The aim of this study was to assess on-site sanitation facilities in Yaounde on the basis of the eight proposed indicators of hygienic safety, sustainability and functionality of the Millennium Development Goals (MDG) target 7 definitions of improve sanitation. Information were collected on the design of toilet facilities, management and functionality through a semi-structured interview and observations of 602 randomly selected toilet facilities in 22 different urban settlements of Yaounde. In addition, information about education and socioeconomic status of householders, management and functionality of toilet facilities and health status of the users were collected. The results revealed several methods of excreta disposal and noted that approximately 3 % of households had no latrine and practiced open defecation. It also showed that 79% of latrines were covered at the top with concrete slabs while 69% with ground lined below floors. Households that lacked proper toilet facilities frequently suffered from orally transmitted sanitation-related diseases, with higher prevalence recorded in rainy seasons. This study recommends improvement in the management of sanitation facilities in some settlements of Yaounde in order to guarantee adequate sanitation in a healthy environment.
Les écoulements et les transferts de matières à travers les sols et sous-sols sont des processus qui impactent les ressources en eau. Ainsi, la restauration des milieux dégradés participe à la préservation de la qualité de la ressource. Afin de contribuer à la décontamination des sols pollués par phytoremédiation - technique de dépollution basée sur l’action des plantes en association avec les micro-organismes du sol - des inventaires floristiques de sites potentiellement pollués et non pollués (témoins) par les hydrocarbures ont été réalisés dans quatre villes du Cameroun. Sur la base d'indicateurs floristiques, six espèces ont été sélectionnées, et leurs capacités phytoremédiatrices testées dans un sol pollué par du fioul à 82,5 mL∙kg‑1 de sol pendant 150 jours en présence de trois modalités : Tn - sols non pollués plantés (6), To - sols pollués non plantés (3) et Tp - sols pollués plantés (18). La biodiversité des sites pollués (106 espèces, 76 genres et 30 familles) est moins élevée que celle des témoins (166 espèces, 125 genres et 50 familles). Les espèces les plus fréquentes (Fri > 10 %) et abondantes (7 % < A < 10 %) sur les sites potentiellement pollués sont dominées par 15 espèces tropicales; parmi lesquelles, Eleusine indica (L.) Gaertn., Cynodon dactylon (L.) Pers., Alternanthera sessilis (L.) R. Br. ex DC†, Commelinpa benghalensis L., Cleome ciliata Schum. et Thonn., et Asystasia gangetica (L.) T. Anderson, sont utilisées dans des essais de phytoremédiation des sols contaminés au fioul domestique. Seules trois de ces espèces, notamment E. indica, C. dactylon et A. sessilis ont pu survivre et se développer. Contrairement à A. sessilis, E. indica et C. dactylon ne présentent pas de différence significative pour les paramètres de croissance considérés entre les modalités Tn et Tp. Les espèces E. indica et C. dactylon seraient donc plus tolérantes au fioul domestique que l’espèce A. sessilis.Flows and transfers of materials through soils and subsoils are processes that impact water resources. Thus the restoration of degraded areas contributes to the preservation of the quality of the resource. In order to contribute to the decontamination of polluted soil, phytoremediation (a clean-up technique based on the action of plants in association with soil microorganisms), floristic surveys of potentially polluted and unpolluted (control) sites by hydrocarbons were carried out in four cities of Cameroon. On the basis of floristic indicators, six species were selected and their phytoremediation capacities tested in a soil polluted by fuel oil at 82.5 mL∙kg‑1 of soil for 150 d in the presence of three modalities: Tn - unpolluted soil planted (6), To - unplanted polluted soils (3) and Tp - polluted soil planted (18). The biodiversity of polluted sites (106 species, 76 genera and 30 families) was lower than the controls (166 species, 125 genera and 50 families). The most frequent species (Fri > 10%) and most abundant (7% < A < 10%) on potentially polluted sites were dominated by 15 tropical species;...
To address the soil–plant transfer modelling of 13 US-EPA Polycyclic Aromatic Hydrocarbons (PAHs), a mechanistic model—MM_19—has been developed based on the fugacity concept. For that, the Mackay_97 model has been improved in terms of reconsidering the losses related to the transport and transformation mechanisms taking place in the compartments—roots and aboveground shoots—of the three short-life species (Eleusine indica, Cynodon dactylon and Alternanthera sessilis). Model input parameters consist of both experimental and literature data, including the initial soil and air PAHs content, flowrates, PAHs physico-chemical properties, retention times and transport half-lives of PAHs inside plant species. Using in situ weather data and Penman’s law, xylem flows were estimated as the evapotranspiration for each plant. Model calibration was performed using a Generalized Reduced Gradient (GRG) nonlinear optimization solver method. Sensitivity analysis showed that the phloem flow was the most sensitive among all tested parameters. According to the Nash–Sutcliffe efficiency (NSE), the MM_19 model is more efficient than the Mackay_97 model for all three plant species. Finally, the impact of PAHs physico-chemical parameters on their sol-plant transfer was discussed in terms of slight, intermediate and high molecules weight. The NSE values showed that the MM_19 model is more efficient than the Mackay_97 model. Indeed, comparisons between experimental and simulated results in the MM_19 model showed similarities for each compartment of the plant species. Thus, the MM_19 model can be used to predict the soil–plant transfer of organic pollutants.
Faecal sludge (FS) management is a challenging problem in low-income countries where the majority of the urban population relies on on-site sanitation systems. The design of treatment plants relies on accurate knowledge on FS quantities and characteristics. Due to the lack of information on the quality and quantity of FS in the Cameroonian context, this study aims at evaluating the quantity and the quality of FS produced at the city scale by mechanical trucks at the dumping site of "Bois des singes" in Douala. Quantification was done through enumeration of emptying trucks and emptying truck capacities during one-week period while in the laboratory, analyses of composite samples were performed by the determination of physico-chemical, bacteriological and parasitological parameters in samples according to the standard protocols. Results on the quantification of FS in the city of Douala revealed that the weekly volume of faecal sludge dumped in natural environment at "Bois de singe" is estimated at about 2,890 m 3 with an average of 50 discharges per day by mechanical emptying trucks. Concerning the characterization of FS samples, FS exhibited high strength because of its higher concentration of organic, bacterial and helminth eggs loads. Therefore, there is need for proper health and environmental protection measures to prevent threats due to dumping of untreated faecal sludge into the environment after on-site sanitation technologies emptying by the construction of a treatment plant.
The removal of pathogens in irrigation water is of great importance in developing countries. Indeed, wastewater generally reused for agriculture in countries such as Cameroon is associated with health and environmental concerns. Recent studies have shown a strong disinfectant action of the natural coagulant from the seeds of Moringa oleifera. These findings have raised the question whether or not they can be used to polish effluents from natural systems treating faecal sludge. This paper deals with trials carried out to investigate the effect of these extracts in reducing faecal indicators from initially treated faecal sludge leachate. Bacteriological and physico-chemical parameters were used to determine the optimum conditions and assess treatment efficacy. Settling time of 3 h at a concentration of extracts between 267 and 333 mg/L permitted to reduce Escherichia coli and faecal coliforms from 4.85 to 3.92 ulog (86.74%) and from 5.75 to 4.87 ulog (86.39%) respectively with 1 ulog equal to 90%. For the same settling time and at a concentration of 333 mg/L, faecal streptococci were removed from 6.40 to 5.67 ulog (81.33%). This level of removal suggests that this natural coagulant cannot be used alone for disinfection of heavily loaded effluent. Further investigations are therefore still needed to fulfil the Cameroon and WHO guidelines for safe reuse in agriculture.
This study examines quality and variability of FS collected in Yaounde City. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) were applied for the description of FS data obtained in the context of Yaounde (Cameroon). Almost 13 parameters for the appreciation of the FS characteristics (temperature, pH, electric conductivity, salinity, COD, BOD 5 , NH 4 + , TKN, TS, TVS, TSS, water content and total helminth eggs) were measured in 53 different samples originated from various on-sanitation systems found around the town represented by septic tanks, traditional latrines, ventilated improved pit latrines and piped equipped latrines located all around the town. FS samples were classified into 9 clusters with 72.91% of variation within the samples of the same cluster and 27.09% of variation between clusters. PCA of the whole data set indicated about 78% of the total variance with the first component accounting for 28.38% of the total variance and significantly correlated with COD, BOD 5 , NH 4 + , TKN, TS and total helminth eggs. The second component accounting for 18.54% of the total variance correlated with electric conductivity, salinity and TVS. We found that the quality of FS is significantly different (p< 0.05) between groups of latrines. The p-values obtained after the Kruskall Wallis test were 0.03, 0.02, 0.01, 0.05 and 0.002 respectively for the parameters salinity, TKN, DCO, TSS and Water content. On the base of this study, it can be concluded that PCA and HCA could be helpful for the representation and interpretation of high variable FS quality data produced in urban and rural area of developing countries.
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