> Greater than. DO
>5 mg/L would be read as:
DO greater than 5 mg/L.
< Less than. DO
<4 mg/L would be read as:
DO less than 4 mg/L.
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The
taking in or soaking up of one substance into the body of another by molecular or chemical action (as tree roots
absorb dissolved nutrients in the soil).
How closely an instrument measures the true or actual value of the process
variable being measured or sensed.
(1)
A substance that tends to lose an electron.
(2) A substance that dissolves in water with the formation of hydrogen ions.
(3) A substance containing hydrogen which may be replaced by metals to form salts.
(4) A substance that is corrosive.
The condition of water or soil which contains a sufficient amount of acid substances to lower the pH below 7.0
The
addition of an acid (usually nitric or sulfuric) to a sample to lower the pH below 2.0.
The purpose of acidification is to “fix” a sample so it won’t change until
it is analyzed.
The quantitative capacity of aqueous solutions to react with hydroxyl ions. It is measured by titration with a standard solution of a base to a specified end point. Usually expressed as milligrams per liter of calcium carbonate.
The material being removed by the adsorption process.
The material (activated carbon) that is responsible for removing the undesirable
substance in the adsorption process.
The
gathering of a gas, liquid, or dissolved substance on the surface or interface zone of another material.
Pumping
dry air (dew point -40 °
F) into a container to assist with the withdrawal of a liquid or to
force a liquefied gas such as chlorine out of a container.
A
treatment process used to remove dissolved gases and volatile substances from water.
Large volumes of air are bubbled through the water being treated to remove
(strip out) the dissolved gases and volatile substances.
Microscopic
plants which contain chlorophyll and live floating or suspended in water.
They also may be attached to structures, rocks or other submerged surfaces. Excess
algal growths can impart tastes and odors to potable water.
Algae produce oxygen during sunlit times and use oxygen during dark times. Their
biological activities appreciably affect the pH and dissolved oxygen of the water.
ALIPHATIC HYDROXYL ACIDS (AL-uh-FAT-ick)
Organic acids with carbon atoms arranged in branched or unbranched open chains
rather than in rings.
Portion of a sample. Often an equally divided portion of a sample.
Any of certain soluble salts, principally of sodium, potassium, magnesium and calcium, that have the property of combining with acids to form neutral salts and may be used in chemical water treatment processes.
The condition of water or soil which contains a sufficient amount of acid substances to lower the pH above 7.0
The
capacity of water to neutralize acids.
This capacity is caused by the water’s content of carbonate, bicarbonate,
hydroxide, and occasionally borate, silicate, and phosphate.
Alkalinity is express in milligrams per liter of equivalent calcium carbonate. Alkalinity
is not the same as pH because water does not have to be strongly basic (high pH) to have a high alkalinity. Alkalinity
is a measure of how much acid must be added to a liquid to lower the pH to 4.5 SU.
AMBIENT TEMPERATURE (AM-bee-ent)
Temperature of the surroundings. Temperature of the surrounding air (or other medium). For example, temperature of the room where a gas chlorinator is installed.
AMPEROMETRIC (am-PURR-o-MET-rick)
A
method of measurement that records electric current flowing or generated, rather than recording voltage. Amperometric
titration is a means of measuring concentrations of certain substances in water.
A means of measuring concentrations of certain substances in water (such
as strong oxidizers) based on the electric current that flows during a chemical reaction.
See TITRATION.
ANAEROBIC ENVIRONMENT (AN-air-O-bick)
A
condition in which “free” (atmospheric) or molecular (dissolved) oxygen is NOT present in the aquatic (water) environment.
The readout of an instrument by a pointer (or other indicating means) against
a dial or scale.
A device which conducts periodic or continuous measurement of some factor
such as chlorine, fluoride or turbidity.
Analyzers operate by any of several methods including photocells, conductivity
or complex instrumentation.
a unit of length equal to one-tenth of a nanometer or one - ten billionth
of a meter. One Angstrom is the approximate diameter of an atom.
A negatively charged ion in an electrolyte solution, attracted to the anode under the influence of a difference in electrical potential.
The positive terminal of an electrolytic cell.
Free
from the living germs of disease, fermentation or putrefaction.
Sterile.
The
smallest unit of a chemical element; composed of protons, neutrons and electrons.
Hydrogen, 1H, has one proton and one electron. Deuterium, 2H, has one proton and one neutron and one electron. Deuterium Oxide, D2O, is called heavy water.
Among the moderators that have been used in nuclear reactors are carbon in
the form of graphite, the light metal beryllium, heavy water (having a deuterium nucleus), and ordinary water.
[1]
A feature of some newer pH meters that recognize, automatically, the buffers (4.01, 7.00 and 10.01 [within a range of ± 0.5 SU]) required for calibration.
Microorganisms which use inorganic materials for energy and growth. They derive carbon for their cellular growth from inorganic sources such as carbon dioxide and bicarbonate. Nitrosomonas and Nitrobacter (see Nitrification process) are two such naturally occuring microorganisms. Heterotrophs use ORGANIC matter for energy and growth.
The number equal to the number of Carbon atoms in exactly 12 grams of pure 12C. This number is called Avogadro’s number. It is 6.02 x 1023.
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(1) A substance which takes up or accepts protons.
.
(2) A substance containing hydroxyl ions which reacts with an acid to form
a salt
or which may react with metals to form precipitates.
(3)
A substance which dissociates (separates) in aqueous solution to yield hydroxyl ions (OH ¯)
Bacteria are living organisms, microscopic in size, which usually consist of a single cell. Most bacteria use organic matter for their food and produce waste products as a result of their life processes.
(1) A
way of showing or measuring the effect of biological treatment on a
particular waste or substance, or
(2) A method of determining toxic effects of industrial wastes or other wastes by using live organisms such as fish for test organisms.
A term used to describe methods of evaluating or measuring the effects of toxic substances in effluents on aquatic organisms in receiving waters. There are two types of biomonitoring, the biosurvey and the bioassay.
An
accounting of the types and numbers of organisms naturally present in the receiving waters upstream and downstream
from plant effluents.
Comparisons are made between the aquatic organisms upstream and downstream
of the discharge.
A
bottle containing only dilution water or distilled water, but the sample being tested is not added. Tests
are frequently run on a sample and a blank and the differences compared.
Biochemical Oxygen Demand, BOD
Biochemical Oxygen Demand.
The rate at which organisms use the oxygen in water while stabilizing decomposable
organic matter under aerobic conditions.
In decomposition, organic matter serves as food for the bacteria and energy
results from its oxidation.
BOD measurements are used as a measure of the organic strength of wastes
in water.
The quantity of oxygen used in the biochemical oxidation of organic matter
in a specified time, at a specified temperature, and under specified conditions.
A standard test used in assessing wastewater strength.
A solution or liquid whose chemical makeup neutralizes acids or bases without a great change in pH. Any of certain combinations of chemicals used to stabilize the pH values or alkalinities of solutions.
A measure of the capacity of a solution or liquid to neutralize acids or bases. This is a measure of the capacity of water or wastewater for offering a resistance to changes in pH.
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CALCIUM CARBONATE (CaCO3) EQUIVALENT
An expression of the concentration of specified constituents in water in terms of their equivalent value to calcium carbonate. For example, the hardness in water which is caused by calcium, magnesium and other ions is usually described as calcium carbonate equivalent.
A
procedure which checks or adjusts an instrument’s accuracy by comparison with a standard or reference.
The determination, checking, or rectifying of the graduation of any instrument
giving quantitative measurements.
Any
substance which tends to produce cancer in an organism.
A
positively charged ion in an electrolyte solution, attracted to the cathode under the influence of a difference
in electrical potential.
Sodium ion (Na+) is a cation.
The negative terminal of an electrolytic cell.
A
branch of chemistry in which the destabilization and neutralization reactions occur between stable negatively charged
and stable positively charged particles.
A chemical complexing (forming or joining together) of metallic cations (such
as copper) with certain organic compounds, such as EDTA (ethylene diamine tetracetic acid).
Chelation is used to prevent the precipitation of metals (copper). Also
see the antonym SEQUESTRATION.
A measure of the oxygen consuming capacity of inorganic and organic matter present in water or wastewater. It is expressed as the amount of oxygen consumed from a chemical oxidant in a specific test. It does not differentiate between stable and unstable organic matter and thus does not necessarily correlate with biochemical oxygen demand.
CHLORORGANIC (klor-or-GAN-ick)
Organic compounds combined with chlorine. These compounds generally originate from, or are associated with, the processes such as those of algae in water.
Any matter in vegetation serving to impart a color to it other than green. Any matter in nature having color because of the presence of chromophores.
Pertaining to chromogen
Any chemical group which, aside from its chemical action, imparts a color to the compounds of which it is a constituent.
Chain-Of-Custody
A
group of bacteria found in the intestines of warm-blooded animals (including humans) and also in plants, soil,
air and water. Fecal coliforms are a specific class of bacteria which only inhabit the intestines of
warm-blooded animals.
The presence of coliform bacteria is and indication that the water is polluted
and may contain pathogenic organisms.
Very
small, finely divided solids (particles that do not dissolve) that remain dispersed in a liquid for a long time
because of their small size and electrical charge.
When most of the particles in water have a negative electrical charge, they
tend to repel each other.
This repulsion prevents the particles from clumping together, becoming heavier,
and settling out.
A means of measuring unknown chemical concentrations in water by measuring a sample’s color intensity. The specific color of the sample, developed by addition of chemical reagents, is measured with a photoelectric colorimeter or is compared with “color standards” using, or corresponding with, known concentrations of the chemical.
COMPOSITE (com-PAH-zit) (PROPORTIONAL) SAMPLE
A
composite sample is a collection of individual samples obtained at regular
intervals, usually every one or two hours during a 24-hour time interval.
Each individual sample is combined with the others in proportion to the rate
of flow when the sample was collected.
Equal volume individual samples also may be collected at intervals after
a specific volume of flow passes the sampling point or after equal time intervals and still be referred to as a
composite sample.
The resulting mixture (composite sample) forms a representative sample and
is analyzed to determine the average conditions during the sampling period.
A pure substance composed of two or more elements whose composition is constant. For example, table salt (sodium chloride, NaCl) is a compound.
A
rapid method of estimating the dissolved solids content of a sample.
The measurement indicates the capacity of a sample to carry an electric current,
which is related to the concentration of ionized substances in the water.
A measure of the conduction power of a solution equal to the reciprocal of
the resistance. The resistance is expressed in ohms and the conductance is expressed in mhos. Also
called SPECIFIC CONDUCTANCE.
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Records of observations and measurements of physical facts, occurrences, and conditions, reduced to written, graphical, or tabular form.
To remove ions from.
A
measure of how heavy a substance (solid, liquid or gas) is for its size.
Density is expressed in terms of weight per unit volume, that is, grams per
cubic centimeter or pounds per cubic foot.
The density of water (at 4
°C or 39
°F) is 1.0 gram per cubic centimeter or about 62.4 pounds
per cubic foot.
A closed container into which heated weighing or drying dishes are placed to cool in a dry environment in preparation for weighing. The dishes may be empty or they may contain a sample. Desiccators contain a substance, such as anhydrous calcium chloride, which absorbs moisture and keeps the relative humidity near zero so that the dish or sample will not gain weight from absorbed moisture.
DIATOMACEOUS EARTH (DYE-uh-toe-MAY-shus)
A
fine, siliceous (made of silica) “earth” composed mainly of the skeletal remains of diatoms.
Unicellular
(single cell), microscopic algae with a rigid (box-like) internal structure consisting mainly of silica.
The
separation of a colloid from a substance in true solution by allowing the solution to diffuse through a semi-permeable
membrane.
Use
of numbers to indicate the value or measurement of a variable.
The readout of an instrument by a direct, numerical reading of the measured
value.
A
solution that has been made weaker, usually by the addition of water.
DISINFECTION (dis-in-FECT-shun)
The process designed to kill most microorganisms in water, including essentially all pathogenic (disease-causing) bacteria. There are several ways to disinfect, with chlorine being most frequently used in water treatment. Compare with STERILIZATION.
Theoretically, the anhydrous residues of the dissolved constituents in water. Actually, the term is defined by the method used in determination. In water and wastewater treatment the Standard Methods tests are used.
In the distillation of a sample, a portion is evaporated; the part that condensed afterwards is the distillate.
Heated to steam and then cooled (condensed ) back to the liquid state. DI
stands for deionized.
Having a valence of two, such as the ferrous ion, Fe2+.
DPD (pronounce as separate letters)
A method of measuring the chlorine residual in water. The residual may be determined by either titrating or comparing a developed color with color standards. DPD is shorthand for N, N-diethyl-p-phenylene-diamine.
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Ethylenediaminetetraacetate. A hexadentate ligand. A neutral molecule forming six bonds to a metal ion. EDTA forms a very stable complex ion with most metal ions and is used as a “scavenger” to remove toxic heavy metals such as lead from the human body. It is also used as a reagent to analyze solutions for the metal ion content. EDTA is found in countless consumer products, such as soda, beer, salad dressings, bar soaps, and most cleaners. In these products EDTA ties up trace metal ions that would otherwise catalyze decomposition and produce unwanted precipitates.
A
hydraulic device used to create a negative pressure (suction) by forcing a liquid through a restriction, such as
a Venturi. An eductor or aspirator (the hydraulic device)
may be used in the laboratory in place of a vacuum pump.
As an injector, it is used to produce vacuum for chlorinators. Sometimes
used instead of a suction pump.
That
portion of the design range (usually upper 90 percent) in which an instrument has acceptable accuracy.
A device used to disperse a chemical solution into water being treated.
A
list of metals with the standard electrode potentials given in volts.
The size and sign of the electrode potential indicates how easily these elements
will take on or give up electrons, or corrode.
Hydrogen is conventionally assigned a value of zero.
A
conductor used to establish electrical contact with a nonmetallic part of a circuit.
A substance which cannot be separated into its constituent parts and still retain its chemical identity. For example, sodium (Na) is an element.
Samples are titrated to the end point. This means that a chemical is added, drop by drop, to a sample until a certain color change (blue to clear, for example) occurs. This is called the END POINT of the titration. In addition to a color change, and end point may be reached by the formation of a precipitate or the reaching of a specified pH. An end point may be detected by the use of an electronic device such as a pH meter. The completion of a desired chemical reaction.
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FACULTATIVE (FACK-ul-TAY-tive)
Facultative bacteria can use either molecular (dissolved) oxygen or oxygen obtained from food materials such as sulfate or nitrate ions. In other words, facultative bacteria can live under aerobic or anaerobic conditions.
Melted by a flame to smooth out irregularities. Sharp or broken edges of glass (such as the end of a glass tube) are rotated in a flame until the edge melts slightly and becomes smooth.
Fritted : being porous glass made of sintered powdered glass or fiberglass, a glass filter.
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Georgia Environmental
Protection Division.
A division of the GA DNR, Department of Natural Resources.
A
ratio ubiquitous.
Phi.
v. The
simplest of all infinitely continued fractions.
Look up Fibonacci Series.
A single sample of water collected at a particular time and place which represents the composition of the water only at that time and place.
A means of measuring unknown concentrations of water quality indicators in a sample by WEIGHING a precipitate or residue of the sample.
H A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Microorganisms
which use ORGANIC matter for energy and growth.
The same throughout.
Consistent.
No difference of one part with another.
Materials which readily absorb moisture.
I A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Conical glass vessel calibrated to contain a liter and graduated in milliliters per liter at its apex. Used in determination of settleable solids in solutions.
Latin. In place
A
substance that gives a visible change, usually of color, at a desired point in a chemical reaction, generally at
a specified end point.
Material, such as sand, salt, iron, calcium salts and other mineral materials. Inorganic substances are of mineral origin, whereas organic substances are usually of animal or plant origin. Also see ORGANIC.
Waste material, such as sand, salt, iron, calcium, and other mineral materials which are only slightly affected by the action of organisms. Inorganic wastes are chemical substances of mineral origin, whereas organic wastes are chemical substances of an animal or plant origin.
An
electrically charged atom, radical (such as SO42-), or molecule formed by the loss or gain
of one or more electrons.
Ion Selective Electrode
The point at which the potential (mV) of the electrode will not vary with
temperature.
Influent Wastewater Concentration. EPD term.
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Nitrogen
in the form of organic proteins or their decomposition product ammonia, as measured by the Kjeldahl Method.
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A shallow body of water, as a pond or lake, which usually has a shallow, restricted inlet from the sea. A pond containing raw or partially treated wastewater in which aerobic or anaerobic stabilization occurs.
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MATERIAL SAFETY DATA SHEET (MSDS)
A document which provides pertinent information and a profile of a particular
hazardous substance or mixture.
An MSDS is normally developed by the manufacturer or formulator of the hazardous substance or
mixture. The MSDS is required to be made available to employees and operators whenever there is the likelihood
of the hazardous substance or mixture being introduced into the workplace.
Some manufacturers are preparing MSDSs for products that are not considered
to be hazardous to show the product or substance is not hazardous.
A molar solution consists of one gram molecular weight of a compound dissolved in enough water to make one liter of solution. A gram molecular weight is the molecular weight of a compound in grams. For example, the molecular weight of sulfuric acid (H2SO4) is 98. A one M solution of sulfuric acid would consist of 98 grams of H2SO4 dissolved in enough distilled water to make one liter of solution.
The
curved surface of a column of liquid (water, oil, mercury) in a small tube.
When the liquid wets the sides of the container (as with water), the
curve forms a valley.
When the confining sides are not wetted (as with mercury), the curve forms
an upward bulge.
For water, read the bottom. For mercury, read the top.
A measure of the total alkalinity of an aqueous suspension or solution. It is measured by the quantity of sulfuric acid required to bring the water pH to a value of 4.3, as indicated by the change in color of methyl orange. It is expressed in milligrams CaCO3 per liter.
A
measure of the concentration by weight of a substance per unit volume.
For practical purposes, one mg/L of a substance in fresh water is equal to
one part per million parts (ppm). Thus
a liter of water with a specific gravity of 1.0 weighs one million milligrams.
If it contains 10 milligrams of calcium, the concentration is 10 milligrams
per million milligrams, or 10 milligrams per liter (10 mg/L), or 10 parts of calcium per million parts of water,
or 10 parts per million (10 ppm).
The
molecular weight of a substance usually expressed in grams.
The
molecular weight of a compound in grams is the sum of the atomic weights of all the elements in the compound. The
molecular weight of sulfuric acid,
H2SO4, in grams is 98.
A mole.
A mol.
ELEMENT
ATOMIC WEIGHT
NUMBER OF ATOMS
MOLECULAR WEIGHT
H
1
2
2
S
32
1
32
O
16
4
64
One mol weighs
98 grams.
The smallest division of a compound that still retains or exhibits all of the properties of the substance.
MPN (pronounce as separate letters)
That
number of organisms per unit volume that, in accordance with statistical
theory, would be more likely than any other number to yield the observed test result with the greatest frequency. MPN is the Most Probable Number of
coliform-group per unit volume of sample water.
Expressed as a density or population of organisms per 100 mL of sample water. Results
are computed from the number of positive findings of coliform group organisms resulting from multiple portion decimal
dilution plantings.
[ tntc
] is shorthand for ‘too numerous to count’.
MSDS (pronounce as separate letters)
Material
Safety Data Sheet.
A document which provides pertinent information and a profile of a particular
hazardous substance or mixture.
A MSDS is normally developed by the manufacturer or formulator of the hazardous substance or
mixture. The MSDS is required to be made available to employees and operators whenever there is the likelihood
of the hazardous substance or mixture being introduced into the workplace.
Some manufacturers are preparing MSDSs for products that are not considered
to be hazardous to show that the product or substance is not
hazardous.
mV Symbol
representing millivolt.
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A normal solution contains one gram equivalent weight of reactant (compound) per liter of solution. The equivalent weight of an acid is that weight which contains one gram atom of ionizable hydrogen or its chemical equivalent. For example, the equivalent weight of sulfuric acid, H2SO4, is 49 (98 divided by 2 because there are two replaceable hydrogen ions). A one N solution of sulfuric acid would consist of 49 grams of H2SO4 dissolved in enough water to make one liter of solution.
NEPHELOMETRIC (NEFF-el-o-MET-rick)
A
means of measuring turbidity in a sample by using an instrument called a nephelometer.
A nephelometer passes light through a sample and the amount of light deflected
(usually at a 90-degree angle) is then measured.
No Observed Effect
Concentration.
EPD term.
Material, such as sand, salt, iron, calcium and other mineral materials which
are only slightly affected by the actions of organisms and are not lost on ignition of dry solids at 550
ºC.
Volatile materials are chemical substances usually of animal or plant origin. Also
see INORGANIC WASTE or VOLATILE MATTER.
National Pollutant Discharge
Elimination System
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The Williams-Steiger Occupational Safety and Health Act of 1970 (OSHA) is a federal law designed to protect the health and safety of industrial workers and also the operators of water supply systems and treatment plants. The Act also regulates the design, construction, operation and maintenance of water supply systems and water treatment plants. OSHA also refers to the federal and state agencies which administer the OSHA regulations.
Substances
that come from animal or plant sources.
Organic substances always contain carbon,
(inorganic materials are chemical substances of mineral origin.) Also
see INORGANIC.
Any form of animal or plant life. Also see BACTERIA.
Oxidation is the addition of oxygen, removal of hydrogen, or the removal of electrons from an element or compound. In wastewater treatment, organic matter is oxidized to more stable substances. The opposite of REDUCTION.
OXIDATION REDUCTION POTENTIAL (abbreviated ORP)
The electrical potential required to transfer electrons from one compound or element (the oxidant) to another compound or element (the reductant); used as a qualitative measure of the state of oxidation in wastewater treatment systems.
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A
measure of the concentration by weight of a substance per unit volume.
For practical purposes, one mg/L of a substance in fresh water is equal to
one part per million parts (ppm). The
term is equivalent to milligrams per liter (mg/L) which is the preferred term.
See mg/L.
PATHOGENIC ORGANISMS (PATH-o-JEN-ick)
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 bacteria which do not
cause disease.
These organisms are called nonpathogenic.]
Pathogenic
or disease-causing organisms.
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.
Percent Saturation, %
=
Amount of Substance That is Dissolved x 100%
Amount that Could be Dissolved in Solution
pH (pronounce as separate letters)
pH
is an expression of the intensity of the basic or acidic condition of a liquid.
Mathematically, pH is the logarithm (base 10) of the reciprocal of the hydrogen
ion concentration.
pH
=
Log
(1/ [H+] )
The pH ranges from 0 to 14, where 0 is most acidic, 14 most basic, and 7
neutral. Natural waters usually have a pH between 6.5 and 8.5.
A
volumetric measuring device recognized as suitable for accurate and precise analytical work.
Usually long, thin and 50 mL and glass.
A measure of the hydroxides plus one half of the normal carbonates in aqueous suspension. Measured by the amount of sulfuric acid required to bring the water to a pH value of 8.3, as indicated by a change in color of phenolphthalein. It is expressed in parts per million of calcium carbonate.
A phenomenon of electrical interference.
A charge buildup surrounding an electrode,
possibly causing a change in the accuracy of the sample readout.
POLYELECTROLYTE (POLY-ee-LECK-tro-lite)
A high-molecular-weight (relatively heavy) substance that is formed by either natural or man-made processes. Natural polyelectrolytes may be of biological origin or derived from starch products and cellulose derivatives. Synthetic polyelectrolytes consist of simple substances that have been made into complex, high-molecular-weight substances. Used with other chemical coagulants to aid in binding small suspended particles to larger chemical flocs for their removal from water. Often called a POLYMER.
Water that does not contain objectionable pollution, contamination, or infective agents and is considered satisfactory, safe, suitable for drinking.
A
type of flow that occurs in tanks, basins, pipes or reactors when a slug of wastewater moves through without dispersing
or mixing with the rest of the body of liquid.
(1) When used as a noun, precipitate means an insoluble, finely divided substance which is a product of a chemical reaction within a liquid.
(2) When used as a verb, it means the separation from solution of an insoluble substance.
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.
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The
spread from minimum to maximum values that an instrument is designed to measure.
Return Activated Sludge
A pure chemical substance that is used to make new products or is used in chemical tests to measure, detect, or examine other substances.
Reduction is the addition of hydrogen, removal of oxygen, or the addition of electrons to an element or compound. Under anaerobic conditions (no dissolved oxygen present), sulfur compounds are reduced to odor-producing hydrogen sulfide H2S, and other compounds. The opposite of OXIDATION.
A
physical or chemical quantity whose value is known exactly and thus is used to calibrate or standardize instruments.
Flow
back. Sample is heated, evaporates, cools, condenses, and flows back to flask.
The number of significant digits to the right of the decimal point.
A sample portion of material or wastestream that is as nearly identical in content and consistency as possible to that in the larger body of material or wastestream being sampled.
A
device used to measure the flow rate of gases and liquids.
The gas or liquid being measured flows vertically up a tapered, calibrated
tube. Inside the tube is a small ball or bullet-shaped float (it may rotate) that rises or falls
depending on the flow rate.
The flow rate may be read on a scale behind or on the tube by looking at
the middle of the ball or at the widest part or top of the float.
RPD Relative Percent Difference
the absolute difference between the two results for a duplicate pair, divided by the average
result, and multiplied by 100 to express as a percentage
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(1) The
relative concentration of dissolved salts, usually sodium chloride, in a
given water.
(2)
A measure of the concentration of dissolved mineral substances in water. It
is usually expressed in terms of the number of parts per million of chloride (Cl).
The
condition of a liquid (water) when it has taken into solution the maximum possible quantity of a given substance
at a given temperature and pressure.
A
flat disc (painted in alternating black and white quarters for high visibility) lowered into the water by a rope
until it is just barely visible.
At this point, the depth of the disc from the water surface is the recorded
Secci disc transparency.
Perform test under matching light conditions and locations.
SECOND STAGE BIOLOGICAL OXYGEN DEMAND
That part of the oxygen demand associated with the biochemical oxidation of nitrogenous material. As the term implies, the oxidation of the nitrogenous materials usually does not start until a portion of the carbonaceous material has been oxidized during the first stage.
That matter in wastewater which will not stay in suspension during a pre selected settling period, such as one hour, but either settles to the bottom or floats to the top. In the Imhoff cone test, the volume of matter that settles to the bottom of the cone in one hour.
The range of values between upper and lower limits.
A solution mixture of dissolved substances. In a solution it is impossible to see all the separate parts.
The
scale or range of values an instrument is designed to measure.
A
physical or chemical quantity whose value is known exactly, and is used to calibrate or standardize instruments. A
solution having a recognized and permanent value.
A solution in which the exact concentration of a chemical or compound is known.
To
compare with a standard.
(1)
In wet chemistry, to find out the exact strength of a solution by comparing
it with a standard of known strength.
This information is used to adjust the strength by adding more water or more
of the substance dissolved.
(2) To set up an instrument or device to read a standard. This allows you to adjust the instrument so that it reads accurately or enables you to apply a correction factor to the readings.
Solids that either float on the surface of, or are in suspension in water, wastewater, or other liquids, and which are largely removable by laboratory filtering. The quantity of material removed from wastewater in a laboratory test, as prescribed in “Standard Methods for the Examination of Water and Wastewater” and referred to as non filterable residue.
STERILIZATION (STUR-uh-luh-ZAY-shun)
The removal or destruction of all microorganisms, including pathogenic and other bacteria, vegetative forms and spores. Compare with DISINFECTION.
Standard Units. Term
used in conjunction with pH measuring.
SUPERNATANT (sue-per-NAY-tent)
Liquid removed from settled sludge. Supernatant commonly refers to the liquid between the sludge on the bottom and the scum on the water surface of a basin or container.
Abbreviation for surface-active agent. The active agent in detergents that possesses a high cleaning ability.
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A digester sampling well which allows sampling of the digester contents without venting digester gas.
To
TITRATE a sample, a chemical solution of known strength is added on a drop-by-drop basis until a certain color
change, precipitate, or pH change in the sample is observed (end point). Titration
is the process of adding the chemical reagent in increments until completion of the reaction, as signaled by the
end point.
A device or meter that continuously measures and calculates (adds) total flows in gallons, million gallons, cubic feet, or some other engineering unit of volume measure. Also called an “integrator”.
All
of the dissolved solids in a water.
TDS is measured on a sample of water that has passed through a very fine
mesh filter to remove suspended solids.
The water passing through the filter is evaporated and the residue represents
the dissolved solids.
Also see SPECIFIC CONDUCTANCE.
Total Suspended
Solids. The
measurement of suspended solids begins with separating those solids that can be removed from the suspension in
the water by filtration. These
solids contain organic and inorganic materials.
The measurement of the organic materials is referred to as “volatilization”. This is accomplished
by a combustion procedure in which the organic material is converted into water and carbon dioxide by controlled
temperature. The
remaining material is considered “fixed” or “inorganic” 
Having a cloudy or muddy appearance.
TURBIDITY UNITS (TU) (ter-BID-it-tee)
Turbidity units are a measure of the cloudiness of water. If measured by a nephelometric (deflected light) instrumental procedure, turbidity units are expressed in nephelometric turbidity units (NTU) or simply TU. Those turbidity units obtained by visual methods are express in Jackson Turbidity Units (JTU) which are a measure of the cloudiness of water; they are used to indicate the clarity of water. There is no real connection between NTUs and JTUs. The Jackson turbidimeter is a visual method and the nephelometer is an instrumental method based on deflected light. Refer to Secci Disk.
The
ratio of the design range to the range of acceptable accuracy or precision of an instrument.
Also see EFFECTIVE RANGE.
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ULTIMATE BIOCHEMICAL OXYGEN DEMAND
Commonly, the total quantity of oxygen required to satisfy completely the first stage biochemical oxygen demand. More strictly, the quantity of oxygen required to satisfy completely both the first stage and the second stage biochemical oxygen demands.
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(1)
A volatile substance is one that is capable of being evaporated or changed
to a vapor at relatively low temperatures.
Volatile substances also can be partially removed by air stripping.
(2) In terms of solids analysis, volatile refers to materials lost (including most organic matter) upon ignition in a muffle furnace for 60 minutes at 550 ºC. Natural volatile materials are chemical substances usually of animal or plant origin. Manufactured or synthetic volatile materials such as ether, acetone, and carbon tetrachloride are highly volatile and not of plant or animal origin.
Fatty acids produced during digestion which are soluble in water and can be steam-distilled at atmospheric pressure. Also called “organic acids.” Volatile acids are commonly reported as equivalent to acetic acid.
Liquids which easily vaporize or evaporate at room temperature.
Those solids in water or other liquids that are lost on ignition at 550 ºC.
A measurement based on the volume of some factor. Volumetric titration is a means of measuring unknown concentrations of water quality indicators in a sample BY DETERMINING THE VOLUME of titrant or liquid reagent needed to complete particular reactions.
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Waste Activated Sludge
Laboratory
procedures used to analyze a sample of water using liquid chemical solutions (wet) instead of, or in addition to,
laboratory instruments.
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In coagulation and flocculation procedures, the difference in the electrical charge between the dense layer of ions surrounding the particle and the charge of the bulk of the suspended fluid surrounding this particle. The zeta potential is usually measured in millivolts. See also Streaming Current Meter.