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Asustainability assessment tool has been developed to assistin the selection of an appropriate combination of pre-treatment and fi ltration technologies. T e tool assesses

each technologys applicability to the communitys characteristicsand requirements.

It also facilitates the participatory involvement of the community,which helps identify its ability to operate and maintain technologies,and gives it a sense of ownership of the project.

T e tool was developed as part of an Engineers Without Bordersproject in enganan, a rural community in the Karengasem regionof Bali, Indonesia, located in one of the poorest and driest areas onthe island. Most of the communitys water comes from the Batu

Asah spring, but this source is unreliable and varies depending uponthe season and crop cycle, with severe shortages occurring whena dry crop cycle coincides with the dry season. Other availablesources include dug bores and other springs, but these generallyhave poor accessibility and produce an unreliable quantity andquality of water. As a result, there are times in the year where thereis insuffi cient water of a suitable quality to meet the basic require-ments of the community.

Engineers Without Borderss project aims to extract water from amore reliable source and improve water quality through a combina-tion of pre-treatment, fi ltration and household treatment technolo-gies. T e project also plans to improve the management capabilities

Choosing the right technologiesby Nathan Cocks and Dr Raj Kurup

A sustainability assessment tool, designed as part of a development project in Indonesia,helps select the appropriate combination of water pre-treatment and fi ltrationtechnologies.

Villagers in Tenganan must walk for hours to bring water to their homes. PHOTO: IAN CUNNINGHAM/EWB

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of Pengelola Sarana Air Bersih, the organisation responsible for theoperation and management of the water supply.

T e sustainability assessment tool was developed in three mainsteps: selecting appropriate water treatment technologies for assess-ment; developing sustainability assessment criteria; and using thecriteria to evaluate the selected technologies.

T e technologies chosen for assessment were those that met thecommunity constraints of the project. T ese constraints includedno use of mechanical equipment or chemicals; low capital, operating

and maintenance costs; and minimal maintenance requirements.T e pre-treatment technologies which fulfi lled these criteria were: primary sedimentation dynamic gravel fi ltration

upfl ow gravel fi ltration in layers upfl ow gravel fi ltration in series coagulation, fl occulation and sedimentation using hydraulic

mixing devices and natural coagulants.Downfl ow and horizontal fl ow roughing fi ltration were alsoconsidered, but were not assessed because upfl ow gravel fi ltrationwas technically and economically preferable.

T e fi ltration technologies which met the constraints were slowsand fi ltration and reed bed treatment systems.

Rather than assessing these technologies individually, the selectedtechnologies were assessed as part of a number of water treatmentsystems, which included all possible combinations of pre-treatmentand fi ltration technologies, as well as each of the selected fi ltration

Work being done on the communitys water supply system. PHOTO: IAN CUNNINGHAM/EWB

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technologies without a pre-treatment step.Sustainability assessment criteria were then developed to assess

such water treatment systems based on a range of social, environ-mental, economic and technical factors deemed by the authors toaff ect the sustainability of a water treatment facility

T e data required to assess the selected technologies using these

criteria were predominantly collected through a literature reviewand engineering design calculations, but were also acquired throughstakeholder consultation, water and soil sampling and laboratoryanalysis, and hydraulic modelling.

T e collected data, sustainability assessment criteria and selectedwater treatment technologies were then integrated to form thesustainability assessment tool. T e tool was developed using aVisual Basic-enhanced Excel spreadsheet to facilitate a simple andinteractive user interface.

Once a combination of pre-treatment and fi ltration technolo-gies is selected, the tool uses the collected data to assess the watertreatment systems ability to address the criteria. For each criterion,it displays a quantitative and/or qualitative output. If any criterion

is not met, the combination of technologies is deemed inappropri-ate for implementation. However, if the criterion relating to thewater treatment systems ability to produce an appropriate waterquality is the only criterion which was not fulfi lled, the evaluated

water treatment system is inferred to be appropriate so long as anymodelled water quality parameters in excess concentrations in theeffl uent could be treated by household scale treatment processes.

For enganan, the sustainability assessment tool concludedthat reed bed treatment systems would be inappropriate giventheir high capital, operation and maintenance costs and land area

requirements. T e coagulation, fl occulation and sedimentationtechnology was determined to be technically impractical and pos-sibly diffi cult for the community to operate and maintain. T ecosts associated with the combination of an upfl ow gravel fi lter inseries and slow sand fi lter were found to be beyond the communitysfi nancial capacity.

T e viable options were found to be slow sand fi ltration witheither no pre-treatment or pre-treatment via primary sedimenta-tion, dynamic gravel fi ltration or upfl ow gravel fi ltration in layers.However, slow sand fi ltration alone may not be appropriate giventhe fl uctuations in water quality that are hypothesised to occur be-tween the wet and dry seasons in enganan. Further water qualitysampling and testing is required to test this hypothesis.

Moreover, although the selection of the most appropriate watertreatment technologies will assist in the sustainable implementationof a water treatment facility in enganan, there are other factorswhich need to be taken into consideration in the project. It is im-

Members of the Pengelola Sarana Air Bersih water management organisation at work. PHOTO: IAN CUNNINGHAM/EWB

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portant that the enganan community is involved in the decisionmaking processes of the project to assist in giving them a senseof ownership of the project and identify their capacity buildingrequirements. Engineers Without Borders must also ensure that,once its involvement in the project is fi nished, the community hasthe capacity to operate and maintain the implemented system, aswell as to plan and construct their own projects in the future. Ad-ditionally, pilot plants of potential water treatment technologiesshould be implemented to study their performance and act as usefultools for community education.

T ese actions will assist in ensuring the technical, social, eco-nomic, and environmental sustainability of implemented water

treatment technologies in not only enganan, but in other com-munities as well. T is will improve public health and economicdevelopment in these regions and inherently, enhance their qualityof life.

With some modifi cations, the sustainability assessment tool forselection of water treatment technology could be used by otherdevelopment agencies such as the World Bank, AusAID and theAsian Development Bank as well as non-government organisationsthat work in the water treatment sector.

Nathan Cocks is a recent graduate of the University of WA, completing a bachelorof environmental engineering with fi rst class honours. He developed the tool aspart of his honours thesis in collaboration with Engineers Without Borders lastyear.

Dr Raj Kurup, director of Perth-based consultancy Environmental EngineersInternational, supervised the thesis as an adjunct professor at the School ofEnvironmental Systems Engineering at the University of WA.

An earlier phase of the Tenganan Water Supply Project was described in theDecember 2007 issue ofWater Engineering Australia.

Construction of a pilot sand fi ltration plant. PHOTO: IAN CUNNINGHAM/EWB