The efficacy of fecal sludge treatment technologies and resource recovery: a systematic review and meta-analysis in Sub-Saharan Africa

Fecal sludge (FS) management in sub-Saharan Africa (SSA) faces financial, technical, and logistical barriers. Despite rapid urbanization, onsite sanitation (OSS) systems remain the primary option for many households, yet often encounter operational challenges across the FS chain, from emptying to disposal, underscoring the need for effective interventions. A systematic review of 93 studies was conducted; 53.8% addressed both treatment and resource recovery, while 20.04% focused exclusively on treatment efficiency. The majority of research was concentrated in Uganda and Burkina Faso, each accounting for 18% of the studies, followed by Kenya at 11%. Treatment outcomes demonstrated significant reductions in Escherichia coli (E. coli) and five-day biochemical oxygen demand (BOD₅), with pooled effect sizes of 1.06 log CFU/100 mL (95% confidence interval [CI]: 0.34 to 1.78) and 181.40 mg/L (95% CI: 131.6 to 231.3), respectively. However, chemical oxygen demand (COD) removal was not statistically significant, with a mean of 69.97 mg/L (95% CI: –20.8 to 160.8). Substantial heterogeneity was observed (I²: 98.6% for BOD₅; 97.2% for COD), indicating significant differences in performance. These findings highlight ongoing limitations in scaling FS treatment technologies and emphasize the urgent need for stakeholder and interdisciplinary collaboration to promote sustainable FS management and resource recovery in SSA.