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.

Grey water constitutes the largest fraction of domestic wastewater. It causes environmental sanitation and pollution problems if it is not managed well. If treated, grey water can be a resource for a variety of uses. A pilot system was constructed in February 2013 to treat grey water from a four-member household for sub-surface irrigation of local vegetables. A hydraulic loading rate (HLR) of 60 L m−2d−1 and an organic loading rate (OLR) of 519–1,580 g BOD5m−2d−1 were implemented on a multi-media filter of gravel, charcoal, geotextile and mulch (charcoal being the predominant layer) operated as a batched type-system, with a 36-hour retention time. The system was operated for 3 months, during which it showed remarkable removal efficiencies of 90.8 ± 5.4 and 96.1 ± 3.0% after 36 hours for chemical oxygen demand (COD) and biochemical oxygen demand (BOD), respectively, and 95 ± 3.1% for faecal coliforms (FC). The removal efficiencies at 36 hours, of total nitrogen (TN), total phosphorus (Tot-P), total suspended solids (TSS) and total dissolved solids (TDS) were 39.0, 30.1, 85.2 and 78.6%, respectively. Plant response to sub-surface irrigation with treated grey water was largely masked by rainy season and the effluent had a limited effect on the soil.

The design and management of onsite sanitation containments for faecal sludge (FS) in informal settlements presents significant public health and environmental challenges, exacerbated by limited data on sludge accumulation and quality. This study aimed to determine properties and accumulation rate of FS in pit latrines and septic tanks to improve sanitation design and management strategies. Fieldwork was conducted in 22 onsite containments (11 pit latrines and 11 septic tanks) in Kawempe Division, Kampala. The in-situ FS volume was measured using a Volaser device, while laboratory analyses determined key physico-chemical parameters, including total solids (TS), volatile solids (VS), and chemical oxygen demand (COD). The findings revealed median FS accumulation rates of 214 L/cap year for pit latrines and 348 L/cap year for septic tanks, with significant variability across different containment types. Correlation analysis showed a strong relationship between TS and VS (R² = 0.93), while TS and COD exhibited a moderate correlation (R² = 0.47). These insights suggest that TS can be a cost-effective proxy for VS estimation, reducing laboratory analysis costs in resource-limited settings. This study provides data for optimizing faecal sludge management (FSM), supporting the design of more efficient sanitation systems in high-density urban settlements. The findings contribute to improved sludge containment planning, desludging frequency estimation, and the selection of appropriate treatment technologies in similar contexts.