| Environnement, ingénierie & développement |  |
N°61 - Juin 2012
1. Impact des activités humaines sur la dégradation de la qualité des sédiments de l’estuaire de Loukkos (Maroc)
The spatial and temporal variation of 6 trace metals levels (Fe, Zn, Cu, Cr, Pb and Cd) were studied in the sediments of the Loukkos river estuary in relation with various human activities of industrial, agricultural and domestic origin.The results obtained show that level of the station where the waste is discharged wastewater from the Larache city; there is a significant change in the values of principal elements (Cr and Pb). Indeed, the metal content of the sediments of these values reach particularly high near the main upstream (high agricultural activity) and downstream (domestic wastewater of the city and traffic) from the estuary. Nowadays, the limit for Cr and Pb exceeded the standard of the Domestic network Observation. This has confirmed by the index of contamination, the analysis of variance and the Principal Component Analysis practised.
2. Biotransformation des déchets d’abattoir en vue de leur valorisation dans l’alimentation animale
Slaughterhouse wastes (blood and rumen contents) were fermented by a pure culture of Lactobacillus plantarum. The product, before and after fermentation, underwent chemical and microbiological analysis. This fermentation has reduced the pH to 4.0 the final product (biostabilisat). The rate of protein (total nitrogen) has kept in the biostabilisat 22.9% DM against 24.6% DM in the untreated waste. Undesirable microbial populations have suffered a great reduction in fermentation processes: enterobacteriaceae, enterococci, staphylococci and clostridia are each at levels below 10 cfu/g. The biostabilisat is then used to substitute protein sources in the feed formula of three groups of five rats each. Three formulas are prepared from the biostabilisat and maize (V/V) 0% (control), 25% and 50%. We followed the food intake and growth rate of the animals for four weeks. The results obtained indicate that the incorporation of slaughterhouse waste to a rate of 50% yielded growth performance comparable to conventional formula.
3. Evaluation des impacts environnementaux d’un centre de stockage de déchets ménagers en activité sur la base de la caractérisation des flux de matière entrants et sortants : Application au site de Nkolfoulou, Yaoundé, Cameroun
This study evaluates the environmental and social impact of a landfill in the tropical humid zone in Africa. The different parameters analyzed are: the mass and characteristics of waste receive in the landfill, leachate generation and composition, methane production, and rainfall. The characteristics of the environment around the site are considered to approach environmental impacts, including impact monitoring is carried out upstream and downstream of the discharge point.A methodology for assessing flow in and out is proposed to allow whatever the nature and location of the dumpsite to assess the potential impacts of the waste disposal on the different environmental compartments.At the beginning of the study, Nkolfoulou landfill in Yaounde was selected. This had received 2.13 million tons of waste, of which 66% of the wet mass are made of biodegradable materials. Our study shows that the site generates an average of 450 m3 / day of leachate, only 54 m3 is collected and discharged into the river without any treatment. Impacts of these discharges are real on the surface water to the extent that the leachate is COD load (700 to 2500 mg/l) and BOD5 (400 to 700 mg / l) and to a lesser extent, however, heavy metal. We not the presence in this leachate, bacteria of fecal contamination and pathogens. The impact of the discharge of untreated leachate into the river is visible at a distance of 100 m downstream of the discharge point.The average potential methane production of waste […]
4. Etude expérimentale de l'incidence du niveau de démantèlement sur le taux de valorisation avant broyage des véhicules hors d'usage (VHU)
To identify key factors for improving the recovery rates of ELVs, ACYCLEA (PRAXY group) launched in 2009 the “OPTIVAL VHU” research program in collaboration with INSA Lyon. Experimental campaigns were conducted to compare different scenarios of deconstruction, with the support of ADEME. This article presents the first results obtained, which concern the material balances on the stages of depollution (cleanup) and dismantling. Results on the shredding stage and the analysis of other evaluation criteria will be published later.The identification and analysis of bibliographic data revealed that the average weight of ELVs increased significantly in the time period studied, from 910 kg in 1985 to nearly 970 kg in 1997. At the same time, the proportion of ferrous metals declined, partially offset by an increase in polymeric materials, while the proportions of non-ferrous metals appear stable with respect to the variability of the literature data and their uncertainties. The campaigns were done on samples of 90 ELVs. The average mass and age were evaluated at 989 kg / ELV and 14 years respectively. The mass of materials removed during cleanup operations was 3.6 + / 0.1 % of the mass of vehicles. The incidence of these operations on the rate of metal recycling is related to lead batteries and was about 1 % of the weight of ELVs. The contribution of the operations of deconstruction to the recovery rate is higher than that of previous operations. The experimental campaigns showed […]