Gestão de lamas fecais no contexto das Cidades Moçambicanas: desafios e oportunidades

Abstract

The current study was conducted with the objective of identifying potential opportunities, challenges and deficiencies in the fecal sludge management service chain (containment, emptying, transport, treatment, disposal or reuse) with emphasis on the entrepreneurial sector in mozambican cities. In relation to the containment, an estimation of the domestic production of fecal sludge was conducted for the total urban population and for thirteen (13) Mozambican cities, using as a basis the accumulation rates for onsite sanitation technologies for two (2) scenarios. It was found that it was possible to divide the cities into four (4) groups: A, B, C and D, according to the volume of fecal sludge produced and that the biggest producer would be Matola City. For the emptying and transport, an economic viability assessment using Cash-flow analysis was conducted for the private emptying and transport model and licensing model. It was found that it is possible, under optimistic circumstances, to achieve payback after 4 years and 1 month, considering the acquisition and operation of a 4m3 capacity vacuum truck. The use of fecal sludge transfer stations and decentralization of the treatment plants were identified as ways of reducing distance travelled for the operators, resulting in a reduction of costs for operators. Regarding biogas production, the estimation was conducted using production values from literature and considering that it would occur under sub-optimal conditions. The results obtained led to the conclusion that more advanced technologies such as septic tanks result in a reduced production of biogas. Therefore, cities such as Maputo, with the second highest production of domestic fecal sludge, does not produce high levels of biogas. Using as basis the capital costs, operational cost, revenue and volume of fertilizer produced per volume of fecal sludge produced it was determined that the best option for fertilizer production was Co-Composting, due to its higher revenue and fertilizer production per volume of sludge treated. Although it requires established partnerships in order to obtain organic solid waste.