Potential Economic and Environmental Benefits of Faecal Sludge Derived Compost and Char Briquettes: The case of Dar es Salaam, Tanzania

Abstract

The concept of resource recovery, particularly from waste has recently gained much attention and popularity. The aim of this study was to quantify the potential economic and environmental benefits of recovering nutrients and energy from faecal sludge (FS). The empirical data were collected from three unplanned settlements of Dar es Salaam City at Keko, Kipawa and Manzese. Two scenarios were developed to recover nutrients and energy. The estimations of potential amounts of compost and char briquettes were performed by using the resource value mapping (REVAMP) tool. Results from REVAMP indicated daily economic benefits across the study areas ranging between 680 and 950 USD for energy and up to 7,000 USD for nutrients recovered, based on the faecal sludge composition. In general, FS derived compost was found more profitable than FS derived briquettes. The analyzed environmental benefits include saving the estimated to 5 hectares of forest area from being cut when substituting the use of wood charcoal with FS-derived briquettes. Since the composting process resulted to be more profitable option between the two, this study recommends the adoption and scaling up. However, guidelines and standards should be developed for proper practices. Keywords: Faecal sludge; resource recovery; resource value mapping; briquettes; compost; economic benefits; environmental benefits