| Environnement, ingénierie & développement |  |
N°20 - 4ème trimestre 2000
1. Analyse de la décharge de déchets urbains de Marrakech relativement à l’évolution de la réglementation marocaine en matière d’environnement
For 11 years the city of Marrakech (Morocco) stockpiles his municipal solid wastes in an authorized landfill, the location of which was choosed from the criteria of urban planning and tourism. The analysis of the landfill according to the development of the environmental regulations in Morocco reveals two hazardous facts. The first fact is a great concentration of cupper and chromium in the landfill leachate explained by the wastes of cupper and leather from hand craft. The second fact is a risk that the wastes pile, estimated to a 0.6 MT weight and a 6 meter high, could slide because of the form of the landfill which is a slope bowl and due to an exceptionnal rainy event.
2. La roche artificielle: Une solution aux problèmes de la rétention, à l’échelle des temps géologiques, de métaux lourds issus de l’activité anthropique
The thermal treatment of glassy slags enriched in magnetite, with addition of metallic iron produce a hollocrystalline material. The main crystalline phases are hercynite, ulvospinel, fayalite and plagioclase. In this artificial rock, heavy metals are retained at geological time scale. This paper is a description of Tredi Therm process leading to inert slags.
3. Valorisation du phosphogypse de Tunisie en vue de son utilisation comme substituant au gypse naturel dans la fabrication du ciment
The substitution of natural gypsum by raw phosphogypsum residue in the preparation of industrial cement, causes a considerable delay in the cement hardening. The aim of this work is to identify, among the mineral and/or the organic compounds present in the phosphogypsum residue, those which cause such a delay and then to perform tests in order to remove or to decrease such impurities. Several tests have been carried out on the industrial cement by adding several mineral and organic compounds to the cement components, demonstrated that Phosphorus, Organic Matter and Fluorine, are the main and exclusive elements which causes a delay in the cement hardening. When they are present in significant amounts, those elements react with the cement particles, thus inhibiting their hydration, and causing by the same time a considerable delay in the cement hardening. Such result means, that in order to use successfully the phosphogypsum instead of natural gypsum in the preparation of industrial cement, the only need is to find out a method that would be able to remove (or decrease the amounts of) these elements from the phosphogypsum residue. Several tests have been carried out in order to remove (or decrease the amounts of) Phosphorus, Organic and Fluorine compounds, which were previously identified as compounds causing a considerable delay in the setting time of the cement. Treatments such as floatation, calcination, washing with sulfuric acid solution (up to 50% H2SO4) produce a good […]
4. Caractérisation de la mobilisation potentielle des polluants inorganiques dans les sols pollués : approche méthodologique
The specific objective of this study was to characterize the mobility of metals from contaminated soils through laboratory testing. A complete review of leaching/ extraction tests was carried cut in collaboration with the French normalization commetee Afnor). The selected leaching tests (sequential extractions, single extractions, column test and Compact Granular Leach Test) were performed on an artificially contaminated soil (fresh and aged) and an industrial soil containing As, Cr, Pb, Zn. The obtained results allowed to set up a methodology for assessing metal potential mobilisation from contaminated soils.
5. Éditorial n°20 Déchets Sciences et Techniques: La « problématique des boues d'épuration » : diluer ou concentrer ?
A l’évidence, la gestion des boues résiduaires de stations d’épuration urbaines est un des enjeux majeurs dans les stratégies de gestion et traitement des déchets.Tout d’abord sur le plan des tonnages, qui croissent de façon exponentielle en raison de la généralisation -très souhaitable – des stations d’épuration, dans les communes, même de taille modeste et les entreprises.Cette généralisation est parfois discutée : elle est indispensable pour éviter la pollution de nos rivières et cours d’eau. Ensuite, parce qu’elle pose un problème récurrent dans la gestion des déchets : faut-il confiner, concentrer ou diluer ?
6. Aperçu historique (jusqu’en 1950) du développement de l’incinération des ordures ménagères dans le monde
The survey brings out the preeminent position of Great Britain in the history and the development of this waste treatment technology, and its export even to distant countries. At first the United-States were enthusiastic over the British destructor, but then they got disappointed. This technology was adopted in Europe too – and adapted -, in particularly in Germany, the Netherlands, Switzerland and France. With the passing of time, the course of history seems singular: nowadays the MSW incineration rate is low in Great Britain and in the United-States, by comparison with European countries and with Japan. This history, which goes with fits and starts and with new promoting countries, leads to recommend ≪ caution ≫ towards prospective views concerning the waste treatment methods of the future.
7. Méthode de caractérisation des déchets ménagers : analyse sur produit sec
The French methodology for analysing MSW Modecom is described in two standards, AFNOR NF XP X 30-416 about sampling and NF XP X 30-408 about sorting and classification. A new method is proposed to improve the accuracy of the results and works conditions. The operator doesn't touch the waste before drying.The sample is taken according to the standard NF XP X 30-411 in the pit of a plant or according to the standard NF XP X 30-416 from a collection skip. After opening the plastic bags, the sample is divided in four, dried, sieved with a trommel at 100, 20 and 8 mm, then sorted manually on a dry feed in granularly parts. The result is independent of the operator.