I

250 98D1

DISINFECTION SYSTEMSOFAPPROPRIATETECHNOLOGYIN COCHABAMBA-BOLl VIA

Alvaro Mercado,TecnicoInvestigador,Programade Aguasy SaneamientoAmbiental’

Bolivia is a countrylocatedin theheartof SouthAmerica,its economicalconditionsdoesnotallow it to supply good quality water for consumptionto the most of the population,whichlive in the country field, far from the main cities or in the penpheriesof them. The mainproblem of thesegroup of peopleis that most of the water available is bacteriologicallycontaminated,coming from rivers,channels,irrigation systemsor wells which areproneto bein contactwith animalsorresidualscomingfrom otherorganisms.No morethan40 percentofthepopulationis suppliedwith treatedwater,while morethan 50percenthaveaccessto waterofnotcontrolledquality.According to a study on mortality madein 1981, 34% of mortality is relatedto intestinal orparasiticdiseases,whicharecommonlycausedby consumptionofbadqualitywater.Sincemostof theaffectedpeoplehavelow income,aswell as low educationallevel in waterrelatedhealthmatters;thesystemswhich intend to benefitthemshould be effective,versatile,requiringof low maintenanceandoperationalskills.Aiming to deal with situations like the above mentioned, the university of Cochabamba(UMSS)by meansofProgramade Aguas,hasbeenworking in the improvingofthequality ofthe waterby meansof appropriatedtechnologytechniques.Some of thesetechniquesareahydraulic chloridedosing system(alreadypresentedin the previoussimposium),and theuseofslowsandfiltration asdisinfectionmethods.Programade Aguas,in collaborationwith EAWAG — SANDEC, also testedand verified, inlaboratoryandin field, thedisinfectionby solarradiation.Summariesofthementionedtechnologiesarepresentedin thefollowing paragraphs.

1 Programa de Aguas y Saneamiento Ambiental. Universidad Mayor de San Simon. Cochabamba

Casilla de Correo 5783 Cochabamba-BoliviaTeIf 00591-42-50660. Fax (591-042)31765 E-mail: aguas~fcyt.umss.edu.bo

LIBRARY lRCP0 Box 93190, 2509 AD THE HAGUE

Tel.. +31 703068980Fax. +31 70 35 89964

BARCODE: 3LO: 2~o~~

SOLAR WATER DISINFECTION FOR HUMAN CONSUMPTION w

Antecedent

Water disinfectionfor humanconsumptionis a requirementin regionswhere the water isconsideredasnot safe,sincecontaminationaffectsto mostofsurfacesources.This situationisworst in arid andsemiaridregionswheredueto theshort rainy seasons,peopleis obligatedtodrink waterthat hasbeenstoredfor longperiods,or which is alsousedby animals.The sustainabilityof a method is important, since even though a method is effective, itssustainabilitydependson theoperationandmaintenanceof theusers.In therural area,a sustainabledisinfectionmethodmustbe availablefor a commonfamily,whichmeansthatit mustbe easyto understand,to operateandwith aminimumcost.Temperatureis oneof theformsof eliminateorreducingthequantityofmicroorganismsin thewater. EAWAG — SAINDEC studiedthe sinergic effect of the pathogenmicroorganismsinactivationby meansofthesolarradiationandheating,proposingSODIS asan alternativeofwaterdisinfectionfor low incomeanddispersedpopulations.Programade Aguasperformeda field surveyto verify the acceptabilityof the peopleto theproposedsystem.

Zone of theproject

It was located approximately to 90 km to the south of Cochabambacity, in a region calledSacabamba.

Technical aspects

From experiencesin manycountriesit hasbeenshowedthat with two effectsof the solarenergy: the radiation and the heating, it is possiblethe disinfection of water for humanconsumption.Theprocessconsistson filling transparentcontainerswith waterandexposesthemto thesolarlight for somehours. Solarradiationinactivatesand destroyspathogenorganismspresentinwater,withoutchangingthetasteandodor.The solar disinfection occurs evenwith solarradiation intensitiesof a partially cloudy day(350 to 400 W/m2in Cochabamba).Lower intensitiesmayrequirea longerexpositiontime.

Materials

The testedcontainerswerethe availablein the region,plastic andglassbottlesof carbonatedbeverages.Among the plastic bottles, two types were tested: the non-returnableand thereturnableones.Also especialplasticbagsprovidedby EAWAG-SANDECweretested.Materialsusedas supportof the bottles were also tested:concrete,wood, and metal plates(usedfor coveringtheroofs).

Laboratory tests

For different expositionperiods,water,air temperatures,aswell asradiationwererecorded;alsowatersampleswere takento analyzetheexistenceoffecalandtotalcoliforms.It wasalsodeterminedthatthebestsupportsfor thebottleswerethemetallicones.From a comparisonbetweencontainers:non returnableplasticbottle, returnableplasticbottle,glassbottles, and SODIS bags,the oneswhich highertemperaturereachedwere the SODISbags,followedby returnableplasticbags.(seefig. 1 and2)Thefecal coliform remotionwashigherin theplasticbottlesthanin theglassbottles.

People’sparticipation

The introductionofthe SODIS methodwasmadeduring theperiodic communitymeetings.The relationshipbetweenthe water quality and the diseasesbesidesthe importanceof thedisinfectionwereexplained.Mostoftheexplanationsweremadein thequechualanguage.Thepeoplewho initially workedwith thedisinfectionsystemwerechosenfrom theresultsofasurvey,accordingmainly to theirinterestandeducationlevel.Starting from 5 familiesusing the disinfectionsystem,more families askedfor workingwiththedisinfectionsystem.Themain meanof diffusion ofthe methodwasthe commentariesof the userswith theotherpeopleoftheregion.Anotherform ofdiffusion wasthedesignanddistributionof graphicandeasyto understandeducationalcharts,amongtheinterestedpeople.

Asessmentof theproject

It wasmainly doneby meansofperiodicvisits that includedcollectionof samplesfor analysisof pH, conductivity, turbidity, temperature,total andfecal coliform, previouslyand after thetreatment.Most ofthewaterusedby thepeoplehadthefollowing characteristics:Turbidity : 25 NTUConductivity : 15 — 80 ~tmhos/cmSalinity : 0.01 — 0.03 mg/L CaCO3

Conclusions

• Theefficiencyof thesolardisinfectionwasprovedin thefield.• Total and fecal coliform removal hasbeenprovedto be in the order of 90% evenin

partially cloudeddays.• In a partially cloudedday the removal from 1910 to 310 coloniesforming units/lOU ml

wasachievedwith amaximumtemperatureof 34°Cin theglassbottles.• The parameterconsideredmore important in the tests is the solar radiation for

Cochabamba(2600masi) andSacabamba(3200masi).• The containersusedin the field were thereturnableplastic bottles,sincetheseare more

resistantthantheothertestedplasticcontainersandarelessfragile thantheglassbottles.• Theuseof ametallicsupportunderthebottles improvesthe efficiencyof themethodsince

it increasesthetemperaturethat thewaterin thebottlecanachieve.

• Thebestperiodof time to obtainmaximumtemperatureandsolarradiationis between10and15 hours.

Figurel.- Variation of temperaturefor differenttypesofsupportfor SODISbags.Variationofsolarradiationwith time. Themeasurementsstartedatthesametime

C.)

C

E0I-

—*--TEMP MIB [q —e--TEMP SOL [q —i—BOLSA SODIS c~arrunan~

— BOLSA 500(5c~an~na -.o—- BOLSA SODIS tiara —s—BOLSA SODIS madeca

—h-- BOLSA SODIS cortr~o —~--- RADIACION [W/m2]

c~lE

420 ~C

0410

1030 1100 1130 1200 1230 13(X) 1330 1400

I-bra

Figure 2.- Variation of removal of coliform, with the exposition time and the type ofcontainer.Variationoftemperatureofthewaterin thecontainer

EVALUATION OF THE CHARACTERISTICS OF SAND FOR SLOW FILTRATION(2)

Antecedent

Thediametersofsandusedfor slow filtration accordingto literaturego from 0.15 to 0.30 mm,which is usually difficult to fulfill. A slow sand filter to be consideredof appropriatedtechnologyshouldusematerialsavailablein theareaofuse.

Objective

Themain objectiveof thiswork is to determinewhethertheuseof highersanddiametersthantheonessuggestedby literature,modifiestheefficiencyof removalof microorganismspresentin water.

Methodo1oi~y

1. Evaluationin field of pilot slow sandfilter whosesanddiameterrangesbetween0.15 and 1mm. This pilot filter receiveswater from othergravelfilters. It is locatednearTaratacity,approximatelyto 40 km ofCochabambacity, andto anelevationof2800masi.

2. Evaluationin laboratoryof two sandfilters:3. Sanddiametersrangingfrom 0.15 mmto 0.60 mm4. Sanddiametersrangingfrom 0.60mmto 1.0 mm

Experiments

Imtially for both the evaluationfilters (for thepilot plant andthe laboratoryfilters) the sandwasselectedand cleaned.Thecleaningwasperformedwith chloridesolutions,which left thesandsdisinfectedandfree ofestrangeadheredparticles.Thepilot sandfilter wasconstructedafter3 gravelfilters, it had a internaldiameterof0.80 mandahighof2 meters,with afiltration thicknessof 1 m.(Seefig. 1)Thenthetwo laboratoryfilterswereconstructedin 6” pvc pipes.(Seefig. 2)

Results

Pilot sandfilter (diameterbetween0. 15 and1.00mm)Date Turbidity

EntranceNTU

TurbidityOutletNTU

IronEntranceMg/L

IronOutletmg/L

FecalC/IOOmlEntrance

Fecalc/lOOrnIOutlet

TotalC/lOOm)Entrance

TotalC/lOOmlOutlet

28/10/94 24 6929/10/94 23 6630/10/94 62 6931/10/94 12 5701/11/94 37 108 07203/11/94 27 75 02604/11/94 135 100 020 038 28 0 70 007/11/94 43 83 015 053 6 1 14 111/11/94 17 4.8 007 016 4 0 16 213/11/94 107 6414/11/94 105 75

LaboratorysandfiltersParameter Rawwater Prefilter Filter 1 Filter 2Sanddiameter(mrn) 015—06 06—10Sand bed thickness (cm) 84 80Filter diameters (cm~Infil~ationarea(cm)

15 21767

15 21767

Flow çL/sec)Filtration rate (m /m

2 h)0 000700 143

0 000750 153

Turbidity (NTU) 7 7 4 4 2 1 3 0Color (APHA) 140 80 40 50Fecal coliforms (UFC/iOO ml) TNTC 10 0 0

From the last table it is possibleto see that 100% of the bacteriologicalcontaminationisremoved.Also theturbidity andthecolorarereduced.

Conclusions

• Theresultsshowthat it is possibleto usehighersanddiametersthantherecommendedbyliteraturefor slowfiltration.

• The efficiencyof thefilter increaseswith thepercentageof fme particles,but its life alsodecreases.

• Theremovalof fecal coliformsis 99.6%. Anotherimportantdatais that theheterotrophicbacteriaareremovedin 96%.

• Slow sand filtration is an alternative for water treatment for human consumption,especiallyin rural areas.

Figure1.- Schemeof thepilot plantwheretheslow sandfilter wasinstalledPLANTA PILOTO DE LAKA LAKA

FILTRO ASCENDENTE

GRAVA lIE 10 1mm]

FILTRO ASCENDENTE“F!”

GRAVA DE 15 1mm]

0 Eatradade agua

o Liave reguiadorado read.!

0 Regulador de carga consiante

O Solución de Saifato de A!umtnto

© Dos,ficador del Suifato de A!umin~o

FILTRO ASCENDENTE FILTRO LENTO DE ARENA“FLA”

GRAVA DE 5 ImmI ARENA ENTRE0.2-1 ImmI

0 Dosificador de Ia Cal

O Solucidn do Cal

0 Nivel de aguaaobrenadante

0 Regulador de caudal de salida

0 Salida de agua

Figure2.- Schemeof the laboratorySandfilters.

UNIDADES EXPERIMENTALES DE FILTRACION

mafia niilimétrica

~~~Drenaje de grava,diámetro>0 6 [cm]

Tube dePVC, diámetro6[pig]

Mangueraspiásticas,diámetro0 55[cm]

Tube dePVC, diametro 6[pig]

Mangueraspiásticas,diametro 0 55 [cm]

de agua a tratarC

Lechode arenaentre06 - 1 0 [mm]

15 -06 [mm]

to

*

milimetrica

Punto de muestree

de grava, thámetro> 0 6 [cm]U,

*

CHLORIDE DOSIFIERS FOR DISINFECTION OF HUMAN CONSUMPTIONWATER WITH APPROPRIATED TECHNOLOGY (3)

Antecedent

Thedisinfectionin water supplysystemsof rural areasis an importantrequirementand at thesametime oneofthe mostdifficult to achieve,mainly due to the quality of the constructionsofthesupply systemsandthecapacityoftheuserpopulationto maintainandoperateit.Theproblemworsensbecausemost of the institutions in chargeof the constructionof watersupplysystemsprovideonly waterin pipes,butmostofthetimes notdisinfected.Thereare still someproblemswith thetraditionaldisinfectionsystems:• Dosingproportionalto thevolumeofconsumedwater.• Overflowofthestoragetanks,loosingin thisway thedisinfectantsolution.• Permanenttechnicalcontrolofthedosingsystem.• High costsofimporteddisinfectionequipment,which in manycasescannot bemaintained

andoperatedduelimitations oftheusers.By reasonslike the abovementioned,since1991 the Programade Aguas de la UniversidadMayor de SanSimon, startedthestudyof a clorinationwith appropriatedtechnologyfor ruralareas,totally hydraulic,andfor usein gravity andpumpingsystems.This systemhasbeenappliedto small watersupplysystemsespeciallyin theChapareZone,ofCochabamba,but alsoin otherpartsofBolivia.

Technical characteristics

For thechlorine dosing is useda venturi pipe,which is usuallyusedto measurethe flow ratein pipes. It is composedby a convergentconic section,a throat, and anotherdivergentconicsection,aschemeofthedeviceis showedin thediagramshowedin fig. 1.Therearetwo possibilitiesof applicationoftheventuripipe:• Directly applyingtheventuripipe in thebody of themainpipe. This form is usedwhenthe

diameterofthepipe is smallerthan2”.• With a “by pass”.In this methodtheventuri is fitted to apipewhich is parallelto themain

pipe, but it is connectedto it upstreamand downstreamthe venturi, being of smallerdiameter.This way of fitting is usedwhenthe pipe by which the water flows has adiameterbiggerthan2”.

Many laboratorytestsweremadeto seethevariationsofthedosing volumeaccordingwith theflow in themainpipeandtheheadofthetankofdisinfectingsolution.From laboratorytests,thefirst systemsfor realsituationin watersupplysystemswerebuilt.Theneedofverifying andcontrollingtheconcentrationofdisinfectionsolutionin thenodesofthe water supply systems,impulsed to the design and constructionof device to know theconcentrationofchloridebasedin acolorimetrictechnique(colorimeter).A simplified descriptionofthe equipmentis showedin figure 2.• Containerfor thechloridesolution.(A)• Y2” valve,usedto makethemaintenanceandrechargeof chloridesolution(B).• Smallcontainerusedto regulatetheheadofthechloride solution©.• Small diametervalve usedto regulatethe entranceof chloride solution to the mainpipe

(D)

I

ig andregulatingthesolutionthatgoesin to themainpipe(E).oncentrationofchloride in thewater(F).

ice canbe foundin any localmarket.

v rate,thediameterof thepipe,thematerialof the~ragecostis approximately300 americandollars2”. Operationand maintenancecost depend

a necessaryactivity. A continuous aining program forid maintenanceofthesystemshouldb arriedout.emsin which theventuripipehasbe installed,hasgiven astics for different diameters, fib and types of systems

disinfectionsystem,its us s idealfor populationswith water

o electricityandtechnica ersonal,for pumpingaswell as

esthemixing andthe rocessof disinfection.

4 Venturi pipe.Usedfor mix4 Controlpoint, to verify the4 Small accessoriesandhoseAll thematerialsusedin the de

costs

Thecostwill dependon thethquality of thewater,etc. An a’of 1.5 us and a diameterofcharacteristics.

Monitoring and continuous a sessment

Monitoring and assessmentioperatorsanduserson theuseAsessmentsto the differentsy~result, standardizedcharacter(pumpingandgravity).

Conclusions

a systemthe system

Dueto the characteristicsofthsupplysystemswherethereisgravity systems.Theuseof aventuripipeenhar

Figure 1.-Diagramofventuri

I

Figure 2.- Descnptionoftheequipment

GENERAL CONCLUSIONS

Simple technologiesare acceptedmore easilyby peoplethanmodernones,sincethe simpletechnologydevicesandequipmentscanbe repairedor replacedby users,orby personalwhichcanbepaidby theusers.

The appropriatetechnologiesarean alternativefor the developingcountries,mainly due thelow incomeof themostof thepopulation. thereforetheintendedassistanceto thesecountriesshouldbefocusedin the developmentof appropriatetechnologies.

References(1), (2) and(3) aresummariesofpresentedworksinTaller regionalsobretecnologiasadecuadasen saneamientobasicoparael ambito rural. Abrilde 1998-Lima, Peru.Presentedby OlverCoronado

(1) Participants:Olver Coronado,Alvaro Mercado, Rarniro FuentesG., Soma Peredo,RosmeryAyala, ClaudiaGonzales,ErnestoMendoza,Dulio Orellana.

(2) Participants:OlverCoronado,AmadeoMerida,FernandoZegarra,JorgeMejia.(3) Presentedwork in theI Simposio

Participants:OlverCoronado,AmadeoMerida

B

Nigel Browne

From: Jan Teun VisscherSent: Tuesday, October 27, 1998 9:55 AMTo: NIgel BrowneSubject: FW: For Jan Teun Visscher

Another paper that was prepared for the Barcelona conference containing interesting field data on solar disinfection

Jan Teun—Original Message-—From: Lia WahabSent: dinsdag, oktober 20, 1998 1003To: Jan Teun VisscherSubject: FW For Jan Teun Visscher

—Original Message-——From: Aivaro Mercado [SMTPAlvaro mercadoguzmanc~studentkuieuven ac be]Sent: Monday, October 19, 1998 6 21 PMTo: general~irc nISubject: For Jan Teun Visscher

Hola Jan Teun, soy Alvaro Mercado Yo me encontraba en el simposio sobretecnologias adecuadas Ilevado a cabo en Barcelona Te envio como te comenteantes, el articulo que presentamos al simposioTe To envio ahora porque me olvide entregartelo y par que no Ia publicaronen el CD del simposio, ni en el resumen

Saludos

Alvaro

Alvaro Mercado GResidence HollebergSchapenstraat 37 room 191B- 3000 Leuven--BELGIUM--

barcelonadoc

alvaro mercadoguzman~studentkuleuven ac.be

1