Aquatic Chemistry: For Water and Wastewater Treatment Applications

266 Pages·2019·3.544 MB·English

by  Ori Lahav, Liat Birnhack

OriLahav,LiatBirnhack
AquaticChemistry
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Ori Lahav, Liat Birnhack
Aquatic Chemistry
For Water and Wastewater Treatment Applications
Authors
Prof.OriLahav
DepartmentofEnvironmental,WaterandAgricultural
Technion–IsraelInstituteofTechnology
32000Haifa,Israel
[email protected]
GuangdongTechnionIsraelInstituteofTechnology(GTIIT)
DrLiatBirnhack
FacultyofCivilandEnvironmentalEngineering
Technion–IsraelInstituteofTechnology
32000Haifa,Israel
[email protected]
ISBN978-3-11-060392-7
e-ISBN(PDF)978-3-11-060395-8
e-ISBN(EPUB)978-3-11-060409-2
LibraryofCongressControlNumber:2018965709
BibliographicinformationpublishedbytheDeutscheNationalbibliothek
TheDeutscheNationalbibliothekliststhispublicationintheDeutscheNationalbibliografie;
detailedbibliographicdataareavailableontheInternetathttp://dnb.dnb.de.
©2019WalterdeGruyterGmbH,Berlin/Boston
Typesetting:IntegraSoftwareServicesPvt.Ltd.
Printingandbinding:CPIbooksGmbH,Leck
Coverimage:Dimitris66v/iStock/GettyImagesPlus
www.degruyter.com
Preface
Wearehappytointroducethistextbook,whichistheculminationofmanyyearsof
teaching and research in the fields of aquatic chemistry and water treatment pro-
cessdevelopment.
The textbook was written not only with both university-level undergraduate
andgraduate studentsin mind,but also to serveas a toolfor water, chemicaland
environmentalengineersintheirquestforcorrectandoptimaldesignandinterpre-
tationofphenomenaoccurringintheaqueousphase.
The bookdiffers frommostother water-chemistry-relatedbooksinthemethod
developedandadoptedforproblem-solvingandforthedesignofengineeredwater
treatment systems. The main idea throughout the text is to employ mass balances
onconservativeparameters(e.g.,alkalinityandacidityspecies)inordertocompute
thevaluesofnon-conservativeparameters(e.g.,pH,theconcentrationofindividual
weak acid/base species) thereby solving most of the issues related to weak acid
waterquality,whetherinnaturalorengineeredsystems.Thedatarequiredforsolv-
ingalltheproblemspresentedinthebookcanbeobtainedbyrelativelysimplean-
alyticalprocedures,andthesolutionsdonotrequirestrongcomputingabilities.
Thebookstarts(Chapters1and2)byrecitingclassicalaquaticchemistrymate-
rial, then shifts to the definition of conservative weak acid/base parameters (alka-
linity/acidityintheirvarious manifestations)intheaqueous,gas andsolidphases
(Chapters3to6)andthentothetechniquesbywhichtheyareusedtoobtaininfor-
mation on the water quality and design water treatment processes (e.g., mixing of
streams, softening, remineralization) (Chapter 8 and 9). The book also introduces
(Chapter 7) a free computerized tool (the software “Stasoft”) as an easy tool to de-
sign and simulate processes occurring in the aqueous phase upon the dosage of
chemicals and the interaction between the aqueous, solid and gas phases. The
bookfinisheswithacomprehensivequestionsandanswerssession,whichencom-
passesthewholerangeofmaterialscoveredinthetext.
We wish to thank De Gruyter for giving us a venue for publishing this book,
whichwebelieveisimportanttoanywaterandenvironmental/chemical-engineer-
ing professional. We also wish to thank Guangdong Technion Israel Institute of
Technology (GTIIT) and the Technion International School (TI) for their financial
supportandMrYehudaCohen(B.Sc.inEnvironmentalEngineering)forhisinvalu-
ableworkineditingandtranslatingapartofthistext,whichoriginallyappearedin
Hebrew.DrLahavwouldwantalsotothankthelateProf.RichardLoewenthalfrom
the University of Cape Town for his invaluable contribution in making aquatic
chemistrysciencewhatitistoday.
Wehopeyouwillfindthistextbothinterestingandeducative.
Prof.OriLahav
DrLiatBirnhack
April2019
https://doi.org/10.1515/9783110603958-201

Contents
Preface V
1 Waterchemistryfundamentals 1
1.1 Introduction 1
1.2 Solutions 1
1.3 ThechemicalstructureoftheH Omolecule 1
2
1.4 Dissolution 2
1.5 Solubility 2
1.6 Electrolytesandnon-electrolytes 3
1.7 Expressingsoluteconcentrationsinenvironmental
engineering 4
1.8 Weightfraction(massperunitmass) 5
1.9 Weightpervolume 5
1.10 Molarity(M) 6
1.11 Normality(N=eq/L) 6
1.12 Weightpervolumeexpressedasadifferentsubstance
(units:g/LasX) 8
1.13 Thep-notation 10
1.14 Chemicalequilibrium 11
1.15 Thekineticapproachfordescribingchemicalequilibrium 11
1.16 Adjustingtheequilibriumconstanttoanon-idealsystem 13
1.17 Acid–baseequilibriumintheaqueousphase 16
1.18 Thethermodynamicapproachfordescribingchemical
equilibrium 19
1.19 Standardfreeenergyofformation 21
1.20 DeterminingΔGundernon-standardconditions 22
1.21 Temperatureeffectontheequilibriumconstantvalue 24
2 Acidsandbases 27
2.1 Introduction 27
2.2 Basicprinciples 27
2.2.1 Definingacidsandbases 27
2.3 Acid-basepairs 29
2.4 Polyproticacids 30
2.5 Thecarbonatesystem 30
2.6 Thestrengthofanacidorbase 32
2.7 TheHenderson–Hasselbalchequation 36
2.8 Speciesdistributionofweak-acids/basesasafunctionofpH 38
2.8.1 SpeciesconcentrationasafunctionofpH–thegraphical
approach 42
VIII Contents
2.8.2 Sketchingthelog(species)curveasafunctionofpH–aquick
procedure 46
2.8.3 Sketchingthelog(species)curveasafunctionofpH–important
points 47
2.9 Theeffectofachangeinthetotalspeciesconcentration,C 48
T
2.10 Interpretingacid/basesystemsusingprotonbalance
equations 48
2.11 Equivalentsolutionsandequivalencepoints 54
2.11.1 H A –theequivalencepointofH A 55
2 EP 2
2.11.2 HA− –TheequivalencepointofHA− 57
EP
2.11.3 A−2 –theequivalencepointofA−2 59
EP
2.12 Buffercapacity 62
2.13 Graphicalmethodforsolvingproblems 63
3 Alkalinityandacidityastoolsforquantifyingacid-baseequilibrium
anddesigningwaterandwastewatertreatmentprocesses 67
3.1 Introduction 67
3.2 Alkalinityandacidity–definitions 67
3.2.1 Firstverbaldefinition 68
3.2.2 Secondverbaldefinition 68
3.3 Developmentofalkalinityandacidityequationsformonoprotic,
weak-acid(weak-base)systems 70
3.3.1 Developinganequationforthealkalinityofamonoprotic,weak
acidwithHAasthereferencespecies 70
3.3.2 Derivinganequationfortheacidityofamonoprotic,weakacid
withA−asthereferencespecies 72
3.3.3 Generalizationandelaborationoftheconceptsalkalinityand
acidityandtherelationshipsbetweenthemforamonoprotic
weakacid 73
3.3.4 Introductiontomeasuringalkalinityandacidityinthe
laboratory 74
3.4 Developingequationsforthedescriptionofalkalinityandacidity
valuesofdiproticweak-acidsystems 75
3.5 Thecarbonatesystemasanexampleofadiproticsystem 75
3.5.1 Developingalkalinityandacidityequationswithrespecttothe
equivalencepointofH CO * 76
2 3
3.5.2 Developingalkalinityandacidityequationsaroundthe
equivalencepointofHCO − 78
3
3.5.3 Developingthealkalinityandacidityequationsaroundthe
equivalencepointofCO 2− 79
3
3.5.4 Usefulnotesaboutthecarbonatesystemandusefulrelationships
betweenthevaluesofpH,alkalinity,acidityandC 80
T
Contents IX
3.6 Determiningalkalinityandacidityvaluesinthelab:
Characterizationofacid–baserelationshipsinnaturalwaters 82
3.7 Standardlaboratoryalkalinityanalysis 83
3.8 MoreonwatercharacterizationthroughanalysisofC and
T
additionalformsofalkalinityandacidity 84
3.9 Buffercapacityofsolutions 85
3.9.1 Buffercapacityorbufferintensity 85
3.9.2 Derivingthebuffercapacityequationforamonoprotic,weak
acid 86
3.9.3 Expansiononthederivationofβtoincludediproticand
polyproticsystemsusingthecarbonatesystemasanexamplefor
polyproticsystems 88
3.10 Titrationcurves 89
3.11 Alkalinityandacidityequationscomposedofseveralweak-acid
systems 92
3.12 Elaborationonlaboratorymethodsformeasuringalkalinityand
acidity 95
3.12.1 Grantitrationfordeterminingalkalinity 97
3.12.2 MathematicalderivationoftheGranmethod 98
4 Useofalkalinityandacidityequationsforquantifyingphenomenain
chemical/environmentalengineeringanddesignofwaterand
wastewatertreatmentprocesses 101
4.1 Theoreticalbackgroundrelatedtoacid-basecalculationsin
aqueoussolutionsfromtheknowledgeofalkalinityandacidity
parameters 101
4.2 Examplesofacid-baseproblemsfromchemical/environmental
engineeringinwhichalkalinityandaciditytermscanbeused 104
4.3 Examplesforimplementationoftheprinciplesofthecalculation
methodforsolvingproblemsrelatedtowastewater 111
4.4 Usingamethodbasedonalkalinityandaciditymassbalancesto
quantifythechangeincharacterizationofacid-basepropertiesof
waterasaresultofchemicaldosage(deliberateor
unintentional) 117
4.4.1 Solutionoutline 118
5 Equilibriumbetweentheaqueousandgasphasesandimplications
forwatertreatmentprocesses 125
5.1 Introduction 125
5.2 Expressionsdescribingconcentrationsofcomponentsinthegas
phase 126
5.3 Henry’slaw 127
X Contents
5.4 Factorsaffectinghenry’slawconstant 130
5.4.1 TheeffectofthesolutionIonicstrengthonHenry’sconstant 131
5.5 Systemsthatareclosedtotheatmosphere 132
5.6 Thecarbonatesysteminthecontextofgas-liquidphase
equilibriumequations 133
5.7. DistributionofspeciesasafunctionofpHforsystemsthatarein
equilibriumwiththegasphase 137
6 Principlesofequilibriumbetweentheaqueousandsolidphaseswith
emphasisonprecipitationanddissolutionofCaCO 145
3(S)
6.1 Introduction 145
6.2 TheeffectofIonicstrengthonthesolubilityconstants 147
6.3 Effectoftemperatureonthesolubilityconstant 148
6.4 Effectoftheadditionofoneofthesolidcomponentsonthe
concentrationoftheothercomponentinequilibrium(common
ioneffect) 148
6.5 Effectofsidereactionsonsolubilityofsolids 150
6.6 Precipitation/dissolutionofCaCO :qualitativeandquantitative
3
assessmentofthesaturationstate 151
6.6.1 Langeliersaturationindex(LSI) 151
6.6.1.1 MathematicaldevelopmentoftheformulaforcalculatingpH 151
L
6.6.1.2 TheinherentproblemsintheLangeliermethod 152
6.6.2 PrecisequantificationofCaCO precipitation/dissolution
3
potential(CCPPmethod) 153
6.6.3 Determinationoftheprecipitationpotential(numericalmethod) 154
6.6.4 ComparisonofLSIvaluesandCCPPinagivensolution 155
6.6.5 Determiningtheprecipitationpotential(CCPP)graphically 156
6.6.5.1 ModifiedCaldwell–Lawrence(MCL)diagrams 156
6.6.5.2 MCLgraphdevelopment 156
7 Computersoftwareforcalculationsinthefieldofaquaticchemistry
andwatertreatmentprocesses,withanemphasisontheStasoft4.0
program 163
7.1 Introduction 163
7.2 Principlesofcalculationandlimitations 163
7.3 Howtousethesoftware 165
7.4 SimulationofwatertreatmentprocessesusingtheStasoft4
program 174
8 Watersofteningusingthelime-sodaashsofteningmethod 179
8.1 Introduction 179