Alternative and Innovative (Wastewater Treatment System)
AA— Accountable Area; Adverse Action; Advices of Allowance; Assistant
Administrator; Associate Administrator; Atomic Absorption
AAEE— American Academy of Environmental Engineers
AANWR— Alaskan Arctic National Wildlife Refuge
AAP— Asbestos Action Program
AAPCO— American Association of Pesticide Control Officials
AARC— Alliance for Acid Rain Control
ABEL— EPA’s computer model for analyzing a violator’s ability to pay a civil
ABES— Alliance for Balanced Environmental Solutions
AC— Actual Commitment. Advisory Circular
A&C— Abatement and Control
ACA— American Conservation Association
ACBM— Asbestos-Containing Building Material
ACE— Alliance for Clean Energy
ACE— Any Credible Evidence
ACEEE— American Council for an Energy Efficient Economy
ACFM— Actual Cubic Feet Per Minute
ACL— Alternate Concentration Limit. Analytical Chemistry Laboratory
ACM— Asbestos-Containing Material
ACP— Agriculture Control Program (Water Quality Management); ACP— Air
ACQUIRE— Aquatic Information Retrieval
ACQR— Air Quality Control Region
ACS— American Chemical Society
ACTS— Asbestos Contractor Tracking System
ACWA— American Clean Water Association
ACWM— Asbestos-Containing Waste Material
ADABA— Acceptable Data Base
ADB— Applications Data Base
ADI— Acceptable Daily Intake
ADP— AHERA Designated Person; Automated Data Processing
ADQ— Audits of Data Quality
ADR— Alternate Dispute Resolution
ADSS— Air Data Screening System
ADT— Average Daily Traffic
AEA— Atomic Energy Act
AEC— Associate Enforcement Counsels
AEE— Alliance for Environmental Education
AEERL— Air and Energy Engineering Research Laboratory
AEM— Acoustic Emission Monitoring
AERE— Association of Environmental and Resource Economists
AES— Auger Electron Spectrometry
AFA— American Forestry Association
AFCA— Area Fuel Consumption Allocation
AFCEE—Air Force Center for Environmental Excellence
AFS— AIRS Facility Subsystem
AFUG— AIRS Facility Users Group
AH— Allowance Holders
AHERA— Asbestos Hazard Emergency Response Act
AHU— Air Handling Unit
AI— Active Ingredient
AIC— Active to Inert Conversion
AICUZ— Air Installation Compatible Use Zones
AID— Agency for International Development
AIHC— American Industrial Health Council
AIP— Auto Ignition Point
AIRMON— Atmospheric Integrated Research Monitoring Network
AIRS— Aerometric Information Retrieval System
AL— Acceptable Level
ALA— Delta-Aminolevulinic Acid
ALA-O— Delta-Aminolevulinic Acid Dehydrates
ALAPO— Association of Local Air Pollution Control Officers
ALARA— As Low As Reasonably Achievable
ALC— Application Limiting Constituent
ALJ— Administrative Law Judge
ALMS— Atomic Line Molecular Spectroscopy
ALR— Action Leakage Rate
AMBIENS— Atmospheric Mass Balance of Industrially Emitted and Natural Sulfur
AMOS— Air Management Oversight System
AMPS— Automatic Mapping and Planning System
AMSA— Association of Metropolitan Sewer Agencies
ANC— Acid Neutralizing Capacity
ANPR— Advance Notice of Proposed Rulemaking
ANRHRD— Air, Noise, & Radiation Health Research Division/ORD
ANSS— American Nature Study Society
AOAC— Association of Official Analytical Chemists
AOC— Abnormal Operating Conditions
AOD— Argon-Oxygen Decarbonization
AOML— Atlantic Oceanographic and Meteorological Laboratory
AP— Accounting Point
APA— Administrative Procedures Act
APCA— Air Pollution Control Association
APCD— Air Pollution Control District
APDS— Automated Procurement Documentation System
APHA— American Public Health Association
APRAC— Urban Diffusion Model for Carbon Monoxide from Motor Vehicle Traffic
APTI— Air Pollution Training Institute
APWA— American Public Works Association
AQ-7— Non-reactive Pollutant Modelling
AQCCT— Air-Quality Criteria and Control Techniques
AQCP— Air Quality Control Program
AQCR— Air-Quality Control Region
AQD— Air-Quality Digest
AQDHS— Air-Quality Data Handling System
AQDM— Air-Quality Display Model
AQMA— Air-Quality Maintenance Area
AQMD— Air Quality Management District
AQMP— Air-Quality Maintenance Plan; Air-Quality Management Plan
AQSM— Air-Quality Simulation Model
AQTAD— Air-Quality Technical Assistance Demonstration
AR— Administrative Record
A&R— Air and Radiation
ARA— Assistant Regional Administrator; Associate Regional Administrator
ARAC— Acid Rain Advisory Committee
ARAR— Applicable or Relevant and Appropriate Standards, Limitations, Criteria,
ARB— Air Resources Board
ARC— Agency Ranking Committee
ARCC— American Rivers Conservation Council
ARCS— Alternative Remedial Contract Strategy
ARG— American Resources Group
ARIP— Accidental Release Information Program
ARL— Air Resources Laboratory
ARM— Air Resources Management
ARNEWS— Acid Rain National Early Warning Systems
ARO— Alternate Regulatory Option
ARRP— Acid Rain Research Program
ARRPA— Air Resources Regional Pollution Assessment Model
ARS— Agricultural Research Service
ARZ— Auto Restricted Zone
AS— Area Source
ASC— Area Source Category
ASDWA— Association of State Drinking Water Administrators
ASHAA— Asbestos in Schools Hazard Abatement Act
ASHRAE— American Society of Heating, Refrigerating, and Air-Conditioning
ASIWCPA— Association of State and Interstate Water Pollution Control
ASMDHS— Airshed Model Data Handling System
ASRL— Atmospheric Sciences Research Laboratory
AST— Advanced Secondary (Wastewater) Treatment
ASTHO— Association of State and Territorial Health Officers
ASTM— American Society for Testing and Materials
ASTSWMO— Association of State and Territorial Solid Waste Management Officials
AT— Advanced Treatment. Alpha Track Detection
ATERIS— Air Toxics Exposure and Risk Information System
ATS— Action Tracking System; Allowance Tracking System
ATSDR— Agency for Toxic Substances and Disease Registry
ATTF— Air Toxics Task Force
AUSM— Advanced Utility Simulation Model
A/WPR— Air/Water Pollution Report
AWRA— American Water Resources Association
AWT— Advanced Wastewater Treatment
AWWA— American Water Works Association
AWWARF— American Water Works Association Research Foundation.
FILTER RATING: Filter rating meaning that 99.9 percent of essentially all
of the particles larger than a specified micron rating will be trapped on or
within the filter.
process of substance actually penetrating into the structure of another
substance. This is different from adsorption in which one substances adheres to
the surface of another.
Neutralizing Capacity— Measure of ability of a base (e.g. water or soil) to
resist changes in pH.
condition of water or soil which contains a sufficient amount of acid
substances to lower the pH below 7.0.
Regulatory levels recommended by EPA for enforcement by FDA and USDA when
pesticide residues occur in food or feed commodities for reasons other than the
direct application of the pesticide. As opposed to "tolerances” which are
established for residues occurring as a direct result of proper usage, action
levels are set for inadvertent residues resulting from previous legal use or
the Superfund program, the existence of a contaminant concentration in the
environment high enough to warrant action or trigger a response under SARA and
the National Oil and Hazardous Substances Contingency Plan. The term is also
used in other regulatory programs.
CARBON: A form of elemental carbon whose particles have large surface area
with adsorptive qualities, primarily used to remove chlorine, objectionable
tastes and odors and numerous toxic organic compounds from water. Produced by
heating carbonaceous substances, bituminous coal or cellulose-based substances
such as wood or coconut shell, to 700 degrees Centigrade or less in the absence
of air to form a carbonized char and then activating or oxidizing at 800 to
1000 degrees Centigrade with oxidizing gases such as carbon dioxide or steam to
form pores, thus creating a highly porous adsorbent material.
CARBON BLOCK: a blend of fine activated carbon, water and a suitable
binders(such as polyethylene or similar material) that is mixed and molded and
hardened or extruded to a cartridge filter of any size and shape. Occasionally
specialized media are added along with activated carbon to provide customized
performances of specific contaminants such as lead.
A chemical added to a pesticide to increase its activity.
INGREDIENT: In any pesticide product, the component that kills, or
otherwise controls, target pests. Pesticides are regulated primarily on the
basis of active ingredients.
EXPOSURE: A single exposure to a toxic substance which may result in
severe biological harm or death. Acute exposures are usually characterized as
lasting no longer than a day, as compared to longer, continuing exposure over a
period of time.
ACUTE TOXICITY: The ability of a substance to cause severe biological harm
or death soon after a single exposure or dose. Also, any poisonous effect
resulting from a single short-term exposure to a toxic substance.
ADSORPTION: Removal of a pollutant from air or water by collecting the
pollutant on the surface of a solid material; e.g., an advanced method of
treating waste in which activated carbon removes organic matter from
TREATMENT: A level of wastewater treatment more stringent than secondary
treatment; requires an 85-percent reduction in conventional pollutant
concentration or a significant reduction in non-conventional pollutants.
Sometimes called tertiary treatment.
ADVANCED WASTEWATER TREATMENT: Any treatment of sewage that goes beyond
the secondary or biological water treatment stage and includes the removal of
nutrients such as phosphorus and nitrogen and a high percentage of suspended
AERATION: A process which promotes biological degradation of organic
matter in water. The process may be passive (as when waste is exposed to air),
or active (as when a mixing or bubbling device introduces the air). Iron,
manganese, etc are targets of this process.
TANK: A chamber used to inject air into water.
or processes that require, or are not destroyed by, the presence of oxygen.
AEROBIC TREATMENT: Process by which microbes decompose complex organic
compounds in the presence of oxygen and use the liberated energy for
reproduction and growth. (Such processes include extended aeration, trickling
filtration, and rotating biological contactors.)
BINDING: Situation where air enters the filter media and harms both the
filtration and backwash processes.
AIR CHANGES PER HOUR(ACH): The movement of a volume of air in a given
period of time; if a bottling cleanroom, for example, has one air change per
hour, it means that the air in the cleanroom will be replaced in a one-hour
GAP: Open vertical gap or empty space that separates drinking water supply
to be protected from another water system in a treatment plant or other
location. The open gap protects the drinking water from contamination by
backflow or back siphonage. Commonly found in home-use reverse osmosis systems.
SPARGING: Injecting air or oxygen into an aquifer to strip or flush
volatile contaminants as air bubbles up through The ground water and is
captured by a vapor extraction system.
AIR STRIPPING: A treatment system that removes volatile organic compounds
(VOCs) from contaminated ground water or surface water by forcing an airstream
through the water and causing the compounds to evaporate.
rootless plants that grow in sunlit waters in proportion to the amount of
available nutrients. They can affect water quality adversely by lowering the
dissolved oxygen in the water. They are food for fish and small aquatic
ALGAL BLOOMS: Sudden spurts of algal growth, which can affect water
quality adversely and indicate potentially hazardous changes in local water
ALGICIDE: Substance or chemical used specifically to kill or control
ALIQUOT: A measured portion of a sample taken for analysis. One or more
aliquots make up a sample.
ALKALINITY: A measurement of the quantity of chemicals present in water
which can neutralize acids. These include carbon dioxide, bicarbonate,
carbonate and hydroxides. pH conditions which exceed 7.0.
ALUM: See aluminum sulfate.
ALUMINUM SULFATE: An aluminum salt commonly used as a flocculent by
municipal water treatment facilities.
AMPHOTERIC: A substance, such as aluminum, capable of acting as either an
acid or base.
condition in which there is no air or no available free oxygen. Sometimes
relates to microbes which can exist without oxygen.
ANIONS: See ion.
geological formation containing water; one that supplies water for wells,
Board of Assistance Appeals
BAC— Bioremediation Action Committee; Biotechnology Advisory Committee
BACM— Best Available Control Measures
BACT— Best Available Control Technology
BADT— Best Available Demonstrated Technology
BAF— Bioaccumulation Factor
BAP— Benefits Analysis Program
BART— Best Available Retrofit Technology
BASIS— Battelle’s Automated Search Information System
BAT— Best Available Technology
BATEA— Best Available Treatment Economically Achievable
BCT— Best Control Technology
BCPCT— Best Conventional Pollutant Control Technology
BDAT— Best Demonstrated Achievable Technology
BDCT— Best Demonstrated Control Technology
BDT— Best Demonstrated Technology
BEJ— Best Engineering Judgement. Best Expert Judgment
BF— Bonafide Notice of Intent to Manufacture or Import (IMD/OTS)
BID— Background Information Document. Buoyancy Induced Dispersion
BIOPLUME— Model to Predict the Maximum Extent of Existing Plumes
BMP— Best Management Practice(s)
BMR— Baseline Monitoring Report
BO— Budget Obligations
BOA— Basic Ordering Agreement (Contracts)
BOD— Biochemical Oxygen Demand. Biological Oxygen Demand
BOF— Basic Oxygen Furnace
BOP— Basic Oxygen Process
BOPF— Basic Oxygen Process Furnace
BOYSNC— Beginning of Year Significant Non-Compliers
BP— Boiling Point
BPJ— Best Professional Judgment
BPT— Best Practicable Technology. Pest Practicable Treatment
BPWTT— Best Practical Wastewater Treatment Technology
BRI— Building-Related Illness
BRS— Bibliographic Retrieval Service
BSI— British Standards Institute
BSO— Benzene Soluble Organics
BTZ— Below the Treatment Zone
BUN— Blood Urea Nitrogen
of a solution's flow through a system(i.e. water softener). Often used as a
cleansing mechanism in sand and dual media filters.
of a class of microscopic plants having round, rod-like spiral or filamentous
single cell or noncellular bodies, often aggregated into colonies or mobile by
means of flagella. Living in soil, water, organic matter or the bodies of
plants and animals and being autotrophic(self-generative), saprophytic(digests
chemicals already in their environment) or parasitic.
capable of inhibiting or destroying bacteria. Function is known as
capable of reducing the rate of bacterial growth. Sometimes confused with
used in reference to cartridge filters, refers to chemicals used to hold, or
bind, short fibers together in a filter. Also may refer to various chemicals
used to bind polymeric compounds in products such as plastic bottles.
aggregation of active, multi-layered microbes found on surfaces and in
particular inside tubing and pipes. May be difficult to remove by chemical
means due to multiple layers and lack of fluid dynamics at surfaces where it
fouling or plugging of pores in a membrane, usually by a gel-like substance.
BRACKISH WATER: Water containing between 1000 and 15000 mg/l of dissolved
solids is generally considered to be brackish.
first appearance in the effluent of an adsorbate of interest under specified
SALT BRIDGING): The caking of salts in a dry water softener tank which
causes failure of the liquid or brine beneath the dry salt to become saturated.
The net result of bridging is insufficient salt to properly regenerate the resin.
BRINE (same as Reject Water): One of two streams of fluids generated by a
Distiller or Reverse Osmosis unit. It contains the impurities removed from the
feed water. Characteristically 30,000 to 300,000 ppm.
substance which tends to produce cancer in an organism.
CATIONS: See ion.
CELLULASE: An enzyme which causes the decomposition of cellulose.
CELLULOSE ACETATE: A synthetic polymer derived from naturally occurring
cellulose and widely used in the fabrication of membranes. The polymers used
for reverse osmosis membranes may be diacetate, triacetate or blends of these
PUMP: A pump containing a rotation impeller or rotating vanes mounted on a
shaft in a casing and turned by a power source. The rotating impeller uses
centrifugal force to deliver water in a steady steam.
mechanical device that uses centrifugal or rotational forces to separate solids
greater flow of liquid through passages of lower resistance which can occur in
fixed beds or columns of particles(carbon, birm, etc.) due to non-uniform
packing, irregular sizes and shapes of the particles, gas pockets, wall effects
and other causes.
CHLORAMINES: Chemical complexes formed from the reaction between ammonia
and chlorine. They are presently being used to disinfect municipal water
supplies because unlike chlorine, they don't combine with organics in the water
to form potentially dangerous carcinogens such as trihalomethanes (THM).
Retains its bactericidal qualities for a longer time than does free chlorine.
Chloramines can exist in three forms, the proportions of which depend on the
physical and chemical properties of the water: Monochloramine; Dichloramine;
Nitrogen Trichloride. Water containing chloramines must not be used for fish or
kidney dialysis applications.
very toxic biocide. A halogen element isolated as a heavy irritating
greenish-yellow gas of pungent odor used especially as a bleach, oxidizing
agent and a disinfectant in water purification.
CHLORINATED HYDROCARBONS: A group of organic chemicals formed by reacting
petroleum derived chemicals with chlorine. Such chemicals include pesticides
(insecticides) and herbicides and are frequently potent carcinogens.
COAGULANT: A chemical which causes dispersed colloidal particles to become
destabilized, thereby aiding in their removal during municipal water treatment.
Aluminum and iron salts are commonly used for this purpose.
COAGULATION: A practice common in municipal water treatment in which a chemical
(coagulant), most commonly alum, is added to water in order to destabilize
colloidal particles by neutralization of their electrical charges. Coagulation
is used, together with flocculation, as a process for colloid removal.
COLLOIDAL MINERAL/COLLOID: Undissolved, sub micron-sized suspended
particles which are well dispersed in a solution and will not readily settle
out on standing. Most colloidal minerals are held in suspension by their tiny
size and/or a static electrical charge. Many colloidal minerals claim to be
organic due to the fact that they come from prehistoric mineral deposits such
as humic shale and that some of the minerals are bound to carbon.
COMPACTION: The undesirable physical compression of a reverse osmosis or
ultrafiltration membrane which results in reduced flux rates. The phenomenon is
accelerated at higher temperatures and pressures.
portion of a feed stream that retains the ions, organics and suspended
particles that were rejected during the cross flow filtration or purification
process. Associated with water cooled distillers and reverse osmosis systems.
obtained through distillation by evaporation and subsequent condensation.
CONDUCTIVITY: A measure of the ability of an aqueous substance to transmit
an electric current. The conductivity imparted to water by dissolved solids is
a function of both the amount and composition of the salts and the temperature
of the water.
DEIONIZATION: Removal of ions from water by exchange with other ions
associated with fixed charges on a resin. 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. This process is also called demineralization by ion exchange.
process of removing minerals from water e.g. deionization, reverse osmosis and
removal of dissolved inorganic solids(salts) from a solution such as water to
produce a liquid which is free of dissolved salts. Desalination is typically accomplished
by distillation, reverse osmosis or electrodialysis. A common source water may
DIALYSIS DEMENTIA: A severe, often fatal encephalopathy which has been
attributed to accumulation in the brain of aluminum from dialysate prepared with
inadequately purified water. May include consumption of tap water with high
levels of alum used in most municipal water treatment processes.
DISINFECTION: A process for the destruction of bacteria. The process may
be physical, as with heat or ultraviolet irradiation, or chemical, as with
SOLIDS(ALSO TOTAL DISSOLVED SOLIDS-TDS): Includes colloidal and suspended
particles at sizes far less than one micron in diameter. Associated with
evaporation process such as distillation.
from boiling water is condensed on a cool surface, collected and stored. Most
contaminants do not vaporize and therefore do not pass to the condensate.
Removes nearly 100 percent of salts and those organics that do not have a
vaporizing temperature near or below that of water. Usually combined with
carbon filtration to remove balance of remaining organics with vaporization
temperatures below that of water.
DISTILLED WATER: Water which has been purified by passing through an
evaporation, condensation cycle; it generally contains less than 5 ppm of
output stream exiting the system - often the waste stream.
EMPTY BED CONTACT TIME: A measurement of the duration of contact between
water and the media through which it is flowing, typically used in reference to
ENDOTOXIN: Bacterial lipopolysaccharide, a substance released from the
cell walls of gram-negative bacteria when the organism is broken down.
IRON: Small solid iron particles containing trivalent iron, usually as
gelatinous ferric hydroxide or ferric oxide, which are suspended in water and
visible as "rusty water". Ferric iron can normally be removed by
filtration. Also called "precipitated iron".
IRON: A divalent iron ion, usually as ferrous bicarbonate which, when
dissolved in water, produces a clear solution. It is usually removed by cation
exchange water softening. Also called "clear water" iron.
FEED WATER: Water under pressure entering a purification system or an
individual piece of purification equipment, such as an ultra filter, distiller
or reverse osmosis system.
portion of the feed stream that has passed through the membrane or filtering
which, when added to water, causes particles to coagulate into larger, settle
able groupings. Aluminum compounds are common catalysts in this process.
FLOW VELOCITY: A quantitative expression of the rate of linear motion at
which water passes through a pipe or conduit.
FLUIDIZATION: A process by which particles are suspended by an upward flow
of liquid, such as may occur during back washing of ion exchange resin or
FLUORIDE: A salt of hydrofluoric acid which may occur naturally in water
supplies or be added by municipal processes for the prevention of dental
caries. Fluoride is considered toxic in most medical settings and has been
implicated with a wide range of physiological disorders including renal bone
FLUX/FLUX RATE: The rate per unit of area at which water passes through a
semi-permeable membrane, such as those used for ultrafiltration or reverse
FOULING: The deposition of insoluble materials, such as bacteria,
colloids, oxides and water-borne debris, onto the surface of a media such as
water softening resins, reverse osmosis or ultrafiltration membrane. Fouling is
associated with decreased flux rates and may also reduce the rejection rates of
reverse osmosis membranes.
FULVIC ACIDS: Acidic substances which are found in humic (organic) soils
and which may become suspended in water. A component in the production of
FUNGUS: A parasitic plant which produces no chlorophyll and is dependent
on other life forms for its existence.
GLAUCONITE SAND: A mineral which is frequently used in depth filters.
per gallon. Equivalent to 17.1 milligrams/liter of calcium carbonate.
HARDNESS: The amount of calcium and magnesium in the water in grains per
gallon, (expressed as calcium carbonate). This level is important to control
during distillation or reverse osmosis processes to prevent scaling. Each grain
is equal to 17.1 ppm of calcium and magnesium (expressed as calcium carbonate).
constitutes truly "hard" water is subject to much debate and
controversy. Proponents of water softening systems tend to call water
"hard" which contains between 3 and 10 grains of hardness.
Unfortunately, this definition is supported by the American Society of
Agricultural Engineers and the Water Quality Association, major supporters of
the water softening industry.
with 10 grains of hardness is regularly used by consumers with little or no
adverse affect on plumbing or other household functions. Water which approaches
15 to 20 grains is more in line with situations which require water softening or
conditioning. Water with 3 grains of hardness and is termed "moderately
hard" by these organizations is typically found in surface and spring
water sources, far removed from what one would consider hard water sources.
METALS: Metals having a high density or specific gravity. A generic term
used to classify contaminants such as cadmium, lead and mercury. These
contaminants can damage living things even at low concentrations and tend to
accumulate n the food chain.
HOMOGENEOUS MEMBRANES: See membranes.
SULFIDE: A toxic gas that is detectable by a strong "rotten egg"
odor. Associated with high levels of bacterial decay. Commonly found together
with iron and manganese contaminants.
CYCLE: The term used to describe how water travels through the environment
by evaporation, condensation and precipitation. Identical process is observed
in steam distillation systems.
HYDROLYSIS: A chemical process resulting from reactions with water;
frequently used in reference to the breakdown of polymers.
HYDROPHILIC: Pertaining to a substance which readily absorbs water
HYDROPHOBIC: Pertaining to a substance which does not readily absorb water
ION: An atom or molecule having either a positive or negative electrical
charge. Positively charged ions are referred to as cations and ions having a
negative charge are termed anions.
ION EXCHANGE: A process by which certain ionized chemicals present in
water are replaced with other ionized chemicals temporarily attached to resin
particles. The exchange process is made only for ions having the same charge.
very common element often present in ground water in amounts ranging from 0.01
to 10.0 ppm(mg/l). Iron may be found in three forms: in soluble forms such as
in ferrous bicarbonate; bound with a soluble organic compound; or as suspended
ferric iron particles. Iron above 0.3 mg/l is objectionable to water because of
staining of laundry and plumbing fixtures.
BACTERIA: Bacteria which thrive on iron and are able to actually use
ferrous iron(as found in water or steel pipes) in their metabolic processes to
incorporate ferric iron in their cell structure and to deposit gelatinous
ferric hydroxide iron compounds in their life processes.
turbulent fluid flow. Associated with fluid dynamics and designs of fluid
tubing and pipelines.
SATURATION INDEX: A calculated number used to predict the calcium
carbonate(CaCO3) stability of a water; 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 calcium carbonate is
saturation index = pH - pH, where pH = actual pH of the water, and pH, = pH at
which the water having the same alkalinity and calcium content is just
saturated with calcium carbonate.
LIGNIN: A polysaccharide found in the cell walls of plants; a breakdown
product of decaying vegetation which may be present in surface water supplies.
MEMBRANES: Thin films constructed of cellulosic or synthetic materials
which are designed to provide selective transport of solutes. Widely used for
hemodialysis, micro filtration, ultrafiltration and reverse osmosis, membranes
may be either homogeneous or asymmetric. Homogeneous membranes have a uniform
structure or cross-section while asymmetric membranes have a dense
"skin" which overlays a porous substructure.
METHEMOGLOBINEMIA: The presence in blood of methemoglobin, a substance
related to normal oxyhemoglobin but having no oxygen-carrying capabilities and
induced by exposure of blood to certain toxic chemicals, such as nitrites.
FILTRATION: The separation or removal from a liquid of particulates and
micro-organisms in the size range of 0.1 to 2 microns in diameter.
MICRON: A unit of linear measure. It is one millionth of a meter, or one
thousandth of a millimeter. The smallest particle than can be distinguished by
the naked eye would be about 40 microns across.
RATING: A measurement applied to filters or filter media to indicate the
particle size at which a substantial percentage of suspended solids above that
size will be removed. As used in the water treatment industry standards, this
may be an absolute rating or a nominal rating.
MICRO POROUS: In the context of water purification, membranes having an
average pore size which is between 0.1 and 1.0 microns in diameter.
PER SQUARE CENTIMETER: A unit of measurement of intensity and retention or
contact time in the operation of ultraviolet(U/V) systems.
per liter. A measure of concentration of a dissolved substance. A concentration
of one mg/l means that one milligram of a substance is dissolved in each liter
of water. For practical purposes, this unit is equal to parts per million(ppm)
since one liter of water is equal in weight to one million milligrams. Thus, a
liter of water containing 10 milligrams of calcium has 10 parts of calcium per
one million parts of water or 10 parts per million(10 ppm).
millionth of an ohm. The unit of measurement for testing the electrical
resistance of water to determine its purity. The closer water comes to absolute
purity, the greater its resistance to conduction of an electrical current.
Absolute pure water has a specific resistance over 18 million ohms(megohms)
across one centimeter of water at a temperature of 78 degrees Fahrenheit.
MILLILITERS/MINUTE: A common measurement for the flow rate of small RO
systems. Usually measured with a graduate cylinder. One thousandth of a liter
per minute. Milliliters/min x.38 = gal/day.
BED: The intermix of two or more filter or ion exchange products in the
same vessel during a service run. The most common use is in ion exchange
systems having a 40/60 percent cation to anion resin bed such as that for a
deionization polisher system. In filtration, there may be an intermix of two or
more media in a single tank with each stratified into separate layers.
MONOVALENT ION: A cation or anion having a single electrical charge.
Tertiary Butyl Ether): A volatile organic chemical(VOC) used as an
octane-enhancing lead substitute and more recently as an oxygenating agent in
gasoline to reduce carbon monoxide emissions from automobiles. MTBE is
volatile, flammable and highly soluble in water.
refueling and gasoline production, MTBE is volatilized to the atmosphere where
it dissolves into the atmospheric moisture and returns to earth as
precipitation, polluting our water supplies. Since MTBE does not adsorb well
with organic matter in soils it is easily washed away. In surface water, MTBE
volatilizes into the air while in ground water, MTBE persists and moves freely.
MTBE occurrences in ground water above 40 ppb have so far been attributed to
point source contamination such as underground gasoline tank leaks, overflows,
has tentatively classified MTBE as a potential human carcinogen.
membrane treatment process which falls between reverse osmosis and
ultrafiltration on the filtration/separation spectrum. The nanofiltration
process can pass more water at lower pressure operations than reverse osmosis,
can remove particles in the 300 to 1,000 molecular weight range such as humic
acid and organic color bodies present in water, and can reject
selected(typically polyvalent) salts. Nanofiltration may be used for selective
removal of hardness ions in a process known as membrane softening.
addition of either an acid to a base or a base to an acid to produce a more
nearly neutral solution. The use of alkaline or basic materials to neutralize
acidity of some water is common practice in water processing to prevent
corrosion of metallic home plumbing.
NITRATE: An anion comprised of one nitrogen atom and three oxygen atoms.
Nitrates are considered toxic in hemodialysis water and are also harmful to
infants when consumed orally.
FILTER RATING: Filter rating indicating the approximate size particle, the
majority of which will not pass through the filter. It is generally interpreted
as meaning that 85 percent of the particles of the size equal to the nominal
filter rating will be retained by the filter.
PRESSURE: The manufacturer's specified range of pressure expressed in
pounds per square inch(psi) within which a water processing device or water
system is designed to function.
TEMPERATURE: The manufacturer's recommend feed water or inlet water
temperature for a water treatment system.
OSMOSIS: The natural tendency of water to pass through a semipermeable
membrane, so as to equalize concentrations on both sides of the membrane.
OSMOTIC PRESSURE: The force (pressure) resulting when two liquids having
different solute concentrations are separated by a semi-permeable membrane. For
every 100 ppm, an osmotic "back pressure" of 1 psi is generated and
this "back pressure" must be overcome in the reverse osmosis process.
OSTEODYSTROPHY: Abnormal bone development which, in renal patients, may be
attributed to parathyroid gland dysfunction and is characterized by high serum
phosphorus and alkaline phosphates and low serum calcium levels.
OSTEOMALACIA: A softening of bone due to an accumulation of osteoid and
reduced mineralization which may cause fractures with minimal stress.
OSTEOPOROSIS: Demineralization of bone which may cause fractures with
OXIDANTS(OXIDIZING AGENTS): Chemicals which provide oxygen and accept an
electron in an oxidation-reduction reaction. Free chlorine and chloramines are
oxidants which are widely used for disinfection.
FILTERS: Filters that use a catalytic media, such as managanous oxides or
potassium permangenate, to oxidize iron, manganese and other impurities from
OZONE: An extremely active oxidizing agent and bacteriocide which consists
of three oxygen atoms. It is formed by the action of a high voltage electrical
field on oxygen or air(such as occurs during an electrical storm). Some degree
of ozone can also be produced by certain types of ultraviolet lamps.
some material to pass through.
PERMEATE: See product water.
PARTS PER MILLION (ppm): The standard measure of total dissolved solids.
Parts of dissolved material in one million parts of water. (eg. one pound of
mineral salts dissolved in a million pounds of water would be on part per
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. Alternatively, 1 psi = 6895 Pa = 6.895 kN/sq.m = 0.0703 kg/sq.cm.
that can cause disease in other organisms or in humans, animals and plants.
They may be bacteria, viruses or parasites and are found in sewage, in runoff
from animals and in water used for swimming. Fish and shellfish contaminated by
pathogens, or the contaminated water itself, can cause serious illness.
pH: The balance between the strength of the alkaline and acidic compounds
in water. At a pH of 7.0 acid strength and alkaline strength are equal, and the
water is neutral. Less than 7 is more acidic. Greater than 7 is more alkaline.
On a logarithmic scale of 1 to 14, it is the negative logarithm of hydrogen ion
PHENOLS: Weak aromatic acids which are indicative of industrial pollution
of water supplies. When combined with chlorine, they produce an objectionable
taste and odor.
POLYAMIDE: A synthetic polymer of the nylon family used in the fabrication
of reverse osmosis and ultrafiltration membranes.
chemical compound with many repeating structural units.
POLYSULFONE: A synthetic polymer used to fabricate reverse osmosis and
ultrafiltration membranes which are characterized by extreme thermal stability
and chemical resistance. Popular in dental waterline filtration systems.
POLYVALENT ION: A cation or anion having a multiple electrical charge.
POLYVINYL CHLORIDE: A thermoplastic piping material produced by the
polymerization of vinyl chloride.
opening in a membrane which allows certain components to pass through, but not
POTASSIUM PERMANGANATE: An oxidizing agent commonly used for the
regeneration of manganese green sand iron filters and occasionally used as a
per billion(equivalent to micrograms per liter)
per million(equivalent to milligrams per liter)
PRESSURE DROP: Sometimes referred to as "delta P", it is the
decrease in hydrostatic force (pressure) due to the effects of friction or
restrictions on a flowing liquid.
HEAD: 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
PRIORITY POLLUTANTS: Those pollutants that pose the most serious health
hazards determined by the EPA (Environmental Protection Agency).
PRODUCT WATER: The purified water stream from equipment, such as
distillation, reverse osmosis and ultra filter units.
per square inch(pressure)
PYROLOSIS: A breakdown process which occurs when organic matter is
subjected to elevated temperatures.
FLOW: The flow pattern in which water flows from the outside of a filter
element to the center core. For example, a replaceable particulate or carbon
cartridge filter unit.
RECOVERY(PERCENT RECOVERY): A measurement applied to distillation, reverse
osmosis and ultrafiltration equipment which characterizes the ratio of product
water to feed water flow rates. The measurement is descriptive of distillation
reverse osmosis or ultrafiltration equipment as a system and not of individual
membrane elements. Expressed as a , recovery is defined as: % Recovery = (Product
flow rate/Feed flow rate) x 100.
out using either an acid or alkali to remove the accumulated cations or anions,
respectively from a filtration media. At the same time, the cation exchanger
takes on hydrogen ions to restore themselves to the original hydrogen or
hydroxide form, respectively.
REJECTION(PERCENT REJECTION): A measure of the ability of a reverse
osmosis membrane to remove salts. Expressed as a percentage, rejection is
Rejection = (l-Product concentration/Feed concentration) x 100.
manufactured polymer beads used in the ion exchange process to remove dissolved
salts from water.
REVERSE OSMOSIS: A reversal of the natural phenomenon of osmosis brought
about by application of hydraulic pressure greater than the osmotic pressure in
water (containing dissolved solids) to cause the water molecules to flow
through the membrane away from the dissolved substances.
INDEX: A modification of the Langelier index used to calculate the degree
of calcium carbonate saturation and to predict the likelihood of scale
formation from a water supply.
SALT PASSAGE RATE: A measurement of the passage of salts through a reverse
osmosis membrane. Salt passage is related to rejection by: % Salt passage = 100
- % Rejection.
SCALING: Usually used in reference to distillation or reverse osmosis
equipment, scaling is the precipitation of sparingly soluble salts, such as
calcium carbonate, onto the surface of a distiller boiler or reverse osmosis
membrane. Scaling is associated with decreased flux and reduced reverse osmosis
rejection rates. Scaling also effects to a slight degree the efficiency of
SEDIMENTATION: The process by which solids are separated from water by
gravity and deposited on the bottom of a container or basin.
SEMIPERMEABLE: Descriptive of a material, such as a reverse osmosis or
ultrafiltration membrane, which allows the passage of some molecules and
prevents the passage of others.
SILT DENSITY INDEX: A measurement of the rate at which a 0.45 ~m filter
disc is plugged under standardized test conditions. Silt density index (SDI)
determinations are used to estimate the rate at which various water supplies
will cause fouling or pluggage of reverse osmosis or ultrafiltration membranes.
SOFT WATER: Water containing less than 1 grain per gallon dissolved
calcium and magnesium salts. Definition of where "softness” starts may vary
depending on individual viewpoints
particles in a solvent
SORBENT: See adsorption.
SPIRAL WOUND MEMBRANE: The most common practical configuration of
membranes for RO systems.
STERILIZATION: A physical or chemical process that reduces the number of
organisms to a safe predetermined level (see also disinfection).
SUPERFICIAL VELOCITY: A quantitative expression of the rate of linear
motion with which water passes through a vessel used to house particles, such
as ion exchange resin or carbon media.
SURGE TANK: A type of pressurized water storage vessel. Surge tanks
typically have large areas of stagnation that offer opportunistic bacteria a
favorable environment for multiplication. Commonly found in reverse osmosis
systems. Requires periodic sanitation to ensure control of bacterial growth.
SOLIDS: Includes settleable particles less than one micron in diameter.
of a group of water soluble, natural organic phenolic compounds that are
produced by metabolism in trees and plants and are part of the
degradation-resistant fulvic acid materials formed during the decomposition of
occur in water or in almost any location where large quantities of vegetation
have decayed. Tannins can impart a faintly yellowish to brown color to water.
Tannin molecules tend to form anions in water above pH 6 and can be treated with
anion exchange resins. Below pH 5, tannins are better treated with activated
THIN FILM COMPOSITE: A membrane made with a polyamide based polymer
consisting of three layers: a polyester support web, a micro porous
polysulfonic inter layer, and an ultrathin barrier coating on the top surface.
TITRATABLE ALKALINITY: The quantity of hydrogen ions (H+) which must be
added to a sample of alkaline water in order to establish a condition of
TOTAL DISSOLVED SOLIDS: The sum of all ions in a solution, often
approximated by means of electrical conductivity or resistivity measurements.
Total dissolved solids (TDS) measurements are commonly used to assess distiller
and reverse osmosis unit performance.
important to note that a test measuring the electrical conductivity of the
water sample provides only an estimate of the TDS present, as conductivity is
not precisely proportional to the weight of an ion and nonconductive substances
cannot be measured by electrical tests.
TOTAL ORGANIC CARBON: A measurement of the total mass of dissolved carbon
in a water sample, excluding that originating from carbon dioxide and
SUSPENDED SOLIDS: The particles which can be removed from a solution by
filtration, usually specified as the matter which will not pass through a 0.45
micron pore-diameter filter.
TURBIDITY: A measurement of the amount of suspended solids (colloids) in a
solution. Caused by stirred-up sediment, silt, clay, etc. Turbidity blocks
light rays and makes the water opaque. Turbidity is measured in nephelometric
water should not exceed 0.3 NTU. Turbidity cannot be directly equated to
suspended solids because white particles reflect more light than dark-colored
particles and many small particles will reflect more light than an equivalent
ULTRA FILTERS: A membrane based filtration system in which the pore sizes
range from 0.002 to 0.1 microns.
LIGHT: Radiation(light) having a wavelength shorter than 3900 angstroms,
the wavelength of visible light and longer than 100 angstroms, the wavelengths
of x-rays. This wvelength puts ultraviolet light at the invisible violet end of
the light spectrum. UV light is used as a disinfectant. Water treated by
ultraviolet light should be free from particulate materials or turbidity so as
to prevent micro-organisms from being shielded from the incident UV radiation.
VIRUS: The smallest infectious microorganism, made of RNA or DNA in a
protein shell and which grow only in other, living cells. They are 0.004 to 0.1
microns in size and about 100 times smaller than bacteria.
HAMMER: The shock wave or series of waves caused by the resistance of
inertia to an abrupt change of water flow through a water piping system. Water
hammer may produce an instantaneous pressure many times greater than the normal
pressure. For this reason, many building codes now require the installation of
a "water hammer arrestor" or accumulation device to absorb shock
waves and prevent damage to appliances such as washing machines as well as
water treatment components such as reverse osmosis membranes.
SOFTENER: A pressurized water treatment device in which hard water is
passed through a bed of cation exchange media for the purpose of exchanging
calcium and magnesium ions for sodium or potassium ions, thus producing a
"softened" water which is more desirable for laundering, bathing and
dish washing. This cation exchange process was originally called zeolite water
softening or the Permutit Process. Most modern water softeners use a sulfonated
bead form of styrene/divinylbenzene (DVB) cation resin.