubing, fittings, and many other services.

See Also: Chlorinated Polyvinyl Chloride (CPVC) Plastic Pipe Polycarbonate Polyethylene Polypropylene Polyvinyl Chloride (PVC) Chlorinated Polyvinyl Chloride (CPVC) Plastic Pipe Polycarbonate Polyethylene Polypropylene Polyvinyl Chloride (PVC) Chlorinated Polyvinyl Chloride (CPVC) Polycarbonate Polyethylene Polypropylene Polyvinyl Chloride (PVC)

A thermoplastic polymer resin that is a linear polyester of carbonic acid. Polycarbonate is a transparent, nontoxic, noncorrosive, heat resistant, high impact strength plastic; it is generally stable, but may be subject to attack by strong alkalies and some organic hydrocarbons. It can be molded, extruded, or thermoformed, and is commonly used for numerous services, such as nonbreakable windows, household appliances, tubing, piping, and cartridge filter sumps.

See Also: Chlorinated Polyvinyl Chloride (CPVC) Plastic Pipe Polybutylene (PB) Polyethylene Polypropylene Polyvinyl Chloride (PVC) Chlorinated Polyvinyl Chloride (CPVC) Plastic Pipe Polybutylene (PB) Polyethylene Polypropylene Polyvinyl Chloride (PVC) Chlorinated Polyvinyl Chloride (CPVC) Polybutylene (PB) Polyethylene Polypropylene Polyvinyl Chloride (PVC)

A polymeric electrolyte (natural or synthetic) with a long chain-like structure and a high molecular weight which may be used as a cationic, anionic, or nonionic flocculent (or coagulant aid) in the treatment of potable water.

Often called a polymer.

A tough thermoplastic polymer (-CH2CH2-) of ethylene that resists chemicals and absorbs very little moisture.

Polyethylene can vary from soft and flexible to hard and rigid depending on the pressures and catalysts used during manufacturing.

Low density polyethylene has its melting point at about 240 degrees Fahrenheit and tensile strength of 1500 psi; high density polyethylene melts at 275 degrees Fahrenheit and has tensile strength of 4000 psi.

Among services, polyethylene is commonly used for tubing and piping, food packaging, garment bags, and molded plastic products.

See Also: XPLE or PEX Plastic Pipe Polypropylene Cross-linked Polyethylene (XLPE or PEX) Chlorinated Polyvinyl Chloride (CPVC) Plastic Pipe Polybutylene (PB) Polycarbonate Polypropylene Polyvinyl Chloride (PVC) Chlorinated Polyvinyl Chloride (CPVC) Plastic Pipe Polybutylene (PB) Polycarbonate Polypropylene Polyvinyl Chloride (PVC) Chlorinated Polyvinyl Chloride (CPVC) Polybutylene (PB) Polycarbonate Polypropylene Polyvinyl Chloride (PVC)

A chemical formed by the union of many monomers (a molecule of low molecular weight).

Polymers are used with other chemical coagulants to aid in binding small suspended particles to larger chemical flocs for their removal from water.

All polyelectrolytes are polymers, but not all polymers are polyelectrolytes.

A form of phosphate polymer consisting of a series of condensed phosphoric acids containing more than one atom of phosphorous.

Polyphosphate is used as a sequestering agent to control iron and hardness, and as a coating agent that forms a thin passivating film on metal surfaces to control corrosion.

Polyphosphates in solution are anionic and may be removed from water with anion exchange resins. However, polyphosphates that have reacted with a metal (e.g., iron) can form a sticky colloidal precipitate that must be filtered to be removed from water.

See Also: Chelating Agent Phosphate Chelating Agent Phosphate Surfactant Sequestering Agent

A thermoplastic polymer of propylene resembling polyethylene, and used for making molded and extruded plastic products such as water pipe, tubing, and fittings.

See Also: Chlorinated Polyvinyl Chloride (CPVC) Plastic Pipe Polybutylene (PB) Polycarbonate Polyethylene Polyvinyl Chloride (PVC) Chlorinated Polyvinyl Chloride (CPVC) Plastic Pipe Polybutylene (PB) Polycarbonate Polyethylene Polyvinyl Chloride (PVC) Chlorinated Polyvinyl Chloride (CPVC) Polybutylene (PB) Polycarbonate Polyethylene Polyvinyl Chloride (PVC) XPLE or PEX Plastic Pipe Polyethylene Cross-linked Polyethylene (XLPE or PEX)

Polymerized styrene.

Polystyrene forms the skeletal structure of most common ion exchange resin beads.

A synthetic thermoplastic polymer. Used in the manufacture of ultrafiltration membranes and in thin-film composite and charged polysulfone reverse osmosis membranes.

See Also: Reverse Osmosis Charged Polysulfone Membrane Reverse Osmosis Thin-Film Composite Membrane Charged Polysulfone Membrane Polyamide Electrodialysis Reverse Osmosis Polyamide Reverse Osmosis Polyamide Reverse Osmosis Charged Polysulfone Membrane Polyamide Electrodialysis Reverse Osmosis

A thermoplastic polymer resin material (-CH2CHCl-) that is rigid and practically chemically inert.

Commonly used for water pipes and fittings, as well as numerous other services such as siding, gutters, raincoats, chemical containers, flooring, toys, tennis court surfaces, and films and package coatings for food containers.

See Also: Plastic Pipe Plastic Pipe Chlorinated Polyvinyl Chloride (CPVC) Plastic Pipe Polybutylene (PB) Polycarbonate Polyethylene Polypropylene Chlorinated Polyvinyl Chloride (CPVC) Plastic Pipe Polybutylene (PB) Polycarbonate Polyethylene Polypropylene Chlorinated Polyvinyl Chloride (CPVC) Polybutylene (PB) Polycarbonate Polyethylene Polypropylene

A thermoplastic fluorocarbon polymer that can be used for injection molded or extruded products.

More highly inert and resistant to oxidative degradation than polypropylene plastic, for example, but not as inert as the tetrafluoroethylene (TFE) fluorocarbon polymers (Teflon).

A population subgroup that is more likely to be exposed to a chemical, or is more sensitive to a chemical, than is the general population.
A unit of measure used to express the strength of waste water from any source. (That is, not from household waste water only.) In making such calculations, 0.17 pounds of BOD (biological oxygen demand) per capita per day is often used as the standard figure.

Thus, waste water with 17 pounds of BOD per day would have a population equivalent of 17 divided by 0.17 or 100 people.

A very small open space in a rock or granular material.
A measure of the volume of internal pores in filter media and ion exchangers, sometimes expressed as a ratio to the total volume of the medium.
Full of pores through which water, light, etc. may pass.
Tanks containing up to two cubic feet of ion exchanger products or filter media which are rented to homeowners or business clients with the beds fully-regenerated and ready for use.

Portable exchange tanks do not have the valving controls required for regeneration. Upon exhaustion (determined by predetermined calendar days, meter, or monitoring device), the tanks are returned to a central regeneration plant where the resin or other media in each tank is reprocessed and restored for reuse.

Portable exchange tanks may be available with water softening or deionization resins, mixed ion exchange media, manganese zeolite, activated alumina, and activated carbon.

Portable exchange tanks are used for both household and commercial applications.

The electrical charge on an electrode or ion in solution due to the removal of electrons.
A type of piston, diaphragm, gear, or screw pump that delivers a constant volume with each stroke.

Positive displacement pumps are used as chemical solution feeders.

The application of chlorine to a water following other water treatment processes.
Water which is safe and suitable for human consumption.
A type of piston, diaphragm, gear, or screw pump that delivers a constant volume with each stroke.

Positive displacement pumps are used as chemical solution feeders.

The use of potassium chloride salt instead of sodium chloride salt in the regeneration of cation ion exchange water softeners.

The potassium ion (K+) becomes the exchangeable ion rather than the sodium ion (Na+) in the sodium cycle system.

(KMnO4) Dark purple, odorless crystals (with a blue metallic sheen) that dissolve in water to produce a purple-red color.

Potassium permanganate is a powerful oxidizing agent that is used in water treatment as both an oxidizer and a disinfectant.

It is also an effective regenerant for manganese oxidizing filters.

Amount of material necessary to produce a given level of a deleterious effect.
The effect of one chemical to increase the effect of another chemical.
The level to which water will rise in cased wells or other cased excavations into aquifers, measured as feet above mean sea level.
Point-of-use.
Unit of measure for expressing pressure.
Pressure measured with respect to that of the atmosphere. This is a pressure gauge reading in which the gauge is adjusted to read zero at the surrounding atmospheric pressure. It is commonly called gauge pressure.
The ratio of the true power passing through an electric circuit to the product of the voltage and amperage in the circuit.

This is a measure of the lag or load of the current with respect to the voltage.

Parts per billion.
The abbreviation for "Parts Per Million"
Parts per trillion.
The application of chlorine to a water prior to other water treatment processes
To cause a dissolved substance to form a solid particle which can be removed by settling or filtering, such as in the removal of dissolved iron by oxidation, precipitation, and filtration. The term is also used to refer to the solid formed and to the condenation of water in the atmosphere to form rain or snow.
1. The process by which atmospheric moisture falls onto a land or water surface as rain, snow, hail, or other forms of moisture.

2. The chemical transformation of a substance in solution into an insoluble form (precipitate).

The ability of an instrument to measure a process variable and to repeatedly obtain the same result. The ability of an instrument to reproduce the same results.
The application of a granular filter medium, such as diatomaceous earth, to a membrane prior to the service cycle of a filter.
Compounds which lead to other compounds.

For example, natural humic and fulvic acids which, upon combination with chlorine, lead to trihalomethanes.

A filter used in a water treament plant for the partial removal of turbidity before final filtration. Such filters are usually of the rapid type, and their use allows final filtration at a more rapid rate or reduces or removes the necessity of other preliminary treatment of the water. Also called contact filter, contact roughing filter, roughing filter.
An installation which allows domestic water treatment equipment to be easily installed because the necessary bypass and valves are already in place.

An example would be a new home that already has all of the plumbing needed for installing a water treatment device.

Water rights which are acquired by diverting water and putting it to use in accordance with specified procedures.

These procedures include filing a request to use unused water in a stream, river, or lake with a state agency.

An agent that prevents the deterioration of materials; usually associated with the prevention of biological deterioration.
A switch which operates on changes in pressure. Usually this is a diaphragm pressing against a spring. When the force on the diaphragm overcomes the spring pressure, the switch is actuated (activated).
The difference in pressure between two points in a system due to differences in elevation and/or pressure drop due to flow.
A decrease in water pressure during flow due to internal friction between molecules of water, and external friction due to irregularities or roughness in surfaces past which the water flows.
The vertical distance (in feet) equal to the pressure (in psi) at a specific point.

The pressure head is equal to the pressure in psi times 2.31 ft/psi.

A process using a molecular sieve material, when pressurized to just overy 30 psig, to adsorb nitrogen and moisture from air, and to concentrate oxygen in air to approximately 80 to 95 percent oxygen, as in the air feed to an ozone generator.
A tank used in connection with a water distribution system, for a single household, for several houses, or for a portion of a larger water system, which is airtight and holds both air and water, and in which the air is compressed and the pressure so created is transmitted to the water.
Any water treatment step performed prior to the primary treatment process, such as filtration prior to deionization.
An epidemiological study which examines the relationship between diseases and exposures as they exist in a defined population at a particular point in time.
The responsibility for ensuring that a law is implemented, and the authority to enforce a law and related regulations.

A primacy agency has the primary responsibility for administrating and enforcing regulations such as "primary enforcement responsibility" as defined in the Safe Drinking Water Act.

An instrument which measures (senses) a physical condition or variable of interest.

Floats and thermocouples are examples of primary elements.

Also called a sensor.

1.nThe first major treatment in a waste water treatment works, consisting usually of sedimentation. 2. The removal of a substantial amount of suspended matter but little or no colloidal and dissolved matter.
The action of filling a pump casing with water to remove the air.

Most pumps must be primed before startup or they will not pump any water.

A doctrine of water law that allocates the right to use water on a first-come, first-serve basis.
A physical or chemical quantity which is usually measured and controlled in the operation of a water treatment plant or an industrial plant.
Water used in a manufacturing or treatment process or in the actual product manufactured.

Examples would be water used for washing, rinsing, direct contact, cooling, solution makeup, chemical reactions, and gas scrubbing in industrial and food processing operations.

In many cases, water is specifically treated to produce the quality of water needed for the process.

The practice of using some of the product water from the first stage of RO treatment as feedwater for the second stage.
Water that has been through the total treatment process and meets the quality standards required for the use to which the water will be put.

Product water is called by different names, depending upon which treatment process it has gone through:

"Centrate" from a centrifuge "Distillate" from a distiller "Filtrate" from a filter unit "Finished" from a municipal treatment plant "Deionized" from an cation and anion exchange system "Softened" from a softener unit "Permeate" from a reverse osmosis or ultrafiltration unit.

That amount of product water available from the full-open dispensing outlet of a water treatment unit for a specified period of time.
The amount (gallons or liters) of product water the system produces per minute or (especially for reverse osmosis) per 24 hour period.
A drawing showing elevation plotted against distance, such as the vertical section or side view of a pipeline.
An epidemiological study which examines the development of disease in a group of persons determined to be presently free of the disease.
A group of enzymes that is effective in breaking down proteins into smaller, less complex molecules.
An original water treatment equipment unit on which a specific equipment line is modeled.
Microscopic, usually single-celled microorganisms which live in water and are relatively larger in comparison to other microbes.

Protozoa are higher on the food chain than the bacteria that they eat. Many protozoa are parasitic.

Singular form: protozoan or protozoon.

A blue paste or liquid (often on a paper like carbon paper) used to show a contact area.

Used to determine if gate valve seats fit properly.

Pressure swing adsorption.
Pounds per square inch.
Pounds per square inch gauge.
A system for the provision to the public of piped water for human consumption, if such system has at least 15 service connections or regularly serves an average of at least 25 individuals daily at least 60 days out of the year.

Such term includes: 1. any collection, treatment, storage, and distribution facilities under control of the operator of such system and used primarily in connection with such system; and 2. any collection or pretreatment storage facilities not under such control which are used primarily in connection with such system. A public water system is either a "community water system" or a "noncommunity water system."

Porous volcanic rock.
A stable, natural, glassy aluminum silicate mineral from volcanic ash which is used as a water treatment filtration medium.

See Also: Aluminum Silicate Aluminum Silicate Aluminum Silicate

Mechanical devices installed in sewer or water systems or other liquid-carrying pipelines that move the liquids to a higher level.
The vertical distance in feet from the center line of the pump discharge to the level of the free pool while water is being drawn from the pool.
This term has no real meaning unless the word "pure" is defined by some standard.

The Water Quality Association Promotion Guidelines recommend against the use of the words "Pure Water" in advertising unless the meaning of "pure" is very clearly explained for the consumer. The capacity of the words "pure", "purification," "purifier" and other derivatives of the word "pure" to mislead consumers is considerable.

In an absolute sense, all available water contains an amount of some substances in addition to H2O.

The context that is meant by use of these words should always be clearly and accurately defined.

Water produced from water meeting the USEPA standards for safe drinking water through treatment by distillation, reverse osmosis, deionization, or other processes and which meets United States Pharmacopoeia (USP) purity standards for "purified water" can be labeled as "purified."

These standards regulate pH, chloride, sulfate, ammonia, calcium, carbon dioxide, heavy metals, oxidizable substances, total solids, and bacteria.

If water meeting the USP standard has been distilled, it can alternatively be labeled "distilled water."

An agency or person that supplies water (usually potable water).
Biological decomposition of organic matter, with the production of ill-smelling and tasting products, associated with anaerobic (no oxygen present) conditions.
Polyvinyl chloride.
Iron disulfide (FeS2 ). A common mineral that has a bright metallic luster and a brass-yellow color.

Also called iron pyrite or fool's gold.

Substances (often of unknown origin) that produce fever when introduced into the human body.

Being chemically and physically stable, pyrogens are not necessarily destroyed by conditions that kill bacteria.

(MnO2) Manganese dioxide mineral ore which is sold under several trade names. It is the most important ore of manganese and is usually of an iron-black or dark steel-gray color with a metallic luster.

Pyrolusite has very effective capacity as an iron, manganese, and/or hydrogen sulfide sacrificial filter medium but is very heavy, requiring high backwash rates of 20 gallons or more per square foot of media surface area.