Material flow analysis as a tool for sustainable sanitation planning in developing countries: case study of Arba Minch, Ethiopia

Material Flow Analysis is a method that can be used to assess sanitation systems with regard to their environmental impacts. Modelling water and nutrients flows of the urban water, wastewater and waste system can highlight risks for environmental pollution and can help evaluating the potential for linking sanitation with resource recovery and agricultural production. This study presents the results of an analysis of nitrogen and phosphorus flows of Arba Minch town in South Ethiopia. The current situation is modelled and possible scenarios for upgrading the town's sanitation system are assessed. Two different scenarios for nutrient recovery are analysed. Scenario one includes co-composting municipal organic waste with faecal sludge from pit latrines and septic tanks as well as the use of compost in agriculture. The second scenario based on urine-diversion toilets includes application of urine as fertiliser and composting of faecal matter. In order to allow for variations in the rate of adoption, the model can simulate varying degrees of technology implementation. Thus, the impact of a step-wise or successive approach can be illustrated. The results show that significant amounts of plant nutrients can be provided by both options, co-composting and urine diversion.