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8FORMULAEDIGESTTheWaterTreatmentHandbookwasoriginallycompiledtoprovidebothwatertreatmentengineersandtechnicianswithbasicdataandpracticalinformationmostfrequentlyrequiredon-site.Watertreatmentengineeringcallsforincreasinglyspecializedanddiversifiedknowledge,yetthereisstilladefiniteneedforadigestofbasicinformationandsimplenumericorgraphicdatamostfrequentlyusedbytechnicians,particularlywhenworkingonrushedprojectsorduringstart-upoperations.TheFormulaeDigestsetsouttomeetthisneed,althoughitisdifficulttosetclearlimitstoitscontents,whichshouldremainconcise:forexample,thedefinitionofelementarygeometricvolumescouldbeusefulfordeterminingthecapacityofareagentstoragetank;reiteratingcertainessentialregulatoryprovisionsregardingwastewaterdischargecouldbeofusetothesitemanagerwhomaynotbefamiliarwithcertainregulations,etc.Tosomereaders,thisdigestwillnodoubtseemincomplete,whileotherswillfeelitcontainstoomanyuniversallyknownbasicfacts.TheDigestaimstobeofhelptothelargestpossiblenumberofHandbookusers.Itissimplyatoolkit,foreachtouseaccordingtotheirparticularrequirements.Chap.8:Formulaedigest1.UNITSOFMEASUREMENT1.1.SYSTEMSOFUNITSSystemsofunitsderivedfromthemetricsystemhavegraduallybeenreplacedbyasinglesystemtermedtheInternationalSystemofUnits(SI),presentedinthefirstpartofthissub-chapter.Thecgs(centimetre-gramme-second)system,inwhichmostunitscorrespondtodecimalmultiplesorsub-multiplesoftheInternationalSystem,stillhasadvantagesincertainfields.AsmanycountriesstillpersistinusingBritishorUSsystemsofunits,thesecondpartofthischapterliststheequivalentvaluesoftheBritish/USandSIsystemsofunits.poses,affectwatertreatment.ThefirstofthesetablesaretakenfromdocumentspublishedbytheAFNOR(FrenchStandardsCommittee)andparticularlyfromtheInternationalSystemsummarytableinaccordancewithdocumentationitemNo.NFX02-004.Note:ExtractsfromtheAFNORstandardsincludedinthisdocumenthavebeenreproducedwiththeauthorizationoftheFrenchStandardsCommitteeAFNOR-AssociationFrançaisedeNormalisation(address:TourEurope,Cedex7,92080ParisLaDefense,France)-whichshouldbeaddressedifcompletedocumentsarerequired,asonlyoriginalversionsofstandardsintheirmostrecenteditionscanbeconsideredvalid.1.1.1.TheInternationalSystemofUnits(SI)Thissystem,graduallyacceptedandimprovedbytheeffortsoftheGeneralConferencesonWeightsandMeasures(GCWM)andtheInternationalCommitteeonWeightsandMeasures(ICWM),comprisesbaseunits,derivedunits,andsupplementaryunits.Itsapplicationinvolvesdecimalmultiplesandsub-multiples,withthecorrespondingprefixes.Besidestheunitslistedbelow,itadmitsunitscalledcommonunitsdefinedintermsofSIunitsandtemporarilyacceptedunits.Inprinciple,itdiscouragestheuseofcgsandotherunits.TheInternationalSystemtablesbelowrelatetounitswhich,forvariouspur-1.1.2.GeneralprinciplesUnitsymbols:writingrulesUnitsymbolsareonlyusedafteranumberexpressedinfigures..Theyareprintedinstraightcharacters,areinvariableintheplural,writtenwithoutfinalperiodandplacedaftercompletenumericvalues,leavingaspacebetweenthenumericvalueandthesymbol.Theyarewritteninsmallletters;however,thefirstletterisacapitalwhenthenameoftheunitisderivedfromapropernoun.Thereshouldbenomorethanonefractionlineonthesamelinetorepresentacompositeunitthatisthequotientoftwounits,unlessparenthesesareusedtoavoidanyambiguity.1.Unitsofmeasurement.BaseunitsQuantityUnitnameUnitsymbol.lengthmetrem.masskilogrammekg.timeseconds.electriccurrentintensityampereA.absolutetemperaturekelvinK.amountofsubstancemolemol.luminousintensitycandelacdNOTE:CelsiustemperaturetisrelatedtoabsolutetemperatureTbytheequivalencet=T273.15.ThedifferencebetweentwotemperaturescanbeexpressedeitherinkelvinsorindegreesCelsius.Inthiscase,1°C=1K.Supplementaryunits(Thesecanbeusedasbaseunits.)QuantityUnitnameUnitsymbolplaneanglesolidangleradiansteradianradsr.Multiplesandsub-multiplesPowerPrefixSymbol1018exaE1015petaP1012teraT109gigaG106megaM103kilok102hectoh10decada10-1decid10-2centic10-3millim10-6microμ10-9nanon10-12Picop10-15femtof10-18attoa1.1.3.Definitionofbaseunitsandsupplementaryunits.BaseunitsMetre:themetreisthelengthequalto1,650,763.73timesthewavelength,inavacuum,oftheradiationcorrespondingtothetransitionbetweenlevels2pl0and5d5ofanatomofkrypton-86.Kilogramme:thekilogrammeistheunitofmass;itisequaltothemassoftheinternationalprototypekilogramme.Second:thesecondisthedurationof9,192,631,770periodsoftheradiationcorrespondingtothetransitionbetweenthetwohyperfinelevelsofthegroundstateofanatomofcesium-133.Ampere:theampereistheintensityofaconstantelectriccurrentwhich,maintainedintwoparallel,rectilinearconductorsofinfinitelengthandnegligiblecircularcross-section,placedatadistanceof1metrefromeachotherinavacuumwouldproduceaforceequalto2x10-inewtonspermetreoflengthbetweentheseconductors.Kelvin:thekelvinisaunitofabsolutetemperatureequalto1/273.15oftheabsolutetemperatureofthetriplepointofwater.Chap.8:FormulaedigestMole:themoleistheamountofsubstanceofasystemcontainingasmanyelementaryunitsasthereareatomsin0.012kilogrammeofcarbon-12.Whenusingthemole,theelementaryunitsmustbespecifiedandmaybeatoms,molecules,ions,