N° 85 - EID

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1. Assainissement dans la parcelle et quantification des boues de vidanges dans la ville de Yaoundé au Cameroun

Marie Mbang ; Emmanuel Ngnikam ; Boniface Efon ; Pierre Meukam ; Stéphane Fokou.

This study aims to describe the onsite sanitation and the quantification of faecal sludge in the city of Yaoundé. The city of Yaoundé, The population of Yaoundé City is about 3.1 million inhabitants in 2018 , will reach 4.7 million in 2030 with an average annual growth rate of 3.5%. The city of Yaoundé is dominated by an autonomous sanitation system which is used by 99% of households. Domestic wastewater of the city is mainly dealt through on-site sanitation systems represented by septic tanks, traditional pit latrines, ventilated improved pit latrines, etc A survey was carried out among 1100 households in the city of Yaoundé. The choice of household to be surveyed was made according to the stratified sample method. It is reviewed, the methods of quantification of existing used sludge, in order to choose a method adapted to the context of the city of Yaoundé. Several criteria are analyzed to access to the sludge produced by households: the existence or not of roads, their state of deterioration, the types of sanitation structure, the position of the structure in relation to the waterways, etc. Among the methods for quantifying the sludge explored, we found that "the specific production method" is more adapted in the context. But this method has been revised in order to integrate the analyzing elements on the accessibility of the facilities. The application of the method used has been done on 120 pit emptying during two months (june and july 2018). The […]

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2. Etat de la contamination en éléments traces des sédiments du Lac du barrage hydroélectrique de Nangbéto (Togo)

Koudjo Adje ; Kamilou Ouro-Sama ; Hodabalo Dheoulaba SOLITOKE ; Gnon Tanouayi ; Sadikou AGBERE ; Tchaa Esso-Essinam BADASSAN ; Housseni AHOUDI ; Kissao GNANDI.

The Nangbéto hydroelectric dam lake, which is a spillway for agricultural input residues, urban and industrial effluents present in the Mono basin, is exposed to all forms of pollution. The aim of this work is to estimate the content of seven trace elements present in the sediments of the aforementioned lake in order to assess the ecological risk incurred by the aquatic biocenosis and therefore by man. Forty-two sediment samples (21 per season) are realized in different areas of the Lake. Cd, Pb, Ni, Cu, Cr, As and Hg are measured out in the sediments by the flame atomic absorption spectrophotometer in these pre-mineralized samples. The results show average contents varying from the lowest level 0.04 mg / kg for Hg to the highest 12.15 mg / kg for Cu in the rainy season and from 0.03 mg / kg for Hg and for As to 9.14 mg/kg for Cu in the dry season. All of these values are below Canadian sediment quality standards. The strongest average geoaccumulation indices (Igeo) are obtained for Pb with values less than 2. The mean values of the contamination factor (FC) are less than 1. The mean indices of contamination (Im) are less than 2, threshold d 'an onset of polymetallic contamination. The ecological risk (Ri) in relation to the contamination of the sediments of the Lake with trace elements is low in any season (Ri <40) and this implies a low risk of contamination of the biocenosis. However, the present study only deals with metallic trace elements. It does not take into […]

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3. Implémentation de la pré-collecte participative dans la gestion durable des déchets solides ménagers : cas de l’arrondissement de Douala V au Cameroun.

Paul Fabrice Nguema ; Cédric TSOBGHO ; Zakari-Mohamadou MOUNIR.

The main objective of this study in the district of Douala V is to set up participatory pre-collection of household solid waste which, by protecting the environment, promotes the recovery of this waste. More specifically, the aim was to make an inventory of solid waste management, to raise awareness of households on participatory pre-collection, to describe the technical organization of the service and to evaluate the parameters of financial analysis for a pre-collection activity. To do this, available documents, direct observations, interviews and survey form were used. The main results of this study showed that the daily production or ratio of one inhabitant of Douala V is 1.05kg/hab/jour; the annual production is estimated at 363,870 tons. The low collection rate of about 23% was observed. With regard to household sensitization, 43% of the households surveyed are willing to pay for the pre-collection service and 52% are against and 5% are uninformed. The provisional financial analysis is based on one year; the investment cost is estimated at 3 327 400 CFA (5079 €). Overall, it appears that the solid waste collection rate in Douala V is below average, so it appears that pre-collection and recovery of household solid waste have a major role to play in the solid waste management system.

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4. Impacts socio-economiques de l’exploitation artisanale du sable sanaga dans la localite de nkol’ossananga (Yaounde, Cameroun) : vers une exploitation semi-mecanisée

William Happi Tientcheu ; Clautaire Ekengoue ; Rodrigue Lele ; Duluora Oluchukwu ; Benoit Messanga ; Armand Dongmo.

This paper presents the impacts of Nkol’Ossananga sand harvesting on social live and local economy based on field investigations and data analysis. Laboratory analysis of sand samples from the site has shown that the cleanliness of the Nkol’Ossananga sand nears 100%. This means that Nkol’Ossananga sand is pure and clean, most appropriate for house constructions and building engineering. The activity produces incomes to all actors of the chain value and government. Incomes generated are used by artisans to build their houses, buy some electronic devices, and take care of their families or to capitalize in their business investigation. In spite of the positive impacts presumed, Nkol’Ossananga sand harvesting also stands as the origin of many negative impacts including cultural brewing, delinquency, precocious abandon of studies and abandon of agriculture. The exploitation is done with rudimentary tools and poor technics thereby exposing artisans to several risks and illnesses. For sustainable exploitation, a mechanized operation has to be implemented. This kind of exploitation is the one that will improve the working conditions, increase production and incomes of workers as similar as that of government, and also reduces negative environmental impacts. Key words: Nkol’Ossananga sand, rudimentary tools and poor technics, incomes, negative impacts, sustainable exploitation, mechanized operation.

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5. Modélisation géochimique du comportement à la lixiviation des mâchefers d'incinération de déchets non dangereux

Ola Hammoud ; Denise Blanc ; Maria Lupsea-Toader ; Christine De Brauer.

Mineral trace elements (MTE) constitute an environmental restriction on the recycling of municipal solid waste incineration-bottom ash (MSWI-BA). The study of the speciation of MTE and the factors that control their release allows to predict their behavior under different environmental conditions and, consequently, suggest different actions to expand the management of MSWI-BA.A geochemical modeling led to a better understanding of the speciation of MTE. In this study, target elements were barium, copper, lead, nickel and zinc and the factors that control their release were identified.The results show that the leaching of metals as a function of pH mainly depends on the mineralogical phases. On the other hand, the organic matter has an influence in the leaching of MTE (for Ni, Cu and Pb notably); organic matter presents adsorbent or complexation properties.

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