| Environnement, ingénierie & développement |  |
N°70 - novembre 2015
1. Valorisation des coques d’anacarde par pyrolyse au Bénin
Faced to difficulties to energy access and management of waste from the processing of cashew nuts in Benin, the shells stored in cashew nuts processing plants are directly used as fuel. They are therefore burned in kilns to provide the energy required to produce the heat for embrittlement of nuts, steaming and drying almonds. This non controlled combustion generates significant pollution because CNSL, substance contained in the shells, produces abundant and acrid smoke irritating to eyes. To overcome this problem, we have constructed in Benin two pyrolysis plants on the basis of a reactor designed by CEFREPADE and RON-GEAD. Those reactors have been used in Benin for energy recovery from cashew nut shells. This experiment of promotion of cashew nuts showed that the pyrolysis reactor used can be able to produce gaseous energy of approximately 82% of the hull mass processed and produces about 18% of charcoal. Furthermore, on the energy point of view, the recovered gas corresponds to 74% of the energy of the raw material, while the obtained charcoal (18% of raw material) corresponds to 26% of total energy of fed raw material.
2. Éditorial n°70 Déchets Sciences et Techniques
Depuis sa création, la revue DST a souhaité publier des articles apportant une ouverture internationale à la communauté scientifique et technique francophone du monde des déchets. Cette volonté est consolidée aujourd’hui par le partenariat établi avec Re-Sources, plateforme internationale pour l’amélioration de la gestion des déchets solides dans les pays en développement (voir présentation ci-après). Dans le cadre de ce partenariat, la revue DST publiera régulièrement des articles issus de travaux de la plateforme, de type articles de recherche, retours d’expérience ou notes techniques.
3. Essai de traitement des lixiviats par UASB : cas de la ville de Kasba Tadla
The objective of this study is to present the physicochemical characteristics of the fresh leachate household wastes at the city dump in Kasba Tadla in Morocco (Figure 1) and to make test a UASB treatment Technique (Upflow Anaerobic Sludge Blanket). According to the finding obtained during this study we have managed to show that the household wastes of the city of Kasba Tadla are always on the increase. The production of these waste are of the order of 11 787 ton during the year 2013, that is, 0.27 ton per person every year. This waste consists essentially of organic matter (74%), the paper (3%), plastic (9%), metal (1%) and glass (0.5%). The quantities of leachate produced monthly at the city of Kasba Tadla vary between a maximum of 131 m3 during august 2013 and a minimum of 22 m3 during December 2013, whose average is of the order of 79 m3 per month. The physico-chemical analysis of leachate of the city of Kasba Tadla shows a high concentration of organic matter (COD at about 26 720 (mgO2/l)) and high acidity (pH = 4,49), hence the importance of the treatment of these effluents through effective and adaptable technical of climatic conditions of the area like the technique of UASB technology, before being discharged directly into the environment. The results of the tests of leachate treatment by UASB technique allowed us to have a 94% reduction of COD and a passage to neutral pH (pH = 6.87). The results show the success of the leachate treatment by UASB technology in the […]
4. Analyse synthétique des retours d’expérience sur les techniques de compostage dans les pays en développement
Established in 2013, the Re-Source platform aims to boost the activities of material and energy recovery from waste in Africa and the Caribbean. It seeks to promote good practices, develop training modules and diffuse technical and operational recommendations. In this objective, the group publishes synthetic feedback analysis documentsThis article reports feedback analyses related to the implementation of composting techniques in developing countries. Several units in operation in Africa and Haiti have been monitored by Re-Sources partners. The feedback analysis includes compost quality, nature of treated waste, monitoring parameters (temperature, moisture, air supply, grain size, C / N) and the different process stages such as sorting, grinding, hot fermentation and ripening, sifting, packaging and storage. The article gives some design elements, summarizes the most common problems and solutions and provides discussions on the interest of the development of composting in developing countries and recommendations related to technical and operational issues to ensure compost quality and minimize all environmental impacts.
5. Ecailles de poissons : nouveau support de biomasse dans les bioréacteurs a lit mobile pour le traitement des effluents des laiteries
This study focuses on the biological treatment of organic pollution load of effluents dairies. It proposes a new method. i.e. The use of fish scales Diplodus sargus species, as a solid support for colonization of suspended biomass in the bioreactor moving bed in order to improve the properties and quality of clearance. The results of monitoring the parameters of pollution control (pH, COD, MS, total nitrogen) are promising. Finally the amount of scales necessary has been optimized for economic and ecological reasons.
6. Etude expérimentale du traitement par évaporation forcée des lixiviats des déchets ménagers. Cas de la ville de Kasbah Tadla
The aim of our work is the development of an evaporation technique for the treatment of leachate from household waste in the city of Kasba Tadla to avoid rejection permanently in nature. taking into account the characteristics of the selected site which has a warm climate with temperatures that exceed 50 °C during the summer period we favored a forced evaporation processing mode. several models have been tested, the alternatives given on the position of the evaporation pans relative to the ground, coverage evaporation pans by glass plates and their angle of inclination and the presence or absence of systems agitation and ventilation. The tests were used to develop a final evaporation model forced with glass plates inclined with a stirring system of leachate. forced evaporation of leachate testing have helped reduce the time of evaporation of leachate by 50% approximately relative to natural evaporation and 30% compared to evaporation with plates of horizontal glass. the power evaporating of this technique from a value of 0,37 mm/day to reach a value of 1,5 mm/day during the winter period. the model developed shows evaporation performance and effectiveness for the treatment of leachate so it stands out as alterative techniques for the treatment of leachate.