Sanitation access in urban areas of low-income countries is provided through unstandardized onsite technologies containing accumulated faecal sludge. The demand for infrastructure to manage faecal sludge is increasing, however, no reliable method exists to estimate total accumulated quantities and qualities (Q&Q) This proposed approach averages out complexities to estimate conditions at a centralized to semi-centralized scale required for management and treatment technology solutions, as opposed to previous approaches evaluating what happens in individual containments. Empirical data, demographic data, and questionnaires were used in Kampala, Uganda to estimate total faecal sludge accumulation in the city, resulting in 270 L/cap∙year for pit latrines and 280 L/cap∙year for septic tanks. Septic tank sludge was more dilute than pit latrine sludge, however, public toilet was not a distinguishing factor. Non-household sources of sludge represent a significant fraction of the total and have different characteristics than household-level sludge. Income level, water connection, black water only, solid waste, number of users, containment volume, emptying frequency, and truck size were predictors of sludge quality. Empirical relationships such as a COD:TS of 1.09 ± 0.56 could be used for more resource efficient sampling campaigns. Based on this approach, spatially available demographic, technical and environmental (SPA-DET) data and statistical relationships between parameters could be used to predict Q&Q of faecal sludge.

The majority of residents in low- and middle-income countries are served by onsite sanitation. Equitable access to sanitation, including emptying, collection, and transport services for the accumulation of faecal sludge remains a major challenge. Comprehensive information on service coverage by mechanical faecal sludge emptying service providers is lacking. The purpose of this study is to analyse the spatial distribution of service coverage and identify areas without faecal sludge emptying services in Kampala, Uganda. The study uses GIS (geographic information systems) as a tool to analyse real-time data of service providers based on GPS (global positioning system) units that were installed in a representative number of trucks. Of the total recorded 5653 emptying events, 27% were located outside Kampala city boundaries. Of those within Kampala city boundaries, 37% were classified as non-household customers. Areas without service provision accounted for 13% of the total area. Service provision normalised by population density revealed much greater service provision in medium- and high-income areas than low- and very low-income areas. The employed method provides a powerful tool to optimise faecal sludge management on a city-wide scale by increasing sustainability of the planning and decision-making process, increasing access to service provision and reducing faecal sludge transport times and costs.

Background: There is an unmet demand for community-scale fecal sludge treatment units (FSTUs) that serve communities of between 1,000 and 50,000 people and are able to operate in non-sewered and off-grid environments. An emerging industry standard for FSTUs includes as a key criteria energy independence in steady-state. Theoretically, there is sufficient thermal energy available in fecal sludge to provide the electrical power needed to run the FSTU. However, such a system had never been implemented. Methods: Biomass Controls has previously demonstrated the thermal treatment of fecal sludge using the Biogenic Refinery, a thermal FSTU deployed in three sites in India. In this article we describe testing where a Biogenic Refinery was paired with a thermal fluid heat exchanger and organic Rankine cycle generator to generate electrical power. Results: This Biogenic Refinery combined heat and power system generated sufficient electrical power to offset electrical parasitic loads in steady-state operation and produce a surplus of 1.2 kWe. Conclusions: The results of the study demonstrate that there is an excess of energy available and reliable mechanisms to generate electrical energy using an FSTU. Additional steps are necessary to transition to a true off-grid FSTU.

Light-absorbing carbonaceous (LAC) aerosols, particularly black carbon (BC), impact human health and climate, yet their sources are understudied in sub-Saharan Africa (SSA). This study presents the first source apportionment of LAC aerosols in Malawi, using locally determined Absorption Ångström Exponent (AAE) values for the first time in the SSA region. From May to August 2023, mobile monitoring covered eight settlements and highways, with stationary monitoring at two sites in Blantyre, Malawi's second-largest city. We used the MA200 micro-aethalometer to measure equivalent black carbon (eBC) as a BC proxy. Fossil fuel and biomass burning sources were distinguished based on locally determined AAE thresholds (1.63 for biomass and intermediate values indicating mix of both). Stationary monitoring revealed mean eBC levels of 4.1 ± 4.1 µg m^-³ in planned and 3.6 ± 2.6 µg m^-³ in unplanned settlements. Mobile monitoring showed spatial variations, with highways averaging 11.3 µg m^-³ and settlements mean ranging from 2.4 to 9.9 µg m^-³ eBC. Across settlements, biomass burning contributed 7 %-46 %, and fossil fuel combustion contributed 10 %-73 % of the total average eBC. The dominant eBC source between fossil fuel and biomass remained consistent across AAE values 1.21-1.37 for fossil fuel and 1.55-1.71 for biomass in sensitivity analysis, except in one settlement. Blantyre's eBC concentrations were comparable to some large and more populated urban cities in SSA, highlighting air quality challenges as the city urbanizes. The study emphasizes area-specific interventions and demonstrates a transferable source apportionment methodology for diverse urban contexts globally.