Le bassin versant de l’Abiergué, localisé dans le périmètre urbain de Yaoundé entre 11°05’ et 11°25’ de longitude Est et entre 3°51’ et 3°54’ de latitude Nord connaît une importante activité maraîchère dans les bas fonds de Nkolbikok à Nkolbisson. Une étude démarrée en 2005 dans cette zone, a pour objectif principal de contribuer à la valorisation de cette activité tout en œuvrant à la réduction des risques induits (sanitaires et environnementaux). De nombreuses activités ont été développées suivant une démarche transdisciplinaire. Les conditions socio-économiques des acteurs impliqués dans cette filière ont été décrites. Les contraintes et les atouts liés au développement du maraîchage ont été relevés. Les eaux usées proviennent d’origines diverses (ménages, marché, centres de santé, …) et présentent des teneurs non négligeables en DBO5 (10 à 360 mg d’O2/l), DCO (15 à 601 mg d’O2/l), Coliformes fécaux (5025 UFC/100ml à 3 x 106 UFC/100ml), Streptocoques fécaux (1960 UFC/100ml à 138 000 UFC/100ml). Des taux variables de kystes de protozoaires (Entamoeba hystolitica et Giardia sp) et des œufs d’helminthes ont été décelés dans ces eaux. La réutilisation des eaux usées a pour corollaire la recrudescence de maladies hydriques telles que l’amibiase intestinale qui affecte aussi bien les acteurs engagés dans cette filière que la population en général indépendamment du sexe, de l’âge ou du statut social. De nombreuses pratiques et de nombreux comportements à risque concourent à la propagation de ces maladies hydriques.Malgré les risques de maladies hydriques, cette activité contribue considérablement à la sécurité alimentaire, au renforcement du potentiel économique, à l’aménagement de l’espace urbain, bref à l’amélioration des conditions et du cadre de vie des catégories d’acteurs engagés dans cette activité en particulier et des populations en général. Des actions économiquement viables, socialement acceptables et écologiquement durables sont à mettre en œuvre par l’Etat et les ONG afin de réduire les aspects négatifs et de consolider les aspects positifs de cette activité multifonctionnelle.

The effect of a continuous supply of a water extract of Moringa oleifera seeds (WEMOS) on the hydrolytic microbial population of biomass grown in mesophilic upflow anaerobic sludge blanket reactors treating domestic wastewater was investigated. The WEMOS‐treated sludge had seemingly a wider diversity, with enterobacter and klebsiella as dominant hydrolytic bacteria, compared with the control sludge. Additional tests indicated that various hydrolytic bacteria could degrade WEMOS. It appeared that a continuous supply of WEMOS to an anaerobic digester, treating domestic wastewater, increased the diversity of hydrolytic bacteria and therefore enhanced the biological start‐up of the reactor.

Water disinfection by photosensitization from bergamot oil shows (production of singulet oxygen) a complete inhibition of fecal coliforms present in water after one hour of exposition to the light. It is not the case for water kept in dark during two hours. The sensitivity of fecal enterococci (Gramþ) is higher than that of fecal coliforms (Gram-). This difference could be due to the constitution of their cellular membranes, those of fecal enterococci being deprived of polyliposaccharidic layer and easily damaged by singlet oxygen. No regrowth of both fecal coliforms and fecal enterococci was noticed in water treated with bergamot oil, exposed to the light during two hours and kept in the darkness during 24 h.

Safe drinking water access for rural populations in developing countries remains a challenge for a sustainable development, particularly in rural and periurban areas of Burkina Faso. The study aims to investigate the purifying capacity of Moringa oleifera defatted cake as compared to Moringa oleifera seed in the treatment of surface and well waters used for populations alimentation. A total of 90 water samples were collected in sterile glass bottles from 3 dams' water reservoirs, a river, and a large diameter well, respectively. The water samples were treated in triplicate with Moringa oleifera seed and defatted cake coagulants. At different settling time and coagulant concentration, turbidity and pH were measured to determine the optimal conditions and factors influencing treatment with regard to sampling source. Nine physicochemical parameters (turbidity, pH, nitrates, nitrites, calcium, magnesium, total hardness, organic matter and sulfates), three bacterial fecal pollution indicators (Escherichia coli, fecal Coliforms and fecal Streptococcus) and parasite cysts were monitored based on laboratory standard methods. Data were analyzed using the Student's t test and XLSTAT 7.5.2 statistical software. From the results obtained, for the same concentration of coagulant, settling time providing the lowest turbidity was significantly shorter (p < 0.0001) with Moringa oleifera cake than seed. Optimum settling time with Moringa oleifera cake was between 15-60 min versus 60-120 min, with Moringa oleifera seed. Both treatments significantly reduced minerals concentration in water excepted sulfates for which the concentration reversely increased. However, only Moringa oleifera cake treatment reduced organic matter content in all the water samples, while it increased with Moringa oleifera seed one (p < 0.0001). The reduction of microbial pollution indicators was 92%-100% with M. oleifera cake treatment and 84%-100% with M. oleifera seed one. Overall, for all water samples, Moringa oleifera cake treatment appeared more efficient in improving drinking water quality than the M. oleifera seed treatment.

In the present paper we investigated macrophyte community structure in 60 natural and impacted stream and river sites distributed throughout the Walloon river network. The objectives were to describe the distribution of macrophyte assemblages in relation to physico-chemical parameters of their environment and to assess the variability in ecological metrics within these watercourses. Two-way clustering allowed us to simultaneously assign sample units and species to groups by performing two separate cluster analyses. Indicator species analysis allowed us to assess the degree to which a species indicated a group, based on its constancy and distribution of abundance. Six end-groups were identified as a result of using twoway clustering and indicator species analysis techniques. Hygroamblystegium fluviatile, Chiloscyphus polyanthos and Lemanea fluviatilis were found to characterize acidic and low impacted streams and rivers (G1), while Ranunculus fluitans was found in all low impacted large streams (G2). Potamogeton pectinatus, proved to be more common in eutrophicated waters in the calcareous areas particularly in the ʺLoess low plateauxʺ region (G6).Cinclidotus riparius, Fissidens crassipes and Pellia endiviifolia, appeared in rivers situated in the Condroz region (G4), which was characterized by a high concentration of nitrogen.