Multi-criteria analysis of options for urban sanitation and urban agriculture : case study in Accra (Ghana) and in Lima (Peru)

The Millennium Development Goal 7 (Ensure environmental sustainability), targetnumber 10 (halve, by 2015, the proportion of people without sustainable access to safedrinking water and basic sanitation) was introduced to encourage better solutions forwater and sanitation problems in developing countries.The SWITCH (Sustainable Water management Improves Tomorrows Cities' Health)project, funded by the European Union, aims to provide a sustainable, healthy, and safeurban water system to the people. This research was conducted under sub-theme 4.1 ofthe SWITCH project (eco-sanitation and decentralised wastewater management in anurban context). Accra in Ghana is a ""demonstration city"" in the SWITCH project; Limain Peru is a ""study city"".The objective of this research, which was limited to a desk top study, was to find out themost suitable sanitation system for urban and peri-urban areas (considering urbanagriculture) by using a multi-criteria analysis for comparing options. The case study wascarried out for urban and peri-urban areas in Accra (Ghana) and in Lima (Peru) with themain focus being on the Accra Metropolitan Assembly (AMA).The detailed analysis of sanitation systems was carried out for only Accra MetropolitanAssembly (AMA) because of the lack of available data for Lima. The available low-costsanitation options for AMA were short-listed to Option 1 (VIP-ventilated improved pitlatrine with down-stream processing) and Option 2 (UDD-urine diversion dehydrationtoilet, double vault with the down-stream processing). The population to be covered inthis design is 265,000 (this is 16% of the total population in AMA who engage in urbanagriculture) and the average household size is 4.5 (assume one toilet per household).In order to do a cost estimate, a concept design was developed for both options whichcovers all parts the sanitation system (i.e. toilet, transport from toilet to treatment plant/storage, treatment, transport from treatment plant/storage to farm, and reuse).According to the results of the financial model, the capital cost for Option 1 is € 27 percapita whereas the capital cost for Option 2 is € 39 per capita. The difference is mainlydue to costs in Part A (toilet), which is for € 354 for a VIP toilet and € 447 for a doublevaultUDD toilet. The NPV for Option 1 is € 10.5 million and for Option 2 it is € 13.5million (12% discount rate, 10 year project lifetime).A multi-criteria analysis (MCA) was carried out for both options to determine the bestsolution concerning social, technical, economic, environmental, health, and institutionalaspects by five experts in the field. From the analysis results, Option 2 (UDD) obtainedhigher scores than Option 1 and hence more desirable for AMA.The MCA used a number of indicators per aspect, which different for each part of thesystem; Weighting of each aspect could also be adjusted by the experts, who had to givescores from 1 to 5 for each indicator.It seems that Accra and Lima are not on the track to meet the MDG target for sanitationcoverage. The common constraints found for achievement of MDG targets are lack offinance (for people and government), lack of technology, lack of political will, andinsufficient land. Ecosan approaches could play a major role in achieving MDG targets(1, 2, 5, 8, 10, and 11) at lower cost than conventional sanitation systems.Main recommendations from this thesis include carrying out conceptual design withmore specific detail for every part of the sanitation components (Part A to E), costestimation with accurate quantities and costs especially for the toilet itself and urinestorage, and designing and cost estimation for greywater management systems