| Environnement, ingénierie & développement |  |
N°81 - septembre 2019
1. Éditorial n°81 Déchets Sciences et Techniques
2. Influence chimique et minéralogique des sédiments de dragage portuaire dans le cadre de leur valorisation dans la fabrication des briques
This work is part of the development of alternative solutions for better management of dredging sediments or cleaning. The work carried out as part of this work focuses on the valorization of marine sediments from Bethioua port. The mineralogical properties of a brick slip from a brickyard and the brick slip made of marine sediments from the Bethioua port, Oran (Algeria) were studied. The bricks made from the Bethioua port sediment at the laboratory scale have mechanical performances similar to the reference bricks with a substitution rate of 5 % but with a low temperature (600°C instead of 900°C). The mineralogical study of the samples was compared before and after heat treatment for a temperature of 600°C and 900°C and for a cooking time of 24 hours. After heat treatment, quartz and calcite have been slightly diminished and remain as main crystalline components. An absence of kaolinite and dolomite was observed for the samples studied at a temperature of 600°C. At the temperature of 900°C there was appearance of dolomite for brick slip. The results of this work show that we can valorize the marine sediments of the Bethioua port in the manufacture of bricks and have a higher resistance with a temperature of 600°C than that of the brick of reference to 900°C.
3. Note technique : performance d’une station d’épuration dans l’élimination de la pollution carbonée d’effluents de brasserie
This study is focused on wastewater treatment using activated sludge in a brewery. It aims in controlling the efficiency of the step and enhancing its performance by oxygenation of effluents in buffer basin. Experiments were performed 23 weeks. From the 17th week, three oxyjets were installed in the buffer pond. pH, Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) were considered to raw wastewater “EE” and treated effluents “ES” analysis. The removal rates of DBO5 and COD were estimated. Brewery effluents, which are generally basic, contain biodegradable organic pollutants (DBO/DCO>0.3). Their oxygenation in the buffer pool promotes biological activities and increases the purification efficiency.
4. L’analyse coûts-bénéfices, un outil d’aide à la décision pour le développement approprié/équilibré de la filière déchet
The planning of waste management on a territory is a responsibility generally assumed by the municipalities. From household’s production to final treatment, waste follows a long process divided into several interdependent links (pre-collection / collection / recovery / burial).Like for any public service, the choices made in the development of the sector have repercussions that impact the entire urban space (health / environment / social / welfare/ economic activities). These are the externalities induced by the service, which may be positive or negative.In addition, there are many constraints that the municipalities have to face when planning the service, particularly related to the budgetary issue. Municipalities in Developing Countries (DCs) are subject to strong pressure because they have to meet their responsibilities despite their limited budgetary capacity. So, it is necessary that they have a visibility on the choices that they operate.In this sense, the Cost-Benefit Analysis is an interesting answer because it is a method to analyze and compare different development scenarios of a sector, while taking into account the externalities induced by the choices made.By translating all externalities into economic value, the Cost-Benefit Analysis is a tool for public decision-making. It makes it possible to orient the municipality towards optimum choices taking into account all the constraints on their territories.It is thanks to the results of this method that the […]
5. Réduction des risques professionnels liés à la pré-collecte des déchets municipaux dans les pays en développement : proposition d’approches adaptées à partir du cas de Lomé, Togo
Several risks exist in waste management. These risks are caused by the nature of waste, treatment processes and work organization. This study, carried out in three pre-collection companies in Lomé showed that workers are exposed to several risks, the three main ones being physical injuries, musculoskeletal disorders and exposure to organic dust and micro-organisms. These risks are due to the permanent contact of workers with the waste and to this work entirely manual. They are accentuated by the ignorance of the workers in terms of risks associated with their activities and the insufficient resources of the pre-collection companies to provide the workers with adequate equipment. The risk reduction measures taken by these structures essentially consist of the provision of personal protective equipment and agents. This equipment is often inadequate and poorly used. Only 6% of staff report regular wear. Risk reduction is effective when they are attacked at source, through integration, into a coherent set of technology and work organization and actors are trained and sensitized.
6. Evaluation du peuplement du phytoplancton dans les bassins d’une station d’épuration des eaux usées en milieu hospitalier (Centre hospitalier régional de Daloa, Côte d’Ivoire)
The quality of the phytoplankton community in the basins that composed a microphyte natural lagoon station gives an indication on its proper functioning. So, the algal flora of water from three (3) basins of the wastewater treatment station of the Regional Hospital Center of Daloa (Côte d’Ivoire) was inventoried, using water samples taken from each basin. The phytoplankton of the different samples were observed under an optical microscope. Similarly, the component of phytoplankton, the density and the planktonic index of each basin were determined. It’s appeared that the community of phytoplankton from the basins was estimated at 63 taxa grouped into 8 classes, 5 phyla. The Cyanobacteria and Chlorophyceae are more diversified. The planktonic index showed that the basins are under an eutrophic state due to a high density of Cyanobacteria, which are indicators of pollution during the study period. In addition, the results revealed a similarity between the basins about the phytoplankton flora inventoried. But, this similarity is more marked (76.1%) between the anaerobic basin (basin 1) and the maturation or aerobic basin (basin 3). This is contrary to the normal functioning of the wastewater treatment station.