analytical report of the international symposium ... · analytical report of the international...

Analytical Report of the International Symposium

Alternative Technologiesfor Water and Sanitation Supplyin Small TownsThis document is an abstract of the Proceedings of the International Symposium on AlternativeTechnologies for Water and Sanitation Supply in Small Towns held in Peru, in April 2004. It providestechnical information on costs and requirements for the operation and maintenance of alternativetechnologies for small towns, as well as includes references to documents or web sites, where furtherinformation on technological options can be found.

April 2005

Field Note

33071

Pub

lic D

iscl

osur

e A

utho

rized

Pub

lic D

iscl

osur

e A

utho

rized

Pub

lic D

iscl

osur

e A

utho

rized

Pub

lic D

iscl

osur

e A

utho

rized

Pub

lic D

iscl

osur

e A

utho

rized

Pub

lic D

iscl

osur

e A

utho

rized

Pub

lic D

iscl

osur

e A

utho

rized

Pub

lic D

iscl

osur

e A

utho

rized

In order to better respond to the specific needs of small towns, an InternationalSymposium on Alternative Technologies for Water and Sanitation Supply inSmall Towns was held in Lima, Peru, in April 2004.

2

Executive Summary

Water and sanitation service provisionapproaches have traditionally beendifferentiated according to rural andurban areas. The largest urban centersfollow the conventional service supplythrough public companies orconcessionaires, while rural areas applycommunity-based management models.

These models do not necessarily suitspecific needs of small towns, which maybe either too big for the rural communityapproach or too small to stir up theinterest of public service companiesoperating in urban areas.

In Latin America, the proportion ofinhabitants that live in small towns incomparison to the country’s totalpopulation is variable: 10% in Boliviaand Chile, 15% in Peru, and 32% inColombia. In Peru, small towns aredefined in terms of population, rangingbetween 2,001 and 30,000 inhabitants.

Overall, water and sanitation coveragerates are lower in small towns than inmedium or large urban centers. Thetechnology to be used for the provisionof water and sanitation services in smalltowns is part of the challenges. If waterand sanitation technology similar to whatis used in large urban areas is chosen, itwill lead to high investments, which can-not be afforded by small towns in LatinAmerica. It is important to choosetechnologies that can be operated andmaintained by local service providers.

Tabalosos small town, San Martin, Peru

Alternative Technologiesfor Water and Sanitation Supplyin Small Towns

3

In order to better respond to the specific

needs of small towns, an InternationalSymposium on Alternative Technologiesfor Water and Sanitation Supply in Small

Towns was held in Lima, Peru, in April20041.

The symposium report includes technicalinformation, costs and requirements forthe operation and maintenance ofalternative technologies for small towns.It is addressed to decision makers,municipal and local technicians andservice providers. Furthermore, thisreport provides references to documentsor web sites available on the Internet,which present detailed information abouteach technological option.

Concerning water distribution, thisdocument describes condominialdrinking water technology and the

construction of structures withferrocement for water storage.

As to water treatment, it outlines a seriesof processes that form part of the socalled multiple-stage filtration (FiME, in

Spanish), which is a relevant alternativeto conventional processes of quickfiltration that use chemical products and

mechanized equipment for flocculationand filtration.

1 This event was organized by the Peruvian Vice Ministry of Construction and Sanitation, with the support of the Canadian International Development Agency(CIDA), the Swiss Agency for Development and Cooperation (SDC), the Pan-American Center for Sanitary Engineering and Environmental Sciences (CEPIS-PAHO),and the Water and Sanitation Program (WSP) administered by The World Bank. It relied on the participation of professionals and international institutions such asACUAVALLE (Colombia), Aguas del Illimani (Bolivia), The World Bank, CARE Peru, CENTA (Spain), CIEMA-UNI (Nicaragua), CINARA (Colombia), Condominium(Brazil), COPASA (Brazil), SANBASUR (Peru), SARAR Transformación SC (Mexico) and SEDAPAL (Peru).

Concerning sanitation services, thedocument describes the followingtechnological options:

Centralized or sewerage

! Small-bore sewerage! Condominial sewerage

Decentralized

! Compost or ecological latrine! Pour-flush latrine! Septic tank

For waste water treatment, thefollowing criteria were provided forthe selection of adequatetechnologies:

! Little or no energyconsumption.

! Streamlining operational andmaintenance procedures.

! Stable and efficientoperation regardless of flowand organic load variations -a common occurrence withwaste water in small towns.

! Management of the sludgegenerated during theprocess.

Among technologies meeting thesecriteria are stabilization ponds, bio-filters, and Upward-Flow AnaerobicReactors (RAFA, in Spanish).

Conclusions

! There are currently interestinglow-cost alternative technologiesoffering a level of serviceequivalent to that of conventionaltechnologies that may beimplemented in small towns.

! The absence of knowledgesharing and disseminationhampers its wider implementationand refinement.

! In order to provide small townswith sustainable water andsanitation services, there is morethan one alternative or technologythat could be useful.

! It is important to provide a rangeof options that shows municipaland local decision makers theadvantages and disadvantages ofeach alternative.

Lessons learned

Technology is coupled with operationaland maintenance issues. There are noproper operation and maintenancemodes that are low-cost by themselves.However, the application of technologiesthat require lower investment andoperational costs makes it more likelythat financial resources will be efficientlyused. This can help widen the coverageof water and sanitation services in smalltowns and to carry out rehabilitation andextension of the system.

Notwithstanding the above, thetechnological aspect is just one of thevariables that must be taken intoconsideration in the provision ofsustainable water and sanitationservices. It is also essential to meet thereal demand of the population and to

Tabalosos small town, San Martin, Peru

Experience in Latin America shows that, regardless of how complex the systemmay be, it is necessary to implement a regular follow-up and technicalassistance process.

4

develop decentralized management

models.

Often, technicians who work in small

towns are not familiarized with

alternative water and sanitation

technologies, or are afraid that they will

not be able to learn how to handle them.

Consequently, they prefer to continue

designing and applying conventional

technologies that are more familiar and

safer for them.

On the other side, in some cases, the

predominance of technical standards

based on conventional technologies for

urban areas can limit the development

and application of alternative

technologies in small towns, since they

are not adapted to the local contexts.

The provision of technical assistance forthe adequate management of water andsanitation services is of greatimportance, particularly when there arewater or waste water purificationprocesses underway. Experience in LatinAmerica shows that, regardless of howcomplex the system may be, it isnecessary to implement a regular follow-up and technical assistance process.

The creation of centers for technologydevelopment and promotion andtechnical assistance provision has apositive impact on the training of humanresources, the adaptation of technologyto the local area, and the effective use ofthose technologies. This strategy hasalready proved its effectiveness in PlantaExperimental de Carrión de losCéspedes (PECC, Spanish abbreviation)in Andalucía, Spain, the CINARA Centerin Colombia and CEPIS in Peru.

individual house with aconnection to the public network,a connection point is created foreach group of houses (block), as ifit were a condominium orapartment building, hence thename condominial system. Thisapproach substantially reducesthe cost of network expansion.

2. The community participates in theconstruction and maintenance ofnetworks, resulting in an evengreater cost reduction.Additionally, interaction with thecommunity facilitates the adoptionof actions in sanitary education.

The condominial network technology fordrinking water supply has beensuccessfully implemented in the city ofParauapebas, Brazil, since 1996, and inthe city of La Paz, Bolivia, since 1999.

Technology Description

The condominial model consists of twobasic components:

1. The model consists of extendingthe water and sewerage linesalong sidewalks and inside lots,as opposed to in the streets.Rather than providing each

Water Supply through Condominial Networks

Furthermore, this particular networkdesign facilitates subdivision of thesystem into sectors comprising a specificnumber of blocks. Network maintenanceis possible by installing a collectingchamber. In this way, only a small numberof users will be affected (see picture).

Investment and Operational Costs

The cost of building condominialbranches is significantly lower than that ofconventional systems. The table in thefollowing page compares connectioncosts in a project implemented inParauapebas, Brazil.


5

Water Distribution Network in a Conventional and Condominial System

CONVENTIONAL SYSTEM CONDOMINIAL SYSTEM

Operation and MaintenanceExperiences

The simplicity of the condominial modelfacilitates the service control andoversight of the household connectionsand branches that feed each block byinstalling water meters at eachcondominium connecting point. Similarly,service operation and maintenancebecomes simpler due to the division intosectors, affecting a limited number ofusers when carrying out maintenanceactivities.

References:- CONDOMINIUM Emprendimentos Ambientais Ltda. Joao da Costa Miranda Neto: [email protected] Foster, Vivien, 2001, Sistemas condominiales de agua y alcantarillado. Costos de implementación del modelo, Programa

de Agua y Saneamiento (www.wsp.org)

The simplicity of the condominial model facilitates the service control andoversight of the household connections and branches that feed each block byinstalling water meters at each condominium connecting point.

Description of Condominial Branches

Distribution network

Block Hydrometer and inspection box

Con

dom

inia

l br

anchC

ross

arm

Cro

ssa

rmCon

dom

inia

l br

anch

Quantity

Conventional

5.5—2.970.36

0.631

Condominial

55——

——

Cost (R$)

Conventional

8.8—

17.826.70

6.114

43.43

Condominial

89——

——

17.00

Item

20 mm PVC piping25 mm PVC pipingDiggingRemoved /replacedconcreteRemoved /replaced asphaltConnection pieces

Unit

MMm3m2

m2Unit

Unit Cost(R$)

31.61.8

18.60

9.74

Cost Comparison Chart in Parauapebas, Brazil (Reales per connection) 2

TOTAL COST

6

2 US$ 1= 3.13 Reales

This technology was developed in 1960

in the current Republic of Zambia. Later,

these systems were installed in Australia

(1962), the United States (1975),

Colombia (1982), Brazil (1987) and

South Africa (1989). This technology is

very common in Australia and the United

States where over 300 systems have

been installed (www.sanicom.net).

Between 1981 and 1982, this technology

was replicated in Colombia. Based on

Settled or Small-Diameter Sewerage Systems

Settled Sewerage

Networkinflection

House connection to sewer

Interceptor tank

Domiciliaryconnection

Settled solids

Outflow

Foam, fat and oil


7

this experience, the Ministry of EconomicDevelopment of Colombia published the“Technical Guides on Settled SewerageSystems”. The results are promising:Projects have been implemented inGranada (370 houses), San Zenón(255 houses), Tiquisio (213 houses)and Puerto Rico (326 houses).


The settled sewerage system is a type oftechnology which conveys domestic

waste water which has been previouslysettled in a septic tank, also known as a“solid interceptor tank” (see picture).

The first settled sewerage systems weredesigned on the basis of 100 mm.-diameter pipes laid at a minimumgradient of 1 in 200 to achieve a speedof 0.3 m/s under peak flows.

In the late 70s, the “inflective gradient”approach was developed in the UnitedStates. According to this approach, the

References:- “Guías Técnicas de Alcantarillados Decantados”. Ministerio de Desarrollo Económico de Colombia- Sanitation Connection (www.sanicon.net)- SANBASUR. Herberth Pacheco: [email protected]

Inspection Register

Multiple-stage filtration technology consists in combining thick gravel filtrationwith slow sand filters. This technology has produced very good results inColombia where there are about 50 operating plants, ten of which have beenworking since the mid-1980s.

8

sewer must follow the superficial ground

contour and the flow in the sewer is

allowed to vary between open channel

flow and pressure (full bore). In these

cases, measures must be taken to make

sure that in sections where there is

pressure flow, there is no refluence from

the sewer to the interceptor tank.

Furthermore, there must be a positive

height difference between the two ends

(upstream/downstream) of the sewer.

This approach is more economical than

the first design, which required a specific

speed at peak flows. Additionally, self-

cleansing speeds are not necessary with

settled sewerage since solids are

retained in the interceptor tanks.

When septic tanks are located at the rear

part of properties, the sewers can be laid

there rather than in the road, thus

resulting in considerable cost savings,

as in the case of condominial networks

laid in the backyard of houses. Manholes

are not required at every change of

direction, as cleanouts will suffice. Lift

stations are only required in those areas

with a very low gradient that need simple

structures with a water pump rather than

a more expensive sludge pump since

there are no solids to be pumped.

Furthermore, when 40% of the

biochemical demand of oxygen (BDO) inseptic tanks is removed, the demandover treatment processes decreases

proportionally.

Investment and Operation Costs

Settled sewerage construction costs aretypically 20% to 50% less than those of

conventional sewerage in rural UnitedStates. In those areas with existing septictanks, cost reduction will be greater (from

40% to 70%). Operation costs include, inaddition to the usual maintenance cost ofsewers, regular cleaning of septic tanks.


The operator must make sure that onlyconnections from septic tanks are madeto sewers. Furthermore, it has to beresponsible for desludging septic tanks –a task that cannot be left to usersbecause they simply would not do it, andeventually settled solids would passthrough sewers causing blockages andhampering its adequate disposal andtreatment. It is important to consider –asin the case of condominial systems-putting pressure on users to enlargetheir houses and take up the spaceintended for sewers.

Multiple-Stage Filtration (MSF)

Multiple-stage filtration technologyconsists of combining thick gravelfiltration with slow sand filters. Thistechnology has produced very goodresults in Colombia where there areabout 50 operating plants, ten of whichhave been working since the mid-1980s.

On the other side, experience shows thatprior to the adoption of this technology, a

Water Treatment without Chemical Coagulation

Thick Dynamic FilterSand Washing ChamberOperating house

ThickUpwardFilter

Slowfilter

Chlorine contact tankStorage tankDistribution network


9

detailed analysis of technical and socialconsiderations as well as localconstruction and plant operation skillsmust be made. The availability of short-and medium-term technical assistance isa critical factor.


The MFS can comprise two or threefiltration processes, depending on thedegree of contamination of water

sources. The picture shows analternative consisting of three processes:Thick Dynamic Filters (FGDi, Spanishabbreviation), Thick Upward LayerFilters (FGAC, Spanish abbreviation)and Slow Sand Filters (FLA, SpanishAbbreviation).

The first two processes take place duringthe pre-treatment stage which helpsreduce solute solid concentration. Aswater flows, the tiniest particles areeliminated on their way to the slow sandfilter -known as a simple, reliable andefficient technology because it canproduce low-turbidity water, free ofsuspended impurities and virtually freeof enterobacteria, enteroviruses andprotozoan cysts.

Thick Dynamic Filters (FGDi)

Thick dynamic filters are tankscontaining a thin layer of fine gravel (6 to13 mm) on the surface, over a thickerbed of gravel (13 to 25 mm), and adraining system at the bottom.

Water coming into the filter flows overthe superficial layer of gravelhorizontally. Part of the water filtersthrough the bed and is conveyed to thenext treatment stage, while the excesswater returns to the original waterstream. Under normal operationalconditions, the layer of fine gravelretains between 70% to 80% of solute

Processes involved in MSF

Multiple-Stage Filtration (MSF) is cost effective in terms of initial investment,particularly in small systems where the cost of land is low and labor force andmaterials are available at local level.

La Quemazón, Piura, Peru

10

material, eventually blocking thesuperficial bed. If there were highconcentrations of solute solids, thefiltrating bed may get blocked faster, thusreducing the water flow and preventingother treatment processes.

These units must be cleaned one to twotimes a week, and for this purpose, thesuperficial bed of gravel must bescraped to remove the depositedmaterial. This process includes basedraining.

Thick Upward Layer Filter

A thick upward filter has a maincompartment containing the filtrating bedof gravel. The size of gravel grainsdecreases as the flow moves upward. Apiping system, located at the base of thestructure, allows a uniform distribution ofwater flow inside the filter.

As the filter is used, empty spacesbetween gravel particles start to fill upwith water retained particles. For thisreason, it is necessary to carry outweekly cleanings for which quickopening valves located in the base of thestructure are used. These valves openand close to remove material depositedin the filter bed.

Slow Sand Filter (FLA)

It comprises a tank with a bed of gradedsand on a layer of gravel which becomesthe support for the sand. The sand isconfined on a drilled piping system that

References:- Instituto CINARA

(www.cinara.org.co).Alberto Galvis,[email protected]

- International Water and SanitationCenter (www.irc.nl)


11

collects filtered water. The flow runsdownward, with a very low filtrationspeed that can be controlled, preferably,at the tank opening.

As the filter is used, a biological layerdevelops on the surface as a result of theaccumulation of organic and inorganicmaterial. This layer generates thegreatest discharge during the operationof the filter; therefore, cleaning consistsof removing or scraping one to two cm ofthe filter media surface after severalweeks or months, depending on factorslike water turbidity and filtration speed.After several scrapings, the filter must berefilled with sand, meaning that the sandpreviously removed from the cleanedfilter must be replaced. This must bedone every three or more years.


Multiple-Stage Filtration (MSF) is costeffective in terms of initial investment,particularly in small systems where thecost of land is low and labor force andmaterials are available at local level.However, the greatest advantage lies inits administration, operation andmaintenance costs, which aresignificantly lower compared to costsincurred by the use and management ofchemical products -like coagulants-needed in other technologies.

The CINARA institute developed a seriesof equations and models that helpdetermine the investment cost of theseunits.


Tasks to be fulfilled by operators of anMSF plant include:

• Intake cleaning (daily, dependingon the time of year)

• Sand trap cleaning (weekly)• Cleaning and scraping of

dynamic filters (daily or every twodays)

• Cleaning and scraping of thickfilters (every week)

• Washing and scraping of sandfrom slow filters (every twomonths)

• Preparation and dosage ofchlorine solution

• Measurement and registration offlow when entering and leavingthe plant (daily)

Experiences with this technologyindicate the need of an optimalknowledge of the characteristics of thewater to be treated, including itsseasonal variations, and the elaborationof pilot studies prior to theimplementation. It is also important tocount on technical assistance during thedesign, construction and operation of theplant for the short and medium term.

Bio-filter technology was first introducedin Latin America in Nicaragua in 1996with the implementation of a pilot plant.A five-year monitoring process helpedestablish the design and constructioncriteria, as well as the necessarymeasures to ensure appropriateoperation and maintenance.

Based on this experience, similar plantswere built in other cities of Nicaragua, ElSalvador and Honduras.


The bio-filter is a gravel or volcanic rockbiological filter that is sown with marshplants through which pre-treated residualwaters flow horizontally or vertically.Bacteria responsible for organic matterdegradation use the filtering bed surfaceto form a bacterial film.

The use of bio-filters requires previoustreatment processes ensuring aneffective removal of suspended solids, inorder to prevent plugging of the filteringbed. These preliminary processes mayconsist of a grid, followed by a sand trapand settling units, such as an imhoff tankor a septic tank.

The biological treatment within thefiltering bed is optional, meaning that inthe filter’s body there are areas with, andalso without, oxygen. Plant roots allow airflow from the atmosphere to the subsoil,

Bio-filters

Section of a Horizontal Flow Biological Filter

Source: CENTA, 2004

which adds oxygen to the water

increasing the number of aerobicbacteria capable of decomposing theorganic matter. Water coming from the

imhoff tank or septic chamber isuniformly distributed over the wholefiltering bed surface and infiltrates into

the water collection area. The water-filterfeeding interval must be wide enough toallow full water infiltration and air filling

into all the empty bed spaces.Once the biofilter has been installed andis under proper operation, it can have a

long life span due to the balancebetween plant growth and death andbacterial mass reproduction.

The plants to be sown may be selectedbased on the type of contaminant thatwill be reduced in residual waters.

Effectiveness of platanillo, zacate taiwan,reed and tule has been shown.

The use of bio-filters requires previous treatment processes ensuring aneffective removal of suspended solids, in order to prevent plugging of thefiltering bed.

12

Macrophyte

Pretreated waterdistribution

channel

90 c

Coarse volcanic rock(2" – 4")

Coarse volcanic rock(2" – 4")

Bed surfaceWater level

Slope: 0-1%

Compacted clay impermeablelayer, B = 0.2 m

Volcanic rock filtering bed(0.5 – 15 mm)

Flexiblehose

Collectionbox

Treated water heading toreceiving body or agriculturalirrigation area

! Imhoff tank

! Bio-filter

Silting zone: hydraulic retention time = 1.5 hours atmaximum flow. Digestion zone: 70 liters perequivalent inhabitant (extraction of sludge every sixmonths).

Required surface: 5 m2 per equivalent inhabitant.

The following is a series of designreference values developed for warmclimates at the Carrion de los Céspedes

Experimental Plant, Andalucía (CENTA,2004):


13

Advantages

! The system can operate without energy consumption.! Lack of damages due to the lack of electromechanical

equipment.! Easy to operate.! Perfect integration in rural areas.! Vegetal biomass production (50 to 70 tons of dry

matter/hectare year).

Disadvantages

! A considerably largearea is needed for itsimplementation.

! Primary treatmentgenerates sludge.

Investment and operation costs

The table below shows an example ofinvestment and operation andmaintenance costs of plants built inCentral America. In general, thosesystems serving 1,000 or more peoplehave a cost ranging from US$ 30 to 60

Investment, operation and maintenance costs in Central American plants

Plant and location

Planta Salinas Grandes.Nicaragua

Planta Villa Bosco Monje.Masaya, Nicaragua

Planta San José LasFlores. El Salvador

Planta Teupasenti.Honduras

Planta Chichigalpa.Nicaragua

Equivalentinhabitants

300

1,000

1,365

2,812

8,753

Investment cost(US$/inhabitant)

81.20

42.00

50.20

32.80

45.70

Operation andmaintenance cost

(US$/inhabitant/month)

0.166

0.024

0.01

0.023

per person. In operation terms, the pilotplant of Masaya needs US$ 4 annuallyper person. In the plant of La Providencia,the larger number of people connectedreduced the cost to US$ 1.75 annuallyper person.


Operation and maintenance activitiesare simple and low cost in everytreatment stage.

! Grid and sand trap: weeklyremoval of coarse solids andsettled matter, by using a shoveland a wheelbarrow.

! Imhoff tank: surface scum removalonce a month by using a shoveland a wheelbarrow, and sludgeremoval once a year though theinstalled drainage pipe.

! Bio-filter: cutting of surface plantswith a machete, depending ontheir growth cycle. Replacementof the first meter of the filteringbed when a superficial water flowis noted (every two or threeyears).

References:- CIEMA-UNI, Proyecto ASTEC.

Vidal Cáceres:[email protected]

- CENTA – Junta de Andalucía,España. Planta Experimental deCarrión de los Céspedes(www.plantacarrion-pecc.com)

Ecologic sanitation is a new approach tosanitation services. It revolves aroundfour principles: recycle human excreta,prevent contamination instead of trying tocontrol it once water and soil have beencontaminated, preserve water resources,and close the nutrient cycle whenrecycled human excreta is used foragricultural purposes. The utilization ofthis type of latrine, both in periurbanareas of cities like Mexico D.F. and smalltowns, is currently in pilot phase.

Compost or Ecologic Latrine with Separate Urinal


Compost or ecologic latrines isolatehuman excreta from urine. Dehydratedexcreta may be used subsequently asfertilizer. The latrine consists of a toilet or“Turkish toilet” with a urinal at the front,which is linked to a receptacle through ahose, in order to convert it into fertilizer –due to its high nitrogen content andalmost inexistent presence of germs as aresult of its high acidity- or to pour it into

an absorbing well. The superstructureand toilet or “Turkish toilet” are built overtwo chambers which are usedalternatively to facilitate organic matterdegradation.

The ecologic latrine can be built insidehouses or in backyards.

Some criteria that must be consideredwhen implementing ecological latrineprojects are:

Advantages

! It does not require orcontaminate water.

! Soil improvement is achieved.! Urine can be used as

fertilizer.! It is appropriate in areas

where there is a risk ofcontaminating undergroundwater bodies.

! It is appropriate for soilsdifficult to dig (rocky orsandy).

Disadvantages

! Its cost is higher thanthat of a ventilated dry pitlatrine or a pour-flushlatrine due to theconstruction of twoalternating chambers.

! Urine may be isolatedand treated for its finaldisposal.

! After every use, ashes,dried sand or vegetalmaterial must be added.

The latrine consists of a toilet or “Turkish toilet” with a urinal at the front, whichis linked to a receptacle through a hose, in order to convert it into fertilizer –due to its high nitrogen content and almost inexistent presence of germs as aresult of its high acidity- or to pour it into an absorbing well.

14

Compost or ecologic latrine

Socio-Cultural Criteria. Considerationmust be given to family practices as towater management and excrementdisposal, including anal cleaningpractices.

Technical Criteria. For an adequateoperation, the following aspects must beconsidered:

! Excrement is placed in one of thetwo chambers and, after everyuse, it is necessary to addapproximately half a cup of sand –three quarters of sand and two ofashes or lime- in order that theinside of the chamber is dried andhas a level of acidity (pH) higherthan nine.

! When the chamber under use isabout to get full, the deposit has tobe covered with a layer of driedsand and the toilet must be placedin the empty chamber. The fullchamber must be totally coveredwith earth in order to continue withthe transformation of organicmatter into harmless matter . Oncethe two chambers are full, thesettling chamber must be emptied.

! It is advisable to have a latrineincluding a urinal to prevent from

dampening the inside of thechamber.

! To reuse urine as fertilizer, youcan dissolve it in water in a ratioof one to ten.

The latrine superstructure must meetminimum requirements in terms of size,ventilation, lighting and cleanliness.

Financial Criteria. Family’s monetarycontribution is critical to ensure a realand sustainable use of services.

References:- Sanitation Connection (www.sanicon.net)- Sarar Transformación SC. Ron Sawyer: [email protected] CENCA. Juan Carlos Calizaya: [email protected]

Sanitary Service. The provision oflatrines must be the result of a sanitaryeducation process which must startbefore the project implementation andcontinue after its conclusion.


The investment cost of ecologicallatrines is higher than that of dry latrinesor pour-flush latrines. Its operation andmaintenance are under the full

responsibility of users.


15

The findings, interpretations, and conclusions expressed are entirely those of the author and should not be attributed in any mannerto The World Bank, to its affiliated organizations, or to members of its Board of Executive Directors or the companies they represent.

Design adaptation by Fabiola Pérez-Albela 420 6881Photography by WSP-LAC

April 2005

WSP MISSION:To help the poor gain sustainedaccess to improved water and sanitationservices.

WSP FUNDING PARTNERS:The Governments of Australia,Belgium, Canada, Denmark, Germany,Italy, Japan, Luxembourg,the Netherlands, Norway, Sweden,Switzerland, and the United Kingdom,the United Nations DevelopmentProgramme, and The World Bank.

Acknowledgements:This publication of WSP- LAC was madepossible by generous contribution fromthe Swiss Agency for Development andCooperation (SDC) and the PanAmerican Center for Sanitary Engineeringand Environmental Sciences (CEPIS) ofthe Panamerican Health Organization(PAHO).

Prepared by:Alfonso Alvéstegui, consultant to theWorld Bank Water and SanitationProgram.

Contributed with their review:CEPIS: Ricardo Rojas.WSP-LAC: Francois Brikke, Rafael Vera,Oscar Castillo, Jorge Luis McGregor,and Beatriz Schippner.

Latin America and the Caribbean RegionWorld Bank Office, Lima.Alvarez Calderón No. 185,San Isidro, Lima 27, Perú.

Phone: (511) 615-0685Fax: (511) 615-0689E-mail: [email protected]: http://www.wsp.org

ABOUT THE SERIES:

WSP Field Notes describe andanalyze projects and activities inwater and sanitation that providelessons for sector leaders,administrators, and individualstackling the water and sanitationchallenges in urban and ruralareas. The criteria for selection ofstories included in this series arelarge scale impact, demonstrablesustainability, good costrecovery, replicable conditions,and leadership.

analytical report of the international symposium ... · analytical report of the international...

Documents