[dictionary] of environmental engineering and wastewater treatment

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Alireza Bahadori · Scott T. Smith

Dictionary ofEnvironmentalEngineeringand WastewaterTreatment


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Dictionary of Environmental Engineeringand Wastewater Treatment


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Alireza Bahadori • Scott T. Smith

Dictionaryof EnvironmentalEngineeringand Wastewater Treatment


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ISBN 978-3-319-26259-8 ISBN 978-3-319-26261-1 (eBook)DOI 10.1007/978-3-319-26261-1

Library of Congress Control Number: 2016930301

Springer Cham Heidelberg New York Dordrecht London

© Springer International Publishing Switzerland 2016This work is subject to copyright. All rights are reserved by the Publisher, whether the whole orpart of the material is concerned, specically the rights of translation, reprinting, reuse ofillustrations, recitation, broadcasting, reproduction on microlms or in any other physical way,and transmission or information storage and retrieval, electronic adaptation, computer software,or by similar or dissimilar methodology now known or hereafter developed.The use of general descriptive names, registered names, trademarks, service marks, etc. in thispublication does not imply, even in the absence of a specic statement, that such names areexempt from the relevant protective laws and regulations and therefore free for general use.The publisher, the authors and the editors are safe to assume that the advice and information inthis book are believed to be true and accurate at the date of publication. Neither the publisher northe authors or the editors give a warranty, express or implied, with respect to the materialcontained herein or for any errors or omissions that may have been made.

Printed on acid-free paper

Springer International Publishing AG Switzerland is part of Springer Science+Business Media(www.springer.com )

Alireza BahadoriSchool of Environment, Science

& EngineeringSouthern Cross UniversityLismore , NSW , Australia

Scott T. SmithSchool of Environment, Science

& EngineeringSouthern Cross UniversityLismore , NSW , Australia

http://www.springer.com/http://www.springer.com/


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The main goal of this comprehensive dictionary is to help industrial profes-sionals, academic staff members, and science and engineering students com-municate with a clearer understanding of the denitions and descriptions ofthe processes, equipment, and concepts related to wastewater treatment andenvironmental engineering that they use every single day in their jobs.

When unclear communication occurs in an industry, the problems thatresult can be costly, and that’s where this dictionary can help to eliminatefrustration, cost, downtime, and equipment failure. Now, engineers, students,academic staff, vendors, contract employees, and consultants can quicklyrefer to key technical terms and denitions in this handy new volume.Providing a common ground for more effective communication, this diction-ary is an essential reference for anyone working in a wastewater and environ-mental industrial setting, and it is a useful reference for students as well.

The alphabetically arranged entries range from a few descriptive words to

a page or more, covering key wastewater and environmental terms used indaily communications and all research and industrial activities. The key tech-nical terms, written in easy-to-understand, practical language, clearly demon-strate the principles and concepts behind the denitions. Many terms found inthis dictionary have standard denitions and can be found across a wide arrayof sources. The purpose of this work is to offer these many technical terms ina single, easily accessible format. The editors of this dictionary have carefullycompiled terms from various sources, including Earth System GovernanceProject, Global Environment Facility (GEF), Intergovernmental Panel onClimate Change (IPCC), United Nations Environment Program (UNEP),

World Nature Organization (WNO), World Wide Fund for Nature (WWF),European Environment Agency (EEA), Partnerships in EnvironmentalManagement for the Seas of East Asia (PEMSEA), Australian Department ofSustainability, Environment, Water, Population and Communities, AustralianNetwork of Environmental Defenders Ofces, Australian StudentEnvironment Network, Greening Australia, Environment Victoria, Land careAustralia, Brazilian Institute of Environment and Renewable NaturalResources, Environment Canada, Danish Ministry of Climate and Energy,German Federal Ministry for the Environment, Nature Conservation andNuclear Safety, Hong Kong Environmental Protection Department, Indian

Central Pollution Control Board (CPCB), Environmental Protection Agencyof Ireland, Ministry of Infrastructure and the Environment of Netherlands,Department of Conservation of New Zealand, Ministry for the Environment

Preface


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of New Zealand, Norwegian Directorate for Nature Management, NorwegianClimate and Pollution Agency, Saudi Environmental Society, Department forEnvironment, Food and Rural Affairs of the United Kingdom, EnglishHeritage, Environment Agency of England, Natural England, ScottishEnvironment Protection Agency, Scottish Natural Heritage, CountrysideCouncil for Wales, Environment Agency Wales, US Environmental ProtectionAgency, US Fish and Wildlife Service, US National Park Service, TorontoEnvironmental Alliance (TEA), African American EnvironmentalistAssociation, Environment America, Environment California, OMI Industries,Aqueonics, Inc., Stevens Water Monitoring Systems, Inc., Meitler Consulting,Inc., KLa Systems, EnviroChemie GmbH Technology for Water, NEFCO,Inc., and Soil Conservation Service of NSW.

Finally, the book explains the industry-specic terms for those who needto understand aspects of the industry but have been hindered from doing soby their inability to discover the meaning of the jargon used.

Last but not least, we would like to thank the Springer editorial team, inparticular Michael Luby, for their editorial assistance and support whileworking on this book project.

Lismore, NSW, Australia Alireza BahadoriScott T. Smith

Preface


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Contents

A .............................................................................................................. 1

B .............................................................................................................. 39

C .............................................................................................................. 65

D .............................................................................................................. 111

E .............................................................................................................. 141

F .............................................................................................................. 167

G ............................................................................................................. 195

H ............................................................................................................. 211

I ............................................................................................................... 227

J ............................................................................................................... 243

K ............................................................................................................. 245

L .............................................................................................................. 247

M ............................................................................................................. 265

N .............................................................................................................. 283

O ............................................................................................................. 293

P .............................................................................................................. 307

Q ............................................................................................................. 343R .............................................................................................................. 345

S .............................................................................................................. 375

T .............................................................................................................. 443

U .............................................................................................................. 467

V .............................................................................................................. 475

W ............................................................................................................. 485


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X .............................................................................................................. 499

Y .............................................................................................................. 501

Z .............................................................................................................. 503

Suggested Readings ............................................................................... 505

Contents


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Alireza Bahadori , Ph.D. is a lecturer in the School of Environment, Science& Engineering at Southern Cross University, Lismore, NSW, Australia. Hereceived his Ph.D. from Curtin University, Perth, Western Australia. For thebetter part of 20 years, Dr. Bahadori had held various process engineeringpositions and been involved in many large-scale projects at National IranianOil Company (NIOC), Petroleum Development Oman (PDO), and CloughAMEC PTY LTD. He is the author of several articles and books. His bookshave been published by multiple prestigious and major publishers such as

John Wiley & Sons, Springer, Taylor & Francis Group , and Elsevier .Dr. Bahadori is the recipient of the highly competitive and prestigiousAustralian Government’s Endeavour International Postgraduate Researchaward as part of his research in oil and gas. He also received a top-up awardfrom the State Government of Western Australia through Western AustraliaEnergy research Alliance (WA:ERA) in 2009. He is a member of Engineers

Australia (EA) as a professional engineer.

Scott T. Smith is Dean of Engineering at Southern Cross University, Lismore,NSW, Australia. Professor Smith’s research interests include the applicationof advanced materials (e.g., bre-reinforced polymer composites) for therepair and strengthening of existing concrete, metallic, and timber infrastructureand sustainable development of the built environment. He has publishedwidely in the FRP composites in civil engineering eld and has won severalresearch awards from professional international institutions including:• 2011 Warren Medal, Engineers Australia

• 2010 Distinguished Young Researcher Award, International Institute forFRP in Construction

• CICE 2008 Best Paper Award• 2004 Howard Medal, Institution of Civil Engineers UK (ICE)

To support his research he has been awarded USD 1.7 million fromexternal sources (Australian Research Council ARC-Discovery, ARC-Linkage, RGC Hong Kong-General Research Fund, National Natural ScienceFoundation of China NSFC) and sources internal to the university.

About the Authors


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1© Springer International Publishing Switzerland 2016A. Bahadori, S.T. Smith, Dictionary of Environmental Engineering and Wastewater Treatment ,DOI 10.1007/978-3-319-26261-1_1

A

Abandoned Mine (DerelictMine) (mm)

A mine which has been inactive for some consid-erable time and for which no title is current orwhere the lease has been cancelled.

Abandonment

Discontinued use of a system component or com-

ponents by removing them or rendering theminaccessible and inoperable.

Abatement

(1) The act or process of reducing the intensity ofpollution. (2) The use of some method of abatingpollution. (3) Putting an end to an undesirable orunlawful condition affecting the wastewater

collection system. A property owner found tohave inow sources connected to the collectionsystem may be issued a “Notice of Abatement.”Such notices will usually describe the violation,suggest corrective measures, and grant a periodof time for compliance.

Abiotic Resources

Abiotic Resources are the resources which areconsidered abiotic and therefore not renewable.Zinc ore and crude oil are examples of abioticresources.

Abrasion

The removal of surface material from any solidthrough the frictional action of another solid, aliquid or a gas or combination thereof.

Abrasion Mode

A size range of particles, typically larger thanabout 3 micrometres in diameter, primarily gen-erated by abrasion of solids.

Abrasion Resistance

The ability of a material to withstand abrasionwithout appreciative erosion.


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Abrupt Climate Change

Sudden (on the order of decades), large changesin some major component of the climate system,with rapid, widespread effects.

Absorption

Process of incorporation or assimilation by whichone substance is physically taken into andincluded with another substance; for example,bacteria assimilating nutrients from efuent. Thepenetration of atoms, ions or molecules into thebulk mass of a substance. A physio-chemical pro-cess in which a substance associates with anotherto form a homogeneous mixture presenting thecharacteristics of a solution. Absorption is a pro-cess in which liquid molecules are taken up by aliquid or solid and distributed throughout thebody of that liquid or solid.

Absorption Area

Design parameter described by the square foot-age of an absorptive surface that is associatedwith the hydraulic acceptance of efuent.

Absorption Capacity

A measure of the quantity of a soluble substancethat can be absorbed by a given quantity of asolid substance.

Absorption Coefcient

A measure of the ability of particles or gases toabsorb photons; a number that is proportional tothe number of photons removed from the sightpath by absorption per unit length.

Absorption Cross SectionThe amount of light absorbed by a particledivided by its physical cross section.

Absorption Trench

An Absorption Trench is a trench that is excavatedinto the ground and is installed along the naturalcontour of the ground and contains an arch or slot-ted pipe, aggregate, geo-textile, and is back lledwith topsoil. Absorption trenches treat wastewaterfrom toilets, laundries, bathrooms and kitchens.The length of trench depends on the soils absorp-tive capacity and the local climatic conditions.

Absorptive Surface

Plane of native soil where hydraulic properties

change.

Abstraction

The removal of water from any source, eitherpermanently or temporarily, so that it: Ceases tobe part of the resources of that area, or; is trans-ferred to another source within the area.

Abuse Coverings and Finishes

Jackets, mastics or lms used to protect insula-tion from mechanical and personnel abuse.

Acceleration Corrosion Test

Method designed to approximate, in a short-time,the deteriorating effect under normal long-termservice condition.

Acceptable

Condition in which a component is performingits intended purpose and is considered to be in anoperable state.

Acceptable Daily Intake (ADI)The highest daily amount of a substance that may beconsumed over a lifetime without adverse effects.

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Accepted Engineering Practices

Those requirements which are compatible withstandards of practice required of a registered pro-fessional engineer.

Acceptance Rate

Inltration of efuent into a designated mediaexpressed as a rate (e.g., cm/day).

Access Hole

A hole in the duct, at the extremity of a samplingline, through which sampling is undertaken.

Acclimation

The dynamic response of a system to the additionor deletion of a substance until equilibriumis reached; adjustment to a change in theenvironment.

Accretion

Gradual addition of sand to a beach or lake shore-line during periods of light on-shore wind and/orlowered sea level.

Accumulation Mode

A size range of particles, from about 0.1 to3 micrometres, formed largely by accumulationof gases and particles upon smaller particles.They are very effective in scattering light.

Accuracy

The absolute nearness to the truth. In physical

measurements, it is the degree of agreementbetween the quantity measured and the actual

quantity. It should not be confused with“precision,” which denotes the reproducibility ofthe measurement.

Acequia

Acequias are gravity-driven waterways, similarin concept to a ume. Most are simple ditcheswith dirt banks, but they can be lined with con-crete. They were important forms of irrigation inthe development of agriculture in the AmericanSouthwest. The proliferation of cotton, pecansand green chile as major agricultural staples owetheir progress to the acequia system.

Acicular Ferrite

A highly substructured, non-equiaxed ferriteformed upon continuous cooling by a mixed dif-fusion and shear mode of transformation thatbegins at a temperature slightly higher than thetransformation temperature range for upperbainite. It is distinguished from bainite in that it

has a limited amount of carbon available thus,there is only a small amount of carbide present.

Acid

(1) A substance that tends to lose a proton. (2) Asubstance that dissolves in water with the forma-tion of hydrogen ions. (3) A substance containinghydrogen which may be replaced by metals to

form salts.

Acid Deposition

A term for the conversion of sulfur oxide andnitrogen oxide emissions into acidic compoundswhich precipitate in rain, snow, fog, or dry parti-cles. A complex chemical and atmospheric phe-nomenon that occurs when emissions of sulfur

and nitrogen compounds and other substancesare transformed by chemical processes in the

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atmosphere, often far from the original sources,and then deposited on earth in either wet or dryform. The wet forms, popularly called “acidrain,” can fall to earth as rain, snow, or fog. Thedry forms are acidic gases or particulates.

Acid Embrittlement

A form of hydrogen embrittlement that may beinduced in some metals by acid.

Acid-Forming Bacteria

Microorganisms that can metabolize complexorganic compounds under anaerobic conditions.This metabolic activity is the rst step in the two-step anaerobic fermentation process leading tothe production of methane.

Acid Precipitation

Typically is rain with high concentrations of acids

produced by the interaction of water with oxy-genated compounds of sulfur and nitrogen whichare the by-products of fossil fuel combustion.

Acid Rain

Air pollution produced when acid chemicals areincorporated into rain, snow, fog or mist. The“acid” in acid rain comes from sulfur oxides and

nitrogen oxides, products of burning coal andother fuels and from certain industrial processes.The sulfur oxides and nitrogen oxides are relatedto two strong acids: sulfuric acid and nitric acid.When sulfur dioxide and nitrogen oxides arereleased from power plants and other sources,winds blow them far from their source. If the acidchemicals in the air are blown into areas wherethe weather is wet, the acids can fall to Earth inthe rain, snow, fog, or mist. In areas where the

weather is dry, the acid chemicals may becomeincorporated into dusts or smokes. Acid rain can

damage the environment, human health, andproperty. Acid rain is atmospheric precipitationwith a pH below 3.6–5.7. Burning of fossil fuelsfor heat and power is the major factor in thegeneration of oxides of nitrogen and sulfur,which are converted into nitric and sulfuricacids washed down in the rain. See alsoATMOSPHERIC CORROSION.

Acid Soil

A soil giving an acid reaction throughout mostor all of the soil prole (precisely. below a pHof 7.0; practically, below a pH of 6.5). Generally

speaking, acid soils become a problem whenthe pH drops below 5.5. At this level, andparticularly below 5.0, the following specicproblems may occur—aluminum toxicity,manganese toxicity, calcium deciency and/ or molybdenum deciency. Such problemsadversely affect plant growth and root nodula-tion, which may result in a decline in plantcover and increase in erosion hazard. The termis frequently used to describe soils with acidity

problems as above. Correction of the acidityis normally carried out by the application ofappropriate amounts of lime to bring the soil pHto a level of 6.0–6.5.

Acidity

The quantitative capacity of aqueous solutions toneutralize a base; measured by titration with a

standard solution of a base to a specied endpoint; usually expressed as milligrams of equiva-lent calcium carbonate per litre (mg/L CaCO 3 );not to be confused with pH. Water does not haveto have a low pH to have high acidity.

Acidity

The chemical activity of hydrogen ions in

soil expressed in terms of pH. See also ACIDSOIL, pH.

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ACM

Asbestos-containing material: a substance (usu-ally a construction material) that includes someform of asbestos.

Acoustic Logging

Acoustic logging is a method of determining thelocation of a leak in a water main, by placinglistening devices at known distances along themain.

Acoustic Insulation

Refers to the measures taken to reduce the trans-mission of noise from its source to the placeswhich must be protected or insulated.

Acoustics

The study of sound, and its transfer, reectionand absorption.

Acre-Foot (ac-ft)

A volume of water 1-ft deep and 1 ac in area, or43,560 cu ft (1233.5 m 3 ).

Acrylic

Resin polymerized from acrylic acid, methacrylicacid, eaters of these acids, or acrylonitrile.

Act

In an air pollution control context, usually refersto the federal Clean Air Act.

Action

Service Action: The identier for the type ofaction to take when the service is executed. Theavailable actions vary by service.

Action

The service action to take.

Active RecreationA level of land development which provides forovals, camp sites or other activities requiringextensive clearing or leveling for facilities.

ACTS

Asbestos Contractor Tracking System, a US EPAdatabase system for keeping track of asbestosremoval contractors and sites. The APCD usesACTS.

Activated Carbon

Adsorptive particles or granules usually obtainedby heating carbonaceous material in the absenceof air or in steam and possessing a high capacityto selectively remove trace and soluble compo-nents from solution.

Activated Carbon Adsorption

Removal of soluble components from aqueoussolution by contact with highly adsorptive granu-lar or powdered carbon.

Activated Carbon Treatment

A process intended for the removal of dissolvedand colloidal organic substances from water andwastewater by absorption on activated carbon;for example for the amelioration of taste, odouror colour.

Activated Sludge

A occulent microbial/mass, produced whensewage is continuously aerated. Sludge thathas undergone occulation forming a bacterialculture typically carried out in tanks. Can be

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extended with aeration. Activated sludge isSludge particles produced by the growth oforganisms in the aeration tank in the presenceof dissolved oxygen.

Activated Sludge Process

A common method of disposing of pollutants inwastewaters. In the process, large quantities ofair are bubbled through wastewaters that containdissolved organic substances in open aerationtanks. Bacteria and other types of microorgan-isms present in the system need oxygen to live,grown, and multiply in order to consume the

dissolved organic “food” or pollutants in thewaste. After several hours in a large holding tank,the water is separated from the sludge of bacteriaand discharged from the system. Most of the acti-vated sludge is returned to the treatment process,while the remainder is disposed of by one of sev-eral acceptable methods.

Activated-Sludge Loading

The pounds (kilograms) of BOD in the appliedliquid per unit volume of aeration capacity or perpound (kilogram) of activated sludge per day.

Activated-Sludge Process

Wastewater treatment process that uses activatedsludge to biologically convert non-settle able

(suspended, dissolved, and colloidal) organicmaterials to a settle able product using aerobicand facultative microorganisms; typically fol-lowed by clarication and sludge return.

Activation

The changing of a passive surface of a metalto a chemically active state. Contrast with

passivation.

Active

A state in which a metal tends to corrode (oppo-site of passive).

Active Metal

A metal ready to corrode, or being corroded.

Active Potential

The potential of a corroding material.

Activity

A measure of the chemical potential of asubstance, where chemical potential is not equalto concentration, that allows mathematical rela-tions equivalent to those for ideal systems to beused to correlate changes in an experimentallymeasured quantity with changes in chemicalpotential.

Activity (Ion)

The ion concentration corrected for deviationsfrom ideal behavior. Concentration multipliedby activity coefcient. Activity coefcient.A characteristic of a quantity expressing thedeviation of a solution from ideal thermody-namic behavior; often used in connection with

electrolytes.

Acute

A stimulus severe enough to rapidly induce aneffect; in aquatic toxicity tests, an effect observedin 96 h or less is typically considered acute.When referring to aquatic toxicology or humanhealth, an acute effect is not always measured in

terms of lethality.

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Acute Exposure

One or a series of short-term exposures generallylasting less than 24 h.

Acute Health Effect

A health effect that occurs over a relatively shortperiod of time (e.g., minutes or hours). The termis used to describe brief exposures and effectswhich appear promptly after exposure.

Adaptability

Refers to the degree to which adjustments arepossible in practices, processes, or structures ofsystems to projected or actual changes of climate.Adaptation can be spontaneous or planned, andbe carried out in response to or in anticipation ofchanges in conditions.

Adaptation

Measures taken by societies and individuals toadapt to actual or expected adverse impactson the environment, especially as the result ofclimate change.

Adaptive Capacity

The ability of a system to adjust to climate change

(including climate variability and extremes) tomoderate potential damages, to take advantage ofopportunities, or to cope with the consequences.

Added R-Value

Thermal resistance added to a constructionelement by insulation.

Addition Agent

A substance added to a solution for the purposeof altering or controlling a process. Examplesinclude wetting agents in acid pickles, brighten-ers or antipitting agents in plating solutions, andinhibitors.

Additive

Product added to a sewage treatment systemmarketed to improve performance. Additive is aSubstance added in a small amount, usually to auid, for a special purpose, such as to reduce fric-tion, corrosion, etc.

Add-On Control Device

An air pollution control device such as carbonabsorber or incinerator that reduces the pollution inexhaust gas. The control device usually does notaffect the process being controlled and thus is “add-on” technology, as opposed to a scheme to con trol

pollution through altering the basic process itself.See also POLLUTION PREVENTION.

Adhesive

A substance used to bond materials by surfaceattachment.

AdsorptionAdhesion of a substance to the surface of solidbodies or liquids with which it is in contact. Aphysical process in which the molecules of a gas,of dissolved substances or of liquids, adhere inextremely thin layers to the exposed surface ofsolid substances with which they come into con-tact. The retention of atoms, ions or molecules

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onto the surface of another substance. Refers tothe surface retention or adhesion of a very thinlayer of water molecules to the surfaces of amaterial (such as insulation bers) with whichthey are in contact.

Adsorption Water

Water held on the surface of solid particles bymolecular forces with the emission of heat (heatof wetting).

Advanced Primary Treatment

The use of special additives to raw wastewater tocause occulation or clumping to help settlingbefore the primary treatment such as screening.

Advanced Technology Partial ZeroEmission Vehicle (AT PZEV)

A vehicle that meets the Partial Zero Emission

Vehicle (PZEV) standard and includes zero emis-sion vehicle enabling technologies.

Advanced Waste Treatment

Any physical, chemical, or biological treatmentprocess used to accomplish a degree of treatmentgreater than that achieved by secondary treatment.

Advanced Wastewater Treatment

Any advanced process used above and beyondthe defacto typical minimum primary and sec-ondary wastewater treatment.

Adverse Health Effects

Health effects from exposure to air contaminantsthat may range from relatively mild temporaryconditions, such as minor eye or throat irritation,

shortness of breath, or headaches, to permanentand serious conditions such as birth defects, can-cer, or damage to lungs, nerves, liver, heart, orother organs.

Adverse Impact

A determination that an air-quality related valueis likely to be degraded within a Class I area.

Aeolian

A term applied to deposits of soil materials trans-

ported and/or arranged by wind.

Aerated

Solution containing more than 10 PPb (Parts Perbillion) oxygen.

Aerated Contact Bed

A biological treatment unit consisting of stone,cement-asbestos, or other surfaces supported inan aeration tank, in which air is diffused up andaround the surfaces and settled wastewaterows through the tank; also called a contactaerator.

Aerated Pond

A natural or articial wastewater treatment pondin which mechanical or diffused air aeration isused to supplement the oxygen supply. Aeration(1) The bringing about of intimate contactbetween air and a liquid by one or more of thefollowing methods: (a) spraying the liquid in theair; (b) bubbling air through the liquid; and (c)agitating the liquid to promote surface absorptionof air. (2) The supplying of air to conned spaces

under nappes, downstream from gates in con-duits, and so on, to relieve low pressures and toreplenish air entrained and removed from such

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conned spaces by owing water. (3) Relief ofthe effects of cavitation by admitting air to theaffected section.

Aeration

(1) Exposing to the action of air. (2) Causing airto bubble through. (3) Introducing air into asolution by spraying, stirring, or a similar method.(4) Supplying or infusing with air, as in sandor soil.

Aeration, Active

Introduction of air via either mechanical meansor diffused aeration.

Aeration Cell

An oxygen concentration cell; an electrolyticcell resulting from differences in dissolvedoxygen at two points. Also see DIFFERENTIAL

AERATION CELL.

Aeration Chamber

Chamber or tank in which wastewater is broughtinto contact with air to facilitate biological degra-dation such as in (but not limited to) the activatedsludge process.

Aeration, Diffused

Process of introducing air bubbles under pressureinto a treatment unit using a compressor orblower and a diffuser (Fig. 1 ).

Aeration Liquor

Mixed liquor. The contents of the aeration tankincluding living organisms and material carriedinto the tank by either untreated wastewater orprimary efuent.

Aeration, MechanicalProcess of introducing air into a treatmentcomponent by physical agitation using a devicesuch as a paddle, paddle wheel, spray nozzle orturbine.

Aeration, Passive

Process of introducing air into a treatment com-ponent without mechanical means.

Aeration Period

(1) The theoretical time, usually expressed inhours, during which mixed liquor is subjected toaeration in an aeration tank while undergoingactivated-sludge treatment. It is equal to the vol-

ume of the tank divided by the volumetric rate ofow of the wastewater and return sludge. (2) Thetheoretical time during which water is subjectedto aeration.

Fig. 1 Diffused aeration

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Aeration System

Piping, diffusers, air source, vents, and all othernecessary devices for an active aeration process.

Aeration Tank

A tank in which wastewater or other liquid is aer-ated. A chamber for injecting air into water. Thetank where raw or settled wastewater is mixedwith return sludge and aerated. The same as“aeration bay,” “aerator,” or “reactor.” Followingprimary treatment, contaminants dissolved insewage are consumed by microorganisms in largetanks that are supplied with the oxygen (air) nec-essary for the survival of the microorganisms.

Aerator

A device that brings air and a liquid into intimatecontact.

Aerial PhotographAny photograph taken of the surface of the earthfrom xed wing aircraft, helicopters, balloons orspacecraft. There are two categories of aerialphotography: Vertical where an attempt is madeto keep the optical axis of the camera perpendicu-lar to the earth's surface. If the axis is exactlyvertical, the photo is called a truly vertical photoand therefore contains zero TILT. However, in

practice it is impossible to keep the camera axisvertical and small tilts of less than 3° are toler-ated, The resultant photos are referred to as nearvertical and may be regarded as equivalent totruly vertical for most photo interpretation pur-poses. Oblique where the optical axis is deliber-ately tilted away from the vertical. If it is tiltedsufciently to include the horizon, the photo is

called a high oblique and it the horizon doesnot appear, it is called a low oblique. Obliqueaerial photographs cover more ground area thanvertical aerial photographs exposed at the samealtitude.

Aerial PhotographInterpretation (API)

A technique of obtaining information from aerialphotographs, principally applied to the tech-niques involving the stereoscopic viewing of thephotographs. This method enables the evaluationof terrain in three dimensions. lt is basically a

deductive process that requires conscious or sub-conscious consideration of the elements of theimage. The quality, reliability and efciency ofany interpretation are dependent on the personalexperience and expertise of the interpreter. Theacquisition of such knowledge, either by eldexamination to establish ground truth, or by thestudy of available maps and reports, should,therefore be considered an essential part ofany photo-interpretation job. API involves some

basic steps: examine the photographs to get athree- dimensional perception: identify groundconditions by observing certain elements appear-ing in the photographs: and analyzing specicproblems by the association of ground conditionswith one’s background experience. No othertechnique can provide a three-dimensional over-view of the terrain from which the inter-relationsof topography, drainage, surface cover, geologicmaterials, and human activities on the landscape

can be viewed and evaluated.

Aerobic

In the presence of, or requiring, oxygen.Wastewater treatment depending on oxygen forbacterial breakdown of waste.

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Aerobic Bacteria

Bacteria that require free (elementary) oxygenfor growth.

Aerobic Composting

It is a method of composting organic waste usingbacteria that need oxygen. This requires that thewaste be exposed to air either by turning or byforcing air through pipes that pass through thematerial.

Aerobic Condition

Descriptive of a condition in which dissolvedoxygen is present.

Aerobic Digestion

The breakdown of suspended and dissolvedorganic matter in the presence of dissolved oxy-gen. An extension of the activated-sludge pro-cess, waste sludge is stored in an aerated tankwhere aerobic microorganisms break down thematerial.

Aerobic Lagoon

An oxygen-containing lagoon, often equippedwith mechanical aerators, in which wastewater ispartially stabilized by the metabolic activities ofbacteria and algae (Fig. 2 ). Small lagoons (lessthan 0.5 ac [0.2 ha] and less than 3-ft [0.9-m]deep) may remain aerobic without mechanicalaeration. See also ANAEROBIC LAGOON.

Aerobic Treatment Unit (ATU)

A mechanical wastewater treatment unit that pro-vides secondary wastewater treatment for a single

home, a cluster of homes, or a commercial establish-ment by mixing air (oxygen) and aerobic and facul-tative microbes with the wastewater. ATUs typicallyuse a suspended growth process (such as activatedsludge-extended aeration and batch reactors), axed-lm process (similar to a trickling lter), or acombination of the two treatment processes.

Aerobic Wastewater TreatmentSystem

An Aerobic Wastewater Treatment System is anaerobic biological wastewater treatment system,usually producing secondary treatment.

Fig. 2 Aerobic lagoon

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Aerometric Information RetrievalSystem (AIRS)

A computer-based repository of US air pollutioninformation administered by the EPA Ofce ofAir Quality Planning and Standards.

Aerogel

A homogeneous, low-density solid state materialderived from a gel, in which the liquid compo-nent of the gel has been replaced with a gas. Theresulting material has a porous structure with anaverage pore size below the mean free path of airmolecules at standard atmospheric pressure andtemperature.

Aerosol

A suspension, in a gaseous medium, of solidparticles, liquid particles, or solid particles andliquid particles, having a negligible falling veloc-ity. (Note: In physics, an upper value is arbitrarily

assigned to the dimensions of particles capable ofconstituting an aerosol, adopting for the placebeing considered a maximum limit for the fallingvelocity. It is dened as being that of a sphericalparticle of density equal to 103 kg/m 3 and ofdiameter 100 μm, falling under the effect of itsown weight in an immobile gas at a temperatureof 20 °C and at a pressure of 101.3 kPa. In air,under a gravitational acceleration of 9.81 m/s 2 ,this speed is 0.25 m/s.)

Aeration Chamber

Chamber or tank in which wastewater is broughtinto contact with air to facilitate biological degra-dation such as in (but not limited to) the activatedsludge process.

Aeration SystemPiping, diffusers, air source, vents, and all othernecessary devices for an active aeration process.

Aerobic Decomposition

Decomposition and decay of organic material inthe presence of “free” or dissolved oxygen.

Aerobic Digestion

The breakdown of wastes by microorganisms inthe presence of dissolved oxygen. This digestionprocess may be used to treat only waste activatedsludge, or trickling lter sludge and primary(raw) sludge, or waste sludge from activatedsludge treatment plants designed without primarysettling. The sludge to be treated is placed in a

large aerated tank where aerobic microorganismsdecompose the organic matter in the sludge. Thisis an extension of the activated sludge process.

Aerobic Process

A waste treatment process conducted underaerobic (in the presence of “free” or dissolvedoxygen) conditions.

Aerobic Treatment Unit (ATU)

(1) Treatment component that utilizes oxygen todegrade or decompose wastewater, with or with-out mechanical means; (2) Term traditionallyused to describe proprietary devices that usedirect introduction of air into wastewater bymechanical means to maintain aerobic conditionswithin the pre-treatment component.

Aerobic Wastewater Treatment

Oxygen dependent wastewater treatment requir-ing the presence of oxygen for aerobic bacterialbreakdown of waste.

Aethalometer

An aerosol monitoring instrument that continu-ously measures particle light absorption (aerosolblack carbon) on a quartz bre lter.

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Afforestation

The establishment of a forest on land that has notpreviously, or not recently, been timbered. Theplanting of new forests on lands where the pre-ceding vegetation or land did not contain forests.

Afterburner

An air pollution abatement device that removesundesirable organic gases through incineration.In incinerator technology, a burner located so thatthe combustion gases are made to pass throughits ame in order to remove smoke and odours.It may be attached to or be separated from theincinerator proper.

Age Hardening

Hardening by aging, usually after rapid coolingor cold working.

Agglomerate

A collection of solid particles adhering to eachother.

Agglomeration

The grouping, or coming together of dispersedsuspended matter into larger particles, which set-

tle more rapidly. The action leading to the forma-tion of agglomerates (Fig. 3 ). The coalescence of

ocks or particles of suspended matter to formlarger ocks or particles which settle or may becaused to oat more readily.

Agglutination

The action of joining, by impact, solid particlescoated with a thin adhesive layer or of trappingsolid particles by impact on a surface coated withadhesive.

Aggradation

The process of building up of surfaces, such asstreambeds or oodplains, by the deposition ofsediment and/or colluviums.

Aggregate

(1) Primary soil particles that cohere to eachother more strongly than other surrounding par-ticles. (2) Naturally-occurring inorganic material

(crushed rock or gravel) screened to sizes forvarious uses. (3) A relatively stable assembly ofdry particles, formed under the inuence of phys-ical forces.

Aging

A change in the properties of certain metals andalloys that occurs at ambient or moderately ele-

vated temperatures after hot working or a heattreatment (quench aging in ferrous alloys, natural

Fig. 3 Agglomeration

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or articial aging in ferrous and non-ferrousalloys) or after a cold working operation (strainaging). The change in properties is often but notalways, due to a phase change (precipitation), butnever involves a change in chemical compositionof the metal or alloy.

Agitator

Mechanical apparatus for mixing or aerating.A device for creating turbulence.

Agricultural Residue

Plant parts, primarily stalks and leaves, notremoved from the elds with the primary food orbre product. Examples include corn Stover(stalks, leaves, husks, and cobs); wheat straw;and rice straw.

Agroforestry

The integration of commercial tree growing intothe operation of a farming enterprise. It involvesthe commercial utilization of native frees as wellas the planting and management of quicker-growing frees through afforestation. The aim is toensure a long term viable enterprise based ontimber and limber products, as part of the overallfarm operation.

AgronomyThe study of land management and associatedpractices for the establishment, growth and use ofcrops and pastures involves an understanding ofsoils, land, climate, plant characteristics and ani-mal husbandry in relation to crop and pastureproduction.

AHERA

Asbestos Hazards Emergency Response Act.

AIM

Architectural and industrial maintenance(coatings).

Air

So-called “pure” air is a mixture of gasescontaining about 78% nitrogen; 21% oxygen;less than 1% of carbon dioxide, argon, andother inert gases; and varying amounts of watervapour.

Air Barrier

A layer of material resistant to air ow usuallyin the form of polyolen. A material that isapplied in conjunction with a building compo-

nent (such as a wall, ceiling or sill plate) toprevent the movement of air through thatcomponent.

Air Barrier System

The assembly of components used in buildingconstruction to create a plane of air tightnessthroughout the building envelope and to control

air leakage.

Air Basins

Areas dened by geographical or administrativeboundaries; used for air pollution controlprograms.

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Air-Bound

Obstructed, as to the free ow of water, becauseof air entrapped in a high point; used to describea pipeline or pump in such condition.

Air Chamber

A closed pipe chamber installed on the dischargeline of a reciprocating pump to take up irregula-rities in hydraulic conditions, induce a uniformow in suction and discharge lines, and relievethe pump of shocks caused by pulsating ow.

Air-Chamber Pump

A displacement pump equipped with an air cham-ber in which the air is alternately compressed andexpanded by the water displaced by the pump,resulting in the water being discharged at a moreeven rate.

Air Changes Per Hour

An expression of ventilation rates—the numberof times in an hour that a home’s entire air vol-ume is exchanged with outside air.

Air Diffuser

Devices of varied design that transfer oxygen

from air into a liquid.

Air Diffusion

The transfer of air into a liquid through anoxygen- transfer device. See DIFFUSION.

Air Duct

Ducts, usually made of sheet metal, that carrycooled or heated air to all rooms.

Air Filters

Adhesive lters made of metal or various bresthat are coated with an adhesive liquid to whichparticles of lint and dust adhere. These lters willremove as much as 90% of the dirt if they do notbecome clogged. The more common lters are ofthe throwaway or disposable type.

Air Gap

The unobstructed vertical distance through thefree atmosphere between the lowest openingfrom any pipe or outlet supplying water to a tank,

plumbing xture, or other device, and the ood-level rim of the receptacle.

Air Hawks

Rectangular shaped vents at the attic rooftops.

Air Inltration

The amount of air leaking in and out of a buildingthrough cracks in walls, windows and doors.

Air Intake

An opening in a building’s envelope whose pur-pose is to allow outside air to be drawn in toreplace inside air.

Air Lift

A device for raising liquid by injecting air in andnear the bottom of a riser pipe submerged in theliquid to be raised.

Air-Lift Pump

A pump, used largely for lifting water from wells,from which ne pressured air bubbles are dis-charged into the water at the bottom of the well.

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The bubbles reduce the density of the water at thebottom, allowing the denser surrounding water topush it up in the discharge pipe to the outlet. Alsocalled an air lift.

Air Light

Light scattered by air (molecules or particles)toward an observer, reducing the contrast ofobserved images.

Air Lock

(1) Condition in a pressurized distribution systemwhere the presence of air or other gases preventsow; (2) Condition where air or other gasescollect at a high point in a gravity distributionsystem and prevent or restrict ow.

Air Monitoring

Sampling for and measuring of pollutants present

in the atmosphere.

Air Parcel

A volume of air that tends to be trans-ported as asingle entity.

Air Pollutant

Any material emitted into the atmosphere eitherby human activity or natural processes andadversely affecting man or the environment. Anysubstance in air that could, in high enough con-centration, harm man, other animals, vegetation,or material. Pollutants may include almost anynatural or articial composition of airborne mat-ter capable of being airborne. They may be in theform of solid particles, liquid droplets, gases, or

in combination thereof. Generally, they fall into

two main groups (1) those emitted directly fromidentiable sources and (2) those produced in theair by interaction between two or more primarypollutants, or by reaction with normal atmo-spheric constituents, with or without photo acti-vation. Exclusive of pollen, fog, and dust, whichare of natural origin, about 100 contaminantshave been identied. Air pollutants are oftengrouped in categories for ease in classication;some of the categories are solids, sulfur com-pounds, volatile organic chemicals, particulatematter, nitrogen compounds, oxygen compounds,halogen compounds, radioactive compound, andodours.

Air Pollution

Usually the presence of substances in the atmo-sphere resulting either from human activity ornatural processes, present in sufcient concentra-tion, for a sufcient time and under circum-stances such as to interfere with comfort, healthor welfare of persons or the environment. AirPollution is the presence of polluting gases and

suspended particles in the atmosphere in excessof air quality standards.

Air Pollution Bandings

The Air Pollution Information Service uses fourbands to describe levels of pollution. The bandsare Low, Moderate, High and Very High. Healthypeople do not normally notice any effects from

air pollution, except occasionally when air pollu-tion is “Very High”.

Air Pollution Control Device

Mechanism or equipment that cleans emissionsgenerated by a source (e.g. an incinerator, indus-trial smokestack, or an automobile exhaust sys-tem) by removing pollutants that would otherwise

be released to the atmosphere.

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Air Quality Criteria

The varying amounts of pollution and lengths ofexposure at which specic adverse effects tohealth and comfort take place.

Air Quality Index (AQI)

A numerical index used for reporting severity ofair pollution levels to the public. It replaces theformerly used Pollutant Standards Index (PSI).AQI incorporates ve criteria pollutants—ozone,particulate matter, carbon monoxide, sulfurdioxide, and nitrogen dioxide—into a singleindex. AQI levels range from 0 (Good air quality)to 500 (Hazardous air quality). The higher theindex, the higher the level of pollutants and thegreater the likelihood of health effects.

Air Quality Management Area(AQMA)

If a Local Authority identies any locations

within its boundaries where the Air QualityObjectives are not likely to be achieved, it mustdeclare the area as an Air Quality ManagementArea (AQMA). The area may encompass just oneor two streets, or it could be much bigger. TheLocal Authority is subsequently required to puttogether a plan to improve air quality in thatarea—a Local Air Quality Action Plan.

Air Quality Management District(AQMD)

Local agency charged with controlling air pollu-tion and attaining air quality standards.

Air Quality Objectives

The Air Quality Objectives are policy targets

generally expressed as a maximum ambientconcentration to be achieved, either without excep-tion or with a permitted number of exceedances,

within a specied timescale. The Objectives areset out in the UK Governments Air QualityStrategy for the key air pollutants.

Air Quality Plan (AQP)

A plan developed to attain and maintain an airquality standard.

Air Quality Simulation Model

A mathematical relationship between emissionsand air quality which simulates on a computer the

transport, dispersion and transformation of com-pounds emitted into the air.

Air Quality Standard (AQS)

The prescribed level of a pollutant in the outsideair that should not be exceeded during a specictime period to protect public health. Establishedby both federal and state governments. The level

of pollutants prescribed by regulations that arenot being exceeded during a given time in adened area.

Air Release

Allowing air to escape during pressurization of adistribution system using an air/vacuum releasevalve.

Air Scour

The use of air either alone or in combination withbackwash to enhance lter cleaning.

Air Space

The area between insulation facing and inte-rior of exterior wall coverings. Normally a 1 ″ airgap.

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Air Stripping

A technique for removal of volatile substancesfrom a solution; employs the principles ofHenry’s Law to transfer volatile pollutants from asolution of high concentration into an air streamof lower concentration. The process ordinarily isdesigned so that the solution containing the vola-tile pollutant contacts large volumes of air. Themethod is used to remove ammonia in advancedwaste treatment.

Air Tightness

Describes the leakiness of the building fabric.

Air Toxic

Any air pollutant for which a national ambient airquality standard does not exist (i.e., excludingozone, carbon monoxide, PM10, sulfur dioxide,and nitrogen dioxide) that may reasonably beanti cipated to cause cancer, developmental effects,

reproductive dysfunctions, neurological disorders,heritable gene mutations or other serious or irre-versible chronic or acute health effects in humans.

Air Valve

An air valve is a valve used on pipes to release airtrapped within the pipes as a result of lling oremptying it. Air valves are situated on high points

of the pipeline.

Airway

A space between roof insulation and roof boardsprovided for movement of air.

Airborne Particulates

Total suspended particulate matter found in theatmosphere as solid particles or liquid droplets.Chemical composition of particulates varies

widely, depending on location and time of year.Sources of airborne particulates include dust,emissions from industrial processes, combustionproducts from the burning of wood and coal,combustion products associated with motor vehi-cle or non-road engine exhausts, and reactions togases in the atmosphere.

AIRS

Aerometric Information Retrieval Subsystem, theUS EPA’s main air pollution database system.It includes ambient monitoring and meteorologicaldata (stored in SAROAD before 1987) in the Air

Quality Subsystem (AQS) and compliance andpermit data in the AIRS Facility Subsystem (AFS).Until recently, AFS also contained source emissiondata, but those data are moving to the EPA’s NETdatabase system and soon to the new NEI. For awhile, there was also an Area and Mobile Sourcessubsystem, but it has been shut down. The EPA hasmore information on AIRS and also provides datafrom AIRS through the web.

Air Shed

A term denoting a geographical area of which,because of topography, meteorology, and cli-mate, shares the same air (see AIR BASINS).

Airspace

A volume in a water storage, which is kept emptyfor the purpose of mitigating potential oods.

Alarm

Device that provides information on the status ofa component using a visual and/or audible device;can either be on site or remotely located.

AlbedoThe amount of solar radiation reected from anobject or surface, often expressed as a percentage.

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Alclad

Composite wrought product comprised of an alumi-num alloy core having on one or both surfaces ametallurgically bonded aluminum or aluminumalloy coating that is anodic to the core and thus elec-trochemically protects the core against corrosion.

Alcove

A moderately inclined to very steep open depres-sion with concave cross-section, such as the recesscreated in a hi//slope as the result of a slump.

Algal Bloom

A large, visible mass of algae found in bodies ofwater such as lakes or estuaries. Blooms occurmost often during warm weather, but may alsooccur at other times of the year. Color rangesfrom green to red.

Algae

Microscopic plants which contain chlorophylland live oating or suspended in water. They alsomay be attached to structures, rocks or other sim-ilar substances.

Algae produce oxygen during sunlight hoursand use oxygen during the night hours. Their bio-logical activities appreciably affect the pH anddissolved oxygen of the water.

Algal Assay

An analytical procedure that uses specied nutri-ents and algal inoculums to identify the limitingalgal nutrient in water bodies.

Algal Bloom

Large masses of microscopic and macroscopicplant life, such as green algae, occurring in bod-ies of water.

Alkali Generally

Any substance that has highly basic properties;used particularly with reference to the soluble saltsof sodium, potassium, calcium, and magnesium.

Alkali Metal

A metal in group lA of the periodic system—namely, lithium, sodium, potassium, rubidium,cesium, and francium. They form strongly alka-line hydroxides, hence the name.

AlkalineThe condition of water, wastewater, or soil thatcontains a sufcient amount of alkali substances toraise the pH above 7.0. Alkaline is Having proper-ties of an alkali. (2) Having a pH greater than 7.

Alkaline Cleaner

A material blended from alkali hydroxides andsuch alkaline salts as borates, carbonates, phos-phates, or silicates. The cleaning action may beenhanced by the addition of surface-active agentsand special solvents.

Alkaline Soil

A soil giving an alkaline reaction throughout mostor all of the soil prole (precisely, above a pH of7.0; practically, above a pH of 8.0). Many alkalinesoils have a high pH indicated by the presence ofcalcium carbonate, and are suitable tor agricul-ture. However, others are problem soils becauseof salinity and/or sodicity. Soils with a pH above9.5 are generally unsuitable for agriculture. Seealso SODIC SOIL, SALINE, SOIL, pH.

Alkalinity

The capacity of water to neutralize acids; aproperty imparted by carbonates, bicarbonates,hydroxides, and occasionally borates, silicates,

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and phosphates. It is expressed in milligramsof equivalent calcium carbonate per litre (mg/LCaCO 3 ).

Alkyd

Resin used in coatings. Reaction products ofpolyhydric alcohols and polybasic acids.

Alkyl Benzene Sulfonate (ABS)

A type of surfactant, or surface active agent, pres-ent in synthetic detergents in the United Statesprior to 1965. ABS was troublesome because ofits foam-producing characteristics and resistanceto breakdown by biological action. ABS has beenreplaced in detergents by linear alkyl sulfonate,which is biodegradable.

Alkylation

(1) A chemical process in which an alkyl radicalis introduced into an organic compound by sub-stitution or addition. (2) A renery process forchemically combining isoparafn with olenhydrocarbons.

Alligatoring

(1) Pronounced wide cracking over the entiresurface of a coating having the appearance ofalligator hide. (2) The longitudinal splitting ofat slabs in a plane parallel to the rolled surface.Also called sh-mouthing.

Allocation Announcement

The basis upon which Water Allocation is calcu-lated from time to time. It may take the form ofan Initial Announcement at the beginning of theWater Year or a Supplementary Announcementduring the Water Year. It is expressed as a per-centage of Entitlement.

Allowances

An authorization to emit, during a specied year,up to one ton of carbon dioxide equivalent.

Alloy Plating

The code position of two or more metallicelements.

Alloy Steel

Is one that contains either silicon or manganese

in amounts in excess of those quoted in plain car-bon steel or that contains any other element, orelements, as the result of deliberately made alloy-ing additions.

Alluvial

Pertaining to processes or materials associatedwith transportation or deposition of sediment bywater. Describes material deposited by, or in tran-sit in, owing water.

Alluvial Fan

An accretion of sediments in a ow line charac-terized by radial slope lines inclined away from apoint, giving it a typical fan’ shape. Such depositsmay build up to eventually block and divert ows.

Alluvial Plain

A large at area of alluvium. Although it includesoodplains, the preferred use of the term is todescribe former oodplains where there is norecent accumulation of sediment.

Alluvial Soil

A soil developed from recently deposited allu-vium, normally characterised by little or no mod-ication of the deposited material by soil-forming

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processes, particularly with respect to soilhorizon development. (1) Soil developing fromsediments (alluvium) recently deposited by run-ning water of streams and rivers and exhibitingessentially no horizon development or modica-tion of the recently deposited materials; (2) Whencapitalized, it refers to a great soil group of theazonal order consisting of soils with little or nomodication of the recent sediment in which theyare forming.

Alluvium

Deposits of clay, silt, sand, gravel, or other

particulate material that has been deposited bya stream or other body of running water in astreambed, on a ood plain, on a delta, or at thebase of a mountain. An extensive stream-laiddeposit of unconsolidated material, includinggravel, sand, silt and clay. Typically it formsoodplains that develop alluvial soils.

Alpha Factor

In an activated sludge plant, the ratio of the oxy-gen transfer coefcient in mixed liquor to theoxygen transfer coefcient in clean water.

Alpha Iron

The body-centered cubic form of pure iron, sta-ble below 910 °C (1670 °F).

Alternate-Immersion Test

A corrosion test in which the specimens are inter-mittently exposed to a liquid medium at denitetime intervals.

Alteration

Modication of a wastewater treatment systemon the basis of: an increase in the volume of per-mitted ow; a change in the nature of permitted

inuent; a change from the planning materialsapproved by the permitting authority; a change inconstruction; or an increase, lengthening, orexpansion of the treatment or dispersal system.

Alternate Meter

A Meter (or series of meters) attached to thedevice which drives the extraction pump at aLicensed Work.

Alternating Drain Fields

Final treatment and dispersal component that iscomprised of multiple soil treatment areas whichare independently dosed.

Alternative Energy

Energy that is not popularly used and is usuallyenvironmentally sound, such as solar or windenergy (as opposed to fossil fuels).

Alternative Fibres

Fibres produced from non-wood sources for usein paper making.

Alternative Fuels

Fuels that can replace ordinary gasoline. Alter-native fuels may have particularly desirableenergy efciency and pollution reduction fea-tures. Alternative fuels include compressed natu-ral gas, alcohols, liqueed petroleum gas (LPG),and electricity.

Alternative Transportation

Modes of travel other than private cars, such aswalking, bicycling, rollerblading, carpooling andtransit.

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Altitude Valve

An altitude valve is a type of valve typicallyfound in a storage tank of a water distributionsystem. It closes to prevent the storage tank fromoverowing when a pres-set level is reached, butwill remain open while the level is below the setpoint.

Aluminizing

Process for impregnating the surface of a metalwith aluminium in order to obtain protectionfrom oxidation and corrosion.

Aluminium (Al)

Aluminium is one of the main components of themost common rock species. Increased acidica-tion in the soil releases aluminium which travelsin the and then runs into the sea and lakes whereit has a negative effect on the reproductive capa-bility of sh and birds, for example. The metal

aluminium is made from bauxite. Its productionconsumes a huge amount of energy, but at thesame time aluminium is easy to recycle manytimes.

Aluminium Foil

Thin sheet of rolled aluminium (0.15 mm thickand under).

Alum, Aluminium Sulphate

[Al 2 (SO 4 )3 · 18H 2 O] Used as a coagulant in l-tration. Dissolved in water, it hydrolyzes intoAl(OH) 2 and sulfuric acid (H 2 SO 4 ). To precipitatethe hydroxide, as needed for coagulation, thewater must be alkaline.

Amalgam

An alloy of mercury with one or more other metals.

Ambient

Pertaining to the current environmental condi-tion; ambient monitoring evaluates water qualityperiodically at xed locations; data collected overlong periods of time help determine the status andtrends of water quality of a particular body ofwater. Generally refers to the prevailing dynamicenvironmental conditions in a given area.

Ambient Air

Outside air; any portion of the atmosphere notconned by walls and a roof.

Amendment

A change or addition to an existing law or rule.

Amenities

Benets of a property, such as nearby playgrounds,swimming pools, community centres or parks.

American Society for Testingand Materials (ASTM)

A non-prot organization that provides a forumfor producers, consumers and representatives ofgovernment and industry to write laboratory teststandards for materials, products, systems andservices. ASTM publishes standard test methods,

specications, practices, guides, classicationsand terminology.

Ammeter

An instrument for measuring the magnitude ofelectric current ow.

Ammonia (NH3 )

A chemical combination of hydrogen (H) andnitrogen (N) found extensively in nature. Anindicator of fresh pollution.

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Ammonia, Ammonium

(NH 3 , NH 4 1 ) Urea and proteins are degradedinto dissolved ammonia and ammonium in rawwastewaters. Typically, raw wastewater contains30–50 mg/L of NH 3 . Reactions between chlorineand ammonia are important in disinfection.

Ammonia Nitrogen

The quantity of elemental nitrogen present in theform of ammonia (NH 3 ).

Ammoniator

Apparatus used for applying ammonia or ammo-nium compounds to water.

Ammonication

Bacterial decomposition of organic nitrogen toammonia.

Ammonia Stripping

A method of removing ammonia content fromwater by making it alkaline, and aerating.

Amoeba

A group of simple protozoans, some of whichproduce diseases such as dysentery in humans.

Amorphous Solid

A rigid material whose structure lacks crystallineperiodicity; that is, the pattern of its constituentatoms or molecules does not repeat periodicallyin three dimensions.

Ampere

The unit of measurement of electrical current.It is proportional to the quantity of electronsowing through a conductor past a given point inone second and is analogous to cubic feet ofwater owing per second. It is the current pro-duced in a circuit by one volt acting through aresistance of one ohm.

Amperometric

Pertaining to measurement of electric currentowing or generated, rather than by voltage.

Amphoteric

A term applied to oxides and hydroxides whichcan act basic toward strong acids and acidictoward strong alkalis. Substances which candissociate electrolytically to produce hydrogen orhydroxyl ions according to conditions.

Anchor Pattern/Surface Prole

Shape and amplitude of prole of blast cleanedor grooved steel which inuences the bondbetween metallic or paint of lms and thesubstrate.

AnchoriteA zinc-iron phosphate coating for iron andsteel.

Anaerobic

Wastewater treatment in which bacteria break-down waste without using oxygen.

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Anaerobic Bacteria

Bacteria that grow in the absence of free oxygenand derive oxygen from breaking down complexsubstances .

Anaerobic Decomposition

Decomposition of cellulose and proteins occur-ring in the absence of oxygen, such as in landllwaste, producing methane and carbon dioxide.Anaerobic bioreactors increase the rate of meth-ane generation, which can then be collected andused for energy recovery.

Anaerobic Digestion

The degradation of concentrated wastewater sol-ids, during which anaerobic bacteria break downthe organic material into inert solids, water, car-bon dioxide, and methane.

Anaerobic Lagoon

A wastewater or sludge treatment process thatinvolves retention under anaerobic conditions.

Anaerobic Wastewater Treatment

Wastewater treatment in the absence of oxygen,anaerobic bacteria breakdown waste.

Ancient Forest

A forest that is typically older than 200 yearswith large trees, dense canopies and an abun-dance of diverse wildlife.

Angle of Repose

The stable angle between the horizontal and themaximum slope that loose material assumesthrough the inuence of gravity.

Animal Feeding Operation (AFO)

Lot or facility (other than an aquatic animal pro-duction facility) where the following conditionsare met:

• Animals (other than aquatic animals) havebeen, are, or will be stabled or conned andfed or maintained for a total of 45 days ormore in any 12-month period, and

• Crops, vegetation, forage growth, or post-harvest residues are not sustained in the nor-mal growing season over any portion of the lotor facility.

Anion

A negatively charged ion attracted to the anodeunder the inuence of electrical potential.

Anionic Flocculants

A polyelectrolyte with a net negative electrical

charge.

Announcement

An Announcement is made to a Water Sourceand Access License Category and applies to allAccess Licenses in the Water Source with thatLicense Category. The key elements of anAnnouncement are:

• Water Source• License Category• Announcement Type• Date or period that the Announcement applies to• Percentage Allocation—transaction change to

apply to the Access License.

Anoxic

Condition in which all constituents are in theirreduced form (no oxidants present); conditions in aseptic tank are generally anaerobic, but not anoxic.

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Condition in which oxygen is available in thecombined form only; there is no free oxygen.Anoxic sections in an activated-sludge plant maybe used for denitrication.

Annealing

A generic term denoting a treatment, consistingof heating to and holding at a suitable tempera-ture, followed by cooling at a suitable rate, usedprimarily to soften metallic materials, but also tosimultaneously produce microstructure. The pur-pose of such changes may be, but is not connedto improvement of machinability, facilitation of

cold work, improvement of mechanical or elec-trical properties and/or increase in stability ofdimensions. When the term is used by itself, fullannealing is implied. When applied only for therelief of stress, the process is properly calledstress relieving or stress-relief annealing.

Annual Arithmetic Mean

The mean (average) of a set of values of a vari-able over a calendar year. The arithmetic mean isequal to the sum of all the readings divided by thenumber of readings.

Annual Exceedance Probability

The chance that a particular storm or ood eventwill be equalled or exceeded in any year,

expressed as a percentage. lt is the reciprocal ofreturn period. For example, a 20 year returnperiod is equivalent to a 5% annual exceedanceprobability.

Annual Geometric Mean

The geometric average of a set of values of avariable over a calendar year. The geometric

mean is the nth root of the product of n readings,

usually calculated as the antilogarithm of theaverage of the logarithms of the data points. Thisstatistic has been used to compile total suspendedparticulate data, for example.

Annual Use Limit

This is the maximum Annual Usage allowablefor the Access Licence. It is dened as a percen-tage of the Annual Share Component for theAccess Licence.

Anode

An electrode at which oxidation of the surface orsome component of the solution is occurring.

Anode Corrosion

The dissolution of a metal acting as an anode.

Anode Corrosion EfciencyRatio of actual to theoretical corrosion based onthe total current ow calculated by Faraday’slaw from the quantity of electricity that haspassed.

Anode Effect

The effect produced by polarization of theanode in electrolysis. It is characterized by a sud-den increase in voltage and a correspondingdecrease in amperage due to the anode becomingvirtually separated from the electrolyte by a gaslm.

Anode Efciency

Current efciency of the anode.

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Anode Film

(1) The portion of solution in immediate contactwith the anode, especially if the concentrationgradient is steep. (2) The outer layer of the anodeitself.

Anode Polarization

Difference between the potential of an anodepassing current and equilibrium potential (orsteady-state potential) of the electrode having thesame electrode reaction.

Anodic Cleaning

Electrolytic cleaning in which the work is theanode. Also called reverse-current cleaning.

Anodic Coating

A lm on a metal surface resulting from an elec-

trolytic treatment at the anode.

Anodic Inhibitor

A chemical substance or combination of substan-ces that prevent or reduce, by physical, physio-chemical or chemical action, the rate of theanodic or oxidation reaction.

Anodic Metallic Coating

A coating, composed wholly or partially of ananodic metal (in sufcient quantity to set offelectrochemical reaction) which is electricallypositive to the substrate to which it is applied.

Anodic Polarization

The change in the initial anode potential resultingfrom current ow effects at or near the anode sur-face. Potential becomes mode noble (more posi-tive) because of anodic polarization.

Anodic Potential

An appreciable reduction in corrosion by makinga metal an anode and maintaining this highlypolarized condition with very little current ow.

Anodic Protection

A technique to reduce corrosion of a metal sur-face under some conditions, by passing sufcientanodic current to it to cause its electrode potentialto enter and remain in the passive region.

Anodic Reaction

Electrode reaction equivalent to a transfer ofpositive charge from the electronic to the ionicconductor. An anodic reaction is an oxidationprocess. An example common in corrosion is:Me ~ Me n+ + ne.

Anodizing

Forming a conversion coating on a metal surfaceby anodic oxidation; most frequently applied toaluminum.

Anolyte

The electrolyte adjacent to the anode in an elec-trolytic cell.

Antagonism

Detrimental interaction between two entities.

Antecedent Moisture Content

The moisture content of a soil prior to a rainfall

event. It has an important inuence on the likeli-hood of runoff occurring as a result of subsequentrainfall, because antecedent moisture restricts theamount of inltration which can take place.

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Anthric Saturation

Variation of episaturation associated with con-trolled ooding, which causes a reduced environ-ment in a soil layer and oxidation of mobilizediron and manganese in a deeper unsaturatedsubsoil.

Anthropogenic

Made by people or resulting from human activi-ties. Usually used in the context of emissions thatare produced as a result of human activities.

Anti-Abrasive Coating

Cushioning material applied where insulationcontacts the pipe, duct, vessel or adjacent insula-tion to prevent eroding of either or both.

Antichlors

Reagents, such as sulfur dioxide, sodium bisul-te, and sodium thiosulfate, that can be used toremove excess chlorine residuals from water orwatery wastes by conversion to an inert salt.

Anticorrosion Treatment

Treatment to reduce or eliminate corrosion-producing qualities of a water.

Ant Degradation

Policies which ensure protection of water qual-ity for a particular water body where the waterquality exceeds levels necessary to protectsh and wildlife propagation and recreation onand in the water. This also includes special pro-tection of waters designated as outstanding natu-

ral resource waters. Antidegradation plans areadopted by each state to minimize adverseeffects on water.

Anti-Fouling

Intended to prevent fouling of under-water struc-tures, such as the bottoms of ships; refers to theprevention of marine organism’s attachment orgrowth on a submerged metal surface, generallythrough chemical toxicity caused by the compo-sition of the metal or coating layer.

Antipitting Agent

An addition agent for electroplating solutions toprevent the formation of pits or large pores in theelectrodeposit.

Anti-Siphon Device

Any device in a supply line designed to returnpressure to atmospheric conditions in orderto prevent undesired water movement (such aswater siphoning out of pump tank); includesvalves, vent holes, spit tubes, etc.

Anti-Vortex Device

A device, usually a vertical or horizontal plate,placed at the entrance of a pipe to prevent the for-mation of a vortex (whirlpool effect) in the waterat the pipe entrance.

An Open Dump

An open dump is a facility that does not meet thecriteria for a sanitary landll and is not a facilityfor disposal of hazardous waste.

ANSI

The American National Standards Institute, theprivate non-prot organization that administrates

and coordinates the U.S. private-sector voluntarystandardization system. It is the US memberorganization of ISO.

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APCD

Air Pollution Control District. Here, the Louis-ville Metro Air Pollution Control District (alsoknown as the Air Pollution Control District ofJefferson County).

APCDJC

The Air Pollution Control District of JeffersonCounty (Kentucky), now called the LouisvilleMetro Air Pollution Control District.

Apedal

Describes a soil in which none of the soil materialoccurs in the form of peds in the moist state. Sucha soil is without apparent structure and is typi-cally massive or single grained. When disturbedit separates into primary particles or fragmentswhich may be crushed to primary particles.

Apparent Contrast

Contrast at the observer of a target with respect tosome background, usually an element of horizonsky directly above the target.

Appropriation Doctrine

The system for allocating water to private indi-

viduals used in most Western states. The doctrineof Prior Appropriation was in common usethroughout the arid west as early settlers andminers began to develop the land. The priorappropriation doctrine is based on the concept of“First in Time, First in Right.” The rst person totake a quantity of water and put it to BenecialUse has a higher priority of right than a subse-quent user. Under drought conditions, higher pri-ority users are satised before junior users

receive water. Appropriative rights can be lost

through non-use; they can also be sold ortransferred apart from the land. Contrasts withRiparian Water Rights.

Appurtenances Machinery

Appliances, or auxiliary structures attached to amain structure enabling it to function, but notconsidered an integral part of it.

Apron

A layer of concrete, stone, timber, or other rela-

tively permanent material placed at the entranceor outlet of a hydraulic structure, such as a cul-vert or chute, in the channel bed, to protect thestructure against erosion.

Aquaculture

The controlled rearing of sh or shellsh by peo-ple or corporations who own the harvestable

product, often involving the capture of the eggsor young of a species from wild sources, fol-lowed by rearing more intensively than possiblein nature.

Aquatic Bench

A 10–15 foot wide bench around the inside perim-eter of a permanent pool that ranges in depth from

0 to 12 inches—vegetated with emergent plants, itaugments pollutant removal, provides habitats,protects the shoreline from the effects of waterlevel uctuations and enhances safety.

Aqueduct

A pipe, conduit, or channel designed to trans-port water from a remote source, usually by

gravity.

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Aqueous

Pertaining to water; an aqueous solution is awater solution.

Aqueous Vapor

The gaseous form of water. See WATER VAPOR.

Aquic Moisture Regime

Primarily reducing soil moisture regime nearlyfree of dissolved oxygen due to saturation bygroundwater or its capillary fringe and occurringduring periods when the soil temperature 50 cm(20 inches) below the surface is greater than5 °C (41 °F).

Aquic Conditions

Continuous or periodic saturation and reductionindicated by redoximorphic features and veried

by measuring saturation and reduction of the soil.

Aquifer

A geologic formation capable of transmitting sig-nicant quantities of groundwater under normalhydraulic gradients. Water-bearing formation

(bed or stratum) of permeable rock, sand, orgravel capable of yielding signicant quantitiesof water. An underground geological formationor group of formations containing usable amountsof groundwater that can supply wells and springs.

Aquifer (Conned)

Soil or rock below the land surface that is satu-rated with water. There are layers of imperme-able material both above and below it and it isunder pressure so that when the aquifer is pene-trated by a well, the water will rise above the topof the aquifer (Fig. 4 ).

Aquifer (Unconned)

An aquifer whose upper water surface (watertable) is at atmospheric pressure, and thus is ableto rise and fall (Fig. 5 ).

Aquifer

A porous soil or geological formation, oftenlying between impermeable sub-surface strata,which holds water and through which water canpercolate slowly over long distances and whichyields ground water to springs and wells. Aquifersmay, however, be unconned and the water levelsubject to seasonal inow. An AQUITAnO is also

Fig. 4 Conned aquifer

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a groundwater bearing formation but is insuf-ciently permeable to transmit and yield water inusable quantities.

Aquifer Compaction

The reduction in the porosity (pore spaces) of anaquifer, and may result from over pumping theaquifer.

Aquifer License

A licence granting access to using an amount ofwater from an aquifer.

Aquitard

A geologic formation that may contain ground-water but not capable of transmitting signicantquantities of groundwater under normal hydrau-lic gradients.

Area DrainA drain installed to collect surface or stormwaterfrom an open area of a building.

Area Sources

Those sources for which a methodology is usedto estimate emissions. This can include area-wide, mobile and natural sources, and alsogroups of stationary sources (such as dry clean-ers and gas stations). The federal air toxics pro-

gram denes a source that emits less than 10 tonsper year of a single hazardous air pollutant(HAP) or 25 tons per year of all HAPs as an areasource.

Area-Wide Sources

Sources of pollution where the emissions arespread over a wide area, such as consumer prod-ucts, replaces, road dust and farming opera-tions. Area-wide sources do not include mobilesources or stationary sources.

Areal Fill

Above-grade soil treatment area designed andinstalled such that the entire inltrative surface islocated above the original ground elevation usingsuitable imported soil material for ll; utilizes

gravity, pressure-dosed gravity or low-pressuredistribution; a nal cover of suitable soil stabilizesthe completed installation and supports vegetativegrowth.

Fig. 5 Unconnedaquifer

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Arid (ram)

Refers to climates or regions which lack sufcientrainfall for crop production or extensive sownpastures. Usually dened as a climate with annualaverage rainfall less than 250 mm (10 inches).

Armouring

The process of development of a layer of coarseparticles on the surface of a soil which is capableof protecting the soil below from wind or owingwater.

Armouring Layer

A layer of particles, som

[dictionary] of environmental engineering and wastewater treatment

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