A.C.: an electric current which continually reverses its direction of flow in a regular fashion. The vast majority of electricity supply systems use A.C. The other system of electric current transmission is Direct Current (D.C.).

abatement: The reduction of pollutant discharge by means of process modification, shutdown or addition of control equipment.

absorber: A kind of scrubber utilizing the absorption principle.

acid: chemical substance whose water solutions exhibit a pH less than 7.

activated sludge: sludge withdrawn from the secondary clarifier in the activated sludge process, consisting of micro-organisms, nonliving organic matter and inorganic materials.
activated sludge process: a common method of disposing of pollutants in wastewaters. In the process, large quantities of air are bubbled through wastewaters that contain dissolved organic substances in open aeration tanks. Oxygen is required by bacteria and other types of microorganisms present in the system to live, grow, and multiply in order to consume the dissolved organic "food", or pollutants in the waste. After several hours in a large holding tank, the water is separated from the sludge of bacteria and discharged from the system. Most of the activated sludge is returned to the treatment process, while-the remainder is disposed of by one of several accepted methods.
adsorbent: In addition to the adjectival meaning, the term describes any of several substances that collect gaseous pollutants. Used both for measurement and control.

aeration: the process or method of bringing about intimate contact between air and a liquid.
aeration tank: serves as a chamber for injecting air into water.
aerobic bacteria: bacteria which require free (elementary) oxygen for their growth.
alternating current: an electric current which continually reverses its direction of flow in a regular fashion. The vast majority of electricity supply systems use A.C. The other system of electric current transmission is Direct Current (D.C.).

ampere: the standard unit of measure of electric current, named after Andre-Marie Ampere, represented by the symbol A. One ampere is the electric current produced in a circuit by one volt acting through a resistance of one ohm.

anaerobic bacteria: bacteria which grow in the absence of free oxygen and derive oxygen from breaking down complex substances.

B

BACT (best available control technology): An emission limitation based on the maximum degree of emission reduction achievable under Title 1 of the CAAA. EPA will establish BACT standards for serious, severe and extreme nonattainment areas.

biological oxidation: the process by which bacteria and other types of micro-organisms consume dissolved oxygen and organic substances in waste water, using the energy released to convert organic carbon into carbon dioxide and cellular material.

biochemical oxygen demand (BOD): a quantitative measure of the oxygen needed by bacteria and microorganisms for the biological oxidation of organic wastes in a unit volume of waste water. BOD is generally measured in milligrams per liter (rng/1) of oxygen consumed over a five-day period. Although complete biological decomposition of, organic waste requires about 20 days, the five-day BOD is about two-thirds of the total oxygen requirement and, therefore, is a practical measure of waste concentration. In waste treatment language, BOD is most frequently stated as the percentage removed during treatment, or remaining after treatment.

British thermal unit (BTU): heat required to raise the temperature of 1 lb. of water by 1° F. The BTU/hr. required to raise the temperature of a volume of standard air by a specific number of degrees is calculated by the formula:
Btu/hr = Temp. Rise x CFM x 1.085

buffer: a compound or mixture that, when contained in an solution, causes the solution to resist change in an pH. Each buffer has a characteristic limited range of pH over which it is effective.

C

capacitor start motor: type of single-phase induction motor with a capacitor connected in series with the starting winding. High–starting and breakdown torque, medium starting current. Used in hard-starting applications; compressors, pumps, etc.

catalyst: an element or ion that promotes or assists in a reaction without affecting or changing the element.

cation: a positively-charged ion.

celsius: a thermometric scale in which water boils at 100° and freezes at 0°, same as centigrade. °C = 0.5556 x (°F – 32°) 5/9 = 0.5556

chelate compound: a compound in an which the metal is contained as an integral part of a ring structure and is not readily ionized.

chelating agent: a compound capable of forming a chelate compound with a metal ion. See Also: chelate compound.
chemical oxygen demand (COD): a quantitative measure of the amount of oxygen required to oxidize all organic components in a unit volume on waste water - non-biodegradable as well as the BOD. The COD level can be determined more readily than BOD, but this measurement does not indicate how much of the waste can be decomposed by biological oxidation.
chlorination: the application of chlorine to water, sewage, or industrial wastes, generally for the purpose of disinfection, but frequently for accomplishing other biological or chemical results
chromium: a lustrous, hard, steel-gray metallic element, resistant to tarnish and corrosion, used in the hardening of alloys and in electro-plating
coagulation: the agglomeration of colloidal or suspended matter brought about by the addition of some chemical to the liquid, by contact, or by other means.
complex ion: an ion composed of two or more ions or radicals, both of which are capable of independent existence, for example cuprocyanide (Cu(CN)2)-.

complexing agent: a compound that will combine with metallic ions to form complex ions. See Complex Ion.

D

D.C.: direct current: an electric current which flows in one direction only. Other system of electric current transmission is alternating current (A.C.).

damper: change in pressure, or pressure drop, that occurs across a piece of control equipment.

dbA: sound-pressure level corrected to the “A” weighing network.

decibel: the logarithmic ratio between some known reference and some quantity of electrical or acoustic signal power.

delta P (?P): change in pressure, or pressure drop, that occurs across a piece of control equipment.

deionization: the removal of ions from a solution by ion exchange.

detergent: a surface active agent that possess the ability to clean soiled surfaces.

diaphragm: a porous or permeable membrane separating anode and cathode compartments of an electrolytic cell from each other or from an intermediate compartment.

digestion: the biochemical decomposition of organic matter which results in the formation of mineral and simpler organic compounds.
dispersing agent: a substance that increases the stability of a suspension by retarding the flocculation of such particles.

E

effluent: any gas or liquid emerging from a pipe or similar outlet; usually refers to waste products from chemical or industrial plants as stack gases or liquid mixtures.

electrowinning: the production of metals by electrolysis with insoluble anodes in an solutions derived from ores or other materials.

emission: release of pollutants into the air, water, or ground from a source.

F

fahrenheit: a thermometric scalre in which water boils at 212° and freezes at 32°. °F = (1.8 x °C) + 32°

federal implementation plan (FIP): under current law, a federally implemented plan to achieve attainment of an air quality standard, used when a state is unable to develop an adequate plan. Under the Senate bill, a plan containing control measures developed and promulgated by EPA in order to fill gaps in a State Implementation Plan (SIP).

filter area: quantity of filter media available for collection of contaminants. Expressed in square feet.

filtration: a means of separation where constituents are separated usually by physical methods.

flocculate: to aggregate into larger particles, to increase in an size to the point where precipitation occurs.

flocculation (floc): the combination or aggregation of suspended colloidal particles in such a way that they form small clumps; usually used in conjunction with additive chemicals (flocculants) to treat wastewater.

fluxing: a process used in the heating of metals which may be intended to reduce or eliminate oxidation, confine the products of oxidation, reduce their melting point, and improve fluidity of surface metal layers. Fluxing is generally used in casting, welding, and soldering.

free cyanide: (1) True. - The actual concentration of cyanide radical, or equivalent alkali cyanide, not combined in an complex ions with metals in an solution. (2) Calculated. - The concentration of cyanide, or alkali cyanide, present in an solution in an excess of that calculated as necessary to form a specified complex ion with a metal or metals present in an solution. (3) Analytical free cyanide content of a solution, as determined by a specified analytical method.

FRP: abbreviation for fiberglass-reinforced-plastic.

H

heat exchanger: a device such as a coil or radiator that is used to transfer heat between two physically separate fluids.

hydrophilic: tendency to absorb water

hydrophobic: tendency to repel water

impeller: another term for pump or mixer “wheel”. The rotating portion of the pump/mixer designed to increase the energy level of the liquid stream.

I

impeller diameter: the maximum diameter measured over the impeller blade.

indicator (pH): a substance that changes color when the pH of the medium is changed. In the case of most useful indicators, the pH range within which the color changes is narrow.

inhibitor: a substance used to reduce the rate of a chemical or electrochemical reaction, commonly corrosion or pickling.

inorganic material: material which will not respond to biological action (sand, cinders, stone). Nonvolatile fraction of solids

ion: a charged portion of matter of atomic or molecular dimensions.

ion exchange: a reversible process by which ions are interchanged between a solid and a liquid with no substantial structural changes in the solid. In practice, most commonly effected by ion exchange resins.

K

kelvin: absolute temperature in the SI system scale.

L

LAER (lowest achievable emission rate): the rate of emissions that reflects either the most stringent emission limit contained in the implementation plan of any state (unless it is proved that such limitations are not achievable, or the most stringent emission limit achieved in practice, whichever is most stringent).

liquid flowrate: the amount of water or “scrubbing liquid” introduced into a wet collector.

M

membrane: a microporous structure that acts as a highly efficient filter that allows passage of water, but rejects suspended solids and colloidals; depending on membrane type, ions and small molecules might or might not be rejected.

mixed liquor: the combination of primary effluent and active biological solids (return sludge) in the activated sludge process that is fed into the aeration tank
mixed media gravity filter: a filter using more than one filtering media @ such as coal and sand).
motor starter: an electrical control device used to start a motor and to protect the device from current overload condition. A motor starter should be selected to match the operating voltage and horsepower requirements of the motor.

MSDS (material safety data sheet): compilation of data and information on individual hazardous chemicals produced by the manufacturers and importers of that chemical, as required by OSHA’s Hazard Communication Standard, 29 CFR 1910.1200.

O

organic compound: a compound consisting of carbon, hydrogen and oxygen atoms.

organic matter: the waste from homes or industry of plant or animal origin. Volatile fraction of solids.
organic material: Material that can be broken down by bacteria (fats, meats, plant life).
oxidation: a reaction in an which electrons are removed from a reactant. Sometimes, more specifically the combination of a reactant with oxygen.

oxidation ponds or lagoons: holding ponds designed to allow the decomposition or organic wastes by aerobic or anaerobic means

oxidizing agent: a compound that causes oxidation, thereby itself becoming reduced.

P

particle: a small, discrete mass of solid or liquid material.

particulate: a particle of solid or liquid matter.

particulate matter: any solid liquid material in the atmosphere.

permit: an authorization, license or equivalent control document issued by EPA or an approved state agency to implement the requirements of an environmental regulation such as a permit to operate a facility that may generate harmful emissions.

pH: a unit of measure depicting the hydrogen concentration of a solution: Scale 1 to 14. Where 7 is neutral; <7 acidic; >7 basic.

pH adjustment: the act of changing the pH of an aqueous solution by adding acid or caustic.

polyelectrolytes: synthetic chemicals used as a coagulant aid in waste treatment

potable water: water fit for human consumption

PPM (parts per million): the number of parts of a given pollutant in a million parts of air or water. Units are expressed by weight or volume.

PSI (pounds per square inch): a measure of pressure .1 psi equals 27.7” water gauge.

PSIA (pounds per square inch absolute): the absolute pressure without reference to another point. Atmospheric pressure is 14.7 PSIA.

PSIG (pounds per square inch gauge): the pressure relative to atmosphere. For instance, 10 PSIG equals 24.7 PSIA. This is the more common pressure term.

reducing agent: a compound that causes reduction, thereby itself becoming oxidized.

rotor: the rotating part of most AC motors.

RPM: revolutions per minute.

S

service factor: the number by which the horsepower rating is multiplied to determine the maximum safe load that a motor may be expected to carry continuously.

SIP (state implementation plan): documents prepared by states, and submitted to EPA for approval, which identify actions and programs to be undertaken by the state and its subdivisions to implement their responsibilities under the Clean Air Act.

slurry: a suspension of solids in water.

specific gravity: the ratio of the weight or mass of a given volume of any substance to that of an equal volume of some other substance taken as a standard. The ratio of the density of any gas to the density of dry air at the same temperature and pressure is the specific gravity of the gas.

specific heat: the ratio of the quantity of heat required to raise a certain volume one degree to that required to raise an equal volume of water one degree.

split-phase motor: the most common type of single-phase induction motor. Moderate starting torque, high-starting current, high breakdown torque. Used on easy-starting equipment, such as belt-drive fans.

T

TEFC (totally enclosed, fan-cooled): totally enclosed motors equipped with a cooling fan to prevent overheating.

total cyanide: the total content of cyanide expressed as the radical CN-, or alkali cyanide whether present as simple or complex ions. The sum of both the combined and free cyanide content of a solution.

Toxic Release Inventory (TRI): a listing of pollutants and emission levels from each major source.

transformer: an electrical device that transfers energy from one circuit to another by magnetic coupling with no moving parts. Transformers provide a change in voltage, current, phase or other electric characteristic during the transfer and hence are used to convert between high and low voltages, to change impedance, and to provide electrical isolation between circuits.

transmitter: a wireless or radio transmitter; the set that transmits or sends a wireless

TSCA (Toxic Substances Control Act): administered by the EPA, was passed by Congress to protect human health and the environment by requiring testing and necessary use restrictions to regulate the commerce of certain chemical substances.

U

ULPA filter: Ultra Low Penetration Air Filter designed to be 99.997% efficient on 0.3 micron particles when clean

ultrafiltration: the process that uses membranes to achieve separation of various constituents; a typical ultrafiltration membrane allows water, ions, and small molecules to pass through while rejecting large molecules and suspended solids.

V

volt: the standard unit of potential difference or electromotive force, named after Alessandro Volta. One volt is the potential difference across a conductor when a current of one ampere dissipates one watt of power.