1、BRITISH STANDARD BS EN 12255-13:2002 Wastewater treatment plants Part 13: Chemical treatment Treatment of wastewater by precipitation/flocculation The European Standard EN 12255-13:2002 has the status of a British Standard ICS 13.060.30 BS EN 12255-13:2002 This British Standard, was published under
2、the authority of the Standards Policy and Strategy Committee on 24 July 2003 BSI 24 July 2003 ISBN 0 580 42318 2 National foreword This British Standard is the official English language version of EN 12255-13:2002. The UK participation in its preparation was entrusted to Technical Committee B/505, W
3、aste water engineering, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the B
4、SI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for
5、 its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK inte
6、rests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 14, an inside back cover and a back cover. The BSI copyright notice displayed in this do
7、cument indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM EN1225513 December2002 ICS13.060.30 Englishversion WastewatertreatmentplantsPart13:Chemicaltreatment Treatmentofwastewaterbyprecipitation/flocc
8、ulation StationsdpurationPartie13:Traitementchimique Traitementdeseauxusesparprcipitation/flocculation KlranlagenTeil13:ChemischeBehandlung AbwasserbehandlungdurchFllung/Flockung ThisEuropeanStandardwasapprovedbyCENon1November2002. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhich
9、stipulatetheconditionsforgivingthisEurope an Standardthestatusofanationalstandardwithoutanyalteration.Uptodatelistsandbibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicationtotheManagementCentreortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,F
10、rench,German).Aversioninanyotherlanguagemadebytra nslation undertheresponsibilityofaCENmemberintoitsownlanguageandnotifiedtotheManagementCentrehasthesamestatusasthe official versions. CENmembersarethenationalstandardsbodiesofAustria,Belgium,CzechRepublic,Denmark,Finland,France,Germany,Greece, Icelan
11、d,Ireland,Italy,Luxembourg,Malta,Netherlands,Norway,Portugal,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2002CEN Allrightsofexploitationinanyformandbyanymeansreser
12、ved worldwideforCENnationalMembers. Ref.No.EN1225513:2002EEN1225513:2002(E) 2 Contents page Foreword3 1 Scope 4 2 Normativereferences 4 3 Termsanddefinitions. .4 4 Requirements .5 4.1 General5 4.2 Chemicalbackgroundandprocessoptions. 5 4.2.1 Chemicalprocess 5 4.2.2 Precipitationprocesses . .6 4.2.3
13、Selectionofprecipitationchemicals .7 4.3 Storageofchemicals .7 4.3.1 General7 4.3.2 Aluminumsalts 8 4.3.3 Ironsalts .8 4.3.4 Calciumsalts. .8 4.4 Dosingequipment 8 4.4.1 General8 4.4.2 Aluminiumsalts . 9 4.4.3 Ironsalts .9 4.4.4 Calciumsalts. .9 4.5 Silosandtanks. 10 4.6 Mixingsystems 10 4.7 Floccul
14、ators10 4.8 Sedimentationtanks. .10 4.8.1 General10 4.8.2 Designconsiderations . .10 4.8.3 Chemicalsludgewasting. .10 4.9 Flotation10 4.10 Physicalfiltration .11 4.11 Sludge .11 4.11.1 Sludgeproduction .11 4.11.2 Sludgecharacteristics. 11 AnnexA (normative) Precipitationchemicals 12 A.1 Aluminiumsal
15、ts . 12 A.2 Ironsalts .12 A.2.1 Ferroussalts. 12 A.2.2 Ferroussulphate,monohydrate. 12 A.2.3 Ferroussulphate,heptahydrate .12 A.2.4 Ferricsalts 12 A.3 Calciumsalts. .13 A.3.1 General13 A.3.2 Calciumoxide. 13 A.3.3 Calciumhydroxide. 13 Bibliography 14EN1225513:2002(E) 3 Foreword Thisdocument(EN122551
16、3:2002)hasbeenpreparedbyTechnicalCommitteeCEN /TC 165“Wastewater engineering“,thesecretariatofwhichisheldbyDIN. ThisEuropeanStandard shallbegiventhestatusofanationalstandard,eitherbypublicationofanidenticaltextor byendorsement,atthelatestbyJune2003,andconflictingnationalstandardsshallbewithdrawnatth
17、elatestby June2003. ItisthethirteenthpartpreparedbytheWorkingGroupsCEN/TC165/WG42and43relatingtothegeneral requirementsandprocessesforwastewatertreatmentplantsforatotalnumberofinhabitantsandpopulation equivalents(PT)over50.Thepartsoftheseriesareasfollows: Part1:Generalconstructionprinciples Part3:Pr
18、eliminarytreatment Part4:Primarysettlement Part5:Lagooningprocesses Part6:Activatedsludgeprocess Part7:Biologicalfixedfilmreactors Part8:Sludgetreatmentandstorage Part9:Odourcontrolandventilation Part10:Safetyprinciples Part11:Generaldatarequired Part12:Controlandautomation Part13:ChemicaltreatmentT
19、reatmentofwastewaterbyprecipitation/flocculation Part14:Disinfection Part15:Measurementoftheoxygentransferincleanwaterinactivatedsludgeaerationtanks Part16:Physical(mechanical)filtration 1) NOTE Forrequirementsonpumpinginstallationsatwastewatertreatmentplants,providedinitiallyaspart2“Pumping install
20、ationsforwastewatertreatmentplants“,seeEN7526“DrainandsewersystemsoutsidebuildingsPart6:Pumping installations. ThepartsEN122551,EN122553toEN122558andEN1225510andEN1225511wereimplemented togetherasaEuropeanpackage(ResolutionBT152/1998). WARNING TheuseofthisEuropeanStandardmayinvolvehazardousmaterials
21、,operationsand equipment.ThisEuropeanStandarddoesnotpurporttoaddressallofthesafetyproblemsassociatedwith itsuse.ItistheresponsibilityoftheuserofthisEuropeanStandardtoestablishappropriatesafetyand healthpracticesanddeterminetheapplicabilityofregularitylimitationspriortouse(seealsoEN1225510). AnnexAis
22、normative. AccordingtotheCEN/CENELECInternalRegulations,thenationalstandardsorganizationsofthefollowing countriesareboundtoimplementthisEuropeanStandard:Austria,Belgium,CzechRepublic,Denmark,Finland, France,Germany,Greece,Iceland,Ireland,Italy,Luxembourg,Malta,Netherlands,Norway,Portugal,Spain, Swed
23、en,SwitzerlandandtheUnitedKingdom. 1) inpreparationEN1225513:2002(E) 4 1Scope ThisEuropeanStandardspecifiestherequirementsforchemicaltreatmentofwastewaterby precipitation/flocculationforremovalofphosphorusandsuspendedsolids. TheapplicationofpolymersisnotdescribedinthisEuropeanStandard. Differencesin
24、wastewatertreatmentthroughoutEuropehaveledtoavarietyofpracticesbeingdeveloped.This standardgivesfundamentalinformationaboutthepractices;thisstandardhasnotattemptedtospecifyallavailable practices. Detailedinformationadditionaltothatcontainedinthisstandardmaybeobtainedbyreferringtothebibliography. 2 N
25、ormativereferences ThisEuropeanStandardincorporatesbydatedorundatedreference,provisionsfromotherpublications.These normativereferencesarecitedattheappropriateplacesinthetext,andthepublicationsarelistedhereafter.For datedreferences,subsequentamendmentstoorrevisionsofanyofthesepublicationsapplytothisE
26、uropean Standardonlywhenincorporatedinitbyamendmentorrevision.Forundatedreferencesthelatesteditionofthe publicationreferredtoapplies(includingamendments). EN7526, DrainandsewersystemsoutsidebuildingsPart6:Pumpinginstallations. EN1085:1997, WastewatertreatmentVocabulary. EN100882, StainlesssteelsPart
27、2:Technicaldeliveryconditionsforsheet/plateandstripforgeneralpurposes. EN122551, WastewatertreatmentplantsPart1:Generalconstructionprinciples. EN122556, WastewatertreatmentplantsPart6:Activatedsludgeprocess. EN1225511, WastewatertreatmentplantsPart11:Generaldatarequired. EN12518:2000, Chemicalsusedf
28、ortreatmentofwaterintendedforhumanconsumptionHighcalciumlime. 3 Termsanddefinitions ForthepurposesofthisEuropeanStandard,thetermsanddefinitionsgiveninEN1085:1997andEN12518:2000 andthefollowingapply. 3.1 chemicaltreatmentofwastewater treatmentofwastewaterbychemicalcoagulation/precipitationwithmetalsa
29、lts(includinglime)ororganicpolymers inordertoremoveinorganicandorganicphosphoruscompoundsandsuspendedsolidsandcolloidsEN1225513:2002(E) 5 4Requirements 4.1General Chemicaltreatmentofwastewatercanbedividedintotwoprocesses:areactionphase,thatconsistsof precipitationofdissolvedphosphates,destabilisatio
30、nofcolloidsandtheformationofflocs,andaseparationphase, inwhichtheflocsareseparatedfromthewater. Thereactorsandflocseparators(sedimentationtanks,flotationunitsetc.)forthechemicaltreatmentcanbe integratedwiththeotherpartsofthewastewatertreatmentplant(preprecipitation,simultaneousprecipitation,see 4.2.
31、2.2and4.2.2.3)orbeaseparatepartofthetreatmentplant(postprecipitation,directprecipitation). Thewaterlevelinthechemicalreactorsandtanksmaybecontrolledbyfixedoradjustableweirs.Itisparticularly importantwheretherearemultipleparallelreactors. Thedesignoftheprocessshalltakeintoaccountvariationsinflowandlo
32、adasstipulatedinEN122551and EN1225511. 4.2 Chemicalbackgroundandprocessoptions 4.2.1 Chemicalprocess Inordertoobtaincoagulation/precipitationacationicchemicalhastobeaddedtothewastewater.Mostcommonly thisisasaltofaluminiumoriron.Limemayalsobeused.Ifonlycoagulation(removalofparticles)isaimedat,a catio
33、nicpolymermaybeaddedaloneorinadditiontoametalsalt. Phosphoruscanbepresentinthewastewaterinthefollowingforms: a) organicallyboundphosphorus, b)inorganic phosphorus, polyphosphate, orthophosphate. Polyphosphatesareeventuallyconvertedtoorthophosphatesandtheorganicallyboundphosphorusisconverted toorthop
34、hosphateduringbiologicaltreatment. Inprimarytreatment,phosphorusfixedtosettleableparticlesisremoved(5 %to15 %ofthetotalinfluent phosphorusdependingonthecharacterofthewastewater).Inthebiologicaltreatmentacertainamountof phosphorusisconsumedatthemicrobialsynthesisofnewcellularmaterial(10 %to30 %ofthei
35、nfluent phosphorus).Byintroducingananaerobicstagewherevolatilefattyacidsareproducedandphosphatesare releasedanincreasedbiologicalremovaloftotalphosphoruscanbereachedwithoutadditionofchemicals (60%to90%oftheinfluentconcentration). Inthechemicalprecipitation,aprecipitationagent(suchasaluminiumsulphate
36、,ferroussulphate,ferricchlorideor calciumhydroxide)isaddedtothewastewater.Theorthophosphatephosphorusisprecipitatedasmetal orthophosphate.Al 3+ andFe 3+ alsoformcolloidalhydroxides.ThesolubilityoftheprecipitatesispHdependent. Organicpolyelectrolytesareusedasflocculationagentsforcolloidalandsuspended
37、matter. Chemicalcoagulation/precipitationcanbecarriedoutinsixdifferentways,namely direct precipitation, preprecipitation,EN1225513:2002(E) 6 simultaneous precipitation, postprecipitation, multipoint precipitation, precipitation on filters. 4.2.2 Precipitationprocesses 4.2.2.1 Directprecipitation Dir
38、ectprecipitationisusedinwastewatertreatmentplantswithoutabiologicalstage. Inadirectprecipitationplant,theprecipitationagentshouldbeaddedafterthepreliminarystage(screen,grit chamberandpossiblyaprimarysettlementtank). Theprecipitationagentshouldbeaddedinawaythatassuresrapidandcompletemixingofthechemic
39、al. Aftermixingflocculationtakesplaceinaflocculationtank.Thechemicalflocsarethenseparatedinafinal sedimentationtankoranotherflocseparationdevice. 4.2.2.2Preprecipitation Preprecipitationcanbeusedinwastewatertreatmentplantshavingbothmechanicalandbiologicaltreatment. Withpreprecipitation,theadditionof
40、theprecipitationagentiseffectedbeforethebiologicalstage,oftenbeforethe aeratedgritchamber,preaerationtanks,orflocculationtanks.Thechemicalflocsareseparatedtogetherwiththe primarysludgeintheprimarysettlementtanks. Chemicalflocswhicharenotremovedintheprimarysettlementtankaretransportedwiththewastewate
41、rand separatedinthesecondarysettlementtanktogetherwiththebiologicalsludge. 4.2.2.3 Simultaneousprecipitation Simultaneousprecipitationcanbeusedinwastewatertreatmentplantswithbiologicaltreatmentdependingonthe activatedsludgeprocessused. Withsimultaneousprecipitationtheadditionoftheprecipitationagenti
42、seffectedintheaerationtank,attheendof theaerationtankortogetherwiththereturnsludge,wherebothabiologicalandachemicalprocesstakesplace. Themixedbiologicalandchemicalsludgeisseparatedinthesecondarysettlementtankoraflotationunit.The returnsludge,theexcesssludgeandthemixedliquorsuspendedsolidscontainalar
43、gerpartofinorganicmaterial ascomparedtothesludgesinanormalactivatedsludgeplant. 4.2.2.4Postprecipitation Postprecipitationcanbeusedinwastewatertreatmentplantswithbiologicaltreatment(activatedsludge,trickling filteretc.). Withpostprecipitationtheadditionoftheprecipitationagentisdoneinamixingtankafterthesecondary settlement.Flocformationtakesplaceinaflocculationtankfollowedbyafinalclarificationtankwherethechemical sludgeisseparated.Alternativelylamellasedimentationorflotationcanbeusedforseparation. 4.2.2.5 Multipointprecipitation Theefficienc
