Multi-Criteria Framework for Selection of City-Wide Sanitation Solutions in Coastal Towns in Northern Angola

In this paper, an expedited multi-criteria decision analysis framework, capable of tackling several dimensions for the choice of sanitation services, at an early planning stage is presented. The approach combines geographic information systems aided analysis for onsite solutions, with a multi-criteria decision analysis tool capable of suggesting and ranking several viable offsite treatment alternatives, according to the desired criteria. The framework was applied to four coastal cities in Northern Angola, one of the sub-Saharan countries of the west coast of Africa, thus obtaining an indication for city-wide solutions, as an aid to achieve the goal of ensuring full sanitation coverage in those four locations. It included possible onsite collection and storage interfaces, namely Ventilated Improved Pit latrines, fossa alterna, septic tanks or conventional sewer systems. The study also contributed to an informed decision regarding optimal offsite treatment facility type, namely based on dedicated or combined wastewater and faecal sludge treatment (co-treatment), as well as different options for locations and sanitation technologies. Alternatives were compared and ranked according to ten main criteria concerning social, economic, technological and environmental aspects. This work helped demonstrate the usefulness of decision-aiding tools in the multi-stakeholder and complex context of sanitation in a developing country.