As Uganda works to transform itself into an industrialized, middle-income country in the coming decades, the country is faced with a number of problematic trends that could hinder this transition. High population growth and urbanization are quickly forcing small towns to deal with issues of limited space and the aesthetic conditions within sanitation systems, while declining soil fertility in surrounding rural areas calls into question the future nutritional security of the growing population. Ecological Sanitation (Eco-San) systems, which are designed to recover nutrients from human excreta, may help to address these trends. Improved sanitation coverage in Uganda is currently estimated to be 34%, with most people using either improved or unimproved pit latrines. Eco-San systems, especially Urine-Diverting Dry Toilets (UDDTs, also referred to as composting toilets), have been promoted in the country, but uptake has been slow. Additionally, while UDDTs generally treat human feces to a greater degree than pit latrines and composting toilets (another type of Eco-San system), concerns have been raised as to the inactivation of environmentally persistent pathogens, such as Ascaris lumbricoides eggs. This research focused on two potential solutions to the issues of effective promotion and Ascaris inactivation, evaluating them in the context of Kalisizo, a small town in southern Uganda. Demonstration facilities have been reported to effectively convince local stakeholders of the benefits and advantages of UDDTs, thereby increasing long-term uptake of the technology in the surrounding community. However, an unresolved question concerns whether these facilities should be installed in household or institutional settings. The initial effects of demonstration facilities constructed at local primary schools in Kalisizo were evaluated by assessing local knowledge and attitudes regarding UDDTs, both before installation and after several months of operation, through focus group discussions and key informant interviews. In general, this promotion strategy proved to be successful. After installation, students exhibited a marked increase in knowledge regarding these facilities and their benefits, and opinions were strongly positive. These changes were seen in users of the facilities as well as non-users, and students expressed clear acceptance of using the products of the toilets to fertilize crops. The introduction of an improved sanitation system at the schools also appears to have sparked other improvements related to sanitation and hygiene. In the future, it is likely that students will be compelling representatives for UDDTs within their households and communities. Regarding the treatment of persistent pathogens, previous work has demonstrated that the elevation of free ammonia levels to levels that can inactivate Ascaris eggs can be achieved through the urea addition. In this research, use of stored urine as an ammonia source for treatment of fecal products from UDDTs in Uganda was investigated. Mixtures of stored urine, fecal products from UDDTs, and wood ash were prepared, and treatment conditions (pH, temperature, ammonia concentration) were compared to the results of previous Ascaris inactivation studies to determine whether this strategy would be a feasible and effective treatment alternative. Results indicated that a volumetric mixture containing two parts stored urine and one part fecal products could provide 4-log1¬0 inactivation of Ascaris eggs after five months of indoor storage or after three months of outdoor storage. This strategy could improve the safety of recovered products while maintaining their agricultural value. Social acceptance of the treatment system appears to be possible with proper education efforts, and a cost comparison showed that this system may be more economically favorable than typical double-vault UDDTs.

Ce travail vise à proposer une solution d’assainissement durable, digne, sécurisante, accessible à tous, permettant de réduire les maladies à transmission hydrique, adaptée aux populations vivant dans des conditions précaires en zones rurales de pays en développement. Il contribue ainsi à la lutte contre la défécation à l’air libre, une des cibles de l’Objectif de Développement Durable n°6 concernant l’eau et l’assainissement. Le choix s’est porté sur des toilettes sèches individuelles à litière biomaîtrisée et un mode de gestion communautaire des résidus, en lien avec une association paysanne locale. La mise en place s’est faite avec un accompagnement scientifique qui a donné lieu aux travaux présentés ici. Dans un premier temps, nous avons opéré selon une approche participative, visant à s’assurer de l’adhésion des utilisateurs. Puis nous avons mené un programme scientifique pour identifier les conditions permettant l’hygiénisation des résidus traités. Après 3 ans d’expérimentation, la filière d’assainissement mise en place est totalement adoptée par les ménages, qui apportent régulièrement leurs résidus sur le site de compostage. Une enquête a fait ressortir que les familles sont très satisfaites de ce mode d’assainissement à domicile et se sentent moins sujettes à des maladies féco-orales. Ces ménages se sont constitués en un groupe qui procède à présent à l’appui à la réplication. Les litières absorbantes utilisées, les résidus avant et après traitement par compostage ont été caractérisés. Des essais en pilotes ont permis de déterminer les conditions permettant de garantir une hygiénisation rapide, ce qui était un de nos principaux objectifs, afin de réduire les risques sanitaires. Nous sommes à présent à même de définir les « bonnes pratiques » pour que la filière d’assainissement par toilettes sèches à litière biomaîtrisée dans une zone rurale de pays en développement soit sûre et durable, sur les aspects sociaux, techniques, économiques, environnementaux et sanitaires. / This work aims at proposing a sustainable, dignified, safe, accessible to everyone sanitation solution, allowing to reduce water-borne diseases, adapted to populations living in precarious conditions in rural areas of developing countries. It thus contributes to the fight against open defecation, one of the targets of the Sustainable Development Goal n ° 6 concerning water and sanitation. The choice fell on individual dry toilets with biocontrolled litter and a way of community management of residues, in connection with a local peasant association. The implementation was done with a scientific accompaniment which gave rise to the work presented here. Firstly, we operated according to a participatory approach, aiming to ensure the adhesion of the users. Then we conducted a scientific program to identify the conditions allowing the sanitizing of treated residues. After 3 years of experimentation, the sanitation system set up is totally adopted by the households, who regularly bring their residues to the composting site. One survey found that the families are very satisfied with this type of home sanitation and feel less prone to disease. These households have formed into a group that now supports replication of the system. The absorbent litter used, the residues before and after composting were characterized. Pilot tests were conducted to determine conditions to ensure rapid sanitizing, which was one of our main objectives, in order to reduce health risks. We are now in position to assure safe and sustainable practices so that the sanitation by dry biocontrolled litter toilets in rural areas of developing countries satisfy social; technical; economical, environmental and health criteria.