Evaluation of bioadditive effectiveness at reducing sludge accumulation and E. coli in latrine systems in informal settlements in Lebanon

As protracted humanitarian emergencies are increasing, effective fecal sludge management solutions are needed to prevent disease spread. One fecal sludge management solution often promoted is adding bioadditives to reduce fecal sludge volume. However, scientific evidence documenting bioadditive effectiveness is weak. In this study, we evaluated the effectiveness of Sanipit® bioadditive in latrine containment systems in Syrian informal settlements in Lebanon with and without bioadditive. Systems were connected to flush latrines, and were three watertight holding tanks and a soak pit in series. Each week for 28 weeks, we measured sludge volume, E. coli concentration, and odor/fly presence in systems with and without bioadditives. Monthly, we conducted household surveys. Data from 21 systems were analyzed, with no statistical differences in sludge volume and E. coli concentration between systems (p > 0.05), and <12 % difference in reporting 'no odor'. We found Sanipit® bioadditive had no significant influence on sludge accumulation, E. coli concentration, or odor. Additionally, due to flooding and/or maintenance needs, only four systems remained operational throughout the 28-week study. Our work highlights the difficulties in conducting programs and research in protracted humanitarian contexts, and the need to focus on improved design, construction, and operation of sanitation infrastructure and services in protracted humanitarian settings.