Beyond Anecdotes to Numbers: Statistical Analysis of Fecal Sludge Management Disparities in Dhaka’s Urban Gradient

Urbanization in Dhaka has led to differences in fecal sludge management (FSM) methods between urban (Mirpur) and semi-urban (Savar) areas. This research investigates how urbanization and user perceptions influence FSM practices using structured household survey data (n = 394) on toilets, containment systems, desludging frequency, service accessibility, and satisfaction. Statistical methods (correlation and two-way ANOVA) uncovered relationships among infrastructure, behavior, and perception, whereas laboratory-measured biochemical data helped in investigating the influence of retention time on sludge quality. The findings showed that Mirpur residents had larger containment volumes, more frequent desludging, and much higher satisfaction levels (mean = 4.2) than those in Savar (mean = 3.1). Tank size (r = 0.70), willingness to pay (r = 0.60), and accessibility (r = 0.53) were strongly correlated with satisfaction. According to biochemical studies, Savar’s sludge contained much higher TS, TSS, NH4–N, and pH but lower VS, COD, and TN, suggesting longer anaerobic retention leading to more stabilization. Urbanization has a positive impact on FSM service performance, service accessibility, and user perceptions, while semi-urban areas remain constrained by infrastructure and awareness gaps. Implementing decentralized treatment, planned desludging, and community-inclusive FSM planning is necessary for equitable sanitation and progress towards SDG 6.2.