Technology review of urine diversion componentsOverview of urine diversion components such as waterless urinals, urine diversion toilets, urine storage and reuse systems

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Sustainable sanitation - ecosan program

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Place and date of publication:Eschborn, May 2011

Authors:Dr. Elisabeth von Münch, Dr.-Ing. Martina Winker

Responsible editor:Dr. Elisabeth von Münch

Acknowledgement:Nathasith Chiarawatchai, Florian Klingel, Christine Werner and Patrick Bracken (authors of an earlier version), Dr. Håkan Jönsson, Dr. Elisabeth Kvarnström and Dr. Arno Rosemarin (reviewers of the current document)

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Photos:Cover: © Philipp Feiereisen, Steffen Blume, Lukas Ulrich, Abdoulaye Fall, Sören Rüd, Robert Gensch, iStockBack: © GIZ, Steffen Blume, Elmer Sayre, Sören Rüd, Patrick Zimmerer, Alexandra Höhne/Rwanda Village Concept Project, Elisabeth von Münch, Stefanie LorenzInside: © Elke Mühlegger/EcoSan Club Austria, Patrick Zimmerer, Philipp Feiereisen, Julia Littmann, Håkan Jönsson, Abdoulaye Fall, Steffen Blume, Philipp Feiereisen, Robert Gensch, Heike Hoffmann, Arne Panesar, Michael Kropac

Technology review of urine diversion componentsOverview of urine diversion components such as waterless urinals, urine diversion toilets, urine storage and reuse systems

4

5 Foreword

ThispublicationisanimportantcontributionoftheGIZprogram“Sustainablesanitation–ecosan”asitpullstogetherscatteredknowledgearoundthetopicofurinediversioninaconcisemanner.

TheprogramiscommissionedbytheGermanFederalMinis-tryforEconomicCooperationandDevelopment(BMZ).Theecologicalsanitation(ecosan)approachisabletoaddressboth:childhealthwhichneedstobeimprovedthroughbettersani-tation,andsustainablemanagementandsaferecyclingofimportantresourcessuchaswaterandnutrients,inparticularphosphorus.

Itisapositivedevelopmentthatmoreandmorepeoplearenowbecomingawareofthepresentworldwidesanitationcrisis–whichiskillingthousandsofyoungchildreneachday.Itisalsobecomingmorewidelyknownthatphosphorus(intheformofphosphaterockdeposits),isanon-renewable,limitedresource.High-qualityphosphaterockwillrunoutinthefuture.

Thesafeuseofurineasafertilisercanenableallfarmerstogrowmorefood–notonlythosewhohavethemeanstobuyartificialfertilisers.Whenpricesforartificialfertiliserincreaseagain–asin2008whenpricesincreasedbyuptoeighttimesinsomecountries–farmersrelyingonurinewillbelessaffectedbysuchfertiliserpricehikes.

Iamsurethistechnologyreviewwillhelpandinspirepeopleworkingonsustainablesolutionsforexcretamanagement.Feedbackaboutthispublicationiswelcomeandshouldbesenttoecosan@giz.de.

Letusjointlycontinuetoworktowardstheaimofsafeandsustainablesanitationforall!

Andreas KanzlerHead of Water SectionDivision Water, Energy, Transport

DeutscheGesellschaftfürInternationaleZusammenarbeit(GIZ)GmbHEschborn,Germany

Eschborn,May2011

6 Contents

1 Summary .......................................................................................... 8

2 Introduction to urine diversion (UD) ................................... 8

2.1 DefinitionofUD.................................................... 82.2 PurposesofUDinstallations.................................. 92.3 BenefitsofUDsystems........................................... 92.3.1BenefitsofalltypesofUDtoiletsand waterlessurinals...................................................... 92.3.2FurtheradditionalbenefitsofUDDTscompared

topitlatrines...........................................................92.4 ChallengeswithUDsystems.................................. 102.4.1Socialacceptanceamongstusers............................. 102.4.2Usercooperation..................................................... 102.4.3Urinereuse/disposalissues...................................... 102.4.4Urineprecipitation.................................................. 10

2.5 Quantityofurine................................................... 112.6 Qualityofurine...................................................... 112.6.1Sourceconsiderations............................................. 112.6.2Pathogens................................................................ 112.6.3Nutrients................................................................ 112.6.4Micro-pollutants..................................................... 12

2.7 Urinetreatment...................................................... 122.7.1 Treatmentobjectives............................................... 122.7.2 Treatmentbystorage.............................................. 122.7.3 Otherurinetreatmenttechnologies........................ 12

2.8 AreUDsystemsmorecosteffective?...................... 132.9 TechnicalcomponentsusedforachievingUD....... 13

3 Reuse of urine as fertiliser in agriculture ....................... 13

3.1 Howtouseurineasafertiliser............................... 133.1.1 Basicguidelines...................................................... 133.1.2 Specificadvantagesofurinecompared

toothermineralfertilisers.................................... ..143.1.3 Disadvantagesofurinecompared

toothermineralfertilisers.................................... ..143.1.4 Shouldurinebeappliedundiluted

ordilutedwithwater?........................................... ..153.2 Arehormonesandpharmaceutical

residuesinurineproblematicforreuse?.................. 153.3 Isurinean“organic fertiliser”

andcanitbeusedinorganicfarming?................... 16

4 Waterless urinals ........................................................................ 16

4.1 Definitionandpurpose..............................................164.2 Historicaldevelopmentofwaterlessurinals............ 174.3 Odourcontrolmethods(general)........................... 174.4 Odourcontrolforconnectionofurinal

tosewerorstoragetank.......................................... 174.4.1Rubbertubeseal..................................................... 174.4.2Curtainvalveseal.................................................. 174.4.3Sealantliquid(blockingfluid)................................ 184.4.4Othermethodsfortheodourseal.......................... 19

4.5 Furtherdesigninformation.................................... 194.6 Useandmaintenanceofwaterlessurinals............... 194.7 Useracceptanceofwaterlessurinals....................... 204.8 Suppliersandcostsofwaterlessurinals................... 204.9 Howtochoosetherighttypeofwaterlessurinal.... 20

5 Urine diversion toilets .............................................................. 21

5.1 Definition............................................................... 215.2 BasicdesigninformationforUDtoilets................. 215.3 Urinediversiondehydrationtoilets(UDDTs)........ 215.3.1 Basicdesigninformation........................................ 215.3.2Odourcontrolforurinecollectionsystem.............. 225.3.3Constructionmethodsandmaterials...................... 225.3.4Useandmaintenance.............................................. 225.3.5 Projectexamples..................................................... 22

5.4 UDflushtoilets...................................................... 225.4.1 Overviewonhistoricaldevelopment....................... 225.4.2Basicdesigninformation........................................ 225.4.3Odourcontrolfortheurinecollectionsystem........ 235.4.4Materials................................................................. 235.4.5 Useandmaintenance.............................................. 235.4.6Projectexamples..................................................... 23

5.5 SuppliersandcostsforUDtoilets.......................... 235.6 HowtochoosebetweenaUDDT

andaUDflushtoilet.............................................. 23

6 Urine piping and storage tanks ............................................. 24

6.1 Urinepiping........................................................... 246.1.1 Functionalprinciples.............................................. 246.1.2 Materials................................................................. 246.1.3 Pipesizeandlayout................................................ 246.1.4 Odourcontrol......................................................... 24

6.2 Urinestoragetanks................................................. 246.2.1Functionalprinciples.............................................. 246.2.2Locations................................................................ 256.2.3Materials................................................................. 256.2.4Urinetanksize....................................................... 256.2.5Numberofurinetanksneeded............................... 256.2.6Urineoverflowpipe................................................ 266.2.7Examples................................................................ 26

6.3 Ventilationforpressureequalisationofpipesandtanks................................................... 26

6.4 Maintenanceofurinepipesandtanks.................... 27

7 References ....................................................................................... 27

7.1 Referencesusedinthisdocument.......................... 277.2 Videoclips.............................................................. 297.3 Additionalphotos................................................... 29

8 Appendix: Worldwide listing of suppliers for waterless urinals, UD pedestals and squatting pans ....................................... 29

7 List of Tables & Figures:

Table 1.Averagechemicalcompositionoffreshurine(literaturevalues)andstoredurine(simulatedvalues,seeUdertetal.(2006))...................................................... 12

Figure 1.Waterlessurinalsformen.Left:CentaurusmodelofKeramagcompany.Right:PlasticurinalfromAddicom,SouthAfrica,withEco-Smellstopdevice(sources:left:E.v.Münch,Delft,2006;right:Addicom)............................................ 16

Figure 2.Twotypesofodoursealsforwaterlessurinals.Left:Flatrubbertube(KeramagCentaurus).Right:(leftside)See-throughpipefitting;(rightside)see-throughEcoSmellstop(ESS)unitshowingthebluesiliconcurtainone-wayvalveinside(source:(left):E.v.Münch,2007;right:Addicom).......... 18

Figure 3.EcoSmellstop(ESS)unitwithpipefittingandextractor.InsidetheESSisthesiliconcurtainvalve(source:Addicom)..................................................... 18

Figure 4.Exampleinstructionsheet,showingreplacementofsealantliquidforUridanurinals(otherurinalswithsealantliquidhaveasimilarmaintenanceroutine)(source:Uridan).............................. 18

Figure 5. Left:IndoorUDDT(pedestaltype)inJohannes-burg,SouthAfricainthehouseofRichardHolden(source:E.v.Münch,2006).Right:UDDTsquattingpaninBanga-lore,India,withthreeholes:theareainthefrontisforanalwashing,middleisforfaecesandbackisforurine(source:D.Schäfer,2008)............................................................... 22

Figure 6.UDflushtoilets.Left:Gustavsberg(inMeppel,theNetherlands);Right:Dubbletten(inStockholm,Sweden),(sources:E.v.Münch,2007)..... 23

Figure 7.Left:Low-costsolution:20LplasticjerrycanforurinestorageatindividualtoiletlevelinOuagadougou,BurkinaFaso(source:E.v.Münch,2006)Right: Below-groundplasticurinestoragetanksatKullön,Swedenduringtheconstructionprocess.Thetankswillbecoveredwithsoil(photo:MatsJohansson,source:Kvarnströmetal.,2006)............. 26

Figure 8.Urinestoragetankmadeofa150m³plasticbladderatLakeBornsjönnearStockholm,Sweden(photocomissionedby:E.v.Münch,2007)......... 26

Figure 9. PlasticurinestoragetankinOuagadougou,BurkinaFasoaspartoftheEU-fundedprojectECOSAN_UEledbyCREPA(source:S.Rüd,2008)............................... 26

8 1 Summary

Thetargetaudienceforthispublicationarepeoplewhoarenewtothetopicofurinediversionornewtothetopicofecologicalsanitation(ecosan),andwho:ÿ needtoobtainanoverviewofthemainissuesfor

urinediversionandthemaintechnicalcomponentsÿ wanttoknowwhicharethemainimportantdocu-

mentsforfurtherreadingÿ haveaparticularinterestindevelopingcountries,

withapro-poorperspectiveÿ needinformationonavailablesuppliersworldwide

andoncostsforwaterlessurinalsandurinediversiontoiletpedestalsandsquattingpans.

Thispublicationexplainsthepurposesofurinediversion,itsbenefitsandchallenges,urineprecipitation,urinetreatmentandreuseinagriculture.Itprovidesanoverviewondesignandoperationalaspectsforequipmentneeded,suchaswaterlessurinalsandurinediversiontoiletsincludingsupplierinforma-tionandindicativecosts.Thepublicationalsoprovidesbasicdesigninformationforurinepipingandstoragetanks(inclu-dingtanksizing,odourcontrolandventilationdesignissues).

Urinediversionisthetermusedtodescribekeepingurineandfaecesseparatefromeachotheratthepointofexcretion.Thefourmainpurposesofimplementingsystemswithurinediver-sion(UD)are:toreduceodour,topreventproductionofwetfaecalsludge,toreducewaterconsumptionandtocollectpureurineforuseasfertiliserinagriculture.

Furtherbenefitsincludeminimisedexcreta-relatedgroundwaterpollution,thefactthatthetoiletcanbeindoors(asopposedtoapitlatrine)andbettercontrolovermicro-pollutantsdis-chargedtotheenvironment.Thechallengesincludesocialacceptance,usercooperation,urinereuseordisposalissuesandurineprecipitation.

Equipmentusedinurinediversionsystemsincludeswaterlessurinals,urinediversiontoilets(eitherwithorwithoutflushwater),urinepipingandurinestoragetanks.Themostcom-monandcheapestmethodtotreaturineforpathogenremovalfromfaecalcross-contaminationisbyextendedstorage.

Urinecansafelybeusedingardeningandagricultureasanutrient-richfertiliser,providedrelevantreuseguidelines(seeWHO,2006)arefollowed.Ifthereisnousefortheurine,itcanbedischargedtoasewerorpossiblyinfiltratedintheground(iflocalsoilandgroundwaterconditionspermitthiswithoutadverseimpactsongroundwaterquality).

Waterlessurinalsenablethecollectionofundilutedurineandarealreadywidelyusedinmanyindustrialisedcountries(par-ticularlyinGermany)inpublicorcommunalbuildings(not

commonathouseholdlevel).Butsofar,theyareusuallyjustconnectedtothesewersystemandtheurineisneithercollectednorreused.Odourcontrolinwaterlessurinalsiscrucialforuseracceptance,andisachievedby(i)variousdesignsforanodourblockingmechanism(mostnotablywithaflatrubbertube,siliconcurtainvalveorsealantliquid),and(ii)byen-suringcorrectmaintenanceprocedures.

Urinediversiondehydrationtoilets(UDDTs)collectfaeces“in a dry system”(i.e.separatelyfromurine,flushwaterandanalwashwater)invaultsorbucketslocatedunderneaththeUDpedestalorsquattingpan.Forpro-poorapproachesindeve-lopingcountries,UDDTsaremoresuitablethanUDflushtoilets,asthelatterstillrequireasewersystemandtreatmentforbrownwater.UDDTscaneasilybedesignedtosuituserswhousewaterinsteadoftoiletpaperbyprovidingaseparatedrainholeforanalwashwater.

Odourcontrolandpressureequalisationwithinurinepipesandurinestoragetanksneedtobeincludedinthedesigninthecaseofindoormulti-toiletsystems.WaterlessurinalsandUDDTsareapromisingstepforwardtowardsimplementingwatersa-ving,moresustainablesanitationandreduceddependencyoncostlyartificialfertiliser,thuscontributingtopovertyreduction.

2 Introduction to urine diversion (UD)

2.1 Definition of UD

Urinediversion(UD)devicescollecturineseparatelyfromfaecesandfromwater(orwithminimalflushwater).Aurinediversiontoilethastwooutletswithtwocollectionsystems:oneforurineandoneforfaeces(andpossiblyathirdoneforanalwashwater),inordertokeepthesetwo(orthree)excretaorwastewaterfractionsseparate.UDtoiletsmay,ormaynot,mixwaterandfaeces,orsomewaterandurine,buttheynever mix urine and faeces.Section 5.1providesanoverviewofthetwomaintypesofurinediversiontoilets:UDtoiletswithoutflushwater(thesearecalledurinediversiondehydrationtoiletsorUDDTs)andthosewithflushwater(UDflushtoilets).

Urinals–widelyusedbymenatpublictoilets,restaurants,schools,etc.–workasurinediversiondevicesbecauseurineiscollectedseparatelyfromfaeces.Whenurinalsareofthewaterlesstype,theycancollecttheurinepure,meaningwithoutdilutionwithwater.

Urinediversionmaybeusedinecologicalsanitation(ecosan)concepts,butnot all ecosan projects use urine diversion.Ecosanisanapproachtosanitationwhichfocussesonreuseofnutrientsandorganicmattercontainedinexcretaandwastewater,andemphasisessustainabilityinallaspects1.

1 Thedefinitionof“sustainable sanitation”isprovidedinthefirstvisiondocumentoftheSustainableSanitationAlliance(http://www.susana.org/index.php/lang-en/intro/vision/42-vision/76-vision-document).

9 2.2 Purposes of UD installations

ThepurposeofaUDinstallationisusuallyone,orseveralofthefollowingfourpurposes–whichcanbesplitintwocategories:

Purposes relevant for all types of UD systems (describedinmoredetailinSection 2.3.1below):1. toreducewaterconsumption2. tobeabletocollecturinepureandundilutedso

thatitcan–aftersanitisationbystorage–besafelyusedasfertiliserinagriculture.

Purposes relevant for UDDTs (urinediversiondehydrationtoilets)comparedtopitlatrines(describedinmoredetailinSection 2.3.2below):3. toreduceodour4. toavoidproductionofwet,odorousfaecalsludge,

whichhastoberemovedbysomeonewhenthepitlatrineisfull.

2.3 Benefits of UD systems2.3.1 Benefits of all types of UD toilets and waterless urinals

ÿ Water savings: UDDTsandwaterlessurinalsrequirenoflushwater,whereasconventionalurinalsusearound4Lperflush(flushtoiletsuseabout8-12Lperflush;pourflushtoiletsuse2-3Lperflush).UDflushtoiletscanalsoreducewaterconsumptionwhencomparedtoconventionalwater-flushedtoilets:thisisbecausethe“urine flush”usesalowvolumetoflushawayremai-ningurinedropsandusedtoiletpaper(0.5to2Lofflushwater,dependingonthetoiletmodel).Ifurine-soiledtoiletpaperiscollectedinabin,ratherthanflushedaway,watersavingscouldbeevengreater.

ÿ Thecollectedurinecanbeusedasfertiliser,whichcanincreasecropyields.AsexplainedfurtherinSection 3,urineisaliquidfertiliserrichinnitrogenandphosphorus.Thisisofparticularimportanceforthosefarmersindevelopingcountrieswhocannotaffordmineralfertilisers.

ÿ Recycling of phosphorus from urinemaybecomenecessaryinthemid-termfutureandiseasiertoachieveifurineiscollectedpureratherthanmixedwithwastewater.Phosphorusisanessentialelementforagriculturalproduction.Itiseitheravailableinthesoiloraddedwithfertiliser,andisproducedfrommineddepositsofphosphaterock.High-gradephosphaterockreservesarerunningout:atcurrentratesofexploitation(increasingataround3%peryear),theeconomicre-servesofphosphoruswilllastnomorethan50years.TheeconomicallyviablereservesintheUnitedStatesforexample,willbedepletedwithin25to30years(Rosemarinetal.,2008;Cordelletal.,2009).Inthe

future,increasedeffortstorecyclethephosphoruscontentofhumanandanimalexcretaareinevitable(EcoSanRes,2008).

ÿ Ifthereisconcernabouthormones and pharmaceuti-calresiduesenteringdrinkingwatersourcesviahouse-holdwastewater(sewage),thentheseparatecollectionofurinecansimplifyremovalofthesesubstancesfromtheenvironment.Particularlyforindustrialisedcoun-tries,thiscouldbeamajordrivingforceinfavourofUDsystems(see Section 3.2).

ÿ Urinediversionmayalsocreatebusiness opportunities fortheprivatesectorviathesaleofUDtechnologyandrelatedservices.

ÿ Inmanycases,cost savingscanberealisedwhenim-plementingUDsystemsespeciallyregardingeconomiccostswhenasystem-wideanalysisisperformed(inclu-dingexternalcostsduetogroundwaterpollutionforexample),seeSection 2.8fordetails.

2.3.2 Further additional benefits of UDDTs compared to pit latrines

ÿ Thereissignificantlyless odourwhenurineandfaecesarenotmixed–asinaUDDT–comparedtothecasewhereurineandfaecesaremixedasinapitlatrine.

ÿ SinceUDDTsareodour-freewhendesignedandoper-atedcorrectlyandsincetheydonotneedcontactwiththesoiltoinfiltrateliquids,UDDTscanbeindoors,whichleadstoimprovedsecurity,privacyandusercomfort.Thisaspectisveryimportantespeciallyforwomenandgirls,forwhomitmaybetoodangeroustogotothetoiletoutsideindarkness(sexualassaults).

ÿ No production of wet faecal sludge:Faecescollectedinadrymanner,separatelyfromurineandwater,arenotoffensive,especiallyafteranextendeddryingperiod.Hence,itismucheasiertoemptythefaecesvaultofaUDDTthanthepitofapitlatrine.Thisisparticularlyimportantforhillyorcrowdedareaswhereaccesstopitlatrinesbyconventionaltrucksisimpossible.

ÿ Minimised toilet-related groundwater pollution with nitrate and pathogens.Pitlatrinesandseptictanksaredesignedtoinfiltrateliquidintothesoil,whichcanleadtogroundwaterpollutionifthepopulationdensityishigh,thegroundwaterlevelishighortherearepre-ferentialpathwaysinthesoiltothegroundwater.UDDTsontheotherhandcollecttheurineandfaecesabove-groundandthereforedonotpollutetheground-water.Notethatonsitegreywaterdisposalcanalsoleadtogroundwaterpollutionandthisissueisnotaddressedbyurinediversiontoilets.

1010 2.4 Challenges with UD systems2.4.1 Social acceptance amongst users

Regardingsocialacceptance,thesuccessfuladoptionofurinediversionsystemsiscloselylinkedto:ÿ Users'motivationandwillingnesstochangeexisting

habitsandbehaviours,forexample: „ Thewillingnessofmentositdownonpedestal-type

UDtoiletsforurinationifnourinalsarebeingprovi-ded–thisdoesnotapplytosquatting-typeUDtoilets;

„ ThewillingnesstomovebackwardsalittlebitsothatanalwashwatercanbecollectedseparatelyfromfaecesinthecaseofUDDTsand“anal washers”.

ÿ Supportiveattitudeofallstakeholdersinvolved(users,maintenancestaff,planners,farmers,politiciansandsoon).

ÿ Possibleuseofurineasafertiliser(orsomeotherdisposaloptionforcollectedurineifreuseinagricultureoraquacultureisnotpossible).

ÿ Culturalobstacleslikesuperstitionoftheusers.

Odournuisance(beitonlyperceivedoractual)isafurtherpotentialobstacletosocialacceptance,butwiththecorrectdesignandoperation,odoursfromwaterlessurinalsandUDtoiletsarethesameorlessthanconventionalurinalsandtoilets.Also,UDDTshavesignificantlylessodourandfliesthanpitlatrines,andcanthereforebeplacedindoorswhichmayprovetobeasignificantdriverforsocialacceptance.

Socialacceptancealsodependstoahighdegreeon:ÿ Thecurrentsanitationsituation(arepeopleusedto

“flying toilets”(plasticbags),pitlatrinesorflushtoilets?)andtheusers’expectationforthefuture.

ÿ Theprevailingnormsregardingreuseofhumanexcretaandrelatedtaboos.

ÿ Availableserviceproviderswhocanofferacollectionandmaintenanceservice.

Hence,carefulplanningwithstakeholderparticipationiscrucial.

2.4.2 User cooperation

Therearethreemainissuestobekeptinmindregardingusercooperation:1. Usershaveto“think a bit”whentheyuseUDtoilets

forthefirsttime(thispointdoesnotapplytowater-lessurinals,whichareusedinthesamewayaswater-flushedurinals).Thus,urinediversiontoiletsneedsomeupfrontawarenessraisingtoensurecorrectusageandsocialacceptance.

2. Ifusersdonotcooperate,toiletmisusecanresultinodour(e.g.ifusersurinateinthefaecescompartmentofaUDDT)orina“messed-up”toilet(e.g.ifusersdefecateintotheurinecompartmentofaUDtoilet)–althoughthisisnotdissimilarfrompitlatrinesandflushtoilets.

3. CleaningofUDtoiletsisalittlemoretimeconsu-mingthancleaningofconventionaltoilets,duetotheseparateurinesectioninthetoiletbowl.

2.4.3 Urine reuse/disposal issues

Thefollowingissuesregardingurinereuseordisposalareimportant:ÿ Urineneedstobetransportedtothereuseareaswhich

leadstoincreasedtraffic,andisproblematicifthedis-tancesarelarge(noise,airpollutionandCO₂emissions).

ÿ Whenurineisusedinagriculture,thefarmersneedtobetrainedonthecorrectmethods(see Section 3.1).

ÿ Ifurinecannotbereused,itissometimesinfiltratedintheground.Insomecircumstances,thishasnoad-verseenvironmentalimpacts.Inothercases,thiscanleadtogroundwaterpollutionwithnitrate(depen-dingontheamountofurineinfiltratedperarea,soilproperties,groundwatertable)–justlikewithpitlatrines(butwithpitlatrinesthereistheaddedpro-blemofpathogentransporttogroundwater).

2.4.4 Urine precipitation

TheinformationgiveninthissectionwasmainlytakenfromLarsenandLienert(2007).Infreshurine,themainnitrogencompoundisurea.Duringstorage,ureaishydro-lysedtoammonia/ammoniumandhydrocarbonatebyureaseenzymespresentintheurinestoragecontainer,soilandinaquaticsystems(see also Table 1).Thisprocessisaccompa-niedbyanincreaseinthepHvalue.TheincreasedpHvalueresultsinprecipitationofstruvite(MgNH₄PO₄)andcalciumphosphate(Ca₁₀(PO₄)₆(OH)₂)crystals.Thosecrystalscanformincrustations,alsocalled“urine stone”.

Precipitationinurinepipesandstoragetanksoccursinbothwater-flushedandwaterlesssystems.Inadditionskincells,hairandexcretedorganiccomplexeswillalsosettle.

Theendresultmaybehardprecipitates(incrustations)orsoft,viscous,paste-likeprecipitates(deposits).Incrustationstendtooccurontheinnerwallsofpipesandpipebends.Softdepositsoccurinstoragetanks(wheretheyformasludgeatthebottomofthetank)andinnear-horizontalurinepipes.

11 11 Thefollowingdesignparametersreducetheextentofprecipitation:ÿ Short retention time:precipitationoftenoccursat

locationswheretheurineflowvelocityisloworevenstagnant(suchassiphons,horizontalpipes,U-bendsofthetoilet).Sucharrangementsshouldthereforebeavoided.

ÿ Smooth surfaces and hydrophobic materialsshouldbeused.Scratchingofsurfacesbymechanicalcleaningshouldbeavoided.PlasticPVCpipesarecommonlyusedforurinepipes.

ÿ Ifflushingwithwater:Flushing with soft water,suchasrainwater,ispreferredtoflushingwithhardwater(softwaterhaslesscalciumandmagnesiumwhichcanprecipitatewiththeurine’sammoniumandphosphate).

ÿ Pipes with a relatively large diameter (atleast2.5cm)arelesslikelytogetclogged.

Usingnoflushwateratall(asinwaterlessurinals)doesnoteliminatetheproblem,sinceurinealsocontainscalciumandmagnesiumwhichcanprecipitatewithammoniumandphos-phatetoformstruvite.InwaterlessUDsystems,moresoftdepositstendtooccurthanhardincrustations,whereasforwater-flushedUDsystemsitistheotherwayaround.Informa-tionaboutmaintenancetaskstopreventorremoveblockagesinurinepipesisprovidedinSection 6.4.

2.5 Quantity of urine

Thequantityofurineproducedbyanadultisaround0.8to1.5Lperadultperday(WHO,2006,Volume4)–itmainlydependsontheamountapersondrinksandhisorhertranspi-ration.Childrenproduceapprox.halfasmuchurineasadults.Awidelyuseddesignfigure,basedonSwedishdata,is1.5 L/cap/d (or 550 L/cap/year)2.

2.6 Quality of urine2.6.1 Source considerations

Thedescriptionofurinequalityinthissectionappliestourinecollectedwithoutcross-contaminationwithfaeces.Suchcross-contaminationisdealtwithviaurinetreatmentmethods(see Section 2.7).

Additionally,itshouldbehighlightedthatthequalityofthecollectedurineisrelatedtothehealthandlifestyleofthepeopleexcretingitandtotheurinecollectionsystem.Forex-ample,ifurineiscollectedfromahospitaloranold-agehomeitwillmostlikelycontainmorepharmaceuticalresiduesthanurinefromhealthyandyoungpeople.Andifurineisledthroughcopperpipesitmayhaveahighcopperconcentration.Thishastobekeptinmindduringthedesignphase,especiallywhenreuseisplanned.

2.6.2 Pathogens

Therearefourtypesofpathogensrelevantforsanitation:bacteria,viruses,parasiticprotozoaandintestinalhelminths.Itisimportanttoknowthaturineinthebladderofahealthypersonissterile(meaningitcontainsnopathogens).Onlyveryfewdiseasesaretransmittedviapathogensinurine.Theonlydiseasewhichneedstobeconsideredfromariskperspec-tivewhenurineisreusedinagricultureisSchistosoma haema-tobium–andonlyinareaswherethisdiseaseisendemic(WHO,2006,Volume4).Incontrast,theamountofpatho-gensinfaecescanbeveryhigh,dependingontheprevalenceofdiseasesinthepopulation.

2.6.3 Nutrients

Macro-nutrientsinexcretaincludeN,P,KandS(nitrogen,phosphorus,potassiumandsulphur)ofwhichNandParethemostimportant.

Withregardstothenutrientscontainedinurine,thefollow-ingdesignfiguresareused(derivedmainlyfromSwedishdatabutconsideredtobequiteuniversal,seeJönssonetal.,2004):ÿ Massofnutrientsexcretedwithurine:4kgN/cap/yr,

0.36kgP/cap/yrand1.0kgK/cap/yr.ÿ Concentrationsofmacro-nutrientsinurine(design

figure):7300mg/LN;670mg/LP;1800mg/LK.ÿ Concentrationfiguresarebasedonaperson’sdiet

andshouldpreferablybeverifiedonsite.ÿ 80%ofthenitrogenexcretedbyapersonisexcreted

withtheurine,andtherestwiththefaeces.Hence,intermsofnitrogenfertiliser,urineismoreimportantthanfaeces.Forphosphorus,55%isexcretedwiththeurine,therestwiththefaeces.

ÿ Adultsexcretethesamemassofnutrientsastakenupintheirdiet,asthereisnoretentionofnitrogenandphosphorusinthehumanbody,exceptforchildrenwhereasmallamountisretainedforbonegrowth.

Thechemicalcompositionoffreshandstored3urineissummarisedinTable 1(see next page) andthefollowingobservationsarehighlighted:ÿ Freshurinecontainsnitrogenmainlyintheform

ofurea;storedurinecontainsnitrogenmainlyintheformofammonium/ammonia(thetransformationprocessisdescribedinSection 2.7.2).

ÿ Thelowerphosphate,magnesiumandcalciumcon-centrationsinstoredurinecomparedtofreshurineareduetoprecipitationprocessesduringstorage.

2 Cap=capita=person

3 Storedurinemeansurinewhichiscompletelyhydrolysed(Udertetal.,2003),andthistypicallyoccurswithin2-4weeksdepen-dingontheamountofureasepresent(Maurer,2007).

1212

2.6.4 Micro-pollutants

Micro-pollutantsinurinecouldincludethefollowingcategoriesofsubstances:1. Naturalhormones2. Pharmaceuticalresidues,includinghormones

fromcontraceptivepill3. Heavymetals4. Persistentorganicpollutants(POPs)

Thelasttwocategoriesofmicro-pollutants–heavymetalsandPOPs–arevirtuallynon-existentinurineastheywouldoriginatefromthefoodapersonhaseaten.Urineisanim-portantpathwayforthebodytoeliminateorganicdegrada-tionproductswhicharetoxictothehumanbody,butthesesubstancesareeasilybiodegradablebysoilmicroorganismsafterexcretion.Thefirsttwocategoriesofmicro-pollutants–thenaturalhormonesandpharmaceuticalresidues–dooccurinurineandcanbemanaged(see Section 2.7.3 and 3.2).

2.7 Urine treatment2.7.1 Treatment objectives

Urinetreatmenthasthefollowingobjectives:ÿ Pathogen kill(thisisthemainobjective):Collected

urinemaybecontaminatedwithfaecalpathogensif

carelessusersdepositfaecesintheurinecompartmentofaUDtoilet(thisistermed“cross-contamination”ofurinewithfaecalmaterial).Asmentionedabove,pureurineisvirtuallypathogen-free.

ÿ Otherpossibletreatmentobjectivesmayinclude: „ Volumereductionbyevaporationorbyconversion

intosolidform(struvite)toreducetransportcosts. „ Extraction(furtherconcentration)ofnutrients. „ Eliminationofmicro-pollutants.

2.7.2 Treatment by storage

Thesimplest,cheapestandmostcommonmethodtotreaturinewiththeaimofpathogenkill,isextendedstorageinstoragetanks.

Storageofurineinaclosedtankorcontainer(notnecessarilygastight)isanefficienttreatmentmethodforreducingpatho-gensinurine:Thedecompositionofureaintoammonia/ammoniumandhydrocarbonate–whichisfacilitatedbythenaturalenzymeurease–leadstoanincreased pH value(pHaround9)whichhasasanitisingeffect(meaningitkillspatho-gens),sothatbacteria,parasiticprotozoa,virusesandintestinalhelminthsdieoffovertime.Anenvironmentwithahightem-peratureandlowdilutionwithwaterenhancesthiseffect.Timeitselfalsoleadstopathogenkill.

Safereuseofurineinagriculturecanbeensuredifthefol-lowingrecommendedstoragetimesareused(fordetailsseeWHO,2006,Volume4):ÿ Urineoriginatingfromlargersystems(communitylevel)

–wherecross-contaminationwithfaecescannotberuledout–shouldbestoredforatleastonemonthifitisusedonfoodorfoddercropswhichareprocessed.Forahighersafetymargin,6monthsofstoragecanbeused(inwhichcasetheurinecanbeusedonallcrops).Butiftheammonialevelintheurineisgreaterthan2 mgN/L(whichitshouldbeforundilutedurine)thenshorterstoragetimeswillsuffice(Winkeretal.,2008).

ÿ Nostorageisneededwhenurinefromownproduction(orfromsystemswherecross-contaminationwithfae-cesisdefinitelynotoccurring5)isusedforcropsgrownforownconsumption.Thisisbecausediseasetrans-missionwithinthehouseholdviatheurine-oralrouteismuchlesslikelycomparedtoday-to-daycontactofthehouseholdmembers.

2.7.3 Other urine treatment technologies

Advancedurinetreatmenttechnologiescanincludebio-logicalprocesses(nitrification),chemicalprocesses(struviteprecipitation;ozonation)orphysicalprocesses(membrane-based).Someofthesehigh-techmethods(suchasozonation

Parameter Freshurine Storedurine

pH 6.2 9.1

Total nitrogen, TN (mg/L) 8830 9200

Ammonium/ammonia-N, 460 8100NH4+ and NH3 (mgN/L)

Nitrate/nitrite NO3 + NO2 0.06 0(mgN/L)

Chemical oxygen demand, 6,000 10,000COD (mg/L)*

Total phosphorus, TP (mg/L) 800 – 2000 540

Potassium, K (mg/L) 2740 2200

Sulphate, SO4 (mgSO4/L) 1500 1500

Sodium, Na (mg/L) 3450 2600

Magnesium, Mg (mg/L) 120 0

Chloride, Cl (mg/L) 4970 3800

Calcium, Ca (mg/L) 230 0

* COD is a measure of the organic components.

Table1. Average chemical composition of fresh urine (literature values) and stored urine (simulated values, see Udert et al. (2006))4. Significant changes during storage are indicated in bold.

5 Forexamplewhenurineiscollectedfromwaterlessurinals.4 Source:Maurer(2007)

13 13 andmembrane-basedprocesses)canremovemicro-pollutantsfromurine(seeLarsenandLienert(2007);Tettenborn(2007)).Thisisusefultoknowifthereisconcernaboutmicro-pollutantsinurine(see Section 3.2).

2.8 Are UD systems more cost effective?

Possiblecostsavingsofurinediversionsystemsmaybere-latedtothefollowingaspects(ineachcase,oneneedstocon-siderwhichsystemsarebeingcompared):ÿ Ifacentralisedsewersystemandwastewatertreatment

plantcanbeavoidedbyusingUDtoilets,thencostsavingswillbesignificant.However,thecollectionandtreatmentofgreywater, industrial wastewater and rainwaterstillrequiresasewersystemofsomesort(separate,decentralisedsystemsmayoftenbepreferable).NotethattheremaininggreywaterinUDsystemscontainsafarlowerconcentrationofpatho-gensandnutrientscomparedtoconventionaldomesticwastewater.

ÿ Inregionswherewaterisscarceandexpensive,watersavingsfromUDtoilets(inparticularUDDTs)canleadtooverallcostsavingscomparedtoflushtoilets.

ÿ Inregionswheresoilfertilityispoorandfertiliserex-pensive,farmersmayhaveproductioncostsavingsorhigheryieldswhenusingurineasafertiliserinsteadofmineralfertiliserornofertiliseratall.

Regardingpotentialenergysavings,thisneedstobeanalysedonacasebycasebasis.EnergysavingsmaybepossiblewithUDsystemsinthreeareas:1. Ifthesystemissetuptouselesswater,energysavings

arepossiblewithrespecttopumping,processinganddistributionofthetapwater.

2. Energysavingsmaybepossibleatthewastewatertreatmentplant,whichreceivesalowerloadofnitro-geninthesewageifurineiscollectedseparately(hencelessoxygenrequiredfornitrificationprocess).

3. Ifurinereplacesartificialmineralfertiliser,thenener-gysavingsarepossibleforfertiliserproductionaswellasforfertilisertransport(mostAfricancountrieshavenolocalmineralfertiliserproductionfacilities).

Alifecycleanalysis,comparingtheenergydemandfornutri-entremovalandmineralfertiliserproductionversusnutrientrecoveryidentifiedaconsiderableenergysavingpotentialwithurinediversionnutrientrecovery(Maureretal.,2003).

Ontheotherhand,thefollowingaspectscanleadtoUDsystemshavinghighercoststhanconventionalsystems:ÿ Incomparisonwithconventionalsewer-basedsanitation

systems,urinediversionsystemsusingUDflushtoiletstendtohaveahigherinitialinvestmentcostastheyre-quireadditionalcomponentsfortheseparatecollection,transportandtreatmentoftheurineandfaeces.

ÿ AUDDTusuallyhasaslightlyhighercapitalcostthanasimplepitlatrineor–ofcourse–thedo-noth-ingoptionofopendefecation.

Adequatefinancingandoperatingschemeshavetobefoundthatensurefinancialsustainabilityandmakethesystemafford-ablefortheusers.FurtherinformationisavailableinthefactsheetoftheSuSanAworkinggroupon“costs and economics”(http://susana.org/lang-en/library/rm-susana-publications?view=ccbktypeitem&type=2&id=609).

2.9 Technical components used for achieving UD

Toachieveurinediversion,thefollowingtechnicalcom-ponentsareused:waterlessurinals,urinediversiontoilets,urinepipingtoaurinestoragetank(ortoasewer)andareusesystemfortheurine.FurtherinformationisprovidedinSections 4 to 6.

TherearetwomainvariantsofUDtoilets:UDDTs(urine-diversiondehydrationtoilets-noflushwaterisusedatall)andUDflushtoilets(waterisusedtoflushthefaecesawayandtorinsetheurinecompartment).

3 Reuse of urine as fertiliser in agriculture

3.1 How to use urine as a fertiliser

Whensanitationprojectsaresetupwherecollectedurineistobeusedasfertiliser,consultationwithfarmersandsoilfer-tilityexpertsisessential,astheengineerssettingupthesanita-tionprojectsusuallylackthenecessaryagriculturalexpertise.

3.1.1 Basic guidelines

Thebenefitsofurineasafertiliseranditsapplicationme-thodshavebeenwelldocumented,forexampleinGenschetal.(2011),Richertetal.(2010),SuSanA(2008),Morgan(2007),WHO(2006)andJonssonetal.(2004).Somehigh-lightsfromthesedocumentsaresummarisedbelow.

Urineisaquickactingfertiliserthatcanbeusedforanycropswhichrequirethemacro-nutrientsN,P,KorS(nitrogen,phosphorus,potassiumorsulphur6).Thefertilisingeffectsofthesenutrientsinurinearethesameasthoseofartificialmineralfertiliserifthesameamountofnutriensisapplied.Hence,reuseofurineinagriculturehasthepotentialtore-ducedemandforartificialmineralfertiliser.

6 Sulphurisanimportantmacro-nutrient,neededinapproximatelythesameamountasphosphorus,andoftenlacking.

1414 Belowaresomerulesofthumbfortheuseofurineasaferti-liserwithrespecttoitsnutrientcontent(takenfromJönssonetal.(2004)andothers):ÿ Urineisanitrogen-richcompletefertiliser,containing

alsosodiumandchloride.Thismakesitwellsuitedasfertiliserforcropsthrivingonnitrogen(suchasmaize)andespeciallyforcropsalsoenjoyingsodium,suchaschard(similartospinach).Careshouldbetakenwhenapplyingitforcropssensitivetochloride(suchaspota-toesandtomatoes),althoughyieldsofthesecropscanalsobemuchimprovedbyappropriateurineapplication.

ÿ Ifallurinefromonepersoniscollected,itwillsufficetofertiliseabout300-400 m²ofcropperpersonperyear,e.g.producingforexample250kgofmaize(roughlyequaltothefoodintakeofonepersonperyear).

ÿ Applytheamountofurinethatonepersonexcretesinonedayonone square metrepercroppingseason(thismeansapprox.1.5Lundilutedurinepersquaremetre).Ifweassumethatthereis7gN/Linurine(typicalvalueforSwedishconditions),then1.5Lurine/m2willcor-respondto105kgN/ha,whichisalowtonormaldoseforcereals(dependingonthecountry,soilandexpec-tedharvestfromthefield).

ÿ Thecropyieldalsodependsverymuchonthesoil,andurinewillalwaysworkbetterin“living soils”comparedtobarren,sandysoils.Thenitrogenconvertingbacte-riamustbepresentandcomposthelpsenormously7.

Somerecommendationsforthemethodsonhowurineshouldbeappliedasafertiliserare:ÿ Betweenlastfertilisationandharvestaperiodofat

leastonemonthshouldalwaysbeapplied(forbothlargeandsmallscalesystems).

ÿ Thepersonapplyingtheurinetothefieldsshouldfollowgoodpersonalhygienepractices(thoroughhandwashingafterapplyingtheurine,andifpossiblealsowearingglovesandboots).

ÿ Thebestnitrogenfertilisingeffectisobtainedwhenurineisappliedclosetothegroundanddirectlyincor-poratedorwateredintothesoilinordertominimiseammonialossestotheair.Inordertoavoidleaching,andforclimateswithheavyrainfallorverysandysoils,frequentapplicationofsmallamountsofurineisfavourablebutnotessential.Itisnecessarytobalancemaximumcropyieldwithwhatispracticalinreallife.

ÿ Urineshouldalwaysbeappliedtothesoilnext to the plant(infurrows)butnot ontotheplant.Otherwiseitmightleadto“burning”oftheleaves.Note:“We fertilise the soil, not the plant!”.

3.1.2 Specific advantages of urine compared to other mineral fertilisersAspointedoutbyElisabethKvarnström(StockholmEnvironmentInstitute),oneofthegreatadvantagesofurineisthat“the content of heavy metals and organic compounds is very low, as these only come from the food which you have once consi dered having a high enough quality to ingest. Artificial mineral fertilisers can have a relatively high content of heavy metals.”

Secondly,whenfarmersareabletousetheurinefromtheirfamiliesandneighboursintheirownfields,thisfertiliserisessentiallyforfree(butifurinehastobetransportedoveradistancefromproductiontouse,therearetransportcosts).

Urinefertiliserisalsoindependentfromtheavailabilityandpriceofmineralfertiliserontheworldmarket.Furthermore,urinecontainsmicro-nutrientswhichthesoilmayneedforhighersoilfertility.

3.1.3 Disadvantages of urine compared to other mineral fertilisers

Whilsturineisaprovenfertiliser,ithassomedrawbackscomparedtoartificiallymanufacturedchemicalfertilisers:ÿ Urineis,comparedtoartificialfertilisers,adiluted

fertiliser:TheN,P,KandSconcentrationinurineismuchlowerthaninartificiallymanufacturedferti-liser.Urine’snutrientcontent–expressedwiththein-ternationalfertiliserconventionofN:P₂O₅:K₂O8–isapproximately0.7:0.15:0.22–comparedtoforex-ampledi-ammonium-phosphate(DAP)or(NH₄)₂HPO₄withthecompositionN:P₂O₅:K₂Oof21:46:0.Thismeansthatahugevolumeofwateristransportedwheneverurinefertiliseristransported.

ÿ Urinecontainstracesofpharmaceuticalresiduesandhormones,andpotentialbuyersofcropsfertilisedwithurinemaybeputoffeveniftheactualhealthrisksareextremelylow(see Section 3.2).

ÿ Urineisamulti-componentfertiliser,containingN,P,KandSinaslightlyvariableratio,whichmayormaynotbetherightfertiliserforagivensoilandcrop.Themacro-nutrientconcentrationsinurinemayvarysomewhat(althoughinrelativelynarrowranges),de-pendingonpeople’sdietandwhethertoiletusersaddflushwatertothetoilet.

ÿ Urineisaliquidfertiliser,whilstsomefarmersmaypreferasolidfertiliserifthisiswhattheyareusedto(unlessurineisconvertedtostruvite,byadditionofmagnesiumandraisingpH,whichisalsoaprovenprocess).

8 Thismeans0.15%byweightofP₂O₅,or1500 mg/LP₂O₅(mul-tiply%valueby10,000).

7 Source:PeterMorgan,Aquamor,Zimbabwein2008

15 15 Thefollowingdisadvantagesarenotspecifictourineasafertiliserbutstillneedtobekeptinmind:ÿ Likeotherfertilisers,urinecancauseplantfertiliser

burn(alsocalledleafscorch)ifnotappliedcorrectly.Fertiliserburnisthevisiblesymptomofinsufficientwaterinaplantassociatedwithanoverapplicationoffertilisersalts(saltsdissolvedinurine)9.

ÿ Urineaddssalinitytothesoilandthereforeitsuseasfertilisertopotplantsisonlyrecommendedwhenthesoilcaneasilybeexchanged.

ÿ Alsolikeotherfertilisers,urinecanleadtoground-waterpollution(withnitrate)andnutrientrun-off(resultingineutrophicationinwaterbodies)ifexcessamountsareapplied.

ÿ Urineisamulti-componentfertiliser(withafixedratioofN,P,KandS)whichshouldonlybeapplieduntilthefirstnutrientreachesitsoptimumforthesoil(probablynitrogenorsulphur).Otherwise(ifapplieduntilphosphorusissufficientlysupplied)itcancauseover-fertilisationofnitrogenandsulphur.

3.1.4 Should urine be applied undiluted or diluted with water?

Urinecanbeappliedeitherundilutedordilutedwithwater,dependingonthesoilandthegardener’sorfarmer’spreferences.Somegardenersdiluteurinewithwaterinaratioof1:3,1:5orevenupto1:15,andthisdilutionhasthefollowingadvantages:1. Reducesriskofplant“ fertiliser burn”(see previous

section).2. Enablesirrigationandfertilisationinonestep(also

called“ fertigation”)andwithonepieceofequipment.Butnozzlesofdripirrigationmayclogwhenaurine-watermixtureisusedforfertigation.

3. Reducesodourduringapplication,especiallyifahighdilutionratioisused(1:5orgreater).

4. Minimisestheriskofapplyingtoomuchfertilisertopottedplants,asthepotwilloverflowbeforetoomuchnitrogenisapplied.

Ontheotherhand,applyingurineundilutedhastheadvan-tagethatasmallervolumeofanodorousliquidhastobehandled.

Whenapplyingurineundiluted,fertiliserburnoftherootsisavoidedbyaddingurineinfurrows,somewhattothesideoftheplants(approx.15cm).Odournuisanceisminimisedbyimmediatelycoveringtheurinewithsoilaftertheurinehasbeenaddedtothefurrows.Usually,irrigationwaterisaddeddirectlyaftertheurineapplication.

3.2 Are hormones and pharmaceutical residues in urine problematic for reuse?

TheinformationinthissectionisbasedonWinker(2009)andtheinputfromArnoRosemarin(StockholmEnvironmentInstitute).ThepublicationofLarsenandLienert(2007)isalsorecommendedinthiscontext.

Hormonesandpharmaceuticalresiduesaretwotypesofmi-cro-pollutantswhichoccurinurine(concentrationlevelsareavailableinWinker(2009)),ashumansexcretethemwiththeirurineandfaeces(asaruleofthumb:twothirdsofphar-maceuticalresiduesubstancesareexcretedwiththeurine,onethirdwithfaeces,althoughthefigurescanvarywidelyforin-dividualsubstances10).

Ifurineisreusedinagriculture,someofthesemicro-pollu-tantscanbetakenupbyplantsandtherebyenterthehumanfoodchain.Thisisarisk,butasmallone.Afullevaluationofthepotentialtoxiceffectsofpharmaceuticalsingestedbyhu-mansviaurine-fertilisedcropsisverydifficultandhasnotyetbeendone.Thepotentialrisksfromconsumingcropsfertilisedwithurineneedtobecomparedwiththerisksrelatedtopesti-cideuseoncrops,aswellasantiobioticsandhormonesgiventofarmanimals(poultryandcattle)whichcanbetracedforexampleinmilkandeggs.Attheendoftheday,itcomesdowntoariskanalysisandriskmanagementstrategy.

Animalmanuresandsewagesludgecontainingpharmaceuti-calresiduesandhormonesarealreadynowbeingusedonfields.Itwasshownthattheloadofhormonesandantibioticsinhumanurineisinfactmuchlowerthaninanimalmanure(howevernotallgroupsofsubstancescanbecomparedinthiswayastheyarenotallpresentinanimalmanure).Withsewer-basedsanitationsystems,thesetypesofmicro-pollu-tantsarenotremovedinconventionalsewagetreatmentplantsandarethusdischargedintosurfacewaterbodiesandcanreachthegroundwater(detectedconcentrationsofpharma-ceutialresiduesingroundwaterareintheorderof50 ng/LinseverallocationsinGermany).

Whencomparingthetwoapproaches(dischargingurinewithtreatedwastewatertosurfacewaterversusurineapplicationtosoil),itislikelytobesafertodischargeurinetosoilratherthanwater.Themicro-pollutantscanbedegradedbetterintheaerobic,biologicallyactivesoillayers(highconcentrationofmicro-organismspercubiccentimetre)withlongerresidencetimesthaninwaterbodieswhoseecosystemsaremuchmoresensitive.Thishaspreviouslybeenproveninthecaseofhor-mones11,andmoreresearchisneededtoproveitforothertypesofmicro-pollutantsaswell.

10 Tobemoreprecise:around70%ofpharmaceuticalsubstancesareexcretedviaurineaccountingfor50%oftheoverallecotoxicologicalrisk(LarsenandLienert,2007).Theecotoxicologicalriskofthefractionofpharmaceuticalresiduescontainedinurineandinfaecesisthesameregardlessofthehighernumberofsubstancesexcretedviaurine.11 Thisfindingisofparticularrelevanceregardingtheartificialhormoneswhichareexcretedinurinefromwomentakingthecontraceptivepill.

9 Rootcellsactivelyabsorbfertilisersaltsfromsoilsolution,andundernormalconditionsmaintainahigherosmoticpressure.Ifexcessfertilisersaltsareapplied(i.e.concentratedurinewhichisnotdiluted),theosmoticpressureofthesoilsolutionisraised.Thismeanswatercan-notenterthecellandmayactivelymoveoutofit.Theresultinginjuryisknownasfertiliserburnorphysiologicaldrought(RobertHolmer,Ecosanresdiscussionforum,2008).

1616 Terrestialsystems(soil)aremoresuitablefornaturaldegra-dationofpharmaceuticalsthanaquaticsystemsbecause:ÿ Theoxygenlevelsarearound50,000timeshigher

insoilthaninwater.ÿ ExposuretoUVlighthelpstodegradepharmaceuti-

cals,althoughthisonlyappliestothesurface(1-2cmsoildepth)andcropscanshadetheground.

ÿ Thehighspecificsurfaceofsoilparticlesmaximisestheexposureofadsorbedchemicals,maximisingthekineticsofdegradation.

ÿ Thewidebiodiversityofthefungalandbacterial floraofsoilisadaptedtodegradevarioustypesoforganicmolecules,bothcomplexandsimple.

Finally:“Drug residues in sustainable sanitation products used to supply plant nutrients can hardly be a serious issue in regions where malnutrition, groundwater and surface water pollution due to inappropriate sanitation and irrigation with untreated wastewater is a reality”12.

3.3 Is urine an “organic fertiliser” and can it be used in organic farming?

Thedefinitionof“organic fertiliser”maybeaccordingtotwodifferentcategories:1. Organicintheanalytical chemistry sense(acom-

poundwhichcontainscarbonandmaycontainotherelementssuchashydrogen,oxygen,nitrogen).

2. Organicina“green”, “eco” or “natural”sense.

Freshurinecontainsureaandisthusanorganicfertiliserintheanalyticalchemistrysense.Storedurinecontainsammo-niaandnourea(see Section 2.6.3),andisthereforenotorganicbutrathera“mineral fertiliser”intheanalyticalchemistrysense.Inotherwords:Urineisbothanaturalmineralisedormineralfertiliser,andanorganic,ecologicalornaturalferti-liser13.

The“organic farming”14regulationsdifferbetweencountrieswithregardstowhichtypeoffertiliserisallowed(andisinthiscontextcalled“organic fertiliser”).Forexample,countriesintheEuropeanUnionaresubjecttotheEUorganicfarminglegislation,whereurineisnot consideredanallowedfertiliser.InChinaontheotherhand,urineisconsideredanaturalfer-tiliserandthusallowedinorganicfarming.Makingurineal-lowedfororganicfarmingintheEUremainsanimportantchallenge.Itshouldbepossibleasurineisanaturalfertiliserwithasimilarcompositionasforexamplepigurine.

4 Waterless urinals

Thischapterdrawsonthepublicationbyv.MünchandDahm(2009).Note:“waterless”means“without water”inEnglish.Somepeoplealsousetheterm“waterfree”.Wedonotrecommendanyparticularurinalmodelinthispublication.

4.1 Definition and purpose

Aurinalisaspecialisedtoiletforurinatingonly,whichisusedwhilestandingup,andisdesignedprimarilyformaleusers.Urinalsarewidelyusedaroundtheworld,especiallyinpublicfacilitiesbeingfrequentedbyalargenumberofboysandmen,becausetheysavespaceandcostscomparedtotoi-lets(simplerdesign;noseparatecubiclesneeded,althoughinmanycasesseparationpanelsareinstalled).Urinalsarenotcommonlyusedinprivatehouseholdsduetotheiradditionalspacerequirements.

Alimitednumberofurinalsforfemales(tobeusedwhilestandingorsquatting)areonthemarketbuttheyarenotwidelyacceptedforvariousreasons,suchasfemaleshavinggreaterneedsforprivacyastheyhavetopartiallyundress.Squatting-typeurinals(squattingpanswithoutanoutletforfaeces)aresometimesusedforgirlsinAfricanorAsianprima-ryschoolstosaveonspaceandcostscomparedtotoilets.

Conventionalurinalsareflushedwithapprox.4Lofwatereitheraftereachuseorbasedonatimer,whereaswaterlessurinals(see Figure 1)usenowaterforflushing.

Themainmotivationforusingwaterlessurinalsisto:1. Savewaterandhencecosts–theseurinalsare

connectedtoasewersystem.2. Allowcollectionofpure,undilutedurineforusein

agricultureasanitrogenandphosphorus-richfertiliser–theseurinalsareconnectedtoaurinestoragetank.

Waterlessurinalsarethefirstandeasieststeptowardsurinediversionand,possibly,ecologicalsanitation(ecosan).

12 Source:JörnGermeronEcosanresdiscussionforum,April2009.13 Source:HåkanJönsson(onEcosanresDiscussionForum,De-cember2008,http://www.ecosanres.org/discussion_group.htm)14 Apossibledefinitionof“organic farming/agriculture”:Organicagricultureisaproductionsystemthatsustainsthehealthofsoils,eco-systemsandpeople.Itreliesonecologicalprocesses,biodiversityandcyclesadaptedtolocalconditions,ratherthantheuseofinputswithadverseeffects.Organicagriculturecombinestradition,innovationandsciencetobenefitthesharedenvironmentandpromotefairrelationships

andagoodqualityoflifeforallinvolved(source:InternationalFederationofOrganicFarmingMovement,http://www.ifoam.org/).

Figure 1. Waterless urinals for men. Left: Centaurus model of Keramag company. Right: Plastic urinal from Addicom, South Africa, with EcoSmell-stop device (sources: (left) E. v. Münch, Delft, 2006; right: Addicom).

17 17

4.2 Historical development of waterless urinals

In1894,Mr.BeetzfromAustriapatentedadrainagedevice(trap)whichallowedurinalstobemade"flushless".Thetrapusedasealantliquid(themechanismisexplainedin section 4.4.3).ThispatentwasthencommerciallyexploitedbythecompanyF.ErnstEngineerinZürich,Switzerlandwhowasthesolesupplierofwaterlessurinalsworldwideforapproximately100years.

Intheearly1990s,watersavingcameintofashionandseveralcompaniesappearedonthemarketusingderivativesoftheBeetzpatent.AtmoreorlessthesametimeHepworth,aUKplumbingmanufacturer,patentedadrainagedevice(onewayvalve)whichwasinfactaflattube.Asimilardeviceisusedinsmallboatstodrainspraywaterfromthebilge.Derivativepatentsoftheflattubeelementsareusedtodayinwaterlessurinalsandmarketedbyvarioussanitarywarecompanies,forexampleKeramag(modelCentaurus).

In2002,aSwissengineerlivinginSouthAfrica(PeterDahm)patentedaonewayvalvesimilartotheflattubedesignbutusinga“curtain”mechanisminordertoreducemaintenancerequirements.Thisunit,whichisnowusedinwaterlessuri-nalsofseveralsuppliers,issoldunderthenameofEcoSmell-stop(ESS).

Atpresent,Germanyisprobablythecountrywiththehighestnumberofwaterlessurinalspercapita,asthepriceofmunici-paltapwaterinGermanyisoneofthehighestintheworld,andGermansareconsequentlyveryinterestedinallwater-savingopportunities(1,200waterlessurinalsofKeramagareinuseinthepublictoiletsofHamburginGermany).

Waterlessurinalsarecommonlyusedinindustrialisedcoun-triesforpublictoiletswhicharenotconnectedtothesewer(suchasreststopsalonghighways).Itwouldbebeneficialiftheybecamewidelyusedindevelopingcountriesaswell.

4.3 Odour control methods (general)

Togainwideacceptance,waterlessurinalsmustmeettheacceptedstandardsapplicableforconventionalwaterbornein-stallations.Theirodouremissionmustbelessoratworstequaltotheoldsystem.Toachievethisodour-freeperformancefouraspectsareabsolutelycrucialforwaterlessurinals:1. Suitablemechanismtoblocktheodourcomingback

fromthesewerandurinestoragetank,forexample(discussedindetailinthesections below):

„ rubbertubeseal „ curtainvalveseal „ sealantliquid(blockingfluid) „ plastictabletennisballplacedinafunnelwhich

isinsertedintheopeningofajerrycan;or

„ placeurinalinawellventilatedarea(locatedoutside

ofhouses),andputupwithsomeodour(maybepossibleforruralareas).

2. Appropriatesurfaceoftheurinalbowl(smooth,non-sticky,e.g.withwaxcoating).

3. Correctlydesignedinterrelationbetweenurinalbowlandthedrainfittingtominimisecreviceswhereurinecanaccumulate.

4. Onanoperationallevel:athoroughmaintenancere-gardingthebowlandtheodourblockingdevice.Thesurfaceoftheurinalbowlisusuallywipedcleanonce,twiceorseveraltimesperdaywithamoistsponge.Fortheodourblockingdevice,themaintenancedependsonthespecificationsoftheurinalsupplier(see below).

4.4 Odour control for connection of urinal to sewer or storage tank4.4.1 Rubber tube seal

Forthismethod,aflatrubbertubeisused(Figure 2).Thisrubbertubeisflatatthebottomwhennotinuse(andhenceblocksodourfromthesewerorurinestoragetank)butopensupwhenurineisflowingthrough.Thisone-wayvalveallowspassageofgritupto2mm.

Urineprecipitates(“urine stone”),whichsticktotherubbertubeneedtobecleanedoffwithwaterregularly(otherwisetheflatrubbertubedoesnotcloseproperlyanymore).Thecleaningfrequencydependsonthenumberofusesperday(cleaningoncepermonthunderaveragecircumstancesmaybesufficient).Therubbertubeneedstobereplacedaroundonceayear.Therubbermaterialissensitivetosolvents,acids,anddeodorisingtabletsoftenusedinurinals.Therefore,theuseofacidsoraggressivecleaningagentsmustbeavoided.ThissystemisusedforexamplebytheGermancompanyKeramagintheirCentaurusmodel.

4.4.2 Curtain valve seal

Thecurtainvalvesealissimilartotherubbertubeseal,butwasdesignedtoreducemaintenancerequirements.Thistypeofone-wayvalvehas“self-cleaning properties”asasmallpressuredifferenceforcestheurinetowetthewholeinnersurfacebetweenthe“curtains”,thereforeflushingthemclean.Theelementisdesignedinamannertominimisebuild-upofurineprecipitatesorurinesludgeandthuskeepingthesealingsurfacesclean.Liketheflatrubbertubeseal,thisone-wayvalvealsoallowspassageofgritupto2mm.Thesiliconcurtainelementisintegratedintoaplasticcasing(Figure 2).TheplacingoftheEcoSmellstop(ESS)elementintoaplasticsleevehastwopurposes,firstlytoguaranteethat

1818 noodourfromthesewerorurinestoragetanksescapesintotheroom,andsecondlytoallowaneasyremovaloftheESSunitformaintenancepurposes.Forreplacementofthecurtain(ifsimplecleaningisnolongerpossible),theentireplasticcasingisremovedwithasmallplasticextractortool(Figure 3),thendiscardedandreplacedwithanewESS.Thisreplacementprocessmaybenecessaryaboutonceperyearandtakesonlyafewseconds.ItcanbeperformedwithouthavingtotouchtheESSelementbyhand.

TheESSmanufacturingprocessisnotsimpleastheinjectionmouldsareofextremecomplexity,andthemixingandinjec-tionrequiresverysophisticatedmachinery.Forthisreason,itisnotyetpossibletomanufacturetheESSlocallyindevelo-pingcountries,butitcaneasilybeimportedasitissmall,light-weightandlow-cost.ThispatentedESSunitisusedbythecompaniesAddicom,KellerinventAGandF.ErnstInge-nieurAG15since2006.

4.4.3 Sealant liquid (blocking fluid)

Thissystemworkswithasealantliquid(alsocalledblock-ingfluid)whichismadeofvegetableoilsoraliphaticalcohols–theyarebiodegradableifreleasedtothesewerorurinestor-agetank.Thesealantliquid,withaspecificgravityofaround0.8,floatsontopoftheurinecontainedinthetrapandthusconstitutesaneffectiveodourbarrier.Urineimmediatelype-netratesthesealantliquidandflowstothedrain.Urinepre-cipitatesarecollectedinacartridgeorinnercylinderofthetrap.Themaintenanceprogramofwaterlessurinalswithasealantliquidconsistsofcleaningoftheurinalbowl,andtheregularexchangeofthecartridge(orthesealantliquid,see Figure 4 ).Therequiredexchangefrequencydependsonthenumberofusers.Witheachuseandinbetweenuses,someurineprecipitatesaccumulatewhicheventuallyrendersthetrapinoperative.Foreignobjects,suchascigarettestubs,acceleratetheprocess.Atthispointthecartridgehastobecleanedorreplaced.

Ifthetrapstartstosmell,whileitisstillfreelypassingurine,merelyarefillwiththesealantliquidcanresolvetheproblemforsomedesigns.IntheUSA,thisiscurrentlythemostcom-montypeofwaterlessurinal,asundercurrentlegislationonlytheseliquid-filledtrapsareapprovedforwaterlessurinals.

Figure 2. Two types of odour seals for waterless urinals. Left: Flat rubber tube (Keramag Centaurus). Right: (left side) See-through pipe fitting; (right side) see-through EcoSmellstop (ESS) unit showing the blue silicon curtain one-way valve inside (source: (left) E. v. Münch, 2007; (right) Addicom).

Figure 3. EcoSmellstop (ESS) unit with pipe fitting and extractor. Inside the ESS is the silicon curtain valve (source: Addicom).

Figure 4. Example instruction sheet, showing replacement of sealant liquid for Uridan urinals (other urinals with sealant liquid have a similar maintenance routine) (source: Uridan).

19 19 Possibleadvantagesofsealantliquidsystemsinthecontextofdevelopingcountriesmayinclude:ÿ Noneedtobeexchangedwhenfullwithprecipitates,

butcanbeeasilycleaned.ÿ Afterbeingcleaned,theycanberefilledwithsome

thickcookingoil16(thisdoesnotlastaslongastherecommendedliquid,butisavailablealmostanywhere).

Thereisnoclearevidenceyetwhichofthethreesystemsdis-cussedaboveisbetterforlow-cost,low-maintenanceapplica-tions,andthismaydependonthepreferenceoftheindividu-alsorcompaniesresponsiblefortheurinals’maintenance.

4.4.4 Other methods for the odour seal

Othermethodsforodourcontrolareonthemarket(see also suppliers listing in Appendix).OneexampleisthesystembyUrimatwherethesealantliquidisreplacedbyafloat(hy-drostaticfloatbarrier)whichismagneticallyactivatedthusopeningthechanneltotheoverflowchamber.Forlow-costapplicationsindevelopingcountries,thissystemhasthedis-advantageofahighercomplexitycomparedtothesystemsdescribedabove17.

Small-scalesimplesystemsmayutilisejustapipeorhose(with-outanyodourtrap)connectingtheurinalwiththetank.Here,theodourcanbecontrolledbyhavingtheurinepipe(fillinghose)goingdowntoalmostthebottomofthecollectionvessel,thuscreatingaliquidsealinthecollectionvessel.Anotherop-tionistopoursomecookingoilintothecollectionvessel,thuscreatingathinsealantfilminthecollectionvesselitself.Acut-offcondomontheurineoutletpipehasalsobeenused.

Anotherverysimpleoptionforawaterlessurinalisthe“eco-lily”,whereaplasticfunnelisinsertedintotheopeningofaplasticjerrycan.Anoldlightbulboratabletennisballisplacedintothefunneltoactasodourseal(itshouldfloatupwhenurineentersthefunnelbutcouldendupstickingtothefunnel).Thedisadvantageofthelightbulbovertheplasticballisthatthesolderandmetalcaponthelightbulbcontainsheavymetalswhichcancontaminatetheurine.

4.5 Further design information

Thespacerequirementofaurinalislessthanthatofatoi-let,whichmakesthempopularforanyvenuewheremanymenneedtourinate(soccerstadiums,restaurants,schools,etc.).Waterlessurinalsareusuallywallhunganddonotrequirepipingforflushwaternorflushingdevices,thusallowingaconsiderablecostsaving.Theflushingdevicesaswellasthetraditionalwatertrapsintheoutletpiping(U,Por“bottle”shaped)ofconventionalurinalstendtoattractaconsiderableamountofvandalism(hencewaterlessurinalscanfurtherre-

ducemaintenancecosts).Waterlessurinalsdonotneedtobeconnectedtoasewerbutcanbeconnectedtoaurinestoragetankinstead(importantforremotelocationsnotconnectedtosewers).Obviously,waterforhandwashbasinsandwater-f lushedtoilets(ifnotreplacedbywaterlesstoilets)isstillrequirednexttothewaterlessurinals.

MaterialsUrinalbowlsaretypicallymadeofacrylic,ceramic,stainlesssteelorglass-fibrereinforcedpolyester,butcanalsobemadeofsimplelow-costplastic,providedthatithasasmoothsur-face(forodourcontrol).Self-constructionofinexpensivewaterlessurinalsisalsopossible.Whenusingplasticurinalbowls,oneoptionistouselinearlowdensitypolypropyleneasitisoneofthemostinertplastics(non-sticksurfaces).Thehotproductionprocessat180°Cguaranteesasmooth,non-poroussurface,thereforeminimisingbacterialbiofilmgrowth. 

Converting water-flushed urinals to waterless urinalsItisinprinciplealsopossibletoconvertconventionalwater-flushedurinalstowaterlessurinals(dependingonthebowldesign),forexamplebyusingtheESS,whichisalsosoldasastandaloneunit.ItisveryimportanttogetasnugfitoftheESSintotheurinaldrain.

4.6 Use and maintenance of waterless urinals

Theinstructionsgivenbelowarenotforurinalsathouse-holdsbutforinstallationsatinstitutionsorpublicplaces18.Athouseholdlevel,differentmaintenanceroutinesapplythanthosedescribedbelowduetomuchlowerfrequencyofuse.Theurinalbowlshouldbecleaneddaily,justlikeanyother(water-flushed)urinal.Thereare100%biodegradableclea-ningsolutionsonthemarketthataresimplysprayedontotheurinalbowlandnotwipedoff.Forexample,URIMATMB-AktivReinigerwithtensidesisusedforthe50waterlessurinalsintheGIZheadquartersinEschborn,Germany.

15 ThecompanyF.ErnstIngenieurAGusedthesealantliquidsys-tem(initswaterlessurinalsinstalledmostlyinSwitzerlandandGerma-ny),butchangedovertotheEcoSmellstopsysteminOctober2006,andisnowretrofittingallofitsapprox.100,000urinalswhichwereinstalledpriortothatdate(F.ErnstAGoperatesitsurinalsunderamaintenancecontractshouldtheclientnotdecideotherwise).16 HakanJönsson:“the important properties of oil for this use are density lower than water - most oils have a density around 0.7 kg/L - this way it floats on urine; hydrophobic - maintains a lid above the urine and its content; and both of these are shared by cooking oils. Cooking oils are partly unsaturated and will thus oxidise faster and need replacement, but this is secondary to them being generally available”.17 HansKellerusedtorunthecompanyUrimatandhasthepat-ents.ButhenowrunsKellerInventwhichboughtFErnstAG(henceMr.KellermovedfromhydrostaticfloatbarriertoESS).18 Incountrieswithwide-spreadsewersystems,urinalsarenotusedathouseholdlevel.Butincountrieswhereonsitesanitationiscom-mon,waterlessurinalsathouseholdlevelareusedtogetherwithurinedi-versiondehydrationtoilets.

2020 Anytypeofodourseal(beitflatrubbertube,curtainsealorsealantliquid)needstobecleaned(orreplacedifcleaningisnolongerpossible)atregularintervalstokeepitfullyfunc-tional.Thefrequencyofcleaningorreplacementoftheodoursealsystemdependsmainlyonthenumberofusesperdayaswellasuserandcleaningstaffbehaviour(intermsofforeignobjectsdiscardedinurinal).Itcanthereforevarywidely,rangingfromonceaweektoonceeverysixmonths.

TheflatrubbertubeandESSunitscanbecleanedmanytimesbeforehavingtobereplaced.Somesealantliquidcartridgescannotbecleanedbutneedtobereplacedwhentheyfail,whilstforexampletheUridansystemcanbecleaned,andthesealantliquidreplaced,anynumberoftimes.Togiveanexample:AccordingtoinformationgivenbyAddicom,anESSelementcanlastfor16monthswithcarefulmaintenance,suchassprayingtheurinalbowlregularlywiththecleaningagent“DestroySmell”(containingtensidesandactivemicroorganisms),andremovingtheESSelementandrinsingwithdilutedcitricacidtoslowdowntheformationofurineprecipitatesonthecurtains.

Empiricalevidencegatheredinlow-incomesettingsinSouthAfrica(suchaspublicparksandtaxiranksinJohannesburg)since2004suggeststhatthecurtainseal(ESSsystem)canperformwithless maintenance thantheflatrubbertube.Inregionswherediligentmaintenanceofurinalscannotbegua-ranteed(suchaspublictoiletsininformalsettlementsinsub-SaharanAfrica),theESSsystemmaythereforebeabetterchoiceofthetwo.Moreside-by-sidecomparisonsbetweendifferentwaterlessurinaltypesarerequired,particularlyforurban,low-incomeareasindevelopingcountrieswithapoten-tiallyhighlevelofabuseandneglect.

4.7 User acceptance of waterless urinals

Experienceworldwidehasshownthatwaterlessurinalsen-joythesamelevelofuseracceptanceaswater-flushedurinalsdo,sinceforthemaleusersthereisnobehaviourchangere-quired(manyusersdonotevennoticethattheyareusingawaterlessurinal).Forthosemenwhoareshyanddonotlikeusingurinalsinpublicplaces(forlackofprivacy),itmakesnodifferencewhethertheurinaliswater-flushedornot.

Incultureswhereanalwashingwithwaterispracticed,eachurinalcanbeinstalledinacubicletoguaranteeprivacy.Forexample,manyMuslimmaleswashtheirgenitalswithwaterafterurinating,whichrequireswatersupplyandseparatedrai-nagefacilities.Priortoprovidingwaterlessurinals,onehastoestablishwhetherthecommunityinquestioniswillingtoacceptsuchfacilities.Notealsothatinsomeculturesmenareusedtosquattingwhenurinating.Waterlessurinalscouldbeplacedonthegroundinsteadofbeingwall-hung.

Insomeinstances,theremaybeapsychologicalbarrierofusersorcleaningstaff(“if a urinal is not flushed it cannot be hy gie-nic”).Thethoughtthatwaterisalwaysequaltohygieneisanunderstandablemisconception.However,whenfacedwithawell-functioning,odourlesswaterlessurinal,thosefearsarequicklyalleviated,whichiswhydemonstrationprojectscanbeuseful.Today’swaterlessurinalsaredesignedtobeodour-lessandsimpletomaintain.

Aswaterlessurinalsareanoveltyformanypeople,anysmellemittedfromawaterlessurinalgetsblamedonthenewsystem.Howeverasmellywater-flushedurinalisacceptedasnormalastheyhavealongodoroushistory.Itisafactthatanytypeofurinal(water-flushedorwaterless)willnotsmellifwellmaintained.Theextentofmaintenancerequiredforwater-lessurinalscanbehigherorlowercomparedtowater-flushedurinals,dependingonthetypeofwaterlessurinalused(asexplainedabove).

4.8 Suppliers and costs of waterless urinals

Thefollowingoptionsexistforbuyingwaterlessurinalsindevelopingcountries:ÿ Importedwaterlessurinalswithorwithoutpatented

odourcontroldevicesÿ Plasticwaterlessurinalsmanufacturedlocallyand

importedESSelementorliquidsealinsertedforodourcontrol

ÿ Self-constructedwaterlessurinalsmadefromplasticcontainers.

Forlowcostapplications,simpleplasticurinalsmaybeagoodoption.Thesecanbeproducedina"rotationmoulding"pro-cess.Thisisacheapandsimpleprocesstomakeasingle-skintypeunit,whichcanbereplicatedinanycountry.

SupplierslistsforwaterlessurinalsareprovidedintheAppendix. Forreferenceinstallationseithercontactthemanufacturersorseethecasestudydescriptionsofsustainablesanitationprojectsonwww.susana.org.Manyoftheseprojectsincorpo-ratewaterlessurinals.Photosofwaterlessurinalsarealsoavailablehere:http://www.flickr.com/photos/gtzecosan/sets/72157613881735035/

4.9 How to choose the right type of waterless urinal

Whenchoosingawaterlessurinalfromthelargerangeofsuppliersandmodels,thefollowingguidequestionscanbeused(forwaterlessurinalsininstitutionsandpublicplaces19):1. Dotheurinalsneedtobeascheapaspossible?2. Dotheuserspreferceramicurinalsoverplasticurinals?

19 Note:Forwaterlessurinalsathouseholds,themaintenancecon-siderationsarequitedifferent.Householdswanttousemaintenancema-terialsthatcanbefoundinageneralstoreataminimalcost.

21 21 3. Aretheurinalsavailablelocally(localdistributor)ordotheyhavetobeimported?

4. Doesthesupplierofferyoutogetincontactwiththesuppliers’existingclients?

5. Doesthesupplierhavereferenceletters?6. Howmanyunitshasthesuppliersoldalready?7. Dotheurinalsneedsparepartsandcantheybe

obtainedlocallywithminimalwaitingtimes?8. Istherelikelytobeanyvandalisminthelocation

wheretheurinalswillbeinstalled?9. Whowilldothemaintenanceandwilltheybe

diligentorratherunreliable?10. Afterhowmanyusesdoestheodoursealneed

replacement(orafterwhattimeperiod)?11. Howlongdoeseacheventofodourseal

replacementtake?12. Howdifficultistheodoursealreplacementroutine?

5 Urine diversion toilets

5.1 Definition

Urinediversion(UD)toiletsaredesignedtonotmixurineandfaecesatthepointofcollectioninthetoilet.TherearetwomainmaintypesofUDtoiletsandbothtypescanbebuiltindoors:1. Urine diversion dehydration toilets (UDDTs) Noflushwaterisused.Thesetoiletsareoftencalled

“ecosan toilets”butthiswouldwronglylabeloneparticulartoilettypeasthe toilettobeusedinecosanprojects.

2. UD flush toilets Waterisusedtoflushthefaecesawayandto

rinsetheurinecompartment.

Thesetoiletsmaybeimplementedwithinnewsanitationsystemsormaycomplementexistingsystems.Inanycase,additionalpipeworksuchasapipefromthetoiletstotheurinestoragetanksbecomesnecessary(see Section 6).

5.2 Basic design information for UD toilets

CarefulplanningandappropriatedesignisessentialforsuccessfulapplicationofUDtoilets.Theyshouldbedesignedorchosenbasedontheneedsandthecustomsoftheusers.Thepreferredpostureoftheusercanbe:ÿ Sitting toilets (withpedestals):

thesecanbewall-hungorfloormounted;orÿ Squatting toilets(withsquattingpans):manypeople

areusedtotoiletswhichareusedinasquattingposition.

FurtherdesignconsiderationswhichareimportantforalltypesofUDtoilets(detailsareprovidedinSection 5.3 and 5.4):1. Dotheuserswashtheiranalareawithwaterafter

usingthetoiletsordotheyusetoiletpaper(“washers”asopposedto“wipers”)?ThisiscustomaryinmanyMuslimandBuddhistculturesbutmayalsobelinkedtofactorsotherthanreligion.

2. Needsofdisabledpeople,elderly,childrenwhenusingthetoilet

3. Specificneedsoffemales(menstrualhygiene;privacyandsecurityneeds)

4. Odourcontrolfortheurinecollectionsystem5. Willthetoiletbeanindoororanoutdoortoilet

(indoorislikelytobecomethenorminthefutureandispossiblewithUDtoilets)?

5.3 Urine diversion dehydration toilets (UDDTs)

ThissectiononUDDTscontainsonlybasicinformation.Formoreinformationonthisimportanttechnologyanditsoperationandmaintenancerequirementssee:ÿ TechnologyreviewonUDDTsbyGIZ(http://www.gtz.de/en/themen/umwelt-infrastruktur/

wasser/9397.htm)ÿ BergerandLorenz-Ladener(2008);Morgan(2007);

Austin(2006);Kvarnströmetal.(2006);WinbladandSimpson-Hebert(2004)

ThebenefitsofUDDTscomparedtopitlatrineswerelistedinSection 2.3.2.

5.3.1 Basic design information

UDDTsdonotusewaterforflushing.Theyuseaverysim-plesystemwheretheurineiscapturedinabowlwhichisintegratedinthefrontofthetoiletpedestalorsquattingpan.Fromhere,theurineisdrainedofftoastoragecontainer.

Forthefaeces,astraightdrop(orchuteiftoiletsareonseve-rallevelsinthehouse)isprovidedfromthetoiletpedestalorsquattingpantoacollectionvaultorbin.

Aventpipeisprovidedtoventilatethefaeceschamber,removeodourfromtheroomandtospeedupthedryingprocess.UDDTsarenot designedforcompostingtotakeplaceinthefaecesvaultbutjustfordrying.

Inregionswherepeoplepractiseanalcleansingwithwater,athirdoutletholeisused,tocollectandtreattheanalwashwaterseparatelyfromurineandfaeces(see Figure 5).Itisbestnottomixanalwashwaterwithurinetokeeppathogenlevelsintheurineataminimum,ifurineistobeusedasafertiliser.

2222 Theanalwashwatercanbeinfiltratedinagravelfilterortreatedtogetherwithgreywaterinasubsurfaceconstructedwetland.UDDTsareespeciallypopularwhereverthereiswaterscarcityandademandforcheapfertiliser.Theycanbebuiltindoorsoroutdoors.

5.3.2 Odour control for urine collection system

Anodoursealmaybeusedontheurinepipeifthetoiletisindoors,especiallyinsystemswithmanytoilets(thesametypesofsealsasforwaterlessurinalscanbeused,includingtheESS(see Section 4.3)).SomeUDDTsevenhaveaninte-gratedfan(suchasthetoiletofSeparett),whichremovesodourfromboththefaecesbucketandtheurinepipe.Noseparateodourblockingdeviceisnecessaryinthiscase.

ForoutdoorUDDTswithindividualurinestoragetanks,theconnectiontotheurinestoragetankisusuallydirect,with-outanyodourtrappingdevice.Thefaeceschamberhasaventpipetoremoveodourfromthetoilet,anddryadditivesassistinodourcontrol.

5.3.3 Construction methods and materials

Possiblematerialsforthetoiletpedestalorsquattingpanare:ceramic,concrete,acrylicorglass-fibrereinforcedplastic.Thetoiletcaneitherbeself-constructedorprefabricated.Metalcomponents(exceptforstainlesssteel)cannotbeusedsinceurineiscorrosive.

5.3.4 Use and maintenance ThemainoperationalrequirementwhenusingUDDTsisthatthefaecesvaultiskeptasdryaspossible(noadditionofurineorwater).Theurineandfaecescontainersneedtobeemptiedwhenfull.

Coveringmaterialshouldbeaddedtothefaecesvaultaftereachdefecation.Coveringmaterialcanbeash,sand,soil,lime,leavesorcompostandshouldbeasdryaspossible.Thepurposeofaddingcoveringmaterialisto:ÿ reduceodourÿ assistindryingofthefaeces(tosoakupexcessmoisture)ÿ preventaccessforfliestofaecesÿ improveaestheticsofthefaecespile(fornextuser)ÿ increasepHvalue(achievedwhenlimeorashisused).

5.3.5 Project examples

UDDTsareusedinmanyruralandurbansustainablesanitationprojectsworldwide.Theyhavebeeninstalledathouseholds,schools,prisons,universitiesetc.andforpublictoilets(seeforexampleSuSanAcasestudieson:http://www.susana.org/lang-en/case-studies).

5.4 UD flush toilets5.4.1 Overview on historical development

UDflushtoiletswereinventedinSwedeninthe1990’s(Kvarnströmetal.,2006).Theywerefirstadoptedineco-villagesandholidayhomes.Today,theyarealsousedinsomehousingprojectsandpublicbuildingsinseveralcountriesinEurope,althoughstillonlyatapilotscale.Adetailedstudy(calledNOVAQUATIS)onUDflushtoiletswasconductedbyEawag,Switzerland(LarsenandLienert,2007).

5.4.2 Basic design information

ThebenefitsofUDflushtoiletscomparedtoflushtoiletswerelistedinSection 2.3.1.TheUDflushtoilethasaparti-tioninthetoiletbowlisolatingabowlforurineinthefront,andabowlforfaecesintheback.ThebowlissimilartobowlsusedforUDDTs,exceptthatfortheUDflushtoilet,waterisusedtoflushthefaecesaway.Theflushingmechanismfortheurinepartisdesignedinoneoftwoways:1. Theurinepipestaysopenandthereforereceivesa

certainamountofflushingwaterwhenthebowlisflushed(see Figure 6);or

2. theurinepipeisclosedbyavalveandthereforereceivesnoflushingwater(thisisthecasefortheRoedigerNoMixtoilets).

Figure 5. left: Indoor UDDT (pedestal type) in Johannesburg, South Africa in the house of Richard Holden (source: E. v. Münch, 2006).Right: UDDT squatting pan in Bangalore, India, with three holes: the area in the front is for anal washing, middle is for faeces and back is for urine (source: D. Schäfer, 2008).

23 23 TheUDflushtoiletscanreducewaterconsumptioncom-paredtoconventionalwater-flushedtoiletsbecausethewaterrequiredforthe“urine flush”islessthantheamountforthe“ faeces flush”.

UDflushtoiletscanalsobecombinedwiththeconceptofvacuumtoilets(realisedforexamplebythecompanyRoedi-gerforapilotprojectinBerlinStahnsdorfandbytheSwe-dishcompanyWostManEcology,seeAppendix).Thistypeoftoiletcollectsurineandasmall,concentratedamountofbrownwater(faeceswithabout1Lofflushwater).

5.4.3 Odour control for the urine collection system

Fortheurinepipe,severaltypesofodoursealsareusedbythetoiletmanufacturers,suchasavalve(RoedigerNoMixtoi-lets),aurine/waterseal(Gustavsbergtoilets)oranovelsiliconseal(Dubblettentoilets).

OdourlocksintheUDtoilet’surinepipearerequiredtopre-ventbackflowofodourintothetoiletroom;butthesearenotnecessaryinthecaseofshorturinepipesystemsofupto3-4m.Forthefaecespart,odourcontrolisachievedbyawatersealinaU-bend(justlikeforconventionalflushtoilets).

5.4.4 Materials

AsUDflushtoiletshavebeendesignedforusersinhigh-incomecountries,theyhavebeenmanufacturedonlyincera-micandhaveasimilarappearancetoconventionalflushtoilets.

5.4.5 Use and maintenance

ThefaecessectionofUDflushtoiletsiscleanedinthesamewayasforconventionalf lushtoilets(withabrush).Toiletpaperisflushedawaytogetherwiththefaeces.

AparticularproblemfoundwiththeRoedigerNoMixtoiletisthattoiletpaperthrownintotheurinalbowlisnotflushedawaywiththesmallurineflush;andhencemorethanoneflushbecomesnecessary–negatingthewatersavingeffectofthistypeoftoilet20.

AnotherproblemoftheRoedigerNoMixtoiletisthatthevalveontheurinepipecangetblockedovertime.Inthiscase,urineisnolongercollectedinthestoragetankbutflowstothefaecessectionofthetoilet,orthevalveisnotclosinganymorecausingodourproblemsinthetoiletroom.Therefore,theuserneedstocarryoutpreventativemaintenancebyaddingdilutedcitricacidtothevalveoncepermonthforaperiodof24hours.

5.4.6 Project examples

UDflushtoiletsareusedinsomeindustrialisedcountriesandtheyarenotalowcostoption.SofartheyaremainlyusedinSwedenandinsomeprojectsinGermany,theNetherlands,SwitzerlandandAustria.

Twoprojectexamplesforwhichdetaileddescriptionsareavail-ableare(bothonhttp://www.susana.org/case-studies?showby=default&vbls=2&vbl_2=9&vbl_0=0):ÿ UrineandbrownwaterseparationattheGIZ

mainbuilding,Eschborn,Germanyÿ Urbanurinediversion&greywatertreatment

system,Linz,Austria

5.5 Suppliers and costs for UD toilets

InformationonmodelsandsupplierscanbefoundintheAppendix.Thecostsforsomeofthesetoiletsarerelativelyhigh,asthenumbersoldisquitelow.Ifthemarketforthesetypesoftoiletsgrowsandmoresuppliersenterthemarket,thentheunitcostswilldecline.

5.6 How to choose between a UDDT and a UD flush toilet

Forpro-poorapproachesindevelopingcountries,UDDTsaremoresuitablethanUDflushtoilets,asthelatterstillrequireareliable24-hourwatersupply,asewersystemandatreatmentprocessforthefaeces-watermixture(brownwater).

Incountrieswithexistinginfrastructureforwastewatertreat-ment,theUDflushtoiletmaybecomecompetitivewiththeconventionalflushtoiletinthefutureifthebenefitslistedinSection 2.3aredriversfortherequiredswitch.

Figure 6. UD flush toilets. Left: Gustavsberg (in Meppel, the Netherlands); Right: Dubbletten (in Stockholm, Sweden); (sources: E. v. Münch, 2007).

20 TheRoedigerNoMixtoiletisafirstprototypewhichrequiresfurtherdevelopmentofitsdesign.

http://www.susana.org/case-studies?showby=default&vbls=2&vbl_2=9&vbl_0=0

2424 6 Urine piping and storage tanks

AcomprehensivedescriptionofthetechnicaldetailsforurinepipesandtanksisavailableinKvarnströmetal.(2006).Somekeyconsiderationsareprovidedbelow.

6.1 Urine piping6.1.1 Functional principles

TheurinepipingsystemconnectswaterlessurinalsortheurinesectionofaUDtoilettotheurinestoragetank.Asurinegeneratesaconsiderableamountofurineprecipitatesandsludge(see Section 2.4.4 for causes),specialattentionhastobepaidtothedesignandmaintenanceoftheurinepipingsystem.

6.1.2 Materials

Urinepipeworkisnormallymadeofdurableplasticssuchaspolyethylene(PE)orpolyvinylchloride(PVC).

6.1.3 Pipe size and layout

Tomaximisetheflowrateoftheurine(andanysediments),theinsidesofthepipesshouldbesmooth.Flowrestrictions,suchassharp90ºbends,shouldbeavoidedasmuchaspossible.

Theminimumrecommendeddiameterofthepipesis50mm,buttheoptimumrangeisfrom75mmto110mm.

Forlargersystems(severaltoiletsconnectedtooneurinetank),theslopeofthepipeshouldbeatleast1%tominimiseurineprecipitation.Forindividualtoiletsystems,theslopeshouldbeatleast4%,butcanbebuiltwithsmallerdiameterpipes,downtoabout15mm.

Forinspectionandcleaning,thepipesshouldbemadeaccessible(byprovisionofinspectionopenings).

Asaruleofthumb:keepurinepipesas short as possibleandwiththehighestpossibleslope.Horizontalpipesshouldnotexceed200mbecauseoftheproblemsofsludgeaccu-mulationinthecontinuouslywettedsideofthepipe21.

Overtimecrystalsandsludgemayaccumulateintheslowflowinghorizontalpartsofthepipesystem,soperiodicflush-ingmaybenecessary(onceeveryfewyearsinthebestcase;morefrequentintheworstcase)22.

6.1.4 Odour control

Topreventodours,thepipingsystemshouldbeonly spar-inglyventilated,pressureequalisationisenough(see Section 6.3 for more details on ventilation).Alsothepipeopeningneedstobeimmersedintotheliquidinthestoragetank.Thisisparti-cularlyimportantinlongventpipesthatcanactaschimneyswithupwardflowofair23.

Thismeansthattheincomingpipetotheurinestoragetankshouldgodownalmosttothebottom,sothataliquidsealisformedpreventingunduegasmovementthroughthepipingsystem.Butitisnotrecommendtoplaceabucketatthebaseofthispipe,asitmightfillwithsludgeandthusintroduceaflowrestriction.

6.2 Urine storage tanks6.2.1 Functional principles

Theurinewhichiscollectedbymeansofawaterlessurinalorbyaurinediversiontoiletflowstoaurinestoragetank.Thesetankshavealidandareclosedtopreventodourandlossofnitrogenviaammoniagas.Thetanksareeitheremptiedbytheusersthemselves(small-scalesystems)oremptiedbyapumpandtruckarrangement.Theurineisthentransportedtothepointofagriculturalreuseortofurtherstorageortreatment.

Urinestoragetankshaveoneorseveralofthefollowingthreemainpurposes:1. Tobridgethetimeinbetweencollection/emptying

events.2. Tosanitisetheurine:overtime,pathogensinthe

urinearekilledoff(increasedpHduetoureaconver-siontoammonia(see Section 2.7.2).

3. Tobridgeperiodswhereplantsarenotfertilised:Theplants’needforfertiliserisnotconstantallyearround(exceptinthetropics).Fertilisernutrientsaregenerallyonlyneededjustbeforesowingandinthebeginningofthegrowthperiod (see Section 3).

Therearetwotypesofurinetanks:thereceptorurinetankatthetoiletandtheurinestoragetankforstorage,sanitisationandreuse(thesefunctionscanberealisedinthesamevesselorinseparatevessels).

21 Source:ArnoRosemarin(March2009)22 HakanJönsson(March2009):“My fairly extensive experience is that as long as there is at least a slope of 1% and the diameter is 75 mm or more, then the sludge will flow out at the rate of generation and flushing is not necessary. The reason why extensive pipes should be avoided is that fre-quently there has been problems with groundwater leaking into the pipes, di-luting the urine!”23 Source:ArnoRosemarin,March2009,basedonexperiencewithlarge-scaleurinediversionsystemwithindoorUDDTsinErdos,China.

25 25 6.2.2 Locations

Thelocationoftheurinestoragetankscanbe:1. At toilet level:Iftheurineistobeusedinthehouse-

holdgarden,asimpleplasticjerrycancanbeused.2. At household/building level(severaltoiletstogether).3. At community level(severalhousestogether)–

thisispossibleifdistancesbetweenhousesareshort.

Astheurinetanksmustbeemptiedregularly,suitableaccessforpersonsorvehiclesisrequired.

Thetankscanbelocatedeitherinthecellarofthebuilding,nexttothebuildingorbelowground.Urinetanksbelowgroundhavethedisadvantagethatleaksfromtheurinetankaredifficulttodetect(aleakingurinestoragetankcanleadtogroundwaterpollutionwithammoniaandnitrateortothetankbeingfilledwithgroundwater).Undergroundtankshavetheadvantageshoweverthattheyareusuallycheapertobuild,haveabetterinsulationinwinter(relevantforcoldclimates)andtheaccesstothemanholeisusuallyalsoeasier.Inthecaseofundergroundtanksitisimportanttotakethegroundwaterlevelintoaccount–toavoidtanksfloatingintheeventofrisinggroundwater.

Whilstthetanksareclosedanddesignedtominimiseodour,someodourcouldstilloccur.Hence,thetanksshouldbeinawell-ventilatedareaandawayfromkitchens,officesandbedroomstominimiseodourcomplaints.

Asecondaryurinestoragetankatthefarmer’spremisesmaybenecessarytoenablethefarmerstoapplytheurinewhentheyneedit(Figure 8).

6.2.3 Materials

Urinestoragetanksneedtobecompletelywatertighttoavoidlossofurinefertiliser,groundwatercontaminationandgroundwaterentering.Theyaremostcommonlymadeofglassfibrereinforcedplastic,PE,PPorPVC,buttheycanalsobemadeofrubberbladdersorhigh-qualityreinforcedconcrete(thereareafairnumberofconcreteurinetanksinSweden,buttheyneedtobebuilttoahighstandardtoavoidleakages).

Metalcomponentscannotbeusedsinceurineiscorrosive(ex-ceptforstainlesssteel,whichcouldbeusedbutisexpensive).

Plastictankswhicharesoldforrainwaterharvestingarealsosuitableasurinestoragetanks,andcanbeagoodsolutionindevelopingcountries.

6.2.4 Urine tank size

Theurinetanksystemmaybesetuptouseonelargeurinestoragetankorseveralsmallertanks(evendowntousingalargenumberof20 Ljerrycans).Ineithercase,therequiredtotalstoragevolume(Vstorage)canbeestimatedasfollows(addi-tionalsafetyfactorsmaybeapplied):

Vstorage = Nusers · purine · tstorage·ftimefraction

with:Nusers =numberofuserspurine =specificurineproductionperperson

(~1.5 L/cap/dofurineiftheuserisatthepremises24hoursperday24)

tstorage =desiredstoragetime25ftimefraction =fractionoftimethattheusersstaysatthe

premiseswherethetoiletis.

Therequiredstoragetime(tstorage)wasalreadydiscussedinSection 2.7.2).Forexample,typicaldesigncriteriaforasto-ragetankare360Lofurineperpersonperyear(iftheyspend2/3oftheirtimeatthepremises)andastoragetimeofonemonth.

Itisobviousfromthisequationthatifurineisflushedawaywithwater,thenalargerurinestoragetankisrequiredcom-paredtoatoiletwhereurineiscollectedundiluted.

Whendesigningthesizeoftheurinestoragetank,considera-tionalsoneedstobegiventothecapacityoftheemptyingvehicle.Detailsonpossibleemptyingvehiclesinthelow-costcontextareprovidedinSlob(2006).

Iftransportationoccursmanually,thecollectiontanksshouldnotbelargerthan20 Lwhichequals20 kgwhenfull(thiswouldalreadybetooheavyfortheelderly,femalesandchildren).

6.2.5 Number of urine tanks needed

Forpropersanitisation(tokillpathogensoriginatingfromcross-contaminationwithfaeces)itisimportantthattheurineisstoredwithoutfreshurineenteringbeforeitisappliedinagriculture.Hence,atleasttwotanksarerecommended(are-ceptortankandastoragetank).

Forlargeinstallations,theuseofseveralurinestoragetanksisadvisablesothatonecanbetakenoutofserviceifnecessary.

24 PlusflushingwaterifUDflushtoiletsareused,unlesstheyhaveavalveliketheRoedigerNoMixtoiletmodel.25 Thiscouldalsobethedesiredtimebetweenemptyingeventsifsanitisationbystorageisnottheaim(forreceptortankwithadditionalstorageelsewhere).

2626

6.2.6 Urine overflow pipe

Installationofaurineoverflowpipeonthetankisnotrecommended,asthisincreasescostsandintroducesariskofcontaminationoftheurinewhenthereisanoverfloworblock-ageintheordinarywastewatersystem.Also,ifthereisanover-flowarrangement,usersmaybetemptedtojustlettheurineoverflowandnotensureitsuse.Itisbetterthattheurineispumpedtoanacceptabledisposalpointwithaportablewaste-waterpumpifthecollectiontankbecomestoofull.

6.2.7 Examples

Examplesforurinestoragetanksofdifferentsizesareshownbelow.

6.3 Ventilation for pressure equalisation of pipes and tanks

Thepipeandtanksystemshouldonlybepressureequal-ised(notventilated)whichisbestdonebyasmallholeinthetankforequalisationwiththeurinetankpressure.Thisal-lowsthereplacementofheadspaceairbyurineflowingintothetank,andviceversawhenemptyingthetank.

Thereasonswhythepipesystemshouldnotbeventilatedare:ÿ Toeliminateammoniaemissionsandodour.ÿ Toreduceriskofsuckingtheliquidoutofanyliquid

urinesealsintheUDtoilets.

Aone-wayvalveorairadmittancevalveplacedatthetopoftheventpipecanalsobeagoodoption.Advantagesofsuchavalveare26:1. thatammoniaisnotemitted,2. internalpressureisequalisedensuringproperdrainage

downwardstothetank(emptiedurinepipesmeannostandingurineandlessprecipitation),

3. theinstallationcanbedoneinsidethebuildingjustabovethetopfloorinthebuildingsothatthetopoftheventpipedoesnotneedtopenetratetheroof likeold-fashionedventilationpipes,

4. savesonconstructioncosts,5. eliminatesproblems causedbycondensationicein

coldclimatesandUVweatheringofplasticpipes.

Theseone-wayairvalvesarepopularinSwedenforgreywaterandurine systems,andmanynewhousesnolongerhavepro-trudingventpipes.

Theurinetankshouldnotbeopenedmoreoftenthanneces-saryinordertoprevento